1
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Pan Z, Wu X, Bodi A, van Bokhoven JA, Hemberger P. Catalytic pyrolysis mechanism of lignin moieties driven by aldehyde, hydroxyl, methoxy, and allyl functionalization: the role of reactive quinone methide and ketene intermediates. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2024; 26:9899-9910. [PMID: 39219704 PMCID: PMC11363027 DOI: 10.1039/d4gc03143a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024]
Abstract
The catalytic pyrolysis of guaiacol-based lignin monomers, vanillin, syringol, and eugenol over commercial HZSM-5 has been investigated using operando Photoelectron Photoion Coincidence (PEPICO) spectroscopy to unveil the reaction mechanism by detecting reactive intermediates, such as quinone methides and ketenes, and products. Vanillin shares the decomposition mechanism with guaiacol due to prompt and efficient decarbonylation, which allows us to control this reaction leading to a phenol selectivity increase by switching to a faujasite catalyst and decreasing the Si/Al ratio. Syringol first demethylates to 3-methoxycatechol, which mainly dehydroxylates to o- and m-guaiacol. Ketene formation channels over HZSM-5 are less important here than for guaiacol or vanillin, but product distribution remains similar. C3 addition to guaiacol yields eugenol, which shows a more complex product distribution upon catalytic pyrolysis. By analogies to monomers with simplified functionalization, namely allylbenzene, 4-allylcatechol, and 4-methylcatechol, the eugenol chemistry could be fully resolved. Previously postulated reactive semi-quinone intermediates are detected spectroscopically, and their involvement opens alternative pathways to condensation and phenol formation. Allyl groups, produced by dehydroxylation of the β-O-4 bond, may not only decompose via C1/C2/C3 loss, but also cyclize to indene and its derivatives over HZSM-5. This comparably high reactivity leads to an unselective branching of the chemistry and to a complex product distribution, which is difficult to control. Indenes and naphthalenes are also prototypical coke precursors efficiently deactivating the catalyst. We rely on these mechanistic insights to discuss strategies to fine-tune process conditions to increase the selectivities of desired products by enhancing either vanillin and guaiacol or supressing eugenol yields from native lignin.
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Affiliation(s)
- Zeyou Pan
- Paul Scherrer Institute 5232 Villigen Switzerland
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich 8093 Zurich Switzerland
| | - Xiangkun Wu
- Paul Scherrer Institute 5232 Villigen Switzerland
| | - Andras Bodi
- Paul Scherrer Institute 5232 Villigen Switzerland
| | - Jeroen A van Bokhoven
- Paul Scherrer Institute 5232 Villigen Switzerland
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich 8093 Zurich Switzerland
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2
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Zhang Z, Li Q, Wu X, Bourmaud C, Vlachos DG, Luterbacher J, Bodi A, Hemberger P. A solution for 4-propylguaiacol hydrodeoxygenation without ring saturation. Nat Commun 2024; 15:6330. [PMID: 39068201 PMCID: PMC11283461 DOI: 10.1038/s41467-024-50724-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 07/15/2024] [Indexed: 07/30/2024] Open
Abstract
We investigate solvent effects in the hydrodeoxygenation of 4-propylguaiacol (4PG, 166 amu), a key lignin-derived monomer, over Ru/C catalyst by combined operando synchrotron photoelectron photoion coincidence (PEPICO) spectroscopy and molecular dynamics simulations. With and without isooctane co-feeding, ring-hydrogenated 2-methoxy-4-propylcyclohexanol (172 amu) is the first product, due to the favorable flat adsorption configuration of 4PG on the catalyst surface. In contrast, tetrahydrofuran (THF)-a polar aprotic solvent that is representative of those used for lignin solubilization and upgrading-strongly coordinates to the catalyst surface at the oxygen atom. This induces a local steric hindrance, blocking the flat adsorption of 4PG more effectively, as it needs more Ru sites than the tilted adsorption configuration revealed by molecular dynamics simulations. Therefore, THF suppresses benzene ring hydrogenation, favoring a demethoxylation route that yields 4-propylphenol (136 amu), followed by dehydroxylation to propylbenzene (120 amu). Solvent selection may provide new avenues for controlling catalytic selectivity.
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Affiliation(s)
- Zihao Zhang
- Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Qiang Li
- Catalysis Center for Energy Innovation, University of Delaware, 221 Academy St., Newark, DE, 19716, USA
| | - Xiangkun Wu
- Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Claire Bourmaud
- Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Station 6, Lausanne, 1015, Switzerland
| | - Dionisios G Vlachos
- Catalysis Center for Energy Innovation, University of Delaware, 221 Academy St., Newark, DE, 19716, USA.
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE, 19716, USA.
| | - Jeremy Luterbacher
- Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Station 6, Lausanne, 1015, Switzerland.
| | - Andras Bodi
- Paul Scherrer Institute, Villigen, 5232, Switzerland.
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3
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Karir G, Mendez-Vega E, Portela-Gonzalez A, Saraswat M, Sander W, Hemberger P. The elusive phenylethynyl radical and its cation: synthesis, electronic structure, and reactivity. Phys Chem Chem Phys 2024; 26:18256-18265. [PMID: 38904382 DOI: 10.1039/d4cp02129k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Alkynyl radicals and cations are crucial reactive intermediates in chemistry, but often evade direct detection. Herein, we report the direct observation of the phenylethynyl radical (C6H5CC˙) and its cation (C6H5CC+), which are two of the most reactive intermediates in organic chemistry. The radical is generated via pyrolysis of (bromoethynyl)benzene at temperatures above 1500 K and is characterized by photoion mass-selected threshold photoelectron spectroscopy (ms-TPES). Photoionization of the phenylethynyl radical yields the phenylethynyl cation, which has never been synthesized due to its extreme electrophilicity. Vibrationally-resolved ms-TPES assisted by ab initio calculations unveiled the complex electronic structure of the phenylethynyl cation, which appears at an adiabatic ionization energy (AIE) of 8.90 ± 0.05 eV and exhibits an uncommon triplet (3B1) ground state, while the closed-shell singlet (1A1) state lies just 2.8 kcal mol-1 (0.12 eV) higher in energy. The reactive phenylethynyl radical abstracts hydrogen to form ethynylbenzene (C6H5CCH) but also isomerizes via H-shift to the o-, m-, and p-ethynylphenyl isomers (C6H4CCH). These radicals are very reactive and undergo ring-opening followed by H-loss to form a mixture of C8H4 triynes, along with low yields of cyclic 3- and 4-ethynylbenzynes (C6H3CCH). At higher temperatures, dehydrogenation from the unbranched C8H4 triynes forms the linear tetraacetylene (C8H2), an astrochemically relevant polyyne.
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Affiliation(s)
- Ginny Karir
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Enrique Mendez-Vega
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | | | - Mayank Saraswat
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute (PSI), Villigen CH-5232, Switzerland.
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4
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Babayan M, Redekop E, Kokkonen E, Olsbye U, Huttula M, Urpelainen S. PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:841-850. [PMID: 38917019 PMCID: PMC11226177 DOI: 10.1107/s1600577524004405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 05/10/2024] [Indexed: 06/27/2024]
Abstract
The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts - zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors. However, GC is not suitable for the detection of highly reactive intermediates such as ketene or formaldehyde and is not suitable for kinetic studies under well defined low pressure conditions. Photoelectron-photoion coincidence (PEPICO) spectroscopy has emerged as a powerful analytical tool for unraveling complex compositions of catalytic effluents, but its availability is limited to a handful of facilities worldwide. Herein, PEPICO analysis of catalytic reactor effluents has been implemented at the FinEstBeAMS beamline of MAX IV Laboratory. The conversion of dimethyl ether (DME) on a zeolite catalyst (ZSM-5-MFI27) is used as a prototypical model reaction producing a wide distribution of hydrocarbon products. Since in zeolites methanol is quickly equilibrated with DME, this reaction can be used to probe vast sub-networks of the full MTH process, while eliminating or at least slowing down methanol-induced secondary reactions and catalyst deactivation. Quantitative discrimination of xylene isomers in the effluent stream is achieved by deconvoluting the coincidence photoelectron spectra.
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Affiliation(s)
- Morsal Babayan
- Nano and Molecular Systems Research UnitUniversity of OuluOuluFinland
| | - Evgeniy Redekop
- Department of Chemistry, Centre for Materials Science and Nanotechnology (SMN)University of OsloOsloNorway
| | | | - Unni Olsbye
- Department of Chemistry, Centre for Materials Science and Nanotechnology (SMN)University of OsloOsloNorway
| | - Marko Huttula
- Nano and Molecular Systems Research UnitUniversity of OuluOuluFinland
| | - Samuli Urpelainen
- Nano and Molecular Systems Research UnitUniversity of OuluOuluFinland
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5
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Kanayama K, Nakamura H, Maruta K, Bodi A, Hemberger P. Conformer-Specific Photoelectron Spectroscopy of Carbonic Acid: H 2CO 3. J Phys Chem Lett 2024; 15:2658-2664. [PMID: 38426443 PMCID: PMC10945571 DOI: 10.1021/acs.jpclett.4c00343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/02/2024]
Abstract
Carbonic acid (H2CO3) is a fundamental species in biological, ecological, and astronomical systems. However, its spectroscopic characterization is incomplete because of its reactive nature. The photoionization (PI) and the photoion mass-selected threshold photoelectron (ms-TPE) spectra of H2CO3 were obtained by utilizing vacuum ultraviolet (VUV) synchrotron radiation and double imaging photoelectron photoion coincidence spectroscopy. Two carbonic acid conformers, namely, cis-cis and cis-trans, were identified. Experimental adiabatic ionization energies (AIEs) of cis-cis and cis-trans H2CO3 were determined to be 11.27 ± 0.02 and 11.18 ± 0.03 eV, and the cation enthalpies of formation could be derived as ΔfH°0K = 485 ± 2 and 482 ± 3 kJ mol-1, respectively. The cis-cis conformer shows intense peaks in the ms-TPES that are assigned to the C=O/C-OH stretching mode, while the cis-trans conformer exhibits a long progression to which two C=O/C-OH stretching modes contribute. The TPE spectra allow for the sensitive and conformer-selective detection of carbonic acid in terrestrial experiments to better understand astrochemical reactions.
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Affiliation(s)
- Keisuke Kanayama
- Laboratory
for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute
of Fluid Science, Tohoku University 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
- Graduate
School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba, Sendai, Miyagi 980-8579, Japan
| | - Hisashi Nakamura
- Institute
of Fluid Science, Tohoku University 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Kaoru Maruta
- Institute
of Fluid Science, Tohoku University 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Andras Bodi
- Laboratory
for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Patrick Hemberger
- Laboratory
for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
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6
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Wagner MS, Peisert H, Chassé T, Hemberger P, Bettinger HF. Gas Phase Ionization Energy of Heptacene. J Phys Chem Lett 2024; 15:2332-2336. [PMID: 38386914 DOI: 10.1021/acs.jpclett.3c03580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The ionization energy is a fundamental property that is relevant to charge transport in organic semiconductors. We report adiabatic ionization energies (AIEs) of heptacene at 6.21 and 7.20 eV for the X̃+B2g and Ã+Au states, respectively, as the next larger member of the acene series using mass- and isomer-selective double imaging photoelectron photoion coincidence spectroscopy. The X̃+ state energy decreases monotonically with an increase in size within the homologous series of acenes and approaches an asymptotic limit [AIE(polyacene) = 5.94 ± 0.06 eV] based on a fit with an exponential decay function. As byproducts of heptacene formation from cycloreversion of diheptacenes, 5,18-, 7,16-, and 6,17-dihydroheptacene can be detected, and their AIE is similar to that of their largest acene subunit (anthracene and tetracene, respectively), in very good agreement with computational treatments.
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Affiliation(s)
- Marie S Wagner
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Institut für Physikalische und Theoretische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institut für Physikalische und Theoretische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institut für Physikalische und Theoretische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - Holger F Bettinger
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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7
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Saraswat M, Portela-Gonzalez A, Mendez-Vega E, Karir G, Sander W, Hemberger P. Photoelectron spectroscopic study of 2-naphthylnitrene and its thermal rearrangement to cyanoindenes. Phys Chem Chem Phys 2023; 25:31146-31152. [PMID: 37947458 DOI: 10.1039/d3cp04064j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
2-Cyanoindene has recently been identified in the interstellar medium, however current models cannot fully account for its formation pathways. Herein, we identify and characterize 2-naphthylnitrene, which is prone to rearrange to 2- and 3-cyanoindene, in the gas phase using photoion mass-selective threshold photoelectron spectroscopy (ms-TPES). The adiabatic ionization energies (AIE) of triplet nitrene (3A'') to the radical cation in its lowest-energy doublet X̃+(2A') and quartet ã+(4A') electronic states were determined to be 7.72 ± 0.02 and 8.64 ± 0.02 eV, respectively, leading to a doublet-quartet energy splitting (ΔED-Q) of 0.92 eV (88.8 kJ mol-1). A ring-contraction mechanism yields 3-cyanoindene, which is selectively formed under mild pyrolysis conditions (800 K), while the lowest-energy isomer, 2-cyanoindene, is also observed under harsh pyrolysis conditions at 1100 K. The isomer-selective assignment was rationalized by Franck-Condon spectral modeling and by measuring the AIEs at 8.64 ± 0.02 and 8.70 ± 0.02 eV for 2- and 3-cyanoindene, respectively, in good agreement with quantum chemical calculations.
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Affiliation(s)
- Mayank Saraswat
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | | | - Enrique Mendez-Vega
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Ginny Karir
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44780, Germany.
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut (PSI), Villigen CH-5232, Switzerland.
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8
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Saraswat M, Portela-Gonzalez A, Karir G, Mendez-Vega E, Sander W, Hemberger P. Thermal Decomposition of 2- and 4-Iodobenzyl Iodide Yields Fulvenallene and Ethynylcyclopentadienes: A Joint Threshold Photoelectron and Matrix Isolation Spectroscopic Study. J Phys Chem A 2023; 127:8574-8583. [PMID: 37734109 PMCID: PMC10591508 DOI: 10.1021/acs.jpca.3c04688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/06/2023] [Indexed: 09/23/2023]
Abstract
The thermal decomposition of 2- and 4-iodobenzyl iodide at high temperatures was investigated by mass-selective threshold photoelectron spectroscopy (ms-TPES) in the gas phase, as well as by matrix isolation infrared spectroscopy in cryogenic matrices. Scission of the benzylic C-I bond in the precursors at 850 K affords 2- and 4-iodobenzyl radicals (ortho- and para-IC6H4CH2•), respectively, in high yields. The adiabatic ionization energies of ortho-IC6H4CH2• to the X̃+(1A') and ã+(3A') cation states were determined to be 7.31 ± 0.01 and 8.78 ± 0.01 eV, whereas those of para-IC6H4CH2• were measured to be 7.17 ± 0.01 eV for X̃+(1A1) and 8.98 ± 0.01 eV for ã+(3A1). Vibrational frequencies of the ring breathing mode were measured to be 560 ± 80 and 240 ± 80 cm-1 for the X̃+(1A') and ã+(3A') cation states of ortho-IC6H4CH2•, respectively. At higher temperatures, subsequent aryl C-I cleavage takes place to form α,2- and α,4-didehydrotoluene diradicals, which rapidly undergo ring contraction to a stable product, fulvenallene. Nevertheless, the most intense vibrational bands of the elusive α,2- and α,4-didehydrotoluene diradicals were observed in the Ar matrices. In addition, high-energy and astrochemically relevant C7H6 isomers 1-, 2-, and 5-ethynylcyclopentadiene are observed at even higher pyrolysis temperatures along with fulvenallene. Complementary quantum chemical computations on the C7H6 potential energy surface predict a feasible reaction cascade at high temperatures from the diradicals to fulvenallene, supporting the experimental observations in both the gas phase and cryogenic matrices.
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Affiliation(s)
- Mayank Saraswat
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | | | - Ginny Karir
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Enrique Mendez-Vega
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Wolfram Sander
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Patrick Hemberger
- Laboratory
for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut (PSI), CH-5232 Villigen, Switzerland
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9
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Hemberger P, Pan Z, Wu X, Zhang Z, Kanayama K, Bodi A. Photoion Mass-Selected Threshold Photoelectron Spectroscopy to Detect Reactive Intermediates in Catalysis: From Instrumentation and Examples to Peculiarities and a Database. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:16751-16763. [PMID: 37670794 PMCID: PMC10476201 DOI: 10.1021/acs.jpcc.3c03120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 08/04/2023] [Indexed: 09/07/2023]
Abstract
Photoion mass-selected threshold photoelectron spectroscopy (ms-TPES) is a synchrotron-based, universal, sensitive, and multiplexed detection tool applied in the areas of catalysis, combustion, and gas-phase reactions. Isomer-selective vibrational fingerprints in the ms-TPES of stable and reactive intermediates allow for unequivocal assignment of spectral carriers. Case studies are presented on heterogeneous catalysis, revealing the role of ketenes in the methanol-to-olefins process, the catalytic pyrolysis mechanism of lignin model compounds, and the radical chemistry upon C-H activation in oxyhalogenation. These studies demonstrate the potential of ms-TPES as an analytical technique for elucidating complex reaction mechanisms. We examine the robustness of ms-TPES assignments and address sampling effects, especially the temperature dependence of ms-TPES due to rovibrational broadening. Data acquisition approaches and the Stark shift from the extraction field are also considered to arrive at general recommendations. Finally, the PhotoElectron PhotoIon Spectral Compendium (https://pepisco.psi.ch), a spectral database hosted at Paul Scherrer Institute to support assignment, is introduced.
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Affiliation(s)
| | - Zeyou Pan
- Paul
Scherrer Institute, Villigen 5232, Switzerland
| | - Xiangkun Wu
- Paul
Scherrer Institute, Villigen 5232, Switzerland
| | - Zihao Zhang
- Paul
Scherrer Institute, Villigen 5232, Switzerland
| | - Keisuke Kanayama
- Paul
Scherrer Institute, Villigen 5232, Switzerland
- Institute
of Fluid Science, Tohoku University 2-1-1 Katahira, Aoba, Sendai 980-8577, Miyagi, Japan
- Graduate
School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba, Sendai 980-8579, Miyagi, Japan
| | - Andras Bodi
- Paul
Scherrer Institute, Villigen 5232, Switzerland
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10
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Fischer I, Hemberger P. Photoelectron Photoion Coincidence Spectroscopy of Biradicals. Chemphyschem 2023; 24:e202300334. [PMID: 37325876 DOI: 10.1002/cphc.202300334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/17/2023]
Abstract
The electronic structure of biradicals is characterized by the presence of two unpaired electrons in degenerate or near-degenerate molecular orbitals. In particular, some of the most relevant species are highly reactive, difficult to generate cleanly and can only be studied in the gas phase or in matrices. Unveiling their electronic structure is, however, of paramount interest to understand their chemistry. Photoelectron photoion coincidence (PEPICO) spectroscopy is an excellent approach to explore the electronic states of biradicals, because it enables a direct correlation between the detected ions and electrons. This permits to extract unique vibrationally resolved photoion mass-selected threshold photoelectron spectra (ms-TPES) to obtain insight in the electronic structure of both the neutral and the cation. In this review we highlight most recent advances on the spectroscopy of biradicals and biradicaloids, utilizing PEPICO spectroscopy and vacuum ultraviolet (VUV) synchrotron radiation.
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Affiliation(s)
- Ingo Fischer
- Julius-Maximilians-Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Am Hubland, D-97074, Würzburg, Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut (PSI), CH-5232, Villigen, Switzerland
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11
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Xu X, Liu X, Zhang J, Liang L, Wen C, Li Y, Shen M, Wu Y, He X, Liu G, Xu X. Formation, migration, derivation, and generation mechanism of polycyclic aromatic hydrocarbons during frying. Food Chem 2023; 425:136485. [PMID: 37276667 DOI: 10.1016/j.foodchem.2023.136485] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/16/2023] [Accepted: 05/26/2023] [Indexed: 06/07/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and lipophilic, which can be found in frying system. This review summarized the formation, migration and derivation for PAHs, hypothesized the possible mechanism for PAHs generation during frying and presented the research prospects. Some factors like high oil consumption, high temperature, long time and oil rich in unsaturated fatty acids promoted the formation of PAHs and the presence of antioxidants inhibited the PAHs formation. The effect of proteins and carbohydrates in foods on the formation of PAHs is inconclusive. The formed PAHs were migrated into food and air. Moreover, some PAHs transformed into more toxic PAHs-derivatives during frying. The generation of PAHs may be related to low-barrier free radical-mediated reaction and the unsaturated hydrocarbons may be precursors of PAHs during frying. In future, the isotope tracer technology and on-line detection may be applied to discover intermediates and provide clues for studying PAHs generation mechanisms.
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Affiliation(s)
- Xiangxin Xu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Xiaofang Liu
- School of Tourism and Cuisine, Yangzhou University, Yangzhou 225127, China
| | - Jixian Zhang
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Li Liang
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Chaoting Wen
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Youdong Li
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Mengyu Shen
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Yinyin Wu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Xudong He
- Yangzhou Center for Food and Drug Control, Yangzhou 225009, China
| | - Guoyan Liu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China.
| | - Xin Xu
- College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China.
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12
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Abstract
Combustion is a reactive oxidation process that releases energy bound in chemical compounds used as fuels─energy that is needed for power generation, transportation, heating, and industrial purposes. Because of greenhouse gas and local pollutant emissions associated with fossil fuels, combustion science and applications are challenged to abandon conventional pathways and to adapt toward the demand of future carbon neutrality. For the design of efficient, low-emission processes, understanding the details of the relevant chemical transformations is essential. Comprehensive knowledge gained from decades of fossil-fuel combustion research includes general principles for establishing and validating reaction mechanisms and process models, relying on both theory and experiments with a suite of analytic monitoring and sensing techniques. Such knowledge can be advantageously applied and extended to configure, analyze, and control new systems using different, nonfossil, potentially zero-carbon fuels. Understanding the impact of combustion and its links with chemistry needs some background. The introduction therefore combines information on exemplary cultural and technological achievements using combustion and on nature and effects of combustion emissions. Subsequently, the methodology of combustion chemistry research is described. A major part is devoted to fuels, followed by a discussion of selected combustion applications, illustrating the chemical information needed for the future.
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Tuli LB, Goettl SJ, Turner AM, Howlader AH, Hemberger P, Wnuk SF, Guo T, Mebel AM, Kaiser RI. Gas phase synthesis of the C40 nano bowl C 40H 10. Nat Commun 2023; 14:1527. [PMID: 36934084 PMCID: PMC10024697 DOI: 10.1038/s41467-023-37058-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/27/2023] [Indexed: 03/20/2023] Open
Abstract
Nanobowls represent vital molecular building blocks of end-capped nanotubes and fullerenes detected in combustion systems and in deep space such as toward the planetary nebula TC-1, but their fundamental formation mechanisms have remained elusive. By merging molecular beam experiments with electronic structure calculations, we reveal a complex chain of reactions initiated through the gas-phase preparation of benzocorannulene (C24H12) via ring annulation of the corannulenyl radical (C20H9•) by vinylacetylene (C4H4) as identified isomer-selectively in situ via photoionization efficiency curves and photoion mass-selected threshold photoelectron spectra. In silico studies provided compelling evidence that the benzannulation mechanism can be expanded to pentabenzocorannulene (C40H20) followed by successive cyclodehydrogenation to the C40 nanobowl (C40H10) - a fundamental building block of buckminsterfullerene (C60). This high-temperature pathway opens up isomer-selective routes to nanobowls via resonantly stabilized free-radical intermediates and ring annulation in circumstellar envelopes of carbon stars and planetary nebulae as their descendants eventually altering our insights of the complex chemistry of carbon in our Galaxy.
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Affiliation(s)
- Lotefa B Tuli
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | - Shane J Goettl
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Andrew M Turner
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - A Hasan Howlader
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Patrick Hemberger
- Paul Scherrer Insitute, CH-5232, Villigen PSI, Villigen, Switzerland.
| | - Stanislaw F Wnuk
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | - Tianjian Guo
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Tianjin, 370001, PR China
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA.
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14
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Bodi A, Hafliðason A, Kvaran Á. Branching ratios in the dissociative photoionization of iodomethane by photoelectron photoion coincidence. Phys Chem Chem Phys 2023; 25:7383-7393. [PMID: 36826403 DOI: 10.1039/d2cp03339a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Iodomethane yields ten fragment ions after valence photoionization, in part by multiple dissociation pathways for each, thanks to a plethora of electronic states available in the parent ion as well as in the fragments. The comprehensive breakdown diagram from 11 eV to the double ionization onset, i.e., 26.7 eV, is recorded at high resolution using double imaging photoelectron photoion coincidence spectroscopy with synchrotron vacuum ultraviolet radiation. Based on fragment ion groupings, the changing branching ratios between these groups and between fragment ions within each group, as well as ancillary thermochemistry, we provide an overview of the dissociation pathways at play. Statistical and impulsive dissociations are identified using kinetic energy release analysis. Finally, a newly observed regime change is discussed in double ionization, whereby coincident H+ + I+ formation dominates over a 4 eV photon energy range, outcompeting the normally prevailing CH3+ + I+ channel.
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Affiliation(s)
- Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland.
| | - Arnar Hafliðason
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland
| | - Ágúst Kvaran
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland
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15
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Unraveling Radical and Oxygenate Routes in the Oxidative Dehydrogenation of Propane over Boron Nitride. J Am Chem Soc 2023; 145:7910-7917. [PMID: 36867720 PMCID: PMC10103127 DOI: 10.1021/jacs.2c12970] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Oxidative dehydrogenation of propane (ODHP) is an emerging technology to meet the global propylene demand with boron nitride (BN) catalysts likely to play a pivotal role. It is widely accepted that gas-phase chemistry plays a fundamental role in the BN-catalyzed ODHP. However, the mechanism remains elusive because short-lived intermediates are difficult to capture. We detect short-lived free radicals (CH3•, C3H5•) and reactive oxygenates, C2-4 ketenes and C2-3 enols, in ODHP over BN by operando synchrotron photoelectron photoion coincidence spectroscopy. In addition to a surface-catalyzed channel, we identify a gas-phase H-acceptor radical- and H-donor oxygenate-driven route, leading to olefin production. In this route, partially oxidized enols propagate into the gas phase, followed by dehydrogenation (and methylation) to form ketenes and finally yield olefins by decarbonylation. Quantum chemical calculations predict the >BO dangling site to be the source of free radicals in the process. More importantly, the easy desorption of oxygenates from the catalyst surface is key to prevent deep oxidation to CO2.
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16
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Wu X, Pan Z, Steglich M, Ascher P, Bodi A, Bjelić S, Hemberger P. A direct liquid sampling interface for photoelectron photoion coincidence spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:034103. [PMID: 37012765 DOI: 10.1063/5.0136665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/19/2023] [Indexed: 06/19/2023]
Abstract
We introduce an effective and flexible high vacuum interface to probe the liquid phase with photoelectron photoion coincidence (liq-PEPICO) spectroscopy at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source. The interface comprises a high-temperature sheath gas-driven vaporizer, which initially produces aerosols. The particles evaporate and form a molecular beam, which is skimmed and ionized by VUV radiation. The molecular beam is characterized using ion velocity map imaging, and the vaporization parameters of the liq-PEPICO source have been optimized to improve the detection sensitivity. Time-of-flight mass spectra and photoion mass-selected threshold photoelectron spectra (ms-TPES) were recorded for an ethanolic solution of 4-propylguaiacol, vanillin, and 4-hydroxybenzaldehyde (1 g/l of each). The ground state ms-TPES band of vanillin reproduces the reference, room-temperature spectrum well. The ms-TPES for 4-propylguaiacol and 4-hydroxybenzaldehyde are reported for the first time. Vertical ionization energies obtained by equation-of-motion calculations reproduce the photoelectron spectral features. We also investigated the aldol condensation dynamics of benzaldehyde with acetone using liq-PEPICO. Our direct sampling approach, thus, enables probing reactions at ambient pressure during classical synthesis procedures and microfluidic chip devices.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Zeyou Pan
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | | | | | - Andras Bodi
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Saša Bjelić
- Paul Scherrer Institute, 5232 Villigen, Switzerland
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17
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Schleier D, Gerlach M, Schaffner D, Mukhopadhyay DP, Hemberger P, Fischer I. Threshold photoelectron spectroscopy of trimethylborane and its pyrolysis products. Phys Chem Chem Phys 2023; 25:4511-4518. [PMID: 36445209 DOI: 10.1039/d2cp04513c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Trimethylborane (TMB) and its chemistry upon pyrolysis have been investigated by threshold photoelectron spectroscopy. TMB shows an unstructured spectrum and its adiabatic ionization energy (IEad) has been determined to be 9.93 ± 0.1 eV. Dissociative photoionization induces a methyl radical loss in TMB and the barrier to dissociation in the cation is measured to be 0.65 ± 0.1 eV. Upon pyrolysis methane loss dominates, leading to C2H5B, which can exist in five different isomeric structures. Quantum chemical calculations were used to investigate possible methane loss mechanisms as well as the isomerization pathways on the C2H5B potential energy surface. Through isomer-selective photoion mass-selected threshold photoelectron spectroscopy (ms-TPES) the two isomers CH3BCH2 and CH3CHBH were identified by their ms-TPE spectra and IEad values of 8.55 ± 0.02 eV and 8.73 ± 0.02 eV were determined, respectively. A second channel leading to the loss of ethene from TMB forms CH2BH, which exhibits an IEad value of 9.37 ± 0.03 eV. The reaction mechanism in the literature needs to be expanded by an additional methane loss from the intermediately formed ethyl methyl borane.
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Affiliation(s)
- Domenik Schleier
- Institute for Physical and Theoretical Chemistry, University of Würzburg, 97074, Würzburg, Germany.
| | - Marius Gerlach
- Institute for Physical and Theoretical Chemistry, University of Würzburg, 97074, Würzburg, Germany.
| | - Dorothee Schaffner
- Institute for Physical and Theoretical Chemistry, University of Würzburg, 97074, Würzburg, Germany.
| | - Deb Pratim Mukhopadhyay
- Institute for Physical and Theoretical Chemistry, University of Würzburg, 97074, Würzburg, Germany.
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute (PSI), 5232, Villigen, Switzerland.
| | - Ingo Fischer
- Institute for Physical and Theoretical Chemistry, University of Würzburg, 97074, Würzburg, Germany.
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18
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Wu X, Bjelić S, Hemberger P, Bodi A. Isomer-Dependent Threshold Photoelectron Spectroscopy and Dissociative Photoionization Mechanism of Anisaldehyde. J Phys Chem A 2023; 127:661-670. [PMID: 36630284 DOI: 10.1021/acs.jpca.2c07591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We studied the threshold photoionization and dissociative ionization of para-, meta-, and ortho-anisaldehyde by photoelectron photoion coincidence spectroscopy in the 8.20-19.00 eV photon energy range. Vertical ionization energies by equation of motion-ionization potential-coupled cluster singles and doubles (EOM-IP-CCSD) calculations reproduce the photoelectron spectral features in all three isomers. The dissociative photoionization (DPI) pathways of para- and meta-anisaldehyde are similar and differ markedly from those of ortho-anisaldehyde. In the para and meta isomers, the lowest-energy DPI channel corresponds to hydrogen atom loss to form the C8H7O2+ fragment at m/z 135, which undergoes sequential dissociation processes at higher energies, such as carbon monoxide loss to C7H7O+ (m/z 107) and further, sequential CH3, CH2O, and CH2CO losses to produce C6H4O+ (m/z 92), C6H5+ (m/z 77), and C5H5+ (m/z 65), respectively. Carbon monoxide loss from the parent ions, yielding C7H8O+ (m/z 108), is a subordinate dissociation channel parallel to H atom loss. At higher energies, it also gives rise to sequential formaldehyde (CH2O) loss to produce C6H6+ (m/z 78). In the ortho-anisaldehyde cation, the vicinity of the aldehyde and methoxy groups opens up low-energy hydrogen-transfer processes, which allow for seven fragmentation channels to compete effectively with the H- and CO-loss channels. Thus, the fragmentation mechanism changes considerably, thanks to the steric interaction of the substituents. Functional group interactions, in particular H transfer pathways, must therefore be considered when predicting the isomer-specific unimolecular decomposition mechanism of cationic and neutral species, as well as mass spectra for isomers.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, Villigen5232, Switzerland
| | - Saša Bjelić
- Paul Scherrer Institute, Villigen5232, Switzerland
| | | | - Andras Bodi
- Paul Scherrer Institute, Villigen5232, Switzerland
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19
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Lowe B, Cardona AL, Salas J, Bodi A, Mayer PM, Burgos Paci MA. Probing the pyrolysis of ethyl formate in the dilute gas phase by synchrotron radiation and theory. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4901. [PMID: 36691327 DOI: 10.1002/jms.4901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/02/2023] [Indexed: 06/17/2023]
Abstract
The thermal decomposition of the atmospheric constituent ethyl formate was studied by coupling flash pyrolysis with imaging photoelectron photoion coincidence (iPEPICO) spectroscopy using synchrotron vacuum ultraviolet (VUV) radiation at the Swiss Light Source (SLS). iPEPICO allows photoion mass-selected threshold photoelectron spectra (ms-TPES) to be obtained for pyrolysis products. By threshold photoionization and ion imaging, parent ions of neutral pyrolysis products and dissociative photoionization products could be distinguished, and multiple spectral carriers could be identified in several ms-TPES. The TPES and mass-selected TPES for ethyl formate are reported for the first time and appear to correspond to ionization of the lowest energy conformer having a cis (eclipsed) configuration of the O=C(H)-O-C(H2 )-CH3 and trans (staggered) configuration of the O=C(H)-O-C(H2 )-CH3 dihedral angles. We observed the following ethyl formate pyrolysis products: CH3 CH2 OH, CH3 CHO, C2 H6 , C2 H4 , HC(O)OH, CH2 O, CO2 , and CO, with HC(O)OH and C2 H4 pyrolyzing further, forming CO + H2 O and C2 H2 + H2 . The reaction paths and energetics leading to these products, together with the products of two homolytic bond cleavage reactions, CH3 CH2 O + CHO and CH3 CH2 + HC(O)O, were studied computationally at the M06-2X-GD3/aug-cc-pVTZ and SVECV-f12 levels of theory, complemented by further theoretical methods for comparison. The calculated reaction pathways were used to derive Arrhenius parameters for each reaction. The reaction rate constants and branching ratios are discussed in terms of the residence time and newly suggest carbon monoxide as a competitive primary fragmentation product at high temperatures.
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Affiliation(s)
- Bethany Lowe
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - Alejandro L Cardona
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Juana Salas
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Paul M Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - Maxi A Burgos Paci
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
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20
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Gong X, Ye Y, Chowdhury AD. Evaluating the Role of Descriptor- and Spectator-Type Reaction Intermediates During the Early Phases of Zeolite Catalysis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Xuan Gong
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei People’s Republic of China
| | - Yiru Ye
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei People’s Republic of China
| | - Abhishek Dutta Chowdhury
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei People’s Republic of China
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21
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Fernholz C, Bodi A, Hemberger P. Threshold Photoelectron Spectrum of the Phenoxy Radical. J Phys Chem A 2022; 126:9022-9030. [DOI: 10.1021/acs.jpca.2c06670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christin Fernholz
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
| | - Andras Bodi
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
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22
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Tools to understand catalysis. Nat Catal 2022. [DOI: 10.1038/s41929-022-00868-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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Bodi A, Hemberger P, Pérez-Ramírez J. Photoionization reveals catalytic mechanisms. Nat Catal 2022. [DOI: 10.1038/s41929-022-00847-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Paunović V, Hemberger P, Bodi A, Hauert R, van Bokhoven JA. Impact of Nonzeolite-Catalyzed Formation of Formaldehyde on the Methanol-to-Hydrocarbons Conversion. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Vladimir Paunović
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
- Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Roland Hauert
- Swiss Federal Laboratories for Materials Science and Technology, EMPA, Überlandstrasse 129, 8600 Dübendorf, Switzerland
| | - Jeroen A. van Bokhoven
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
- Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
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Wu X, Zhang Z, Pan Z, Zhou X, Bodi A, Hemberger P. Ketenes in the Induction of the Methanol-to-Olefins Process. Angew Chem Int Ed Engl 2022; 61:e202207777. [PMID: 35929758 PMCID: PMC9804150 DOI: 10.1002/anie.202207777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Indexed: 01/05/2023]
Abstract
Ketene (CH2 =C=O) has been postulated as a key intermediate for the first olefin production in the zeolite-catalyzed chemistry of methanol-to-olefins (MTO) and syngas-to-olefins (STO) processes. The reaction mechanism remains elusive, because the short-lived ethenone ketene and its derivatives are difficult to detect, which is further complicated by the low expected ketene concentration. We report on the experimental detection of methylketene (CH3 -CH=C=O) formed by the methylation of ketene on HZSM-5 via operando synchrotron photoelectron photoion coincidence (PEPICO) spectroscopy. Ketene is produced in situ from methyl acetate. The observation of methylketene as the ethylene precursor evidences a computationally predicted ketene-to-ethylene route proceeding via a methylketene intermediate followed by decarbonylation.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute5232VilligenSwitzerland
| | - Zihao Zhang
- Paul Scherrer Institute5232VilligenSwitzerland
- National Centre of Competence in Research (NCCR) CatalysisPaul Scherrer Institute5232VilligenSwitzerland
| | - Zeyou Pan
- Paul Scherrer Institute5232VilligenSwitzerland
| | - Xiaoguo Zhou
- Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei230026China
| | - Andras Bodi
- Paul Scherrer Institute5232VilligenSwitzerland
- National Centre of Competence in Research (NCCR) CatalysisPaul Scherrer Institute5232VilligenSwitzerland
| | - Patrick Hemberger
- Paul Scherrer Institute5232VilligenSwitzerland
- National Centre of Competence in Research (NCCR) CatalysisPaul Scherrer Institute5232VilligenSwitzerland
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26
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Pan Z, Bodi A, van Bokhoven JA, Hemberger P. Operando PEPICO unveils the catalytic fast pyrolysis mechanism of the three methoxyphenol isomers. Phys Chem Chem Phys 2022; 24:21786-21793. [PMID: 36082786 PMCID: PMC9491049 DOI: 10.1039/d2cp02741k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of lignin valorization processes such as catalytic fast pyrolysis (CFP) to produce fine chemicals and fuels leads to a more sustainable future. The implementation of CFP is enabled by understanding the chemistry of lignin constituents, which, however, requires thorough mechanistic investigations by detecting reactive species. In this contribution, we investigate the CFP of the three methoxyphenol (MP) isomers over H-ZSM-5 utilizing vacuum ultraviolet synchrotron radiation and operando photoelectron photoion coincidence (PEPICO) spectroscopy. All isomers demethylate at first to yield benzenediols, from which dehydroxylation reactions proceed to produce phenol and benzene. Additional pathways to form benzene proceed over cyclopentadiene, methylcyclopentadiene, and fulvene intermediates. The detection of trace amounts of methanol in the product stream suggests a demethoxylation reaction to yield phenol. Guaiacol (2- or ortho-MP) exhibits slightly higher reactivity compared to 3-MP and 4-MP, due to the formation of the fulvenone ketene, which opens additional routes to benzene and phenol. When compared to benzenediol catalytic pyrolysis, the additional methyl group in MP leads to high conversion at lower reactor temperatures, which is mostly owed to the lower H3C–O vs. H–O bond energy and the possibility to demethoxylate to produce phenol. Demethylation, demethoxylation and fulvenone ketene formation determine the reactivity of methoxyphenols over H-ZSM-5 to yield phenols, benzene and toluene. Intermediates are isomer-selectively detected utilizing threshold photoelectron spectroscopy.![]()
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Affiliation(s)
- Zeyou Pan
- Paul Scherrer Institute, 5232 Villigen, Switzerland. .,Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Andras Bodi
- Paul Scherrer Institute, 5232 Villigen, Switzerland.
| | - Jeroen A van Bokhoven
- Paul Scherrer Institute, 5232 Villigen, Switzerland. .,Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
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27
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Gong X, Çağlayan M, Ye Y, Liu K, Gascon J, Dutta Chowdhury A. First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis. Chem Rev 2022; 122:14275-14345. [PMID: 35947790 DOI: 10.1021/acs.chemrev.2c00076] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Zeolite chemistry and catalysis are expected to play a decisive role in the next decade(s) to build a more decentralized renewable feedstock-dependent sustainable society owing to the increased scrutiny over carbon emissions. Therefore, the lack of fundamental and mechanistic understanding of these processes is a critical "technical bottleneck" that must be eliminated to maximize economic value and minimize waste. We have identified, considering this objective, that the chemistry related to the first-generation reaction intermediates (i.e., carbocations, radicals, carbenes, ketenes, and carbanions) in zeolite chemistry and catalysis is highly underdeveloped or undervalued compared to other catalysis streams (e.g., homogeneous catalysis). This limitation can often be attributed to the technological restrictions to detect such "short-lived and highly reactive" intermediates at the interface (gas-solid/solid-liquid); however, the recent rise of sophisticated spectroscopic/analytical techniques (including under in situ/operando conditions) and modern data analysis methods collectively compete to unravel the impact of these organic intermediates. This comprehensive review summarizes the state-of-the-art first-generation organic reaction intermediates in zeolite chemistry and catalysis and evaluates their existing challenges and future prospects, to contribute significantly to the "circular carbon economy" initiatives.
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Affiliation(s)
- Xuan Gong
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei P. R. China
| | - Mustafa Çağlayan
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Yiru Ye
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei P. R. China
| | - Kun Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei P. R. China
| | - Jorge Gascon
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
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Wu X, Zhang Z, Pan Z, Zhou X, Bodi A, Hemberger P. Ketenes in the Induction of the Methanol‐to‐Olefins Process. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute: Paul Scherrer Institut PSI General Energy SWITZERLAND
| | - Zihao Zhang
- Paul Scherrer Institute: Paul Scherrer Institut PSI Photon Science SWITZERLAND
| | - Zeyou Pan
- Paul Scherrer Institute: Paul Scherrer Institut PSI Photon Science SWITZERLAND
| | - Xiaoguo Zhou
- University of Science and Technology of China Department of Chemical Physics CHINA
| | - Andras Bodi
- Paul Scherrer Institute: Paul Scherrer Institut PSI Photon Science SWITZERLAND
| | - Patrick Hemberger
- Paul Scherrer Institut Molecular Dynamics WSLA/028 5232 Villigen PSI SWITZERLAND
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Elucidation of radical- and oxygenate-driven paths in zeolite-catalysed conversion of methanol and methyl chloride to hydrocarbons. Nat Catal 2022; 5:605-614. [PMID: 35892076 PMCID: PMC7613158 DOI: 10.1038/s41929-022-00808-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 05/18/2022] [Indexed: 11/08/2022]
Abstract
Understanding hydrocarbon generation in the zeolite-catalysed conversions of methanol and methyl chloride requires advanced spectroscopic approaches to distinguish the complex mechanisms governing C-C bond formation, chain growth and the deposition of carbonaceous species. Here operando photoelectron photoion coincidence (PEPICO) spectroscopy enables the isomer-selective identification of pathways to hydrocarbons of up to C14 in size, providing direct experimental evidence of methyl radicals in both reactions and ketene in the methanol-to-hydrocarbons reaction. Both routes converge to C5 molecules that transform into aromatics. Operando PEPICO highlights distinctions in the prevalence of coke precursors, which is supported by electron paramagnetic resonance measurements, providing evidence of differences in the representative molecular structure, density and distribution of accumulated carbonaceous species. Radical-driven pathways in the methyl chloride-to-hydrocarbons reaction(s) accelerate the formation of extended aromatic systems, leading to fast deactivation. By contrast, the generation of alkylated species through oxygenate-driven pathways in the methanol-to-hydrocarbons reaction extends the catalyst lifetime. The findings demonstrate the potential of the presented methods to provide valuable mechanistic insights into complex reaction networks.
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Redekop EA, Yablonsky GS, Gleaves JT. Truth is, we all are transients: A perspective on the time-dependent nature of reactions and those who study them. Catal Today 2022. [DOI: 10.1016/j.cattod.2022.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Hemberger P, Wu X, Pan Z, Bodi A. Continuous Pyrolysis Microreactors: Hot Sources with Little Cooling? New Insights Utilizing Cation Velocity Map Imaging and Threshold Photoelectron Spectroscopy. J Phys Chem A 2022; 126:2196-2210. [PMID: 35316066 DOI: 10.1021/acs.jpca.2c00766] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Resistively heated silicon carbide microreactors are widely applied as continuous sources to selectively prepare elusive and reactive intermediates with astrochemical, catalytic, or combustion relevance to measure their photoelectron spectrum. These reactors also provide deep mechanistic insights into uni- and bimolecular chemistry. However, the sampling conditions and effects have not been fully characterized. We use cation velocity map imaging to measure the velocity distribution of the molecular beam signal and to quantify the scattered, rethermalized background sample. Although translational cooling is efficient in the adiabatic expansion from the reactor, the breakdown diagrams of methane and chlorobenzene confirm that the molecular beam component exhibits a rovibrational temperature comparable with that of the reactor. Thus, rovibrational cooling is practically absent in the expansion from the microreactor. The high rovibrational temperature also affects the threshold photoelectron spectrum of both benzene and the allyl radical in the molecular beam, but to different degrees. While the extreme broadening of the benzene TPES suggests a complex ionization mechanism, the allyl TPES is in fact consistent with an internal temperature close to that of the reactor. The background, room-temperature spectra of both are superbly reproduced by Franck-Condon simulations at 300 K. On the one hand, this leads us to suggest that room-temperature reference spectra should be used in species identification. On the other hand, analysis of the allyl iodide pyrolysis data shows that iodine atoms often recombine to form molecular iodine on the chamber surfaces. Such sampling effects may distort the chemical composition of the scattered background with respect to the molecular beam signal emanating directly from the reactor. This must be considered in quantitative analyses and kinetic modeling.
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Affiliation(s)
- Patrick Hemberger
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Xiangkun Wu
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Zeyou Pan
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Andras Bodi
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
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32
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Schleier D, Hemberger P, Bodi A, Bouwman J. Threshold Photoelectron Spectroscopy of Quinoxaline, Quinazoline, and Cinnoline. J Phys Chem A 2022; 126:2211-2221. [PMID: 35357143 DOI: 10.1021/acs.jpca.2c01073] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The threshold photoelectron spectra of cinnoline, quinazoline, and quinoxaline, three small naphthalene-analogue polycyclic nitrogen-containing hydrocarbons of C8H6N2 composition, were recorded. The spectra are assigned to understand their electronic structure and the role of isomerism. Furthermore, this work provides reference data for the selective identification of such species as gas-phase reaction products at low number densities. Imaging photoelectron photoion coincidence spectroscopy was used at the VUV beamline of the Swiss Light Source to record the spectra from the ionization onset to 12 eV. To assign and interpret the spectral features, we relied on (time-dependent) density functional theory and EOM-IP-CCSD calculations and computed vertical and adiabatic ionization energies as well as Franck-Condon factors to simulate ground- and excited-state spectra. Vibrational progressions belonging to four electronic states could be simulated in each of the samples, and we report a total of 12 adiabatic ionization energies, including the ones to the ground and excited cation states. Such a wealth of spectral information, as well as the reliable ab initio modeling, is promising with regards to analytical applications. While cinnoline can be easily distinguished by its lowest adiabatic ionization energy, quinazoline and quinoxaline show different vibrational fingerprints, which can be used to distinguish the three isomers even in complex reaction mixtures. Finally, we also relate the cation electronic states to the neutral molecular orbitals and note that Koopmans' approximation fails in these N2-containing species very much like it does in N2.
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Affiliation(s)
- Domenik Schleier
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, NL 2300 RA Leiden, The Netherlands.,Mass Spectrometry in Reactive Flows, Institute for Combustion and Gas Dynamics (IVG), Universität Duisburg-Essen, Duisburg 47057, Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Jordy Bouwman
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT), NASA/SSERVI, Boulder, Colorado 80309, United States
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33
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Pan Z, Bodi A, van Bokhoven JA, Hemberger P. On the absolute photoionization cross section and threshold photoelectron spectrum of two reactive ketenes in lignin valorization: fulvenone and 2-carbonyl cyclohexadienone. Phys Chem Chem Phys 2022; 24:3655-3663. [PMID: 35080222 PMCID: PMC8827046 DOI: 10.1039/d1cp05206c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report the absolute photoionization cross section (PICS) of fulvenone and 2-carbonyl cyclohexadienone, two crucial ketene intermediates in lignin pyrolysis, combustion and organic synthesis. Both species were generated in situ by pyrolyzing salicylamide and dectected via imaging photoelectron photoion coincidence spectroscopy. In a deamination reaction, salicylamide loses ammonia yielding 2-carbonyl cyclohexadienone, a ketoketene, which further decarbonylates at higher pyrolysis temperatures to form fulvenone. We recorded the threshold photoelectron spectrum of the ketoketene and assigned the ground state (X̃+2A′′ ← X̃1A′) and excited state (Ã+2A′ ← X̃1A′) bands with the help of Franck–Condon simulations. Adiabatic ionization energies are 8.35 ± 0.01 and 9.19 ± 0.01 eV. In a minor reaction channel, the ketoketene isomerizes to benzpropiolactone, which decomposes subsequently to benzyne by CO2 loss. Potential energy surface and RRKM rate constant calculations agree with our experimental observations that the decarbonylation to fulvenone outcompetes the decarboxylation to benzyne by almost two orders of magnitude. The absolute PICS of fulvenone at 10.48 eV was determined to be 18.8 ± 3.8 Mb using NH3 as a calibrant. The PICS of 2-carbonyl cyclohexadienone was found to be 21.5 ± 8.6 Mb at 9 eV. Our PICS measument will enable the quantification of reactive ketenes in lignin valorization and combustion processes using photoionization techniques and provide advanced mechanistic and kinetics insights to aid the bottom-up optimization of such processes. The absolute photoionization cross section (PICS) of these crucial ketene intermediates supports their quantification in lignin pyrolysis, combustion and organic synthesis.![]()
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Affiliation(s)
- Zeyou Pan
- Zeyou Pan, Andras Bodi, Jeroen A. van Bokhoven and Patrick Hemberger, Paul Scherrer Institute, 5232 Villigen, Switzerland. .,Zeyou Pan and Jeroen A. van Bokhoven, Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Andras Bodi
- Zeyou Pan, Andras Bodi, Jeroen A. van Bokhoven and Patrick Hemberger, Paul Scherrer Institute, 5232 Villigen, Switzerland.
| | - Jeroen A van Bokhoven
- Zeyou Pan, Andras Bodi, Jeroen A. van Bokhoven and Patrick Hemberger, Paul Scherrer Institute, 5232 Villigen, Switzerland. .,Zeyou Pan and Jeroen A. van Bokhoven, Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Patrick Hemberger
- Zeyou Pan, Andras Bodi, Jeroen A. van Bokhoven and Patrick Hemberger, Paul Scherrer Institute, 5232 Villigen, Switzerland.
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34
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McCabe MN, Hemberger P, Campisi D, Broxterman JC, Reusch E, Bodi A, Bouwman J. Formation of phenylacetylene and benzocyclobutadiene in the ortho-benzyne + acetylene reaction. Phys Chem Chem Phys 2022; 24:1869-1876. [PMID: 34989380 DOI: 10.1039/d1cp05183k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Ortho-benzyne is a potentially important precursor for polycyclic aromatic hydrocarbon formation, but much is still unknown about its chemistry. In this work, we report on a combined experimental and theoretical study of the o-benzyne + acetylene reaction and employ double imaging threshold photoelectron photoion coincidence spectroscopy to investigate the reaction products with isomer specificity. Based on photoion mass-selected threshold photoelectron spectra, Franck-Condon simulations, and ionization cross section calculations, we conclude that phenylacetylene and benzocyclobutadiene (PA : BCBdiene) are formed at a non-equilibrium ratio of 2 : 1, respectively, in a pyrolysis microreactor at a temperature of 1050 K and a pressure of ∼20 mbar. The C8H6 potential energy surface (PES) is explored to rationalize the formation of the reaction products. Previously unidentified pathways have been found by considering the open-shell singlet (OSS) character of various C8H6 reactive intermediates. Based on the PES data, a kinetic model is constructed to estimate equilibrium abundances of the two products. New insights into the reaction mechanism - with a focus on the OSS intermediates - and the products formed in the o-benzyne + acetylene reaction provide a greater level of understanding of the o-benzyne reactivity during the formation of aromatic hydrocarbons in combustion environments as well as in outflows of carbon-rich stars.
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Affiliation(s)
- Morgan N McCabe
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Dario Campisi
- Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Jeger C Broxterman
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
| | - Engelbert Reusch
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Jordy Bouwman
- Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
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35
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Wu X, Zhou X, Bjelić S, Hemberger P, Sztáray B, Bodi A. A plethora of isomerization processes and hydrogen scrambling in the fragmentation of the methanol dimer cation: a PEPICO study. Phys Chem Chem Phys 2022; 24:1437-1446. [PMID: 34984425 DOI: 10.1039/d1cp05155e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The valence photoionization of light and deuterated methanol dimers was studied by imaging photoelectron photoion coincidence spectroscopy in the 10.00-10.35 eV photon energy range. Methanol clusters were generated in a rich methanol beam in nitrogen after expansion into vacuum. They generally photoionize dissociatively to protonated methanol cluster cations, (CH3OH)nH+. However, the stable dimer parent ion (CH3OH)2+ is readily detected below the dissociation threshold to yield the dominant CH3OH2+ fragment ion. In addition to protonated methanol, we could also detect the water- and methyl-loss fragment ions of the methanol dimer cation for the first time. These newly revealed fragmentation channels are slow and cannot compete with protonated methanol cation formation at higher internal energies. In fact, the water- and methyl-loss fragment ions appear together and disappear at a ca. 150 meV higher energy in the breakdown diagram. Experiments with selectively deuterated methanol samples showed H scrambling involving two hydroxyl and one methyl hydrogens prior to protonated methanol formation. These insights guided the potential energy surface exploration to rationalize the dissociative photoionization mechanism. The potential energy surface was further validated by a statistical model including isotope effects to fit the experiment for the light and the perdeuterated methanol dimers simultaneously. The (CH3OH)2+ parent ion dissociates via five parallel channels at low internal energies. The loss of both CH2OH and CH3O neutral fragments leads to protonated methanol. However, the latter, direct dissociation channel is energetically forbidden at low energies. Instead, an isomerization transition state is followed by proton transfer from a methyl group, which leads to the CH3(H)OH+⋯CH2OH ion, the precursor to the CH2OH-, H2O-, and CH3-loss fragments after further isomerization steps, in part by a roaming mechanism. Water loss yields the ethanol cation, and two paths are proposed to account for m/z 49 fragment ions after CH3 loss. The roaming pathways are quickly outcompeted by hydrogen bond breaking to yield CH3OH2+, which explains the dominance of the protonated methanol fragment ion in the mass spectrum.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, 5232 Villigen, Switzerland.
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Saša Bjelić
- Paul Scherrer Institute, 5232 Villigen, Switzerland.
| | | | - Bálint Sztáray
- University of the Pacific, Department of Chemistry, Stockton, CA 95211, USA
| | - Andras Bodi
- Paul Scherrer Institute, 5232 Villigen, Switzerland.
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36
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Savee J, Sztáray B, Hemberger P, Zádor J, Bodi A, Osborn DL. Unimolecular isomerisation of 1,5-hexadiyne observed by threshold photoelectron photoion coincidence spectroscopy. Faraday Discuss 2022; 238:645-664. [DOI: 10.1039/d2fd00028h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unimolecular isomerisation of the prompt propargyl + propargyl "head-to-head" adduct, 1,5- hexadiyne, to fulvene and benzene by the 3,4-dimethylenecyclobut-1-ene (DMCB) intermediate (all C6H6) was studied in the high-pressure limit...
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37
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Puente‐Urbina A, Pan Z, Paunović V, Šot P, Hemberger P, van Bokhoven JA. Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled. Angew Chem Int Ed Engl 2021; 60:24002-24007. [PMID: 34459534 PMCID: PMC8596584 DOI: 10.1002/anie.202107553] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Indexed: 11/08/2022]
Abstract
Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we use operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C2+ radical intermediates participating in the complex gas-phase reaction network. Our experiments pinpoint different C2 -C5 radical species that allow for a stepwise growth of the hydrocarbon chains. Propargyl radicals (H2 C-C≡C-H) are identified as essential precursors for the formation of aromatics, which then contribute to the formation of heavier hydrocarbon products via hydrogen abstraction-acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for the development of methane valorization processes.
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Affiliation(s)
- Allen Puente‐Urbina
- Institute for Chemical and BioengineeringDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
| | - Zeyou Pan
- Institute for Chemical and BioengineeringDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
- Laboratory for Synchrotron Radiation and FemtochemistryPaul Scherrer InstituteForschungsstrasse 1115232VilligenSwitzerland
| | - Vladimir Paunović
- Institute for Chemical and BioengineeringDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
| | - Petr Šot
- Institute for Chemical and BioengineeringDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
- Laboratory of Inorganic ChemistryDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and FemtochemistryPaul Scherrer InstituteForschungsstrasse 1115232VilligenSwitzerland
| | - Jeroen Anton van Bokhoven
- Institute for Chemical and BioengineeringDepartment of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 1–5/108093ZurichSwitzerland
- Laboratory for Catalysis and Sustainable ChemistryPaul Scherrer InstituteForschungsstrasse 1115232VilligenSwitzerland
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38
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Puente‐Urbina A, Pan Z, Paunović V, Šot P, Hemberger P, Bokhoven JA. Direct Evidence on the Mechanism of Methane Conversion under Non‐oxidative Conditions over Iron‐modified Silica: The Role of Propargyl Radicals Unveiled. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107553] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Allen Puente‐Urbina
- Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
| | - Zeyou Pan
- Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
- Laboratory for Synchrotron Radiation and Femtochemistry Paul Scherrer Institute Forschungsstrasse 111 5232 Villigen Switzerland
| | - Vladimir Paunović
- Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
| | - Petr Šot
- Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
- Laboratory of Inorganic Chemistry Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry Paul Scherrer Institute Forschungsstrasse 111 5232 Villigen Switzerland
| | - Jeroen Anton Bokhoven
- Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1–5/10 8093 Zurich Switzerland
- Laboratory for Catalysis and Sustainable Chemistry Paul Scherrer Institute Forschungsstrasse 111 5232 Villigen Switzerland
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Ramirez A, Gong X, Caglayan M, Nastase SAF, Abou-Hamad E, Gevers L, Cavallo L, Dutta Chowdhury A, Gascon J. Selectivity descriptors for the direct hydrogenation of CO 2 to hydrocarbons during zeolite-mediated bifunctional catalysis. Nat Commun 2021; 12:5914. [PMID: 34625554 PMCID: PMC8501036 DOI: 10.1038/s41467-021-26090-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 09/06/2021] [Indexed: 11/16/2022] Open
Abstract
Cascade processes are gaining momentum in heterogeneous catalysis. The combination of several catalytic solids within one reactor has shown great promise for the one-step valorization of C1-feedstocks. The combination of metal-based catalysts and zeolites in the gas phase hydrogenation of CO2 leads to a large degree of product selectivity control, defined mainly by zeolites. However, a great deal of mechanistic understanding remains unclear: metal-based catalysts usually lead to complex product compositions that may result in unexpected zeolite reactivity. Here we present an in-depth multivariate analysis of the chemistry involved in eight different zeolite topologies when combined with a highly active Fe-based catalyst in the hydrogenation of CO2 to olefins, aromatics, and paraffins. Solid-state NMR spectroscopy and computational analysis demonstrate that the hybrid nature of the active zeolite catalyst and its preferred CO2-derived reaction intermediates (CO/ester/ketone/hydrocarbons, i.e., inorganic-organic supramolecular reactive centers), along with 10 MR-zeolite topology, act as descriptors governing the ultimate product selectivity.
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Affiliation(s)
- Adrian Ramirez
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | - Xuan Gong
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, Hubei, P. R. China
| | - Mustafa Caglayan
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | - Stefan-Adrian F Nastase
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | - Edy Abou-Hamad
- Imaging and Characterization Department, KAUST Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | - Lieven Gevers
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | - Luigi Cavallo
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
| | | | - Jorge Gascon
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.
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Savee JD, Sztáray B, Welz O, Taatjes CA, Osborn DL. Valence Photoionization and Autoionization of the Formyl Radical. J Phys Chem A 2021; 125:3874-3884. [PMID: 33929204 DOI: 10.1021/acs.jpca.1c01775] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have used 308 nm photolysis of acetaldehyde to measure a photoionization spectrum of the formyl (HCO) radical between 8 and 11.5 eV using an 11 meV FWHM photoionization energy resolution. We have confirmed that the formyl radical is the carrier of the spectrum by generating an identical spectrum of the HCO product in the Cl + H2CO reaction. The spectrum of HCO and its deuterated isotopologue (DCO) have several resolved autoionizing resonances above the Franck-Condon envelope, which we assign to autoionization after initial excitation into neutral 3sσ and 3p Rydberg states converging to the first triplet excited state of HCO+(ã 3A'). The quantum defects for these states are δ3sσ = 1.06 ± 0.02 and δ3p = 0.821 ± 0.019. We report absolute photoionization cross-section measurements of σHCOPI(9.907 eV) = 4.5 ± 0.9 Mb, σHCOPI(10.007 eV) = 4.8 ± 1.0 Mb, σHCOPI(10.107 eV) = 6.0 ± 1.2 Mb, σHCOPI(10.107 eV) = 5.7 ± 1.2 Mb, and σHCOPI(10.304 eV) = 10.6 ± 2.2 Mb relative to the photoionization cross section of the methyl radical. The absolute cross-section measurements are a factor of ∼1.5 larger than those determined in past studies, although the presence of strong autoionizing features supports a dependence on photoionization energy resolution. We propose that the semiempirical model of Xu and Pratt for estimation of free radical photoionization cross sections is more accurate when applied with a reference species containing the same atoms as the free radical rather than isoelectronic species with different atoms.
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Affiliation(s)
- John D Savee
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Oliver Welz
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Craig A Taatjes
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States.,Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States
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41
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Wu X, Zhou X, Bjelić S, Hemberger P, Bodi A. Valence Photoionization and Energetics of Vanillin, a Sustainable Feedstock Candidate. J Phys Chem A 2021; 125:3327-3340. [PMID: 33872037 DOI: 10.1021/acs.jpca.1c00876] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We studied the valence photoionization of vanillin by photoelectron photoion coincidence spectroscopy in the 8.20-19.80 eV photon energy range. Vertical ionization energies by EOM-IP-CCSD calculations reproduce the photoelectron spectral features. Composite method calculations and Franck-Condon simulation of the weak, ground-state band yield the adiabatic ionization energy of the most stable vanillin conformer as 8.306(20) eV. The lowest energy dissociative photoionization channels correspond to hydrogen atom, carbon monoxide, and methyl losses, which form the dominant C8H7O3+ (m/z 151) and the less intense C7H8O2+ (m/z 124) and C7H5O3+ (m/z 137) fragment ions in parallel dissociation channels at modeled 0 K appearance energies of 10.13(1), 10.40(3), and 10.58(10) eV, respectively. On the basis of the breakdown diagram, we explore the energetics of sequential methyl and carbon monoxide loss channels, which dominate the fragmentation mechanism at higher photon energies. The 0 K appearance energy for sequential CO loss from the m/z 151 fragment to C7H7O2+ (m/z 123) is 12.99(10) eV, and for sequential CH3 loss from the m/z 123 fragment to C6H4O2+ (m/z 108), it is 15.40(20) eV based on the model. Finally, we review the thermochemistry of the bi- and trifunctionalized benzene derivatives guaiacol, hydroxybenzaldehyde, anisaldehyde, and vanillin. On the basis of isodesmic functional group exchange reactions, we propose new enthalpies of formations, among them ΔfH°298K(vanillin, g) = -383.5 ± 2.9 kJ mol-1. These mechanistic insights and ab initio thermochemistry results will support analytical works to study lignin conversion involving vanillin.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, 5232 Villigen, Switzerland.,Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Saša Bjelić
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | | | - Andras Bodi
- Paul Scherrer Institute, 5232 Villigen, Switzerland
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42
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Steglich M, Wu X, Bodi A, Hemberger P. Double-Imaging Photoelectron Photoion Coincidence Spectroscopy Reveals the Unimolecular Thermal Decomposition Mechanism of Dimethyl Carbonate. J Phys Chem A 2021; 125:2895-2904. [PMID: 33797917 DOI: 10.1021/acs.jpca.1c00724] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We studied the thermal decomposition of dimethyl carbonate (DMC, C3H6O3) in a flash vacuum pyrolysis reactor in the 1100-1700 K range. The reaction products and intermediates were probed by vacuum ultraviolet synchrotron radiation in a photoelectron photoion coincidence (PEPICO) spectrometer to record isomer-specific photoion mass-selected threshold photoelectron (ms-TPE) spectra. Reaction pathways were explored using quantum chemical calculations, which confirmed the experimental observation that the intramolecular migration of a methyl group, yielding dimethyl ether (DME, C2H6O) and carbon dioxide, dominates the initial unimolecular decomposition chemistry. The role of a second potentially important channel, namely, C-O bond fission to yield methyl radicals, could not be determined experimentally due to the short lifetime of the ·C2H3O3 radical and overlapping sequential decomposition products. However, potential energy surface and microcanonical rate constant calculations predict 2 to 3 orders of magnitude lower rates for this channel than for decarboxylation to yield DME. Consequently, DMC pyrolysis shows bewilderingly similar products and product abundances as DME pyrolysis. This coincides with DMC combustion modeling studies, which found that DME is a key intermediate in the mechanism. Furthermore, we have detected traces of methyl formate and formaldehyde, produced after the hydrogen shift to the central carbon atom in DMC. Ethylene and acetylene could be established as bimolecular reaction products because their abundance depended strongly on the DMC concentration. It is intriguing to compare the decomposition of DMC with that of the structurally similar methylal (dimethoxymethane, DMM). While methanol and formaldehyde are produced in similar quantities in DMM, thanks to low-energy hydrogen-transfer reactions, the methanol channel is almost fully suppressed in DMC due to the absence of hydrogens at the central carbon atom and the thermodynamically favored decarboxylation. These new mechanistic insights may help the development of predictive combustion models for fuel additives and biofuels.
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Affiliation(s)
| | - Xiangkun Wu
- Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Andras Bodi
- Paul Scherrer Institute, Villigen 5232, Switzerland
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43
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Bodi A, Hemberger P, Tuckett RP. From Energetics to Intracluster Chemistry: Valence Photoionization of Trifluoromethylsulfur Pentafluoride (CF 3SF 5) by Double Velocity Map Imaging. J Phys Chem A 2021; 125:2601-2611. [PMID: 33729793 DOI: 10.1021/acs.jpca.1c00918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Trifluoromethylsulfur pentafluoride (CF3SF5) was valence threshold photoionized in a double imaging photoelectron photoion coincidence spectrometer using vacuum ultraviolet synchrotron radiation. In the 12.5-16.4 eV photon energy range, CF3+, SF5+, and SF3+ cations were observed in both room temperature (RT) and molecular beam (MB) experiments. Their fractional abundances exhibited differences beyond the sample temperature. Kinetic energy analysis of the fragment ions confirmed the difference in the dissociative photoionization mechanism. In the RT experiment, the CF3+ kinetic energies were extrapolated to a 11.84 ± 0.15 eV threshold, which was used in an ion cycle to determine the enthalpy of formation of CF3SF5 as ΔfH°298K(CF3SF5) = -1593 ± 16 kJ mol-1. We also updated the enthalpy of formation of the sulfur pentafluoride radical as ΔfH°298K(SF5) = -854 ± 7 kJ mol-1 and discuss the discrepancy between the CF3 ionization energy based on the Active Thermochemical Tables and the value anchored to the CF ionization energy. A computed reaction enthalpy network optimization resulted in ΔfH°298K(CF3SF5) = -1608 ± 20 kJ mol-1. Both values for ΔfH°298K(CF3SF5) agree with previous ab initio ones in contrast to the original, experimental determination. SF3+ is formed by F-transfer processes both in the RT and MB experiments. Although the same peaks were observed in both experiments, the lower SF3+ onset energy and the more slowly rising CF3+ kinetic energy release in the MB experiment revealed clustering and intracluster F-transfer reactions upon ionization. The monomer and dimer cation potential energy surfaces were explored to rationalize the observations. In the dimer cation, the observer CF3SF5 catalyzes fluorine transfer and promotes CF4 formation, which ultimately leads to the SF3+ fragment ion.
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Affiliation(s)
- Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Richard P Tuckett
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
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44
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Pan Z, Puente-Urbina A, Bodi A, van Bokhoven JA, Hemberger P. Isomer-dependent catalytic pyrolysis mechanism of the lignin model compounds catechol, resorcinol and hydroquinone. Chem Sci 2021; 12:3161-3169. [PMID: 34164083 PMCID: PMC8179379 DOI: 10.1039/d1sc00654a] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/05/2021] [Indexed: 12/26/2022] Open
Abstract
The catalytic pyrolysis mechanism of the initial lignin depolymerization products will help us develop biomass valorization strategies. How does isomerism influence reactivity, product formation, selectivities, and side reactions? By using imaging photoelectron photoion coincidence (iPEPICO) spectroscopy with synchrotron radiation, we reveal initial, short-lived reactive intermediates driving benzenediol catalytic pyrolysis over H-ZSM-5 catalyst. The detailed reaction mechanism unveils new pathways leading to the most important products and intermediates. Thanks to the two vicinal hydroxyl groups, catechol (o-benzenediol) is readily dehydrated to form fulvenone, a reactive ketene intermediate, and exhibits the highest reactivity. Fulvenone is hydrogenated on the catalyst surface to phenol or is decarbonylated to produce cyclopentadiene. Hydroquinone (p-benzenediol) mostly dehydrogenates to produce p-benzoquinone. Resorcinol, m-benzenediol, is the most stable isomer, because dehydration and dehydrogenation both involve biradicals owing to the meta position of the hydroxyl groups and are unfavorable. The three isomers may also interconvert in a minor reaction channel, which yields small amounts of cyclopentadiene and phenol via dehydroxylation and decarbonylation. We propose a generalized reaction mechanism for benzenediols in lignin catalytic pyrolysis and provide detailed mechanistic insights on how isomerism influences conversion and product formation. The mechanism accounts for processes ranging from decomposition reactions to molecular growth by initial polycyclic aromatic hydrocarbon (PAH) formation steps to yield, e.g., naphthalene. The latter involves a Diels-Alder dimerization of cyclopentadiene, isomerization, and dehydrogenation.
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Affiliation(s)
- Zeyou Pan
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute 5232 Villigen Switzerland
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich 8093 Zurich Switzerland
| | - Allen Puente-Urbina
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich 8093 Zurich Switzerland
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute 5232 Villigen Switzerland
| | - Jeroen A van Bokhoven
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich 8093 Zurich Switzerland
- Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute 5232 Villigen Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute 5232 Villigen Switzerland
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45
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Zuo W, Zhang L, Zhang Z, Tang S, Sun Y, Huang H, Yu Y. Degradation of organic pollutants by intimately coupling photocatalytic materials with microbes: a review. Crit Rev Biotechnol 2021; 41:273-299. [PMID: 33525937 DOI: 10.1080/07388551.2020.1869689] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
With the rapid development of industry and agriculture, large amounts of organic pollutants have been released into the environment. Consequently, the degradation of refractory organic pollutants has become one of the toughest challenges in remediation. To solve this problem, intimate coupling of photocatalysis and biodegradation (ICPB) technology, which allows the simultaneous action of photocatalysis and biodegradation and thus integrates the advantages of photocatalytic reactions and biological treatments, was developed recently. ICPB consists mainly of porous carriers, photocatalysts, biofilms, and an illuminated reactor. Under illumination, photocatalysts on the surface of the carriers convert refractory pollutants into biodegradable products through photocatalytic reactions, after which these products are completely degraded by the biofilms cultivated in the carriers. Additionally, the biofilms are protected by the carriers from the harmful light and free radicals generated by the photocatalyst. Compared with traditional technologies, ICPB remarkably improves the degradation efficiency and reduces the cost of bioremediation. In this review, we introduce the origin and mechanisms of ICPB, discuss the development of reactors, carriers, photocatalysts, and biofilms used in ICPB, and summarize the applications of ICPB to treat organic pollutants. Finally, gaps in this research as well as future perspectives are discussed.
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Affiliation(s)
- Wenlu Zuo
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, PR China.,School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, PR China
| | - Lei Zhang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, PR China
| | - Zhidong Zhang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, PR China.,Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Xinjiang Uigur Autonomous Region, Urumqi, PR China
| | - Susu Tang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, PR China
| | - Yongjun Sun
- College of Urban Construction, Nanjing Tech University, Nanjing, PR China
| | - He Huang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, PR China
| | - Yadong Yu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, PR China.,School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, PR China
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46
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Wu X, Zhou X, Hemberger P, Bodi A. Dissociative Photoionization of Chloro-, Bromo-, and Iodocyclohexane: Thermochemistry and the Weak C–Br Bond in the Cation. J Phys Chem A 2021; 125:646-656. [DOI: 10.1021/acs.jpca.0c10386] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, Villigen 5232, Switzerland
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | | | - Andras Bodi
- Paul Scherrer Institute, Villigen 5232, Switzerland
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47
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Hoener M, Bodi A, Hemberger P, Endres T, Kasper T. Threshold photoionization shows no sign of nitryl hydride in methane oxidation with nitric oxide. Phys Chem Chem Phys 2021; 23:1265-1272. [DOI: 10.1039/d0cp04924g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
No nitryl hydride was detected in partial oxidation of nitric oxide doped methane, despite recent theoretical reaction rates suggesting otherwise.
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Affiliation(s)
- Martin Hoener
- Mass Spectrometry in Reactive Flows – Institute for Combustion and Gas Dynamics (IVG)
- University Duisburg-Essen
- Duisburg 47057
- Germany
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry
- Paul Scherrer Institute
- Villigen
- Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry
- Paul Scherrer Institute
- Villigen
- Switzerland
| | - Torsten Endres
- Reactive Fluids – Institute for Combustion and Gas Dynamics (IVG)
- University Duisburg-Essen
- Duisburg 47057
- Germany
| | - Tina Kasper
- Mass Spectrometry in Reactive Flows – Institute for Combustion and Gas Dynamics (IVG)
- University Duisburg-Essen
- Duisburg 47057
- Germany
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48
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Zhou B, Huang E, Almeida R, Gurses S, Ungar A, Zetterberg J, Kulkarni A, Kronawitter CX, Osborn DL, Hansen N, Frank JH. Near-Surface Imaging of the Multicomponent Gas Phase above a Silver Catalyst during Partial Oxidation of Methanol. ACS Catal 2020. [DOI: 10.1021/acscatal.0c04396] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Bo Zhou
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
- Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Erxiong Huang
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Raybel Almeida
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Sadi Gurses
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Alexander Ungar
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Johan Zetterberg
- Division of Combustion Physics, Lund University, Lund SE-221 00, Sweden
| | - Ambarish Kulkarni
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Coleman X. Kronawitter
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - David L. Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Nils Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Jonathan H. Frank
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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Tao L, Choksi TS, Liu W, Pérez-Ramírez J. Synthesizing High-Volume Chemicals from CO 2 without Direct H 2 Input. CHEMSUSCHEM 2020; 13:6066-6089. [PMID: 32946662 DOI: 10.1002/cssc.202001604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Decarbonizing the chemical industry will eventually entail using CO2 as a feedstock for chemical synthesis. However, many chemical syntheses involve CO2 reduction using inputs such as renewable hydrogen. In this review, chemical processes are discussed that use CO2 as an oxidant for upgrading hydrocarbon feedstocks. The captured CO2 is inherently reduced by the hydrocarbon co-reactants without consuming molecular hydrogen or renewable electricity. This CO2 utilization approach can be potentially applied to synthesize eight emission-intensive molecules, including olefins and epoxides. Catalytic systems and reactor concepts are discussed that can overcome practical challenges, such as thermodynamic limitations, over-oxidation, coking, and heat management. Under the best-case scenario, these hydrogen-free CO2 reduction processes have a combined CO2 abatement potential of approximately 1 gigatons per year and avoid the consumption of 1.24 PWh renewable electricity, based on current market demand and supply.
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Affiliation(s)
- Longgang Tao
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore
| | - Tej S Choksi
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore
| | - Wen Liu
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore
| | - Javier Pérez-Ramírez
- Institute of Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg, 1, 8093, Zurich, Switzerland
- Department of Chemical, Biomolecular Engineering National University Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
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50
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Garcia GA, Loison JC, Holzmeier F, Gans B, Alcaraz C, Nahon L, Wu X, Zhou X, Bodi A, Hemberger P. Characterisation of the first electronically excited state of protonated acetylene C2H3+ by coincident imaging photoelectron spectroscopy. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1825851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
| | - Jean-Christophe Loison
- Institut des Sciences Moléculaires, UMR 5255 CNRS - Université de Bordeaux, Cedex, France
| | - Fabian Holzmeier
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Wüzburg, Germany
| | - Bérenger Gans
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris-Saclay, Orsay, France
| | - Christian Alcaraz
- Institut de Chimie Physique, CNRS, Université Paris-Saclay, Orsay, France
| | - Laurent Nahon
- Synchrotron SOLEIL, L'Orme des Merisiers, Cedex, France
| | - Xiangkun Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Peoples Republic of China
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Peoples Republic of China
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
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