1
|
Kanayama K, Nakamura H, Maruta K, Bodi A, Hemberger P. The Unimolecular Decomposition Mechanism of Trimethyl Phosphate. Chemistry 2024; 30:e202401750. [PMID: 38877823 DOI: 10.1002/chem.202401750] [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: 05/03/2024] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 06/16/2024]
Abstract
Trimethyl phosphate (TMP), an organophosphorus compound (OPC), is a promising fire-retardant candidate for lithium-ion battery (LIB) electrolytes to mitigate fire spread. This study aims to understand the mechanism of TMP unimolecular thermal decomposition to support the integration of a TMP chemical kinetic model into a LIB electrolyte surrogate model. Reactive intermediates and products of TMP thermal decomposition were experimentally detected using vacuum ultraviolet (VUV) synchrotron radiation and double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy. Phosphorus-containing intermediates such as PO, HPO and HPO2 were identified. Sampling effects could successfully be obviated thanks to photoion imaging, which also showed evidence for isomerization reactions upon wall collisions in the ionization chamber. Quantum chemical calculations performed for the unimolecular decomposition of TMP revealed for the first time that isomerization channels via hydrogen and methyl transfer (barrier heights of 65.9 and 72.6 kcal/mol, respectively) are the lowest-energy primary steps of TMP decomposition followed by CH3OH/CH3/CH2O or dimethyl ether (DME) production, respectively. We found an analogous DME production channel in the unimolecular decomposition of dimethyl methylphosphonate (DMMP), another important OPC fire-retardant additive with a similar molecular structure to TMP, which are not included in currently available chemical kinetic models.
Collapse
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, 980-8577, Sendai, Miyagi, Japan
- Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba, 980-8579, Sendai, Miyagi, Japan
| | - Hisashi Nakamura
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba, 980-8577, Sendai, Miyagi, Japan
| | - Kaoru Maruta
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba, 980-8577, Sendai, Miyagi, 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
| |
Collapse
|
2
|
Han L, Sun C, Wang HT, Lin WX, Chen JL, Pao CW, Chuang YC, Wang CH, Zhou J, Wang J, Pong WF, Xin HL. Interrogation of 3d Transition Bimetallic Nanocrystal Nucleation and Growth Using In Situ Electron Microscope and Synchrotron X-ray Techniques. NANO LETTERS 2024; 24:7645-7653. [PMID: 38875704 DOI: 10.1021/acs.nanolett.4c01442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Understanding the nucleation and growth mechanism of 3d transition bimetallic nanocrystals (NCs) is crucial to developing NCs with tailored nanostructures and properties. However, it remains a significant challenge due to the complexity of 3d bimetallic NCs formation and their sensitivity to oxygen. Here, by combining in situ electron microscopy and synchrotron X-ray techniques, we elucidate the nucleation and growth pathways of Fe-Ni NCs. Interestingly, the formation of Fe-Ni NCs emerges from the assimilation of Fe into Ni clusters together with the reduction of Fe-Ni oxides. Subsequently, these NCs undergo solid-state phase transitions, resulting in two distinct solid solutions, ultimately dominated by γ-Fe3Ni2. Furthermore, we deconvolve the interplays between local coordination and electronic state concerning the growth temperature. We directly visualize the oxidation-state distributions of Fe and Ni at the nanoscale and investigate their changes. This work may reshape and enhance the understanding of nucleation and growth in atomic crystallization.
Collapse
Affiliation(s)
- Lili Han
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, People's Republic of China
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Chen Sun
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, People's Republic of China
| | - Hsiao-Tsu Wang
- Bachelor's Program in Advanced Materials Science, Tamkang University, New Taipei City 25137, Taiwan
| | - Wei-Xuan Lin
- Department of Physics, Tamkang University, New Taipei City 25137, Taiwan
| | - Jeng-Lung Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chih-Wen Pao
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yu-Chun Chuang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Jigang Zhou
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon S7N 2 V3, Canada
| | - Jian Wang
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon S7N 2 V3, Canada
| | - Way-Faung Pong
- Department of Physics, Tamkang University, New Taipei City 25137, Taiwan
| | - Huolin L Xin
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
Uchkina D, Vlasov S, Ponomarev A. Effect of boiling on the radiolysis of acetylacetone. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
7
|
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
| |
Collapse
|
8
|
Zhao Z, Liu Z, Zhang A, Yan X, Xue W, Peng B, Xin HL, Pan X, Duan X, Huang Y. Graphene-nanopocket-encaged PtCo nanocatalysts for highly durable fuel cell operation under demanding ultralow-Pt-loading conditions. NATURE NANOTECHNOLOGY 2022; 17:968-975. [PMID: 35879455 DOI: 10.1038/s41565-022-01170-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
The proton exchange membrane fuel cell (PEMFC) as an attractive clean power source can promise a carbon-neutral future, but the widespread adoption of PEMFCs requires a substantial reduction in the usage of the costly platinum group metal (PGM) catalysts. Ultrafine nanocatalysts are essential to provide sufficient catalytic sites at a reduced PGM loading, but are fundamentally less stable and prone to substantial size growth in long-term operations. Here we report the design of a graphene-nanopocket-encaged platinum cobalt (PtCo@Gnp) nanocatalyst with good electrochemical accessibility and exceptional durability under a demanding ultralow PGM loading (0.070 mgPGM cm-2) due to the non-contacting enclosure of graphene nanopockets. The PtCo@Gnp delivers a state-of-the-art mass activity of 1.21 A mgPGM-1, a rated power of 13.2 W mgPGM-1 and a mass activity retention of 73% after an accelerated durability test. With the greatly improved rated power and durability, we project a 6.8 gPGM loading for a 90 kW PEMFC vehicle, which approaches that used in a typical catalytic converter.
Collapse
Affiliation(s)
- Zipeng Zhao
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - Zeyan Liu
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ao Zhang
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - Xingxu Yan
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
| | - Wang Xue
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Bosi Peng
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Huolin L Xin
- Department of Physics and Astronomy, University of California, Irvine, CA, USA
| | - Xiaoqing Pan
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Physics and Astronomy, University of California, Irvine, CA, USA
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Yu Huang
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, USA.
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA.
| |
Collapse
|
9
|
Lowe B, Cardona AL, Salas J, Bodi A, Burgos Paci MA, Mayer PM. Probing the pyrolysis of methyl formate in the dilute gas phase by synchrotron radiation and theory. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4868. [PMID: 35698788 DOI: 10.1002/jms.4868] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/22/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
The thermal dissociation of the atmospheric constituent methyl formate was probed by coupling pyrolysis with imaging photoelectron photoion coincidence spectroscopy (iPEPICO) using synchrotron VUV radiation at the Swiss Light Source (SLS). iPEPICO allows threshold photoelectron spectra to be obtained for pyrolysis products, distinguishing isomers and separating ionic and neutral dissociation pathways. In this work, the pyrolysis products of dilute methyl formate, CH3 OC(O)H, were elucidated to be CH3 OH + CO, 2 CH2 O and CH4 + CO2 as in part distinct from the dissociation of the radical cation (CH3 OH+• + CO and CH2 OH+ + HCO). Density functional theory, CCSD(T), and CBS-QB3 calculations were used to describe the experimentally observed reaction mechanisms, and the thermal decomposition kinetics and the competition between the reaction channels are addressed in a statistical model. One result of the theoretical model is that CH2 O formation was predicted to come directly from methyl formate at temperatures below 1200 K, while above 1800 K, it is formed primarily from the thermal decomposition of methanol.
Collapse
Affiliation(s)
- Bethany Lowe
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, 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
| | - Maxi A Burgos Paci
- INFIQC-CONICET, Departamento Fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Paul M Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
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.![]()
Collapse
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.
| |
Collapse
|
12
|
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.
Collapse
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.
| |
Collapse
|