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Andriopoulou C, Kentri T, Boghosian S. Vibrational spectroscopy of dispersed Re VIIO x sites supported on monoclinic zirconia. Dalton Trans 2024; 53:4020-4034. [PMID: 38319078 DOI: 10.1039/d3dt04270g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
In situ Raman and FTIR spectra complemented by in situ Raman/18O isotope labelling are exploited for deciphering the structural properties and configurations of the (ReOx)n phase dispersed on monoclinic ZrO2 at temperatures of 120-400 °C under oxidative dehydration conditions and coverages in the range of 0.71-3.7 Re nm-2. The dispersed (ReOx)n phase is heterogeneous, consisting of three distinct structural units: (a) Species-I with mono-oxo termination ORe(-O-Zr)m (ReO mode at 993-1005 cm-1); (b) Species-IIa with di-oxo termination (O)2Re(-O-Zr)m-1 (symmetric stretching mode at 987-998 cm-1); and (c) Species-IIb with di-oxo termination (O)2Re(-O-Zr)u (symmetric stretching mode at 982-991 cm-1); all terminal stretching modes undergo blue shifts with increasing coverage. With increasing temperature, a reversible temperature-dependent Species-IIa ↔ Species-I transformation is evidenced. At low coverages, below 1 Re nm-2, isolated species prevail; at 400 °C the mono-oxo ORe(-O-Zr)m Species-I is the majority species, the di-oxo Species-IIa occurs in significant proportion and di-oxo Species-IIb is in the minority. At coverage ≥1.3 Re nm-2, at 400 °C the di-oxo Species-IIa prevails clearly over mono-oxo Species-I. Below 80 °C and at a low coverage of 0.71 Re nm-2, the occurrence of a fourth structural unit, Species-III taking on a tri-oxo configuration (symmetric stretching mode at 974 cm-1) is evidenced. All temperature-dependent structural and configurational transformations are fully reversible and interpreted by mechanisms at the molecular level.
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Affiliation(s)
| | - Theocharis Kentri
- Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - Soghomon Boghosian
- Department of Chemical Engineering, University of Patras, Patras, Greece.
- Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras, Greece
- School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
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2
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Kruczała K, Neubert S, Dhaka K, Mitoraj D, Jánošíková P, Adler C, Krivtsov I, Patzsch J, Bloh J, Biskupek J, Kaiser U, Hocking RK, Caspary Toroker M, Beranek R. Enhancing Photocatalysis: Understanding the Mechanistic Diversity in Photocatalysts Modified with Single-Atom Catalytic Sites. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303571. [PMID: 37888857 PMCID: PMC10724417 DOI: 10.1002/advs.202303571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/16/2023] [Indexed: 10/28/2023]
Abstract
Surface modification of heterogeneous photocatalysts with single-atom catalysts (SACs) is an attractive approach for achieving enhanced photocatalytic performance. However, there is limited knowledge of the mechanism of photocatalytic enhancement in SAC-modified photocatalysts, which makes the rational design of high-performance SAC-based photocatalysts challenging. Herein, a series of photocatalysts for the aerobic degradation of pollutants based on anatase TiO2 modified with various low-cost, non-noble SACs (vanadate, Cu, and Fe ions) is reported. The most active SAC-modified photocatalysts outperform TiO2 modified with the corresponding metal oxide nanoparticles and state-of-the-art benchmark photocatalysts such as platinized TiO2 and commercial P25 powders. A combination of in situ electron paramagnetic resonance spectroscopy and theoretical calculations reveal that the best-performing photocatalysts modified with Cu(II) and vanadate SACs exhibit significant differences in the mechanism of activity enhancement, particularly with respect to the rate of oxygen reduction. The superior performance of vanadate SAC-modified TiO2 is found to be related to the shallow character of the SAC-induced intragap states, which allows for both the effective extraction of photogenerated electrons and fast catalytic turnover in the reduction of dioxygen, which translates directly into diminished recombination. These results provide essential guidelines for developing efficient SAC-based photocatalysts.
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Affiliation(s)
- Krzysztof Kruczała
- Faculty of ChemistryJagiellonian University in KrakówGronostajowa 2/C1‐21Krakow30–387Poland
| | - Susann Neubert
- Faculty of Chemistry and BiochemistryRuhr University BochumUniversitätsstr. 15044780BochumGermany
| | - Kapil Dhaka
- Department of Materials Science and EngineeringTechnion – Israel Institute of TechnologyHaifa3200003Israel
| | - Dariusz Mitoraj
- Institute of ElectrochemistryUlm UniversityAlbert‐Einstein‐Allee 4789069UlmGermany
| | - Petra Jánošíková
- Faculty of Chemistry and BiochemistryRuhr University BochumUniversitätsstr. 15044780BochumGermany
| | - Christiane Adler
- Institute of ElectrochemistryUlm UniversityAlbert‐Einstein‐Allee 4789069UlmGermany
| | - Igor Krivtsov
- Institute of ElectrochemistryUlm UniversityAlbert‐Einstein‐Allee 4789069UlmGermany
- Department of Chemical and Environmental EngineeringUniversity of OviedoOviedo33006Spain
| | - Julia Patzsch
- Chemical Technology GroupDECHEMA Research InstituteTheodor‐Heuss‐Allee 2560486Frankfurt am MainGermany
| | - Jonathan Bloh
- Chemical Technology GroupDECHEMA Research InstituteTheodor‐Heuss‐Allee 2560486Frankfurt am MainGermany
| | - Johannes Biskupek
- Central Facility of Electron MicroscopyElectron Microscopy Group of Material ScienceUniversity of UlmD‐89081UlmGermany
| | - Ute Kaiser
- Central Facility of Electron MicroscopyElectron Microscopy Group of Material ScienceUniversity of UlmD‐89081UlmGermany
| | - Rosalie K. Hocking
- Department of Chemistry and BiotechnologyARC Training Centre for Surface Engineering for Advanced Material SEAMSwinburne University of TechnologyHawthornVIC3122Australia
| | - Maytal Caspary Toroker
- Department of Materials Science and EngineeringTechnion – Israel Institute of TechnologyHaifa3200003Israel
- The Nancy and Stephen Grand Technion Energy ProgramTechnion – Israel Institute of TechnologyHaifa3200003Israel
| | - Radim Beranek
- Institute of ElectrochemistryUlm UniversityAlbert‐Einstein‐Allee 4789069UlmGermany
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Arnosti NA, Wyss V, Delley MF. Controlled Surface Modification of Cobalt Phosphide with Sulfur Tunes Hydrogenation Catalysis. J Am Chem Soc 2023; 145:23556-23567. [PMID: 37873976 PMCID: PMC10623574 DOI: 10.1021/jacs.3c07312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/19/2023] [Accepted: 10/09/2023] [Indexed: 10/25/2023]
Abstract
Transition metal phosphides have shown promise as catalysts for water splitting and hydrotreating, especially when a small amount of sulfur is incorporated into the phosphides. However, the effect of sulfur on catalysis is not well understood. In part, this is because conventional preparation methods of sulfur-doped transition metal phosphides lead to sulfur both inside and at the surface of the material. Here, we present an alternative method of modifying cobalt phosphide (CoP) with sulfur using molecular S-transfer reagents, namely, phosphine sulfides (SPR3). SPR3 added sulfur to the surface of CoP and using a series of SPR3 reagents having different P═S bond strengths enabled control over the amount and type of sulfur transferred. Our results show that there is a distribution of different sulfur sites possible on the CoP surface with S-binding strengths in the range of 69 to 84 kcal/mol. This provides fundamental information on how sulfur binds to an amorphous CoP surface and provides a basis to assess how number and type of sulfur on CoP influences catalysis. For the catalytic hydrogenation of cinnamaldehyde, intermediate amounts of sulfur with intermediate binding strengths at the surface of CoP were optimal. With some but not too much sulfur, CoP exhibited a higher hydrogenation productivity and a decreased formation of secondary reaction products. Our work provides important insight into the S-effect on the catalysis by transition metal phosphides and opens new avenues for catalyst design.
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Affiliation(s)
- Nina A. Arnosti
- Department of Chemistry, University
of Basel, 4058 Basel, Switzerland
| | - Vanessa Wyss
- Department of Chemistry, University
of Basel, 4058 Basel, Switzerland
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4
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Kentri T, Tsevis A, Boghosian S. Heterogeneity of the vanadia phase dispersed on titania. Co-existence of distinct mono-oxo VO x sites. Dalton Trans 2023. [PMID: 37211989 DOI: 10.1039/d3dt00749a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The structural and configurational characteristics of the species comprising the (VOx)n phase dispersed on TiO2(P25) are studied under oxidative dehydration conditions by in situ molecular vibrational spectroscopy (Raman, FTIR) complemented by in situ Raman/18O isotope exchange and Raman spectroscopy under static equilibrium at temperatures of 175-430 °C and coverages in the 0.40-5.5 V nm-2 range. It is found that the dispersed (VOx)n phase consists of distinct species with different configurations. At low coverages of 0.40 and 0.74 V nm-2, isolated (monomeric) species prevail. Two distinct mono-oxo species are found: (i) a majority Species-I, presumably of distorted tetrahedral OV(-O-)3 configuration with VO mode at 1022-1024 cm-1 and (ii) a minority Species-II, presumably of distorted octahedral-like OV(-O-)4 configuration with VO mode at 1013-1014 cm-1. Cycling the catalysts in the 430 → 250 → 175 → 430 °C sequence results in temperature-dependent structural transformations. With decreasing temperature, a Species-II → Species-I transformation with concomitant surface hydroxylation takes place by means of a hydrolysis mechanism mediated by water molecules retained by the surface. A third species (Species-III, presumably of di-oxo configuration with νs/νas at ∼995/985 cm-1) occurs in minority and its presence is increased when further lowering the temperature according to a Species-I → Species-III hydrolysis step. Species-II (OV(-O-)4) shows the highest reactivity to water. For coverages above 1 V nm-2, an association of VOx units takes place leading to gradually larger polymeric domains when the coverage is increased in the 1.1-5.5 V nm-2 range. Polymeric (VOx)n domains comprise building units that maintain the structural characteristics (termination configuration and V coordination number) of Species-I, Species-II, and Species-III. The terminal VO stretching modes are blue-shifted with increasing (VOx)n domain size. A lower extent of hydroxylation is evidenced under static equilibrium forced dehydrated conditions, thereby limiting the temperature dependent structural transformations and excluding the possibility of incoming water vapors as the cause for the temperature dependent effects observed in the in situ Raman/FTIR spectra. The results address open issues and offer new insight in the structural studies of VOx/TiO2 catalysts.
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Affiliation(s)
- Theocharis Kentri
- Department of Chemical Engineering, University of Patras, Patras, Greece.
- Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras, Greece
| | - Athanasios Tsevis
- School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
| | - Soghomon Boghosian
- Department of Chemical Engineering, University of Patras, Patras, Greece.
- Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras, Greece
- School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
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Johnston-Peck AC, Maier RA. Adlayer formation on C-plane (0001) and R-plane ( 1 1 ‒ 0 2 ) Al 2O 3 surfaces. JOURNAL OF THE AMERICAN CERAMIC SOCIETY. AMERICAN CERAMIC SOCIETY 2023; 106:1490-1499. [PMID: 36761689 PMCID: PMC9903351 DOI: 10.1111/jace.18814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 09/17/2022] [Indexed: 06/18/2023]
Abstract
Adlayers on C-plane (0001) and R-plane ( 1 1 ‒ 02 ) terminated surfaces of corundum phase aluminum oxide were synthesized by annealing mixtures of two oxide powders, aluminum oxide with an additive. Using high-angle annular dark field scanning transmission electron microscopy, the adsorbed layers were characterized, and image simulations aided interpretation of the results. The adlayers were pseudomorphic, one atomic layer thick and with a fractional site occupancy. Atomic positions of the adlayer atoms relaxed and changed relative to the bulk structure, where there is evidence that the magnitude of the relaxation is sensitive to the ionic radius of the adsorbate. The pseudomorphic adlayer structure formed for different elements including, but not limited to, the lanthanides (i.e., Ge, Ba and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm).
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Affiliation(s)
- Aaron C Johnston-Peck
- Material Measurement Laboratory National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 United States
| | - Russell A Maier
- Material Measurement Laboratory National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 United States
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Drozdov EO, Buzina DV, Malkov AA, Malygin AA. Quantum Chemical Simulation of Polycondensation Processes of Vanadium Oxide Structures on Silica Surface. RUSS J GEN CHEM+ 2022. [DOI: 10.1134/s1070363222120398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Kentri T, Trimpalis A, Misa A, Kordouli E, Ramantani T, Boghosian S. Rethinking the molecular structures of W VIO x sites dispersed on titania: distinct mono-oxo configurations at 430 °C and temperature-dependent transformations. Dalton Trans 2022; 51:7455-7475. [PMID: 35466984 DOI: 10.1039/d2dt00595f] [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 structural properties of the (WOx)n phase dispersed on TiO2 (P25, anatase) at surface densities of 0.5-4.5 W nm-2 (i.e. up to approximately a monolayer) were explored by using in situ Raman and FTIR spectroscopy, in situ Raman/18O exchange and Raman spectroscopy in static equilibrium at temperatures of 175-430 °C. Deciphering the temperature and coverage dependence of the spectral features under oxidative dehydration conditions showed that (i) the (WOx)n dispersed phase is heterogeneous at 430 °C consisting of two distinct mono-oxo species: Species-I with C3v-like OW(-O-)3 configuration (WO mode at 1009-1014 cm-1) and Species-II with C4v-like OW(-O-)4 configuration (WO mode at 1003-1009 cm-1); (ii) the OW(-O-)3 site is formed with first order of priority and its formation ceases after the complete consumption of the most basic hydroxyls that are titrated first, hence is abundant at low coverage (<1.5 W nm-2); (iii) the OW(-O-)4 site prevails over the OW(-O-)3 site at medium to high coverage (≥2 W nm-2) and partially occurs in associated (polymerized) coverages above 2 W nm-2; (iv) lowering the temperature in the 430 → 250 → 175 °C sequence does not affect the structural and vibrational properties of OW(-O-)3 but leads to the gradual transformation of the OW(-O-)4 site to a di-oxo (O)2W(-O-)3 site (with a symmetric stretching mode at ∼985 cm-1) and the partial association of adjacent OW(-O-)4 units. All temperature-dependent structural/configurational transformations are fully reversible in the 430-175 °C range and are interpreted at the molecular level by a mechanism involving water molecules retained at the surface that act in a reversible temperature-dependent mediative manner resulting in hydroxylation (upon cooling, e.g. to 250 °C) and dehydroxylation (upon heating, e.g. to 430 °C). The Raman spectra obtained for the hydroxyl region confirm the successive hydroxylation/dehydroxylation steps during temperature cycles (e.g. 430 → 250 → 430 °C). One can tune the speciation of the dispersed (WOx)n phase under dehydrated conditions by appropriate control of temperature and coverage.
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Affiliation(s)
- Theocharis Kentri
- Department of Chemical Engineering, University of Patras, Patras, Greece. .,Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras, Greece
| | - Antonios Trimpalis
- Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - Adam Misa
- Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - Eleana Kordouli
- Department of Chemistry, University of Patras, Patras, Greece
| | - Theodora Ramantani
- Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - Soghomon Boghosian
- Department of Chemical Engineering, University of Patras, Patras, Greece. .,Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras, Greece.,School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
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8
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Glotov A, Vutolkina A, Vinogradov N, Pimerzin A, Vinokurov V, Pimerzin A. Enhanced HDS and HYD activity of sulfide Co-PMo catalyst supported on alumina and structured mesoporous silica composite. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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9
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Kortewille B, Pfingsten O, Bacher G, Strunk J. Supported Vanadium Oxide as a Photocatalyst in the Liquid Phase: Dissolution Studies and Selective Laser Excitation. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Bianca Kortewille
- Leibniz Institute for Catalysis at the University of Rostock 18059 Rostock Germany
- Pilkington Holding GmbH R&D Building Products Haydnstr. 19 45884 Gelsenkirchen Germany
| | - Oliver Pfingsten
- Werkstoffe der Elektrotechnik and Center for Nanointegration Duisburg-Essen (CENIDE) Universität Duisburg-Essen 47057 Duisburg Germany
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and Center for Nanointegration Duisburg-Essen (CENIDE) Universität Duisburg-Essen 47057 Duisburg Germany
| | - Jennifer Strunk
- Leibniz Institute for Catalysis at the University of Rostock 18059 Rostock Germany
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11
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Sprenger P, Stehle M, Gaur A, Weiß J, Brueckner D, Zhang Y, Garrevoet J, Suuronen J, Thomann M, Fischer A, Grunwaldt J, Sheppard TL. Chemical Imaging of Mixed Metal Oxide Catalysts for Propylene Oxidation: From Model Binary Systems to Complex Multicomponent Systems. ChemCatChem 2021. [DOI: 10.1002/cctc.202100054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Paul Sprenger
- Institute for Chemical Technology and Polymer Chemistry Karlsruhe Institute of Technology Karlsruhe 76131 Germany
| | - Matthias Stehle
- Institute for Chemical Technology and Polymer Chemistry Karlsruhe Institute of Technology Karlsruhe 76131 Germany
| | - Abhijeet Gaur
- Institute for Chemical Technology and Polymer Chemistry Karlsruhe Institute of Technology Karlsruhe 76131 Germany
- Institute of Catalysis Research and Technology Karlsruhe Institute of Technology Eggenstein-Leopoldshafen 76344 Germany
| | - Jana Weiß
- Leibniz Institute for Catalysis (LIKAT) Rostock 18059 Germany
| | - Dennis Brueckner
- Deutsches Elektronen-Synchrotron DESY Hamburg 22607 Germany
- Faculty of Chemistry and Biochemistry Ruhr University Bochum Bochum 44801 Germany
- Department Physik Universität Hamburg Hamburg 22761 Germany
| | - Yi Zhang
- Deutsches Elektronen-Synchrotron DESY Hamburg 22607 Germany
| | - Jan Garrevoet
- Deutsches Elektronen-Synchrotron DESY Hamburg 22607 Germany
| | - Jussi‐Petteri Suuronen
- ESRF - The European Synchrotron Grenoble 38000 France
- Current Address: Xploraytion GmbH Berlin 10625 Germany
| | | | | | - Jan‐Dierk Grunwaldt
- Institute for Chemical Technology and Polymer Chemistry Karlsruhe Institute of Technology Karlsruhe 76131 Germany
- Institute of Catalysis Research and Technology Karlsruhe Institute of Technology Eggenstein-Leopoldshafen 76344 Germany
| | - Thomas L. Sheppard
- Institute for Chemical Technology and Polymer Chemistry Karlsruhe Institute of Technology Karlsruhe 76131 Germany
- Institute of Catalysis Research and Technology Karlsruhe Institute of Technology Eggenstein-Leopoldshafen 76344 Germany
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12
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Insights on alkylidene formation on Mo2C: A potential overlap between direct deoxygenation and olefin metathesis. J Catal 2021. [DOI: 10.1016/j.jcat.2020.11.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hess C. New advances in using Raman spectroscopy for the characterization of catalysts and catalytic reactions. Chem Soc Rev 2021; 50:3519-3564. [PMID: 33501926 DOI: 10.1039/d0cs01059f] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Gaining insight into the mode of operation of heterogeneous catalysts is of great scientific and economic interest. Raman spectroscopy has proven its potential as a powerful vibrational spectroscopic technique for a fundamental and molecular-level characterization of catalysts and catalytic reactions. Raman spectra provide important insight into reaction mechanisms by revealing specific information on the catalysts' (defect) structure in the bulk and at the surface, as well as the presence of adsorbates and reaction intermediates. Modern Raman instrumentation based on single-stage spectrometers allows high throughput and versatility in design of in situ/operando cells to study working catalysts. This review highlights major advances in the use of Raman spectroscopy for the characterization of heterogeneous catalysts made during the past decade, including the development of new methods and potential directions of research for applying Raman spectroscopy to working catalysts. The main focus will be on gas-solid catalytic reactions, but (photo)catalytic reactions in the liquid phase will be touched on if it appears appropriate. The discussion begins with the main instrumentation now available for applying vibrational Raman spectroscopy to catalysis research, including in situ/operando cells for studying gas-solid catalytic processes. The focus then moves to the different types of information available from Raman spectra in the bulk and on the surface of solid catalysts, including adsorbates and surface depositions, as well as the use of theoretical calculations to facilitate band assignments and to describe (resonance) Raman effects. This is followed by a presentation of major developments in enhancing the Raman signal of heterogeneous catalysts by use of UV resonance Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), and shell-isolated nanoparticle surface-enhanced Raman spectroscopy (SHINERS). The application of time-resolved Raman studies to structural and kinetic characterization is then discussed. Finally, recent developments in spatially resolved Raman analysis of catalysts and catalytic processes are presented, including the use of coherent anti-Stokes Raman spectroscopy (CARS) and tip-enhanced Raman spectroscopy (TERS). The review concludes with an outlook on potential future developments and applications of Raman spectroscopy in heterogeneous catalysis.
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Affiliation(s)
- Christian Hess
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, 64287, Darmstadt, Germany.
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Increasing the Efficiency of Optimized V-SBA-15 Catalysts in the Selective Oxidation of Methane to Formaldehyde by Artificial Neural Network Modelling. Catalysts 2020. [DOI: 10.3390/catal10121411] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The present study investigates the possibility of improving the selective oxidation of methane to formaldehyde over V-SBA-15 catalysts in two different ways. In a classical approach of catalyst optimization, the in situ synthesis of V-SBA-15 catalysts was optimized with regard to the applied pH value. Among the set of catalysts synthesized, a higher amount of incorporated vanadium, a higher content of polymeric VOx species as well as a less ordered structure of the support material were observed by increasing the pH values from 2.0 to 3.0. An optimum in performance during the selective oxidation of methane to formaldehyde with respect to activity and selectivity was found over V-SBA-15 prepared at a pH value of 2.5. With this knowledge, we have now evaluated the possibilities of reaction control using this catalyst. Specifically, artificial neural network modelling was applied after the collection of 232 training samples for obtaining insight into the influence of different reaction parameters (temperature; gas hourly space velocity (GHSV); and concentration of O2, N2 and H2O) onto methane conversion and selectivity towards formaldehyde. This optimization of reaction conditions resulted in an outstanding high space-time yield of 13.6 kgCH2O∙kgcat∙h−1.
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15
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Andriopoulou C, Boghosian S. Molecular structure and termination configuration of Oxo-Re(VII) catalyst sites supported on Titania. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.06.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Drozdov EO, Dubrovenskii SD, Malygin AA. Quantum Chemical Analysis of the Processes of Synthesis of
Vanadium Oxide Structures on the Silica Surface. RUSS J GEN CHEM+ 2020. [DOI: 10.1134/s1070363220050217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Promoter Effects on Catalyst Selectivity and Stability for Propylene Partial Oxidation to Acrolein. Catal Letters 2020. [DOI: 10.1007/s10562-019-02969-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Andriopoulou C, Boghosian S. Tuning the configuration of dispersed oxometallic sites in supported transition metal oxide catalysts: A temperature dependent Raman study. Catal Today 2019. [DOI: 10.1016/j.cattod.2019.01.080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Lang M, Klahn M, Strunk J. Photophysical and Catalytic Properties of Silica Supported Early Transition Metal Oxides Relevant for Photocatalytic Applications. Catal Letters 2019. [DOI: 10.1007/s10562-019-02803-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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20
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Combination of Chemo- and Biocatalysis: Conversion of Biomethane to Methanol and Formic Acid. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9142798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the present day, methanol is mainly produced from methane via reforming processes, but research focuses on alternative production routes. Herein, we present a chemo-/biocatalytic oxidation cascade as a novel process to currently available methods. Starting from synthetic biogas, in the first step methane was oxidized to formaldehyde over a mesoporous VOx/SBA-15 catalyst. In the second step, the produced formaldehyde was disproportionated enzymatically towards methanol and formic acid in equimolar ratio by formaldehyde dismutase (FDM) obtained from Pseudomonas putida. Two processing routes were demonstrated: (a) batch wise operation using free formaldehyde dismutase after accumulating formaldehyde from the first step and (b) continuous operation with immobilized enzymes. Remarkably, the chemo-/biocatalytic oxidation cascades generate methanol in much higher productivity compared to methane monooxygenase (MMO) which, however, directly converts methane. Moreover, production steps for the generation of formic acid were reduced from four to two stages.
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Kiani D, Sourav S, Baltrusaitis J, Wachs IE. Oxidative Coupling of Methane (OCM) by SiO2-Supported Tungsten Oxide Catalysts Promoted with Mn and Na. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01585] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniyal Kiani
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Sagar Sourav
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Jonas Baltrusaitis
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Israel E. Wachs
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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22
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Marcelino RBP, Amorim CC. Towards visible-light photocatalysis for environmental applications: band-gap engineering versus photons absorption-a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:4155-4170. [PMID: 30238261 DOI: 10.1007/s11356-018-3117-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 08/31/2018] [Indexed: 06/08/2023]
Abstract
A range of different studies has been performed in order to design and develop photocatalysts that work efficiently under visible (and near-infrared) irradiation as well as to improve photons absorption with improved reactor design. While there is consensus on the importance of photocatalysis for environmental applications and the necessity to utilized solar irradiation (or visible-light) as driving force for these processes, it is not yet clear how to get there. Discussion on the future steps towards visible-light photocatalysis for environmental application is of great interest to scientific and industrial communities and the present paper reviews and discusses the two main approaches, band-gap engineering for efficient solar-activated catalysts and reactor designs for improved photons absorption. Common misconceptions and drawbacks of each technology are also examined together with insights for future progress.
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Affiliation(s)
- Rafaela B P Marcelino
- Research Group on Environmental Applications of Advanced Oxidation Processes, Graduate Program in Sanitation, Environment and Water Resources, School of Engineering, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, Brazil
| | - Camila C Amorim
- Research Group on Environmental Applications of Advanced Oxidation Processes, Graduate Program in Sanitation, Environment and Water Resources, School of Engineering, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, Brazil.
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23
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Kortewille B, Wachs IE, Cibura N, Pfingsten O, Bacher G, Muhler M, Strunk J. Photocatalytic Methanol Oxidation by Supported Vanadium Oxide Species: Influence of Support and Degree of Oligomerization. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800490] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Bianca Kortewille
- Heterogene Photokatalyse Leibniz‐Institut für Katalyse e. V. an der Universität Rostock 18059 Rostock Germany
- Lehrstuhl für Technische Chemie Ruhr‐Universität Bochum 44801 Bochum Germany
| | - Israel E. Wachs
- Operando Molecular Spectroscopy & Catalysis Lab Lehigh University 18015‐3128 Bethlehem PA USA
| | - Niklas Cibura
- AG Nanobasierte Heterogene Katalysatoren Max‐Planck‐Institut für Chemische Energiekonversion 45470 Mülheim/Ruhr Germany
| | - Oliver Pfingsten
- Werkstoffe der Elektrotechnik, and Center for Nanointegration Duisburg‐Essen (CENIDE) Universität Duisburg‐Essen 47057 Duisburg Germany
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik, and Center for Nanointegration Duisburg‐Essen (CENIDE) Universität Duisburg‐Essen 47057 Duisburg Germany
| | - Martin Muhler
- Lehrstuhl für Technische Chemie Ruhr‐Universität Bochum 44801 Bochum Germany
| | - Jennifer Strunk
- Heterogene Photokatalyse Leibniz‐Institut für Katalyse e. V. an der Universität Rostock 18059 Rostock Germany
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24
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Andrushkevich TV, Chesalov YA. Mechanism of heterogeneous catalytic oxidation of organic compounds to carboxylic acids. RUSSIAN CHEMICAL REVIEWS 2018. [DOI: 10.1070/rcr4779] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The results of studies on the mechanism of heterogeneous catalytic oxidation of organic compounds of different chemical structure to carboxylic acids are analyzed and generalized. The concept developed by Academician G.K.Boreskov, according to which the direction of the reaction is governed by the structure and bond energy of surface intermediates, was confirmed taking the title processes as examples. Quantitative criteria of the bond energies of surface compounds of oxidizable reactants, reaction products and oxygen that determine the selective course of the reaction are presented.
The bibliography includes 195 references.
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25
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Sprenger P, Stehle M, Gaur A, Gänzler AM, Gashnikova D, Kleist W, Grunwaldt JD. Reactivity of Bismuth Molybdates for Selective Oxidation of Propylene Probed by Correlative Operando Spectroscopies. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00696] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul Sprenger
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Matthias Stehle
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Abhijeet Gaur
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Andreas Martin Gänzler
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Daria Gashnikova
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Wolfgang Kleist
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Jan-Dierk Grunwaldt
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
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26
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Andriopoulou C, Boghosian S. Heterogeneity of deposited phases in supported transition metal oxide catalysts: reversible temperature-dependent evolution of molecular structures and configurations. Phys Chem Chem Phys 2018; 20:1742-1751. [DOI: 10.1039/c7cp07286d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reversible temperature-dependent structural transformations of oxometallic species deposited at low submonolayer coverage on titania(P25).
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Affiliation(s)
| | - Soghomon Boghosian
- Department of Chemical Engineering
- University of Patras
- Patras
- Greece
- FORTH/ICE-HT
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