Pub Date : 2017-10-02DOI: 10.1080/2055074X.2017.1414345
Y. Hao, F. Cárdenas-Lizana, M. Keane
Abstract We report the catalytic gas phase hydrogenation of p-nitrobenzonitrile (p-NBN) to p-aminobenzonitrile (p-ABN) over a series of oxide (CeO2, Fe2O3, Fe3O4, TiO2, ZrO2 and Al2O3) supported (1 mol%) Au catalysts (mean size 3–8 nm from electron microscopy). Hydrogenation rate was structure sensitive with lower turnover frequencies (TOF) over larger Au nanoparticles in the 4–8 nm interval and a decrease in TOF for Au ≤ 3 nm. This size dependence also applies to H2 chemisorption under reaction conditions. Rate normalised with respect to H2 uptake showed a dependence on support redox potential where the formation of oxygen vacancies (from O2 titration) served to stabilise the −NO2 group, lowering reactivity. Reaction over Au/TiO2 with modified electronic character (from XPS) deviated from this trend and delivered the highest specific hydrogenation rate, which is attributed to –NO2 activation at the Au-TiO2 interface; this effect extends to TiO2 supported Ag and Pd.
{"title":"Gas phase chemoselective hydrogenation of p-nitrobenzonitrile over gold: effect of metal particle size, support and the metal-support interface","authors":"Y. Hao, F. Cárdenas-Lizana, M. Keane","doi":"10.1080/2055074X.2017.1414345","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1414345","url":null,"abstract":"Abstract We report the catalytic gas phase hydrogenation of p-nitrobenzonitrile (p-NBN) to p-aminobenzonitrile (p-ABN) over a series of oxide (CeO2, Fe2O3, Fe3O4, TiO2, ZrO2 and Al2O3) supported (1 mol%) Au catalysts (mean size 3–8 nm from electron microscopy). Hydrogenation rate was structure sensitive with lower turnover frequencies (TOF) over larger Au nanoparticles in the 4–8 nm interval and a decrease in TOF for Au ≤ 3 nm. This size dependence also applies to H2 chemisorption under reaction conditions. Rate normalised with respect to H2 uptake showed a dependence on support redox potential where the formation of oxygen vacancies (from O2 titration) served to stabilise the −NO2 group, lowering reactivity. Reaction over Au/TiO2 with modified electronic character (from XPS) deviated from this trend and delivered the highest specific hydrogenation rate, which is attributed to –NO2 activation at the Au-TiO2 interface; this effect extends to TiO2 supported Ag and Pd.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1414345","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49347569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-02DOI: 10.1080/2055074x.2017.1336869
{"title":"Obituary for Professor Ken Waugh (1941–2017)","authors":"","doi":"10.1080/2055074x.2017.1336869","DOIUrl":"https://doi.org/10.1080/2055074x.2017.1336869","url":null,"abstract":"","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074x.2017.1336869","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47206267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-08-10DOI: 10.1080/2055074X.2017.1344793
J. Manna, Binayak Roy, D. Pareek, Pratibha Sharma
Abstract Aluminium phosphate and bentonite supported Co-B catalyst were synthesized via two step impregnation-reduction method for sodium borohydride hydrolysis. The synthesized catalysts were characterized by XRD, FTIR, XPS, FE-SEM, FE-TEM, BET, ICP-AES techniques and tested for NaBH4 hydrolysis reaction. The results demonstrated that the synthesized supported Co-B catalysts greatly facilitate the NaBH4 hydrolysis reaction. Highest hydrolysis rate observed for Co-B/AlPO4 and Co-B/bentonite catalysts are 6.50 and 3.91 L min−1 g−1, respectively, with 2 wt% NaBH4, 5 wt% NaOH solution at 30 °C. The hydrogen generation rate was found to increase with experimental temperature. Activation energy for the hydrolysis reaction was observed to be 37 and 40.2 kJ mol−1 for Co-B/AlPO4 and Co-B/bentonite catalysts, respectively.
摘要采用两步浸渍还原法制备了磷酸铝和膨润土负载的Co-B催化剂，用于硼氢化钠水解。采用XRD、FTIR、XPS、FE-SEM、FE-TEM、BET、ICP-AES等技术对合成的催化剂进行了表征，并对NaBH4的水解反应进行了测试。结果表明，所合成的负载型Co-B催化剂对NaBH4的水解反应有较好的促进作用。在30°C条件下，Co-B/AlPO4和Co-B/膨润土催化剂的水解率分别为6.50和3.91 L min - 1 g - 1，分别为2 wt% NaBH4和5 wt% NaOH。产氢速率随实验温度的升高而升高。Co-B/AlPO4和Co-B/膨润土催化剂的水解活化能分别为37和40.2 kJ mol−1。
{"title":"Hydrogen generation from NaBH4 hydrolysis using Co-B/AlPO4 and Co-B/bentonite catalysts","authors":"J. Manna, Binayak Roy, D. Pareek, Pratibha Sharma","doi":"10.1080/2055074X.2017.1344793","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1344793","url":null,"abstract":"Abstract Aluminium phosphate and bentonite supported Co-B catalyst were synthesized via two step impregnation-reduction method for sodium borohydride hydrolysis. The synthesized catalysts were characterized by XRD, FTIR, XPS, FE-SEM, FE-TEM, BET, ICP-AES techniques and tested for NaBH4 hydrolysis reaction. The results demonstrated that the synthesized supported Co-B catalysts greatly facilitate the NaBH4 hydrolysis reaction. Highest hydrolysis rate observed for Co-B/AlPO4 and Co-B/bentonite catalysts are 6.50 and 3.91 L min−1 g−1, respectively, with 2 wt% NaBH4, 5 wt% NaOH solution at 30 °C. The hydrogen generation rate was found to increase with experimental temperature. Activation energy for the hydrolysis reaction was observed to be 37 and 40.2 kJ mol−1 for Co-B/AlPO4 and Co-B/bentonite catalysts, respectively.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1344793","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44973659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-08-02DOI: 10.1080/2055074X.2017.1348711
M. Newton, R. Nicholls, J. Brazier, B. Nguyen, Christopher J. Mulligan, K. Hellgardt, Elena M. Barreiro, H. Emerich, K. K. Hii, I. Snigireva, P. Thompson
Abstract In situ X-ray absorption spectroscopy (XAS) and Pd K, LIII, and Cl K-edges shows that Cl can be present in significant amounts in ENCAT™ 30 catalysts and that it can severely retard Pd nanoparticle (NP) development in flowing solvents. We also show that whilst polymeric encapsulation protects the Pd against solvent induced agglomeration of Pd nanoparticles the evidence suggests it does not prevent the formation PdHx through reaction with the aqeous ethanol solvent, and that, as received, ENCAT™ 30 NP catalysts are not, for the most part, comprised of nanoparticulate Pd0 irrespective of the presence of Cl.
{"title":"Effect of retained chlorine in ENCAT™ 30 catalysts on the development of encapsulated Pd: insights from in situ Pd K, L3 and Cl K-edge XAS","authors":"M. Newton, R. Nicholls, J. Brazier, B. Nguyen, Christopher J. Mulligan, K. Hellgardt, Elena M. Barreiro, H. Emerich, K. K. Hii, I. Snigireva, P. Thompson","doi":"10.1080/2055074X.2017.1348711","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1348711","url":null,"abstract":"Abstract In situ X-ray absorption spectroscopy (XAS) and Pd K, LIII, and Cl K-edges shows that Cl can be present in significant amounts in ENCAT™ 30 catalysts and that it can severely retard Pd nanoparticle (NP) development in flowing solvents. We also show that whilst polymeric encapsulation protects the Pd against solvent induced agglomeration of Pd nanoparticles the evidence suggests it does not prevent the formation PdHx through reaction with the aqeous ethanol solvent, and that, as received, ENCAT™ 30 NP catalysts are not, for the most part, comprised of nanoparticulate Pd0 irrespective of the presence of Cl.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1348711","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43801128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-31DOI: 10.1080/2055074X.2017.1327472
G. V. Shiva Reddy, M. Chandrappa, V. N. Padmanabha Gowda, Fazlur Rahaman, S. G. Kumar, B. Narasimha Murthy, P. K. Pullela
Abstract Broad spectrum pesticides are molecules which act across a range of pests. The popular class of compounds with this property are thiacloprid, nitenpyram, ethaboxam, silthiofam, 3,3,4,4-tetrachloro tetrahydro thiophene etc. Interestingly, all these compounds possess at least one heterocyclic ring like thiophene, furan, and imidazole etc. in their structure. Among the synthons available for synthesis of neonicotinoids, tetrachlorothiophene is unique. The bulk scale synthesis of tetrachlorothiophene is reported only by cyclization of hexachloro-1,3-butadiene. The reaction yields of synthesis of this synthon are around 45%. We report silica-coated magnetic nanoparticles as a generic catalyst for this cyclization reaction yielding tetrachlorothiophene. The yield improvement is 50–60% more compared to original yield. The distillate crystallization in methanol yielded >98% pure compound compared to typical 90–92% in conventional process. The proposed reaction uses reusable silica-coated 40 nm size magnetic nanoparticles and the catalyst itself is of low cost and reaction conditions are mild.
{"title":"Efficient bulk scale synthesis of popular pesticide synthon: tetrachlorothiophene","authors":"G. V. Shiva Reddy, M. Chandrappa, V. N. Padmanabha Gowda, Fazlur Rahaman, S. G. Kumar, B. Narasimha Murthy, P. K. Pullela","doi":"10.1080/2055074X.2017.1327472","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1327472","url":null,"abstract":"Abstract Broad spectrum pesticides are molecules which act across a range of pests. The popular class of compounds with this property are thiacloprid, nitenpyram, ethaboxam, silthiofam, 3,3,4,4-tetrachloro tetrahydro thiophene etc. Interestingly, all these compounds possess at least one heterocyclic ring like thiophene, furan, and imidazole etc. in their structure. Among the synthons available for synthesis of neonicotinoids, tetrachlorothiophene is unique. The bulk scale synthesis of tetrachlorothiophene is reported only by cyclization of hexachloro-1,3-butadiene. The reaction yields of synthesis of this synthon are around 45%. We report silica-coated magnetic nanoparticles as a generic catalyst for this cyclization reaction yielding tetrachlorothiophene. The yield improvement is 50–60% more compared to original yield. The distillate crystallization in methanol yielded >98% pure compound compared to typical 90–92% in conventional process. The proposed reaction uses reusable silica-coated 40 nm size magnetic nanoparticles and the catalyst itself is of low cost and reaction conditions are mild.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1327472","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46440949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-04-26DOI: 10.1080/2055074X.2017.1281718
M. Bainbridge, J. Clarkson, B. L. Parnham, J. Tabatabaei, D. V. Tyers, K. Waugh
Abstract Cobalt supported on a number of different metal oxides are often used in the Fischer–Tropsch (FT) reaction. No obvious rationale for the composition of the metal oxide used exists. In this paper we examine the possibility that some form of interaction between the metal and the metal oxide support exists which enhances the activity of the Co metal. To this effect, we have supported Co metal on a series of metal oxides of different degrees of reducibility: (i) Al2O3 which is unreducible under FT conditions, (ii) ZrO2 which can be reduced to a small extent under FT conditions, and (iii) ZnO which can be reduced to a measurable degree under FT conditions. The postulate was that the more reducible support will have the greater number of trapped electrons at anion vacancies, and so will have the greater possibility of transferring these electrons from the support to the metal, giving rise to a sequentially greater metal/metal oxide interaction. We have previously shown that temperature programmed desorption/decomposition of formate species adsorbed on Cu/ZnO/Al2O3 (methanol synthesis catalysts) has been able to identify adsorption sites on: (i) the Cu metal, (ii) the ZnO, (iii) Al2O3 and (iv) at the Cu/ZnO interface. Here we have used the same probe reaction, namely the adsorption and temperature programmed desorption/decomposition of a formate species, to identify and predict the extent of metal/metal oxide interaction. The whole system, the kinetics of the decomposition of the formate used, and the different forms of metal oxide support used constituted a predictive possibility of what would constitute an active metal oxide supported Co catalyst on (i) Co supported on Al2O3, on (ii) Co supported on ZrO2 and (iii) on Co supported on ZnO. The ZnO support is shown to provide the greatest extent of charge transfer from the support to the Co, evidenced by the lowest temperature for desorption/decomposition of the formate of all the supports used, and the largest amount of CO in the product spectrum. The in situ N2O reactive frontal chromatography measurement of the Co metal area showed the formate species to be closely packed on the Co. Schematic diagram of closely packed formate species on Co, showing the overlap of the electron charge clouds, demonstrating the possibility of reaction between neighbouring formate strands (red balls: O atoms, grey balls: C atoms, white balls: H atoms and blue balls: Co atoms)
{"title":"Evidence for support effects in metal oxide supported cobalt catalysts","authors":"M. Bainbridge, J. Clarkson, B. L. Parnham, J. Tabatabaei, D. V. Tyers, K. Waugh","doi":"10.1080/2055074X.2017.1281718","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1281718","url":null,"abstract":"Abstract Cobalt supported on a number of different metal oxides are often used in the Fischer–Tropsch (FT) reaction. No obvious rationale for the composition of the metal oxide used exists. In this paper we examine the possibility that some form of interaction between the metal and the metal oxide support exists which enhances the activity of the Co metal. To this effect, we have supported Co metal on a series of metal oxides of different degrees of reducibility: (i) Al2O3 which is unreducible under FT conditions, (ii) ZrO2 which can be reduced to a small extent under FT conditions, and (iii) ZnO which can be reduced to a measurable degree under FT conditions. The postulate was that the more reducible support will have the greater number of trapped electrons at anion vacancies, and so will have the greater possibility of transferring these electrons from the support to the metal, giving rise to a sequentially greater metal/metal oxide interaction. We have previously shown that temperature programmed desorption/decomposition of formate species adsorbed on Cu/ZnO/Al2O3 (methanol synthesis catalysts) has been able to identify adsorption sites on: (i) the Cu metal, (ii) the ZnO, (iii) Al2O3 and (iv) at the Cu/ZnO interface. Here we have used the same probe reaction, namely the adsorption and temperature programmed desorption/decomposition of a formate species, to identify and predict the extent of metal/metal oxide interaction. The whole system, the kinetics of the decomposition of the formate used, and the different forms of metal oxide support used constituted a predictive possibility of what would constitute an active metal oxide supported Co catalyst on (i) Co supported on Al2O3, on (ii) Co supported on ZrO2 and (iii) on Co supported on ZnO. The ZnO support is shown to provide the greatest extent of charge transfer from the support to the Co, evidenced by the lowest temperature for desorption/decomposition of the formate of all the supports used, and the largest amount of CO in the product spectrum. The in situ N2O reactive frontal chromatography measurement of the Co metal area showed the formate species to be closely packed on the Co. Schematic diagram of closely packed formate species on Co, showing the overlap of the electron charge clouds, demonstrating the possibility of reaction between neighbouring formate strands (red balls: O atoms, grey balls: C atoms, white balls: H atoms and blue balls: Co atoms)","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1281718","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46143639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-22DOI: 10.1080/2055074X.2017.1278870
S. Parker, Celine Carias, J. Tomkinson
Abstract Butadiene potentially exhibits many different modes of bonding to a surface, the aim of this work is to fully characterise how the spectrum of the s-cis conformer changes on coordination. A model complex, C4H6Fe(CO)3 and its deuterated isotopomer, was studied with infrared, Raman and inelastic neutron scattering (INS) spectroscopies and has provided a definitive set of assignments for the ligand. These differ in many respects from previous work that was solely based on empirical correlations. The use of INS spectroscopy has allowed observation of several of the low energy modes for the first time, the most significant of which is the C1–C1′ torsion at 485 cm−1. The comparison of observed and calculated infrared spectra for butadiene on silica confirms the surprising assignment that the molecule is adsorbed as the gauche form.
{"title":"Vibrational spectra of buta-1,3-diene iron tricarbonyl: comparison to surface species","authors":"S. Parker, Celine Carias, J. Tomkinson","doi":"10.1080/2055074X.2017.1278870","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1278870","url":null,"abstract":"Abstract Butadiene potentially exhibits many different modes of bonding to a surface, the aim of this work is to fully characterise how the spectrum of the s-cis conformer changes on coordination. A model complex, C4H6Fe(CO)3 and its deuterated isotopomer, was studied with infrared, Raman and inelastic neutron scattering (INS) spectroscopies and has provided a definitive set of assignments for the ligand. These differ in many respects from previous work that was solely based on empirical correlations. The use of INS spectroscopy has allowed observation of several of the low energy modes for the first time, the most significant of which is the C1–C1′ torsion at 485 cm−1. The comparison of observed and calculated infrared spectra for butadiene on silica confirms the surprising assignment that the molecule is adsorbed as the gauche form.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1278870","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41923051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-03DOI: 10.1080/2055074X.2017.1280641
W. Onderwaater, O. Balmes, S. Roobol, M. V. van Spronsen, J. Drnec, F. Carlá, R. Felici, J. Frenken
Abstract Under particular temperature and gas conditions the reactivity of the Pd(1 0 0) surface toward CO oxidation exhibits oscillatory behaviour. Here we examine the surface structure of this model catalyst and show that the periodic pattern is more complex than previously reported and that superimposed on the overall oscillation much faster structural variations are present. By examining the structure of the sample surface at high temporal resolution we conclude that the structure of the oxide layer present at the surface evolves continuously toward a more disordered phase in agreement with the Mars-Van Krevelen reaction mechanism.
{"title":"Oxidation of CO on Pd(1 0 0): on the structural evolution of the PdO layer during the self sustained oscillation regime","authors":"W. Onderwaater, O. Balmes, S. Roobol, M. V. van Spronsen, J. Drnec, F. Carlá, R. Felici, J. Frenken","doi":"10.1080/2055074X.2017.1280641","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1280641","url":null,"abstract":"Abstract Under particular temperature and gas conditions the reactivity of the Pd(1 0 0) surface toward CO oxidation exhibits oscillatory behaviour. Here we examine the surface structure of this model catalyst and show that the periodic pattern is more complex than previously reported and that superimposed on the overall oscillation much faster structural variations are present. By examining the structure of the sample surface at high temporal resolution we conclude that the structure of the oxide layer present at the surface evolves continuously toward a more disordered phase in agreement with the Mars-Van Krevelen reaction mechanism.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1280641","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46664325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-03DOI: 10.1080/2055074X.2017.1287535
M. Hävecker, Pascal Düngen, S. Buller, A. Knop‐Gericke, A. Trunschke, R. Schlögl
Abstract A series of vanadia catalysts supported on mesoporous silica SBA-15 has been prepared with a loading in the range of 2–14 wt-% V and characterized under oxygen and propane oxidative dehydrogenation reaction conditions at elevated temperature up to 550 °C. In situ soft X-ray absorption spectra at the vanadium L- and oxygen K-edges and in situ synchrotron based X-ray photoemission spectra reveal a restructuring of vanadium species that results in an enhanced degree of dispersion of molecular vanadia species on the silica support. The impact of the X-ray beam on the XAS spectra of dispersed VxOy species has been studied and a brief perspective of X-ray based electron spectroscopy as a probe in catalyst characterization is given.
{"title":"Restructuring of silica supported vanadia during propane oxidative dehydrogenation studied by combined synchrotron radiation based in situ soft X-ray absorption and photoemission","authors":"M. Hävecker, Pascal Düngen, S. Buller, A. Knop‐Gericke, A. Trunschke, R. Schlögl","doi":"10.1080/2055074X.2017.1287535","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1287535","url":null,"abstract":"Abstract A series of vanadia catalysts supported on mesoporous silica SBA-15 has been prepared with a loading in the range of 2–14 wt-% V and characterized under oxygen and propane oxidative dehydrogenation reaction conditions at elevated temperature up to 550 °C. In situ soft X-ray absorption spectra at the vanadium L- and oxygen K-edges and in situ synchrotron based X-ray photoemission spectra reveal a restructuring of vanadium species that results in an enhanced degree of dispersion of molecular vanadia species on the silica support. The impact of the X-ray beam on the XAS spectra of dispersed VxOy species has been studied and a brief perspective of X-ray based electron spectroscopy as a probe in catalyst characterization is given.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1287535","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44292429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-03DOI: 10.1080/2055074X.2017.1278891
Ashley R. Head, Xin Tang, Zachary Hicks, Linjie Wang, H. Bleuel, Scott Holdren, Lena Trotochaud, Yi Yu, Line Kyhl, Osman Karslıoǧlu, K. Fears, J. Owrutsky, M. Zachariah, K. Bowen, H. Bluhm
Abstract Organophosphonates are used as chemical warfare agents, pesticides, and corrosion inhibitors. New materials for the sorption, detection, and decomposition of these compounds are urgently needed. To facilitate materials and application innovation, a better understanding of the interactions between organophosphonates and surfaces is required. To this end, we have used diffuse reflectance infrared Fourier transform spectroscopy to investigate the adsorption geometry of dimethyl methylphosphonate (DMMP) on MoO3, a material used in chemical warfare agent filtration devices. We further applied ambient pressure X-ray photoelectron spectroscopy and temperature programmed desorption to study the adsorption and desorption of DMMP. While DMMP adsorbs intact on MoO3, desorption depends on coverage and partial pressure. At low coverages under UHV conditions, the intact adsorption is reversible. Decomposition occurs with higher coverages, as evidenced by PCHx and POx decomposition products on the MoO3 surface. Heating under mTorr partial pressures of DMMP results in product accumulation.
{"title":"Thermal desorption of dimethyl methylphosphonate from MoO3","authors":"Ashley R. Head, Xin Tang, Zachary Hicks, Linjie Wang, H. Bleuel, Scott Holdren, Lena Trotochaud, Yi Yu, Line Kyhl, Osman Karslıoǧlu, K. Fears, J. Owrutsky, M. Zachariah, K. Bowen, H. Bluhm","doi":"10.1080/2055074X.2017.1278891","DOIUrl":"https://doi.org/10.1080/2055074X.2017.1278891","url":null,"abstract":"Abstract Organophosphonates are used as chemical warfare agents, pesticides, and corrosion inhibitors. New materials for the sorption, detection, and decomposition of these compounds are urgently needed. To facilitate materials and application innovation, a better understanding of the interactions between organophosphonates and surfaces is required. To this end, we have used diffuse reflectance infrared Fourier transform spectroscopy to investigate the adsorption geometry of dimethyl methylphosphonate (DMMP) on MoO3, a material used in chemical warfare agent filtration devices. We further applied ambient pressure X-ray photoelectron spectroscopy and temperature programmed desorption to study the adsorption and desorption of DMMP. While DMMP adsorbs intact on MoO3, desorption depends on coverage and partial pressure. At low coverages under UHV conditions, the intact adsorption is reversible. Decomposition occurs with higher coverages, as evidenced by PCHx and POx decomposition products on the MoO3 surface. Heating under mTorr partial pressures of DMMP results in product accumulation.","PeriodicalId":43717,"journal":{"name":"Catalysis Structure & Reactivity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/2055074X.2017.1278891","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48550590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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