scholarly journals Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies

2020 ◽  
Vol 22 (34) ◽  
pp. 18806-18814
Author(s):  
Baran Eren ◽  
Christopher G. Sole ◽  
Jesús S. Lacasa ◽  
David Grinter ◽  
Federica Venturini ◽  
...  
Keyword(s):  
Water Vapour ◽  
Catalyst Surface ◽  
Ambient Pressure ◽  
Methanol Conversion ◽  
Chemical State ◽  
Adsorbed Species ◽  
X Ray ◽  
Cu Catalyst

A model Cu catalyst surface oxidises to Cu2O when methanol, oxygen and water vapour are all present during methanol conversion.

scholarly journals In situ investigation of degradation at organometal halide perovskite surfaces by X-ray photoelectron spectroscopy at realistic water vapour pressure

2017 ◽  
Vol 53 (37) ◽  
pp. 5231-5234 ◽  
Author(s):  
Jack Chun-Ren Ke ◽  
Alex S. Walton ◽  
David J. Lewis ◽  
Aleksander Tedstone ◽  
Paul O'Brien ◽  
...  
Keyword(s):  
Water Vapour ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Water Vapour Pressure ◽  
Lead Iodide ◽  
X Ray ◽  
In Situ Investigation ◽  
Organometal Halide Perovskite ◽  
Methylammonium Lead Iodide

Near-ambient-pressure X-ray photoelectron spectroscopy enables the study of the reaction of in situ-prepared methylammonium lead iodide (MAPI) perovskite at realistic water vapour pressures for the first time.

A kinetic and surface study of the oxidation of ethane by nitrous oxide and by oxygen over manganese(III) oxide

1982 ◽  
Vol 60 (7) ◽  
pp. 893-897 ◽  
Author(s):  
Craig Fairbridge ◽  
Robert Anderson Ross
Keyword(s):  
Nitrous Oxide ◽  
Infrared Spectroscopy ◽  
Catalyst Surface ◽  
Binding Energies ◽  
Adsorbed Species ◽  
X Ray ◽  
Chemisorbed Oxygen ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Oxygen Complexes

The kinetics of the nitrous oxide/ethane and oxygen/ethane reactions on manganese(III) oxide have been studied from 573 to 673 K and from 523 to 593 K, respectively. The apparent activation energy for carbon dioxide formation was 130 ± 4 kJ mol−1 in both reactions while that for nitrogen formation in the nitrous oxide/ethane reaction changed from 106 ± 4 kJ mol−1, 573–613 K, to 133 ± 4 kJ mol−, 623–673 K. The kinetic results for both reactions fit the same rate equation:[Formula: see text]where px represents either [Formula: see text]. The rate-controlling step has been associated with the interaction of adsorbed species on the catalyst surface while both ethane and the oxidising gas appear to be directly involved in further steps in the mechanism. Samples were analysed routinely by scanning electron microscopy, X-ray powder diffraction, and infrared spectroscopy. Electron spectroscopy results from samples treated in various ways with hydrocarbon/oxidant mixtures gave O(1s) values from 528.7 to 529.7 eV which are indicative of binding energies usually associated with chemisorbed oxygen. No N(1s) spectrum was obtained from catalysts exposed to hydrocarbon/nitrous oxide mixtures, in agreement with the absence of bands in the infrared which are usually associated with nitrates or nitrogen/oxygen complexes. A binding energy value of 406.5 eV was measured in the comparable N(1s) spectrum of a catalyst used at 623 K for the oxidation of ethane by nitric oxide — a result which confirms conclusions from previous surface studies on the same system using infrared spectroscopy.

scholarly journals Identification of Adsorbed Species and Surface Chemical State on Ag(111) in the Presence of Ethylene and Oxygen Studied with Infrared and X-ray Spectroscopies

Physchem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 259-271
Author(s):  
Adva Ben Yaacov ◽  
Roey Ben David ◽  
David C. Grinter ◽  
Georg Held ◽  
Baran Eren
Keyword(s):  
Gas Phase ◽  
Total Pressure ◽  
Oxidation Reaction ◽  
Pressure Range ◽  
Ambient Air ◽  
Chemical State ◽  
Surface Chemical ◽  
Adsorbed Species ◽  
X Ray ◽  
Surface Chemical State

Using a combination of two surface-sensitive spectroscopy techniques, the chemical state of the Ag(111) surface and the nature of the adsorbed species in the presence of ethylene and oxygen gases are identified. In the 10 mbar pressure range and 25–200 °C studied here, Ag(111) remains largely metallic even in O2-rich conditions. The only adsorbed molecular species with a low but discernible coverage is surface carbonate, which forms due to further oxidation of produced CO2, in a similar manner to its formation in ambient air on Ag surfaces. Its formation is also pressure-dependent, for instance, it is not observed when the total pressure is in the 1 mbar pressure range. Production of carbonate, along with carbon dioxide and water vapor as the main gas-phase products, suggests that an unpromoted Ag(111) surface catalyzes mainly the undesired full oxidation reaction.

Physicochemical and Catalytic Properties of Spinels Formed by Solid-Solid Interaction Between Fe2O3and V2O5

1996 ◽  
Vol 61 (8) ◽  
pp. 1131-1140 ◽  
Author(s):  
Abd El-Aziz Ahmed Said
Keyword(s):  
Vanadium Oxide ◽  
Active Sites ◽  
Catalyst Surface ◽  
Catalytic Properties ◽  
Flow System ◽  
Oxide Catalysts ◽  
X Ray Diffraction ◽  
Selective Catalyst ◽  
X Ray ◽  
Solid Catalysts

Vanadium oxide catalysts doped or mixed with 1-50 mole % Fe3+ ions were prepared. The structure of the original samples and those calcined from 200 up to 500 °C were characterized by TG, DTA, IR and X-ray diffraction. The SBET values and texture of the solid catalysts were investigated. The catalytic dehydration-dehydrogenation of isopropanol was carried out at 200 °C using a flow system. The results obtained showed an observable decrease in the activity of V2O5 on the addition of Fe3+ ions. Moreover, Fe2V4O13 is the more active and selective catalyst than FeVO4 spinels. The results were correlated with the active sites created on the catalyst surface.

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