scholarly journals It's not just the defects – a curved crystal study of H2O desorption from Ag

2019 ◽  
Vol 21 (28) ◽  
pp. 15422-15430
Author(s):  
Sabine V. Auras ◽  
Robert A. B. van Bree ◽  
Dima L. Bashlakov ◽  
Richard van Lent ◽  
Ludo B. F. Juurlink
Keyword(s):  
Binding Energy ◽  
Temperature Programmed Desorption ◽  
Structure Sensitivity ◽  
Spatially Resolved ◽  
Temperature Programmed

Spatially-resolved temperature-programmed desorption of H2O from curved Ag surfaces resolves the causes of structure sensitivity in binding energy.

Adsorption and Reaction Mechanisms of Thiophene over Sulfided Ruthenium Catalysts

1987 ◽  
Vol 111 ◽  
Author(s):  
Ray A. Cocco ◽  
Bruce J. Tatarchuk
Keyword(s):  
Binding Energy ◽  
Mass Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Reaction Mechanisms ◽  
Temperature Programmed Desorption ◽  
Ruthenium Catalysts ◽  
Subsequent Annealing ◽  
X Ray ◽  
Temperature Programmed ◽  
Secondary Ion

AbstractAdjustable (hydrogenolysis/hydrogenation) ratios (i.e., selectivity) of thiophene over sulfided ruthenium catalysts have been observed to depend on the method of presulfidization. Sulfidization in 10% H2S/H2 at 300–800K yielded a selectivity greater than 100, whereas a ratio of ca. 1 was noted after presulfidization in 100% H2S. The transition from one selectivity regime to another is reversible and can be changed via subsequent annealing or resulfidization procedures. X-Ray photoelectron spectroscopy shows similar results where sulfidization in 100% H2S yields: (i) a higher sulfur uptake with a corresponding 0.5 eV shift of the S 2P1/2–3/2 peaks to higher binding energy; (ii) multilayer sulfur incorporation at lower temperatures; and (iii) similar reversible behavior following subsequent annealing or resulfidization. Secondary ion mass spectroscopy and temperature programmed desorption studies also reveal that sulfur coverages affect thiophene adsorption, orientation and cracking on ruthenium surfaces.

Temperature-Programmed Desorption of Large Molecules: Influence of Thin Film Structure and Origin of Intermolecular Repulsion

Nanoscale ◽  
2021 ◽  
Author(s):  
Pierre-Martin Dombrowski ◽  
Stefan Renato Kachel ◽  
Leonard Neuhaus ◽  
J. Michael Gottfried ◽  
Gregor Witte
Keyword(s):  
Thin Film ◽  
Binding Energy ◽  
Temperature Programmed Desorption ◽  
Film Structure ◽  
Solid Surfaces ◽  
Theoretical Modelling ◽  
Large Molecules ◽  
Organic Adsorbates ◽  
Temperature Programmed ◽  
Molecular Nanostructures

Although the exact knowledge of the binding energy of organic adsorbates on solid surfaces is of vital importance for the realization of molecular nanostructures and the theoretical modelling of molecule-substrate...

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

scholarly journals Nanosheet-Like Ho2O3 and Sr-Ho2O3 Catalysts for Oxidative Coupling of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 388
Author(s):  
Yuqiao Fan ◽  
Changxi Miao ◽  
Yinghong Yue ◽  
Weiming Hua ◽  
Zi Gao
Keyword(s):  
Oxidative Coupling ◽  
Temperature Programmed Desorption ◽  
Oxidative Coupling Of Methane ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Oxygen Species ◽  
N2 Adsorption ◽  
Basic Sites ◽  
Chemisorbed Oxygen ◽  
Temperature Programmed

In this work, Ho2O3 nanosheets were synthesized by a hydrothermal method. A series of Sr-modified Ho2O3 nanosheets (Sr-Ho2O3-NS) with a Sr/Ho molar ratio between 0.02 and 0.06 were prepared via an impregnation method. These catalysts were characterized by several techniques such as XRD, N2 adsorption, SEM, TEM, XPS, O2-TPD (temperature-programmed desorption), and CO2-TPD, and they were studied with respect to their performances in the oxidative coupling of methane (OCM). In contrast to Ho2O3 nanoparticles, Ho2O3 nanosheets display greater CH4 conversion and C2-C3 selectivity, which could be related to the preferentially exposed (222) facet on the surface of the latter catalyst. The incorporation of small amounts of Sr into Ho2O3 nanosheets leads to a higher ratio of (O− + O2−)/O2− as well as an enhanced amount of chemisorbed oxygen species and moderate basic sites, which in turn improves the OCM performance. The optimal catalytic behavior is achievable on the 0.04Sr-Ho2O3-NS catalyst with a Sr/Ho molar ratio of 0.04, which gives a 24.0% conversion of CH4 with 56.7% selectivity to C2-C3 at 650 °C. The C2-C3 yield is well correlated with the amount of moderate basic sites present on the catalysts.

scholarly journals The interaction of size-selected Ru3 clusters with RF-deposited TiO2: probing Ru-CO binding sites with CO-Temperature Programmed Desorption

2021 ◽  
Author(s):  
Liam Howard-Fabretto ◽  
Timothy Gorey ◽  
Guangjing Li ◽  
Siriluck Tesana ◽  
Gregory F Metha ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Chemical Reactions ◽  
Binding Sites ◽  
Co Hydrogenation ◽  
Temperature Programmed Desorption ◽  
Temperature Programmed

Small Ru clusters are efficient catalysts for chemical reactions such as CO hydrogenation. In this study 3-atom Ru3 clusters were deposited onto radio frequency (RF)-deposited TiO2 which is an inexpensive,...

scholarly journals Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1066 ◽  
Author(s):  
Bogdan Samojeden ◽  
Marta Kamienowska ◽  
Armando Izquierdo Colorado ◽  
Maria Elena Galvez ◽  
Ilona Kolebuk ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Temperature Programmed Desorption ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Temperature Programmed Reduction ◽  
Fly Ashes ◽  
Coal Fly Ashes ◽  
Temperature Programmed ◽  
Mg Content

Cenospheres from coal fly ashes were used as support in the preparation of Ni–Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 °C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 °C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

scholarly journals Nonthermal Plasma Induced Fabrication of Solid Acid Catalysts for Glycerol Dehydration to Acrolein

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 391
Author(s):  
Lu Liu ◽  
Xiaofei Philip Ye
Keyword(s):  
Solid Acid ◽  
Nonthermal Plasma ◽  
Temperature Programmed Desorption ◽  
Argon Atmosphere ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Pyridine Adsorption ◽  
X Ray ◽  
Glycerol Dehydration ◽  
Temperature Programmed

The feasibility of fabricating better solid acid catalysts using nonthermal plasma (NTP) technology for biobased acrolein production is demonstrated. NTP discharge exposure was integrated in catalyst fabrication in air or argon atmosphere. The fabricated catalysts were characterized by Brunauer–Emmett–Teller surface area analysis, temperature-programmed desorption of ammonia, X-ray powder diffraction and Fourier-transform infrared spectroscopy of pyridine adsorption, in comparison to regularly prepared catalysts as a control. Further, kinetic results collected via glycerol dehydration experiments were compared, and improvement in acrolein selectivity was displayed when the catalyst was fabricated in the argon NTP, but not in the air NTP. Possible mechanisms for the improvement were also discussed.

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