X-ray photoelectron spectroscopy, temperature-programmed desorption and temperature-programmed reduction study of LaNiO3 and La2NiO4 +? catalysts for methanol oxidation

1994 ◽  
Vol 90 (13) ◽  
pp. 1987 ◽  
Author(s):  
Jacques Choisnet ◽  
Navena Abadzhieva ◽  
Plamen Stefanov ◽  
Dimitar Klissurski ◽  
Jean Marc Bassat ◽  
...  
Keyword(s):  
Methanol Oxidation ◽  
Photoelectron Spectroscopy ◽  
Temperature Programmed Desorption ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Temperature Programmed

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 Deposition of Co onto Supported MoS2 by Water-Assisted Spreading: Increased Activity Promotion in Hydrodesulphurization of 1-Benzothiophene

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 987 ◽  
Author(s):  
Luděk Kaluža ◽  
Martin Koštejn ◽  
Daniela Gulková
Keyword(s):  
Photoelectron Spectroscopy ◽  
Temperature Programmed Reduction ◽  
Solubility In Water ◽  
X Ray ◽  
Activity Promotion ◽  
Hds Catalysts ◽  
Temperature Programmed ◽  
Increased Activity ◽  
Low Solubility ◽  
Scanning Electron

Hydrodesulphurization (HDS) catalysts were newly prepared by water-assisted spreading of CoCO3.Co(OH)2 of low solubility in water onto pre-sulphided Mo species supported on several Al2O3 of surface area SBET 77-262 m2g−1, ZrO2 of SBET 108 m2g−1, and TiO2 of SBET 140 m2g−1. The spreading was followed by scanning electron microscopy (SEM-EDX). X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (H2-TPR) characterized partial re-oxidation of sulphidic Mo catalysts before Co sorption. The prepared catalysts were characterized in sulphidic form by H2-TPR. Activity of catalysts was determined in the HDS reaction of 1-benzothiophene. The spreading of Co onto sulphidic catalysts led to systematic increase of HDS activity by 16–86% in comparison to the spreading of Co onto oxide samples.

scholarly journals Effect of Residual Na+ on the Combustion of Methane over Co3O4 Bulk Catalysts Prepared by Precipitation

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 427 ◽  
Author(s):  
Andoni Choya ◽  
Beatriz de Rivas ◽  
Jose Gutiérrez-Ortiz ◽  
Rubén López-Fonseca
Keyword(s):  
Photoelectron Spectroscopy ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Negative Impact ◽  
Methane Combustion ◽  
Molar Ratio ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Two Samples ◽  
Temperature Programmed

The effect of the presence of residual sodium (0.4 %wt) over a Co3O4 bulk catalyst for methane combustion was studied. Two samples, with and without residual sodium, were synthesized by precipitation and thoroughly characterised by X-ray diffraction (XRD), N2 physisorption, Wavelength Dispersive X-ray Fluorescence (WDXRF), temperature-programmed reduction with hydrogen followed by temperature-programmed reduction with oxygen (H2-TPR/O2-TPO), temperature-programmed reaction with methane (CH4-TPRe), ultraviolet–visible–near-infrared diffuse reflectance spectroscopy (UV-vis-NIR DRS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that during calcination, a fraction of the sodium atoms initially deposited on the surface diffused and migrated into the spinel lattice, inducing a distortion that improved its textural and structural properties. However, surface sodium had an overall negative impact on the catalytic activity. It led to a reduction of surface Co3+ ions in favour of Co2+, thus ultimately decreasing the Co3+/Co2+ molar ratio (from 1.96 to 1.20) and decreasing the amount and mobility of active lattice oxygen species. As a result, the catalyst with residual sodium (T90 = 545 °C) was notably less active than its clean counterpart (T90 = 500 °C). All of this outlined the significance of a proper washing when synthesizing Co3O4 catalyst using a sodium salt as the precipitating agent.

Effect of Heat Treatments on TiH2: Surface Composition and Hydrogen Release

2016 ◽  
Vol 879 ◽  
pp. 2032-2037 ◽  
Author(s):  
Gabriele Lapi ◽  
Carlo Alvani ◽  
Francesca Varsano ◽  
Saulius Kaciulis ◽  
Roberto Montanari ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Titanium Hydride ◽  
Surface Composition ◽  
Hydrogen Desorption ◽  
Temperature Programmed Desorption ◽  
Heat Treatments ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

The present work investigates the effect of heat treatments in air on the surface and structure of titanium hydride (TiH2) and hydrogen desorption. TiH2 has been heated in air at 440 and 540 °C for increasing time up to 180 min. to obtain the samples representative of 12 different oxidation conditions. The samples have been then examined by Temperature Programmed Desorption (TPD), X-Ray Diffraction (XRD) and Photoelectron Spectroscopy (XPS). Experimental results are presented and discussed.

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