Temperature-programmed, extended

Temperature-Programmed Extended X-ray Absorption Fine-Structure (EXAFS) and X-ray Absorption Near-Edge (XANES) Spectroscopies... 

It is seen that the viscosity of the gas will change significantly during a temperature program and, thus, at a constant gas mass flow rate, the inlet pressure will rise proportionally. This increase in inlet pressure will result in an increase in the inlet/outlet pressure ratio and, as a consequence, will extend the retention time and oppose the effect of any increase in temperature. It also follows that the effect of... 

Abbreviations CCD, charge-coupled device DEXAFS, dispersive extended X-ray absorption fine structure EXAFS, extended X-ray absorption fine structure QEXAFS, quick extended X-ray absorption fine structure TPR, temperature-programmed reaction XRD, X-ray diffraction XAFS, X-ray absorption fine structure. 

The sulfidation mechanism was investigated by temperature-programmed sulfidation, as the oxidic catalyst was heated in a flow of H2S and ff2, and the consumption of IH S and ff2 and the evolution of H20 were measured continuously (13). ft was found that IH S is taken up and H20 given off, even at room temperature, indicating a sulfur-oxygen exchange reaction. This conclusion was confirmed by quick extended X-ray absorption fine structure (QEXAFS) studies (Fig. f, phase 2), which also demonstrated... 

The molybdenum dispersion also depends on the phosphorus content of the catalyst. Atanasova et al. (68, 87) reported that the dispersion of molybdenum and nickel, measured by X-ray photoelectron spectroscopy (XPS), shows a steep increase due to the presence of phosphorus at low loadings. The dispersion of molybdenum in NiMoP/Al catalysts increases further as a result of calcination, whereas that of nickel decreases. In contrast, Sajkowski et al. (83) reported, on the basis of an extended X-ray absorption fine structure (EXAFS) investigation, that phosphorus does not affect the size of the polymolybdate species, Mangnus et al. (31) inferred that the stacking of molybdates does not increase as a result of the addition of phosphorus since the height of a temperature-programmed reduction (TPR) peak at 400°C due to the reduction of deposited multilayered molybdenum oxo-species was found to be independent of the phosphorus content. However, Chadwick el al. (60) concluded from XPS measurements that the dispersion of molybdenum decreases upon addition of phosphorus. 

TPR, Temperature-programmed reaction XPS, X-ray photoelectron spectroscopy IR, infrared spectroscopy H NMR, proton nuclear magnetic resonance spectroscopy UV-vis, ultraviolet-visible spectroscopy ESR, electron spin resonance spectroscopy TPD, temperature-programmed desorption EXAFS, extended X-ray absorption fine structure spectroscopy Raman, Raman spectroscopy C NMR, carbon-13 nuclear magnetic spectroscopy. 

The mechanistic details for the combustion of CO on supported gold clusters are discussed next. Small gold clusters, Au (n < 20) were deposited after size-selection from the gas phase onto defect-poor and defect-rich MgO(lOO) films. As described in Sect. 1.5.1, defect-rich films are characterized by a given density ( 5% ML) of extended defects and point defects (F centers), whereas for defect-poor films the density of F-centers is negligible. The CO-oxidation was studied by combined temperature programmed reaction (TPR) and Fourier transform infrared spectroscopy and the obtained results were compared to extensive ab initio calculations [209,368,369]. 

Characterization of the catalysts was made using high-resolution transmission electron microscopy (TEM) (Hitachi H-9000), X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and Fourier transform-infrared spectroscopy (FT-IR). 

Metallic sites Temperature-programmed reduction (TPR) X-ray adsorption near-edge spectroscopy (XANES) Extended X-ray adsorption fine structure (EXAFS) Mossbauer spectroscopy X-ray photoelectron spectroscopy (XPS) Electron paramagnetic spectroscopy (EPR)... 

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