作者: B. Scheffer , J. J. Heijeinga , J. A. Moulijn
DOI: 10.1021/J100302A023
关键词:
摘要: A series of NiO-WO/sub 3//Al/sub 2/O/sub 3/ catalysts were studied by UV-vis diffuse reflectance spectroscopy (DRS) and x-ray diffraction (XRD). Both the metal content temperature calcination varied over a wide range. It was found that W is present as W/sup 6 +/ surface phase regardless content. In NiO/Al/sub samples several Ni/sup 2 species detected: an octahedral located at both tetrahedral in Al/sub 7/O/sub support. different Ni also found, which mixed containing Ni, W, Al, O. The has some influence on speciation but major factor determines location coordination Ni. Calcination below 775 K results contain only surface. At higher temperatures diffusion into support detected XRD, 1175 equilibrium distribution throughout particles established. most themore » tetrahedrally coordinated, above 925 sites hardly affected change or model presented can quantitatively describe process using independently determined parameters. concluded negligible under hydrodesulfurization (HDS) reaction conditions, stresses importance structure oxidic precursor for HDS activity sulfided catalysts.« less