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Y. Yoshimura, T. Sato, H. Shimada, N. Matsubayashi, M. Imamura, A. Nishijima and S. Yoshitomi
[Prep. of Division of Petroleum Chem./American Chemical Soc., Vol.38, No.1, pp.32-39, 1993]
Temperature-programmed oxidation of CoMo and NiW hydrotreating catalysts from hydrotreatment of vacuum gas oil and coal-derived oils was carried out in thermogravimetric and fixed-bed reactors. The mechanism of oxidative removal of carbon and sulfur from spent catalysts was elucidated, and the structural changes of active metals and some solid-phase interactions between active metals and deposited metals during regeneration were also elucidated in order to correlate these resulting properties with the catalytic activities of regenerated catalysts. Changes in chemical states and structure of supported metals were analyzed by EXAFS and XPS. These structural changes were also analyzed by using the thermodynamical phase diagrams (Figs.1 and 2). These analyses indicated the effectiveness of the thermodynamics to predict a priori the regeneration and following sulfidation behavior.
