ZSM-5 supported Mo catalysts for the dehydroaromatization reaction of methane were characterized by Mo K-edge EXAFS, NH3-TPD, and XPS techniques. Mo/ZSM-5 catalysts showed the maximum activity for benzene formation at 5 wt% Mo. The activity of the catalysts was related to the particle size of Mo2C supported on ZSM-5 estimated by Mo K-edge EXAFS. The addition of a second metal did not increase the activity for benzene formation. These results are ascribed to the weakening of the interaction between the acid sites of ZSM-5 and Mo oxide precursors due to competitive consumption of zeolite protons by added metal atoms, resulting in the formation of less dispersed Mo carbide particles and the decreased number of acid sites.

Co _ Mo/Al2O3 catalysts with high loading of Mo (20 wt% Mo) were prepared by the addition of citric acid (CA) using a simultaneous impregnation method or a post-treatment method. The catalyst activity was investigated for the hydrodesulfurization (HDS) of dibenzothiophene. TEM, Co K-edge XANES, NO adsorption capacity, and surface area measurements were conducted to characterize the catalysts. The catalysts were also investigated by the chemical vapor deposition technique using Co(CO)3NO to prepare Co/MoS2 and Co/Co _ MoS2 catalysts. Addition of citric acid by the post-treatment method to calcined (Co) _ Mo/Al2O3 oxide catalysts significantly enhanced the edge dispersion of MoS2 particles and the catalytic activity of Co/Mo/Al2O3 and Co _ Mo/Al2O3, whereas citric acid addition by the simultaneous impregnation method hardly affected the edge dispersion. The highest HDS activity was obtained with a CA/Mo mole ratio of 1.5-2 for the post-treatment catalysts. The posttreatment method may be applicable to the regeneration of deactivated HDS catalysts.

A recent experimental result shows that Pt L-edge XANES spectra for Pt small cluster are sensitive to CO adsorption. In the present study we try to extract useful information about geometric and electronic structures of these cluster by applying a full multiple-scattering approach for the XANES analyses. Detailed analyses provide us with information that some extent of change transfer plays an important role for the CO adsorption. We also discuss the plausible adsorption site on the Pt clusters.