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Co−Mo/B2O3/Al2O3 catalysts were prepared by a post-treatment of the calcined states with citric acid (CA) and were tested for the hydrodesulfurization (HDS) reaction of thiophene. The catalysts were characterized by LRS, UV−visible spectroscopy, Mo K-edge EXAFS, TEM, NO adsorption capacity, and surface area measurements. Catalysts obtained by simultaneous impregnation with citric acid were also prepared for comparison. Sulfided catalysts were characterized by a chemical vapor deposition (CVD) technique using Co(CO)3NO. The addition of citric acid in a post-treatment more effectively increased the catalytic activity and NO adsorption capacity than did addition by a simultaneous-impregnation method. Co-CA and Mo-CA surface complexes formed at the expense of CoMoO4 and polymolybdates. The maximum potential activity of Co−Mo/B2O3/Al2O3 was obtained by a simple post-treatment of the calcined catalyst with citric acid.

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Pillared clay-supported NiMo catalysts were synthesized in their reduced and sulfided forms and applied to the hydrodeoxygenation of guaiacol (2-methoxyphenol) as a bio-oil model compound. The sulfided catalyst displayed better activity and selectivity as compared to the reduced catalyst, yielding phenol as the major product. Quasielastic neutron scattering demonstrated that jump diffusion of guaiacol was seen after adsorption on both the sulfide catalyst and pillared clay. Inelastic neutron scattering was carried out in conjunction with an infrared study and reveal that there were two types of interaction of guaiacol with the catalyst. The first is guaiacol adsorbed via various types of H-bonding interaction, as observed in the sulfided catalyst. The second type of interaction is guaiacol adsorbed on the surface, presumably at a Mo vacant site, by chemisorption through formation of a methoxyphenate species as seen in the reduced catalyst. The interactions were greater in the sulfided catalyst by which guaiacol was selectively adsorbed in coordination with the Ni–Mo–S site.

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