Hydrodeoxygenation of Guaiacol as a Bio-Oil Model Compound over Pillared Clay-Supported Nickel-Molybdenum Catalysts

Pillared clay-supported NiMo catalysts were synthesized in their reduced and sulfided forms and applied to the hydro-deoxygenation 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.