Guaiacol Hydrodeoxygenation and Hydrogenation over BimetallicPt-M (Nb, W, Zr)/KIT-6 Catalysts with Tunable Acidity

Owing to a high oxygen content, bio-oils from the fastpyrolysis of biomass require upgrading to meet fuel specification standards.Catalytic hydrodeoxygenation (HDO) of bio-oils faces several challenges suchas low hydrocarbon yields, the requirement of high H2partial pressure forcomplete deoxygenation, and catalyst deactivation caused by coking/carbondeposition. In the present work, Pt supported on Nb, W, and Zr-incorporatedKIT-6 materials were prepared, characterized, and tested for the gas-phaseHDO of guaiacol, a widely used model compound of bio-oil. Facile HDO ofguaiacol was observed over a 1 wt % Pt/Nb-KIT-6 catalyst, with similar to 90%conversion and similar to 75% hydrocarbon selectivity under relatively mild hydrogenpartial pressure (0.5 MPa) at 400 degrees C and 33 h-1weight hourly space velocity(WHSV). No significant catalyst deactivation was observed during a 24-hcontinuous run indicating that the mesoporous support provides enhancedcoking resistance. Mechanistic investigations indicate that the tunable acidity of the supports promotes transalkylation reactions,which favor increased aromatic hydrocarbon yields. A plausible reaction mechanism is postulated based on correlating the number ofmetal and acid sites with the measured rates for the individual reaction steps.