(425e) Guaiacol Hydrodeoxygenation and Hydrogenation over Bimetallic Pt-M (Nb, W, Zr)/KIT-6 Catalysts with Tunable Acidity

Owing to high oxygen content, bio-oils from fast pyrolysis of lignin require upgrading to meet the fuel specification standards. Catalytic hydrodeoxygenation (HDO) of bio-oils faces several challenges such as low hydrocarbon yield, the requirement of high H₂ partial pressure for complete deoxygenation, and catalyst deactivation caused by coking/carbon deposit. In the present work, Pt supported on Nb, W and Zr-incorporated KIT-6 materials were prepared, characterized and tested for gas-phase HDO of guaiacol, a widely used model compound of bio-oil. Facile HDO of guaiacol was observed over 1 wt.% Pt/Nb-KIT-6 catalyst, with ~90% conversion and ~75% hydrocarbon selectivity under relatively mild hydrogen partial pressure (0.5 MPa) at 400 °C and 33 h^-1 WHSV (weight hourly space velocity). No significant catalyst deactivation was observed during a 24-h continuous run indicating that the mesoporous support provides enhanced coking 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 of metal and acid sites with the measured rates for the individual reaction steps.