(435e) Surface Modification and Catalytic Activity of MoO3 during Hydrodeoxygenation (HDO) of Lignin-Derived Model Compounds
AIChE Annual Meeting
Wednesday, November 19, 2014 - 9:50am to 10:10am
Hydrodeoxygenation (HDO) is a major route of upgrading bio-oil. MoO3 has been shown to be active for HDO of bio-oil model compounds. Specifically, the catalyst is selective towards cleavage of C-O bonds at temperatures of 320-350oC and H2 pressures <= 1 bar. Importantly, this catalyst selectively cleaves stronger phenolic Ph-OMe over weaker PhO-Me bonds. Detailed reactivity studies were performed to gain insight into the nature of the active sites. An initial induction period was observed for the catalyst to achieve peak performance,which suggested a surface modification was required to render the catalyst active. The catalyst surface undergoes partial carburization as evidenced by the presence of oxycarbide- and oxycarbohydride-containing phases (i.e., MoOxCyHz) at lower temperatures. Mo5+ species are hypothesized to be responsible for the HDO chemistry on the catalyst. The transformation of bulk phases and the surface modification of MoO3 by carbon/H2 are also investigated to understand the role of surface carbon in the stabilization and enhanced activity of the partially reduced MoO3 surface. The partial surface carburization during reaction was found to play a role in stabilizing Mo5+ state on the catalyst surface and slowing down over-reduction of MoO3 into inactive MoO2 phase.