Catalytic transfer hydrogenation/hydrogenolysis of guaiacol to cyclohexane over bimetallic RuRe/C catalysts

Abstract

The hydrodeoxygenation of lignin monomer guaiacol via catalytic transfer hydrogenation was studied with 2-propanol as a hydrogen donor and Ru-based catalysts. Guaiacol was mainly converted into a partially deoxygenated product, cyclohexanol (>70% selectivity), over Ru/C catalysts with the hydrogen produced in-situ from 2-propanol. An addition of Re to Ru/C catalysts significantly enhanced the rate of C-O hydrogenolysis, resulting in the complete deoxygenation to cyclohexane (similar to 60% selectivity). The remarkable deoxygenation ability of the bimetallic RuRe/C catalyst is attributed to its bifunctional characteristic, by which Ru catalyzes the hydrogenation-hydrogenolysis of guaiacol and Re provides acid sites to promote cyclohexane production via hydrogenolysis. (C) 2016 Elsevier B.V. All rights reserved.