Hydrodeoxygenation of guaiacol as lignin model compound for alkanes preparation with palladium-carbon catalysts

As a model reaction for catalytic hydrodeoxygenation of lignin to produce hydrocarbon fuels, the hydrodeoxygenation of guaiacol was studied over Pd, Pt, Ru and Rh catalysts on carbon. Pd/C was found to be effective for the formation of alkanes including cyclohexane and methyl cyclopentane, the yield of which was over 78% (at temperature 225℃, 0.5% mass fraction of H3PO4, H2 pressure 5 MPa, 1 h). Moreover, the serial reaction model of guaiacol conversion was proposed and the kinetics equations were also established. Based on the kinetic experiments, the reaction rate constants and apparent activation energies of each reaction steps in guaiacol hydrodeoxygenation were obtained. The apparent activation energies were 60.1 kJ/mol for partial hydrodeoxygenation to phenols and 73.6 kJ/mol for the following exhaustive hydrodeoxygenation to alkanes. The kinetic models and some general rules on the catalytic hydrodeoxygenation of guaiacol can provide important basic data for efficient utilization of lignin.