Catalytic hydrogenolysis of lignin β-O-4 aryl ether compound and lignin to aromatics over Rh/Nb2O5 under low H2 pressure

Abstract

The increasing risk of fossil fuels depletion due to surging energy demand has accelerated the search of alternative renewable sources. Lignin, one of the major components of lignocellulosic biomass, is the only abundant renewable natural resource for aromatic compounds. In this work, the effects of metals and process parameters were discussed via the catalytic hydrogenolysis of β-O-4 lignin model compound, 2-phenethyl phenyl ether. The best results were obtained over Rh/Nb2O5 with an overall conversion of 99.3% and exceptional selectivity of 98.9% to aromatic products when the hydrogenolysis was carried out at 260 °C and 0.1 MPa H2 for 4 h. The high efficiency is mainly attributed to the cooperation between Rh and NbOx at the perimeter sites, in which Rh particles are responsible for the dissociation of H2 and NbOx for activating CO bonds. With respect to depolymerize of ash wood lignin, the liquid products were mostly aromatics over Rh/Nb2O5 under 0.1 MPa H2. The results achieved in this work provide a promising prospect towards valorization of lignin into production of valuable aromatic compounds under low hydrogen pressure.