Hydrodeoxygenation of lignin model compounds to alkanes over Pd-Ni/HZSM-5 catalysts

In this work, a bimetallic catalyst of Pd and Ni supported on HZSM-5 was designed and evaluated in the hydrodeoxygenation of model compounds representing various C-O bonds in lignin. The effects of temperature, holding time, and initial H-2 pressure on the catalytic performance of the Pd-Ni/HZSM-5 catalyst were investigated. The results indicated that the Pd-Ni/HZSM-5 catalyst exhibited superior catalytic activity towards the conversion of the model compounds to alkanes compared to its monometallic counterparts. Direct cleavage of the C-O bond in DPE was achieved under low H-2 pressure, mainly producing benzene and minor amounts of phenol and cyclohexane, while at high H-2 pressure, the reaction pathway was altered towards hydrogenation of the benzene ring, followed by then cleavage of the C-O bond to afford only cyclohexane. Moreover, the Pd-Ni/HZSM-5 catalyst showed high activities when applying other substrates including anisole, veratrole, guaiacol, benzyloxybenzene, phenethyl phenyl ether, and dibenzyl ether. (C) 2019 Energy Institute. Published by Elsevier Ltd. All rights reserved.