Gas-phase hydrodeoxygenation of guaiacol over Fe/SiO2 catalyst

Abstract

Lignin could be an important green source for aromatic hydrocarbon production (benzene, toluene and xylenes, BTX). Catalytic hydrodeoxygenation (HDO) of guaiacol was studied over Fe/SiO2 as a model reaction of lignin pyrolysis vapours hydrotreatment. The catalytic conditions were chosen to match with the temperature of never-condensed lignin pyrolysis vapours. The catalyst was characterised by XRD, Mössbauer spectroscopy, N2 sorption and temperature programmed oxidation. A comparison is made with a commercial cobalt-based catalyst. Cobalt-based catalyst shows a too high production of methane. Fe/SiO2 exhibits a good selectivity for BT production. It does not catalyse the aromatic ring hydrogenation. Temperature (623–723K) and space time (0.1–1.5gcath/gGUA) influence the aromatic carbon–oxygen bond hydrogenolysis reaction whereas H2 partial pressure (0.2–0.9bar) has a minor influence. 38% of BT yield was achieved under the best investigated conditions. Reaction mechanisms for guaiacol conversion over Fe/SiO2 are discussed.