Coupling Red-Mud Ketonization of a Model Bio-Oil Mixture with Aqueous Phase Hydrogenation Using Activated Carbon Monoliths

Abstract

A two-stage catalytic process for converting model bio-oil oxygenates (acetic acid, formic acid, acetol, and levoglucosan) to higher value compounds was conducted. Ketonization using iron oxide catalysts prepared from red mud was implemented in a packed bed reactor system using fast pyrolysis oil model compounds (stage one). High levels of acetone (15–25 g/L), 2-butanone (∼5 g/L), and cyclic ketones (9–13 g/L) were observed. Time-on-stream studies (7 h) indicated no measurable decline in conversion of acetol, formic acid, and levoglucosan and only a 4% decline in acetic acid conversion. Subsequently, a second stage continuous hydrogenation of the ketonization products was conducted using Pd on activated carbon monolith (ACM) catalysts generated from wood and Pd–C granules. The best results were achieved using the Pd-ACM catalyst at 180 °C and 300 psi (H2), which converted ketones to alcohols at ∼60–80%. The Pd-ACM catalyst achieved higher space time yields, selectivity, and conversions compared to Pd–C gr...