2-Methylfuran from pinewood by molten-salt hydropyrolysis and catalytic hydrogenation of the furfural intermediate

Abstract

This study explores the production pathway of 2-methylfuran (MF) renewable fuels by integrating molten salt hydropyrolysis of lignocellulosic biomass for furfural generation and subsequent catalytic hydrodeoxygenation of furfural to MF in the vapour phase using copper-based catalysts. In response to the increasing demand for biofuels, where bioethanol-blended gasoline dominates, MF presents itself as a promising fuel additive with improved fuel characteristics. This work focuses on optimizing MF production from pine wood pyrolysis using an innovative reaction environment, being chloride molten salts, eliminating the need for biomass fractionation. Employing a tandem micro-reactor and evaluating two Cu-based catalysts, Cu/SiO₂ and Cu/activated carbon (Cu/AC), the study aims to identify optimal conditions for MF production in this integrated process. The process demonstrated selective furfural production in the first step, with subsequent high-yield conversion to 2-methylfuran (up to 92% selectivity) using Cu/AC. Optimal hydrodeoxygenation occurred at 400–500 °C, yielding approximately 10.3 wt% of 2-methylfuran on a dry pinewood basis. Cu/AC outperformed Cu/SiO₂ due to higher copper loading and dispersion. Notably, chloromethane, a byproduct from molten salt hydropyrolysis, was removed entirely during hydrodeoxygenation with Cu/AC. The study outlined conditions for an in situ conversion route from pinewood to furfural and 2-methyl furan in the vapour phase.