Catalytic Hydrotreatment of Alcell Lignin Using Supported Ru, Pd, and Cu Catalysts

Abstract

A catalyst screening study on the catalytic hydrotreatment of Alcell lignin in a batch setup was performed using supported Ru (C, Al₂O₃,TiO₂), Pd (C, Al₂O₃), and a Cu/ZrO₂ catalyst with the objective to determine the best catalyst for high yields of biobased aromatics and alkylphenolics. Experiments were performed at 400 °C, 4 h reaction time and an initial hydrogen pressure of 100 bar. Best results were obtained with Ru/TiO₂ and a lignin oil (78 wt % on lignin intake) with 9.1 wt % alkylphenolics, 2.5 wt % aromatics, and 3.5 wt % catechols on lignin intake were obtained. The reaction products were characterized using advanced GC×GC-FID and GC×GC-TOFMS techniques in combination with GPC, ¹³C NMR, and GC–MS-FID measurements. Systematic studies with the Ru/C catalysts using variable batch times (0–8 h, 400 °C, and an initial hydrogen pressure of 100 bar) gave insights in the reaction pathways occurring during the catalytic hydrotreatment and these include depolymerization, hydrogenation, hydrodeoxygenation, and dehydration reactions