Effect of catalysts on liquefaction of alkali lignin for production of aromatic phenolic monomer

Hydrothermal liquefaction (HTL) has emerged as a promising technology for producing fuels/chemicals. Lignin liquefaction was carried out with different temperature 250, 270, 290 and 310 degrees C in the presence of 50% ethanol-50% water (v/v) and a reaction time 30 min. The catalyst reaction with 10 wt% each catalyst of Pd/C, Fe/C, Co/C and Ni/C at 270 degrees C for 30 min reaction time was carried out. For non-catalytic reaction maximum bio-oil (68.2 wt%) was obtained at 270 degrees C while catalytic reaction with Co/C catalyst gave highest bio-oil (73.2 wt %). The obtained bio-oil has been analyzed with the help of GC-MS, FT-IR, NMR, GPC and CHNS. On the basis of GC-MS analysis, the main monomeric phenolic compounds produced were phenol, 2-methoxy-phenol, 4-ethyl-phenol, 2-methoxy-4-ethyl-phenol and 2,6-dimethoxy-phenol, due to their high concentrations it was feasible to select these five monomeric phenols as target compounds. It was seen that compared to the non-catalytic liquefaction reaction, the catalytic (Pd/C, Co/C, Ni/C and Fe/C) liquefaction reaction promotes the hydrogenation and hydrogeoxygenation of bio-oils. The possible reaction pathways have been explored in this studied.