Catalytic (copper) hydrothermal liquefaction for lignin to produce high quality bio-oil and nano Cu carbon hybrids material

Abstract

The in-situ hydrothermal liquefaction of direct Cu salt solution with lignin and Cu-impregnated lignin was performed with a motive to enhance the bio-oil yield along with the generation of nanometal carbon hybrids. The key operating parameter, temperature (200 °C to 320 °C) was varied, and the performance of both processes was evaluated based on the bio-oil yields. From the experiments, a maximum bio-oil yield of 28.74% and 24.87% was achieved for impregnated and direct process, respectively, at the optimum condition of 280 °C, 15 min, and the feed-to-solvent ratio of 1:9, which is almost double the non-catalytic bio-oil yields (10.16%) at the similar operating conditions. The XRD analysis confirmed the transition of Cu2+ to Cu+ and Cu. TEM inferred an average Cu particle size of 15.9 nm and 62.1 nm in hybrids material obtained from direct Cu effluent and Cu-impregnated lignin respectively.