Hydrothermal liquefaction of Ulva prolifera macroalgae and the influence of base catalysts on products

Abstract

Hydrothermal liquefaction of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in an autoclave reactor at different temperature (270, 290 and 310 °C) and reaction holding time (10, 20 and 30 min.). The catalytic reactions of UM were carried out in the presence of three basic catalysts (KOH, NaOH and Na2CO3) with the different catalyst amount. Maximum bio-oil yield for non-catalytic liquefaction was (12.0 wt%) at 290 with 10 min reaction time. In the catalytic reaction the maximum bio-oil yield (26.7 wt%) was observed with KOH (0.1 g) catalyst. The chemical components and functional groups present in the bio-oils are identified by GC–MS, FT-IR, 1H-NMR, TGA and elemental analysis techniques. Majorly nitrogen containing compounds were found with catalytic reaction in bio-oils. The higher heating value (33.6 MJ kg−1) as well as the higher carbon content (64.2%) was observed in the case of catalytic liquefaction bio-oil.