Analysis of Processing Hydrothermal Liquefaction of Microalgae Reaction Product with and without Dichloromethane Solvent for Biocrude Recovery

Producing biocrude from hydrothermal liquefaction (HTL) of microalgae has the potential to complement fossil fuels, while simultaneously reducing greenhouse gas emissions. However, biocrude recovery from the HTL reaction product has been a concern. In this study, analysis of yields and property of biocrude recovered with and without using dichloromethane (DCM) organic solvent was investigated. The HTL experiment were performed at reaction temperature of 350 o C and 20 min reaction time using 16 w/w % solids each of Spirulina sp. and Tetraselmis sp. Data obtained showed that use of DCM favours maximum biocrude yield but of lower quality when compared with DCM-free biocrude. Biocrude yield of 58wt% was obtained from Tetraselmis sp. and 48wt% from Spirulina sp. when DCM was used. About 38 and 40wt% biocrude yields were derived with DCM-free recovery process. Higher carbon content, energy dense, and lower heteroatoms content constitutes biocrude recovered without DCM treatment, which is in contrast to the biocrude recovered with DCM. In addition, an average energy input of 13MJ/kg is required to produce unit biocrude, with an additional energy input ~0.5MJ/kg to evaporate DCM when used in biocrude recovery. Keywords — Bio-energy, Hydrothermal liquefaction, Microalgae, Organic solvent, Separation method