Hydrothermal liquefaction (HTL) of microalgae under milder reaction conditions was studied for the production and characterization of biocrude oil and hydrochar confirming the process feasibility . The effects of the methanol/water mass ratios, reaction temperature and time on the biocrude oil yield obtained by HTL were investigated. The optimum yield of biocrude oil (57.8 wt.%) and highest energy recovery (85.3 %) was obtained with 75 wt.% of methanol in water at 272°C, 11.5 MPa, and reaction time of 35 min. Hydrochar is considered as a renewable carbonaceous material compared to activated carbon from traditional non-renewable fossil sources. This study also focused on the effects of different activation parameters on prepared activated carbon. Based on the optimum condition of T=675°C, R=1.5 and F=267/min, using KOH as a chemical agent, highest BET surface area of 2100 m²/g was obtained, which also revealed total pore volume and average pore size of 1.2 cm³/g and 5.9 nm, respectively. The use of novel NiMo carbide catalysts supported activated carbon obtained from chemical activation of algal hydrochar for the catalytic hydrodeoxygenation of algal biocrude oil was investigated. The synthesized catalysts were screened through hydrodeoxygenation (HDO) reactions of HTL algal biocrude oil to produce liquid hydrocarbon fuels. The NiMo carbide synthesized through co-impregnation and carbothermal reduction in N₂ showed high activity for oxygen removal due to its high acidity and higher active phase exposure to active hydrogen. Response surface methodology was applied for the said catalyst to optimize the effects of temperature (350-450°C), catalyst loadings (5-15wt.%), and reaction time (1.5-4h) at a constant pressure of 3MPa. The upgraded biocrude oil at reaction condition of T=400°C, t=2.7 h and 10 wt.% of catalyst loading revealed an oxygen reduction percentage of 94% with HHV of 43.9 MJ/kg. The minimum fuel selling price (MFSP) for two stages of algal biofuels production was $8.89/gal. The effects of process conditions for biofuels production through HDO of algal biocrude oil over hydrochar based catalysts, on the GHG emissions performance were estimated at 50g CO_2-eq/MJ.

Shima Masoumi

Ph.D. student, University of Saskatchewan

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