Deoxygenation of microalgal oil into hydrocarbon with precious metal catalysts: Optimization of reaction conditions and supports

Deoxygenation of microalgal oil obtained by pyrolysis of microalgae was carried out for the production of hydrocarbon fuel from biomass by metal supported catalyst. Oleic acid was used as a model reactant to select an optimized catalyst. Effects of support, metal species, and metal loading on catalytic performance were investigated. Activated carbon showed better performance than silica as a support. Considering various factors in model reaction, such as metal loading, reaction temperature, activity for deoxygenation, and selectivity for decarboxylation, 5wt% platinum supported on activated carbon (5wt% Pt/C) was selected as an optimized catalyst. Based on these results, deoxygenation of the pyrolysis oil from Chlorella sp. KR-1 was conducted at 623 and 673K over this selected catalyst. The product after catalytic deoxygenation was mainly composed of pure hydrocarbons, and its oxygen content was below 2.0%. The fraction in the product of which the boiling point was less than 623K was about 90%. These properties could allow this upgraded oil to be used for transportation fuel. However, the degree of oxygen removal with microalgal pyrolysis oil was lower than that with oleic acid, implying that impurities in the pyrolysis oil may inhibit the deoxygenation reaction.