Algae have been widely considered as an important biomass of the second generation bio-energy. Crude bio-oil produced from liquefaction of microalgae is rich in fatty acids and can be used as potential feedstock for advanced biofuel. However, microalgal bio-oil tends to be viscous, tar-like, and contains significant amount of oxygen. Thus, the bio-oil needs to be upgraded before it could be used as drop-in fuel. However, complete upgrade to drop-in fuel can be expensive. Consequently, developing mild hydrotreatment strategies to produce refinery compatible bio-oil is desirable.Since hydrogen is very expensive and safe-concerning to perform hydrodeoxygenation reaction, we prefer to remove oxygen in a milder reaction condition, e.g. subcritical water, without hydrogen usage. Subcritical water has been demonstrated as a promising reaction media to perform deoxygenation reaction via decarbonylation and decarboxylation. These reactions do not require much of hydrogen involvement. On the other hand H2 can be in-situ produced under hydrothermal catalytic reaction of fatty acid by hydrothermal gasification and decarbonylation combined with water-gas shift reaction. In-situ produced hydrogen is beneficial to increase the conversion and hydrocarbon selectivity. Furthermore, subcritical water is very helpful to control the coke formation by transporting the coke precursors out from the catalyst pores. Therefore, our lab is developing and employing this hydrothermal catalytic deoxygenation technique to remove oxygen from bio-oil and fatty acid in the form of deCOx without usage of hydrogen. We use fatty acid as model compounds to screen several transition metal catalysts on different support and find Ni/ZrO2 is promising. The catalyst shows great selectivity for converting palmitic acid to pentadecane in aqueous phase. Without hydrogen usage, 50% conversion of palmitic acid is achieved at 300�C and selectivity to linear paraffin is 45% with pentadecane as the main product.

Hydrothermal deoxygenation of algal bio-oil rich in fatty acid

246th National Meeting (2013)

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