Using a hybrid-like supported catalyst to improve green fuel production through hydrothermal liquefaction of Scenedesmus obliquus microalgae

Abstract

Hydrothermal liquefaction of Scenedesmus obliquus has been optimized in a micro reactor using response surface methodology. Temperature, residence time and feedstock concentration were studied through central composite design to verify the optimized conditions leading to the highest yield of bio-crude and energy recovery. Based on the non-catalytic studies, temperature, feedstock concentration, and their interaction were respectively determined as the most effective variables. In order to improve the quality of produced bio-crude, the one step upgrading procedure was carried out in the presence of synthesized heterogeneous catalysts including Ni/AC, Ni/AC-CeO₂ nanorods and Ni/CeO₂ nanorods. Although, it was found that, more or less, all the catalysts were able to improve the bio-crude yield and quality based on their specific characteristics, however using Ni/AC-CeO₂ hybrid like nanorods, not only the bio-crude yield would be improved by more than 9% but also the bio-crude could be upgraded to a green bio-based fuel.

Keywords: Bio-crude upgrading; Ceria nanorods; Hydrothermal liquefaction; Microalgae; Response surface methodology.