Advanced biofuels from waste cooking oil via solventless and hydrogen-free catalytic deoxygenation over mesostructured Ni-Co/SBA-15, Ni-Fe/SBA-15, and Co-Fe/SBA-15 catalysts

Abstract

Waste cooking oil (WCO) is one of the attractive feedstocks in the production of advanced biofuels due to its low cost and was usually left behind abundantly. In this study, a series of mesoporous bimetallic catalysts, Ni-Co/SBA-15, Ni-Fe/SBA-15, and Co-Fe/SBA-15 were synthesized and analyzed their catalytic activity through a hydrogen-free and solventless catalytic deoxygenation process that consists of decarboxylation and decarbonylation reaction pathways. In this process, the oxygenated triacylglycerols (TAGs) of WCO were converted to advanced biofuels that contain gasoline and diesel-like hydrocarbons. Firstly, the bimetallic catalysts were prepared using the wet impregnation process of Ni-Co, Ni-Fe, and Co-Fe (5 wt%, 10 wt%, and 15 wt%) metal species on the hexagonal mesoporous catalyst supporter, SBA-15. Nitrogen-isotherm physisorption analysis proved that all the prepared catalysts are mesostructured with a 4.8–5.5 nm pore diameter range. X-ray diffractogram confirmed that the wet impregnation of bimetallic particles does not disrupt the hexagonal structure of catalyst support, SBA-15. The catalytic activity, deoxygenation process show that 10% Ni-Fe/SBA-15 possess the highest yield of liquid (73.1%) but have a low selectivity towards the diesel fraction, while the 5% Ni-Co/SBA-15 posed the highest selectivity of diesel fraction (C11-C17) of 81%.