Deoxygenation of beef fat for the production of hydrogenated biodiesel over Pd-supported mesoporous titania catalysts: effect of catalyst preparation

Abstract

Hydrogenated biodiesel is one of the biofuels that has gained attention in recent years due to its superior fuel properties compared to conventional biodiesel. In our previous work, Pd supported TiO2 was shown to be a promising catalyst for the deoxygenation of triglycerides towards hydrogenated biodiesel. In this research, the effect of catalyst preparation on the production of hydrogenated biodiesel was evaluated. Pd/TiO2 catalysts were prepared by incipient wetness impregnation (IWI) and photochemical deposition (PCD) by using both mesoporous TiO2 supports synthesized via a combined sol-gel process with a surfactant-assisted templating method (SG-Ti2) and commercial TiO2 support (P25-TiO2). Moreover, Pd/TiO2 catalyst synthesized via a combined single-step sol-gel process (SSSG) with surfactant-assisted templating method was conducted to compare with two other methods. The catalysts were tested in a fixed-bed continuous flow reactor at 500 psig, 325 °C, H2/feed molar ratio of 30, and liquid hourly space velocity (LHSV) of 4 h-1 The products obtained from all catalysts were in the specification range of diesel fuel and the main diesel products were n-heptadecane and n-pentadecane resulting from decarboxylation/decarbonylation pathway. Among all catalysts, SSSG Pd/TiO2 catalyst provided the highest conversion of triglycerides and selectivity of the desired products. The high activity and product selectivity of SSSG could be due to its high surface area and the ability in Pd dispersity.