Synthesis of Hydrocarbon Biodiesel from Fats and Oils by Catalytic Decarboxylation—Analysis of Products and Reaction Networks—

Abstract

We have developed a new process for producing hydrocarbon-based biodiesel by the decarboxylation of fats and oils using a MgO/SiO₂ catalyst. The physical properties of the biodiesel product with simple secondary processing can meet the NEET standards for biofuels, and can successfully be used in common rail diesel engines. However, the biodiesel product contains a mixture of various compounds, and the complete contents are unclear. Therefore, the reaction networks of the process are also not understood. This study clarified the product contents and the reaction networks through detailed GC and GC-MS analysis of the cracked bio-oil obtained with the MgO/SiO₂ catalyst. The reaction networks were clarified by tracking the reactions of model compounds. The analysis found that the most abundant products were olefins and paraffins formed by direct decarboxylation of the fatty acids on MgO, and ketones derived from dimerized fatty acids. The wide carbon number distribution of hydrocarbons was thought to result from a decomposition reaction that caused a chain reaction of radicals generated during the direct decarboxylation reactions and ketone decomposition processes.