Effect of Hydrogen Transfer Reactions and Catalyst Synergies on the Catalytic Cracking of Saturated Fatty Acid Triglycerides to Renewable Hydrocarbons

The catalytic cracking of triglycerides offers a promising route for producing renewable hydrocarbon fuels from biomass resources. This study investigated the deoxygenation process in the catalytic cracking of saturated fatty acid triglyceride, focusing on the reaction mechanism and the role of catalyst components. It was confirmed that the hydrogen transfer reaction efficiently utilizes the hydrogen contained in the feedstock and promotes deoxygenation with H2O formation despite the reaction under a hydrogen-free atmosphere. Since oxygen-containing compounds accept hydrogen preferentially over hydrocarbons, the promotion of the hydrogen transfer reaction in catalytic cracking of triglycerides does not necessarily lead to the olefin hydrogenation, and it may be possible to combine efficient deoxygenation with the production of valuable hydrocarbons. Individual catalyst components play distinct roles in this process: Y-zeolite serves as the primary site for hydrogen-transfer-driven deoxygenation, while silica–alumina in the matrix provides moderate hydrogen transfer activity within mesopores, which suppresses excessive overcracking of the gasoline fraction. Furthermore, the alumina binder facilitates the initial cracking of bulky triglycerides and promotes an alternative deoxygenation pathway via ketonic decarboxylation. The synergy between the zeolite’s active sites and the matrix’s pore structure is essential for optimizing product distribution, specifically by suppressing the formation of polycyclic aromatic hydrocarbons (PAHs) while maintaining high liquid fuel yields.