Novel acid-base dual-activity heterogeneous Ba40-Ce15/ZSM-5 catalyst for biodiesel production: RSM-based optimization and performance analysis

Biodiesel, known for its low carbon emissions and renewability, offers a promising alternative to fossil diesel. Support loading and additive modification are effective strategies for synthesizing high-performance heterogeneous catalysts. This study modified ZSM-5 zeolite with the addition of divalent barium ions and tetravalent cerium ions to develop the novel acid-base dual-activity Ba-Ce/ZSM-5 catalyst for biodiesel production from the acidified palm oil through transesterification. Characterization results show that the synergistic loading of the divalent barium ions and the tetravalent cerium ions generates snowflake-like particles on the multi-porous ZSM-5 surface and increases the density of catalytic active sites. Compared to the pure ZSM-5, the Ba40-Ce15/ZSM-5 catalyst exhibits nearly a five-fold increase in average pore size and forms the hierarchical pore structure. This modification reduces the diffusion resistance of triglycerides during transesterification. The catalyst retains excellent activity even in the presence of 5.00 wt% free fatty acids and moisture. With optimization by Response Surface Methodology with Box-Behnken Design (RSM-BBD), the maximum biodiesel yield of 97.48 % is achieved at the alcohol-to-oil molar ratio of 14.95 : 1, reaction temperature of 149.6 °C, catalyst amount of 6.73 wt%, and reaction duration of 2 h. Compared to previously reported catalysts, the Ba40-Ce15/ZSM-5 catalyst exhibits superior performance in increasing biodiesel yield while offering greater cost-effectiveness.