Two-dimensional Mo catalysts supported on the external surface of planar Silicalite-1 zeolite for biodiesel production from waste cooking soybean oil: Transesterification experiment and kinetics

Customized and two-dimensional Mo catalyst supported on external surface of planar Silicalite-1 (Mo/S-1-p) zeolite was prepared for efficient transesterification of waste cooking soybean oil (WCSO) to produce biodiesel. Structural characteristics show the framework structure of Mo/S-1-p was almost unchanged by introducing different Mo-loading, and the Mo⁶⁺ oxide species were only well dispersed on the outer surface of Mo/S-1-p with low Mo-loading, but the aggregation of bulky MoO₃ were detected under the high Mo-loading above 5 %. Furthermore, the 5Mo/S-1-p catalyst showed a good performance and stability, which exhibited the WCSO conversion of 80.73 % and biodiesel selectivity of 99.32 %. Additionally, the intrinsic kinetics of the transesterification of WCSO catalyzed by 5Mo/S-1-p catalyst was studied after eliminating mass transfer diffusion. The corresponding kinetic equation was established through the correlation of the initial rate and the reactant concentration, and the apparent Ea was calculated to be 48.03 kJ mol⁻¹. Finally, the fuel properties of the as-synthesized biodiesel are matched with the current international standards. This research provides a beneficial technology for the synthesis of green and inexpensive sustainable fuel.