Efficient and economic transesterification of waste cooking soybean oil to biodiesel catalyzed by outer surface of ZSM-22 supported different Mo catalyst

With the aim of developing efficient heterogeneous catalysts for production of clean biodiesel through the transesterification process, a novel Mo catalyst supported on the outer surface of ZSM-22 (xMo/ZSM-22) was developed and synthesized successfully with the wet impregnation method. The characterization results showed that the Mo(VI) oxide species were highly dispersed on the surface of catalysts under the Mo-loading not higher than 5%, and the aggregation of the MoO3 nanoparticles were detected above the Mo-loading of 5%. Meanwhile, the maximum acid intensity was also exhibited in the 5Mo/ZSM-22 catalyst. As a result, the catalytic performance of Mo/ZSM-22 catalysts in the transesterification of waste cooking soybean oil (WCSO) was significantly improved compared with the untreated ZSM-22 catalyst. Especially, the 5Mo/ZSM-22 showed the good activity (XWCSO of 59.29%, SBiodiesel of 99.86%), which was mainly due to the well dispersed Mo species and the larger acidity. Additionally, the 5Mo/ZSM-22 catalyst exhibits good stability and the high biodiesel selectivity, and the fuel properties of the as-synthesized biodiesel meet ASTM D6751 standards. This work provides a useful synthesis strategy of transesterification catalysts for the preparation of biodiesel. [Display omitted] •Novel Mo catalyst supported on the outer surface of ZSM-22 zeolite for production of biodiesel is synthesized.•Clean biodiesel energy is produced through the transesterification process from waste cooking soybean oil.•Mo species are well dispersed on the outer surface of catalyst when the Mo-loading is under 5%.•The 5Mo/ZSM-22 catalyst shows a good catalytic activity and stability in the transesterification reaction.