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

Abstract

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.