Synthesis of mesoporous sulfated zirconia nanoparticles with high surface area and their applies for biodiesel production as effective catalysts

Sulfated zirconia (SZ) was employed as solid acid catalyst for biodiesel production via the transesterification of soybean oil with methanol. The effects of synthesis method, template/sulfonating agent and calcination temperature were investigated. Compared to conventional two-step route, one-step liquid-crystal template (LCT) method achieved the successful synthesis of mesoporous SZ nanoparticles (MNSZ) with larger surface area, favored the more acid sites, stronger acidity and smaller tetragonal ZrO2 (t-ZrO2). Sodium dodecyl sulfate (SDS), both as template/sulfonating agent, was superior to Hexadecylsulfonic acid sodium salt (CSS) in retarding the grain growth of t-ZrO2, formation of monoclinic ZrO2 phase and loss of sulfated groups. High calcination temperature resulted in the serious loss of acid sites, decrease of surface area and increase in crystal size of tZrO(2), accelerated the transformation of active t-ZrO2 into monoclinic ZrO2, thus leaded to severe decline in catalytic activity. MNSZ, prepared via one-step LCT method at 550 degrees C using SDS as template/sulfonating agent, was found to be the best catalyst. Over this catalyst of 4 wt%, approximately 100% of soybean oil conversion and FAME yield of 94.9% could be achieved at 120 degrees C in 4 h, using the feedstock with methanol/soybean oil molar ratio of 12: 1.