Effective transesterification of triglyceride with sulphonated modified SBA-15 (SBA-15-SO3H): Screening, process and mechanism

Different morphologies of ZrO2 were produced by different templates: ZrO2(CaCO3), ZrO2(C12H25SO3Na), ZrO2(C12H25SO4Na), ZrO2(CTAB), and solid superacids, such as ZrO2/SBA-15, SO42-/ZrO2, SO42-/ZrO2/SBA-15, and SBA-15-SO3H. The catalytic transesterification activities of these catalysts were tested. The more highly acidic catalysts and higher surface areas led to higher catalytic activity. In particular, the conversion yield of triglyceride reached 90.1% and was maintained for 90 min at 200 degrees C with 5.0 wt% SBA-15-SO3H, indicating this material to be one of most effective acid catalysts for the transesterification process. The mechanism indicated that the most important process was the abstraction of hydrogen from alcohols and alpha-substituted carboxylic glycerides. In the initial transesterification, the alcohol hydrogen atoms could be attracted onto the surface. Then, the nucleophilic attack of the alcohol led to the alpha-substituted carboxylic glyceride. Finally, mono-glycerides, diglycerides or glycerine were released from the surface by proton (H+) replacement.