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, SO₄^2-/ZrO₂, SO₄^2-/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 °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 α-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 α-substituted carboxylic glyceride. Finally, monoglycerides, diglycerides or glycerine were released from the surface by proton (H⁺) replacement.