Kinetic study of oleic acid esterification over 12-tungstophosphoric acid catalyst anchored to different mesoporous silica supports

• 12-tungstophosphoric acid anchored to two different supports, MCM-41 and SBA-15
• Catalytic activity for esterification of oleic acid with methanol
• Excellent catalytic activity of TPA3/SBA-15 as compared to that of TPA3/MCM-41
• The size of the support channels plays a crucial role in catalyst performance.

The synthesized catalyst comprising 12-tungstophosphoric acid anchored to two different mesoporous silica supports, MCM-41 and SBA-15, was characterized and used as heterogeneous acid catalyst for biodiesel production by esterification of oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio and reaction time was studied to optimize the conditions for maximum conversion of oleic acid. A detailed kinetic study was carried out and activation energies were determined from the Arrhenius plot. From the kinetic studies it was found that esterification of oleic acid follows first order kinetics with respect to substrate concentration. The activation energy was found to be 44.6 and 52.4 kJ mol− 1 for 12-tungstophosphoric acid anchored to SBA-15 and MCM-41, respectively. Based on the catalytic as well as kinetic studies, 12-tungstophosphoric acid anchored to SBA-15 was found to be a better catalyst.

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