Direct synthesis of mesoporous 12-tungstophosphoric acid SBA-15 catalyst for selective esterification of glycerol and lauric acid to monolaurate

• Direct synthesis method of 12-tungstophosphoric acid SBA-15 catalyst.
• Surface characteristics retention at anions concentration below 20 wt.%.
• Formation of tungsten oxides at anions concentration above 20 wt.%.
• Direct esterification of glycerol with lauric acid to monolaurate.
• Elucidation of effects of process variables.

Via direct synthesis method, highly uniformed SBA-15 catalysts functionalized with 12-tungstophosphorus acid (HPW) were synthesized. Their characteristics were investigated using BET surface analysis, NH3-TPD, FTIR, SEM, TEM, EDS and TGA. Surface defects were found in catalysts with high HPW loading (30–40 wt.%). High loadings also caused the deposition of HPW on the external surface and subject to oxidative decomposition to WO3 that affected their acidity. HPW in mesopores had better thermal stability. High lauric acid conversion (70%) and monolaurin yield (50%) were shown in 6 h at 160 °C by the catalyst with 20 wt.% HPW. Lower yield was achieved at higher temperature. Its ordered mesoporosity evidently resulted in shape selectivity effect to suppress by-products formation. Effects of reaction temperature (150–170 °C), reactant ratios (1:1–5:1) and catalysts loadings (1–5 wt.%) were thoroughly elucidated.

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