Conversion of bioplatform molecule, succinic acid to value-added products via esterification over 12-tungstosilicic acid anchored to MCM-22

Highlights: • Sustainable approach for synthesis of fuel components & green chemicals. • Solvent-free esterification of bioplatform molecules, derived from renewable resources. • Excellent conversion (97%) & diester (fuel component) selectivity (59%), with high TON. • Versatile reactivity of catalyst, 12-tungstosilicic acid anchored to MCM-22, with other biomass derived molecules. The model bioplatform molecule succinic acid, via esterification with n-butanol, leads to succinate esters, promising fuel additives and value-added products. In the present article, the potential application of heterogeneous catalyst comprising silicotungstic acid (SiW₁₂) and MCM-22 (SiW₁₂-MCM-22) was exploited for esterification of succinic acid with n-butanol. Performance of the catalyst was examined by carrying out a detailed optimization study, focusing on the synthesis of diester (one of the excellent fuel additives) and kinetic experiments at different reaction time and temperatures. The experimental results exhibit synergistic effect of SiW₁₂ and MCM-22, yielding 97% conversion of acid with 59% selectivity of diester, TON of 1214 and activation energy of 68 kJmol^-1. Experiments to demonstrates the effectiveness of High Gravity approach were also performed. The green metrics, atom economy (86.47%) (for desired diester) with E-factor (0.69) were calculated. The catalyst was recovered and used for consecutive three catalytic cycles, exhibiting remarkable regenerative activity to synthesize esters and contribute new routes for industrial scale.