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Novel allylimidazolium-based ionic liquids (ILs) with Brønsted acid functionalities, bearing triflate ([ASBI][TfO]) and sulfate ([ASBI][HSO₄]) anions, along with their Lewis acid derivatives ([ASCBI][TfO] and [ASCBI][HSO₄]), were synthesized and covalently immobilized on silica via a thiol (-SH) anchoring group. Comprehensive characterization—including FTIR, thermogravimetric analysis (TGA), elemental composition, N₂ adsorption, and acidity measurements—confirmed successful immobilization and high surface acidity. These hybrid materials acted as efficient Brønsted and Lewis acid catalysts in the esterification of glycerol (C₃H₈O₃) with acetic acid (CH₃COOH), exhibiting superior selectivity toward diacetin (DAG) and triacetin (TAG) compared with conventional heterogeneous acid catalysts. Low-conversion studies were used to distinguish between 1,3- and 1,2-diacetin formation. Investigations with diols of varying chain lengths demonstrated that diacetin selectivity is strongly influenced by substrate structure. Among the catalysts, SiO₂-[ASBI][HSO₄] exhibited the highest activity and was further studied to evaluate the influence of reaction time, temperature, catalyst loading, and glycerol to-acetic acid molar ratio on product distribution. The immobilized ionic liquids showed excellent recyclability, thermal stability, and catalytic efficiency, indicating their potential for sustainable glycerol valorization.