Highly Effective Fe-TPA Immobilized SBA-15 and SBA-16 Mesoporous Catalysts for Solketal Production from Glycerol

The surplus glycerol produced as a byproduct of biodiesel manufacturing offers significant potential for valorization through its conversion into value-added chemicals such as solketal, a promising fuel additive and environmentally benign solvent. In this study, Fe-TPA nanoparticles were synthesized and immobilized onto SBA-15 and SBA-16 mesoporous supports at varying loadings (20%, 30% and 40%) to develop efficient solid acid catalysts for the acetalization of glycerol with acetone. The catalysts were systematically characterized using XRD, FT-IR, BET, pore size distribution, SEM-EDS, XRF, NH₃-TPD and DRIFT analyses, confirming successful incorporation of Fe-TPA and revealing correlations between mesostructural properties, acidity and catalytic behavior. Among the catalysts, 40% Fe-TPA/SBA-15 displayed the best performance, achieving 100% glycerol conversion and 97% solketal selectivity under mild conditions (35 °C, 1:6 glycerol-to-acetone molar ratio, 4 wt% catalyst). Its superior activity is attributed to its high surface area, well-ordered pore structure and enhanced total acidity. The catalyst also exhibited excellent stability and reusability over multiple cycles, showing minimal loss of activity. Thus, the results demonstrate that Fe-TPA/SBA-15 is a highly efficient and robust heterogeneous catalyst for sustainable solketal production, presenting a promising strategy for glycerol valorization within biodiesel-based biorefineries.