Effect of\nSi/Zr Ratio on the Catalytic Transformation\nof Glycerol to Solketal Over Sulfated Zr-MCM-41 Catalysts

Sulfated Zr-MCM-41 (SZM) was found to be a highly efficient\nand\nreusable mesoporous catalyst with 97% glycerol conversion and 99%\nsolketal selectivity under ambient conditions. All Zr-MCM-41 catalysts\nwere synthesized using the sol–gel method, with varying Si/Zr\nratios ranging from 250 to 40. Subsequently, the catalysts were impregnated\nwith sulfate derived from sulfuric acid. Furthermore, the impact of\nZr content and sulfonation on the rate of reaction was also investigated.\nX-ray diffraction (XRD) and nitrogen sorption investigations provided\nevidence of the mesoporous characteristics of SZM catalysts, demonstrating\na favorable surface area and porosity. SEM-EDAX and TEM investigations\nprovided clear evidence of the preserved spherical morphology and\nhexagonal structure of the MCM-41 material following Zr incorporation\nand sulfonation treatments. XPS results indicated the existence of\nZr and sulfate ions on the catalyst surface. <i>Ex-Situ</i> pyridine-adsorbed IR (Py-IR) and NH<sub>3</sub>-TPD analysis results\nconfirmed that the Lewis/Bronsted acidity of catalysts was boosted\nas the Zr content increased, and this effect was further amplified\nby sulfonation, which was corroborated by the solid-state <sup>29</sup>Si MAS NMR data. The catalyst exhibited sustained activity even after\nbeing used up to five times.