Hydrophilic sulfonic acid-functionalized micro-bead silica for dehydration of sorbitol to isosorbide

Abstract

Different (3-mercaptopropyl)trimethoxysilane (MPTS) loadings of sulfonic acid-functionalized micro-bead silica (SA-SiO₂) were prepared by silylation and oxidation, and characterized by elemental analysis, SEM, FT-IR, TGA, NH₃-TPD, BET N₂ adsorption–desorption and ¹³C NMR CP/MAS. The as-prepared SA-SiO₂ showed strong hydrophilic nature and excellent catalytic performance for dehydration of sorbitol to isosorbide. The selectivity to isosorbide is obviously affected by the MPTS loading. Using SA-SiO₂ as a solid catalyst with 60.5% MPTS loading, 100% sorbitol conversion and 84% yield of isosorbide are achieved at 120 °C for 10 h under vacuum. The catalyst was reused 10 times without noticeable loss of activity and selectivity.