Читать книгу Handbook of Biomass Valorization for Industrial Applications - Группа авторов - Страница 85

N-heterocyclic carbene–silica nanoparticles have been used for glycerol cyclization into cyclic acetals. The catalyst was prepared by immobilization of 1-Butylimidazole onto rice husk ash by 3-chloropropyltriethoxysilane (CPTES). The chlorine of the catalyst was replaced by the phosphate and sulfate group, and the resulting catalysts were named RHABIm-H₂PO₄ and RHABIm-HSO₄ respectively. The RHABIm-H₂PO₄ catalyst show superior catalytic efficiency and selectivity as compared to RHABIm-HSO₄ owing to the presence of extra free acidic proton. The cyclization reaction followed a pseudo-first-order rate low [57].