Poly (ionic liquid)s-silica spheres as effective core-shell catalysts for the conversion of glucose and fructose into 5-hydroxymethylfurfural

Abstract

5-Hydroxymethylfurfural (5-HMF), as a significant, bio-derived platform chemical molecule, has been under extensive research due to its wide application in petrochemical industry. In this work, three kinds of poly (ionic liquid)s-silica spheres (PIL@SiO2) with various lengths of alkyl chains as effective core-shell catalysts were prepared by the polymerization and coating methods, and were used to prepare 5-HMF from glucose and fructose with optimal results. When the alkyl carbon number of PIL monomer was 18, PIL@SiO2-18 displayed good catalytic activity in 5-HMF production, resulting in the highest yields of 77.36% and 72.8% from glucose and fructose in methyl isobutyl ketone (MIBK)/ saturated solution of sodium chloride (Sat.NaCl) biphasic solvent. A possible reaction mechanism was proposed that the core-shell synergistic catalysis effectively promoted the preparation of 5-HMF from monosaccharide, in which Lewis acidic polycationic centers contributed to driving the isomerization process. The promising approach provides an efficient strategy for silica-based core-shell synergistic catalysts in the synthesis of 5-HMF from carbohydrates.