Conversion of fructose into furfural or 5-hydroxymethylfurfural over HY zeolites selectively in γ-butyrolactone

Furfural is one of the most valuable biomass platform compounds which is typically prepared from hemicellulose. Conversion of cellulose and its derived hexoses, which are the most abundant resource in nature, to furfural, is a big challenge. The amount of the reactive form (fructofuranose) which was beneficial to the formation of furfural and HMF, was increased when the solvent transformed from water to gamma-butyrolactone (GBL)-water. The GBL promoted the adsorption of fructose on HY. The transfer of fructose from the solution to the channels of HY was enhanced with the introducing of GBL in solvent. The HY zeolite with apertures of 7.4 angstrom was found to promote the formation of acyclic fructose from cyclic fructose (8.6 angstrom) in the synergy with GBL. The Bronsted acid sites in the channels of HY favored the selective cleavage of the C-C bond in acyclic fructose to xylose, and promoted the following dehydration of xylose to furfural, simultaneously. The furfural yield was increased while the 5-hydroxymethylfurfural (HMF) yield was decreased with the decrease of the Bronsted acid sites density. The maximum furfural yield was 37.8% over HY-3, while the maximum HMF yield was 69.2% over HY-1 in the conversion of fructose in GBL-water solvent. In addition, the etherification of HMF was the main factor for the low HMF yield and carbon balance in fructose conversion in GBL-water solvent.