Direct transformation of carbohydrates to the biofuel 5-ethoxymethylfurfural by solid acid catalysts

The direct conversion of glucose to 5-ethoxymethylfurfural (EMF) is a promising biomass transformation due to the potential application of the product as a biofuel. Here, the conversion of glucose to EMF was examined over several solid acid catalysts in ethanol between 96 and 125 degrees C. Among the catalysts employed, dealuminated beta zeolites [DeAl-H-beta-12.5 (700)] gave a moderate yield of EMF (37%) in a single step catalytic process. A combined catalytic system consisting of H-form zeolite and Amberlyst-15 was found to be more efficient for the transformation of glucose to EMF (46%) via a one-pot, two-step reaction protocol. Alternative biomass-based mono-, di- and polysaccharides also gave moderate to good yields of EMF with the catalytic systems, including fructose which yielded 67% of EMF and 4% of ethyl levulinate (ELevu) along with 10% 5-hydroxymethyl furfural (HMF) in the combined reaction protocol. A significant amount of ELevu (1-16%), a rehydrated product of EMF and a promising fuel additive, was observed in this study. Recyclability studies suggested that it was possible to reuse the DeAl-H-beta-12.5 (700) catalyst in consecutive reactions without significant changes in product yields due to its easy recovery and thermal stability during regeneration.