Promotion effect of mesopore on the conversion of carbohydrates to methyl levulinate over H-USY zeolite

• Mesopores were formed on USY zeolite by treatment with nitric acid.
• Acid in low concentration mainly removes extraframework Al.
• Acid sites are primary for the conversion of glucose to MLE.
• Mesopores promote the efficiency of acid sites.

H-USY was treated with nitric acid solution to remove Al species and thus adjust the mesoporosity and acidity. Effects of mesopore and acidity of H-USY zeolite were studied on the conversion of carbohydrate to methyl levulinate (MLE). Low concentration of nitric acid mainly removed the extraframework aluminum species with the increase of mesoporosity and resulted in a slight decrease of acidity. Both extraframework and framework Al species were removed to some extent under high concentration of nitric acid, associating with the obvious decrease of acidity. H-USY treated with low concentration of nitric acid showed higher yield of MLE than H-USY-parent. Generated mesopores improved the diffusion limitations, facilitated the accessibility of reactant to the acid sites, and thus promoted the formation of MLE.

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