Mesoporous molecular sieves solid superacid as a catalyst for alcoholysis of fructose into methyl levulinate

Abstract

Methyl levulinate (MLE) is an important biomass-based platform compound, which is the precursor of many chemicals. In this paper, a series of zirconium-containing mesoporous molecular sieve superacid Si-SCZ-x (x was the molar ratio of Zr/Si) was prepared by hydrothermal synthesis and applied in the reaction of fructose conversion to MLE. The results indicated that when the molar ratio of Zr/Si was 1.3, Si-SCZ-1.3 presented the highest catalytic activity. Under the optimum reaction conditions (catalyst dosage of 5 mg mL−1, reaction temperature of 160 °C, reaction time of 90 min), the yield of MLE was 70.42%. Si-SCZ-1.3 had a large specific surface area of 246.41 m2 g−1, excellent hydrothermal stability, considerable total acid content and B/L ratio. The recycling catalysts exhibited excellent reusability with little loss of activity after five runs. The reaction path was analyzed in this catalytic system, and the rate-limiting step of the reaction was concluded to be the ring-opening of 5-(Methoxymethyl)-2-furaldehyde to form MLE. This study demonstrated the potential of zirconium-containing mesoporous molecular sieve solid superacid (Si-SCZ-1.3) for the production of MLE under mild process conditions.