Highly efficient conversion of glucose to methyl lactate over hierarchical bimetal-doped Beta zeolite catalysts

BACKGROUND Methyl lactate is widely applied in the chemical, food, cosmetics and pharmaceutical industries. The conversion of carbohydrates over heterogeneous catalysts to methyl lactate is a promising environmentally benign process. RESULTS Hierarchical Sn-Beta zeolite (Sn-Beta) and corresponding bimetal-doped Beta zeolites (M-Sn-Beta; M = Zn, In, La, Ga, Ni) were prepared via a novel modified hydrothermal synthesis method to convert carbohydrates into methyl lactate. The introduction of Zn into Sn-Beta considerably improved the yield of methyl lactate from glucose, while for the catalysts containing In, La, Ga and Ni, such improvements were not observed. CONCLUSIONS A methyl lactate yield reaching up to 66.7% was obtained over Zn-Sn-Beta at 220 degrees C for 6 h. The enhanced catalytic performance was attributed to high Lewis acid density and strength, together with synergistic effects between framework Sn4+ and Zn2+ ions of Zn-Sn-Beta. Additionally, Zn-Sn-Beta demonstrated fructose and sucrose conversion into methyl lactate with yields of 68.4% and 70.0%, respectively. The Zn-Sn-Beta catalyst could be re-used at least five times with only a slight loss of methyl lactate yield. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

The addition of zinc significantly improved the yield of methyl lactate from glucose, while other metals like indium, lanthanum, gallium, and nickel did not show the same improvements. The Zn-Sn-Beta catalyst showed a methyl lactate yield of 66.7% at 220 degrees Celsius.