Solid acid catalyzed glucose conversion to ethyl levulinate

A series of solid acid catalysts including SO42−/ZrO2, SO42−/TiO2, SO42−/ZrO2–TiO2 and SO42−/ZrO2–Al2O3 were prepared by precipitation and impregnation method for ethyl levulinate production from glucose in ethanol. Effects of various reaction parameters and catalyst reuse cycle towards the reaction performance were studied. Experimental results showed that different components of the sulfated metal oxides had markedly different catalytic effects on the ethanolysis of glucose. SO42−/ZrO2–Al2O3 could significantly suppress the formation of ethyl levulinate due to the incorporation of Al2O3. With SO42−/ZrO2 as the catalyst, an optimized ethyl levulinate yield of above 30 mol% was obtained at 200 °C for 3 h with catalyst dosage of 2.5 wt%, and the recovered catalyst after calcination was found to remain active with an almost unchanged product yield after being reused five times. The main liquid substances including ethyl levulinate, diethyl ether and ethanol can be easily separated from the resulting product mixture by fractionation and the excess ethanol was recycled. The physicochemical properties of the prepared and thermally regenerated catalysts were characterized using BET surface area, XRD, NH3-TPD and XPS techniques.

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► SO42−/ZrO2 is found to be efficient in the conversion of glucose to ethyl levulinate.
► A maximum ethyl levulinate formation yield of ca. 30 mol% was obtained from glucose.
► SO42−/ZrO2–Al2O3 can suppress the formation of ethyl levulinate from ethyl glucoside.
► The effect of small amounts of water present in ethanol is thought to be negligible.
► SO42−/ZrO2 after calcination can be reused multiple times with similar product yield.