Selective preparation of 5-hydroxymethylfurfural by catalytic fast pyrolysis of cellulose over zirconium-tin mixed metal oxides

Abstract

5-Hydroxymethylfurfural (5-HMF) is a value-added platform chemical, which can be obtained from pyrolysis of biomass materials, whereas related investigation on its selective production via catalytic fast pyrolysis (CFP) process is still insufficient. In this work, a zirconium-tin mixed metal oxide (ZrO2-SnO2) catalyst was developed for the selective production of 5-HMF from the in-situ CFP of cellulose. According to pyrolysis-chromatography/mass spectrometry (Py-GC/MS) tests, the ZrO2-SnO2 catalyst has better performance on the selective preparation of 5-HMF than single nano oxide ZrO2, SnO2, or their physical mixture. 5-HMF was sensitive to the reaction conditions, and its yield and selectivity always exhibited the tide of first increasing followed by decreasing along with the increase of Zr loading and catalyst-to-cellulose (CA-to-CL) ratio. At the optimum conditions with ZrO2-SnO2 of 15 wt% Zr loading (ZrO2-SnO2-15), pyrolysis temperature of 350 °C and CA-to-CL ratio of 2:1, the 5-HMF yield was 6.49 wt%, which was 4 times more than that of the non-catalytic process (1.35 wt%). Correspondingly, the selectivity of 5-HMF was up to 23.50 %. The catalyst characterization combined with the pyrolysis texts of several typical saccharides, including cellobiose, maltose, glucose, and mannose indicated that the ZrO2-SnO2-15 could promote the breakage of glycosidic bonds with the formation of reducing ends and the selective conversion of the reducing end to 5-HMF due to its mild acidity. Overall, the ZrO2-SnO2 is expected a promising catalyst for the CFP of cellulose to prepare 5-HMF.