One-pot conversion of wheat straw into biobased chemicals in methanol/water medium using cheap mixed acid catalyst.

Abstract

Environmental concerns and the diminishing availability of unrenewable resources have spurred research into the use of agricultural waste as a feedstock for industrial applications. Efficient conversion of wheat straw into biobased chemicals is an important way to realize the potential value of renewable agricultural biomass. This study investigated one-pot conversion of wheat straw into two notable platform chemicals, levulinic acid (LA) and methyl levulinate (ML). A mixed acid catalyst system, including 1% H2 SO4 and 0.015mol L-1 Al2 (SO4 )3 , was an efficient catalyst for the conversion of wheat straw due to the combination of Brønsted acid and Lewis acid. A ratio of wheat straw to methanol of 5g/50 mL was identified as the preferred solid/liquid ratio, and a methanol/H2 O medium with 25% water content aided the simultaneous production of LA and ML from wheat straw. Under optimum conditions, the maximum total yield of LA and ML reached 23.01% at 220 °C and 3h. The kinetics of biobased chemical formation and the reaction pathways in methanol/water were investigated. The presence of water in the methanol/H2 O medium affected the distribution of products and promoted hydrolysis reactions. The methanol/H2 O medium not only inhibited the side reactions but also promoted the degradation of wheat straw and increased the total yield of LA and ML. This study provides a feasible method for the conversion of wheat straw to prepare biobased chemicals. © 2021 Society of Chemical Industry.