Efficient conversion of wheat straw into methyl levulinate catalyzed by cheap metal sulfate in a biorefinery concept

Wheat straw can be converted into biofuel candidate-methyl levulinate with copper sulfate as the cheap catalyst. To take advantage of the whole components of wheat straw, a two-stage pretreatment process was developed in this study. In the first-stage process, the hemicellulose component in wheat straw can be converted into biosurfactant at the mild conditions, and the lignin component can be extracted as another value added by-product in the second stage. On the basis, the pretreated wheat straw was used as raw material for methyl levulinate production, and a yield of 20.2 wt% can be obtained under the optimum reaction conditions. Meanwhile, the catalyst recycling experiments showed that copper sulfate was stable and can be reused more than five times. The results of mass balances and preliminary economic analysis further indicated that the production of integrated biorefinery processes producing diversified products offers potential for the sustainable valorization of wheat straw.