Recycling of Sulfuric Acid in the Valorization of Biomass Residues
The biomass-based production of levulinic acid requires aqueous mineral acid as catalyst. In the present study, the possible reuse of sulfuric acid in the biomass conversion was investigated. The acid can either be reused after extracting the product or before extraction. The results show that both methods are applicable for producing levulinic acid while reducing the sulfuric acid demand of the process. Conversion of D-fructose showed similar results after five recycle steps in both post- and pre-extraction methods. The post-extraction method was successfully repeated four times with cooked tea leaves. The sulfuric acid applied for the conversion of a simulated household waste was successfully recycled eight times with pre-extraction plus once by post-extraction without significant change in the product formation.