Hydrothermal Reactive Distillation of Biomass and Biomass Hydrolysates for the Recovery and Separation of Furfural and its Byproducts

The production of furfural is associated with side reactions. Hydrothermal reactive distillation (HRD) can prevent these by continuous stripping of furfural via the vapor phase. However, in recent years, only minor investigations based on real biomass and hydrolysates from biorefineries have been carried out. Additionally, few information exists on the enrichment of byproducts in the sump and condensate. Therefore, two biomasses and hydrolysates were treated at 170-210 °C by using a steam releasing batch reactor. Condensate and sump samples were analyzed regarding reactants, products, and byproducts. Results indicate an excellent performance of the HRD, in terms of furfural yield (∼83 mol %) and purity. No sugars or humins could be detected in the condensate. The main side products in the condensate are acetic and formic acid. In contrast, nonvolatile substances such as levulinic acid and 5-hydroxymethylfurfural are enriched in the sump with a yield up to 23 mol %.