Reactive Extrusion of Lignocellulosic Biomass to Produce Biopolymer Monomers using High-Energy Radiation and Catalytic Acids

The increasing prevalence of bio-based and biodegradable plastics as an alternative to traditional plastics derived from crude oil is a noteworthy trend. Polybutylene succinate (PBS), a plastic produced from succinic acid, is among the promising materials for the future. However, the production of bio-based succinic acid through biotechnical processes in controlled environments presents challenges. This process leads to increased costs and is currently not economically competitive compared to crude oil-based succinic acid production. In addition to succinic acid, levulinic acid is another monomer produced in the same process. A novel approach to the digestion of biomass has been developed to address the issue of biotechnological production of bio-based platform chemicals. This innovative process employs microwave radiation, pressure, and temperature to convert wood residues into succinic acid and levulinic acid. Various catalyst concentrations and biomass ratios were tested in a batch process, with high-pressure liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC/MS) analyses revealing the formation of succinic acid, levulinic acid, formic acid, and 2-oxoglutaric acid. The results demonstrate that microwaves combined with a metal salt catalyst can be used to produce platform chemicals from lignocellulosic biomass. To further advance the continuous production of PBS, a twin-screw extruder was modified and adapted after the successful results obtained from the batch processes. This setup enables additional experiments to evaluate the transferability of batch process results to continuous reactions, facilitating the scale-up and the economic viability of the overall PBS production process in the future.