Sustainable Butyl Rubber Production from Microbial Isobutanol-Derived Isobutylene

Isobutylene, a monomer for butyl rubber production, is traditionally obtained via the thermal cracking of natural gas. However, this route should be superseded by those that rely on the chemical or biological valorization of renewables to reduce our dependence on fossil resources. Despite extensive research on biobased butyl rubber, its economically viable large-scale production from bioisobutylene remains underexplored. This study develops a process for the microbial production of isobutanol and its conversion to isobutylene and butyl rubber. The fermentation of glucose by metabolically engineered Escherichia coli afforded isobutanol, which was removed from the culturing medium via absorptive vapor capture using water in a recovery tower to prevent cytotoxicity-related problems, concentrated via batch distillation and selectively dehydrated to isobutylene over γ-Al2O3/HCl. The low-temperature cationic copolymerization of isobutylene with isoprene afforded butyl rubber with properties suitable for commercial applications. Computational modeling validated the efficiency of the absorption tower and underscored the need for a multistage distillation tower for optimal isobutylene recovery. This study presents a framework for sustainable chemical production and contributes to the development of ecofriendly and commercially viable technologies.