Process Simulation of Isoprene Recovery from Dilute Fermentation Off-Gas Using Absorption–Desorption

Abstract The recovery of biobased isoprene from dilute fermentation off-gas remains a major challenge due to low product concentrations and energy-intensive downstream separations. In this study, a process intensification strategy based on absorption–desorption was developed and evaluated to efficiently recover isoprene from air mixtures. The proposed system integrates absorption using 3-methyltridecane, vacuum degassing, steam stripping, and condensation with multiple recycle loops for solvent, water, and residual isoprene. Of the thermodynamic models examined, the Peng–Robinson equation of state was used for the absorption section while UNIFAC was used for steam stripping. Process optimization demonstrated up to 95% isoprene recovery and 98% product purity while significantly reducing energy consumption. Sensitivity analyses revealed that solvent temperature, solvent-to-feed ratio, and feed isoprene concentration strongly influence process efficiency, with energy demand decreasing from 26 to 10 MJ kg–1 as feed concentration increased. Compared to literature benchmarks, the proposed design achieved up to 40% reduction in steam usage. These results highlight absorption-based separation as a viable and energy-efficient pathway for recovering volatile hydrocarbons from dilute bioprocess streams and provide design insights for future scale-up and experimental validation.