Process modeling and sensitivity analysis for integrated carbon capture and conversion with ionic liquids

Abstract

Integrated carbon capture and conversion (ICCC) processes convert captured CO₂ directly in the capture medium, avoiding the solvent regeneration, separation, and compression required in conventional capture–conversion (CCC) schemes. We present a prototype ionic liquid (IL)-based ICCC process integrated with an ethylene plant, producing methanol via

hydrogenation. A sensitivity analysis evaluates process energy use with respect to (1) CO₂ removal rate and (2)

conversion, under both mass-transfer- and reaction-rate-limited regimes. Results show that energy demand is strongly linked to IL recirculation and vapor recycle rates. Importantly, a reaction-rate-limited regime is advantageous: fast CO₂ absorption (even with slower hydrogenation) allows unreacted CO₂ in the vapor recycle to be reabsorbed, lowering flowrates and energy use. Because purging in the conversion loop affects net CO₂ removal, it is critical to design ICCC processes holistically, integrating capture and conversion to optimize overall carbon and energy efficiency.