Comparative Analysis of MEA Absorption and Membrane Separation for FCCU CO ₂ Capture: Process Simulation and Techno-Economic Evaluation

Fluid Catalytic Cracking Units (FCCUs) are major contributors to refinery CO2 emissions, accounting for up to 30% of the total. While CCS is recognized as a key mitigation strategy, comparative evaluations of alternative capture technologies under consistent operating conditions remain limited. This study investigates three FCCU–CCS configurations: postcombustion chemical absorption with monoethanolamine (PCC-MEA), postcombustion polymeric membrane separation (PCC-Membrane), and oxy-combustion chemical absorption (OCC-MEA). Process simulations were developed in Aspen HYSYS v14, including flue gas conditioning, capture units, compression, and TEG dehydration. Key performance indicators, fixed capital investment (FCI), net present value (NPV), and a marginal abatement cost curve (MACC) were assessed using CAPCOST methodology. All scenarios achieved >90% CO2 capture efficiency and >99.9 mol % product purity. PCC-MEA and OCC-MEA reached ∼95% efficiency with 77.6 and 105.4 t·h–1 of CO2 captured, respectively, while the PCC-Membrane achieved 99.9% efficiency and 108.2 t·h–1 of CO2 captured. The economic analysis showed NPVs of −970.6 MMUSD (PCC-MEA), −1214 MMUSD (PCC-Membrane), and −1138.6 MMUSD (OCC-MEA), compared with −617.5 MMUSD for the base FCCU, resulting in abatement costs of 22–27 USD·t–1 CO2. The comparative analysis shows that PCC-MEA remains the most cost-effective option, membranes provide the highest capture efficiency at higher cost, and OCC-MEA offers a compromise benefiting from richer flue gas composition. These findings highlight both the technical feasibility and the economic challenges of deploying CCS in FCCUs, underlining the need for supportive policies and further optimization to enable large-scale implementation.