Carbon Dioxide Capture Using Ionic Liquid 1-Butyl-3-methylimidazolium Acetate

Carbon dioxide (CO2) capture using aqueous amine scrubbing is currently considered the most feasible option for separating CO2 from post-combustion flue gas. Using simple absorption and stripping configurations, monoethanolamine has been commercially demonstrated to effectively scrub CO2 from post-combustion flue gas. However, the current capital and operating costs are high and do not meet the target of the Department of Energy to remove 90% of CO2 from post-combustion flue gas with no more than a 35% increase in the cost of electricity. The evaluation of advanced absorbents, adsorbents, and membranes is under way to find the most energy-efficient CO2-capture technology. We have modeled an ionic liquid that can reduce the energy losses by 16% compared to a commercial monoethanolamine process. The choice of the ionic liquid, 1-butyl-3-methylimidazolium acetate, has not been optimized but was chosen based on chemical absorption behavior and the desire to understand performance. Engineering design estimates indicate that the investment for the ionic liquid process will be 11% lower than the amine-based process and provide a 12% reduction in equipment footprint. A parametric study examined four improvements in the ionic liquid technology, which may reduce even further the energy and cost required for CO2 capture.