Carbon dioxide capture using phase change ionic liquids

Disclosed herein are methods for CO.sub.2 capture that use phase change ionic liquids (PCILs) to remove the CO.sub.2 from flue gas or other gas streams containing CO.sub.2. PCILs have high CO.sub.2 uptake and form a liquid PCIL-CO.sub.2 complex when they react with C( ).sub.2. When the liquid PCIL-CO.sub.2 complex is heated to regenerate the solid PCIL material by removing the carbon dioxide, part of the heat needed to release the CO.sub.2 can be supplied by the heat of fusion of the PCIL as it solidifies. Utilization of the heat of fusion of the PCIL to assist in its own regeneration can substantially reduce the parasitic energy loss associated with post-combustion CO.sub.2 capture.