Integrated gasification combined cycle (IGCC) plants have demonstrated that coal can be combusted with greater efficiency, but CO2 extraction from the mixed gas stream has proved to be costly. One reason for the expense is that while currently employed ethylene-glycol-based materials (Selexol) are highly selective in removing CO2, they are also hydrophilic, so water must first be removed before the solvent can be used to dissolve the CO2. In order to remove the water, the fuel gas stream must be cooled to 40 ⁰C—a costly and energy-demanding process. Polydimethylsiloxanes (PDMS) have overcome the problem of miscibility in water, but suffer from low selectivity.
This invention describes a method to remove CO2 from a mixed gas stream using a solvent that is not only highly selective, but also has no affinity for water. A hydrophobic solvent allows absorption of CO2 at higher temperatures while eliminating the need for a water removal step at IGCC plants, which will simplify the gas removal process and reduce operating costs while increasing thermal efficiency.
The successful integration of this technology into industrial processes could replace ethylene-glycol-based solvent and PDMS to significantly reduce CO2 from fuel gas streams while simplifying IGCC processes in a cost-effective manner.
