Transformational Nano-confined Ionic Liquid Membrane for Greater than or Equal to 97 Percent Carbon Dioxide Capture from Natural Gas Combined Cycle Flue Gas

A transformational process based on nano-confined ionic liquid (NCIL) membranes was developed for capturing ≥97% CO₂ from natural gas combined cycle (NCCC) flue gas. The NCIL membranes were prepared by loading amino acid ionic liquid into a framework composed of single-walled carbon nanotube mesh filled with graphene oxide quantum dots. The membranes exhibited CO₂ permeance as high as 2,000 GPU with a CO₂/N2 selectivity of 2,300 for a typical NGCC flue gas composition. When H₂O vapor sweep was applied in the permeate side, 96.6% CO2 dry-basis purity and 97.6% CO₂ capture rate were achieved for a simulated NGCC flue gas with single stage. In the process design, a highly H₂O-selective membrane would be needed to recover majority of the H₂O vapor, and the recovered H₂O vapor could be recycled to the permeate side of the NCIL membrane. Sulfonated poly(ether ether ketone) membranes were successfully developed for this purpose. These membranes exhibited H₂O permeance great than 11,000 GPU and H₂O/CO₂ selectivity greater than 1,000 at 70ºC for a feed mixture consisting of 14.5 vol% H2O and balanced CO₂. A standalone membrane model using MATLAB platform was developed for process simulation. The model was validated with experimental data. Techno-economic analysis based on the testing data collected during the current program suggests this transformational membrane process can achieve 97% CO₂ capture efficiency with a cost of $47.8/tonne of CO₂, which is a 21% reduction versus DOE’s reference case B31B.97.. Authors: LI, SHIGUANG [Gas Technology Institute, Des Plaines, IL (United States)]; Yu, Miao [State Univ. of New York at Buffalo, NY (United States)]; Wang, Fan [State Univ. of New York at Buffalo, NY (United States)]; Behera, Dinesh [State Univ. of New York at Buffalo, NY (United States)]; Xu, Weiwei [Gas Technology Institute, Des Plaines, IL (United States)]. DOE Contract: FE0032215. Subjects: 03 NATURAL GAS; 20 FOSSIL-FUELED POWER PLANTS; Carbon Capture; Membrane Process; Natural Gas Combined Cycle