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A novel concept of multilayer polymer/zeolite Y composite membrane structure was developed and investigated for CO2 capture from flue gas. Zeolite Y nanoparticles with an average particle size of 40 nm were successfully deposited onto flexible polymer supports with uniform coverage by the vacuum-assisted dip deposition approach. The zeolite Y dispersion concentration was varied for different commercial polymer supports to obtain a crack-free zeolite Y layer. Scanning electron microscopy (SEM) analysis indicated that a uniform zeolite Y layer could be formed either on Biomax polyethersulfone (PES) membrane or on TM10 polyvinylidene fluoride (PVDF) membrane with appropriate vacuum-assisted dip deposition conditions. Atomic force microscopy (AFM) analysis showed that the zeolite Y/Biomax PES substrate was smoother than the zeolite Y/TM10 PVDF substrate. The Pebax®/PEG-200 membrane prepared on the zeolite Y/Biomax PES substrate exhibited higher CO2 permeance than that prepared on the bare Biomax PES support since the penetration of the polymer membrane was minimized by the smaller interparticle pore size on the zeolite Y layer. The membrane of the multilayer composite structure showed a CO2 permeance of 745 GPU and a CO2/N2 selectivity of 25.4 under flue gas operating conditions at 57 °C and ~1 atm. This concept has provided the basis for high performance membranes with the selective polymer cover layer containing amino groups and for grown zeolite Y membranes with continuous polycrystalline structure supported by the flexible polymer substrate.

In recent years, integrated gasification combined cycle (IGCC) technology has gained significant attention for large-scale power generation with carbon capture. In an IGCC power plant, the syngas is typically directed to the gas turbine (for power generation) after CO2 and H2S removal. This work describes the transport properties of the CO2-selective polymeric facilitated transport membranes for syngas purification at different pressures (2–15 bar) and 107 °C. These membranes contain amines as CO2-carriers that are dispersed in a crosslinked polyvinylalcohol (PVA) matrix. Furthermore, a two-stage membrane process is proposed for CO2 removal from syngas in an IGCC plant. A process modeling and cost-sensitivity analysis of the proposed two-stage membrane process was performed. The effects of feed pressure, temperature, membrane permeance, and selectivity on the overall increase in the cost of electricity (COE) were analyzed. An increase in the COE of 14–18% was estimated for 90% CO2 removal and >99% H2 recovery using the two-stage membrane process in an IGCC power plant.

Carbon capture in a postcombustion scenario needs cost-effective and energy-efficient alternatives to the amine process. High performance membranes can potentially meet the stringent cost targets set by the U.S. Department of Energy (DOE). In this context, we review and identify the most promising membranes/membrane materials along with the most innovative membrane-based processes reported recently in literature. The important transport results were grouped into different categories depending upon the mechanism of selective CO2 transport through the respective membrane. The analysis of the literature results indicates that each type of membrane demonstrates one or more of the important trade-offs including selectivity–permeability, selectivity–permeance, transport-ease of synthesis, and transport–stability. Reproducible and large-scale production of thin films from existing and new highly permeable materials while maintaining a reasonable selectivity along with innovation in process schemes that utilize multiple membranes with different and unique benefits were identified as key tasks to realizing a membrane-based alternative for this application.