Membrane performance requirements for carbon dioxide capture using hydrogen-selective membranes in integrated gasification combined cycle (IGCC) power plants

Precombustion CO2 capture is an important option for the management of greenhouse gas emissions from power generation, because the higher concentrations can lead to improved separation economics. Membranes can provide a significant boost in the performance by separating CO2 at high temperature and at high pressure, provided they are properly integrated into a power plant. In this study, membrane performance targets were derived for CO2 capture using H2-selective membranes in integrated gasification combined cycle (IGCC) power plant systems. Three key differences were found relative to plants configured for the production of industrial-grade H2. First, the H2/CO2 selectivity requirement is lower when the permeate is combusted in a gas turbine, as opposed to purified for industrial use. Second, the membrane is subject to additional selectivity requirements. For example, CO2 product purity specs impose a H2/N2 selectivity requirement. Third, the plant design must account for the energy associated with unshifted CO, CH4 and other fuel components that are not separated by the membrane. In contrast to H2 production systems where the high H2/CO2 selectivity requirement favors ultra-high selectivity metal-based membranes, the requirements for IGCC indicate a wider range of materials, including ceramic, zeolite, and polymeric membranes, should be considered.