Evaluation of Pd composite membrane for pre-combustion CO2 capture

Abstract Carbon capture with hydrogen-selective Pd membranes can be realized as highly integrated process and CO 2 can be separated at high pressure without employing environmentally harmful sorption agents. This study investigates the technical viability of using ultrathin Pd/ceramic composite membranes with innovative ceramic-to-metal connections under conditions that are practically interesting for natural gas-fired power stations, i.e. high feed and permeate pressures and high H 2 recovery at elevated temperature. The 90% CO 2 capture target was well exceeded during a 150 day test in water gas-shifted reformate at 673 K. After system stabilization 98% carbon were held back by the membrane while 98% H 2 were separated at nominally 99.5% H 2 purity. Special attention has been paid to long-term operation effects on the 2–4 μm thick Pd layer. These include the development of a striking, cavernous Pd morphology which increases mechanical stability of the composite membrane, a somewhat reduced but steady H 2 permeability, and the disappearance of most membrane defects. The latter is attributed to carbon deposits as exit flow analyses point to CO 2 reduction preserving effectively membrane selectivity. Altogether, carbon capture with supported Pd membranes projects as feasible from a technological vantage point.