A New Ceramic-Carbonate Dual-Phase Membrane for High-Flux CO2 Capture

High-temperature membrane-based electrochemical CO2 capture technology is advantageous in achieving high CO2 flux without selectivity constraint over its low-temperature counterparts. A high operating temperature also allows in situ catalytic conversion of the captured CO2 into valuable products in the same reactor, thus reducing the overall product cost. Ceramic-carbonate dual-phase membranes are a new class of high-temperature CO2 capture technology that emerged in recent years, in which the ceramic phase plays a crucial role in the performance. We here report on porous Sc- and Ce-stabilized zirconia (ScCeSZ) as a new ceramic phase in the membrane. The study finds that the wettability between ScCeSZ and molten carbonate (MC) is rather poor, thus requiring surface modification of the ScCeSZ matrix by a wetting agent such as Al2O3. The surface-modified ScCeSZ-MC membranes show the highest CO2 flux density among all ceramic-carbonate dual-phase membranes previously reported, reaching 0.5 and 1.0 mL/cm(2)/min at 650 degrees C with 15% CO2/75% N-2/10% O-2 and 50% CO2/N-2 as the feed gas, respectively. Long-term testing on the membrane indicates a reasonable flux stability over 200 h. The study also observes that the presence of steam in the sweep gas boosts the CO2 flux density by 50% without compromising the stability. A mechanism is given to explain the flux enhancement.