A New Ceramic–Carbonate Dual-Phase Membrane for High-Flux CO<sub>2</sub> Capture
Shichen Sun, Yeting Wen, Kevin Huang
Abstract
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/cm2/min at 650 °C with 15% CO2/75% N2/10% O2 and 50% CO2/N2 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.