CFD modeling of a membrane reactor concept for integrated CO2 capture and conversion

Capturing CO2 and converting it into valuable products represents a future direction of carbon emissions reduction. The emergence of CO2-permeable membranes has opened up a broad range of new opportunities for efficient CO2 capture and conversion. In this context, this study develops a membrane reactor concept using a ceramic-carbonate dual-phase membrane for integrated CO2 capture and conversion. The membrane reactor has two concentric tubes, with the inner tube being for the flue gas to provide a CO2 source and the outer for the CO2 conversion. The catalyst is coated on the membrane surface instead of being packed in the reactor bed so that the permeated CO2 can be immediately converted, and the CO2 permeation flux can be significantly promoted in this manner. The performance of the developed membrane reactor concept is evaluated based on CFD simulations. The membrane reactor can achieve high CO2 capture rates of over 90% and conversions of up to 95% for the reaction of the reverse water gas shift. The CO productivity is limited by the membrane permeation flux and large reactor volume, and can be increased by compact designs that increase the ratio of the membrane area to the reactor volume, which are simple but effective approaches to increasing CO productivity, but maintain high CO2 capture rates and conversions. The developed membrane reactor concept can be readily applied to any other reaction for integrated CO2 capture and conversion.