Direct, efficient and selective capture of low concentration of CO2 from natural gas flue gas using a high temperature tubular carbon capture membrane

Abstract

Natural gas (NG) fired power plants emit low concentration (4–5%) of CO2, which presents additional technical and economic challenges to the current benchmark amine absorption technology. The newly emerged high-temperature multiphase membranes operated on molten carbonate (MC) chemistry for CO2 capture/separation/conversion have been demonstrated with great potential to meet this challenge. In this study, we report on the CO2 capture performance of such a membrane in tubular geometry from a mockup NG flue gas. The membrane is comprised of a mixture of Gd0.20Ce0.80O1.95 (GDC) and MC, in which GDC forms a porous skeleton to contain MC. We show that the membrane with a dimension of 6.1 mm in outer diameter, 5.1 mm in inner diameter and 5 cm in effective length (resulting in 4 cm2 effective surface area) can achieve a CO2 flux density of 0.46–0.55 mL/min·cm2 at 650 °C, capturing 97% pure CO2 at a rate of 37–42% from 5%CO2–N2 using moistened Ar as the sweep gas. The level of performance demonstrated by this study suites the membrane well for stationary CO2 capture from NG power plants.