Water vapour adsorption by a coffee-based microporous carbon: effect on CO2capture

Abstract

BACKGROUND Carbon materials are appealing adsorbents for postcombustion CO2 capture applications. In the present work, the adsorption of H2O, which is an abundant component in flue gases, and its influence on the adsorption of CO2 is evaluated using a microporous carbon. RESULTS The adsorption and desorption isotherms of H2O at 12.5, 25, 50, 70 and 85 °C were obtained for relative pressures between 0 and 0.95. The average isosteric heat of adsorption of H2O on PPC is 46 kJ mol−1. The equilibrium of adsorption and desorption of H2O on PPC can be reasonably well described by the DJD model over the entire temperature and pressure range evaluated. Breakthrough experiments carried out with synthetic flue gas showed that the adsorption of CO2 is not hindered by H2O at short adsorption times, relevant for the adsorption of CO2. Moreover, PPC can be fully regenerated recovering its full adsorption capacity after extended exposure to humid gas. CONCLUSIONS Although the adsorption capacity of CO2 can be reduced by the coadsorption of H2O, this effect only becomes significant at long adsorption times. By appropriately selecting the adsorption time in the cyclic process design the concentration of CO2 in the adsorbed phase can be maximized. © 2015 Society of Chemical Industry