1 Precombustion CO2 capture by means of phenol-formaldehyde resin-derived carbons: from equilibrium to dynamic conditions

The performance of two phenol-formaldehyde resin-based activated carbons prepared in our laboratory, as potential adsorbents for precombustion CO2 capture has been evaluated under static (adsorption isotherms) and dynamic (adsorption-desorption cycles conducted in a fixed bed) conditions. Most of the literature on CO2 capture with solid sorbents is based on equilibrium CO2 adsorption capacities, determined from CO2 adsorption isotherms at the desired temperature. However, dynamic testing is required to ascertain the extent to which the equilibrium uptake may be translated into breakthrough capacity. CO2 and H2 adsorption isotherms up to 30 bar were determined in a high-pressure magnetic suspension balance. Equilibrium CO2 uptakes at 15 bar of up to 8.5 mmol g-1 at 298 K and 7 mmol g-1 at 318 K were attained. Adsorption-desorption cycles by means of pressure and temperature swings were conducted with a simulated shifted-syngas in a purpose-built fixed-bed set-up. With a ternary mixture of CO2/H2/N2, breakthrough capacities at a total pressure of 15 bar reached 6.5 mmol g-1 at 298 K and 5.8 mmol g-1 at 318 K. These figures point out the suitability of these adsorbents to be applied to precombustion CO2 capture by means of a PSA process