High capacity adsorbents for CO2 capture in gasification

During gasification, and after the water gas shift reaction where CO2 is at high pressure, “physical” adsorbents with weak basic functionality are required for CO2 capture, as opposed to the strong basic functionalities required at low pressures. In this study, a number of novel AC adsorbents, prepared from phenolic and urea formaldehyde (UF) resins, and polyacrylonitrile (PAN), and possessing a range of surface areas, have been evaluated. Equilibrium uptake measurements have been conducted in a dual limb differential pressure rig and an Intelligent Gravimetric Analyser at pressures from 20 – 50 bar at 25 – 170 °C. Although heavily dependent on sample pre-treatment, the novel ACs displayed considerably higher equilibrium capacities than existing commercial ACs (15% – over 50% at 40 bar), with capacity correlating well with micropore surface area. Adsorption isotherms produced at 170°C indicated that at least two-thirds of the CO2 could be removed by TSA.