CO2 capture and sorbent regeneration performances of some wood ash materials

Wood ash, which is recognized as an environmental pollutant, is tried as a new material for CO2 capture in this work. Five wood ash samples obtained from different raw materials were chosen, and an experimental demonstration of the CO2 capture performances of these wood ash samples was present in detail in a modified fixed bed reactor system. The CO2 capture and the sorbent regeneration performances of wood ash were investigated under different conditions by changing the temperature, H2O concentration, gas flow rate and the heating rate. The CO2 capture capacities are in the range of 0.35–0.54mmol CO2/g for different wood ash samples under the condition of 60°C, 10% CO2+12% H2O. The CO2 capture processes contain two parts for these samples. One is the physical adsorption process, and another is the chemical reaction of K2CO3 with CO2 and H2O to form KHCO3, K2CO3·1.5H2O and K4H2(CO3)3·1.5H2O. The desired wood ash is proved to be regenerable and stable during 10-cycle CO2 sorption–desorption tests. The deactivation model and the Avrami–Erofeyev model are adopted to evaluate the CO2 sorption and desorption kinetics of this sample respectively. Considering the low cost, and the recycling of environmental pollutants, wood ash is a nice choice for CO2 capture.