Diethanolamine impregnated palm shell activated carbon for CO2 adsorption at elevated temperatures

The CO2 adsorption characteristics of palm shell activated carbon (AC) impregnated with monoethanolamine (MEA) and with diethanolamine (DEA) were compared. The impregnation of the AC with 3% MEA and 3% DEA yielded loadings of 2.46 mol MEA/kg AC and 1.33 mol DEA/kg AC, respectively. The impregnation with MEA and DEA caused reductions of micropore surface areas by 52% and 11%, respectively. The saturation adsorption capacities of the AC-DEA were found to be above those of the AC-MEA at 40-70 degrees C. A maximum CO2 adsorption capacity of 5.3 mol/kg was obtained for the AC-DEA at 400 kPa and 70 degrees C. Under atmospheric pressure, the breakthrough capacities of the AC-MEA samples were lower than those of the AC-DEA samples at all temperatures investigated. The saturation capacities of the AC-MEA were also lower than for the AC-DEA by approximately the same percentages as for the breakthrough capacities. At the regeneration temperature of 160 degrees C, the regeneration times for the AC-MEA were found to be at least 20 min longer than the times for the AC-DEA. This difference was possibly due to higher intraparticle mass transfer resistance in the AC-MEA than in the AC-DEA. Based on both adsorption and desorption characteristics, DEA was suggested to be a more suitable impregnating agent for palm shell activated carbon. (C) 2015 Elsevier Ltd. All rights reserved.