Study on the improvement of the capacity of amine-impregnated commercial activated carbon beds for CO2 adsorbing

Amine-based chemicals were impregnated onto activated carbon particles to improve its natural adsorption ability and selectivity to adsorb CO2 from gas mixture stream. Characterization results achieved by measuring the surface area with ASAP 2020 showed that the amine-based chemicals blocked the mostly micropore pores of the activated carbon particles. The amine-based chemicals used in this study were, monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). The impregnation process and the subsequent blockage reduced the surface area of the activated carbon particles significantly but on the other hand enhanced the adsorption capacity and selectivity of the activated carbon for CO2 adsorption. Elemental analysis results using energy-dispersive X-ray spectroscopy showed that the impregnation process managed to attach the reactive N2 molecules onto the surface and inside the pores of the activated carbon particles. Images from field emission scanning electron microscope showed that due to impregnation process most of the pores of the activated carbon particles had been blocked by the MEA and AMP molecules. Sweeping exhausted non-impregnated activated carbon beds with 60 ml/min pure nitrogen for 4 h was enough for these beds to regain their original adsorption capacity but in contrast it was not enough to regenerate exhausted AMP, MEA-impregnated activated carbon beds to regain their original adsorption capability.

► Impregnation with MEA and AMP enhanced the adsorbing capacity of activated carbon beds.
► MEA and AMP became part of the activated carbon surface structure after impregnation.
► MEA enhanced adsorbing capacity more than AMP did.
► Total surface area dropped significantly after impregnation with MEA and AMP.