Performance of immobilized tertiary amine solid sorbents for the capture of carbon dioxide

The capture of carbon dioxide (CO2) from a simulated flue gas stream was achieved by utilizing immobilized tertiary amine solid sorbents. The tertiary amine immobilized in these solid substrates was 1, 8 Diazabicyclo-[5.4.0]-undec-7-ene (DBU) and it has the stoichiometric capability of capturing carbon dioxide at a 1:1 R-NH2:CO2 molar ratio. This is a unique feature compared to other primary and secondary amines which capture CO2 at a 2:1 molar ratio, thus making the immobilized DBU solid sorbents competitive with existing commercially available sorbents and liquid amine-based capture systems. The immobilized DBU solid sorbents prepared in this study exhibit acceptable CO2 capture capacities of 3.0 mol CO2/kg sorbent at 298 K; however, at the critical operational temperature of 338 K, the capacity was reduced to 2.3 mol/kg sorbent. The DBU sorbents did exhibit acceptable stability over the adsorption/desorption temperature range of 298–360 K based on XPS and TGA analyses.