Efficient, stable, oxidation resistant and cost effective epoxide modified polyamine adsorbents for CO2 capture from various sources including air.

Carbon dioxide adsorbents based on the reaction of pentaethylenehaxamine (PEHA) or tetraethylenepentamine (TEPA) with propylene oxide (PO) were easily prepared in "one pot" by impregnation on a silica support in water. The starting materials are readily available and have a low cost facilitating the production of the adsorbents on a large scale. The prepared polyamine/epoxide adsorbents were efficient in capturing CO2 and regenerable under mild conditions (50-85 °C). They displayed a much improved stability compared to their unmodified amine counterparts, especially under oxidative conditions. Leaching of the active organic amine became minimal or non-existent after treatment with the epoxide. The adsorption as well as desorption kinetics were also greatly improved. The polyamine/epoxide adsorbents were able to capture CO2 from various sources including ambient air and indoor air with CO2 concentrations of only 400 to 1000 ppm. The presence of water, far from being detrimental, increased the adsorption capacity. Their use for indoor air quality purposes is explored.