CO2 adsorption by PAMAM dendrimers: Significant effect of impregnation into SBA-15

Adsorption capacities for dry CO2 were determined for neat polyamidoamine (PAMAM) dendrimers (generation G0.0, 1.0, 2.0 and 3.0), mesoporous SBA-15 and impregnated adsorbents (50% by weight) consisting of SBA-15 as substrate and PAMAM dendrimer (G0.0, 1.0, 2.0 and 3.0) at 20, 75 and 105 °C. Neat PAMAM dendrimers adsorbed CO2 very poorly. However, impregnation by these materials into SBA-15 improved their CO2 adsorption capacity significantly, especially at 75 and 105 °C. Impregnation seems to break down internal H-bonding and allow the amine groups within the dendrimer to interact with CO2. Elevated temperature improves CO2 diffusion within the impregnated adsorbents, presumably due to improved mobility of the dendrimers, such that cyclic adsorption/desorption behaviour would be realised on a reasonable (10 min) time scale.