Carbon Dioxide Capture by Amine-Impregnated Mesocellular-Foam-Containing Template

Abstract

By impregnating polyethylenimine (PEI) into silica mesocellular foam with the template remaining (MCF­(a)), a novel sorbent with both high CO₂ adsorption capacity and high thermal stability was obtained. The remaining P123 template in the MCF played a great role in promoting the CO₂ adsorption capacity, which could be 4.5 mmol·g^–1 (adsorbent) when the amount of amine loading and the adsorption temperature were optimized as 60% and at 70 °C for the sample MCF­(a)/PEI. Meanwhile, MCF­(a)/PEI had a high thermal stability and selectivity, after 10 adsorption–desorption cycles, MCF­(a)/PEI almost held a constant adsorption capacity; for different compositions of CO₂ and N₂ mixed gases, it always kept a high adsorption selectivity of CO₂/N₂. The mechanism of the template synergistic effect was elucidated by the result of a second-order rate law through CO₂ adsorption kinetic studies. Moreover, as predicted by the Langmuir adsorption model with <i>n</i> = 2 (two active adsorption sites for one CO₂ molecule), the adsorption enthalpy was calculated as about −85 kJ·mol^–1, a value which belonged to typical chemical adsorption