Mesoporous silica impregnated with organoamines for post‐combustion CO 2 capture: a comparison of introduced amine types

Polyethylenimine (PEI) with different molecular weight such as 275, 800, 1800, and 25000, together with tetraethylenpentamine (TEPA) were impregnated into a mesoporous silica support (silica gel) using a wet impregnation method. These resultant solid amine sorbents with different amine types were compared in terms of CO 2 sorption kinetics and capacity at different temperatures, sorbent regeneration, and cyclic sorption‐desorption performance, to study the effect of introduced amine types on the CO 2 capture performance. In the studied temperature range of 35–95°C for CO 2 sorption, samples with different amine types perform differently in CO 2 sorption kinetics and capacity. The largest CO 2 capture capacity for different solid amine samples appears at different temperatures, and there is evident difference on CO 2 capture capacity of different samples. In particular, PEI(25000)/silica gel showed the lowest CO 2 capture capacity among all samples. Compared to PEI/silica gel samples, TEPA/silica gel showed a relatively higher CO 2 sorption capacity. The regeneration of TEPA/silica gel is more difficult than PEI/silica gel samples, and 100°C was found suitable for complete regeneration of all sorbents. PEI(25000)/silica gel showed good reversibility and stability during 10 cyclic CO 2 sorption‐desorption (sorption at 75°C and desorption at 100°C) tests, whereas PEI(275), PEI(800), PEI(1800), and TEPA/silica gel all suffered to various extents from amine leaching problems in cyclic CO 2 sorption‐desorption performance under identical conditions. The cyclic CO 2 sorption‐desorption performance can be improved by decreasing the desorption temperature to 75°C that leads to slightly loss of CO 2 uptake in the second run. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.