Mesoporous silica impregnated with organoamines for post†combustion CO2 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 CO2 sorption kinetics and capacity at different temperatures, sorbent regeneration, and cyclic sorption†desorption performance, to study the effect of introduced amine types on the CO2 capture performance. In the studied temperature range of 35–95°C for CO2 sorption, samples with different amine types perform differently in CO2 sorption kinetics and capacity. The largest CO2 capture capacity for different solid amine samples appears at different temperatures, and there is evident difference on CO2 capture capacity of different samples. In particular, PEI(25000)/silica gel showed the lowest CO2 capture capacity among all samples. Compared to PEI/silica gel samples, TEPA/silica gel showed a relatively higher CO2 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 CO2 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 CO2 sorption†desorption performance under identical conditions. The cyclic CO2 sorption†desorption performance can be improved by decreasing the desorption temperature to 75°C that leads to slightly loss of CO2 uptake in the second run. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.