FT-IR study on CO2 adsorbed species of CO2 sorbents

The stability of amine-functionalized silica sorbents prepared through the incipient wetness technique with primary, secondary, and tertiary amino organosilanes was investigated. The prepared sorbents were exposed to different gaseous streams including CO2/N-2, dry CO2/air with varying concentration, and humid CO2/air mixtures to demonstrate the effect of the gas conditions on the CO2 adsorption capacity and the stability of the different amine structures. The primary and secondary amine-functionalized adsorbents exhibited CO2 sorption capacity, while tertiary amine adsorbent hardly adsorbed any CO2. The secondary amine adsorbent showed better stability than the primary amine sorbent in all the gas conditions, especially dry conditions. Deactivation species were evaluated using FT-IR spectra, and the presence of urea was confirmed to be the main deactivation product of the primary amine adsorbent under dry condition. Furthermore, it was found that the CO2 concentration can affect the CO2 sorption capacity as well as the extent of degradation of sorbents.