Degradation of amine-supported CO2 adsorbents in the presence of oxygen-containing gases

Three samples containing grafted primary, secondary and tertiary monoamines (pMono, sMono and tMono) as well as a triamine-grafted material (TRI) with both primary and secondary amines were exposed to flowing air at 120 degrees C for 30-40h. It was found that pMono and tMono were stable as evidenced by CO2 adsorption measurements as well as infrared and NMR data, whereas sMono and TRI adsorbents exhibited extensive deactivation. Infrared data showed the development of an absorption band at 1665-1680 cm(-1) whose intensity increased with the degree of oxidative degradation. However, only minor changes occurred in the corresponding C-13 CP/MAS NMR spectra. The findings were discussed, and a tentative explanation was provided. (C) 2011 Elsevier Inc. All rights reserved.