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 °C for 30–40 h. 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 13C CP/MAS NMR spectra. The findings were discussed, and a tentative explanation was provided.

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► The effect of air exposure on CO2 adsorption over amine-grafted silicas was investigated using DRIFT and 13C CP/MAS NMR.
► Materials containing primary and tertiary monoamines were found to be highly stable up to ca. 120 °C.
► Materials with secondary monoamine, or mixed amines such as triamine were very sensitive to air-exposure.