Oxidative stability of structurally varied amines for post-combustion CO2 capture

Amine degradation is one of the key issues that hampers the implementation of amine-based post combustion carbon capture technology. In this work, the oxidative degradation of fourteen structurally varied amines were experimentally studied by measuring the amine loss, alkalinity change, ammonia yield, and degradation product. There is a linear relationship between amine loss against alkalinity change and ammonia yield, indicating that the degradation product either loss reactivity for CO2 absorption or emit out as the small molecule. The results have shown that amine stability generally increased with amine order and stronger steric hindrance effect. Most primary and secondary amines showed more than 40 % amine loss after 336 h degradation experiment, while most of tertiary amines showed less than 10 % amine loss. This may be due to the exposed amine groups of primary and secondary amines. The oxidative degradation mechanism was studied based on density functional theory (DFT) calculations.