Stability of Structurally Varied Aqueous Amines for CO2 Capture

Abstract

Eighteen structurally varied amines were subjected to harsh oxidative conditions, and their stability was assessed and seen in the context of biological and thermal stability. Steric effects play a large role in the stabilization of amines under oxidative conditions, and the presence of carbon dioxide plays a vital role in the degradation pathway of ethanolamine (MEA). Tertiary amines are generally very stable, and are known not to form carbamates to any large extent. Many steric effects play a vital role in stabilization, such as chain length, substituents located both close to and farther from the nitrogen atom, and bond strain. A correlation is seen between biodegradability and oxidative degradability, giving similar degradability in both cases. There are, however, promising exceptions to this, such as 3-(dimethylamino)-1-propylamine (DMAPA) and 2-dimethylaminoethanol (DMMEA), which are stable under oxidative conditions, but also biodegradable. Direct correlations between oxidative stability and ecotoxicity or thermal stability are not seen.