Speciation in CO2-loaded Aqueous Solutions of Sixteen Triacetoneamine-derivates (EvAs) and Elucidation of Structure-property Relationships

Abstract

The speciation in CO2-loaded aqueous solutions of 16 different derivates of triacetoneamine (EvAs) was investigated in a comprehensive NMR-spectroscopic study. About 350 experiments were carried out for CO2-loadings up to 3 moles CO2 per mole amine, temperatures between 20 °C and 100 °C, and a mass fraction of EvA in the unloaded solvent of 0.1 g/g. The observed CO2-containing species were primary and secondary carbamates, alkylcarbonate, (bi)carbonate, and molecular CO2. Some EvAs can form zwitterions with a ring structure, which have an important influence on the speciation. From the comprehensive set of data, relationships between the chemical structure of the EvAs and the observed speciation in aqueous solution were established. These results were related to application properties of the EvAs that were taken from previous work. Based on the findings, some general guidelines for the design of new amines were derived and applied for proposing new amines for CO2-absorption.