Postcombustion Capture of CO2 by Diamines Containing One Primary and One Tertiary Amino Group: Reaction Rate and Mechanism

Developing ideal amine solvents with a high CO2 absorption capacity and a fast absorption rate is an attractive avenue to advance the amine scrubbing technology. In this regard, diamines bearing one primary and one tertiary amino group (1°/3° diamines) are proposed to be promising solvents for CO2 absorption, which can exhibit the fast CO2 absorption rate of primary amines while maintaining the diamines’ intrinsic high absorption capacity. Here, we present a detailed kinetic study of four 1°/3° diamines for CO2 absorption and investigate the relationship between the structure of various 1°/3° diamines and their CO2 absorption rate. Results showed that increasing alkyl spacer between two amino groups within 1°/3° diamines promoted the CO2 absorption rate, while a large decrease in their reactivity with CO2 was observed when the tertiary amino group existed in the cyclic structure. Among these studied 1°/3° diamines, 3-(dimethylamino)-1-propylamine (DMAPA) displayed the highest absorption rate under relevan...