Investigation mechanism of DEA as an activator on aqueous MEA solution for postcombustion CO₂ capture

Abstract

In this work, Diethanolamine (DEA) was considered as an activator to enhance the CO 2 capture performance of Monoethanolamine (MEA). The addition of DEA into MEA system was expected to improve disadvantages of MEA on regeneration heat, degradation, and corrosivity. To understand the reaction mechanism of blended MEA‐DEA solvent and CO 2 , 13 C nuclear magnetic resonance (NMR) technique was used to study the ions (MEACOO ‐ , DEACOO – , MEA, DEA, MEAH + , DEAH + , , ) speciation in the blended MEA‐DEA‐CO 2 ‐H 2 O systems with CO 2 loading range from 0 to 0.7 mol CO 2 /mol amine at the temperature of 301 K. The different ratios of MEA and DEA (MEA: DEA = 2.0:0, 1.5:0.5, 1.0:1.0, and 0:2.0) were studied to comprehensively investigate the role of DEA in the system of MEA‐DEA‐CO 2 ‐H 2 O. The results revealed that DEA performs the coordinative role at the low CO 2 loading and the competitive role at high CO 2 loading. Additionally, the mechanism was also proposed to interpret the reaction process of the blended solvent with CO 2 . © 2018 American Institute of Chemical Engineers AIChE J , 64: 2515–2525, 2018