US EPA

7427875 

Journal Article 

CO2 capture performance and mechanism of blended amine solvents regulated by N-methylcyclohexyamine 

Wang, R; Liu, S; Li, Q; Zhang, S; Wang, L; An, S 

2021 

Yes 

Energy
ISSN: 0360-5442 

Elsevier Ltd 

215 

English 

10.1016/j.energy.2020.119209 

WOS:000598388400003 

Blended amine solvents are considered potential alternatives to monoethanolamine for CO2 capture, for the fast absorption kinetics of primary/secondary amine and low regeneration penalty of tertiary amine. In this research, blended amine solvents comprising N,N-dimethylcyclohexylamine (DMCA) and N-methylcyclohexyamine (MCA) were proposed. CO2 absorption increased the polarity of the products and ensured the absorbent remained homogenous throughout the absorption/desorption cycles. Through quantum chemical calculation, the low stability of MCA-carbamate was confirmed by a ΔΔG3 value of −6.41 kcal/mol, and a possible reaction route from carbamate to bicarbonate was revealed. Thus, the CO2 capacity of DMCA-MCA reached 0.875–0.985 mol CO2/mol amine. Moreover, MCA exhibited considerably low forward energy barrier for zwitterion formation (2.7 kcal/mol), and the CO2 absorption of DMCA could be accelerated through the proton transfer reaction with the MCA-zwitterion. Accordingly, the total mass transfer coefficient of CO2 in DMCA-MCA approached 2.02 × 10−10 mol/cm2 s Pa, which was 1.2-fold higher than that of 5 M MEA. The total regeneration energy of DMCA-MCA blend was estimated at 2.20 GJ/t CO2, which was 44.9% lower than 5 M MEA. This study developed a novel DMCA-MCA blended solvent with rapid absorption rate, huge CO2 capacity and efficient regeneration for CO2 capture. © 2020 Elsevier Ltd 

Absorption rate; Blended amines; CO2 capture; Hybrid amines; Regeneration heat; Amines; Blending; Chemical stability; Ethanolamines; Mass transfer; Proton transfer; Quantum chemistry; Solvents; Absorption kinetics; Absorption rates; Absorption/desorption; Monoethanolamine; Proton transfer reactions; Quantum chemical calculations; Regeneration energy; Zwitterion formation; Carbon dioxide; absorption; bicarbonate; carbamate (ester); carbon dioxide; chemical reaction; detection method; mass transfer; performance assessment; solvent