Performance of the Water‐Lean Mixture of 2‐Amino‐2‐Methyl‐1,3‐Propanediol, Ethylene Glycol, and Propanol in CO ₂ Separation From Simulated Biogas

ABSTRACT AMPD (2‐Amino‐2‐methyl‐1,3‐propanediol) is a candidate hindered amine for CO 2 separation from biogas. In this study, the performance of water‐lean mixtures of AMPD with the organic solvents ethylene glycol (EG) and propanol (PrOH) was explored. Hindered amines load more CO 2 , while organic solvents desorb CO 2 at low temperature. As a result, the proposed mixtures will be useful for improved CO 2 removal from biogas. Thus, CO 2 solubility in the blends AMPD/H 2 O (AMPD = 1 M) and AMPD/EG/PrOH/H 2 O (AMPD = 1 M, EG:PrOH = 1:1, H 2 O = 15 wt.%) was measured at 303, 313, and 323 K. The equilibrium CO 2 partial pressure varied in the 0.05–240 kPa range. Upon replacing water with the chosen organic solvents, the rate of CO 2 desorption in AMPD doubled, and low‐temperature regeneration ( T = 363 K) was possible. Besides, the heat of CO 2 absorption was lowered too, as evident from the Gibbs–Helmholtz equation. Since these outcomes were encouraging, absorption kinetics were also studied in the fast pseudo‐first order reaction regime using the stirred cell technique and rate constants at 308 K were reported. Such water‐lean mixtures were hitherto scarcely studied, and we filled this gap in this work.