Kinetics of carbon dioxide absorption in aqueous blend of 1-(2-aminoethyl) piperazine using a stirred cell reactor

Abstract

Carbon capture utilization and storage (CCUS), the technology for decarbonizing carbon dioxide (CO₂) from greenhouse gas emitters such as steel, cement, oil, gas, petrochemicals, chemicals, and fertilizers, has a critical role to play in the world to achieve industrial net zero targets by 2050. CO₂ can be separated from industrial exhaust gases/flue gases using amine-based solvents utilizing the post-combustion CO₂ Capture process. One most crucial solvent characterization for this application is the kinetics of CO₂ absorption. This work identifies aqueous 1-(2-aminoethyl) piperazine (AEPZ) as a potential candidate for CO₂ capture solvent. The kinetics of absorption of CO₂ in aqueous AEPZ is studied using stirred cell reactor. The experiments are performed at temperatures ranging from 303 to 333 K with weight fractions of AEPZ in an aqueous solution ranging from 0.1 to 0.4. One of the critical parameters of the kinetic study is Henry’s constant which is determined experimentally using another stirred cell reactor at a similar temperature and pressure range. The experimental data shows that the overall rate constant is K_ov = 2.52987 × 10⁻⁴ mol/m²s-kPa for 0.1 wt fr. of AEPZ at 313 K with an initial CO₂ partial pressure of 10 kPa. The temperature dependency relation of the second-order reaction rate constant, ${k}_{2},$ is found to be $6.126\times {10}^{11} exp\left(-5102/T\right)$ using the Arrhenius equation. The activation energy of 0.3 wt fr. AEPZ is found to be 42.42 kJ/mol. In addition, the density and viscosity of the aqueous solvent are determined at a wide range of temperatures. The diffusivity of CO₂ and physical solubility used in the model development has also been determined. The kinetic parameters obtained from this study are helpful in the process design of CO₂ capture in a regenerative process with a blended solvent with AEPZ.