Thermodynamic modelling of carbon dioxide solubility in aqueous amino acid salt solutions and their blends with alkanolamines

Enrichment in CO2 Absorption by 2-Methyl Piperazine-Activated Tertiary Amines, Physical Solvents, and Ionic Liquid Systems

One of the ever-demanding research fields is the development of new solvents with better properties for mitigation of CO₂ compared to existing solvents. This work reports the measurement and modeling of CO₂ solubility in newly proposed aqueous solvent blends of 2-methyl piperazine with N-methyldiethanolamine (MDEA), sulfolane (TMSO₂), and 1-butyl-3-methyl-imidazolium acetate ([bmim] [Ac]). The operating temperature and CO₂ partial pressure conditions chosen were 303.2-323.2 K and 2-370 kPa, respectively. Along with this, qualitative ¹³C NMR and FTIR analysis were also performed to consider the proposed reaction scheme. The experimental vapor-liquid equilibrium data were modeled by a modified Kent-Eisenberg equilibrium model. The equilibrium constants associated with 2-methyl piperazine (2-MPZ) and [bmim] [Ac] deprotonation and carbamate formation reactions were regressed to fit the experimental CO₂ solubility data. In addition, the CO₂ cyclic capacity and heat of absorption were evaluated for the aq (MDEA + 2-MPZ) blend.

State-of-the-art of CO2 capture with amino acid salt solutions

The emission of large amounts of CO2 into the atmosphere is believed to be a major reason behind climate change, which has led to increased demand for CO2 capture. Postcombustion CO2 capture with chemical solvent is considered one of the most important technologies in order to reduce CO2 emission. Amino acid salt solutions have attracted special attention in recent years due to their excellent physicochemical properties, e.g., low volatility, less toxicity, and high oxidative stability, as well as capture performance comparable with conventional amines. In this study, physicochemical properties of 20 amino acids are reported and their CO2 absorption performance discussed. The topics covered in this review include the most relevant properties of amino acids including CO2 loading capacity, cyclic capacity, equilibrium constant, density, viscosity, dissociation constant, CO2 solubility, CO2 diffusivity, reaction kinetic between CO2 and amino acid salts, reaction rate constant, surface tension, heat of CO2 absorption, precipitation, toxicity, solvent degradation, and corrosion rate. This review provides the most recent information available in the literature on the potential of using amino acid salts as a solvent for CO2 capture which can help improve the performance of the CO2 capture process from flue gas streams.