Kinetics and Steric Hindrance Effects of Carbon Dioxide Absorption into Aqueous Potassium Alaninate Solutions

Kinetic studies of carbon dioxide absorption into aqueous potassium alaninate (PA) solutions were performed using a stirred-cell reactor at concentrations ranging from 1.0 to 3.0 M and temperatures from 293.15 to 313.15 K. In the present work, the potassium salt of alanine was suggested as an energy-efficient absorbent for CO 2 capture. Densities and viscosities of the aqueous PA solution and physical solubilities of CO 2 in the solution were also measured to evaluate the reaction rate constant. The reaction rate was determined as the following equation: (− r CO 2: rate of reaction between absorbent and CO 2 gas [mol dm –3 s –1 ]; T: temperature [K]; C s: concentration of PA solution [mol dm –3 ]; C CO 2: concentration of CO 2 in PA solution [mol dm –3 ]). Furthermore, the effect of the sterically hindered structure of PA was studied by comparing the diffusivity, physical solubility, and reaction rate constant with literature values of potassium glycinate.