Amino Acid Salts for Carbon Dioxide Capture: Evaluating l-Prolinate at Desorber Conditions

Abstract

Vapor–liquid equilibrium (VLE) measurements for unloaded and CO2-saturated aqueous potassium salt solutions of l-proline have been performed using a high-pressure equilibrium cell. The solubility of CO2 has been determined at temperatures of 363, 393, and 403 K in 3 and 4 mol dm–3 aqueous solutions. The CO2 partial pressures ranged from 3.0 to 358 kPa. In addition, the VLE data for CO2-free and CO2-saturated 3 mol dm–3 aqueous potassium sarcosinate solutions are presented for the same range of temperatures. The vapor pressures of the considered compounds have been determined at temperatures from 353 to 403 K. The reboiler duty required for stripping CO2 from potassium l-prolinate solutions has been computed by the summation of the desorption enthalpy of CO2, sensible heat, and evaporation heat associated with co-produced regenerator overhead water vapor. A new approach to calculate the latter contribution is presented. The calculated energy requirements for l-prolinate are in the range reported in the literature for other amino acid salts.