Improved quasi-cycle capacity method based on microcalorimetry strategy for the fast screening of amino acid salt absorbents for CO2 capture

Abstract

Reaction rate and energy consumption are important factors that determine whether the chemical absorbent is suitable for capturing carbon dioxide (CO2). In this work, a high-precision microcalorimetry instead of the traditional estimation method based on the Gibbs-Helmholtz equation was used to directly measure the CO2 absorption heat of six amino acid salt absorbents (potassium taurinate (PT), potassium sarcosinate (PS), potassium L-Prolinate (PL-P), potassium β-Alaninate (Pβ-A), potassium L-Threonine (PL-T), and potassium glycinate (PG)) and the sensible heat of their solutions. In addition, the absorption rate, desorption rate, absorption time, desorption time, and CO2 loading of the absorbents were studied and were integrated into a parameter called the CO2 quasi-cycle capacity to evaluate the reaction rate. Based on thermodynamic data and CO2 quasi-cycle capacity, the absorbent screening method was improved in this work, and PS was identified as a promising absorbent by this method. The CO2 quasi-cycle capacity of the PS solution was similar to that of MEA. In addition, PS solution has the lowest CO2 absorption heat (-75.79 kJ/mol CO2) and the lowest sensible heat which were 14.1% and 23.2% lower than those of MEA solution.