(101b) Thermodynamic Modeling of CO2 Absorption in K2CO3-H2o Solution with Association Enrtl Model

An environmentally benign absorbent, K₂CO₃-H₂O solution is a common chemical absorbent for CO₂ capture due to its low cost. Recently, the industry is gaining interest in developing high-temperature and high-concentration K₂CO₃-based CO₂ absorption processes to reduce energy requirement associated with CO₂ stripping and compression processes. Previous thermodynamic modeling research has not investigated enthalpy of CO₂ absorption and vapor-liquid equilibrium, especially water vapor pressure, at high temperatures. This study expands the prior thermodynamic modeling of the K₂CO₃-H₂O-CO₂ ternary system and its associated binary systems with a temperature range of 273.15 – 473.15 K and the K₂CO₃ concentration up to saturation with the association electrolyte nonrandom two-liquid (association eNRTL) model (Y.-J. Lin, C.-J. Hsieh, and C.-C. Chen, AIChE Journal, 68 (2022) e17422). The association eNRTL model is well suited for thermodynamic modeling of electrolyte solutions with high charge density ions with strong association tendency including the carbonate ions. Accounting for both self- and cross-association of water and carbonate ions, the association model provides an improved representation of the K₂CO₃-H₂O-CO₂ ternary system compared to the original eNRTL model.