Crystallization kinetics and the role of equilibrium in carbon capture systems with gas-liquid-solid equilibrium: Case study of AMP in NMP solution

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Abstract

A semi-empirical power law-based theory has been developed to model the crystallization kinetics in precipitating systems for CO2 capture. A more reliable activity-based theory and simplified concentration-based crystallization kinetics have also been derived for a gas-liquid-solid system in which CO2 evolution might be unavoidable during the experiments performed to determine crystallization kinetics. The power law is based on the concept of the metastable zone. Changes in the metastable zone width are therefore discussed when complex chemistry is involved (as in the case of CO2 capture). 2-Amino-2-methyl-1-propanol (AMP) in the organic solvent N-methyl pyrrolidinone (NMP) was used as a case study, and the kinetics for the precipitation of the salt resulting from the capture of CO2 were determined using the developed theory. The theory required thermodynamic property modeling of the AMP-NMP-CO2 system, which was accomplished using equilibrium solubility experiments with equilibrium times of at least 330 min. The model was developed in Aspen Plus using the ENRTL-RK property model. The meta-stable zone width varied with varying loading. The logarithm of the activity-based supersaturation ratio should be considered a more reliable measure of supersaturation. It was also found that concentration-based relative supersaturation was a good approximation of the supersaturation ratio for the case of AMP in NMP. However, approximating the supersaturation ratio with the concentration difference was found to be too error-prone.

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Subject classification (UKÄ) – MANDATORY

  • Theoretical Chemistry

Keywords

  • CCS, Crystallization kinetics, Gas-liquid-solid, Precipitating
Original languageEnglish
Article number112505
JournalFluid Phase Equilibria
Volume511
Publication statusPublished - 2020
Publication categoryResearch
Peer-reviewedYes