Development of a Validated Rate-Based Model for CO₂ Absorption in Aqueous 2‑Amino-2-methyl-1-propanol and Piperazine...

Area of Science:

• Chemical Engineering
• Thermodynamics
• Carbon Capture Technologies

Background:

• Carbon dioxide (CO2) absorption using amine solutions is a key technology for post-combustion carbon capture.
• Aqueous mixtures of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) are promising absorbents due to their favorable properties.
• Accurate thermodynamic models are essential for optimizing the design and operation of CO2 capture processes.

Purpose of the Study:

• To develop and validate a new e-NRTL thermodynamic framework for modeling CO2 absorption in aqueous AMP/PZ mixtures.
• To accurately predict CO2 solubility, total pressure, heat of absorption, and free CO2 concentration.
• To assess the model's performance across a wide range of operating conditions and amine concentrations.

Main Methods:

• Development of an e-NRTL thermodynamic framework in Aspen Plus for the CO2-AMP-PZ-H2O system.
• Fitting the model parameters using experimental data for varying AMP and PZ concentrations, temperatures, and CO2 loadings.
• Validation of the model with pilot-scale campaign data, incorporating mass transfer and kinetics.

Main Results:

• The e-NRTL model achieved an Absolute Average Relative Deviation (AARD) of 26.3% for CO2 solubility and 7.0% for total pressure.
• The model accurately predicted the heat of absorption (AARD 10.2%) and free CO2 concentration (AARD 13.1%).
• Rate-based model predictions for CO2 capture, rich loading, and reboiler duty were within 5% AARD of pilot campaign data.

Conclusions:

• The developed e-NRTL thermodynamic framework provides a robust and accurate representation of CO2 absorption in aqueous AMP/PZ solutions.
• The model demonstrates good predictive capability for key process variables relevant to industrial CO2 capture applications.
• The validated model, coupled with mass transfer and kinetics, is suitable for designing and optimizing large-scale carbon capture facilities.