Thermodynamic and Kinetic Modeling of Piperazine/2-Methylpiperazine

The equimolal CO2 solvent, 4 m 2-methylpiperazine (2MPZ)/4 m piperazine (PZ), was modeled in Aspen Plus® using the eNRTL thermodynamic framework. Data were regressed using binary interaction parameters. The sequential regression method was used starting from prior PZ and 2MPZ models. The model correctly predicts the CO2 equilibrium partial pressure from 40–160 °C. The average differential heat of absorption is close to the expected value of –70 kJ/mol CO2. Newly reported data show that previous data overpredicted viscosity. Activity-based kinetics were used with pairs of power-law reactions representing the forward and reverse reactions. Fluxes measured in a WWC for lean to rich loading and for 40–100 °C were matched, yielding a SSE of 2.39. The kinetic model used ten different reactions along with the diffusivity of amine-products to capture the rate behavior. This model can be used for techno-economic assessments, pilot plant data reconciliation, and process modeling.