(244d) CO2 Absorption in an Aqueous Amine with a Physical Co-Solvent: Electrolyte NRTL and Rate-Based Process Model and Pilot Plant Experimental Validation.

Absorption with aqueous amines is the most mature industrial technology to remove CO₂ from a gas. The major drawback of the technology is the high energy required to regenerate the solvent. To lower the energy required to warm up the solvent during the regeneration it has been proposed to add a significant amount of a physical co-solvent, to lower the solvent specific heat. There is, however, no clear experimental and model-based evaluation of the overall process of CO₂ removal with a mixed aqueous amine and physical co-solvent. This is important to assess the overall impact of the physical co-solvent on the CO₂ absorption and desorption properties as well as on the operation.

In this work we present the results of a rate-based AspenPlus process model for the CO₂ capture using aqueous mixtures of N-methyl diethanolamine (MDEA) and a common physical co-solvent. We performed new Liquid-Vapor Equilibrium as well as new kinetic experiments and used the data to develop a new thermodynamic electrolyte e-NRTL model, as well as a new kinetic model, which have subsequently been implemented in the overall AspenPlus process model. In parallel we performed experiments on CO₂ removal with the aqueous MDEA-co-solvent on our absorption-regeneration pilot in Lacq, to validate the results of the process simulations. The results of this work will be presented and the overall impact of adding a significant amount of physical co-solvent will be discussed.