(88c) The Chemical Product Design of Solvents for Post-Combustion CO2 Capture Processes

The solvents used in post-combustion CO₂ capture processes must satisfy several physical, chemical, operational and economic constraints. They must possess a reaction equilibrium with CO₂ that is significantly affected by temperature. They must possess vapor pressures that allow for easy separations. They must possess heat capacities and enthalpies of vaporization that lower the energy requirements for thermal processing.

We used a chemical product design approach to systematically identify promising candidate solvents for the capture of CO₂ from coal fired power plants. Our chemical product design approach consisted of the following five steps:

1. Compiling and developing accurate structure-property relationships for the basic physical properties needed for performance evaluation. These properties include activity coefficients, pKa, heat capacities, vapor pressures and enthalpies of vaporization.
2. Using a series of structure generation and enumeration algorithms to create a database of candidate solvents. These generated molecular structures include both commonly known solvents as well as novel solvent structures.
3. Using the compiled structure-property relationships to estimate the physical properties of each candidate solvent.
4. Quickly evaluating each candidate solvent using a simplified process-independent model.
5. Detailed evaluation using a process simulator.

 We will discuss the details of our approach, the details of the algorithms used and areas in which improvement is needed.