Design and Evaluation of Ionic Liquids as Novel Absorbents
Project # 42122

Primary Performing Organization:
University of Notre Dame

	Fig. 1: Measured Henry's Law constants for carbon dioxide, oxygen, ethylene, and ethane in various ionic liquids. A small Henry's Law constant indicates high solubility.

The potential of this project as a more economical means of carbon dioxide (CO₂) capture depends upon the efficient use of ionic liquids as CO₂ absorbents in natural gas- or coal-fueled power plants.  This design would reduce costs through higher CO₂ loading in the circulating liquid and lower heat requirements for regeneration, compared to existing amine-based technologies.

The feasibility of ionic liquid technology will first be tested by increasing the knowledge base for the chemical characteristics of ionic liquids.  Success of this technology also will hinge on the competitiveness of ionic liquids-based absorbents for CO₂ capture from flue gas streams, when compared to amine-based technologies now in use.  Consequently, a successful ionic liquid absorbent must have high CO₂ selectivity and capacity, coupled with a
low energy requirement for regeneration.

A number of ionic liquids have been synthesized or acquired, and CO₂ solubility has been measured for some of these compounds.  By measuring the solubility of other gases in these liquids, it was found that CO₂ is significantly more soluble in these ionic liquids than in any of these other gases.  See Fig 1.

The analytical objectives of this project are to:

• Produce a range of ionic liquid sorbents for further evaluation.
• Determine the fundamental factors influencing the absorption of CO₂ and other gases present in flue gas streams.
• Determine relevant thermo-physical and phase behavior properties.
• Develop a preliminary process design that uses ionic liquids in an absorption separation system.

Contact:
Project Manager: Jose D. Figueroa, jose.figueroa@netl.doe.gov

Related Papers and Publications:

• Ionic Liquids Fact Sheet [PDF]