Potential for Hydrogen Sulfide Removal Using Ionic Liquid Solvents
The removal of hydrogen sulfide (H2S) via absorptive processes is an important consideration in the oil and gas and electric power industries. The use of ionic liquid (IL)-based solvents in this application is emerging as a new research area. Published data indicate that ILs are capable of absorbing H2S from gas streams, as well as selectively separating H2S from carbon dioxide (CO2). As the solubility of H2S in ILs is highly dependent on the partial pressure of H2S, most ILs should be classified as “physical” solvents and would be best used under conditions where H2S is present at high concentrations and/or high partial pressures. Preliminary results also show that the solubility differences between H2S and other gases can be advantageously employed in membranes, as an alternative to using absorptive processes. Furthermore, ILs can be combined with amines to create “hybrid” solvents that utilize chemical reactions as well as physical solubility to increase the capacity of the solvent for H2S, especially at low concentrations and/or low partial pressures. Hybrid IL-amine solvents can be attained either through formation of “task-specific” ILs with covalently attached amines or through directly mixing ILs with common (e.g., monoethanolamine) and/or specialty amines. This chapter discusses the progress in this field to date as well as the advantages, challenges, and opportunities associated with each approach.
KeywordsIonic Liquid Hydrogen Sulfide Integrate Gasification Combine Cycle Hybrid Solvent Physical Solvent
The author wishes to thank Johnny Johnson and Barry Friedman of URS/Washington Group for their helpful discussions on industrial gas processing.
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