The use of ionic liquids and polymeric solvents as gas capture media

Abstract

This thesis is written in two parts. Section one contains a survey of the chemistry of Salen (Salen = bis(salicylaldehyde) ethylenediimine) cobalt complexes as molecules and materials with tunable capacities for reversible oxygen binding. These complexes were explored in low-volatility solvents as inexpensive and reusable oxygen-trapping mechanisms. Three of the complexes were synthesized and dissolved in an ionic liquid, but degraded upon exposure to oxygen.

The second section describes a study on the thermal stability of common ionic liquids and polymeric solvents, which demonstrates that these solvents are incompatible for oxygen capture. Therefore, the trapping of the acidic gas, carbon dioxide was investigated instead of oxygen. A survey of carbon dioxide capture was performed in phosphonium-based ionic liquids and end-capped polyethylene glycol using DETA (DETA = diethylenetriamine) as a model absorbent. The carbon dioxide adduct of DETA formed readily in both ionic and polymeric media, and decomposed with heating. Crystals of the adduct were isolated and its X-ray crystal structure reported.