Reversible Reaction of CO2 with Superbasic Ionic Liquid [P66614][benzim] Studied with in Situ Photoelectron Spectroscopy

Ionic liquids (ILs) are of significant interest as CO2 capture agents,
and one subgroup of ILs that has shown particular promise is that of superbasic
ILs. They can absorb large quantities of CO2 in the dry state, but some will have a
diminished CO2 capacity when prewetted. In the work presented here, the
superbasic IL trihexyl-tetradecylphosphonium benzimidazolide, or [P66614]-
[benzim], was exposed to 3 mbar of CO2, 2 mbar of H2O vapor, and a CO2 +
H2O gas mixture and was investigated using near-ambient pressure X-ray
photoelectron spectroscopy. The results show that the IL reacts with CO2 to
form carbamate and that the reaction is reversible through reduction of the
surrounding gas pressure. Regardless of whether the IL was exposed to CO2 or H2O vapor first, the presence of H2O under
these experimental conditions does not significantly hinder th