The Thiocyanate Anion is a Primary Driver of Carbon Dioxide Capture by Ionic Liquids

TL;DR

This study uses PM7-MD simulations to demonstrate that the thiocyanate anion significantly enhances CO2 capture in ionic liquids, with the anion's orbital interactions playing a crucial role.

Contribution

It reveals the primary role of the thiocyanate anion in CO2 adsorption, highlighting orbital interactions beyond electrostatics, which advances understanding of ionic liquid-based gas capture.

Findings

Thiocyanate anion is key in CO2 capture.

CO2 interacts with the anion through orbital sharing.

Cation impact on CO2 capture is minimal.

Abstract

Carbon dioxide, CO2, capture by room-temperature ionic liquids (RTILs) is a vivid research area featuring both accomplishments and frustrations. This work employs the PM7-MD method to simulate adsorption of CO2 by 1,3-dimethylimidazolium thiocyanate at 300 K. The obtained result evidences that the thiocyanate anion plays a key role in gas capture, whereas the impact of the 1,3-dimethylimidazolium cation is mediocre. Decomposition of the computed wave function on the individual molecular orbitals confirms that CO2-SCN binding extends beyond just expected electrostatic interactions in the ion-molecular system and involves partial sharing of valence orbitals.