Efficient Selective CO₂ Composite Sorbent from Amino Acid Ionic Liquids and Silica Gel: ²H NMR Spectroscopy Provides Insight on the CO₂‐Binding Mechanism and in‐Pore Microscopic Viscosity

Abstract

A promising CO2 sorbent based on the [Emim][Gly]/silica gel composite has been studied. Absorption experiments have shown that the optimum loading of [Emim][Gly] ionic liquid in silica gel is 40 wt%. The 2‐step process CO2 binding mechanism in [Emim][Gly] has been proposed based on the results of absorption experiments, 2H NMR spectroscopy and ab‐initio calculations. The impact of CO2 on the microscopic viscosity and the dynamical melting of ionic liquid has been thoroughly investigated. 2H NMR spectroscopy has revealed that CO2 strongly binds cation and anion in [Emim][Gly], forcing them to move in a correlated fashion.