CO₂ Capture from Natural Gas with Ionic Liquid

Abstract

Carbon dioxide capture is a global concern because of its effect on climate change, especially as regards to global warming. Absorption using physical and chemical solvents is the commonly used method to capture CO₂. Ionic liquids (ILs) as advanced solvents have been regarded as appropriate candidates for CO₂ capture because of their advantages such as non-volatility potentially that makes ILs “green” solvents, negligible vapor pressure and high CO₂ solubility.

This work aimed to study the feasibility of CO₂ separation from a gas containing methane using the low viscosity ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate [hmim][TCB] as an alternative to conventional ones by simulation using Aspen plus V.8.0. Thermophysical properties were calculated using empirical correlations, and the experimental data for CO₂/CH₄ in presence of [hmim][TCB] were fitted with the NRTL activity coefficient model to determine the binary interaction parameters. The results show that lower solvent flow rate and lower energy consumption are required for the absorption with [hmim][TCB] than with organic solvents, especially for gas streams with moderate acid gas content.