Study of CO₂ removal in natural gas process using mixture of ionic liquid and MEA through process simulation

There has been a shift to less carbon intensive fuels such as natural gas to meet energy demand due to increasing pressure to cut CO₂ emissions. This has prompted a need to assess unconventional and contaminated natural gas reserves (which contains CO₂ concentration of 20 mol% or more). The CO₂ capture process with MEA as the solvent is mostly adopted to treat contaminated natural gas. In this study, the option of using a blend of ionic liquids (IL) and MEA as a promising solvent in the process was investigated through modelling and simulation. A detailed rate-based model was developed for both MEA (30 wt%) solvent and IL (30 wt%)-MEA (30 wt%) blend using Aspen Plus® to assess both process and economic performances. The 1-Butylpyridinium ([bpy][BF₄]) ionic liquid was selected in this study. The physiochemical properties of [bpy][BF₄], predicted using Aspen Plus®, showed good accuracy compared with experimental data. The results from this study showed about 15% and 7.44% lower energy consumption in the reboiler duty and CO₂ removal cost respectively with aqueous [bpy][BF₄]-MEA solvent compared to 30 wt% MEA solvent. It is concluded that the aqueous [bpy][BF₄]-MEA solvent is therefore a promising solvent that could replace 30 wt% MEA solvent in this process.