Heating load depreciation in the solvent-regeneration step of absorption-based acid gas removal using an ionic liquid with an imidazolium-based cation

Abstract Natural gas is a cleaner energy source compared to other fossil-based energy sources owing to its low emissions. However, natural gas contains acidic gases (including CO 2 and H 2 S), which may cause equipment corrosion and environmental damage. To date, amine-based absorption techniques have been used to remove acidic gases from natural gas to reach regulated concentration limits. However, a tremendous amount of heating is required to regenerate amine-based solvents, which remains a major issue with traditional absorption-based acid gas removal units. In this context, 1-butyl-3-methyimidazolium methyl sulfate (bmim)(CH 3 SO 4 ) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmim)(PF 6 ) were adopted as potential solvents for reducing the heating requirements in the solvent-regeneration step of absorption-based removal techniques. This study shows that by using the imidazolium-based cationic IL, up to 99 wt% of acid gases can be removed while dramatically reducing the heating load and the total annualized cost compared to conventional amine-based absorption units. Flash-based solvent regeneration was used to recover the solvent with a heating loading value of 3978 kW, which is 78.6% lower than that of conventional amine regeneration strippers. Use of only flash column instead of stripper also makes the proposed ionic liquid-based absorption technique most economical with respect to capital investment.