Investigation of interaction binary parameters for solubilities of the natural gas components in ionic liquids with EoS for predicting phase behavior

Abstract

This paper describes multicomponent solubilities in ionic liquids using non-associative and associative equations of state (EoS). The parameterization routine was developed from liquid density and speed of sound data as an implementation procedure confirmed with the Aspen Plus simulator, which was used to evaluate the EoS’ phase equilibrium predictive performance. The [EMIM][BF₄] and [BMIM][NTf₂] ionic liquids were employed in this work. PC-SAFT with the 4 C associative scheme showed the best results in fitting the density and speed of sound curves. The deviation for [EMIM][BF₄] was 0.12 % and 0.02 %, respectively, while for [BMIM][NTf₂] was 0.05 % and 0.57 %, respectively. Regarding vapor-liquid equilibria, the CPA and PC-SAFT models presented the best predictive results, while PC-SAFT (4 C) presented, in general, a better fit for the binaries studied. The binary interaction parameter $\left(k_{\mathrm{ij}}\right)$ is near zero using PC-SAFT for C₄₊. So, we recommend using PC-SAFT with $k_{\mathrm{ij}}$=0 between ionic liquids and C₅₊ or heavier hydrocarbons.