Evaluation of thermophysical data, COSMO‐SAC predictions, and feed simplifications for aromatic extraction process simulation using ionic liquid [EMIM][NTf2]

Abstract

Ionic liquids (ILs) are promising alternatives to conventional solvents for selective separation of aromatics from hydrocarbon mixtures, and their implementations depend on economic feasibility demonstrated by process simulation. Prior process modeling studies typically assume simplified hydrocarbon feeds or use the COSMO‐SAC predictive model. Our goal is to evaluate how feed simplifications and COSMO‐SAC predictions impact process modeling. We collect experimental data for 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]) from the ILThermo database to regress UNIQUAC model binary interaction parameters for 17 hydrocarbons. We find that feed simplifications tend to significantly underpredict process energy requirements and fail to reveal important details in the extractive distillation section of the process. COSMO‐SAC predictions underpredict activity coefficient of aliphatics in [EMIM][NTf2] by a large margin, which leads to lower aromatic‐aliphatic selectivities and overprediction of process energy requirements. It is significant enough to lead to the conclusion of process infeasibility in the case of [EMIM][NTf2].

Science‐guided data analytics for selecting ionic liquid solvents for aromatic extraction

“…We have prior success with this thermodynamic model accurately capturing experimental equilibrium data between hydrocarbons and an IL. We obtain the binary parameters used for [EMIM][NTf2] and sulfolane from our prior process modeling work 1,23 …”

“…We obtain the binary parameters used for [EMIM][NTf2] and sulfolane from our prior process modeling work. 1,23 Binary parameters for the 15 additional ILs included in this study are presented in Data S1. We use experimental data from the ILThermo database to regress binary parameters.…”

Development of energy‐optimum aromatic extraction processes using ionic liquid [EMIM][NTf2]

“…We use Aspen Plus process simulation software for the study and the UNIQUAC thermodynamic model with ideal gas equation of state. We have demonstrated the ability of UNIQUAC binary regression parameters to reflect experimental equilibrium data in our associated work, 27 which we use to obtain all [EMIM][NTf2] binary interaction parameters and pure component properties. We represent [EMIM][NTf2] as a conventional component in Aspen Plus.…”

“…Antione parameters for [EMIM][NTf2] are A = −30, B = 0, and C = 0 to reflect the assumed non‐volatility. We provide details of all property models and their parameter values for [EMIM][NTf2] in our associated work 27 …”

“…We have determined in our associated work 27 that the COSMO‐SAC method is not accurate enough for process modeling application because of large underprediction of aliphatic activity coefficients that lead to incorrect design conclusions. We have also determined that limited component definitions of prior experimentally supported models lead to significantly different operating conditions than fully defined feed compositions 27 . Most of the prior process design studies feature one or more of these issues that may impact the model ability to reflect real process performance 5,6,8,9,11–13,15–19 .…”