Mixed Ionic Liquids as Entrainers for Aromatic Extraction Processes: Energy, Economic, and Environmental Evaluations

Abstract

Experimental measurements for the vapor–liquid equilibria (VLE) of benzene + 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([EMIM]­[NTf2]), benzene + 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM]­[EtSO4]), and benzene + mixed ionic liquids (ILs) (equimolar [EMIM]­[NTf2] + [EMIM]­[EtSO4] mixture) are performed. The non-random two liquid (NRTL) model binary interaction parameters are then obtained by fitting the new VLE data and the liquid–liquid equilibrium data previously reported. The interactions between chemical species are analyzed using quantum chemical calculations and the COSMO-SAC method, and it is found that the interactions between benzene and ILs are strongly attractive. Taking as a reference the industrial process that uses sulfolane as the entrainer, several novel industrial processes are proposed, which involve either pure ionic liquids [EMIM]­[NTf2] and [EMIM]­[EtSO4] or their mixtures as the extractant for separating aromatic hydrocarbons (benzene) and paraffins (n-hexane). The optimal operating parameters, such as the number of theoretical stages, the extractant-to-hydrocarbon feed ratio, the reflux ratio, and the feed stage, are determined for the different processes. Steady-state process simulations are performed to evaluate the total annual cost (TAC) and the environmental impact (carbon dioxide emissions). It is shown that significant savings in energy consumption (reduction of 19.6–48.7%), TAC (reduction of 6.3–27.1%), and CO2 emissions (reduction of 17.8–47.6%) can be achieved for the processes that use IL extractants, compared to the process based on sulfolane extractant. The proposed IL extractant and the corresponding process are promising alternatives to conventional solvents and processes for aromatic extraction.

Water–Ionic Liquid Working Fluids in Absorption Cycles: Fluid Screening, Vapor–Liquid Equilibrium Measurements and Modeling, and Performance Evaluation

“…The experimental VLE data were determined through the static isothermal method described in our previous work. 34 The 1.…”

“…The experimental VLE data were determined through the static isothermal method described in our previous work . The chemicals used in this work include deionized water, Karl Fischer reagent, and three ILs of [Bmim]­[Cl], [Bmim]­[SCN], and [Hmim]­[Cl].…”

A novel symmetrically structured protonated ionic liquids for alkane de‐aromatization

“…However, the separation of alkanes and aromatics by rectification consumes a large amount of energy because of their close boiling points. 3 Catalytic hydrogenation does not significantly improve combustion efficiency, 4,5 not to mention its large consumption of hydrogen on no-aromatic components. 6 Adsorption is currently limited by the type of adsorbent and the adsorption flux, thus not applicable at high concentrations.…”

“…Especially for middle distillates such as diesel oil and light cycle oil (LCO), steam cracking after dearomatization is currently the most popular treatment process. However, the separation of alkanes and aromatics by rectification consumes a large amount of energy because of their close boiling points 3 . Catalytic hydrogenation does not significantly improve combustion efficiency, 4,5 not to mention its large consumption of hydrogen on no‐aromatic components 6 .…”