A systematic approach to design task-specific ionic liquids and their optimal operating conditions

Abstract

Carbon capture and storage (CCS) has gained great interest in recent years as a potential technology to mitigate industrial carbon dioxide (CO 2 ) emissions. Ionic liquids (ILs) were identified as potential CO 2 capturing solvents, due to their negligible vapour pressure, high thermal stability, and wide range of thermophysical properties. However, determining a task-specific IL merely through experimental studies is tedious and costly, as there are about a million possible combinations of cations and anions that may make up the ILs. This work presents a systematic approach to design an optimal IL for the purpose of carbon capture. The significant contribution of the presented approach in this work is the introduction of disjunctive programming to identify optimal operating conditions of the process involved while solving the IL synthesis problem. As studies show, the performance of ILs changes with the operating conditions, which in turn affects overall performance of the carbon capture process. Hence, the presented approach will determine the optimal IL by considering the effect of system operating conditions, and simultaneously determining optimal conditions of the carbon capture process. Operating conditions of the process are modelled as continuous variables; disjunctive programming can discretise these variables and reduce search space for results. Since most of the ILs to be designed are novel solvents, their thermophysical properties are estimated using the group contribution (GC) method. Appropriate structural constraints are defined to ensure the structure of the synthesised IL is feasible. An illustrative case study is solved to demonstrate the proposed approach.

Computational design of heterogeneous catalysts and gas separation materials for advanced chemical processing

“…During the past few decades, the computer-aided molecular design (CAMD) method [23] has been widely used for optimal solvent design [24][25][26][27][28]. Considering the strong interactions between solvent selection and process operation, integrated solvent and process design is also essential [29][30][31][32][33]. Figure 5 shows the schematic diagram for solvent and process design using the CAMD method.…”

Design of Ionic Liquid as Carbon Capture Solvent for a Bioenergy System: Integration of Bioenergy and Carbon Capture Systems

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Equation (26) is the objective function formulated using Equations (16) and (22).…”

“…22 Peng-Robinson fluid package is used to simulate the process because it was shown to be suitable to simulate CO 2 desorption from ILs. The flowsheet for CO 2 desorption from IL-based solvent is shown in Figure 6.…”

“…31 CO 2 solubility of pure IL is estimated through vapour liquid phase equilibrium as shown in Equations(21)and(22).…”

CO2 capture by methanol, ionic liquid, and their binary mixtures: Experiments, modeling, and process simulation

“…A number of predictive thermodynamic models are available for modeling the solubility of CO 2 in ILs . Among others, the universal quasichemical (UNIQUAC) functional‐group activity coefficients (UNIFAC) model for ILs constantly developed by our group (UNIFAC‐Lei model) has attracted wide attention, and it produces solid outcomes in various‐specific applications due to the unique advantages: (1) it provides quantitative accurate predictions; (2) its formulation is simple, and thus the calculation speed is rapid; (3) its parameters can be readily utilized in the modern simulation packages (e.g., Aspen Plus, PROII, and ChemCAD) for simulation and optimization of the desired industrial processes; and (4) in terms of the UNIFAC‐Lei preferable decomposition approach, the introduced main groups and subgroups together with their derived parameters are appropriate for the ILs‐based designing methodologies for specific applications . Thus, the UNIFAC‐Lei model has been extended in this work to predict the solubility of CO 2 in the proposed solvents.…”