Supporting Information for The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and the Effect of Tetraglyme on CO2 Solubility.

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1 Supporting Information for The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and the Effect of Tetraglyme on CO2 Solubility. Joseph J. Fillion, Joshua Edward Bennett and Joan F. Brennecke* Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana, 46556, USA Corresponding Author *Tel: (574) Fax: (574) jfb@nd.edu The Supporting Information includes details on the NMR characterization of [hmmim][tf2n], Figure S, a graph of the G values as a function of temperature for the various IL + tetraglyme mixtures, information on the excess molar volumes of [P6664][3-Triz] + tetraglyme mixtures and CO2 solubility data analysis. NMR Characterization Figure S: Proton NMR spectrum of [hmmim][tf2n]. The signals at 2.5 ppm and ~3.3 ppm are solvents residual peaks (DMSO and water, respectively).

2 G Value Figure S2 is the graphical form of Table 4 that is located in the main text. Description of the trends in also located in the main manuscript..5 G T / K Figure S2: The value G, from equation 3 in main manuscript, of [P6664][4-NO2imid], [P6664][4,5-CNimid], [P6664][Tf2N], [P6664][2-CH3,5-NO2imid], [P6664][DCA], [hmim][tf2n], [P6664][BrBnim], [P6664][Acetate], [hmmim][tf2n], [P6664][4-Triz], [P6664][3-Triz], [P4442][3-Triz], [P2228][4-NO2pyra], [P2228][4-NO2imid], [P2228][2-CH3,5-NO2imid], [mm(butene)im][4-no2pyra], [P2224][2-CH3,5-NO2imid], and [pmmim][4-no2pyra] from K to 33.5 K. Excess Molar Volumes The density of mixtures of [P6664][3-Triz] and tetraglyme were measured at temperatures between K and K. In addition, the density of pure [P6664][3-Triz] and pure tetraglyme were measured. These data are shown in Table 7 of the main manuscript. The uncertainty in the density of the pure IL is as high as.2 g cm -3 when impurities are taken in to consideration. However, the reproducibility of the measurements is. g cm -3. The excess molar volumes were calculated with the following equation: VV EE = VV mm xx IIII VV IIII xx TTTT VV TTTT where the molar volume is the molecular weight divided by the density (i.e. V=MW/ρ) and TG is an abbreviation used for tetraglyme. As seen in Table S, the excess molar volume is greatest

3 around a mole fraction of.5 of [P6664][3-Triz]. These data are plotted in Figure 4 of the main manuscript. CO2 Solubility The solubility of CO2 in tetraglyme, [P6664][3-Triz], [P6664][4-Triz], [P6664][3-Triz] mixed with tetraglyme (TG), and [P6664][4-Triz] mixed with TG were reported in the main manuscript in terms of mole fraction. In Tables S2 and S3, we report the same data in terms of mole ratio, Z, which is moles of CO2 per mole of tetraglyme, IL, or tetraglyme + IL mixture. Figure S3a through S3b compare our measurements of the solubility of CO2 in tetraglyme to those from the literature. The values agree within experimental uncertainty. Figure S3a and Figure S3b shows the difference in graphing the data in terms of mole fraction or mole ratio. The mole ratio increases linearly with increasing pressure at pressures up to 3.5 MPa whereas it increases sharply at higher pressures, Figure S3c. The new data at 33.5 K, K, and K are all linear to 3.5 MPa, as shown in Figure S4. The mole ratio based Henry s law constants, P=HzZ, are 3.6, 5.26 and 7.46 MPa, respectively. The ILs can react stoichiometrically with CO2. If this were the only effect and they were fully saturated with CO2, then the mole ratio would be.. Of course, CO2 also dissolves in these ILs by physical dissolution, which becomes more important at higher pressures. The solubility of CO2 in [P6664][3-Triz] and [P6664][4-Triz], in terms of mole ratio, is shown in Figures S5 and S6. [P6664][3-Triz] only weakly reacts with CO2 so the data, in terms of mole ratio, is not far from linear over the entire pressure range. However, [P6664][4-Triz] reacts more strongly with CO2, as indicated by the significant curvature in the data at lower pressures. The solubility of CO2 in mixtures initially composed of 7 mole % IL + 3 mole % TG were analyzed using a simple additivity equation: Zidealmixture=ZIL (T,p)*xIL + p*hz(t)*xtg Zidealmixture is the mole ratio solubility of CO2 of an ideal mixture, ZIL (T,p) is the CO2 mole ratio in the pure IL at the specified pressure (p) and temperature (T), Hz(T) is the mole ratio based Henry s law constant for CO2 solubility in pure TG, xil is mole fraction of IL in the original IL/TG mixture, and xtg is the mole fraction of tetraglyme in the original IL/TG mixture. As shown in Figures S7 and S8, this simple additive model predicts the CO2 solubility in the IL/TG mixtures reasonably well. Figure S9 shows the separate contributions to the CO2 solubility for [P6664][4- Triz] at 33.5 K. This analysis indicates that tetraglyme does not interfere with the ability of the aprotic heterocyclic anion to chemically bind with CO2. Table S4 compares the solubility of CO2 in neat [P6664][4-Triz] and [P6664][3-Triz] near. MPa from this work with data from the literature. A direct comparison is not possible because the temperatures are different. However, the data appears to be consistent. Seo et al. measured

4 the solubility of CO2 at multiple pressures up to. MPa 2 while McCrellis et al. only report a single data point at. MPa. 3 Table S: Excess molar volume of [P6664][3-Triz] (x) mixed with tetraglyme. Mole fraction V E / cm 3 mol - T / K Table S continued: Excess molar volume of [P6664][3-Triz] (x) mixed with tetraglyme. Mole fraction V E / cm 3 mol - T / K

5 Table S2: Solubility of CO2 in tetraglyme, [P6664][3-Triz], and [P6664][4-Triz] at 33.5 K, K, and K, in terms of mole ratio, which is mole CO2 per (mole IL+ mole TG). Tetraglyme (TG) [P6664][3-Triz] [P6664][4-Triz] T / K p / MPa Z (mole CO2/mole TG) T / K p / MPa Z (mole CO2/mole IL) T / K p / MPa Z (mole CO2/mole IL)

6 Table S3: Solubility of CO2 in [P6664][3-Triz] mixed with 3 mole % tetraglyme and in [P6664][4-Triz] mixed with 3 mole % tetraglyme at 33.5 K, K, and K, in terms of mole ratio, which is mole CO2 per mole IL+ mole TG. [P6664][3-Triz].7 / TG T / K p / MPa Z (mole CO2/mole IL+TG) [P6664][4-Triz].7 / TG T / K p / MPa Z (mole CO2/mole IL+TG)

7 Mole fraction of CO Kodama et al., 2 This work Figure S3a: Solubility of CO2 in tetraglyme at 33.5 K from this work Kodama et., 2 in terms of mole fraction. and

8 .4 Mole ratio (mol CO 2 / mol TG) Kodama et al., 2 This work Figure S3b: Solubility of CO2 in tetraglyme at 33.5 K from this work Kodama et., 2 in terms of mole ratio. and Mole ratio (mol CO 2 / mol TG) 4 Kodama et al., This work Figure S3c: Solubility of CO2 in tetraglyme at 33.5 K from this work Kodama et., 2 in terms of mole ratio up to a higher pressure. and

9 Mole ratio (mol CO 2 / mol IL + TG) y =.34x y =.278x y =.9x 33.5 K K K Figure S4: Solubility of CO2 in tetraglyme at 33.5 K, K, and K Mole ratio of CO K K K Figure S5: Solubility of CO2 in [P6664][3-Triz] at K, K, and K.

10 .6.4 Mole ratio of CO K K Figure S6: Solubility of CO2 in [P6664][4-Triz] at 33.5 K and K..6 Mole ratio (mol CO 2 / (mol IL + TG)) K ideal mixture K ideal mixture K ideal mixture 33.5 K K K Figure S7: Solubility of CO2 in [P6664][3-Triz] mixed with 3 mole % tetraglyme at 33.5 K, K, and K. The ideal mixture lines are a simple addition of the solubility of CO2 in pure [P6664][3-Triz] and in pure tetraglyme (in terms of mole ratio), weighted by the liquid mixture mole fractions.

11 Mole ratio (mole CO 2 / (mole IL+mole TG)) K K K 33.5 K ideal mixture K ideal mixture Figure S8: Solubility of CO2 in [P6664][4-Triz] mixed with 3 mole % tetraglyme at 33.5 K, K, and K. The ideal mixture lines are a simple addition of the solubility of CO2 in pure [P6664][4-Triz] and in pure tetraglyme (in terms of mole ratio), weighted by the mixture mole fractions. Mole ratio (mole CO 2 / (mole IL+mole TG)) Ideal mixture [P6664][4 Triz] Mixture tetraglyme Figure S9: Solubility of CO2 in [P6664][4-Triz], [P6664][4-Triz] mixed with 3 mole % tetraglyme, and tetraglyme at 33.5 K. The ideal mixture line is a simple addition of the solubility of CO2 in pure [P6664][4-Triz] and in pure tetraglyme (in terms of mole ratio), weighted by the mixture mole fractions.

12 Table S4: Comparison of the solubility of CO2 in [P6664][4-Triz] and in [P6664][3-Triz] near. MPa with previously published data. Note that the temperatures are different. Ionic liquid p / MPa T / K Z (mole CO2/mole IL) [P6664][4-Triz] * * [P6664][3-Triz] *This work * * References ) Kodama, D.; Kanakubo, M.; Kokubo, M.; Hashimoto, S.; Nanjo, H.; Kato, M. Density, viscosity, and solubility of carbon dioxide in glymes. Fluid Phase Equilib., 2, 32, 3-8 2) Seo, S.; Quiroz-Guzman, M.; DeSilva, M. A.; Lee, T. B.; Huang, Y.; Goodrich, B. F.; Schneider, W. F.; Brennecke, J. F. Chemically Tunable Ionic Liquids with Aprotic Heterocyclic Anion (AHA) for CO2 Capture. J. Phys. Chem. B, 24, 8, ) McCrellis, C.; Taylor, S. F. R.; Jacquemin, J.; Hardacre, C. Effect of the Presence of MEA on the CO2 Capture Ability of Superbase Ionic Liquids. J. Chem. Eng. Data, 26, 6, 92-

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