Ethylene Oligomerization Research Articles

Ni-H-Beta Catalysts for Ethylene Oligomerization: Impact of Parent Cation on Ni Loading, Speciation, and Siting

Ni-H-Beta catalysts for ethylene oligomerization (EO) were prepared by ion exchange of NH4-Beta and H-Beta zeolites with aqueous Ni(NO3)2 and characterized by H2-temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD), and diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS). Quadruple exchange of NH4-Beta at 70 °C resulted in 2.5 wt.% Ni loading corresponding to a Ni2+/framework aluminum (FAl) molar ratio of 0.52. [NiOH]+ and H+ are the primary charge-compensating cations in the uncalcined catalyst, as evidenced by TPR and DRIFTS. Subsequent calcination at 550 °C in air yielded a Ni-H-Beta catalyst containing primarily bare Ni2+ ions bonded to framework oxygens. Quadruple exchange of H-Beta at 70 °C gave 2.0 wt.% Ni loading (Ni2+/FAl = 0.41). After calcination at 550 °C, the resulting Ni-H-Beta catalyst comprises a mixture of bare Ni2+ ions: [NiOH]+ and NiO species. The relative abundance of [NiOH]+ increases with the number of exchanges. In situ pretreatment at 500 °C in flowing He converted the [NiOH]+ species to bare Ni2+ ions via dehydration. The bare Ni2+ ions interact strongly with the Beta framework as evidenced by a perturbed antisymmetric T-O-T vibration at 945 cm−1. DRIFT spectra of CO adsorbed at 20 °C indicate that the Ni2+ ions occupy two distinct exchange positions. The results of EO testing at 225 °C and 11 bar (ethylene) suggested that the specific Ni2+ species initially presented (e.g., bare Ni2+, [NiOH]+) did not significantly affect the catalytic performance.

Oligo- and polymerization of ethylene by pyrrolide-imine chromium catalysts bearing pendant O-, S- and N-donor groups. Synthesis, characterization and DFT studies

The synthesis and ethylene reactivity of a new set of chromium(III) complexes supported by pyrrolide-imine ligands bearing pendant O-, S- and N-donor groups [Cr{(C4H3N-2-CH=N)Z}(THF)Cl2] (Z = CH2Ph-2-OMe, Cr1; Z = Ph-2-OPh, Cr2; Z = Ph-2-OMe, Cr3; Z = Ph-2-SPh, Cr4; Z = Ph-2-SMe, Cr5; Z = CH2Py, Cr6; Z = C2H4Py, Cr7) are described. Activation of Cr1-Cr7 with MAO generates active systems affording a full range oligomerization of ethylene (C4-C12+) with turnover frequencies (TOFs) in the range of 13,900–94,200 mol(ethylene)·mol(Cr)–1·h–1 along with production of a varied amount of polymer (6.9 - 91.5 wt.%). The nature of the pendant group has a significant impact on the catalytic performances of these Cr complexes. Particularly, catalytic precursors containing pendant O-donor groups (Cr1-Cr3) produce mostly oligomers (up to 89.0 wt%) while those bearing sulfur-base donor groups (Cr4 and Cr5) are primarily polymerization systems. DFT calculations suggested the presence of two different CrIII catalytic species, the mononuclear species responsible for production of polymer and one dinuclear species that have been ascribed for production of oligomers. By tunning the reactional conditions, higher TOF and higher selectivities for production of α-olefins were achieved. Notably, the use of high MAO loading (1500 equiv.) enhanced the activity of Cr2 [TOF = 389,800 (mol ethylene)⋅(mol Cr)−1⋅h−1] producing mostly oligomers (97.7 wt% of total products) with high selectivity for α-olefins (>95.5 wt.%).

(Digital Presentation) Novel Organic Materials for Non-Aqueous Redox Flow Batteries: Implementation of Triarylamine and Phenazine Core Structures

The rapid growth of the role of renewable energy sources dictates new requirements for the efficiency, stability and scales of electrochemical energy storage devices for stationary applications [1]. Among the storage systems, redox flow batteries (RFBs) are regarded as a promising technology, since their advantages of excellent scalability, low cost, easy fabrication and operation, long lifetime, and safety. Today inorganic RFBs are penetrating the market, however, low specific capacity in conjunction with low electrochemical stability window of aqueous electrolytes (≈1.5 V) and safety issues, hinders their wide-scale commercialization. [2]. Replacing the inorganic materials with environment-friendly organic redox-active molecules may solve the capacity problems and safety issues. Moreover, the application of non-aqueous electrolytes provides a wide electrochemical stability window (e.g., up to 5 V for acetonitrile) enabling high-voltage batteries with increased energy density [3].Within the framework of the current project, we implemented a comprehensive study for a large group of novel highly soluble organic materials based on aromatic amines with general formulas of NPh3RnBrm (M1-M4) and N2Ph5RnBrm (M5-M7) where R=-(OCH2CH2)2-OCH3 (Fig. 1a). All the compounds demonstrated high solubility in MeCN (from >2.2 M up to complete miscibility), which can potentially enable outstanding specific capacities of organic RFBs approaching 134 Ah L-1 [4]. Compounds demonstrated one or two quasi-reversible electron transition processes with redox potential up to 0.6 V vs. Ag/AgNO3 electrode, which makes them perspective for the investigation in the RFBs as catholyte materials.For the RFB investigation butylviologen perchlorate (-0.75V vs. Ag/AgNO3, ~1.15 V battery voltage) was chosen as the redox pair (Fig. 1b, d). On the first step, the selection of the most appropriate electrolyte was performed: it was shown that the usage of electrolytes that contained lithium cations (Li+) and hexafluorophosphate anions (PF6 -) leads to fast decreasing of all the parameters of the RFBs, whereas the usage of the tetrabutylammonium tetrafluoroborate (TBABF4) and NaClO4 produces the stable characteristics (Fig. 1e). Final RFB tests proved that the most promising systems are capable to exhibit 65% of maximum capacities and more than 95% coulombic efficiency after 50 cycles [4] (Fig. 1f).In the next step, we focused on the creation of low-voltage anolyte material: thus, we synthesized and investigated novel phenazine derivative with oligomeric ethylene glycol ether substituents as promising anolyte material for non-aqueous organic RFBs (Fig. 1c) [5]. The designed compound undergoes a reversible and stable reduction at -1.72 V vs. Ag/AgNO3 and demonstrates excellent (>2.5 M) solubility in MeCN. A non-aqueous organic redox flow battery assembled using novel phenazine derivative as anolyte and substituted triarylamine derivative as a catholyte exhibited high specific capacity (~93% from the theoretical value), >95% coulombic efficiency, 65% utilization of active materials and good charge-discharge cycling stability (Fig. 1g).To summarize, triarylamine-based and phenazine-based materials establish themselves attractive for future research: obtained redox potentials, high solubility, fast diffusion and kinetics opens promising future directions for their usage as organic cathodic and anodic materials for non-aqueous RFBs.

Ethylene oligomerization over NiOx/SiO2-Al2O3 catalysts prepared by a coprecipitation method

Thirty-three types of NiOx/SiO2-Al2O3 with different pore structures (BET specific surface area: 32–565 m2 g−1), acid properties (total acid sites: 0.32–1.50 mmol g−1), and NiO crystallite sizes (3.8–20.6 nm) were prepared and evaluated as catalysts for ethylene oligomerization. SiO2-Al2O3 support was prepared by a coprecipitation method, and Ni was loaded on it by an impregnation method. Catalysts were characterized by nitrogen adsorption, powder X-ray diffraction, scanning electron microscopy, temperature-programmed reduction under hydrogen, and temperature-programmed desorption of ammonia. Catalytic reactions were performed in a fixed-bed, down-flow reactor operated at 300 °C and 0.1 MPa. The preparation conditions of the SiO2-Al2O3 support (i.e., type of precipitant, Al2O3 content, and aging temperature) greatly influenced the structure and activity of the resulting NiOx/SiO2-Al2O3 catalysts. The highest activity was obtained when SiO2-Al2O3 was prepared using aqueous ammonia as the precipitant, the Al2O3 content was 15%, and the aging temperature was 70 °C. The activity of this NiOx/SiO2-Al2O3 catalyst was comparable with that of Ni-AlSBA-15, which was the highest activity heterogenous catalysts reported to date. The activity of NiOx/SiO2-Al2O3 increased linearly with increasing BET specific surface area and number of acid sites of the catalyst, but it decreased with increasing Ni surface density. We speculate that highly dispersed Ni species and (weak) acid sites together improve the activity of the developed catalysts.

Catalytic performance of nickel(II) complexes bearing 1,10-phenanthroline based ligands in homogeneous ethylene oligomerization

A comparative study of catalytic activity of nickel(II) complexes bearing 1,10-phenanthroline (phen) based ligands in homogeneous ethylene oligomerization process has been performed. It was found that activated by methylaluminoxane (MMAO-12), [NiBr2(phen)] complex oligomerizes ethylene with the moderate activity (66.2 × 103 molC2H4∙molNi−1∙h−1) to the wide range (C4–C20) of even-numbered olefins, with a selectivity for linear alpha-olefins of 43%. The insertion of the carbonyl groups at the 5- and 6-position of 1,10-phenanthroline leads to an increase in catalytic activity up to 81.4 × 103 molC2H4∙molNi−1∙h−1. The presence of hydroxyl groups at the same positions causes a decrease in activity to 15.5 × 103 molC2H4∙molNi−1∙h−1. The steric hindrances near the metal center caused by the methyl groups at 2- and 9-position of 2,9-dimethyl-1,10-phenanthroline result in a decrease in the activity to (26.8–52.2) × 103 molC2H4∙molNi−1∙h−1 and increasing of the selectivity to butenes to 80–96%. The use of activated by MMAO-12 organonickel sigma-complex [NiBr(Mes)(phen)] (where Mes = 2,4,6-trimethylphenyl) bearing Ni–C bond increases the oligomerization activity – the activated complex dimerizes ethylene to mainly butenes with activity of 83.5 × 103 molC2H4∙molNi−1∙h−1. At the same time, this sigma-complex in combination with Et3Al2Cl3 and EtAlCl2 served as activators exhibits higher oligomerization activity – (348.1–394.5) × 103 molC2H4∙molNi−1∙h−1, and lower selectivity to butenes – 58–61%.

Investigation of Curing Mechanism and Mechanical Properties of Polypropylene/Aliphatic Epoxy Composites

Temperature-sensitive cure kinetics based on bisphenol A oligomeric diglycidyl ether and branching diphenylmethane di-isocyanate, polymer aliphatic or lower molecular weight aromatic amines, and polypropylene and epoxy composites were examined. Polypropylene networks are formed initially, followed by amine hardeners interfering with epoxy oxirane rings to frame linear oligomers. Finally, the system is formed by a reaction between amines obtained in the second phase and epoxy oxirane rings during the curing step. This three-stage treatment was illustrated. The activation energy was calculated using the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose isoconversational approaches to cure degree. The Ea-to-αcorrelation was determined using these approaches, revealing that the research curing systems exhibited autocatalytic effects. Among the materials studied, compounds with low molecular weight aromatic amines had the strongest and longest-lasting tensile characteristics. There are numerous advantages to slow curing and discrete stages of composite creation, including better mechanical properties.

Asymmetric carbon-bridged diphosphine based chromium complexes for selective ethylene tri-/tetramerization with high thermal stability

Asymmetric alkylphosphanyl carbon-bridged diphosphine Ph2PC = CPR1(R2)-type L1-L5 ligand has been observed to have a distinct effect on the catalytic performance of the corresponding Cr(III) based catalysts in ethylene oligomerization. Precatalyst 1, bearing diethylphosphanyl moiety, exhibited a high catalytic activity of 3628 kg·g−1·h−1 accompanied by 65.5% high C8 selectivity. Precatalyst 2 having diisopropylphosphanyl group afforded remarkably high catalytic activity of 4833 kg·g−1·h−1 with 91.8% combined (C6 + C8) product selectivity. Precatalysts 1–2 also showed good thermal stability and offer high catalytic activity at the high reaction temperature. Precatalyst 3 with sterically encumbered dicyclohexylphosphanyl substituent mainly offers C6 selectivity at the expense of the C8 fraction. Precatalyst 5 having isopropylphosphanyl moiety afforded poor catalytic activity and high C6 selectivity. Density functional theory (DFT) calculations of precatalyst 2 showed that the rate-determining step in the trimerization pathway of the catalyst may face a low energy barrier and therefore produce more C6 fraction.

Stable and reusable hierarchical ZSM-5 zeolite with superior performance for olefin oligomerization when partially coked

The character of coke is typically regarded as a “deactivator” in zeolite catalysis. We report the interdependence of coke nature and location with its true character in the mechanisms of ethylene oligomerization: a model zeolite catalyzed transformation involved in many sustainable processes. We prepared, characterized, and tested ZSM-5 zeolites of different diffusion paths and acidities, using polymeric-, organic-template, or template-free strategies and various Si/Al ratios. The results indicate that coke can improve the selectivity/yield of higher olefins and jet-fuel aliphatics, and this positive effect is better than modifying the number of acid sites. The molecular-level nature of these coke species is elucidated using high-resolution mass spectrometry. The “enhancer” character of the coke can be better exploited in polymeric templated (hierarchical) ZSM-5 zeolite because mesopores retain coke without critically affecting accessibility or causing deactivation. Furthermore, this catalyst is stable for at least 74 h on stream and in multiple reaction-regeneration cycles.

The Role of Nickel and Brønsted Sites on Ethylene Oligomerization with Ni-H-Beta Catalysts

The present work studies the adsorption of ethylene on Ni-H-Beta particles to unravel the roles of nickel and Brønsted sites in the catalytic oligomerization of ethylene. Three models (i.e., two based on the Cossee–Arlman mechanism and one based on the metallacycle mechanism) are examined in terms of the nature of the active sites and the adsorption mechanism involved in the ethylene coordination step. The results are consistent with the participation of two active sites in the formation of [Ni(II)-H]+ Cossee–Arlman centers and also suggest that ethylene dissociates upon adsorption on [Ni(II)-H]+ sites. Further characterization of Ni-H-Beta catalysts prepared at different nickel loadings and silica-to-alumina ratios reveals that highly dispersed Ni2+ exists on the catalyst surface and interacts with the catalyst’s lattice oxygen and free NiO crystals. At the same time, the kinetic results indicate that Brønsted sites may form isolated nickel-hydride ([Ni(II)-H]+) centers on the catalyst surface. In addition, the presence of residual, noncoordinated Ni2+ and Brønsted sites (not involved in the formation of [Ni(II)-H]+ sites) shows a reduced probability of the formation of nickel-hydride sites, hindering the conversion rate of ethylene. A mechanism for forming [Ni(II)-H]+ centers is proposed, involving ethylene adsorption over Ni2+ and a Brønsted site. This research has important implications for improving ethylene oligomerization processes over nickel-based heterogeneous catalysts.

Synthesis and catalytic behavior of nickel heterogenized in covalent organic frameworks as precatalysts in ethylene oligomerization

Two covalent organic frameworks (COFs), as the supports of transition metal catalysts, were prepared and coordinated with nickel to synthesize two precatalysts for ethylene oligomerization. The chemical structure of sub-constructing unit had a significant influence on the specific surface area and the catalytic performance of covalent organic frameworks supported nickel(Ⅱ) catalysts. Two COFs were stacked in lamellae, and the specific surface area and the pore volume of COF with p-phthalaldehyde as sub-constructing unit were far larger than those of COF with butanedione as sub-constructing unit. The catalyst with a larger specific surface area had a higher catalytic activity and a higher selectivity of low carbon olefins in ethylene oligomerization because of a higher specific surface areas and larger pore structure for ethylene diffusion and mass transfer. Two catalysts can be reused at least three times without considerable loss in the catalytic activity and the selectivity toward short-chain α-olefins.

Thermodynamic Optimization of the Ethylene Oligomerization Chemical Process

The use of olefin oligomerization in the synthesis of liquid fuel has broad application prospects in military and civil fields. Here, based on finite time thermodynamics (FTT), an ethylene oligomerization chemical process (EOCP) model with a constant temperature heat source outside the heat exchanger and reactor pipes was established. The process was first optimized with the minimum specific entropy generation rate (SEGR) as the optimization objective, then multi-objective optimization was further performed by utilizing the algorithm with the minimization of the entropy generation rate (EGR) and the maximization of the C10H20 yield as the optimization objectives. The results showed that the point of the minimum EGR was the same as that of SEGR in the Pareto optimal frontier. The solution obtained using the Shannon entropy decision method had the lowest deviation index, the C10H20 yield was reduced by 49.46% compared with the point of reference and the EGR and SEGR were reduced by 59.01% and 18.88%, respectively.

Preparation of NiOx/SiO2–Al2O3 catalysts by a homogenous precipitation method and their catalytic activity for ethylene oligomerization

NiOx/SiO2–Al2O3 catalysts with different pore structures (BET specific surface area: 303–709 m2 g−1, average pore size: 2.2–5.1 nm), acid properties (total amount of acid sites: 0.99–1.66 mmol g−1), and NiO particle sizes (4.6–14.7 nm) were prepared, and the structural factors influencing their catalytic activity for ethylene oligomerization were studied. SiO2–Al2O3 support was prepared by means of a homogeneous precipitation method, and supports with different physicochemical properties were obtained by changing the preparation conditions. Ni was loaded by means of an impregnation method. Catalytic reactions were performed in a fixed-bed down-flow reactor operated at 300 °C and 0.1 MPa. NiOx/SiO2–Al2O3 catalysts prepared with the homogenous precipitation method had a higher surface area, more uniform pore size, and a larger amount of acid sites, and they showed a higher activity not only compared with NiOx/SiO2–Al2O3 catalysts prepared by means of our previous coprecipitation method but also compared with Ni-AlSBA-15, the best heterogenous catalyst for ethylene oligomerization reported to data. The catalytic activities of the NiOx/SiO2–Al2O3 catalysts strongly depended on the BET specific surface area and the amounts of acid sites. The optimal amounts of weak, medium-strength, strong, and total acid sites were 0.5, 0.3, 0.4, and 1.2 mmol g−1, respectively. Examination of the structure–activity relationships of the catalysts suggested that their catalytic activity was promoted by close contact between the Ni and acid sites.

First-Principles Analysis of Ethylene Oligomerization on Single-Site Ga3+ Catalysts Supported on Amorphous Silica

First-Principles Analysis of Ethylene Oligomerization on Single-Site Ga³⁺ Catalysts Supported on Amorphous Silica

Direct synthesis of hyperbranched ethene oligomers and ethene‐MA co‐oligomers using iminopyridyl systems with weak neighboring group interactions

AbstractThe synthesis of hyper‐branched ethene oligomers through catalytic insertion reactions with late transition metal catalysts is unique in its synthetic and practical scope. In this study, a series of iminopyridyl Ni(II) and Pd(II) complexes with electron‐rich distal aryl motifs were synthesized and characterized. These complexes were very efficient in ethene oligomerization and co‐oligomerization with methyl acrylate (MA). Hyperbranched ethene oligomers with different microstructures were generated using different metal species in ethene oligomerization. More importantly, hyperbranched ethene‐MA co‐oligomers with varying incorporation ratios were generated via ethene and MA co‐oligomerization using the Pd(II) complexes. Most notably, weak neighboring group interactions of distal aryl motifs in the nickel system are more effective in influencing the microstructure of ethene oligomers than the corresponding palladium system.

Novel Ni-SIRAL Catalyst for Heterogeneous Ethylene Oligomerization

Novel Ni-SIRAL Catalyst for Heterogeneous Ethylene Oligomerization

Kinetic Modeling of Ethene Oligomerization on Bifunctional Nickel and Acid β Zeolites

Kinetic Modeling of Ethene Oligomerization on Bifunctional Nickel and Acid β Zeolites

Catalytic oligomerization and polymerization of ethylene with complexes of iron triad metals: influence of metal nature and new prospects

In the last five years the field of catalytic oligomerization and polymerization of olefins using complexes of late transition metals has been the most intensively developing area of post-metallocene catalysis. This review is devoted to detailed analysis of the influence of metal nature on the catalytic properties of systems based on complexes of iron triad metals. Some novel and developing areas of application of such complexes in olefin oligomerization and polymerization (ethylene trimerization, production of olefins with an odd number of carbon atoms and polyethylene waxes, targeted synthesis of heavy fractions of ethylene oligomers) are surveyed. Different approaches to the heterogenization of catalysts on various solid supports are considered.The bibliography includes 225 references.

Bis(pyrazolyl)thioether/amine‐chromium(III) catalysts bearing pendantO‐ andN‐donor group for oligomerization and polymerization of ethylene

In this work, a new family of chromium complexes supported by bis(pyrazolyl)thioether/amine ligands containing pendantO‐ andN‐donor groups CrCl3{S‐bis[(3,5‐DMPz)methyl]sulfide} (2a), CrCl3{N‐bis[(3,5‐DMPz)benzylamine]} (2b), CrCl3{N‐bis[(3,5‐DMPz)butylamine]} (2c), [CrCl2{N‐bis[(3,5‐DMPz)methyl][(2‐pyridinyl)methyl]amine}]Cl (2d), [CrCl2{N‐bis[(3,5‐DMPz)methyl][quinoline]amine}]Cl (2e), [CrCl2{N‐bis[3,5‐DMPz‐methyl][EtNMe2]amine}]Cl (2f), CrCl3{N‐bis[(3,5‐DMPz)methyl][2‐methoxyphenyl]amine} (2g), and CrCl3{N‐bis[2‐(3,5‐DMPz)methyl][(2‐pyridyl)ethyl]amine} (2h) were synthetized and characterized by elemental analysis and Fourier transform infrared spectroscopy (FTIR) spectroscopy. Density functional theory (DFT) calculations demonstrated that the pendant group as well as the spacer between theN‐donor group and the central amine nitrogen have strong influence on the coordination motif of the ligand. Thus,1d–1fact as tetradentate ligands while1gand1hpreferably coordinated to the chromium metal center in a tridentate [N,N,N] mode fashion. The catalytic performance of2a–2his strongly influenced by the nature of the central bridging atom (S, N) as well as the pendantO‐ andN‐donor group. Upon activation with methylaluminoxane (MAO), chromium precatalysts2a–2c,2e, and2fgenerated active systems producing oligomers ranging from C4to C12+with a high selectivity for α‐olefins (>82.4%). On the other hand, precatalysts bearing pyridine (2dand2h) and methoxy (2g) functionalized amine bis (pyrazolyl) ligands exclusively produce polyethylene (PE) with activities in the range of 107.2–372.0 kg of PE·mol[Cr]−1 h−1.

Slow-chain-walking polymerization of ethylene and highly chain-straightening polymerization of 1-hexene to access semicrystalline polyolefins

The production of semicrystalline polyolefins using α-diimine late transition metal catalysts is highly desired but challenging in both ethylene and α-olefin polymerization, which relates to fundamental steps such as slow-chain-walking and highly chain-straightening events. In this work, by the combination of 4-(diphenylamino)phenyl moiety with different bulky substituents including H, Me, CHPh2, and Ph groups, a new family of unsymmetrical α-diimine nickel catalysts Ni1-Ni4 has been prepared. Under the activation of co-catalyst, these catalysts are highly active (107 g mol-1h−1) for ethylene polymerization, giving polymers from branched ethylene oligomers to linear ultrahigh molecular weight polyethylenes (UHMWPEs) over a wide temperature range of 30–70 °C. Notably, the preferred Ni4 even enables a slow-chain-walking process and thus is capable of producing linear, semicrystalline UHMWPE (Mn = 1056 kg mol−1, brs = 9.1/1000C, Tm = 123.5 °C) at low ethylene pressure of 1 bar. Likewise, in 1-hexene polymerization Ni4 is highly selective (88.1%) for uncommon 2,1-insertion followed by complete chain-walking. Thus, the chain-straightening polymerization of 1-hexene efficiently yields semicrystalline poly(1-hexene) with a high Tm of 102.1 °C that resembles low-density polyethylene (LDPE).

The Effect of Fluorinated Solvents on the Physicochemical Properties, Ionic Association, and Free Volume of a Prototypical Solvate Ionic Liquid.

Solvate ionic liquid (SIL) synthesis and properties depend on a delicate balancing of cation-solvent and cation-anion interactions to produce materials containing only cation-solvent complexes and solvent-separated anions. Most SILs meeting these characteristics fall within the paradigm of oligomeric ethylene oxides (e.g. glymes and glycols) and lithium salts. Targeted functionalization of solvent molecules to achieve desired properties is a relatively unexplored avenue of research. Fluorinated solvents have significantly different electric charge distributions compared to their nonfluorinated analogs. We test the impact of solvent fluorination for a SIL created from equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide (LiNTf2 ) and triethylene glycol (TEG), hereafter [(TEG)1 Li]NTf2 . In the first experiment, TEG is partially substituted with 2,2,4,4,5,5,7,7-octafluoro-3,6-dioxaoctane-1,8-diol (FTEG). This leads to a precipitous decrease in ionic conductivity and larger quantities of ionically-associated Li(NTf2 )2 - species, as detected with vibrational spectroscopy. These observations suggest FTEG does not readily coordinate Li+ ions in a manner analogous to TEG. Computational studies reinforce this conclusion. Relative complex cation stabilities are ranked as [(FTEG)1 Li]+ >[(TEG)1 Li]+ . A second experiment adds FTEG as a diluent to [(TEG)1 Li]NTf2 . This places FTEG and TEG in competition to coordinate a limited number of Li+ ions. The resulting mixtures exhibit conductivity enhancement over the parent SIL and minimal changes in ion speciation due to the poor Li+ binding by FTEG compared to TEG. Positron annihilation lifetime spectroscopic studies point to increased amounts of free volume upon dilution of FTEG. This likely explains the origin of the conductivity and viscosity enhancements.