AlCl3 Ionic Liquid Research Articles

Analysis of long term catalytic performance for isobutane alkylation catalyzed by NMA–AlCl3 based ionic liquid analog

Abstract Isobutane alkylation with 2-butene to produce high-quality gasoline was catalyzed by N-methylacetamide (NMA)–AlCl3 based ionic liquid (IL) analog with a NMA/AlCl3 molar ratio of 0.75 and CuCl modification, which was marked as CuCl-modified 0.75NMA–1.0AlCl3. The long-term experiment was carried out in the autoclave operated in continuous mode to investigate the distribution of alkylate under different experimental nodes. The result indicated that the long-term alkylation was divided into three stages: rising, stable, and descending regions. C8 selectivity and molar ratio of trimethylpentanes (TMPs) to dimethylhexanes (DMHs) reached the highest level in the stable region, and research octane number (RON) of alkylate was as high as 97. Anionic Al species ([Al2Cl7]−, [AlCuCl5]−) and cationic Al species ([AlCl2L]+) from IL analog as two active Lewis acidic species played a catalytic role in the long-term alkylation, whereas the neutral Al species did not participate into the alkylation. Moreover, the structure of CuCl-modified 0.75NMA–1.0AlCl3 was destroyed after the deactivation, and CuCl was enriched in the CD2Cl2-insoluble substance, resulting in a decreasing TMP/DMH ratio. The catalytic lifetime of IL analog was similar with CuCl-modified 0.55Et3NHCl–1.0AlCl3 IL, but IL analog had a lower cost.

Stability, Deactivation, and Regeneration of Chloroaluminate Ionic Liquid as Catalyst for Industrial C4 Alkylation

Alkylation of isobutane and 2-butene was carried out in a continuous unit using triethylamine hydrochloride (Et3NHCl)-aluminum chloride (AlCl3) ionic liquid (IL) as catalyst. The effects of impurities such as water, methanol, and diethyl ether on the stability of the catalytic properties and deactivation of the ionic liquid were studied in the continuous alkylation. In the Et3NHCl-2AlCl3 ionic liquid, only one half of the aluminum chloride could act as the active site. With a molar ratio of 1:1, the active aluminum chloride in the ionic liquid was deactivated by water by reaction or by diethyl ether through complexation while the complexation of aluminum chloride with two molecular proportions of methanol inactivated the active aluminum chloride in the ionic liquid. The deactivation of chloroaluminate ionic liquid was observed when the active aluminum chloride, i.e., one half of the total aluminum chloride in the ionic liquid, was consumed completely. The regeneration of the deactivated ionic liquid was also investigated and the catalytic activity could be recovered by means of replenishment with fresh aluminum chloride.

Electrodeposition and Anodization of Al–W Alloy Films

Al–W alloys are known to exhibit high corrosion resistance and mechanical strength. Thus, Al–W alloys have attracted much research attention as corrosion-protective coatings for reactive materials such as Mg alloys and steels.1–3 Recently, our research group reported that dense Al–W alloy films can be electrodeposited from 1-ethyl-3-methylimidazolium chloride (EMIC)–AlCl3 ionic liquids containing W6Cl12 as the tungsten precursor.3 In this study, we explored the feasibility of anodization of electrodeposited Al–W alloy films with the aim of providing the films with additional functionalities. Anodization of Al metal yields a porous Al2O3 layer on its surface. Hence, the anodization of Al–W alloys should potentially yield a porous Al2O3 layer containing WO3. WO3is a photocatalytic material sensitive to visible light and decomposes pollutant organic compounds under visible light illumination. Therefore, the electrodeposition and anodization of Al–W alloy films can be a facile process to produce corrosion-protective coatings with additional functionalities such as water purification and self-cleaning. Only a few reports on the anodization of Al–W alloy films are available in literature,4and the anodization behavior of Al–W alloy films under different anodization conditions has not been elucidated. In addition, the properties of anodized films have not been investigated. In this study, we investigated the effect of anodization conditions on the microstructure of the porous layer obtained after the anodization of the Al–W alloy films. The photocatalytic activity of the anodized films was also evaluated. Al–W alloy films containing ~12 at% W were electrodeposited from an EMIC–AlCl3 ionic liquid containing W6Cl12. The anodization of the Al–W alloy films was carried out by applying 40 V between them and a platinum cathode in an oxalic acid solution for up to 40 min. The cross-sectional SEM images of the films revealed that pores with diameters of 10–30 nm were formed on their surface. These pores extended up to ~2 μm in the direction toward the substrate. The anodized films displayed bright interference colors, which varied with the anodization conditions. The photocatalytic activity of the anodized films was evaluated by measuring the photo-decomposition rate of Congo Red (CR) in aqueous solution. The anodized film was immersed in a 1 μM solution of CR and was illuminated with a xenon lamp (wave length = 350–750 nm). The anodized films decomposed more than 30% of CR in 180 min. The decomposition performance of the anodized films was higher than that of the as-deposited film. 1. T. Tsuda, Y. Ikeda, T. Arimura, M. Hirogaki, A. Imanishi, S. Kuwabata, G. R. Stafford, and C. L. Hussey, J. Electrochem. Soc., 161, D405 (2014). 2. K. Sato, H. Matsushima, and M. Ueda, ECS Trans., 75, 305 (2016). 3. S. Higashino, M. Miyake, H. Fujii, A. Takahashi, and T. Hirato, J. Electrochem. Soc., 164, D120 (2017). 4. S. J. Garcia-Vergara, P. Skeldon, G. E. Thompson, and H. Habazaki, Surf. Coat. Technol., 201, 9506 (2007).

Evaluation of the hardness and Young's modulus of electrodeposited Al–W alloy films by nano-indentation

Al–W alloy films with various W contents up to ~12 at.% were prepared by electrodeposition using 1-ethyl-3-methylimidazolium chloride (EMIC)–AlCl3 ionic liquids with different concentrations of W precursor, W6Cl12. The hardness (H) and Young's modulus (E) of the films were examined by nano-indentation. The films were composed of a single-phase fcc Al super-saturated solid solution, an amorphous phase, or both, depending on the W content and the deposition conditions. The H value increased with increasing W content up to 9.8 at.% and then decreased slightly with further increases in the W content up to 12.4 at.%. A similar trend was observed in the E value with increasing W content, but the decrease in E value at 12.4 at.% W was more significant than that in H value. The changes in the H and E values are discussed from the viewpoints of the grain size and the constituent phases. The 9.8–12.4 at.% W films, which had relatively high H values and H/E ratios, are expected to have a higher resistance to mechanical damage than Al films.

Electrodeposition of Al-W Alloy Films in a 1-Ethyl-3-methyl-imidazolium Chloride-AlCl3 Ionic Liquid Containing W6Cl12

The electrodeposition of Al-W alloy films in a Lewis acidic 1-ethyl-3-methyl-imidazolium chloride (EMIC)-AlCl3 ionic liquid using W6Cl12 as the W ion source was investigated. W6Cl12 dissolved in the ionic liquid at a higher concentration than other W ion sources used in previous studies. Potentiostatic electrodeposition was performed in a bath containing W6Cl12 at a concentration of 49 mM. Dense Al-W alloy films containing up to 12 at.% W were electrodeposited at potentials more negative than 0 V vs. Al/Al(III). The deposition current density at >0 V was lower than 0.3 mA cm−2, while that for Al-W alloy films was higher and reached 38 mA cm−2 at −0.5 V. The deposition of W was induced by the deposition of Al. At lower W concentrations, the Al-W alloy films were composed of a super-saturated solid solution, and in the W content range of 9–12 at.% they comprised an amorphous phase. Potentiodynamic polarization and nano-indentation showed that the Al-W alloy films containing 10–12 at.% W exhibited high pitting corrosion resistance, high hardness, and low Young's modulus.

Electrodeposition of Al-W Alloy Films from Ionic Liquid and Evaluation of Their Corrosion Resistance and Mechanical Properties

Introduction The many useful characteristics of Al, particularly its high oxidation and corrosion resistance, make Al coatings effective in extending the lives of metallic materials. However, if Al is exposed to an environment where chloride ions are present (like seawater), the Al passivation layer is destroyed locally, followed by the creation of small holes on the surface. This form of corrosion is called pitting corrosion, and Al–transition metal alloys are known to exhibit a resistance to pitting corrosion. In particular, sputtered Al–W alloy films are reported to show outstanding pitting corrosion resistance [1-3]. Establishing a method for electrodeposition of Al–W films is of importance for industrial applications, because electrodeposition has advantages over other film formation processes including simple equipment, high film formation speed, and applicability in the case of complex surface shapes. Tsuda et al. reported the electrodeposition of Al–W alloys with a high W content from the 1-ethyl-3-methylimidazolium chloride(EMIC)–AlCl3 ionic liquid containing K3W2Cl9 [4]. However, these Al–W alloys had a powdery morphology when the W content was higher than 3 at%, and did not show significant pitting corrosion resistance. In this study, we formed smooth, dense and adherent Al–W alloy coatings by electrodeposition from the EMIC–AlCl3 ionic liquid with the addition of WCl2, and we investigated the pitting corrosion resistance of the resulting coatings. Furthermore, we evaluated the mechanical properties of the Al–W alloy coatings. Experimental The electrolytic bath was prepared by mixing EMIC with anhydrous AlCl3, and tungsten(II) chloride. The tungsten(II) chloride was prepared by reduction of tungsten(VI) chloride by bismuth. The electrodeposition of Al–W films was conducted under galvanostatic conditions using Cu and Al plates as the cathode and anode, respectively. The bath temperature was 80°C. All electrodeposition experiments were conducted in an argon-filled glove box. The electrodeposited films were analyzed by SEM, EDX, and XRD. Partial current density and current efficiency were determined by ICP-AES. The water content of the electrolytic bath was measured by the coulometric Karl Fischer method. Pitting corrosion potentials were determined by linear sweep voltammetry in a deaerated 3.5 wt% NaCl aqueous solution at room temperature. The mechanical properties of Al–W films were analyzed by the nano-indentation method. Results and Discussion The electrodeposited Al–W films were gray and had a rather smooth appearance. Surface and cross-sectional SEM observation showed that these films were composed of dense globular grains, which is characteristic of amorphous deposit. The average grain size was less than 3 μm. At a fixed concentration of tungsten (II) chloride in the bath, the W content of the films was, typically 15–16 at%, independent of the current density. XRD measurements detected no diffraction peaks from these Al–W films, indicating that the films were amorphous. The current efficiency for the Al–W electrodeposition estimated by ICP-AES was less than 87%, which was lower than that for pure Al electrodeposition. Further, the water content was found to be higher in the electrolytic bath with tungsten(II) chloride than in the bath without it. Therefore, the current loss is attributed to the reduction of water. The pitting corrosion potential of the Al–W alloy film was more positive by >800 mV than that of pure Al, indicating that the Al–W films have a high resistance to the pitting corrosion. Nano-indentation showed that the amorphous Al–W alloy films had high hardness and low elastic modulus compared to a pure Al film. As the alloy films were amorphous, the films contained no grain boundaries and dislocations, and this should be responsible for the excellent hardness and elastic modulus. Conclusion Smooth, dense, and adherent Al–16 at% W alloy films were obtained by electrodeposition. The Al–W alloy films exhibited excellent pitting corrosion resistance and mechanical properties compared with pure Al films. These results sufficiently demonstrate the potential applications of the electrodeposited Al–W alloy as a surface protective material.

Template-free electrodeposition of AlFe alloy nanowires from a room-temperature ionic liquid as an anode material for Li-ion batteries.

AlFe alloy nanowires were directly electrodeposited on copper substrates from trimethylamine hydrochloride (TMHC)-AlCl3 ionic liquids with small amounts of FeCl3 at room temperature without templates. Coin cells composed of AlFe alloy nanowire electrodes and lithium foils were assembled to characterize the alloy electrochemical properties by galvanostatic charge/discharge tests. Effects of FeCl3 concentration, potential and temperature on the alloy morphology, composition and cyclic performance were examined. Addition of Fe into the alloy changed the nanowires from a 'hill-like' bulk morphology to a free-standing morphology, and increased the coverage area of the alloy on Cu substrates. As an inactive element, Fe could also buffer the alloys' large volume changes during Li intercalation and deintercalation. AlFe alloy nanowires composed of a small amount of Fe with an average diameter of 140 nm exhibited an outstanding cyclic performance and delivered a specific capacity of about 570 mA h g(-1) after 50 cycles. This advanced template-free method for the direct preparation of high performance nanostructure AlFe alloy anode materials is quite simple and inexpensive, which presents a promising prospect for practical application in Li-ion batteries.

Electroplating of Aluminum with Nickel Particle Codeposition

Aluminum-nickel nanostructured thin films have many uses. The exothermic mixing of the phases may be implemented for localized heat generation wherever restricted welding, brazing or local energy release may be required. Current fabrication methods generally rely on vapor deposition processes that require high vacuum and are limited to low rates. New fabrication methods such as electroplating these films can result in significant improvement of energetic density and cost savings. To pursue this, we investigated aluminum deposition to determine the characteristics and mechanism of the complex reduction process, nickel particle incorporation into an aluminum matrix, and nickel deposition properties in a multicomponent bath.Because aluminum has a lower atomic density than nickel and the desired mixing ratio is 1:1, the aluminum volume must be 60% of the total. The codeposition process is limited in its capability for particle incorporation by particle diffusion and geometric hindrances and therefore the particulate species is almost always a significantly lower volume percentage than the matrix. For this reason the aluminum is the matrix material that is deposited out of the electrolyte and the nickel component is incorporated as imbedded particles. Aluminum deposition must be carried out in aprotic solvents because the reduction potential is lower than that of hydrogen, making aluminum deposits using aqueous solutions inefficient and low quality. Electrolytes were characterized based on transport properties and deposition kinetics.Some of the most promising aluminum deposition is done in Chloroaluminate RTILs (room temperature ionic liquids) 2. These solutions are high aluminum concentration and low vapor pressure but typically high viscosity. Additions of toluene have improved the dendritic morphology and at 30-50 volume% toluene, the bath produces a smooth uniform coating of aluminum 1. The dilutions reduce the viscosity, and participate in complexing with the reactants, modifying the reduction and transport properties. These electrolytes are investigated with RDE and EIS to determine the reaction properties of aluminum deposition. The reported reduction of aluminum metal occurs from the complex Al2Cl7-. This bulky anion has very poor diffusion properties, there are kinetic limitations due to the complex multi-step reduction process and our experiments aim to analyze the reaction mechanism to optimize the electrolyte composition, speciation and applied deposition current and potential.EIS conductivity measurements show that pure TMPAC:AlCl3 ionic liquids have low conductivity and the conductivity is greatly increased with dilution with toluene or dichlorobenzene, although a maximum is reached as the improved transport starts to be overcome by the reduced ionic concentrations. This maximum conductivity is reached at about 50-60 molar% of DCB to IL.Although these aluminum deposition electrolytes have been used before, little fundamental understanding of mechanism has been undertaken; a better understanding of the reaction properties will allow for design of a more effective codeposition process. Codeposition with particulates in aluminum enables production of heterogeneous films with improved mechanical properties; and cost effective bilayer or alloy deposition will increase aluminum’s already large applicability. Bi-phasic films may also be produced by alternatively depositing Al and Ni layer, and Nickel properties in the electrolyte were studied to develop this fabrication method also.Comparisons are made between the electrochemically produced film and the commercial PVD film. These are characterized by energy release, burn rate. The high interfacial area of these films is subject to atomic diffusion which can reduce the burn characteristics. TEM analysis of the interfacial layers seems to indicate that the lower temperature process associated with codeposition can reduce this pre-reaction mixing. Accelerated aging is being performed on film from both fabrication methods and increased temperature heavily influences interatomic mixing.

Electroreduction of Copper Dichloride Powder to Copper Nanoparticles in an Ionic Liquid

There were a large number of ionic liquids electrodeposition reported in the literature; but were still in the laboratory stage some problems in the practical application of electrodeposition remain such as easily reacted with moisture in the air (AlCl3 ionic liquid), high cost, and corrosive (dialkylimidazolium cation and , ionic liquid). In addition to the above shortcomings, low solubility of many metal salts in ionic liquids limits the practical application. In order to solve the problem of low solubility, [Bmim]Cl could be added [Bmim]PF6, which could significantly increase the solubility of metal chlorides; this method could be commonly used in preparing metal electrochemical reduction of metal chlorides. Our study showed that adding cationic groups in hydroxyl ionic liquid could cause the good solubility of transition metal chlorides, such as CuCl2. Complexation of hydroxyl functional group and transition metal ions increased solubility, resulting in a larger deposition current density and surface electrochemical reduction of copper nanoparticles deposited on the metal Ni. The electroreduction mechanism and behavior of CuCl2 in hydroxyl ionic liquid and the Cu nanoparticle formation mechanism were investigated based on a comparison between similar experiments in the ionic liquid.

Mechanistic study of Al electrodeposition from EMIC–AlCl3 and BMIC–AlCl3 electrolytes at low temperature

Aluminum was electrodeposited from two different ionic liquid electrolytes namely; 1-ethyl-3-methylimidazolicum chloride and AlCl3 (EMIC–AlCl3) and 1-butyl-3-methylimidazolium chloride (BMIC–AlCl3) at 90 ± 2 °C. Nodular morphology of aluminum was obtained at the copper substrate. To evaluate the reaction mechanism, chronoamperometric study was adopted. From the chronoamperometric analysis, it was observed that the reaction was controlled by instantaneous three-dimensional diffusion process. The diffusion coefficient (D) of Al2C7− was found to be 5.2–6.6 × 10−11 m2 s−1 and 2.2 × 10−11 m2 s−1 for EMIC–AlCl3 and BMIC–AlCl3 ionic liquid electrolytes, respectively. The nuclei density of electrodeposited aluminum on the copper was also confirmed by scanning electron microscope wherein uniformly distributed aluminum nodules were observed.

The effect of electrode surface modification and cathode overpotential on deposit characteristics in aluminum electrorefining using EMIC–AlCl3 ionic liquid electrolyte

Abstract Electrorefining of aluminum alloy was investigated using AlCl 3 and 1-ethyl-3-methyl-imidazolium chloride (EMIC) (molar ratio AlCl 3 :EMIC = 1.65:1) ionic liquid electrolyte on copper and aluminum cathodes at temperature of 90 ± 3 °C and cell voltage of 1.5 V. The effect of electrode surface modification and cathode overpotential on deposit characteristics of aluminum was investigated. The surface modification of electrodes reduced the dendritic depositions of aluminum. It was also observed that cathodic overpotentials obtained from experiments using modified electrodes are significantly lower than those of unmodified electrodes. A non-dendritic deposit of aluminum was observed even after prolonged electrorefining of 25 h. Pure aluminum deposits were obtained for all experiments with the current efficiencies in the range of 94–99%.

Alkylation of isobutane and butene using chloroaluminate imidazolium ionic liquid as catalyst: Effect of organosulfur compound additive

Alkylation of isobutane and butene was carried out in a batch unit using 1-butyl-3-methylimidazolium chloride (BMIC)-aluminium (III) chloride (AlCl3) ionic liquid as catalyst. The effects of additives of butyl thioalcohol and ethyl thioether on the properties of ionic liquids for alkylation were investigated. Improvement of production distribution with high yields of isooctane and selectivity of TMP under a mild reaction condition was observed after addition of butyl thioalcohol. Moreover, the effects of operating variables were investigated and the mechanism was discussed.

Behavior of UO2 in a room-temperature ionic liquid in the presence of AlCl3

A study was made of interaction between AlCl3 and room-temperature ionic liquid (RTIL) [C8H15N2][N(SO2CF3)2], or BuEtIm-Tf2N, and of anodic dissolution in RTIL of UO2 and of a simulated oxide fuel at 297–302 K, depending on the AlCl3 concentration. It was shown that anodic dissolution of UO2 pellets and a UO2-Al mixture in RTIL yields soluble uranium species. Potentiostatic electrolysis of the resulting solutions can yield uranium compounds at the cathode, though with low current efficiencies. The role of AlCl3 in these processes was suggested. A heterophase reaction between UO2 and AlCl3 was studied, depending on the content of AlCl3 in solution. It was found that the exchange reaction products, soluble uranium species, are accumulated in solution only at the molar ratio AlCl3/Tf2N > 1.

Lewis Acidic Chloroaluminate Ionic Liquids: Novel Reaction Media for the Synthesis of 4-Chloropyrans.

1-n-Butyl-3-methylimidazolium chloroaluminate [bmim]Cl·AlCl3 (N = 0.56−0.67) ionic liquid has been employed as an alternative reaction medium to conventional acid catalysts for Prins cyclizations, to produce 4-chlorotetrahydropyran derivatives in excellent yields and in short reaction times. The ionic liquid plays a dual role as both catalyst and solvent, providing a rapid and efficient route to the synthesis of chlorotetrahydropyrans. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Lewis Acidic Chloroaluminate Ionic Liquids: Novel Reaction Media for the Synthesis of 4‐Chloropyrans

Abstract1‐n‐Butyl‐3‐methylimidazolium chloroaluminate [bmim]Cl·AlCl3 (N = 0.56−0.67) ionic liquid has been employed as an alternative reaction medium to conventional acid catalysts for Prins cyclizations, to produce 4‐chlorotetrahydropyran derivatives in excellent yields and in short reaction times. The ionic liquid plays a dual role as both catalyst and solvent, providing a rapid and efficient route to the synthesis of chlorotetrahydropyrans. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

A fast atom bombardment mass spectrometric study of room‐temperature 1‐ethyl‐3‐methylimidazolium chloroaluminate(III) ionic liquids. Evidence for the existence of the decachlorotrialuminate(III) anion

AbstractPrevious studies of 1‐ethyl‐3‐methylimidazolium chloride–aluminium(III) chloride ([emim]Cl–AlCl3) ionic liquids have been hampered by significant contamination of these liquids by oxide impurities. Treatment of these liquids with phosgene removes the oxide impurities, and the use of a specially constructed sample inlet system for air‐sensitive materials permitted them to be studied by fast atom bombardment mass spectrometry. The ions Cl−, [Cl2]−, [AlCl4]−, [Al2Cl7]−, [emim]+ and [(emim)2X]+ (X = Cl or AlCl4) were observed for the basic ionic liquid. In addition, the anion [Al3Cl10]− was observed for the acidic composition. Within the mass spectrometer, the hydrolyses of [Al3Cl10]− to produce [Al3Cl8O]− and of [Al2Cl7]− to produce [Al2Cl5O]− were observed. Comparison of these results with published 17O NMR data suggests that the primary hydrolysis products in acidic ionic liquids are [Al3Cl8O]− and [Al2Cl5O]− and that the principal secondary hydrolysis product is [Al2Cl6(OH)]−.

The structure of halogenometallate complexes dissolved in both basic and acidic room-temperature halogenoaluminate(III) ionic liquids, as determined by EXAFS

The salts [MeEtim]2[MCl4]([MeEtim]+= 1-methyl-3-ethylimidazolium; M = Mn, Co, or Ni) are shown by EXAFS to dissolve in basic [MeEtim]Cl–AlCl3 ionic liquids to yield four-co-ordinate [MCl4]2–, and to dissolve in acidic [MeEtim]Cl–AlCl3 ionic liquids to yield six-co-ordinate [M(AlCl4)3]– anions.