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1.
Activity data for NaCl, AlCl3 and NaAlCl4 in basic NaClAlCl3 melts are derived from emf measurements. Literature values for the total vapour pressure are interpreted in terms of partial pressures of the gaseous species AlCl3, Al2Cl6, and NaAlCl4. A possible contribution of small amounts of the dimer Na2Al2Cl8(g) is discussed. Thermodynamic data are derived for the molten mixture and for the corresponding vapour phase. Interaction between the melts and silica or alumina container materials is considered. 相似文献
2.
Mark A. Plummer 《Fuel Processing Technology》1985,11(3):313-323
Sodium and hydrogen tetrachloroaluminates (NaAlCl4 and HAlCl4) have been evaluated as catalysts for the molecular weight reduction of hydrocarbons. The NaAlCl4 is the major molecular weight reduction and synthesis component, and HAlCl4 adds a hydrogenation function. The optimum catalyst composition, for the petroleum AC-20 resid and shale oil feeds studied, was found to be 2.5–4.5 wt.% HAlCl4 in NaAlCl4. To convert these feeds completely into gasoline range materials, a hydrogen partial pressure and a hydrogen consumption of 950 psia and 900 scf/bbl, respectively, are estimated to be required. About 40% of the hydrogen consumption would be for contaminant removal. Above a hydrogen partial pressure of about 450 psia, the liquid products produced contained less than 100 ppm each of sulfur and nitrogen contaminants. The C6C13 molecular weight portion of the liquid products contained about 55% aromatics, 8% naphthenes, 33% branched paraffins and 4% normal paraffins (weight basis). 相似文献
3.
Jai Prakash Laszlo Redey Donald R. Vissers James DeGruson 《Journal of Applied Electrochemistry》2000,30(11):1229-1233
The effect of sodium iodide and sulfur additives on the performance of Na/-alumina/NaAlCl4/NiCl2/Ni cells was investigated in quasi-sealed laboratory research cells (0.5–1.0 Ah capacity) and in sealed full-size cells (4 Ah capacity). It was found that sodium iodide additive especially in combination with sulfur in Na/NiCl2 cells significantly increases the usable capacity and reduces the impedance of the Na/NiCl2 cells. It is proposed that the use of sodium iodide enhances the energy and power performance of the NiCl2 electrode by two different mechanisms. The first mechanism, iodide ion doping of the anodically formed solid NiCl2, is dominant at potentials lower than that of iodine evolution. The doping effect of the iodide ions produces a higher-capacity, lower-impedance NiCl2 layer on the positive electrode. The second mechanism, anodic formation of very reactive iodine species, is effective when the cell is cycled through the iodine evolution potential range (2.8–3.1 V vs Na). During this process, the dissolved iodine species improve electrode kinetics through liquid-phase mass transport. Use of the sodium iodide additive is safe in sealed cells, causing no over-pressurizing problems. A maximum pressure increase of only 10 kPa was detected by a pressure sensor during severe overcharge tests. 相似文献
4.
《国际聚合物材料杂志》2012,61(1-2):101-107
Abstract The authors experimentally investigated pyrolysis of model vulcanized butadiene compounds with different sulphur content on the melt of NaAlCl4. The maximum yield of liquid pyrolysis products occurs at 400°C, and is independent on S content. There was also observed strong desulphurization of liquid products, due to removal of S with the pyrolysis gases in the form of H2S. On the basis of same experiments on desulphurization of model mixture C16H34S with C15H32 with the same catalyst was proposed possible mechanism of S removal through the formation of stable complexes. 相似文献
5.
Zhigang Xie Qiushi Song Hongwei Xie Huayi Yin Zhiqiang Ning 《Journal of the American Ceramic Society》2021,104(2):753-765
Surface doping of Li4Ti5O12 (LTO) with Ti3+ ions is an effective way to enhance its electrochemical properties for lithium ion batteries (LIBs). Herein, a molten salt approach was reported to synthesize Ti3+ self-doped LTO powder. The reaction mechanism and the role of molten salt for the synthesis have been systemically discussed. Finally, electrochemical performance of the LTO powder was preliminarily evaluated as anode material of LIBs. The molten salt accelerated the mass transportation for the formation of LTO by transferring a solid diffusion to the diffusion of ions in a liquid media. Self-doping of Ti3+ ions on the surface of LTO particles was achieved by controlling equilibriums of chemical reactions in the reactor. Electrochemical performance of the LTO powders was effectively promoted by doping Ti3+ ions on the surface. The discharge capacity of the Ti3+ self-doped LTO powder prepared at 850°C was 171 mAhg−1, and the capacity dacayed 9.9% after 200 cycles at a rate of 0.5 C. 相似文献
6.
Sodium metal can be produced at low temperatures (523 K) by electrolysis of sodium tetrachloroaluminate (NaAlCl4) in a cell, which employs sodium ion conducting beta-alumina as diaphragm. A laboratory-scale electrolytic cell and associated systems were designed and constructed to study the various aspects of the energy efficient process. Graphite/reticulated vitreous carbon (RVC) was used as the anode and molten sodium as the cathode. Electrolysis was carried out at 523 K with currents in the range 1–10 A (10–125 mA cm–2). The cathodic current efficiency was close to 100%, but the anodic current efficiency was very low (20–30%), probably due to the consumption of chlorine in the intercalation reaction of graphite and aluminium chloride. The sodium metal was analysed by AAS and found to have 5N purity. On prolonged electrolysis, the graphite anode disintegrated due to the formation of graphite intercalation compounds. RVC behaved as a better chlorine-evolving anode in the initial period of electrolysis, but its ability for chlorine evolution decreased on continuous electrolysis. The study indicated the need for effective stirring of the electrolyte with excess NaCl to avoid build up of aluminium chloride and the resultant complications in the cell. 相似文献
7.
Béatrice Garcia Serge Lavallée Gérald Perron Christophe Michot Michel Armand 《Electrochimica acta》2004,49(26):4583-4588
In the present study, are reported investigations obtained with the room temperature molten salt (RTMS) ethyl-methyl-imidazolium bis-(trifluoromethanesulfonyl)-imide (EMI-TFSI) in order to use it as solvent in lithium battery. The thermal stability, viscosity, conductivity and electrochemical properties are presented. A solution of 1m lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) in EMI-TFSI has been used to test the electrolyte in a battery with LiCoO2 and Li4Ti5O12 as respectively cathode and anode materials. Cycling and power measurements have been obtained. The results have been compared with those obtained with a molten salt formulated with a different anion, BF4− and with a conventional liquid organic solvent EC/DMC containing LiTFSI. The 1m LiTFSI/EMI-TFSI electrolyte provides the best cycling performance: a capacity up to 106 mAh g−1 is still delivered after 200 cycles, with 1C rate at 25 °C. 相似文献
8.
Spinel LiMn2O4 is a promising cathode due to its advantages of low-cost, nontoxicity and thermal stability. However, the dissolution of manganese and the phase transformation induce the rapid capacity fade. Surface coating is an effective method to improve its electrochemical performance. In this work, spinel LiMn2O4 modified with perovskite LaCoO3 was prepared using a novel molten salt method. The resulted samples were characterized by X-ray diffraction (XRD), transmission/scanning electron microscopy (TEM/SEM), Fourier transformation infrared (FT-IR), Raman, and X-ray photoelectronic spectroscopy. The content of Mn3+ increased with the LaCoO3 coating accompanied by the increased concentration of oxygen vacancy. LiMn2O4 modified with 2% LaCoO3 shows a higher capacity and cycling stability than others at 0.2 C, while the cathode with 4% LaCoO3 shows the best rate performance at a larger current at 2 and 5 C. This enhanced performance can be attributed to improved interfacial conductivity between the cathode and electrolyte and the protective effects of coating. 相似文献
9.
The solubility and the polymerization of polyacrylonitrile in low‐temperature molten salts was investigated. It was found, that the polymer dissolves in eutectic mixtures of molten sodium thiocyanate and potassium thiocyanate (NaSCN/KSCN) as well as in the molten hydrate lithium perchlorate (LiClO4*3H2O). The polymer can be regenerated by cooling the melt or diluting with water. The chemical interaction between the molten salt and the polymer was investigated by 13C‐NMR spectroscopy. These measurements show that the dissolution of the polymer in molten KSCN/NaSCN is accompanied by the splitting of the the hydrogen bonds. Starting from acrylonitrile, the formation of polyacrylonitrile by a radical polymerization in a molten salt becomes successful. The polymerization of acrylonitrile in an eutectic mixture of KSCN/NaSCN results in the formation of atactic polyacrylonitrile with high molecular weight. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2113–2117, 2000 相似文献
10.
Jinguang Yang Ping Wu Li Wang Shiping Zhang Dan Yan Ya-nan Li 《Journal of the American Ceramic Society》2022,105(9):5627-5637
The melt of silicon, hindering nitridation for its agglomeration, should be avoided in the direct nitridation of silicon to synthesize silicon nitride powders, although liquid phase facilitates nitridation. Therefore, we proposed a method to nitride molten silicon without agglomeration. Thermogravimetric and in situ Raman studies on the nitridation process of molten silicon were performed. The as-prepared silicon nitride samples were found to be micron clusters composed of submicron grains with high α-Si3N4 content. The nitridation of molten silicon at 1500°C was completed after 500 s and 109 times faster than the nitridation of solid silicon at 1350°C. β-Si3N4 is produced dominantly by α–β-phase transition. Less nitridation time and low temperature can decrease the β-Si3N4 content. The rapid nitridation was owning to core–shell structure Si@Si3N4, which was formed after the initial nitridation of silicon particles and hindered the agglomeration of molten silicon. 相似文献
11.
Tao Wang Weihui Jiang Jianmin Liu Guo Feng Lifeng Miao Ting Chen Qian Wu 《Ceramics International》2019,45(4):4514-4519
High quality zirconia whiskers have been successfully prepared by molten salt method, using zirconium oxychloride (ZrOCl2·8H2O) and sodium phosphate tribasic dodecahydrate (Na3PO4·12H2O) as precursor and molten salt, respectively. The effects of types of molten salt and heat treatment temperature on the formation of zirconia whiskers were characterized by XRD, Raman, DTA-TG, FE-SEM, TEM, SAED and HR-TEM. When Na3PO4·12H2O is utilized as molten salt and the heat treatment temperature is 900?°C, the as-prepared zirconia whiskers with length ranging from 4?µm to 8?µm show an average aspect ratio of 25. The obtained ZrO2 whiskers with monoclinic structure are elongated along [010] direction and exhibit a smooth surface with no distinct defects. The XRD and Raman results reveal that the phase transformation from tetragonal zirconia to monoclinic zirconia occurs with the increased crystal size and the water quenching treatment can significantly reduce the content of sodium zirconium phosphate [Na9–4×Zrx(PO4)3] in the final product. The growth mechanism of zirconia whiskers is supposed to be a dissolution-precipitation process. Since the sodium zirconium phosphate [Na9–4×Zrx(PO4)3] effectively promotes the dissolution of zirconia in liquid molten salt, zirconia can grow into zirconia whiskers according to its anisotropy. 相似文献
12.
《Ceramics International》2022,48(17):24471-24475
Al2O3–SiC composite powder (ASCP) was successfully synthesized using a novel molten-salt-assisted aluminum/carbothermal reduction (MS-ACTR) method with silica fume, aluminum powder, and carbon black as raw materials; NaCl–KCl was used as the molten salt medium. The effects of the synthesis temperature and salt-reactant ratio on the phase composition and microstructure were investigated. The results showed that the Al2O3–SiC content increased with an increase in molten salt temperature, and the salt–reactant ratio in the range of 1.5:1–2.5:1 had an impact on the fabrication of ASCP. The optimum condition for synthesizing ASCP from NaCl–KCl molten salt consisted of maintaining the temperature at 1573 K for 4 h. The chemical reaction thermodynamics and growth mechanism indicate that the molten salt plays an important role in the formation of SiC whiskers by following the vapor-solid growth mode in the MS-ACTR treatment. This study demonstrates that the addition of molten salt as a reaction medium is a promising approach for synthesizing high-melting-point composite powders at low temperatures. 相似文献
13.
Hierarchical Co3O4 nanostructure is synthesized via a self-assembled process in molten hydroxides. The morphologies, crystal structures and the phase transformation processes are analyzed by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. As an anode material for lithium ion batteries, the hierarchical Co3O4 exhibit an initial capacity of 1336 mAh g−1 and a stable capacity of 680 mAh g−1 over 50 cycles. More importantly, high rate capability is obtained at different current densities between 140 and 1120 mA g−1. The improved electrochemical performance of Co3O4 could be attributed to the unique hierarchical nanostructure. 相似文献
14.
《Ceramics International》2017,43(10):7531-7536
Ultrasound-assisted dipping of ZrO2 ceramics into molten Sn solder was performed to realize the low-temperature joining of ZrO2 ceramics in this study. Scanning electron microscopy with energy dispersive spectrometer, X-ray diffraction and X-ray photoelectron spectroscopy were employed to study the effects of ultrasonic vibration on the microstructure of Sn/ZrO2 interface, and to elucidate the joining mechanism between Sn coating layer and ZrO2 ceramic. Results showed that, after ultrasonically dipping in molten Sn for 1200 s, a pure Sn solder layer with a thickness of approximately 8–9 µm was coated on the ZrO2 surface. The Sn coating layer exhibited excellent metallurgic bonding with ZrO2 ceramic. A nano-sized ZrSnO4 ternary phase, which was beneficial to the smooth transition of the lattice from Sn solder to ZrO2 ceramic, was formed at the Sn/ZrO2 interface. The formation of ZrSnO4 interlayer was ascribed to the acoustic cavitation induced high-temperature reaction of Sn, O and ZrO2 at the molten Sn/ZrO2 ceramic interface. The tested average shear strength of ZrO2/Sn/ZrO2 joints was approximately 32 MPa, and the shearing failure mainly took place within the Sn solder layer. 相似文献
15.
《Electrochimica acta》1986,31(9):1117-1123
Solid AgIAgIO3 and AgIAg3AsO4 of various compositions were investigated by conductivity, thermal and electrochemical methods. Both systems show dependences on composition and temperature enabling determination of the activation energy of conductivity. Glassy phases are formed at appropriate rates of cooling of molten samples. By thermal analysis (DSC), the glass transition and crystallization processes of the glassy phases were identified. Processes of anodic and cathodic decomposition of the electrolyte were investigated. The energy of activation for the cathodic redox (Ag+ → Ag) process was determined. It was also shown how the capacity of the Pt/electrolyte phase boundary depends on the dc potential and ac frequency. 相似文献
16.
《Ceramics International》2022,48(22):32798-32803
In this paper, copper-loaded antibacterial glasses were prepared by an ion-exchange method with CuSO4 or CuCl as copper sources. The effects of different molten salts and ion exchange duration on the antibacterial properties of copper-loaded glasses were investigated. The experimental results show that the glasses exchanged with CuSO4/Na2SO4 mixed molten salts have a higher surface copper loading than that with CuCl/KCl mixed molten salts. The sample color results from the reduced Cu0. The equilibrium between Cu+ and Cu0 is related to the Sn2+ ions existed in the lower surface of float glass. Finally, the antibacterial function of glass samples was found to be related to the charge transfer between Cu++e??Cu0, and has a proportional correlation with the content of Cu+ ions on the glass surface. 相似文献
17.
Anugraha Thyagatur Ruchi Gakhar Dev Chidambaram Pattrick Calderoni Michael Buric Leslie T. Mushongera 《Journal of the American Ceramic Society》2022,105(5):3647-3653
The continued development of molten salt reactors and concentrated solar power plants requires highly efficient and stable instruments that can efficiently monitor the chemical conditions of the molten salt during long-term operation in both the fuel and coolant/heat transfer fluid loops. Sapphire (Al2O3) fibers have shown tremendous potential due to inherent radiation resistance and a broader operational range of temperature. In this work, computational thermodynamic modeling (CALPHAD) using the ThermoCalc software in conjunction with the SGTE (Scientific Group Thermodata Europe) Molten Salts (SALT1) and Pure Substances (Pure5) databases is applied to understand the compatibility of Al2O3 fibers with NaCl-MgCl2 eutectic molten salt in the temperature range of 1500–2500 K. The thermodynamic calculations show that sapphire fibers are not expected to be stable over the long-term when exposed to molten chloride salts at these temperatures. To improve the stability of these diagnostic fibers in molten salt environments, various pure metallic elements were evaluated as potential cladding materials for Al2O3 fibers. Based on the thermodynamic analysis, molybdenum (Mo) and nickel (Ni) could be effective cladding materials to enhance the stability of Al2O3 in NaCl-MgCl2 chloride salt molten bath in the desired temperature range. Thus, the presence of Mo and Ni cladding can provide a protective coating against the corrosive molten salts, thus improving the stability of Al2O3. Additionally, it is also shown that Al2O3 remains stable up to 2400 K in the presence of preexisting Al2MgO4 and Al2NiO4 in the eutectic molten chloride bath environment. 相似文献
18.
Yuxuan He Xu Wang Chao Wang Shiying Liu Liuyuan Li Yusheng Wu Zhanjie Wang 《Journal of the American Ceramic Society》2023,106(5):2744-2751
To improve the ability of rare-earth (RE) silicates to resist molten calcium–magnesium–aluminosilicate (CMAS) at high temperature, a novel high-entropy (4RE0.25)2Si2O7/(4RE0.25)2SiO5 (RE = Y, Yb, Er, and Sc) multiphase ceramic was prepared by a two-step process. During sintering, (4RE0.25)2SiO5 can react with SiO2 at the grain boundaries of (4RE0.25)2Si2O7, which can not only purify the grain boundary but also promote the growth of the original (4RE0.25)2Si2O7 grains, thereby significantly improving the ability to resist molten CMAS corrosion at high temperature. After corroding at 1500°C for 48 h, the reaction layer of the multiphase ceramic was only 55 μm thick. Our results confirm that the high-entropy RE silicate multiphase ceramics represent an effective way to improve the ability to resist molten CMAS corrosion at high temperature. 相似文献
19.
Seok Kim 《Electrochimica acta》2009,54(14):3775-1117
The effects of room-temperature molten salt addition on the micro-structure and electrochemical properties of composite electrolytes (CEs) based on poly(ethylene oxide) (PEO)/ethylene carbonate (EC)/LiBF4 were studied. Additional salt, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4), was found to influence the crystalline structure and heterogeneous morphology, resulting in changes to the ionic conductivity of the CE. The CE containing 0.2 mol of EMIBF4 showed a small crystallinity, 27.9%. These CEs showed the highest ion conductivity, 3.1 × 10−4 S/cm, five times higher than that of the pristine PEO/EC/LiBF4. This enhanced conductivity originated from the decreased crystallinity and improved ion transference due to a Lewis acid-base interaction. The CE containing 0.3 mol of EMIBF4 showed decreased conductivity due to the lower mobility, reflecting the high viscosity of the molten salt. 相似文献
20.
Synthesis of Anisotropic Na0.5Bi0.5TiO3 Crystals Using Different Topochemical Microcrystal Conversion Methods
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Wei Zhao Nianqi Liu Kexin Gao Zihao Wang Shimeng Zhang 《International Journal of Applied Ceramic Technology》2016,13(5):871-875
Na0.5Bi0.5TiO3 (NBT) platelets with high aspect ratio were synthesized from Na0.5Bi4.5Ti4O15 (NBIT) precursors via a topochemical microcrystal conversion in molten salt conditions. The effect of the synthesis parameters, such as the molten salt system, synthesis temperature, and the molar ratio of Na2CO3 and NBIT, was investigated. The results showed that NaCl–KCl molten salt environment and excess Na2CO3 played a positive role in the synthesis, square‐shaped NBT was obtained at 950°C in NaCl–KCl molten salt and a TiO2‐free environment, and it was a suitable template candidate to achieve NBT‐based textured ceramics using the reactive template grain growth (RTGG) method. 相似文献