Studies On Thermodynamics And Synthesis Of Rhenium Ionic Liquids By Solvent Extraction Method

Rhenium is one kind of refractory metal, which becomes a part of the newmaterials in high-tech field. Rhenium and its alloy are widely used in thepetrochemical industry, electronic industry and aerospace application and so on.Solvent extraction is one of the best methods of separation rhenium, tested by a massof experimental research, owing to its special scattered existence characterization.This method only needs simple equipments, and always performs in roomtemperature or low temperature with simple operation process. This method is easy toachieve the mass production, which plays the important role in industry developmentand environment protection.This paper reports the thermodynamics of extracting Re（Ⅶ） with the extractant[Cnmim]Br in neutral system. The standard equilibrium constants at varioustemperatures were obtained by linear extrapolation with Debye-Hückel equation, inthe conditions of the same amounts of ReO₄-and metal ionic, and ionic strengthschanging from0.1to2.0mol·kg-1in the organic phase at temperatures from278.15to303.15K. Then the others thermodynamic quantities in the extraction process arecalculated.The ionic liquid containing perrhenate HN(C₈H₁₇)₃ReO₄is synthesized bysolvent extraction method. This reaction is one-step synthesis with simple processand the product is easy to separate, which occurs in room temperature. Densities andsurface tension of the IL are measured at the same temperature range. The relativeproperty values of the IL are calculated using Glasser theory and Kabo experientialequation. The coefficient of thermal expansion of the IL is also estimated, which ingood agreement with the experimental one, and then verifies authenticity of theinterstice model.The cyclooctene epoxidatiom system is established, which cyclooctene issubstrate, UHP is oxidant, ionic liquid is used as catalyst and solvent. The bestreaction condition is determined by single factor experiments: the amount ofcyclooctene is1mmol, the amount of UHP is4mmol, the amount of ionic liquids is 0.4mL and reaction time is30h at temperature70°C. The yield is99.21%with highselectivity, and no by-products is generated during the process.In this paper, rhenium ionic liquid is directly synthesized from inorganic phaseby solvent extraction method. The thermodynamic quantities of the extraction processare obtained. The physical-chemical properties of the IL are also calculated andestimated by semi-empirical methods. The rhenium ionic liquid is used as catalystand solvent in cyclooctene epoxidation system and the optimization of conditions areobtained, which supports the theory of scatterred metals, develops the application ofscattered metal ionic liquids.