Study On Ferrocene Sublimation Process

Ferrocene,sandwich compound,is made up of two cyclopentadienes base anion and a Bivalent iron cationic, and has a wide range of applications in many fields.At present industry, the commonly used method is steam distillation for the purification of ferrocene, with the advantages of simple equipments, high purity products,deficiency is that we need liquid-solid separation and drying to obtain the solid products,and with its complex process, high energy consumption, many "three wastes" emissions.The sublimation purification method can directly obtain ferrocene products, low energy consumption, and this process does not produce waste gases and water. Research and development in this sublimation purification processes have important economic benefits and environmental benefits.(1)The thermal behaviour of ferrocene samples was investigated by nonisothemal and isothermal thermogravimetric methods in a high pure nitrogen atmosphere.Isothemal TG indicates that ferrocene purity sublimates in the zero-order process.The calculation of activation energy of the isothermal sublimation process was carried out in the temperature of 125-165℃.The nonisothermal sublimation activation energy values determined following the procedures of Arrhenius,Kissinger and Ozawa,for the purity ferrocene and the ferrocene raw material,we can obtain77.2,78.7,83.1,96.4,82.2,and88. 1kJ/mol, respectively.the isothermal sublimation activation erengy was found to be 67.1kJ/mol over the temperature 125-165 ℃.For ferrocene purity,analysis of the experimental results suggested that the isothermal sublimation activation energies are in best agreement with the activation obtained from Arrhenius method at the lowest heating rate.The activation energy values obtained from the nonisothermal experiments are in good agreed with those values computed using the procedures of Arrhenius and Kissinger methods.(2) The impact about heating temperature, inert particles and nitrogen on the yield and purity were studied in the sublimation process.The research shows that ferrocene purity can reach more than 99% while sublimation temperature is below 160℃, and with the temperature upon 160℃, the purity decreases. During the process of sublimation, clumps produced have an significant influence on product yield. Reducing or destroying clumps help improving ferrocene yield.Inert particle has no inflence on the purity of ferrocene, but can enhance the heat and mass transfer, disperse material and reduce clumps size, which improves ferrocene yield. Nitrogen access can accelerate the sublimation of ferrocene, but the ferrocene purity is declined due to the entrained solid impurities.