Study On The Synthesis Of Hexafluoroisopropanol

Hexafluoroisopropanol (HFIP) could be used in the preparation of fluorinated surfactant, fluorinated emulsifier, fluorine-containing medicine and many other kinds of chemicals. And it is also a good solvent and advanced cleaner. So, hexafluoroisopropanol is a kind of fluorinated alcohol with great value in application.The preparation of hexafluoroacetone was studied as well as its hydrogenated process to form hexafluoroisopropanol in this paper. Hexafluoroacetone was prepared by rearrangement reaction from hexafluoropropeneoxide in the presence of catalyst. In this paper, a series of research was taken to study the activity and lifetime of different rearrangement catalysts, and to obtain the optimized temperature, space velocity, and other conditions of the reaction. The results show that at the temperature of60℃and space velocity of228h-1, catalyst C15-3performed best with high activity and good stability.Liquid-phase hydrogenation and gas-phase hydrogenation were two methods to form hexafluoroisopropanol from hexafluoroacetone. And they were studied respectively to find out their feasibility and process conditions. For the liquid-phase hydrogenation, the effect of different catalysts and there dosage, reaction temperature and pressure, monomer concentration on the reaction rate, conversion rate and product selectivity was studied. The reaction taken at the temperature of100℃and at the pressure of0.8MPa with the catalyst of5%Ru/C was considered to be the optimal process and the conversion rate was up to98.62%. The reuse of catalyst was feasible and the purification of product was taken by reaction of the product with hydrazine hydrate and then rectification. For the gas-phase hydrogenation, the efficiency, lifetime and stability of different catalysts for the reaction was studied and the best one was selected for further research, including the effect of reaction temperature, vaporization temperature, space velocity and feed ratio of reactants. The results showed that at the reaction temperature of110-140℃and vaporization temperature of120-140℃, the catalyst had good activity and stability with the space velocity less than0.2h-1(liquid phase) and n(H2):n(HFA-3H2O) larger than2. The conversion rate and product selectivity are both above99%. According to the parameters of the studies above, a device to produce300tons of hexafluoroisopropanol per year process was set up and succeeded in test for the first time and the production capacity meet the design requirements. The average conversion rate of hexafluoroacetone hydrate was greater than98%, while the selectivity of hexafluoroisopropanol greater than99%, and the catalyst efficiency greater than200gHFIP/gCat.