Study On Gas-phase Catalytic Synthesis Technology Of Pentafluoroethyliodide

A novel process route of gas phase catalytic synthesis on pentafluoroethyl iodide was put forward on the basis of former research. The experiment research plat was designed.The research was made on process condition and catalytic technique, moreover, the catalytic and reaction mechanism of this process was simplely speluated in this paper.The novel process of continal one-step gas phase catalytic synthesis on pentafluoroethyl iodide which is pentafluoroethane, iodine and oxygen as raw materials, alkaline and alkaline earth metal salts as active components, active carbon and porous metal fluorides as carriers was designed. The result of thermodynamics calculation and feasibility test revealed pentafluoroethyl iodide was gained with high yield on this novel synthesis process. The influence laws of calcinations temperature, velocity and weight proportion on catalytic performance were also studied. The results revealed that these process conditions had important effects on the catalytic performance. The fitting process condition: the reactive temperature is 550℃-600℃, the velocity is 70h^-1-106h^-1, the weight proportion is 20 to 3 among C₂F₅H and O₂.The specific area, surface morphology, surface elements and thermal decomposition were analyzed by BET, XRD, EDS, Tg-DTA method. The catalysis laws of reaction system were studied through one-way experiments, the results indicated that Alkaline metal salts are more suited for active components; the activity order for the cation is Rb⁺＞K⁺＞Ba²⁺＞Cs⁺＞Mg²⁺; the activity order for the anion is nitrate＞fluorid; the fitting loading of active components is 15%-20%; catalytic performance of AC was made from coconut shell is the highest .The stabality of the catalyst was investigated, the result showed that the life of catalyst is very short. the main reason of deactivation is high-temperature oxidation,carbon deposition,active components are los,catalyst poisioning.Increaseing basicity can improve catalyst performance. penafluoroethyl iodide is easy to pyrolyze with resultant CF₃I and some by-products. the possible mechanism is the reaction proceeds via CF₂: carbenes as intermediates formed by removing HF from C₂F₅H, followed by carbene disproportionation to CF₃ radicals, finally pentafluoroethyl iodide is generated through addition and iodination reaction on CF₂:. CF₃·and I·.