Trifluoroiodomethane Gas-phase Catalytic Synthesis

In this dissertation,a research has been made on the new gas-phase synthesis process of iodotrifluoromethane,the catalysis and reaction mechanism of this process,and the catalysis technique of this process.First,the new gas-phase synthesis process of iodotrifluoromethane is selected by thermodynamics calculation in which trifluoromethane,iodine and oxygen as raw materials, alkaline and alkaline earth metal salts as active components,active carbon and porous metal fluorides as carriers.By the one-way experiments,it is proved that the best result could be achieved with the temperature of 550 degree centigrade,vacant speed of 100h^-1～300h^-1and the weight proportion is 12 to 4 to 1 among CHF₃,I₂ and O₂.Second,the reaction and catalysis mechanism of this process is studied by comparing R23 hydrogenation with R22 hydrogenation and theory analysis.A consideration of the reaction mechanism suggests that the reaction proceeds via CF₂ carbenes as intermediates formed by removing HF from CF₃H,followed by carbene disproportionation to CF₃ radicals,followed by reaction with I₂ to give CF₃I.A possible catalysis mechanism is as follows:The intensities of C—H and C—F bonds are weakened by active components;The catalysis activities of active components are relative to electronegation of ions;In the induction period of the initial start up,the generated CF₂ carbenes possibly cumulate on the surface of catalyst.At last,the catalysts are charactered by BET,XRD,Tg-DSC,EDS,XPS and some catalysis laws are achieved by one-way experiments.Alkaline metal salts are more suited for active components;Among the alkaline metal salts with the same anion,the activity order is Rb＞Cs＞K;Among the alkaline metal salts with the same cation,the activity order is nitrate＞halide with F＞Cl＞Br;Carbon carriers have the larger surface area,but they could react with O₂ and active components on them could be blown away easily;Compared with carbon carriers,Porous metal fluorides have the opposite characters.