| CF3I has potential applications in replacement of Halon extinguishing agents and refrigerants due to its low GWP value and low ODP value. Current methods do not seem likely candidates for large-scale production of CF3I due to the low yield and batch processes. In this dissertation, a continuous vapor-phase catalytic process for preparation of CF3I was studied, especially in the reaction mechanism, process conditions and catalytic technique.According to the Gibbs free energy, the reaction between CHF3 with I2 in the presence of O2 is an appropriate synthetic route. Over an experimental line system, CHF3,I2 vapor and O2 were mixed and fed into the reactor at 550℃, then the producted was collected and analyze by GC-MS, GC and FTIR. It was found that CF3I can be synthesis by this method.H2 or 2-methyl-2-butene, as capture agent, was fed into reactor with CHF3 over catalysts or non-catalyst. And the intermediate absorbed on the surface was conducted pyrolysis reaction and hydrogenation reaction. It was found that in pyrolysis of CHF3 through empty reactor in the presence of H2, CH2F2 was obtained via the reaction of CF2 carbene with H2. But over AC, the formed CF2 carbene was adsorbed on the surface of AC. the CF2 carbene intermediate can not be trapped by H2,2-methyl-2-butene and CF2 carbene itself. CF2 carbene takes plcae disproportionation reaction takes place to generate CF3 radical. CF3 radical reacts with I2 to form CF3I, whereas with H radical to form CHF3. CF3 radical reacts with CF2 carbene to form CF3CF2 radical, which generates CF3CF2I and CF3CHF2. When CHF2Cl and hexafluoropropylene oxide (HFPO), as other CF2 carbene sources, were conducted the same reactions over AC or porous AlF3 (PAF), the similar products were detected. It was indicated that under experimental conditions, CF3 radical generation associated only with the intermediate CF2 carbene. CF2 carbene disproportionation took palce over AC or PAF. It was verified that the reaction mechanism was CF2 carbene disproportionation by experimental means.To check the above mechanism, the software of Material Studio was used to simulate the reaction process and a low temperature catalytic reaction for CF3I synthesis was conducted. Calculation results showed that CF2 carbene was strongly combined with AC and reacted with conjugatedπbond to form difluoro-cyclopropane compound. Between two closed CF2 carbene, one F atom of one CF2 carbene will close to the C atom of the other CF2 carbene to form CF3 group. The adsorption energy of CF2 carbene with AC was-36.32 kcal/mol and activated energy of two steps of disproportionation reaction were 36.4kcal/mol and 42.1kcal/mol, respectively. Through the simulation, it is indicated that CF2 carbene can adsorb on the surface of AC and take palce disproportionation reaction to generate CF3 group. It was in accordance with experimental results. When HFPO reacted with I2 over KF/AC catalyst at 170℃, CF3I was generated. When reaction temperature was increased to 200℃and hold for 2h, the conversion of HFPO reached 99%,. Calculation results and CF3I synthesis via HFPO showed that the reaction mechanism is positive.Based on mechanism above, the reaction conditions were optimized. The appropriate reation temperature was 550℃.and the appropriate space velocity was 300h-1. The optimized amount of raw materials was CHF3:36ml/min, I2:8.2g/h and O2:3ml/min (catalyst volume was 16ml)To increase the conversion of CHF3 and prolong catalyst life, the catalytic technique of this catalytic reaction for CF3I synthesis was investigated, including activated substances supporters. It was found that alkali metal salts showed a higher catalytic activity than the alkaline earth metal salts. AC, as the catalytic supporter, showed higher activity due to its high surface area. Porous metal fluoride, such as porous aluminum fluoride and porous magnesium fluoride, as carriers showed medium activity and stable properties in the presence of O2 and HF. So, Porous metal fluoride processed industrial potential application as carrier for this reaction. Under optimized conditions, the catalyst life of RbNO3-KF/AC increased and reached 120h.
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