Study On The Synthetic Technology Of HFC-125/HCFC-124 And Its Industrialization

Chlorofluorocarbons (CFCs) were widely used as refrigerants, blowing agents, propellants in medicinal applications, and degreasing solvents. Since the late 1970s, the use of CFCs has been heavily regulated because of their destructive effects on the ozone layer, as well as contribution to global warming. Work on alternatives for CFCs began in the late 1970s after the first warnings of damage to stratospheric ozone were published. HFC-125 (CF3CHF2) has been generally accepted as a promising and environmental-friendly CFC-12 (CCl2F2).Based on the successful pilot test of 100t/a HFC-125 with self-owned intellectual property, the jointly technology of 3000 t/a HFC-125 and HCFC-124 and its industrialization were studied in this dissertation. A series of core technologys, including the synthesis of target product, the recovery of by-product, dry separation of products, the consumptions of staring materials and energy, and the selection of material for manufacturing plants were investigated systematically. The optimized reaction condition provides a basis for the scaled-up production of HFC-125. The technological processes were list as follows in detail.Firstly, the combinations of HFC-125 and HCFC-124 in different proportions were obtained, tarring from HCFC-123 and AHF, catalyzed by Cr2O3/AlF3 solid-phase catayst, via two-step substitution. The target product HFC-125 was obtained after washing, distillation and drying. The results showed that the improvement of pressure and the ratio of AHF to HCFC-123 could suppress the formation of impurities. Meanwhile, below 319 C, the improvement of reaction temperature could also suppress the side-reaction.Additionally, the recovery of by-products and the removing of olefin in starting material were also investigated. The side-products such as HCFC-133a, CFC-114a and CFC-115 could be recovered. The usages of residual heat and cold were also investigated, which could improve the safety, environment-protection and energy-saving of manufacturing plants. Moreover, the recovery of starting material was is greatly enhanced and other loads such as drying and compression significantly reduced, after the dry separation process of HF was employed.