The method of obtaining pentafluoroethane
(57) Abstract:The invention relates to a method for Pentafluoroethane containing 1-chloro-Pentafluoroethane less than 0.02 percent by weight. Pentaverate get the conversion process tetrafluorochloroethane CF3CHClF in the gas phase in the presence of a chromium oxide catalyst (Cr2O3) supported on a carrier, including AlF3to release it from the product received. And said media has a fluorine content corresponding to at least 90% AlF3with respect to the total weight of the carrier. The process is carried out at 140 to 300°C and a contact time of 0.1 - 30,0 C. the result is pentaverate small quantities of 1-chloro-Pentafluoroethane. 6 C.p. f-crystals. The invention relates to a method for Pentafluoroethane.This particularly applies to the production method of Pentafluoroethane containing very low amounts of 1-chloro-Pentafluoroethane, usually lower than 0.02% by weight, most preferably lower than 0.01%.It is well known that the fluorocarbons containing chlorine, the so-called chlorofluorocarbons, can no longer be used according to the international rules, as they have a negative vsevolodov currently we mean cooling of the mixture, the use of foam and spray agents, where the chlorofluorocarbons used separately or in mixtures with other, attempts are being made to find substitutes that do not contain chlorine or chlorine simultaneously with the hydrogen atoms in the molecule, the so-called fluorocarbons and chlorofluorocarbons, respectively.One of the deputies of chlorofluorocarbons, which is used in cooling the mixtures, the so-called pentaborate is ftoruglevodorodnye.In the literature there are various ways to obtain Pentafluoroethane, however, that due to industrial equipment, there is a simplified process that combines high outputs with low amounts of undesirable compounds, such as, for example, chlorpropramide, which are formed as by-products of the reaction and must be removed from Pentafluoroethane.You must know that if by-products are easily separated, and no problems arise from the production point of view after is suitable destinationa column, attached to the main equipment production Pentafluoroethane.You need a warning that applied for the possession of 1-chloro-Pentafluoroethane, usually about 100 ppm (0.01 percent). See, for example, EP patent 612709.Separation of 1-chloro-Pentafluoroethane from Pentafluoroethane fractional distillation is extremely difficult, and the purity specified in the aforementioned European patent, it is almost impossible to obtain in the production facilities. See, for example, US patent 5087329. This patent also describes the distillation can separate 1-chloro-pentaverate from Pentafluoroethane of a mixture containing 1-chloro-pentaverate with the addition of the third component, including, for example, chlorofluorocarbon.Various derivative methods for cleaning Pentafluoroethane from 1-chloro-Pentafluoroethane described in the literature.For example, in EP 508631 described the recovery of 1-chloro - Pentafluoroethane using metal hydrides to turn 1-chloro-pentaborate in pentaborate in the liquid phase. In this process, the maximum conversion of about 60%.Another process for separating a multi-stage distillation to remove the 1-chloro - pentaverate from Pentafluoroethane described in USP 5346595. However, the maximum received the purity 99.8%, therefore the limits are much higher than appropriate.Another method, which is described, is the fluoridation of tdelay by distillation from Pentafluoroethane. See, for example, EP patent 612709.The disadvantage of all these processes, described in the literature, is that there should be an additional setting to an industrial method for producing 1-chloro-Pentafluoroethane, therefore, along with manufacturing defects observed additional cost of the product.Consequently, there was an urgent need to have available a way to get directly from the industrial installation pentaborate as a final product containing small amounts of 1 - chloro-Pentafluoroethane lower than 0.02% by weight, without the need for additional operations.It has been unexpectedly found that it is possible to obtain pentaverate small quantities of 1-chloro-Pentafluoroethane stated above, if you act in the manner described below.The object of the present invention is a method of producing Pentafluoroethane containing a quantity of 1-chloro-Pentafluoroethane lower than 0.02% by weight, where pentaverate get the conversion process tetrafluorochloroethane CF3CHClF in the gas phase in the presence of a chromium oxide catalyst (Cr2O3) supported on a carrier, including AlF3the carrier has the soda is setout at a temperature of 140-180oC at the time of contact with 15-30, from >180oWith up to 240oC when the contact time between 5 and 15, >240oWith up to 260oC at the time of contact between 1 and 5, from >260oWith up to 300oC at the time of contact between 0.1 and 1 C. Preferably operate in the range of 160 - 260oC, most preferably 180oC - 240oC.In the preferred within pentaverate get with the specified purity with 1-chloro-Pentafluoroethane even lower than 0.005% by weight. In practice, the process of rearrangement of the present invention tetraphthalate becomes pentaborate and chlorofluorocarbon and other by-products, the reaction product of pentaverate separated by distillation from chlorofluorocarbon and other by-products, and he's ready for use in cooling substances after quantities of 1-chloro-Pentafluoroethane contained therein are lower than the limits specified above.In this case, additional phases described in the known processes for the separation of 1-chloro-Pentafluoroethane from Pentafluoroethane avoid.The catalyst of the present invention contains Cr2O3printed on AlF3method, well known in the literature.and then subjecting the thus impregnated carrier to activate the processing of air or nitrogen at a temperature of from 200 to 600oC, but preferably from 350 to 500oC.The preferred carrier is 100% by weight AlF3, preferably in the gamma and/or beta form.AlF3may also contain Delta form, usually up to 30% by weight.The content of Cr2O3in the catalyst on the carrier is usually in the range from 1 to 15% by weight in terms of Cr in the catalyst.The catalyst of the invention is particularly suitable for use in a fluidized bed apparatus.The following examples illustrate but do not limit the present invention.Example 1. The catalyst containing Cr2O3on AlF3suitable for use in fluidized layer was prepared by impregnation of a granulated AlF3media (a mixture of beta, gamma and/or Delta form, having a surface area of 25-30 m2/g, the fluorine content of about 95% of theoretical value) in an aqueous solution of CrCl3in the ratio of 492 g CrCl36H2O per kg AlF3.Thus obtained catalyst was dried in an oven at 20oC for several hours, then placed in an Inconel 600 tube reactor having a diameter of 50 mm, equipped with a porous wall and is electrically heated.The product was analyzed by gas chromatography and got:
125 : 35,8% mol; 124 : 36,5% mol;
123 : 27,1% mol; other : 0.6% of mole.The content of 1-chloro-Pentafluoroethane in Pentafluoroethane after separation of Pentafluoroethane of the obtained products was lower than the detection limit, i.e. below 0.005% by weight.Example 2. Example 1 was repeated using a contact time of 2.5 seconds, duplicate filing tetrafluorochloroethane.The products were analyzed by gas chromatography and got:
125 : 23,9% mol; 124 : 56,9% mol;
123 : 18,7 mole%; other 0.5% mol.115 125 lower limit of 0.005% by weight.Example 3. 800 cm3the catalyst of example 1 was placed in the reactor of the previous examples and 530 g/h tetraphthalate missed at 180oC so that the contact time was 30 seconds.The products were analyzed by gas chromatography and got:
125 : 32,5% mol; 124 : 31,7% mol;
123 : 35.2% mol; others : 0 was defined as 0,002% by weight.Example 4. Example 1 was repeated, but using a temperature of 240oC and a contact time of 10 seconds, reducing by half the supply tetrafluorochloroethane.The products were analyzed by gas chromatography and got:
125 : 24,5% mol; 124 : 50,3% mol;
123 : 24.8% mol; other : 0.4% mol.The content of 1-chloro-Pentafluoroethane in Pentafluoroethane lower limit of 0.005% by weight.Example 5 (comparative) 250 cm3the catalyst prepared according to example 1, except that the final calcination was performed in a stream of nitrogen instead of air, was placed in the reactor, which was used in the previous examples.At 280oC and a pressure slightly higher than one atmosphere, 180 g of TETRAFLUOROMETHANE diluted 25 N/h of nitrogen was applied, the contact time of 10 seconds, and got the following products, which were analyzed by gas chromatography.125 : 36,7% mol; 124 : 32,5% mol;
123a : lower than 0.05% mol; 123 : 27,8% mol; other: 2.8% mol.The content of 1-chloro-Pentafluoroethane in Pentafluoroethane higher than 0.1% by weight. 1. The method of obtaining Pentafluoroethane containing 1-CHLOROPENTAFLUOROETHANE less than 0.02 percent by weight, where pentaborate was obtained by the transformation of TETRAFLUOROMETHANE CF
FIELD: organic synthesis catalysts.
SUBSTANCE: catalyst is prepared from allyl chloride production wastes comprising 30-50% 1,3-dichloropropenes, 30-60% 1,2-dichloropropane, and 3-5% 1,2,3-trichloropropane, which are treated at 5-10°C with 30-50% dimethylamine aqueous solution in such amount as to ensure stoichiometric ratio of dimethylamine with respect to 1,3-dichloropropenes. Resulting mixture is held at 20-25°C for 0.5-1.0 h and then 40-44 sodium hydroxide solution is added in stoichiometric amount regarding dimethylamine, after which clarified waste is added to dimethylamine at 60-70°C and stirring in amount ensuring stoichiometric ratio of dimethylamine to 1,3-dichloropropenes contained in clarified waste. Mixture is aged for 2-3 h, organic phase is separated, and remaining interaction phase is supplemented by C1-C4-alcohol or benzyl alcohol at alcohol-to-dimethylamine molar ratio 1:(1-3).
EFFECT: reduced expenses on starting materials.
2 cl, 3 ex