JP6043415B2 - Method for producing 2,3,3,3-tetrafluoropropene - Google Patents

Description

  The present invention relates to a method for producing 2,3,3,3-tetrafluoropropene (1234yf), and more particularly to its two-stage production process. In the present invention, pentachloropropane containing 1,1,1,2,3-pentachloropropane (HCC 240db) and / or l, 1,2,2,3-pentachloropropane (HCC 240aa) is first converted to hydrogen fluoride ( HF) to make 2-chloro-3,3,3-trifluoropropene (HFO 1233xf) in this first stage (a), which is converted to 1234yf in the second stage (b).

  The target product of the present invention, 1234yf, is a known compound for foaming agents, refrigerants, aerosol propellants, heat transfer media, fire extinguishers, and other applications. This 1234yf is a compound having zero ozone depletion potential (Zero Ozone Depletion Potential, ODE) and is also known to have a very low global warming potential (GWP) of 150 or less.

  The use of chlorofluorocarbons (CFCs) was prohibited by the Montreal protocol for ozone layer protection. Instead of chlorofluorocarbons, compounds that have less impact on the ozone layer, such as hydrofluorocarbons, HFCs, such as HFC-134a, have come to be used. However, these compounds become greenhouse gases. Accordingly, there is a need to develop one with low ODE (ozone depletion potential) and low GWP (global warming potential). Hydrofluorocarbons (HFCs) have been identified as important candidates for compounds that do not affect the ozone layer, but there is still a need to find compounds that exhibit relatively high GWP values and even lower GWP values. Yes. Hydrofluoroolefins (HFO) are considered to be an alternative with very low ODE and GWP values. Several processes for producing this HFO compound, especially propylene, have been developed.

Patent Document 1 (US Patent Publication No. US2009 / 0240090) discloses 2-chloro-3,3,3-trifluoro by gas phase reaction of 1,1,1,2,3-pentachloropropane (HCC 240db). A method for producing propene (HCFO 1233xf) is disclosed. Example 3 of this patent uses a catalyst consisting of fluorinated Cr ₂ O ₃ . The resulting compound 1233xf is then converted to the product 2-chloro-1,1,1,2-tetrafluoropropane (244bb) in a liquid phase reaction, which is then converted to the desired product 1234yf.

In Example 3 of Patent Document 2 (WO 02005/108334), a contact time of about 5 to 50 in the presence of 5 molar excess of HF on a 50 g 1/8 inch Cr ₂ O ₃ catalyst bed was set. In a second, 240 db is passed through the through reactor at a temperature of about 250-400 ° C. to 244 db (2-chloro-1,1,1,3-tetrafluoropropane). In addition, this 244db was dehydrochlorinated over Cr ₂ O ₃ catalyst (50 g) at 425-550 ° C. with a contact time of 25-30 seconds to give 234ze (1,3,3,3-tetrafluoropropene). It is also described to do.

  This document generally relates to a schema that produces 1234yf via 244. Thus, there is a need for further processes for manufacturing 1234yf.

US Patent Publication No. US2009 / 0240090 International Patent Publication No. W02005 / 108334

  The present invention is based on the discovery that 1234yf compounds can be prepared starting from pentachloropropane. In an embodiment of the present invention, the process of the present invention is performed without producing 244bb (2-chloro-1,1,1,2-tetrafluoropropane) in an intermediate stage.

The present invention provides a process for producing 2,3,3,3-tetrafluoropropene characterized by comprising the following steps (a) and (b):
(A) Catalytic reaction of 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane with HF to give 2-chloro-3,3,3-trifluoro Make a propen,
(B) The obtained 2-chloro-3,3,3-trifluoropropene is converted to 2,3,3,3-tetrafluoropropene by a catalytic reaction.

Is a conceptual diagram of a process for executing step (b). FIG. 4 is a conceptual diagram of another process for executing step (b). FIG. 2 is a diagram showing an example of an experimental apparatus used in the first stage of a liquid phase reaction. FIG. 2 is a diagram of a process performed in the stage (a) liquid phase.

Specific examples are as follows.
(1) The step (b) includes the following (i) to (iii):
(I) Hydrogen fluoride HE and gas phase under conditions sufficient to obtain 2-chloro-3,3,3-trifluoro-1-propene (1233xf) in the presence of a fluorination catalyst to obtain a reaction mixture. Contact with
(Ii) combining the reaction mixture with a first stream comprising HC1 and 2,2,2,3-tetrafluoropropene (1234yf), HF and unreacted 2-chloro-3,3,3-trifluoro- separating into a second stream consisting of l-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb);
(Iii) Recirculate at least a portion of the second stream to at least a portion of step (i).

(2) The first stream is further separated into HCl and 2,2,2,3-tetrafluoropropene (1234yf), preferably in the distillation stage.

(3) The step (b) includes the following (i) to (iv):
(I) 2-chloro-3,3,3-trifluoro-1-propene (1233xf) is hydrogen fluoride HF in the gas phase in the presence of a fluorination catalyst under conditions sufficient to obtain a reaction mixture. Contact with
(Ii) separating the reaction mixture into a stream comprising HC1 and a fluorinated product;
(Iii) The above stream containing the fluorinated product is mixed with a first stream comprising 2,2,2,3-tetrafluoropropene (1234yf), HF and unreacted 2-chloro-3,3,3-trifluoro. -1-Propene (1233xf) and a second stream consisting of 1,1,1,2,2-pentafluoropropane (245cb),
(Iv) Recirculating at least a portion of the second stream to at least a portion of step (i).

(4) Step (b) is carried out in the presence of a catalyst comprising Ni-Cr, preferably a supported catalyst.
(5) The catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

(6) Step (a) is performed in the liquid phase.
(7) Step (a) is carried out in an organic medium.

(8) The above method is carried out in a solvent. This solvent is 1,2-dichloroethane, 1,2,3-trichloropropane, 1-chloro-1-fluoroethane, 1,1-difluoroethane, 1,1-dichloroethane, 1,3-dichloro-1-fluorobutane, Tetrachlorofluoropropane isomer, trichlorodifluoropropane isomer, dichlorotrifluoropropane isomer, 1,1,1,3,3-pentafluorobutane, 1,1,2-trichloro-2,2-difluoroethane, nitromethane and Selected from nitrated solvents containing nitrobenzene, sulfones containing sulfolane and dimethyl sulfone, 1,1,2-trichloro-2-fluoroethane, tetrachloroethylene or mixtures thereof, preferably 1,1,2-trichloro- 2,2-difluoroethane.

(9) The catalyst is made an ionic liquid.
(10) The reaction product is taken out in a gaseous state.

(11) The method includes the following steps (i) and (ii):
(I) a reaction mixture comprising 1,1,1,2,3-pentachloropropane or / and 1,1,2,2,3-pentachloropropane and 2-chloro-3,3,3-trifluoropropene. Contacting with hydrogen fluoride in the liquid phase in an organic medium under conditions sufficient to form,
(Ii) separating the reaction mixture into a first stream consisting of HC1 and a second stream consisting of HF and 2-chloro-3,3,3-trifluoropropene;

(12) Step (a) is performed in the gas phase.
(13) The above method is performed in the presence of oxygen.

(14) Step (a) is carried out in the presence of a catalyst comprising Ni-Cr, preferably a supported catalyst. The catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

(15) The temperature of step (b) is at least 30 ° C. higher than the temperature of step (a).
(16) 1,1,1,2,3-pentachloropropane contains isomer 1,1,2,2,3-pentachloropropane up to 40 mol% or less.
(17) The above method is a continuous method.

  The present invention further resides in a mixture comprising the product obtained at the above stage of the above inventive process, in particular mainly 1234yf, and impurities and / or unreacted starting materials and / or co-products.

1233xf is converted to 1234yf by gas phase reaction.
The second stage of the above production method of 1234yf is the 2,3,3 of the desired product by fluorination reaction of 2-chloro-3,3,3-trifluoro-1-propylene (1233xf) obtained in the previous stage. , 3-tetrafluoro-1-propene.

  These two stages can be performed in succession or in a discontinuous manner with intermediate storage of 1233xf. The second stage can be carried out directly on the fluorination catalyst in the gas phase in the presence of HF. This gas phase reaction is carried out in the presence of a fluorination catalyst. The reaction is carried out in a single gas phase reactor. The temperature, pressure and contact time can be easily determined by one skilled in the art. Typical conditions are shown below.

  The level of conversion and selectivity of the desired product varies according to the process conditions. The catalyst can be in any suitable form such as a fixed bed or fluidized bed, preferably a fixed bed. The flow direction may be the downstream direction or the ascending direction.

The catalyst is, for example, a metal catalyst based on transition metal oxides or derivatives or halides or oxyhalides of such metals. Examples of the catalyst include FeC1 ₃ , chromium oxyfluoride, chromium oxide (which may be fluorinated if necessary), Hokkrom, and a mixture thereof. Other catalysts is a catalyst supported on carbon, antimony Berosu catalysts, aluminum-based catalyst (A1F ₃ and Al ₂ O ₃ and oxy alumina fluoride and aluminum fluoride, etc.). Commonly usable catalysts are chromium oxyfluoride (aluminum fluoride and oxyfluoride) and metals such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Mg, Sb Is a supported or unsupported catalyst. Patent Document 3, page 7, lines 1 to 5 and lines 28 to 32, patent document 4, paragraph [0022], patent document 5, page 9, lines 22 to page 10, line 34. Reference can be made to Claim 1 of Patent Document 6. These contents are part of the book.
International Patent Publication No. WO2007 / 079431 European Patent No. EP-A-939071 International Patent Publication No. WO2008 / 054781 International Patent Publication No. WO2008 / 040969

The catalyst is activated before use. Typically, HF is activated under high pressure as described in Patent Document 7 (generally, the pressure used in the gas phase method is a pressure of about 10 bar or more). The contents of this patent form part of the present specification. Any other suitable conditions are also suitable.
US Patent No. US-A-7485598

  In the preferred embodiment, a specific catalyst is used. This catalyst is a mixed catalyst containing chromium and nickel. The molar ratio of Cr: Ni to metal element is generally between 0.5 and 5, for example between 0.7 and 2, close to 1. The catalyst can contain 0.5-20% chromium and 0.5-20% nickel by weight, preferably between 2-10% of each metal.

  The metal can be in the form of a metal or in the form of its oxides, halides or derivatives containing oxyhalides. The above derivatives containing halides and halide oxides are obtained by activation of the catalytic metal. Metal activation is not required but is preferred.

The support is preferably made of aluminum. Some supports such as alumina, activated alumina or aluminum derivatives are also possible. These derivatives include, for example, aluminum halides and aluminum halide oxides described in Patent Document 8, and can be obtained by the activation method described later.
US Patent No. US-P-4902838

The catalyst can include activated or unactivated chromium and nickel on the support in an activated or deactivated state. Reference can be made to the catalyst described in Patent Document 9, particularly the catalyst described on page 4, line 30 to page 7, line 16 of the catalyst. This is part of this specification.
International Patent Publication No. W02009 / 118628

  It is known that the activation step can be carried out using fluorinated materials, generally HF. This stage of the process of the invention and the whole process are preferably carried out in continuous operation.

  The 1233xf fluorination process involves contacting 1233xf and HF in the reaction zone in the gas phase under conditions sufficient to convert 1233xf to a fluorinated product comprising 1234yf and 245cb. The conditions are described below. Also, unreacted 1233xf and other by-product subfluorinated intermediates present in minor amounts are recycled to the reactor. This recycle stream also includes heavy fractions in the reaction stream separated in the distillation stage.

  This step is generally carried out with a molar ratio of HF: 1233xf of 3: 1 to 150: 1, preferably 4: 1 to 70: 1, more preferably 5: 1 to 50: 1. This stage is generally carried out at a pressure of 1 to 20 bar, preferably 5 to 15 bar, more preferably 7 to 10 bar. Also, this stage is generally carried out at a temperature of 200-450 ° C, preferably 300-430 ° C, more preferably 320-420 ° C. The temperature of the reactor bed can be substantially uniform or can be adjusted along the flow direction and can be reduced or increased along the flow direction.

  The contact time (according to the operating pressure and temperature, the catalyst volume divided by the total flow rate of the reactants and feed) is generally 6-100 seconds, preferably 10-80 seconds, more preferably 15-50 seconds. is there. An oxygen co-feed or a chlorine co-feed can be used to extend the catalyst life, the amount generally being 0.05-15 mol%, preferably 0.5-20 mol%, relative to 1233xa. Oxygen or chlorine. Oxygen can be introduced as an oxygen-containing gas such as air, pure oxygen or an oxygen / nitrogen mixture. Chlorine can be introduced as a chlorine-containing gas such as pure chlorine or as a chlorine / nitrogen mixture.

  Each reactant can be fed using a feed at the same location in the reactor, a different location, or a predetermined location along the reactor. A preferred feed system is to blow gaseous reactants into the bottom of the reactor. Recirculation can take place at the reactor inlet or at an intermediate stage of the reactor, preferably at the reactor inlet.

  In another embodiment of the present invention, a portion of the reaction stream exiting the gas phase reactor can be recycled to the reactor before being separated into a first light stream and a second heavy stream. The recirculation ratio can be about 0.7. This recycling can dilute the highly reactive 233xf to avoid polymerization.

  This step can be performed with the apparatus shown in FIG. 1 or FIG. FIG. 1 represents the process performed in one embodiment of the present invention, where 1233xf and HF are supplied to the gas phase reactor. The reaction mixture exiting the reactor consists of HC1, unreacted 1233xf, unreacted HF, 1234yf, 245cb, and a minor amount of 244bb. This reaction stream is separated by distillation into a first stream (light product) consisting of HC1 and 1234yf (which forms an azeotrope with a small amount of HF) and minor amounts of 245cb and 1233xf. The second stream (heavy product) obtained at the bottom of the distillation column consists of HF, 1233xf, 245cb and a minor amount of 244bb. Light fractions containing HCl, 1234yf (together with HF), and minor amounts of other products are distilled again. The top stream consists of HC1, and the bottom stream consists of 1234yf and HF, which can be separated again using any suitable known method. Among the known methods, decantation can be used, where an HF rich stream can be created and recycled to the gas phase reactor. The stream leaving the decanter is processed according to known methods including water washing and gas washing and distillation.

  FIG. 2 represents another embodiment. In this case, HC1 is removed in the first stage before distillation of the organic fluorinated product. The gas phase reactor is supplied with 1233xf and HF. The reaction mixture exiting the reactor consists of 1233xf, unreacted HCl, unreacted HF, 1234yf, 245cb, and a minor amount of 244bb. This reaction stream is separated in the first distillation column into a stream mainly containing HC1 and another stream containing other products. This other stream is separated by distillation into 1234yf (which forms an azeotrope with a small amount of HF) and a first stream (light product) consisting of minor amounts of 245cb and 1233xf. The second stream (heavy product) obtained at the bottom of the distillation column consists of HF, 1233xf, 245cb and a minor amount of 244bb. From the top of the second distillation column is obtained a light fraction containing 1234yf (with HF) and minor amounts of other products. This top stream can be separated again using any known suitable method. By using decantation in a known process, an HF rich stream can be made and recycled to the gas phase reactor. The stream leaving the decanter is processed according to known methods including water washing and gas washing and distillation.

  The pressures in steps (a) and (b) need not be the same. Preferably, the second reactor pressure is less than or equal to the first reactor pressure to provide a gain for the unit pump. Other process conditions need not be the same in steps (a) and (b).

Production of 1233xf by 240 liquid phase reaction The present invention can be made 1233xf by liquid phase fluorination of 240db / 240aa, and the reaction is carried out so that the process conditions have substantial selectivity to the desired product. Based on the discovery that you can choose as you can.

  In a preferred embodiment of the present invention, the liquid phase process is performed in the organic phase. The reaction to 1233xf proceeds favorably by using the organic phase rather than the HF phase. The above prior art discloses a reaction mixture (hence the acidic phase) consisting essentially of HF. In this acidic phase, only saturated products are produced. Surprisingly, the inventor has discovered that conditions exist that allow fluorination to 1233xf. In particular, 1233xf can be formed when the reaction is carried out in an organic phase (consisting of 240 starting materials and / or solvent). When HF is added to the initial medium, it reacts and does not remain in the medium. The amount (or concentration) of HF is too low compared to other products.

  The term “organic phase” can be defined as a reaction phase consisting of a catalyst, starting materials, and optionally a solvent, which is substantially free of HF. A process carried out in the “organic phase” means a process that does not contain HF in the initial material, in contrast to conventional methods.

Because of the specific operating conditions, gaseous 1233xf can be removed from the reactor in the gas phase while maintaining the polymerization reaction at a low level.
Liquid phase fluorination of 240db / 240aa to 1233xf is performed in the presence of a catalyst.

  The reaction can be carried out in a liquid solvent, and the reaction zone is fed with a starting amount of organic (starting material) and / or the required amount of solvent at the start or mixed with this amount of solvent (if possible with the material). Continuously). When carrying out in a solvent, it is preferable to add the solvent first, and the amount can be adjusted by injecting the solvent if necessary.

  The reaction conditions (particularly pressure) are conditions such that the reactant becomes liquid. In one embodiment, the reaction product is a gas and the reactant is a liquid. Due to the fact that the reaction product is a gas, it can be recovered in the gas phase at the outlet of the reaction zone. The intermediate product, particularly compound 242 (trichlorodifluoropropane), is preferably liquid under reaction conditions, even if it can be stripped off with a gas stream.

  In the present invention, this stage is carried out especially under a pressure of 2 bar or more. This pressure is between 4 and 50 bar, preferably between 5 and 25 bar. For example, the reaction can be carried out at temperatures between 30 ° C. and 200 ° C., preferably between 40 ° C. and 170 ° C., advantageously between 50 ° C. and 150 ° C.

  The molar ratio of HF: starting compound is generally between 0.5: 1 and 50: 1, preferably between 3: 1 and 20: 1. A value of 5: 1 can be used advantageously. The amount of HF added corresponds to the stoichiometric amount of reaction (3) plus the amount of HF present in the effluent (HF and organic solvent), usually an azeotrope.

  Other reaction conditions (especially flow rates) can be determined by one skilled in the art according to common general knowledge, according to temperature, pressure, catalyst, reactant ratio, etc. Care is taken to avoid further fluorination reactions so that the main product obtained is 1233xf (no intermediate product).

The solvent (if used) is an organic solvent that is inert under the reaction conditions. The solvent is advantageously a generally saturated, preferably C2-C6 solvent, to avoid addition reactions. This solvent is described in Patent Document 10, for example.
French Patent FR 2733227

  The solvent advantageously has a boiling point (under atmospheric pressure) of, for example, 40 ° C. or higher, advantageously 50 ° C. or higher, more preferably 60 ° C. or higher. The higher the reaction temperature, the higher the pressure, and the boiling point of the solvent under the reaction conditions is higher than the temperature at which the reaction is carried out.

As the solvent, mention may be made in particular of saturated compounds of ethane, propane or butane or mixtures thereof in which at least two atoms have been substituted with a halogen selected from chlorine and fluorine. Examples include 1,2-dichloroethane, l, 23-trichloropropane, 1-chloro-1-fluoroethane, 1,1-difluoroethane, 1,1-dichloroethane, 1,3-dichloro-1-fluorobutane, tetrachloro Fluoropropane isomer, trichlorodifluoropropane isomer, dichlorotrifluoropropane isomer, 1,1,1,3,3-pentafluorobutane, 1,1,2-trichloro-2,2-difluoroethane or a mixture thereof Can be mentioned. Nitration solvents such as nitromethane or nitrobenzene and sulfolane such as tetramethylene sulfone (known as sulfolane) or dimethyl sulfone can be used. A preferred solvent is 1,1,2-trichloro-2,2-difluoroethane (F122). A reactive solvent can also be used as long as the reaction product is a non-reactive solvent. For example, the precursor of F122, namely F121 (CC1 ₂ F—CHC1, 1,1,2-trichloro-2-fluoroethane or tetrachloroethylene) can be used.

  The solvent can be present in an amount of dilution of at least 20%, preferably between 20% and 80%, advantageously between 40% and 60%. The reaction takes place catalytically. The catalyst can be a fluorination catalyst known in the art in the liquid phase.

Lewis acids, catalysts containing metal halides, antimony, tin, tantalum, titanium, transition metals, in particular metal halides containing transition metal halides such as molybdenum, niobium, iron halides, cesium, oxides of transition metals, Group IVb metal halides, group Vb metal halides, halogenated fluorinated chromium, fluorinated chromium oxide or mixtures of both can be used. Metal chlorides and fluorides can be used advantageously. Examples of this type of catalyst include SbC1 ₅ , SbC1 ₃ , TiC1 ₄ , SnC1 ₄ , TaCl ₅ , NbC1 ₅ , TiC1 ₄ , FeC1 ₃ , MoC1 ₆ , CsCl and their corresponding fluorinated derivatives. A pentavalent metal halide is suitable.

Preference is given to using a catalyst comprising an ionic liquid. This ionic liquid is particularly important for fluorination with HF in the liquid phase. The ionic liquid is described in Patent Document 11 (particularly, page 4, line 1 to page 6, line 15), Patent Document 12 and Non-Patent Document 1 of the present applicant.
International Patent Publication No. W02008 / 149011 International Patent Publication No. W001 / 81353 "Liquid-phase HF Fluorination", Multiphase Homogeneous Catalysis, Ed., Wiley-VCH (2002) 535

  While it can be operated at various catalyst / organic (including solvent) ratios, this molar ratio is generally between 2 mol% and 90 mol%, preferably between 4 mol% and 80 mol%, more preferably between 6 mol% and Preferably it is between 75 mol%.

  The starting material can be substantially pure 240 db and / or substantially pure 240 aa or a mixture of the two. In one embodiment, the starting material is substantially pure 240 db. In other embodiments, the starting material contains a typical 240 db feed or 240aa isomer up to 40%, typically up to 20%.

  Chlorine streams can be used to extend catalyst life, and the amount is generally 0.05 to 20 mol%, preferably 0.5 to 15 mol% per mole of 240 db / 240aa of the starting compound. Chlorine can be introduced pure or mixed with a noble gas such as nitrogen. By using an ionic catalyst, the amount of chlorine can be reduced to the amount used.

  A material stabilizer can be used as required, and the amount used is generally 5 to 1000 ppm, preferably 10 to 500 ppm. This stabilizer is generally a polymerization inhibitor.

  The reactant product can also be stripped by mechanical entrainment with a light gas that allows its movement. By removing the 1233xf gas from the liquid phase reactor, the polymerization reaction and side reactions (addition of 1233xf to the double bond) can be maintained at a low level (because the amount of polymerizable material in the medium is reduced). The addition of a gaseous compound is advantageous for the reaction, and is also preferable for improving stirring (bubbling), for example.

  This gas is preferably an inert gas such as nitrogen or helium, or HC1 gas. When HC1 is used, the reaction proceeds even if it is added to the medium of HC1, which is a reaction product.

  This additive gas is advantageously anhydrous hydrogen chloride. The stripping gas flow is determined according to the operating conditions. For example, compared to the starting material stream, the HC1 stream is such that the molar ratio of HC1: starting material is between 0.5: 1 and 5: 1, preferably between 1: 1 and 3: 1. .

  The liquid phase fluorination process of the present invention can be carried out continuously or semi-continuously. In the preferred embodiment, the process is continuous.

  The reactants (starting materials and HF) and other compounds used in the reaction (chlorine, anhydrous HCl) are fed to the reactor from the same location or from different locations in the reactor. In the preferred embodiment of the invention, gaseous compounds are injected from the bottom of the reactor to improve mechanical stripping and mixing.

  If recirculation is performed, it can be recirculated directly to the reactor inlet or recirculated to a separate dip pipe.

  [FIG. 4] is a conceptual diagram of the method of the present invention. A reactor for a liquid phase reaction (provided with a catalyst strip tower not shown) contains a catalyst, pentachloropropane, and a solvent used as necessary. And then pentachloropropane and HF are fed continuously. An anhydrous HC1 stream can also be injected.

  The stream withdrawn from the reaction zone is in the form of a gas, mainly 1233xf, HCl, HF, stripped traces of solvent 122 (if used) and 242 isomers and possibly 243 (dichlorotrifluoro). Propane), especially 243db (1,1,1-trifluoro-2,3-dichloropropane) and other by-products. This stream is sent to the HC1 distillation column. The HC1 stream is withdrawn from the top of the column and from the bottom of the column is a stream comprising 1233xf, 242 and HF and trace amounts of 122 and 243 db. This bottom stream is generally 30-70 mol% 1233xf, 30-70 mol% HF, and minor amounts, generally no more than 10 mol%, preferably no more than 5 mol% of the 242, 243 series of compounds (particularly 243db) It consists of. This stream is sent to the separation stage by decantation. This decantation separates the two streams, the first stream consisting of HF, soluble organics and solvent (if used). This HF rich stream is returned to the fluorination reaction. The second stream consists of 1233xf, 242 and the remaining HF and trace amounts of 122 and 243db. This stream is sent to a distillation column where it is separated. Trace amounts of 122 and 243 db recovered at the bottom are returned to the fluorination reactor.

  Since 242 products (generally 240 series higher saturated fluorinated compounds) are intermediate compounds, they are not increased. A stream containing HF and 1233xf is withdrawn at the top. This top stream can be further separated or sent directly to the next stage. The 242 isomer and / or 243db can be recycled in the process of the present invention.

A heavy stream is withdrawn from the bottom of the liquid phase reactor. This heavy component is thought to consist of oligomers of the C ₆ F ₆ H ₂ Cl ₂ type, but is not restricted thereto. The bottom stream of the fluorination reactor is purged with a period and flow that avoids accumulation of heavy components (the purge ratio, defined as flow, frequency, can be easily determined by one skilled in the art). This stream is treated with a heavy recovery column and removed from the bottom of the column. A column top stream containing HF, 122, 242 isomer, and 243 db is recovered and this stream is recycled to the fluorination reactor.

Production of 1233xf by 240 gas phase reactions The present invention is based on the discovery that 240db (and / or 240aa) can be made 1233xf by catalytic fluorination in the gas phase. In the present example, process conditions can be selected such that when oxygen is cofed with 240, the reaction can be run with improved catalyst life. The catalyst used in the present invention can be, for example, the same type as the catalyst disclosed in step (b) above.

  The fluorination process of the present invention involves contacting 240 db with HF in the gas phase in the reaction zone under conditions sufficient to convert 240 db to a fluorinated product consisting primarily of 1233xf. This process of the invention is generally carried out at a HF: 240 molar ratio of 3: 1 to 150: 1, preferably 4: 1 to 70: 1, more preferably 5: 1 to 50: 1.

  This process of the invention is generally carried out at a pressure of 1-20 bar, preferably 3-15 bar, more preferably 5-10 bar. This process of the present invention is generally carried out at a temperature of 200-450 ° C, preferably 300-430 ° C, more preferably 320-420 ° C. The temperature of the bed can be adjusted along the flow path so that the reactor is substantially uniform or decreases or increases along the flow direction.

  The temperature of step (a) is generally below the temperature of step (b), preferably at least 30 ° C. Contact time (catalyst volume divided by total flow rate of reactants and cofeeds matched to operating pressure and temperature) is generally 6-100 seconds, preferably 10-80 seconds, more preferably 15-50 seconds. .

  Use oxygen co-feed to extend catalyst life. The amount of oxygen or chlorine per molecule of pentachloropropane is generally 0.05 to 15 mol%, preferably 0.5 to 10 mol%. Oxygen can be supplied as an oxygen-containing gas such as air, pure oxygen or an oxygen / nitrogen mixture. It is also possible to use co-fed chlorine instead of co-fed oxygen (under the same operating conditions).

  Each reactant can be fed stepwise to the reactor at the same location, a different location, or each location located along the reactor. A preferred feed system is a method in which gaseous reactants are blown into the bottom of the reactor. Recirculation can take place at the reactor inlet or at an intermediate stage of the reactor, preferably at the reactor inlet. It is also possible to recycle part of the stream leaving the reactor.

Polymerization inhibitors can be used at any stage of the process of the invention to extend catalyst life. The amount is generally about 50 to 1000 ppm, preferably 100 to 500 ppm. The polymerization inhibitor can be p-methoxyphenol, t-amylphenol, limonene, d, l-limonene, quinones, hydroquinone derivatives, epoxides, amines and mixtures thereof. A preferred polymerization inhibitor is p-methoxyphenol or t-amylphenol. By co-feeding the polymerization inhibitor at a low level, the polymerization of the chloroolefin can be controlled, and the catalyst life can be extended as described in Patent Document 13 (the contents of which are part of this specification). ).
US Pat. No. 5,714,651

  The final product and intermediate product can be easily recovered by any means known to those skilled in the art, such as gas washing, water washing, extraction, decantation, preferably distillation. Each stream can be further purified by distillation.

  The reaction is carried out in a reactor dedicated to the reaction containing halogen. This type of reactor is known to those skilled in the art and can be a lining, for example, a reactor based on Hastelloy®, Inconel®, Monel® or fluoropolymer. The reactor can have a heat exchange means as required.

Unless otherwise indicated, the percentage is mol%.
Examples of the present invention will be described below, but the present invention is not limited to the following examples.

This example produces 1234yf starting from 1233xf. In the following examples, a Ni—Cr / A1F ₃ catalyst obtained as follows is used. The catalyst used is a nickel / chromium mixed catalyst having an Ni / Cr atomic ratio of 1 supported on alumina fluoride, which is produced by impregnating a solution of nickel and chromic anhydride (CrO ₃ ). After impregnation and drying, the solid is treated at a temperature between 320 ° C. and 390 ° C. in the presence of a mixture of hydrofluoric acid and nitrogen (the concentration of acid in nitrogen is 5-10% by volume). The catalyst bed is placed on a grid welded to the lower end of the reactor. Temperature was measured along the catalyst bed at three locations in the reactor.

Example 1
Add catalyst Ni-Cr / A1F ₃ of 150ml the fluorination reactor 1233xf. The reactor is fed with HF at 16.4 g / hr and 1233xf at 4.1 grams / hr. The reaction temperature is 352 ° C. and atmospheric pressure. The molar ratio of HF / 1233xf is 26.9, and the contact time is 4.9 seconds. The conversion rate is 10.3%. The selectivity (the amount of one product divided by all reaction products, which means 1233xf is not included) is 71.4% for 1234yf and 22.7% for 245cb. Other minor compounds detected were 244bb, 1234ze and 245fa (the outlet gas stream was 89.13 mol% 1233xf, 7.75 mol% 1234yf, 2.47 mol% 245cb and 0.65 mol). % Other compounds).

Examples 2-6
The fluorination reaction of 1233xf was carried out according to Example 1 and the contact time was varied so that the HF / 1233xf molar ratio of the HF stream and the 1233xf stream was close to 5, 9.5, 18.8, 26.7, 37.9 And 39 seconds. The main products obtained are 1234yf and 245cb (except for 1233xf, not fully converted). The molar compositions of 1234yf and 245cb are summarized in [Table 1].

Example 7
A 1233xf fluorination reaction was performed according to Example 1. A 60 ml catalyst was placed in a 60 ml reactor. 245cb was added to the feed. The flow rate of 245cb is 2.1 g / h, the flow rate of 1233xf is 4.5 g / h, and the flow rate of HF flow is 16.2 g / h. Therefore, 47 moles of 245cb were used per 100 moles of 1233xf. The molar ratio of HF / 1233xf is 24.5 and the contact time is 4.8 seconds. Air was added continuously to extend catalyst life. The amount of oxygen introduced is equal to 0.5% expressed as a molar ratio of O ₂ / (1233xf + 245cb. The molar composition of the outlet gas was analyzed by gas chromatography: 1233xf: 60.6%, 1234yf: 26.6%, 245cb: 12.4%, other impurities (1233xf: 89.08 mol, 1234yf: 39.07 mol, 245cb: 18.17 mol, other: 0.72 mol).

  In this example, 1233xf is produced starting from 240 in the liquid phase. The apparatus used is that described in FIG. 3 and consists of an autoclave made of a jacketed 1 liter stainless steel 316L equipped with a magnetic stirrer. Furthermore, a pressure gauge and a thermometer are provided. The introduction and degassing of the reactants is made from a hole in the top of the autoclave and has a pressure control valve and a condenser at the top. The condenser temperature was controlled using an independent thermostat bath.

  During the reaction, the reaction product was continuously withdrawn and a scrubber was added to recover the hydrogen acid HF and HCl and cold trapped in liquid nitrogen. The mass balance can be calculated from the change in the weight of the scrubber and the increase in traps.

  At the end of the reaction period, the reaction medium is degassed and the residual HF is evacuated. Organics that would be withdrawn simultaneously during this degassing are trapped after always passing through a scrubber to remove HF and HC1 from the gas stream. In the last stage, the autoclave is opened and discharged, and after the catalyst is hydrolyzed and extracted with hydrochloric acid solution, a sample of the organic phase is analyzed.

  The liquid sample was then analyzed by gas phase chromatography. Chromatographic analysis was performed using column CP Sil8 (dimensions 50 m, 0.32 mm, 5 μm). The furnace temperature was programmed for 10 minutes at 40 ° C. and then 200 ° C. with a 4 ° C./min ramp. The conversion (%) is (xi−xf) / xi * 100 where xi is the initial molar amount of the material and xf is the total molar yield of the material. Product selectivity is calculated from the sum and ratio of the recovered molar amount of product and the molar amount of product reacted.

Examples 8 and 9
0.5 mole of 240db or 1,1,1,2,3-pentachloropropane, and 0.2 moles of catalyst (0.2 mol of ethyl methyl imidazolium chloride, 0.4 mole and SBC1 ₅ Combination 0.2 mol of the fluorinated complex catalyst emim ⁺ Sb ₂ F ₁₁ ^- emimcl) was introduced into the autoclave. In one example, 151 g of F122 or 1,1,2-trichloro-2,2-dichloroethane as a solvent was added to the autoclave. HF was then continuously added for 5 hours at a steady flow of 1 mol / hour. The temperature is 133 ° C. and the absolute pressure is 9 bar. The condenser was always set at 90 ° C. In both examples, HC1 was run through the autoclave to aid in stirring and product stripping. The molar ratio of HC1 to 240 db is close to 2: 1.

  It can be seen that a significant amount of 1233xf was produced. This was obtained in an organic medium rather than an acidic medium.

Examples 10 and 11
The same equipment as above was used. 0.5 (240db including 240db or 10% 240Aa) moles of material samples, 0.2 mole of catalyst (0.2 mol of ethyl methyl imidazolium chloride, a combination of a 0.4 mol SBC1 ₅ 0.2 mol of the fluorinated complex catalyst emim ⁺ Sb ₂ F ₁₁ ^- _emimcl ) and 2 mol of F122 are introduced into the autoclave. HF is then continuously added for 5 hours with a steady flow of 1 mol / h. The temperature is 135 ° C. and the absolute pressure is 9 bar. The condenser set point was always 90 ° C. In both examples, a helium stream was passed through the autoclave to aid in stirring and production. The flow rate of helium is 5 liters / hour.

  These examples produce 1233xf starting from 240 in the gas phase. The apparatus used is a tubular reactor with an inner diameter of 19 mm made of INCONEL® alloy 600 surrounded by a tubular oven, equipped with a pressure gauge and a temperature control device. The reactants were vaporized in advance with a heater to form a gas phase and introduced from the top of the reactor. A sample of the reaction product was taken at the outlet of the reactor, washed with a precolumn, and analyzed online by gas phase chromatography equipped with a low polarity capillary column. Chromatographic analysis was performed as described above.

Example 12
The fluorination of 240db (1,1,1,2,3-pentachloropropane) was performed in the reactor with a Ni-Cr catalyst 79.4Cm ³ which is supported on A1F _3. The apparatus used is the same as in Example 1.
To the reactor, anhydrous HF was continuously supplied at 15 g / hour and 1,1,1,2,3-pentachloropropane was continuously supplied at 4.5 g / hour for 86 hours under atmospheric pressure. The contact time is 7.4 seconds and the molar ratio of HF to 240 is 36. The reaction temperature is 340 ° C., and the amount of oxygen with respect to 240 db is about 4 mol%. The results are shown in [Table 4].

Example 13
Fluorination of a mixture of 65.9% 240db or 1,1,1,2,3-pentachloropropane and 34.9% 240aa or l, 1223-pentachloropropane was carried out in the manner described in Example 1. . Anhydrous HF was continuously supplied to the reactor at 16 g / hour and 1,1,1,2,3-pentachloropropane at 5.1 g / hour continuously at atmospheric pressure. The contact time is 6.9 seconds and the molar ratio is 34. The reaction temperature is from 340 ° C., and the amount of oxygen is about 4 mol% based on the total number of moles of 1,1,1,2,3-pentachloropropane and 1,1,2,2,3-pentachloropropane. is there. The results are shown in [Table 4].

Examples 14 and 15
Example 13 was repeated at different temperatures as described in Table 4.

Claims (12)

A process for producing 2,3,3,3-tetrafluoropropene comprising the following steps (a) and (b):
(A) 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3-pentachloropropane is catalytically reacted with HF in the gas phase to give 2-chloro-3,3,3 -Make trifluoropropene,
(B) The obtained 2-chloro-3,3,3-trifluoropropene was subjected to catalytic reaction in the presence of HF and 1,1,2,2,2-pentachloropropane to produce 2,3,3,3-tetra Use fluoropropene. The method of claim 1, wherein step (b) comprises the following (i) to (iii):
(I) 2-chloro-3,3,3-trifluoro-1-propene (1233xf) in the presence of a fluorination catalyst under conditions sufficient to obtain a reaction mixture with hydrogen fluoride HF and a gas phase Contact with
(Ii) The reaction mixture is mixed with a first stream comprising HC1 and 2,3,3,3-tetrafluoropropene (1234yf), HF, and unreacted 2-chloro-3,3,3-trifluoro- separating into a second stream consisting of l-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb);
(Iii) Recirculate at least a portion of the second stream to at least a portion of step (i).   The process according to claim 2, wherein the first stream is further separated into HCl and 2,2,2,3-tetrafluoropropene (1234yf) in a distillation step. The method of claim 1, wherein step (b) comprises the following (i) to (iv):
(I) 2-chloro-3,3,3-trifluoro-1-propene (1233xf) is hydrogen fluoride HF in the gas phase in the presence of a fluorination catalyst under conditions sufficient to obtain a reaction mixture. Contact with
(Ii) separating the reaction mixture into a stream comprising HC1 and a fluorinated product;
(Iii) The above stream containing the fluorinated product is combined with a first stream comprising 2,3,3,3-tetrafluoropropene (1234yf), HF and unreacted 2-chloro-3,3,3-trifluoro. -1-Propene (1233xf) and a second stream consisting of 1,1,1,2,2-pentafluoropropane (245cb),
(Iv) Recirculating at least a portion of the second stream to at least a portion of step (i).   The process according to any one of claims 1 to 4, wherein step (b) is carried out in the presence of a catalyst consisting of Ni-Cr.   6. A process according to claim 5, wherein the catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.   The process according to any one of claims 1 to 6, wherein steps (a) and / or (b) are carried out in the presence of oxygen.   The process according to any one of claims 1 to 7, wherein step (a) is carried out in the presence of a catalyst consisting of Ni-Cr.   9. A process according to claim 8, wherein the catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.   The process according to any one of the preceding claims, wherein the temperature of step (b) is at least 30 ° C higher than the temperature of step (a).   The method according to any one of claims 1 to 10, wherein the 1,1,1,2,3-pentachloropropane contains the isomer 1,1,2,2,3-pentachloropropane up to 40 mol%.   The method as described in any one of Claims 1-11 performed by a continuous method.

Images