JP6623561B2 - Method for producing fluorine-containing olefin - Google Patents

Description

  The present invention relates to a method for producing a fluorine-containing olefin.

Fluoroolefins represented by the general formula: CF ₃ (CX ₂ ) _n CF = CH ₂ , and the general formula: CF ₃ (CX ₂ ) _n CH = CHF (X is a halogen) are various functional materials. , A solvent, a refrigerant, a foaming agent, and the like, and a compound useful as a monomer or a raw material thereof for producing a functional polymer. In particular, among the above-mentioned fluoroolefins, 2,3,3,3-tetrafluoropropene represented by the general formula CF ₃ CF = CH ₂ (hereinafter, abbreviated as “HFO-1234yf” in the present specification) is used for global warming. Promising as a refrigerant compound having a low conversion coefficient.

It is known that the above HFO-1234yf is produced by a method in which halopropane or halopropene is used as a raw material and which is fluorinated with hydrogen fluoride (HF) or a method in which hydrogenation and dehydrohalogenation are appropriately combined. . For example, as shown in Patent Document 1, when 1,1,1,2,3,3-hexafluoropropene (HFO-1216) is used as a raw material, HFO- 1234yf is manufactured.
CF ₃ CF = CF ₂ + H ₂ → CF ₃ CFHCF ₂ H (HFC-236ea) (1)
CF ₃ CFHCF ₂ H → CF ₃ CF = CFH (HFO-1225ye (E / Z)) + HF (2)
CF ₃ CF = CFH + H ₂ → CF ₃ CFHCFH ₂ (HFC-245eb) (3)
CF ₃ CFHCFH ₂ → CF ₃ CF = CH ₂ (HFO-1234yf) + HF (4)
Further, as shown in the following reaction formula (5), a reaction process is also known in which after fluorinating HFO-1243zf to obtain HFC-245eb, the reaction of the above reaction formula (4) is performed to obtain HFO-1234yf. .
CF ₃ CH = CFH + F ₂ → CF ₃ CFHCFH ₂ (HFC-245eb) (5)
CF ₃ CFHCFH ₂ → CF ₃ CF = CH ₂ (HFO-1234yf) + HF (4)
As described above, in any of the reaction steps, HFO-1234yf is produced by the dehydrofluorination reaction of HFC-245eb. Various studies have been made on such a dehydrofluorination reaction (see, for example, Patent Documents 2 to 4 and the like), and the type of catalyst, the reaction temperature, the contact time, and the like are appropriately adjusted so that HFO- A method for producing a fluorine-containing olefin such as 1234yf has been proposed.

JP 2012-77086 A JP-T-2009-54251 JP 2011-515457 A JP-T-2009-513719

However, in order to carry out the dehydrofluorination reaction of hydrofluorocarbon such as 245 eb, a certain amount of catalyst is required, and the reaction temperature also needs to be relatively high. For this reason, in the conventional method, there is a problem that not only the target substance but also its isomer CF ₃ CH = CHF (HFO-1234ze) tends to be produced as a by-product, and the life of the catalyst used in the reaction is reduced. There was also a problem. The problem that the catalyst life is shortened may be solved by entraining oxygen. However, in this case, since the combustion of the raw material and the target product is promoted, there is a problem that the yield is reduced.

  The present invention has been made in view of the above, and in a process of producing a fluorinated olefin by a dehydrofluorination reaction of a hydrofluorocarbon, a high conversion rate, and, at a high selectivity, the desired fluorinated olefin at a high selectivity. It is intended to provide a method of manufacturing.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, in a reaction for producing a fluorinated olefin by a dehydrofluorination reaction of a hydrofluorocarbon, a chromium-based catalyst containing a Group 5 metal was used as a catalyst. It has been found that the use can achieve the above object, and the present invention has been completed.

That is, the present invention relates to the following method for producing a fluorinated olefin.
Item 1.
In a method for producing a fluorinated olefin through a first reaction step in which dehydrofluorination of a hydrofluorocarbon is performed in the presence of a catalyst,
The hydrofluorocarbon is represented by the general formula (1) R ^f CFYCHZ ₂ (In the general formula (1), R ^f is a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms and does not contain chlorine. , Y and Z are each independently H or F, but when all Z are H, then Y is F).
The method for producing a fluorinated olefin, wherein the catalyst is a chromium-based catalyst containing a Group 5 metal.
Item 2.
Item 2. The method for producing a fluorine-containing olefin according to the above item 1, wherein in the general formula (1), R ^f is CF ₃ .
Item 3.
Item 3. The method for producing a fluorinated olefin according to Item 2, wherein the hydrofluorocarbon includes at least one selected from the group consisting of HFC-236ea, HFC-245eb, and HFC-245cb.
Item 4.
Item 4. The method for producing a fluorinated olefin according to Item 3, wherein the hydrofluorocarbon is HFC-245eb.
Item 5.
The ratio of the number of atoms of the Group V metal contained in the catalyst is 0.1% or more and 50% or less based on the total number of metal atoms contained in the catalyst. A method for producing a fluorine-containing olefin.
Item 6.
Item 6. The method for producing a fluorine-containing olefin according to any one of Items 1 to 5, wherein the dehydrofluorination in the first reaction step is performed at 50 to 380 ° C.
Item 7.
Item 7. The method for producing a fluorinated olefin according to any one of Items 1 to 6, wherein the dehydrofluorination in the first reaction step is performed at 100 to 350 ° C.
Item 8.
Item 8. The method for producing a fluorinated olefin according to any one of Items 1 to 7, wherein the hydrofluorocarbon is supplied to the first reaction step with oxygen gas.
Item 9.
Item 9. The method according to Item 8, wherein the flow rate (mol / min) of the oxygen gas is 0.1% or more and 10% or less with respect to the flow rate (mol / min) of the hydrofluorocarbon.

  In the method for producing a fluorinated olefin according to the present invention, a specific hydrofluorocarbon is subjected to a dehydrofluorination reaction using a chromium-based catalyst containing a Group 5 metal as a catalyst. Thereby, the conversion rate of the hydrofluorocarbon can be increased, and the target product can be obtained with a high selectivity. In addition, even if the dehydrofluorination reaction is performed at a low temperature, the target product can be obtained with a high conversion and a high selectivity.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the method for producing a fluorinated olefin of the present embodiment, the fluorinated olefin is produced through a first reaction step in which hydrofluorocarbon is dehydrofluorinated in the presence of a catalyst. In particular, in the present embodiment, the catalyst includes a chromium-based catalyst containing a Group 5 metal. In the method for producing a fluorinated olefin of the present embodiment, by using the above catalyst, the conversion of hydrofluorocarbon can be increased, and the target product can be obtained with a high selectivity. In addition, even if the dehydrofluorination reaction is performed at a low temperature, the target product can be obtained with a high conversion and a high selectivity.

  In the first reaction step, dehydrofluorination of hydrofluorocarbon is performed in the presence of a catalyst.

The hydrofluorocarbon is a compound represented by the general formula (1) R ^f CFYCHZ ₂ . Here, in the general formula (1), R ^f is a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms, does not contain chlorine, and Y and Z are each independently H or F However, if Z is all H, then Y is F. Hydrofluorocarbons have the advantage of not having to perform a dehydrochlorination step or a fluorination step because they do not have chlorine as a substituent.

R ^f is not particularly limited as long as it is a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms, but is preferably a CF ₃ group (trifluoromethyl group). In this case, the fluorinated olefin can be produced at a higher conversion and selectivity.

  The hydrofluorocarbon may be composed of only one compound represented by the general formula (1), but is not limited thereto, and may be composed of two or more compounds represented by the general formula (1). It may be.

  The hydrofluorocarbon preferably contains at least one selected from the group consisting of HFC-236ea, HFC-245eb and HFC-245cb. In this case, the fluorinated olefin can be produced at a higher conversion and selectivity.

  Note that HFC-236ea is 1,1,1,2,3,3-hexafluoropropane, HFC-245eb is 1,1,1,2,3-pentafluoropropane, and HFC-245cb is 1,1 , 1,2,2-pentafluoropropane.

  As the hydrofluorocarbon, a commercially available product can be used, but the present invention is not limited thereto. For example, the hydrofluorocarbon may be produced by hydrogen reduction of a hydrofluorocarbon having a double bond. For example, hydrogen reduction of hexafluoropropane yields HFC-236ea, and hydrogen reduction of 1,2,3,3,3-pentafluoropropene (HFO-1225ye) yields HFC-245eb.

  In the production method of the present embodiment, as described above, the catalyst includes a chromium-based catalyst containing a Group 5 metal. Thereby, a fluorinated olefin can be produced with a higher conversion and selectivity.

  Specific examples of the Group 5 element include vanadium, niobium, tantalum, and the like. Vanadium, niobium, and the like are preferable in terms of availability and performance, and niobium is particularly preferable. The Group 5 element may contain only one kind or two or more kinds.

  The group 5 element preferably exists in a tetravalent to pentavalent state. In this case, as a raw material for preparing the catalyst, a compound containing a group 5 element of 0 to 3 valences may be used, and in the process of producing the catalyst, the group 5 element is oxidized to 4 to 5 valences. Can be.

  The amount of the Group 5 element is not particularly limited. However, from the viewpoint of suppressing a decrease in selectivity, the ratio of the number of Group 5 metal atoms contained in the chromium oxide is 0.1% or more to the total number of metal atoms contained in the chromium oxide. %, More preferably 0.5% or more and 15% or less. Further, when the Group 5 element is vanadium, the ratio of the number of vanadium atoms contained in chromium oxide is 0.1% or more and 50% or less with respect to the total number of metal atoms contained in chromium oxide. It is more preferably 0.5% or more and 15% or less, particularly preferably 0.5% or more and 3% or less.

  The chromium-based catalyst containing a Group 5 metal is not particularly limited as long as it contains chromium, and examples thereof include chromium oxide and chromium oxyfluoride catalysts. A particularly preferred chromium-based catalyst is chromium oxide. The valence of chromium in chromium oxide is not particularly limited, and may be, for example, three or more. The valence of chromium can be measured by a known method.

  If the chromium-based catalyst is chromium oxide, it can be produced, for example, as follows.

  First, an aqueous solution of a chromium salt and aqueous ammonia are mixed to obtain chromium hydroxide precipitate. Examples of the chromium salt include chromium nitrate, chromium chloride, chrome alum, chromium sulfate and the like. For example, precipitation of chromium hydroxide can be obtained by dropping about 1 equivalent or more of aqueous ammonia to 1 equivalent of chromium nitrate in an aqueous solution of chromium nitrate.

  The precipitate is filtered, washed and dried. Drying may be performed, for example, in air at about 70 to 200 ° C., particularly about 120 ° C., for about 1 to 100 hours, particularly about 12 hours. The product at this stage is called the chromium hydroxide state. The product is then broken up.

  The chromium hydroxide powder obtained by crushing is pelletized by a tableting machine. The pellet may have, for example, a diameter of about 3.0 mm and a height of about 3.0 mm. At the time of pellet formation, additives such as graphite may be mixed.

  Preferably, the formed pellets are fired to form chromium oxide.

  Chromium oxide can be prepared as described above.

  The Group 5 element may be present at the same time as a chromium-based catalyst such as chromium oxide, and the state of the Group 5 element is not particularly limited. For example, the Group 5 element may be unevenly distributed on the surface of the chromium-based catalyst, or the Group 5 element may be uniformly mixed with the chromium-based catalyst. In these cases, the Group 5 element may be present as a metal, or may be present in the form of an oxide or oxyfluoride, but may be present in the form of an oxide or oxyfluoride. preferable. Further, part or all of the Group 5 element may be combined with chromium metal to form a complex oxide. The chromium oxide containing a Group 5 element may be in a crystalline state or an amorphous state. Alternatively, a mixture of a crystalline oxide and an amorphous oxide can be used.

  The method for producing a chromium-based catalyst containing a Group 5 metal is not particularly limited. For example, as a method for producing chromium oxide containing a group V element, chromium oxide or chromium hydroxide which is a precursor thereof is added to a solution containing a group V element to impregnate the group V element. Then, the solvent is removed, and the residue is calcined (impregnation method); from a solution containing Group 5 element in addition to Cr, Cr and Group 5 element are hydroxide, ammonium salt, carbonate, hydrogen carbonate. After precipitating as such, the precipitate is washed, dried, and calcined (coprecipitation method); the solution containing Cr and the Group 5 element is subjected to a hydrothermal synthesis reaction to remove Cr and the Group 5 from the solution. A method of precipitating the element and then calcining the separated precipitate (hydrothermal synthesis method): a salt containing Cr and a Group 5 element, an oxide containing Cr and a Group 5 element, and the like are physically converted using a mortar or the like. And then, if necessary, firing the mixture (kneading method) Etc. can be exemplified. In addition, after a metal salt containing a Group 5 element having sublimability, for example, niobium chloride, vanadium chloride, tantalum chloride, and the like, and chromium oxide are physically mixed using a mortar or the like, the sublimation of the sublimable metal salt is performed. A method in which a sublimated metal salt is vapor-deposited on chromium oxide by heating to a temperature equal to or higher than a temperature and, if necessary, the sublimable metal salt is decomposed and supported on chromium oxide as a metal or metal oxide (chemical vapor deposition method; CVD method). And the like (see Japanese Patent Application Laid-Open No. 2015-509096).

  The chromium oxide used as the catalyst may be fluorinated, so-called fluorinated chromium oxide. This fluorination method may be in accordance with a known method.

  Further, the catalyst can be used by being supported on a carrier such as alumina, aluminum fluoride, aluminum fluoride oxide, and activated carbon.

  As the catalyst, a chromium-based catalyst containing the above-described group V element may be used alone, or together with the above-mentioned chromium-based catalyst containing a group V element as long as the effect of the present invention is not impaired. Alternatively, another catalyst may be used in combination. In the chromium oxide containing a Group 5 element, a catalyst to which a component other than the Group 5 metal is further added may be used. Specifically, examples of the component other than the Group 5 metal include metals such as indium, gallium, nickel, copper, and zinc, and oxides, fluorides, and oxyfluorides of the metal. In addition, non-metals such as carbon can be exemplified as components other than the Group 5 metals.

  When a component other than the Group 5 metal coexists with chromium oxide, the content of chromium can be 30% or more, preferably 50% or more, more preferably 50% or more of the total number of atoms contained in chromium oxide. 90% or more.

  Next, the reverse conditions of the first reaction step other than those described above will be described.

  In the dehydrofluorination reaction of hydrofluorocarbon in the first reaction step, the reaction pressure is not particularly limited, and the reaction can proceed under reduced pressure, normal pressure, or increased pressure. In particular, a reaction under normal pressure is advantageous in equilibrium as compared with a reaction under pressure, and has an advantage that a relatively large apparatus is not required as compared with a reaction under reduced pressure.

  There is no particular limitation on the reactor for performing the first reaction step, and a reactor made of a material such as Hastelloy, Inconel, or Monel can be used.

  The upper limit of the reaction temperature of dehydrofluorination in the first reaction step is preferably 380 ° C., more preferably 380 ° C., from the viewpoint of suppressing waste of energy, decrease in selectivity and deterioration of the catalyst. The temperature is 350 ° C, more preferably 330 ° C, particularly preferably 300 ° C. In addition, the lower limit of the reaction temperature of the dehydrofluorination in the first reaction step is preferably in the case of normal pressure from the viewpoint that the conversion is easily prevented from unacceptably low in terms of productivity. The temperature is 50 ° C, more preferably 100 ° C, further preferably 200 ° C, particularly preferably 230 ° C, and particularly preferably 270 ° C.

  Normally, the dehydrofluorination reaction of hydrofluorocarbon needs to be performed at a relatively high temperature. However, in the production method of the present embodiment, the reaction is performed using the above-described specific catalyst, and the activity of the catalyst is reduced. Since it is high, it is possible to react at a lower temperature than before. Therefore, by reacting at a low temperature, it is possible to further reduce by-products that are likely to be generated when reacting at a high temperature, and it is easy to suppress a decrease in the catalyst life.

The contact time in the first reaction step is not particularly limited, and may be, for example, 0.1 to 300 seconds. Also, the value of W / F0 (g · sec · ml ⁻¹ ) is not particularly limited, and may be, for example, 0.1 to 350. F0 (Nml · sec ⁻¹ ) is the supply amount of the gas containing the raw material to the reactor, and W (g) is the amount of the catalyst charged in the reactor.

  In the first reaction step, there is no limitation on the method of supplying the hydrofluorocarbon to the reactor. For example, the hydrofluorocarbon can be supplied to the first reaction step with the accompanying oxygen gas. In this case, the flow rate (mol / min) of the oxygen gas can be, for example, 0.1% or more and 30% or less, and 0.5% or more and 15% or less with respect to the flow rate (mol / min) of the hydrofluorocarbon. Is preferably 1% or more and 10% or less. As a result, a decrease in the catalytic activity is easily suppressed, and the desired fluorinated olefin can be obtained at a high selectivity continuously for a long period of time.

Further, when supplying the hydrofluorocarbon to the reactor, a gas such as nitrogen, helium, or argon, which is inert to the raw material or the catalyst, may be allowed to coexist. However, if an inert gas is mixed with the raw material, it becomes necessary to separate and recover the target substance and the inert gas by rectification or extractive distillation. In this case, since the inert gas N ₂ is a non-condensable gas, the N ₂ and the organic component including the target substance are collected and collected. For this reason, there is a possibility that the recovery rate of the target object may decrease. From such a viewpoint, in supplying the hydrofluorocarbon to the reactor, the content of the inert gas with respect to the total amount of the hydrofluorocarbon and the inert gas is preferably less than 50 mol%, more preferably less than 10 mol%, and particularly preferably. Is less than 2 mol%, and most preferably, no inert gas is allowed to coexist with the hydrofluorocarbon.

  In the dehydrofluorination reaction in the first reaction step, for example, the raw material is continuously supplied from the inlet of the reactor, the reaction is performed in the reactor, and the product is continuously discharged from the outlet of the reactor. The reaction can be carried out in a system (so-called continuous reaction system).

  Further, the dehydrofluorination reaction may be carried out in any of a gas phase state and a liquid phase state depending on the reaction temperature, but from the viewpoint of obtaining the desired fluorinated olefin with a high selectivity. The reaction is preferably performed in a gas phase.

  Through the above first reaction step, the desired fluorine-containing olefin is produced.

Fluorine-containing olefin of the general formula ^{(2) R f CF = CHZ} ( where, R ^f and Z have the general formula (1) is the same) is represented by.

Although the specific fluorinated olefin depends on the type of the hydrofluorocarbon as a raw material, for example, if HFC-245eb or HFC-245cb is used as the hydrofluorocarbon, the obtained fluorinated olefin is 1,1, It becomes 1,2-tetrafluoropropene (HFO-1234yf). If HFC-236ea is used as the hydrofluorocarbon, the obtained fluorinated olefin will be 1,2,3,3,3-pentafluoropropene (HFO-1225ye). Similarly, if 1,1,2,2,3-pentafluoropropane (HFC-245ca) is used as the hydrofluorocarbon, the resulting fluorinated olefin will be 1,1,2,3-pentafluoropropene (HFO-1234ye). ).
The reaction product of the dehydrofluorination reaction in the first reaction step can be extracted, for example, by discharging it from the outlet of the reactor.

  In the production method of the present embodiment, the conversion of hydrofluorocarbon, which is the raw material after the dehydrofluorination reaction, is high, and the selectivity of the target fluorine-containing olefin is also high. Therefore, for example, after the first reaction step, the content ratio of the target fluorine-containing olefin to the flow rate S (mol / min) of all products discharged from the reactor in which the first reaction step is performed is large. It becomes. That is, the content ratio of by-products to the flow rate S (mol / min) of all products is small. Hereinafter, a specific example will be described.

For example, when the hydrofluorocarbon is HFC-245eb, the target fluorinated olefin is HFO-1234yf, but usually, as a by-product, E-form 1,3,3,3-pentafluoropropene ( Hereinafter, HFO-1234ze), Z-form HFO-1234ze and 1,1,1,3,3-pentafluoropropane (hereinafter abbreviated as HFC-245fa) are produced. 245cb and CO ₂ may also be by-produced. In particular, the E-form and the Z-form of HFO-1234ze and HFC-245fa may reduce the performance of the target product.

  In this regard, in the manufacturing method of the present embodiment, the amounts of the E-form and the Z-form of HFO-1234ze and HFC-245fa are reduced. Specifically, after the first reaction step, the flow rate S (mol / min) of all products discharged from the reactor in which the first reaction step is performed is defined as the flow rate of E-form and Z-form contained in the total products. When the sum of the flow rate of HFO-1234ze and the flow rate of HFC-245fa is S1 (mol / min), the ratio of the total S1 (mol / min) to the flow rate S (mol / min) can be 20% or less. That is, the ratio of by-products contained in all products is low, and the ratio of HFO-1234yf, which is the target product, can be high. More preferably, the total S1 (mol / min) is 10% or less, particularly preferably 5% or less, based on the flow rate S (mol / min) of all products.

  As described above, in the production method of the present embodiment, since the selectivity of the target substance is high, the fluorine-containing olefin that is the target substance can be produced with high purity. Therefore, the effluent discharged from the reactor after the first reaction step can be used as it is as a fluorine-containing olefin without purification.

  The effluent obtained as described above may be purified to obtain a fluorine-containing olefin with higher purity. By performing this purification, a fraction containing unreacted hydrofluorocarbon, by-products, and the like can be obtained, and this fraction can be reused. In short, in the production method of the present embodiment, after the first reaction step, a separation step of separating part or all of the effluent from the reactor in which the first reaction step is performed into at least two or more fractions is performed. be able to. Hereinafter, a specific example will be described.

  For example, when the hydrofluorocarbon is at least one selected from the group consisting of HFC-236ea, HFC-245eb and HFC-245cb, after the first reaction step, the effluent from the reactor in which the first reaction step is performed May contain HFC-245eb in addition to the target product HFO-1234yf and the by-products described above. This HFC-245eb is an unreacted material if the raw material hydrofluorocarbon includes HFC-245eb, while if the raw material is not HFC-245eb but HFC-236ea or HFC-245cb, it is a by-product. HFC-245eb.

  In any case, the separation step can separate part or all of the effluent from the reactor in which the first reaction step is performed into a first fraction and a second fraction. The means for this separation is not particularly limited, but for example, it can be separated by a distillation operation utilizing a difference in boiling point. By performing such a separation step, for example, a fraction (referred to as a first fraction) in which the HFC-245eb concentration is higher than before the separation step and the HFC-245eb concentration are lower than before the separation step (A second fraction).

  After the separation step, if a part or all of the first fraction is dehydrofluorinated, HFC-245eb in the first fraction is dehydrofluorinated, whereby HFO-1234yf can be obtained. it can. Therefore, the raw material hydrofluorocarbon (HFC-245eb) can be effectively used, and HFO-1234yf can be efficiently produced.

  In performing the dehydrofluorination of HFC-245eb contained in the first fraction, the HFC-245eb may be performed in the above-described first reaction step. That is, after the effluent obtained in the first reaction step is separated into a first fraction and a second fraction in a separation step, the obtained first fraction is recycled to the first reaction step again. You may. In this case, HFO-1234yf can be manufactured more efficiently, and the conversion of the raw material and the selectivity of the target product can be further increased.

  Of course, the dehydrofluorination of HFC-245eb contained in the first fraction may be performed in a reaction step different from the first reaction step (for example, referred to as a second reaction step). Also in this second reaction step, the dehydrofluorination reaction can be performed under the same conditions as in the first reaction step.

  Further, for example, when the hydrofluorocarbon is at least one selected from the group consisting of HFC-236ea, HFC-245eb and HFC-245cb, after the first reaction step, the outflow from the reactor in which the first reaction step is performed is performed. The product may include unreacted HFC-245cb in addition to the desired product, HFO-1234yf. This HFC-245cb is an unreacted product if the hydrofluorocarbon contains HFC-245cb, while if the raw material is not HFC-245cb but HFC-236ea or HFC-245eb, by-product HFC-245cb is produced. 245 cb.

  Also in this case, if the separation step is performed in the same manner as described above, part or all of the effluent from the reactor in which the first reaction step is performed can be divided into two types of fractions (the third fraction and the fourth fraction, respectively). To). For example, the third fraction is a fraction in which the HFC-245cb concentration is higher than before the separation step, and the fourth fraction is a fraction in which the HFC-245cb concentration is lower than before the separation step. It is.

  After the separation step, if at least a part of the third fraction is dehydrofluorinated, HFC-245cb in the third fraction is defluorinated to obtain HFO-1234yf. As a result, the raw material hydrofluorocarbon (HFC-245cb) can be effectively used, and HFO-1234yf can be efficiently produced.

  The dehydrofluorination of HFC-245cb contained in the third fraction may be performed in the first reaction step described above. That is, after the effluent obtained in the first reaction step is separated into a third fraction and a fourth fraction in a separation step, the obtained third fraction is recycled to the first reaction step again. You may. In this case, HFO-1234yf can be manufactured more efficiently, and the conversion of the raw material and the selectivity of the target product can be further increased.

  Further, as in the case of the first fraction described above, the dehydrofluorination of HFC-245cb contained in the third fraction may be performed in the second reaction step.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
The dehydrofluorination reaction in the first reaction step was performed using HFC-245eb as the hydrofluorocarbon. A tubular reactor was charged with 150 g of a chromium oxide catalyst (a chromium-based catalyst containing a Group 5 metal) to which 10% of niobium oxide was added based on the total number of atomic moles of niobium and chromium. As a pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through a reactor containing the catalyst, and the reactor was heated to a maximum of 350 ° C. to perform a fluorination treatment.

Nitrogen was passed through the pretreated catalyst layer at 1 L / min, and the reactor was heated by an electric furnace. After the reactor reached a predetermined temperature (350 ° C. in this example), the introduction of HFC-245eb into the reactor was started and the nitrogen supply was reduced instead. The flow of HFC-245eb is increased so that the initial heat generation does not become excessive, and the flow rate of nitrogen is reduced by the increased amount. Finally, the flow rate of HFC-245eb is 900 NmL / min. Was adjusted to 0. Thereafter, oxygen gas was introduced. Oxygen gas was introduced from the inlet of the reactor so as to be 10 mol% with respect to the flow rate of HFC-245eb to be introduced. The operating conditions for the reaction were a pressure of 0.0 MPaG (G indicates a gauge pressure), a reaction temperature of 350 ° C., and a W / F0 of 10 g · sec · ml ⁻¹ .

  The dehydrofluorination reaction in the first reaction step was performed as described above, and the component composition of the effluent extracted from the reactor outlet was analyzed using a gas chromatograph. The results are shown in Table 1 below.

(Example 2)
The dehydrofluorination reaction in the first reaction step was performed using HFC-245eb as the hydrofluorocarbon. As the catalyst, 150 g of a chromium oxide catalyst (a chromium-based catalyst containing a Group 5 metal) in which 1% of vanadium oxide was added to the total atomic mole number of vanadium and chromium was charged into a tubular reactor. As a pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through a reactor containing the catalyst, and the reactor was heated to a maximum of 350 ° C. to perform a fluorination treatment.

Nitrogen was passed through the pretreated catalyst layer at 1 L / min, and the reactor was heated by an electric furnace. After the reactor reached a predetermined temperature (350 ° C. in this example), the introduction of HFC-245eb into the reactor was started and the nitrogen supply was reduced instead. The flow of HFC-245eb is increased so that the initial heat generation does not become excessive, and the flow rate of nitrogen is reduced by the increased amount. Finally, the flow rate of HFC-245eb is 900 NmL / min. Was adjusted to 0. Thereafter, oxygen gas was introduced. Oxygen gas was introduced from the reactor inlet so as to be 2 mol% with respect to the flow rate of HFC-245eb to be introduced. The operating conditions for the reaction were a pressure of 0.0 MPaG (G indicates a gauge pressure), a reaction temperature of 350 ° C., and a W / F0 of 10 g · sec · ml ⁻¹ .

  The dehydrofluorination reaction in the first reaction step was performed as described above, and the component composition of the effluent extracted from the reactor outlet was analyzed using a gas chromatograph. The results are shown in Table 1 below.

(Comparative Example 1)
The dehydrofluorination reaction in the first reaction step was performed using HFC-245eb as the hydrofluorocarbon. As the catalyst, a chromium oxyfluoride catalyst obtained by fluorinating chromium oxide (a chromium-based catalyst containing no Group 5 metal) was used. In addition, as a pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through a reactor containing the catalyst, and the reactor was heated to a maximum of 350 ° C. to perform a fluorination treatment.

The pretreated catalyst was accommodated in a reactor for performing a dehydrofluorination reaction, and the reactor was heated with an electric furnace in a nitrogen stream. After the reactor reached a predetermined temperature (420 ° C. in this example), HFC-245eb was introduced into the reactor, and the supply of nitrogen was stopped. Oxygen gas was appropriately introduced from the reactor inlet so as to be 10 mol% with respect to HFC-245eb at the reactor inlet. The operating conditions for the reaction were a pressure of 0.0 MPaG (G indicates a gauge pressure), a reaction temperature of 420 ° C., and a W / F0 of 164 g · sec · ml ⁻¹ .

  The dehydrofluorination reaction in the first reaction step was performed as described above, and the component composition of the effluent extracted from the reactor outlet was analyzed using a gas chromatograph. The results are shown in Table 1 below.

  In Table 1, 245eb is 1,1,1,2,3-pentafluoropropane, 1234yf is 2,3,3,3-tetrafluoropropene, and 245cb is 1,1,1,2,2 -Pentafluoropropane, 1234ze indicates 1,3,3,3-pentafluoropropene, and 245fa indicates 1,1,1,3,3-pentafluoropropane.

  Table 1 shows the type of catalyst used, the reaction temperature, and the selectivity of each component (conversion rate for HFO-245eb) detected by gas chromatography.

  In Examples 1 and 2, since the dehydrofluorination reaction is carried out using a chromium-based catalyst containing a Group 5 metal as a catalyst, the selectivity of HFC-245eb as a raw material is high, and HFO as an objective substance is obtained. It can be seen that -1234yf was manufactured with a high selectivity. On the other hand, in Comparative Example 1, a chromium-based catalyst containing no Group V metal was used as the catalyst, so that the conversion of the raw material was higher than in Examples 1 and 2, despite the higher reaction temperature and contact time. The selectivity of HFO-1234yf, which was low, was low.

Claims (9)

In a method for producing a fluorinated olefin through a first reaction step in which dehydrofluorination of a hydrofluorocarbon is performed in the presence of a catalyst,
The hydrofluorocarbon is represented by the general formula (1) R ^f CFYCHZ ₂ (In the general formula (1), R ^f is a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms and does not contain chlorine. , Y and Z are each independently H or F, but when all Z are H, then Y is F).
The method for producing a fluorinated olefin, wherein the catalyst is a chromium-based catalyst containing a Group 5 metal. The method for producing a fluorinated olefin according to claim 1, wherein in the general formula (1), R ^f is CF ₃ .   The method for producing a fluorine-containing olefin according to claim 2, wherein the hydrofluorocarbon includes at least one selected from the group consisting of HFC-236ea, HFC-245eb, and HFC-245cb.   The method for producing a fluorinated olefin according to claim 3, wherein the hydrofluorocarbon is HFC-245eb.   5. The catalyst according to claim 1, wherein the proportion of the number of Group 5 metal atoms contained in the catalyst is 0.1% or more and 50% or less based on the total number of metal atoms contained in the catalyst. A method for producing a fluorine-containing olefin.   The method for producing a fluorine-containing olefin according to any one of claims 1 to 5, wherein the dehydrofluorination in the first reaction step is performed at 50 to 380 ° C.   The method for producing a fluorine-containing olefin according to any one of claims 1 to 6, wherein the dehydrofluorination in the first reaction step is performed at 100 to 350 ° C.   The method for producing a fluorinated olefin according to any one of claims 1 to 7, wherein the hydrofluorocarbon is supplied to the first reaction step with accompanying oxygen gas.   The method according to claim 8, wherein a flow rate (mol / min) of the oxygen gas is 0.1% or more and 10% or less with respect to a flow rate (mol / min) of the hydrofluorocarbon.