JP2016222597A - Manufacturing method of fluorine-containing olefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing fluorine-containing olefin at high conversion reaction and high selectivity in a process for manufacturing the fluorine-containing olefin by a dehydrofluorination reaction of hydrofluorocarbon.SOLUTION: There is provided a method for manufacturing fluorine-containing olefin through a first reaction process where a dehydrofluorination reaction of hydrofluorocarbon is conducted in presence of a catalyst. The hydrofluorocarbon is a compound represented by the general formula (1) RCFYCHZ, where Ris a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms and having no chlorine, Y and Z are each independently H or F, but Y is F when all of Z are H. The catalyst is a chromium-based catalyst containing Group 5 metal.SELECTED DRAWING: None

Description

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

Fluoroolefins represented by general formula: CF ₃ (CX ₂ ) _n CF═CH ₂ , general formula: CF ₃ (CX ₂ ) _n CH═CHF, etc. (where X is halogen) are various functional materials. , A solvent, a refrigerant, a foaming agent and the like, and a compound useful as a monomer for producing a functional polymer or a raw material thereof. 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) It is regarded as a promising refrigerant compound with 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 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- is obtained through the following reaction steps. 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, a reaction process is also known in which HFO-1243zf is fluorinated to obtain HFC-245eb as shown in the following reaction formula (5), and then 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, HFO-1234yf is produced by the dehydrofluorination reaction of HFC-245eb in any reaction step. Various studies have been made on such a dehydrofluorination reaction (see, for example, Patent Documents 2 to 4), and the HFO- is efficiently adjusted by appropriately adjusting the type of catalyst, reaction temperature, contact time, and the like. A method for producing a fluorine-containing olefin such as 1234yf has been proposed.

JP 2012-77086 A Special table 2009-542651 gazette Special table 2011-515457 gazette Special table 2009-513719

However, in order to carry out the dehydrofluorination reaction of hydrofluorocarbons such as 245eb, a large amount of catalyst is required, and in addition, the reaction temperature needs to be relatively high. For this reason, in the conventional method, there is a problem that not only the target product 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 reduced may be solved by entraining oxygen, but in this case, the combustion of the raw material and the target product is promoted, so that the yield is reduced.

  The present invention has been made in view of the above, and in a process for producing a fluorinated olefin by a hydrofluorocarbon dehydrofluorination reaction, the target fluorinated olefin is obtained with a high conversion rate and a high selectivity. The object is to provide a method of manufacturing.

  As a result of intensive research to achieve the above object, the present inventor has obtained a chromium-based catalyst containing a Group 5 metal as a catalyst in a reaction for producing a fluorinated olefin by dehydrofluorination of hydrofluorocarbon. By using it, it discovered that the said objective could be achieved and came to complete this invention.

That is, this invention relates to the manufacturing method of the following fluorine-containing olefin.
Item 1.
In the method for producing a fluorinated olefin through a first reaction step in which hydrofluorocarbon dehydrofluorination is performed in the presence of a catalyst,
The hydrofluorocarbon has 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 Z is all H, 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.
In the general formula (1), R ^f is CF _3, process for producing a fluorinated olefin according to 1.
Item 3.
Item 3. The method for producing a fluorinated olefin according to Item 2, wherein the hydrofluorocarbon contains 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 5 metal contained in the catalyst is 0.1% to 50% with respect to the total number of metal atoms contained in the catalyst, according to any one of Items 1 to 4 above. A method for producing a fluorine-containing olefin.
Item 6.
Item 6. The method for producing a fluorinated 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 used in the first reaction step with oxygen gas.
Item 9.
Item 9. The method according to Item 8, wherein the flow rate (mol / min) of 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 dehydrofluorination reaction of a specific hydrofluorocarbon is performed using a chromium-based catalyst containing a Group 5 metal as a catalyst. Thereby, the conversion rate of hydrofluorocarbon can be made high, and a target object can be obtained with high selectivity. Even if the dehydrofluorination reaction is carried out at a low temperature, the desired product can be obtained with a high conversion rate 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 the hydrofluorocarbon is dehydrofluorinated in the presence of a catalyst. In particular, in this embodiment, the catalyst includes a chromium-based catalyst including a Group 5 metal. In the method for producing a fluorinated olefin of the present embodiment, by using the above catalyst, the conversion of the hydrofluorocarbon can be increased, and the target product can be obtained with a high selectivity. Even if the dehydrofluorination reaction is carried out at a low temperature, the desired product can be obtained with a high conversion rate 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 general formula (1), ^Rf is a C1-C3 linear or branched perfluoroalkyl group, does not contain chlorine, and Y and Z are each independently H or F. If Y is all H, then Y is F. Hydrofluorocarbons have the advantage that there is no need for 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 with a higher conversion and selectivity.

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

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

  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.

  A commercially available product can be used as the hydrofluorocarbon. However, the hydrofluorocarbon is not limited to this. For example, the hydrofluorocarbon may be produced by hydrogen reduction of a hydrofluorocarbon having a double bond. For example, HFC-236ea is obtained by hydrogen reduction of hexafluoropropane, and HFC-245eb is obtained by hydrogen reduction of 1,2,3,3,3-pentafluoropropene (HFO-1225ye).

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

  Specific examples of the Group 5 element include vanadium, niobium, tantalum and the like, and vanadium, niobium and the like are preferable in terms of availability and performance, and niobium is particularly preferable. The Group 5 element may be included alone or in combination of two or more.

  The Group 5 element is preferably present in a tetravalent to pentavalent state. In this case, as a raw material for preparing the catalyst, a compound containing a 0-3 valent group 5 element may be used. In the catalyst manufacturing process, the 5th group element is oxidized to 4-5 valence. Can do.

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

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

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

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

  This precipitate is washed by filtration and then dried. The 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 disintegrated.

  The chromium hydroxide powder obtained by crushing is pelletized by a tableting machine. For example, the pellet may have a diameter of about 3.0 mm and a height of about 3.0 mm. In forming the pellet, an additive such as graphite may be mixed.

  It is preferable to fire the molded pellets to make chromium oxide.

  As described above, chromium oxide can be prepared.

  The Group 5 element only needs to be present at the same time as the chromium-based catalyst such as chromium oxide, and the presence 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 exist as a metal, or may exist in the state of an oxide, oxyfluoride, etc., but may exist in the state of an oxide, oxyfluoride. preferable. Further, part or all of the Group 5 element may be combined with chromium metal to form a composite oxide. The chromium oxide containing a Group 5 element may be in a crystalline state or an amorphous state. A mixture of a crystalline oxide and an amorphous oxide can also be used.

  A 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 5 element, a solution containing a Group 5 element was added with chromium oxide or its precursor chromium hydroxide and impregnated with the Group 5 element. Thereafter, the solvent is removed, and the residue is fired (impregnation method); Cr and the Group 5 element are mixed with Cr, Group 5 element in addition to Cr, hydroxide, ammonium salt, carbonate, bicarbonate After the precipitate is precipitated, the precipitate is washed, dried, and then fired (coprecipitation method); a solution containing Cr and a Group 5 element is subjected to a hydrothermal synthesis reaction, whereby Cr and Group 5 are removed from the solution. Method of precipitating elements and then firing the separated precipitate (hydrothermal synthesis method): Physically using a mortar or the like with a salt containing Cr and a Group 5 element, an oxide containing Cr and a Group 5 element, etc. Mixing and then firing this mixture if necessary (kneading method) Etc. can be exemplified. In addition, 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, and then the sublimation metal salt is sublimated. A method in which the sublimated metal salt is vapor-deposited on chromium oxide by heating above the temperature, and the sublimable metal salt is decomposed and supported on chromium oxide as a metal or metal oxide if necessary (chemical vapor deposition method; CVD method) Etc. (see JP-A-2015-509096, etc.).

  The chromium oxide used as the catalyst may be fluorinated so-called fluorinated chromium oxide. This fluorination method may follow a known method.

  The catalyst can also be used by being supported on a carrier such as alumina, aluminum fluoride, aluminum fluoride oxide, activated carbon or the like.

  As the catalyst, a chromium-based catalyst containing the above-mentioned group 5 element may be used alone, or together with a chromium-based catalyst containing the above-mentioned group 5 element as long as the effect of the present invention is not hindered. Other catalysts may be used in combination. Moreover, in the chromium oxide containing said group 5 element, you may use the catalyst in which components other than the group 5 metal were further added. Specific 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 metals. In addition, as a component other than the Group 5 metal, nonmetals such as carbon can be exemplified.

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

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

  In the hydrofluorocarbon dehydrofluorination reaction 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 restriction | limiting in particular as a reactor which performs a 1st reaction process, The reactor comprised by materials, such as HASTELLOY, INCONEL, INCONEL, MONEL, can be used.

  The upper limit of the reaction temperature of dehydrofluorination in the first reaction step is preferably 380 ° C., more preferably from the viewpoint of suppressing waste of energy, lowering of selectivity and catalyst deterioration, more preferably at normal pressure. 350 ° C, more preferably 330 ° C, particularly preferably 300 ° C. In addition, the lower limit of the reaction temperature of dehydrofluorination in the first reaction step is preferably from the viewpoint of easily preventing the conversion rate from being unacceptably lowered from the viewpoint of productivity, if it is under normal pressure. 50 ° C, more preferably 100 ° C, further preferably 200 ° C, particularly preferably 230 ° C, and particularly preferably 270 ° C.

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

The contact time in the first reaction step is not particularly limited and can be, for example, 0.1 to 300 seconds. Moreover, the value of W / F0 (g * sec * ml < ^-1 >) is not specifically limited, either, For example, it can be set to 0.1-350. Note that F0 (Nml · sec ⁻¹ ) is the amount of gas containing the raw material supplied to the reactor, and W (g) is the amount of catalyst charged in the reactor.

  In the first reaction step, the method for supplying hydrofluorocarbon to the reactor is not limited. For example, the hydrofluorocarbon can be supplied to the first reaction step with 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. Thereby, the fall of catalyst activity becomes easy to be suppressed and the target fluorine-containing olefin can be obtained with a high selectivity continuously for a long period of time.

In addition, when supplying the hydrofluorocarbon to the reactor, a gas inert to the raw material or catalyst such as nitrogen, helium, or argon may coexist. However, when an inert gas is mixed with the raw material, it is necessary to separate and recover the target product and the inert gas by rectification or extractive distillation. In this case, since the inert gas N ₂ is a non-condensable gas, the organic component containing N ₂ and the target product is accompanied and recovered. Therefore, there is a possibility that the recovery rate of the target product is lowered. From this point of view, when 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%, particularly preferably. Is less than 2 mol%, and most preferably the inert gas is not 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 and the reaction is performed in the reactor, and then the product is continuously discharged from the outlet of the reactor. It can be made to react in a system (so-called continuous reaction system).

  In addition, the dehydrofluorination reaction may be performed in either a gas phase state or a liquid phase state depending on the reaction temperature, but from the viewpoint of obtaining the desired fluorine-containing olefin with high selectivity. It is preferable to react in the gas phase.

  The target fluorine-containing olefin is produced through the first reaction step.

The fluorine-containing olefin is represented by the general formula (2) R ^f CF═CHZ (where R ^f and Z are the same as those in the general formula (1)).

The specific fluorine-containing 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 resulting fluorine-containing olefin is 1,1, 1,2-tetrafluoropropene (HFO-1234yf). If HFC-236ea is used as the hydrofluorocarbon, the resulting fluorine-containing olefin will be 1,2,3,3,3-pentafluoropropene (HFO-1225ye). Similarly, when 1,1,2,2,3-pentafluoropropane (HFC-245ca) is used as the hydrofluorocarbon, the resulting fluorine-containing olefin is 1,1,2,3-pentafluoropropene (HFO-1234ye). )
The reaction product of the dehydrofluorination reaction in the first reaction step can be extracted by, for example, discharging from the outlet of the reactor.

  In the production method of this embodiment, the conversion rate of hydrofluorocarbon, which is a raw material after the dehydrofluorination reaction, is high, and the selectivity of the fluorine-containing olefin that is the target product is also high. Therefore, for example, after the first reaction step, the content of the target fluorine-containing olefin is large with respect to the flow rate S (mol / min) of all products discharged from the reactor in which the first reaction step is performed. It becomes. That is, the content ratio of by-products with respect 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 fluorine-containing olefin is HFO-1234yf. Usually, as a by-product, E-form 1,3,3,3-pentafluoropropene ( (Hereinafter abbreviated as HFO-1234ze), Z-form HFO-1234ze and 1,1,1,3,3-pentafluoropropane (hereinafter abbreviated as HFC-245fa), and in addition to these, HFC- 245cb and CO ₂ may also be-product. In particular, E-form and Z-form HFO-1234ze and HFC-245fa are liable to reduce the performance of the target product.

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

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

  Further, the effluent obtained as described above may be purified to obtain a fluorine-containing olefin with higher purity. By carrying out this purification, a fraction containing unreacted hydrofluorocarbon and by-products 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 a 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 of HFC-236ea, HFC-245eb, and HFC-245cb, the effluent from the reactor in which the first reaction step is performed after the first reaction step In addition to the target product HFO-1234yf and the by-products described above, HFC-245eb may also be included. This HFC-245eb is an unreacted material if the raw material hydrofluorocarbon contains HFC-245eb, and on the other hand, if the raw material is not HFC-245eb but HFC-236ea or HFC-245cb, HFC-245eb.

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

  If a part or all of the dehydrofluorination reaction of the first fraction is performed after the separation step, HFC-245eb in the first fraction is dehydrofluorinated, thereby obtaining HFO-1234yf. it can. Therefore, the raw material hydrofluorocarbon (HFC-245eb) can be used effectively, and HFO-1234yf can be produced efficiently.

  The dehydrofluorination of HFC-245eb contained in the first fraction may be performed within the first reaction step described above. That is, after separating the effluent obtained in the first reaction step into the first fraction and the second fraction in the separation step, the obtained first fraction is recycled again to the first reaction step. May be. In this case, HFO-1234yf can be produced more efficiently, and the conversion rate 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 (for example, referred to as a second reaction step) different from the first reaction step. Also in the 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 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 The product may contain unreacted HFC-245cb in addition to the target product HFO-1234yf. This HFC-245cb is an unreacted material if the hydrofluorocarbon contains HFC-245cb, whereas if the raw material is not HFC-245cb but HFC-236ea or HFC-245eb, HFC- 245cb.

  In this case as well, if the separation step is performed in the same manner as described above, a part or all of the effluent from the reactor in which the first reaction step is performed is separated into two types of fractions (the third fraction and the fourth fraction, respectively). Can be separated. For example, the third fraction is a fraction in which the HFC-245cb concentration is higher than that before the separation step, and the fourth fraction is a fraction in which the HFC-245cb concentration is lower than that 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 can be defluorinated to obtain HFO-1234yf. Thereby, the hydrofluorocarbon (HFC-245cb) which is a raw material can be utilized effectively, and HFO-1234yf can be manufactured efficiently.

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

  Moreover, you may perform the dehydrofluorination of HFC-245cb contained in a 3rd fraction at the said 2nd reaction process similarly to the case of the above-mentioned 1st fraction.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the aspect of these Examples.

Example 1
The dehydrofluorination reaction of 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) in which 10% of niobium oxide was added relative to the total number of moles of niobium and chromium. As pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through the reactor containing the catalyst, and the temperature of the reactor was heated to a maximum of 350 ° C. to perform fluorination treatment.

Nitrogen was passed through the pretreated catalyst layer at 1 L / min, and the reactor was heated with 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, the flow rate of nitrogen is decreased by the increased amount, and finally the flow rate of HFC-245eb is a flow rate of 900 NmL / min, the flow rate of nitrogen Was adjusted to 0. Thereafter, oxygen gas was introduced. Oxygen gas was introduced from the reactor inlet so as to be 10 mol% with respect to the flow rate of HFC-245eb to be introduced. The operating conditions of the reaction were a pressure of 0.0 MPaG (G indicates a gauge pressure), a reaction temperature of 350 ° C., and 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 of the first reaction step was performed using HFC-245eb as the hydrofluorocarbon. As a 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 number of moles of vanadium and chromium was charged in a tubular reactor. As pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through the reactor containing the catalyst, and the temperature of the reactor was heated to a maximum of 350 ° C. to perform fluorination treatment.

Nitrogen was passed through the pretreated catalyst layer at 1 L / min, and the reactor was heated with 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, the flow rate of nitrogen is decreased by the increased amount, and finally the flow rate of HFC-245eb is a flow rate of 900 NmL / min, the flow rate of nitrogen 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 of the reaction were a pressure of 0.0 MPaG (G indicates a gauge pressure), a reaction temperature of 350 ° C., and 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 of the first reaction step was performed using HFC-245eb as the hydrofluorocarbon. The catalyst used was a chromium oxyfluoride catalyst (chromium-based catalyst not containing a Group 5 metal) obtained by fluorinating chromium oxide. In addition, as a pretreatment for using the catalyst in the reaction, anhydrous hydrogen fluoride diluted with nitrogen was passed through the reactor containing the catalyst, and the reactor temperature was heated to 350 ° C. at maximum to perform the fluorination treatment.

The pretreated catalyst was accommodated in a reactor for performing a dehydrofluorination reaction, and the reactor was heated by 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 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, 245cb is 1,1,1,2,2 -Pentafluoropropane, 1234ze represents 1,3,3,3-pentafluoropropene, 245fa represents 1,1,1,3,3-pentafluoropropane.

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

  In Examples 1 and 2, since the dehydrofluorination reaction is performed using a chromium-based catalyst containing a Group 5 metal as a catalyst, the selectivity of the raw material HFC-245eb is high, and the target HFO is It can be seen that −1234yf can be produced with high selectivity. On the other hand, in Comparative Example 1, since a chromium-based catalyst not containing a Group 5 metal is used as a catalyst, the conversion rate of the raw material is high although the reaction temperature and contact time are larger than those in Examples 1 and 2. The selectivity of the target product HFO-1234yf was also low.

Claims (9)

In the method for producing a fluorinated olefin through a first reaction step in which hydrofluorocarbon dehydrofluorination is performed in the presence of a catalyst,
The hydrofluorocarbon has 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 Z is all H, 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 R ^f is CF ₃ in the general formula (1).   The manufacturing method of the fluorine-containing olefin of Claim 2 in which the said hydrofluorocarbon contains at least 1 sort (s) chosen from the group 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.   The ratio of the number of atoms of the Group 5 metal contained in the catalyst is 0.1% or more and 50% or less with respect to the total number of metal atoms contained in the catalyst. A method for producing a fluorine-containing olefin.   The method for producing a fluorinated olefin according to any one of claims 1 to 5, wherein dehydrofluorination in the first reaction step is performed at 50 to 380 ° C.   The method for producing a fluorinated olefin according to any one of claims 1 to 6, wherein dehydrofluorination in the first reaction step is performed at 100 to 350 ° C.   The said hydrofluorocarbon is a manufacturing method of the fluorine-containing olefin of any one of Claims 1-7 which encloses oxygen gas and uses for the said 1st reaction process.   The method according to claim 8, wherein the flow rate (mol / min) of oxygen gas is 0.1% or more and 10% or less with respect to the flow rate (mol / min) of the hydrofluorocarbon.