Purification method of 1,2-difluoroethylene (HFO-1132)

Abstract

The present invention provides a method for suppressing the isomerization and loss of HFO-1132 and highly purifying HFO-1132. Specifically, the present invention provides a method for purifying 1,2-difluoroethylene (HFO-1132), which successively includes: step 1 of reducing the amount of water in the above composition by contacting a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and water with zeolite having an average pore diameter; and step 2 of recovering the purified product, wherein the purified product contains HFO-1132(E) and the reduced amount of water, and HFO-1132(Z) is less than 0.1% by volume.

Description

Technical Field

[0001] The present invention relates to a method for purifying 1,2-difluoroethylene (HFO-1132). Background Art

[0002] As a candidate for a substitute refrigerant component for HFC mixed refrigerants such as R410A (a two-component mixed refrigerant of HFC-32 and HFC-125) used as a refrigerant for air conditioners, 1,2-difluoroethylene (HFO-1132) can be cited. In HFO-1132, there are two isomers, trans-1,2-difluoroethylene (HFO-1132(E)) and cis-1,2-difluoroethylene (HFO-1132(Z)).

[0003] As a purification method for reducing the above-mentioned water and other impurities from a composition containing HFO-1132 and water, a method of dehydrating by bringing the composition into contact with zeolite (molecular sieve), calcium chloride, silica gel, activated carbon, concentrated sulfuric acid, etc. is generally known. For example, in Patent Document 1, it is described that dehydration is carried out by bringing a fluid containing HFO-1132 into contact with synthetic zeolite.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2015 / 125877 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] An object of the present invention is to provide a method for purifying HFO-1132 with high purity while suppressing isomerization and loss of HFO-1132.

[0009] Technical Solution for Solving the Technical Problem

[0010] The present invention includes the following solutions.

[0011] Item 1. A method for purifying 1,2-difluoroethylene (HFO-1132), which sequentially has:

[0012] Step 1 of reducing the amount of water from the composition by bringing a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and water into contact with zeolite having an average pore diameter of ; and

[0013] Step 2 of recovering the purified product, wherein the purified product contains HFO-1132(E) and the reduced amount of water, and HFO-1132(Z) is less than 0.1% by volume.

[0014] Item 2. A method for purifying 1,2-difluoroethylene (HFO-1132), which successively includes:

[0015] Step 1 of reducing the amount of water in the above composition by contacting a composition containing cis-1,2-difluoroethylene (HFO-1132(Z)) and water with zeolite having an average pore diameter of ; and

[0016] Step 2 of recovering the purified product, wherein the above purified product contains HFO-1132(Z) and the reduced amount of water, and HFO-1132(E) is less than 0.1% by volume.

[0017] Item 3. A method for purifying 1,2-difluoroethylene (HFO-1132), which includes:

[0018] Step 1 of reducing the amount of water in the above composition by passing a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and water through a column having zeolite with an average pore diameter of ;

[0019] When passing through the above column, the isomerization rates of HFO-1132(E) and HFO-1132(Z) follow the following formula:

[0020] (1132(E)(% at inlet) / (1132(E,Z)(% at inlet)) -

[0021] (1132(E)(% at outlet) / (1132(E,Z)(% at outlet)) < 0.01, and

[0022] (1132(Z)(% at inlet) / (1132(E,Z)(% at inlet)) -

[0023] (1132(Z)(% at outlet) / (1132(E,Z)(% at outlet)) < |0.01|.

[0024] Item 4. A method for purifying 1,2-difluoroethylene (HFO-1132), including:

[0025] Step 1 of reducing the amount of water in the above composition by passing a composition containing cis-1,2-difluoroethylene (HFO-1132(Z)) and water through a column having zeolite with an average pore diameter of ;

[0026] When passing through the above column, the isomerization rates of HFO-1132(E) and HFO-1132(Z) follow the following formula:

[0027] (1132(E)(% at inlet) / (1132(E,Z)(% at inlet)) -

[0028] (1132(E)(Exit%) / (1132(E,Z)(Exit%)) < |0.01|, and

[0029] (1132(Z)(Entry%) / (1132(E,Z)(Entry%)) -

[0030] (1132(Z)(Exit%) / (1132(E,Z)(Exit%)) < 0.01.

[0031] Item 5. A method for purifying 1,2 - difluoroethylene (HFO - 1132), comprising:

[0032] Passing a composition containing trans - 1,2 - difluoroethylene (HFO - 1132(E)), cis - 1,2 - difluoroethylene (HFO - 1132(Z)) and water through a column of zeolite having an average pore diameter of to reduce the amount of the above - mentioned water from the above - mentioned composition in Step 1,

[0033] When passing through the above - mentioned column, the isomerization rates of HFO - 1132(E) and HFO - 1132(Z) follow the following formula:

[0034] (1132(E)(Entry%) / (1132(E,Z)(Entry%)) -

[0035] (1132(E)(Exit%) / (1132(E,Z)(Exit%)) < |0.01|, and

[0036] (1132(Z)(Entry%) / (1132(E,Z)(Entry%)) -

[0037] (1132(Z)(Exit%) / (1132(E,Z)(Exit%)) < |0.01|.

[0038] Item 6. The method for purifying HFO - 1132 according to any one of Items 1 to 5 above, wherein Step 1 is carried out in a temperature range of 0 to 100 °C.

[0039] Item 7. The purification method according to any one of Items 1 to 6 above, wherein the zeolite is molecular sieve 3A and / or molecular sieve 4A.

[0040] Item 8. A method for purifying 1,2 - difluoroethylene (HFO - 1132), characterized by having:

[0041] By bringing a composition containing trans - 1,2 - difluoroethylene (HFO - 1132(E)) and / or cis - 1,2 - difluoroethylene (HFO - 1132(Z)) and containing water into contact with SiO2 / Al 2 O 3 A step of reducing the amount of the water from the above composition by contacting with a zeolite having a ratio of / Al of 5.0 or more.

[0042] Item 9. The method for purifying HFO-1132 according to item 8 above, wherein the isomerization rate of HFO-1132 in the above step is less than 0.1% by volume.

[0043] Item 10. The method for purifying HFO-1132 according to item 8 or 9 above, wherein the above step is carried out in a temperature range of 0 to 100 °C.

[0044] Item 11. The method for purifying HFO-1132 according to any one of items 8 to 10 above, wherein the above zeolite is ZSM-5.

[0045] Item 12. The method for purifying HFO-1132 according to any one of items 1 to 11 above, wherein the above composition further contains at least one selected from vinyl fluoride, difluoroethylene, trifluoroethylene, 1,1,1-trifluoroethane, and propylene.

[0046] Item 13. The method for purifying HFO-1132 according to any one of items 1 to 12 above, wherein the above composition is a product of the dehydrofluorination reaction of 1,1,2-trifluoroethane.

[0047] Item 14. The method for purifying HFO-1132 according to any one of items 1 to 12 above, wherein the above composition is a product of the isomerization reaction of HFO-1132(E) and / or HFO-1132(Z) in the presence of a metal catalyst.

[0048] Item 15. A purified product containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) and containing water, wherein the content of the above water is in the range of 100 ppm (w / w) or less.

[0049] Effects of the Invention

[0050] According to the present invention, it is possible to suppress the isomerization and loss of HFO-1132 and purify HFO-1132 to high purity. Detailed Description

[0051] As a result of in-depth research by the inventors of the present invention, it was found that when purifying HFO-1132 by reducing the above water from a composition containing HFO-1132 and water, by contacting the composition with a specific zeolite, it is possible to suppress the isomerization and loss of HFO-1132 and purify HFO-1132 to high purity.

[0052] The present invention has been completed through further repeated research based on the following insights.

[0053] The present invention includes the following embodiments.

[0054] In the present invention, unless otherwise specified, 1,2-difluoroethylene (HFO-1132) refers to trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)). That is, it refers to HFO-1132(E) alone, HFO-1132(Z) alone, or a mixture of HFO-1132(E) and HFO-1132(Z) (the mixing ratio is arbitrary unless otherwise specified). In addition, the range indicated by "A to B" refers to "A or more and B or less" unless otherwise specified.

[0055] Hereinafter, the present invention will be described in detail by dividing it into Embodiment 1, Embodiment 2, and Embodiment 3.

[0056] Purification method of HFO-1132 in Embodiment 1

[0057] The invention of Embodiment 1 is based on the following insight: when reducing the amount of water in the above composition by bringing a composition containing HFO-1132 and water into contact with zeolite having an average pore diameter of , the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be refined to high purity. In particular, the degree of isomerization (isomerization rate) of HFO-1132 during the refining process is less than 0.1% by volume (including the case where no isomerization occurs). When the invention of Embodiment 1 is divided into the case where the composition before refining is rich in HFO-1132(E) (Embodiment 1-1) and the case where the composition before refining is rich in HFO-1132(Z) (Embodiment 1-2), it can be determined as follows respectively.

[0058] (Embodiment 1-1: Rich in HFO-1132(E))

[0059] A method for refining 1,2-difluoroethylene (HFO-1132), which successively has:

[0060] Step 1 of reducing the amount of water in the above composition by bringing a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and water into contact with zeolite having an average pore diameter of ; and

[0061] Step 2 of recovering the refined product, wherein the refined product contains HFO-1132(E) and the reduced amount of water, and HFO-1132(Z) is less than 0.1% by volume.

[0062] (Embodiment 1-2: Rich in HFO-1132(Z))

[0063] A method for purifying 1,2-difluoroethylene (HFO-1132), which successively has:

[0064] Step 1 of reducing the amount of water in the above composition by contacting a composition containing cis-1,2-difluoroethylene (HFO-1132(Z)) and water with zeolite having an average pore diameter of ; and

[0065] Step 2 of recovering the purified product, wherein the purified product contains HFO-1132(Z) and the reduced amount of water, and HFO-1132(E) is less than 0.1% by volume.

[0066] Examples of the composition containing HFO-1132 and water include a composition containing water mixed in during the production of HFO-1132. Specifically, as the composition, products of dehydrofluorination reaction of 1,1,2-trifluoroethane, products of isomerization reaction of HFO-1132(E) and / or HFO-1132(Z) in the presence of a metal catalyst, etc. can be cited.

[0067] The composition may sometimes contain impurities other than water. As the impurities, for example, intermediates, isomers, by-products, etc. mixed in during the production of HFO-1132 can be cited (for example, at least one of hydrogen fluoride, fluoroethylene, difluoroethylene, trifluoroethylene, 1,1,1-trifluoroethane, propylene, acetylene, difluoromethane, trifluoromethane, fluoromethane, etc.).

[0068] In the case of Embodiment 1-1, particularly with a composition containing HFO-1132(E) and water as the purification target, it is characterized in that by using a specific zeolite, the degree of isomerization (isomerization rate) of HFO-1132(E) during the purification process is less than 0.1% by volume (including the case where no isomerization occurs).

[0069] Therefore, in the recovery step (Step 2) after the purification step (Step 1), a purified product containing HFO-1132(E) and the reduced amount of water and with HFO-1132(Z) less than 0.1% by volume (including the case of 0% by volume, i.e., less than the detection limit by gas chromatography) can be recovered.

[0070] In addition, by using zeolite having an average pore diameter of For zeolites, the adsorption of HFO-1132(E) onto the zeolite is suppressed. Therefore, the isomerization and loss of HFO-1132 can be inhibited, and HFO-1132 can be refined to high purity. Additionally, it is preferred that the composition before refining substantially does not contain HFO-1132(Z), for example, it is preferably at a level where the content cannot be detected by gas chromatography.

[0071] In the case of Embodiment 1-2, particularly when a composition containing HFO-1132(Z) and water is the object of refining, it is characterized in that by using a specific zeolite, the degree of isomerization (isomerization rate) of HFO-1132(Z) during the refining process is less than 0.1% by volume (including the case where no isomerization occurs).

[0072] Therefore, in the recovery step (Step 2) after the refining step (Step 1), a refined product can be recovered that contains HFO-1132(Z) and a reduced amount of water, and the content of HFO-1132(E) is less than 0.1% by volume (including the case of 0% by volume, i.e., less than the detection limit by gas chromatography).

[0073] Additionally, by using a zeolite with an average pore diameter of for the zeolite, the adsorption of HFO-1132(Z) onto the zeolite is suppressed. Therefore, the isomerization and loss of HFO-1132 can be inhibited, and HFO-1132 can be refined to high purity. Additionally, it is preferred that the composition before refining substantially does not contain HFO-1132(E), for example, it is preferably at a level where the content cannot be detected by gas chromatography.

[0074] Next, the zeolite that functions as an adsorbent for adsorbing and removing water in the present invention will be described. In addition, in the present invention, the zeolite can not only adsorb and remove water, but can also adsorb and remove one or more impurities other than water. However, the adsorption and removal of water will be specifically described below.

[0075] Zeolite is a type of clay mineral and is a hydrated aluminosilicate containing an alkali metal or alkaline earth metal, composed of a rigid anionic framework with regular channels (tubular micropores) and cavities.

[0076] Zeolite is generally represented by the following composition, where cations compensate for the negative charge of the aluminosilicate framework.

[0077] (M I ,M II 1 / 2 ) m (Al m Si n O 2(m+n) )· x H2 O, (n≥m)

[0078] (M I :Li + 、Na + , K + etc., M II :Ca 2+ Mg 2+ , Ba 2+ wait)

[0079] The type of cation in the zeolite is not particularly limited, but H + , Li + 、Na + , K + , Ca 2+ Mg 2+ , Ba 2+ wait.

[0080] The basic unit of the structure is SiO 4 or AlO 4 The tetrahedral structure (collectively referred to as TO 4 Tetrahedron), which are infinitely connected in three dimensions to form crystals. Zeolite crystals are porous and the diameter of the pores is usually around 0.2 to 1.0 nm. Zeolite has a molecular sieve effect that prevents molecules larger than its pore diameter from entering the pores. In addition to the molecular sieve effect brought about by the pores of its skeleton structure, zeolite also has properties such as solid acidity, ion exchange capacity, catalytic capacity, and adsorption capacity.

[0081] In Embodiment 1, a composition containing HFO-1132 and water is mixed with an average pore size of When the amount of water is reduced from the composition by contacting with zeolite, the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be purified to a high purity. In particular, the degree of isomerization (isomerization rate) of HFO-1132 during the purification process is suppressed to a low level of less than 0.1 volume % (including the case where isomerization does not occur).

[0082] By making the average pore diameter of zeolite The isomerization rate of HFO-1132 and the possibility of HFO-1132 itself being adsorbed on zeolite can be suppressed to a low level, and the adsorption and removal efficiency of water can be improved. Therefore, the loss caused by isomerization and the like in the refining process can be suppressed to a low level, and HFO-1132 can be purified efficiently.

[0083] The average pore size is Zeolites of this type can be purchased commercially, for example, molecular sieve 3A (average pore size ) Molecular sieve 4A (average pore diameter is )(both are manufactured by UNION SHOWA K.K.). These zeolites only need to meet the condition of the average pore diameter and can be used alone or in combination of two or more.

[0084] In the present invention, the composition to be refined containing HFO-1132 and water is brought into contact with the zeolite having an average pore diameter of , which means that the above composition is passed through a device (such as a column) filled with the above zeolite, or the above composition is filled in a container filled with the above zeolite.

[0085] In the present invention, by using the above zeolite as an adsorbent (material for adsorbing and removing impurities) and bringing the composition to be refined into contact with it (passing through), the water contained in the composition can be adsorbed and removed by the zeolite.

[0086] In the present invention, in order to effectively adsorb and remove water, it is preferred that the composition to be refined is brought into contact with the zeolite at a mass ratio of about 100:1 to 1:10, more preferably at a ratio of about 50:1 to 1:5, and further preferably at a ratio of about 10:1 to 1:3. In the present invention, regarding the usage amount of the zeolite, for example, the composition to be refined can be in the range of about 10 g to 100 g with respect to 10 g of the zeolite filler (such as a stainless steel column).

[0087] In the present invention, the zeolite can be subjected to an activation treatment before its use. The conditions of the activation treatment are not limited. For example, a drying treatment such as heating at a temperature of 200 °C to 350 °C overnight in a vacuum (10 －1 mmHg to 10 －3 mmHg) can be cited. In addition, in the present invention, zeolites without undergoing an activation treatment can also be suitably used.

[0088] In the present invention, the usage method of the zeolite is not particularly limited. The composition to be refined can be passed through a device (such as a column) filled with the zeolite, or the composition to be refined can be filled in a container filled with the zeolite, and the refined product can be recovered after a specified time.

[0089] In the present invention, the temperature at which the composition to be refined is brought into contact with the zeolite is not particularly limited and can be set in consideration of the boiling point of HFO-1132 contained in the composition to be refined, etc. Generally, from the aspect of suppressing side reactions (such as isomerization reactions) during contact, it is preferred to carry out the contact at a low temperature. A range of about 0 to 100 °C is preferred. Among them, for example, a range of 0 to 50 °C, a range of 50 to 100 °C, etc. can be selected.

[0090] In the present invention, the contact time between the composition to be refined and the zeolite is not particularly limited, and can be arbitrarily set as long as the amount of impurities including water contained in the refined recovered product can be reduced to below the target level. Specifically, it can be set according to the flow rate, filling time, the above temperature, etc.

[0091] In the present invention, the zeolite used can be in the form of powder, granules or pellets, or can be in the form of a molded body. Industrially, it is preferably used in the form of a molded body. The shape of the molded body is not particularly limited. For example, it is preferably used in the shape of a cylindrical shape with a diameter of about 0.5 to 5 mm and a length of about 1 to 15 mm, or a spherical shape with a diameter of about 0.5 to 10 mm.

[0092] In the present invention, the method for manufacturing the molded body of zeolite is not particularly limited. For example, an existing well-known method using kaolin-based clay as an adhesive can be adopted.

[0093] In Embodiment 1-1, after the above-mentioned refining step (Step 1), in the recovery step (Step 2), a refined product containing HFO-1132(E) and a reduced amount of water and with HFO-1132(Z) less than 0.1% by volume (including the case of 0% by volume, i.e., less than the detection limit by gas chromatography) can be recovered. In other words, by suppressing the isomerization rate to as low as less than 0.1% by volume (preferably less than 0.01% by volume), the purity of HFO-1132(E) in the refined product can also be suitably increased to more than 99.9% by volume. In addition, by using a specific zeolite, the adsorption of HFO-1132(E) is suppressed, so the loss of HFO-1132(E) can be inhibited.

[0094] In Embodiment 1-2, after the above-mentioned refining step (Step 1), in the recovery step (Step 2), a refined product containing HFO-1132(Z) and a reduced amount of water and with HFO-1132(E) less than 0.1% by volume (including the case of 0% by volume, i.e., less than the detection limit by gas chromatography) can be recovered. In other words, by suppressing the isomerization rate to as low as less than 0.1% by volume (preferably less than 0.01% by volume), the purity of HFO-1132(Z) in the refined product can also be suitably increased to more than 99.9% by volume. In addition, by using a specific zeolite, the adsorption of HFO-1132(Z) is suppressed, so the loss of HFO-1132(Z) can be inhibited.

[0095] Purification method of HFO-1132 in Embodiment 2

[0096] The invention of Embodiment 2 is based on the following insight: by bringing a composition containing HFO-1132 and water into contact with a zeolite having an average pore diameter of When reducing the amount of the above water by contacting with zeolite, isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be refined to high purity. In particular, the degree of isomerization (isomerization rate) of HFO-1132 during the refining process is suppressed to be low (including the case where isomerization does not occur). When the invention of Embodiment 2 is divided into the case where the composition before refining is rich in HFO-1132(E) (Embodiment 2-1), the case where the composition before refining is rich in HFO-1132(Z) (Embodiment 2-2), and the case where the mixing ratio of HFO-1132(E) and HFO-1132(Z) in the composition before refining is arbitrary (Embodiment 2-3), it can be determined as follows respectively.

[0097] (Embodiment 2-1: Rich in HFO-1132(E))

[0098] A method for refining 1,2-difluoroethylene (HFO-1132), comprising: passing a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and water through a column having a zeolite with an average pore diameter of to reduce the amount of the above water from the above composition in Step 1,

[0099] When passing through the above column, the isomerization rates of HFO-1132(E) and HFO-1132(Z) follow the following formula:

[0100] (1132(E)(% at inlet) / (1132(E,Z)(% at inlet)) -

[0101] (1132(E)(% at outlet) / (1132(E,Z)(% at outlet)) < 0.01, and

[0102] (1132(Z)(% at inlet) / (1132(E,Z)(% at inlet)) -

[0103] (1132(Z)(% at outlet) / (1132(E,Z)(% at outlet)) < |0.01|.

[0104] (Embodiment 2-2: Rich in HFO-1132(Z))

[0105] A method for refining 1,2-difluoroethylene (HFO-1132), comprising: passing a composition containing cis-1,2-difluoroethylene (HFO-1132(Z)) and water through a column having a zeolite with an average pore diameter of to reduce the amount of the above water from the above composition in Step 1,

[0106] When passing through the above column, the isomerization rates of the above HFO-1132(E) and HFO-1132(Z) follow the following formula:

[0107] (1132(E)(inlet%) / (1132(E,Z)(inlet%)) -

[0108] (1132(E)(outlet%) / (1132(E,Z)(outlet%)) < |0.01|, and

[0109] (1132(Z)(inlet%) / (1132(E,Z)(inlet%)) -

[0110] (1132(Z)(outlet%) / (1132(E,Z)(outlet%)) < 0.01.

[0111] (Embodiment 2-3: Arbitrary mixing ratio of HFO-1132(E) and HFO-1132(Z))

[0112] A method for purifying 1,2-difluoroethylene (HFO-1132), comprising: passing a composition containing trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)) and water through a column packed with zeolite having an average pore diameter of to reduce the amount of the above water from the above composition.

[0113] When passing through the above column, the isomerization rates of the above HFO-1132(E) and HFO-1132(Z) follow the following formula:

[0114] (1132(E)(inlet%) / (1132(E,Z)(inlet%)) -

[0115] (1132(E)(outlet%) / (1132(E,Z)(outlet%)) < |0.01|, and

[0116] (1132(Z)(inlet%) / (1132(E,Z)(inlet%)) -

[0117] (1132(Z)(outlet%) / (1132(E,Z)(outlet%)) < |0.01|.

[0118] The general description of the above composition to be purified containing HFO-1132 and water is the same as that in Embodiment 1.

[0119] In the case of Embodiment 2-1, particularly, a composition containing HFO-1132(E) and water is used as the object to be purified, and it is characterized in that, by using as an adsorbent an average pore diameter of The zeolite suppresses the degree of isomerization (isomerization rate) of HFO-1132(E) during the purification process (dehydration process) to a low level (including the case where no isomerization occurs).

[0120] Therefore, before the purification step (column inlet) and after (column outlet), the isomerization rates of the above-mentioned HFO-1132(E) and HFO-1132(Z) when passing through the above column follow the following formula;

[0121] (1132(E)(inlet%) / (1132(E,Z)(inlet%)) -

[0122] (1132(E)(outlet%) / (1132(E,Z)(outlet%)) < 0.01, and

[0123] (1132(Z)(inlet%) / (1132(E,Z)(inlet%)) -

[0124] (1132(Z)(outlet%) / (1132(E,Z)(outlet%)) < |0.01|.

[0125] In addition, by using zeolite with an average pore diameter of during the purification step, the adsorption of HFO-1132(E) onto the zeolite is suppressed. Therefore, the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be purified to high purity. Additionally, it is preferable that the composition before purification substantially does not contain HFO-1132(Z), for example, preferably to the extent that the content cannot be detected by gas chromatography.

[0126] In the case of Embodiment 2-2, particularly when a composition containing HFO-1132(Z) and water is the purification target, it is characterized in that by using zeolite with an average pore diameter of the degree of isomerization (isomerization rate) of HFO-1132(Z) during the purification process (dehydration process) is suppressed to a low level (including the case where no isomerization occurs).

[0127] Therefore, before the purification step (column inlet) and after (column outlet), the isomerization rates of the above-mentioned HFO-1132(E) and HFO-1132(Z) when passing through the above column follow the following formula;

[0128] (1132(E)(inlet%) / (1132(E,Z)(inlet%)) -

[0129] (1132(E)(outlet%) / (1132(E,Z)(outlet%)) < |0.01|, and

[0130] ((1132(Z)(Inlet %) / (1132(E,Z)(Inlet %)) -

[0131] (1132(Z)(Outlet %) / (1132(E,Z)(Outlet %)) < 0.01.

[0132] In addition, by using zeolite with an average pore diameter of in the purification process, the adsorption of HFO-1132(Z) to the zeolite is suppressed. Therefore, the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be purified to high purity. In addition, it is preferable that the composition before purification is substantially free of HFO-1132(E), for example, preferably to the extent that the content cannot be detected by gas chromatography.

[0133] In the case of Embodiment 2-3, particularly, a composition containing HFO-1132(E), HFO-1132(Z), and water is the object of purification. It is characterized in that by using zeolite with an average pore diameter of as an adsorbent, the degree of isomerization (isomerization rate) of HFO-1132 during the purification process is suppressed to a low level (including the case where no isomerization occurs).

[0134] Therefore, before (column inlet) and after (column outlet) the purification process, the isomerization rates of the above-mentioned HFO-1132(E) and HFO-1132(Z) when passing through the above column follow the following formula;

[0135] (1132(E)(Inlet %) / (1132(E,Z)(Inlet %)) -

[0136] (1132(E)(Outlet %) / (1132(E,Z)(Outlet %)) < |0.01|, and

[0137] (1132(Z)(Inlet %) / (1132(E,Z)(Inlet %)) -

[0138] (1132(Z)(Outlet %) / (1132(E,Z)(Outlet %)) < |0.01|.

[0139] In addition, by using zeolite with an average pore diameter of in the purification process, the adsorption of HFO-1132 to the zeolite is suppressed. Therefore, the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be purified to high purity.

[0140] The description of the zeolite in the present invention is the same as that in Embodiment 1.

[0141] In the present invention, a column having the above zeolite as an adsorbent (impurity adsorption and removal material) is used, and the composition to be refined is passed through (contacted with) the column, whereby water contained in the composition is adsorbed and removed by the zeolite.

[0142] In the present invention, in order to effectively adsorb and remove water, it is preferable that the composition to be refined and the zeolite are contacted in a ratio of about 100:1 to 1:10 by mass, more preferably in a ratio of about 50:1 to 1:5, and still more preferably in a ratio of about 10:1 to 1:3. In the present invention, regarding the amount of zeolite used, for example, the composition to be refined can be in the range of about 10 g to 100 g relative to 10 g of the zeolite filler (such as a stainless steel column).

[0143] In addition, in order to effectively adsorb and remove water, it is preferable that the composition to be refined and the zeolite flow through for a contact time of about 0.01 to 60 minutes, more preferably about 0.1 to 30 minutes, and still more preferably about 0.3 to 10 minutes.

[0144] In the present invention, the temperature at which the composition to be refined is contacted with the zeolite is not particularly limited and is set in consideration of the boiling point of HFO-1132 contained in the composition to be refined, etc. Generally, from the aspect of suppressing side reactions (such as isomerization reactions) during contact, it is preferable to contact at a low temperature. A range of about 0 to 100 °C is preferred. Among them, for example, a range of 0 to 50 °C, a range of 50 to 100 °C, etc. can be selected.

[0145] In the present invention, the time for contacting the composition to be refined with the zeolite is not particularly limited, as long as the amount of water contained in the refined recovered product can be reduced to below the target level, and it can be arbitrarily set. Specifically, it can be set according to the amount of zeolite used, the contact time, the temperature, etc. In Embodiments 2-1 to 2-3, the isomerization rate can be less than 0.01 in absolute value, preferably less than 0.001.

[0146] In the present invention, the zeolite used can be used in the form of powder, granules or pellets, or can also be used in the form of a molded body. Industrially, it is preferably used in the form of a molded body. The shape of the molded body is not particularly limited. For example, it is preferably used in a cylindrical shape with a diameter of about 0.5 to 5 mm and a length of about 1 to 15 mm, or a spherical shape with a diameter of about 0.5 to 10 mm.

[0147] In the present invention, the method for manufacturing the molded body of the zeolite is not particularly limited. For example, an existing well-known method using kaolin-based clay as a binder can be adopted.

[0148] Purification method of HFO-1132 in Embodiment 3

[0149] The invention of Embodiment 3 is based on the following insight: when reducing the amount of water from the composition containing HFO-1132 and water by contacting with a zeolite having an SiO 2 / Al 2 O 3 ratio of 5.0 or more, isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be refined to high purity. In particular, the degree of isomerization (isomerization rate) of HFO-1132 during the refining process is suppressed to a low level (including the case where no isomerization occurs), and preferably the isomerization rate is less than 0.1% by volume.

[0150] The method for refining HFO-1132 of Embodiment 3 can be determined as follows.

[0151] A method for refining 1,2-difluoroethylene (HFO-1132), characterized by comprising: a step of reducing the amount of water from the composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) and containing water by contacting with a zeolite having an SiO 2 / Al 2 O 3 ratio of 5.0 or more.

[0152] The general description of the composition to be refined containing HFO-1132 and water is the same as that in Embodiment 1. In addition, regarding the contents of HFO-1132(E) and HFO-1132(Z) in the composition, for example, they can be set within a wide range of 10 to 99.99% by volume in total.

[0153] In Embodiment 3, in particular, a composition containing HFO-1132(E) and / or HFO-1132(Z) and containing water is used as the object to be refined, and is characterized in that the degree of isomerization (isomerization rate) of HFO-1132 during the refining process is appropriately suppressed to a low level of less than 0.1% by volume (including the case where no isomerization occurs).

[0154] Therefore, after the refining step, in the recovery step, a refined product can be recovered in which the isomerization of HFO-1132 is suppressed (the change in the E / Z volume% ratio is suppressed) and the amount of water contained is reduced. In addition, by using a zeolite having an SiO 2 / Al 2 O 3 ratio of 5.0 or more in the refining step, the adsorption of HFO-1132 to the zeolite is suppressed, so that the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be refined to high purity.

[0155] Regarding the description of the zeolite in Embodiment 3, except for using a zeolite with an SiO 2 / Al 2 O 3 ratio of 5.0 or more, it is the same as in Embodiment 1. Additionally, in Embodiment 3, there is no upper limit specified for the SiO 2 / Al 2 O 3 ratio of the zeolite, and it is about 2000. That is, the SiO 2 / Al 2 O 3 ratio is preferably 5.0 or more and 2000 or less, more preferably 5 or more and 100 or less.

[0156] In Embodiment 3, when reducing the amount of the above-mentioned water from the composition containing HFO-1132 and water by bringing it into contact with a zeolite having an SiO 2 / Al 2 O 3 ratio of 5.0 or more, the isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be refined to high purity. In particular, the degree of isomerization (isomerization rate) of HFO-1132 during the refining process is preferably suppressed to be lower than 0.1% by volume (more preferably lower than 0.01% by volume) (wherein, including the case of 0% by volume, that is, lower than the detection limit by gas chromatography).

[0157] By making the SiO 2 / Al 2 O 3 ratio 5.0 or more, the isomerization rate of HFO-1132 and the possibility of HFO-1132 itself being adsorbed onto the zeolite can be suppressed to be lower, and the adsorption and removal efficiency of water can be improved. Therefore, the loss caused by isomerization and the like during the refining process can be suppressed to be lower, and HFO-1132 can be refined with high efficiency.

[0158] Zeolites with an SiO 2 / Al 2 O 3 ratio of 5.0 or more can be purchased commercially. For example, ZSM-5 (manufactured by Tosoh Corporation) and Ferrierite (manufactured by Tosoh Corporation) can be cited. These zeolites only need to meet the condition of the SiO 2 / Al 2 O 3 ratio and can be used alone or in combination of two or more.

[0159] In Embodiment 3, regarding bringing the composition to be refined containing HFO-1132 and water into contact with an SiO 2 / Al 2 O 3The method, conditions, etc. for contacting with zeolite having a ratio of 5.0 or more are the same as those in Embodiment 1.

[0160] Purified product with reduced water content

[0161] As described above, in the purification method of HFO-1132 of the present invention, when reducing the amount of water in the above composition by contacting the composition containing HFO-1132 and water with a specific zeolite, isomerization and loss of HFO-1132 can be suppressed, and HFO-1132 can be purified to high purity. The purified product with the reduced amount of water obtained through such a purification method can be determined as follows.

[0162] A purified product containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) and containing water, wherein the content of the above water is in the range of 100 ppm (w / w) or less.

[0163] The embodiments of the present invention have been described above. However, various changes can be made to the embodiments and details as long as they do not exceed the gist and scope of the claimed scope.

[0164] Examples

[0165] Hereinafter, examples and comparative examples will be described to specifically illustrate the present invention. However, the present invention is not limited by these examples.

[0166] In the examples and comparative examples, the purity and impurity concentration of HFO-1132 were measured by the following measuring devices and measuring conditions. And the water content was measured by the following moisture meter.

[0167] Measuring device: Gas chromatography (using FID detector)

[0168] Measuring conditions: Column / GS-GasPro

[0169] Calculation of purity: Calculated based on the GC peak area ratio

[0170] Measurement of water content: Measured by a Karl Fischer moisture meter.

[0171] Example 1

[0172] Weigh 5 g of molecular sieve 3A (average pore diameter SiO 2 / Al 2 O 3 ratio = 2.0), add it to the cartridge, and perform vacuum drying at 250 °C for 2 hours.

[0173] After drying, it is allowed to cool. After returning to room temperature, 10 g of a gas containing trans-1,2-difluoroethylene (HFO-1132(E)) (water content 200 ppm) is added to the cartridge and heated at 50 °C for 3 hours.

[0174] After heating, it is allowed to cool. Then, the gas in the cartridge is recovered by vacuum degassing and its composition is analyzed by gas chromatography.

[0175] Example 2

[0176] The heating temperature (50 °C) is changed to 100 °C, and otherwise, the same operations as in Example 1 are carried out.

[0177] Example 3

[0178] Using molecular sieve 4A (average pore diameter SiO 2 / Al 2 O 3 ratio = 2.0), otherwise, the same operations as in Example 1 are carried out.

[0179] Example 4

[0180] Using molecular sieve 4A, the heating temperature (50 °C) is changed to 100 °C, and otherwise, the same operations as in Example 1 are carried out.

[0181] Example 5

[0182] Using ZSM-5 (SiO 2 / Al 2 O 3 ratio = 40.0), otherwise, the same operations as in Example 1 are carried out.

[0183] Example 6

[0184] Using ZSM-5, the heating temperature (50 °C) is changed to 100 °C, and otherwise, the same operations as in Example 1 are carried out.

[0185] Comparative Example 1

[0186] Using molecular sieve 5A (average pore diameter exceeding SiO 2 / Al 2 O 3 ratio = 2.0), otherwise, the same operations as in Example 1 are carried out.

[0187] Comparative Example 2

[0188] Using molecular sieve 5A, the heating temperature (50 °C) was changed to 100 °C, and other than that, the same operations as in Example 1 were carried out.

[0189] [Table 1]

[0190]

[0191] From the results in Table 1, it can be seen that by using zeolites with an average pore diameter of or zeolites with an SiO 2 / Al 2 O 3 ratio of 5.0 or more, the purification methods of HFO-1132 in Examples 1 to 6 can suppress the isomerization and loss of HFO-1132 and purify HFO-1132 to high purity.

Claims

1. A refining method of 1,2-difluoroethylene (HFO-1132), characterized in that, it has: A step of reducing the amount of water from the composition by contacting a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) and containing water with a zeolite having a SiO 2 / Al 2 O 3 ratio of 5.0 or more.

2. The refining method of HFO-1132 according to claim 1, characterized in that: The isomerization rate of the HFO-1132 (E)) and / or the HFO-1132 (Z) in the said process is less than 0.1% by volume.

3. The refining method of HFO-1132 according to claim 1 or 2, characterized in that: The said process is carried out in the temperature range of 0 to 100 °C.

4. The refining method of HFO-1132 according to claim 1 or 2, characterized in that: The zeolite is ZSM-5.

5. The refining method of HFO-1132 according to claim 1 or 2, characterized in that: The said composition further contains at least one selected from vinyl fluoride, difluoroethylene other than HFO-1132, trifluoroethylene, 1,1,1-trifluoroethane and propylene.

6. The refining method of HFO-1132 according to claim 1 or 2, characterized in that: The said composition is the product of the dehydrofluorination reaction of 1,1,2-trifluoroethane.

7. The refining method of HFO-1132 according to claim 1 or 2, characterized in that: The said composition is the product of the isomerization reaction of HFO-1132 (E) and / or HFO-1132 (Z) in the presence of a metal catalyst.

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