阅读说明：本技术 一种反式-1,3-二氯丙烯的制备方法 (Preparation method of trans-1, 3-dichloropropene ) 是由 王怡明 徐林 丁克鸿 刘相李 卞辰超 赵慧 张巍伟 于 2021-03-03 设计创作，主要内容包括：本发明提供一种反式-1,3-二氯丙烯的制备方法,所述制备方法采用特定催化剂将顺式-1,3-二氯丙烯转化为反式-1,3-二氯丙烯,只需催化剂和光照,无需加入其它溶剂和助剂,反应条件温和,工艺简单,易于工业化实施；反应过程中的副产物少,后续分离简单,应用前景广阔。(The invention provides a preparation method of trans-1, 3-dichloropropene, which adopts a specific catalyst to convert cis-1, 3-dichloropropene into trans-1, 3-dichloropropene, only needs the catalyst and illumination, does not need to add other solvents and auxiliaries, has mild reaction conditions, simple process and easy industrial implementation; few byproducts are generated in the reaction process, the subsequent separation is simple, and the application prospect is wide.)

1. A method for preparing trans-1, 3-dichloropropene, which comprises the following steps: mixing reaction raw materials and a catalyst, and reacting under the illumination condition to prepare trans-1, 3-dichloropropene;

the reaction raw material contains cis-1, 3-dichloropropene, and the catalyst comprises any one or the combination of at least two of titanium dioxide, aluminum oxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, cuprous oxide, bromine simple substance or iodine simple substance.

2. The method according to claim 1, wherein the cis-1, 3-dichloropropene in the reaction raw material is 50 to 100 wt%.

3. The production method according to claim 1 or 2, characterized in that the reaction raw material further contains trans-1, 3-dichloropropene;

preferably, the content of trans-1, 3-dichloropropene in the reaction raw materials is 1-50 wt%.

4. The method according to any one of claims 1 to 3, wherein the mass ratio of the reaction raw material to the catalyst is 1 (0.01 to 0.1).

5. The production method according to any one of claims 1 to 4, wherein the titanium dioxide is nano titanium dioxide;

preferably, the alumina is nano alumina.

6. The method according to any one of claims 1 to 5, wherein the light source for illumination comprises any one or a combination of at least two of a visible light source, an ultraviolet light source or a natural light source.

7. The method according to any one of claims 1 to 6, wherein the wavelength range of the light irradiation includes 10 to 780 nm;

preferably, the intensity of the illumination is 5-2000W.

8. The method according to any one of claims 1 to 7, wherein the reaction temperature is 10 to 100 ℃;

preferably, the reaction time is 0.5-8 h.

9. The production method according to any one of claims 1 to 8, characterized by further comprising: and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction to obtain the trans-1, 3-dichloropropene.

10. The method according to any one of claims 1 to 9, characterized by comprising the steps of:

(1) mixing reaction raw materials and a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1 (0.01-0.1), reacting for 0.5-8 h under the illumination condition at 10-100 ℃, the illumination wavelength range comprises 10-780 nm, the intensity is 5-2000W, and the light source comprises any one or the combination of at least two of a visible light source, an ultraviolet light source or a natural light source, so as to prepare trans-1, 3-dichloropropene;

the reaction raw material comprises a byproduct 1, 3-dichloropropene raw material in chloropropene production, and the catalyst comprises any one or the combination of at least two of titanium dioxide, aluminum oxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, cuprous oxide, a bromine simple substance or an iodine simple substance;

(2) and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction to obtain the trans-1, 3-dichloropropene.

Technical Field

The invention relates to the technical field of fine chemical engineering, in particular to a preparation method of trans-1, 3-dichloropropene.

Background

The 1, 3-dichloropropene has two configurations of trans-1, 3-dichloropropene and cis-1, 3-dichloropropene, and the two cis-trans isomers have similar properties, belong to flammable colorless liquids, have strong irritation and chloroform-like odor, are insoluble in water and are soluble in most organic solvents such as ethanol, diethyl ether, benzene and the like. Wherein, the trans-1, 3-dichloropropene is mainly used for synthesizing intermediates of the cyclohexenone herbicides and synthesizing the antifungal medicine terbinafine hydrochloride. The mixed 1, 3-dichloropropene and cis-1, 3-dichloropropene can be directly used as soil fumigants and soil insecticides and can also be used for producing novel insecticide raw materials.

The 1, 3-dichloropropene is a byproduct in the chloropropene production process, and 170kg of mixed-type 1, 3-dichloropropene is produced as a byproduct in the industry every 1t of chloropropene, wherein the cis-form ratio is about 56 percent, and the trans-form ratio is about 42 percent. The byproduct of the device for producing 10 ten thousand tons of chloropropene annually is mixed with 1.7 ten thousand tons of dichloropropene, wherein the cis form is about 9000 tons, and the trans form is about 8000 tons. At present, the market price of cis-1, 3-dichloropropene is 4000-8000 yuan/ton, the price is low, and the market demand is small. The market price of the trans-1, 3-dichloropropene is 2-3 ten thousand yuan/ton, the price is high, and the application is wide. The trans-1, 3-dichloropropene is generated by translocating the cis-1, 3-dichloropropene, so that the way of the cis-1, 3-dichloropropene can be increased, the economy of a chloropropene device is improved, and extremely high economic and social benefits are achieved.

Currently, 1, 3-dichloropropene on the market exists in a form of a mixture of cis-1, 3-dichloropropene and trans-1, 3-dichloropropene isomers, and trans-1, 3-dichloropropene is mainly obtained by separating and mixing 1, 3-dichloropropene through multi-stage rectification, wherein cis-1, 3-dichloropropene and trans-1, 3-dichloropropene are isomers, cis-1, 3-dichloropropene CAS #10061-01-5 has a molecular weight of 110.97, a melting point of-50 ℃, a boiling point of 104.3 ℃ and a density of 1.225 g/ml; trans 1, 3-dichloropropene CAS #10061-02-6, molecular weight 110.97, boiling point 112 ℃, density 1.198 g/ml. The boiling point difference of cis/trans-1, 3-dichloropropene is less than 7 ℃, and the separation is carried out by adopting a multi-stage rectification scheme in industry, so that the separation difficulty and the energy consumption are high.

CN1466559A discloses a low-coloring trans-1, 3-dichloropropene and a preparation method thereof, this patent describes a composition comprising cis-1, 3-dichloropropene, trans-1, 3-dichloropropene and a compound of C6, removing cis-1, 3-dichloropropene with low boiling point through a chlorination step and a rectification step, rectifying to remove C6 chlorinated compounds with high boiling point to obtain trans-1, 3-dichloropropene with the chroma less than or equal to 200, the method only carries out rectification separation on the mixed 1, 3-dichloropropene, does not generate a trans-related process by cis-transposition, and the separated cis-form is still mixed with the mixed 1, 3-dichloropropene to be used as a soil fumigant and an insecticide, so that the economic value is low, and the problem that the cis-1, 3-dichloropropene does not have a proper way is not solved.

In 2005, it was reported that cis-isomer has high internal energy and poor thermal stability, and can be translocated under certain conditions to form trans-isomer having low internal energy and high thermal stability, and the mechanism of cis-isomerization to form trans-isomer includes photoisomerization, thermal isomerization and catalytic isomerization (see "cis-trans isomerization process and mechanism", plum front, etc., cis-trans isomerization process and mechanism, phase 1, pages 21-23).

US3914167 discloses a method for isomerizing trans-1, 3-dichloropropene into cis-1, 3-dichloropropene by adding a certain amount of photocatalyst under the irradiation of ultraviolet light to generate free radicals which can efficiently catalyze the isomerization of trans-1, 3-dichloropropene to cis-structure, wherein the cis-trans isomerization mechanism is that the free radicals generated under the irradiation of ultraviolet light can induce double bonds to generate double radicals, so that the double radicals are twisted to obtain an isomeric structure. The method provides a concept for preparing cis-1, 3-dichloropropene, but does not mention how to prepare trans-1, 3-dichloropropene.

CN109694308A discloses a method for in-situ conversion of trans-1, 3-dichloropropene into cis-1, 3-dichloropropene, which comprises adding trans-1, 3-dichloropropene into an alcohol solvent, adding a light promoter, carrying out ultraviolet irradiation, and reacting to obtain cis-1, 3-dichloropropene. The method also provides a thought for preparing cis-1, 3-dichloropropene, and does not mention how to prepare trans-1, 3-dichloropropene.

Therefore, it is required to develop a method for preparing trans-1, 3-dichloropropene that improves economic efficiency in the chloropropene production process.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method of trans-1, 3-dichloropropene, which adopts cis-1, 3-dichloropropene as a raw material and adopts a technology of converting under the photocatalysis action to generate the trans-1, 3-dichloropropene, does not need solvents, auxiliaries and other substances, and has the advantages of high conversion rate and selectivity, mild reaction conditions, simple process, easy industrial implementation and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of trans-1, 3-dichloropropene, which comprises the following steps: mixing reaction raw materials and a catalyst, and reacting under the illumination condition to prepare trans-1, 3-dichloropropene; the reaction raw material contains cis-1, 3-dichloropropene, and the catalyst comprises any one or the combination of at least two of titanium dioxide, aluminum oxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, cuprous oxide, bromine simple substance or iodine simple substance.

The preparation method provided by the invention can realize the conversion of cis-1, 3-dichloropropene to trans-1, 3-dichloropropene by adopting a specific catalyst matched with illumination without adding solvents such as methanol and other auxiliaries, the trans-selectivity is more than 95%, the conversion rate and the selectivity are high, a solvent is not required to be separated in the subsequent separation process, the catalyst can be directly recycled, the three-waste emission is reduced, and the preparation method is safe and environment-friendly.

Typical but non-limiting combinations among the catalysts described herein are titanium dioxide and aluminum oxide, titanium dioxide and zinc oxide, aluminum oxide and tin oxide, aluminum oxide and cadmium sulfide, zinc oxide and tin oxide, tin oxide and cuprous oxide.

Preferably, the cis-1, 3-dichloropropene content of the reaction feed is 50 to 100 wt%, for example, 50 wt%, 56 wt%, 60 wt%, 67 wt%, 70 wt%, 78 wt%, 80 wt%, 85 wt%, 90 wt%, or 100 wt%, but is not limited to the recited values, and other values not recited in this range are also applicable.

Preferably, the reaction raw material also contains trans-1, 3-dichloropropene.

Preferably, the trans-1, 3-dichloropropene content of the reaction feed is 1 to 50 wt%, and may be, for example, 1 wt%, 7 wt%, 12 wt%, 18 wt%, 23 wt%, 29 wt%, 34 wt%, 40 wt%, 45 wt%, or 50 wt%, but is not limited to the recited values, and other values not recited in this range are also applicable.

The mass ratio of the reaction material to the catalyst is preferably 1 (0.01 to 0.1), and may be, for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1, but not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

Preferably, the titanium dioxide is nano titanium dioxide.

Preferably, the alumina is nano alumina.

Preferably, the light source for illumination includes any one of or a combination of at least two of a visible light source, an ultraviolet light source or a natural light source, wherein typical but non-limiting combinations are a combination of a visible light source and an ultraviolet light source, a combination of an ultraviolet light source and a natural light source, and a combination of a natural light source and a visible light source.

Preferably, the wavelength range of the illumination light includes 10 to 780nm, for example, 10nm, 96nm, 182nm, 267nm, 353nm, 438nm, 524nm, 609nm, 695nm, 780nm, etc., but is not limited to the recited values, and other values not recited in the range are also applicable.

Preferably, the intensity of the light irradiation is 5 to 2000W, and may be, for example, 5W, 60W, 115W, 170W, 225W, 280W, 335W, 390W, 445W, 500W, 800W, 1000W, 1200W, 1500W, 2000W, or the like, but is not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the reaction temperature is 10 to 100 ℃, for example, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, but not limited to the cited values, and other values not listed in the range are also applicable.

Preferably, the reaction time is 0.5-8 h, for example, 0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3h, 3.5h, 4.0h, 4.5h, 5.0h, 5.5h, 6.0h, 6.5h, 7.0h or 8 h.

Preferably, the reaction raw material comprises a 1, 3-dichloropropene raw material by-produced in chloropropene production.

Preferably, the preparation method further comprises: and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction to obtain the trans-1, 3-dichloropropene.

The rectification separation condition of the invention can be the separation condition of the conventional cis-1, 3-dichloropropene and trans-1, 3-dichloropropene, and can also be adjusted according to the actual process.

Preferably, the degree of vacuum of the rectification separation is-0.065 to-0.075 MPa, and may be, for example, -0.065MPa, -0.066MPa, -0.068MPa, -0.069MPa, -0.070MPa, -0.071MPa, -0.072MPa, -0.073MPa or-0.075 MPa, but the degree is not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the temperature of the bottom of the rectification column is 70 to 77 ℃, and may be, for example, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃ or 77 ℃, but is not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the top temperature of the rectification separation is 64 to 68 ℃, and may be, for example, 64 ℃, 64.5 ℃, 64.9 ℃, 65.4 ℃, 65.8 ℃, 66.3 ℃, 66.7 ℃, 67.2 ℃, 67.6 ℃ or 68 ℃, but is not limited to the above-mentioned values, and other values not listed in the range are also applicable.

Preferably, the reflux ratio of the rectification separation is 3 to 5:1, and may be, for example, 3:1, 3.3:1, 3.5:1, 3.7:1, 3.9:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

Preferably, the preparation method comprises the following steps:

(1) mixing reaction raw materials and a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1 (0.01-0.1), reacting for 0.5-8 h under the illumination condition at 10-100 ℃, the illumination wavelength range comprises 10-780 nm, the intensity is 5-2000W, and the light source comprises any one or the combination of at least two of a visible light source, an ultraviolet light source or a natural light source, so as to prepare trans-1, 3-dichloropropene;

the reaction raw material comprises a byproduct 1, 3-dichloropropene raw material in chloropropene production, and the catalyst comprises any one or the combination of at least two of titanium dioxide, aluminum oxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, cuprous oxide, a bromine simple substance or an iodine simple substance;

(2) and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction to obtain the trans-1, 3-dichloropropene.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) mixing reaction raw materials and a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1 (0.01-0.1), reacting for 0.5-8 h under the illumination condition at 10-100 ℃, the illumination wavelength range comprises 10-780 nm, the intensity is 5-2000W, and the light source comprises any one or the combination of at least two of a visible light source, an ultraviolet light source or a natural light source, so as to prepare trans-1, 3-dichloropropene;

the reaction raw material comprises a byproduct 1, 3-dichloropropene raw material in chloropropene production, and the catalyst comprises any one or the combination of at least two of titanium dioxide, aluminum oxide, zinc oxide, tin oxide, zirconium dioxide, cadmium sulfide, cuprous oxide, a bromine simple substance or an iodine simple substance;

(2) and (3) rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction, wherein the vacuum degree of the rectification and separation is-0.065 to-0.075 MPa, the temperature of the top of the tower is 64 to 68 ℃, the temperature of the bottom of the tower is 70 to 77 ℃, the reflux ratio is 3 to 5:1, and the trans-1, 3-dichloropropene is extracted.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) the preparation method of trans-1, 3-dichloropropene provided by the invention only needs catalyst and illumination, does not need to add other solvents and auxiliaries, and has the advantages of mild reaction conditions, simple process, simple subsequent separation and easy industrial implementation;

(2) the preparation method of trans-1, 3-dichloropropene provided by the invention expands the source of trans-1, 3-dichloropropene, utilizes free radicals generated under the illumination condition to generate transposition reaction, efficiently translocates cis-1, 3-dichloropropene to generate trans-1, 3-dichloropropene, under the better condition, the conversion rate is more than or equal to 60 wt%, the selectivity of trans-1, 3-dichloropropene is more than or equal to 95%, and the conversion rate and the selectivity are high;

(3) the unreacted cis-1, 3-dichloropropene and the catalyst in the preparation method of the trans-1, 3-dichloropropene provided by the invention can be recycled, the discharge amount of three wastes is small, the preparation method is safe and environment-friendly, and the comprehensive resource utilization of the C3 raw material with low added value is realized.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

First, an embodiment

Example 1

This example provides a process for the preparation of trans-1, 3-dichloropropene comprising the steps of:

(1) mixing reaction raw materials (80.1 wt% of cis-1, 3-dichloropropene and 17.8 wt% of trans-1, 3-dichloropropene) and nano titanium dioxide serving as a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1:0.03, heating to 30 ℃, and reacting for 3 hours under the illumination condition of a 20W 310nm LED ultraviolet lamp to prepare the trans-1, 3-dichloropropene;

(2) and (3) rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction, wherein the vacuum degree of the rectification and separation is-0.070-0.072 MPa, the temperature of the top of the tower is 64-65 ℃, the temperature of the bottom of the tower is 72-75 ℃, the reflux ratio is 3.2-3.5: 1, and the cis-1, 3-dichloropropene and the trans-1, 3-dichloropropene are sequentially extracted from the top of the tower.

Example 2

This example provides a process for the preparation of trans-1, 3-dichloropropene comprising the steps of:

(1) mixing reaction raw materials (55.6 wt% of cis-1, 3-dichloropropene and 43.4 wt% of trans-1, 3-dichloropropene) and nano-alumina serving as a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1:0.05, heating to 50 ℃, and reacting for 2 hours under the conditions of 50W and 310nm LED lamp illumination to prepare the trans-1, 3-dichloropropene;

(2) and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction, wherein the vacuum degree of the rectification and separation is-0.065 to-0.070 MPa, the temperature of the top of the tower is 65 to 67 ℃, the temperature of the bottom of the tower is 75 to 77 ℃, the reflux ratio is 3 to 3.3:1, and the cis-1, 3-dichloropropene and the trans-1, 3-dichloropropene are sequentially collected from the top of the tower.

Example 3

This example provides a process for the preparation of trans-1, 3-dichloropropene comprising the steps of:

(1) mixing reaction raw materials (95.6 wt% of cis-1, 3-dichloropropene and 2.7 wt% of trans-1, 3-dichloropropene) and cadmium sulfide serving as a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1:0.1, heating to 75 ℃, and reacting for 1h under the condition of natural illumination to prepare the trans-1, 3-dichloropropene;

(2) and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction, wherein the vacuum degree of the rectification and separation is-0.070 to-0.075 MPa, the temperature of the top of the tower is 66 to 68 ℃, the temperature of the bottom of the tower is 70 to 73 ℃, the reflux ratio is 4.3 to 5:1, and the cis-1, 3-dichloropropene and the trans-1, 3-dichloropropene are sequentially collected from the top of the tower.

Example 4

This example provides a process for the preparation of trans-1, 3-dichloropropene comprising the steps of:

(1) mixing reaction raw materials (71.8 wt% of cis-1, 3-dichloropropene and 27.3 wt% of trans-1, 3-dichloropropene) and zirconium dioxide serving as a catalyst, wherein the mass ratio of the reaction raw materials to the catalyst is 1:0.02, heating to 80 ℃, and reacting for 4 hours under the illumination condition of a 200W and 200nm high-pressure mercury lamp to prepare the trans-1, 3-dichloropropene;

(2) and rectifying and separating the product containing the trans-1, 3-dichloropropene obtained after the reaction, wherein the vacuum degree of the rectification and separation is-0.066 to-0.070 MPa, the temperature of the top of the tower is 65 to 67 ℃, the temperature of the bottom of the tower is 70 to 75 ℃, the reflux ratio is 4.5 to 4.6:1, and the cis-1, 3-dichloropropene and the trans-1, 3-dichloropropene are sequentially extracted from the top of the tower.

Examples 5 to 8

The recovered catalyst nano titanium dioxide of example 1 was reused in the same process as in example 1, and the reuse results are shown in table 1.

TABLE 1

Examples	Example 1	Example 5	Example 6	Example 7	Example 8
						Application batch	0	1	2	3	4

Example 9

This example provides a process for producing trans-1, 3-dichloropropene similar to example 1, except that the mass ratio of the starting materials to the catalyst in step (1) is 1: 0.005.

Example 10

This example provides a process for producing trans-1, 3-dichloropropene similar to example 1, except that the mass ratio of the starting materials to the catalyst in step (1) is 1: 0.2.

Example 11

This example provides a process for producing trans-1, 3-dichloropropene similar to that of example 1, except that the catalyst used in step (1) is tin oxide.

Example 12

This example provides a process for the preparation of trans-1, 3-dichloropropene as in example 1, except that in step (1) the catalyst is cuprous oxide.

Example 13

This example provides a process for producing trans-1, 3-dichloropropene similar to that of example 1, except that the catalyst used in step (1) is zinc oxide.

Example 14

This example provides a process for producing trans-1, 3-dichloropropene similar to that of example 1, except that the catalyst used in step (1) is elemental iodine.

Second, comparative example

Comparative example 1

This comparative example provides a process for the preparation of trans-1, 3-dichloropropene as in example 1, except that in step (1) the methanol solvent is added, the ratio of methanol solvent to starting materials for the reaction is 1: 1.

Third, test and results

The test method comprises the following steps: the purity of trans-1, 3-dichloropropene prepared in the above examples and comparative examples was determined by a quantitative gas chromatography test.

The test results of the above examples and comparative examples are shown in table 2.

TABLE 2

From table 2, the following points can be seen:

(1) it can be seen from the comprehensive examples 1 to 14 that the trans-1, 3-dichloropropene generated by transposition of cis-1, 3-dichloropropene by the solvent-free method has high conversion rate and selectivity, the conversion rate is more than or equal to 60 wt% and the selectivity is more than or equal to 95 wt% under the better condition, and the solvent-free method has the advantages of easy product separation, high product quality and the like, is advanced in process and is easy for industrial implementation;

(2) it can be seen from the combination of example 1 and comparative example 1 that, in example 1, the conversion of cis-1, 3-dichloropropene is 75.6 wt%, the selectivity of trans-1, 3-dichloropropene is 96.2 wt%, and the purity of final trans-1, 3-dichloropropene is as high as 99.35 wt% in comparison with the addition of methanol solvent in comparative example 1, whereas in comparative example 1, not only methanol solvent generates waste liquid, but also the conversion of cis-1, 3-dichloropropene is only 36.5 wt%, the selectivity of trans-1, 3-dichloropropene is only 92.1 wt%, and the purity of final trans-1, 3-dichloropropene is only 95.1 wt%, thus showing that the present invention significantly improves the selectivity of reaction, conversion and final trans-1 by not adding methanol or other solvent, the purity of the 3-dichloropropene product;

(3) it can be seen from the comprehensive examples 1 and 5-8 that the catalyst provided by the invention still has high selectivity and catalytic performance after being reused for many times, and the product purity is high;

(4) it can be seen from the combination of example 1 and examples 9 to 10 that the mass ratio of the reaction raw material to the catalyst in example 1 is 1:0.03, and the conversion rate, the selectivity and the product purity are higher in example 1 than in examples 9 to 10, which are 1:0.005 and 1:0.2 respectively, while the conversion rate of cis-1, 3-dichloropropene is only 42.1 wt% in example 9, and the selectivity of trans-1, 3-dichloropropene is only 80.5 wt% in example 10, and the final product purity is relatively lower, which indicates that the conversion rate and the selectivity can be improved by controlling the ratio of the reaction raw material to the catalyst in a specific range.

In conclusion, the preparation method of trans-1, 3-dichloropropene provided by the invention uses a specific catalyst to convert cis-1, 3-dichloropropene into trans-1, 3-dichloropropene, only needs the catalyst and illumination, does not need to add other solvents and auxiliaries, and has the advantages of conversion rate of more than or equal to 60 wt%, selectivity of more than or equal to 95 wt%, easy separation and recovery of trans-1, 3-dichloropropene and wide application prospect under better conditions.

The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.