Compound polymerization inhibitor for improving selectivity of 1, 2, 2, 3-trichloropropene prepared from 1, 2, 2, 3-tetrachloropropane and preparation method and application of compound polymerization inhibitor

Abstract

The invention discloses a compound polymerization inhibitor for improving the selectivity of 1, 2, 3-trichloropropene prepared from 1, 2, 2, 3-tetrachloropropane as well as a preparation method and application of the compound polymerization inhibitor. The compound polymerization inhibitor consists of the following components: a phenol polymerization inhibitor, an inorganic compound polymerization inhibitor, a regulator and a solvent. The compound polymerization inhibitor can efficiently inhibit further polymerization of 1, 2, 3-trichloropropene to generate by-products, so that the reaction selectivity is improved, and the separation difficulty of subsequent products is reduced. The compound polymerization inhibitor provided by the invention can effectively reduce excessive polymerization of 1, 2, 3-trichloropropene in the reaction process without influencing the reaction conversion rate, is not easy to block a pipeline, has high product selectivity, is easy for subsequent product separation and purification, and is suitable for industrial scale use. The compound polymerization inhibitor can be dissolved in a water phase, is simple to separate and has no influence on subsequent rectification. Meanwhile, a method for dehydrochlorination by using alkali liquor is adopted, so that the reaction conditions are mild, and the safety performance is high.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis, and in particular relates to a composite polymerization inhibitor for improving the selectivity of preparing 1,2,3-trichloropropene from 1,2,2,3-tetrachloropropane, and a preparation method and application thereof. Background Art

[0002] 1,2,3-Trichloropropene is an important intermediate for the synthesis of 1,1,2,3-tetrachloropropene, the raw material of the new refrigerant HFO-1,2,3,4yf, and is also an important intermediate for the herbicide avenant. In the existing technology, the method of alkaline dehydrochlorination is usually used to prepare trichloropropene. Specifically, tetrachloropropane is mixed with an alkaline catalyst and dehydrochlorination reaction is carried out at a certain temperature and pressure. This method can effectively prepare trichloropropene, but due to the high chemical activity of trichloropropene, it is easy to undergo polymerization to produce solid polymers, resulting in pipeline blockage, low selectivity and yield.

[0003] The invention patent with publication number GB1381619A discloses a method for preparing 1,2,3-trichloropropene from 1,2,2,3-tetrachloropropane, wherein gaseous 1,2,2,3-tetrachloropropane is passed into a fixed bed or fluidized bed containing a catalyst (preferably Al2O3 or silicon / aluminum / magnesium oxide) at a temperature of 325°C-330°C for a residence time of 1-20 seconds to obtain 1,2,3-trichloropropene. However, the gaseous catalytic dehydrochlorination reaction temperature used in this method is high, the risk in terms of safe production is high, the energy consumption is high, and the requirements for catalyst performance and reaction equipment are relatively stringent.

[0004] The invention patent with publication number CN101955414A discloses a process for producing 1,1,2,3-tetrachloropropene, which involves the step of preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane. The reaction is carried out at a temperature of 75-80°C by dropping an alkaline solution to remove hydrogen chloride. However, the 1,2,3-trichloropropene produced by this method is prone to further polymerization, resulting in a reduced product yield and a large number of impurities, which is not conducive to subsequent separation.

[0005] The journal "Study on the Mixed Herbicide of Avena Methacrylate and Avena Methacrylate - II. A New Synthesis Method for the Mixture of 1,2,3-Trichloropropene and 1,1,2,3-Tetrachloropropene" (Wang Jinxian, Journal of Chemistry in Higher Education, Vol. 1, No. 002, 1981) proposed using 1,2,2,3-tetrachloropropane and 1,1,2,2,3-pentachloropropane as raw materials to undergo liquid alkali dehydrochlorination reaction to obtain 1,2,3-trichloropropene and 1,1,2,3-tetrachloropropene, with a total product yield of 90-94%. However, this method uses mixed polychlorinated alkanes as raw materials, and the yield decreases as the content of 1,2,2,3-tetrachloropropane increases.

[0006] Therefore, it is urgent to develop a production method for 1,2,3-trichloropropene that can reduce production energy consumption, reduce polymerization, and improve yield and purity. Summary of the invention

[0007] In view of the above problems, the present invention adds a composite polymerization inhibitor on the basis of alkali solution dehydrochlorination, which can effectively inhibit the polymerization of trichloropropylene, improve the selectivity, and facilitate subsequent separation and purification. The composite polymerization inhibitor can increase the selectivity of the target product from 80-85% to 94-99%, and the polymerization inhibitor can be dissolved in alkali solution and is easy to separate.

[0008] According to one aspect of the present invention, an object of the present invention is to provide a composite polymerization inhibitor for improving the high selectivity of preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane, wherein the composite polymerization inhibitor is composed of the following components: a phenolic polymerization inhibitor, an inorganic compound polymerization inhibitor, a regulator and a solvent;

[0009] Wherein, the phenolic polymerization inhibitor is one or more of hydroquinone, phenol, and p-tert-butylcatechol.

[0010] Preferably, the inorganic compound inhibitor is one or more of ferric chloride, potassium chloride, cesium chloride, sodium sulfate, and sodium thiocyanate.

[0011] Preferably, the solvent is one or more of formamide, acetonitrile, chloroform, water, ethyl acetate, toluene and xylene.

[0012] Preferably, the regulator is one or more of sodium bicarbonate, sodium carbonate and potassium hydroxide.

[0013] Preferably, the mass ratio of the phenolic polymerization inhibitor, the inorganic compound polymerization inhibitor, and the solvent is 1:5-20:10-100, more preferably 1:5-20:10-30.

[0014] Preferably, the amount of the regulator is such that the pH of the final compound inhibitor can be adjusted to between 6 and 8.

[0015] According to another aspect of the present invention, an object of the present invention is to provide a method for preparing the composite polymerization inhibitor, the method comprising the following steps:

[0016] A. Mix a phenolic polymerization inhibitor and an inorganic compound polymerization inhibitor, and stir to form a mixture.

[0017] B. Add the mixture prepared in step A into a solvent and stir to form an inhibitory main body slurry or solution.

[0018] C. At a temperature of 20-40°C, add the regulator to the inhibitor main slurry or solution to adjust the pH value to between 6 and 8 to form a composite inhibitor.

[0019] According to another aspect of the present invention, an object of the present invention is to provide a method for improving the high selectivity of preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane, comprising the following steps:

[0020] 1) First, add 1,2,2,3-tetrachloropropane, phase transfer catalyst and polymerization inhibitor into a reactor and stir evenly to form a reaction system;

[0021] 2) Prepare a sodium hydroxide solution of a certain concentration;

[0022] 3) Under heating, stirring and certain pressure conditions, the sodium hydroxide solution of step 2) is added dropwise to the reaction system of step 1) and reacted for a period of time until the reaction is completed;

[0023] 4) There is no solid polymer in the system after the reaction. The oil and water are separated by liquid separation operation, and then the organic phase is further distilled and purified through a distillation tower. The phase transfer catalyst and inhibitor are present in the water phase, and they can be separated and treated by subsequent wastewater treatment.

[0024] The reaction formula of this method is:

[0025]

[0026] Preferably, the molar ratio of 1,2,2,3-tetrachloropropane to sodium hydroxide is 1:0.8-3;

[0027] Preferably, the phase transfer catalyst is a phase transfer catalyst conventionally used in the art, for example, it can be a quaternary ammonium salt phase transfer catalyst, such as benzyltriethylammonium chloride, tetrabutylammonium bromide;

[0028] Preferably, the mass concentration of the sodium hydroxide solution is 5-30%;

[0029] Preferably, the phase transfer catalyst accounts for 0.01% to 5% of the mass of 1,2,2,3-tetrachloropropane;

[0030] Preferably, the compound polymerization inhibitor accounts for 1%-5% of the mass of 1,2,2,3-tetrachloropropane;

[0031] Preferably, the reaction pressure in step 3) is 1-2 atmospheres;

[0032] Preferably, the reaction temperature in step 3) is 40-100°C;

[0033] Preferably, the reaction time in step 3) is 1-14 hours.

[0034] The present invention provides a method for preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane with high selectivity. The method uses a compound polymerization inhibitor to effectively inhibit the further polymerization of 1,2,3-trichloropropene to produce by-products, thereby improving the selectivity of the reaction and reducing the difficulty of subsequent product separation. In the process of producing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane in a sodium hydroxide solution system without the addition of a compound polymerization inhibitor, excessive polymerization is very likely to occur, generating a solid polymer suspended in a liquid, and generating 1,2,3-trichloropropene dimers and polymers of various structures.

[0035] Beneficial Effects

[0036] The composite polymerization inhibitor of the present invention can effectively reduce the excessive polymerization of 1,2,3-trichloropropene in the reaction process without affecting the reaction conversion rate, is not easy to block the pipeline, has high product selectivity, is easy to separate and purify the subsequent products, and is suitable for industrial-scale use. The composite polymerization inhibitor is soluble in water phase, is easy to separate, and has no effect on subsequent distillation. At the same time, the present invention adopts the method of dehydrochlorination of alkali solution, has mild reaction conditions, and has high safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 The figure is a schematic flow diagram of a method for preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane with high selectivity according to one embodiment of the present invention. DETAILED DESCRIPTION

[0039] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the principle of allowing the inventor to appropriately define the terms for the best interpretation, based on the meaning and concept corresponding to the technical level of the present invention. Therefore, the description herein is only a preferred example for illustrative purposes, and is not intended to limit the scope of the present invention, so it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the present invention.

[0040] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0041] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0042] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0043] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0044] According to the method of the present invention, the reactor is not particularly limited in the present invention and can be any one selected from known batch reactors, semi-batch reactors, continuous stirred tank reactors, plug flow reactors, stationary phase reactors and fluidized bed reactors, or can be a mixed reactor in which two or more of these reactors are connected.

[0045] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0046] Example 1

[0047] Add 1g of hydroquinone, 5g of ferric chloride and 10g of formamide into a beaker and stir evenly at 30°C. Use sodium bicarbonate solution as a regulator to adjust the pH of the solution to 8.0 to obtain a composite inhibitor.

[0048] In a 150mL three-necked flask, 18.1g of 1,2,2,3-tetrachloropropane, 0.1g of a composite inhibitor, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. The oil phase was separated by a separating funnel and rectified by a distillation tower to obtain the final product 1,2,3-trichloropropene. The yield of 1,2,3-trichloropropene was 71%, the conversion rate of 1,2,2,3-tetrachloropropane was 72%, and the selectivity of 1,2,3-trichloropropene was 98.6%.

[0049] Example 2

[0050] 0.5 g of hydroquinone, 1 g of phenol, 5 g of sodium sulfate and 12 g of formamide were added into a beaker and stirred evenly at 30° C. Sodium bicarbonate solution was used as a regulator to adjust the pH of the solution to 8.0 to obtain a composite inhibitor.

[0051] In a 150mL three-necked flask, 20g of 1,2,2,3-tetrachloropropane, 0.15g of a composite inhibitor, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 60°C, and a reflux reaction was carried out under stirring for 14 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. The oil phase was separated by a separating funnel and rectified by a distillation tower to obtain the final product 1,2,3-trichloropropene. The yield of 1,2,3-trichloropropene was 66.7%, the conversion rate of 1,2,2,3-tetrachloropropane was 70%, and the selectivity of 1,2,3-trichloropropene was 95.3%.

[0052] Example 3

[0053] Add 1 g of hydroquinone, 8 g of sodium thiocyanate and 20 g of acetonitrile into a beaker and stir evenly at 35° C. Use sodium carbonate solution as a regulator to adjust the pH of the solution to 8.0 to obtain a composite inhibitor.

[0054] In a 150mL three-necked flask, 30g of 1,2,2,3-tetrachloropropane, 0.8g of a composite inhibitor, 0.1g of benzyltriethylammonium chloride, and 60g of a 20% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 80°C, and a reflux reaction was carried out under stirring for 10 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. The oil phase was separated by a separating funnel and rectified by a distillation tower to obtain the final product 1,2,3-trichloropropene. The yield of 1,2,3-trichloropropene was 63%, the conversion rate of 1,2,2,3-tetrachloropropane was 65%, and the selectivity of 1,2,3-trichloropropene was 96.4%.

[0055] Example 4

[0056] Add 1g phenol, 5g sodium sulfate, 6g potassium chloride and 12g formamide into a beaker and stir evenly at 25° C. Use sodium bicarbonate solution as a regulator to adjust the solution pH to 8.0 to obtain a composite inhibitor.

[0057] In a 150mL three-necked flask, 20g of 1,2,2,3-tetrachloropropane, 0.3g of a composite inhibitor, 0.05g of benzyltriethylammonium chloride, and 40g of a 22% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 100°C, and a reflux reaction was carried out under stirring for 11 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. The oil phase was separated by a separating funnel and rectified by a distillation tower to obtain the final product 1,2,3-trichloropropene. The yield of 1,2,3-trichloropropene was 72%, the conversion rate of 1,2,2,3-tetrachloropropane was 75%, and the selectivity of 1,2,3-trichloropropene was 96.1%.

[0058] Example 5

[0059] Add 1 g of p-tert-butylcatechol, 11 g of cesium chloride and 12 g of formamide into a beaker and stir evenly at 25° C. Use potassium hydroxide solution as a regulator to adjust the pH of the solution to 8.0 to obtain a composite inhibitor.

[0060] In a 150mL three-necked flask, 20g of 1,2,2,3-tetrachloropropane, 0.1g of a composite inhibitor, 0.03g of tetrabutylammonium bromide, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. The oil phase was separated by a separating funnel and rectified by a distillation tower to obtain the final product 1,2,3-trichloropropene. The yield of 1,2,3-trichloropropene was 78%, the conversion rate of 1,2,2,3-tetrachloropropane was 80%, and the selectivity of 1,2,3-trichloropropene was 97.6%.

[0061] Comparative Example 1

[0062] In a 150mL three-necked flask, 18.1g of 1,2,2,3-tetrachloropropane, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise. The temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. After suction filtration, separation with a separating funnel, and rectification in a distillation tower, the final product 1,2,3-trichloropropene was obtained. The yield of 1,2,3-trichloropropene was 64%, the conversion rate of 1,2,2,3-tetrachloropropane was 78%, and the selectivity of 1,2,3-trichloropropene was 82%.

[0063] This comparative example is a comparison with Example 1, in which no self-made compound polymerization inhibitor is added, and other conditions are exactly the same as those of Example 1. According to the results, the selectivity and yield of Example 1 with the addition of the self-made polymerization inhibitor are significantly improved.

[0064] Comparative Example 2

[0065] Add 6 g of hydroquinone and 10 g of formamide into a beaker and stir evenly at 30° C. Use sodium bicarbonate solution as a regulator to adjust the solution pH to 8.0 to obtain a single inhibitor.

[0066] In a 150mL three-necked flask, 18.1g of 1,2,2,3-tetrachloropropane, 0.1g of a single polymerization inhibitor, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. After suction filtration, separation with a separating funnel, and rectification in a distillation tower, the final product 1,2,3-trichloropropene was obtained. The yield of 1,2,3-trichloropropene was 64%, the conversion rate of 1,2,2,3-tetrachloropropane was 86%, and the selectivity of 1,2,3-trichloropropene was 80.4%.

[0067] This comparative example is a comparison with Example 1. The comparative example does not contain an inorganic polymerization inhibitor, and other conditions are exactly the same as those of Example 1. According to the results, although the conversion rate of 1,2,2,3-tetrachloropropane is increased without adding an inorganic polymerization inhibitor, the yield and selectivity of 1,2,3-trichloropropene are reduced, indicating that the by-products increase.

[0068] Comparative Example 3

[0069] 6 g of ferric chloride and 10 g of formamide were added to a beaker and stirred evenly at 30° C. Sodium bicarbonate solution was used as a regulator to adjust the pH of the solution to 8.0 to obtain a single inhibitor.

[0070] In a 150mL three-necked flask, 18.1g of 1,2,2,3-tetrachloropropane, 0.1g of a single polymerization inhibitor, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. After suction filtration, separation with a separating funnel, and rectification by a distillation tower, the final product 1,2,3-trichloropropene was obtained. The yield of 1,2,3-trichloropropene was 59%, the conversion rate of 1,2,2,3-tetrachloropropane was 71%, and the selectivity of 1,2,3-trichloropropene was 67.8%.

[0071] This comparative example is a comparison with Example 1. The comparative example does not contain phenolic polymerization inhibitors, and other conditions are exactly the same as those of Example 1. According to the results, without the addition of phenolic polymerization inhibitors, although the conversion rate of 1,2,2,3-tetrachloropropane, the yield and selectivity of 1,2,3-trichloropropene are all reduced, at the same time, the by-products of oligomers or polymers of 1,2,3-trichloropropene are significantly increased.

[0072] Comparative Example 4

[0073] Add 1 g of hydroquinone, 5 g of ferric chloride and 10 g of formamide into a beaker and stir evenly at 30° C. to obtain a composite polymerization inhibitor.

[0074] In a 150mL three-necked flask, 18.1g of 1,2,2,3-tetrachloropropane, 0.1g of a composite inhibitor, 0.01g of benzyltriethylammonium chloride, and 40g of a 25% by mass sodium hydroxide solution were added dropwise, the temperature of the reaction system was maintained at 70°C, and a reflux reaction was carried out under stirring for 12 hours. After the reaction was completed, the reaction liquid was cooled to room temperature, and the oil phase was a mixed solution of the target product 1,2,3-trichloropropene. After suction filtration, separation with a separating funnel, and rectification in a distillation tower, the final product 1,2,3-trichloropropene was obtained. The yield of 1,2,3-trichloropropene was 72.0%, the conversion rate of 1,2,2,3-tetrachloropropane was 84%, and the selectivity of 1,2,3-trichloropropene was 84.2%.

[0075] This comparative example is a comparison with Example 1. In the composite polymerization inhibitor of the comparative example, the pH value of the solution is not adjusted by a regulator, and other conditions are exactly the same as those of Example 1. According to the results, when the pH value of the composite polymerization inhibitor is not adjusted, the selectivity of 1,2,3-trichloropropene is reduced. This may be because when the pH value of the solution is adjusted to 8, part of the ferric chloride in the solution is converted into the form of flocculent ferric hydroxide or its hydrate, and the flocculent ferric hydroxide or its hydrate may work together with phenol to achieve an inhibitory effect.

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A composite polymerization inhibitor for improving the high selectivity of preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane, the composite polymerization inhibitor comprising the following components: Phenolic inhibitors, inorganic compound inhibitors, regulators and solvents; Wherein, the phenolic inhibitor is one or more of hydroquinone, phenol, and p-tert-butylcatechol; The inorganic compound inhibitor is one or more of ferric chloride, potassium chloride, cesium chloride, sodium sulfate, and sodium thiocyanate; The solvent is one or more of formamide, acetonitrile, chloroform, water, ethyl acetate, toluene, and xylene; The regulator is one or more of sodium bicarbonate, sodium carbonate and potassium hydroxide.

2. The composite polymerization inhibitor according to claim 1, characterized in that: The mass ratio of the phenolic polymerization inhibitor, the inorganic compound polymerization inhibitor and the solvent is 1:5-20:10-100, more preferably 1:5-20:10-30.

3. The composite polymerization inhibitor according to claim 1, characterized in that: The amount of the regulator is such that the pH of the final compound inhibitor can be adjusted between 6 and 8.

4. The method for preparing the composite polymerization inhibitor according to any one of claims 1 to 3, comprising the following steps: A. mixing a phenolic polymerization inhibitor and an inorganic compound polymerization inhibitor, stirring to form a mixture; B. adding the mixture prepared in step A to a solvent and stirring to form an inhibitory main body slurry or solution; C. At a temperature of 20-40°C, add the regulator to the inhibitor main slurry or solution to adjust the pH value to between 6 and 8 to form a composite inhibitor.

5. A method for improving the high selectivity of preparing 1,2,3-trichloropropene by dehydrochlorination of 1,2,2,3-tetrachloropropane, comprising the following steps: 1) First, add 1,2,2,3-tetrachloropropane, phase transfer catalyst and polymerization inhibitor into a reactor and stir evenly to form a reaction system; 2) Prepare a sodium hydroxide solution of a certain concentration; 3) Under heating, stirring and certain pressure conditions, the sodium hydroxide solution of step 2) is added dropwise to the reaction system of step 1) and reacted for a period of time until the reaction is completed; 4) There is no solid polymer in the system after the reaction. The oil and water are separated by liquid separation operation, and then the organic phase is further distilled and purified through a distillation tower. The phase transfer catalyst and inhibitor are present in the water phase, and they can be separated and treated by subsequent wastewater treatment.

6. The preparation method according to claim 5, characterized in that: The molar ratio of 1,2,2,3-tetrachloropropane to sodium hydroxide is 1:0.8-3; Preferably, the phase transfer catalyst is a phase transfer catalyst conventionally used in the art, for example, it can be a quaternary ammonium salt phase transfer catalyst, such as benzyltriethylammonium chloride, tetrabutylammonium bromide; Preferably, the mass concentration of the sodium hydroxide solution is 5-30%; Preferably, the phase transfer catalyst accounts for 0.01% to 5% of the mass of 1,2,2,3-tetrachloropropane; Preferably, the compound polymerization inhibitor accounts for 1%-5% of the mass of 1,2,2,3-tetrachloropropane; Preferably, the reaction pressure in step 3) is 1-2 atmospheres; Preferably, the reaction temperature in step 3) is 40-100°C; Preferably, the reaction time in step 3) is 1-14 hours.

Images