Method for efficiently preparing 1, 1, 2, 3-tetrachloropropene and catalyst used in method

Abstract

The invention discloses a method for efficiently preparing 1, 1, 2, 3-tetrachloropropene, which comprises the following steps: by taking 1, 1, 2, 2, 3-pentachloropropane / 1, 1, 1, 2, 3-pentachloropropane as a raw material, carrying out dehydrochlorination reaction in a tank reactor under the action of a composite catalyst to prepare the 1, 1, 2, 3-tetrachloropropene. Compared with the traditional dehydrochlorination of alkali liquor, the method has the advantages of less generation of three wastes, simple process operation and easiness in industrial implementation. The prepared composite catalyst can be suitable for pentachloropropane of different structures as a raw material, the catalyst compatibility is high, the application scene is wide, the composite catalyst is good in catalytic activity and high in selectivity, and the selectivity of tetrachloropropene is 95% or above and can reach 99% to the maximum. Meanwhile, the composite catalyst is good in regeneration performance, the inactivated catalyst is easy to regenerate, and the catalytic activity is not reduced after regeneration; the composite catalyst material is easy to obtain and low in price, the production cost can be greatly saved, and industrial production is facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of chemical synthesis, and more particularly, relates to a method for efficiently preparing 1,1,2,3-tetrachloropropene and a catalyst used therefor. Background Art

[0002] 1,1,2,3-Tetrachloropropene, with the English name Tetracholoropropene, CAS number 10436-39-2; chemical formula C3H2Cl4, appears as a colorless oily liquid, and industrial products often show a brownish-yellow color. The relative density is 1.539 g / cm 3 , the boiling point is 167.3 °C, soluble in organic solvents such as chloroform and carbon tetrachloride, and slightly soluble in water. It is mainly used in the fields of fire extinguishing agents, heat transfer media, propellants, foaming agents, gas dielectrics, pesticide raw materials, and refrigerant raw materials. As a pesticide raw material, it can be used as the main intermediate of the chemical herbicide dicamba emulsifiable concentrate, and is also the main intermediate for preparing the new generation of environmentally friendly refrigerant HFO-1234yf (2,3,3,3-tetrafluoropropene).

[0003] The process routes for preparing 1,1,2,3-tetrachloropropene mainly include the allyl chloride method and the carbon tetrachloride method. Both methods involve the process of dehydrochlorination of pentachloropropane to prepare tetrachloropropene, and the pentachloropropane involved includes 1,1,1,2,3-pentachloropropane and 1,1,2,2,3-pentachloropropane.

[0004] Patent WO2011065574A1 discloses a method for preparing 1,1,2,3-tetrachloropropene. The reaction steps include directly subjecting the obtained 1,1,1,2,3-pentachloropropane to high-temperature cracking to remove hydrogen chloride to obtain 1,1,2,3-tetrachloropropene. When this method is carried out for cracking, the reaction temperature needs to be 350 °C, and at the same time, a large amount of inert gas needs to be introduced to reduce the formation amount of polymers in the reaction tube, resulting in high energy consumption and low production capacity. The selectivity calculation basis described in this method only relies on GC analysis, without performing material balance, and the carbon deposition generated in the actual reactor is not taken into account. The actual reaction selectivity is lower than the stated 97.9%. The above two aspects restrict its large-scale industrial application.

[0005] Patent WO2010123148A1 discloses that after using ethylene and carbon tetrachloride as raw materials to obtain 1,1,1,3-tetrachloropropane, through dehydrochlorination and chlorination, 1,1,1,2,3-pentachloropropane with a purity of 99.6% can be obtained. 1,1,1,2,3-pentachloropropane can continue to be added with 40% potassium hydroxide and a quaternary ammonium salt to remove one molecule of hydrogen chloride, and the reaction obtains a mixture of 1,1,2,3-tetrachloropropene and 2,3,3,3-tetrachloropropene. This process uses a liquid alkali method to remove hydrogen chloride, and a large amount of organic waste salts are produced as by-products during the process.

[0006] Chinese Patent CN101955414A discloses a production process of 1,1,2,3-tetrachloropropene, which includes dehydrochlorination of 1,2,3-trichloropropane in the presence of an alkali solution to obtain 2,3-dichloropropene; chlorination of 2,3-dichloropropene to generate 1,2,2,3-tetrachloropropane; dehydrochlorination of 1,2,2,3-tetrachloropropane in the presence of an alkali solution to obtain 1,2,3-trichloropropene; chlorination of 1,2,3-trichloropropene to generate 1,1,2,2,3-pentachloropropane; rectifying and purifying the obtained 1,1,2,2,3-pentachloropropane; dehydrochlorination of 1,1,2,2,3-pentachloropropane in the presence of an alkali solution to obtain 1,1,2,3-tetrachloropropene. The disadvantages of this method are that the reaction steps are numerous, the time is long, and the economy is insufficient.

[0007] US Patent US8084653 discloses a preparation method of 1,1,2,3-tetrachloropropene. In its reaction steps, 1,1,2,2,3-pentachloropropane is saponified with 25% sodium hydroxide solution to eliminate hydrogen chloride to prepare 1,1,2,3-tetrachloropropene, and the yield is 96%. The disadvantages of this method are that the reaction time is long, the content of by-products is high, and the amount of "three wastes" is large, which is not conducive to industrial production.

[0008] Therefore, it is necessary to develop a method for efficiently preparing 1,1,2,3-tetrachloropropene, reducing the generation of by-products and "three wastes", having a high yield, and being conducive to industrial production. Summary of the Invention

[0009] To solve the above problems, the present invention provides a method for efficiently preparing 1,1,2,3-tetrachloropropene. Using 1,1,2,2,3-pentachloropropane / 1,1,1,2,3-pentachloropropane as raw materials, under the action of a catalyst, dehydrochlorination reaction is carried out in a kettle reactor to prepare 1,1,2,3-tetrachloropropene, which has the characteristics of high selectivity, simple process, low equipment requirements, and easy industrialization.

[0010] According to one aspect of the present invention, an object of the present invention is to provide a method for efficiently preparing 1,1,2,3-tetrachloropropene, and the method includes the following steps:

[0011] 1) Catalyst activation

[0012] Load a composite catalyst in a fixed-bed reactor, introduce nitrogen, heat to a certain temperature to activate the catalyst, and then adjust the temperature to reach the reaction temperature.

[0013] 2) Dehydrochlorination reaction

[0014] The reactants are fed into a preheater through a metering pump for preheating, then enter a vaporizer for gasification, and finally enter a fixed-bed reactor. Under the action of a composite catalyst, dehydrochlorination reaction is carried out at a certain pressure and a certain reaction temperature.

[0015] 3) Product separation:

[0016] The reacted materials are successively passed through a condenser and a gas-liquid separator to separate the liquid reaction mixture.

[0017] 4) Product rectification:

[0018] The liquid reaction mixture is separated by rectification to obtain 1,1,2,3-tetrachloropropene product.

[0019] Preferably, in step 1), the activation temperature is 300 - 500 °C, more preferably 350 - 400 °C; the activation time is 4 - 8 h, more preferably 4 - 5 h.

[0020] Preferably, in step 2), the reaction temperature is 200 - 350 °C, more preferably 200 - 300 °C, such as 200 °C, 220 °C, 240 °C, 260 °C, 280 °C, etc. The values are not limited to those listed above, and other values within the range are equally applicable.

[0021] Preferably, in step 2), the reaction pressure is 0.2 - 0.5 MPa, more preferably 0.2 - 0.4 MPa.

[0022] Preferably, in step 2), the mass hourly space velocity of the reactant feed is 1 - 6 h -1 more preferably 1 - 4 h -1 .

[0023] Preferably, during the reaction process, the preheating temperature is 100 - 180 °C, more preferably 120 - 160 °C, and the vaporization temperature is 150 - 250 °C, more preferably 180 - 230 °C.

[0024] Preferably, in step 2), the reactant is 1,1,2,2,3-pentachloropropane or 1,1,1,2,3-pentachloropropane.

[0025] According to one aspect of the present invention, an object of the present invention is to provide a composite catalyst for preparing 1,1,2,3-tetrachloropropene. The composite catalyst is a supported catalyst, wherein the carrier is activated carbon and the active ingredient is a Lewis acid. Among them, based on the total weight of the composite catalyst, the carrier accounts for 98 - 99.5 wt%, and the active ingredient accounts for 0.5 - 2 wt%.

[0026] Preferably, the activated carbon used as the carrier is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, and coal-based activated carbon.

[0027] Preferably, the Lewis acid as the active ingredient is selected from one or more of BaCl2, CsF, CsCl, FeCl3, CuCl2, etc., and more preferably FeCl3 or CuCl2.

[0028] According to one aspect of the present invention, an object of the present invention is to provide a method for preparing the composite catalyst, and the preparation method includes the following steps:

[0029] 2) Reflux and treat the activated carbon with a 40% by mass nitric acid solution at 85 °C for 6 h;

[0030] 2) Wash with deionized water until weakly acidic, and stop washing when the pH of the washing water is 6.0;

[0031] 3) Vacuum dry at 190 °C for 6 h to remove the adsorbed water on the activated carbon;

[0032] 5) Use a 20% by mass Lewis acid solution as the impregnation solution, take it out after impregnating for an appropriate time;

[0033] 5) Vacuum dry at 110 °C for 6 h;

[0034] 6) Calcinate at 500 °C for 8 h under nitrogen protection to obtain the composite catalyst.

[0035] In the method for preparing the composite catalyst, the activated carbon as the carrier is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, and coal-based activated carbon.

[0036] In the method for preparing the composite catalyst, the Lewis acid as the active ingredient is selected from one or more of BaCl2, CsF, CsCl, FeCl3, CuCl2, etc., and more preferably FeCl3 or CuCl2.

[0037] Beneficial effects

[0038] In the preparation method of 1,1,2,3-tetrachloropropene according to the present invention, a composite catalyst is used for dehydrochlorination reaction. Compared with the traditional alkali solution dehydrochlorination, the generation amount of "three wastes" is small, the process operation is simple, and it is easy to carry out industrial implementation. The composite catalyst prepared by the present invention can be applied to pentachloropropane with different structures as raw materials, has strong catalyst compatibility and wide application scenarios. This composite catalyst has good catalytic activity and high selectivity, and the selectivity of tetrachloropropene is above 95%, up to 99% at most. At the same time, this composite catalyst has good regeneration performance, and the deactivated catalyst is easy to regenerate, and the catalytic activity will not decrease after regeneration; the composite catalyst material of the present invention is easy to obtain and has a low price, which can greatly save production costs and is easy for industrial production. Specific embodiments

[0039] Hereinafter, the present invention will be described in detail. Before the description, it should be understood that the terms used in this specification and the appended claims should not be construed as limited to the general meaning and dictionary meaning, but should be interpreted based on the principle that allows the inventor to appropriately define the terms for the best explanation, according to the meanings and concepts corresponding to the technical aspects of the present invention. Therefore, the description presented here is merely a preferred example for illustrative purposes and is not intended to limit the scope of the present invention. Thus, it should be understood that other equivalent ways or improved ways can be obtained without departing from the spirit and scope of the present invention.

[0040] In this context, the terms "comprising", "including", "having", "containing" or any other similar terms are all open-ended connectives, which are intended to cover non-exclusive inclusions. For example, a composition or article containing plural elements is not limited to only these elements listed herein, but may also include other elements that are not explicitly listed but are normally inherent in the composition or article. In addition, unless there is a clear contrary statement, 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), A and B are both true (or exist). Furthermore, in this context, the interpretations of the terms "comprising", "including", "having", "containing" should be regarded as having specifically disclosed and simultaneously covered closed or semi-closed connectives such as "consisting of" and "substantially consisting of".

[0041] In this context, all features or conditions defined in the form of numerical ranges or percentage ranges are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual values within the range, especially integer values. For example, the range description of "1 to 8" should be regarded as having specifically disclosed all sub-ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially the sub-ranges defined by all integer values, and should be regarded as having specifically disclosed individual values such as 1, 2, 3, 4, 5, 6, 7, 8 within the range. Unless otherwise specified, the foregoing interpretation method applies to all contents of the present invention, regardless of the breadth of the range.

[0042] If a 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 formed by any pair of the upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, whether or not these ranges are separately disclosed. In addition, when a range of numerical values is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0043] In this document, on the premise that the object of the invention can be achieved, a numerical value should be understood to have the precision of the significant digits of that numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0044] In addition, in the heterogeneous catalyst according to the present disclosure, the carrier serves to support and disperse the Lewis acid active ingredient, thereby increasing its surface area and stabilizing the catalyst by preventing sintering. The carrier itself has no activity, but affects the activity of the catalyst due to the above functions. Even when using the same composition, depending on the degree of metal catalyst loading, the difference in catalyst activity becomes larger. Therefore, the selection of the carrier needs to be considered very important.

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

[0046] Preparation Example 1

[0047] Preparation method of FeCl3 / C composite catalyst: Using commercially available coconut shell activated carbon (0.8 - 1.5 mm, between 10 - 20 mesh, cylindrical particles), 50 g of activated carbon was placed in a three-necked flask, 20 ml of nitric acid solution with a mass fraction of 40% was added, and reflux treatment was carried out at 85 °C for 6 h. After the treatment, the activated carbon was filtered out, washed with deionized water until weakly acidic until the pH of the washing water was 6.0. The activated carbon was dried in a vacuum oven at 190 °C for 6 h, taken out and cooled to room temperature. The activated carbon was placed in a beaker, 50 ml of FeCl3 solution with a mass fraction of 20% was added for impregnation. The impregnated sample was vacuum dried at 110 °C for 6 h, and then in a tube furnace, under the condition of nitrogen protection, the sample was carbonized at 500 °C for 8 h. The prepared sample was the FeCl3 / C composite catalyst.

[0048] Preparation Example 2

[0049] Preparation method of CuCl2 / C composite catalyst: Use commercially available coconut shell activated carbon (0.8 - 1.5 mm, between 10 - 20 meshes, cylindrical particles). Place 50 g of activated carbon in a three-necked flask, add 20 ml of nitric acid solution with a mass fraction of 40%, reflux at 85 °C for 6 h. After the treatment, filter out the activated carbon, wash it with deionized water until it is weakly acidic until the pH of the washing water is 6.0. Dry the activated carbon in a vacuum oven at 190 °C for 6 h, take it out and let it cool to room temperature. Place the activated carbon in a beaker, add 50 ml of CuCl2 solution with a mass fraction of 20%, and carry out impregnation. The impregnated sample is vacuum dried at 110 °C for 6 h, and then in a tubular furnace, under the condition of nitrogen protection, carbonize the sample at 500 °C for 8 h. The prepared sample is the CuCl2 / C composite catalyst.

[0050] Example 1

[0051] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0052] Add 10 g of the freshly prepared FeCl3 / C composite catalyst prepared in Preparation Example 1 to a fixed-bed reactor, with a space velocity of 350 h -1 Introduce oxygen-depleted nitrogen as the carrier gas, heat up to 350 °C to activate the catalyst for 4 h. After the activation is completed, wait for the temperature to drop to the required reaction temperature. Feed 1,1,2,2,3-pentachloropropane into the preheater at a mass space velocity of 1.0 h -1 The material is preheated at 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 230 °C. The reaction pressure is 0.1 MPa. During the reaction process, continuously introduce the carrier gas oxygen-depleted nitrogen. After reacting for 10 hours, sample the reactants after condensation and separation through a condenser and a gas-liquid separator, and conduct gas chromatography analysis. Distill the reactants to obtain 1,1,2,3-tetrachloropropene product. The test results are shown in Table 1 below.

[0053] Example 2

[0054] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0055] Add 10 g of the freshly prepared FeCl3 / C composite catalyst prepared in Preparation Example 1 to a fixed-bed reactor, with a space velocity of 350 h -1 Introduce oxygen-depleted nitrogen as the carrier gas, heat up to 350 °C to activate the catalyst for 4 h. After the activation is completed, wait for the temperature to drop to the required reaction temperature. Feed 1,1,2,2,3-pentachloropropane into the preheater at a mass space velocity of 1.0 h -1It enters the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 250 °C. The reaction pressure is 0.15 MPa. During the reaction, oxygen-deficient nitrogen gas is continuously introduced as the carrier gas. After reacting for 10 hours, the reactants are condensed and separated by a condenser and a gas-liquid separator, sampled, and analyzed by gas chromatography. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene product, and the test results are shown in Table 1 below.

[0056] Example 3

[0057] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0058] 10 g of the fresh FeCl3 / C composite catalyst prepared in Preparation Example 1 is added to the fixed-bed reactor, and the space velocity is 350 h -1 Oxygen-deficient nitrogen gas is introduced as the carrier gas, the temperature is raised to 350 °C to activate the catalyst for 4 h. After the activation is completed, wait for the temperature to drop to the required reaction temperature. 1,1,2,2,3-pentachloropropane is fed into the preheater at a mass space velocity of 1.0 h -1 It enters the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 250 °C. The reaction pressure is 0.2 MPa. During the reaction, oxygen-deficient nitrogen gas is continuously introduced as the carrier gas. After reacting for 10 hours, the reactants are condensed and separated by a condenser and a gas-liquid separator, sampled, and analyzed by gas chromatography. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene product, and the test results are shown in Table 1 below.

[0059] Example 4

[0060] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0061] 10 g of the fresh CuCl2 / C composite catalyst prepared in Preparation Example 2 is added to the fixed-bed reactor, and the space velocity is 350 h -1 Oxygen-deficient nitrogen gas is introduced as the carrier gas, the temperature is raised to 350 °C to activate the catalyst for 4 h. After the activation is completed, wait for the temperature to drop to the required reaction temperature. 1,1,2,2,3-pentachloropropane is fed into the preheater at a mass space velocity of 1.0 h -1It enters the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 230 °C. The reaction pressure is 0.1 MPa. During the reaction, oxygen-deficient nitrogen is continuously introduced. After reacting for 12 hours, the reactants are condensed and separated by a condenser and a gas-liquid separator and then sampled for gas chromatography analysis. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene product, and the test results are shown in Table 1 below.

[0062] Example 5

[0063] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0064] 10 g of the fresh CuCl2 / C composite catalyst prepared in Preparation Example 2 was added to the fixed-bed reactor, and at a space velocity of 350 h -1 Oxygen-deficient nitrogen was introduced as the carrier gas, and the temperature was raised to 350 °C to activate the catalyst for 4 h. After the activation was completed, the temperature was waited to drop to the required reaction temperature. 1,1,2,2,3-pentachloropropane was passed through a metering pump at a rate of 1.0 h -1 It enters the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 250 °C. The reaction pressure is 0.15 MPa. During the reaction, the carrier gas oxygen-deficient nitrogen is continuously introduced. After reacting for 12 hours, the reactants are condensed and separated by a condenser and a gas-liquid separator and then sampled for gas chromatography analysis. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene product, and the test results are shown in Table 1 below.

[0065] Example 6

[0066] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0067] 10 g of the fresh CuCl2 / C composite catalyst prepared in Preparation Example 2 was added to the fixed-bed reactor, and at a space velocity of 350 h -1 Oxygen-deficient nitrogen was introduced as the carrier gas, and the temperature was raised to 350 °C to activate the catalyst for 4 h. After the activation was completed, the temperature was waited to drop to the required reaction temperature. 1,1,2,2,3-pentachloropropane was passed through a metering pump at a rate of 1.0 h -1Enter the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 250 °C. The reaction pressure is 0.2 MPa. During the reaction, an inert gas, oxygen-deficient nitrogen, is continuously introduced. After reacting for 12 hours, the reactants are sampled after being condensed and separated by a condenser and a gas-liquid separator, and subjected to gas chromatography analysis. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene products. The test results are shown in Table 1 below.

[0068] Comparative Example 1

[0069] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0070] Add 10 g of deactivated FeCl3 / C composite catalyst (the deactivation of the composite metal catalyst is due to the formation of tar and coke on the surface during the use of the catalyst, which reduces the activity of the catalyst and leads to deactivation) to the fixed-bed reactor. With a space velocity of 350 h -1 Introduce oxygen-deficient nitrogen as an inert gas, heat up to 350 °C to activate the catalyst for 4 h. After the activation is completed, wait for the temperature to drop to the required reaction temperature. Feed 1,1,2,2,3-pentachloropropane into the preheater at a mass space velocity of 1.0 h -1 Enter the preheater at a mass space velocity, the material is preheated to 130 °C in the preheater, enters the vaporizer, is vaporized at 200 °C in the vaporizer and enters the fixed-bed reactor, and reacts at 230 °C. The reaction pressure is 0.1 MPa. During the reaction, an inert gas, oxygen-deficient nitrogen, is continuously introduced. After reacting for 20 hours, the reactants are sampled after being condensed and separated by a condenser and a gas-liquid separator, and subjected to gas chromatography analysis. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene products. The test results are shown in Table 1 below.

[0071] Comparative Example 2

[0072] This example provides a method for preparing 1,1,2,3-tetrachloropropene from 1,1,2,2,3-pentachloropropane.

[0073] Add 10 g of the fresh FeCl3 / C composite catalyst prepared in Preparation Example 1 to the fixed-bed reactor. Feed 1,1,2,2,3-pentachloropropane into the preheater at a mass space velocity of 1.0 h -1It enters the preheater at a mass space velocity, and the material is preheated to 130 °C in the preheater and then enters the vaporizer. It is vaporized to 200 °C in the vaporizer and enters the fixed-bed reactor, where it reacts at 230 °C. The reaction pressure is 0.1 MPa. During the reaction, carrier gas nitrogen is continuously introduced. After 10 hours of reaction, the reactants are condensed and separated through a condenser and a gas-liquid separator, and then sampled for gas chromatography analysis. The reactants are rectified to obtain 1,1,2,3-tetrachloropropene product, and the test results are shown in Table 1 below. The difference between Comparative Example 2 and Example 1 is that the catalyst activation was not carried out, and it was found that the effect was not good.

[0074] Table 1

[0075]

[0076] Example 7

[0077] The FeCl3 / C catalyst prepared in Example 1 was selected and its catalyst life was investigated under the condition of a reaction temperature of 230 °C. The specific results are shown in Table 2.

[0078] Table 2

[0079]

[0080]

[0081] It can be seen from Table 2 that the FeCl3 / C catalyst can operate stably at least for 400 hours under the condition of 230 °C. It can be seen that this catalyst has a certain stability and is suitable for industrial production.

[0082] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for efficiently preparing 1,1,2,3 - tetrachloropropene, the method comprising the following steps: 1) Catalyst activation Load a composite catalyst into a fixed - bed reactor, introduce nitrogen, heat to a certain temperature to activate the catalyst, and then adjust the temperature to the reaction temperature; 2) Dehydrochlorination reaction Feed the reactant into a pre - heater through a metering pump for pre - heating, then into a vaporizer for gasification, and finally into a fixed - bed reactor. Under the action of the composite catalyst, carry out the dehydrochlorination reaction at a certain pressure and a certain reaction temperature; 3) Product separation Feed the reaction mixture successively through a condenser and a gas - liquid separator to separate the liquid reaction mixture; 4) Product rectification Carry out rectification separation on the liquid reaction mixture to obtain a tetrachloropropene product.

2. The method according to claim 1, characterized in that: Preferably, in step 1), the activation temperature is 300 - 500 °C, more preferably 350 - 400 °C; the activation time is 4 - 8 h, more preferably 4 - 5 h.

3. The method according to claim 1, characterized in that: Preferably, in step 2), the reaction temperature is 200 - 350 °C, more preferably 200 - 300 °C, such as 200 °C, 220 °C, 240 °C, 260 °C, 280 °C; Preferably, in step 2), the reaction pressure is 0.2 - 0.5 MPa, more preferably 0.2 - 0.4 MPa; Preferably, the mass hourly space velocity of the reactant feed in step 2) is 1 to 6 h -1 , more preferably 1 to 4 h -1 ; Preferably, during the reaction process, the pre - heating temperature is 100 - 180 °C, more preferably 120 - 160 °C, the vaporization temperature is 150 - 250 °C, more preferably 180 - 230 °C; Preferably, in step 2), the reactant is 1,1,2,2,3 - pentachloropropane or 1,1,1,2,3 - pentachloropropane.

4. A composite catalyst for preparing 1,1,2,3-tetrachloropropene, the composite catalyst being a supported catalyst, wherein the carrier is activated carbon and the active ingredient is a Lewis acid, wherein, Based on the total weight of the composite catalyst, the carrier accounts for 98 - 99.5 wt%, and the active ingredient accounts for 0.5 - 2 wt%.

5. The composite catalyst according to claim 4, characterized in that: The activated carbon used as the carrier is selected from one or more of coconut shell - type activated carbon, fruit shell - type activated carbon, and coal - based activated carbon.

6. The composite catalyst according to claim 4, characterized in that: The Lewis acid used as the active ingredient is selected from one or more of BaCl2, CsF, CsCl, FeCl3, and CuCl2, etc., and more preferably FeCl3 or CuCl2.

7. The preparation method of the composite catalyst according to claim 4, the preparation method comprising the following steps: 1) Reflux - treat the activated carbon with a 40% mass - fraction nitric acid solution at 85 °C for 6 h; 2) Wash with deionized water until weakly acidic, and stop washing when the pH of the washing water is 6.0; 3) Vacuum - dry at 190 °C for 6 h to remove the adsorbed water on the activated carbon; 4) Use a 20% mass - fraction Lewis acid solution as the impregnation solution, impregnate for an appropriate time, and then take out; 5) Vacuum - dry at 110 °C for 6 h; 6) Calcinate at 500 °C for 8 h under nitrogen protection to obtain the composite catalyst.

8. The method according to claim 7, characterized in that: The activated carbon used as a carrier is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, and coal-based activated carbon.

9. The method according to claim 7, wherein: The Lewis acid used as an active ingredient is selected from one or more of BaCl2, CsF, CsCl, FeCl3, CuCl2, etc., and more preferably FeCl3 or CuCl2.

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