Isomeric tetrachloroethylene stabilizer, isomeric tetrachloroethylene and preparation method thereof

Abstract

The present invention relates to the technical field of tetrachloroethylene, and provides an isomeric tetrachloroethylene stabilizer, isomeric tetrachloroethylene and a preparation method thereof. The isomeric tetrachloroethylene stabilizer provided by the present invention includes propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide, and the stabilizer has a good stabilizing effect, and a small amount of addition can achieve the purpose of stabilizing tetrachloroethylene, and is suitable for the preparation of isomeric tetrachloroethylene. The isomeric tetrachloroethylene prepared by the present invention has high purity, good chromaticity, low moisture content, no hydrolysis, and no corrosiveness, is suitable for petrochemical isomerization and catalytic reforming, and plays an important auxiliary catalytic role in the petrochemical aromatics industry. Further, the present invention also improves the purity of the tetrachloroethylene raw material by distillation and deacidification, reduces its moisture content and acidity, and then ensures that the various quality indicators of the obtained isomeric tetrachloroethylene meet the requirements.

Description

Technical Field

[0001] The invention relates to the technical field of tetrachloroethylene, and in particular to an isomerized tetrachloroethylene stabilizer, isomerized tetrachloroethylene and a preparation method thereof. Background Art

[0002] Tetrachloroethylene, also known as perchloroethylene, is a compound formed by replacing all hydrogen atoms in ethylene with chlorine in terms of molecular structure. It is a colorless, transparent liquid with an ether-like odor, is non-flammable, and is miscible with organic solvents such as ethanol, ether, chloroform, and benzene, and does not hydrolyze.

[0003] In the production of petroleum reforming isomerization, tetrachloroethylene can be combined with platinum-containing catalysts (such as Pt / Al2O3-Cl) to form a composite catalyst. The composite catalyst can promote the decomposition and recombination of petroleum molecules, thereby improving the yield and quality of petroleum products. At the same time, in the process of petroleum reforming isomerization, the chlorine content of catalysts such as Pt / Al2O3-Cl may decrease due to continuous high-temperature operation, chlorine loss or reaction with other chemicals. If sufficient chlorine is not added, the activity and selectivity of the catalyst will seriously decrease or even completely lose its activity. As a chlorine supplement, tetrachloroethylene can help restore the chlorine content of the catalyst and maintain the activity of the catalyst. The role of tetrachloroethylene as a chlorinating agent is mainly reflected in the following aspects: (1) Enhance the acidity of the catalyst: The hydrogen chloride or chlorine produced by the decomposition of tetrachloroethylene can react with the catalyst surface to form a strong acid center. This acidic environment helps to promote the chemical bond breaking and rearrangement of the crude oil molecules, thereby realizing the isomerization process. (2) Improve the activity and selectivity of the catalyst: By adjusting the dosage of the chlorinating agent and the reaction environment, the acidity of the catalyst can be precisely adjusted, thereby controlling the selectivity and reaction rate of the product. As a chlorinating agent, tetrachloroethylene can stabilize and optimize the acidic environment on the catalyst surface, improving the activity and selectivity of the reaction. (3) Preventing catalyst poisoning and deactivation: Under certain conditions, tetrachloroethylene can decompose, provide a chlorine source, reactivate the inactive catalyst, extend its service life and improve production stability.

[0004] During storage or use, tetrachloroethylene is easily affected by light, air, heat, moisture or metal and decomposes to produce acidic substances or tar-like substances such as hydrochloric acid, phosgene, trichloroacetic acid, etc. These decomposition products are easy to corrode equipment. In order to prevent the decomposition of tetrachloroethylene, stabilizers are usually added to maintain its chemical stability and extend its service life. However, the tetrachloroethylene injected in the petroleum isomerization process is required to have a high purity, otherwise it will affect the activity and life of the isomerization catalyst. Therefore, a lower amount of stabilizer is required in isomerization-grade tetrachloroethylene. On the basis of ensuring the storage requirements, the purity of tetrachloroethylene must be high and must not affect the activity and life of the isomerization catalyst.

[0005] Existing stabilizers for tetrachloroethylene mainly include cycloalkane compounds, phenol compounds and hydroxy compounds, etc. However, these stabilizers are usually suitable for dry-cleaning grade tetrachloroethylene, and require a large amount of addition, resulting in low purity of tetrachloroethylene, which cannot meet the requirements of isomerized grade tetrachloroethylene. Summary of the invention

[0006] In view of this, the present invention provides an isomerized tetrachloroethylene stabilizer, isomerized tetrachloroethylene and a preparation method thereof. The isomerized tetrachloroethylene stabilizer provided by the present invention has good stabilizing effect, a small amount of addition in tetrachloroethylene, and is suitable for the preparation of isomerized tetrachloroethylene; the isomerized tetrachloroethylene prepared by using the stabilizer of the present invention has high purity, good chromaticity, and low moisture content, and meets the requirements of isomerized tetrachloroethylene.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] An isomerization-grade tetrachloroethylene stabilizer comprises the following components: glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide; the mass ratio of the glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide is (1-3):(1-3):(1-3).

[0009] Preferably, the purity of the propylene oxide is ≥97%, and the moisture content is ≤0.1wt%; the purity of the 2,6-di-tert-butyl-p-cresol is ≥99.0%, and the moisture content is ≤0.1wt%; the purity of the butylene oxide is ≥99.0%, and the moisture content is ≤0.02wt%.

[0010] The present invention also provides an isomerized tetrachloroethylene, comprising tetrachloroethylene and a stabilizer; the stabilizer is the isomerized tetrachloroethylene stabilizer described in the above scheme; the content of the stabilizer in the isomerized tetrachloroethylene is 0.0003wt%~0.0009wt%; the purity of the isomerized tetrachloroethylene is ≥99.97%, the water mass content is ≤25ppm, the pH value is 7~7.5, and the chromaticity is ≤10.

[0011] The present invention also provides a method for preparing isomeric tetrachloroethylene described in the above scheme, comprising the following steps:

[0012] The stabilizer and the tetrachloroethylene raw material are mixed to obtain the isomerized tetrachloroethylene; the purity of the tetrachloroethylene raw material is ≥99.97%, the water mass content is ≤25ppm, the pH value is 6.5-7.5, and the chromaticity is ≤10.

[0013] Preferably, the mixing comprises: mixing the stabilizer with a portion of the tetrachloroethylene raw material to obtain a stabilizer solution, and then mixing the stabilizer solution with the remaining portion of the tetrachloroethylene raw material.

[0014] Preferably, the method for preparing the tetrachloroethylene raw material comprises: sequentially distilling and removing acid from industrial-grade tetrachloroethylene to obtain the tetrachloroethylene raw material; the purity of the industrial-grade tetrachloroethylene is 99.90% to 99.93% or 99.93% to 99.95%.

[0015] Preferably, the distillation is carried out in a distillation tower; the total number of sections of the packing layer in the distillation tower is 7, which are recorded as the first packing section to the seventh packing section from bottom to top; the distillation tower is provided with a first feed inlet, a second feed inlet, a side line outlet and a reflux inlet; the first feed inlet is arranged above the first packing section, the second feed inlet is arranged above the second packing section, the side line outlet is arranged below the seventh packing section, and the reflux inlet is arranged above the seventh packing section.

[0016] Preferably, during the distillation, industrial-grade tetrachloroethylene with a purity of 99.90% to 99.93% is fed from the first feed port, and industrial-grade tetrachloroethylene with a purity of 99.93% to 99.95% is fed from the second feed port.

[0017] Preferably, the distillation conditions include: the liquid level of the distillation tower is 60%-85%, the reflux ratio is 3-5:1, the top operating pressure is less than 10KPa, the top temperature is 119-125°C, and the bottom temperature is less than 128°C.

[0018] Preferably, the acid removal reagent includes an adsorbent and a neutralizer; the adsorbent is sintered silica gel, and the neutralizer is anhydrous sodium carbonate; the mass ratio of the adsorbent to the neutralizer is 1:1~5.

[0019] The present invention provides an isomeric tetrachloroethylene stabilizer, comprising the following components: glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide; the mass ratio of glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide is (1-3):(1-3):(1-3). The isomeric tetrachloroethylene stabilizer of the present invention comprises glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide, wherein the stabilization principle of each component is as follows:

[0020] Glycidol is a multifunctional compound that contains hydroxyl and epoxy groups in its structure. It has high chemical reactivity, which enables it to stabilize tetrachloroethylene. The main mechanisms of action of glycidol as a stabilizer are as follows: (1) Antioxidant: Glycidol can capture free radicals and prevent tetrachloroethylene from decomposing in the presence of oxygen, thereby extending its service life. (2) pH buffering effect: The hydroxyl groups in glycidol can react with acidic substances to neutralize the solution, maintain the pH level of the solution, and prevent the decomposition of tetrachloroethylene under acidic conditions. (3) Complexation: Glycidol can form complexes with metal ions, reducing the catalytic decomposition of tetrachloroethylene by metal ions. (4) Adsorption: Glycidol can adsorb on the surface of tetrachloroethylene to form a protective layer, reducing the influence of external factors (such as light and temperature) on its decomposition.

[0021] As an antioxidant, the stabilizer mechanism of 2,6-di-tert-butyl-p-cresol is as follows: (1) Free radical capture: During the use of tetrachloroethylene, oxidation reactions may occur to generate free radicals, which further lead to the decomposition of tetrachloroethylene. 2,6-di-tert-butyl-p-cresol can capture the generated free radicals and prevent the free radical chain reaction, thereby preventing the oxidative decomposition of tetrachloroethylene. (2) Antioxidant protection: 2,6-di-tert-butyl-p-cresol reacts with oxygen to generate stable peroxides, reducing the oxidative effect of oxygen on tetrachloroethylene. (3) Thermal stability: 2,6-di-tert-butyl-p-cresol has excellent stability at high temperatures and can effectively prevent the decomposition of tetrachloroethylene under high temperature conditions.

[0022] The mechanism of butylene oxide as a stabilizer in tetrachloroethylene is as follows: (1) Free radical capture: butylene oxide may react with free radicals through its epoxy group, thereby capturing free radicals and reducing the oxidative decomposition of tetrachloroethylene. For example, the epoxy group can react with the generated free radicals to prevent the chain reaction. (2) Acid neutralization: Under certain conditions, tetrachloroethylene may generate acidic byproducts. Butylene oxide can react with acidic substances through its reactive epoxy group to achieve the purpose of neutralization and prevent the decomposition of tetrachloroethylene under acidic conditions. (3) Complexation: Butylene oxide can form complexes with metal impurities, thereby reducing the catalytic decomposition pathway.

[0023] In summary, the isomerized tetrachloroethylene stabilizer provided by the present invention has good stabilizing effect, and can achieve the purpose of stabilizing tetrachloroethylene by adding a small amount thereof, and is suitable for the preparation of isomerized tetrachloroethylene.

[0024] Furthermore, the glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide used in the present invention have high purity and low water content, which can avoid the introduction of water and impurities into the isomerization-grade tetrachloroethylene, and further avoid affecting the activity and life of the petroleum isomerization catalyst.

[0025] The present invention also provides an isomerized tetrachloroethylene, comprising tetrachloroethylene and a stabilizer; the stabilizer is the isomerized tetrachloroethylene stabilizer described in the above scheme; the content of the stabilizer in the isomerized tetrachloroethylene is 0.0003wt%~0.0009wt%; the purity of the isomerized tetrachloroethylene is ≥99.97%, the water mass content is ≤25ppm, the pH value is 7~7.5, and the chromaticity is ≤10. The isomerized tetrachloroethylene provided by the present invention has high purity and low stabilizer content, can meet storage requirements, and at the same time has good chromaticity, low water content, no hydrolysis, no corrosiveness, can meet the requirements of isomerized tetrachloroethylene, can be used for petrochemical isomerization and catalytic reforming, and plays an important auxiliary catalytic role in the petrochemical aromatics industry.

[0026] The present invention also provides a method for preparing the isomeric-grade tetrachloroethylene described in the above scheme. The preparation method provided by the present invention has simple steps, is easy to operate, and is suitable for large-scale production.

[0027] Furthermore, the present invention also distills and removes acid from industrial-grade tetrachloroethylene to obtain the tetrachloroethylene raw material. The present invention improves the purity of the raw material and reduces the moisture content and acidity through distillation and deacidification, thereby ensuring that the purity, moisture content, pH value and other indicators of the obtained isomerized-grade tetrachloroethylene meet the requirements. DETAILED DESCRIPTION

[0028] The invention provides an isomeric tetrachloroethylene stabilizer, comprising the following components: glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide; the mass ratio of the glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide is (1-3):(1-3):(1-3).

[0029] In the present invention, the mass ratio of the glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide is preferably (1-2):(1-2):(1-2).

[0030] In the present invention, the purity of the glycidol is preferably ≥97%, and the water content is preferably ≤0.1wt%; the purity of the 2,6-di-tert-butyl-p-cresol is preferably ≥99.0%, and the water content is preferably ≤0.1wt%; the purity of the butylene oxide is preferably ≥99.0%, and the water content is preferably ≤0.02wt%. Isomeric tetrachloroethylene has high requirements for water content, which is less than 25ppm, so as to reduce the water in the system as much as possible and protect the catalyst; the present invention controls the purity and water content of glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide within the above range, which can avoid the introduction of water and impurities into tetrachloroethylene, thereby avoiding affecting the activity and life of the petroleum isomerization catalyst.

[0031] The present invention also provides an isomerized tetrachloroethylene, comprising tetrachloroethylene and a stabilizer, wherein the stabilizer is the isomerized tetrachloroethylene stabilizer described in the above scheme; the content of the stabilizer in the isomerized tetrachloroethylene is 0.0003wt%~0.0009wt%; the purity of the isomerized tetrachloroethylene is ≥99.97%, preferably 99.9710~99.9725%, the water mass content is ≤25ppm, preferably 15~25ppm, the pH value is 7~7.5, and the chromaticity is ≤10. In the present invention, the content of the stabilizer in the isomerized tetrachloroethylene is preferably 0.006wt%~0.009wt%; specifically, the content of glycidol in the isomerized tetrachloroethylene is 0.0001wt%~0.0003wt%, preferably 0.0002wt%~0.0003wt%, the content of 2,6-di-tert-butyl-p-cresol is 0.0001wt%~0.0003wt%, preferably 0.0002wt%~0.0003wt%, and the content of butylene oxide is 0.0001wt%~0.0003wt%, preferably 0.0002wt%~0.0003wt%.

[0032] The present invention also provides a method for preparing isomeric tetrachloroethylene, comprising the following steps:

[0033] The stabilizer is mixed with a tetrachloroethylene raw material to obtain isomerized tetrachloroethylene;

[0034] The purity of the tetrachloroethylene raw material is ≥99.97%, the water content is ≤25ppm, the pH value is 6.5-7.5, and the chromaticity is ≤10.

[0035] First, the preparation method of the tetrachloroethylene raw material is described.

[0036] In the present invention, the method for preparing the tetrachloroethylene raw material preferably comprises: sequentially rectifying and deacidifying industrial-grade tetrachloroethylene to obtain the tetrachloroethylene raw material. In the present invention, the industrial-grade tetrachloroethylene is preferably industrial-grade type I tetrachloroethylene; the purity of the industrial-grade tetrachloroethylene is preferably ≥99.9%, more preferably 99.91%~99.95%, specifically, the purity of the industrial-grade tetrachloroethylene used in the present invention is 99.90%~99.93% or 99.93%~99.95%, and industrial-grade tetrachloroethylene of different purities is fed from different feed ports during rectification, which will be described in detail later; the water content of the industrial-grade tetrachloroethylene is preferably ≤50ppm, more preferably 30~40ppm, the pH value is preferably 5~8, more preferably 6.5~7, and the chromaticity is preferably ≤10; in the present invention, the chromaticity is the Hazen unit platinum-cobalt color number.

[0037] In the present invention, the distillation is preferably carried out in a distillation tower; the total number of sections of the packing layer in the distillation tower is preferably 7 sections, which are recorded as the first section of packing to the seventh section of packing from bottom to top; the packing of the packing layer in the distillation tower is preferably a wire mesh packing; the distillation tower is preferably provided with a first feed port, a second feed port, a side line outlet and a reflux port; the first feed port is preferably arranged above the first section of packing, the second feed port is preferably arranged above the second section of packing, the side line outlet is preferably arranged below the seventh section of packing, and the reflux port is preferably arranged above the seventh section of packing; in a specific embodiment of the present invention, the diameter of the distillation tower is preferably 1000~1200mm, and the tower height is preferably 50m; the top of the distillation tower is provided with a top condenser, and the bottom of the tower is provided with a bottom reboiler; the caliber of the first feed and second feed ports is preferably DN25.

[0038] In the present invention, during the distillation, industrial-grade tetrachloroethylene with a purity of 99.90% to 99.93% is preferably fed from the first feed port, and industrial-grade tetrachloroethylene with a purity of 99.93% to 99.95% is preferably fed from the second feed port.

[0039] In the present invention, the operating conditions of the distillation preferably include: the liquid level of the distillation tower is 60%~85%, preferably 70%~80%, the reflux ratio is 3~5:1, preferably 4:1, the top operating pressure is slightly positive, specifically <10KPa, the top temperature is 119~125℃, more preferably 121℃, the bottom temperature is <128℃, preferably 123℃≤bottom temperature<128℃; in a specific embodiment of the present invention, when the bottom liquid temperature of the distillation tower is ≥128℃, the bottom liquid is extracted. In a specific embodiment of the present invention, the processing capacity of the distillation tower is preferably 1~1.5m 3 / h, the reflux rate is preferably 3~5m 3 / h, the content of tetrachloroethylene in the reflux liquid is preferably >99.97%, and the side line production volume is preferably 1m 3 / h.

[0040] In the present invention, the purity of the tetrachloroethylene extracted from the side line of the distillation tower is preferably ≥99.97%, the water content is preferably ≤25ppm, the pH value is preferably 6-6.5, the acidity in terms of HCl is preferably <5ppm, and the chromaticity is preferably ≤10.

[0041] In the present invention, the deacidification reagent preferably includes an adsorbent and a neutralizer; the adsorbent is preferably sintered silica gel, and the neutralizer is preferably anhydrous sodium carbonate; the mass ratio of the adsorbent to the neutralizer is preferably 1:1~5, more preferably 1:2; the deacidification is preferably carried out in a deacidifier, specifically, the adsorbent and the neutralizer are filled in the deacidifier, and then the distilled tetrachloroethylene is introduced into the deacidifier for deacidification; in a specific embodiment of the present invention, the distilled tetrachloroethylene is preferably pumped into the deacidifier by a circulation pump, and the deacidification is preferably circulated for 3 times; the tetrachloroethylene raw material is obtained after deacidification; the present invention can reduce the acidity of tetrachloroethylene by deacidification, and the purity can also be increased by 10~30ppm compared with the distilled tetrachloroethylene.

[0042] In the present invention, the purity of the tetrachloroethylene raw material is ≥99.97%, the water content is ≤25ppm, the pH value is 6.5-7.5, and the chromaticity is ≤10; the acidity of the tetrachloroethylene raw material in terms of HCl is preferably <1ppm.

[0043] The preparation method of the isomeric-grade tetrachloroethylene is described in detail below.

[0044] The present invention mixes the stabilizer with a tetrachloroethylene raw material to obtain isomeric tetrachloroethylene; the stabilizer is the isomeric tetrachloroethylene stabilizer described in the above scheme. In the present invention, the mixing preferably includes: mixing the stabilizer with a portion of the tetrachloroethylene raw material to obtain a stabilizer solution, and then mixing the stabilizer solution with the remaining portion of the tetrachloroethylene raw material. In the present invention, the method of mixing the stabilizer with a portion of the tetrachloroethylene raw material preferably includes method one or method two; the method one preferably includes: adding the stabilizer to a portion of the tetrachloroethylene raw material, stirring for 30 minutes, and obtaining the stabilizer solution; the method two preferably includes: first adding 2,6-di-tert-butyl-p-cresol to butylene oxide, and at the same time adding a portion of the tetrachloroethylene raw material, stirring until the solid reagent is completely dissolved, and then adding propylene oxide, and continuing to stir until the mixture is uniform. In the mixing process of the method one and the method two, the stirring is carried out under normal temperature and pressure sealed conditions. The present invention has no special requirements for the specific amount of the portion of the tetrachloroethylene raw material, and the stabilizer can be dissolved.

[0045] After obtaining the stabilizer solution, the present invention mixes the stabilizer solution with the remaining part of the tetrachloroethylene raw material to obtain isomerized tetrachloroethylene. The present invention has no special requirements for the specific method of mixing, as long as uniform mixing can be achieved.

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the following examples, the purity of the glycidol used is ≥97%, and the moisture content is ≤0.1wt%; the purity of 2,6-di-tert-butyl-p-cresol is ≥99.0%, and the moisture content is ≤0.1wt%; the purity of butylene oxide is ≥99.0%, and the moisture content is ≤0.02wt%.

[0048] Example 1

[0049] Type I industrial grade tetrachloroethylene with a purity of 99.90-99.95% is distilled. The distillation tower has a diameter of 1200mm and is filled with seven sections of wire mesh packing. The processing capacity is 1.5m 3 / h, the operating parameters of the distillation tower are as follows: the top operating pressure is slightly positive (<10KPa), the liquid level is 70%, the top temperature is 121℃, the bottom temperature is controlled at 123℃ or more and less than 128℃, and the reflux rate is 4m 3 / h, the kettle liquid extraction temperature is ≥128℃, and the side line extraction volume is 1m 3 / h.

[0050] Two feed ports are set for feed components of different purities, and the diameter of the feed ports is DN25. The first feed port is located above the first section of filler, and the type I industrial-grade tetrachloroethylene with a purity of 99.90%~99.93% is fed through this feed port. The second feed port is located above the second section of filler, and the type I industrial-grade tetrachloroethylene with a purity of 99.93%~99.95% is fed through this feed port; the reflux port is located above the seventh section of filler, and the side line outlet is located below the seventh section of filler. The purity of tetrachloroethylene extracted from the side line is ≥99.97%, the water content is ≤25ppm, the pH value is 6~6.5, the acidity is <5ppm in terms of HCl, and the color is 10.

[0051] The distilled tetrachloroethylene is passed through the deacidifier through a circulation pump for deacidification. The deacidifier is filled with adsorbent and neutralizer, with a total filling volume of 3m 3 , the mass ratio of the adsorbent to the neutralizer is 1:2, the adsorbent is sintered silica gel, the neutralizer is anhydrous sodium carbonate, and a circulating pump is used to circulate the distilled tetrachloroethylene for deacidification 3 times to obtain a tetrachloroethylene raw material. The purity of the tetrachloroethylene raw material obtained in this embodiment is ≥99.97%, the acidity is <1ppm in terms of HCl, the pH value is 6.5-7.5, the water mass content is ≤25ppm, and the chromaticity is 10.

[0052] The tetrachloroethylene raw material prepared in Example 1 was used in the preparation of isomerized tetrachloroethylene in the subsequent examples.

[0053] Example 2

[0054] Taking the contents of glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide in isomerized tetrachloroethylene as influencing factors, an orthogonal experiment was carried out according to Table 1 and Table 2. The operation steps are as follows:

[0055] First, add 3 kg of tetrachloroethylene raw material into a stirring cup, and then add propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide into the stirring cup in sequence, and stir for 30 minutes to obtain a stabilizer solution.

[0056] The prepared stabilizer solution was added to the tetrachloroethylene raw material in the required amount to obtain isomeric tetrachloroethylene; the contents of propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide in the isomeric tetrachloroethylene in each group of experiments are shown in Table 2.

[0057] Table 1 Factor level table

[0058]

[0059] Table 2 Orthogonal experiment table

[0060]

[0061] In the above 9 groups of experiments, the initial quality indicators of isomerized tetrachloroethylene all met the following requirements: purity: 99.9710~99.9725%, pH value: 7~7.5; water content by mass was 15~25ppm, and chromaticity was 10.

[0062] After the isomerized perchloroethylene obtained from each group of experiments was sealed and placed for 60 days, its quality indicators were measured and compared with the initial quality indicators. Among them, purity, color, moisture content, pH value, and evaporation residue were measured according to the measurement method specified in HG / T3262-2014. In addition, the stabilizing effect of the stabilizer was determined by a copper sheet corrosion test. The specific method of the copper sheet corrosion test is as follows:

[0063] First, prepare two copper sheets with a size of 80mm×2.5mm×0.05mm and a purity of more than 99.9%. Wash the copper sheets with the test sample, hydrochloric acid, and water in turn, wipe them dry, bake them in an oven at 105±2℃ for 30min, cool them in a desiccator to room temperature, and weigh them for later use.

[0064] Measure 135mL of isomerized tetrachloroethylene sample and 5mL of water, and pour them into the same flask respectively; place a copper sheet in the extractor, and hang the other piece at the lower end of the condenser with a wire, and let cooling water flow into the condenser. Heat the sample to form a circulation, and adjust the electric heater so that the sample circulates once every 12-15 minutes. After 30 minutes of circulation, stop heating, take out the copper sheet, and weigh it after pickling, washing, and drying. Calculate the corrosion amount of the two copper sheets, and calculate the average corrosion amount. Determine the stabilizing effect of the stabilizer based on the corrosion amount of the copper sheet.

[0065] The test results of the isomeric grade tetrachloroethylene obtained from each group of experiments after being sealed and placed for 60 days are shown in Table 3.

[0066] Table 3 Quality index test results

[0067]

[0068] According to the test results of copper sheet corrosion in Table 3, the average effect (k1, k2 and k3) and range (R) of each level of each factor were calculated in the orthogonal experiment. The results are shown in Table 4.

[0069] Table 4 Calculation results of k value and R value

[0070]

[0071] According to the results in Table 4, it can be seen that the content of 2,6-di-tert-butyl-p-cresol has the greatest impact on the stability of isomeric tetrachloroethylene, and the corrosiveness is the lowest when the dosage of propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide is 0.0003wt%.

[0072] Based on the above results, it can be seen that the purity of the isomerized tetrachloroethylene prepared in this example changed little after being placed for 60 days, and the pH value, moisture content and chromaticity hardly changed, and the amount of copper sheet corrosion was also small, indicating that it has good stability.

[0073] Example 3

[0074] First, add 3 kg of tetrachloroethylene raw material into a stirring cup, and then add propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide into the stirring cup in sequence, and stir for 30 minutes to obtain a stabilizer solution.

[0075] The prepared stabilizer solution is added to the tetrachloroethylene raw material in a required amount to obtain isomeric tetrachloroethylene; the content of propylene oxide in the isomeric tetrachloroethylene is 0.0001wt%, the content of 2,6-di-tert-butyl-p-cresol is 0.0001wt%, and the content of butylene oxide is 0.0001wt%.

[0076] The test results of the quality indicators (purity, pH value, moisture content and color) of the tetrachloroethylene raw material, the tetrachloroethylene after adding the stabilizer (i.e., the isomeric grade tetrachloroethylene just prepared) and the isomeric grade tetrachloroethylene after being sealed and placed for 60 days are shown in Table 5. The test results of the copper sheet corrosion amount of the tetrachloroethylene after adding the stabilizer (i.e., the isomeric grade tetrachloroethylene just prepared) are shown in Table 6.

[0077] Table 5 Quality index test results

[0078]

[0079] Table 6 Copper sheet corrosion test results

[0080]

[0081] The pH value changes in Table 6 are the pH value changes of the corrosion solution used in the copper strip corrosion experiment before and after the experiment.

[0082] According to the test results in Table 5, it can be seen that the isomerized tetrachloroethylene prepared in this embodiment has high purity, low acidity, low moisture content, good chroma, and the various indicators are basically unchanged after being placed for 60 days; according to the test results in Table 6, it can be seen that the tetrachloroethylene copper sheet has low corrosiveness after adding the stabilizer, indicating that the stabilizer in this embodiment has a good stabilizing effect.

[0083] Example 4

[0084] First, add 3 kg of tetrachloroethylene raw material into a stirring cup, and then add propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide into the stirring cup in sequence, and stir for 30 minutes to obtain a stabilizer solution.

[0085] The prepared stabilizer solution is added to the tetrachloroethylene raw material in a required amount to obtain isomeric tetrachloroethylene; the content of propylene oxide in the isomeric tetrachloroethylene is 0.0002wt%, the content of 2,6-di-tert-butyl-p-cresol is 0.0002wt%, and the content of butylene oxide is 0.0002wt%.

[0086] The test results of the quality indicators (purity, pH value, moisture content and color) of the tetrachloroethylene raw material, the tetrachloroethylene after adding the stabilizer (i.e., the isomeric tetrachloroethylene just prepared) and the isomeric tetrachloroethylene after being sealed and placed for 60 days are shown in Table 7. The test results of the copper sheet corrosion amount of the tetrachloroethylene after adding the stabilizer (i.e., the isomeric tetrachloroethylene just prepared) are shown in Table 8.

[0087] Table 7 Quality index test results

[0088]

[0089] Table 8 Copper sheet corrosion test results

[0090]

[0091] According to the test results in Table 7, it can be seen that the isomerized tetrachloroethylene prepared in this embodiment has high purity, low acidity, low moisture content, good chroma, and the various indicators are basically unchanged after being placed for 60 days; according to the test results in Table 8, it can be seen that the corrosiveness of the tetrachloroethylene copper sheet after adding the stabilizer is small, indicating that the stabilizer in this embodiment has a good stabilizing effect.

[0092] Example 5

[0093] First, add 3 kg of tetrachloroethylene raw material into a stirring cup, and then add propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide into the stirring cup in sequence, and stir for 30 minutes to obtain a stabilizer solution.

[0094] The prepared stabilizer solution is added to the tetrachloroethylene raw material in a required amount to obtain isomeric tetrachloroethylene; the content of propylene oxide in the isomeric tetrachloroethylene is 0.0003wt%, the content of 2,6-di-tert-butyl-p-cresol is 0.0003wt%, and the content of butylene oxide is 0.0003wt%.

[0095] The test results of the quality indicators (purity, pH value, moisture content and color) of the tetrachloroethylene raw material, the tetrachloroethylene after adding the stabilizer (i.e., the isomeric grade tetrachloroethylene just prepared) and the isomeric grade tetrachloroethylene after being sealed and placed for 60 days are shown in Table 9. The test results of the copper sheet corrosion amount of the tetrachloroethylene after adding the stabilizer (i.e., the isomeric grade tetrachloroethylene just prepared) are shown in Table 10.

[0096] Table 9 Quality index test results

[0097]

[0098] Table 10 Copper sheet corrosion test results

[0099]

[0100] According to the test results in Table 9, it can be seen that the isomerized tetrachloroethylene prepared in this embodiment has high purity, low acidity, low moisture content, good chroma, and the various indicators are basically unchanged after being placed for 60 days; according to the test results in Table 10, it can be seen that the corrosion of the tetrachloroethylene copper sheet after adding the stabilizer is small, indicating that the stabilizer in this embodiment has a good stabilizing effect.

[0101] Comparative Example

[0102] Comparative experiment 1: other conditions were the same as those in Example 3, except that the addition of butylene oxide was omitted, and the addition amounts of propylene oxide and 2,6-di-tert-butyl-p-cresol were both 0.0003 wt %.

[0103] Comparative Experiment 2: Other conditions were the same as those in Example 3, except that the addition of 2,6-di-tert-butyl-p-cresol was omitted, and the addition amounts of propylene oxide and butylene oxide were both 0.0003 wt %.

[0104] Comparative experiment 3: other conditions were the same as those in Example 3, except that the addition of propylene oxide was omitted, and the addition amounts of 2,6-di-tert-butyl-p-cresol and butylene oxide were both 0.0003 wt %.

[0105] The quality index of tetrachloroethylene and the amount of copper sheet corrosion after adding the stabilizer were tested. The test method was the same as that in Example 2. The test results are shown in Table 11.

[0106] Table 11 Test results of perchloroethylene quality index and copper sheet corrosion after adding stabilizer

[0107]

[0108] The tetrachloroethylene with stabilizer added in Comparative Experiments 1 to 3 was sealed and placed for 60 days, and its quality indicators were tested. The results are shown in Tables 12 to 14.

[0109] Table 12 Test results of comparative experiment 1 after sealing for 60 days

[0110]

[0111] According to Table 12, after 60 days, the purity of tetrachloroethylene in Comparative Experiment 1 was less than 99.9%, the pH change rate was 21.8%, the moisture change rate was 182%, and the chromaticity increased. The above results show that the stability of the stabilizer in Comparative Experiment 1 cannot meet the performance requirements.

[0112] Table 13 Test results of comparative experiment 2 after sealing for 60 days

[0113]

[0114] According to the data in Table 13, after 60 days, the purity of vinyl chloride in Comparative Experiment 2 was less than 99.9%, the pH change rate was 31.8%, the moisture change rate was 250%, and the chromaticity increased. The above results show that the stability of the stabilizer in Comparative Experiment 2 cannot meet the performance requirements.

[0115] Table 14 Test results of comparative experiment 3 after sealing for 60 days

[0116]

[0117] According to the data in Table 13, after 60 days, the purity of tetrachloroethylene in Comparative Experiment 2 was less than 99.9%, the pH change rate was 18.23%, the moisture change rate was 157%, and the chromaticity increased. The above results show that the stability of the stabilizer in Comparative Experiment 3 cannot meet the performance requirements.

[0118] The results of the above embodiments show that the present invention adopts a compound of propylene oxide, 2,6-di-tert-butyl-p-cresol and butylene oxide as a stabilizer for isomerized tetrachloroethylene, and the obtained isomerized tetrachloroethylene has unchanged purity, substantially unchanged pH value, substantially unchanged moisture content and unchanged chromaticity within 60 days; and the stabilizer provided by the present invention has high purity and low moisture content, and has little effect on the life and activity of the catalyst; the isomerized tetrachloroethylene prepared by the present invention has the advantages of good chromaticity, low moisture content, high chlorine content, low vapor pressure, easy decomposition at high temperature, no hydrolysis, no corrosion, etc., and has high purity and low stabilizer content, and has almost no effect on the main catalyst in the petroleum isomerization production process, and can be used in petrochemical isomerization and catalytic reforming, and has broad application prospects.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An isomerization grade tetrachloroethylene, characterized in that: The invention is composed of tetrachloroethylene and a stabilizer; the stabilizer is composed of glycidol, 2,6-di-tert-butyl-p-cresol and butylene oxide; the content of glycidol in the isomeric tetrachloroethylene is 0.0001-0.0003wt%, the content of 2,6-di-tert-butyl-p-cresol is 0.0001-0.0003wt%, and the content of butylene oxide is 0.0001-0.0003wt%; the purity of the isomeric tetrachloroethylene is ≥99.97%, the water content is ≤25ppm, the pH value is 7-7.5, and the chromaticity is ≤10.

2. The isomerized tetrachloroethylene according to claim 1, characterized in that: The purity of the propylene oxide is ≥97%, and the moisture content is ≤0.1wt%; the purity of the 2,6-di-tert-butyl-p-cresol is ≥99.0%, and the moisture content is ≤0.1wt%; the purity of the butylene oxide is ≥99.0%, and the moisture content is ≤0.02wt%.

3. The method for preparing isomeric-grade tetrachloroethylene according to claim 1, characterized in that: The following steps are involved: The stabilizer and the tetrachloroethylene raw material are mixed to obtain the isomerized tetrachloroethylene; the purity of the tetrachloroethylene raw material is ≥99.97%, the water content is ≤25ppm, the pH value is 6.5-7.5, and the chromaticity is ≤10.

4. The preparation method according to claim 3, characterized in that: The mixing comprises: mixing the stabilizer with a part of the tetrachloroethylene raw material to obtain a stabilizer solution, and then mixing the stabilizer solution with the remaining part of the tetrachloroethylene raw material.

5. The preparation method according to claim 3 or 4, characterized in that: The method for preparing the tetrachloroethylene raw material comprises: sequentially distilling and removing acid from industrial-grade tetrachloroethylene to obtain the tetrachloroethylene raw material; the purity of the industrial-grade tetrachloroethylene is 99.90% to 99.93% or 99.93% to 99.95%.

6. The preparation method according to claim 5, characterized in that: The distillation is carried out in a distillation tower; the total number of sections of the packing layer in the distillation tower is 7, which are recorded as the first packing section to the seventh packing section from bottom to top; the distillation tower is provided with a first feed inlet, a second feed inlet, a side line outlet and a reflux inlet; the first feed inlet is arranged above the first packing section, the second feed inlet is arranged above the second packing section, the side line outlet is arranged below the seventh packing section, and the reflux inlet is arranged above the seventh packing section.

7. The preparation method according to claim 6, characterized in that: During the distillation, industrial-grade tetrachloroethylene with a purity of 99.90% to 99.93% is fed from the first feed port, and industrial-grade tetrachloroethylene with a purity of 99.93% to 99.95% is fed from the second feed port.

8. The preparation method according to claim 5, characterized in that: The distillation conditions include: the liquid level of the distillation tower is 60%~85%, the reflux ratio is 3~5:1, the tower top operating pressure is less than 10KPa, the tower top temperature is 119~125℃, and the tower bottom temperature is less than 128℃.

9. The preparation method according to claim 5, characterized in that: The acid removal reagent includes an adsorbent and a neutralizer; the adsorbent is sintered silica gel, and the neutralizer is anhydrous sodium carbonate; the mass ratio of the adsorbent to the neutralizer is 1:1-5.

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