阅读说明：本技术 生产环保级四氯乙烯的方法 (Method for producing environment-friendly grade tetrachloroethylene ) 是由 姚国锋 张仕君 张松 左祥群 张晓斌 张碧元 闫伟 梁尧 唐波 植利军 周志安 于 2019-10-23 设计创作，主要内容包括：本发明公开了一种生产环保级四氯乙烯的方法,包括以下步骤：步骤1、向工业四氯乙烯原料中加入适量碳酸钾溶液搅拌,然后静置分出上层的碳酸钾溶液；步骤2、在步骤1得到的四氯乙烯中加入适量纯化水进行洗涤,然后静置分出上层的水液；步骤3、将步骤2洗涤后的四氯乙烯中加入适量的固体碱性剂并搅拌,然后分出固体碳酸钾；步骤4、将步骤3处理后的四氟乙烯通过分子筛脱水；步骤5、将步骤4脱水后的四氟乙烯精馏后即得。本发明得到的四氯乙烯产品在2930nm处的红外光谱吸光度不大于0.34,在2960nm处的红外光谱吸光度不大于0.07,在3030nm处的红外光谱吸光度不大于0.00,得到了合格的环保级产品,解决了目前企业不能大规模生产环保级四氯乙烯的问题。(The invention discloses a method for producing environment-friendly grade tetrachloroethylene, which comprises the following steps: step 1, adding a proper amount of potassium carbonate solution into an industrial tetrachloroethylene raw material, stirring, and standing to separate out an upper potassium carbonate solution; step 2, adding a proper amount of purified water into tetrachloroethylene obtained in the step 1 for washing, and then standing to separate an upper-layer water solution; step 3, adding a proper amount of solid alkaline agent into the tetrachloroethylene washed in the step 2, stirring, and separating solid potassium carbonate; step 4, dehydrating the tetrafluoroethylene treated in the step 3 through a molecular sieve; and 5, rectifying the dehydrated tetrafluoroethylene obtained in the step 4 to obtain the tetrafluoroethylene modified polytetrafluoroethylene. According to the invention, the infrared spectrum absorbance of the tetrachloroethylene product at 2930nm is not more than 0.34, the infrared spectrum absorbance at 2960nm is not more than 0.07, and the infrared spectrum absorbance at 3030nm is not more than 0.00, so that a qualified environment-friendly product is obtained, and the problem that the environment-friendly tetrachloroethylene cannot be produced in a large scale by the existing enterprises is solved.)

1. A method of producing environmentally friendly grade tetrachloroethylene, comprising the steps of:

step 1, adding a proper amount of potassium carbonate solution into an industrial tetrachloroethylene raw material, stirring, and standing to separate out an upper potassium carbonate solution;

step 2, adding a proper amount of purified water into tetrachloroethylene obtained in the step 1 for washing, and then standing to separate an upper-layer water solution;

step 3, adding a proper amount of solid alkaline agent into the tetrachloroethylene washed in the step 2, stirring, and separating solid potassium carbonate;

step 4, dehydrating the tetrafluoroethylene treated in the step 3 through a molecular sieve;

and 5, rectifying the dehydrated tetrafluoroethylene obtained in the step 4 to obtain the tetrafluoroethylene modified polytetrafluoroethylene.

2. The method for producing environmentally friendly tetrachloroethylene as claimed in claim 1, wherein the potassium carbonate solution is prepared by mixing potassium carbonate and water in a mass ratio of 1 (3-7), and the volume ratio of the added potassium carbonate solution to industrial tetrachloroethylene is 1 (17-23).

3. The method for producing eco-grade tetrachloroethylene according to claim 2, wherein in step 1, the stirring time is 1-3 h.

4. The method of producing eco-grade tetrachloroethylene according to claim 1, wherein in step 2, pure water is added in an amount of 10 to 30% by volume of tetrachloroethylene, and the stirring washing time is 1 to 3 hours.

5. The method for producing eco-friendly tetrachloroethylene according to claim 4, wherein in step 2, the tetrachloroethylene is repeatedly washed with pure water 2 to 5 times.

6. The method for producing eco-friendly tetrachloroethylene according to claim 1, wherein in step 3, the solid alkaline agent is solid potassium carbonate, the amount of the solid potassium carbonate added is 0.1-0.5% by mass of tetrafluoroethylene, and the stirring time is 1-4 hours.

7. The method for producing environmentally friendly tetrachloroethylene according to any of claims 1 to 6, wherein in step 5, the dehydrated tetrachloroethylene is distilled in a distillation still and the tetrachloroethylene at 121 ℃ is collected to obtain tetrachloroethylene.

Technical Field

The invention relates to the technical field of tetrachloroethylene purification, and particularly relates to a method for producing environment-friendly tetrachloroethylene.

Background

The environmental-friendly grade tetrachloroethylene is a concept proposed in recent years and is sought after, the environmental-friendly grade tetrachloroethylene is mainly used for the field of environmental-friendly environmental monitoring, standard parameters of the environmental-friendly grade tetrachloroethylene are identified, in the technical field, the environmental-friendly grade tetrachloroethylene is mainly formulated by enterprises such as Tianjin proud fine chemical research institute, Tianjin Kemi European chemical reagent company and the like, wherein the requirement is that when the environmental-friendly grade tetrachloroethylene is detected by an infrared oil detector in an infrared mode, the absorbance of the infrared spectrum at 2930nm is not more than 0.34, the absorbance of the infrared spectrum at 2960nm is not more than 0.07, the absorbance of the infrared spectrum at 3030nm is not more than 0.00, and the environmental-friendly grade tetrachloroethylene can be called as the environmental-friendly grade tetrachloro.

Chinese patent CN107778130A discloses a purification method of tetrachloroethylene in environmental protection grade, which adopts the following general technical scheme: soaking industrial-grade tetrachloroethylene in a 13X molecular sieve, then passing through an injection activated carbon column, and then passing through a magnesium silicate column to obtain the tetrachloroethylene, removing impurities by adopting a solid physical adsorption mode, wherein when the obtained tetrachloroethylene is detected by an infrared oil detector, the tetrachloroethylene has no infrared absorption at 3030nm and 2960nm, and the infrared absorption at 2930nm is less than or equal to 0.2, so that the requirements of environment-friendly grade tetrachloroethylene are met. The absorbance of the original environment-friendly grade tetrachloroethylene produced by the applicant at three points of 2930nm, 2960nm and 3030nm is similar to the result measured by the patent CN107778130A, namely no infrared absorption exists at 3030nm and 2960nm, and the infrared absorption at 2930nm is less than 0.25.

However, in recent years, complaints of customers to products are greatly increased, the products do not meet the requirements of environmental-friendly tetrachloroethylene as return goods and reimbursement, and after the investigation of the applicant, the detection instrument used by the original customer is different from the detection instrument used by the applicant, the detection instrument with the highest acceptance on the market at present is the detection instrument provided by the innate fine chemical research institute (namely used by the customer), while the applicant uses the detection instrument provided by other enterprises, so that the customer does not accept the detection instrument, and in order to find out the reason of the product or the reason of the detection instrument, the detection instrument is obtained after the investigation and the conclusion of the applicant for a long time, for the detection of the infrared spectrum absorbance of tetrachloroethylene, different infrared oil detectors have different precision and accuracy, so that the detected infrared spectrum absorbance results have larger difference, and most of the detection instruments accepted by the customer are proud, the precision and the accuracy are higher, while the precision and the accuracy of the detection instrument originally used by the applicant are lower, therefore, contradictory results appear, and in order to verify the fact, when the applicant detects the original product by using the detecting instrument which is prohibitively beautiful, the values appear at 3030nm and 2960nm, and do not reach the standard, and the result is the same as the result fed back by the client, in order to carry out multi-party verification, the applicant also purchases the environmental-protection-grade tetrachloroethylene product of the patent applicant, when the product is detected by an prohibitively expensive detection instrument, the actual value of its absorbance in the infrared spectrum at 2930nm is between 0.34 and 0.35, the actual value of the absorbance in the infrared spectrum at 2960nm was 0.06 and the actual value of the absorbance in the infrared spectrum at 3030nm was 0.00, that is, the infrared spectrum absorbance of the product at 2930nm is not up to standard, thereby proving that the product has problems.

In order to produce qualified environmental-friendly grade tetrachloroethylene, the applicant has made many improvements on the existing process, however, due to the nature characteristics of tetrachloroethylene, the purification difficulty is high, and the purification and stabilization method of tetrachloroethylene (Zheng Xuan, Xipin, etc., Yuzhou university, Vol.15, 4 of 1998) in Chinese thesis outlines the existing purification method of tetrachloroethylene, wherein alkali washing, water washing, adsorption treatment and direct adsorption treatment are the most commonly used purification methods, but the tetrachloroethylene produced according to the existing purification method has a poor result in the infrared spectrum absorbance test, the conventional improvement means can not make the product reach the environmental-friendly grade requirement, and if the production cost input is increased, the tetrachloroethylene is subjected to purification treatment of different procedures for many times, although the qualified environmental-friendly product can be obtained, the production period is increased in multiples, the yield is low, the production cost is high, not only can enterprises realize large-scale production, but also the enterprises can not have profit spaces or the profit spaces are extremely small, so that the method can not realize industrial application and can only be used for small-scale special customization, and the domestic environment-friendly tetrachloroethylene product market shortage and the import quantity are large.

Disclosure of Invention

The invention aims to: in order to solve the problems, the method for producing the environment-friendly tetrachloroethylene comprises the steps of carrying out alkali washing by using a potassium carbonate solution, washing away impurities by using water, and finally rectifying to obtain a qualified environment-friendly tetrachloroethylene product by a treatment mode of adding a solid alkaline agent and molecular sieve for dehydration, so that the problem that the existing enterprises cannot produce the environment-friendly tetrachloroethylene on a large scale is solved.

The technical scheme adopted by the invention is as follows: a method of producing environmentally friendly tetrachloroethylene, comprising the steps of:

step 1, adding a proper amount of potassium carbonate solution into an industrial tetrachloroethylene raw material, stirring, and standing to separate out an upper potassium carbonate solution;

step 2, adding a proper amount of purified water into tetrachloroethylene obtained in the step 1 for washing, and then standing to separate an upper-layer water solution;

step 3, adding a proper amount of solid alkaline agent into the tetrachloroethylene washed in the step 2, stirring, and separating solid potassium carbonate;

step 4, dehydrating the tetrafluoroethylene treated in the step 3 through a molecular sieve;

and 5, rectifying the dehydrated tetrafluoroethylene obtained in the step 4 to obtain the tetrafluoroethylene modified polytetrafluoroethylene.

In the method for producing environmentally friendly grade tetrachloroethylene of the present invention, the use of potassium carbonate is necessary at present, i.e. when industrial tetrachloroethylene is subjected to alkaline washing, a potassium carbonate solution is required, and the reason why the present invention does not use other alkaline agents is that the inventor uses the alkaline agent such as KOH, NaOH and Na₂CO₃When alkaline agents are used, no matter what concentration of solution is adopted, alkali washing is carried out once or for many times, the finally prepared product can not reach the standard, the infrared spectrum absorbance at 2930nm is mainly not up to the standard, the measured value is always greater than 0.34, and when K is used₂CO₃After the solution is dissolved, the absorbance indexes of the produced tetrachloroethylene reach the standards, wherein the absorbance of the infrared spectrum at 2930nm is stabilized between 0.321 and 0.337, and under the condition of not increasing the production cost, an environment-friendly product is obtained, and at present, only K is used₂CO₃The inventors have not found a specific reason to guess about a stabilizer in industrial tetrachloroethylene, but it is certain that K is used₂CO₃And then, the problem that the environment-friendly grade tetrachloroethylene cannot be produced on a large scale is solved. Further, in step 1, dry K cannot be used directly₂CO₃Proved by experiments, the dried K₂CO₃The purification effect is poor, the tetrachloroethylene can not reach the environmental protection level standard, and K is used₂CO₃The solution form solves the problem of dry K₂CO₃The inapplicable problem is that the tetrachloroethylene is in the form of solution and impurities are introduced into tetrachloroethylene, so that the tetrachloroethylene is washed by pure water to remove the impurities, and the tetrachloroethylene after washing is directly dehydrated by a molecular sieve according to the conventional process, however, in the test, the tetrachloroethylene after direct dehydration by the molecular sieve is unstable, the decomposition amount of tetrachloroethylene is large, the dehydration efficiency is low, and the production requirement cannot be satisfied, and the reason is that the acidity of tetrachloroethylene after washing with alkali and water is reduced to about 5.0pH, and the tetrachloroethylene is easily decomposed in the acid environment, so that,before the molecular sieve is used for dehydration, the acidity of tetrachloroethylene needs to be adjusted firstly to keep the stability of tetrachloroethylene, and when the acidity is adjusted by alkali liquor traditionally, the tetrachloroethylene needs to be washed by pure water, which is obviously not suitable. The absorbance indexes of the tetrachloroethylene prepared by the method all meet the requirement of environmental protection level in three items, the existing difficulties are solved, and a successful path is provided for industrial large-scale application.

Further, in order to better implement the invention, the potassium carbonate solution is prepared by mixing potassium carbonate and water according to the mass ratio of 1 (3-7), and the volume ratio of the added potassium carbonate solution to industrial tetrachloroethylene is 1 (17-23). The ratio of the potassium carbonate to the water is preferably in a range of 1 (3-7), if the ratio is lower than the range, not only the alkali washing effect of the potassium carbonate solution cannot meet the requirement, but also excessive impurities are introduced due to excessive water to influence the stability of tetrachloroethylene, and if the ratio is higher than the range, the alkali washing effect of the potassium carbonate solution is reduced due to overhigh potassium carbonate content and overlarge pH value, and the technical requirement cannot be met; correspondingly, the ratio of the potassium carbonate solution to the industrial tetrachloroethylene is preferably controlled to be 1 (17-23), only within the range, the alkaline washing effect of the potassium carbonate solution can be fully exerted, if the range is exceeded, the alkaline washing effect is poor if too much or too little alkali washing effect is generated, and finally the product can not reach the standard due to incomplete alkaline washing.

Further, in order to allow the added potassium carbonate solution to be sufficiently alkali-washed, in step 1, the stirring time is 1 to 3 hours.

Further, in the step 2, the addition amount of pure water is 10 to 30% by volume of tetrachloroethylene, and the stirring and washing time is 1 to 3 hours.

Further, in order to enhance the pure water washing effect, in step 2, tetrachloroethylene is repeatedly washed with pure water 2 to 5 times. The more the number of times of cleaning, the better the washing effect, but generally after 3-4 times of cleaning, the improvement of the cleaning effect is not obvious, so 3-4 times of cleaning is recommended.

Further, in step 3, the solid alkaline agent is preferably solid potassium carbonate, although other solid alkaline agents may be selected, and in step 3, the alkaline agent is not limited, and for example, CaCO may be selected₃、Na₂CO₃、NaHCO₃After solid potassium carbonate is selected, the addition amount of the solid potassium carbonate is preferably 0.1-0.5% of the mass of tetrafluoroethylene, the addition amount is not excessive, and the stirring time is preferably 1-4 h.

Further, in order to obtain tetrachloroethylene by better rectification, in the step 5, the dehydrated tetrachloroethylene is introduced into a distillation kettle for distillation, and the tetrachloroethylene at the temperature of 120-.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that: according to the invention, through carrying out alkaline washing by using a potassium carbonate solution, then washing with water to remove impurities, and then carrying out dehydration treatment by adding a solid alkaline agent and a molecular sieve, the infrared spectrum absorbance of a tetrachloroethylene product obtained by final rectification at 2930nm is not more than 0.34, the infrared spectrum absorbance at 2960nm is not more than 0.07, and the infrared spectrum absorbance at 3030nm is not more than 0.00, a qualified environment-friendly product is obtained, the problem that an existing enterprise cannot produce environment-friendly grade tetrachloroethylene on a large scale is solved, and a successful path is provided for industrial large-scale application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a method for producing environment-friendly grade tetrachloroethylene, which comprises the following steps:

step 1, adding a proper amount of potassium carbonate solution into an industrial tetrachloroethylene raw material, stirring, and standing to separate out an upper potassium carbonate solution;

step 2, adding a proper amount of purified water into tetrachloroethylene obtained in the step 1 for washing, and then standing to separate an upper-layer water solution;

step 3, adding a proper amount of solid alkaline agent into the tetrachloroethylene washed in the step 2, stirring, and separating solid potassium carbonate;

step 4, dehydrating the tetrafluoroethylene treated in the step 3 through a molecular sieve;

and 5, rectifying the dehydrated tetrafluoroethylene obtained in the step 4 to obtain the tetrafluoroethylene modified polytetrafluoroethylene.

In the step 1, the potassium carbonate solution is prepared by mixing potassium carbonate and water according to a mass ratio of 1 (3-7), wherein the ratio can be specifically selected from 1:3, 1:4, 1:5, 1:7 and the like, the volume ratio of the added potassium carbonate solution to the industrial tetrachloroethylene is 1 (17-23), the ratio can be specifically 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23 and the like, and when the potassium carbonate solution is mixed with the industrial tetrachloroethylene, the stirring time is 1-3 hours.

Further, in the step 2, the amount of pure water added is 10 to 30% by volume of tetrachloroethylene, the stirring and washing time is 1 to 3 hours, the number of washing times can be appropriately added depending on the washing effect in washing with pure water, and when one washing effect is not satisfactory, the desired effect can be achieved by a plurality of washing. Correspondingly, in the step 3, the solid alkaline agent is preferably solid potassium carbonate, the addition amount of the solid potassium carbonate is 0.1-0.5 wt%, and the stirring time is 1-4 h. Further, in step 5, the dehydrated tetrachloroethylene is introduced into a distillation kettle for distillation, and the tetrachloroethylene at the temperature of 120-.

In order to better carry out the invention, specific examples are set forth below