Method for preparing hexafluoropropane

Abstract

The invention discloses a method for preparing hexafluoropropane, and relates to the technical field of new material preparation, and the method comprises the following steps: S1, preparing a solid catalyst: taking a porous material formed by mixing activated carbon and montmorillonite, sequentially carrying out acid washing and alkali washing, then activating in a mixed salt aqueous solution of chlorate and carbonate, drying, roasting, then mixing with modified vermiculite, and carrying out solid-liquid separation to obtain the solid catalyst; then adding a chromium trichloride solution, carrying out ultrasonic impregnation, and drying, so as to obtain a solid catalyst; s2, telomerization section: carrying out telomerization reaction on the raw materials vinylidene chloride and carbon tetrachloride under certain operation conditions; the hexachloropropane is obtained; s3, fluorination section: continuously adding hexachloropropane and anhydrous hydrogen fluoride into a fluorination reaction kettle, and carrying out fluorination reaction in the presence of a solid catalyst; the hexafluoropropane is obtained. The product prepared by the method is high in purity and high in yield.

Description

Technical Field

[0001] The invention relates to the technical field of new material preparation, and in particular to a method for preparing hexafluoropropane. Background Art

[0002] Hexafluoropropane (English name: HFC-236fa), a chemical substance, is suitable for filling portable fire extinguishers and is used for fire extinguishing in open and semi-open spaces. It is also suitable for use in total flooding fire extinguishing systems in manned locations.

[0003] In the existing production technology of hexafluoropropane, the catalyst is generally selected from trivalent chromium, tetravalent tin, or pentavalent antimony halides, that is, unsupported catalysts. There are some defects in the reaction, such as: large catalyst loss during the reaction process and post-treatment process, and certain difficulties in catalyst recovery. Therefore, it is necessary to develop a new catalyst to improve the production efficiency of hexafluoropropane. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a method for producing hexafluoropropane.

[0005] The technical solution of the present invention is as follows:

[0006] A method for producing hexafluoropropane, comprising the following steps:

[0007] S1: Preparation of solid catalyst:

[0008] A porous material mixed with activated carbon and montmorillonite is sequentially acid-washed and alkali-washed, then activated in a mixed salt solution of chloride and carbonate, oxygen is introduced during activation, and then calcined, and then mixed with modified vermiculite to obtain a porous matrix, and then chromium trichloride solution is added for ultrasonic impregnation, and dried to obtain a solid catalyst;

[0009] S2: Telomerization stage: the raw materials vinylidene chloride and carbon tetrachloride are subjected to telomerization reaction under certain operating conditions to obtain hexachloropropane;

[0010] S3: Fluorination chemical section: Hexachloropropane and anhydrous hydrogen fluoride are continuously added into a fluorination reactor, and a fluorination reaction is carried out under the condition of a solid catalyst to obtain hexafluoropropane.

[0011] As a preferred embodiment of the present invention, in step S1, the mass addition ratio of activated carbon to montmorillonite is 1-3:2.

[0012] As a preferred embodiment of the present invention, in step S1, the chloride salt is sodium chloride or potassium chloride, and the carbonate salt is sodium carbonate or potassium carbonate.

[0013] As a preferred embodiment of the present invention, in step S1, the mass ratio of the chloride salt to the carbonate salt is 1:3-5.

[0014] As a preferred embodiment of the present invention, in step S1, the added amount of the modified vermiculite is 3-10 wt % of the porous material.

[0015] As a preferred embodiment of the present invention, in step S1, the modified vermiculite is a first vermiculite body treated at 300-400°C for 1-2h, a second vermiculite body treated at 400-500°C for 20-30min, and a third vermiculite body treated at 500-700°C for 20-40min.

[0016] As a preferred embodiment of the present invention, in step S1, the calcination temperature is 900-1000°C.

[0017] As a preferred embodiment of the present invention, in step S2, the raw materials of vinylidene chloride and carbon tetrachloride with a molar ratio of 1.5-10:1 are subjected to a polymerization reaction for 10-25 hours at a temperature of 100-180°C, a pressure of 0.1-1 MPa, a copper halide catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled by desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product.

[0018] As a preferred embodiment of the present invention, in step S3, the raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added to a fluorination reaction kettle at a molar ratio of 1:5-7, and the fluorination reaction is carried out under the condition of a solid catalyst, and the reaction temperature is 220-450°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by a falling film absorber to produce industrial hydrochloric acid with a concentration of 31%; the crude reaction product is subjected to water alkali washing, drying, distillation and other processes to finally obtain the product.

[0019] As a preferred embodiment of the present invention, the mass ratio of the solid catalyst to hexachloropropane is 1-5:100.

[0020] The beneficial effects of the present invention are as follows: a method for manufacturing hexafluoropropane of the present invention, by adopting a porous mixture of a specific structure, chromium trichloride is loaded, on the one hand, due to the rich pore structure of activated carbon, the layered structure after montmorillonite is dissolved in water, the impurities are removed after acid washing and alkali washing, and after roasting treatment, the vermiculite treated with different temperature sections has a pore structure with different accommodation spaces, so that a new adsorption space is further formed with the porous mixture, and the accommodation of chromium trichloride is further enhanced, and in the subsequent participation in the catalytic reaction process, the agglomeration of the catalytic substance is reduced, and it is easy to recover, greatly improving the reaction rate, and improving the product conversion rate. In addition, the present invention activates the porous material by using molten salt, and directly etches carbon on the carbon surface in combination with the oxygen introduced, thereby forming gas, such as carbon dioxide and carbon monoxide, that is, not only the etching effect of potassium ions in the molten salt, but also the etching of oxygen, and moreover, at the same time, the original part of potassium carbonate itself will decompose at this high temperature, and the part that does not have time to decompose will directly react with carbon, and its product will further etch carbon. At the same time, the gas produced by it will also overflow the pore formation. Therefore, it will etch the carbon layer together with potassium ions. This makes the surface of porous materials have more micropores and mesopores active sites. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0022] Example 1

[0023] A method for producing hexafluoropropane, comprising the following steps:

[0024] S1: Preparation of solid catalyst:

[0025] A porous material of activated carbon and montmorillonite mixed in a mass ratio of 3:2 is acid-washed and alkali-washed in sequence, and then activated in a mixed salt solution of potassium chloride and potassium carbonate in a mass ratio of 1:3, oxygen is introduced during activation, and the gas flow rate is 45 ml / min. It is roasted at 900°C for 100 minutes, and then modified vermiculite is mixed to obtain a porous matrix, and then a chromium chloride solution is added for ultrasonic impregnation, and then dried to obtain a solid catalyst;

[0026] The modified vermiculite is a mixture of a first vermiculite body treated at 300°C for 1 hour, a second vermiculite body treated at 400°C for 30 minutes, and a third vermiculite body treated at 500-700°C for 30 minutes; the addition amount of the modified vermiculite is 5wt% of the porous material.

[0027] S2: Polymerization section: The raw materials of vinylidene chloride and carbon tetrachloride in a molar ratio of 10:1 are subjected to a polymerization reaction for 25 hours at a temperature of 170°C, a pressure of 0.7 MPa, a copper halide catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled after desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product;

[0028] S3: Fluorination chemical section: The raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added to the fluorination reactor at a molar ratio of 1:7, and the fluorination reaction is carried out under the condition of solid catalyst at a reaction temperature of 400°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by the falling film absorber to produce 31% concentration of industrial hydrochloric acid; the crude reaction product is subjected to water alkali washing, drying, and distillation processes to finally obtain the product.

[0029] The mass ratio of the solid catalyst to hexachloropropane is 3:100.

[0030] Example 2

[0031] A method for producing hexafluoropropane, comprising the following steps:

[0032] S1: Preparation of solid catalyst:

[0033] A porous material mixed with activated carbon and montmorillonite in a mass ratio of 3:2 is taken, acid-washed and alkali-washed in sequence, and then activated in a mixed salt solution of potassium chloride and potassium carbonate in a mass ratio of 1:3, oxygen is introduced during activation, and the gas flow rate is 45 ml / min. It is roasted at 950°C for 100 minutes, and then modified vermiculite is mixed to obtain a porous matrix, and then a chromium chloride solution is added for ultrasonic impregnation, and then dried to obtain a solid catalyst;

[0034] The modified vermiculite is a mixture of a first vermiculite body treated at 350°C for 1.5 hours, a second vermiculite body treated at 450°C for 25 minutes, and a third vermiculite body treated at 600°C for 30 minutes; the added amount of the modified vermiculite is 3wt% of the porous material.

[0035] S2: Polymerization section: The raw materials of vinylidene chloride and carbon tetrachloride in a molar ratio of 8:1 are subjected to a polymerization reaction for 20 hours at a temperature of 170°C, a pressure of 0.5 MPa, a copper chloride catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled after desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product;

[0036] S3: Fluorination chemical section: The raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added into the fluorination reactor at a molar ratio of 2-7, and the fluorination reaction is carried out under the condition of solid catalyst at a reaction temperature of 450°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by the falling film absorber to produce 31% concentration of industrial hydrochloric acid; the crude reaction product is subjected to water alkali washing, drying, and distillation processes to finally obtain the product.

[0037] The mass ratio of the solid catalyst to hexachloropropane is 3:100.

[0038] Example 3

[0039] A method for producing hexafluoropropane, comprising the following steps:

[0040] S1: Preparation of solid catalyst:

[0041] A porous material mixed with activated carbon and montmorillonite in a mass ratio of 3:2 is acid-washed and alkali-washed in sequence, and then activated in a mixed salt solution of potassium chloride and potassium carbonate in a mass ratio of 1:4, oxygen is introduced during activation, and the gas flow rate is 45 ml / min. It is roasted at 950°C for 100 minutes, and then modified vermiculite is mixed to obtain a porous matrix, and then a chromium chloride solution is added for ultrasonic impregnation, and then dried to obtain a solid catalyst;

[0042] The modified vermiculite is a mixture of a first vermiculite body treated at 350°C for 1 hour, a second vermiculite body treated at 450°C for 25 minutes, and a third vermiculite body treated at 600°C for 30 minutes; the addition amount of the modified vermiculite is 4wt% of the porous material.

[0043] S2: Polymerization section: The raw materials of vinylidene chloride and carbon tetrachloride in a molar ratio of 9:1 are subjected to a polymerization reaction for 20 hours at a temperature of 170°C, a pressure of 0.5 MPa, a copper chloride catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled after desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product;

[0044] S3: Fluorination chemical section: The raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously fed into the fluorination reactor at a molar ratio of 3:7, and the fluorination reaction is carried out under the condition of solid catalyst at a reaction temperature of 450°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by the falling film absorber to produce industrial hydrochloric acid with a concentration of 31%; the crude reaction product is subjected to water alkali washing, drying, and distillation processes to finally obtain the product.

[0045] The mass ratio of the solid catalyst to hexachloropropane is 4:100.

[0046] Example 4

[0047] A method for producing hexafluoropropane, comprising the following steps:

[0048] S1: Preparation of solid catalyst:

[0049] A porous material mixed with activated carbon and montmorillonite in a mass ratio of 1:1 is acid-washed and alkali-washed in sequence, and then activated in a mixed salt solution of potassium chloride and potassium carbonate in a mass ratio of 1:5, oxygen is introduced during activation, and the gas flow rate is 45 ml / min. It is roasted at 950° C. for 100 min, and then modified vermiculite is mixed in to obtain a porous matrix, and then a chromium chloride solution is added for ultrasonic impregnation, and then dried to obtain a solid catalyst;

[0050] The modified vermiculite is a mixture of a first vermiculite body treated at 400°C for 2h, a second vermiculite body treated at 500°C for 20min, and a third vermiculite body treated at 700°C for 30min; the addition amount of the modified vermiculite is 4wt% of the porous material.

[0051] S2: Polymerization section: The raw materials of vinylidene chloride and carbon tetrachloride in a molar ratio of 7:1 are subjected to a polymerization reaction for 20 hours at a temperature of 180°C, a pressure of 0.8 MPa, a copper halide catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled after desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product;

[0052] S3: Fluorination chemical section: The raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added into the fluorination reactor at a molar ratio of 4:7, and the fluorination reaction is carried out under the condition of solid catalyst at a reaction temperature of 450°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by the falling film absorber to produce 31% concentration of industrial hydrochloric acid; the crude reaction product is subjected to water alkali washing, drying, and distillation processes to finally obtain the product.

[0053] The mass ratio of the solid catalyst to hexachloropropane is 3:100.

[0054] Example 5

[0055] A method for producing hexafluoropropane, comprising the following steps:

[0056] S1: Preparation of solid catalyst:

[0057] A porous material of activated carbon and montmorillonite mixed in a mass ratio of 3:2 is acid-washed and alkali-washed in sequence, and then activated in a mixed salt solution of potassium chloride and potassium carbonate in a mass ratio of 1:3, oxygen is introduced during activation, and the gas flow rate is 45 ml / min. It is roasted at 1000°C for 100 minutes, and then modified vermiculite is mixed to obtain a porous matrix, and then a chromium chloride solution is added for ultrasonic impregnation, and then dried to obtain a solid catalyst;

[0058] The modified vermiculite is a mixture of a first vermiculite body treated at 400°C for 1 hour, a second vermiculite body treated at 500°C for 30 minutes, and a third vermiculite body treated at 700°C for 20 minutes; the addition amount of the modified vermiculite is 5wt% of the porous material.

[0059] S2: Polymerization section: The raw materials of vinylidene chloride and carbon tetrachloride in a molar ratio of 9:1 are subjected to a polymerization reaction for 25 hours at a temperature of 180°C, a pressure of 1Mpa, a copper chloride catalyst, and acetonitrile as a solvent; the unreacted CCl4 and VDC are recycled after desolventizing, and the hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product;

[0060] S3: Fluorination chemical section: The raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added into the fluorination reactor at a molar ratio of 1:6, and the fluorination reaction is carried out under the condition of solid catalyst at a reaction temperature of 450°C; the main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by the falling film absorber to produce industrial hydrochloric acid with a concentration of 31%; the crude reaction product is subjected to water alkali washing, drying, distillation and other processes to finally obtain the product.

[0061] The mass ratio of the solid catalyst to hexachloropropane is 5:100.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that chromium chloride is directly used as a catalyst.

[0064] Comparative Example 2

[0065] The difference from Example 1 is that S1: preparing a solid catalyst:

[0066] Take activated carbon, wash it with acid and alkali in sequence, calcine it at 1000°C for 100 minutes, then add chromium chloride solution for ultrasonic impregnation, and dry it to obtain a solid catalyst;

[0067] Comparative Example 3

[0068] The difference from Example 1 is that S1: preparing a solid catalyst:

[0069] A porous material of activated carbon and montmorillonite mixed in a mass ratio of 3:2 was acid-washed and alkali-washed in sequence, calcined at 1000°C for 100 min, and then mixed with modified vermiculite to obtain a porous matrix, which was then ultrasonically impregnated with a chromium chloride solution and dried to obtain a solid catalyst.

[0070] Comparative Example 4

[0071] Different from Example 1, the vermiculite is not modified. Specifically, S1: Preparation of solid catalyst:

[0072] A porous material of a mixture of activated carbon and montmorillonite in a mass ratio of 3:2 is taken, acid-washed and alkali-washed in sequence, and then activated in a mixed saline solution of potassium chloride and potassium carbonate in a mass ratio of 1:3, oxygen is introduced while activating, and the gas flow rate is 45 ml / min. It is calcined at 1000°C for 100 min, and then mixed with vermiculite to obtain a porous matrix, and then a chromium trichloride solution is added for ultrasonic impregnation, and dried to obtain a solid catalyst.

[0073] The purity and yield of the products of the above examples and comparative examples were tested, and the test results are shown in Table 1.

[0074] Table 1 Performance test results of embodiments and comparative examples

[0075]

[0076]

[0077] As can be seen from the above table, the performance of the embodiment is better than that of the comparative example. The main reason may be that, as shown in Comparative Examples 1-3, the embodiment uses a porous mixture of a specific structure to load chromium trichloride. On the one hand, due to the rich pore structure of activated carbon, the layered structure after montmorillonite is dissolved in water, impurities are removed after acid washing and alkali washing, and after roasting treatment, the vermiculite treated with different temperature sections has a pore structure with different accommodation spaces, so that a new adsorption space is further formed with the porous mixture, and the accommodation of chromium trichloride is further enhanced, and in the subsequent participation in the catalytic reaction process, the agglomeration of the catalytic substance is reduced, and it is easy to recover, greatly improving the reaction rate, and improving the product conversion rate. In addition, the analysis of Comparative Example 4 shows that the embodiment activates the porous material by using molten salt, and the carbon surface is directly etched by combining the oxygen introduced, so as to form a gas, such as carbon dioxide, carbon monoxide, that is, not only the etching effect of potassium ions in the molten salt, but also the etching of oxygen, and moreover, at the same time, the original part K2CO3 itself will decompose at this high temperature, and the decomposition will not have time to react directly with carbon, and its product will further etch carbon. At the same time, the gas produced will overflow to form pores. Therefore, it will etch the carbon layer together with potassium ions. This will make the surface of the porous material have more microporous and mesoporous active sites, thereby increasing the catalyst load, thereby increasing the conversion rate of the product, reducing the generation of by-products, and improving the purity.

[0078] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for producing hexafluoropropane, characterized in that: The following steps are involved: S1: Preparation of solid catalyst: A porous material mixed with activated carbon and montmorillonite is sequentially acid-washed and alkali-washed, then activated in a mixed salt solution of chloride and carbonate, oxygen is introduced during activation, and then calcined, and then mixed with modified vermiculite to obtain a porous matrix, and then chromium trichloride solution is added for ultrasonic impregnation, and dried to obtain a solid catalyst; S2: Telomerization stage: the raw materials vinylidene chloride and carbon tetrachloride are subjected to telomerization reaction under certain operating conditions to obtain hexachloropropane; S3: Fluorination chemical section: Hexachloropropane and anhydrous hydrogen fluoride are continuously added into a fluorination reactor, and a fluorination reaction is carried out under the condition of a solid catalyst to obtain hexafluoropropane.

2. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the mass addition ratio of activated carbon to montmorillonite is 1-3:

2.

3. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the chloride salt is sodium chloride or potassium chloride, and the carbonate salt is sodium carbonate or potassium carbonate.

4. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the mass ratio of the chloride salt to the carbonate salt is 1:3-5.

5. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the added amount of the modified vermiculite is 3-10wt% of the porous material.

6. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the modified vermiculite is a mixture of a first vermiculite body treated at 300-400°C for 1-2h, a second vermiculite body treated at 400-500°C for 20-30min, and a third vermiculite body treated at 500-700°C for 20-40min.

7. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S1, the calcination temperature is 900-1000°C.

8. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S2, raw materials of vinylidene chloride and carbon tetrachloride with a molar ratio of 1.5-10:1 are subjected to a polymerization reaction for 10-25 hours at a temperature of 100-180° C., a pressure of 0.1-1 MPa, a copper halide catalyst, and acetonitrile as a solvent; unreacted CCl4 and VDC are recycled after desolventizing, and hexachloropropane in the reactants is purified by distillation and stored in a large tank as an intermediate product.

9. A method for producing hexafluoropropane according to claim 1, characterized in that: In step S3, raw materials hexachloropropane and anhydrous hydrogen fluoride are continuously added into a fluorination reaction kettle at a molar ratio of 1:5-7, and a fluorination reaction is carried out under the condition of a solid catalyst at a reaction temperature of 220-450° C. The main product of the reaction is hexafluoropropane, and the by-product is HCl, which is absorbed by a falling film absorber to produce industrial hydrochloric acid with a concentration of 31%; the crude reaction product is subjected to water alkali washing, drying, distillation and other processes to finally obtain the product.

10. The method for producing hexafluoropropane according to claim 1, characterized in that: The mass ratio of the solid catalyst to hexachloropropane is 1-5:100.

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