Method for preparing vinyl chloride by cracking 1, 2-dichloroethane

Abstract

The invention discloses a method for preparing vinyl chloride by cracking 1, 2-dichloroethane, which comprises the following steps: in a reactor, contacting and reacting 1, 2-dichloroethane with a catalyst to obtain vinyl chloride, the catalyst is prepared by the following steps: in an inert gas atmosphere, introducing methane, mixing boron nitride with methane, and carrying out heat treatment to obtain the catalyst, and the specific surface area of the catalyst is 50-1500m < 2 > / g. The boron nitride supported carbon catalyst with abundant pore structure and high specific surface area can be prepared by using the method, isopyknic impregnation is not needed, the preparation process is simple, carbon can be directly supported in the heat treatment process, the industrial production is easier, no by-product is generated, the whole preparation process conforms to the green and environment-friendly production concept, and the method is suitable for industrial production. And the material has wide application prospects in the related catalysis fields of catalyzing 1, 2-dichloroethane cracking to prepare vinyl chloride and the like or used as an adsorbent due to the characteristics of the material.

Description

Technical Field

[0001] The present application relates to a method for preparing vinyl chloride by cracking 1,2-dichloroethane, and belongs to the field of industrial catalysis. Background Art

[0002] Polyvinyl chloride has the characteristics of high corrosion resistance, wear resistance and low price, and is widely used in production and life. Vinyl chloride is an important bulk chemical used to synthesize polyvinyl chloride plastics. Regarding the production routes of vinyl chloride, there are currently mainly calcium carbide hydrochlorination method, ethylene method, etc. Among them, the cracking of 1,2-dichloroethane (EDC) to produce vinyl chloride is crucial to the development of the vinyl chloride industry. The traditional EDC high-temperature cracking used in industry to produce vinyl chloride has an optimal cracking temperature of 500-550°C. The resulting vinyl chloride yield is high but also increases by-products including unsaturated hydrocarbons and carbon deposits. Therefore, it is imperative to select a suitable catalyst to reduce energy consumption and reduce by-products while obtaining a higher vinyl chloride yield, and to replace the traditional high-temperature thermal cracking process with catalytic cracking. Boron nitride materials have the advantages of high temperature resistance, multiple adsorption sites, large specific surface area, and strong antioxidant capacity. They have obvious advantages in energy storage, water pollutant adsorption, sensors, and other applications.

[0003] Patent CN 116657176 A discloses a porous boron nitride-supported atomic-level dispersed precious metal catalyst, its preparation method and application. Boron nitride is used as a carrier material and mixed with a platinum metal salt solution to obtain a composite material of boron nitride supported platinum, which is used as a catalyst for electrolysis of water to produce hydrogen. Patent CN 114192180A discloses a preparation method and application of a modified boron nitride-supported nickel-based methane dry reforming catalyst. Active metal nickel is supported on a boron nitride carrier by an impregnation method to solve the problems of carbon deposition in methane dry reforming reactions. Patent CN 113713839 A discloses a boron nitride-supported metal ruthenium catalyst, its preparation method and application in the preparation of imines. The boron nitride-supported ruthenium catalyst is obtained by an equal volume impregnation method of adding a reducing agent to an aqueous dispersion containing a ruthenium source, boron nitride and a complexing agent. Summary of the invention

[0004] The purpose of this application is to provide a method for preparing a porous boron nitride supported carbon catalyst, which does not require the most commonly used equal volume impregnation method, has a simple process and is easier to industrialize, so as to solve the problems of high energy consumption, serious carbon deposition, and many by-products in the traditional high temperature cracking of 1,2-dichloroethane. The obtained catalyst has the advantages of heat resistance, large specific surface area, developed pore structure, and good adsorption performance, and can catalyze the dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride at below 300°C.

[0005] According to one aspect of the present application, a method for preparing vinyl chloride by cracking 1,2-dichloroethane is provided, wherein 1,2-dichloroethane is contacted with a catalyst in a reactor to react and obtain vinyl chloride;

[0006] The catalyst is obtained by the following steps:

[0007] The boron nitride precursor is placed in a vertical furnace, heated to a specified temperature under an inert atmosphere, and after methane is introduced for a period of time, the methane is turned off, and the temperature is continued to drop to room temperature under the inert atmosphere before being taken out to obtain the boron nitride-supported carbon catalyst.

[0008] Optionally, specifically:

[0009] In an inert gas atmosphere, methane is introduced, boron nitride and methane are mixed, and heat-treated to obtain the catalyst;

[0010] The catalyst has a high specific surface area and rich pore structure, with a specific surface area of ​​50 to 1500 m 2 / g.

[0011] The inert gas atmosphere includes a nitrogen atmosphere and an inert gas atmosphere;

[0012] The flow rate of the inert gas atmosphere is 50 to 500 mL / min.

[0013] Optionally, the flow rate of the inert gas atmosphere is any value of 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 300 mL / min, 400 mL / min, 500 mL / min or any range between the above two points.

[0014] The temperature of the heat treatment is 250-1300°C;

[0015] Optionally, the heat treatment temperature is 600-1000°C.

[0016] Optionally, the heat treatment temperature is 500-1100°C.

[0017] Optionally, the temperature of the heat treatment is independently selected from any value of 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C or any range of values ​​between the above two points.

[0018] The time for introducing methane is 1 to 60 minutes.

[0019] Optionally, the methane introduction time is independently selected from any value among 1 min, 5 min, 10 min, 15 min, 20 min, 30 min, 40 min, 50 min, 60 min or any range of values ​​between the above two points.

[0020] The heating rate of the heat treatment is 1-10°C / min.

[0021] Optionally, the heating rate of the heat treatment is selected from any value of 1°C / min, 2°C / min, 3°C / min, 5°C / min, 10°C / min or any range of values ​​between the above two points.

[0022] The boron nitride is selected from at least one of commercial hexagonal boron nitride and homemade boron nitride fiber.

[0023] The reaction temperature is 200-350°C

[0024] Optionally, the reaction temperature is independently selected from any value of 200°C, 230°C, 250°C, 280°C, 300°C, 350°C or any range between the above two points.

[0025] The beneficial effects of this application include:

[0026] The method of the present application can be used to prepare a boron nitride-supported carbon catalyst with rich pore structure and high specific surface area. There is no need for equal volume impregnation, the preparation process is simple, and the carbon can be directly loaded during the heat treatment process, making industrial production easier. No by-products are generated, and the entire preparation process conforms to the green and environmentally friendly production concept. The characteristics of the material itself have broad application prospects whether in related catalytic fields such as catalytic cracking of 1,2-dichloroethane to produce vinyl chloride or when used as an adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the BET diagram of the boron nitride-supported carbon catalyst obtained in Example 10 of the present application.

[0028] Figure 2 This is the BET diagram of the boron nitride-supported carbon catalyst obtained in Example 3 of the present application.

[0029] Figure 3 This is a graph showing the conversion rate of 1,2-dichloroethane for the boron nitride-supported carbon catalyst obtained in Example 2 of the present application. DETAILED DESCRIPTION

[0030] The present application is described in detail below in conjunction with embodiments, but the present application is not limited to the following embodiments.

[0031] The measuring instruments used in the embodiments of the present application are: the specific surface area of ​​the boron nitride-supported carbon catalyst is tested on the Quantachrome four-station physical adsorption Quadrasorb S; the performance evaluation of the reaction of 1,2-dichloroethane cracking to produce vinyl chloride is carried out on a continuous flow atmospheric pressure fixed bed reactor, and the reaction products are analyzed online by a gas chromatograph connected to the reaction device, using an Agilent 8890B gas chromatograph.

[0032] Example 1

[0033] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 800℃ at 2℃ / min. After passing methane for 30 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0034] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 300 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen is used to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 13% and 17%.

[0035] Example 2

[0036] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 600℃ at 5℃ / min. After passing methane for 20 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0037] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 300 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen brings 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 16% and 19%.

[0038] Example 3

[0039] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 800℃ at 5℃ / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0040] Figure 2 This is the BET diagram of the boron nitride supported carbon catalyst obtained in Example 3 of the present application. The specific surface area of ​​the obtained catalyst is 1331m2 / g.

[0041] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250°C at 5°C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Use nitrogen to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 30% and 34%.

[0042] Figure 3 This is a graph showing the conversion rate of 1,2-dichloroethane using the boron nitride supported carbon catalyst obtained in Example 2 of the present application. After 25 hours of reaction, the conversion rate was maintained at about 30%.

[0043] Example 4

[0044] Take 1g of the homemade boron nitride precursor, place it in a vertical furnace, and in a 200mL / min nitrogen atmosphere, increase the temperature from room temperature to 950°C at 10°C / min. After passing methane for 5 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0045] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 200 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen is used to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 3% and 5%.

[0046] Example 5

[0047] Take 1g of the homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 850°C at 5°C / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0048] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250°C at 5°C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Use nitrogen to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 27% and 30%.

[0049] Example 6

[0050] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 800℃ at 5℃ / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0051] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 270 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen brings 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is 35% to 40%.

[0052] Example 7

[0053] Take 1g of the homemade boron nitride precursor, place it in a vertical furnace, and in a 250mL / min nitrogen atmosphere, increase the temperature from room temperature to 700°C at 2°C / min. After passing methane for 20 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0054] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 300 ° C at 5 ° C / min, open the four-way valve equipped with a 1,2-dichloroethane bubbler, and use nitrogen to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 28% and 32%.

[0055] Example 8

[0056] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 200mL / min nitrogen atmosphere, increase the temperature from room temperature to 1000℃ at 8℃ / min. After passing methane for 5 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0057] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 220°C at 5°C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Use nitrogen to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 1% and 3%.

[0058] Example 9

[0059] Take 1g of homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 900℃ at 10℃ / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0060] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen is used to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 18% and 20%.

[0061] Example 10

[0062] Take 1g of the homemade boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 650°C at 5°C / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0063] Figure 1 This is the BET diagram of the boron nitride supported carbon catalyst obtained in Example 10 of the present application. The specific surface area of ​​the obtained catalyst is 953 m 2 / g.

[0064] Weigh 50 mg of boron nitride-supported carbon catalyst and load it into a reaction tube. Purge it under nitrogen atmosphere (50 mL / min, STP) for 15 min to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250°C at 5°C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Use nitrogen to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is between 20% and 23%.

[0065] Embodiment 11

[0066] Take 1g of commercial boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 650°C at 5°C / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0067] Weigh 50 mg of boron nitride-supported carbon catalyst and place it in a reaction tube. Purge for 15 min under a nitrogen atmosphere (50 mL / min, STP) to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen is used to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is 0%.

[0068] Embodiment 11

[0069] Take 1g of commercial boron nitride precursor and place it in a vertical furnace. In a 300mL / min nitrogen atmosphere, increase the temperature from room temperature to 650°C at 5°C / min. After passing methane for 10 minutes, turn it off and take it out when the nitrogen atmosphere drops to room temperature.

[0070] Weigh 50 mg of boron nitride-supported carbon catalyst and place it in a reaction tube. Purge for 15 min under a nitrogen atmosphere (50 mL / min, STP) to remove the air in the reaction tube and pipelines. Then, raise the temperature to 250 ° C at 5 ° C / min. Open the four-way valve equipped with a 1,2-dichloroethane bubbler. Nitrogen is used to bring 1,2-dichloroethane into the reactor in the form of bubbles for reaction. After 32 hours, the conversion rate of 1,2-dichloroethane is 0%.

[0071] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing vinyl chloride by cracking 1,2-dichloroethane, characterized in that: In a reactor, 1,2-dichloroethane is contacted with a catalyst to react to obtain vinyl chloride; The catalyst is obtained by the following steps: In an inert gas atmosphere, methane is introduced, boron nitride and methane are mixed, and heat-treated to obtain the catalyst; The specific surface area of ​​the catalyst is 50 to 1500 m 2 / g.

2. The method according to claim 1, characterized in that The inert gas atmosphere includes a nitrogen atmosphere and an inert gas atmosphere; The flow rate of the inert gas atmosphere is 50 to 500 mL / min.

3. The method according to claim 1, characterized in that The temperature of the heat treatment is 250-1300°C; Preferably, the heat treatment temperature is 600-1000°C.

4. The method according to claim 1, characterized in that The time for introducing methane is 1 to 60 minutes.

5. The method according to claim 1, characterized in that: The heating rate of the heat treatment is 1-10°C / min.

6. The method according to claim 1, characterized in that The boron nitride is selected from at least one of commercial hexagonal boron nitride and homemade boron nitride fiber.

7. The method according to claim 1, characterized in that The reaction temperature is 200-350°C.

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