Boron-doped nitrogen-carbon catalyst as well as preparation method and application thereof
By introducing boron heteroatoms on nitrogen carbon materials, boron doped nitrogen carbon catalysts are prepared, which solves the problems of mercury catalyst contamination and thermal cracking of carbon deposits in the existing vinyl chloride production process, and achieves the effect of efficient cracking of dichloroethane at lower temperatures.
Patent Information
- Application Number
- CN202311773491.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-20
- Publication Date
- 2025-06-20
AI Technical Summary
In the existing vinyl chloride production processes, especially the acetylene method and dichloroethane cracking process, there is a problem of environmental pollution caused by the use of a large amount of mercury catalysts. Thermal cracking technology will increase the conversion rate while generating a large amount of carbon deposits, increasing production costs.
By pyrolyzing the boron nitrogen carbon source, boron heteroatoms are introduced on the nitrogen carbon material, and a boron doped nitrogen carbon catalyst is prepared for the cracking reaction of dichloroethane, reducing the reaction temperature and increasing the conversion rate.
The catalyst can achieve high conversion and selectivity at lower temperatures, reduce production costs, and avoid environmental pollution of mercury catalysts.
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Figure CN120169401A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to a boron-doped nitrogen-carbon catalyst, a preparation method thereof and an application thereof, belonging to the field of catalysis. Background Art
[0002] Vinyl chloride is a monomer for synthesizing polyvinyl chloride. Polyvinyl chloride is the third largest synthetic polymer plastic in the world and is widely used in various industries. At present, the main industrial production methods of vinyl chloride are the ethylene method, the ethane oxychlorination method and the acetylene method. A large amount of mercury catalyst is used in the production of vinyl chloride by the acetylene method, causing serious environmental pollution. The ethylene method and the ethane oxychlorination method have gradually developed. In these two processes, the process of producing vinyl chloride by cracking dichloroethane is involved. At present in industry, the cracking of dichloroethane mainly uses thermal cracking technology. Increasing the reaction temperature can increase the conversion rate of dichloroethane, but at the same time, a large amount of carbon deposition will be generated. Catalytic cracking of dichloroethane can achieve a higher conversion rate at a lower temperature, effectively reducing production costs and becoming a research hotspot. Summary of the Invention
[0003] Metal-free carbon-based materials are an ideal catalyst for the cracking of dichloroethane to prepare vinyl chloride, and their chemical activity and performance can be regulated by heteroatom functionalization. In addition, it has been found that the doping of two elements can effectively enhance their performance. In particular, boron and nitrogen are adjacent to carbon in the periodic table and have similar atomic properties. The strong polarity of B-N can generate a unique electronic structure, thereby changing the catalytic performance. In the present application, boron heteroatoms are introduced onto the nitrogen-carbon material by pyrolyzing a boron-nitrogen-carbon source, realizing the improvement of catalytic performance.
[0004] The present application provides a preparation method and an application of a boron-doped nitrogen-carbon catalyst for the cracking of 1,2-dichloroethane to prepare vinyl chloride. The method has a simple process, and the activity of the catalyst in the reaction can be adjusted by adjusting the treatment temperature, and it has a broad application prospect in the field of catalysis.
[0005] In one aspect of the present application, a boron-doped nitrogen-carbon catalyst is provided. The boron-doped nitrogen-carbon catalyst is obtained by subjecting a mixture containing a carbon source, a nitrogen source and a boron source to a hydrothermal reaction and carbonization.
[0006] Optionally, the carbon source is selected from at least one of glucose, sucrose, cellulose, and starch;
[0007] The nitrogen source is selected from at least one of urea, melamine, ethylenediamine, lysine, glycine, serine, threonine, tyrosine, histidine, glutamic acid, and arginine;
[0008] The boron source is selected from at least one of boric acid, boron oxide, sodium borate, ammonium borate, and potassium borate.
[0009] Another aspect of the present application provides a method for preparing the above-mentioned boron-doped nitrogen-carbon catalyst, and the preparation method includes:
[0010] (1) Mix a carbon source, a nitrogen source, a boron source and water, and carry out a hydrothermal reaction to obtain a carbon composite material;
[0011] (2) Carbonize the carbon composite material obtained in step (1) to obtain the boron-doped nitrogen-carbon catalyst.
[0012] As a specific embodiment, the method for preparing the boron-doped nitrogen-carbon catalyst includes:
[0013] (1) Dissolve and mix evenly a carbon source, a nitrogen source and a boron source in water.
[0014] (2) Treat the mixture under hydrothermal conditions to obtain an initially carbonized composite carbon material.
[0015] (3) Carbonize the material to obtain the boron-doped nitrogen-carbon catalyst.
[0016] Optionally, the molar ratio of the carbon source to the nitrogen source is 0.2 to 20.
[0017] Optionally, the molar ratio of the carbon source to the nitrogen source is 0.3 to 5.
[0018] Optionally, the molar ratio of the carbon source to the nitrogen source is independently selected from any value of 0.2, 0.4, 0.5, 1, 1.5, 2, 5, 20 or any range value between any two of the above.
[0019] Optionally, the molar ratio of the boron source to the carbon source is 0.05 to 5;
[0020] Optionally, the molar ratio of the boron source to the carbon source is 0.2 to 4.
[0021] Optionally, the molar ratio of the boron source to the carbon source is independently selected from any value of 0.05, 0.5, 1, 2, 3, 4, 5 or any range value between any two of the above.
[0022] Optionally, the carbon source is a water-soluble compound selected from at least one of glucose, sucrose, cellulose, and starch;
[0023] The nitrogen source is a water-soluble compound selected from at least one of urea, melamine, ethylenediamine, lysine, glycine, serine, threonine, tyrosine, histidine, glutamic acid, and arginine;
[0024] The boron source is a water-soluble compound selected from at least one of boric acid, boron oxide, sodium borate, ammonium borate, and potassium borate.
[0025] Optionally, the temperature of the hydrothermal reaction is 140 to 200 °C;
[0026] The time of the hydrothermal reaction is 2 to 24 hours.
[0027] Optionally, the temperature of the hydrothermal reaction is independently selected from any value of 140 °C, 190 °C, 200 °C or any range value between any two of the above.
[0028] Optionally, the time of the hydrothermal reaction is independently selected from any value of 2 hours, 8 hours, 12 hours, 20 hours, 24 hours or any range value between any two of the above.
[0029] Optionally, the carbonization is carried out in an inert atmosphere.
[0030] The temperature of the carbonization is 500 to 1000 °C, and the time of the carbonization is 0.5 to 12 hours.
[0031] Optionally, the temperature of the carbonization is independently selected from any value of 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C or any range value between any two of the above.
[0032] Optionally, the time of the carbonization is independently selected from any value of 0.5 hours, 3 hours, 12 hours or any range value between any two of the above.
[0033] In another aspect of the present application, a method for cracking dichloroethane to produce vinyl chloride is provided, and the method includes: contacting dichloroethane with a catalyst to carry out a cracking reaction to obtain vinyl chloride;
[0034] The catalyst is the above-mentioned boron-doped nitrogen-carbon catalyst.
[0035] As a specific implementation manner, the method is specifically to introduce 1,2-dichloroethane into a fixed-bed reactor loaded with the catalyst in a bubbling manner, and the reaction temperature is 180 to 350 °C.
[0036] Optionally, the temperature of the cracking reaction is 180 to 350 °C, and the space velocity of the cracking reaction is 0.1 to 10 h -1 .
[0037] Optionally, the temperature of the cracking reaction is independently selected from any value of 180 °C, 230 °C, 250 °C, 280 °C, 350 °C or any range value between any two of the above.
[0038] Optionally, the space velocity of the cracking reaction is independently selected from 0.1 h -1 、1 h -1 、5 h -1 、10 h -1Any value therein or any range value between any two of the above points.
[0039] The beneficial effects that this application can produce include:
[0040] 1) The preparation method of the catalyst provided by this application is to treat the carbon, nitrogen, and boron sources by the hydrothermal method, and then carbonize the composite under an inert atmosphere. Compared with the existing pyrolysis technology, this catalyst can reduce the reaction temperature and has a high conversion rate and selectivity.
[0041] 2) The catalyst provided by this application is used in the reaction of cracking 1,2-dichloroethane to prepare vinyl chloride, and has good catalytic activity. The preparation method has a simple process, and the catalytic activity can be regulated by adjusting the carbonization temperature, and has broad application prospects in the catalytic field. Description of the Drawings
[0042] Figure 1 It is a graph of the conversion rate of 1,2-dichloroethane cracking obtained in Examples 1-6 and Comparative Examples 1-2 of this application. Detailed Embodiments
[0043] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.
[0044] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.
[0045] The measuring instrument used in the embodiments of this application is as follows: The gas after the reaction enters an on-line chromatograph for analysis. The chromatograph is Agilent 8890, equipped with a DB-624UI capillary column, and the outlet is connected to an FID detector to detect the contents of 1,2-dichloroethane and vinyl chloride in the product, and obtain the conversion rate of 1,2-dichloroethane cracking.
[0046] The conversion rate in the embodiments of this application is calculated as follows:
[0047]
[0048] Example 1
[0049] Dissolve 6 g of glucose monohydrate, 1.8178 g of urea, and 5.617 g of boric acid in 130 ml of deionized water, stir evenly, add it to a 200 ml hydrothermal reactor, fix the hydrothermal reactor in a rotary oven, with a rotation speed of 10 rpm / min, and carry out hydrothermal treatment at 200 °C for 12 h. Naturally cool to room temperature, wash with water and ethanol, centrifuge until the supernatant is colorless, and then place it in an oven at 80 °C for drying for 8 h to obtain a boron-doped carbon nitride precursor. Place the precursor in a tube furnace, and calcine it from room temperature to 500 °C for 3 h under a nitrogen atmosphere. Obtain a boron-doped nitrogen-carbon catalyst.
[0050] Application of boron-doped nitrogen-carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0051] Example 2
[0052] 6 g of sucrose, 1.8178 g of urea, and 5.617 g of boric acid were dissolved in 130 ml of deionized water, stirred evenly, added to a 200-ml hydrothermal autoclave, and the hydrothermal autoclave was fixed in a rotary oven with a rotation speed of 10 rpm / min and hydrothermally treated at 200 °C for 12 h. It was naturally cooled to room temperature, washed with water and ethanol, centrifuged until the supernatant was colorless, and then placed in an 80 °C oven and dried for 8 h to obtain a boron-doped carbon-nitrogen precursor. The precursor was placed in a tubular furnace and calcined at 600 °C for 3 h under a nitrogen atmosphere. A boron-doped nitrogen-carbon catalyst was obtained.
[0053] Application of boron-doped nitrogen-carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0054] Example 3
[0055] 6 g of starch, 1.8178 g of urea, and 5.617 g of boric acid were dissolved in 130 ml of deionized water, stirred evenly, added to a 200-ml hydrothermal autoclave, and the hydrothermal autoclave was fixed in a rotary oven with a rotation speed of 10 rpm / min and hydrothermally treated at 200 °C for 12 h. It was naturally cooled to room temperature, washed with water and ethanol, centrifuged until the supernatant was colorless, and then placed in an 80 °C oven and dried for 8 h to obtain a boron-doped carbon-nitrogen precursor. The precursor was placed in a tubular furnace and calcined at 700 °C for 3 h under a nitrogen atmosphere. A boron-doped nitrogen-carbon catalyst was obtained.
[0056] Application of boron-doped nitrogen-carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0057] Example 4
[0058] Dissolve 6 g of glucose monohydrate, 1.8178 g of melamine, and 5.617 g of boric acid in 130 ml of deionized water, stir evenly, add it to a 200 ml hydrothermal reactor, fix the hydrothermal reactor in a rotary oven, with a rotation speed of 10 rpm / min, and carry out hydrothermal treatment at 200 °C for 12 h. Naturally cool to room temperature, wash with water and ethanol, centrifuge until the supernatant is colorless, and then place it in an 80 °C oven to dry for 8 h to obtain a boron-doped carbon nitride precursor. Place the precursor in a tubular furnace, and under a nitrogen atmosphere, heat it from room temperature to 800 °C and calcine for 3 h. Obtain a boron-doped nitrogen-carbon catalyst.
[0059] Application of the boron-doped nitrogen-carbon catalyst: Feed 1,2-dichloroethane into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature is 250 °C and the space velocity is 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0060] Example 5
[0061] Dissolve 6 g of glucose monohydrate, 1.8178 g of urea, and 5.617 g of sodium borate in 130 ml of deionized water, stir evenly, add it to a 200 ml hydrothermal reactor, fix the hydrothermal reactor in a rotary oven, with a rotation speed of 10 rpm / min, and carry out hydrothermal treatment at 200 °C for 12 h. Naturally cool to room temperature, wash with water and ethanol, centrifuge until the supernatant is colorless, and then place it in an 80 °C oven to dry for 8 h to obtain a boron-doped carbon nitride precursor. Place the precursor in a tubular furnace, and under a nitrogen atmosphere, heat it from room temperature to 900 °C and calcine for 3 h. Obtain a boron-doped nitrogen-carbon catalyst.
[0062] Application of the boron-doped nitrogen-carbon catalyst: Feed 1,2-dichloroethane into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature is 250 °C and the space velocity is 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0063] Example 6
[0064] Dissolve 6 g of glucose monohydrate, 1.8178 g of urea, and 5.617 g of ammonium borate in 130 ml of deionized water, stir evenly, add it to a 200 ml hydrothermal reactor, fix the hydrothermal reactor in a rotary oven, with a rotation speed of 10 rpm / min, and carry out hydrothermal treatment at 200 °C for 12 h. Naturally cool to room temperature, wash with water and ethanol, centrifuge until the supernatant is colorless, and then place it in an 80 °C oven to dry for 8 h to obtain a boron-doped carbon nitride precursor. Place the precursor in a tubular furnace, and under a nitrogen atmosphere, heat it from room temperature to 1000 °C and calcine for 3 h. Obtain a boron-doped nitrogen-carbon catalyst.
[0065] Application of boron-doped nitrogen-carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0066] Example 7
[0067] 6 g of glucose monohydrate, 1.8178 g of urea, and 3.744 g of boric acid were dissolved in 130 ml of deionized water, stirred evenly, added to a 200 ml hydrothermal autoclave. The hydrothermal autoclave was fixed in a rotary oven with a rotation speed of 10 rpm / min and hydrothermally treated at 200 °C for 12 h. It was naturally cooled to room temperature, washed with water and ethanol, centrifuged until the supernatant was colorless, and then placed in an 80 °C oven for drying for 8 h to obtain a boron-doped carbon-nitrogen precursor. The precursor was placed in a tubular furnace and calcined at 1000 °C for 3 h in a nitrogen atmosphere to obtain a boron-doped nitrogen-carbon catalyst.
[0068] Application of boron-doped nitrogen-carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0069] Comparative Example 1
[0070] 6 g of glucose monohydrate was dissolved in 130 ml of deionized water, stirred evenly, added to a 200 ml hydrothermal autoclave. The hydrothermal autoclave was fixed in a rotary oven with a rotation speed of 10 rpm / min and hydrothermally treated at 200 °C for 12 h. It was naturally cooled to room temperature, washed with water and ethanol, centrifuged until the supernatant was colorless, and then placed in an 80 °C oven for drying for 8 h to obtain a carbon precursor. The precursor was placed in a tubular furnace and calcined at 1000 °C for 3 h in a nitrogen atmosphere to obtain a carbon catalyst.
[0071] Application of carbon catalyst: 1,2-dichloroethane was introduced into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature was 250 °C and the space velocity was 1 h -1 The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0072] Comparative Example 2
[0073] Dissolve 6 g of glucose monohydrate and 1.8178 g of urea in 130 ml of deionized water, stir evenly, add it to a 200 ml hydrothermal reactor, fix the hydrothermal reactor in a rotary oven, with a rotation speed of 10 rpm / min, and carry out hydrothermal treatment at 200 °C for 12 h. Naturally cool to room temperature, wash with water and ethanol, centrifuge until the supernatant is colorless, and then place it in an 80 °C oven to dry for 8 h to obtain a carbon-nitrogen precursor. Place the precursor in a tubular furnace and calcine it from room temperature to 1000 °C for 3 h in a nitrogen atmosphere. Obtain a nitrogen-carbon catalyst.
[0074] Application of the nitrogen-carbon catalyst: Feed 1,2-dichloroethane into the reactor filled with the catalyst prepared in this example in a bubbling manner. The reactor temperature is 250 °C and the space velocity is 1 h -1 . The cracking conversion rate of 1,2-dichloroethane is shown in Figure 1 .
[0075] It can be seen from Figure 1 that pure carbon does not have catalytic activity for the cracking of 1,2-dichloroethane. The addition of nitrogen can act as an effective active site to catalyze the occurrence of the 1,2-dichloroethane cracking reaction. The addition of boron further enhances the activity of the catalyst, showing a volcano-type trend with the increase of the calcination temperature. The formation of B-N bonds and the appropriate pyridine nitrogen content at 700 °C result in the highest activity at 700 °C.
[0076] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the disclosed technical content above is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.
Claims
1. A boron-doped nitrogen-carbon catalyst, characterized in that, The boron-doped nitrogen-carbon catalyst is obtained by subjecting a mixture containing a carbon source, a nitrogen source, and a boron source to hydrothermal reaction and carbonization.
2. The boron-doped nitrogen-carbon catalyst according to claim 1, characterized in that, The carbon source is selected from at least one of glucose, sucrose, cellulose, and starch; The nitrogen source is selected from at least one of urea, melamine, ethylenediamine, lysine, glycine, serine, threonine, tyrosine, histidine, glutamic acid, and arginine; The boron source is selected from at least one of boric acid, boron oxide, sodium borate, ammonium borate, and potassium borate.
3. A method for preparing the boron-doped nitrogen-carbon catalyst according to any one of claims 1 to 2, characterized in that, The preparation method includes: (1) Mixing the carbon source, nitrogen source, boron source, and water, and subjecting them to hydrothermal reaction to obtain a carbon composite material; (2) Carbonizing the carbon composite material obtained in step (1) to obtain the boron-doped nitrogen-carbon catalyst.
4. The preparation method according to claim 3, characterized in that, The molar ratio of the carbon source to the nitrogen source is 0.2 to 20; Preferably, the molar ratio of the carbon source to the nitrogen source is 0.3 to 5.
5. The preparation method according to claim 3, characterized in that, The molar ratio of the boron source to the carbon source is 0.05 to 5; Preferably, the molar ratio of the boron source to the carbon source is 0.2 to 4.
6. The preparation method according to claim 3, characterized in that, The carbon source is selected from at least one of glucose, sucrose, cellulose, and starch; The nitrogen source is selected from at least one of urea, melamine, ethylenediamine, lysine, glycine, serine, threonine, tyrosine, histidine, glutamic acid, and arginine; The boron source is selected from at least one of boric acid, boron oxide, sodium borate, ammonium borate, and potassium borate.
7. The preparation method according to claim 3, characterized in that, The temperature of the hydrothermal reaction is 140 to 200 °C; The time of the hydrothermal reaction is 2 to 24 hours.
8. The preparation method according to claim 3, characterized in that, The carbonization is carried out in an inert atmosphere. The temperature of the carbonization is 500 to 1000 °C, and the time of the carbonization is 0.5 to 12 hours.
9. A method for cracking dichloroethane to produce vinyl chloride, characterized in that, The method includes: contacting dichloroethane with the catalyst to carry out a cracking reaction to obtain vinyl chloride; The catalyst is the boron-doped nitrogen-carbon catalyst according to any one of claims 1 to 2.
10. The method according to claim 10, characterized in that, The temperature of the cracking reaction is 180 to 350 °C, and the space velocity of the cracking reaction is 0.1 to 10 h -1 .