A biochar-coupled copper catalyst and its preparation method and application
A biochar-coupled copper catalyst addresses the high cost and stability issues of mercury-free and precious metal catalysts by using a visible light-assisted method, providing a stable and efficient acetylene hydrochlorination process.
Patent Information
- Application Number
- CN202211472693.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-23
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2042-11-23
AI Technical Summary
The use of mercury-free and precious metal catalysts in the acetylene hydrochlorination process is hindered by high costs and component loss, posing challenges for industrial applications.
A biochar-coupled copper catalyst is prepared using a visible light-assisted method, where copper is dispersed on biochar with a rich flaky microporous structure, enhancing stability and catalytic activity.
The catalyst achieves stable and efficient acetylene hydrochlorination with reduced agglomeration, offering a cost-effective alternative to traditional catalysts.
Smart Images
Figure CN115770572B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of composite catalyst preparation, and specifically relates to a biochar-coupled copper catalyst and a preparation method and application thereof. Background Art
[0002] Polyvinyl chloride (PVC) is the most widely used thermoplastic resin, involving pipes and fittings, doors, windows, packaging boards and other products. PVC is obtained by the polymerization of vinyl chloride monomer (VCM). The calcium carbide method (i.e., acetylene hydrochlorination) is the primary preparation method, but the calcium carbide method requires the use of mercuric chloride catalyst (HgCl2), which is a highly toxic catalyst that can cause irreversible harm to human health and the ecological environment. Therefore, researchers are actively working on exploring mercury-free catalysts.
[0003] Studies have shown that precious metals, including Au, Bi, Pt and Pd, have good catalytic activity for acetylene hydrochlorination. However, there is an important issue that cannot be ignored when using precious metals, which is the high cost of using these catalysts to run the entire catalytic life cycle, which puts pressure on the operation of the entire industrial system. In addition, the use of these precious metal catalysts is prone to loss during the process of acetylene hydrochlorination. In order to save costs, the study of non-precious metal catalysts in acetylene hydrochlorination has extremely important practical significance. Summary of the invention
[0004] The object of the present invention is to provide a biochar-coupled copper catalyst and a preparation method and application thereof. The obtained catalyst is a non-mercury and non-precious metal acetylene hydrochlorination catalyst with good dispersibility, stability and catalytic activity. The technical scheme of the present invention is as follows:
[0005] A method for preparing a biochar-coupled copper catalyst comprises the following steps:
[0006] 1) Dissolve copper salt in deionized water as a copper solution, immerse the biochar in the copper solution, and disperse it by ultrasound;
[0007] 2) transferring the preparation of step 1) into a quartz photoreactor, introducing nitrogen to drive out dissolved oxygen, controlling the room temperature in a constant temperature water bath, irradiating with visible light under magnetic stirring, and slowly injecting a reducing agent solution to promote metal ion reduction and crystallization;
[0008] 3) After the reaction, centrifugal separation was performed and the product was dried in a vacuum drying oven overnight to obtain a biochar-coupled copper catalyst.
[0009] Furthermore, the copper salt in step 1) is copper chloride, copper nitrate, copper sulfate, copper phosphate, copper acetate or copper ammonium chloride, and the concentration of the copper solution is 12-13 mg / ml.
[0010] Furthermore, the biochar is in powder form with a particle size of 30-540 mesh and a specific surface area of 200-2000 m 2 / g, pore volume 0.15~1.1cm 3 / g, and micropores with a pore size less than 2 nm account for more than 50%.
[0011] Furthermore, the mass ratio of copper salt to biochar is 1:10-100.
[0012] Furthermore, the reducing agent in step 2) is hydrazine, sodium borohydride, potassium borohydride, ethanol, ammonia or sodium sulfite, the concentration of the reducing agent solution is 0.2-6 mol / L, and the amount of the reducing agent solution added does not exceed 10% of the total volume of the reaction solution.
[0013] Furthermore, the adding speed of the reducing agent solution is 13-16 gtt / min.
[0014] Furthermore, the rotation speed of the centrifugal separation in step 3) is 4000-10000 r / min, the time is controlled within 30 min, and the moisture content of the product after overnight drying must be less than 10%.
[0015] A biochar-coupled copper catalyst prepared by the preparation method as described in any one of claims 1 to 7.
[0016] The invention discloses an application of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination. The specific operation is as follows: a biochar-coupled copper catalyst is filled in a fixed bed reactor, HCl and C2H2 gases are introduced, and vinyl chloride is prepared by reaction at a temperature of 100-160°C and a pressure of 0.1-0.15 MPa.
[0017] Furthermore, the molar ratio of HCl to C2H2 is 1:0.95~1.2, and the volumetric space velocity of acetylene is 30~720 h -1 .
[0018] The beneficial effects achieved by the present invention are:
[0019] 1) The present invention uses biochar with rich flaky microporous structure as a carrier, which not only improves the dispersion and anchoring of copper atoms, but also has good stability to effectively reduce component loss, thereby improving the catalytic activity of acetylene hydrochlorination;
[0020] 2) The visible light in-situ metal deposition method described in the present invention uses visible light bands to complete the loading reaction at room temperature, effectively avoiding the agglomeration problem caused by the intensified crystallization reaction caused by heating, making the copper-based catalyst evenly distributed and reducing agglomeration;
[0021] 3) The present invention can provide a new method for developing new functional materials of mercury-free and non-precious metal catalysts in the acetylene hydrochlorination industry. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 TEM image and surface scanning energy spectrum of the biochar-coupled copper catalyst sample prepared in Example 1.
[0023] Figure 2 The activity curves of catalyst samples 1, 2, 3 and 4 prepared in the examples are shown in FIG.
[0024] Figure 3 This is the SEM image of the carrier biochar sample in the comparative example. DETAILED DESCRIPTION
[0025] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.
[0026] Example 1 Preparation method and application of biochar-coupled copper catalyst for acetylene hydrochlorination reaction, the steps are as follows:
[0027] The biochar used in this example was prepared by molten salt method and was in powder form with a particle size of 150 mesh and a specific surface area of 1332 m 2 g, pore volume 0.8 cm 3 / g, and the proportion of micropores with a pore size less than 2nm is 60%.
[0028] 1) Dissolve 250 mg of copper chloride in deionized water to a concentration of 0.19 mol / L. Then, immerse the microporous biochar in the copper solution at a mass ratio of copper salt to biochar of 1:20 and disperse it by ultrasonication for 5 minutes.
[0029] 2) The preparation in step 1) was transferred to a quartz photoreactor, nitrogen was introduced for 30 minutes to drive out dissolved oxygen, and a constant temperature water bath was connected to control the room temperature. Under magnetic stirring, visible light with a wavelength of 420-630 nm was irradiated, and 5 mL of 1.2 mol / L NaBH4 reducing agent solution was slowly injected at 15 gtt / min to promote in-situ reduction and crystallization of the metal;
[0030] 3) After reacting for 1 hour, the mixture was separated by centrifugation at 8000 r / min for 5 minutes, washed with deionized water and acetone, and dried in a vacuum drying oven at 65°C overnight. The moisture content of the product was 5%, and the biochar-coupled copper catalyst was obtained, which was recorded as sample No. 1.
[0031] like Figure 1 As shown, the TEM image and surface scanning energy spectrum of catalyst sample No. 1 prepared in Example 1 show that copper atoms have been successfully and evenly loaded on the biochar carrier.
[0032] Catalyst sample No. 1 prepared in Example 1 was used for acetylene hydrochlorination reaction, and the specific process was as follows:
[0033] 1) A fixed bed microreactor was used for evaluation. The inner diameter of the fixed bed cavity was 1.5 cm, the length of the constant temperature heating zone was 20 cm, and the temperature was controlled by an electric furnace. The biochar material was loaded with 2.88 g. The atmosphere was activated for 0.5 h before the reaction. After activation, HCl and C2H2 gases were introduced to react. The gas chromatograph equipped with a FID detector was used for analysis, and the sampling frequency was 1 h each time.
[0034] 2) Control the molar ratio of HCl and C2H2 in the reaction gas to 1.2:1, and the volumetric space velocity in terms of acetylene to 50 h -1 The reaction temperature was 160 °C and the pressure was 0.1 MPa. The acetylene hydrochlorination experiment was carried out. The acetylene conversion rate was 27.3% and remained stable after 12 h of operation. Figure 2 .
[0035] Example 2 Preparation method and application of biochar-coupled copper catalyst for acetylene hydrochlorination reaction, the steps are as follows:
[0036] The biochar used in this example was prepared by molten salt method and was in powder form with a particle size of 150 mesh and a specific surface area of 1332 m 2 g, pore volume 0.8 cm 3 / g, and the proportion of micropores with a pore size less than 2nm is 60%.
[0037] 1) Dissolve 250 mg of copper chloride in deionized water to a concentration of 0.19 mol / L, then immerse the microporous biochar in the copper solution at a mass ratio of copper salt to biochar of 1:10, and disperse it by ultrasonication for 5 minutes;
[0038] 2) The preparation in step 1) was transferred to a quartz photoreactor, nitrogen was introduced for 30 minutes to drive out dissolved oxygen, and a constant temperature water bath was connected to control the room temperature. The mixture was irradiated with visible light in the wavelength range of 420-630 nm under magnetic stirring, and 5 mL of 2.2 mol / L NaBH4 reducing agent solution was slowly injected at 15 gtt / min to promote the in-situ metal deposition reaction;
[0039] 3) After reacting for 1 hour, the mixture was separated by centrifugation at a speed of 8000 r / min for 5 minutes, washed with deionized water and acetone, and dried in a vacuum drying oven at 65°C overnight. The moisture content of the product was 6%, and the biochar-coupled non-precious metal copper catalyst was obtained, which was recorded as sample No. 2.
[0040] Catalyst sample No. 2 prepared in Example 2 was used for acetylene hydrochlorination reaction. The specific process was the same as that in Example 1. The molar ratio of HCl / C2H2 in the reaction gas was controlled to be 1.2:1, and the volumetric space velocity was 50 h / min based on acetylene. -1The reaction temperature was 160 °C and the pressure was 0.1 MPa. The acetylene hydrochlorination experiment was carried out. The acetylene conversion rate was 43.2% and remained stable after 12 h of operation. Figure 2 .
[0041] Example 3 Preparation method and application of biochar-coupled non-precious metal copper catalyst for acetylene hydrochlorination reaction, the steps are as follows:
[0042] The biochar used in this example was prepared by molten salt method and was in powder form with a particle size of 150 mesh and a specific surface area of 1332 m 2 g, pore volume 0.8 cm 3 / g, and the proportion of micropores with a pore size less than 2nm is 60%.
[0043] 1) Dissolve 250 mg of copper chloride in deionized water to a concentration of 0.19 mol / L, then immerse the microporous biochar in the copper solution at a mass ratio of copper salt to biochar of 1:6.7, and disperse it by ultrasonication for 5 minutes;
[0044] 2) The material prepared in step 1) was transferred to a quartz photoreactor, nitrogen was introduced for 30 minutes to drive out dissolved oxygen, and a constant temperature water bath was connected to control the room temperature. The material was irradiated with visible light in the wavelength range of 420-630 nm under magnetic stirring, and 5 mL of 3.7 mol / L NaBH4 reducing agent solution was slowly injected at 15 gtt / min to promote the in-situ metal deposition reaction;
[0045] 3) After reacting for 1 hour, the mixture was separated by centrifugation at a speed of 8000 r / min for 5 minutes, washed with deionized water and acetone, and the obtained product was dried in a vacuum drying oven at 65°C overnight. The moisture content of the product was 8.4%, and the biochar-coupled non-precious metal copper catalyst was obtained.
[0046] Catalyst sample No. 3 prepared in Example 3 was used for acetylene hydrochlorination reaction. The specific process was the same as that in Example 1. The molar ratio of HCl / C2H2 in the reaction gas was controlled to be 1.2:1, and the volumetric space velocity was 50 h / min based on acetylene. -1 The reaction temperature was 160 °C and the pressure was 0.1 MPa. The acetylene hydrochlorination experiment was carried out. The acetylene conversion rate was 52.9% and remained stable after 12 h of operation. Figure 2 .
[0047] Comparative Example 1 Preparation method and application of biochar rich in microporous structure, the steps are as follows:
[0048] 1) The wood waste biomass is crushed, sieved, soaked, ultrasonicated, centrifuged, dehydrated, and dried. The biomass dried at 110° C. for 5 hours is pulverized by a grinder and finely sieved with a 150-mesh sieve to obtain a particle size;
[0049] 2) The obtained biomass powder is mixed with a pre-prepared mixed salt with a mass ratio of KCl: K2SO4: Na2SO4 = 32.5: 30.4: 37.1 in a mass ratio of 1:2, and an appropriate amount of water is added dropwise to mix well. In an inert gas nitrogen atmosphere, the heating rate is adjusted to 14°C / min, the reaction temperature is 700°C, and the constant temperature time is 60 minutes to carry out a carbonization reaction;
[0050] 3) The obtained biochar was pickled with 0.2 mol / L dilute hydrochloric acid at 65 °C and washed with ultrapure water until it was nearly neutral, thereby obtaining a biochar material with a high microporous structure and a high pore volume characteristic, which was recorded as sample No. 4.
[0051] The SEM image of the carrier biochar sample prepared in Comparative Example 1 shows that the biochar prepared by the method of the present invention has a sheet-like self-assembled three-dimensional pore structure. Figure 3 The BET test showed that the pore structure of the sample was mainly composed of micropores of 1.8 nm, with a total pore volume of 0.80 cm 3 / g, of which the micropore volume reaches 0.70 cm 3 / g (accounting for 87.5%), with a specific surface area of 1533 m 2 / g.
[0052] The carrier biochar sample prepared in Comparative Example 1 was used for acetylene hydrochlorination reaction. The specific process was the same as that in Example 1. The molar ratio of HCl / C2H2 in the reaction gas was controlled to be 1.2:1, and the volumetric space velocity was 50 h / min based on acetylene. -1 The reaction temperature was 160 °C and the pressure was 0.1 MPa. The acetylene hydrochlorination experiment was carried out. The acetylene conversion rate was 25.7% and remained stable after 12 h of operation. Figure 2 .
[0053] The catalyst with a mass ratio of copper salt to biochar of 1:6.7 has a better acetylene conversion rate than the other three types of catalysts. It can be inferred that the biochar material has different degrees of interaction with the active metal, which in turn affects its catalytic performance.
[0054] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.
Claims
1. An application of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination, characterized in that: The specific operation is as follows: fill the fixed bed reactor with biochar coupled copper catalyst, introduce HCl and C2H2 gas, and react at a temperature of 100-160 °C and a pressure of 0.1-0.15 MPa to produce vinyl chloride; The preparation method of biochar coupled copper catalyst comprises the following steps: 1) Dissolve copper salt in deionized water as a copper solution, immerse the biochar in the copper solution, and disperse it by ultrasound; 2) transferring the preparation of step 1) into a quartz photoreactor, introducing nitrogen to drive out dissolved oxygen, controlling the room temperature in a constant temperature water bath, irradiating with visible light under magnetic stirring, and slowly injecting a reducing agent solution to promote metal ion reduction and crystallization; 3) After the reaction, centrifugal separation is performed and the product is dried in a vacuum drying oven overnight to obtain a biochar-coupled copper catalyst; The reducing agent in step 2) is hydrazine, sodium borohydride, potassium borohydride, ethanol, ammonia or sodium sulfite, the concentration of the reducing agent solution is 0.2-6 mol / L, and the amount of the reducing agent solution added does not exceed 10% of the total volume of the reaction solution; The reducing agent solution was added at a rate of 13-16 gtt / min.
2. The use of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination as claimed in claim 1, characterized in that: The copper salt described in step 1) is copper chloride, copper nitrate, copper sulfate, copper phosphate, copper acetate or copper ammonium chloride, and the concentration of the copper solution is 0.15-0.20 mol / L.
3. The use of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination as claimed in claim 2, characterized in that: Biochar is in powder form with a particle size of 30-540 mesh and a specific surface area of 200-2000 m 2 / g, pore volume 0.15~1.1cm 3 / g, and micropores with a pore size less than 2 nm account for more than 50%.
4. The use of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination as claimed in claim 3, characterized in that: The mass ratio of copper salt to biochar is 1:10-100.
5. The use of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination as claimed in claim 1, characterized in that: The speed of centrifugal separation in step 3) is 4000-10000 r / min, the time is controlled within 30 min, and the moisture content of the product after overnight drying must be less than 10%.
6. The use of a biochar-coupled copper catalyst in the preparation of vinyl chloride by acetylene hydrochlorination as claimed in claim 1, characterized in that The molar ratio of HCl and C2H2 is 0.95~1.2:1, and the volumetric space velocity of acetylene is 30~720 h -1 .