Preparation of Copper(Ⅱ) Catalyst and Its Application in Catalytic Synthesis of Polyvinyl Chloride

Abstract

The present invention relates to the field of catalyst technology, and in particular to the preparation of a copper (II) catalyst and its application in catalyzing the synthesis of polyvinyl chloride. The present invention simultaneously coordinates a copper ion with a 1-(3-carboxyphenyl)-5-methyl-4-oxo-1,4-dihydropyridazine-3-carboxyl (3-PDCA) ligand and a 4,4'-bipyridine ligand, and utilizes two bridging ligands to form a special hexagonal network structure, thereby obtaining a copper (II) catalyst with a novel structure. The copper (II) catalyst has high acetylene conversion and good stability. More importantly, the development of a new coordination polymer catalyst makes it possible to replace traditional catalysts, thus filling the industry gap in mercury-free production of polyvinyl chloride using the calcium carbide process.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, in particular to the preparation of a copper (II) catalyst and its application in catalyzing polyvinyl chloride synthesis. Background Art

[0002] Vinyl chloride is an important industrial intermediate widely used in processes such as the preparation of polyvinyl chloride (PVC). Its synthesis is usually obtained by the chlorination reaction of ethylene with chlorine, but this method has environmental and energy consumption issues. Catalytic synthesis of vinyl chloride has become an important way to reduce environmental impact and improve energy efficiency. Commonly used catalysts include metal chlorides, oxides or organic coordination polymers containing metal centers, which can promote the selective reaction of ethylene and chlorine, increasing the yield and product purity of vinyl chloride. In addition, optimizing reaction conditions such as temperature, pressure and reactant ratio also has a significant impact on the efficiency and selectivity of the reaction. Therefore, research and development of efficient and environmentally friendly catalytic systems are of great significance for the industrial production of vinyl chloride.

[0003] The present invention adopts solvent thermal synthesis conditions to synthesize copper (II) catalyst, and tests its catalytic vinyl chloride synthesis performance. The copper (II) catalyst exhibits good acetylene hydrochlorination activity as a catalyst. Its high acetylene conversion rate and high vinyl chloride selectivity are likely to become a mainstream new coordination polymer catalyst for synthesizing vinyl chloride. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for preparing a copper (II) catalyst and its application in catalyzing the synthesis of polyvinyl chloride. By program-controlling the temperature of the solvent thermal reaction, a copper ion is coordinated with a 3-PDCA ligand and a 4,4'-bipyridine ligand at the same time, and a special hexagonal network structure is formed by two bridging ligands to prepare a copper (II) catalyst C. 18 H 14 CuN3O6, whose coordination polymer has good stability, is used as a catalyst in the preparation process of vinyl chloride from hydrogen chloride and acetylene. Its high conversion rate and high selectivity are likely to become the mainstream mercury-free catalyst for the synthesis of polyvinyl chloride.

[0005] In order to solve the above technical problems, the present invention provides a copper (II) catalyst, the molecular formula of which is C 18 H 14 CuN3O6.

[0006] The present invention provides a method for preparing the above-mentioned copper (II) catalyst, comprising the following steps:

[0007] S1. Add 3-PDCA ligand and 4,4'-bipyridine ligand to acetonitrile and stir evenly to obtain an acetonitrile suspension;

[0008] S2. Dissolve copper nitrate trihydrate in deionized water and stir to obtain a copper nitrate trihydrate solution;

[0009] S3. Add the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, stir evenly, and after solvent thermal reaction, filter, wash and vacuum dry in sequence to obtain a copper (II) catalyst.

[0010] According to the preparation method provided by the present invention, the molar volume ratio of the 3-PDCA ligand, 4,4'-bipyridine ligand and acetonitrile in S1 is 0.05 mmol:0.05 mmol:2-4 mL.

[0011] The preparation method provided by the present invention is characterized in that the molar volume ratio of copper nitrate trihydrate and deionized water in S2 is 0.1 mmol: 1-3 mL;

[0012] According to the preparation method provided by the present invention, the temperature control procedure of the solvent thermal reaction in S3 is: heating to 110°C and maintaining for 48 hours, and then cooling to room temperature, the heating rate of the heating is 0.1°C / min, and the cooling rate of the cooling is 0.1°C / min.

[0013] According to the preparation method provided by the present invention, the volume ratio of the hydrated copper nitrate solution and the acetonitrile suspension in S3 is 1:1.

[0014] According to the preparation method provided by the present invention, the detergent selected for washing in S3 is a mixed detergent of acetonitrile and deionized water, and the volume ratio of acetonitrile to deionized water in the mixed detergent is 1:1.

[0015] According to the preparation method provided by the present invention, the stirring speed in S1, S2 and S3 is 1200 rpm.

[0016] The present invention also provides an application of the copper (II) catalyst, wherein the copper (II) catalyst is used for catalyzing the synthesis of vinyl chloride.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention simultaneously coordinates a copper ion with a 3-PDCA ligand and a 4,4'-bipyridine ligand, and uses two bridging ligands to form a special hexagonal network structure, thereby obtaining a copper (II) catalyst C with a novel structure. 18 H 14 CuN3O6, the copper (II) catalyst can be used as a catalyst in the process of synthesizing vinyl chloride from hydrogen chloride and acetylene.

[0019] (2) The copper (II) catalyst in the present invention has a high acetylene conversion rate and good stability. The development of new coordination polymer catalysts to replace traditional catalysts becomes possible, which can fill the industry gap in the mercury-free production of polyvinyl chloride by the calcium carbide process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the molecular structure of copper (II) catalyst;

[0021] Figure 2 is the network structure diagram of copper (II) catalyst;

[0022] Figure 3 This is a performance diagram of acetylene conversion and polyethylene selectivity of copper (II) catalyst. DETAILED DESCRIPTION

[0023] Example 1

[0024] This embodiment provides a method for preparing a copper (II) catalyst, comprising the following steps:

[0025] S1, take 0.05 mmol of 1-(3-carboxyphenyl)-5-methyl-4-oxo-1,4-dihydropyridazine-3-carboxyl (3-PDCA) ligand and 0.05 mmol of 4,4'-bipyridine ligand, add them to 3 mL of acetonitrile, and stir at a speed of 1200 rpm to obtain an acetonitrile suspension;

[0026] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0027] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 110° C. and maintaining for 72 h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1° C. / min, and the cooling rate during the cooling process is 0.1° C. / min;

[0028] After the solvent thermal reaction is completed, the solution in the reactor is filtered and then washed three times with a mixed detergent of acetonitrile and deionized water in a volume ratio of 1:1. After vacuum drying, the light blue block crystals are obtained, which is the copper (II) catalyst with the molecular formula C 18 H 14 CuN3O6, yield is 72.3%.

[0029] The chemical structure of the 3-PDCA ligand used in this embodiment is:

[0030] The chemical structure of 4,4'-bipyridine is:

[0031] 3-PDCA ligand and 4,4'-bipyridine are bridging organic acid ligands that function to connect adjacent metal nodes. They have good chemical stability and reactivity, and can obtain a stable coordination polymer with catalytic properties.

[0032] In this embodiment, a copper ion is coordinated with a 3-PDCA ligand and a 4,4'-bipyridine ligand at the same time, and two bridging ligands are used to form a special hexagonal network structure, thereby obtaining a copper (II) catalyst with a novel structure.

[0033] After testing the catalytic performance of vinyl chloride, it was found that the copper (II) catalyst has good stability and can be used as a catalyst in the process of synthesizing vinyl chloride from hydrogen chloride and acetylene.

[0034] Example 2

[0035] S1. Add 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand to 2 mL of acetonitrile and stir at 1200 rpm to obtain an acetonitrile suspension.

[0036] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0037] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 110° C. and maintaining for 72 h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1° C. / min, and the cooling rate during the cooling process is 0.1° C. / min;

[0038] After the solvent thermal reaction is completed, the solution in the reactor is filtered and then washed three times with a mixed detergent of acetonitrile and deionized water in a volume ratio of 1:1. After vacuum drying, the light blue block crystals are obtained, which is the copper (II) catalyst with the molecular formula C 18 H 14 CuN3O6, yield 71.1%.

[0039] Example 3

[0040] This embodiment provides a method for preparing a copper (II) catalyst, comprising the following steps:

[0041] S1. Take 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand and add them to 4 mL of acetonitrile, and stir them at a speed of 1200 rpm to obtain an acetonitrile suspension;

[0042] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0043] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 110° C. and maintaining for 72 h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1° C. / min, and the cooling rate during the cooling process is 0.1° C. / min;

[0044] After the solvent thermal reaction is completed, the solution in the reactor is filtered and then washed three times with a mixed detergent of acetonitrile and deionized water in a volume ratio of 1:1. After vacuum drying, the light blue block crystals are obtained, which is the copper (II) catalyst with the molecular formula C 18 H 14 CuN3O6, yield 70.6%.

[0045] Example 4

[0046] S1. Add 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand to 3 mL of acetonitrile and stir at 1200 rpm to obtain an acetonitrile suspension.

[0047] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 1 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0048] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 110° C. and maintaining for 72 h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1° C. / min, and the cooling rate during the cooling process is 0.1° C. / min;

[0049] After the solvent thermal reaction is completed, the solution in the reactor is filtered and then washed three times with a mixed detergent of acetonitrile and deionized water in a volume ratio of 1:1. After vacuum drying, the light blue block crystals are obtained, which is the copper (II) catalyst with the molecular formula C 18 H 14 CuN3O6, yield is 69.7%.

[0050] Comparative Example 1

[0051] In this comparative example, compared with Example 1, the solvent thermal reaction in S3 was eliminated and the evaporation was carried out slowly at room temperature. The specific operation was as follows:

[0052] S1. Add 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand to 3 mL of acetonitrile and stir at 1200 rpm to obtain an acetonitrile suspension.

[0053] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0054] S3. Add the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stir evenly at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1. Place the mixed suspension in a container, seal the container with plastic wrap and poke small holes in the plastic wrap, place the sealed and poke-hole container in a room temperature environment, and slowly evaporate. Ultimately, no testable crystals are obtained.

[0055] Comparative Example 2

[0056] In this comparative example, compared with Example 1, the washed product was evaporated directly at room temperature without vacuum drying. The specific steps are as follows:

[0057] S1. Add 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand to 3 mL of acetonitrile and stir at 1200 rpm to obtain an acetonitrile suspension.

[0058] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0059] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 110° C. and maintaining for 72 h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1° C. / min, and the cooling rate during the cooling process is 0.1° C. / min;

[0060] The solution in the reactor was then filtered and washed three times with a mixed detergent of acetonitrile and deionized water in a volume ratio of 1:1. The washed product was then placed in a container, sealed with plastic wrap and small holes were punched in the plastic wrap. The sealed and punched container was placed in a room temperature environment to allow the remaining solvent to slowly evaporate, and finally a powdered solid was obtained.

[0061] Comparative Example 3

[0062] In this comparative example, the temperature control procedure of the solvothermal reaction was modified relative to Example 1, and the specific steps were as follows:

[0063] S1. Add 0.05 mmol of 3-PDCA ligand and 0.05 mmol of 4,4'-bipyridine ligand to 3 mL of acetonitrile and stir at 1200 rpm to obtain an acetonitrile suspension.

[0064] S2. Dissolve 0.1 mmol of copper nitrate trihydrate in 3 mL of deionized water and stir at 1200 rpm to obtain a copper nitrate trihydrate solution.

[0065] S3, adding the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, and stirring at a speed of 1200 rpm to obtain a mixed suspension, wherein the volume ratio of the copper nitrate trihydrate solution to the acetonitrile suspension is 1:1, and the mixed suspension is placed in an autoclave, and the temperature is programmed to perform a solvothermal reaction. The specific temperature control program is: heating to 90°C and maintaining for 72h, and then cooling to room temperature, wherein the heating rate during the heating process is 0.1°C / min, and the cooling rate during the cooling process is 0.1°C / min;

[0066] The solution in the reactor was then filtered, washed three times with acetonitrile and deionized water in a volume ratio of 1:1, and then vacuum dried to obtain light blue block crystals.

[0067] Example 5

[0068] The elemental analysis of the blue block crystals finally obtained in Example 1 showed that: 18 H 14 CuN3O6, molecular weight 431.86.

[0069] The blue bulk crystals obtained in Example 1 were tested using a Bruker SMART 1000CCD surface diffractometer, specifically using a wavelength of The MoKα ray and ω scanning mode were used. The collected diffraction points were restored using the SAINT program and corrected using the SADABS program. Based on the full-angle least squares method, the crystallographic software SHELXTL 5.1 package was used to find the coordinates of all non-hydrogen atoms on the difference Fourier map using a direct method. Then, all non-hydrogen atoms were refined using anisotropic refinement. The schematic diagram of the solved molecular structure is shown below. Figure 1 The obtained crystallographic parameters are shown in Table 1:

[0070] Table 1

[0071]

[0072]

[0073] R1=∑||F o |-|F c || / ∑|F o |,wR2=[∑w(F o 2 -F c 2 ) 2 / ∑w(F o 2 ) 2 ] 1 / 2 .

[0074] As shown in Table 1, the R1 value is less than 0.05, indicating that there is no error in the structural analysis and the true molecular structure is obtained.

[0075] Example 6

[0076] In this example, the catalyst activity of the blue block crystals finally obtained in Example 1 was evaluated.

[0077] 50 mg of the blue block crystals obtained in Example 1 were placed in a stainless steel fixed-bed reactor with an inner diameter of 25 mm. The reactor was temperature-controlled by a thermocouple. The hydrogen chloride and acetylene were purified and dried before entering the premixing device. V(HCl):V(C2H2)=1.05, and the air velocity was 90 h -1 The tail gas after the reaction is washed with sodium hydroxide solution, deacidified and dried before entering into gas chromatography, where the catalytic performance of the catalyst is tested by gas chromatography analysis.

[0078] This example uses a GC-9790 gas chromatograph, a GDX-301 packed column, and an FID detector. The column temperature is 150° C., the detector temperature is 120° C., the analyzed components are acetylene, vinyl chloride, and ethylene dichloride, and the external standard method is used to measure the amount of each component.

[0079] The catalytic performance of the blue block crystals obtained in Example 1 was evaluated using acetylene conversion (X) and vinyl chloride selectivity (S) as indicators. Since hydrogen chloride is absorbed and removed after the reaction, the entire reaction system can be considered as having a constant volume for calculation purposes, and the total volume is calculated as 1 volume unit. The calculation formula is:

[0080]

[0081] Where, is the residual acetylene volume fraction; is the volume fraction of vinyl chloride.

[0082] The acetylene conversion rate and vinyl chloride selectivity curve obtained from the catalyst performance test are as follows: Figure 3 As shown by Figure 3 It can be seen that the copper (II) catalyst prepared in Example 1 has a high acetylene conversion rate and vinyl chloride selectivity as a catalyst in the process of synthesizing vinyl chloride from hydrogen chloride and acetylene.

[0083] The copper (II) catalyst maintained an acetylene conversion rate of 96.3% and a vinyl chloride selectivity of 98.1% within 2400 hours. Compared with traditional catalysts, it has the advantages of good stability, high conversion rate and high selectivity.

[0084] From the above experimental results, it can be seen that the copper (II) catalyst in the present invention has a high acetylene conversion rate and good stability. More importantly, the development of new coordination polymer catalysts to replace traditional catalysts has become possible, which can fill the industry gap in the mercury-free production of polyvinyl chloride by the calcium carbide process.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A copper (II) catalyst, characterized in that The molecular formula of the copper (II) catalyst is C 18 H 14 CuN3O6, the copper (II) catalyst contains ligand 4,4'-bipyridine and ligand 1, and the structural formula of ligand 1 is: 。 2. A method for preparing the copper (II) catalyst as claimed in claim 1, characterized in that: The following steps are involved: S1. Add ligand 1 and 4,4'-bipyridine ligand to acetonitrile and stir evenly to obtain an acetonitrile suspension; S2. Dissolve copper nitrate trihydrate in deionized water and stir to obtain a copper nitrate trihydrate solution; S3. Add the copper nitrate trihydrate solution prepared in S2 to the acetonitrile suspension prepared in S1, stir evenly, and after solvent thermal reaction, filter, wash and vacuum dry in sequence to obtain a copper (II) catalyst.

3. The preparation method according to claim 2, characterized in that: The molar volume ratio of the ligand 1, 4,4'-bipyridine ligand and acetonitrile in S1 is 0.05 mmol:0.05 mmol:2-4 mL, and the molar volume ratio of the copper nitrate trihydrate and deionized water in S2 is 0.1 mmol:1-3 mL.

4. The preparation method according to claim 2, characterized in that The temperature control program of the solvothermal reaction in S3 is: heating to 110°C and maintaining for 48 h, then cooling to room temperature, the heating rate of the heating is 0.1°C / min, and the cooling rate of the cooling is 0.1°C / min.

5. The preparation method according to claim 2, characterized in that: The volume ratio of the hydrated copper nitrate solution and the acetonitrile suspension in S3 is 1:

1.

6. The preparation method according to claim 2, characterized in that: The detergent used for washing in S3 is a mixed detergent of acetonitrile and deionized water, and the volume ratio of acetonitrile to deionized water in the mixed detergent is 1:

1.

7. The preparation method according to claim 2, characterized in that: The stirring speed in S1, S2 and S3 was 1200 rpm.

8. Use of a copper (II) catalyst as claimed in any one of claims 1 to 7, characterized in that: The copper (II) catalyst is used for catalyzing the synthesis of polyvinyl chloride.

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