A bimetallic complex catalyst for acetylene hydrochlorination reaction and preparation and application thereof
By preparing a bimetallic complex catalyst, the problems of insufficient activity and stability of copper-based catalysts in the acetylene hydrochlorination reaction were solved, achieving efficient acetylene conversion and vinyl chloride selectivity, avoiding metal sublimation and toxicity, and making it suitable for the acetylene hydrochlorination reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2024-12-20
- Publication Date
- 2026-06-05
AI Technical Summary
Existing copper-based catalysts for the acetylene hydrochlorination reaction suffer from poor activity and stability, especially at high temperatures where they are prone to carbon buildup and are difficult to produce industrially.
A bimetallic complex catalyst was prepared by generating polydentate ligands from aldehydes and amines in a solvent, then reacting them with copper and cobalt salts to form bimetallic complexes, which were then supported on activated carbon for use in the hydrochlorination of acetylene.
It improves the catalyst's activity and resistance to carbon deposition, exhibits good catalytic activity and vinyl chloride selectivity, while avoiding metal sublimation and toxicity issues. The preparation method is simple and environmentally friendly.
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Abstract
Description
Technical Field
[0001] This invention relates to a bimetallic complex catalyst for the hydrochlorination of acetylene, its preparation method, and its application. Background Technology
[0002] Acetylene hydrochlorination is an important industrial process for producing vinyl chloride monomer (VCM), which is then used as a starting material for the production of polyvinyl chloride (PVC). Although VCM can also be obtained through vinyl processes, the hydrochlorination of acetylene is becoming increasingly important due to rising oil prices, as acetylene is derived from the coal industry. Currently, acetylene hydrochlorination is still widely used in VCM production in China (approximately 7.21 million tons / year), primarily under the catalysis of HgCl2 supported on activated carbon. However, HgCl2 catalysts have some inherent drawbacks, particularly their toxicity and volatility.
[0003] Since the 1970s, researchers both domestically and internationally have been studying mercury-free catalysts for the hydrochlorination of acetylene. Extensive research indicates that currently, mercury-free catalysts suitable for industrial application are mainly those with noble metals (such as Au, Pt, and Ru) as active components and those with non-noble metals (such as Cu, Sn, and Bi) as active components. Driven by economic considerations, non-noble metal mercury-free catalysts have seen a surge in research in recent years, particularly Cu-based catalysts, resulting in numerous publications and patent reports. Currently, the main problems with copper-based hydrochlorination catalysts for acetylene include poor activity and stability, or difficulties in industrializing their preparation methods. Many publications and patents have proposed solutions to these problems.
[0004] CN 108654653 A patent discloses a method for preparing a mercury-free catalyst for the synthesis of vinyl chloride. First, coal-based activated carbon is ultrasonically cleaned with distilled water and dried. Tin tetrachloride, copper chloride, bismuth trichloride, barium chloride, and cerium trichloride are dissolved in a hydrogen chloride solution to prepare an impregnation solution. This solution is then loaded onto the treated activated carbon using an equal-volume impregnation method. The carbon is then transferred to a rotary evaporator and evaporated at 60-64°C for 5.5-6.5 hours to evaporate most of the moisture. Finally, the carbon is dried in an oven at 100-105°C for 13-15 hours and cooled to obtain the final catalyst. Although this preparation method is simple and yields a catalyst with excellent performance, approaching that of mercury catalysts, it still faces challenges related to metal ion reduction and carbon deposition, leading to reduced catalyst stability and shortened lifespan.
[0005] Patent CN 103007972 A discloses a mercury-free catalyst for the hydrochlorination of acetylene to synthesize vinyl chloride. The catalyst is prepared by dissolving copper chloride dihydrate and cobalt chloride hexahydrate in an aqueous solution, and then loading the solution onto activated carbon. However, the catalyst fails to react within 180 hours. -1Catalytic hydrochlorination of acetylene at 140℃ yielded an acetylene conversion rate of only 29%.
[0006] Patent CN 112916049 A discloses a copper-based catalyst modified with oxygen-containing multidentate ligands for the hydrochlorination of acetylene, its preparation method, and its application. The catalyst uses activated carbon as a support and copper salt as the main active component. The catalytic activity and stability are improved by adding oxygen-containing multidentate ligands. The reaction conditions are 130℃ and acetylene space velocity 40 h⁻¹. -1 When the volume ratio of hydrogen chloride to acetylene is 1.2:1, the acetylene conversion rate is less than 90%. Summary of the Invention
[0007] To address the problem of poor activity and stability of copper-based catalysts used in the hydrochlorination of acetylene, this invention provides a bimetallic complex catalyst for the hydrochlorination of acetylene, its preparation method, and its application.
[0008] The technical solution adopted in this invention is as follows:
[0009] In a first aspect, the present invention provides a method for preparing a bimetallic complex catalyst for the hydrochlorination of acetylene, comprising the following steps: at room temperature, mixing an aldehyde compound and an amine compound in a solvent, stirring thoroughly to generate a multidentate ligand, then adding a copper salt and a cobalt salt, wherein the molar ratio of the copper salt and the cobalt salt is 1-2:0.5-2 based on the molar ratio of copper and cobalt elements contained in each salt; then stirring thoroughly to generate a bimetallic complex; mixing the resulting reaction solution with an acid-washed activated carbon support, stirring thoroughly to impregnate, drying, and cooling to obtain the bimetallic complex catalyst for the hydrochlorination of acetylene;
[0010] The aldehyde compound is selected from one of 3-chlorosalicylaldehyde, 3,5-dichloro-2-hydroxybenzaldehyde, 4-bromo-2-hydroxybenzaldehyde, and 3-chloro-2-hydroxybenzaldehyde; the amine compound is selected from one of o-phenylenediamine and 4-bromobenzoylhydrazine.
[0011] Preferably, the solvent is at least one of methanol, ethanol, and acetonitrile.
[0012] Preferably, the molar ratio of the aldehyde compound, amine compound, copper salt, and cobalt salt is 1-2.5:1-1.5:1-2:0.5-2, and the molar number of the copper salt and cobalt salt is calculated based on the molar number of copper and cobalt elements contained therein.
[0013] Preferably, the reaction is stirred at room temperature for 1-5 hours to generate polydentate ligands.
[0014] Preferably, the copper salt is copper chloride and the cobalt salt is cobalt chloride.
[0015] Preferably, the copper element in the copper salt accounts for 9-20% of the mass percentage of the activated carbon.
[0016] Preferably, the reaction is stirred at room temperature for 1-5 hours to generate a bimetallic complex.
[0017] Preferably, the activated carbon is first cleaned with hydrochloric acid.
[0018] Preferably, the stirring and soaking time is 2-8 hours.
[0019] As a preferred method, the drying conditions are: drying in an oven at 100°C for 12-15 hours.
[0020] In a second aspect, the present invention provides a bimetallic complex catalyst for the hydrochlorination reaction of acetylene prepared according to the preparation method described in the first aspect.
[0021] Thirdly, the present invention provides the application of the bimetallic complex catalyst described in the second aspect in the acetylene hydrochlorination reaction.
[0022] The specific application involves: loading a mercury-free catalyst into a fixed-bed reactor, introducing a mixed feed gas of acetylene and hydrogen chloride, and maintaining a gas space velocity of 160-180 h⁻¹. -1 Acetylene hydrochlorination is carried out at a reaction temperature of 160-200℃ to produce vinyl chloride.
[0023] Preferably, in the mixed raw material gas, V(C2H2):V(HCl) = 1:1.1-1.2.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0025] (1) The catalyst prepared by the present invention has good activity and anti-carbon deposition properties, and has good catalytic activity and vinyl chloride selectivity in the process of acetylene hydrochlorination to produce vinyl chloride.
[0026] (2) The catalyst prepared by this invention is environmentally friendly and the catalyst preparation method is simple; the active component is stable, there is no sublimation problem under the reaction conditions, and it is non-toxic. Attached Figure Description
[0027] Figure 1 This is a graph showing the change in acetylene conversion rate over reaction time for the catalyst samples in the examples and comparative examples.
[0028] Figure 2 This is a graph showing the change in vinyl chloride selectivity of the catalyst samples in the examples and comparative examples as a function of reaction time. Detailed Implementation
[0029] The technical solution of the present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0030] Example 1
[0031] (1) Preparation of catalyst system
[0032] I. 1.56 g of 3-chlorosalicylaldehyde and 1.21 g of o-phenylenediamine were sequentially added to 30 ml of methanol. The resulting yellow suspension was stirred at room temperature for 2 h to obtain a novel polydentate ligand. 2 g of CoCl2 and 2 g of CuCl2 were added to the above solution, and the resulting solution was stirred for another 2 h. This preparation method can yield bimetallic complexes constructed from halide polydentate ligands with good catalytic performance.
[0033] II. Weigh 10g of Norit Rox 0.8 activated carbon that has been washed with hydrochloric acid into a beaker. Pour the above solution into the beaker containing the activated carbon, stir and impregnate for 6 hours, and then dry in an oven at 100℃ for 12 hours. Cool to obtain Cu-Co catalyst.
[0034] (2) Acetylene hydrochlorination reaction
[0035] Weigh 5g of the catalyst prepared above and pack it into a fixed-bed reactor (quartz glass) with an inner diameter of 10mm. Incubate the reactor at a gas space velocity of 180h⁻¹. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of a reaction temperature of 160℃ and a feed gas ratio of V(C2H2):V(HCl) = 1:1.2. The acetylene conversion rate as a function of reaction time is shown in the figure. Figure 1 The selectivity of vinyl chloride as a function of reaction time is shown in the figure. Figure 2 .
[0036] Example 2
[0037] (1) Preparation of catalyst system
[0038] I. 1.91 g of 3,5-dichloro-2-hydroxybenzaldehyde and 2.15 g of 4-bromobenzoylhydrazine were added to 30 mL of methanol. The resulting yellow suspension was stirred at room temperature for 2 h to obtain a novel polydentate ligand. 2 g of CoCl2 and 2 g of CuCl2 were added to the above solution, and the resulting solution was stirred for another 2 h. This preparation method can yield bimetallic complexes constructed from halide polydentate ligands with good catalytic performance.
[0039] II. Weigh 10g of Norit Rox 0.8 activated carbon that has been washed with hydrochloric acid into a beaker. Pour the above solution into the beaker containing the activated carbon, stir and impregnate for 6 hours, and then dry in an oven at 100℃ for 12 hours. Cool to obtain Cu-Co catalyst.
[0040] (2) Acetylene hydrochlorination reaction
[0041] Weigh 5g of the catalyst prepared above and pack it into a fixed-bed reactor (quartz glass) with an inner diameter of 10mm. Incubate the reactor at a gas space velocity of 180h⁻¹. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of a reaction temperature of 160℃ and a feed gas ratio of V(C2H2):V(HCl) = 1:1.2. The acetylene conversion rate as a function of reaction time is shown in the figure. Figure 1 The selectivity of vinyl chloride as a function of reaction time is shown in the figure. Figure 2 .
[0042] Example 3
[0043] (1) Preparation of catalyst system
[0044] I. Add 2.01 g of 4-bromo-2-hydroxybenzaldehyde and 2.15 g of 4-bromobenzoylhydrazine to 30 mL of methanol. Stir the resulting yellow suspension at room temperature for 2 h to obtain a novel polydentate ligand. Add 2 g of CoCl2 and 2 g of CuCl2 to the above solution, and stir the resulting solution for another 2 h. This preparation method can yield bimetallic complexes constructed from halide polydentate ligands with good catalytic performance.
[0045] II. Weigh 10g of Norit Rox 0.8 activated carbon that has been washed with hydrochloric acid into a beaker. Pour the above solution into the beaker containing the activated carbon, stir and impregnate for 6 hours, and then dry in an oven at 100℃ for 12 hours. Cool to obtain Cu-Co catalyst.
[0046] (2) Acetylene hydrochlorination reaction
[0047] Weigh 5g of the catalyst prepared above and pack it into a fixed-bed reactor (quartz glass) with an inner diameter of 10mm. Incubate the reactor at a gas space velocity of 180h⁻¹. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of a reaction temperature of 160℃ and a feed gas ratio of V(C2H2):V(HCl) = 1:1.2. The acetylene conversion rate as a function of reaction time is shown in the figure. Figure 1 The selectivity of vinyl chloride as a function of reaction time is shown in the figure. Figure 2 .
[0048] Example 4
[0049] (1) Preparation of catalyst system
[0050] I. 1.56 g of 3-chloro-2-hydroxybenzaldehyde and 2.15 g of 4-bromobenzoylhydrazine were added to 30 mL of methanol. The resulting yellow suspension was stirred at room temperature for 2 h to obtain a novel polydentate ligand. 2 g of CoCl2 and 2 g of CuCl2 were added to the above solution, and the resulting solution was stirred for another 2 h. This preparation method can yield bimetallic complexes constructed from halide polydentate ligands with good catalytic performance.
[0051] II. Weigh 10g of Norit Rox 0.8 activated carbon that has been washed with hydrochloric acid into a beaker. Pour the above solution into the beaker containing the activated carbon, stir and impregnate for 6 hours, and then dry in an oven at 100℃ for 12 hours. Cool to obtain Cu-Co catalyst.
[0052] (2) Acetylene hydrochlorination reaction
[0053] Weigh 5g of the catalyst prepared above and pack it into a fixed-bed reactor (quartz glass) with an inner diameter of 10mm. Incubate the reactor at a gas space velocity of 180h⁻¹. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of a reaction temperature of 160℃ and a feed gas ratio of V(C2H2):V(HCl) = 1:1.2. The acetylene conversion rate as a function of reaction time is shown in the figure. Figure 1 The selectivity of vinyl chloride as a function of reaction time is shown in the figure. Figure 2 .
[0054] Comparative Example 1
[0055] (1) Preparation of the catalyst system:
[0056] I. 2.01 g of 3-bromo-2-hydroxybenzaldehyde and 2.15 g of 4-bromobenzoylhydrazine were added to 30 mL of methanol solution. The resulting yellow suspension was stirred at room temperature for 2 h to obtain a novel multidentate ligand. 2 g of CuCl2 was added to the above solution, and the resulting solution was stirred for another 2 h.
[0057] II. Weigh 10g of Norit Rox 0.8 activated carbon that has been washed with hydrochloric acid into a beaker. Pour the above solution into the beaker containing the activated carbon, stir and soak for 6 hours, then dry in an oven at 100℃ for 12 hours. Cool to obtain Cu catalyst.
[0058] (2) Acetylene hydrochlorination reaction
[0059] Weigh 5g of the catalyst prepared above and pack it into a fixed-bed reactor (quartz glass) with an inner diameter of 10mm. Incubate the reactor at a gas space velocity of 180h⁻¹. -1The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of a reaction temperature of 160℃ and a feed gas ratio of V(C2H2):V(HCl) = 1:1.2. The acetylene conversion rate as a function of reaction time is shown in the figure. Figure 1 The selectivity of vinyl chloride as a function of reaction time is shown in the figure. Figure 2 .
[0060] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.
Claims
1. A method for preparing a bimetallic complex catalyst for the hydrochlorination reaction of acetylene, characterized in that: The preparation method includes the following steps: at room temperature, aldehyde compounds and amine compounds are mixed in a solvent and stirred thoroughly to generate a multidentate ligand. Then, copper salt and cobalt salt are added, wherein the molar ratio of copper salt and cobalt salt is 1-2:0.5-2 based on the molar ratio of copper and cobalt elements contained in each salt. The resulting mixture is then stirred thoroughly to generate a bimetallic complex. The resulting reaction solution is mixed with an acid-washed activated carbon support, stirred thoroughly, impregnated, dried, and cooled to obtain a bimetallic complex catalyst for the acetylene hydrochlorination reaction. The aldehyde compound is selected from one of 3-chlorosalicylaldehyde, 3,5-dichloro-2-hydroxybenzaldehyde, 4-bromo-2-hydroxybenzaldehyde, and 3-chloro-2-hydroxybenzaldehyde; the amine compound is selected from one of o-phenylenediamine and 4-bromobenzoylhydrazine.
2. The preparation method according to claim 1, characterized in that: The solvent is at least one of methanol, ethanol, and acetonitrile.
3. The preparation method according to claim 1, characterized in that: The molar ratio of the aldehyde compound, amine compound, copper salt, and cobalt salt is 1-2.5:1-1.5:1-2:0.5-2, and the molar number of the copper salt and cobalt salt is calculated based on the molar number of copper and cobalt elements contained therein.
4. The preparation method according to claim 1, characterized in that: Stir the reaction at room temperature for 1-5 hours to generate polydentate ligands.
5. The preparation method according to claim 1, characterized in that: The copper salt is copper chloride, and the cobalt salt is cobalt chloride.
6. The preparation method according to claim 1, characterized in that: The copper element in the copper salt accounts for 9-20% of the mass percentage of the activated carbon.
7. The preparation method according to claim 1, characterized in that: The reaction was stirred at room temperature for 1-5 hours to generate a bimetallic complex.
8. The preparation method according to claim 1, characterized in that: The stirring and soaking time is 2-8 hours.
9. A bimetallic complex catalyst for the hydrochlorination reaction of acetylene, prepared by the method according to any one of claims 1-8.
10. The application of the bimetallic complex catalyst as described in claim 9 in the acetylene hydrochlorination reaction.