Bimetal complex catalyst for acetylene hydrochlorination reaction as well as preparation and application thereof

Abstract

The invention discloses a preparation method of a bimetallic complex catalyst for acetylene hydrochlorination reaction, and the preparation method comprises the following steps: mixing an aldehyde compound and an amine compound in a solvent at room temperature, fully stirring and reacting to generate a polydentate ligand, then adding a copper salt and a cobalt salt, and reacting to obtain the bimetallic complex catalyst for acetylene hydrochlorination reaction. And fully stirring the obtained mixture for reaction to generate a bimetallic complex, mixing the obtained reaction liquid with an acid-washed activated carbon carrier, fully stirring and dipping, drying, and cooling to obtain the bimetallic complex catalyst for acetylene hydrochlorination reaction. The bimetallic complex catalyst prepared by the invention has good activity and carbon deposition resistance, and has good catalytic activity, vinyl chloride selectivity and stability in the process of generating vinyl chloride through acetylene hydrochlorination reaction.

Description

Technical Field

[0001] The invention relates to a bimetallic complex catalyst for acetylene hydrochlorination reaction, and a preparation method and application thereof. Background Art

[0002] Acetylene hydrochlorination is an important industrial process for the production of vinyl chloride monomer (VCM), and further as a starting material for the production of polyvinyl chloride. Although VCM can also be obtained by the vinyl process, the hydrochlorination of acetylene is becoming increasingly important due to rising oil prices, as acetylene comes from the coal industry. Currently, acetylene hydrochlorination is still widely used in the production of VCM in China (about 7.21 million tons / year), mainly under the catalysis of activated carbon-supported HgC12. However, HgC12 catalysts have some inherent disadvantages, especially the toxicity and volatility of the catalyst.

[0003] Since the 1970s, relevant scientific researchers at home and abroad have begun research on mercury-free catalysts for acetylene hydrochlorination. A large number of research results show that the mercury-free catalysts that are currently suitable for industrial application are mainly catalysts with precious metals (such as Au, Pt, Ru) as active components and catalysts with non-precious metals (such as Cu, Sn, Bi) as active components. Based on economic efficiency, non-precious metal mercury-free catalysts have ushered in a research boom in recent years, especially Cu-based catalysts, and a large number of literature and patent reports have appeared. At present, the main problems of copper-based catalysts for acetylene hydrochlorination are poor activity and stability or the preparation method is not easy to industrialize. Many documents and patents have proposed solutions to the above problems.

[0004] CN 108654653 A patent discloses a preparation method of a mercury-free catalyst for synthesizing vinyl chloride. First, the coal-based activated carbon is ultrasonically cleaned with distilled water and dried for use; tin tetrachloride, copper chloride, bismuth trichloride, barium chloride and cerium trichloride are dissolved in a hydrogen chloride solution to prepare an impregnation solution, and then the impregnation solution is loaded onto the above-treated activated carbon by an equal volume impregnation method, transferred to a rotary evaporator for rotary evaporation at 60-64°C for 5.5-6.5h, the water is basically evaporated, and finally dried in an oven at 100-105°C for 13-15h, and cooled to obtain. Although the preparation method is simple and the obtained catalyst has excellent performance, close to the level of mercury catalyst, it still faces the challenges of metal ion reduction and carbon deposition, resulting in reduced catalyst stability and shortened service life.

[0005] CN 103007972 A discloses a mercury-free catalyst for synthesizing vinyl chloride from acetylene hydrochlorination. The impregnation solution is prepared by dissolving cupric chloride dihydrate and cobalt chloride hexahydrate in an aqueous solution and loading the solution onto activated carbon. However, the catalyst is not fully degraded within 180 hours. -1, catalyzing the acetylene hydrochlorination reaction at 140°C, the conversion rate of acetylene was only 29%.

[0006] CN 112916049 A patent discloses a copper-based catalyst modified with oxygen-containing multidentate ligands for acetylene hydrochlorination reaction, and its preparation method and application. The catalyst uses activated carbon as a carrier and copper salt as the main active component. The catalytic activity and stability of the catalyst are improved by adding oxygen-containing multidentate ligands. Under the reaction conditions of 130°C and acetylene space velocity of 40h -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] In order to solve the problem of poor activity and stability of a copper-based catalyst used in acetylene hydrochlorination reaction, the present invention provides a bimetallic complex catalyst used in acetylene hydrochlorination reaction, a preparation method and an application thereof.

[0008] The technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a method for preparing a bimetallic complex catalyst for acetylene hydrochlorination reaction, comprising the following steps: at room temperature, mixing an aldehyde compound and an amine compound in a solvent, stirring the mixture thoroughly to react and generate a multidentate ligand, then adding a copper salt and a cobalt salt, wherein the molar ratio of the copper salt to the cobalt salt is 1-2:0.5-2 based on the molar ratio of the copper and cobalt elements contained in each, stirring the mixture thoroughly to react and generate a bimetallic complex, mixing the reaction solution with an acid-washed activated carbon carrier, stirring and impregnating the mixture thoroughly, drying the mixture, and cooling the mixture to obtain a bimetallic complex catalyst for acetylene hydrochlorination reaction;

[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-bromobenzohydrazide.

[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 numbers of the copper salt and cobalt salt are calculated based on the molar numbers of the copper element and the cobalt element contained therein.

[0013] Preferably, the reaction is stirred at room temperature for 1-5 h to form the multidentate ligand.

[0014] Preferably, the copper salt is copper chloride, and the cobalt salt is cobalt chloride.

[0015] Preferably, the mass percentage of copper element in the copper salt to the activated carbon is 9-20%.

[0016] Preferably, the reaction is stirred at room temperature for 1-5 hours to form a bimetallic complex.

[0017] Preferably, the activated carbon is first washed with hydrochloric acid.

[0018] Preferably, the stirring and immersion time is 2-8 hours.

[0019] Preferably, the drying condition is: drying in an oven at 100°C for 12-15h.

[0020] In a second aspect, the present invention provides a bimetallic complex catalyst for acetylene hydrochlorination reaction prepared according to the preparation method described in the first aspect.

[0021] In a third aspect, the present invention provides use of the bimetallic complex catalyst described in the second aspect in acetylene hydrochlorination reaction.

[0022] The specific application is as follows: the mercury-free catalyst is loaded into a fixed bed reactor, a mixed raw gas of acetylene and hydrogen chloride is introduced, and the gas space velocity is 160-180h -1 , acetylene is hydrochlorinated at a reaction temperature of 160-200°C to produce vinyl chloride.

[0023] Preferably, in the mixed raw gas, V(C2H2):V(HCl)=1:1.1-1.2.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The catalyst prepared by the present invention has good activity and resistance to carbon deposition, 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 the present invention is environmentally friendly and the catalyst preparation method is simple; the active components are stable, there is no sublimation problem under the reaction conditions, and it is non-toxic. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a curve diagram of acetylene conversion rate of catalyst samples of Examples and Comparative Examples versus reaction time.

[0028] Figure 2 It is a curve diagram of vinyl chloride selectivity of catalyst samples of Examples and Comparative Examples changing with reaction time. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below through specific embodiments, but the protection scope of the present invention is not limited thereto.

[0030] Example 1

[0031] (1) Preparation of catalyst system

[0032] Ⅰ. 1.56g 3-chlorosalicylaldehyde and 1.21g o-phenylenediamine were added to 30ml methanol in sequence, and the resulting yellow suspension was stirred at room temperature for 2h to obtain a novel multidentate ligand. 2g CoCl2 and 2g CuCl2 were added to the above solution, and the resulting solution was stirred for 2h. This preparation method can obtain a bimetallic complex constructed by a halogenated multidentate ligand with good catalytic performance.

[0033] Ⅱ. Weigh 10g of Norit rox 0.8 activated carbon washed with hydrochloric acid in a beaker, pour the above solution into the beaker containing activated carbon, stir and immerse for 6h, then dry in an oven at 100℃ for 12h. Cool and obtain a Cu-Co catalyst.

[0034] (2) Acetylene hydrochlorination reaction

[0035] 5 g of the catalyst prepared above was weighed and loaded into a fixed bed reactor (made of quartz glass) with an inner diameter of 10 mm. -1 The catalyst was evaluated for acetylene hydrochlorination activity under the conditions of reaction temperature of 160°C and feed gas ratio of V(C2H2):V(HCl)=1:1.2. The acetylene conversion rate versus reaction time curve is shown in Figure 1 The curve of vinyl chloride selectivity changing with reaction time is shown in Figure 2 .

[0036] Example 2

[0037] (1) Preparation of catalyst system

[0038] Ⅰ. 1.91g 3,5-dichloro-2-hydroxybenzaldehyde and 2.15g 4-bromobenzohydrazide were added to 30mL methanol, and the resulting yellow suspension was stirred at room temperature for 2h to obtain a novel multidentate ligand. 2g CoCl2 and 2g CuCl2 were added to the above solution, and the resulting solution was stirred for 2h. This preparation method can obtain a bimetallic complex constructed by a halogenated multidentate ligand with good catalytic performance.

[0039] Ⅱ. Weigh 10g of Norit rox 0.8 activated carbon washed with hydrochloric acid in a beaker, pour the above solution into the beaker containing activated carbon, stir and immerse for 6h, then dry in an oven at 100℃ for 12h. Cool and obtain a Cu-Co catalyst.

[0040] (2) Acetylene hydrochlorination reaction

[0041] 5 g of the catalyst prepared above was weighed and loaded into a fixed bed reactor (made of quartz glass) with an inner diameter of 10 mm. -1 The catalyst was evaluated for acetylene hydrochlorination activity under the conditions of reaction temperature of 160°C and feed gas ratio of V(C2H2):V(HCl)=1:1.2. The acetylene conversion rate versus reaction time curve is shown in Figure 1 The curve of vinyl chloride selectivity changing with reaction time is shown in Figure 2 .

[0042] Example 3

[0043] (1) Preparation of catalyst system

[0044] Ⅰ. Add 2.01g 4-bromo-2-hydroxybenzaldehyde and 2.15g 4-bromophenylhydrazide into 30mL methanol, and stir the resulting yellow suspension at room temperature for 2h to obtain a novel multidentate ligand. Add 2g CoCl2 and 2g CuCl2 into the above solution, and stir the resulting solution for 2h. This preparation method can obtain a bimetallic complex constructed by a halogenated multidentate ligand with good catalytic performance.

[0045] Ⅱ. Weigh 10g of Norit rox 0.8 activated carbon washed with hydrochloric acid in a beaker, pour the above solution into the beaker containing activated carbon, stir and immerse for 6h, then dry in an oven at 100℃ for 12h. Cool and obtain a Cu-Co catalyst.

[0046] (2) Acetylene hydrochlorination reaction

[0047] 5 g of the catalyst prepared above was weighed and loaded into a fixed bed reactor (made of quartz glass) with an inner diameter of 10 mm. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of reaction temperature of 160°C and feed gas ratio of V(C2H2):V(HCl)=1:1.2. The curve of acetylene conversion rate versus reaction time is shown in Figure 1 The curve of vinyl chloride selectivity changing with reaction time is shown in Figure 2 .

[0048] Example 4

[0049] (1) Preparation of catalyst system

[0050] Ⅰ. 1.56g 3-chloro-2-hydroxybenzaldehyde and 2.15g 4-bromobenzohydrazide were added to 30mL methanol, and the resulting yellow suspension was stirred at room temperature for 2h to obtain a novel multidentate ligand. 2g CoCl2 and 2g CuCl2 were added to the above solution, and the resulting solution was stirred for 2h. This preparation method can obtain a bimetallic complex constructed by a halogenated multidentate ligand with good catalytic performance.

[0051] Ⅱ. Weigh 10g of Norit rox 0.8 activated carbon washed with hydrochloric acid in a beaker, pour the above solution into the beaker containing activated carbon, stir and immerse for 6h, then dry in an oven at 100℃ for 12h. Cool and obtain a Cu-Co catalyst.

[0052] (2) Acetylene hydrochlorination reaction

[0053] 5 g of the catalyst prepared above was weighed and loaded into a fixed bed reactor (made of quartz glass) with an inner diameter of 10 mm. -1 The activity of the catalyst in the acetylene hydrochlorination reaction was evaluated under the conditions of reaction temperature of 160°C and feed gas ratio of V(C2H2):V(HCl)=1:1.2. The curve of acetylene conversion rate versus reaction time is shown in Figure 1 The curve of vinyl chloride selectivity changing with reaction time is shown in Figure 2 .

[0054] Comparative Example 1

[0055] (1) Preparation of catalyst system:

[0056] Ⅰ. Add 2.01 g of 3-bromo-2-hydroxybenzaldehyde and 2.15 g of 4-bromophenylhydrazide to 30 mL of methanol solution, and stir the resulting yellow suspension at room temperature for 2 h to obtain a novel multidentate ligand. Add 2 g of CuCl2 to the above solution, and stir the resulting solution for another 2 h.

[0057] Ⅱ. Weigh 10g of Norit rox 0.8 activated carbon washed with hydrochloric acid in a beaker, pour the above solution into the beaker containing activated carbon, stir and immerse for 6h, then dry in an oven at 100℃ for 12h. Cool and obtain Cu catalyst.

[0058] (2) Acetylene hydrochlorination reaction

[0059] 5 g of the catalyst prepared above was weighed and loaded into a fixed bed reactor (made of quartz glass) with an inner diameter of 10 mm. -1The catalyst was evaluated for acetylene hydrochlorination activity under the conditions of reaction temperature of 160°C and feed gas ratio of V(C2H2):V(HCl)=1:1.2. The acetylene conversion rate versus reaction time curve is shown in Figure 1 The curve of vinyl chloride selectivity changing with reaction time is shown in Figure 2 .

[0060] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a bimetallic complex catalyst for acetylene hydrochlorination, characterized in that: The preparation method comprises the following steps: at room temperature, mixing an aldehyde compound and an amine compound in a solvent, stirring them fully to react 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 the copper and cobalt elements contained in each, stirring the obtained mixture to react to generate a bimetallic complex, mixing the obtained reaction solution with an acid-washed activated carbon carrier, stirring and impregnating them fully, drying them, and cooling them to obtain a bimetallic complex catalyst for 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-bromobenzohydrazide.

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, the amine compound, the copper salt and the cobalt salt is 1-2.5:1-1.5:1-2:0.5-2, and the molar numbers of the copper salt and the cobalt salt are calculated based on the molar numbers of the copper element and the cobalt element contained therein.

4. The preparation method according to claim 1, characterized in that: The reaction was stirred at room temperature for 1-5 h to generate the multidentate ligand.

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 mass percentage of the copper element in the copper salt to the activated carbon is 9-20%.

7. The preparation method according to claim 1, characterized in that: The reaction was stirred at room temperature for 1-5 h to form the bimetallic complex.

8. The preparation method according to claim 1, characterized in that: The stirring and dipping time is 2-8h.

9. A bimetallic complex catalyst for acetylene hydrochlorination prepared according to the preparation method of any one of claims 1 to 8.

10. Use of the bimetallic complex catalyst as claimed in claim 9 in acetylene hydrochlorination reaction.

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