A copper-based catalyst, a preparation method and application thereof

Abstract

The application discloses a copper-based catalyst, a preparation method and application, relates to a copper-based catalyst used for catalyzing acetylene hydrochlorination reaction, and has the technical scheme as follows: a copper-based catalyst, a copper-based catalyst formula including coal-based activated carbon, a copper precursor and a ligand; the loading amount of copper elements in the copper-based catalyst formula is 8-16 wt%; the molar ratio of the metal copper precursor to the ligand is 10-25:1; and the rest is coal-based activated carbon.The copper-based catalyst has good dispersity and high activity.

Description

TECHNICAL FIELD

[0001] The present application relates to a copper-based catalyst for catalyzing the hydrochlorination of acetylene, and more particularly to a copper-based catalyst, a preparation method and an application thereof. BACKGROUND

[0002] Vinyl chloride is a monomer for the production of polyvinyl chloride (PVC), and the main production process of vinyl chloride is the hydrochlorination of acetylene. The catalyst traditionally used in this process is a supported HgCl2 / AC catalyst, which has the disadvantage of easy evaporation, which not only causes the loss of active components, but also causes harm to human health and the environment due to the loss of mercury elements. In Hutchings' prediction, the electrode potential is positively correlated with the catalytic performance of the hydrochlorination of acetylene, and Cu 2 has a higher electrode potential, and thus may have better catalytic performance for the hydrochlorination of acetylene. Compared with noble metals such as Au and Ru, Cu has good thermal stability and is inexpensive and easy to obtain, and thus as a substitute for noble metals, Cu has important research significance in the production process of PVC industry.

[0003] For copper-based catalysts for the hydrochlorination of acetylene, there are many different improvement schemes, such as a composite support Cu-based catalyst, which uses a precipitation method to load CeO2 on activated carbon to form a composite activated carbon, which can inhibit the generation of carbon deposition during the reaction, and can improve the interaction between the active component and the support, and prevent the loss of active components; a copper-based composite catalyst, which uses a Schiff base to pretreat the activated carbon support, and combines with an amino acid complex impregnation technology to prepare a copper-based composite catalyst, which realizes the nanoscale loading of Cu on the surface of the support, reduces the loss of Cu in the reaction, and slows down the grain growth; nitrogen-doped activated carbon as a support is treated, and an ionic liquid is added as an additive, the ionic liquid and copper salt are mixed to form an impregnation solution, and an equal-volume impregnation method is used to load the activated carbon, which can effectively improve the catalytic activity of the catalyst and reduce the industrial preparation cost of the catalyst; the traditional equal-volume impregnation method is combined with a high-voltage pulse electric field technology, and the interaction between the high-voltage pulse electric field of appropriate intensity and the charged particles in the preparation system can prepare a highly dispersed catalyst with high activity and good stability; a fluorine-containing weakly coordinated anion modified copper-based catalyst, which introduces a weakly coordinated anion into the copper-based catalyst, adjusts the electronic structure of the active center, and improves the activity and stability of the copper-based catalyst.

[0004] The current common preparation method for supported copper-based catalysts in the hydrochlorination of acetylene is to load copper precursors and additives on the support through impregnation under certain conditions. Although researchers have made some improvements to copper-based catalysts in recent years, there are still problems of catalyst deactivation caused by reasons such as weak interaction between the active component and the support, uneven dispersion of copper active species in the copper-based catalyst, and reduction of high-valence copper active species. SUMMARY

[0005] In order to solve the problems of uneven dispersion and easy agglomeration of copper-based catalysts in the background art, the present patent first provides a copper-based catalyst.

[0006] The above technical purpose of the present application is achieved by the following technical solution: a copper-based catalyst, the formula of the copper-based catalyst comprising coal-based activated carbon, a copper precursor and a ligand; the loading amount of copper element in the formula of the copper-based catalyst being 8-16wt%; the molar ratio of the copper precursor to the ligand being 10-25:1; and the remainder being activated carbon.

[0007] Further, the copper precursor is one of CuCl2, CuCl, CuSO4 and Cu(NO3)2; or one of the hydrates of CuCl2, CuCl, CuSO4 and Cu(NO3)2.

[0008] Further, the copper precursor is CuCl2·2H2O.

[0009] Further, the ligand is a compound containing a phosphorus-oxygen double bond and a cyclic molecular structure.

[0010] Further, the ligand is one of phenylphosphonic dichloride, 1-ethyl-3-methylimidazolium diethylphosphate, O-(diphenylphosphoryl)hydroxylamine, bis(2-oxo-3-oxazolidinyl)phosphinic chloride, and 2-chloro-2-oxo-1,3,2-dioxaphospholane.

[0011] Further, the ligand is bis(2-oxo-3-oxazolidinyl)phosphinic chloride.

[0012] Secondly, the present application provides a production method of a copper-based catalyst, which adopts the formula as described above, and comprises the following steps: mixing the copper precursor, the ligand and anhydrous ethanol, and stirring uniformly; adding coal-based activated carbon and continuing to stir uniformly; performing impregnation and heat activation, and then drying to obtain the copper-based catalyst.

[0013] Further, the method further comprises a pretreatment method of coal-based activated carbon, and the pretreatment method is as follows: refluxing and stirring 0.5-1.5mol / L hydrochloric acid configured in advance with 40-60 mesh coal-based activated carbon at 70℃ for 6-10h, washing to neutral with deionized water, and then drying in an oven at 100-120℃ for 10-12h.

[0014] Further, the impregnation and heat activation are performed by water bath heating, and the water bath temperature is 60-70℃.

[0015] The activation time is 5-7h.

[0016] Finally, the application provides the application of the copper-based catalyst in the preparation of chloroethylene by acetylene hydrochlorination reaction.

[0017] To sum up, the application has the following beneficial effects: the application provides a copper-based catalyst taking coal-based activated carbon as a carrier, CuCl2·2H2O as a stable-state metal precursor, and several compounds containing phosphorus-oxygen double bonds and cyclic molecular structures as ligands. The added ligands can help anchor the copper active species on the carrier and inhibit the agglomeration or loss of highly dispersed copper. In addition, the high-valence Cu active species is stabilized through electron transfer between the ligands with strong electron-donating ability and the metal precursor, which not only improves the adsorption capacity of the catalyst for the reactants hydrogen chloride and acetylene, but also inhibits the generation of carbon deposition during the reaction, thereby significantly improving the activity and stability of the catalyst. The prepared catalyst has the characteristics of low cost, high activity, and good stability when applied to the acetylene hydrochlorination reaction, and has good economic efficiency and industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a graph of the relationship between acetylene conversion rate and reaction time using the catalysts provided in Examples 1-5 and Comparative Example 1 under the conditions of Example 6.

[0019] Figure 2 is a graph of the relationship between chloroethylene selectivity and reaction time using the catalysts provided in Examples 1-5 and Comparative Example 1 under the conditions of Example 6.

[0020] Figure 3 is a TPD curve of the copper-based catalysts provided in Examples 1-5 and Comparative Example 1 for the reactant hydrogen chloride.

[0021] Figure 4 is a TPD curve of the copper-based catalysts provided in Examples 1-5 and Comparative Example 1 for the reactant acetylene.

[0022] Figure 5 is a transmission electron microscope (TEM) image of the copper-based catalyst provided in Example 1 DETAILED DESCRIPTION

[0023] In order to make the technical problems to be solved by the application, the technical solutions and beneficial effects more clear and explicit, the application will be further described in detail below in combination with the drawings and examples.

[0024] This example first provides a formula of a copper-based catalyst, including a carrier, a copper precursor, and a ligand.

[0025] The carrier is coal-based activated carbon (CAC).

[0026] The copper precursor is one of CuCl2, CuCl, CuSO4 and Cu(NO3)2; or one of the hydrates of CuCl2, CuCl, CuSO4 and Cu(NO3)2; preferably, the copper precursor is CuCl2·2H2O.

[0027] The ligand is one of phenyl phosphonic dichloride, 1-ethyl-3-methylimidazolium diethylphosphate, O-(diphenylphosphoryl)hydroxylamine, bis(2-oxo-3-oxazolidinyl)chlorophosphite, 2-chloro-2-oxo-1,3,2-dioxaphospholane; preferably, the ligand is bis(2-oxo-3-oxazolidinyl)chlorophosphite.

[0028] In the copper-based catalyst formula, the loading of copper element is 8-16 wt.%, preferably 12 wt.%. The calculation method of the loading of copper element is: m Cu / (m 载体 +m 铜前驱体 +m 配体 ); m Cu is the mass of copper element, m 载体 is the mass of carrier; m 铜前驱体 is the mass of copper precursor; m 配体 is the mass of ligand.

[0029] The molar ratio of copper precursor to ligand is 10-25:1; preferably, the molar ratio of copper precursor to ligand is 15:1.

[0030] Secondly, the embodiment provides a preparation method of the copper-based catalyst using the above formula, which comprises the following steps:

[0031] Coal-based activated carbon (CAC) pretreatment: method one, the activated carbon (CAC) is used as a carrier, and is purchased and used after pretreatment. The prepared 1 mol / L hydrochloric acid is refluxed and stirred with 40-60 mesh coal-based activated carbon at 70°C for 6h, and then washed with deionized water until neutral, and dried in an oven at 120°C for 12h. Method two, the coal-based columnar activated carbon (CAC) is pretreated. First, the coal-based columnar activated carbon (CAC) is washed with an acid solution (0.01-0.1 mol / L), and then dried at 140°C. The acid used is one or a mixture of two of hydrochloric acid, nitric acid and phosphoric acid. Then, the coal-based columnar activated carbon (CAC) is modified with a potassium salt and / or a tin salt, and then dried at 120°C. The potassium salt used is one of potassium chloride, potassium bromide, potassium sulfide and potassium azide. The tin salt used is one of tin chloride, tin sulfate and tin nitrate. Preferably, the method two is used for the pretreatment.

[0032] Mixing of raw materials: the coordination compound and the copper precursor are mixed with anhydrous ethanol, and then the coal-based activated carbon (CAC) is added and stirred uniformly at room temperature for 2h.

[0033] Catalyst activation: After the raw material is fully stirred, it is placed in a 60-70℃ water bath for 4-7h of closed constant temperature for impregnation activation.

[0034] Drying: The activated catalyst is dried at 70℃ for 12h to obtain a copper-based complex catalyst containing phosphorus complex.

[0035] Finally, the present embodiment also provides a method for preparing vinyl chloride by using the above copper-based catalyst for acetylene hydrochlorination reaction. The reaction method is as follows: the prepared copper-based catalyst is loaded into a fixed bed reactor, and acetylene and hydrogen chloride reaction gas are introduced, under the reaction conditions of 160℃, acetylene space velocity (GHSV) of 160h -1 , volume ratio of acetylene to hydrogen chloride of 1:1.12, and reaction for 24h.

[0036] The main reactions involved in the acetylene hydrochlorination reaction include:

[0037] Main reaction: C2H2+HCl→CH2=CHCl

[0038] Non-polymerization side reactions:

[0039] CH2=CHCl+HCl→CH3CHCl2

[0040] CH2=CHCl+HCl→CH2ClCH2Cl

[0041] Polymerization side reactions:

[0042] 2CH2=CHCl→CH2ClCH=CCl-CH3

[0043] 2C2H2→CH2=CH-C≡CH

[0044] Existing thermodynamic studies show that the above main reaction is greatly affected by the polymerization side reaction, and the non-polymerization side reaction has little effect on the main reaction. The above main and side reactions are exothermic reactions, but the heat effect of the polymerization side reaction is greater than that of the main reaction. Higher temperature is more conducive to inhibiting the polymerization side reaction (if the reaction temperature is too high, the polymerization product may deposit on the surface of the catalyst, forming carbon deposition, leading to catalyst deactivation), improving the selectivity of the main reaction and reducing carbon deposition, but at high temperature, the metal catalyst also has the problem of valence change deactivation. After considering the effects of temperature on the polymerization side reaction and catalyst reduction deactivation, the reaction temperature should be controlled at about 160℃.

[0045] The volume ratio of acetylene to hydrogen chloride is 1:1-2, preferably the volume ratio of acetylene to hydrogen chloride is 1:1.12.

[0046] The gas phase reaction is carried out in a fixed bed reactor, and the copper-based catalyst is loaded in the fixed bed reactor. The acetylene space velocity is controlled in the range of 90-720h-1 , preferably at 160 h -1 .

[0047] Example 1

[0048] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.2243 g of bis(2-oxo-3-oxazolidinyl) phosphorous chloride (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.5221 g of CAC was slowly added to the mixture and continue to stir for 2 h, then put into a 70 °C water bath pot, sealed and constant temperature for 6 h, finally dried in a 70 °C air drying oven for 12 h, to obtain a copper-based catalyst, named Cu-L1 / CAC.

[0049] Example 2

[0050] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.2329 g of 1-ethyl-3-methylimidazolium diethyl phosphate (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.5135 g of CAC was slowly added to the mixture and continue to stir for 2 h, then put into a 70 °C water bath pot, sealed and constant temperature for 6 h, finally dried in a 70 °C air drying oven for 12 h, to obtain a copper-based catalyst, named Cu-L2 / CAC.

[0051] Example 3

[0052] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.1756 g of O-(diphenylphosphoryl)hydroxylamine (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.5708 g of CAC was slowly added to the mixture and continue to stir for 2 h, then put into a 70 °C water bath pot, sealed and constant temperature for 6 h, finally dried in a 70 °C air drying oven for 12 h, to obtain a copper-based catalyst, named Cu-L3 / CAC.

[0053] Example 4

[0054] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.1718 g of phenylphosphonic dichloride (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.5746 g of CAC was slowly added to the mixture and continue to stir for 2 h, then put into a 70 °C water bath pot, sealed and constant temperature for 6 h, finally dried in a 70 °C air drying oven for 12 h, to obtain a copper-based catalyst, named Cu-L4 / CAC.

[0055] Example 5

[0056] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.1256 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.6208 g of CAC was slowly added to the mixture and continued to stir for 2 h, then put into a 70°C water bath pot and sealed constant temperature for 6 h, finally dried in a 70°C air drying oven for 12 h to obtain a copper-based catalyst, named Cu-L5 / CAC.

[0057] Comparative Example 1

[0058] In a 50 mL beaker, 2.2536 g (0.01322 mol) of CuCl2·2H2O was dissolved in 15 mL of anhydrous ethanol, then 0.1256 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (0.00088 mol) was added at room temperature, after stirring for 30 min, 4.6208 g of CAC was slowly added to the mixture and continued to stir for 2 h, then put into a 70°C water bath pot and sealed constant temperature for 6 h, finally dried in a 70°C air drying oven for 12 h to obtain a copper-based catalyst, named Cu-L5 / CAC.

[0059] The effects of the above catalysts were verified by the following examples.

[0060] Example 6

[0061] 5 mL of the catalyst prepared in Examples 1-5 and Comparative Examples 1-5 was respectively loaded into a fixed bed reactor, and acetylene and hydrogen chloride mixed reaction gas was passed, under the reaction conditions of a reaction temperature of 160°C, an acetylene space velocity (GHSV) of 160 h -1 -1.12, for 24 h, and the highest conversion rate (%) of acetylene, the conversion rate decrease amplitude (%) in 24 h, and the vinyl chloride (VCM) selectivity were detected.

[0062] The gas mixture entering the gas chromatograph was mainly acetylene and vinyl chloride, and sometimes extremely small amounts of 1,1-dichloroethane impurity gas was produced, which was calculated by peak area normalization method. Since the hydrogen chloride after the reaction was completely absorbed, the reaction volume in the system could be considered as a constant value, and the calculation methods of acetylene conversion rate (X A ) and vinyl chloride selectivity (S VC ) were as follows:

[0063] The calculation method of acetylene conversion rate was as follows: A = (Ψ A0 - Ψ A ) / Ψ A0 *100%, and the average value of three measurements was taken.

[0064] The VCM selectivity calculation method: S VC = Ψ VC / (I- Ψ A )*100%, taking the average of three measurements.

[0065] wherein, Ψ A0 , Ψ A and Ψ VC represent the volume fraction of acetylene in the raw gas, the volume fraction of residual acetylene in the product and the volume fraction of vinyl chloride in the product, respectively. The test results of the acetylene hydrochlorination reaction catalyzed by each catalyst are shown in Table 1.

[0066] Table 1. Performance of different catalysts in catalyzing acetylene hydrochlorination reaction

[0067]

[0068] As can be seen from Table 1, when the added ligand is bis(2-oxo-3-oxazolidinyl) phosphorous oxychloride, the copper-based catalyst Cu-L1 / CAC with a loading of 12 wt.% prepared has a catalytic activity obviously superior to other catalysts, and the conversion rate decreases relatively less at 24 h. This is because the addition of the ligand can help to anchor the copper active species on the support and inhibit the agglomeration or loss of highly dispersed copper metal. In addition, the high-valence Cu active species is stabilized by electron transfer between the ligand with strong electron-donating ability and the metal precursor, not only improving the adsorption capacity of the catalyst for the reactants hydrogen chloride and acetylene, but also effectively inhibiting the rapid deactivation caused by carbon deposition, copper active species agglomeration and loss during the reaction, thereby significantly improving the activity and stability of the catalyst.

[0069] Figure 1 is the acetylene conversion rate-reaction time relationship diagram of the catalysts provided in Examples 1-5 and Comparative Example 1 under the condition of Example 6; as can be seen from the figure, the acetylene conversion rate of the catalyst with the additive is higher.

[0070] Figure 2 is the vinyl chloride selectivity-reaction time relationship diagram of the catalysts provided in Examples 1-5 and Comparative Example 1 under the condition of Example 6; as can be seen from the figure, the vinyl chloride selectivity of the copper-based catalysts all reaches more than 90%.

[0071] Figure 3 is the TPD curve of the reactant hydrogen chloride of the copper-based catalysts provided in Examples 1-5 and Comparative Example 1. Figure 4 is the TPD curve of the reactant acetylene of the copper-based catalysts provided in Examples 1-5 and Comparative Example 1. As can be seen, the catalyst has a strong adsorption capacity for the reactants hydrogen chloride and acetylene, which is conducive to improving the activity and stability of the catalyst.

[0072] Figure 5 The active component of the catalyst prepared by the method of the embodiment 1 is uniformly dispersed on the carrier, more active sites are exposed, the adsorption capacity of the reactants hydrogen chloride and acetylene is enhanced, and the catalytic activity and stability of the catalyst are improved.

[0073] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for producing a copper-based catalyst, characterized by, The method comprises the following steps: Mixing copper precursor, ligand and anhydrous ethanol, and stirring uniformly; After adding coal-based activated carbon, continue to stir uniformly; After impregnation and heat activation, dry to obtain copper-based catalyst; The copper-based catalyst formula comprises coal-based activated carbon, copper precursor and ligand; The loading amount of copper element in the copper-based catalyst formula is 8-16wt%; the molar ratio of copper precursor to ligand is 10-25:1; and the rest is coal-based activated carbon; The copper precursor is CuCl2·2H2O; The ligand is bis(2-oxo-3-oxazolidinyl) chlorophosphine; The method further comprises a pretreatment method for coal-based activated carbon, which is as follows: First, acid washing with 0.01-0.1mol / L acid solution, drying at 140℃, then modifying with potassium salt and / or tin salt, drying at 120℃, the acid used is one or a mixture of two of hydrochloric acid, nitric acid and phosphoric acid, the potassium salt used is one of potassium chloride, potassium bromide, potassium sulfide and potassium azide; the tin salt is one of tin chloride, tin sulfate and tin nitrate.

2. The method of claim 1, wherein the copper-based catalyst is produced by: The impregnation and heat activation are performed by water bath heating; the water bath temperature is 60-70℃; and the activation time is 5-7h.

3. Application of the copper-based catalyst prepared by the production method of claim 1 in the preparation of vinyl chloride by acetylene hydrochlorination reaction.

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