Nacl modified Cu-na-dmf / ac catalyst and preparation method and application thereof

Abstract

The application discloses a NaCl modified Cu-Na-DMF / AC catalyst and a preparation method and application thereof. The NaCl modified Cu-Na-DMF / AC catalyst comprises a main catalyst, a ligand, a metal additive and a carrier. The main catalyst is copper chloride; the ligand is N,N-dimethylformamide; the metal additive is sodium chloride; and the carrier is coconut shell activated carbon. The NaCl modified Cu-Na-DMF / AC catalyst and the preparation method and application thereof have the advantages that the low coordination copper site induced by NaCl modification has superior catalytic activity, so that the NaCl modified Cu-DMF complex loaded on the carrier can significantly improve the stability of an acetylene dimerization catalyst system, the single-pass conversion rate of acetylene and the ethynyl acetylene selectivity are improved, the by-products in the reaction process are less, the content of acetylene polymer is greatly reduced, and then the separation difficulty and the production cost are reduced. Moreover, the catalyst has the advantages of mild preparation condition, simple process, short preparation period, low cost, and suitability for acetylene dimerization reaction.

Description

Technical Field

[0001] This invention belongs to the technical field of catalysts, specifically relating to a NaCl-modified Cu-Na-DMF / AC catalyst, its preparation method, and its applications. Background Technology

[0002] Chloroprene rubber (CR) is a versatile polymer material with excellent physical properties and stable chemical properties. Currently, the main methods for synthesizing CR are the butadiene method and the vinylacetylene method. With the continuous advancement of coal-to-acetylene technology, the development of coal-to-CR vinylacetylene processes has broad prospects. Simultaneously, vinylacetylene can be used in the production of chemical products such as benzene, dimethyl ethyl ketone, 4-chlorophthalic anhydride, and vinyl polymers, as well as many traditional petrochemical products, thereby effectively alleviating the current industrial dependence on the petrochemical industry. It is well known that the development of coal-based energy and chemical products is a mainstream trend and a crucial cornerstone for ensuring our energy security. Therefore, the efficient production of vinylacetylene is of great significance.

[0003] Acetylene dimerization to form MVA is a key step in acetylene-based processes for CR production. Nieuwland catalysts (NCs), composed of high-concentration aqueous solutions of CuCl and KCl / NH4Cl, are typical catalysts for acetylene dimerization. Recent research on NC-catalyzed acetylene dimerization has focused on solvent effects, ligand modification, metal additives, catalytic mechanisms, and reaction kinetics. Despite significant progress in these areas, low conversion rates, poor selectivity, and overpolymerization continue to hinder the effectiveness of NCs. Therefore, there is an urgent need for more stable and high-performance acetylene catalysts.

[0004] To improve catalytic activity and stability, a novel gas-solid acetylene dimerization system was developed. Previous research reported a highly efficient Cu-DMF / AC catalyst with a Cu-O coordination structure, exhibiting optimal catalytic performance in the gas-solid acetylene dimerization reaction. The introduction of the DMF ligand altered the electronic environment, enhancing the reducibility of Cu(II) and improving the dispersion of the active metal. However, these catalysts suffer from drawbacks such as low stability and short lifetime. The main causes of catalyst deactivation are the loss, aggregation, and carbon deposition of the active component, copper.

[0005] In view of this, the present invention proposes a new catalyst and its preparation method and application, which is a NaCl-modified Cu-Na-DMF / AC catalyst, which can overcome the problem of poor stability of acetylene dimerization to vinylacetylene by Cu-DMF / AC catalyst. Summary of the Invention

[0006] The purpose of this invention is to propose a NaCl-modified Cu-Na-DMF / AC catalyst, which exhibits strong activation ability for acetylene, high acetylene conversion rate, and high selectivity for vinylacetylene; at the same time, alkali metal modification can significantly improve the selectivity and stability of the catalyst.

[0007] To achieve the above objectives, the technical solution adopted is as follows:

[0008] A NaCl-modified Cu-Na-DMF / AC catalyst, comprising: a main catalyst, a ligand, a metal promoter, and a support;

[0009] The main catalyst is copper chloride;

[0010] The ligand is N,N-dimethylformamide;

[0011] The aforementioned metallic additive, sodium chloride;

[0012] The carrier is coconut shell activated carbon.

[0013] Furthermore, the molar ratio of the main catalyst to the ligand is 1:0.1-1.33.

[0014] Furthermore, the mass ratio of copper to support in the main catalyst is 5-25:100.

[0015] Furthermore, the molar ratio of copper to metal additive in the main catalyst is 1:0.1-1.

[0016] Furthermore, the coconut shell activated carbon is 60-80 mesh coconut shell activated carbon.

[0017] Another objective of this invention is to provide a method for preparing the above-mentioned Cu-Na-DMF / AC catalyst, which is simple and uses inexpensive materials.

[0018] To achieve the above objectives, the technical solution adopted is as follows:

[0019] The preparation method of the above-mentioned Cu-Na-DMF / AC catalyst includes the following steps:

[0020] (1) After the metal additive is fully dissolved in water, it is added to the carrier, stirred, and dried to obtain Na / AC material;

[0021] After dissolving the main catalyst in water, the ligand was added dropwise at 20-50℃, and the mixture was stirred until the main catalyst and the ligand were fully coordinated to obtain a complex solution.

[0022] (2) The Na / AC material is added to the complex solution, stirred, and the complex is uniformly loaded on the support. Then it is dried to obtain the Cu-Na-DMF / AC catalyst.

[0023] Furthermore, in step (1), stirring for 20-40 minutes allows the main catalyst and ligands to be fully coordinated;

[0024] In step (2), the drying process is as follows: first dry at 60-90℃ for 4-12 hours, then dry at 90-120℃ for 4-12 hours.

[0025] Furthermore, in step (1), the stirring speed is 300-700 rpm.

[0026] Another objective of this invention is to provide the application of the aforementioned Cu-Na-DMF / AC catalyst.

[0027] To achieve the above objectives, the technical solution adopted is as follows:

[0028] Application of the above-mentioned Cu-Na-DMF / AC catalyst or the Cu-Na-DMF / AC catalyst prepared by the above-mentioned preparation method in the synthesis of vinylacetylene.

[0029] Furthermore, the catalyst is added to the reactor, and then acetylene is introduced into the reactor. The acetylene undergoes a dimerization reaction to produce vinylacetylene. The reaction temperature in the reactor is 80-110°C, and the acetylene space velocity is 100-180 h⁻¹. -1 .

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] Compared with the large amounts of organic solvents and co-catalysts used in previous catalyst preparations, the preparation of Cu-Na-DMF / AC catalyst uses water as a solvent, DMF as a ligand, and sodium chloride as a metal promoter. The specific improvements are as follows:

[0032] 1. NaCl-modified copper-based catalysts facilitate the desorption of the target product MVA. Therefore, the addition of NaCl inhibits polymer formation and avoids polymer blockage of the gas path.

[0033] 2. NaCl-modified copper-based catalysts weaken the adsorption of C2H2, alter the electronic environment, and enhance the adsorption of Cu. 2+ The reducing properties of the Na improve the dispersibility of Cu. Therefore, the adsorption capacity of copper-based catalysts for C2H2 can be altered by adjusting the Na / Cu ratio.

[0034] 3. Modification with NaCl promotes the conversion of (Cu(DMF)2Cl2) to (Cu(DMF)2Cl2), significantly increasing the number of low-coordination catalytically active copper sites, thereby promoting the acetylene dimerization reaction.

[0035] 4. Modification with NaCl makes the entire catalytic system more stable and its catalytic activity higher. The conversion rate of acetylene, the single-pass yield of vinylacetylene, and the selectivity are all significantly improved.

[0036] In summary, compared with the large amounts of organic solvents and co-catalysts used in previous catalyst preparations, the Cu-Na-DMF / AC catalyst of this invention is inexpensive and environmentally friendly. Furthermore, NaCl modification of the Cu-DMF / AC catalyst significantly improves its stability, solving the problems of poor stability, severe copper loss, and severe carbon deposition associated with Cu-DMF / AC catalysts. Therefore, the acetylene dimerization process of this invention to vinylacetylene is a novel, efficient, stable, environmentally friendly, and economical synthetic method. Attached Figure Description

[0037] Figure 1 To demonstrate the performance of the catalyst prepared in the implementation case in catalyzing the dimerization of acetylene.

[0038] Figure 2 XAFS characterization of the catalyst prepared in the implementation case.

[0039] Figure 3 The catalyst prepared in the implementation case was characterized by FT-IR, XRD, BET, and XPS.

[0040] Figure 4 XPS, XRD, TG characterization and lifetime testing of the post-reaction catalyst prepared in the implementation case. Detailed Implementation

[0041] To further illustrate the NaCl-modified Cu-Na-DMF / AC catalyst, its preparation method, and its applications according to the present invention, and to achieve the intended objectives of the invention, the following detailed description, in conjunction with preferred embodiments, details the specific implementation methods, structures, features, and effects of the NaCl-modified Cu-Na-DMF / AC catalyst, its preparation method, and its applications. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0042] The following will provide a detailed description of the NaCl-modified Cu-Na-DMF / AC catalyst of the present invention, its preparation method, and its applications, with reference to specific embodiments:

[0043] To overcome the problems of complex processes, high production costs, and low single-pass conversion and selectivity of acetylene in the existing acetylene dimerization process, this invention provides a NaCl-modified Cu-Na-DMF / AC catalyst. This catalyst uses CuCl₂·2H₂O as the main catalyst, N,N-dimethylformamide (DMF) as the ligand, deionized water as the solvent, coconut shell activated carbon as the support, and alkali metals as metal promoters. Experiments show that the NaCl-modified Cu-Na-DMF / AC catalyst of this invention has strong activation ability for acetylene, and high acetylene conversion and selectivity for vinylacetylene; at the same time, alkali metal modification can significantly improve the selectivity and stability of the catalyst. Therefore, the acetylene dimerization reaction involving this catalyst can efficiently produce vinylacetylene.

[0044] The NaCl-modified Cu-Na-DMF / AC catalyst of this invention can be effectively used in the acetylene dimerization reaction, reducing production costs and improving production efficiency, thereby enabling the efficient preparation of vinylacetylene. The technical solution of this invention is as follows:

[0045] A NaCl-modified Cu-Na-DMF / AC catalyst, comprising: a main catalyst, a ligand, a metal promoter, and a support;

[0046] The main catalyst is copper chloride;

[0047] The ligand is N,N-dimethylformamide;

[0048] The aforementioned metallic additive, sodium chloride;

[0049] The carrier is coconut shell activated carbon.

[0050] Preferably, the molar ratio of the main catalyst to the ligand is 1:0.1-1.33.

[0051] Preferably, the mass ratio of copper to support in the main catalyst is 5-25:100.

[0052] Preferably, the molar ratio of copper to metal additive in the main catalyst is 1:0.1-1.

[0053] Preferably, the coconut shell activated carbon is 60-80 mesh coconut shell activated carbon.

[0054] The preparation method of the above-mentioned Cu-Na-DMF / AC catalyst includes the following steps:

[0055] (1) After the metal additive is fully dissolved in water, it is added to the carrier, stirred, and dried to obtain Na / AC material;

[0056] After dissolving the main catalyst in water, the ligand was added dropwise at 20-50℃, and the mixture was stirred until the main catalyst and the ligand were fully coordinated to obtain a complex solution.

[0057] (2) The Na / AC material is added to the complex solution, stirred, and the complex is uniformly loaded on the support. Then it is dried to obtain the Cu-Na-DMF / AC catalyst.

[0058] Preferably, in step (1), stirring for 20-40 minutes allows the main catalyst and ligands to be fully coordinated;

[0059] In step (2), the drying process is as follows: first dry at 60-90℃ for 4-12 hours, then dry at 90-120℃ for 4-12 hours.

[0060] Preferably, in step (1), the stirring speed is 300-700 rpm.

[0061] Application of the above-mentioned Cu-Na-DMF / AC catalyst or the Cu-Na-DMF / AC catalyst prepared by the above-mentioned preparation method in the synthesis of vinylacetylene.

[0062] Preferably, the catalyst is added to the reactor, and then acetylene is introduced into the reactor, whereby the acetylene undergoes a dimerization reaction to produce vinylacetylene. The reaction temperature in the reactor is 80-110°C, and the acetylene space velocity is 100-180 h⁻¹. -1 .

[0063] Example 1: Synthesis of supported Cu-Li-DMF / AC catalyst

[0064] The specific operating steps are as follows:

[0065] (1) First, 0.04 g of LiCl was dissolved in an aqueous solution. The temperature control system of the stirrer was adjusted to 30°C, and the stirring speed was 400 rpm until completely dissolved. Next, 4 g of coconut shell activated carbon was added to the mixture, and then the mixture was placed in a sealed beaker and magnetically stirred at 50°C for 12 hours. Subsequently, it was dried at 100°C overnight to obtain Li / AC material.

[0066] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30°C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate, thus obtaining a complex solution.

[0067] (3) After adding Li / AC to the complex solution in step (2) and stirring overnight, the resulting mixture was dried in a drying oven at 80°C for 12 hours. Subsequently, the temperature of the constant temperature drying oven was increased to 100°C and dried for another 12 hours. After cooling, the catalyst was obtained. The solid catalyst is represented as Cu-Li-DMF / AC.

[0068] Example 2: Synthesis of supported Cu-Na-DMF / AC catalyst

[0069] The specific operating steps are as follows:

[0070] (1) First, dissolve 0.05g NaCl in an aqueous solution. Adjust the temperature control system of the stirrer to 30℃ and the stirring speed to 400rpm until completely dissolved. Next, add 4g coconut shell activated carbon to the mixture, and then place the mixture in a sealed beaker and stir magnetically at 50℃ for 12 hours. Subsequently, dry at 100℃ overnight to obtain Na / AC material.

[0071] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30 °C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate. After adding Na / AC, stir overnight. Dry the resulting mixture in a drying oven at 80 °C for 12 h. Then, increase the temperature of the drying oven to 100 °C and continue drying for 12 h. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-Na-DMF / AC.

[0072] Example 3: Synthesis of supported Cu-K-DMF / AC catalyst

[0073] The specific operating steps are as follows:

[0074] (1) First, 0.06 KCl was dissolved in an aqueous solution. The temperature control system of the stirrer was adjusted to 30°C, and the stirring speed was 400 rpm until completely dissolved. Next, 4 g of coconut shell activated carbon was added to the mixture, and then the mixture was placed in a sealed beaker and magnetically stirred at 50°C for 12 hours. Subsequently, it was dried at 100°C overnight to obtain K / AC material.

[0075] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30°C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate, thus obtaining a complex solution.

[0076] (3) Add K / AC to the complex solution in step (2) and stir overnight. Dry the resulting mixture in a drying oven at 80°C for 12 hours. Then, increase the temperature of the constant temperature drying oven to 100°C and continue drying for 12 hours. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-K-DMF / AC.

[0077] Example 4: Synthesis of supported Cu-Mg-DMF / AC catalyst

[0078] The specific operating steps are as follows:

[0079] (1) First, 0.08 g of MgCl2 was dissolved in an aqueous solution. The temperature control system of the stirrer was adjusted to 30°C, and the stirring speed was 400 rpm until completely dissolved. Next, 4 g of coconut shell activated carbon was added to the mixture, and then the mixture was placed in a sealed beaker and magnetically stirred at 50°C for 12 hours. Subsequently, it was dried at 100°C overnight to obtain the Mg / AC material.

[0080] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30°C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate, thus obtaining a complex solution.

[0081] (3) Add Mg / AC to the complex solution in step (2) and stir overnight. Dry the resulting mixture in a drying oven at 80°C for 12 hours. Then, increase the temperature of the constant temperature drying oven to 100°C and continue drying for 12 hours. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-Mg-DMF / AC.

[0082] Example 5: Synthesis of supported Cu-Ca-DMF / AC catalyst

[0083] The specific operating steps are as follows:

[0084] (1) First, 0.10 CaCl2 was dissolved in an aqueous solution. The temperature control system of the stirrer was adjusted to 30°C, and the stirring speed was 400 rpm until completely dissolved. Next, 4 g of coconut shell activated carbon was added to the mixture, and then the mixture was placed in a sealed beaker and magnetically stirred at 50°C for 12 hours. Subsequently, it was dried at 100°C overnight to obtain the Ca / AC material.

[0085] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30°C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate, thus obtaining a complex solution.

[0086] (3) Add Ca / AC to the complex solution in step (2) and stir overnight. Dry the resulting mixture in a drying oven at 80°C for 12 hours. Then, increase the temperature of the constant temperature drying oven to 100°C and continue drying for 12 hours. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-Ca-DMF / AC.

[0087] Example 6: Synthesis of supported Cu-xNa-DMF / AC catalyst (x = 2, 3, 5, 7, indicating a molar ratio of Na to Cu of x:10)

[0088] The specific operating steps are as follows:

[0089] (1) Weigh 0.10 g, 0.15 g, 0.25 g, and 0.35 g of NaCl reagent into five beakers respectively, add a certain amount of deionized water, adjust the temperature control system of the stirrer to 30°C, and stir at 400 rpm until completely dissolved. Next, add 4 g of coconut shell activated carbon to each of the five beakers containing the mixed solution, then seal the beakers with plastic wrap and stir magnetically at 50°C for 12 hours. Subsequently, dry at 100°C overnight to obtain xNa / AC materials (x = 2, 3, 5, 7).

[0090] (2) Next, 1.47 g of CuCl2·2H2O and 10 mL of deionized water were added to a beaker equipped with a magnetic stir bar. The temperature control system of the stirrer was adjusted to 30°C and the stirring speed was 400 rpm to ensure that the copper chloride was fully dissolved. 0.64 g of N,N-dimethylformamide solution (DMF) was added dropwise to the beaker and stirred for 30 min to allow the copper chloride and DMF to fully coordinate, thus obtaining a complex solution.

[0091] (3) Add xNa / AC to the complex solution in step (2), stir overnight, dry the resulting mixture in a drying oven at 80°C for 12 hours, then raise the temperature of the constant temperature drying oven to 100°C and continue drying for 12 hours. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-xNa-DMF / AC (x = 2, 3, 5, 7).

[0092] Example 7: Synthesis of a supported Cu-Na-DMF / AC catalyst

[0093] The specific operating steps are as follows:

[0094] (1) First, dissolve 0.05g NaCl in an aqueous solution. Adjust the temperature control system of the stirrer to 30℃ and the stirring speed to 400rpm until completely dissolved. Next, add 2.19g coconut shell activated carbon to the mixture, and then place the mixture in a sealed beaker and stir magnetically at 50℃ for 12 hours. Subsequently, dry at 100℃ overnight to obtain Na / AC material.

[0095] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 20 °C and the stirring speed to 700 rpm to ensure that the copper chloride is fully dissolved. Add 0.06 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 20 min to allow the copper chloride and DMF to fully coordinate. After adding Na / AC, stir overnight. Dry the resulting mixture in a drying oven at 60 °C for 12 h, and then increase the temperature of the drying oven to 90 °C and continue drying for 12 h. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-Na-DMF / AC.

[0096] (3) In a fixed-bed microreactor, 2 mL (1.2 g) of the above catalyst was added to the acetylene dimerization reactor to carry out a gas-solid acetylene dimerization reaction. The reaction conditions were: reaction temperature 80℃, reaction pressure atmospheric pressure, and acetylene space velocity 100 h⁻¹. -1 .

[0097] Example 8: Synthesis of supported Cu-Na-DMF / AC catalyst

[0098] The specific operating steps are as follows:

[0099] (1) First, dissolve 0.05g NaCl in an aqueous solution. Adjust the temperature control system of the stirrer to 30℃ and the stirring speed to 400rpm until completely dissolved. Next, add 10.96g coconut shell activated carbon to the mixture, and then place the mixture in a sealed beaker and stir magnetically at 50℃ for 12 hours. Subsequently, dry at 100℃ overnight to obtain Na / AC material.

[0100] (2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 50 °C and the stirring speed to 300 rpm to ensure that the copper chloride is fully dissolved. Add 0.84 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 40 min to allow the copper chloride and DMF to fully coordinate. After adding Na / AC, stir overnight. Dry the resulting mixture in a drying oven at 90 °C for 4 h, and then increase the temperature of the drying oven to 120 °C and continue drying for 4 h. After cooling, the catalyst is obtained. The solid catalyst is represented as Cu-Na-DMF / AC.

[0101] (3) In a fixed-bed microreactor, 2 mL (1.2 g) of the above catalyst was added to the acetylene dimerization reaction apparatus to carry out a gas-solid acetylene dimerization reaction. The reaction conditions were: reaction temperature 110 °C, reaction pressure atmospheric pressure, and acetylene space velocity 180 h⁻¹. -1 .

[0102] Example 9:

[0103] The specific operating steps are as follows:

[0104] In a fixed-bed microreactor, the catalyst prepared in the examples was used to carry out acetylene dimerization. 2 mL (1.2 g) of the above catalyst was added to the acetylene dimerization reaction apparatus to carry out a gas-solid acetylene dimerization reaction. The reaction conditions were: reaction temperature 90°C, reaction pressure atmospheric pressure, and acetylene space velocity 120 h⁻¹. -1 Under these reaction conditions, the conversion rate of acetylene was 58.7%, and the selectivity of MVA was 91.4%. Finally, during the experiment, the gas mixture was injected into a gas chromatograph (Shimadzu, GC-2014C, GDX-301, and flame ionization detector) every 20 minutes to analyze its composition. The products obtained from the acetylene dimerization reaction were quantitatively analyzed using the calibrated area normalization method. The acetylene conversion rate (X) and MVA selectivity (S) were used as standards to evaluate the performance of the copper-based catalyst in catalyzing the acetylene dimerization reaction. The main product of the acetylene dimerization gas-solid phase catalytic system was MVA, with byproducts including DVA and 2-chloro-1,3-butadiene, as well as unreacted acetylene. The formulas for calculating the acetylene conversion rate and MVA selectivity are as follows:

[0105] X=[(2α2+2α3+3α4) / (α1+2α2+2α3+3α4)×100%

[0106] S=[2α2 / (α1+2α2+2α3+3α4)×100%

[0107] Wherein, α1, α2, α3, and α4 are the volume fractions of C2H2, MVA, 2-chloro-1,3-butadiene, and 1,5-hexadien-3-yne (DVA) in the gaseous products, respectively. The level of X indicates the amount of reactants in the products; a higher C2H2 conversion rate indicates a greater consumption of C2H2. S measures the amount of the target product MVA generated; a higher MVA selectivity indicates the greater amount of MVA produced in the reaction.

[0108] Example 10.

[0109] Previous studies have shown that the use of DMF ligands significantly improves the conversion and selectivity of acetylene dimerization catalyzed by CuCl2 / AC catalysts; however, problems such as insufficient catalyst stability have emerged. This example presents the following experiments, and the results are as follows: Figure 1 As shown, Figure 1 The changes in C2H2 conversion, MVA selectivity, and MVA time-yield for all catalysts as a function of process time (TOS) are shown.

[0110] (1) Metallic additives:

[0111] ① Literature review revealed that adding alkali metals, alkaline earth metals, Cr, Co, and other promoters to copper catalysts can improve catalyst activity, extend catalyst lifespan, and inhibit copper loss. Therefore, the catalytic performance of other second-metal modified Cu-DMF catalysts was evaluated using the method in Example 9, and the results are as follows: Figure 1 As shown in ac.

[0112] The specific operating steps are as follows:

[0113] To improve the stability of the catalyst, a variety of second metal-modified Cu-DMF catalysts were prepared by distributed impregnation method, such as Cu-1Co-DMF / AC, Cu-1Fe-DMF / AC, Cu-1Na-DMF / AC, Cu-1La-DMF / AC, Cu-1Ni-DMF / AC, and Cu-1Zn-DMF / AC, where "1" refers to a molar ratio of the second metal to copper of 1:10.

[0114] 1) First, equal molar amounts of Co, Fe, Na, La, Ni, and Zn chlorides were dissolved in aqueous solutions. The temperature control system of the stirrer was adjusted to 30°C, and the stirring speed was 400 rpm until completely dissolved. Next, 4 g of coconut shell activated carbon was added to the mixture, and then the mixture was placed in a sealed beaker and magnetically stirred at 50°C for 12 hours. Subsequently, it was dried overnight at 100°C to obtain Co / AC, Fe / AC, Na / AC, La / AC, Ni / AC, and Zn / AC materials.

[0115] 2) Add 1.47 g of CuCl2·2H2O and 10 mL of deionized water to a beaker equipped with a magnetic stir bar. Adjust the temperature control system of the stirrer to 30°C and the stirring speed to 400 rpm to ensure that the copper chloride is fully dissolved. Add 0.64 g of N,N-dimethylformamide solution (DMF) dropwise to the beaker and stir for 30 min to allow the copper chloride and DMF to fully coordinate. Add Co / AC, Fe / AC, Na / AC, La / AC, Ni / AC, and Zn / AC materials respectively and stir overnight. Dry the resulting mixture in a drying oven at 80°C for 12 h, and then increase the temperature of the drying oven by 100°C and continue drying for 12 h. After cooling, the catalyst is obtained. The solid catalysts are represented as Cu-1Co-DMF / AC, Cu-1Fe-DMF / AC, Cu-1Na-DMF / AC, Cu-1La-DMF / AC, Cu-1Ni-DMF / AC, and Cu-1Zn-DMF / AC.

[0116] Figure 1 As shown in (a)-(c), the addition of auxiliary elements such as alkali metals, alkaline earth metals, chromium, and cobalt to copper-based catalysts can improve their catalytic activity and extend their lifespan. Alkali metal-based copper catalysts exhibited almost identical catalytic selectivity for vinylacetylene, with an MVA selectivity reaching 84% within 10 hours. However, the Cu-Ni-DMF / AC and Cu-Co-DMF / AC catalysts showed poorer activity, with acetylene conversion rates of only about 45% and 48%, respectively, within 10 hours. Interestingly, the Cu-Na-DMF / AC catalyst achieved an acetylene conversion rate of approximately 56% within 10 hours. Therefore, the enhancement of catalyst performance was most significant when the second metal was an alkali metal.

[0117] ② The catalytic performance of the Cu-DMF catalysts in Examples 1-5 was evaluated using the method in Example 7, and the results are as follows: Figure 1 As shown in df.

[0118] The acetylene dimerization activity of various alkali metals on copper-based catalysts was studied, such as Figure 1 As shown in (d)-(f), the catalytic performance decreased significantly when the second metal was Mg or Ca. When the second metal was Li or K, the catalyst showed significant deactivation after 10 hours of reaction. The results indicate that the addition of sodium chloride as an alkali metal compound enhances the catalyst's activity and stability.

[0119] (2) Optimize the amount of sodium chloride added

[0120] The catalyst prepared in Example 6 was evaluated for its catalytic performance using the method described in Example 7, and the results are as follows: Figure 1 As shown in gi.

[0121] The results showed that the undoped Na Cu-DMF / AC catalyst exhibited very low catalytic activity, with a C2H2 conversion of only 30% and an MVA selectivity of only 56% after 20 h of reaction. Conversely, the Cu-2Na / AC catalyst with appropriate Na content showed significantly improved performance, achieving a C2H2 conversion of 58.7% and an MVA selectivity of 91.4%. Notably, Cu-2Na-DMF / AC demonstrated excellent performance, with a maximum MVA yield of 53.6%. The maximum selectivity of all samples from Cu-DMF / AC to Cu-7Na-DMF / AC also showed a trend of first increasing and then decreasing with increasing Na doping content. This indicates that adding an appropriate amount of Na to Cu-based catalysts can promote MVA formation, while excessive Na content hinders its activity. Therefore, there is a non-linear correlation between catalyst activity and Cu content.

[0122] Example 11: Characterization of Synchrotron Radiation

[0123] The 12-BM Advanced Photon Source at Argonne National Laboratory was used for transmission mode (fluorescence mode) X-ray absorption spectroscopy (XAS) observations of the XX-edge. Data from XAS and EXAFS were analyzed using Athena and Artemis software.

[0124] To further investigate the effect of Na on Cu speciation, X-ray absorption spectroscopy analysis was performed on Cu-DMF / AC and Cu-Na-DMF / AC catalysts to determine the coordination and reducing properties of copper. Figure 2 (a) shows the XANES spectra of Cu-DMF / AC and Cu-Na-DMF / AC catalysts at the Cu K-edge. They exhibit similar spectra, indicating that the valence state of Cu is close to +2. Similarly, the leading-edge peak at 8977 eV is attributed to dipole-forbidden Cu. 2+ The 1s→3d electron transition, with the shoulder peak at 8986 eV originating from Cu 2+ 1s→4p transition. The shoulder peak at 8983.3 eV is Cu. + The 1s→4p transition indicates that, in addition to Cu 2+ In addition to the species, a small amount of Cu also exists. + Yes. Furthermore, the oscillation curves of Cu-DMF / AC and Cu-Na-DMF / AC catalysts differ from those of copper foil, but agree well with the oscillation curves of CuCl2 and Cu(OH)2 catalysts. Figure 2 (b) This further demonstrates their similar central atom coordination environments. Then, curve fitting was performed on the R-space experimental results of Cu Kedge EXAFS to quantitatively analyze the differences in the local environment of each catalyst. The results are shown in Table 1.

[0125] Table 1. Cu K-edge parameters fitted by EXAFS for various samples.

[0126]

[0127] Comparison of copper foil, Cu(OH)2 and CuCl2 standard samples ( Figure 2 (c)-(g)) reveals that the sample peaks contain Cu-N / O and Cu-Cl signals. The peak at (without phase correction) is attributed to the scattering path of the Cu-O bond. The peak at (without phase correction) is attributed to the scattering path of the Cu-Cl bond. Notably, the coordination numbers of Cu-O / N and Cu-Cl in the Cu-DMF / AC catalyst are 3.8 ± 0.6 and 1.8 ± 0.4, respectively, while those in the Cu-Na-DMF / AC catalyst are 2.8 ± 0.2 and 1.3 ± 0.1, respectively. Compared to the Cu-DMF / AC catalyst, the coordination numbers and bond lengths of Cu-N and Cu-Cl in the Cu-Na-DMF / AC catalyst are reduced to varying degrees. These results indicate that Na modification significantly increases the number of low-coordination catalytically active copper sites. In previous studies, we determined the structure of the catalytically active material in the Cu-DMF / AC catalyst to be Cu(DMF)₂Cl₂. Therefore, the introduction of Na can increase the number of active sites on the Cu-DMF / AC catalyst, thereby promoting the dimerization of acetylene.

[0128] To further investigate the atomic dispersion of Cu in Cu-DMF / AC and Cu-Na-DMF / AC catalysts, wavelet transform (WT) was performed on CuK-edge EXAFS. Figure 2 The WT-EXAFS contour plots of Cu K-edge in (h)-(i) show that the k-axis position of the scattering center shifts to a lower value after the addition of Na. Combined with the above results, it can be concluded that the introduction of NaCl leads to an increase in the Cl ion concentration in the system, thus suppressing the Cu-Cl signal.

[0129] Example 12.

[0130] To provide evidence for the structure of the Cu-Na-DMF / AC catalyst and to gain a deeper understanding of its unusual catalytic performance, a series of physical characterizations were performed. The methods employed included:

[0131] Information about the functional groups on the catalyst surface can be obtained by testing with a Fourier Transform Infrared Spectrometer (FTIR), specifically the Thermo Nicolet Avatar 360.

[0132] X-ray photoelectron spectroscopy (XPS) was used to analyze the valence states and electronic structure characteristics of elements in catalysts, and to perform semi-quantitative analysis of the elemental composition of the catalyst surface. XPS analysis was performed using a Thermo ESCALAB 250XI spectrometer equipped with a monochromatic Al-Kα X-ray source at a power of 225 W. Detection results were based on a binding calibration using the C1s peak (284.6 eV). The elemental composition was determined using Thermo Vantage software based on the peak areas and sensitivity coefficients of the C1s, N 1s, O 1s, and Cu 2p peaks.

[0133] X-ray diffraction (XRD) was performed using a D8 ADVANCE instrument from Brüg GmbH, Germany, to record XRD data and analyze the crystal phase structure of the catalyst. The radiation source used was Cu Kα, the operating current was 40 mA, the voltage was 40 mV, and the 2θ angle range was between 10° and 90°.

[0134] The results are as follows Figure 3 As shown, we have:

[0135] (1) FTIR spectrum

[0136] The interaction between NaCl and Cu-DMF / AC was investigated using FT-IR spectroscopy. The FT-IR results showed that the addition of NaCl had a negligible effect on the O-Cu coordination bonds in the Cu-DMF / AC catalyst, but a more significant effect on the C=C content. Figure 3 (a)).

[0137] (2) XRD analysis

[0138] Figure 3 (b) shows the X-ray diffraction patterns of 10Na-DMF / AC and Cu-xNa-DMF / AC (x = 0, 1, 2, 5, 7). The diffraction peaks of the new catalyst at 2θ = 27.3°, 31.7°, 45.4°, 53.8°, 56.5°, 66.2°, and 75.3° correspond to the characteristic diffraction peaks of NaCl (JCPDS No. 05-0628). No characteristic peaks belonging to the Cu species were observed in the XRD curves of any of the catalysts, indicating that the Cu particles are smaller than the detection limit of XRD, or exist in an amorphous form with DMF. Figure 3 As shown in (c), all samples exhibited reversible Langmuir type IV isotherms and h1 type hysteresis loops, indicating that the Na-modified Cu-DMF / AC catalysts maintained macroporous and mesoporous structures.

[0139] (3) XPS spectroscopy

[0140] The surface Cu composition of the Cu-xNa-DMF / AC catalyst was analyzed using XPS. The XPS spectra are shown below. Figure 3 As shown in (d)-(f), C, N, O, Cl, Na, and Cu are the main components of Cu-xNa-DMF / AC. Curve fitting revealed that the peak at 932-935.5 eV was split into two peaks. The first main peak is located at 935.0 ± 0.1 eV, while the second smaller peak is located at 932.7 ± 0.1 eV. The higher-energy main peak (935.0 eV) can be attributed to Cu. 2+ The small peak at 932.7 eV is related to Cu. + The presence of metallic Cu(0) species may be related. Compared to Cu-DMF / AC catalysts, Cu-2Na-DMF / AC catalysts exhibit better Cu content. 2+ The relatively negative BE shift indicates that charge is transferred from Na metal to Cu. 2+ Transfer. This can be attributed to the interaction between Na and copper, where electrons transfer from Na to Cu, leading to an increase in the electron density at Cu sites.

[0141] Example 13.

[0142] The content of metal elements in the catalyst was determined by inductively coupled plasma atomic emission spectrometry (ICP-OES, Agilent 5110).

[0143] Previous work has shown that the loss of active components is the main cause of deactivation of Cu-DMF / AC catalysts in the acetylene dimerization reaction. Therefore, to investigate the effect of adding Na as a promoter on catalyst deactivation, the total copper content of fresh and used Cu-based catalysts was determined by ICP-OES (Table 2).

[0144] Table 2. Copper loading of catalysts as measured by ICP-OES

[0145]

[0146] Before the reaction, the Cu loadings of Cu-DMF / AC and Cu-2Na-DMF / AC catalysts were 9.33% and 9.35%, respectively. After 10 h of reaction, the Cu contents were 4.86% and 8.01%, respectively. Table 2 shows a significant change before and after the reaction; the Cu loss rates of Cu-DMF / AC and Cu-2Na-DMF / AC were 47.9% and 16.0%, respectively. The results indicate that the addition of Na as a promoter can suppress copper loss.

[0147] Example 14.

[0148] (1) Valence state changes of XPS active species

[0149] from Figure 4 (a) and Figure 4 (b) It can be seen that in the Cu-xNa-DMF / AC (x=1,2,3,5,7) catalysts used, Cu 2+ / Cu + The proportion of Cu changed significantly, which may explain why some Cu in the Cu-xNa-DMF / AC catalyst decreased as the reaction proceeded. 2+ Reduced to Cu by acetylene + or Cu 0 The reason is that as the Na / Cu ratio increases, the catalyst's adsorption capacity for acetylene gradually weakens, leading to Cu... 2+ / Cu + The molar ratio increases. Furthermore, as the Na content increases from Cu-DMF / AC to Cu-7Na-DMF / AC, Cu... 2+ / Cu + The ratio first increased from 35.0% to 65.0%. Therefore, based on the results of acetylene conversion and Cu2p 3 / 2XPS data analysis revealed appropriate Cu + / Cu 2+ Molar ratio can improve catalytic performance.

[0150] Figure 4 (c) The diffraction peaks of CuCl (JCPDS 06-0344) are shown to be those of Cu-DMF / AC at 2θ values ​​of 28.49°, 32.92°, 47.43°, and 56.28°. Notably, in Cu-xNa-DMF / AC (x=1,2,3,5,7), no reflection peaks of CuCl (JCPDS 06-0344) were detected except for the amorphous diffraction peaks of NaCl (JCPDS no. 05-0628). The XRD pattern results indicate that the addition of appropriate NaCl to the Cu-based catalyst can effectively suppress the aggregation of cuprous chloride and promote the dispersion of Cu on the AC support.

[0151] (2) TG test of catalyst carbon deposits after reaction

[0152] The samples were analyzed using a TA TGA5500 thermogravimetric analyzer (TG) to determine the amount of coke deposited on the catalyst (in air atmosphere). The heating rate was 10 °C / min, and the temperature was increased from 25 °C to 800 °C.

[0153] The carbon deposition on the catalyst was determined by thermogravimetric analysis, and the results are as follows: Figure 4As shown in (d)-(e), both Cu-DMF / AC and Cu-2Na-DMF / AC catalysts exhibited four distinct stages during the weight loss process. Below 104 °C, the initial weight loss is likely attributed to the desorption of adsorbed water. Therefore, the weight loss in the temperature range of 104–241 °C can be attributed to the vaporization of DMF. The surface carbon deposition rate of the Cu-DMF / AC catalyst was approximately 9.6%, while that of the Cu-2Na-DMF / AC catalyst was only about 2.1%, indicating that the addition of NaCl during the reaction effectively prevents carbon deposition. The catalyst lifetime test results are as follows... Figure 4 As shown in (f). Activity test results indicate that adding appropriate amounts of NaCl to the Cu-DMF / AC catalyst can effectively improve the catalyst lifetime.

[0154] The highly selective dimerization of acetylene to monoacetylene oxide (MVA) under continuous flow-fixed bed microreactor conditions is significant but also challenging. The gas-solid acetylene dimerization reaction provides a simple and effective method for preparing MVA under mild conditions, but the Cu-DMF / AC catalyst suffers severe deactivation during the reaction.

[0155] This invention relates to a NaCl-modified Cu-Na-DMF / AC catalyst and its preparation method. The catalyst uses CuCl₂·2H₂O as the main catalyst, DMF as the ligand, deionized water as the solvent, NaCl as the metal promoter, and coconut shell activated carbon as the support. The catalyst preparation steps are as follows: NaCl is fully dissolved in deionized water, then coconut shell activated carbon is added to the mixed solution, stirred, and dried to obtain the Na / AC material. Next, CuCl₂·2H₂O is fully dissolved in deionized water, then N,N-dimethylformamide solution is added dropwise, followed by the addition of the Na / AC material to the mixed solution, stirred, and dried to obtain the NaCl-modified Cu-Na-DMF / AC catalyst.

[0156] This invention prepares a NaCl-modified Cu-Na-DMF / AC catalyst using an impregnation method, exhibiting excellent performance. Compared with the Cu-DMF / AC catalyst, the catalyst shows significantly improved activity and stability. The addition of NaCl can inhibit the loss of copper from the catalyst and increase the number of low-coordination active sites.

[0157] As demonstrated in the embodiments, the present invention establishes a correlation between experimental measurements and theoretical simulations, proving that the low-coordination copper sites induced by NaCl modification possess superior catalytic activity. The NaCl-modified Cu-DMF complex of the present invention, when supported on a carrier, significantly improves the stability of the acetylene dimerization catalyst system, simultaneously enhancing both the acetylene single-pass conversion and vinylacetylene selectivity. It also reduces byproducts and the content of acetylene polymers during the reaction, thereby lowering the difficulty of separation and production costs. Furthermore, the catalyst prepared according to the present invention features mild preparation conditions, a simple process, a short preparation cycle, and low cost, making it suitable for acetylene dimerization reactions.

[0158] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A NaCl-modified Cu-Na-DMF / AC catalyst, characterized in that, The Cu-Na-DMF / AC catalyst comprises: a main catalyst, a ligand, a metal promoter, and a support; The main catalyst is copper chloride; The ligand is N,N-dimethylformamide; The aforementioned metallic additive, sodium chloride; The carrier is coconut shell activated carbon; The molar ratio of copper to metal additive in the main catalyst is 1:0.1-1.

2. The Cu-Na-DMF / AC catalyst according to claim 1, characterized in that, The molar ratio of the main catalyst to the ligand is 1:0.1-1.

33.

3. The Cu-Na-DMF / AC catalyst according to claim 1, characterized in that, The mass ratio of copper to support in the main catalyst is 5-25:

100.

4. The Cu-Na-DMF / AC catalyst according to claim 1, characterized in that, The coconut shell activated carbon mentioned is 60-80 mesh coconut shell activated carbon.

5. The method for preparing the Cu-Na-DMF / AC catalyst according to claim 1, characterized in that, Includes the following steps: (1) After the metal additive is fully dissolved in water, it is added to the carrier, stirred, and dried to obtain Na / AC material; After dissolving the main catalyst in water, the ligand was added dropwise at 20-50℃ and stirred until the main catalyst and ligand were fully coordinated to obtain a complex solution. (2) The Na / AC material is added to the complex solution, stirred, and the complex is uniformly loaded on the support. Then it is dried to obtain the Cu-Na-DMF / AC catalyst.

6. The preparation method according to claim 5, characterized in that, In step (1), stirring for 20-40 minutes allows the main catalyst and ligands to be fully coordinated; In step (2), the drying process is as follows: first dry at 60-90℃ for 4-12 hours, then dry at 90-120℃ for 4-12 hours.

7. The preparation method according to claim 5, characterized in that, In step (1), the stirring speed is 300-700 rpm.

8. The use of the Cu-Na-DMF / AC catalyst according to any one of claims 1-4 or the Cu-Na-DMF / AC catalyst prepared by the preparation method according to any one of claims 5-7 in the synthesis of vinylacetylene.

9. The application according to claim 8, characterized in that, A catalyst is added to the reactor, and then acetylene is introduced into the reactor. The acetylene undergoes a dimerization reaction to produce vinylacetylene. The reaction temperature in the reactor is 80-110℃, and the acetylene space velocity is 100-180 h⁻¹. -1 ; The catalyst is the Cu-Na-DMF / AC catalyst according to any one of claims 1-4 or the Cu-Na-DMF / AC catalyst prepared by the preparation method according to any one of claims 5-7.

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