An acetylene hydrochlorination liquid copper-based catalyst, a preparation method and application thereof

Abstract

The application provides an acetylene hydrochlorination reaction liquid copper-based catalyst and a preparation method and application thereof, and belongs to the field of chemical industry catalysis technology.The application obtains an acetylene hydrochlorination reaction liquid copper-based catalyst by uniformly mixing cuprous chloride, concentrated hydrochloric acid and a metal chloride.The copper-based catalyst exists in the form of a liquid complex in a reactor, has the advantages of high activity and good stability;and the copper-based catalyst belongs to a fluid catalyst, has good intermolecular heat transfer performance, is easy to replace and regenerate, and has no pressure drop problem between bed layers, uniform heat transfer and no local temperature too high phenomenon.The copper-based catalyst is used for catalyzing acetylene hydrochlorination reaction to prepare vinyl chloride, the reaction is carried out on the surface and / or inside of the liquid complex, the conversion rate of acetylene is greater than 98%, the by-product (mainly dichloroethane) is less than 0.5%, and the copper-based catalyst has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology in the chemical industry, specifically to a liquid copper-based catalyst for the acetylene hydrochlorination reaction, its preparation method, and its application. Background Technology

[0002] Polyvinyl chloride (PVC) is widely used in light industry, construction, agriculture, electronics, and daily life due to its low cost, high durability, and stable physicochemical properties. It was one of the earliest resins to be industrialized. PVC production methods are mainly divided into two routes based on the raw materials used: the ethylene method and the calcium carbide method. For my country, abundant coal resources make the calcium carbide method for synthesizing vinyl chloride into PVC more competitive. However, the mercuric chloride (HgCl2) catalyst currently used in the calcium carbide method of PVC production poses serious environmental and health risks.

[0003] In the research of mercury-free metal catalysts, noble metals (such as gold, platinum, palladium, etc.) possess high activity and stability, but their high cost makes industrial application difficult. Non-noble metals (such as copper, tin, bismuth, etc.), while inexpensive, have relatively poor activity and stability. To address this issue, research on copper-based catalysts has gradually become a hot topic. To improve the activity and stability of copper-based catalysts, various improvement schemes have been proposed, such as adding organophosphate ligands or oxygen-containing multidentate ligands. In 2018, Chinese patent CN108993596A disclosed "A copper complex catalyst for the acetylene hydrochlorination reaction and its preparation method," which increased the acetylene conversion rate by approximately 25% by complexing copper salts with organophosphate ligands; however, this catalyst exhibits poor stability, with a significant decrease in conversion rate after 9 hours of reaction. In 2020, Chinese patent CN107008465A disclosed "A copper-based catalyst with high activity and stability for the acetylene hydrochlorination reaction." This method uses copper salt as the active component and organic amine salt as a stabilizer to obtain a copper-based catalyst. The catalyst has high stability but only moderate catalytic effect. In 2021, Chinese patent CN112916049A disclosed "An oxygen-containing multidentate ligand-modified copper-based catalyst for the acetylene hydrochlorination reaction, its preparation method and application." This method improves the catalytic activity and stability of the copper-based catalyst by adding oxygen-containing multidentate ligands, achieving good catalytic activity at 130℃ and an acetylene space velocity of 40 h⁻¹. -1Under certain conditions, the acetylene conversion rate remains below 90%, failing to meet industrial requirements. In the same year, Chinese patent CN113171773A disclosed a method for preparing and applying a nanoporous copper catalyst for the acetylene hydrochlorination reaction. This method involves grinding Cu-Al alloy into fine particles, reacting them in NaOH solution, and drying to obtain a nanoporous copper catalyst for the acetylene hydrochlorination reaction, used in fixed-bed catalysis. In 2023, Chinese patent CN115430425A disclosed a highly stable copper-based catalyst for catalyzing the acetylene hydrochlorination reaction, its preparation and application. This method uses coconut shell activated carbon as a carrier, copper salt as the active component, and introduces a ligand containing electron-withdrawing groups to improve catalyst activity. In the same year, Chinese patent CN116764685A disclosed a copper-based catalyst, its preparation method and application. This method involves fixing copper precursors and ligands onto coal-based activated carbon to obtain a catalyst with good dispersibility and high activity. In 2024, Chinese patent CN115608359A disclosed "A copper catalyst and its preparation method and application," which uses activated carbon as a support to fix copper salts, organophosphorus compounds, and organic amines to obtain the catalyst. In addition, numerous publications, such as "Preparation and Application of Multi-component Copper-based Catalysts for Acetylene Hydrochlorination" (Chen Fangyong et al., Modern Chemical Industry, 2023, Vol. 43, No. 7, pp. 130-141) and "Evaluation of Industrial Application of Copper-based Catalysts in Acetylene Hydrochlorination Reaction" (Dai Yuanyuan et al., Modern Chemical Industry, 2025, Vol. 45, No. 1, pp. 72-76), have researched and reported on copper-based catalysts. Ultimately, all of the above research on copper-based catalysts involves using a support to fix copper salts and adding stabilizers to maintain the catalyst, all belonging to fixed-bed catalysis technology. Although fixed-bed catalysis technology is mature, it has the following drawbacks: 1) Catalyst preparation requires a high-quality support, which is complex and costly; 2) Fixed beds have poor heat transfer performance, and the fixed particles make it difficult for heat to dissipate, easily leading to localized high temperatures; 3) Fixed beds are prone to leakage, causing catalyst failure; 4) Catalyst replacement is difficult, requiring shutdown and reactor disassembly, affecting production efficiency; 5) The bed pressure drop is large, and the resistance is high when fluid passes through the dense catalyst bed, increasing energy consumption; 6) Localized overheating may occur, and excessively high local temperatures may cause catalyst deactivation or side reactions. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a liquid copper-based catalyst for the acetylene hydrochlorination reaction, its preparation method, and its application. The copper-based catalyst exists in the reactor as a liquid complex, unlike fixed-bed catalysts, and is therefore a fluid catalyst. Fluid catalysts have good intermolecular heat transfer performance and are easy to replace and regenerate. The copper-based catalyst has high activity and good stability, and because it is a fluid, there is no pressure drop between the bed layers, resulting in uniform heat transfer and preventing localized overheating. The acetylene hydrochlorination reaction takes place on the surface and / or inside the liquid complex. This copper-based catalyst achieves a conversion rate of acetylene greater than 98%, with byproducts (mainly dichloroethane) less than 0.5%.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a liquid copper-based catalyst for the acetylene hydrochlorination reaction, which is obtained by uniformly mixing cuprous chloride (CuCl), concentrated hydrochloric acid and a metal chloride.

[0007] The cuprous chloride is completely dissolved in concentrated hydrochloric acid, and Cu⁺ exists in the form of a soluble cupric chloride complex. The reaction equation is as follows:

[0008] CuCl + HCl = H[CuCl2] (chlorocopper acid complex).

[0009] Furthermore, the mass concentration of the concentrated hydrochloric acid is 36%~38% (corresponding to a molar concentration of approximately 11.6~12.4 mol / L).

[0010] Furthermore, the molar ratio (molar amount / volume) of cuprous chloride to concentrated hydrochloric acid is 0.5~2 mol / L. Excessive cuprous chloride dosage will increase viscosity, while insufficient dosage will result in inadequate catalytic activity.

[0011] Further, the metal chloride includes at least one selected from bismuth chloride (BiCl3), palladium chloride (PdCl2), ferric chloride (FeCl3), aluminum chloride (AlCl3), calcium chloride (CaCl2), and magnesium chloride (MgCl2). This invention significantly improves the performance of Cu by adding trace amounts of metal chloride to the cuprous chloride-concentrated hydrochloric acid catalyst system. + The stability of the catalyst significantly extends its recycling cycle.

[0012] Further, the mass ratio of the metal chloride to cuprous chloride is (0.01~0.2):1, more preferably (0.05~0.15):1, and even more preferably (0.08~0.12):1.

[0013] Secondly, the present invention provides a method for preparing the liquid copper-based catalyst for the acetylene hydrochlorination reaction, comprising the following steps: dissolving cuprous chloride in concentrated hydrochloric acid, adding a trace amount of metal chloride and mixing evenly to obtain the liquid copper-based catalyst for the acetylene hydrochlorination reaction.

[0014] Thirdly, this invention provides the application of the liquid copper-based catalyst in the catalytic hydrochlorination of acetylene to prepare vinyl chloride (VCM). In this application, the liquid copper-based catalyst is first activated by heating before being used in the acetylene hydrochlorination reaction. Before use, this invention activates the liquid copper-based catalyst to ensure that CuCl and concentrated hydrochloric acid react and dissolve fully, forming a homogeneous catalytic system to effectively exert its catalytic efficiency.

[0015] When the liquid copper-based catalyst prepared in this invention is used in the calcium carbide process for producing vinyl chloride, the Cu from cuprous chloride... + It can form a π-complex with acetylene, weakening the C≡C energy barrier, promoting the electrophilic addition of HCl, and effectively improving the conversion rate of acetylene. The reaction process is as follows:

[0016] (1) Cu + + C2H2 → [Cu(C2H2)] (a π-complex of copper and acetylene, i.e., activated acetylene);

[0017] (2) [Cu(C2H2)] + HCl → CH2=CHCl + Cu + .

[0018] The active center of the liquid copper-based catalyst for the acetylene hydrochlorination reaction provided by this invention is Cu⁺, and Cu⁺ is relatively easy to oxidize to Cu. 2+ To avoid degradation of catalyst performance, Cu content needs to be suppressed as much as possible during preparation, transportation, and use. 2+ The generation of Cu. According to the inventor's experiments, trace amounts of Cu were detected. 2+ It does not affect catalytic efficiency and allows for trace amounts of Cu. 2+ It exists, with a permissible concentration ≤10%; when Cu is detected 2+ Excessive amounts of Cu should be replenished immediately. + To ensure reaction efficiency.

[0019] Furthermore, the activation temperature is 60~110℃, and the time is 3~10 h.

[0020] Furthermore, the temperature of the acetylene hydrochlorination reaction is 90-110°C, and the space velocity is 40-400 h⁻¹. -1 .

[0021] Fourthly, the present invention provides an apparatus for catalytically preparing vinyl chloride using the liquid copper-based catalyst, comprising a preparation tank, a circulating pump, a graphite cooler, and a reaction tower; the preparation tank is used to prepare the liquid copper-based catalyst, and the prepared copper-based catalyst is sequentially transported to the reaction tower via the circulating pump and the graphite cooler to react with a mixture of acetylene and hydrogen chloride gas;

[0022] The graphite cooler cools the liquid copper-based catalyst, preventing Cu from precipitating during transport. + Oxidized to Cu 2+ The liquid copper-based catalyst is discharged from the graphite cooler, then heated and activated before being transported to the reaction tower.

[0023] Both the primary and secondary reaction towers are multi-layer plate towers to enhance the gas-liquid contact reaction effect. Furthermore, the bottom of the primary and secondary reaction towers is equipped with a catalyst collection outlet, which is connected to the inlet pipe of the catalyst circulation pump through an outlet return pipe to form a complete circulation loop, facilitating catalyst circulation and replenishment with fresh catalyst.

[0024] This invention utilizes a cuprous chloride-concentrated hydrochloric acid system to prepare a copper-based catalyst in a two-stage reactor (the reactor is made of graphite and uses a multi-layer plate tower). The copper-based catalyst exists as a liquid complex and catalyzes the electrophilic addition reaction of HCl to acetylene at 90-110℃ to obtain high-purity vinyl chloride synthesis gas. The heat generated is removed through a catalyst circulation heat exchanger (the circulation pump is made of polytetrafluoroethylene, and the graphite heat exchanger is cooled by hot water). During the reaction process of preparing vinyl chloride using the liquid copper-based catalyst, the Cu in the liquid copper-based catalyst... + It can form π-complexes with acetylene bonds, weakening the energy barrier of the acetylene bond and enhancing the electrophilic addition reaction of hydrogen chloride to acetylene, resulting in an acetylene conversion rate greater than 98% and byproducts (mainly dichloroethane) less than 0.5%; furthermore, the presence of trace amounts of metal chlorides can further stabilize Cu. + This significantly improves the stability of the catalyst. Compared to catalysts without added metal chlorides, the catalyst prepared by adding metal chlorides in this invention has a longer service life. Furthermore, during the reaction, the concentration of hydrochloric acid and the content of cuprous chloride are flexibly controlled and adjusted in a timely manner, and the oxygen content (<0.5% by volume) and water content (<0.006%) of the acetylene and hydrogen chloride mixture are strictly maintained to ensure efficient conversion of acetylene.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] (1) The preparation process of the cuprous chloride-concentrated hydrochloric acid system liquid copper-based catalyst provided by the present invention is simple, the active components are well dispersed, the catalytic activity is stable, it is not easily lost, and it can be cyclically adjusted and regenerated; its advantage lies in Cu+ It can form π-complexes with acetylene bonds, weakening the energy barrier of the acetylene bond, enhancing the electrophilic addition reaction of hydrogen chloride to acetylene, effectively improving the conversion rate of acetylene, and making it suitable for large-scale industrial applications.

[0027] (2) The cuprous chloride-concentrated hydrochloric acid system catalyst provided by the present invention is in liquid form and is suitable not only for normal reaction towers, but also for microchannel reactors and tubular reactors. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process flow for the hydrochlorination of acetylene using the liquid copper-based catalyst of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a liquid copper-based catalyst for the acetylene hydrochlorination reaction, which is obtained by uniformly mixing cuprous chloride (CuCl), concentrated hydrochloric acid, and a metal chloride.

[0031] In some examples, the mass concentration of the concentrated hydrochloric acid is 36% to 38% (corresponding to a molar concentration of approximately 11.6 to 12.4 mol / L).

[0032] In some examples, the molar ratio (molar amount / volume) of cuprous chloride to concentrated hydrochloric acid is 0.5~2 mol / L. Excessive cuprous chloride dosage will increase viscosity, while insufficient dosage will result in inadequate catalytic activity.

[0033] In some examples, the metal chloride includes at least one selected from bismuth chloride (BiCl3), palladium chloride (PdCl2), ferric chloride (FeCl3), aluminum chloride (AlCl3), calcium chloride (CaCl2), and magnesium chloride (MgCl2). The mass ratio of the metal chloride to cuprous chloride is (0.01~0.2):1.

[0034] The preparation method of the liquid copper-based catalyst for the acetylene hydrochlorination reaction includes the following steps: dissolving cuprous chloride in concentrated hydrochloric acid, adding a trace amount of metal chloride and mixing evenly to obtain the liquid copper-based catalyst for the acetylene hydrochlorination reaction.

[0035] This invention also provides the application of the liquid copper-based catalyst in the catalytic hydrochlorination of acetylene to prepare vinyl chloride (VCM). In application, the liquid copper-based catalyst is first activated by heating before being used in the acetylene hydrochlorination reaction.

[0036] In some examples, the activation temperature is 60–110 °C and the time is 3–10 h; the acetylene hydrochlorination reaction temperature is 90–110 °C and the space velocity is 40–400 h⁻¹. -1 .

[0037] The present invention also provides an apparatus for realizing the catalytic preparation of vinyl chloride using the liquid copper-based catalyst, such as... Figure 1 As shown, it includes a preparation tank, a circulating pump, a graphite cooler, and a reaction tower; the preparation tank is used to prepare the liquid copper-based catalyst, and the prepared copper-based catalyst is sequentially transported to the reaction tower through the circulating pump and the graphite cooler to react with a mixture of acetylene and hydrogen chloride gas;

[0038] The graphite cooler cools the liquid copper-based catalyst, preventing Cu from precipitating during transport. + Oxidized to Cu 2+ The liquid copper-based catalyst is discharged from the graphite cooler, then heated and activated before being transported to the reaction tower.

[0039] Both the primary and secondary reaction towers are multi-layer plate towers to enhance the gas-liquid contact reaction effect. Furthermore, the bottom of the primary and secondary reaction towers is equipped with a catalyst collection outlet, which is connected to the inlet pipe of the catalyst circulation pump through an outlet return pipe to form a complete circulation loop, facilitating catalyst circulation and replenishment with fresh catalyst.

[0040] Example 1

[0041] A liquid copper-based catalyst for the hydrochlorination of acetylene

[0042] 25 g of CuCl was mixed with 200 mL of 37% hydrochloric acid, and 0.25 g of PdCl2 was added. The mixture was then activated at 90 °C for 5 h to obtain a liquid copper-based catalyst. This liquid copper-based catalyst was then reacted with a mixture of acetylene and hydrogen chloride (acetylene to hydrogen chloride ratio 1:1) at 100 °C and a space velocity of 250 h⁻¹. -1 Vinyl chloride was prepared by reaction under the specified conditions. In this example, the conversion rate of acetylene was 99.2%, and the content of the byproduct dichloroethane (EDC) was 0.3%.

[0043] Example 2

[0044] A liquid copper-based catalyst for the hydrochlorination of acetylene

[0045] 25 g of CuCl was mixed with 200 mL of 37% hydrochloric acid, and 0.25 g of BiCl3 was added. The mixture was then activated at 90 °C for 5 h to obtain a liquid copper-based catalyst. This liquid copper-based catalyst was then reacted with a mixture of acetylene and hydrogen chloride (acetylene to hydrogen chloride ratio 1:1) at 100 °C and a space velocity of 250 h⁻¹. -1 Vinyl chloride was prepared by reaction under the specified conditions. In this example, the conversion rate of acetylene was 98.5%, and the content of the byproduct dichloroethane (EDC) was 0.4%.

[0046] If cupric chloride is used instead of cuprous chloride in this invention, the comparison is as follows:

[0047]

[0048] In the CuCl / HCl system of this invention, CuCl dissolves in concentrated hydrochloric acid to form a complex and can be recycled. While CuCl2 also dissolves in concentrated hydrochloric acid and exhibits catalytic activity, its selectivity is moderate, and Cu... 2+ This is already the highest oxidation state of copper ions and cannot be recycled. If you want to regenerate Cu... 2+ To Cu + It requires hydrogen reduction, which is costly.

[0049] The liquid copper-based catalyst of the present invention is compared with typical catalysts in the prior art as follows:

[0050]

[0051] In the table, the mercury catalyst was prepared in reference “Zhou Ying, Yang Qin, Luo Qin, et al. Research progress on low mercury catalyst for acetylene hydrochlorination [J]. Polyvinyl Chloride, 2011, 39(11):3”; the CuCl2 catalyst was prepared in reference “Wang Lu, Wang Fumin, Guo Chao, et al. Research progress on mercury-free catalyst for acetylene hydrochlorination [J]. Chemical Industry and Engineering Progress, 2012”.

[0052] As can be seen from the above, the liquid copper-based catalyst of the CuCl / HCl system of this invention has obvious selectivity advantages, low cost, and simple control, which is conducive to optimizing the control of the acetylene hydrochlorination process. It is expected to completely solve the mercury pollution problem in the current calcium carbide method of polyvinyl chloride production and has a bright application prospect.

[0053] In summary, this invention obtains a liquid copper-based catalyst for the hydrochlorination of acetylene by uniformly mixing cuprous chloride, concentrated hydrochloric acid, and a metal chloride. The copper-based catalyst exists as a liquid complex in the reactor, exhibiting advantages such as high activity and good stability. Furthermore, as a fluid catalyst, it possesses excellent intermolecular heat transfer performance, is easily replaceable and regenerated, and eliminates pressure drop issues between bed layers, ensuring uniform heat transfer and preventing localized overheating. When this copper-based catalyst is used to catalyze the hydrochlorination of acetylene to produce vinyl chloride, the reaction occurs on the surface and / or within the liquid complex, achieving an acetylene conversion rate greater than 98% and a byproduct (mainly dichloroethane) of less than 0.5%, demonstrating promising application prospects.

[0054] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A liquid copper-based catalyst for the hydrochlorination of acetylene, characterized in that, The mixture is obtained by uniformly mixing cuprous chloride, concentrated hydrochloric acid, and a metal chloride; the metal chloride includes at least one of bismuth chloride, palladium chloride, ferric chloride, aluminum chloride, calcium chloride, and magnesium chloride; the mass ratio of the metal chloride to cuprous chloride is (0.01~0.12):1; and the mass concentration of the concentrated hydrochloric acid is 36%~38%.

2. The liquid copper-based catalyst for the acetylene hydrochlorination reaction according to claim 1, characterized in that, The ratio of cuprous chloride to concentrated hydrochloric acid is 0.5~2 mol / L.

3. The method for preparing the liquid copper-based catalyst according to any one of claims 1-2, characterized in that, The process includes the following steps: dissolving cuprous chloride in concentrated hydrochloric acid, adding a trace amount of metal chloride and mixing thoroughly to obtain a liquid copper-based catalyst for the acetylene hydrochlorination reaction.

4. The application of the liquid copper-based catalyst according to any one of claims 1-2 in the catalytic hydrochlorination of acetylene to prepare vinyl chloride, characterized in that, The liquid copper-based catalyst is first activated before being used in the acetylene hydrochlorination reaction.

5. The application according to claim 4, characterized in that, The activation temperature is 60~110℃, and the time is 3~10h.

6. The application according to claim 4, characterized in that, The temperature for the acetylene hydrochlorination reaction is 90~110℃.

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