A process for the preparation of 1,2-dichloroethylene
By reacting acetylene and tetrachloroethane with a ruthenium catalyst supported on titanium dioxide, the complex and costly production of 1,2-dichloroethylene has been solved, achieving a low-cost and environmentally friendly preparation of 1,2-dichloroethylene and improving the yield and selectivity of the product.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG NORMAL UNIV
- Filing Date
- 2022-12-28
- Publication Date
- 2026-07-24
AI Technical Summary
Existing methods for producing 1,2-dichloroethylene are complex and costly, and the subsequent purification and separation of products are difficult. Existing methods require reactions in organic solvents, which increases the difficulty of separation.
1,2-Dichloroethylene is produced by reacting acetylene and tetrachloroethane in a ruthenium catalyst supported on titanium dioxide. The ruthenium loading in the catalyst is 0.5–5 wt%, the particle size is 0.5–10 nm, the reaction temperature is 250–450 °C, and the reaction is carried out in a fixed-bed reactor, thus avoiding the use of organic solvents.
It enables simple and low-cost production of 1,2-dichloroethylene with high atom economy, reduced emissions of waste, and is suitable for industrial applications, while improving product yield and selectivity.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of chloroolefin preparation technology, and more particularly to a method for preparing 1,2-dichloroethylene. Background Technology
[0002] Chlorinated alkenes are used as organic solvents and low-temperature extractants due to their low toxicity, volatility, and stable properties. Among them, trichloroethylene and tetrachloroethylene have been widely used over the past decade. However, in recent years, domestic and international studies have shown that the large-scale use of trichloroethylene and tetrachloroethylene will increase the greenhouse effect on Earth. Therefore, seeking environmentally friendly alternatives to trichloroethylene and tetrachloroethylene is of great practical significance.
[0003] Studies have shown that 1,2-dichloroethylene has properties similar to other halogenated hydrocarbons. It can be used as a solvent for paints, resins, rubber, and cellulose acetate, as well as a dry cleaning agent, insecticide, bactericide, anesthetic, low-temperature extractant, and refrigerant. It can also be used to formulate varnishes and rubber solutions. Moreover, it does not damage the atmosphere. Therefore, in today's world where environmental awareness is increasing, vigorously developing the production process of 1,2-dichloroethylene has significant economic and social benefits.
[0004] Existing methods for producing 1,2-dichloroethylene involve the dechlorination of 1,1,2,2-tetrachloroethane, or the cracking of 1,1,2-trichloroethane, selective chlorination of acetylene, and oxychlorination of dichloroethane. However, these processes are complex and costly. CN110054546B discloses a method for preparing dichloroethylene by the addition reaction of acetylene and chlorine, but this method requires the reaction to be carried out in an organic solvent, which complicates the subsequent purification and separation of the product. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing 1,2-dichloroethylene to solve the problem of the harshness of existing production methods.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0007] This invention provides a method for preparing 1,2-dichloroethylene, comprising the following steps:
[0008] Acetylene and tetrachloroethane are reacted in the presence of a catalyst to produce 1,2-dichloroethylene;
[0009] The catalyst comprises a ruthenium metal catalyst supported on titanium dioxide;
[0010] The catalyst has a ruthenium loading of 0.5–5 wt%.
[0011] Preferably, the average particle size of ruthenium in the catalyst is 0.5 to 10 nm.
[0012] Preferably, the reaction temperature is 250–450°C.
[0013] Preferably, the molar ratio of acetylene to tetrachloroethane is 0.5 to 2:1.
[0014] Preferably, the reaction is carried out in a fixed-bed reactor with a reaction space velocity of 50–5000 h⁻¹. -1 .
[0015] Preferably, the absolute pressure of the reaction is 0.1 to 1.0 atm.
[0016] Preferably, the method for preparing the ruthenium catalyst supported on titanium dioxide includes the following steps:
[0017] (1) RuCl3, organic solvent and polyvinylpyrrolidone were mixed and reacted to generate Ru metal nanoparticles;
[0018] (2) Disperse Ru metal nanoparticles in ethanol solvent and then impregnate them on TiO2 support to obtain a metal ruthenium catalyst supported on titanium dioxide.
[0019] Preferably, the concentration of Ru in the reaction mixture system of step (1) is 10 to 100 mmol / L, and the molar ratio of Ru to polyvinylpyrrolidone is 0.05 to 0.5:1.
[0020] Preferably, the reaction temperature in step (1) is 120–180°C.
[0021] This invention utilizes the reaction of acetylene and tetrachloroethane with a ruthenium catalyst on titanium dioxide to produce 1,2-dichloroethylene. The reaction is simple, the sources are widely available and inexpensive, resulting in low production costs. Furthermore, it produces no waste and is safe to operate, making it a clean production process. Moreover, since the raw materials used are acetylene and tetrachloroethane, the reaction also has high atom economy, which is conducive to its industrial application.
[0022] The present invention can adjust the yield and selectivity of 1,2-dichloroethylene by adjusting the particle size of Ru, the active center of the catalyst, and other specific operating parameters.
[0023] This invention can employ fixed-bed catalysis, avoiding the use of organic solvents and reducing the burden on subsequent product purification and separation. Detailed Implementation
[0024] This invention provides a method for preparing 1,2-dichloroethylene, comprising the following steps:
[0025] Acetylene and tetrachloroethane are reacted in the presence of a catalyst to produce 1,2-dichloroethylene;
[0026] The catalyst comprises a ruthenium metal catalyst (Ru / TiO2) supported on titanium dioxide;
[0027] The catalyst has a ruthenium loading of 0.5-5 wt%, preferably 1-4 wt%, and more preferably 2-3 wt%.
[0028] The 1,2-dichloroethylene obtained by the preparation method provided by the present invention comprises cis-1,2-dichloroethylene and trans-1,2-dichloroethylene.
[0029] In this invention, the average particle size of ruthenium in the catalyst is 0.5-10 nm, preferably 2-8 nm, and more preferably 4-6 nm.
[0030] In this invention, the reaction temperature is 250–450°C, preferably 300–400°C, and more preferably 340–380°C.
[0031] In this invention, the molar ratio of acetylene to tetrachloroethane is 0.5 to 2:1, preferably 1 to 1.5:1.
[0032] In this invention, the reaction is carried out in a fixed-bed reactor with a reaction space velocity of 50–5000 h⁻¹. -1 Preferably 500-4000h -1 Further preferably 2000-3000h -1 .
[0033] In this invention, the absolute pressure of the reaction is 0.1 to 1.0 atm, preferably 0.3 to 0.7 atm, and more preferably 0.5 to 0.6 atm.
[0034] In this invention, the method for preparing the ruthenium catalyst supported on titanium dioxide preferably includes the following steps:
[0035] RuCl3, an organic solvent and polyvinylpyrrolidone were mixed and reacted to generate Ru metal nanoparticles.
[0036] Ru metal nanoparticles were dispersed in an ethanol solvent and then impregnated on a TiO2 support to obtain a ruthenium catalyst supported on titanium dioxide.
[0037] In this invention, the concentration of Ru in the reaction mixture system is 10-100 mmol / L, preferably 20-80 mmol / L, and more preferably 40-60 mmol / L; the molar ratio of Ru to polyvinylpyrrolidone is 0.05-0.5:1, preferably 0.1-0.4:1, and more preferably 0.2-0.3:1; the organic solvent comprises ethylene glycol.
[0038] In this invention, the reaction temperature is 120–180°C, preferably 140–160°C; the reaction time is 2–6 h, more preferably 4–5 h.
[0039] In this invention, after the reaction is completed, the product is cooled, washed, and centrifuged to obtain Ru metal nanoparticles with a diameter between 0.5 and 10 nm.
[0040] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0041] Examples 1-7
[0042] Examples 1-7 relate to methods for preparing Ru / TiO2 catalysts, including the following steps:
[0043] A certain amount of RuCl3 was dissolved in ethylene glycol solvent, and a certain amount of polyvinylpyrrolidone (PVP) was added to it. The concentration of Ru in the solution, C(Ru), was controlled to be between 10 and 100 mmol / L, and the molar ratio of n(Ru) / n(PVP) was between 0.05 and 0.5. After stirring evenly, the mixture was refluxed in an oil bath at 120-180℃ for 2-6 hours. After cooling, washing, and centrifugation, Ru metal nanoparticles with a diameter between 0.5 and 10 nm were obtained.
[0044] Then, a certain amount of Ru metal nanoparticles were weighed and dispersed in ethanol solvent, and impregnated on TiO2 support to obtain Ru / TiO2 catalyst. Among them, catalyst A was obtained in Example 1, catalyst B was obtained in Example 2, catalyst C was obtained in Example 3, catalyst D was obtained in Example 4, catalyst E was obtained in Example 5, catalyst F was obtained in Example 6, and catalyst G was obtained in Example 7.
[0045] The Ru concentration, n(Ru) / n(PVP) molar ratio, reaction temperature, reaction time and Ru loading in each embodiment are shown in Table 1.
[0046] Table 1. Ru concentration, n(Ru) / n(PVP) molar ratio, reaction temperature, reaction time, and Ru loading in each example.
[0047]
[0048]
[0049] Examples 8-20 relate to a production process for 1,2-dichloroethylene, specifically including the following steps:
[0050] Acetylene and tetrachloroethane were mixed and then introduced into a catalyst bed at a certain temperature for catalytic reaction. The catalyst was Ru / TiO2 as described above. The reaction temperature, space velocity, n(acetylene) / n(tetrachloroethane) molar ratio and catalyst type are shown in Table 2.
[0051] Table 2. Reaction temperature, space velocity, n(acetylene) / n(tetrachloroethane) molar ratio, and catalyst type for each embodiment.
[0052]
[0053]
[0054] Comparative Example 1
[0055] This comparative example relates to a production process for 1,2-dichloroethylene. The difference between this comparative example and Example 4 is that no catalyst is added in this comparative example.
[0056] Comparative Example 2
[0057] This comparative example relates to a production process for 1,2-dichloroethylene. The difference between this comparative example and Example 12 is that the reaction temperature in this comparative example is 200°C.
[0058] Comparative Example 3
[0059] This comparative example relates to a production process for 1,2-dichloroethylene. The difference between this comparative example and Example 12 is that the reaction temperature in this comparative example is 480°C.
[0060] Comparative Examples 4-6
[0061] Comparative Examples 4-6 involve a production process for 1,2-dichloroethylene. The difference between Comparative Examples 4-6 and Example 12 is the different catalysts. The specific catalysts for each comparative example are shown in Table 3.
[0062] Table 3. Catalyst types for each comparative example
[0063]
[0064]
[0065] Test case
[0066] Products from each example and comparative example were collected. The reacted gas mixture was directly fed into an online gas chromatograph (GC) for quantitative analysis via a quantitative loop. The GC was equipped with an FID detector and a plot-Q capillary column. The products were qualitatively analyzed using gas chromatography-mass spectrometry (GC-MS), followed by quantitative analysis using GC. The selectivity of each product was calculated. An HP-5ms, 30m × 0.25mm × 0.25μm capillary column was used. Products in each example included cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, vinylidene chloride, trichloroethane, and trichloroethylene. The yield and selectivity of each product were calculated using the following formulas, where n is the amount of substance. The data results are recorded in Table 4.
[0067] Product yield:
[0068] Product selectivity:
[0069]
[0070] Table 4. Yields and selectivity of dichloroethylene in each example and comparative example
[0071]
[0072]
[0073]
[0074] As can be seen from the comparison of Examples 8 to 20, reaction temperature, space velocity, n(acetylene) / n(tetrachloroethane) molar ratio and catalyst type all affect the yield and productivity of dichloroethylene.
[0075] No dichloroethylene product was detected in Comparative Example 1, while the yields of dichloroethylene in Examples 8-20 were between 20% and 40%, indicating that dichloroethylene product could not be obtained without a catalyst.
[0076] No dichloroethylene product was detected in Comparative Example 2, while the yields of dichloroethylene in Examples 8-20 were between 20% and 40%, indicating that the catalyst activity was low and dichloroethylene product could not be obtained when the reaction temperature was below 250°C.
[0077] In Comparative Example 3, the selectivity for dichloroethylene was only 5%, indicating that when the reaction temperature is above 450℃, the product selectivity changes significantly, and dichloroethylene cannot be obtained with high selectivity.
[0078] In the product compositions of Comparative Examples 4–6, the selectivity for dichloroethylene was less than 5%, indicating that when other common metal catalysts are used, it is impossible to obtain dichloroethylene products with high selectivity.
[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing 1,2-dichloroethylene, characterized in that, It includes the following steps: Acetylene and tetrachloroethane are reacted in the presence of a catalyst to produce 1,2-dichloroethylene; The catalyst comprises a ruthenium metal catalyst supported on titanium dioxide; The catalyst contains 0.5-5 wt% ruthenium. The average particle size of ruthenium in the catalyst is 0.5~10 nm; The reaction is carried out in a fixed-bed reactor with a reaction space velocity of 800–5000 h⁻¹. -1 ; The method for preparing the ruthenium catalyst supported on titanium dioxide includes the following steps: (1) RuCl3, organic solvent and polyvinylpyrrolidone are mixed and reacted to generate Ru metal nanoparticles; (2) Disperse Ru metal nanoparticles in ethanol solvent and then impregnate them on TiO2 support to obtain a metal ruthenium catalyst supported on titanium dioxide.
2. The method for preparing 1,2-dichloroethylene according to claim 1, characterized in that, In the preparation of 1,2-dichloroethylene, the reaction temperature is 250~450℃.
3. The method for preparing 1,2-dichloroethylene according to claim 2, characterized in that, The molar ratio of acetylene to tetrachloroethane is 0.5 to 2:
1.
4. The method for preparing 1,2-dichloroethylene according to claim 1, characterized in that, In the preparation of 1,2-dichloroethylene, the absolute pressure of the reaction is 0.1~1.0 atm.
5. The method for preparing 1,2-dichloroethylene according to claim 1, characterized in that, In step (1), the concentration of Ru in the reaction mixture system is 10~100 mmol / L, and the molar ratio of Ru to polyvinylpyrrolidone is 0.05~0.5:
1.
6. A method for preparing 1,2-dichloroethylene according to claim 1 or 5, characterized in that, The reaction temperature in step (1) is 120~180℃.