Preparation method of supported modified gold catalyst and application of supported modified gold catalyst in acetylene hydrochlorination reaction
By modifying the gold-trimethylsulfur iodide complex, optimizing the ionic liquid with sterically hindered methylthionium iodide and weakly coordinating anions, and loading it onto nitrogen-doped porous carbon, the stability and temperature window issues of the gold catalyst in the acetylene hydrochlorination reaction were solved, achieving highly efficient catalytic performance.
Patent Information
- Application Number
- CN202511803361.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-03
AI Technical Summary
Existing gold-trimethylsulfur iodide (Au-(CH3)3SI) complex catalysts have drawbacks in the acetylene hydrochlorination reaction, such as poor high-temperature stability, coordination competition, and a narrow reaction temperature window.
Highly sterically hindered methylthionium iodide was used to replace trimethylthionium iodide. The melting point and viscosity of the modified sterically hindered ionic liquid were optimized by combining it with weakly coordinating anions. The gold precursor and the modified thionium salt were loaded onto nitrogen-doped porous carbon. The nitrogen species were used as anchoring sites to enhance the interaction with gold and prevent the migration and aggregation of gold nanoparticles.
This improved the stability of the catalyst and the temperature window of the catalytic reaction, maintained high catalytic activity, and avoided the risk of reduced catalytic activity.
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Figure CN121588907A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of green catalyst technology, specifically to a method for preparing a supported modified gold catalyst and its application in the hydrochlorination reaction of acetylene. Background Technology
[0002] Polyvinyl chloride (PVC), polymerized from vinyl chloride monomer, is one of the world's five major general-purpose plastics. Given my country's energy structure—rich in coal but poor in oil—the acetylene process has become the primary method for producing vinyl chloride monomer. In the industrial production of vinyl chloride using the acetylene process, the catalyst used for the acetylene hydrochlorination reaction is activated carbon-supported mercuric chloride. Because mercuric chloride is highly toxic and extremely volatile, it poses a serious threat to the environment and human health. Therefore, the development of mercury-free catalysts is urgently needed.
[0003] The development of mercury-free catalysts mainly focuses on two aspects: solid-phase mercury-free catalysts and liquid-phase mercury-free catalysts. The gas-solid heterogeneous reaction system is an important part of the acetylene hydrochlorination reaction, generally carried out in a fixed-bed reactor. The reactant gases acetylene and hydrogen chloride are preheated and mixed before entering the fixed-bed reactor containing the catalyst for an addition reaction to produce vinyl chloride. Research on solid-phase mercury-free catalysts mainly focuses on the following aspects: single-metal catalysts, multi-metal catalysts, and non-metal catalysts. Homogeneous catalysis refers to catalysis where the catalyst and reactants are in the same homogeneous phase. Compared to solid-phase catalysis, homogeneous catalysis has the following advantages: 1. Since the reactants and catalyst are in the same system, the temperature is easier to control during the reaction, and the heat transfer performance is better; 2. There is no problem of carbon accumulation on the catalyst surface during the reaction, and there is no catalyst pulverization caused by particle abrasion, so the catalyst stability is significantly better than that of solid-phase catalysts; 3. The above two advantages determine that the equipment used in liquid-phase catalysis is simpler and less expensive.
[0004] In recent years, ionic liquids have been widely used in the preparation of heterogeneous catalysts for the hydrochlorination of acetylene. However, the diverse types and properties of ionic liquids still require further exploration. Currently, there are many reports on gold-trimethylsulfur iodide (Au-(CH3)3SI) complex catalysts in the study of sulfur-containing ionic liquid catalysts. However, when this type of sulfur-containing ionic liquid catalyst is applied to the hydrochlorination of acetylene, it still has disadvantages such as poor stability at high temperatures, coordination competition, and a narrow reaction temperature window. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a supported modified gold catalyst and its application in the hydrochlorination of acetylene. First, the trimethylsulfur iodide in the gold-trimethylsulfur iodide (Au-(CH3)3SI) complex is modified by replacing it with a sterically hindered methylthionium iodide, thus inhibiting the decomposition of the thionium salt cation during the hydrochlorination of acetylene. Second, a weakly coordinating anion is used to optimize the melting point, viscosity, and compatibility with gold of the modified sterically hindered ionic liquid. Finally, the gold precursor and the modified thionium salt are co-loaded onto nitrogen-doped porous carbon. The nitrogen species act as additional anchoring sites, generating strong interactions with the gold. This effectively prevents the migration, aggregation, and loss of gold nanoparticles while enhancing catalytic activity, thereby effectively avoiding the risk of reduced catalyst activity caused by the modified ionic liquid. Compared with the gold-trimethylsulfur iodide (Au-(CH3)3SI) composite catalyst, the supported modified gold catalyst obtained by the above modification treatment has higher stability and a wider catalytic reaction temperature window without reducing catalytic activity.
[0006] Specifically, the first aspect of this invention provides a method for preparing a supported modified gold catalyst, comprising the following steps: Step 1: Anion exchange is performed on the sterically hindered methylthionium iodide to obtain a weakly coordinated anionic sterically hindered methylthionium salt; Step 2: The gold precursor is loaded onto the nitrogen-doped porous carbon support by impregnation to obtain a gold-supported nitrogen-doped porous carbon support. Step 3: The weakly coordinated anionic, highly sterically hindered methyl thionium salt is impregnated onto the gold-supported nitrogen-doped porous carbon support to obtain a supported modified gold catalyst.
[0007] As a further explanation of the present invention, the sterically hindered methylthionium iodide is one or more of (1-adamantanemethyl)dimethylthionium iodide, (naphth-1-yl)dimethylthionium iodide, and (triphenylmethyl)dimethylthionium iodide; The ion exchanger used for anion exchange in step 1 is a substance containing... , , Salts or acids; The gold precursor is one or more of chloroauric acid, gold-sodium thiosulfate, gold acetate, and gold-thiourea. The nitrogen-doped porous carbon support is one or more of the following: polydopamine-derived nitrogen-doped porous carbon, polyaniline-derived nitrogen-doped porous carbon, ZIF-8-derived nitrogen-doped porous carbon, ZIF-67-derived nitrogen-doped porous carbon, chitosan-derived nitrogen-doped porous carbon, and ordered mesoporous nitrogen-doped porous carbon.
[0008] As a further explanation of the present invention, the weakly coordinated anionic, sterically hindered methylthionium salt is... .
[0009] As a further explanation of the present invention, the... The preparation process includes the following steps: Step 11: Combine equimolar ratios and Add to the extraction solvent and mix thoroughly to allow LiI and the target product to react. Separate; Step 12: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] The target product was obtained by washing, concentrating, and drying the extract phase. .
[0010] As a further illustration of the present invention, the preparation process of the nitrogen-doped porous carbon support includes the following steps: Step 21: The ZIF-8 precursor is pyrolyzed in an inert gas atmosphere at 800-1000℃ for 1-3 hours to obtain crude ZIF-8 nitrogen-doped carbon framework. Step 22: The crude ZIF-8 nitrogen-doped carbon framework is acid-washed, water-washed and dried to obtain ZIF-8-derived nitrogen-doped porous carbon.
[0011] As a further explanation of the present invention, the gold loading in the supported modified gold catalyst is 0.1-1 wt%; the loading of the weakly coordinated anionic, highly hindered methyl thioonium salt in the supported modified gold catalyst is 5-30 wt%.
[0012] As a further explanation of the present invention, step 2 specifically includes the following process: Nitrogen-doped porous carbon support was impregnated in a certain volume of chloroauric acid aqueous solution, so that the gold loading in the final supported modified gold catalyst was 0.1-1 wt%. After impregnation at room temperature for 4-24 h, the solution was evaporated to obtain gold-supported nitrogen-doped porous carbon support.
[0013] As a further explanation of the present invention, step 3 specifically includes the following process: A weakly coordinated anionic, highly hindered methyl thioonium salt solution was obtained by dissolving a suitable amount of dichloromethane. A gold-supported nitrogen-doped porous carbon support was impregnated in a certain volume of a weakly coordinated anionic, highly hindered methyl thioonium salt solution, so that the loading of the weakly coordinated anionic, highly hindered methyl thioonium salt in the final supported modified gold catalyst was 5-30 wt%. After impregnation at room temperature for 4-24 h, the solution was evaporated and dried to obtain the supported modified gold catalyst.
[0014] The second aspect of this invention provides the application of the supported modified gold catalyst obtained by the above preparation method in the acetylene hydrochlorination reaction.
[0015] As a further explanation of the present invention, the conditions for the acetylene hydrochlorination reaction are: reaction temperature 120-200℃, reaction pressure 0.1-0.2MPa. airspeed .
[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a method for preparing a supported modified gold catalyst and its application in the acetylene hydrochlorination reaction. First, the trimethylsulfur iodide in the gold-trimethylsulfur iodide (Au-(CH3)3SI) complex is modified by replacing it with a sterically hindered methylthionium iodide to suppress the high-temperature decomposition of the thionium salt cation during the acetylene hydrochlorination reaction. Second, a weakly coordinating anion is used to optimize the melting point, viscosity, and compatibility with gold of the modified sterically hindered ionic liquid. Finally, the gold precursor and the modified thionium salt are co-loaded on nitrogen-doped porous carbon. The nitrogen species act as additional anchoring sites, generating strong interactions with the gold, effectively preventing the migration, aggregation, and loss of gold nanoparticles while enhancing catalytic activity. This effectively avoids the risk of reduced catalyst activity caused by the modified ionic liquid. Compared to the gold-trimethylsulfur iodide (Au-(CH3)3SI) complex catalyst, the supported modified gold catalyst obtained through the above modification treatment exhibits higher stability and a wider catalytic reaction temperature window. Attached Figure Description
[0017] The accompanying drawings are provided to further illustrate the present technical solution and form part of the specification. They are used together with the embodiments of the present technical solution to explain the present technical solution, but do not constitute a limitation thereof. In the accompanying drawings: Figure 1 The curves show the conversion rate of acetylene over time under different catalysts at a reaction temperature of 190℃.
[0018] Figure 2 The curves show the conversion rate of acetylene over time under different catalysts at a reaction temperature of 140℃. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0020] In recent years, ionic liquids have been widely used in the preparation of heterogeneous catalysts for the hydrochlorination of acetylene. However, the diverse types and properties of ionic liquids still require further exploration. Currently, there are many reports on gold-trimethylsulfur iodide (Au-(CH3)3SI) complex catalysts for sulfur-containing ionic liquid catalysts. However, when applied to the hydrochlorination of acetylene, this type of sulfur-containing ionic liquid catalyst still has disadvantages such as poor high-temperature stability, coordination competition, and narrow reaction temperature window.
[0021] To address the shortcomings of existing technologies, this invention provides a method for preparing a supported modified gold catalyst and its application in the hydrochlorination of acetylene. First, the trimethylsulfur iodide in the gold-trimethylsulfur iodide (Au-(CH3)3SI) complex is modified by replacing it with a sterically hindered methylthionium iodide, thus inhibiting the decomposition of the thionium salt cation during the hydrochlorination of acetylene. Second, a weakly coordinating anion is used to optimize the melting point, viscosity, and compatibility with gold of the modified sterically hindered ionic liquid. Finally, the gold precursor and the modified thionium salt are co-loaded onto nitrogen-doped porous carbon. The nitrogen species act as additional anchoring sites, generating strong interactions with the gold. This effectively prevents the migration, aggregation, and loss of gold nanoparticles while enhancing catalytic activity, thereby effectively avoiding the risk of reduced catalyst activity caused by the modified ionic liquid. Compared with the gold-trimethylsulfur iodide (Au-(CH3)3SI) composite catalyst, the supported modified gold catalyst obtained by the above modification treatment has higher stability and a wider catalytic reaction temperature window.
[0022] Specifically, the following embodiments of the present invention provide a method for preparing a supported modified gold catalyst, comprising the following steps: Step 1: Anion exchange is performed on the sterically hindered methylthionium iodide to obtain a weakly coordinated anionic sterically hindered methylthionium salt.
[0023] This invention employs a sterically hindered methylthionium iodide instead of trimethylthionium iodide. This utilizes the steric hindrance to allow the nucleophile to approach the sulfur atom, slowing down the demethylation rate of the thionium iodide and thus inhibiting the decomposition of the thionium salt cation in the acetylene hydrochlorination reaction. Specifically, the aforementioned sterically hindered methylthionium iodide is preferably one or more of (1-adamantanemethyl)dimethylthionium iodide, (naphth-1-yl)dimethylthionium iodide, and (triphenylmethyl)dimethylthionium iodide.
[0024] (1-adamantanemethyl)dimethylthionium iodide For example, the preparation process of the above-mentioned sterically hindered methylthionium iodide includes: Step 101: Add 1-iodoadaramane to an appropriate amount of acetonitrile solvent and stir to dissolve it; Step 102: Under ice-water bath cooling and stirring, slowly add dimethyl sulfide, wherein the molar ratio of 1-iodoadaramane to dimethyl sulfide is 1:1.1; Step 103: After the addition is complete, remove the ice bath, heat the reaction mixture to 60-100℃, and stir the reaction under nitrogen protection for 12-48 hours; Step 104: After the reaction is complete, cool the reaction solution to room temperature, and a white solid will precipitate. Step 105: Filter, wash and dry the precipitated white solid to obtain a white powdery solid. .
[0025] Since directly replacing trimethylthionium iodide with sterically hindered methylthionium iodide would impair the crystallization ability of ionic liquids, leading to an increase in their melting point and enhanced interionic interactions, resulting in increased viscosity, this invention further refines the initial iodide... The exchanger consists of hydrophobic, poorly coordinated, weakly coordinated anions that can lower the melting point and viscosity. Specifically, the ion exchanger used for anion exchange is preferably composed of... , , Salts or acids.
[0026] by For example, the preparation process of the above-mentioned weakly coordinated anionic, sterically hindered methyl thioonium salt includes the following steps: Step 111: Combine equimolar ratios and Add to the extraction solvent and mix thoroughly to allow LiI and the target product to react. Separate; Step 112: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] The target product was obtained by washing, concentrating, and drying the extract phase. .
[0027] Step 2: The gold precursor is loaded onto the nitrogen-doped porous carbon support by impregnation to obtain a gold-supported nitrogen-doped porous carbon support.
[0028] Specifically, the gold precursor is preferably one or more of chloroauric acid, gold-sodium thiosulfate, gold acetate, and gold-thiourea; the nitrogen-doped porous carbon support is preferably one or more of polydopamine-derived nitrogen-doped porous carbon, polyaniline-derived nitrogen-doped porous carbon, ZIF-8-derived nitrogen-doped porous carbon, ZIF-67-derived nitrogen-doped porous carbon, chitosan-derived nitrogen-doped porous carbon, and ordered mesoporous nitrogen-doped porous carbon.
[0029] The preparation process of the above-mentioned nitrogen-doped porous carbon support includes the following steps: Step 21: The ZIF-8 precursor is pyrolyzed in an inert gas atmosphere at 800-1000℃ for 1-3 hours to obtain crude ZIF-8 nitrogen-doped carbon framework. Step 22: The crude ZIF-8 nitrogen-doped carbon framework is acid-washed, water-washed and dried to obtain ZIF-8-derived nitrogen-doped porous carbon.
[0030] Step 2 above specifically includes the following process: impregnating a nitrogen-doped porous carbon support into a certain volume of chloroauric acid aqueous solution, so that the gold loading in the final supported modified gold catalyst is 0.1-1wt%, and after impregnation at room temperature for 4-24 hours, evaporating the solution to obtain a gold-supported nitrogen-doped porous carbon support.
[0031] Step 3: The obtained weakly coordinated anionic, highly sterically hindered methyl thionium salt is impregnated onto the gold-supported nitrogen-doped porous carbon support to obtain a supported modified gold catalyst.
[0032] Step 3 above specifically includes the following process: Step 31: Dissolve the weakly coordinated anionic, highly sterically hindered methyl thioonium salt in an appropriate amount of dichloromethane to obtain a solution of the weakly coordinated anionic, highly sterically hindered methyl thioonium salt. Step 32: Impregnate a gold-supported nitrogen-doped porous carbon support into a certain volume of a weakly coordinated anionic, highly hindered methyl thioonium salt solution, so that the loading of the weakly coordinated anionic, highly hindered methyl thioonium salt in the final supported modified gold catalyst is 5-30 wt%. After impregnation at room temperature for 4-24 h, evaporate the solution and dry to obtain the supported modified gold catalyst.
[0033] This invention loads a gold precursor and a modified thionium salt onto nitrogen-doped porous carbon. By utilizing nitrogen species as additional anchoring sites to generate strong interactions with gold, it can effectively prevent the migration, aggregation, and loss of gold nanoparticles while enhancing catalytic activity, thereby effectively avoiding the risk of reduced catalyst activity caused by modified ionic liquids.
[0034] When the supported modified gold catalyst obtained by the above preparation method of the present invention is applied to the acetylene hydrochlorination reaction, it exhibits higher stability and a wider catalytic reaction temperature range compared to the gold-trimethylsulfur iodide (Au-(CH3)3SI) composite catalyst without reducing catalytic activity.
[0035] Specifically, the conditions for the acetylene hydrochlorination reaction are: reaction temperature 120-200℃, reaction pressure 0.1-0.2 MPa. airspeed .
[0036] Example 1 This embodiment provides a supported modified gold catalyst: The preparation method of [the substance] includes the following steps: Step 1: Preparation : 27.62 g of 1-iodoadaramane and 100 mL of acetonitrile were dissolved by stirring. 8 mL of dimethyl sulfide was slowly added dropwise under ice-water bath cooling and stirring (ensuring a molar ratio of approximately 1:1.1 between 1-iodoadaramane and dimethyl sulfide). After the addition was complete, the ice bath was removed, the reaction mixture was heated to 80 °C, and stirred for 24 hours under nitrogen protection. After the reaction was complete, the reaction solution was cooled to room temperature, and a white solid precipitated. The precipitated white solid was filtered, washed, and dried under vacuum at 50 °C for 12 hours to obtain a white powdery solid. The yield is approximately 30 g, with a yield of around 90%.
[0037] Step 2: Preparation : Take 16.66 g of the product obtained in step 1 and 14.35 g (must be guaranteed) and Add the mixture (with a molar ratio of approximately 1:1) to a separatory funnel, then add 100 mL of deionized water and 50 mL of dichloromethane. Shake thoroughly to dissolve LiI in the aqueous phase, while the target product... The solution was dissolved in dichloromethane, allowed to stand and separate into layers, the lower dichloromethane phase was separated and collected, and the aqueous phase was repeatedly extracted with dichloromethane. All dichloromethane phases were combined, and the combined dichloromethane phases were washed with deionized water to completely remove residual LiI. Anhydrous magnesium sulfate was added to the resulting dichloromethane solution and dried until the liquid was clear. The drying agent was removed by filtration, and the dichloromethane was removed by vacuum evaporation to obtain a viscous oily product. The obtained product was dried under vacuum at 80°C for 24 hours to finally obtain the target product. The yield is approximately 22.0 g, with a yield of around 95%.
[0038] Step 3: Preparation of ZIF-8 derived nitrogen-doped porous carbon: The dried ZIF-8 precursor powder was placed in a tube furnace and heated to 950°C at a rate of 5°C / min for 2 hours under an Ar inert atmosphere to carry out a pyrolysis reaction, which fully carbonized the 2-methylimidazole and reduced and evaporated the metallic zinc. The pyrolysis product was washed with dilute hydrochloric acid at 80°C with stirring to completely remove residual metallic zinc species. It was then washed with deionized water until neutral and finally dried at 110°C to obtain ZIF-8-derived nitrogen-doped porous carbon.
[0039] Step 4: Preparation : The ZIF-8-derived nitrogen-doped porous carbon obtained in step 3 was impregnated into a certain volume of chloroauric acid aqueous solution, resulting in the final product... The Au loading was 0.1 wt%, and the solution was evaporated to dryness after impregnation at room temperature for 12 h to obtain Au / N-AC; the solution obtained in step 2 was... Dissolved in an appropriate amount of dichloromethane to obtain The solution was used to impregnate the obtained Au / N-AC to a certain volume. In the solution, so that the final result is middle The loading was 10 wt%, and after impregnation at room temperature for 12 h, the solution was evaporated and dried to obtain the supported modified gold catalyst. .
[0040] Comparative Example 1 This comparative example provides a supported modified gold catalyst: The preparation method differs from that of Example 1 in that steps 1 and 3 are the same as in Example 1, but step 2 is removed, and step 4 is modified to: prepare The ZIF-8-derived nitrogen-doped porous carbon obtained in step 3 is impregnated into a certain volume of chloroauric acid aqueous solution, so that the final product is obtained... The Au loading was 0.1 wt%, and the solution was evaporated to dryness after impregnation at room temperature for 12 h to obtain Au / N-AC; the solution obtained in step 1 was... Dissolved in an appropriate amount of dichloromethane to obtain The solution was used to impregnate the obtained Au / N-AC to a certain volume. In the solution, so that the final result is middle The loading was 10 wt%, and after impregnation at room temperature for 12 h, the solution was evaporated and dried to obtain the supported modified gold catalyst. .
[0041] Comparative Example 2 This comparative example provides a supported modified gold catalyst: The preparation method differs from Example 1 in that steps 1 and 2 are the same as in Example 1, but step 3 is removed, and step 4 is modified to: prepare Mesoporous carbon Immersed in a certain volume of chloroauric acid aqueous solution, resulting in the final product The Au loading was 0.1 wt%, and the solution was evaporated to dryness after impregnation at room temperature for 12 h to obtain Au / AC; the solution obtained in step 2 was... Dissolved in an appropriate amount of dichloromethane to obtain The solution was used to impregnate the resulting Au / AC solution to a certain volume. In the solution, so that the final result is middle The loading was 10 wt%, and after impregnation at room temperature for 12 h, the solution was evaporated and dried to obtain the supported modified gold catalyst. .
[0042] Comparative Example 3 This comparative example provides a supported modified gold catalyst: The preparation method differs from that of Example 1 in that step 3 is the same as in Example 1, but step 1 is removed, and step 2 is modified to: prepare : 10.1 g and 14.35 g (must be guaranteed) and Add the mixture (with a molar ratio of approximately 1:1) to a separatory funnel, then add 100 mL of deionized water and 50 mL of dichloromethane. Shake thoroughly to dissolve LiI in the aqueous phase, while the target product... The aqueous phase was dissolved in dichloromethane, allowed to stand and separate into layers, the lower dichloromethane phase was separated and collected, and the aqueous phase was repeatedly extracted with dichloromethane. All dichloromethane phases were combined, and the combined dichloromethane phases were washed with deionized water to completely remove residual LiI. Anhydrous magnesium sulfate was added to the resulting dichloromethane solution and dried until the liquid was clear. The drying agent was removed by filtration, and the dichloromethane was removed by vacuum evaporation to obtain a viscous oily product. The obtained product was dried under vacuum at 35°C for 24 hours to finally obtain the target product. The yield is approximately 16.5 g, with a yield of around 95%.
[0043] Meanwhile, step 4 is modified to: preparation The ZIF-8-derived nitrogen-doped porous carbon obtained in step 3 is impregnated into a certain volume of chloroauric acid aqueous solution, so that the final product is obtained... The Au loading was 0.1 wt%, and the solution was evaporated to dryness after impregnation at room temperature for 12 h to obtain Au / N-AC; the solution obtained in step 2 was... Dissolved in an appropriate amount of dichloromethane to obtain The solution was used to impregnate the obtained Au / N-AC to a certain volume. In the solution, so that the final result is middle The loading was 10 wt%, and after impregnation at room temperature for 12 h, the solution was evaporated and dried to obtain the supported modified gold catalyst. .
[0044] Comparative Example 4 This comparative example provides a method for preparing a supported modified gold catalyst: Au-(CH3)3SI / N-AC. The difference between this method and Example 1 is that steps 1 and 2 are removed, step 3 is the same as in Example 1, and step 4 is modified as follows: To prepare Au-(CH3)3SI / N-AC, the ZIF-8 derived nitrogen-doped porous carbon obtained in step 3 is impregnated into a certain volume of chloroauric acid aqueous solution, resulting in the final... The Au loading was 0.1 wt%. After impregnation at room temperature for 12 h, the solution was evaporated to obtain Au / N-AC. (CH3)3SI was dissolved in an appropriate amount of deionized water to obtain (CH3)3SI solution. The obtained Au / N-AC was impregnated into a certain volume of (CH3)3SI solution, so that the (CH3)3SI loading in the final Au-(CH3)3SI / N-AC was 10 wt%. After impregnation at room temperature for 12 h, the solution was evaporated to obtain the supported modified gold catalyst Au-(CH3)3SI / N-AC.
[0045] The supported modified gold catalysts obtained in the above examples and comparative examples were applied to the acetylene hydrochlorination reaction, and the catalytic activity and stability of each catalyst at different reaction temperatures were tested.
[0046] The acetylene hydrochlorination reaction process is as follows: The catalysts obtained in the above examples and comparative examples are loaded into a fixed-bed reactor. After the catalysts are activated, the reactor temperature is adjusted to the target reaction temperature (140℃ and 190℃). Hydrogen chloride gas is introduced to fill the system and pre-adsorb onto the catalyst. The HCl flow rate is set to reach the acetylene space velocity. After 30 minutes, acetylene gas was introduced to maintain the reaction system pressure at 0.1 MPa, and the volume ratio of the two gases was controlled at HCl:C₂H₂ = 1.2. The gas flowed through the reaction tube and then into a bottle containing phenolphthalein-containing sodium hydroxide solution. Acetylene and vinyl chloride, which are insoluble in the alkali solution, were directly introduced into the gas chromatograph for detection. Unreacted acetylene gas was detected online by gas chromatography.
[0047] The data analysis method used was the corrected normalization method, which can accurately calculate the acetylene conversion rate and directly indicate the activity of the catalyst. The acetylene conversion rate calculation method is as follows:
[0048] φ AO φ is the volume fraction of acetylene in the reactants. A This represents the volume fraction of the remaining acetylene in the product.
[0049] Specific test results are as follows Figure 1 and Figure 2 As shown, where, Figure 1The curves show the conversion rate of acetylene over time under different catalysts at a reaction temperature of 190℃. Figure 2 The graph shows the conversion rate of acetylene over time under different catalysts at a reaction temperature of 140℃. Figure 1 As can be seen, when the reaction temperature is at a relatively high temperature of -190°C, the product provided in Example 1 of this invention... The catalytic activity of the catalyst provided by this invention is higher than that of the catalysts provided in Comparative Examples 1-4, with the highest acetylene conversion rate reaching over 96%. Furthermore, the acetylene conversion rate does not change significantly with time, indicating that the catalyst provided by this invention maintains high catalytic activity and stability even during the high-temperature reaction at 190℃. Comparative Examples 1-4 represent the following four cases: ① Using sterically hindered methylthionium iodide instead of trimethylthionium iodide + nitrogen-doped porous carbon support, but without weak coordination anion optimization; ② Using sterically hindered methylthionium iodide instead of trimethylthionium iodide + weak coordination anion optimization, but without nitrogen-doped porous carbon support; ③ Directly using trimethylthionium iodide + weak coordination anion optimization + nitrogen-doped porous carbon support; ④ Directly using trimethylthionium iodide + nitrogen-doped porous carbon support, but without weak coordination anion optimization. By comparing the results of Example 1, Comparative Examples 3 and 4, it can be seen that under reaction conditions of 190°C, when trimethylthionium iodide is directly used as the ionic liquid, the acetylene conversion rate gradually decreases with increasing reaction time, indicating its poor stability at high temperatures. Figure 2 As can be seen, when the reaction temperature is at a relatively low temperature of -140°C, the product provided in Example 1 of this invention... The catalytic activity of the catalyst provided in this invention is higher than that of the catalysts provided in Comparative Examples 1-4, with the highest acetylene conversion rate reaching over 83%. Furthermore, the acetylene conversion rate does not change significantly with time, indicating that the catalyst provided in this invention maintains high catalytic activity and stability even at a low-temperature reaction temperature of 140℃. This demonstrates that the catalyst provided in this invention possesses excellent stability and a wide catalytic reaction temperature window. In addition, by comparing the catalytic activity and stability of Example 1 and Comparative Examples 1-4, it can be seen that each step in the modification process of the catalyst provided in this invention is interconnected and indispensable; only through mutual synergy can the optimal catalytic effect be achieved.
[0050] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a supported modified gold catalyst, characterized in that, Includes the following steps: Step 1: Anion exchange is performed on the sterically hindered methylthionium iodide to obtain a weakly coordinated anionic sterically hindered methylthionium salt; Step 2: The gold precursor is loaded onto the nitrogen-doped porous carbon support by impregnation to obtain a gold-supported nitrogen-doped porous carbon support. Step 3: The weakly coordinated anionic, sterically hindered methyl thionium salt is impregnated onto the gold-supported nitrogen-doped porous carbon support to obtain a supported modified gold catalyst.
2. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: The sterically hindered methyl thionium iodide is one or more of (1-adamantanemethyl)dimethyl thionium iodide, (naphth-1-yl)dimethyl thionium iodide, and (triphenylmethyl)dimethyl thionium iodide; The ion exchanger used for anion exchange in step 1 contains... , , Salts or acids; The gold precursor is one or more of chloroauric acid, gold-sodium thiosulfate, gold acetate, and gold-thiourea. The nitrogen-doped porous carbon support is one or more of the following: polydopamine-derived nitrogen-doped porous carbon, polyaniline-derived nitrogen-doped porous carbon, ZIF-8-derived nitrogen-doped porous carbon, ZIF-67-derived nitrogen-doped porous carbon, chitosan-derived nitrogen-doped porous carbon, and ordered mesoporous nitrogen-doped porous carbon.
3. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: The weakly coordinated anionic, sterically hindered methylthionium salt is... .
4. The method for preparing the supported modified gold catalyst as described in claim 3, characterized in that: The The preparation process includes the following steps: Step 11: Combine equimolar ratios and Add to the extraction solvent and mix thoroughly to allow LiI and the target product to react. Separate; Step 12: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] The target product was obtained by washing, concentrating, and drying the extract phase. .
5. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: The preparation process of the nitrogen-doped porous carbon support includes the following steps: Step 21: The ZIF-8 precursor is pyrolyzed in an inert gas atmosphere at 800-1000℃ for 1-3 hours to obtain crude ZIF-8 nitrogen-doped carbon framework. Step 22: The crude ZIF-8 nitrogen-doped carbon framework is acid-washed, water-washed and dried to obtain ZIF-8-derived nitrogen-doped porous carbon.
6. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: The gold loading in the supported modified gold catalyst is 0.1-1 wt%; the loading of the weakly coordinated anionic, sterically hindered methyl thioonium salt in the supported modified gold catalyst is 5-30 wt%.
7. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: Step 2 specifically includes the following process: Nitrogen-doped porous carbon support was impregnated in a certain volume of chloroauric acid aqueous solution, so that the gold loading in the final supported modified gold catalyst was 0.1-1 wt%. After impregnation at room temperature for 4-24 h, the solution was evaporated to obtain gold-supported nitrogen-doped porous carbon support.
8. The method for preparing the supported modified gold catalyst as described in claim 1, characterized in that: Step 3 specifically includes the following process: A weakly coordinated anionic, highly hindered methyl thioonium salt solution was obtained by dissolving a suitable amount of dichloromethane. A gold-supported nitrogen-doped porous carbon support was impregnated in a certain volume of a weakly coordinated anionic, highly hindered methyl thioonium salt solution, so that the loading of the weakly coordinated anionic, highly hindered methyl thioonium salt in the final supported modified gold catalyst was 5-30 wt%. After impregnation at room temperature for 4-24 h, the solution was evaporated and dried to obtain the supported modified gold catalyst.
9. The application of the supported modified gold catalyst obtained by the preparation method according to any one of claims 1-8 in the acetylene hydrochlorination reaction.
10. The application of the supported modified gold catalyst as described in claim 9 in the acetylene hydrochlorination reaction, characterized in that, The conditions for the acetylene hydrochlorination reaction are: reaction temperature 120-200℃, reaction pressure 0.1-0.2MPa. airspeed .