A gold monatomic catalyst for catalyzing the hydrochlorination of acetylene, and a preparation method and application thereof

Abstract

The application discloses a gold single-atom catalyst for catalyzing acetylene hydrochlorination reaction and a preparation method and application thereof. Activated carbon is added to an ethanol solution containing a triazine nitrogen-containing heterocyclic organic compound and an alkali metal bromide, stirred and dried, and then calcined under a nitrogen atmosphere to obtain a treated carrier; the treated carrier is mixed with a gold precursor solution, and then stirred under a protective gas. The gold single-atom catalyst prepared by the application can preferentially form a coordination action with N atoms in the carrier through the introduced alkali metal atoms, thereby promoting the subsequent active component Au to mainly form a coordination action with C. Since the two have similar electronegativities, the active component Au can exist in a lower valence state more, the content of the active component Au in +1 and +3 valences is significantly increased, the stability of the active component in the catalyst is improved, the catalytic activity and stability are improved, and the production of carbon deposition can be reduced.

Description

Technical Field

[0001] This invention relates to a gold single-atom catalyst for catalyzing the hydrochlorination reaction of acetylene, its preparation method and application, belonging to the field of catalytic reaction technology. Background Technology

[0002] Polyvinyl chloride (PVC) is widely used in building materials, industrial products, daily necessities, floor coverings, floor tiles, artificial leather, pipes, wires and cables, packaging films, bottles, foaming materials, and sealing materials. It is an indispensable material in people's lives. With the continuous development of technology, the application fields of PVC are constantly expanding, and the demand is also constantly rising. Vinyl chloride is the main monomer for synthesizing PVC. According to the difference of raw materials, there are mainly three methods: acetylene method, ethylene method and ethane method. At present, the catalyst for the acetylene hydrochlorination reaction is usually carbon-supported mercuric chloride. This catalyst has the advantages of high catalytic activity and selectivity, but it has the following defects: (1) HgCl2 is easy to desorb and sublimate during the reaction process, and the catalyst has poor stability; (2) HgCl2 has high toxicity and harmfulness, and serious environmental damage; (3) HgCl2 is difficult to recover. Based on the above reasons, it is urgent to develop a green and efficient alternative to HgCl2 acetylene hydrochlorination catalyst. Therefore, a great deal of research has been conducted on alternative active components, including single-component and two-component catalysts such as Ru, Cu, and Au. Among them, Au has shown good catalytic activity and selectivity. However, Au is a precious metal element and is expensive. Therefore, the ideal Au catalyst is one that has high catalytic activity and selectivity at low loading. However, low loading often reduces catalytic efficiency.

[0003] Current research on mercury-free catalysts focuses on both noble metal catalysts and non-noble metal catalysts. However, due to the lower performance and poor stability of non-noble metal catalysts, noble metal catalysts have become the primary focus of mercury-free catalyst research.

[0004] The patents filed by Tianjin University and Tianjin Tiandi Chuangzhi Technology Development Co., Ltd., including 201210307780.5, 201210307816.X, 201210305820.2, and 201210305818.5, all use ruthenium as the main active component, and nickel, cobalt, copper, and other alkali metals and transition metals as auxiliary active components.

[0005] The patents applied for by Shihezi University (201510174452.6) and Inner Mongolia University (201510469027.X) both use gold, a precious metal, as the main active component, and have been optimized by improving the dispersibility of the active component and introducing auxiliary active components.

[0006] Compared with precious metals such as ruthenium and platinum, gold catalysts with gold as the main active component have significant advantages in terms of catalytic activity and stability. Therefore, gold-based catalysts are expected to become the next generation of industrial catalysts to replace mercury-based catalysts in the hydrochlorination of acetylene.

[0007] Currently, gold-based catalyst research mainly focuses on nanoparticles, but these have drawbacks such as poor dispersion of active components, easy aggregation, low molecular utilization, low activity, relatively large loading, and high cost. Summary of the Invention

[0008] To address the problems of poor dispersion and low activity of active components in existing acetylene hydrochlorination catalysts, the present invention aims to provide a gold single-atom catalyst for catalyzing the acetylene hydrochlorination reaction, its preparation method, and its application. This method fully utilizes Au catalytic active centers, thereby improving the dispersion of active components, as well as catalytic activity and selectivity.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] A method for preparing a gold single-atom catalyst for catalyzing the hydrochlorination reaction of acetylene includes the following steps:

[0011] Activated carbon was added to an ethanol solution containing triazine nitrogen-containing heterocyclic organic compounds and alkali metal bromides, stirred and dried, and then calcined under a nitrogen atmosphere to obtain the treated support.

[0012] The treated support was mixed with a gold precursor solution, and then stirred under a protective gas to obtain a gold single-atom catalyst for catalyzing the hydrochlorination of acetylene.

[0013] A further improvement of the present invention is that the alkali metal bromide is one of lithium bromide, sodium bromide, potassium bromide and rubidium bromide.

[0014] A further improvement of the present invention is that the triazine-type nitrogen-containing heterocyclic organic compound is one of cyanamide, dicyandiamide and melamine.

[0015] A further improvement of this invention is that the molar ratio of the triazine nitrogen-containing heterocyclic organic compound to the alkali metal bromide is 2:1-3.

[0016] A further improvement of the present invention is that the calcination temperature is 450-650℃ and the time is 4-5h.

[0017] A further improvement of the present invention is that the temperature is increased to 450-650°C at a heating rate of 2-3°C / min.

[0018] A further improvement of this invention is that the gold precursor is chloroauric acid.

[0019] A further improvement of the present invention is that the mass ratio of the treated carrier to chloroauric acid is 5:0.135.

[0020] A gold single-atom catalyst for catalyzing the hydrochlorination of acetylene, wherein the catalyst has an Au atom loading of 0.1-3 wt%.

[0021] Application of a gold single-atom catalyst for catalyzing the hydrochlorination of acetylene in the preparation of vinyl chloride.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The gold single-atom catalyst prepared in this invention preferentially coordinates with nitrogen atoms in the support through introduced alkali metal atoms. This promotes the subsequent coordination of the loaded active component Au with carbon atoms. Due to the similar electronegativity of the two, the active component Au exists more in a lower valence state, significantly increasing the content of Au in +1 and +3 valence states. This improves the stability of the active component in the catalyst, further enhancing its catalytic activity and stability. It also effectively reduces agglomeration during the reaction, minimizing deactivation of the active component and reducing carbon deposition. The gold single-atom catalyst prepared in this invention improves the dispersibility of the active component, maximizing atom utilization while fully leveraging its catalytic effect, significantly improving the catalyst's catalytic activity and stability. This invention employs a simplified preparation method, eliminating complex procedures and using concise steps, which not only improves the efficiency of catalyst preparation but also enhances its reproducibility.

[0024] Compared with existing metal catalysts for the hydrochlorination of acetylene, the active components in the gold single-atom catalyst of this invention are dispersed in a single-atom state, which has a high molecular utilization rate, can improve stability and catalytic activity, is not easy to lose or agglomerate, and simultaneously activates the acetylene and hydrogen chloride reactants, thus significantly improving the catalytic activity and stability of existing metal catalysts. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 The graph shows the acetylene conversion rate versus reaction time for the catalysts (Examples 1-5 and Comparative Example 1).

[0027] Figure 2 The graph shows the selectivity-reaction time relationship of vinyl chloride with the catalysts (Examples 1-5 and Comparative Example 1);

[0028] Figure 3 The graph shows the acetylene conversion rate versus reaction time for the catalysts (Examples 1, 5, 7-10 and Comparative Example 1).

[0029] Figure 4 The selectivity-reaction time relationship of vinyl chloride for catalysts (Examples 1, 5, 7-10 and Comparative Example 1);

[0030] Figure 5 The graph shows the acetylene conversion rate versus reaction time for the catalysts (Examples 1, Examples 11-12);

[0031] Figure 6 The selectivity-reaction time relationship of vinyl chloride for catalysts (Examples 1, Examples 11-12);

[0032] Figure 7 Graph showing the acetylene conversion rate versus reaction time for catalysts (Examples 6, Examples 13-14);

[0033] Figure 8 The graph shows the selectivity-reaction time relationship of vinyl chloride for the catalysts (Examples 6, Examples 13-14);

[0034] Figure 9 The image shows the HAADF-STEM image of the catalyst (Example 1). Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0036] I. The preparation method of the gold single-atom catalyst for the catalytic hydrochlorination reaction of acetylene is as follows:

[0037] Support preparation: Weigh a certain amount of triazine-based nitrogen-containing heterocyclic organic compound and an alkali metal bromide. Add both to ethanol and stir for 15 min to ensure complete dissolution and homogeneity, obtaining a mixed solution. Then, weigh activated carbon and add it to the mixed solution, stirring for 6-12 h. Dry the solution under vacuum at 60℃ for 12-24 h. After drying, calcine at high temperature under a nitrogen atmosphere for 4-5 h, with a heating rate of 2-3℃ / min. The heating rate affects the formation of C3N4; too rapid a heating rate will cause volatilization, preventing the formation of the desired C3N4 structure.

[0038] The carrier was then washed with deionized water, filtered, and vacuum dried at 60°C to obtain the treated carrier.

[0039] The above-mentioned temperature and time limits are because dissolution or reaction needs to take a certain period of time at the above-mentioned temperature in order to completely dissolve or react.

[0040] The selected alkali metal bromide is chosen from one of lithium bromide, sodium bromide, potassium bromide, and rubidium bromide; more preferably, the alkali metal bromide is potassium bromide.

[0041] The triazine-type nitrogen-containing heterocyclic organic compound is selected from one of cyanamide, dicyandiamide and melamine; preferably, the triazine-type nitrogen-containing heterocyclic organic compound is cyanamide.

[0042] The molar ratio of the triazine-based nitrogen-containing heterocyclic organic compound to the alkali metal bromide is 2:1-3. More preferably, the molar ratio of the activated carbon to the triazine-based nitrogen-containing heterocyclic organic compound is 2:1-2.

[0043] The calcination temperature is 450-650℃, and more preferably, the calcination temperature is 560-600℃.

[0044] Preparation of gold single-atom catalyst: A certain amount of the treated support was weighed and added to deionized water. After sonication for 30 min, a certain amount of chloroauric acid solution was added to obtain a mixture. Nitrogen gas was introduced into the mixture, and then it was heated to 60℃ and stirred for 8 h. After washing with deionized water and vacuum drying, the prepared gold single-atom catalyst was obtained.

[0045] The loading of Au atoms is 0.5-1.5 wt%, preferably 0.8-1.3 wt%, based on the total weight of the gold single-atom catalyst.

[0046] II. Method for preparing vinyl chloride by acetylene hydrochlorination

[0047] The gold single-atom catalyst prepared in step one was used as a catalyst and packed into a fixed-bed reactor. Acetylene and hydrogen chloride reaction gases were introduced, and the reaction was carried out at 110-300℃ with an acetylene space velocity (GHSV) of 960-1500 h⁻¹. -1 Under the reaction conditions of acetylene and hydrogen chloride in a volume ratio of 1:1-2, the reaction proceeds for 24 h to produce vinyl chloride.

[0048] Preparation of the gold precursor solution: Dissolve 1 g of chloroauric acid (gold precursor) in a 100 mL volumetric flask to prepare a chloroauric acid solution. This is to prepare for subsequent sample preparation.

[0049] The selected gold precursor is chloroauric acid. During the thermal activation of the catalyst, the water of crystallization will be removed. In addition to the water of crystallization leaving, a molecule of HCl will also be released from chloroauric acid. The stable gold precursor then becomes AuCl3. Therefore, the stable precursor here refers to the part of the gold precursor that is finally present in the catalyst.

[0050] The reaction is a gas-phase reaction.

[0051] The main reactions involved in the acetylene hydrochlorination process include:

[0052] Main reaction: C2H2 + HCl → CH2=CHCl

[0053] Non-polymerization side reactions:

[0054] CH2=CHCl + HCl→CH3CHCl2

[0055] CH2=CHCl + HCl → CH2ClCH2Cl

[0056] Polymerization side reactions:

[0057] 2CH2=CHCl→CH2ClCH=CCl-CH3

[0058] 2C2H2→CH2=CH-C≡CH

[0059] Existing thermodynamic studies indicate that the main reaction is significantly influenced by polymerization side reactions, while non-polymerization side reactions have little impact on the main reaction. Both the main and side reactions are exothermic, but the thermal effect of polymerization side reactions is greater than that of the main reaction. Higher temperatures are more conducive to suppressing polymerization side reactions (polymerization products may deposit on the catalyst surface, forming carbon deposits), improving the selectivity of the main reaction, and reducing carbon deposits. However, at high temperatures, metal catalysts suffer from valence change deactivation. Considering the combined effects of temperature on polymerization side reactions and catalyst reductive deactivation, the reaction temperature is controlled at 110-300℃, more preferably at 140-280℃, and most preferably at 180-260℃.

[0060] The volume ratio of acetylene to hydrogen chloride is a commonly used volume ratio in the art, specifically 1:1-2. More preferably, the volume ratio of acetylene to hydrogen chloride is 1:1-1.5. Most preferably, the volume ratio of acetylene to hydrogen chloride is 1:1.02-1.2.

[0061] The gas-phase reaction was carried out in a fixed-bed reactor, with a gold single-atom catalyst packed within the reactor. The acetylene space velocity was controlled within the range commonly used in this field, specifically 960-1500 h⁻¹. -1 Preferably, the acetylene space velocity is controlled at 960-1200 h⁻¹. -1 .

[0062] In this invention, the triazine-based nitrogen-containing heterocyclic organic compounds and alkali metal bromides interact with the support, forming a carbon nitride structure within the support after calcination. The addition of a gold precursor further promotes this interaction, anchoring the active components to the support and preventing loss and agglomeration. Simultaneously, the central metal atom coordinates with the support and the carbon nitride structure formed by the triazine-based nitrogen-containing heterocyclic organic compound. The empty d orbitals around the central metal atom nucleus effectively adsorb and activate electron-rich acetylene, while the structure on the support that coordinates with it can adsorb and activate hydrogen chloride through hydrogen bonding. This creates a microenvironment favorable for electrophilic addition reactions, significantly enhancing the catalytic activity and stability of the catalyst.

[0063] The gold single-atom catalyst is formed by dispersing a central metal atom in the form of single atoms under the synergistic effect of carbon nitride and alkali metal, and forming coordination with the support, thereby exerting its catalytic advantages under the synergistic effect of the two; the central metal atom is Au.

[0064] Preferably, the loading of Au atoms (i.e., the percentage of Au atoms by mass of the catalyst) is 0.5-1.5 wt% based on the total weight of the gold-based catalyst, and more preferably 0.8-1.3 wt%.

[0065] The total weight of the catalyst is calculated as follows: m 总 =m 载体 +m 稳态前驱体 +m 氮化碳 .

[0066] m 总 m is the total weight of the catalyst. 载体 m is the weight of the carrier. 稳态前驱体 m is the weight of Au supported in the catalyst. 氮化碳 This represents the weight of carbon nitride formed after calcination of triazine-type nitrogen-containing heterocyclic organic compounds.

[0067] Example 1

[0068] Support treatment: First, 4 g of cyanamide and 5.95 g of KBr were weighed and dissolved in 30 mL of ethanol. Then, 10 g of activated carbon was added, and the mixture was stirred for 6 h. After filtration, the mixture was vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere with a heating rate of 2.2 °C / min. Then, the mixture was washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0069] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst. The theoretical loading is 1.3%, and the actual loading is 0.89%, denoted as Au SAC KCN.

[0070] Example 2

[0071] Support treatment: First, 4 g of cyanamide and 4.34 g of LiBr were weighed and dissolved in 30 mL of ethanol. Then, 10 g of activated carbon was added, and the mixture was stirred for 6 h. After filtration, the mixture was vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere with a heating rate of 2.2 °C / min. The mixture was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0072] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After the heating is complete, filter and wash repeatedly with deionized water. Then dry under vacuum at 60 °C for 12 h to obtain the prepared catalyst. The theoretical loading is 1.3%, and the actual loading is 0.89%, denoted as Au SAC LiCN.

[0073] Example 3

[0074] Support treatment: First, 4 g of cyanamide and 5.15 g of NaBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 6 h, then filtered and vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere at a heating rate of 2.2 °C / min. The calcined support was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0075] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst. The theoretical loading is 1.3%, and the actual loading is 0.89%, denoted as Au SAC NaCN.

[0076] Example 4

[0077] Support treatment: First, 4 g of cyanamide and 8.27 g of RbBr were weighed and dissolved in 30 mL of ethanol. Then, 10 g of activated carbon was added, and the mixture was stirred for 6 h. After filtration, the mixture was vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere with a heating rate of 2.2 °C / min. The mixture was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0078] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain the temperature for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst. The theoretical loading is 1.3%, and the actual loading is 0.89%, denoted as Au SAC RbCN.

[0079] Example 5

[0080] Support treatment: First, 4 g of cyanamide and 5.95 g of KBr were weighed and dissolved in 30 mL of ethanol. Then, 10 g of activated carbon was added, and the mixture was stirred for 6 h. After filtration, the mixture was vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere with a heating rate of 2.2 °C / min. Then, the mixture was washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0081] Measure 10.3 mL of chloroauric acid solution into 25 mL of deionized water, stir for 30 min to mix evenly, weigh 5 g of the prepared support, add it to the above solution, stir for 12 h, water bath at 80℃ for 24 h, filter, and dry at 120℃ for 24 h to obtain the prepared catalyst with an actual loading of 0.89%, denoted as Au KCN.

[0082] Comparative Example 1

[0083] Measure 10.3 mL of chloroauric acid solution into 25 mL of deionized water, stir for 30 min to mix evenly, weigh 5 g of activated carbon, add it to the above solution, stir for 12 h, water bath at 80℃ for 24 h, filter, and dry at 120℃ for 24 h to obtain the prepared catalyst with an actual loading of 0.89%, denoted as Au AC.

[0084] The load is calculated as follows: mAu / (m 载体 +m 稳态前驱体 +m 氮化碳 )=0.0449 g / (5 g+0.0449g)=0.89%.

[0085] Example 6

[0086] One mL of the catalyst prepared in Examples 1-5 and Comparative Example 1 was respectively packed into a fixed-bed reactor, and acetylene and hydrogen chloride reaction gases were introduced. The reactor was set at 180°C and acetylene space velocity (GHSV) = 1200 h⁻¹. -1 Under reaction conditions where the volume ratio of acetylene to hydrogen chloride was 1:1.15, the reaction was carried out for 24 h, and the acetylene conversion and vinyl chloride selectivity were measured. The test results for the acetylene hydrochlorination reaction catalyzed by various catalysts are as follows: Figure 1 and Figure 2 As shown.

[0087] See Figure 1 As can be seen, when the alkali metal bromide is preferably KBr, the catalyst prepared in the above embodiments has the highest catalytic activity and stability, with an activity of up to 99.06%.

[0088] See Figure 2 As can be seen, the catalysts prepared in the above embodiments all exhibit selectivity for vinyl chloride.

[0089] See Figure 9 It can be seen that in the catalyst prepared in Example 1, the active component Au is distributed in the form of single atoms.

[0090] Example 7

[0091] Support treatment: First, 4 g of cyanamide and 5.95 g of KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 6 h, then filtered and vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 650 °C for 4 h under a nitrogen atmosphere at a heating rate of 2.2 °C / min. The calcined support was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0092] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst with an actual loading of 0.89%, denoted as AuSAC KCN-1.

[0093] Example 8

[0094] Support treatment: First, 4 g of cyanamide and 11.3 g of KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 6 h, then filtered and vacuum dried at 60 °C for 12 h. After drying, the mixture was calcined at 560 °C for 4 h under a nitrogen atmosphere at a heating rate of 2.2 °C / min. The calcined support was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support.

[0095] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst with an actual loading of 0.89%, denoted as AuSAC KCN-2.

[0096] Example 9

[0097] Support treatment: First, 4 g of dicyandiamide and KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 12 h, then filtered and vacuum dried at 60 °C for 24 h. After drying, the mixture was calcined at 450 °C for 5 h under a nitrogen atmosphere at a heating rate of 2 °C / min. It was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support. The molar ratio of dicyandiamide to KBr was 2:1.

[0098] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h to obtain the prepared catalyst. The theoretical loading is 1.3%, and the actual loading is 0.89%, denoted as Au SAC KCN-3.

[0099] Example 10

[0100] Support treatment: First, 4 g of melamine and KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 9 h, then filtered and vacuum dried at 60 °C for 20 h. After drying, the mixture was calcined at 600 °C for 4 h under a nitrogen atmosphere at a heating rate of 3 °C / min. It was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support. The molar ratio of melamine to KBr was 2:3.

[0101] Weigh 5 g of the support and disperse it in 26 mL of water. Sonicate for 30 min, then add 13.5 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After the heating is complete, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h. The theoretical loading is 1.3%, and the actual loading is 0.89%, yielding the prepared catalyst, denoted as Au SAC KCN-4.

[0102] The catalysts from Examples 1, 7-10, and Comparative Example 1 were applied to the catalytic hydrochlorination of acetylene. The catalytic results are shown in [reference needed]. Figure 3 and Figure 4 The catalytic effect of the embodiments in this invention is better than that of vinyl chloride selectivity in Comparative Example 1.

[0103] See Figure 3 As can be seen, compared with the Au SAC KCN prepared in Example 1, the catalytic activities of the catalysts Au SAC KCN-1, Au SAC KCN-2, Au SAC KCN-3 and Au SAC KCN-4 prepared by changing the calcination conditions and adjusting the amount of alkali metal bromide all decreased. Among them, Au SAC KCN (99.06%) > Au SAC KCN-2 (95.64%) > Au SAC KCN-4 (93.49%) > Au SAC KCN-1 (82.47%) > Au SAC KCN-3 (81.02%). Therefore, the optimal preparation conditions can be selected.

[0104] See Figure 4 As can be seen, the catalysts prepared in the above embodiments all exhibit selectivity for vinyl chloride.

[0105] Example 11

[0106] Support treatment: First, 4 g of melamine and KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 9 h, then filtered and vacuum dried at 60 °C for 20 h. After drying, the mixture was calcined at 600 °C for 4 h under a nitrogen atmosphere at a heating rate of 3 °C / min. It was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support. The molar ratio of melamine to KBr was 2:3.

[0107] Weigh 5 g of support and disperse it in 26 mL of water. Sonicate for 30 min, then add 7.3 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After the heating is complete, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h. The theoretical loading is 0.7%, and the actual loading is 0.5%, yielding the prepared catalyst, denoted as 0.5 wt% Au SAC KCN.

[0108] Example 12

[0109] Support treatment: First, 4 g of melamine and KBr were dissolved in 30 mL of ethanol, followed by the addition of 10 g of activated carbon. The mixture was stirred for 9 h, then filtered and vacuum dried at 60 °C for 20 h. After drying, the mixture was calcined at 600 °C for 4 h under a nitrogen atmosphere at a heating rate of 3 °C / min. It was then washed with deionized water and vacuum dried at 60 °C for 12 h to obtain the treated support. The molar ratio of melamine to KBr was 2:3.

[0110] Weigh 5 g of support and disperse it in 26 mL of water. Sonicate for 30 min, then add 22.8 mL of chloroauric acid solution. Purge the mixture with nitrogen gas to induce bubbling for 30 min, then heat to 60 °C and maintain for 8 h. After heating, filter and wash repeatedly with deionized water, then vacuum dry at 60 °C for 12 h. The theoretical loading is 2.2%, and the actual loading is 1.5%, yielding the prepared catalyst, denoted as 1.5 wt% Au SAC KCN.

[0111] The catalysts from Examples 1 and 11-12 were applied to the catalytic hydrochlorination of acetylene. The catalytic results are shown in [reference needed]. Figure 5 and Figure 6 .

[0112] See Figure 5 It can be seen that by adjusting the loading of the active component in the catalyst, the catalytic activity and stability of each catalyst increase with the increase of the loading of the active component.

[0113] See Figure 6 As can be seen, the catalysts prepared in the above embodiments all exhibit selectivity for vinyl chloride.

[0114] Example 13

[0115] 1 mL of the catalyst prepared in Example 1 was packed into a fixed-bed reactor, and acetylene and hydrogen chloride reaction gases were introduced. The reactor was set at 300°C and acetylene space velocity (GHSV) = 1500 h⁻¹. -1Under the reaction conditions of acetylene to hydrogen chloride volume ratio of 1:2, the reaction was carried out for 24 h to achieve the catalytic hydrochlorination of acetylene, denoted as Au SAC KCN-1500.

[0116] Example 14

[0117] 1 mL of the catalyst from Example 1 was packed into a fixed-bed reactor, and acetylene and hydrogen chloride reaction gases were introduced. The reactor was set at 140°C and the acetylene space velocity (GHSV) was 960 h⁻¹. -1 Under the reaction conditions of acetylene to hydrogen chloride volume ratio of 1:1.5, the reaction was carried out for 24 h to achieve the catalytic hydrochlorination of acetylene, denoted as Au SAC KCN-960.

[0118] The catalysts from Examples 6 and 13-14 were applied to the catalytic hydrochlorination of acetylene. The catalytic results are shown in [reference needed]. Figure 7 and Figure 8 .

[0119] See Figure 7 It can be seen that the catalytic activity and stability of each catalyst decrease with increasing space velocity.

[0120] See Figure 8 As can be seen, the catalysts prepared in the above embodiments all exhibit selectivity for vinyl chloride.

[0121] The key to this invention is the supported catalyst with low Au loading, high catalytic efficiency, and low cost. Single-atom catalysts have advantages such as highly dispersed catalytic active centers, no clusters, and high activity, thus possessing potential advantages as catalysts for the hydrochlorination of acetylene.

[0122] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0123] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a gold single-atom catalyst for catalyzing the hydrochlorination reaction of acetylene, characterized by comprising the following steps: Activated carbon is added to an ethanol solution of an organic compound and an alkali metal bromide, stirred and dried, and then calcined at 450-650℃ for 4-5 hours under a nitrogen atmosphere to obtain the treated support; the organic compound is one of cyanamide, dicyandiamide and melamine; the molar ratio of the organic compound to the alkali metal bromide is 2:1-3. The treated support was mixed with a chloroauric acid solution and then stirred under a protective gas to obtain a gold single-atom catalyst for catalyzing the hydrochlorination of acetylene; the mass ratio of the treated support to chloroauric acid was 5:0.

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2. The method for preparing the gold single-atom catalyst for catalyzing the hydrochlorination reaction of acetylene according to claim 1, characterized in that the alkali metal bromide is one of lithium bromide, sodium bromide, potassium bromide and rubidium bromide.

3. The method for preparing the gold single-atom catalyst for catalyzing the hydrochlorination reaction of acetylene according to claim 1, characterized in that the temperature is increased to 450-650℃ at a heating rate of 2-3℃ / min.

4. A gold single-atom catalyst for catalyzing the hydrochlorination of acetylene, prepared by the method according to any one of claims 1-3, characterized in that, The catalyst has an Au atom loading of 0.5-1.5 wt%.

5. The application of a gold single-atom catalyst prepared according to claim 1 for catalyzing the hydrochlorination reaction of acetylene in the preparation of vinyl chloride.

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