A gold-based catalyst for the production of vinyl chloride by the hydrochlorination of acetylene and methods for its preparation and use

Abstract

The application provides a gold-based catalyst for preparing vinyl chloride by an acetylene hydrochlorination method and a preparation and use method thereof. The catalyst is mainly used for synthesizing vinyl chloride from acetylene and hydrogen chloride in a normal-pressure fixed bed reactor and belongs to the field of chemical catalysis. According to the principle of isoelectric point and electrostatic adsorption, imidazole is uniformly grown to stabilize the iodine-containing ligand and the active component Au to form two kinds of stable gold iodine complexes with different valence states by taking activated carbon as a carrier and gold salt as an active component, so that a new type of high-efficiency acetylene hydrochlorination mercury-free catalyst is prepared, the activity and stability of the catalyst are improved, and the carbon deposition amount is reduced. The method has high feasibility, high catalyst conversion rate and good stability.

Description

Technical Field

[0001] This invention proposes a gold-based catalyst for the preparation of vinyl chloride via the acetylene hydrochlorination process, along with its preparation and application methods. This catalyst is primarily used for the synthesis of vinyl chloride from acetylene and hydrogen chloride in an atmospheric pressure fixed-bed reactor, and belongs to the field of chemical catalysis. Background Technology

[0002] Polyvinyl chloride (PVC) is the world's second most widely used resin material after polyethylene, making the industrial production of its monomer, vinyl chloride (VCM), particularly important. Due to my country's energy characteristics of being rich in coal but poor in oil, over 79% of my country's vinyl chloride is produced using the calcium carbide method, which uses coal as a raw material. The HgCl2 catalyst traditionally used in this method is highly toxic and prone to sublimation at high temperatures, posing serious threats to the environment and human health. Since 2020, my country has banned the production of mercury-containing products, making the development of mercury-free catalysts an urgent priority. Currently, gold-based catalysts are the most popular and promising area of ​​research. However, due to the high price of gold and its susceptibility to reduction and deactivation, developing highly active and stable gold-based catalysts has significant environmental and economic value.

[0003] Hutchings of Cardiff University in the UK predicted and proved that gold-based catalysts are the most active catalysts for the hydrochlorination of acetylene, sparking a surge of research on gold-based catalysts in China in recent years. Currently, gold-based catalysts have achieved preliminary industrial applications. The advantages of gold-based catalysts are high reactivity and low required loading. However, cationic gold is easily reduced to zero-valent gold, resulting in poor catalyst stability, short lifespan, and high cost. Therefore, the main research direction for gold-based catalysts is the design and synthesis of highly stable gold catalysts.

[0004] Currently, common methods for improving the catalytic performance of gold-based catalysts include: introducing ligands, promoters, ionic liquids, modifying the support, improving the preparation method, and doping with other metal elements. Ligands play an important role in transition metal catalysis, and adding ligands to stabilize metal ions is a common method. Adding ligands can not only stabilize cationic gold but also modulate the reactivity of gold catalysts.

[0005] For example, patent (CN 114146730 A) uses sulfur-containing ligands as co-catalyst components and pre-treats activated carbon with a P-containing aqueous solution. The addition of P and sulfur ligands in the resulting catalyst inhibits the reduction of high-valence gold species and reduces the loss of gold species, but the catalyst cannot maintain stability well. Patent (CN 109622036 A) uses a complex formed by gold salt and nitrogen-containing ligands as the main active component. The complexation of nitrogen-containing ligands with gold stabilizes high-valence gold, thereby improving the efficiency of the catalyst. Patent (CN 102631947 A) prepares a catalyst with good activity and high stability using potassium tetrathiocyanate, a gold complex, as the active component. 102029189A) Catalysts are prepared using gold halides and complexes as active components. The gold halides are one or more of HAuCl4, HAuI4, ethylenediamine gold chloride, and triphenylphosphine gold chloride. The co-active component is a non-precious metal salt. However, this method uses high gold content and the catalyst preparation process is costly.

[0006] The main challenges currently faced by gold-based catalysts include the easy reduction of ionic Au, the easy loss of active components Au and ligands, and severe carbon deposition, which lead to poor catalyst stability and easy deactivation. Summary of the Invention

[0007] This invention aims to address the challenges of stabilizing ionic Au, anchoring the active component and ligands, and reducing catalyst carbon deposition, thereby overcoming the difficulties of traditional catalysts such as easy reduction and loss of active components, severe carbon deposition, and poor stability. This invention proposes a gold-based catalyst for the hydrochlorination of acetylene to vinyl chloride, along with its preparation and application methods. By using activated carbon as a support and gold salt as the active component, imidazole is uniformly grown based on the isoelectric point principle and electrostatic adsorption, thereby stabilizing the iodine-containing ligands and the active component Au, forming two stable gold-iodine complexes with different valence states. This results in a novel, highly efficient mercury-free catalyst for the hydrochlorination of acetylene, improving catalyst activity and stability while reducing carbon deposition. This method is highly feasible, exhibits high catalyst conversion rate, and demonstrates good stability.

[0008] The specific technical solution of the present invention is as follows:

[0009] 1. A method for preparing a gold-based catalyst for the acetylene hydrochlorination process to produce vinyl chloride, characterized by comprising the following preparation steps:

[0010] (1) At 40–50 °C, 100–120 mesh activated carbon powder was added to deionized water under stirring. Then, acid was slowly added to adjust the pH of the slurry to 3–4 and stirring was continued for 1–3 h. Then, acid and sodium zincate were added at the same time, and the pH of the solution was always controlled within the range of 3–4. After stirring for 1–3 h, the obtained product was washed with deionized water until neutral, and the filter cake obtained after vacuum filtration was dried to obtain sample A. Sample A was then placed in a tube furnace and heated at an air space velocity of 40–80 h⁻¹. –1 Under the conditions of calcination at 350–400 °C for 2–4 h, sample B was obtained; in a reaction vessel at 40–50 °C, sample B was added to an organic solvent under stirring, followed by the slow addition of imidazole substances. After stirring for 1–3 h, the reaction vessel was sealed, and the temperature was raised to 110–130 °C and maintained for 5–10 h. After washing with organic solvent multiple times, the filter cake obtained after vacuum filtration was dried to obtain sample C.

[0011] (2) In a reactor at 40–50 °C, under stirring, sample C is added to an organic solvent, followed by the slow addition of iodine-containing alkane. After stirring for 1–3 h, the reactor is sealed. The temperature is then raised to 130–150 °C and maintained for 4–8 h. After washing with organic solvent multiple times, the filter cake obtained after filtration is dried to obtain sample D.

[0012] (3) Gold salt was impregnated onto sample D using the equal volume impregnation method, and the resulting sample was dried at 110–130 °C to obtain the desired catalyst.

[0013] 2. The catalyst preparation method according to Scheme 1 is characterized in that: the activated carbon in step (1) is one or more of coconut shell activated carbon, coal-based activated carbon, and pitch-based activated carbon.

[0014] 3. The catalyst preparation method according to Scheme 1 is characterized in that: the acid in step (1) is one or more of nitric acid, hydrochloric acid, sulfuric acid and acetic acid.

[0015] 4. The catalyst preparation method according to Scheme 1 is characterized in that: the mass ratio of activated carbon, non-washing deionized water and sodium zincate in step (1) is 1: 20–40: 0.04–0.08.

[0016] 5. The catalyst preparation method according to Scheme 1 is characterized in that: the organic solvent in steps (1) and (2) is one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, and N,N-dimethylformamide, wherein the mass ratio of sample B and the non-washing organic solvent is 1:20–40.

[0017] 6. The catalyst preparation method according to Scheme 1 is characterized in that: the imidazole substance in step (1) is one or more of 2-methylimidazolium, N-isopropylimidazolium, benzimidazole, and 2,4-dimethylimidazolium, wherein the molar ratio of the imidazole substance to sodium zincate is 1.15–1.25 : 1.

[0018] 7. The catalyst preparation method according to Scheme 1 is characterized in that: the iodoalkane in step (2) is one or more of 1-iodobutane, 1-iododecane, benzyl iodine, cyclopentyl iodine, and 4-iodotoluene, wherein the molar ratio of iodoalkane to imidazole is 1.15–1.25 : 1.

[0019] 8. The catalyst preparation method according to Scheme 1 is characterized in that: the gold salt in step (3) is one or more of gold trichloride, gold monochloride, gold iodide, chloroauric acid, and potassium chloroaurate, wherein the molar ratio of gold element to iodoalkane is 1:10–45.

[0020] 9. A gold-based catalyst for the preparation of vinyl chloride by acetylene hydrochlorination, characterized in that it is prepared by any one of the preparation methods in Schemes 1–8.

[0021] 10. A method of using the gold-based catalyst described in Scheme 9, characterized by the following steps:

[0022] (1) The catalyst is loaded into the isothermal zone of the continuous flow atmospheric pressure fixed bed reactor, and at least 20 cm of ceramic rings are loaded on the catalyst as a preheating layer. The catalyst is pretreated to 160–190 °C under flowing nitrogen for at least 1 h.

[0023] (2) Switch nitrogen to HCl and purge for at least 1 h; then turn on C2H2 and set the gas hourly space velocity to 80–120 h. –1 At the same time, ensure that the volume ratio of HCl / C2H2 is 1.2;

[0024] (3) The reaction tail gas is absorbed by alkaline solution and dehydrated by silica gel column before entering gas chromatography for online analysis;

[0025] (4) After the reaction is complete, first turn off the raw material gas, then continue to purge with nitrogen for 0.5–1 h, then cool down, and turn off the nitrogen gas when the temperature drops below 80 °C.

[0026] Compared with the prior art, the present invention has the following innovations:

[0027] (1) In this invention, we uniformly load ZnO2 onto the surface of activated carbon. 2–A zinc oxide anchor is formed by calcination of the imidazole group. Then, the weak acidity of the imidazole group is used to etch the zinc oxide anchor, allowing the imidazole group to grow uniformly on the activated carbon surface. After etching the zinc oxide sites, the imidazole group undergoes N-site tautomerism. Iodinated alkanes are then added, and an imidazole iodide salt is formed through a nucleophilic substitution reaction. This method stabilizes iodide ions by anchoring imidazole with zinc oxide, which further reacts with Au to form a stable gold-iodide complex. This complex, due to the imidazole group, is firmly bound to the activated carbon surface, reducing the loss of the active component Au, enhancing the stability of ionic Au, and improving the catalytic performance of the catalyst.

[0028] (2) In this invention, we use acid to adjust the pH of the activated carbon slurry to the range of 3–4. Then, by adding acid and sodium zincate, while controlling the pH of the slurry to remain stable, we use liquid-phase electrostatic adsorption and cleverly utilize the isoelectric point principle to make the surface of the activated carbon positively charged. Due to ZnO2 2– The groups carry negative charges, and opposite charges attract each other, thus causing ZnO2 to... 2– The groups are uniformly distributed on the activated carbon surface, ensuring the uniform growth of imidazole substances and iodine ligands. Traditional solid-liquid impregnation methods easily cause ZnO2... 2– Due to the uneven distribution of functional groups and their blockage of carrier pores, we achieved ZnO2 deposition through electrostatic adsorption and the isoelectric point principle. 2– The selective growth and uniform distribution of functional groups; and this strong electrostatic adsorption requires less time than the reaction between sodium zincate and acid, thus efficiently and conveniently growing ZnO2 modified on the surface of activated carbon by utilizing the time difference between dynamic adsorption and chemical reaction. 2– Species.

[0029] (3) The zinc source in this invention must be sodium zincate in order to achieve electrostatic adsorption by utilizing the isoelectric point principle. If zinc nitrate or other zinc sources are used instead, zinc species that are uniformly distributed and do not block the pore structure cannot be obtained, and the required catalyst structure cannot be obtained.

[0030] (4) In this invention, the calcination is carried out in an air atmosphere. The purpose is to convert zinc ion groups into zinc oxide sites, thereby providing the prerequisite for the next step of etching imidazole materials.

[0031] (5) In this invention, we limited the ratio of acid to sodium zincate to control the pH of the slurry. Reason one: Sodium zincate is prone to precipitation under small amounts of acid, causing blockage of the activated carbon pore structure and resulting in a decrease in the catalytic performance of the final catalyst. Reason two: Small amounts of acid cannot adjust the pH of the solution to maintain a positive charge on the activated carbon surface according to the isoelectric point principle.

[0032] (6) In this invention, we precisely controlled the molar ratio of iodine ligand to Au.– Au can be weakly reduced 3+ To Au + thereby regulating Au 3+ / Au + To achieve the desired ratio, two stable gold-iodine complexes with different valence states are formed as the active components. Simultaneously, the introduction of iodine-containing ligands reduces the adsorption strength and amount of acetylene by the Au-based catalyst, while significantly enhancing the adsorption strength and amount of hydrogen chloride, thus greatly inhibiting the formation of catalyst carbon deposits. Attached Figure Description

[0033] Figure 1 This is a SEM image of catalyst CAT-1. Detailed Implementation

[0034] To better illustrate this patent, the following embodiments are provided. These embodiments are intended to enable those skilled in the art to understand the invention in more detail, or to allow for non-essential improvements and adjustments based on the content of the invention. However, the scope of the invention is not limited to these embodiments.

[0035] Example 1

[0036] (1) At 50 °C, 100–120 mesh coconut shell activated carbon powder was added to deionized water under stirring. Then, nitric acid was slowly added to adjust the pH of the slurry to 4 and stirring was continued for 3 h. Then, nitric acid and sodium zincate were added simultaneously, and the pH of the solution was always controlled at 4. After stirring for 3 h, the product was washed with deionized water until neutral and the filter cake obtained after vacuum filtration was dried to obtain sample A, in which the mass ratio of activated carbon, non-washing deionized water and sodium zincate was 1:40:0.08. Sample A was then placed in a tube furnace and heated at an air space velocity of 80 h⁻¹. –1 Under the conditions of calcination at 400 °C for 4 h, sample B was obtained. In a reaction vessel at 50 °C, sample B was added to methanol under stirring, followed by the slow addition of 2-methylimidazole. After stirring for 3 h, the reaction vessel was sealed, and the temperature was raised to 130 °C and maintained for 10 h. The sample was then washed multiple times with methanol, and the filter cake obtained after filtration was dried to obtain sample C. The mass ratio of sample B to unwashed methanol was 1:40, and the molar ratio of 2-methylimidazole to sodium zincate was 1.25:1.

[0037] (2) In a reactor at 50 °C, sample C was added to methanol under stirring, followed by the slow addition of 1-iodobutane. After stirring for 3 h, the reactor was sealed, and the temperature was raised to 150 °C and maintained for 8 h. The sample was then washed with methanol multiple times and the filter cake obtained after filtration was dried to obtain sample D, wherein the molar ratio of 1-iodobutane to 2-methylimidazole was 1.25:1.

[0038] (3) Chloroauric acid was impregnated onto sample D using the equal volume impregnation method, and then the resulting sample was dried at 130 °C to obtain the desired catalyst, wherein the molar ratio of gold element to 1-iodobutane was 1:45; the obtained catalyst was numbered CAT-1.

[0039] Example 2

[0040] The preparation steps of Example 2 are the same as those of Example 1, except that the coconut shell activated carbon in step (1) is replaced with asphalt-based activated carbon, and the resulting catalyst is numbered CAT-2.

[0041] Example 3

[0042] The preparation steps of Example 3 are the same as those of Example 1, except that the nitric acid in step (1) is replaced with hydrochloric acid, and the resulting catalyst is numbered CAT-3.

[0043] Example 4

[0044] The preparation steps of Example 4 are the same as those of Example 1, except that methanol in steps (1) and (2) is replaced with N,N-dimethylformamide, and the resulting catalyst is numbered CAT-4.

[0045] Example 5

[0046] The preparation steps of Example 5 are the same as those of Example 1, except that 2-methylimidazole in step (1) is replaced with 2,4-dimethylimidazole, and the resulting catalyst is numbered CAT-5.

[0047] Example 6

[0048] The preparation steps of Example 6 are the same as those of Example 1, except that 1-iodobutane in step (2) is replaced with cyclopentyliodine, and the resulting catalyst is numbered CAT-6.

[0049] Example 7

[0050] The preparation steps of Example 7 are the same as those of Example 1, except that chloroauric acid in step (3) is replaced with gold trichloride, and the resulting catalyst is numbered CAT-7.

[0051] Example 8

[0052] The preparation steps of Example 8 are the same as those of Example 1, except that the mass ratio of activated carbon, non-washing deionized water and sodium zincate in step (1) is changed to 1:40:0.04, and the resulting catalyst is numbered CAT-8.

[0053] Example 9

[0054] The preparation steps of Example 9 are the same as those of Example 1, except that the molar ratio of 2-methylimidazole and sodium zincate in step (1) is changed to 1.15:1, and the resulting catalyst is numbered CAT-9.

[0055] Example 10

[0056] The preparation steps of Example 10 are the same as those of Example 1, except that the molar ratio of 1-iodobutane to 2-methylimidazole in step (2) is changed to 1.15:1, and the resulting catalyst is numbered CAT-10.

[0057] Example 11

[0058] The preparation steps of Example 11 are the same as those of Example 1, except that the molar ratio of gold to 1-iodobutane in step (3) is changed to 1:10, and the resulting catalyst is numbered CAT-11.

[0059] Comparative Example 1

[0060] The step of adjusting the pH value of the slurry was omitted in order to compare with Example 1 and illustrate the effect of different slurry pH values ​​on ZnO2. 2– The effect of the distribution of functional groups on the surface of activated carbon.

[0061] (1) At 50 °C, 100–120 mesh coconut shell activated carbon powder was added to deionized water under stirring, and then sodium zincate was added. After stirring for 3 h, the resulting product was washed with deionized water until neutral, and the filter cake obtained after vacuum filtration was dried to obtain sample A, wherein the mass ratio of activated carbon, non-washing deionized water and sodium zincate was 1:40:0.08; sample A was then placed in a tube furnace and heated at an air space velocity of 80 h⁻¹. –1 Under the conditions of calcination at 400 °C for 4 h, sample B was obtained. In a reaction vessel at 50 °C, sample B was added to methanol under stirring, followed by the slow addition of 2-methylimidazole. After stirring for 3 h, the reaction vessel was sealed, and the temperature was raised to 130 °C and maintained for 10 h. The sample was then washed multiple times with methanol, and the filter cake obtained after filtration was dried to obtain sample C. The mass ratio of sample B to unwashed methanol was 1:40, and the molar ratio of 2-methylimidazole to sodium zincate was 1.25:1.

[0062] (2) In a reactor at 50 °C, sample C was added to methanol under stirring, followed by the slow addition of 1-iodobutane. After stirring for 3 h, the reactor was sealed, and the temperature was raised to 150 °C and maintained for 8 h. The sample was then washed with methanol multiple times and the filter cake obtained after filtration was dried to obtain sample D, wherein the molar ratio of 1-iodobutane to 2-methylimidazole was 1.25:1.

[0063] (3) Chloroauric acid was impregnated onto sample D using the equal volume impregnation method. The resulting sample was then dried at 130 °C to obtain the desired catalyst, wherein the molar ratio of gold to 1-iodobutane was 1:45; the resulting catalyst was numbered CAT-12.

[0064] Comparative Example 2

[0065] The purpose of using zinc nitrate as the zinc source is to compare with Example 1 to illustrate the effect of the charge carried by the zinc ion groups in the zinc source on their distribution on the activated carbon surface.

[0066] The preparation steps of Comparative Example 2 are the same as those of Example 1, except that sodium zincate in step (1) is replaced with zinc nitrate, and the resulting catalyst is numbered CAT-13.

[0067] Comparative Example 3

[0068] Nitrogen was chosen as the roasting atmosphere to compare with Example 1 and illustrate the effect of the roasting atmosphere on the formation of zinc oxide anchors.

[0069] The preparation steps of Comparative Example 2 are the same as those of Example 1, except that the air in step (1) is replaced with nitrogen, and the resulting catalyst is numbered CAT-14.

[0070] Comparative Example 4

[0071] The solvent washing step was omitted to compare with Example 1 and illustrate the effect of excess sodium zincate and imidazole on the pore structure of the carrier.

[0072] (1) At 50 °C, 100–120 mesh coconut shell activated carbon powder was added to deionized water under stirring. Then, nitric acid was slowly added to adjust the pH of the slurry to 4 and stirring was continued for 3 h. Then, nitric acid and sodium zincate were added at the same time, and the pH of the solution was always controlled at 4. Stirring was continued for 3 h. The filter cake obtained after filtration was dried to obtain sample A, in which the mass ratio of activated carbon, deionized water and sodium zincate was 1:40:0.08. Sample A was then placed in a tube furnace and heated at an air space velocity of 80 h⁻¹. –1 Under the conditions of calcination at 400 °C for 4 h, sample B was obtained. In a reaction vessel at 50 °C, sample B was added to methanol under stirring, followed by the slow addition of 2-methylimidazole. After stirring for 3 h, the reaction vessel was sealed, and the temperature was raised to 130 °C and maintained for 10 h. The filter cake obtained after filtration was dried to obtain sample C. The mass ratio of sample B to methanol and non-washing methanol was 1:20–40, and the molar ratio of 2-methylimidazole to sodium zincate was 1.25:1.

[0073] (2) In a reactor at 50 °C, sample C was added to methanol under stirring, followed by the slow addition of 1-iodobutane. After stirring for 3 h, the reactor was sealed, and the temperature was raised to 150 °C and maintained for 8 h. The sample was then washed with methanol multiple times and the filter cake obtained after filtration was dried to obtain sample D, wherein the molar ratio of 1-iodobutane to 2-methylimidazole was 1.25:1.

[0074] (3) Chloroauric acid was impregnated onto sample D using the equal volume impregnation method. The resulting sample was then dried at 130 °C to obtain the desired catalyst, wherein the molar ratio of gold to 1-iodobutane was 1:45; the resulting catalyst was numbered CAT-15.

[0075] Comparative Example 5

[0076] The purpose of increasing the amount of sodium zincate is to compare with Example 1 and to illustrate the effect of excessive sodium zincate on the pore structure of the carrier.

[0077] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the mass ratio of activated carbon, non-washing deionized water and sodium zincate in step (1) is changed to 1:40:0.2, and the resulting catalyst is numbered CAT-16.

[0078] Comparative Example 6

[0079] The purpose of reducing the amount of sodium zincate is to compare with Example 1 to illustrate the effect of the amount of sodium zincate on zinc oxide anchor points.

[0080] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the mass ratio of activated carbon, non-washing deionized water and sodium zincate in step (1) is changed to 1:40:0.01, and the resulting catalyst is numbered CAT-17.

[0081] Comparative Example 7

[0082] Increasing the molar ratio of iodoalkane to gold was intended to compare with Example 1 and demonstrate the effect of a higher molar ratio of iodine-containing ligand to gold on regulating Au. 3+ / Au + The effect of catalyst activity.

[0083] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the molar ratio of gold to 1-iodobutane in step (3) is changed to 1:60, and the resulting catalyst is numbered CAT-18.

[0084] Comparative Example 8

[0085] The purpose of reducing the molar ratio of iodoalkane to gold was to compare with Example 1 and illustrate the effect of a lower molar ratio of iodine-containing ligand to gold on regulating Au.3+ / Au + The effect of catalyst activity.

[0086] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the molar ratio of gold to 1-iodobutane in step (3) is changed to 1:5, and the resulting catalyst is numbered CAT-19.

[0087] Methods and conditions for testing the activity of catalysts:

[0088] (1) The catalyst is loaded into the isothermal zone of the continuous flow atmospheric pressure fixed bed reactor, and at least 20 cm of ceramic rings are loaded on the catalyst as a preheating layer. The catalyst is preheated to 180 °C for 1 h under flowing nitrogen.

[0089] (2) Switch nitrogen to HCl and purge for 1 h; then turn on C2H2 and set the gas hourly space velocity to 80 h. –1 At the same time, ensure that the volume ratio of HCl / C2H2 is 1.2;

[0090] (3) The reaction tail gas is absorbed by alkaline solution and dehydrated by silica gel column before entering gas chromatography for online analysis;

[0091] (4) After the reaction is complete, first turn off the raw material gas, then continue to purge with nitrogen for 1 hour, then cool down, and turn off the nitrogen when the temperature drops to 80 °C.

[0092] The activity evaluation results of CAT-1 to CAT-11 catalysts, as well as gold-based catalysts with a mass content of 0.17% (0.17 wt.% Au / AC) supported on industrial activated carbon (AC) and chloroauric acid, are shown in the table below:

[0093] catalyst Acetylene conversion rate (%) Vinyl chloride selectivity (%) CAT-1 98.14 99.5 CAT-2 97.68 99.5 CAT-3 96.82 99.5 CAT-4 96.92 99.5 CAT-5 97.51 99.5 CAT-6 97.32 99.5 CAT-7 97.66 99.5 CAT-8 97.62 99.5 CAT-9 97.71 99.5 CAT-10 97.67 99.5 CAT-11 97.36 99.5 CAT-12 47.14 96.8 CAT-13 57.26 97.3 CAT-14 51.94 97.2 CAT-15 75.24 98.5 CAT-16 89.72 99.3 CAT-17 81.62 99.3 CAT-18 91.77 99.5 CAT-19 72.64 99.2 AC 32.43 95.6 0.17 wt.% Au / AC 91.71 99.5

Claims

1. A method for preparing a gold-based catalyst for the acetylene hydrochlorination process to produce vinyl chloride, characterized in that... The preparation steps include the following: (1) At 40–50 °C, 100–120 mesh activated carbon powder was added to deionized water under stirring. Then, acid was slowly added to adjust the pH of the slurry to 3–4 and stirring was continued for 1–3 h. Then, acid and sodium zincate were added at the same time, and the pH of the solution was always controlled within the range of 3–4. After stirring for 1–3 h, the obtained product was washed with deionized water until neutral, and the filter cake obtained after vacuum filtration was dried to obtain sample A. Sample A was then placed in a tube furnace and heated at an air space velocity of 40–80 h⁻¹. –1 Under the conditions of calcination at 350–400 °C for 2–4 h, sample B was obtained; in a reaction vessel at 40–50 °C, sample B was added to an organic solvent under stirring, followed by the slow addition of imidazole substances. After stirring for 1–3 h, the reaction vessel was sealed, and the temperature was raised to 110–130 °C and maintained for 5–10 h. After washing with organic solvent multiple times, the filter cake obtained after vacuum filtration was dried to obtain sample C. (2) In a reactor at 40–50 °C, under stirring, sample C is added to an organic solvent, followed by the slow addition of iodine-containing alkane. After stirring for 1–3 h, the reactor is sealed. The temperature is then raised to 130–150 °C and maintained for 4–8 h. After washing with organic solvent multiple times, the filter cake obtained after filtration is dried to obtain sample D. (3) Gold salt was impregnated onto sample D using the equal volume impregnation method, and the resulting sample was then dried at 110–130 °C to obtain the desired catalyst.

2. The catalyst preparation method according to claim 1, characterized in that: The activated carbon in step (1) is one or more of coconut shell activated carbon, coal-based activated carbon, and pitch-based activated carbon.

3. The catalyst preparation method according to claim 1, characterized in that: The acid in step (1) is one or more of nitric acid, hydrochloric acid, sulfuric acid, and acetic acid.

4. The catalyst preparation method according to claim 1, characterized in that: The mass ratio of activated carbon, non-washing deionized water, and sodium zincate in step (1) is 1: 20–40: 0.04–0.

08.

5. The catalyst preparation method according to claim 1, characterized in that: The organic solvents in steps (1) and (2) are one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, and N,N-dimethylformamide, wherein the mass ratio of sample B to the organic solvent used for washing is 1:20–40.

6. The catalyst preparation method according to claim 1, characterized in that: The imidazole substance in step (1) is one or more of 2-methylimidazolium, N-isopropylimidazolium, benzimidazole, and 2,4-dimethylimidazolium, wherein the molar ratio of the imidazole substance to sodium zincate is 1.15–1.25 :

1.

7. The catalyst preparation method according to claim 1, characterized in that: The iodoalkane in step (2) is one or more of 1-iodobutane, 1-iododecane, benzyl iodine, cyclopentyl iodine, and 4-iodotoluene, wherein the molar ratio of the iodoalkane to the imidazole is 1.15–1.25 :

1.

8. The catalyst preparation method according to claim 1, characterized in that: The gold salt in step (3) is one or more of gold trichloride, gold monochloride, gold iodide, chloroauric acid, and potassium chloroaurate, wherein the molar ratio of gold element to iodoalkane is 1:10–45.

9. A gold-based catalyst for the preparation of vinyl chloride via acetylene hydrochlorination, characterized in that, Prepared using the preparation method according to any one of claims 1–8.

10. A method of using the gold-based catalyst according to claim 9, characterized by specifically including the following steps: (1) The catalyst is loaded into the isothermal zone of the continuous flow atmospheric pressure fixed bed reactor, and at least 20 cm of ceramic rings are loaded on the catalyst as a preheating layer. The catalyst is pretreated to 160–190 °C under flowing nitrogen for at least 1 h. (2) Switch nitrogen to HCl and purge for at least 1 h; then turn on C2H2 and set the gas hourly space velocity to 80–120 h. –1 At the same time, ensure that the volume ratio of HCl / C2H2 is 1.2; (3) The reaction tail gas is absorbed by alkaline solution and dehydrated by silica gel column before entering gas chromatography for online analysis; (4) After the reaction is complete, first turn off the raw material gas, then continue to purge with nitrogen for 0.5–1 h, then cool down, and turn off the nitrogen gas when the temperature drops below 80 °C.

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