A mercury-free catalyst, its preparation method and use

Abstract

This invention relates to the field of catalyst preparation technology, and more particularly to a mercury-free catalyst, its preparation method, and its application. The preparation method of the mercury-free catalyst includes the following steps: adding a copper salt, an active agent, and an iridium complex to ethanol to obtain a mixed solution; then impregnating the mixed solution into pretreated activated carbon using an equal-volume impregnation method; and finally, after standing and drying, obtaining the mercury-free catalyst. This preparation method is simple and easy to operate, and the resulting catalyst has advantages such as high catalytic activity, good stability, long service life, and being mercury-free and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a mercury-free catalyst, its preparation method, and its application. Background Technology

[0002] Vinyl chloride monomer is the main raw material for the production of polyvinyl chloride (PVC), and its production processes mainly include the ethylene process and the acetylene process. In the industrial application of the acetylene process for synthesizing vinyl chloride, the traditionally used mercuric chloride catalyst has been restricted and phased out due to its high toxicity and environmental hazards. Therefore, developing efficient and environmentally friendly mercury-free catalysts has become a key research focus. Copper-based catalysts are considered a feasible alternative to mercuric chloride catalysts due to their good catalytic activity and relatively low environmental toxicity. However, current copper-based catalysts generally suffer from high copper loading, with some catalysts even exceeding 20 wt%. Although copper is less toxic than mercury, it still poses certain environmental risks as a heavy metal. Furthermore, activated carbon supports are prone to carbon deposition during long-term reactions, further affecting the stability and lifespan of the catalyst. Therefore, how to maintain or even improve catalytic performance while reducing copper loading has become a critical issue that urgently needs to be addressed for the industrial application of copper-based catalysts. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a simple method for preparing a mercury-free catalyst.

[0004] The second objective of this invention is to provide a mercury-free catalyst with advantages such as high catalytic activity, good stability, and long service life.

[0005] The third objective of this invention is to provide an application of a mercury-free catalyst, which has broad prospects.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A method for preparing a mercury-free catalyst includes the following steps:

[0008] A copper salt, an active agent, and an iridium complex were added to ethanol to obtain a mixed solution. The mixed solution was then impregnated into pretreated activated carbon using an equal-volume impregnation method. After standing and drying, the mercury-free catalyst was obtained.

[0009] The structural formula of the active adjuvant is:

[0010] .

[0011] Preferably, the preparation method of the active additive is as follows:

[0012] Under inert gas protection, 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, and platinum catalyst were added to 1,4-dioxane, and the reaction was carried out to obtain the active additive.

[0013] Preferably, the ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, and platinum catalyst is 1 mol: (4-4.1) mol: (5-6) mL; the platinum catalyst is platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane; the reaction temperature is 80-90℃, and the reaction time is 12-24 h.

[0014] Preferably, the iridium complex is prepared by the following method:

[0015] (1) Add 2-(4-bromomethylphenyl)pyridine to tetrahydrofuran, then add hexadecyl dimethyl tertiary amine, and after the reaction, compound 1 is obtained;

[0016] The structural formula of compound 1 is:

[0017]

[0018] (2) Triethylamine and acetone [bis-(2-aminoethyl)dithioacetal] were added to tetrahydrofuran, and then a tetrahydrofuran solution of 2,2-bipyridine-4,4-dicarboxyl chloride was added. After the reaction, compound 2 was obtained.

[0019] The structural formula of compound 2 is:

[0020]

[0021] (3) The compound 1, the compound 2 and hydrated iridium trichloride were added to ethylene glycol ethyl ether and refluxed under inert gas protection to obtain the iridium complex;

[0022] The structural formula of the iridium complex is:

[0023] .

[0024] Preferably, in step (1), the molar ratio of 2-(4-bromomethylphenyl)pyridine to hexadecyl dimethyl tertiary amine is 1:(2.5-3.8); the reaction time is 36-48 h; in step (2), the molar ratio of 2,2-bipyridine-4,4-dicarboxylic acid chloride, acetone [bis-(2-aminoethyl)dithioacetal], and triethylamine is 1 mmol:(2-2.5) mmol:(8-10) μL; and the concentration of the tetrahydrofuran solution of 2-bipyridine-4,4-dicarboxylic acid chloride is 0.9-1 mol / L.

[0025] Preferably, the molar ratio of compound 1, compound 2, and hydrated iridium trichloride in step (3) is 1:(0.56-0.64):(0.4-0.48); and the reflux reaction time is 36-48h.

[0026] Preferably, the method for preparing the pretreated activated carbon is as follows:

[0027] The pretreated activated carbon was obtained by soaking the activated carbon in hydrochloric acid solution, washing and drying it.

[0028] Preferably, the copper salt is copper chloride; by mass percentage, the copper salt accounts for 5-15% of the mercury-free catalyst, the active agent accounts for 2-5%, and the iridium complex accounts for 0.5-3%.

[0029] The second objective of this invention is achieved by the following technical solution:

[0030] A mercury-free catalyst was prepared using the above-described method.

[0031] The third objective of this invention is achieved by the following technical solution:

[0032] The aforementioned mercury-free catalyst was applied to the preparation of vinyl chloride via the acetylene hydrochlorination process.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention provides a method for preparing a mercury-free catalyst, which is simple, easy to operate, and suitable for industrial production.

[0035] 2. The mercury-free catalyst of this invention uses activated carbon as a support, loading active agents, iridium complexes, and copper salts, and possesses advantages such as high catalytic activity, good stability, long service life, and mercury-free environmental friendliness. Specifically, the iridium complex forms a Cu-Ir bimetallic active center with Cu, producing a synergistic catalytic effect. This not only reduces the copper loading but also improves the overall catalytic activity and selectivity. Simultaneously, iridium forms a stable coordination structure with ligands (compound 1 and compound 2), enhancing the interaction with the activated carbon support and effectively inhibiting the migration and loss of Cu and Ir, thereby extending the catalyst's service life. The active agent effectively improves the dispersion of the Cu-iridium complex, preventing the aggregation of active components. Furthermore, the active agent molecule contains a diazonium naphthalene (aza-aryl ring) structure, which can synergistically interact with the amino groups and dithioketals in the iridium complex, neutralizing acidic substances generated during the reaction or interacting with the metal center, thereby reducing carbon deposition, delaying deactivation, strengthening the metal-support interaction, and improving catalyst stability. Detailed Implementation

[0036] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0037] Preparation Example 1

[0038] An active additive is prepared by the following steps:

[0039]

[0040] Under nitrogen protection, 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and 1,4-dioxane were mixed in a ratio of 1 mol: 4.05 mol: 5.5 mL: 23 L. 1,3-Divinyl-1,1,3,3-tetramethyldisiloxane (2% by mass, xylene solution) was added to 1,4-dioxane and reacted at 85°C for 20 h. After the reaction was complete, the catalyst was adsorbed onto activated carbon, the reaction solution was concentrated by rotary evaporation, and the residue was redissolved in 1,4-dioxane. The product was precipitated with n-hexane, and the precipitate was washed with acetone and dried under vacuum to obtain the active agent (yield 71.2%). The NMR and mass spectrometry results of the active agent are as follows:

[0041] 1 HNMR: (400MHz, DMSO-d6) δ: 0.14 (s, 12H), 0.59-0.63 (m, 8H), 1.49-1.53 ​​(m, 8H), 3.16-3.20 (m, 8H), 7.39- 7.43 (m, 4H), 8.37-8.41 (m, 4H), 8.48-8.52 (d, 4H), 8.68-8.72 (dd, 4H), 8.84-8.88 (dd, 4H), 8.98 (s, 4H). MS (ESI) m / z=1092.37 [M].

[0042] Preparation Example 2

[0043] An active additive is prepared by the following steps:

[0044] Under nitrogen protection, 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and 1,4-dioxane were mixed in a ratio of 1 mol:4 mol:5 mL:22 L. Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (2% by mass, xylene solution) was added to 1,4-dioxane and reacted at 80°C for 24 h. After the reaction was completed, the catalyst was adsorbed with activated carbon, the reaction solution was concentrated by rotary evaporation, the residue was redissolved in 1,4-dioxane, the product was precipitated with n-hexane, the precipitate was washed with acetone and dried under vacuum to obtain the active additive (yield 70.6%).

[0045] Preparation Example 3

[0046] An active additive is prepared by the following steps:

[0047] Under nitrogen protection, 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and 1,4-dioxane were prepared in a ratio of 1 mol: 4.1 mol: 6 mL: 25 L. Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (2% by mass, xylene solution) was added to 1,4-dioxane and reacted at 90°C for 12 h. After the reaction was completed, the catalyst was adsorbed with activated carbon, the reaction solution was concentrated by rotary evaporation, the residue was redissolved in 1,4-dioxane, the product was precipitated with n-hexane, the precipitate was washed with acetone and dried under vacuum to obtain the active additive (yield 68.9%).

[0048] Preparation Example 4

[0049] An iridium complex, the preparation method of which is as follows:

[0050]

[0051] (1) Following the ratio of 2-(4-bromomethylphenyl)pyridine, hexadecyl dimethyl tertiary amine, and tetrahydrofuran of 1 mmol: 3 mmol: 3 mL, 2-(4-bromomethylphenyl)pyridine was dissolved in tetrahydrofuran, hexadecyl dimethyl tertiary amine was added, and the mixture was reacted at room temperature for 40 h. After centrifugation, the precipitate was washed with diethyl ether and dried under vacuum to obtain compound 1 (yield 60.8%). The NMR and mass spectrometry results of compound 1 are as follows:

[0052] 1 HNMR: (400MHz, DMSO-d6) δ: 0.86-0.90 (m, 3H), 1.24-1.31 (m, 26H), 1.69-1.73 (m, 2H), 3.20-3.24 (m, 2H), 3.30 (s, 6 H), 4.50 (s, 2H), 6.88-6.92 (m, 1H), 7.12-7.16 (dd, 1H), 7.33-7.40 (m, 3H), 7.96-8.00 (m, 2H), 8.35-8.39 (dd, 1H). MS (ESI) m / z=437.39 [M].

[0053] (2) Following the ratio of 2,2-bipyridine-4,4-dicarboxylic acid chloride, acetone [bis-(2-aminoethyl)dithioacetal], triethylamine, and tetrahydrofuran of 1 mmol: 2.2 mmol: 9 μL: 3 mL, triethylamine and acetone [bis-(2-aminoethyl)dithioacetal] were dissolved sequentially in tetrahydrofuran, and a 0.95 mol / L solution of 2,2-bipyridine-4,4-dicarboxylic acid chloride in tetrahydrofuran was added. The mixture was reacted overnight at room temperature, extracted with dichloromethane / water, and the solvent was removed by rotary evaporation under reduced pressure to obtain compound 2 (yield 81.6%). The NMR and mass spectrometry results of compound 2 are as follows:

[0054] 1 HNMR: (400MHz, DMSO-d6) δ: 1.50 (s, 4H), 1.59 (s, 12H), 2.68-2.72 (m, 8H), 3.00-3.4 (m, 4H) , 3.31-3.35 (m, 4H), 7.36-7.40 (dd, 2H), 8.38 (s, 2H), 8.64-8.68 (d, 2H), 8.85-8.89 (d, 2H). MS (ESI) m / z=596.21 [M].

[0055] (3) Compound 1, Compound 2, hydrated iridium trichloride, and ethylene glycol ethyl ether were dissolved in ethylene glycol ethyl ether at a ratio of 1 mmol: 0.6 mmol: 0.45 mmol: 10 mL. The mixture was refluxed under nitrogen protection for 42 h in the dark. The solvent was removed by rotary evaporation under reduced pressure. The crude product was recrystallized to obtain the iridium complex (yield 33.1%). The NMR and mass spectrometry results of the iridium complex are as follows:

[0056] 1HNMR: (400MHz, DMSO-d6) δ: 0.86-0.90 (m, 6H), 1.24-1.31 (m, 52H), 1.5 (s, 4H), 1.59 (s, 12H), 1.69-1.73 (m, 4H), 2.68-2.72 (m, 8H), 3.00-3.04 (m, 4H), 3.20-3.24 (m, 4H), 3.28- 3.35 (m, 16H), 4.50 (s, 4H), 6.93-6.97 (m, 2H), 7.33-7.42 (m, 8H), 7.80-7.84 (dd, 2H), 8 .09-8.13 (d, 2H), 8.38 (s, 2H), 8.54-8.58 (d, 2H), 8.64-8.68 (d, 2H), 9.04-9.08 (d, 2H). MS(ESI) m / z=1661.93 [M].

[0057] Preparation Example 5

[0058] An iridium complex, the preparation method of which is as follows:

[0059] (1) 2-(4-bromomethylphenyl)pyridine, hexadecyl dimethyl tertiary amine and tetrahydrofuran were used in a ratio of 1 mmol: 2.5 mmol: 2.5 mL. 2-(4-bromomethylphenyl)pyridine was dissolved in tetrahydrofuran and hexadecyl dimethyl tertiary amine was added. The mixture was reacted at room temperature for 36 h. After centrifugation, the precipitate was washed with diethyl ether and dried under vacuum to obtain compound 1 (yield 58.2%).

[0060] (2) The ratio of 2,2-bipyridine-4,4-dicarboxylic chloride, acetone [bis-(2-aminoethyl)dithioacetal], triethylamine, and tetrahydrofuran was 1 mmol: 2 mmol: 8 μL: 2.5 mL. Triethylamine and acetone [bis-(2-aminoethyl)dithioacetal] were dissolved in tetrahydrofuran in sequence. A 0.9 mol / L solution of 2,2-bipyridine-4,4-dicarboxylic chloride in tetrahydrofuran was added. The mixture was reacted overnight at room temperature. The mixture was extracted with dichloromethane / water, and the solvent was removed by rotary evaporation of the organic phase under reduced pressure to obtain compound 2 (yield 79.9%).

[0061] (3) According to the ratio of compound 1, compound 2, hydrated iridium trichloride and ethylene glycol ethyl ether as 1 mmol: 0.56 mmol: 0.4 mmol: 8 mL, compound 1, compound 2 and hydrated iridium trichloride were dissolved in ethylene glycol ethyl ether and reacted under nitrogen protection and light-protected reflux for 36 h. The solvent was removed by rotary evaporation under reduced pressure. The crude product was recrystallized to obtain the iridium complex (yield 31.4%).

[0062] Preparation Example 6

[0063] An iridium complex, the preparation method of which is as follows:

[0064] (1) 2-(4-bromomethylphenyl)pyridine, hexadecyl dimethyl tertiary amine and tetrahydrofuran were used in a ratio of 1 mmol: 3.8 mmol: 3.3 mL. 2-(4-bromomethylphenyl)pyridine was dissolved in tetrahydrofuran and hexadecyl dimethyl tertiary amine was added. The mixture was reacted at room temperature for 48 h. After centrifugation, the precipitate was washed with diethyl ether and dried under vacuum to obtain compound 1 (yield 57.5%).

[0065] (2) The ratio of 2,2-bipyridine-4,4-dicarboxylic acid chloride, acetone [bis-(2-aminoethyl)dithioacetal], triethylamine, and tetrahydrofuran was 1 mmol: 2.5 mmol: 10 μL: 3.3 mL. Triethylamine and acetone [bis-(2-aminoethyl)dithioacetal] were dissolved in tetrahydrofuran in sequence. A 1 mol / L solution of 2,2-bipyridine-4,4-dicarboxylic acid chloride in tetrahydrofuran was added. The mixture was reacted overnight at room temperature. The mixture was extracted with dichloromethane / water. The solvent was removed by rotary evaporation of the organic phase under reduced pressure to obtain compound 2 (yield 80.1%).

[0066] (3) According to the ratio of compound 1, compound 2, hydrated iridium trichloride and ethylene glycol ethyl ether as 1:0.64mmol:0.48mmol:12mL, compound 1, compound 2 and hydrated iridium trichloride were dissolved in ethylene glycol ethyl ether and refluxed under nitrogen protection for 48h in the dark. The solvent was removed by rotary evaporation under reduced pressure. The crude product was recrystallized to obtain the iridium complex (yield 30.7%).

[0067] Example 1

[0068] A method for preparing a mercury-free catalyst includes the following steps:

[0069] Activated carbon was soaked in 2 mol / L hydrochloric acid solution for 10 h, washed with deionized water until the pH of the aqueous solution was 5.5, and dried at 100℃ for 18 h to obtain pretreated activated carbon.

[0070] Copper chloride, the active agent of Preparation Example 1, and the iridium complex of Preparation Example 4 were dissolved in ethanol to obtain a mixed solution. The mixed solution was impregnated in pretreated activated carbon using an equal-volume impregnation method, allowed to stand at room temperature for 1.5 h, and dried at 100 °C to obtain the mercury-free catalyst. By mass percentage, the mercury-free catalyst contained 10% copper chloride, 3% active agent, and 2% iridium complex.

[0071] A mercury-free catalyst was prepared using the above-described method.

[0072] Example 2

[0073] A method for preparing a mercury-free catalyst includes the following steps:

[0074] The activated carbon was soaked in a 1 mol / L hydrochloric acid solution for 8 hours, washed with deionized water until the pH of the aqueous solution was 5, and dried at 90℃ for 24 hours to obtain pretreated activated carbon.

[0075] Copper chloride, the active agent of Preparation Example 2, and the iridium complex of Preparation Example 5 were dissolved in ethanol to obtain a mixed solution. The mixed solution was impregnated in pretreated activated carbon using an equal-volume impregnation method, allowed to stand at room temperature for 1 hour, and dried at 100°C to obtain the mercury-free catalyst. By mass percentage, the proportion of copper chloride in the mercury-free catalyst was 5%, the proportion of the active agent was 2%, and the proportion of the iridium complex was 0.5%.

[0076] A mercury-free catalyst was prepared using the above-described method.

[0077] Example 3

[0078] A method for preparing a mercury-free catalyst includes the following steps:

[0079] The activated carbon was soaked in a 4 mol / L hydrochloric acid solution for 16 h, washed with deionized water until the pH of the aqueous solution was 6, and dried at 105 °C for 12 h to obtain pretreated activated carbon.

[0080] Copper chloride, the active agent of Preparation Example 3, and the iridium complex of Preparation Example 6 were dissolved in ethanol to obtain a mixed solution. The mixed solution was impregnated in pretreated activated carbon using an equal-volume impregnation method, allowed to stand at room temperature for 2 hours, and dried at 105°C to obtain the mercury-free catalyst. By mass percentage, the mercury-free catalyst contained 15% copper chloride, 5% active agent, and 3% iridium complex.

[0081] A mercury-free catalyst was prepared using the above-described method.

[0082] Comparative Example 1

[0083] The difference between Comparative Example 1 and Example 1 is that the active additive is omitted.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 1 is that hydrated iridium trichloride was used to replace the iridium complex in Example 4.

[0086] The performance of the catalyst obtained in this invention will be described below.

[0087] The performance of the mercury-free catalyst prepared in this invention was tested using a fixed-bed reactor, as detailed below:

[0088] 5g of the catalysts from Examples 1-3 and Comparative Examples 1-2 were weighed and placed in a fixed-bed reactor. The catalysts were pre-activated by introducing hydrogen chloride (HCl) at 140°C for 10 hours, and then acetylene (C2H2) was simultaneously introduced, with the C2H2 space velocity controlled at 180 h⁻¹. -1 The molar ratio of C2H2 / HCl was 1:1.1, the reaction temperature was 160℃, and the running time was 120h. The performance evaluation results of the catalyst are shown in Table 1.

[0089] Table 1

[0090]

[0091] As can be seen from Table 1, the mercury-free catalyst prepared by this invention has the advantages of high catalytic activity, good stability, and long service life.

[0092] Compared to Example 1, the performance of the mercury-free catalysts obtained in Comparative Examples 1-2 was reduced. The specific analysis is as follows: The iridium complex forms a Cu-Ir bimetallic active center with Cu, producing a synergistic catalytic effect. This not only reduces the copper loading but also improves the overall catalytic activity and selectivity. Simultaneously, iridium forms a stable coordination structure with ligands (Compound 1, Compound 2), enhancing the interaction with the activated carbon support and effectively inhibiting the migration and loss of Cu and Ir, thereby extending the catalyst's lifespan. The active agent effectively improves the dispersion of the Cu-iridium complex, preventing the aggregation of active components. Furthermore, the active agent molecule contains a diazonium naphthalene (aza-aryl ring) structure, which can synergistically interact with the amino groups and dithioketals in the iridium complex, neutralizing acidic substances generated during the reaction or interacting with the metal center, thereby reducing carbon deposition, delaying deactivation, strengthening the metal-support interaction, and improving catalyst stability.

[0093] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a mercury-free catalyst, characterized in that, Includes the following steps: A copper salt, an active agent, and an iridium complex were added to ethanol to obtain a mixed solution. The mixed solution was then impregnated into pretreated activated carbon using an equal-volume impregnation method. After standing and drying, the mercury-free catalyst was obtained. The structural formula of the active adjuvant is: ； The structural formula of the iridium complex is: 。 2. The method for preparing the mercury-free catalyst according to claim 1, characterized in that, The preparation method of the active additive is as follows: Under inert gas protection, 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazanaphthalene-2-carboxamide, and platinum catalyst were added to 1,4-dioxane, and the reaction was carried out to obtain the active additive.

3. The method for preparing the mercury-free catalyst according to claim 2, characterized in that, The ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, N-allyl-1,8-diazonyl-2-carboxamide, and platinum catalyst is 1 mol: (4-4.1) mol: (5-6) mL; the platinum catalyst is platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane; the reaction temperature is 80-90℃, and the reaction time is 12-24 h.

4. The method for preparing the mercury-free catalyst according to claim 1, characterized in that, The iridium complex is prepared as follows: (1) Add 2-(4-bromomethylphenyl)pyridine to tetrahydrofuran, then add hexadecyl dimethyl tertiary amine, and after the reaction, compound 1 is obtained; The structural formula of compound 1 is: (2) Triethylamine and acetone [bis-(2-aminoethyl)dithioacetal] were added to tetrahydrofuran, and then a tetrahydrofuran solution of 2,2-bipyridine-4,4-dicarboxyl chloride was added. After the reaction, compound 2 was obtained. The structural formula of compound 2 is: (3) The compound 1, the compound 2 and hydrated iridium trichloride were added to ethylene glycol ethyl ether and refluxed under inert gas protection to obtain the iridium complex.

5. The method for preparing the mercury-free catalyst according to claim 4, characterized in that, In step (1), the molar ratio of 2-(4-bromomethylphenyl)pyridine to hexadecyl dimethyl tertiary amine is 1:(2.5-3.8); the reaction time is 36-48 h; in step (2), the ratio of 2,2-bipyridine-4,4-dicarboxylic acid chloride, acetone [bis-(2-aminoethyl)dithioacetal], and triethylamine is 1 mmol:(2-2.5) mmol:(8-10) μL; and the concentration of the tetrahydrofuran solution of 2-bipyridine-4,4-dicarboxylic acid chloride is 0.9-1 mol / L.

6. The method for preparing the mercury-free catalyst according to claim 4, characterized in that, In step (3), the molar ratio of compound 1, compound 2, and hydrated iridium trichloride is 1:(0.56-0.64):(0.4-0.48); the reflux reaction time is 36-48h.

7. The method for preparing the mercury-free catalyst according to claim 1, characterized in that, The method for preparing the pretreated activated carbon is as follows: The pretreated activated carbon was obtained by soaking the activated carbon in hydrochloric acid solution, washing and drying it.

8. The method for preparing the mercury-free catalyst according to claim 1, characterized in that, The copper salt is copper chloride; by mass percentage, the copper salt accounts for 5-15% of the mercury-free catalyst, the active agent accounts for 2-5%, and the iridium complex accounts for 0.5-3%.

9. A mercury-free catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. An application of the mercury-free catalyst according to claim 9, characterized in that, It is used in the preparation of vinyl chloride via the acetylene hydrochlorination process.

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