CN116159579B - Acetylene hydrochlorination low-temperature mercury-free catalyst and preparation method thereof - Google Patents

Abstract

The present invention provides a low-temperature mercury-free catalyst for acetylene hydrochlorination and a preparation method thereof, and belongs to the technical field of catalyst preparation. The catalyst comprises a carrier, an active component and an auxiliary agent, wherein the carrier is a nitrogen-doped carbon nanotube, the active component is a gold precursor, a copper salt and a manganese salt, and the auxiliary agent is a boron precursor; the composite use of the nitrogen-doped carbon nanotube, the gold precursor, the copper salt, the manganese salt and the boron auxiliary agent enables the catalyst to have suitable acetylene and hydrogen chloride adsorption strength in the acetylene hydrochlorination reaction, enhances the structure and electronic properties of the active site, is conducive to promoting the redox cycle of the active site and inhibiting the catalyst from coking and deactivation, and can show excellent vinyl chloride activity, selectivity and stability at a lower reaction temperature. The catalyst provided by the present invention is green, pollution-free and simple to prepare, and is an effective catalyst for the acetylene hydrochlorination to vinyl chloride reaction, and has good industrial application prospects.

Description

A low-temperature mercury-free catalyst for acetylene hydrochlorination and preparation method thereof

Technical Field

The invention belongs to the technical field of catalyst preparation, and in particular relates to a low-temperature mercury-free catalyst for acetylene hydrochlorination and a preparation method thereof.

Background Art

As one of the top five general-purpose plastics in the world, polyvinyl chloride (PVC) has excellent properties in flame retardancy, chemical resistance, mechanical strength and electrical insulation. It is widely used in building materials, daily necessities, floor coverings, pipes, wires and cables, packaging films and other industries. In industry, PVC is mainly produced by the polymerization reaction of vinyl chloride (VCM). Based on China's energy structure of rich coal and poor oil, coal-based acetylene hydrochlorination is a key chemical process for the production of VCM and PVC in China. At present, this industrial process uses activated carbon-supported mercuric chloride (HgCl ₂ ) as a reaction catalyst. The international Minamata Convention on Mercury, which came into effect in 2017, requires the control and reduction of mercury emissions, which brings huge environmental pressure to the process. There is an urgent need to develop a green catalyst to replace the mercury-based catalyst.

The research on mercury-free catalytic systems for acetylene hydrochlorination includes two types: supported metal catalysts and metal-free catalysts. Among them, the gold catalyst supported on activated carbon (Au/C) shows high VCM activity and selectivity, and is considered to be the catalyst with the most potential to replace _HgCl2 catalyst for VCM industrial production. It is worth pointing out that compared with _HgCl2 catalyst, Au/C requires a higher reaction temperature to achieve the same acetylene conversion rate in practical applications, resulting in high energy consumption, and the catalyst often faces the problem of rapid deactivation under reaction conditions. This is partly because high-valent gold (Au ³⁺ , Au ⁺ ) has a higher reactivity. In the presence of reducing gas acetylene and high temperature, Au ³⁺ and Au ⁺ are easily reduced to zero-valent gold (Au ⁰ ) and deactivated, and promote the aggregation and growth of Au species, making it difficult to participate in further redox cycles; at the same time, acetylene is more easily adsorbed on the catalyst surface than hydrogen chloride during the reaction. If the activated acetylene does not undergo addition reaction with hydrogen chloride, it is easy to undergo polymerization reaction with each other, forming coke covering the active sites of the reaction and causing the deactivation of the catalyst; in addition, under high temperature conditions, the rate of VCM and hydrogen chloride reacting in series to produce ethylene dichloride will be significantly accelerated, causing the selectivity of VCM to decrease, resulting in the waste of acetylene and increasing the operating cost for the subsequent separation process. These factors have brought challenges to the industrial application of the catalyst. Therefore, reducing the reaction temperature of Au-based catalysts and developing low-temperature acetylene hydrochlorination catalysts are of great significance for saving energy consumption and improving catalytic reaction performance.

Chinese patent CN201510924992.1 discloses a method for preparing vinyl chloride by low-temperature acetylene hydrochlorination, using an Au-Cu composite catalyst supported on activated carbon, wherein the weight percentages of gold and copper elements to the carrier are 0.01-0.1% and 20-100%, respectively. Compared with a gold catalyst, the reaction temperature and carbon deposition rate can be reduced, thereby extending the catalyst life.

Chinese patent CN201210305820.2 discloses a Ru-Co-Cu catalyst for synthesizing vinyl chloride by hydrochlorination of acetylene, Chinese patent CN201210307780.5 discloses a Ru-Pt-Cu catalyst for synthesizing vinyl chloride by hydrochlorination of acetylene, Chinese patent CN201210305818.5 discloses a Ru-Pt-Ni catalyst for synthesizing vinyl chloride by hydrochlorination of acetylene, and Chinese patent CN201210307816.X discloses a Ru-Ni-Cu catalyst for synthesizing vinyl chloride by hydrochlorination of acetylene. The catalysts invented in the above patents can reduce the reaction temperature to below 180°C when catalyzing the synthesis of vinyl chloride by hydrochlorination of acetylene, and have good reaction product selectivity, few by-products, and high reaction activity, so that the conversion rate of acetylene exceeds 99% and the selectivity of vinyl chloride reaches 99.9%.

Therefore, the current Au-based catalysts require higher reaction temperatures to achieve higher acetylene conversion rates, which will cause a decrease in vinyl chloride product selectivity and catalyst life. There is an urgent need to develop a low-temperature mercury-free catalyst for acetylene hydrochlorination.

Summary of the invention

The present invention aims at the problems existing in the prior art and proposes a low-temperature mercury-free catalyst for acetylene hydrochlorination and a preparation method thereof. The innovation of this method lies in the use of nitrogen-doped carbon nanotubes to load active components. The addition of copper can improve the dispersion of gold and prevent the agglomeration of gold species. The addition of manganese salt strengthens the electron transfer during the reaction and inhibits the reduction of oxidized gold species to zero-valent gold, thereby having higher activity. The addition of boron additive provides electrons for the active component and promotes the adsorption of reactants and intermediate species. The catalyst prepared by the present invention exhibits excellent vinyl chloride activity and selectivity at a relatively low temperature, avoids excessively high hot spot temperatures in the bed layer and accelerates the deactivation of the catalyst, and has good industrial application prospects.

In the first aspect of the present invention, the present invention provides a low-temperature mercury-free catalyst for acetylene hydrochlorination, wherein the catalyst comprises a carrier, an active component and an additive, wherein the carrier is a nitrogen-doped carbon nanotube, and the active component comprises a gold precursor, a copper salt, a manganese salt and a boron precursor.

Wherein, in the mercury-free catalyst, the weight of gold accounts for 0.05-0.2% of the weight of the catalyst.

Wherein, in the mercury-free catalyst, the weight of copper accounts for 0.1-0.5% of the weight of the catalyst.

Wherein, in the mercury-free catalyst, the weight of manganese accounts for 0.05-0.5% of the weight of the catalyst.

Wherein, in the mercury-free catalyst, the weight of boron accounts for 0.05-1% of the weight of the catalyst.

The gold precursor is one of chloroauric acid, gold acetate, trimethylphosphine gold chloride (I), bis(1,2-ethylenediamine) gold chloride, and sodium gold thiosulfate; the copper salt is one of copper chloride, copper nitrate, and copper acetate; the manganese salt is one of manganese dichloride, manganese nitrate, and manganese gluconate; and the auxiliary agent is one or more of boric acid, 1,3-phenylenediboric acid, 4,4-biphenylenediboric acid, and dichlorophenylborane.

In a second aspect of the present invention, the present invention provides a method for preparing a low-temperature mercury-free catalyst for acetylene hydrochlorination, comprising the following steps:

1) Place the Fe/γ-Al ₂ O ₃ catalyst in a quartz boat in a horizontal tube furnace, heat it to 500-700°C in an inert atmosphere, and switch to a hydrogen atmosphere for several hours to fully reduce the catalyst;

2) The atmosphere is switched to a mixed gas of organic hydrocarbons, ammonia and hydrogen, the temperature is kept constant, after a few hours the gas is switched to an inert gas and the temperature is lowered to room temperature, and then the mixture is soaked in a sodium hydroxide solution, ultrasonicated and washed to neutrality, soaked in a hydrochloric acid solution, ultrasonicated and washed to neutrality, and dried to obtain nitrogen-doped carbon nanotubes.

3) preparing a solution of a gold precursor, a copper salt and a manganese salt, loading Au, Cu and Mn components onto the nitrogen-doped carbon nanotubes by an impregnation method or a deposition precipitation method, and obtaining a solid A after drying;

4) preparing a solution of an auxiliary boron precursor, impregnating the solid A, aging and drying the solid A to obtain a catalyst.

Preferably, the Fe/γ-Al ₂ O ₃ catalyst preparation steps in step 1) are as follows: measuring the saturated water absorption rate of γ-Al ₂ O ₃ , weighing and dissolving FeCl ₃ according to the loading amount, and impregnating, aging, drying and calcining γ-Al ₂ O ₃ to obtain the Fe/γ-Al ₂ O ₃ catalyst.

Preferably, the organic hydrocarbon in step 2) is one or more of methane, ethane, ethylene, acetylene, and propane, and the volume flow ratio of the organic hydrocarbon, ammonia, and hydrogen is 1-10:1-4:1.

Preferably, the precipitant used in the sedimentation precipitation method in step 3) is one of sodium hydroxide, urea or sodium carbonate, the temperature is 60-90° C., and the aging time is 3-9 hours.

Preferably, the temperature of the impregnation process in steps 3) and 4) is 20-35°C, the drying temperature is 100-120°C, and the drying time is 12 hours.

In a third aspect of the present invention, there is provided use of the above-mentioned low-temperature mercury-free catalyst for acetylene hydrochlorination in acetylene hydrochlorination reaction.

The application conditions are: temperature T=110-180°C, normal pressure, GHSV(C ₂ H ₂ )=40-300h ^-1 , n(HCl):n(C ₂ H ₂ )=1.05-1.2.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The active components are loaded on nitrogen-doped carbon nanotubes. The addition of copper can improve the dispersion of gold and prevent the agglomeration of gold species. The addition of manganese salt strengthens the electron transfer during the reaction and inhibits the reduction of oxidized gold species to zero-valent gold, thereby having higher activity. The addition of boron additive provides electrons for the active components and promotes the adsorption of reactants and intermediate species. The catalyst prepared by the present invention exhibits excellent vinyl chloride activity and selectivity at a relatively low temperature. Compared with other mercury-free catalysts, it can reduce energy consumption during the reaction operation.

(2) The catalyst provided by the present invention operates at a relatively low temperature, which can slow down the coking and carbon deposition of the catalyst and the loss of gold species, thereby extending the life of the catalyst and reducing the use cost of the gold catalyst.

(3) The catalyst preparation process provided by the present invention is simple and pollution-free, has high catalytic activity, and is a green mercury-free catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a nitrogen physical adsorption-desorption isotherm diagram of the catalyst prepared in Example 1;

FIG2 is an infrared spectrum of the catalyst prepared in Example 1;

FIG3 is a transmission electron micrograph of the catalyst prepared in Example 1;

FIG. 4 is an XPS spectrum of the catalyst prepared in Example 1.

DETAILED DESCRIPTION

It is worth noting that the raw materials used in the present invention are all common commercially available products, and their sources are not specifically limited.

The following is a more specific case description of catalysts:

Basic Example: Fe/γ-Al ₂ O ₃ catalyst preparation steps:

The saturated water absorption rate of γ-Al ₂ O ₃ was determined, FeCl ₃ was weighed and dissolved according to the loading amount, and the γ-Al ₂ O ₃ was impregnated, aged, dried and calcined to obtain the Fe/γ-Al ₂ O ₃ catalyst.

Example 1: A low-temperature mercury-free catalyst for acetylene hydrochlorination and its preparation method

1) 5 g of Fe/γ-Al ₂ O ₃ (Fe loading 8%) catalyst was placed in a quartz boat of a horizontal tube furnace, heated to 600° C. at 5° C./min under an argon atmosphere, and then switched to a hydrogen atmosphere for 4 hours to fully reduce the catalyst;

2) Switch the atmosphere to a mixed gas of ethane, ammonia and hydrogen with a gas volume flow ratio of 4:1:1, keep the temperature unchanged, switch the gas to argon after 8 hours and cool to room temperature, soak in a 10% sodium hydroxide solution for 4 hours, ultrasonicate and wash to neutrality, soak in a 10% hydrochloric acid solution for 4 hours, ultrasonicate and wash to neutrality, and dry at 110°C for 12 hours to obtain nitrogen-doped carbon nanotubes;

3) Weigh 25 g of nitrogen-doped carbon nanotube carrier, prepare 0.0025 g/mL of sodium gold thiosulfate, 0.0025 g/mL of copper chloride and 0.003 g/mL of manganese dichloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

4) Prepare 0.003 g/mL boric acid solution, impregnate the solid obtained by drying in the above step, age for 8 h, and dry at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold, copper, and manganese are measured to be 0.12%, 0.11%, and 0.08%, respectively, and the loading amount of the auxiliary boron is 0.15%.

Example 2: A low-temperature mercury-free catalyst for acetylene hydrochlorination and its preparation method

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1 into a beaker and add 500 mL of water and stir, prepare and add 2.8 mL of 0.012 g/mL chloroauric acid and 2.2 mL of 0.015 g/mL copper chloride solution, stir for 30 min, then drop 0.005 g/mL sodium carbonate solution, adjust the pH of the solution to 5-6, stir for 30 min, heat in a water bath to 70° C., age for 8 h, centrifuge the suspension, wash, and dry at 110° C. for 12 h;

2) A manganese dichloride solution with a concentration of 0.005 g/mL and a 1,3-phenylenediboric acid solution with a concentration of 0.006 g/mL were prepared, and the solid dried in the above step was impregnated, aged for 8 hours, and dried at 110° C. for 12 hours to obtain a catalyst, wherein the loading amounts of gold, copper, and manganese were measured to be 0.12%, 0.11%, and 0.08%, respectively, and the loading amount of the auxiliary boron was 0.15%.

Example 3: A low-temperature mercury-free catalyst for acetylene hydrochlorination and its preparation method

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1, prepare 0.0025 g/mL of gold acetate and 0.004 g/mL of copper acetate solution, co-impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) preparing 0.0025 g/mL manganese nitrate solution and 0.006 g/mL 4,4-biphenyl diboric acid solution, impregnating the solid dried in the above step, aging for 8 h, and drying at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold, copper, and manganese are measured to be 0.12%, 0.10%, and 0.15%, respectively, and the loading amount of boron is 0.08%;

Example 4: A low-temperature mercury-free catalyst for acetylene hydrochlorination and its preparation method

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1, prepare a solution of 0.0025 g/mL trimethylphosphine gold (I) chloride and 0.004 g/mL copper nitrate, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) preparing a manganese gluconate solution with a concentration of 0.02 g/mL and a dichlorophenyl borane solution with a concentration of 0.006 g/mL, impregnating the solid obtained after drying in the above step, aging, and drying at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold, copper, and manganese are measured to be 0.12%, 0.12%, and 0.10%, respectively, and the loading amount of boron is 0.06%;

Comparative Example 1:

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1, prepare 0.0025 g/mL of sodium gold thiosulfate solution and 0.003 g/mL of manganese dichloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) Prepare 0.003 g/mL boric acid solution, impregnate the solid dried in the above step, age for 8 hours, and dry at 110° C. for 12 hours to obtain a catalyst, wherein the gold loading is 0.12%, the manganese loading is 0.08%, and the auxiliary boron loading is 0.15%.

Comparative Example 2:

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1, prepare 0.0025 g/mL of sodium gold thiosulfate and 0.0025 g/mL of cupric chloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) Prepare 0.003 g/mL boric acid solution, impregnate the solid dried in the above step, age for 8 h, and dry at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold and copper are measured to be 0.12% and 0.11%, respectively, and the loading amount of the auxiliary boron is 0.15%.

Comparative Example 3:

1) Weigh 25 g of the nitrogen-doped carbon nanotube carrier in Example 1, prepare 0.0025 g/mL of sodium gold thiosulfate, 0.0025 g/mL of copper chloride and 0.003 g/mL of manganese dichloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h; the loading amounts of gold, copper and manganese are measured to be 0.12%, 0.11% and 0.08%, respectively.

Comparative Example 4:

1) 5 g of Fe/γ-Al ₂ O ₃ (Fe loading 8%) catalyst was placed in a quartz boat of a horizontal tube furnace, heated to 600° C. at 5° C./min under an inert atmosphere, and then switched to a hydrogen atmosphere for 4 hours to fully reduce the catalyst;

2) The atmosphere was switched to a mixed gas of ethane and hydrogen with a gas flow ratio of 4:1, the temperature was kept constant, and after 8 hours, the gas was switched to an inert gas and the temperature was lowered to room temperature, and the carbon nanotubes were obtained after soaking, ultrasonication and washing to neutrality in a 10%wt sodium hydroxide solution, soaking, ultrasonication and washing to neutrality in a 10%wt hydrochloric acid solution, and drying at 110°C for 12 hours;

3) Weigh 25 g of the carbon nanotube carrier, prepare 0.0025 g/mL of sodium gold thiosulfate, 0.0025 g/mL of copper chloride and 0.003 g/mL of manganese dichloride solution, impregnate the carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

4) Prepare 0.003 g/mL boric acid solution, impregnate the solid obtained by drying in the above step, age for 8 h, and dry at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold, copper, and manganese are measured to be 0.12%, 0.11%, and 0.08%, respectively, and the loading amount of the auxiliary boron is 0.15%.

Comparative Example 5:

1) Weigh 25 g of nitrogen-doped carbon nanotube carrier, prepare 0.0025 g/mL sodium gold thiosulfate and 0.007 g/mL manganese dichloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) Prepare 0.003 g/mL boric acid solution, impregnate the solid dried in the above step, age for 8 h, and dry at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold and manganese are measured to be 0.12% and 0.19%, respectively, and the loading amount of the auxiliary boron is 0.15%.

Comparative Example 6:

1) Weigh 25 g of nitrogen-doped carbon nanotube carrier, prepare 0.0025 g/mL sodium gold thiosulfate and 0.006 g/mL copper chloride solution, impregnate the nitrogen-doped carbon nanotubes, age for 8 h, and dry at 110° C. for 12 h;

2) Prepare 0.003 g/mL boric acid solution, impregnate the solid dried in the above step, age for 8 h, and dry at 110° C. for 12 h to obtain a catalyst, wherein the loading amounts of gold and copper are measured to be 0.12% and 0.19%, respectively, and the loading amount of the auxiliary boron is 0.15%.

For the above examples 1-4 and comparative examples

The catalyst in 1-6 was used to evaluate the performance of acetylene hydrochlorination reaction. The evaluation conditions were temperature of 140°C, space velocity of 120h ^-1 , feed gas C ₂ H ₂ :HCl=1:1.1. The acetylene conversion rate was 88.7% at the initial stage of the reaction, and the vinyl chloride selectivity was greater than 99%. After the reaction was run for 500h, the acetylene conversion rate on the catalyst was 80.9%.

The summary results of the catalytic performance test are shown in Table 1:

Table 1 Comparison of catalyst performance of Examples 1-4 and Comparative Examples 1-6

Test items Initial conversion rate of acetylene (%) Vinyl chloride selectivity (%) Acetylene conversion after 500h (%) Example 1 98.3 >99% 97.2 Example 2 97.2 >99% 95.5 Example 3 96.9 >99% 94.1 Example 4 96.4 >99% 93.8 Comparative Example 1 83.5 >99% 80.5 Comparative Example 2 85.3 >99% 81.4 Comparative Example 3 88.2 >99% 82.6 Comparative Example 4 84.1 >99% 77.8 Comparative Example 5 87.2 >99% 83.2 Comparative Example 6 91.0 >99% 86.9

By comparing Examples 1-4 and Comparative Examples 1-6, the following conclusions can be drawn:

Comparison between Examples 1-4 and Comparative Example 1 shows that when the metallic copper component is absent, the activity of the acetylene hydrochlorination reaction is relatively low, and the catalyst activity decreases significantly after 500 hours of reaction.

Comparison between Examples 1-4 and Comparative Example 2 shows that when the metal manganese component is missing, the activity of the acetylene hydrochlorination reaction is relatively low, and the catalyst activity decreases significantly after 500 hours of reaction;

Comparison between Examples 1-4 and Comparative Example 3 shows that when the auxiliary boron component is missing, the activity of acetylene hydrochlorination is relatively low, and the catalyst activity decreases significantly after 500 hours of reaction;

Comparison between Examples 1-4 and Comparative Example 4 shows that when carbon nanotubes not doped with nitrogen are used as carriers to load active components and additives, the activity of acetylene hydrochlorination is relatively low, and the catalyst activity decreases significantly after 500 hours of reaction.

Comparison between Example 1 and Comparative Examples 5-6 shows that the reaction performance of using only manganese or only copper at the same loading amount is not as good as using both manganese and copper, indicating that there is a synergistic effect between copper and manganese.

The solutions of the present invention are not limited to the technical means disclosed by the above technical means, but also include technical solutions composed of any combination of the above technical features. The above is a specific implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (8)

1. The low-temperature mercury-free catalyst for hydrochlorination of acetylene is characterized in that: the acetylene hydrochlorination low-temperature mercury-free catalyst consists of a carrier, an active component and an auxiliary agent, wherein the carrier is a nitrogen-doped carbon nano tube;

The preparation method of the acetylene hydrochlorination low-temperature mercury-free catalyst comprises the following steps:

1) Placing the Fe/gamma-Al ₂O₃ catalyst in a quartz boat of a horizontal tube furnace, heating to 500-700 ℃ under an inert atmosphere, switching to a hydrogen atmosphere, and keeping for 3 hours, and fully reducing the catalyst;

2) Switching the atmosphere into a mixed gas of organic hydrocarbon, ammonia and hydrogen, keeping the temperature unchanged, switching the gas into inert gas after a few hours, cooling to room temperature, soaking in sodium hydroxide solution, performing ultrasonic treatment and washing to neutrality, soaking in hydrochloric acid solution, performing ultrasonic treatment and washing to neutrality, and drying to obtain the nitrogen-doped carbon nanotube;

3) Preparing a solution of a gold precursor, copper salt and manganese salt, loading Au, cu and Mn components onto the nitrogen-doped carbon nano tube by adopting an immersion method or a deposition precipitation method, and drying to obtain a solid A;

4) Preparing a solution of an auxiliary agent boron precursor, and carrying out impregnation, aging and drying on the solid A to obtain a catalyst;

The gold precursor is one of chloroauric acid, gold acetate, trimethylphosphine gold (I) chloride and bis (1, 2-ethylenediamine) gold chloride, and gold sodium thiosulfate; the auxiliary agent is one or more of boric acid, 1, 3-phenyldiboronic acid, 4-biphenyldiboronic acid and dichlorobenzene borane; the weight of gold is 0.05-0.2% of the weight of the catalyst, the weight of copper is 0.1-0.5% of the weight of the catalyst, the weight of manganese is 0.05-0.5% of the weight of the catalyst, and the weight of boron is 0.05-1% of the weight of the catalyst.

2. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the diameter of the nitrogen-doped carbon nano tube is 5-20nm, and the specific surface area is 200-800m ²/g.

3. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the copper salt is one of copper chloride, copper nitrate and copper acetate; the manganese salt is one of manganese dichloride, manganese nitrate and manganese gluconate.

4. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the organic hydrocarbon in the step 2) is one or more of methane, ethane, ethylene, acetylene and propane, and the volume flow ratio of the organic hydrocarbon to the ammonia to the hydrogen is 1-10:1-4:1.

5. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the precipitant used in the deposition precipitation method in the step 3) is one of sodium hydroxide, urea or sodium carbonate, the temperature is 60-90 ℃, and the aging time is 3-9h.

6. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the temperature of the dipping process in the steps 3) and 4) is 20-35 ℃, the drying temperature is 100-120 ℃ and the drying time is 12 hours.

7. The acetylene hydrochlorination low temperature mercury-free catalyst of claim 1, wherein: the preparation steps of the Fe/gamma-Al ₂O₃ catalyst in the step 1) are as follows: and measuring the saturated water absorption of gamma-Al ₂O₃, weighing FeCl ₃ according to the load capacity, dissolving, and carrying out impregnation, ageing, drying and roasting on gamma-Al ₂O₃ to obtain the Fe/gamma-Al ₂O₃ catalyst.

8. Use of the low temperature mercury-free catalyst for hydrochlorination of acetylene according to any one of claims 1 to 7 in hydrochlorination of acetylene.