A dehydrochlorination catalyst, a preparation method and application thereof in synthesis of 1,1,2-trichloroethylene from 1,1,2,2-tetrachloroethane

Abstract

The application discloses a dehydrochlorination catalyst and a preparation method and application thereof in synthesis of 1,1,2-trichloroethylene from 1,1,2,2-tetrachloroethane. The preparation method of the dehydrochlorination catalyst comprises the following steps: A1, pretreating activated carbon with acid or alkali to obtain pretreated activated carbon; A2, adding a pore-forming agent to the activated carbon, and then performing high-temperature calcination after standing; A3, preparing a metal salt aqueous solution, taking the activated carbon and adding the same into the metal salt aqueous solution, and then performing room-temperature impregnation to obtain a product; subsequently, performing freeze-drying to obtain the product; A4, placing the product in the step A3 into a tubular furnace, introducing a reducing gas containing hydrogen to reduce the metal salt into metal elements, and then introducing HCl gas to react with the metal elements to generate metal chlorides, so that the dehydrochlorination catalyst is obtained. The application further provides application of the dehydrochlorination catalyst in synthesis of 1,1,2-trichloroethylene from 1,1,2,2-tetrachloroethane, and the dehydrochlorination catalyst has good catalytic activity and stability.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically relating to a dehydrochlorination catalyst and its preparation method, and its application in the synthesis of 1,1,2,2-trichloroethylene from 1,1,2,2-tetrachloroethane. Background Technology

[0002] Trichloroethylene is widely used in refrigerant raw materials, cleaning agents, and chemical intermediates. Furthermore, it is a high-performance organic chlorine solvent with broad applications in precision machinery, microelectronics, chemicals, and pharmaceuticals. Chlorinated alkenes are one of the important routes for large-scale C-Cl to CF conversion to synthesize fluoroalkanes. With the banning of ozone-depleting refrigerants such as chloroalkanes in recent years, the demand for their substitutes, such as fluoroalkanes, has grown rapidly. Therefore, the application prospects of trichloroethylene are becoming increasingly broad.

[0003] Currently, the main method for producing trichloroethylene is the acetylene-saponification method. This method uses calcium carbide acetylene as raw material and solid ferric chloride as a catalyst. Under negative pressure, the molar ratio of acetylene to chlorine is 1:1.01, and the temperature is 90–130℃. Liquid-phase chlorination is carried out in a chlorination tower to obtain tetrachloroethane. Tetrachloroethane is then reacted with lime at a mass ratio of 1:1.45 at 80–100℃ to produce trichloroethylene, which is then obtained through crude distillation and rectification to obtain the final product. However, due to problems such as limited raw material sources and difficulties in treating waste, this method has been gradually phased out.

[0004] In addition, the oxychlorination of dichloroethane is also a relatively common method. However, this preparation method involves complex reactions and is difficult to control. Therefore, it has not been widely used in industrial production. The gas-phase catalytic dehydrochlorination of tetrachloroethane, with its advantages of low reaction temperature, low waste, and simple process, is gradually becoming the mainstream process in industrial production. Currently, activated carbon or activated carbon-supported metal sulfate / BaCl2 catalysts are the most studied dehydrochlorination catalysts.

[0005] The invention disclosed in CN101032690 presents a highly active catalyst for the gas-phase catalytic dehydrochlorination of chloroalkanes to produce chloroolefins and its preparation method. The method involves pretreating activated carbon at high temperature, then impregnating the activated carbon with active components such as alkali metal sulfates (Na₂SO₄, K₂SO₄, etc.), followed by drying at 110–140 °C for 6 h to obtain the catalyst. This catalyst was applied to the gas-phase catalytic dehydrochlorination of chloroalkanes to produce chloroolefins and exhibits high catalytic activity, high feed conversion rate, and high stability. However, existing research indicates that these types of catalysts still suffer from poor catalytic activity and low stability. Summary of the Invention

[0006] To address the issues of raw material sourcing, waste treatment, and low activity in the acetylene-saponification process, this invention proposes a dehydrochlorination catalyst, its preparation method, and its application in the synthesis of 1,1,2,2-trichloroethylene from 1,1,2,2-tetrachloroethane.

[0007] In a first aspect, the present invention provides a method for preparing a dehydrochlorination catalyst, comprising the following steps:

[0008] A1. Add activated carbon to a 5-10 wt% HNO3 solution or a 5-10 wt% NH3·H2O solution and reflux at a temperature of 50-80℃ for 5-10 h. After reflux, wait for the temperature to drop to room temperature, filter with deionized water and wash until neutral, then dry to obtain pretreated activated carbon.

[0009] A2. Add a pore-forming agent to the activated carbon, let it stand for 2-6 hours, then transfer it to a tube furnace and heat it to 400-800℃ at a rate of 1-10℃ / min under an inert atmosphere, with a gas flow rate of 20-60mL / min, and maintain the temperature for 2-8 hours; the pore-forming agent is one of water, polyethylene glycol, polyvinyl alcohol, and polyacrylamide, or a combination of water and any one of polyethylene glycol, polyvinyl alcohol, and polyacrylamide.

[0010] A3. Prepare an aqueous solution of a metal salt, wherein the solute in the metal salt solution is one of Zn(NO3)2, Ba(NO3)2, and CsNO3, or a combination of Zn(NO3)2 and one of Ba(NO3)2 and CsNO3. Add the activated carbon obtained in A2 to the solution and impregnate at room temperature for 5-10 hours to obtain the product. Subsequently, freeze-dry the product to obtain the product. The mass ratio of the activated carbon to the metal salt is 10-40:1.

[0011] A4. Place the product from A3 into a tube furnace, and introduce a reducing gas containing hydrogen to reduce the metal salt to the elemental metal. The reduction conditions are: heating to 300-800℃ at a rate of 1-10℃ / min in a H2 / Ar mixed gas with a gas flow rate of 20-60 mL / min, and holding at that temperature for 2-5 h; then introduce HCl gas to react with the elemental metal to generate metal chloride. The reaction conditions are: introducing HCl gas at a gas flow rate of 20-60 mL / min, and reacting at room temperature to 800℃ for 0.1-3 h, thereby obtaining a dehydrochlorination catalyst.

[0012] Preferably, the activated carbon in step A1 is either wood-based charcoal or coconut shell charcoal.

[0013] Preferably, in step A1, the ratio of activated carbon to HNO3 solution or NH3·H2O solution is 1g:20-50mL.

[0014] Preferably, the mass ratio of activated carbon to pore-forming agent in step A2 is 1:2-4.

[0015] Preferably, the inert atmosphere in step A2 is one of nitrogen, argon, or helium.

[0016] Preferably, after the A2 step treatment, the activated carbon is predominantly microporous, with a micropore ratio greater than 90% and a specific surface area of ​​800–1000 m². 2 / g, with an average pore size between 1.0nm and 1.5nm, and the number of oxygen-containing functional groups on the surface between 0 and 1.0wt% based on oxygen content.

[0017] Preferably, in step A3, the metal salt is a combination of Zn(NO3)2 and one of Ba(NO3)2 and CsNO3, wherein the mass ratio of Zn(NO3)2 to one of Ba(NO3)2 and CsNO3 is 1:0.5-1.5.

[0018] Preferably, the freeze-drying conditions in step A3 are: freeze-drying the impregnated product at -30 to -50°C for 20-30 hours.

[0019] In step A4 of this invention, the hydrogen-containing reducing gas is preferably an H2 / Ar mixture, wherein the volume percentage of hydrogen is 5-10%, more preferably 5%.

[0020] The reduction conditions in step A4 of this invention depend on the metal. When the metal is Zn, the preferred reduction conditions are: heating to 300-400°C at a rate of 1-10°C / min in an H2 / Ar mixture with a gas flow rate of 20-60 mL / min, and holding at that temperature for 2-5 hours. When the metal is one of Ba and Cs3, or a combination of Zn and one of Ba and Cs, the preferred reduction conditions are: heating to 300-400°C at a rate of 1-10°C / min in an H2 / Ar mixture with a gas flow rate of 20-60 mL / min, and holding at that temperature for 1-3 hours; subsequently, heating to 400-800°C at a rate of 1-10°C / min, and holding at that temperature for 1-3 hours.

[0021] In step A4 of this invention, the reaction temperature of HCl gas with the metallic element also depends on the metal. When the metal is Cs or a combination of Zn and Cs, the preferred reaction conditions for generating the metal chloride are: HCl gas is introduced at a flow rate of 20-60 mL / min at room temperature and maintained for 0.1-3 h. When the metal is Zn or a combination of Zn and Ba, the preferred reaction conditions for generating the metal chloride are: HCl gas is introduced at a flow rate of 20-60 mL / min at room temperature and maintained for 0.1-1 h, then the temperature is increased to 400-800 °C at a rate of 1-10 °C / min and maintained for 0.1-1 h. When the metal is Ba, the preferred reaction conditions for generating the metal chloride are: HCl gas is introduced at a flow rate of 20-60 mL / min at room temperature, the temperature is increased to 400-800 °C at a rate of 1-10 °C / min and maintained for 0.1-1 h.

[0022] Secondly, the present invention provides a dehydrochlorination catalyst prepared according to the preparation method described in the first aspect. The dehydrochlorination catalyst comprises a support and an active component supported on the support, wherein the support is activated carbon; and the active component includes metal chlorides.

[0023] Thirdly, the present invention proposes the application of the dehydrochlorination catalyst described in the second aspect in the synthesis of 1,1,2,2-trichloroethylene from 1,1,2,2-tetrachloroethane.

[0024] The application steps are as follows:

[0025] B1. Pack an appropriate amount of quartz wool into the reaction tube. Weigh a certain mass of dehydrochlorination catalyst and pack it into the reaction tube lined with quartz wool. The particle size ratio of the reaction tube to the catalyst should be 10-20. Then raise the temperature of the reaction tube to 150-250℃. After the temperature stabilizes, use nitrogen or argon as a carrier gas to carry the vaporized 1,1,2,2-tetrachloroethane into the reactor. The carrier gas flow rate should be 20-60 mL / min, and the feed space velocity should be 7000-15000 h⁻¹. -1 .

[0026] B2. After passing through a condenser, the product enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and then analyzed by an Agilent gas chromatograph. The gaseous product HCl is absorbed by an alkaline solution.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. Pretreatment of activated carbon supports with acid or alkali enhances or weakens the acidity of the support surface, which is beneficial to improving catalyst activity. In addition, it effectively reduces the oxygen-containing functional groups on the catalyst surface, resulting in a lower concentration of oxygen-containing functional groups, which is more conducive to improving catalytic activity. At the same time, the pore-forming treatment increases the specific surface area, pore volume, and pore size of the support, which is beneficial to improving catalyst activity.

[0029] 2. In the catalyst preparation process, activated carbon and active components are directly impregnated, and the catalyst is dried by freeze drying, which avoids the problem of active components being lost with the evaporation of deionized water during heating and drying.

[0030] 3. The dehydrochlorination catalyst of the present invention has excellent catalytic activity in the dehydrochlorination of 1,1,2,2-tetrachloroethane to trichloroethylene, and can maintain high conversion rate and selectivity even after long-term use. Detailed Implementation

[0031] The following examples are only used to further illustrate the present invention, but the scope of protection of the present invention is not limited thereto.

[0032] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0033] The activated carbon used in the examples was purchased from Wenzhou Feiruide Trading Co., Ltd., and its model number is 3SW.

[0034] Example 1

[0035] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0036] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0037] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0038] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0039] Example 2

[0040] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0041] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0042] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0043] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0044] Example 3

[0045] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0046] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 96% and a specific surface area of ​​950 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0047] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0048] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0049] Example 4

[0050] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0051] Step 2: Removal of oxygen-containing groups: Add 20g of polyvinyl alcohol to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350℃ at a rate of 1℃ / min and hold for 2 hours. Continue heating to 600℃ and hold for 4 hours. BET characterization analysis showed a micropore ratio of 94% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0052] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0053] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0054] Example 5

[0055] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0056] Step 2: Removal of oxygen-containing groups: Add 10 mL of water and 10 g of polyvinyl alcohol to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0057] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0058] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0059] Example 6

[0060] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0061] Step 2: Removal of oxygen-containing groups: Add 10 mL of water and 10 g of polyacrylamide to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​860 m². 2 / g, with an average pore size of 1.0nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0062] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0063] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0064] Example 7

[0065] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 10wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 3, indicating an increase in the number of weakly acidic sites.

[0066] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 10 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore content of 90% and a specific surface area of ​​800 m². 2 / g, with an average pore size of 1.2nm, and the number of oxygen-containing groups on the surface was determined to be 0.1wt% (based on O content) by VarioEL analyzer.

[0067] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0068] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 5°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0069] Example 8

[0070] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0071] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0072] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then impregnate 5g activated carbon in it, and impregnate at room temperature for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0073] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar), and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour, and then allowed to cool naturally to room temperature.

[0074] Example 9

[0075] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0076] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0077] Step 3: Loading of active components: Take 0.250g Ba(NO3)2 in a beaker, add 10mL of water, and after the solid is completely dissolved, 5g of activated carbon is impregnated in it. The product is obtained by impregnation at room temperature for 5h, and then freeze-drying at -50℃ for 24h.

[0078] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace, and the temperature is increased to 500°C at a rate of 1°C / min for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0079] Example 10

[0080] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0081] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 91% and a specific surface area of ​​900 m². 2 / g, with an average pore size of 1.0nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0082] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then impregnate 5g activated carbon in it, and impregnate at room temperature for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0083] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar), and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour, and then allowed to cool naturally to room temperature.

[0084] Example 11

[0085] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0086] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0087] Step 3: Loading of active components: Take 0.250g Ba(NO3)2 in a beaker, add 10mL of water, and after the solid is completely dissolved, 5g of activated carbon is impregnated in it. The product is obtained by impregnation at room temperature for 5h, and then freeze-drying at -50℃ for 24h.

[0088] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace, and the temperature is increased to 500°C at a rate of 1°C / min for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0089] Example 12

[0090] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0091] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0092] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0093] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0094] Example 13

[0095] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0096] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 91% and a specific surface area of ​​900 m². 2 / g, with an average pore size of 1.0nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0097] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0098] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0099] Example 14

[0100] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0101] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​850 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0102] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0103] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0104] Example 15

[0105] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0106] Step 2: Removal of oxygen-containing groups: Add 20g of polyvinyl alcohol to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350℃ at a rate of 1℃ / min and hold for 2 hours. Continue heating to 600℃ and hold for 4 hours. BET characterization analysis showed a micropore ratio of 94% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0107] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0108] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0109] Example 16

[0110] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0111] Step 2: Removal of oxygen-containing groups: Add 10 mL of water and 10 g of polyvinyl alcohol to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0112] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0113] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0114] Example 17

[0115] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 7.5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 1, indicating an increase in the number of weakly acidic sites.

[0116] Step 2: Removal of oxygen-containing groups: Add 10 mL of water and 10 g of polyacrylamide to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​860 m². 2 / g, with an average pore size of 1.0nm, and the number of oxygen-containing groups on the surface was determined to be 0.2wt% (based on O content) by VarioEL analyzer.

[0117] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0118] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0119] Example 18

[0120] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 10wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 3, indicating an increase in the number of weakly acidic sites.

[0121] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 10 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore content of 90% and a specific surface area of ​​800 m². 2 / g, with an average pore size of 1.2nm, and the number of oxygen-containing groups on the surface was determined to be 0.1wt% (based on O content) by VarioEL analyzer.

[0122] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.250g CsNO3 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0123] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0124] Example 19

[0125] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 10wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized by NH3-TPD. The area of ​​the NH3 desorption peak at low temperature was larger after alkali pretreatment than that in Example 3, indicating an increase in the number of weakly acidic sites.

[0126] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 90% and a specific surface area of ​​900 m². 2 / g, with an average pore size of 1.2nm, and the number of oxygen-containing groups on the surface was determined to be 0.1wt% (based on O content) by VarioEL analyzer.

[0127] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then impregnate 5g activated carbon in it, and impregnate at room temperature for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0128] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar), and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour, and then allowed to cool naturally to room temperature.

[0129] Example 20

[0130] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0131] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0132] Step 3: Loading of active components: Take 0.250g of CsNO3 in a beaker, add 10mL of water, and after the solid is completely dissolved, 5g of activated carbon is impregnated in it. The product is obtained by impregnation at room temperature for 5h, and then freeze-drying at -50℃ for 24h.

[0133] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0134] Example 21

[0135] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0136] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0137] Step 3: Loading of active components: Take 0.250g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then impregnate 5g activated carbon in it, and impregnate at room temperature for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0138] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar), and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour, and then allowed to cool naturally to room temperature.

[0139] Example 22

[0140] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% HNO3 solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. Acid pretreatment resulted in a new NH3 desorption peak at 200–250℃, indicating an increase in the number of strongly acidic sites.

[0141] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 93% and a specific surface area of ​​930 m². 2 / g, with an average pore size of 1.3nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0142] Step 3: Loading of active components: Take 0.250g of CsNO3 in a beaker, add 10mL of water, and after the solid is completely dissolved, 5g of activated carbon is impregnated in it. The product is obtained by impregnation at room temperature for 5h, and then freeze-drying at -50℃ for 24h.

[0143] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) and held for 2 hours. Then, the temperature is increased to 400°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0144] Comparative Example 1

[0145] Compared with Example 1, Comparative Example 1 differs in that the activated carbon does not remove oxygen-containing groups and does not undergo pore-forming treatment, while the other treatment methods are exactly the same as those in Example 1.

[0146] Step 1: Activated Carbon Pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acidity of the activated carbon surface was characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites. BET characterization analysis showed a micropore ratio of 88% and a specific surface area of ​​600m². 2 / g, with an average pore size of 0.6nm, and the number of oxygen-containing groups on the surface was determined to be 1.5wt% (based on O content) by VarioEL analyzer.

[0147] Step 2: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g Ba(NO3)2 in it, then impregnate 5g activated carbon in it, impregnate at room temperature for 5h to obtain the product, and then freeze dry at -50℃ for 24h to obtain the product.

[0148] Step 3: Reduction and chlorination of active components: The product from Step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0149] Comparative Example 2

[0150] Compared with Example 1, Comparative Example 2 differs in that the active component is not chlorinated, while the rest of the treatment is exactly the same as in Example 1.

[0151] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0152] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to 10 g of activated carbon, let stand for 2 h, then transfer to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 h. Continue heating to 600 °C and hold for 4 h. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0153] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g CsNO3 in it, and then impregnate 5g activated carbon in it for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0154] Step 4: Reduction of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar), held for 2 hours, then heated to 400°C at a rate of 1°C / min, held for 2 hours, and then allowed to cool naturally to room temperature.

[0155] Comparative Example 3

[0156] Compared with Example 1, Comparative Example 3 differs in that the drying method is changed to a forced-air drying oven, while the other treatment methods are exactly the same as those in Example 1.

[0157] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0158] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated activated carbon, let it stand for 2 hours, then transfer it to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 hours. Continue heating to 600 °C and hold for 4 hours. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0159] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O and 0.125g Ba(NO3)2 into a beaker, add 20mL of deionized water, and then immerse 5g of activated carbon in it. Immerse for 5h to obtain the product. Then, dry in a forced-air drying oven at 110℃ for 24h to obtain the product.

[0160] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0161] Comparative Example 4

[0162] Compared with Example 1, Comparative Example 5 differs in that the carrier is Al2O3, while the other treatment methods are exactly the same as those in Example 1.

[0163] Step 1: Al2O3 pretreatment: 10g of Al2O3 was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature, filtered with deionized water and washed until neutral, and dried at 100℃ for 24h to obtain pretreated Al2O3. The acid properties of the Al2O3 surface were characterized by NH3-TPD. After alkali pretreatment, the NH3 desorption peak of Al2O3 at low temperature increased significantly, indicating an increase in the number of weakly acidic sites.

[0164] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to the treated Al₂O₃, let stand for 2 h, then transfer to a tube furnace. Heat to 350 °C at a rate of 1 °C / min under a nitrogen atmosphere, hold for 2 h, then continue heating to 600 °C and hold for 4 h. BET characterization analysis showed a micropore ratio of 60% and a specific surface area of ​​200 m² / g. 2 / g, with an average pore size of 0.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.8wt% (based on O content) by VarioEL analyzer.

[0165] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O and 0.125g Ba(NO3)2 into a beaker, add 20mL of deionized water, and then immerse 5g Al2O3 in it. Immerse for 5h to obtain the product. Then, dry in a forced-air drying oven at 110℃ for 24h to obtain the product.

[0166] Step 4: Reduction and chlorination of active components: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a hydrogen-argon mixture (5% H2 + 95% Ar) for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The product is then allowed to cool naturally to room temperature.

[0167] Comparative Example 5

[0168] Compared with Example 1, Comparative Example 5 differs in that the active component is not reduced, while the rest of the treatment is exactly the same as that in Example 1.

[0169] Step 1: Activated carbon pretreatment: 10g of activated carbon was added to 300mL of 5wt% NH3·H2O solution and refluxed at 50℃ for 10h. After reflux, the temperature was allowed to drop to room temperature. The activated carbon was then filtered with deionized water and washed until neutral. It was dried at 100℃ for 24h to obtain pretreated activated carbon. The acid properties of the activated carbon surface were characterized using NH3-TPD. After alkali pretreatment, the NH3 desorption peak at low temperature significantly increased, indicating an increase in the number of weakly acidic sites.

[0170] Step 2: Removal of oxygen-containing groups: Add 20 mL of water to 10 g of activated carbon, let stand for 2 h, then transfer to a tube furnace. Under a nitrogen atmosphere, heat to 350 °C at a rate of 1 °C / min and hold for 2 h. Continue heating to 600 °C and hold for 4 h. BET characterization analysis showed a micropore ratio of 95% and a specific surface area of ​​940 m². 2 / g, with an average pore size of 1.5nm, and the number of oxygen-containing groups on the surface was determined to be 0.5wt% (based on O content) by VarioEL analyzer.

[0171] Step 3: Loading of active components: Take 0.125g Zn(NO3)2·6H2O in a beaker, heat to 50℃ to dissolve it, then dissolve 0.125g Ba(NO3)2 in it, and then impregnate 5g activated carbon in it for 5h to obtain the product. Subsequently, freeze dry at -50℃ for 24h to obtain the product.

[0172] Step 4: Chlorination of the active component: The product from step 3 is transferred to a tube furnace and heated to 300°C at a rate of 1°C / min under a nitrogen atmosphere, and held for 2 hours. Then, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours. After cooling to room temperature, HCl gas is introduced into the furnace and held for 1 hour. Subsequently, the temperature is increased to 500°C at a rate of 1°C / min and held for 1 hour. The furnace is then allowed to cool naturally to room temperature.

[0173] Example 23

[0174] The catalysts from Examples 1-22 were respectively loaded into a fixed-bed reactor. The reaction tube was 500 mm long and 40 mm in inner diameter. The amount of catalyst used in Examples 1-22 was 10.0 g. Quartz wool was placed at the bottom of the catalyst bed, and quartz wool and quartz sand were placed at the top. The particle size ratio of the reaction tube to the catalyst was 15, and the reaction temperature was 230 °C. After the temperature stabilized, nitrogen or argon was used as the carrier gas to carry the vaporized 1,1,2,2-tetrachloroethane into the reactor. The carrier gas flow rate was 30 mL / min, and the feed space velocity was 10000 h⁻¹. -1 The product, after passing through a condenser, enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and analyzed by an Agilent gas chromatograph. The gaseous product, HCl, is absorbed by an alkaline solution. The reaction results are detailed in Table 1.

[0175] Comparative Example 6

[0176] The reaction was carried out in a fixed-bed reactor with a reaction tube 500 mm long and 40 mm inner diameter. The catalyst dosage for Comparative Examples 1-5 was 10.0 g. Quartz wool was placed at the bottom of the catalyst bed, and quartz wool and quartz sand were placed at the top. The particle size ratio of the reaction tube to the catalyst was 15. The reaction temperature was 230℃. After the temperature stabilized, nitrogen or argon was used as the carrier gas to introduce the vaporized 1,1,2,2-tetrachloroethane into the reactor at a flow rate of 30 mL / min. The feed space velocity was 10000 h⁻¹. -1 The product, after passing through a condenser, enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and analyzed by an Agilent gas chromatograph. The gaseous product, HCl, is absorbed by an alkaline solution. The reaction results are detailed in Table 2.

[0177] Example 24

[0178] Referring to the reaction conditions of Example 23, the reaction time was extended, and the stability of the catalyst in Example 4 was tested. The reaction results are detailed in Table 3.

[0179] Table 1. Catalytic performance results of catalysts prepared in Examples 1-22

[0180]

[0181]

[0182] Table 2. Catalytic performance results of catalysts prepared in Comparative Examples 1-5

[0183] Conversion rate / % Selectivity / % Comparative Example 1 86.2 93.5 Comparative Example 2 79.0 88.5 Comparative Example 3 92.0 92.5 Comparative Example 4 70.0 79.0 Comparative Example 5 88.5 94.5

[0184] Table 3. Catalyst stability test results in Example 24

[0185] Time / h Conversion rate / % Selectivity / % 5 99.9 99.0 10 99.9 98.9 50 99.9 99.0 100 99.9 99.5 200 99.7 98.7 500 99.6 98.9 700 99.6 98.6 1000 99.6 98.9

[0186] In summary, this invention prepares a highly efficient catalyst for activated carbon-supported metal chlorides by pretreating the activated carbon support, directly impregnating the active component with the activated carbon, and freeze-drying it. This catalyst exhibits excellent catalytic activity in the dehydrochlorination of 1,1,2,2-tetrachloroethane to trichloroethylene, while maintaining high conversion and high selectivity and extending the catalyst's lifespan.

Claims

1. A method for preparing a dehydrochlorination catalyst, characterized in that: The preparation method includes the following steps: A1. Add activated carbon to a 5-10 wt% HNO3 solution or a 5-10 wt% NH3·H2O solution and reflux at a temperature of 50-80℃ for 5-10 h. After reflux, wait for the temperature to drop to room temperature, filter with deionized water and wash until neutral, then dry to obtain pretreated activated carbon. A2. Add a pore-forming agent to the activated carbon, let it stand for 2-6 hours, then transfer it to a tube furnace and heat it to 400-800℃ at a rate of 1-10℃ / min under an inert atmosphere, with a gas flow rate of 20-60mL / min, and maintain the temperature for 2-8 hours; the pore-forming agent is one of water, polyethylene glycol, polyvinyl alcohol, and polyacrylamide, or a combination of water and any one of polyethylene glycol, polyvinyl alcohol, and polyacrylamide. A3. Prepare an aqueous solution of a metal salt, wherein the solute in the metal salt solution is one of Zn(NO3)2, Ba(NO3)2, and CsNO3, or a combination of Zn(NO3)2 and one of Ba(NO3)2 and CsNO3. Add the activated carbon obtained in A2 to the solution and impregnate at room temperature for 5-10 hours to obtain the product. Subsequently, freeze-dry the product to obtain the product. The mass ratio of the activated carbon to the metal salt is 10-40:

1. A4. Place the product from A3 into a tube furnace, and introduce a reducing gas containing hydrogen to reduce the metal salt to the elemental metal. The reduction conditions are: heating to 300-800℃ at a rate of 1-10℃ / min in a H2 / Ar mixed gas at a gas flow rate of 20-60 mL / min, and holding at that temperature for 2-5 h; then introduce HCl gas to react with the elemental metal to generate metal chloride. The reaction conditions are: introducing HCl gas at a gas flow rate of 20-60 mL / min, and reacting at room temperature to 800℃ for 0.1-3 h, thereby obtaining a dehydrochlorination catalyst.

2. The preparation method according to claim 1, characterized in that: The activated carbon used in step A1 is either wood-based charcoal or coconut shell charcoal.

3. The preparation method according to claim 1, characterized in that: In step A1, the ratio of activated carbon to HNO3 solution or NH3·H2O solution is 1g:20-50mL.

4. The preparation method according to claim 1, characterized in that: In step A2, the mass ratio of activated carbon to pore-forming agent is 1:2-4.

5. The preparation method according to claim 1, characterized in that: The freeze-drying conditions in step A3 are as follows: freeze-dry the impregnated product at -30 to -50°C for 20-30 hours.

6. The preparation method according to claim 1, characterized in that: In step A4, the hydrogen-containing reducing gas is an H2 / Ar mixture, wherein the volume percentage of hydrogen is 5-10%.

7. The preparation method according to claim 1, characterized in that: In step A4, the metal is Zn, and the reduction conditions are: heating to 300-400℃ at a rate of 1-10℃ / min in an H2 / Ar mixture with a gas flow rate of 20-60 mL / min, and holding at that temperature for 2-5 hours; or the metal is one of Ba and Cs3 or a combination of Zn and one of Ba and Cs, and the reduction conditions are: heating to 300-400℃ at a rate of 1-10℃ / min in an H2 / Ar mixture with a gas flow rate of 20-60 mL / min, and holding at that temperature for 1-3 hours; subsequently, heating to 400-800℃ at a rate of 1-10℃ / min, and holding at that temperature for 1-3 hours.

8. The preparation method according to claim 1, characterized in that: In step A4, if the metal is Cs or a combination of Zn and Cs, the reaction conditions for generating the metal chloride are: HCl gas is introduced at a gas flow rate of 20-60 mL / min at room temperature and maintained for 0.1-3 h; or if the metal is Zn or a combination of Zn and Ba, the reaction conditions for generating the metal chloride are: HCl gas is introduced at a gas flow rate of 20-60 mL / min at room temperature and maintained for 0.1-1 h, then the temperature is increased to 400-800 °C at a rate of 1-10 °C / min and maintained for 0.1-1 h; or if the metal is Ba, the reaction conditions for generating the metal chloride are: HCl gas is introduced at a gas flow rate of 20-60 mL / min at room temperature, the temperature is increased to 400-800 °C at a rate of 1-10 °C / min and maintained for 0.1-1 h.

9. A dehydrochlorination catalyst prepared by the method according to any one of claims 1-8.

10. The application of the dehydrochlorination catalyst as described in claim 9 in the synthesis of 1,1,2,2-trichloroethylene from 1,1,2,2-tetrachloroethane.

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