Preparation method of modified activated carbon supported bimetallic catalyst, prepared catalyst and application thereof

Abstract

The application provides a preparation method of a modified activated carbon supported bimetallic catalyst, the prepared catalyst and application of the catalyst. The preparation method of the modified activated carbon supported bimetallic catalyst is as follows: first, the activated carbon serving as a carrier of the bimetallic catalyst is modified, so that the anchoring capacity for metal components is enhanced, and the stability and service life of the catalyst components are improved; second, complexing agents are used to coordinate the bimetallic catalyst, so that the bimetallic catalyst is closely adhered together, and meanwhile, the dispersity of the bimetallic catalyst is maintained; and third, the bimetallic catalyst is rapidly synthesized through flash drying and electromagnetic heating technology, and the catalyst preparation method has the advantages of high efficiency, stability, high activity and the like. The catalyst prepared through the method has multifunctionality in the dechlorination reaction of 1,2-dichloroethane, that is, under the condition of hydrogen, ethane can be generated with high selectivity, and under the condition of no hydrogen, ethylene can be generated with high selectivity while maintaining a high conversion rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and particularly relates to a preparation method of a modified activated carbon supported bimetallic catalyst, the prepared catalyst and application of the catalyst in catalytic dechlorination of 1,2-dichloroethane. BACKGROUND

[0002] 1,2-Dichloroethane (1,2-DCE) is a colorless liquid, slightly soluble in water, and has a smell similar to chloroform. It can be used as a raw material or intermediate and is widely used in the production of fine chemicals such as medicines and pesticides. It can also be used to produce chloroethylene, ethane, ethylene and other basic chemical products with higher added value.

[0003] Currently, 1,2-dichloroethane is used as a raw material to prepare high-value-added products such as ethylene or ethane by catalytic dechlorination. The main methods include electrochemical method, catalytic oxidation method, catalytic hydrogenation method, etc. Among them, catalytic hydrogenation dehalogenation is a mature method for safe and green treatment of chlorinated alkanes. This method has the advantages of clean process route, high atomic economy, low production cost, and recyclable catalyst. Catalytic hydrogenation dehalogenation is one of the best methods for converting 1,2-dichloroethane into higher value-added products such as ethylene, chloroethylene, and ethane. However, this type of catalyst is often used in high-temperature environments containing HCl, and the harsh reaction conditions often result in low conversion rate and easy deactivation of the catalyst. Therefore, solving the conversion rate and selectivity of this type of catalyst is still the focus of attention.

[0004] CN117654604A discloses a preparation method of a catalyst for high-selectivity catalytic cracking of 1,2-dichloroethane to produce chloroethylene, which includes the following steps: pretreating the material as a silicon-containing or aluminum-containing material, first taking 50g of SSZ-13 type molecular sieve and adding it to 10ml of 20% methyl silicate solution for impregnation, with a pretreatment temperature of 30℃. After pretreatment for 24 hours, dry at 60℃ for 24h, and then maintain in a muffle furnace at 700℃ for 4 hours. In the evaluation process, 1,2-dichloroethane is carried into a fluidized bed reactor by helium bubbling, and under the conditions of a reactor temperature of 290℃ and a mass space velocity of 4.6h-1, a 91% conversion rate and a 87% selectivity of chloroethylene are obtained.

[0005] CN105148907A discloses a catalyst for selective hydrogenation dechlorination of 1,2-dichloroethane and its preparation method and application. The catalyst uses oxide C as a carrier, wherein C is one of Al2O3, SiO2, TiO2 or ZrO2, metal A is one of Ag or Cu, and metal B is one of Pd or Pt. The catalyst preparation method is to immerse oxide C in a metal A salt solution, evaporate to dryness, then dry and calcine to obtain A / C; then reduce A / C with H2, and in an inert gas, carry out a displacement reaction with an oxygen-removed metal B salt solution, stir for 0.5-3 h, filter and dry to obtain A-B / C catalyst. The A-B / C catalyst is used for selective hydrogenation dechlorination of 1,2-dichloroethane, and the selectivity of the main product ethylene is greater than 80%.

[0006] CN102658127A discloses a bimetallic catalyst prepared by a continuous light deposition method and its application in selective hydrogenation dechlorination and degradation of 1,2-dichloroethane. 100 mg of pd-Pt(1.07)-Ag(1.05) / TiO2 catalyst is used for gas-phase hydrogenation catalytic degradation of 1,2-dichloroethane, under the conditions of a reaction temperature of 200-250°C, a H2 concentration of 30000-40000 ppm, a 1,2-dichloroethane concentration of 7000-7500 ppm, He as the carrier gas, a mixed gas flow rate of 40-50 mL / min, and a normal pressure reaction for 17-19 h, the selectivity of ethylene is 89.1-90.0%.

[0007] CN117732480A discloses a preparation method of a hydrogenolysis dehalogenation catalyst and its application in the generation of ethylene from 1,2-dichloroethane. The preparation method of the catalyst is as follows: first, uniformly dissolve the soluble salt of metal A and the soluble salt of metal B in deionized water to prepare a bimetallic precursor solution, then add a surfactant, mix uniformly to obtain a co-impregnation solution. Then mix the co-impregnation solution with activated carbon, adsorb and impregnate, dry in a blast oven, and then microwave heat treatment to obtain the hydrogenolysis dehalogenation catalyst. The precursor of 0.5wt% ruthenium and 2.0wt% zinc supported on activated carbon is treated with microwaves under the conditions of nitrogen flow of 30 mL / min, power of 300 W, microwave frequency of 3 GHz emitted by the magnetron, and microwave treatment time of 15 min. The catalyst obtained is used for reaction under the conditions of a reaction temperature of 280°C, n(H2):n(1,2-DCE) of 6:1, and space velocity of 1550 h-1, and the best performance of the catalyst shows a conversion rate of 94.2% and an ethylene selectivity of 95.9%.

[0008] CN113634275A discloses a method for preparing a catalytic hydrodechlorination catalyst and its application. The catalyst comprises a primary active component, Ru, a promoter element, M, and a carrier. The promoter element M is at least one of B, N, and P. The promoter element M forms an amorphous state with the precious metal Ru and is supported on the carrier. The carrier is one or a mixture of activated carbon, carbon black, and silicon carbide. The catalyst is used in the catalytic hydrodechlorination of 1,2-dichloroethane to produce ethylene, achieving a conversion rate of 90% and an ethylene selectivity of 95%.

[0009] In summary, bimetallic catalysts are often used as active components in the hydrodechlorination of 1,2-dichloroethane. Existing methods for preparing bimetallic catalysts have problems such as uneven dispersion and high economic costs. When used in the reaction, they suffer from low conversion and selectivity. In addition, high temperatures and the presence of HCl lead to catalyst deactivation and decreased selectivity. Summary of the Invention

[0010] To address the above issues, the present invention proposes a method for preparing a modified activated carbon-supported bimetallic catalyst, the resulting catalyst, and its application in the catalytic dechlorination of 1,2-dichloroethane. The concept is to modify the activated carbon used as a carrier for the bimetallic catalyst to enhance its anchoring ability for the metal components, thereby improving the stability and service life of the catalyst components. Secondly, the coordination of a complexing agent is used to tightly bond the bimetallic components together while maintaining their dispersion. Furthermore, through flash drying and electromagnetic heating technology, the bimetallic catalyst can be rapidly synthesized. This catalyst preparation method has the advantages of high efficiency, stability, and high activity. The catalyst prepared by this method is multifunctional for the dechlorination of 1,2-dichloroethane. While maintaining a high conversion rate, it can produce ethane with high selectivity in hydrogen conditions and ethylene with high selectivity in the absence of hydrogen.

[0011] In a first aspect, the present invention provides a method for preparing a modified activated carbon-supported bimetallic catalyst, the steps of which include:

[0012] A1. Crushed activated carbon was sieved into 10-40 mesh granules, ultrasonically washed, filtered, dried, and placed in a microwave tube furnace. Calcination was performed for 1-8 hours at a power of 200-900 W, a temperature of 300-900 ° C, and a nitrogen flow rate of 30-100 mL / min.

[0013] A2. The activated carbon treated in step A1 was added to a 0.05-0.40 g / mL urea solution and refluxed at 100-140 ° C for 1-5 hours. The excess solution was separated by filtration, and the treated support was vacuum dried to obtain a modified activated carbon;

[0014] A3. Take potato starch and water mixture, stirring and dissolving under the condition of 20-90℃, 50-500rpm, filtering, and configuring into 0.05-0.20g / mL complexing agent solution;

[0015] A4. First, configure 0.001-0.01g / mL metal precursor I solution and 0.001-0.1g / mL metal precursor II solution, and add the metal precursor I solution and the metal precursor II solution into the container in the volume ratio of 1:1-15, and obtain the mixed impregnation solution by ultrasonic treatment; take the complexing agent solution prepared in step A3 and add it into the mixed impregnation solution, and stir for 2-30min under the condition of 50-500rpm to prepare the colloidal solution containing bimetal; wherein the metal in the metal precursor I solution is selected from one of Pt, Pd, and Ru, and the metal in the metal precursor II solution is selected from one of Fe, Co, Ni, and Cu;

[0016] A5. Take the modified activated carbon treated in step A2 and add it into container 1, add the colloidal solution containing bimetal prepared in step A4, the modified activated carbon and the colloidal solution containing bimetal are in the feeding ratio of 1g:1-3mL, and add methanol, the volume ratio of the methanol and the colloidal solution containing bimetal is 0.5-1.5:1, and stir and adsorb under the condition of 50-100℃ and 50-500rpm for 0.5-3h;

[0017] A6. Take container 2 with a capacity greater than container 1 and at least two openings, connect the opening of container 1 in step A5 with the opening of container 2 with rubber pipe, and connect the other opening of container 2 with a vacuum pump; close the communication between container 1 and container 2, vacuumize container 2 with the vacuum pump, and heat and stir the mixture in the closed container 1, the heating and stirring condition is: heating and stirring under the condition of 60-200℃ and 50-500rpm for 0.5-1h, then open the communication between container 1 and container 2, and make the liquid in container 1 evaporate instantaneously, and continue for 10-60min under-0.1MPa;

[0018] A7. Dry the remaining substances in container 1, place them in a quartz tube filled with N2, and heat treat them in a medium frequency furnace under the condition of 50Hz, 500-1000W, 300-800℃ for 5-50s to prepare the modified activated carbon supported bimetal catalyst.

[0019] As preferred, in step A1, the calcination condition in the microwave tube furnace is: calcination treatment under the condition of 400-800W, 400-800℃, and N2 flow of 50-100mL / min for 1-5h.

[0020] As a preference, in the step A1, the drying is performed in a blast oven at 60-120°C for 3-9h; further preferably at 80-120°C for 3-9h.

[0021] As a preference, in the step A2, the feeding ratio of the activated carbon treated in the step A1 to the urea solution of 0.05-0.40g / mL is 1g:0.5-1.0mL.

[0022] As a preference, in the step A2, the concentration of the urea solution is 0.10-0.30g / mL.

[0023] As a preference, in the step A2, the refluxing is performed at 100-140°C for 1-3h.

[0024] As a preference, in the step A2, the vacuum drying is performed in a vacuum oven at -0.1MPa at 40-80°C for 1-8h, further preferably at 50-80°C for 1-8h.

[0025] As a preference, in the step A3, the potato starch and water are stirred and dissolved at 30-80°C and 100-400rpm, filtered, and configured into a complexing agent solution of 0.05-0.15g / mL.

[0026] As a preference, in the step A4, the metal precursor I solution of 0.001-0.01g / mL and the metal precursor II solution of 0.01-0.1g / mL are prepared, and the metal precursor I solution and the metal precursor II solution are added into a beaker in a volume ratio of 1:1-10, and a uniformly mixed co-impregnation solution is obtained through ultrasonic treatment.

[0027] As a preference, in the step A4, the complexing agent solution prepared in the step A3 is added into the co-impregnation solution, and a bimetal-containing colloidal solution is prepared through stirring at 50-500rpm for 20min.

[0028] As a preference, in the step A4, the volume ratio of the complexing agent solution to the co-impregnation solution is 0.5-1.5:1.

[0029] As a preference, in the step A5, after the addition of the methanol, the stirring and adsorption are performed at 50-100°C and 50-200rpm for 0.5-1h.

[0030] As a preference, in the step A7, the drying is performed in a blast oven at 60-120°C for 1-6h.

[0031] The step A6 is a flash evaporation step, which is designed to improve the flash evaporation effect of the mixture in the container 1. It can be understood that the larger the capacity of the container 2 compared to the container 1, the more helpful to improve the flash evaporation effect.

[0032] In a second aspect, the present application provides a modified activated carbon supported bimetallic catalyst prepared by the method according to the first aspect.

[0033] In a third aspect, the present application provides an application of the modified activated carbon supported bimetallic catalyst according to the second aspect in catalytic dechlorination of 1,2-dichloroethane, wherein the modified activated carbon supported bimetallic catalyst is pre-activated with NH3 before the application.

[0034] As an embodiment, the application is for preparing ethylene, and the steps include:

[0035] B1. loading the modified activated carbon supported bimetallic catalyst into a fixed bed reactor, and passing NH3 / N2 mixed gas into the fixed bed reactor at a volume ratio of 1:1-10, wherein NH3 is passed at a flow rate of 5-10 mL / min, and after a certain time of passing, pre-activating the catalyst, and raising the temperature of the fixed bed reactor to 180-500°C at a rate of 3-10°C / min, and keeping the temperature constant for 1-6 h, to complete the pre-activation of the modified activated carbon supported bimetallic catalyst;

[0036] B2. raising the temperature of the fixed bed reactor to 220-450°C at a rate of 3-10°C / min, and closing the supply of NH3 / N2; opening the feed pump to pass 1,2-dichloroethane as a raw material into the gasification chamber, and gasifying the raw material at 70-160°C, and passing the mixture of the raw material and nitrogen into the fixed bed reactor, so that n(N2):n(C2H4Cl2)=5-1:1, and the volume space velocity of the raw material is 200-2000 h -1 , to generate ethylene under the action of the modified activated carbon supported bimetallic catalyst.

[0037] As another embodiment, the application is for preparing ethane, and the steps include:

[0038] C1. loading the modified activated carbon supported bimetallic catalyst into a fixed bed reactor, and passing NH3 / N2 mixed gas into the fixed bed reactor at a volume ratio of 1:1-10, wherein NH3 is passed at a flow rate of 5-10 mL / min, and after a certain time of passing, pre-activating the catalyst, and raising the temperature of the fixed bed reactor to 180-500°C at a rate of 3-10°C / min, and keeping the temperature constant for 1-6 h, to complete the pre-activation of the modified activated carbon supported bimetallic catalyst;

[0039] C2. raising the temperature of the fixed bed reactor to 220-440°C at a rate of 3-10°C / min, and closing the supply of N2 and NH3; opening the supply of H2 and the feed pump, and passing 1,2-dichloroethane as a raw material into the gasification chamber by the feed pump, and gasifying the raw material at 70-160°C, and then passing the mixture of the raw material and hydrogen into the reactor, and the volume space velocity of the raw material is 500-2000 h -1, the reactant ratio is controlled as n(H2):n(C2H4Cl2)=1-10:1, and the modified activated carbon loaded bimetallic catalyst is used to react to generate ethane.

[0040] The present application has the following advantages:

[0041] (1) The present application first removes the organic matters and impurities on the activated carbon by high-temperature calcination in a microwave tube furnace, and then the activated carbon is impregnated with urea to increase the basic sites of the activated carbon, adjust the adsorption capacity and sequence of the carrier to the bimetal, and enhance the electron transmission capacity of the activated carbon, thereby improving the adsorption of the catalyst to the substrate.

[0042] (2) The bimetal is complexed by the complexing agent prepared from soluble potato starch to adjust the adsorption sequence and capacity of the bimetal on the activated carbon, and enhance the synergistic effect of the complexation of the bimetal. The soluble starch as the complexing agent can enhance the stability of the bimetal colloidal solution, form a complex of metal ions, and maintain the uniformity and stability of the solution.

[0043] (3) The flash drying and electromagnetic heating of the medium-frequency furnace are used to directly heat the metal to the required temperature, uniformly heat the catalyst, accurately control the heating temperature, and be beneficial to the accurate control of the high-efficiency catalyst. The heating requirement can be met in a short time, thereby avoiding the decomposition of the N-doped activated carbon in a long time at high temperature, and effectively maintaining the actual N doping amount.

[0044] (4) The catalyst prepared by the present application has more efficient performance in the hydrogenation dechlorination reaction of 1,2-dichloroethane, maintains the original conversion rate, improves the selectivity of the product ethane, and increases the service life. In addition, the catalyst still has high conversion rate for 1,2-dichloroethane and high selectivity for ethylene under the condition of no hydrogen. DETAILED DESCRIPTION

[0045] The following examples are only used to further illustrate the present application, but the protection scope of the present application is not limited to this.

[0046] In the examples of the present application, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer are conventional products that can be obtained by conventional technical means or purchased on the market.

[0047] In the examples of the present application, the "raw material" is "1,2-dichloroethane" produced by Guangdong Guanghua Science and Technology Co., Ltd., the activated carbon is columnar activated carbon with a particle size of 10-40 mesh and a specific surface area of 1000-1500 m 2 / g, pore size between 2.0-5.0 nm, average pore size of 2.7 nm.

[0048] Example 1

[0049] A1, activated carbon pretreatment: The activated carbon was crushed and sieved into 10-20 mesh granular activated carbon, washed with water by ultrasonic, and separated by filtration, and then dried in a blast oven at 110°C for 5h. The pretreated activated carbon was calcined in a microwave tube furnace at 800W, 700°C, and a N2flow rate of 50mL / min for 3h.

[0050] A2, activated carbon modification treatment: 3g of the pretreated activated carbon of A1 was added to 3mL of a 0.20g / mL urea solution, refluxed at 120°C for 3h, the excess solution was separated by filtration, and the treated carrier was dried in a vacuum oven at -0.1MPa and 70°C for 4h.

[0051] A3, complexing agent preparation: potato starch and water were mixed, stirred at 200rpm and dissolved at 60°C, filtered, and configured into a 0.10g / mL potato starch solution.

[0052] A4, metal precursor preparation: 3ml of 0.005g / mL platinum chloride solution and 3mL of 0.04g / mL copper nitrate solution were ultrasonically treated for 5min to obtain a uniformly mixed co-impregnation solution, 6mL of the complexing agent prepared in A3 was added, and the mixture was stirred at 200rpm for 20min to obtain a bimetallic colloidal solution.

[0053] A5, impregnation: 6g of activated carbon prepared in A2 was placed in a 50mL round-bottom flask, the bimetallic colloidal solution prepared in A4 was added for impregnation, and 12mL of methanol was added, and the mixture was stirred at 50°C and 100rpm for 1h for adsorption.

[0054] A6, flash drying: the round-bottom flask of A5 was connected to a 10L round-bottom flask with a rubber tube, the other end of the 10L round-bottom flask was connected to a vacuum pump; the channel between the two round-bottom flasks was closed, the precursor in the 50mL round-bottom flask was heated and stirred at 100°C and 100rpm for 0.5h, the 10L round-bottom flask was evacuated, the channel between the two round-bottom flasks was opened instantly, the liquid in the 50mL round-bottom flask was instantly evaporated, and the precursor was continuously evacuated at -0.1MPa for 20min, the water content of the precursor was 28.32%.

[0055] A7, electromagnetic heat treatment: the remaining precursor in 50 mL round bottom flask was dried in the blast oven at 80°C for 2 h; then the precursor was moved into the quartz tube filled with N2, and heat treated in the medium frequency furnace at 50 Hz, 800 W, 600°C for 20 s to prepare the activated carbon supported bimetallic catalyst. The loading of Pt was 0.24 wt% and the loading of Cu was 1.96 wt% by ICP detection.

[0056] The catalyst is particularly applied as follows:

[0057] Pre-activation: the bimetallic catalyst prepared above was used in the fixed bed reactor to pre-activate at V N2 :V NH3 = 3:1 for 30 min with NH3 flow rate of 7 mL / min. The fixed bed reactor was raised to 400°C at 5°C / min and kept constant for 3 h to complete the pre-activation.

[0058] Application 1: the fixed bed reactor was raised to 320°C at 5°C / min, NH3 was turned off, and the feed pump was turned on for reaction. The raw material was first vaporized in the vaporization chamber at 120°C, then mixed with nitrogen and entered the fixed bed reactor, n(N2):n(C2H4Cl2) = 2:1, and the raw material volume space velocity was 1000 h -1 , so as to generate ethylene by catalytic dechlorination of 1,2-dichloroethane.

[0059] Application 2: the fixed bed reactor was raised to 300°C at 5°C / min, NH3 and N2 were turned off, H2 and the feed pump were turned on for reaction. The raw material was first vaporized in the vaporization chamber at 120°C, then mixed with hydrogen and entered the reactor, and the raw material volume space velocity was 1500 h -1 , n(H2):n(C2H4Cl2) = 3:1, so as to generate ethane by catalytic dechlorination of 1,2-dichloroethane.

[0060] The catalyst of Example 1 was evaluated for 5 h, and the products were analyzed by gas chromatography. The area normalization results showed that the catalyst of Example 1 exhibited 93.45% conversion and 91.94% ethylene selectivity in application 1, and exhibited 94.34% conversion and 96.43% ethane selectivity in application 2.

[0061] Example 2

[0062] Example 2 changed the pretreatment condition of activated carbon in A1, here the activated carbon was crushed and sieved into 30-40 mesh granular activated carbon, washed with water by ultrasonic, separated by filtration, and dried in a blast oven at 120°C for 6h. After calcination in a microwave tube furnace at 800°C for 5h with N2flow rate of 100mL / min, it was taken out after cooling to room temperature. The rest of the catalyst preparation process and evaluation conditions were the same as in Example 1.

[0063] Example 2 catalyst was evaluated for 5h, and the products were analyzed by gas chromatography. Area normalization results showed that the catalyst in Example 2 exhibited a conversion rate of 94.21% and an ethylene selectivity of 91.21% in Application 1; and a conversion rate of 94.13% and an ethane selectivity of 92.81% in Application 2.

[0064] Example 3-4

[0065] Examples 3, 4 changed the modification conditions of activated carbon in A2 compared to Example 1. Example 3 was refluxed in a 0.10g / mL urea solution at 140°C for 3h, and dried in a vacuum oven at -0.1MPa at 100°C for 3h; Example 4 was refluxed in a 0.30g / mL urea solution at 100°C for 1h, and dried in a vacuum oven at -0.1MPa at 50°C for 5h. The rest of the catalyst preparation process and evaluation conditions were the same as in Example 1.

[0066] After 5h of stable evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst in Example 3 exhibited a conversion rate of 93.36% and an ethylene selectivity of 90.55% in Application 1; and a conversion rate of 93.22% and an ethane selectivity of 94.56% in Application 2. The catalyst in Example 4 exhibited a conversion rate of 94.25% and an ethylene selectivity of 95.35% in Application 1; and a conversion rate of 94.93% and an ethane selectivity of 96.73% in Application 2.

[0067] Example 5-6

[0068] Examples 5, 6 changed the concentration of complexing agent in A3 compared to Example 1, i.e. the concentration of soluble potato starch was changed, where Example 5 used a 0.05g / mL starch solution and Example 6 used a 0.15g / mL starch solution.

[0069] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 5 exhibited 90.36% conversion and 90.79% ethylene selectivity in Application 1; 91.16% conversion and 93.73% ethane selectivity in Application 2; the catalyst of Example 6 exhibited 94.36% conversion and 94.55% ethylene selectivity in Application 1; 93.74% conversion and 95.83% ethane selectivity in Application 2.

[0070] Examples 7-8

[0071] Examples 7 and 8 changed the ratio of platinum in metal component I to copper in metal component II in A4, where Example 7 used 3 mL of a 0.01 g / mL platinum chloride solution and 3 mL of a 0.01 g / mL copper nitrate solution; Example 8 used 3 mL of a 0.001 g / mL platinum chloride solution and 3 mL of a 0.04 g / mL copper nitrate solution. The rest of the catalyst preparation process and evaluation conditions were the same as in Example 1.

[0072] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 7 exhibited 92.86% conversion and 92.55% ethylene selectivity in Application 1; 93.22% conversion and 91.56% ethane selectivity in Application 2; the catalyst of Example 8 exhibited 94.68% conversion and 93.45% ethylene selectivity in Application 1; 95.34% conversion and 95.73% ethane selectivity in Application 2.

[0073] Examples 9-10

[0074] Examples 9 and 10 changed the loading of the bimetallic in A4, where Example 9 used 3 mL of a 0.0025 g / mL platinum chloride solution and 3 mL of a 0.02 g / mL copper nitrate solution; Example 10 used 3 mL of a 0.01 g / mL platinum chloride solution and 3 mL of a 0.08 g / mL copper nitrate solution. The rest of the catalyst preparation process and evaluation conditions were the same as in Example 1.

[0075] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 9 exhibited 90.36% conversion and 90.55% ethylene selectivity in Application 1; 90.30% conversion and 90.93% ethane selectivity in Application 2; the catalyst of Example 10 exhibited 97.45% conversion and 92.35% ethylene selectivity in Application 1; 98.49% conversion and 97.68% ethane selectivity in Application 2.

[0076] Examples 11-12

[0077] Examples 11, 12 changed the metal species in metal component I in A4 compared to Example 1. The specific experiments are as follows. Example 11 used 3 mL of 0.005 g / mL palladium chloride solution with 3 mL of 0.04 g / mL copper nitrate solution; Example 12 used 3 mL of 0.005 g / mL ruthenium chloride solution with 3 mL of 0.04 g / mL copper nitrate solution. The rest of the catalyst preparation process and evaluation conditions were the same as Example 1.

[0078] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 11 exhibited 93.34% conversion and 90.55% ethylene selectivity in Application 1; exhibited 93.81% conversion and 95.56% ethane selectivity in Application 2; the catalyst of Example 12 exhibited 92.36% conversion and 91.15% ethylene selectivity in Application 1; exhibited 91.29% conversion and 93.33% ethane selectivity in Application 2.

[0079] Examples 13-15

[0080] Examples 13, 14, 15 changed the metal species in metal component II in A4 compared to Example 1. The specific experiments are as follows. Example 13 used 3 mL of 0.005 g / mL platinum chloride solution with 3 mL of 0.04 g / mL iron chloride solution; Example 14 used 3 mL of 0.005 g / mL platinum chloride solution with 3 mL of 0.04 g / mL cobalt nitrate solution; Example 15 used 3 mL of 0.005 g / mL platinum chloride solution with 3 mL of 0.04 g / mL nickel nitrate solution. The rest of the catalyst preparation process and evaluation conditions were the same as Example 1.

[0081] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 13 exhibited 91.01% conversion and 94.55% ethylene selectivity in Application 1; exhibited 91.31% conversion and 90.09% ethane selectivity in Application 2. The catalyst of Example 14 exhibited 90.99% conversion and 91.55% ethylene selectivity in Application 1; exhibited 90.69% conversion and 91.63% ethane selectivity in Application 2. The catalyst of Example 15 exhibited 96.36% conversion and 91.95% ethylene selectivity in Application 1; exhibited 97.69% conversion and 98.63% ethane selectivity in Application 2.

[0082] Examples 16-17

[0083] Example 16, 17 vs. Example 1 Here the complexing agent liquid amount in A4 and adsorption time in A5 were changed, as follows. Example 16 in A4, 3 mL of complexing solution was added; in A5, 6 g of activated carbon was taken in a 50 mL apparatus 1 round bottom flask, adsorption was carried out at room temperature, 100 rpm stirring for 0.5 h. Example 17 in A4, 9 mL of complexing solution was added; in A5, 6 g of activated carbon was taken in a 50 mL apparatus 1 round bottom flask, adsorption was carried out at room temperature, 100 rpm stirring for 3 h.

[0084] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 16 exhibited 90.25% conversion and 93.55% ethylene selectivity in Application 1; and exhibited 91.53% conversion and 90.88% ethane selectivity in Application 2. The catalyst of Example 17 exhibited 92.72% conversion and 96.00% ethylene selectivity in Application 1; and exhibited 93.53% conversion and 94.32% ethane selectivity in Application 2.

[0085] Example 18

[0086] Example 18 vs. Example 1 changed the flash drying time in A6, Example 18 in A6, vacuum was drawn for 40 min, at this time the water content of the precursor was 14.54%. The rest of the catalyst preparation process and evaluation conditions were the same as Example 1.

[0087] After 5 h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 18 exhibited 93.90% conversion and 90.07% ethylene selectivity in Application 1; and exhibited 95.11% conversion and 93.87% ethane selectivity in Application 2.

[0088] Examples 19-20

[0089] Example 19, 20 vs. Example 1 changed the power, temperature and heating time of electromagnetic heating in A7. Example 19 in the intermediate frequency furnace at 50 Hz, 600 W, 400 °C for 10 s; Example 20 in the intermediate frequency furnace at 50 Hz, 1000 W, 800 °C for 40 s.

[0090] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 19 exhibited 90.08% conversion and 92.35% ethylene selectivity in Application 1; and 92.71% conversion and 90.09% ethane selectivity in Application 2. The catalyst of Example 20 exhibited 90.54% conversion and 92.46% ethylene selectivity in Application 1; and 90.52% conversion and 97.43% ethane selectivity in Application 2.

[0091] Comparative Example 1

[0092] Comparative Example 1 was prepared by impregnation of untreated activated carbon with co-impregnation solution without complexing agent and by air drying, and the specific experimental process was as follows.

[0093] Catalyst preparation: 3g of 10-20 mesh activated carbon was added to 3mL of 0.005g / mL platinum chloride solution and 3mL of 0.04g / mL nickel nitrate solution to obtain a uniformly mixed co-impregnation solution, which was stirred for 2h at room temperature and 100rpm, and then dried in a blast oven at 80°C for 2h and at 180°C for 5h to obtain the catalyst required for Comparative Example 1. The evaluation process of the catalyst of Comparative Example 1 was the same as that of Example 15.

[0094] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Comparative Example 1 exhibited 60.24% conversion and 67.24% ethylene selectivity in Application 1; and 62.35% conversion and 64.55% ethane selectivity in Application 2. This comparative experiment proved that the pretreatment and modification of activated carbon and the complexing agent prepared from soluble potato starch solution can improve the performance of bimetallic supported catalysts.

[0095] Comparative Example 2

[0096] Comparative Example 2 was prepared by impregnation of activated carbon without pretreatment, and the rest of the catalyst preparation and evaluation process was the same as that of Example 15.

[0097] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Comparative Example 2 exhibited 83.78% conversion and 85.71% ethylene selectivity in Application 1; and 83.13% conversion and 87.87% ethane selectivity in Application 2. This comparative experiment proved that the activated carbon treated with nitric acid can increase the oxygen-containing groups on the activated carbon, which is beneficial to the improvement of catalyst performance.

[0098] Comparative Example 3

[0099] Comparative Example 3 is compared with Example 15, except that the activated carbon is not subjected to urea modification treatment, and the rest of the catalyst preparation and evaluation process is the same as that of Example 15.

[0100] After 5 hours of stable evaluation, the product was analyzed by gas chromatography. Area-normalized results showed that the catalyst in Comparative Example 3 achieved a conversion of 76.88% and an ethylene selectivity of 78.64% in Application 1, and a conversion of 77.95% and an ethane selectivity of 79.96% in Application 2. This comparative experiment demonstrates that nitrogen incorporation into activated carbon imparts more defects, facilitating the anchoring and dispersion of metal components, thereby enhancing catalytic activity.

[0101] Comparative Examples 4-5

[0102] Comparative Examples 4 and 5 were compared to Example 15, except that the urea-modified reflux temperature was changed: 180° C. reflux for 3 h was used in Comparative Example 4, and 80° C. reflux for 3 h was used in Comparative Example 5. The remaining catalyst preparation and evaluation processes for Comparative Examples 4 and 5 were the same as those for Example 15.

[0103] After 5 hours of stable evaluation, the product was analyzed by gas chromatography. Area-normalized results showed that the catalyst from Comparative Example 4 exhibited a conversion rate of 72.56% and an ethylene selectivity of 77.94% in Application 1; and a conversion rate of 74.30% and an ethane selectivity of 76.52% in Application 2. The catalyst from Comparative Example 5 exhibited a conversion rate of 71.08% and an ethylene selectivity of 70.08% in Application 1; and a conversion rate of 72.32% and an ethane selectivity of 73.21% in Application 2. This comparative experiment demonstrates that reflux at higher temperatures may cause the urea acting on the activated carbon to decompose, failing to achieve the purpose of modification; reflux at lower temperatures has a less significant effect, with most of the urea physically adsorbed and bound to the activated carbon.

[0104] Comparative Example 6

[0105] Comparative Example 6, compared to Example 15, did not use soluble potato starch as a complexing agent in the impregnation solution. That is, the soluble potato starch solutions in A3 and A4 were replaced with an equal amount of deionized water. The remaining catalyst preparation and evaluation procedures were the same as in Example 15.

[0106] After 5 hours of stable evaluation, the product was analyzed by gas chromatography. Area-normalized results showed that the catalyst from Comparative Example 6 achieved a conversion of 78.36% and an ethylene selectivity of 74.14% in Application 1, and a conversion of 78.98% and an ethane selectivity of 74.61% in Application 2. This comparative experiment demonstrates that the complexing agent prepared using a soluble potato starch solution can form a coordination complex with the bimetallic catalyst, allowing it to form a close fit and improving the catalytic performance of the bimetallic catalyst.

[0107] Comparative Example 7

[0108] Comparative Example 7 compared with Example 15, here the precursor after impregnation was not flash dried. That is, in A5, 6g of prepared activated carbon was added to the bimetallic colloidal solution of A4 above for impregnation, adsorbed at 50°C, 100 rpm stirring for 1h. Then dried in a blast oven at 80°C for 2h, and then electromagnetic heating treatment in a medium frequency furnace.

[0109] The rest of the catalyst preparation process and evaluation process were the same as Example 15.

[0110] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Comparative Example 7 exhibited 71.24% conversion and 72.36% ethylene selectivity in Application 1; and 70.16% conversion and 72.34% ethane selectivity in Application 2. This comparative experiment proved that flash drying can pre-dry the precursor, quickly increase the solvent volatilization, and to a certain extent, improve the metal redispersion, thereby adjusting the catalyst results and improving the catalyst performance.

[0111] Comparative Example 8

[0112] Comparative Example 8 compared with Example 15, here the prepared catalyst was not subjected to electromagnetic heating treatment. That is, the flash dried precursor was not subjected to electromagnetic heating treatment, but only dried in a blast oven at 80°C for 5h. The rest of the catalyst preparation process and evaluation process were the same as Example 15.

[0113] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Comparative Example 8 exhibited 67.13% conversion and 70.12% ethylene selectivity in Application 1; and 68.24% conversion and 69.98% ethane selectivity in Application 2. This comparative experiment proved the high efficiency of electromagnetic heating treatment, which can synthesize catalysts in a relatively short time, and the catalytic performance is significantly improved.

[0114] Comparative Example 9

[0115] Comparative Example 9 compared with Example 15, here ammonia was not used for pre-activation in the catalyst application part. The rest of the catalyst preparation process and evaluation process were the same as Example 15.

[0116] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Comparative Example 9 exhibited 71.75% conversion and 61.25% ethylene selectivity in Application 1; and exhibited 72.90% conversion and 63.02% ethane selectivity in Application 2. The comparative experiment proved that ammonia pretreatment can effectively activate the catalyst, reduce the metal, and improve the conversion of the reactants and the selectivity of the target products ethylene and ethane.

[0117] Examples 21-22

[0118] Examples 21 and 22 changed the conditions in the catalyst pretreatment step a compared to Example 15. The pretreatment conditions for Example 21 were NH3 / N2=1:2 by volume ratio, with a NH3flow rate of 10 mL / min, and the catalyst was pre-activated after 20 min of aeration. The fixed bed reactor was raised to 330°C at a rate of 3°C / min and held at a constant temperature for 2h to complete the pre-activation. The pretreatment conditions for Example 22 were NH3 / N2=1:5 by volume ratio, with a NH3flow rate of 5 mL / min, and the catalyst was pre-activated after 40 min of aeration. The fixed bed reactor was raised to 300°C at a rate of 6°C / min and held at a constant temperature for 5h to complete the pre-activation.

[0119] After 5h of stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 21 exhibited 92.24% conversion and 92.35% ethylene selectivity in Application 1; and exhibited 93.45% conversion and 94.32% ethane selectivity in Application 2. The catalyst of Example 22 exhibited 91.42% conversion and 91.23% ethylene selectivity in Application 1; and exhibited 92.01% conversion and 93.21% ethane selectivity in Application 2.

[0120] Examples 23-24

[0121] Examples 23 and 24 changed the conditions in Application 2 compared to Example 15. Example 23 was raised to 330°C at a rate of 10°C / min, with a volume space velocity of the raw material of 2000h -1 , and the reactant ratio n(H2):n(C2H4Cl2) was controlled at 5:1. Example 23 was raised to 280°C at a rate of 3°C / min, with a volume space velocity of the raw material of 1000h -1 , and the reactant ratio n(H2):n(C2H4Cl2) was controlled at 3:1.

[0122] After 5h stability evaluation, the products were analyzed by gas chromatography. Area normalization results showed that the catalyst of Example 21 in Application 2 exhibited 99.43% conversion and 90.45% ethane selectivity; the catalyst of Example 22 in Application 2 exhibited 91.66% conversion and 96.78% ethane selectivity.

[0123] Example 25

[0124] Example 25 used the catalyst prepared in Example 15 to perform stability test, here only Application 2 evaluation was performed, where the evaluation conditions were: V N2 :V NH3 = 3:1 ratio, where the NH3flow rate was 5 mL / min, after 30 min of aeration, the catalyst was pre-activated, the fixed bed reactor was raised to 350°C at 5°C / min, and kept constant for 3h, after pre-activation was completed; raised to 330°C at 5°C / min, closed NH3, N2, opened H2, and the feed pump was used to perform the reaction. The raw material was first vaporized in the vaporization chamber at 120°C, then mixed with hydrogen and entered the reactor, the raw material volume space velocity was 1500h -1 , and the reactant ratio n(H2):n(C2H4Cl2) was controlled to be 3:1.

[0125] After stability evaluation, the products were analyzed by gas chromatography, area normalization results showed that the catalyst of Example 25 exhibited 99.87% conversion and 98.75% ethane selectivity after 10h reaction; 99.12% conversion and 98.89% ethane selectivity after 50h reaction; 98.99% conversion and 97.72% ethane selectivity after 100h reaction; 99.07% conversion and 98.84% ethane selectivity after 300h reaction; 99.13% conversion and 99.34% ethane selectivity after 500h reaction; 98.32% conversion and 97.95% ethane selectivity after 800h reaction; 96.36% conversion and 96.55% ethane selectivity after 1000h reaction;

[0126] In summary, by treating activated carbon at high temperature, urea-modified activated carbon, and complexing agent prepared from soluble potato starch, the double metal was complexed, and by using flash drying and electromagnetic heating of the intermediate frequency furnace, an activated carbon-supported double metal high-efficiency catalyst was prepared, which had more efficient dechlorination performance in 1,2-dichloroethane hydrogenation dechlorination reaction, and could efficiently produce ethane under hydrogenation conditions, and could efficiently and selectively produce ethylene under non-hydrogen conditions. In the stability experiment, the original conversion and selectivity were maintained while the service life of the catalyst was increased.

[0127] Table 1. Performance table of catalysts prepared in examples and comparative examples

[0128]

[0129]

[0130] Table 2. Example 25 Stability Test Table

[0131] Time (h) Conversion (%) Ethane selectivity (%) 0.5 0.5 0.5 0.5 0.5 0.5 10 99.87 98.75 50 99.12 98.89 100 98.99 97.72 300 98.74 97.47 800 98.32 97.05 1000 97.36 96.55

Claims

1. A method for preparing a modified activated carbon supported bimetallic catalyst, characterized by: The preparation method comprises the following steps: A1. crushing the activated carbon into 10-40 mesh granular activated carbon, washing with water by ultrasonic, filtering and separating, drying, and then placing into a microwave tube furnace, and performing calcination treatment under the conditions of a power of 200-900 W, a temperature of 300-900 ℃, and a N2 flow rate of 30-100 mL / min for 1-8 h; A2. adding the activated carbon treated in step A1 into a urea solution with a concentration of 0.05-0.40 g / mL, refluxing at 100-140 ℃ for 1-5 h, filtering and separating the excess solution, and vacuum drying the treated carrier to obtain a modified activated carbon; A3. mixing potato starch and water, stirring and dissolving under the conditions of 20-90 ℃ and 50-500 rpm, filtering, and configuring into a complexing agent solution with a concentration of 0.05-0.20 g / mL; A4. first, configuring a metal precursor I solution with a concentration of 0.001-0.01 g / mL and a metal precursor II solution with a concentration of 0.001-0.1 g / mL, and adding the metal precursor I solution and the metal precursor II solution into a container in a volume ratio of 1:1-15, and uniformly mixing by ultrasonic treatment to obtain a co-impregnation solution; adding the complexing agent solution prepared in step A3 into the co-impregnation solution, and stirring at 50-500 rpm for 2-30 min to prepare a colloidal solution containing bimetal; wherein the metal in the metal precursor I solution is selected from one of Pt, Pd and Ru, and the metal in the metal precursor II solution is selected from one of Fe, Co, Ni and Cu; A5. adding the modified activated carbon treated in step A2 into container 1, adding the colloidal solution containing bimetal prepared in step A4, the feeding ratio of the modified activated carbon to the colloidal solution containing bimetal being 1 g:1-3 mL, and adding methanol, the volume ratio of the methanol to the colloidal solution containing bimetal being 0.5-1.5:1, and stirring and adsorbing at 50-100 ℃ and 50-500 rpm for 0.5-3 h; A6. taking container 2 which has a capacity greater than that of container 1 and at least two openings, connecting the opening of container 1 in step A5 to the opening of container 2 by a rubber tube, and connecting the other opening of container 2 to a vacuum pump; closing the communication between container 1 and container 2, vacuumizing container 2 by the vacuum pump, and heating and stirring the mixture in the closed container 1, the heating and stirring conditions being: heating and stirring at 60-200 ℃ and 50-500 rpm for 0.5-1 h, then opening the communication between container 1 and container 2, and making the liquid in container 1 evaporate instantaneously, and maintaining at -0.1 MPa for 10-60 min; A7. drying the remaining substance in container 1, placing it into a quartz tube filled with N2, and placing the quartz tube into a medium-frequency furnace, and performing heat treatment under the conditions of 50 Hz, 500-1000 W, 300-800 ℃, and 5-50 s to prepare a modified activated carbon supported bimetal catalyst.

2. The production method according to claim 1, characterized by: In step A1, the calcination conditions in the microwave tube furnace are as follows: the power is 400-800 W, the temperature is 400-800 ℃, the N2 flow rate is 50-100 mL / min, and the calcination treatment time is 1-5 h.

3. The production method according to claim 1, wherein: In step A2, the feeding ratio of the activated carbon treated in step A1 to the urea solution is 1 g:0.5-1.0 mL, the concentration of the urea solution is 0.10-0.30 g / mL, and the refluxing time is 1-3 h at 100-140 ℃.

4. The production method according to claim 1, wherein: In step A3, the potato starch and water are stirred and dissolved at 30-80 ℃ and 100-400 rpm, filtered, and configured into a complexing agent solution with a concentration of 0.05-0.15 g / mL.

5. The production method according to claim 1, characterized by: In step A4, a metal precursor I solution with a concentration of 0.001-0.01 g / mL and a metal precursor II solution with a concentration of 0.01-0.1 g / mL are prepared, and the metal precursor I solution and the metal precursor II solution are added to a beaker in a volume ratio of 1:1-10 and are uniformly mixed by ultrasonic treatment to obtain a co-impregnation solution. The volume ratio of the complexing agent solution to the co-impregnation solution is 0.5-1.5:

1.

6. The production method according to claim 1, wherein: In step A5, after the addition of methanol, the stirring and adsorption are performed at 50-100 ℃ and 50-200 rpm for 0.5-1 h.

7. A modified activated carbon supported bimetallic catalyst prepared by the preparation method according to any one of claims 1-6.

8. Use of the modified activated carbon supported bimetallic catalyst according to claim 7 in catalytic dechlorination of 1,2-dichloroethane, wherein the modified activated carbon supported bimetallic catalyst is pre-activated with NH3 before use.

9. Use according to claim 8, wherein: The use is for preparing ethylene, and the steps include: B1. The modified activated carbon supported bimetallic catalyst is loaded into a fixed bed reactor, an NH3 / N2 mixed gas is introduced into the fixed bed reactor at a volume ratio of 1:1-10, wherein the flow rate of NH3 is 5-10 mL / min, the catalyst is pre-activated after a certain period of time, the temperature of the fixed bed reactor is increased to 180-500 ℃ at a rate of 3-10 ℃ / min, and the temperature is kept constant for 1-6 h to complete the pre-activation of the modified activated carbon supported bimetallic catalyst. B2. The temperature of the fixed bed reactor is raised at 3-10°C / min to 220-450°C, the NH3 / N2 supply is closed; the feed pump is opened to pass 1,2-dichloroethane as a raw material into the gasification chamber, the raw material is gasified at 70-160°C, and after mixing with nitrogen, is passed into the fixed bed reactor, so that n(N2):n(C2H4Cl2)=5-1:1, the volume space velocity of the raw material is 200-2000h -1 , and reacts to generate ethylene under the action of the modified activated carbon supported bimetallic catalyst.

10. The use according to claim 8, characterized in that: The use is for preparing ethane, and the steps include: C1. The modified activated carbon supported bimetallic catalyst is loaded into a fixed bed reactor, an NH3 / N2 mixed gas is introduced into the fixed bed reactor at a volume ratio of 1:1-10, wherein the flow rate of NH3 is 5-10 mL / min, the catalyst is pre-activated after a certain period of time, the temperature of the fixed bed reactor is increased to 180-500 ℃ at a rate of 3-10 ℃ / min, and the temperature is kept constant for 1-6 h to complete the pre-activation of the modified activated carbon supported bimetallic catalyst. C2. The temperature of the fixed bed reactor is raised at 3-10℃ / min to 220-440℃, the supply of N2, NH3 is closed; the H2 supply and the feed pump are opened, the feed pump is used to feed 1,2-dichloroethane as the raw material into the gasification chamber, the raw material is gasified at 70-160℃, and then mixed with hydrogen before entering the reactor, the volume space velocity of the raw material is 500-2000h -1 -1, and the reaction is carried out under the action of the modified activated carbon supported bimetallic catalyst to generate ethane.

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