Alloy-loaded Pd-Cu-Ho trimetal catalyst, preparation thereof and application of alloy-loaded Pd-Cu-Ho trimetal catalyst in acetylene semi-hydrogenation reaction

Abstract

The invention discloses an alloy-loaded Pd-Cu-Ho trimetal catalyst, preparation thereof and application of the alloy-loaded Pd-Cu-Ho trimetal catalyst in acetylene semi-hydrogenation reaction. The alloy loaded Pd-Cu-Ho three-metal catalyst comprises a carrier and an active component, the carrier is an AlCoCrFeNi2.1 alloy, and the active component is composed of three metals of Pd, Cu and Ho. The invention provides the application of the alloy loaded Pd-Cu-Ho trimetal catalyst in acetylene semi-hydrogenation reaction, and the alloy loaded Pd-Cu-Ho trimetal catalyst shows excellent activity, ethylene selectivity and catalyst stability.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to an alloy-supported Pd-Cu-Ho trimetallic catalyst, a preparation method thereof, and an application thereof in an acetylene semi-hydrogenation reaction. Background Art

[0002] Selective hydrogenation of hydrocarbons is a very important process in the petrochemical industry. Selective hydrogenation of acetylene is to convert trace acetylene (C2H2) impurities in the ethylene stream into ethylene (C2H4) while preventing over-hydrogenation of ethylene and conversion to unwanted ethane (C2H6). This has become a crucial step in the production of polymer-grade ethylene in the olefin industry.

[0003] The active component palladium in palladium (Pd)-based catalysts tends to aggregate. In this case, acetylene (C2H2) prefers to adsorb in a bridging mode on adjacent palladium atomic sites rather than π-type adsorption on isolated palladium atoms. This adsorption mode leads to excessive hydrogenation of C2H2 to ethane (C2H6), which causes reduced product selectivity and coke deposition on the catalyst surface, making it difficult for the catalyst to maintain high ethylene selectivity and shortening the effective service life of the catalyst. Cu-based catalysts have strong adsorption capacity for acetylene and weak adsorption capacity for ethylene, thus showing high ethylene selectivity, which has attracted widespread attention in academia and industry. However, this type of catalyst also has some disadvantages, such as weak dissociation capacity for hydrogen, resulting in low catalytic activity, and easy CC polymerization reaction to produce green oil, which in turn causes catalyst deactivation. Rare earth elements have been proven to effectively inhibit catalyst deactivation. Adding rare earth elements to metal catalysts can significantly enhance the stability of the catalyst and have extremely high application value. As an emerging catalytic material, high entropy alloys (HEAs) have created a broad material design space through the combination of multiple elements, and thus have excellent mechanical properties. In addition, due to their extremely efficient electron transfer characteristics, the application prospects of high entropy alloy materials in the field of catalysis are widely optimistic.

[0004] Based on the above background, the present invention proposes an AlCoCrFeNi 2.1 Alloy-loaded Pd-Cu-Ho trimetallic catalyst was used to improve the selectivity and stability of Pd catalyst in acetylene semi-hydrogenation reaction. Summary of the invention

[0005] The purpose of the present invention is to provide an AlCoCrFeNi 2.1The invention discloses an alloy-loaded Pd-Cu-Ho trimetallic catalyst, its preparation and application in acetylene semi-hydrogenation reaction. The catalyst solves the problems of short life, poor stability and high cost of use of traditional palladium-based catalysts in acetylene semi-hydrogenation reaction.

[0006] The technical solution adopted by the present invention is described in detail below.

[0007] In a first aspect, the present invention provides an alloy-supported Pd-Cu-Ho trimetallic catalyst, comprising a carrier and an active component, wherein the carrier is AlCoCrFeNi 2.1 Alloy, the AlCoCrFeNi 2.1 In the alloy, the molar ratio of Al, Co, Cr, Fe and Ni is 1:1:1:1:2.1, and the active components are composed of three metals: Pd, Cu and Ho, among which, in terms of mass ratio, palladium: copper: holmium = (0.5-1): (1.2-2.5): (0.5-2.5).

[0008] Preferably, in the alloy-loaded Pd-Cu-Ho trimetallic catalyst, the mass of palladium accounts for 0.5%-1% of the total mass of the catalyst, the mass of copper accounts for 1.2%-2.5% of the total mass of the catalyst, and the mass of holmium accounts for 0.5%-2.5% of the total mass of the catalyst, wherein the total mass of the catalyst = m 载体 +m Pd +m Cu +m Ho .

[0009] In a second aspect, the present invention provides a method for preparing the alloy-supported Pd-Cu-Ho trimetallic catalyst according to the first aspect, the preparation method comprising the following steps:

[0010] Step 1: Weigh appropriate amounts of aluminum source, cobalt source, chromium source, iron source, and nickel source and place them in a ball mill for mechanical alloying;

[0011] Step 2: The mechanically alloyed powder is calcined at high temperature in a hydrogen-argon mixed gas atmosphere to obtain AlCoCrFeNi 2.1 Alloy carrier;

[0012] Step 3: Weigh palladium salt, copper salt and holmium salt, dissolve them in a solvent, and stir them thoroughly at room temperature to obtain a mixed solution;

[0013] Step 4: AlCoCrFeNi obtained in step 2 2.1 The alloy carrier is placed in the mixed solution obtained in step 3, and the mixture is stirred at room temperature for 8-12 hours, and then ground into powder after drying to obtain a mixed sample powder;

[0014] Step 5: placing the mixed sample powder obtained in step 4 in an inert gas environment and calcining at high temperature to obtain a calcined product;

[0015] Step 6: The calcined product obtained in step 5 is reduced under a hydrogen atmosphere to obtain an alloy-loaded Pd-Cu-Ho trimetallic catalyst.

[0016] Preferably, in step 1, the aluminum source is Al2O3, the cobalt source is CoO, the chromium source is Cr2O3, the iron source is Fe2O3, and the nickel source is NiO.

[0017] Preferably, in step 1, the mechanical alloying conditions are: ball milling speed of 200rpm-500rpm, ball milling time of 10-30h, more preferably ball milling speed of 270rpm, ball milling time of 15h.

[0018] Preferably, in step 2, the volume percentage content of hydrogen in the hydrogen-argon mixed gas is 5 vol%,

[0019] The flow rate of the hydrogen-argon mixed gas is 1-10 ml / min, more preferably 3-7 ml / min.

[0020] Preferably, in step 2, the high temperature calcination is carried out at a temperature of 800-1200°C and a calcination time of 4-10 hours, more preferably at a temperature of 1000°C and a calcination time of 6 hours.

[0021] Preferably, in step 3, the palladium salt is selected from at least one of palladium dichloride, sodium tetrachloropalladate and dichlorotetraamminepalladium; palladium dichloride is more preferred.

[0022] Preferably, in step three, the copper salt is selected from at least one of copper chloride, copper sulfate, copper nitrate, copper acetate and copper carbonate; more preferably copper nitrate.

[0023] Preferably, in step 3, the holmium salt is selected from holmium nitrate pentahydrate and cyclopentadienyl holmium dichloride; more preferably holmium nitrate.

[0024] Preferably, the solvent is deionized water or hydrochloric acid.

[0025] Preferably, in step 4, the drying conditions are: drying at 80-120° C. for 8-12 hours.

[0026] Preferably, in step five, the calcination temperature is controlled at 200-500° C., more preferably 450° C.; the calcination time is controlled at 0.5-3 h, more preferably 2 h.

[0027] Preferably, in step six, the hydrogen flow rate is 30-70 mL / min, the reduction temperature is 200-600° C., and the reduction time is 1-6 h.

[0028] In a third aspect, the present invention provides the use of the alloy-supported Pd-Cu-Ho trimetallic catalyst described in the first aspect in the semi-hydrogenation reaction of acetylene.

[0029] The application method is: adding raw material gas containing acetylene and hydrogen into a reactor containing alloy-loaded Pd-Cu-Ho, at a space velocity of 5000 to 20000 h -1 (More preferably 10000h -1 ), a hydrogenation reaction is carried out under the conditions of temperature 70-250°C (more preferably 180°C) and pressure 0.1-1MPa (more preferably 0.1MPa) to convert acetylene into ethylene.

[0030] In a specific embodiment of the present invention, the raw material gas containing acetylene and hydrogen is composed of ethylene, hydrogen, acetylene, and the balance nitrogen, wherein the volume ratio of hydrogen to acetylene is 20 to 100:1.

[0031] Compared with the prior art, the advantages of the alloy-supported Pd-Cu-Ho trimetallic catalyst for selective hydrogenation of acetylene provided by the present invention are mainly reflected in:

[0032] (1) The present invention adopts a general method for preparing alloys, namely, mechanical alloying and high temperature calcination in a hydrogen-argon mixed gas to prepare AlCoCrFeNi 2.1 Alloy, this method is simpler than the traditional process and is an environmentally friendly preparation method. 2.1 The alloy has extremely efficient electron transfer characteristics, and using it as a catalyst carrier makes the catalyst have good catalyst activity and stability.

[0033] (2) Due to the high dispersion of its active centers, this catalyst has higher activity and selectivity than single palladium and single copper catalysts.

[0034] (3) The introduction of holmium into the catalyst can slow down the polymerization of palladium, help the uniformity of the palladium-copper alloy, and help improve the selectivity.

[0035] (4) The alloy-supported Pd-Cu-Ho trimetallic catalyst was used for the selective hydrogenation of acetylene and exhibited excellent activity, ethylene selectivity and catalyst stability. DETAILED DESCRIPTION

[0036] The preferred implementation scheme of the present invention is described below in conjunction with specific examples, but it should not be understood as limiting the protection scope of the present invention. It is only for enabling those skilled in the art to better understand the technical solution of the present invention.

[0037] The room temperature described in the present invention refers to 20-35°C.

[0038] Example 1

[0039] A method for preparing an alloy-supported Pd-Cu-Ho trimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0040] 1) Weigh appropriate amounts of 5.1gAl2O3, 7.5gCoO, 7.6gCr2O3, 8gFe2O3, and 15.7gNiO into a ball mill, add grinding balls (ceramic balls) into the ball mill, correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked, set the ball mill speed to 270rpm, the ball milling time to 15h, and obtain a mixed powder after sufficient ball milling;

[0041] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0042] 3) Weigh 0.086 g of palladium chloride, 0.266 g of anhydrous cupric chloride, and 0.267 g of holmium nitrate pentahydrate and dissolve them in 5 mL of concentrated hydrochloric acid. Then add the mixed solution into 15 mL of deionized water and stir thoroughly at room temperature for 3 h to obtain a diluted mixed solution;

[0043] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0044] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating it at 450° C. for 2 h under a nitrogen atmosphere to obtain a calcined product;

[0045] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450 °C for 1 h with a reducing gas flow rate of 50 mL / min to obtain an alloy AlCoCrFeNi with a Pd loading of 0.5%, a Cu loading of 1.5%, and a Ho loading of 1%. 2.1 After reduction, acetylene mixed gas was introduced at a rate of 50 mL / min at a space velocity of 10000 h -1, pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0046] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 97.5% and the ethylene selectivity was 91.4%. After 150 hours of reaction, there was still an acetylene conversion of 95% and an ethylene selectivity of 87.3%.

[0047] Example 2

[0048] A method for preparing an alloy-supported Pd-Cu-Ho trimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0049] 1) Weigh appropriate amounts of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, and 15.7 g NiO and place them in a ball mill for mechanical alloying. Add grinding balls (ceramic balls) into the ball mill. Correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked. Set the ball mill speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0050] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0051] 3) Weigh 0.177 g of palladium chloride, 0.563 g of anhydrous cupric chloride, and 0.668 g of holmium nitrate pentahydrate and dissolve them in 5 ml of concentrated hydrochloric acid. Then add the mixed solution into 15 ml of deionized water and stir well at room temperature for 3 h to obtain a diluted mixed solution;

[0052] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0053] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating it at 450° C. for 2 h under a nitrogen atmosphere to obtain a calcined product;

[0054] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a trimetallic catalyst of AlCoCrFeNi2.1 loaded with Pd-Cu-Ho with a Pd loading of 1%, a Cu loading of 2.5% and a Ho loading of 2.5%. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h -1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0055] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 98.5% and the ethylene selectivity was 96.4%. After 200 hours of reaction, there was still an acetylene conversion of 97% and an ethylene selectivity of 91.3%.

[0056] Example 3

[0057] A method for preparing an alloy-supported Pd-Cu-Ho trimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0058] 1) Weigh appropriate amounts of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, and 15.7 g NiO and place them in a ball mill for mechanical alloying. Add grinding balls (ceramic balls) into the ball mill. Correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked. Set the ball mill speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0059] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0060] 3) Weigh 0.140 g of palladium chloride, 0.379 g of anhydrous cupric chloride, and 0.535 g of holmium nitrate pentahydrate and dissolve them in 5 ml of concentrated hydrochloric acid. Then add the mixed solution into 15 ml of deionized water and stir well at room temperature for 3 h to obtain a diluted mixed solution;

[0061] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0062] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating at 450° C. for 2 h in a nitrogen atmosphere to obtain a calcined product;

[0063] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a trimetallic catalyst of AlCoCrFeNi2.1 loaded with Pd-Cu-Ho with a Pd loading of 0.8%, a Cu loading of 1.7% and a Ho loading of 2%. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h -1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0064] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 98.5% and the ethylene selectivity was 97.3%. After 170 hours of reaction, the acetylene conversion was still 96% and the ethylene selectivity was 94%.

[0065] Comparative Example 1

[0066] A method for preparing an alloy-supported Pd-Cu bimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0067] 1) Weigh appropriate amounts of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, and 15.7 g NiO and place them in a ball mill for mechanical alloying. Add grinding balls (ceramic balls) into the ball mill. Correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked. Set the ball mill speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0068] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0069] 3) Weigh 0.085 g of palladium chloride and 0.323 g of anhydrous cupric chloride and dissolve them in 5 ml of concentrated hydrochloric acid. Then add the mixed solution into 15 ml of deionized water and stir at room temperature for 3 h to obtain a diluted mixed solution.

[0070] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0071] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating at 450° C. for 2 h in a nitrogen atmosphere to calcine the product;

[0072] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a bimetallic catalyst of AlCoCrFeNi2.1 loaded with Pd and Cu with a Pd loading of 0.5% and a Cu loading of 1.5%. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h -1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0073] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion rate was 95.5% and the ethylene selectivity was 89.4%. After the reaction was completed, the catalyst performance was an initial acetylene conversion rate of 55% and an ethylene selectivity of 60%. After 100 hours, the initial acetylene conversion rate dropped to 30% and the ethylene selectivity dropped to 45%.

[0074] Comparative Example 2

[0075] A method for preparing an alloy-supported Pd-Ho bimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0076] 1) Weigh appropriate amounts of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, and 15.7 g NiO and place them in a ball mill for mechanical alloying. Add grinding balls (ceramic balls) into the ball mill. Correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked. Set the ball mill speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0077] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0078] 3) Weigh 0.173 g of palladium chloride and 0.693 g of holmium nitrate and dissolve them in 5 ml of concentrated hydrochloric acid. Then add the mixed solution into 15 ml of deionized water and stir thoroughly at room temperature for 3 h to obtain a diluted mixed solution;

[0079] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0080] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating at 450° C. for 2 h in a nitrogen atmosphere to calcine the product;

[0081] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a Pd-Ho bimetallic catalyst loaded with 1% Pd and 2.5% Ho in an alloy AlCoCrFeNi2.1. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h -1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0082] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 95.5% and the ethylene selectivity was 80.98%. After the reaction, the catalyst performance was an initial acetylene conversion of 60% and an ethylene selectivity of 54.92%. After 100 hours, the initial acetylene conversion dropped to 50% and the ethylene selectivity dropped to 32.01%.

[0083] Comparative Example 3

[0084] A method for preparing an alloy-supported Pd monometallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0085] 1) Weigh appropriate amounts of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, and 15.7 g NiO and place them in a ball mill for mechanical alloying. Add grinding balls (ceramic balls) into the ball mill. Correctly install the ball mill containing the sample and grinding balls on the ball mill, and ensure that the fastening device is firmly locked. Set the ball mill speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0086] 2) The mechanically alloyed powder was placed in a quartz boat, and the quartz boat was placed in the center of a tube furnace. The tube was first purged with a H2 / Ar (5 vol% hydrogen) mixed gas at a flow rate of 5 ml / min to remove the air in the tube. After 30 minutes, the H2 / Ar (5 vol% hydrogen) mixed gas was continuously introduced, and the temperature was raised to 1000°C at a heating rate of 5°C / min. The alloy carrier was calcined at this temperature for 6 hours to obtain a alloy support.

[0087] 3) Weigh 0.168 g of palladium chloride and dissolve it in 5 mL of concentrated hydrochloric acid, then add the mixed solution into 15 mL of deionized water, and stir it thoroughly at room temperature for 3 h to obtain a diluted mixed solution;

[0088] 4) Weigh 10 g of the alloy support obtained above and add it to the mixed solution, stir the mixture at room temperature at 100 rpm for 10 h, place it in an oven at 120° C. and dry it for 12 h, then grind the sample into powder to obtain a mixed sample powder;

[0089] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating at 450° C. for 2 h in a nitrogen atmosphere to obtain a calcined product;

[0090] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a single metal catalyst of AlCoCrFeNi2.1 with a Pd loading of 1%. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h-1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0091] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 90.09% and the ethylene selectivity was 82.2%. After the reaction, the catalyst performance was an initial acetylene conversion of 80.65% and an ethylene selectivity of 64.32%. After 100 hours, the initial acetylene conversion dropped to 45.87% and the ethylene selectivity dropped to 20.65%.

[0092] Comparative Example 4

[0093] A method for preparing an Al2O3-loaded Pd-Cu-Ho trimetallic catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0094] 1) Weigh 0.140 g of palladium chloride, 0.379 g of anhydrous copper chloride, and 0.478 g of holmium salt and dissolve them in 5 ml of concentrated hydrochloric acid. Then add the mixed solution into 15 ml of deionized water and stir well for 3 h at room temperature to obtain a diluted mixed solution;

[0095] 2) Weigh 10 g of the commercial Al2O3 carrier and add it to the mixed solution. Stir the mixture at 100 rpm for 10 h at room temperature, place it in an oven at 120°C and dry it for 12 h. Then grind the sample into powder to obtain a mixed sample powder.

[0096] 5) placing the mixed sample powder obtained in step 4 into a tube furnace and heating at 450° C. for 2 h in a nitrogen atmosphere to obtain a calcined product;

[0097] 0.3 g of the calcined product was placed in a fixed bed reactor. Before the reaction, pure H2 was introduced for reduction at 450°C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a trimetallic catalyst of AlCoCrFeNi2.1 loaded with Pd-Cu-Ho with a Pd loading of 0.8%, a Cu loading of 1.7% and a Ho loading of 2%. After the reduction, acetylene mixed gas was introduced at a speed of 50 mL / min at a space velocity of 10000 h -1 , pressure 0.1MPa, 180℃ for hydrogenation reaction, using gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and the conversion rate of acetylene and its selectivity for ethylene are calculated by area normalization method. The volume concentration of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total amount of 100%.

[0098] Calculation based on chromatographic data showed that when the reaction reached stability, the acetylene conversion was 80.5% and the ethylene selectivity was 96.3%. After the reaction, the catalyst performance was an initial acetylene conversion of 60% and an ethylene selectivity of 50.92%. After 100 hours, the initial acetylene conversion dropped to 30.28% and the ethylene selectivity dropped to 16.87%.

Claims

1. An alloy-supported Pd-Cu-Ho trimetallic catalyst, characterized in that: The alloy-loaded Pd-Cu-Ho trimetallic catalyst comprises a carrier and an active component, wherein the carrier is AlCoCrFeNi 2.1 Alloy, the AlCoCrFeNi 2.1 In the alloy, the molar ratio of Al, Co, Cr, Fe and Ni is 1:1:1:1:2.

1. The active component is composed of three metals: Pd, Cu and Ho. In terms of mass ratio, palladium: Copper: Holmium = (0.5-1): (1.2-2.5): (0.5-2.5).

2. The alloy-supported Pd-Cu-Ho trimetallic catalyst according to claim 1, characterized in that: In the alloy-loaded Pd-Cu-Ho trimetallic catalyst, the mass of palladium accounts for 0.5%-1% of the total mass of the catalyst, the mass of copper accounts for 1.2%-2.5% of the total mass of the catalyst, and the mass of holmium accounts for 0.5%-2.5% of the total mass of the catalyst, wherein the total mass of the catalyst = m 载体 +m Pd +m Cu +m Ho .

3. A method for preparing the alloy-supported Pd-Cu-Ho trimetallic catalyst as claimed in claim 1 or 2, characterized in that: The preparation method comprises the following steps: Step 1: Weigh aluminum source, cobalt source, chromium source, iron source and nickel source and place them in a ball mill for mechanical alloying; Step 2: The mechanically alloyed powder is calcined at high temperature in a hydrogen-argon mixed gas atmosphere to obtain AlCoCrFeNi 2.1 Alloy carrier; Step 3: Weigh palladium salt, copper salt and holmium salt, dissolve them in a solvent, and stir them thoroughly at room temperature to obtain a mixed solution; Step 4: AlCoCrFeNi obtained in step 2 2.1 The alloy carrier is placed in the mixed solution obtained in step 3, and the mixture is stirred at room temperature for 8-12 hours, and then ground into powder after drying to obtain a mixed sample powder; Step 5: placing the mixed sample powder obtained in step 4 in an inert gas environment and calcining at high temperature to obtain a calcined product; Step 6: The calcined product obtained in step 5 is reduced under a hydrogen atmosphere to obtain an alloy-loaded Pd-Cu-Ho trimetallic catalyst.

4. The preparation method according to claim 3, characterized in that: In step 1, the aluminum source is Al2O3, the cobalt source is CoO, the chromium source is Cr2O3, the iron source is Fe2O3, and the nickel source is NiO.

5. The preparation method according to claim 3, characterized in that: In step 1, the mechanical alloying conditions are: ball milling speed is 200rpm-500rpm, and ball milling time is 10-30h.

6. The preparation method according to claim 3, characterized in that: In step 2, the volume percentage content of hydrogen in the hydrogen-argon mixed gas is 3-7 vol%, and the flow rate of the hydrogen-argon mixed gas is 1-10 ml / min; the high-temperature calcination has a calcination temperature of 800-1200° C. and a calcination time of 4-10 h.

7. The preparation method according to claim 3, characterized in that: In step 3, the palladium salt is selected from at least one of palladium dichloride, sodium tetrachloropalladate and dichlorotetraamminepalladium; the copper salt is selected from at least one of copper chloride, copper sulfate, copper nitrate, copper acetate and copper carbonate; the holmium salt is selected from holmium nitrate pentahydrate and cyclopentadienyl holmium dichloride; and the solvent is deionized water or hydrochloric acid.

8. The preparation method according to claim 3, characterized in that: In step 5, the calcination temperature is controlled at 200-500°C; and the calcination time is controlled at 0.5-3h.

9. The preparation method according to claim 3, characterized in that: In step six, the hydrogen flow rate is 30-70 mL / min, the reduction temperature is 200-600° C., and the reduction time is 1-6 h.

10. Use of the alloy-supported Pd-Cu-Ho trimetallic catalyst as claimed in claim 1 in acetylene semi-hydrogenation reaction.