Alloy supported pd-cu-ho trimetallic catalyst, preparation thereof and use thereof in the semi-hydrogenation of acetylene

Abstract

The application discloses an alloy-supported Pd-Cu-Ho trimetallic catalyst, a preparation method thereof and application of the catalyst in an ethyne semi-hydrogenation reaction. 2.1 The alloy-supported Pd-Cu-Ho trimetallic catalyst comprises a carrier and an active component, the carrier is AlCoCrFeNi 2.1 alloy, and the active component is composed of Pd, Cu and Ho. The application provides the application of the alloy-supported Pd-Cu-Ho trimetallic catalyst in the ethyne semi-hydrogenation reaction, and the catalyst exhibits excellent activity, ethylene selectivity and catalyst stability.

Description

TECHNICAL FIELD

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

[0002] Selective hydrogenation of hydrocarbons is a very important process in the petrochemical industry. Selective hydrogenation of acetylene is to convert trace amounts of acetylene (C2H2) impurities in an ethylene stream into ethylene (C2H4) while preventing excessive hydrogenation of ethylene into unwanted ethane (C2H6), which becomes 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 which case acetylene (C2H2) is more inclined to be adsorbed in a bridging mode on adjacent palladium atom sites rather than in a pi-type adsorption on isolated palladium atoms. This adsorption mode leads to excessive hydrogenation of C2H2 into C2H6, thereby causing a decrease in product selectivity and problems of coke deposition on the catalyst surface, which makes it difficult for the catalyst to maintain high ethylene selectivity and shortens the effective service life of the catalyst. Cu-based catalysts exhibit high ethylene selectivity due to their strong adsorption of acetylene and weak adsorption of ethylene, which has attracted widespread attention in academia and industry. However, such catalysts also have some drawbacks, such as weak dissociation ability for hydrogen, which leads to low catalytic activity, and easy occurrence of C-C polymerization to generate green oil, thereby causing catalyst deactivation. Rare earth elements have been proven to effectively inhibit catalyst deactivation. Adding rare earth elements into metal catalysts can significantly enhance the stability of the catalysts, which has extremely high application value. High-entropy alloys (HEAs) as a new emerging catalytic material create a broad space for material design through the combination of multiple elements, and thus have excellent mechanical properties. In addition, due to their extremely efficient electron transfer characteristics, high-entropy alloy materials have a promising application prospect in the field of catalysis.

[0004] Based on the above background, the application provides an AlCoCrFeNi 2.1 The alloy-supported Pd-Cu-Ho trimetallic catalyst can improve the selectivity and stability of the Pd catalyst in the acetylene semi-hydrogenation reaction. SUMMARY

[0005] The application aims to provide an AlCoCrFeNi 2.1A trimetallic catalyst supported on Pd-Cu-Ho alloy, its preparation, and its application in the acetylene semi-hydrogenation reaction. This catalyst solves the problems of short life, poor stability, and high cost of traditional palladium-based catalysts in the acetylene semi-hydrogenation reaction.

[0006] The technical solution adopted in this invention will be described in detail below.

[0007] In a first aspect, the present invention provides a trimetallic catalyst supported on an alloy Pd-Cu-Ho, comprising a support and an active component, wherein the support 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 consists of three metals: Pd, Cu, and Ho, with the mass ratio of palladium:copper:holmium being (0.5-1):(1.2-2.5):(0.5-2.5).

[0008] Preferably, in the alloy-supported Pd-Cu-Ho trimetallic catalyst, palladium accounts for 0.5%-1% of the total catalyst mass, copper accounts for 1.2%-2.5% of the total catalyst mass, and holmium accounts for 0.5%-2.5% of the total catalyst mass, wherein the total catalyst mass = 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 as described in the first aspect, the 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 atmosphere to obtain AlCoCrFeNi. 2.1 Alloy carrier;

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

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

[0014] Step five: the mixed sample powder obtained in step four is calcined at high temperature in an inert gas environment to obtain a calcined product;

[0015] Step six: the calcined product obtained in step five is reduced in a hydrogen atmosphere to obtain a ternary metal catalyst of alloy supported Pd-Cu-Ho.

[0016] As a preferred, in step one, 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] As a preferred, in step one, the mechanical alloying conditions are: ball milling speed of 200 rpm-500 rpm, ball milling time of 10-30 h, more preferably ball milling speed of 270 rpm, and ball milling time of 15 h.

[0018] As a preferred, in step two, the hydrogen content 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] As a preferred, in step two, the high-temperature calcination is carried out at a calcination temperature of 800-1200℃ for 4-10 h, more preferably at a calcination temperature of 1000℃ for 6 h.

[0021] As a preferred, in step three, the palladium salt is selected from at least one of palladium dichloride, sodium tetrachloropalladate, and dichlorotetraammine palladium; more preferably palladium dichloride.

[0022] As a preferred, 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] As a preferred, in step three, the holmium salt is selected from at least one of holmium nitrate pentahydrate and cyclopentadienyl holmium dichloride; more preferably holmium nitrate.

[0024] As a preferred, the solvent is deionized water or hydrochloric acid.

[0025] As a preferred, in step four, the drying conditions are: drying at 80-120℃ for 8-12 h.

[0026] As a preferred, in step five, the calcination temperature is controlled at 200-500℃, more preferably 450℃; and the calcination time is controlled at 0.5-3 h, more preferably 2 h.

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

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

[0029] The method of application is as follows: A feed gas containing acetylene and hydrogen is added to a reactor containing an alloy-supported Pd-Cu-Ho atmosphere, and the mixture is subjected to a space velocity of 5000–20000 h⁻¹. -1 (More preferably 10000h) -1 The hydrogenation reaction is carried out under conditions of temperature 70–250°C (more preferably 180°C) and pressure 0.1–1 MPa (more preferably 0.1 MPa) to convert acetylene into ethylene.

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

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

[0032] (1) This invention uses a common method for preparing alloys, namely mechanical alloying and high-temperature calcination in a hydrogen-argon mixture, to prepare AlCoCrFeNi. 2.1 This alloying method is simpler and more environmentally friendly than traditional processes. The resulting AlCoCrFeNi alloy... 2.1 The alloy has extremely efficient electron transfer characteristics, and using it as a catalyst support gives the catalyst good catalytic 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, which helps to improve the uniformity of palladium-copper alloy and can improve selectivity.

[0035] (4) The alloy-supported Pd-Cu-Ho trimetallic catalyst exhibits excellent activity, ethylene selectivity and catalyst stability in the selective hydrogenation reaction of acetylene. Detailed Implementation

[0036] The preferred embodiments of the present invention are described below with reference to specific examples, but they should not be construed as limiting the scope of protection of the present invention. They are merely intended to enable those skilled in the art to better understand the technical solutions of the present invention.

[0037] The room temperature mentioned in this invention refers to 20-35℃.

[0038] Example 1

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

[0040] 1) Take an appropriate amount of 5.1 g of Al203, 7.5 g of CoO, 7.6 g of Cr203, 8 g of Fe203, and 15.7 g of NiO into a ball mill jar, add grinding balls (ceramic balls) to the ball mill jar, properly install the ball mill jar containing the sample and grinding balls on the ball mill, and ensure that the fastening device has been firmly locked. Set the ball milling speed to 270 rpm, and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0041] 2) Put the mechanically alloyed powder into a quartz boat, and place the quartz boat in the center of a tube furnace. First, use H2 / Ar (5 vol% hydrogen) mixed gas to purge the tube, with a flow rate of 5 ml / min. Remove the air in the tube, and then continuously introduce H2 / Ar (5 vol% hydrogen) mixed gas after 30 min, and increase the temperature to 1000°C at a rate of 5°C / min. Calcine at this temperature for 6 hours to obtain an alloy support;

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

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

[0044] 5) Put the mixed sample powder obtained in step four into a tube furnace, and heat at 450°C for 2 h under a nitrogen atmosphere to obtain a calcined product;

[0045] Put 0.3 g of the calcined product into a fixed bed reactor. Before the reaction, introduce pure H2 to reduce at 450°C for 1 h, with a flow rate of 50 mL / min. A three-metallic catalyst of alloy AlCoCrFeNi supported Pd-Cu-Ho is obtained, with a Pd loading of 0.5%, a Cu loading of 1.5%, and a Ho loading of 1%; 2.1 After reduction, introduce acetylene mixed gas at a speed of 50 mL / min, with a space velocity of 10000 h -1The hydrogenation reaction was carried out at a pressure of 0.1 MPa and a temperature of 180°C, and the peak areas of ethane, ethylene, acetylene and C4 were detected on-line by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene were obtained by area normalization method. The volume concentration of acetylene mixed gas is composed of 0.33% acetylene, 6.6% hydrogen, 33% ethylene and the balance of nitrogen, and the total amount is 100%.

[0046] According to the chromatographic data, when the reaction reaches stability, the conversion rate of acetylene is 97.5%, and the selectivity of ethylene is 91.4%. After 150 hours of reaction, the conversion rate of acetylene is still 95%, and the selectivity of ethylene is 87.3%.

[0047] Example 2

[0048] A preparation method of a three-metal catalyst of alloy-supported Pd-Cu-Ho for selective hydrogenation of acetylene, the method comprising the following steps:

[0049] 1) Weigh an appropriate amount of 5.1 g of Al2O3, 7.5 g of CoO, 7.6 g of Cr2O3, 8 g of Fe2O3, and 15.7 g of NiO into a ball mill jar for mechanical alloying. Add grinding balls (ceramic balls) to the ball mill jar. Install the ball mill jar with the sample and grinding balls on the ball mill correctly and make sure that the fastening device is securely locked. Set the ball milling speed to 270 rpm and the ball milling time to 15 h. After sufficient ball milling, a mixed powder is obtained;

[0050] 2) Put the mechanically alloyed powder into a quartz boat and place the quartz boat in the center of a tube furnace. First, use H2 / Ar (5 vol% hydrogen) mixed gas to purge the tube. The flow rate of H2 / Ar (5 vol% hydrogen) gas is 5 ml / min. Remove the air in the tube. After 30 minutes, continue to flow H2 / Ar (5 vol% hydrogen) mixed gas and increase the temperature to 1000°C at a rate of 5°C / min. Calcine at this temperature for 6 hours to obtain an alloy carrier;

[0051] 3) Weigh 0.177 g of palladium chloride, 0.563 g of anhydrous copper chloride, and 0.668 g of holmium nitrate pentahydrate into 5 ml of concentrated hydrochloric acid. Then add the mixed solution to 15 mL of deionized water. Stir thoroughly at room temperature for 3 hours to obtain a diluted mixed solution;

[0052] 4) Weigh 10 g of the above obtained alloy carrier into the above mixed solution. Stir the mixture at a speed of 100 rpm for 10 hours at room temperature. Dry in an oven at 120°C for 12 hours. Then grind the sample into powder to obtain a mixed sample powder;

[0053] 5) Put the mixed sample powder obtained in step four into a tube furnace and heat at 450°C for 2 hours under nitrogen atmosphere to obtain a calcined product;

[0054] The 0.3 g calcined product was placed in a fixed bed reactor, before the reaction, pure H2was introduced at 450℃ for 1 h, the reduction gas flow rate was 50 mL / min, to obtain the Pd loading 1%, Cu loading 2.5%, Ho loading 2.5% alloy AlCoCrFeNi2.1 supported Pd-Cu-Ho trimetallic catalyst; after reduction, acetylene mixed gas was introduced at a speed of 50 mL / min, under the conditions of space velocity 10000 h-1, pressure 0.1 MPa, 180℃, the hydrogenation reaction was carried out, and the peak areas of ethane, ethylene, acetylene and C4were detected online by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene were obtained by area normalization method. The volume concentration composition of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, the total amount is 100%. -1 、pressure 0.1 MPa, 180℃, the hydrogenation reaction was carried out, and the peak areas of ethane, ethylene, acetylene, C4were detected online by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene were obtained by area normalization method. The volume concentration composition of acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, the total amount is 100%.

[0055] According to the chromatographic data, when the reaction reaches stability, the conversion rate of acetylene is 98.5%, and the selectivity of ethylene is 96.4%, after 200 h of reaction, there is still 97% of acetylene conversion rate and 91.3% of ethylene selectivity.

[0056] Example 3

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

[0058] 1) Take an appropriate amount of 5.1 g Al2O3, 7.5 g CoO, 7.6 g Cr2O3, 8 g Fe2O3, 15.7 g NiO into a ball mill jar for mechanical alloying, add grinding balls (ceramic balls) to the ball mill jar, install the ball mill jar with samples and grinding balls on the ball mill correctly, and make sure that the fastening device has been tightly locked, set the ball milling speed to 270 rpm, and the ball milling time to 15 h, and obtain a mixed powder after sufficient ball milling;

[0059] 2) Put the mechanically alloyed powder into a quartz boat, and place the quartz boat in the center of a tube furnace, first use H2 / Ar (5 vol% hydrogen) mixed gas to purge the tube, the H2 / Ar (5 vol% hydrogen) gas flow rate is 5 ml / min, remove the air in the tube, 30 min later, continue to introduce H2 / Ar (5 vol% hydrogen) mixed gas, and increase the temperature to 1000℃ at a rate of 5℃ / min, and calcine at this temperature for 6 hours to obtain an alloy carrier;

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

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

[0062] 5) Put the mixed sample powder obtained in step four into a tube furnace, heat at 450 °C for 2 h in a nitrogen atmosphere to obtain a calcined product;

[0063] Place 0.3 g of the calcined product into a fixed bed reactor, before the reaction, pass pure H2 to reduce at 450 °C for 1 h, the reduction gas flow rate is 50 mL / min, to obtain a Pd-Cu-Ho alloy AlCoCrFeNi2.1 supported Pd-Cu-Ho trimetallic catalyst with a Pd loading of 0.8%, a Cu loading of 1.7%, and a Ho loading of 2%; after reduction, pass acetylene mixed gas at a speed of 50 mL / min, and perform hydrogenation reaction at a space velocity of 10000 h-1, a pressure of 0.1 MPa, and 180 °C, and use gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and obtain the acetylene conversion rate and the ethylene selectivity by area normalization method. The acetylene mixed gas volume concentration composition is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, and the total amount is 100%. -1

[0064] According to the chromatographic data, when the reaction reaches stability, the acetylene conversion rate is 98.5%, and the ethylene selectivity is 97.3%, and after 170 h of reaction, there is still 96% of acetylene conversion rate and 94% of ethylene selectivity.

[0065] Comparative Example 1

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

[0067] 1) Weigh an appropriate amount of 5.1 g of Al2O3, 7.5 g of CoO, 7.6 g of Cr2O3, 8 g of Fe2O3, and 15.7 g of NiO into a ball mill jar in a mechanical alloying machine, add grinding balls (ceramic balls) to the ball mill jar, correctly install the ball mill jar containing the sample and grinding balls on the ball mill machine, and ensure that the fastening device has been firmly locked, set the ball milling speed to 270 rpm, and the ball milling time to 15 h, and obtain a mixed powder after sufficient ball milling;

[0068] ​2) Put the mechanically alloyed powder into a quartz boat, and put the quartz boat into the center of a tube furnace. First, use H2 / Ar (5 vol% hydrogen) mixed gas to purge the tube, with a flow rate of 5 ml / min. Remove the air in the tube, and then continuously pass the H2 / Ar (5 vol% hydrogen) mixed gas into the tube, and increase the temperature to 1000°C at a rate of 5°C / min. Keep the temperature at 1000°C for 6 hours to obtain the alloy carrier;

[0069] 3) Weigh 0.085 g of palladium chloride and 0.323 g of anhydrous copper chloride into 5 ml of concentrated hydrochloric acid, and then add the mixed solution into 15 mL of deionized water. Stir at room temperature for 3 hours to obtain a diluted mixed solution;

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

[0071] 5) Put the mixed sample powder obtained in step four into a tube furnace, and heat at 450°C for 2 hours in a nitrogen atmosphere to calcine the product;

[0072] Put 0.3 g of the calcined product into a fixed bed reactor. Before the reaction, pass pure H2 into the reactor at a flow rate of 50 mL / min to reduce at 450°C for 1 hour to obtain a Pd-Cu alloy AlCoCrFeNi2.1 supported Pd-Cu bimetallic catalyst with a Pd loading of 0.5% and a Cu loading of 1.5%. After reduction, pass acetylene mixed gas into the reactor at a flow rate of 50 mL / min to perform hydrogenation at a space velocity of 10000 h-1, a pressure of 0.1 MPa, and a temperature of 180°C. Use gas chromatography to detect the peak areas of ethane, ethylene, acetylene, and C4 online, and use the area normalization method to calculate the acetylene conversion rate and the ethylene selectivity. The volume concentration of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%. -1

[0073] According to the chromatographic data, when the reaction reaches a steady state, the acetylene conversion rate is 95.5%, and the ethylene selectivity is 89.4%. After the reaction is completed, the initial acetylene conversion rate of the catalyst is 55%, and the ethylene selectivity is 60%. After 100 hours, the initial acetylene conversion rate decreases to 30%, and the ethylene selectivity decreases 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 out appropriate amounts of 5.1g Al2O3, 7.5g CoO, 7.6g Cr2O3, 8g Fe2O3, and 15.7g NiO and place them in a ball mill jar for mechanical alloying. Add grinding balls (ceramic balls) to the ball mill jar. Correctly install the ball mill jar containing the sample and grinding balls onto 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 hours. After thorough ball milling, a mixed powder is obtained.

[0077] 2) Place the mechanically alloyed powder in a quartz boat, place the quartz boat in the center of a tube furnace, first purge the tube with a H2 / Ar (5 vol% hydrogen) gas mixture at a flow rate of 5 ml / min to remove air from the tube, and after 30 min, continuously introduce the H2 / Ar (5 vol% hydrogen) gas mixture and raise the temperature to 1000℃ at a rate of 5℃ / min. Calcinate at this temperature for 6 hours to obtain the alloy carrier;

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

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

[0080] 5) Place the mixed sample powder obtained in step four into a tube furnace and heat it at 450°C for 2 hours 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 and reduced at 450 °C for 1 h at a reducing gas flow rate of 50 mL / min to obtain a Pd-Ho supported bimetallic catalyst AlCoCrFeNi2.1 with 1% Pd loading and 2.5% Ho loading. After reduction, an acetylene mixture was introduced at a rate of 50 mL / min at a space velocity of 10000 h⁻¹. -1 The hydrogenation reaction was carried out at a pressure of 0.1 MPa and a temperature of 180 °C. The peak areas of ethane, ethylene, acetylene, and C4 were detected online using gas chromatography, and the conversion rate of acetylene and the selectivity for ethylene were determined by area normalization. The volume concentration composition of the acetylene mixture was: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, with the balance being nitrogen, totaling 100%.

[0082] The data calculated from the chromatogram shows that when the reaction reaches stability, the conversion rate of acetylene is 95.5%, the selectivity of ethylene is 80.98%, after the reaction, the initial conversion rate of acetylene is 60%, the selectivity of ethylene is 54.92%, and after 100h, the initial conversion rate of acetylene is reduced to 50%, and the selectivity of ethylene is reduced to 32.01%.

[0083] Comparative Example 3

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

[0085] 1) Take an appropriate amount of 5.1g Al2O3, 7.5g CoO, 7.6g Cr2O3, 8g Fe2O3, 15.7g NiO into a ball mill jar for mechanical alloying, add grinding balls (ceramic balls) to the ball mill jar, install the ball mill jar containing the sample and grinding balls on the ball mill correctly, and make sure that the fastening device has been tightly locked, set the ball milling speed to 270rpm, and the ball milling time to 15h, and after sufficient ball milling, a mixed powder is obtained;

[0086] 2) Put the mechanically alloyed powder into a quartz boat, and put the quartz boat in the center of a tube furnace, first use H2 / Ar (5vol% hydrogen) mixed gas to purge the tube, the flow rate of H2 / Ar (5vol% hydrogen) gas is 5ml / min, remove the air in the tube, 30min later, continue to pass H2 / Ar (5vol% hydrogen) mixed gas, and increase the temperature to 1000℃ at a rate of 5℃ / min, and calcine at this temperature for 6 hours, to obtain an alloy support;

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

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

[0089] 5) Put the mixed sample powder obtained in step four into a tube furnace, heat it at 450℃ for 2h in a nitrogen atmosphere to obtain a calcined product;

[0090] Put 0.3g of the calcined product into a fixed bed reactor, before the reaction, pass pure H2 to reduce it at 450℃ for 1h, the flow rate of the reducing gas is 50mL / min, to obtain a Pd loading of 1% alloy AlCoCrFeNi2.1 supported Pd monometallic catalyst; after reduction, pass acetylene mixed gas at a speed of 50mL / min, the space velocity is 10000h-1 The hydrogenation reaction was carried out at 0.1 MPa and 180°C, and the peak areas of ethane, ethylene, acetylene and C4 were detected on-line by gas chromatography, and the conversion of acetylene and the selectivity of ethylene were obtained by area normalization method. The volume concentration of acetylene mixed gas was composed of 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance was nitrogen, and the total amount was 100%.

[0091] According to the chromatographic data, when the reaction reached stability, the acetylene conversion rate was 90.09%, the ethylene selectivity was 82.2%, after the reaction, the initial acetylene conversion rate of the catalyst was 80.65%, the ethylene selectivity was 64.32%, and after 100h, the initial acetylene conversion rate decreased to 45.87%, and the ethylene selectivity decreased to 20.65%.

[0092] Comparative Example 4

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

[0094] 1) 0.140g of palladium chloride, 0.379g of anhydrous copper chloride, and 0.478g of holmium salt were weighed and dissolved in 5ml of concentrated hydrochloric acid, and then the mixed solution was added to 15ml of deionized water, and stirred at room temperature for 3h to obtain a diluted mixed solution;

[0095] 2) 10g of the above commercial Al2O3 carrier was weighed and added to the above mixed solution, and the mixture was stirred at room temperature at a speed of 100rpm for 10h, and then dried in an oven at 120°C for 12h, and then the sample was ground into powder to obtain a mixed sample powder;

[0096] 5) The mixed sample powder obtained in step four was placed in a tube furnace and heated at 450°C for 2h under nitrogen atmosphere to obtain a calcined product;

[0097] 0.3g of the calcined product was placed in a fixed bed reactor, before the reaction, pure H2 was introduced and reduced at 450°C for 1h, the reduction gas flow rate was 50mL / min, and the alloy AlCoCrFeNi2.1 supported Pd-Cu-Ho trimetallic catalyst with Pd loading of 0.8%, Cu loading of 1.7% and Ho loading of 2% was obtained; after reduction, acetylene mixed gas was introduced at a speed of 50mL / min, the space velocity was 10000h -1 The hydrogenation reaction was carried out at 0.1 MPa and 180°C, and the peak areas of ethane, ethylene, acetylene and C4 were detected on-line by gas chromatography, and the conversion of acetylene and the selectivity of ethylene were obtained by area normalization method. The volume concentration of acetylene mixed gas was composed of 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance was nitrogen, and the total amount was 100%.

[0098] The chromatographic data showed that when the reaction reached stability, the conversion of ethyne was 80.5%, the selectivity of ethylene was 96.3%. After the reaction, the initial conversion of ethyne was 60%, the selectivity of ethylene was 50.92%, and after 100 h, the initial conversion of ethyne was reduced to 30.28%, and the selectivity of ethylene was reduced to 16.87%.

Claims

1. A ternary metal catalyst of alloy supported Pd-Cu-Ho characterized by: The alloy-supported Pd-Cu-Ho trimetallic catalyst comprises a support and an active component, wherein the support 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 consists of three metals: Pd, Cu, and Ho, wherein, by mass ratio, palladium: Copper:Holmium=(0.5-1):(1.2-2.5):(0.5-2.5).

2. The ternary metal catalyst alloy supported Pd-Cu-Ho of claim 1, wherein: The alloy supported Pd-Cu-Ho trimetallic catalyst has the following composition: 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 producing a ternary metal catalyst of the alloy supported Pd-Cu-Ho according to claim 1 or 2, characterized by: The preparation method comprises the following steps: Step one: weigh the aluminum source, cobalt source, chromium source, iron source, nickel source and place them in a ball mill for mechanical alloying; Step two: the mechanically alloyed powder is calcined at high temperature in a hydrogen-argon mixed gas atmosphere to obtain AlCoCrFeNi 2.1 alloy carrier; Step three: weigh the palladium salt, copper salt and holmium salt, dissolve them in a solvent, and stir thoroughly at room temperature to obtain a mixed solution; Step four: The AlCoCrFeNi 2.1 alloy carrier obtained in step two was placed in the mixed solution obtained in step three, and the mixture was stirred at room temperature for 8-12 h. After drying, the mixture was ground into powder to obtain a mixed sample powder. Step five: place the mixed sample powder obtained in step four in an inert gas environment and calcine at high temperature to obtain a calcined product; Step six: reduce the calcined product obtained in step five under a hydrogen atmosphere to obtain a three-metallic catalyst of alloy-supported Pd-Cu-Ho.

4. The production method according to claim 3, characterized by: In step one, 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 production method according to claim 3, characterized by: In step one, the mechanical alloying conditions are: ball milling speed of 200-500 rpm, and ball milling time of 10-30 h.

6. The production method according to claim 3, wherein: In step two, the hydrogen content 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 is carried out at a calcination temperature of 800-1200°C for 4-10 h.

7. The production method according to claim 3, wherein: In step three, the palladium salt is selected from at least one of palladium dichloride, sodium tetrachloropalladate and dichlorotetraammine palladium; 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 dichlorocyclopentadienyl holmium; and the solvent is deionized water or hydrochloric acid.

8. The production method according to claim 3, wherein: In step five, the calcination temperature is controlled at 200-500°C, and the calcination time is controlled at 0.5-3 h.

9. The production method according to claim 3, wherein: 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 three-metallic catalyst of alloy-supported Pd-Cu-Ho according to claim 1 in an ethyne semi-hydrogenation reaction.