Pd-Cu-M / alpha-Si3N4 supported metal catalyst as well as preparation and application thereof

Abstract

The invention discloses a Pd-Cu-M / alpha-Si3N4 supported metal catalyst as well as preparation and application of the Pd-Cu-M / alpha-Si3N4 supported metal catalyst. The preparation method comprises the following steps: 1) dissolving palladium acetylacetonate, copper acetylacetonate and acetylacetone salt of metal M in a solvent to prepare a precursor solution, adding an alpha-Si3N4 carrier, and fully stirring to obtain a suspension; the metal M is a rare earth metal element; (2) transferring the suspension obtained in the step (1) into a steel high-pressure kettle with a polytetrafluoroethylene lining, sealing, heating in an induction heating electric furnace, and cooling to room temperature; and (3) centrifuging the suspension cooled in the step (2), collecting solids, washing and drying the solids, and obtaining the Pd-Cu-M / alpha-Si3N4 supported metal catalyst after drying is finished. The invention provides the application of the catalyst in low-temperature hydrogen catalytic oxidation reaction, and the catalyst has high hydrogen conversion rate and excellent stability.

Description

Technical Field

[0001] The present invention relates to catalyst preparation technology and application field, and specifically to an α-Si3N4 supported metal catalyst (Pd-Cu-M (M is a rare earth element)) and its preparation and application in low-temperature hydrogen catalytic oxidation reaction. Background Art

[0002] Hydrogen energy, a highly acclaimed environmentally friendly energy source, has a wide range of applications, covering multiple industries such as chemical industry, new energy, ships, submarines and even nuclear energy. However, the characteristics of hydrogen also bring challenges. As a highly flammable and explosive gas, when its concentration reaches 4% or above, it is very easy to cause combustion or explosion accidents when encountering a fire source. Therefore, in scenarios where hydrogen leaks or is a by-product of the production process, it is crucial to take effective measures to remove hydrogen. For example, in nuclear submarines, hydrogen is released as a by-product while oxygen is produced using water electrolysis technology. If this process is not properly controlled, it may lead to hydrogen leakage. In conventional submarines, batteries, as the main source of electricity, also produce hydrogen during the charging and discharging process. In these hydrogen-producing environments, especially confined spaces such as submarines and nuclear power plants, if the accumulation of hydrogen exceeds the critical value of 4%, the risk of serious accidents will be greatly increased. In view of this, the development and implementation of safe and reliable hydrogen elimination strategies are particularly critical to ensure the safety of personnel and the integrity of facilities. To meet this challenge, researchers and engineers are actively exploring a variety of technical means, including but not limited to the use of catalytic conversion, adsorption and chemical reactions to safely handle and eliminate hydrogen, to ensure that potential safety hazards can be effectively prevented and controlled in various fields involving hydrogen, thereby promoting the sustainable and safe application of hydrogen energy.

[0003] At present, the mainstream method of eliminating hydrogen is to use the chemical combination of hydrogen and oxygen to generate harmless water. This hydrogen oxidation process is mainly divided into three categories according to different technical paths: direct combustion method, heating catalytic method and catalytic composite reaction method. Although the direct combustion method reacts quickly, its difficult-to-control characteristics limit its application; the heating catalytic method is less efficient because it needs to react at high temperatures; in contrast, the catalytic hydrogen-oxygen composite technology, with the assistance of a catalyst, can not only significantly increase the hydrogen oxidation rate, but also effectively reduce the temperature required for the reaction, showing significant advantages. Catalytic hydrogen oxidation technology, with its high-efficiency catalytic combustion, low environmental impact, and the characteristics of reacting at temperatures far lower than traditional flame combustion, coupled with its high safety performance, is regarded as one of the most effective technologies for eliminating hydrogen at present, especially suitable for places with extremely high safety requirements such as nuclear power plants. Existing hydrogen oxidation catalysts mainly use precious metals or non-precious metals as active components, but precious metals are expensive, and non-precious metals need to be preheated before they react. Catalysts still face challenges in practical applications. "Poisons" such as CO, CO2, iodine, and water vapor in the air may compete with reactants for adsorption sites, seriously interfering with the activity of the catalyst, and even causing the catalyst to be completely deactivated, which has become a major obstacle to the promotion and application of this technology. To overcome this problem, researchers are working to develop new catalysts to enhance their stability and activity in complex environments, while exploring catalyst regeneration and protection technologies to extend the service life of the catalyst and ensure the efficiency and reliability of hydrogen elimination technology, thereby further promoting the widespread application and safe use of hydrogen energy.

[0004] Based on the above background, it is necessary to develop improved catalytic materials and design a suitable catalyst for use in low-temperature hydrogen catalytic oxidation reactions to achieve efficient hydrogen removal and maintain high-efficiency catalysis for a long time. Summary of the invention

[0005] In order to overcome the problems of high cost of precious metal catalysts used in existing hydrogen catalytic oxidation gas-solid phase reactions, the need for preheating of non-precious metal catalysts at a certain temperature before they can react, and the widespread existence of catalyst "poisoning" and deactivation, the present invention provides a method for preparing an α-Si3N4-supported metal catalyst (Pd-Cu-M (M is a rare earth element)), as well as the prepared α-Si3N4-supported metal catalyst and its application in low-temperature hydrogen catalytic oxidation reactions; the catalyst prepared by the present invention has a high hydrogen conversion rate in the hydrogen catalytic oxidation reaction and has excellent stability.

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

[0007] In a first aspect, the present invention provides a method for preparing a Pd-Cu-M / α-Si3N4 supported metal catalyst, comprising the following steps:

[0008] Step 1): dissolving acetylacetonate palladium, acetylacetonate copper and acetylacetonate salt of metal M in a solvent to prepare a precursor solution, adding an α-Si3N4 carrier, and stirring thoroughly to obtain a suspension; the feed ratio of the α-Si3N4 carrier to acetylacetonate palladium, acetylacetonate copper and acetylacetonate salt of metal M is 100: 0.03-0.05: 4-10: 4-10 based on the mass ratio of the α-Si3N4 carrier to the palladium, copper and metal M contained in the three acetylacetonate salts; the metal M is a rare earth metal element;

[0009] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at a temperature of 400 to 600° C. for 3 to 6 hours, and then cooled to room temperature;

[0010] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, which is then washed and dried to obtain a Pd-Cu-M / α-Si3N4 supported metal catalyst.

[0011] Furthermore, the metal M in step 1) is selected from one or more of La, Ce, Nd, Pr, Sm, Tb, Er, and Y.

[0012] Furthermore, the solvent for preparing the precursor solution in step 1) is one or more of methanol, ethanol, and acetone; preferably a mixed solution of ethanol and acetone, wherein the volume ratio of ethanol to acetone is preferably 1:1 to 1:2.

[0013] Furthermore, the stirring conditions in step 1) are: a stirring rate of 300 to 400 r / min and a stirring time of 20 to 40 min.

[0014] Furthermore, in the centrifugation operation described in step 3), the rotation speed is 4000-6000 rpm and the centrifugation time is 10-20 min.

[0015] Furthermore, in step 3), the detergent is one or more of methanol, ethanol, and acetone; preferably ethanol and acetone, each for 2 to 3 times.

[0016] Furthermore, the drying in step 3) is carried out in a vacuum drying oven at a drying temperature of 60 to 80° C. and a drying time of 6 to 12 hours.

[0017] In a second aspect, the present invention provides a Pd-Cu-M / α-Si3N4 supported metal catalyst prepared according to the preparation method described in the first aspect.

[0018] In a third aspect, the present invention provides the use of the Pd-Cu-M / α-Si3N4 supported metal catalyst described in the second aspect in a low-temperature hydrogen catalytic oxidation reaction.

[0019] The specific application is: in a fixed bed reactor, the Pd-Cu-M / α-Si3N4 supported metal catalyst is loaded, and raw gas is introduced, wherein the raw gas includes hydrogen and oxygen, and the reaction temperature is set to 25-30°C and the reaction pressure is set to normal pressure, and hydrogen is oxidized to generate water under the action of the Pd-Cu-M / α-Si3N4 supported metal catalyst.

[0020] The raw gas generally also includes CO, CO2 and nitrogen.

[0021] Furthermore, the ratio of the amount of substances in the raw gas is n(O2):n(H2)=1:2, and the hydrogen space velocity is 6000-10000h -1 .

[0022] The Pd-Cu-M / α-Si3N4 supported metal catalyst prepared by the present invention has high catalytic activity in the above-mentioned low-temperature hydrogen catalytic oxidation reaction, the hydrogen conversion rate can reach up to more than 98%, and the catalyst has excellent stability.

[0023] Compared with the prior art, the present invention has the following innovations and technical advantages:

[0024] (1) The present invention uses commercially purchased α-Si3N4 as a carrier to provide a catalyst with a structure with good mechanical strength, so that the active material is evenly dispersed, the catalyst has a high hydrogen conversion rate, and has excellent stability.

[0025] (2) The catalyst adopts the coordinated effect of Pd and Cu, and the rare earth metal is used as an auxiliary agent, which greatly reduces the amount of Pd without losing activity, thereby saving costs.

[0026] (3) The present invention adopts a solvent thermal method to synthesize the catalyst, and the obtained product has uniform phase, high purity, high yield, simple process, low energy consumption and low cost.

[0027] (4) The present invention adopts an induction heating electric furnace to heat the steel autoclave. This method uses the principle of electromagnetic induction to generate eddy currents inside the steel autoclave, achieving rapid and uniform heating, and can accurately control the heating temperature, heating time and heating area. DETAILED DESCRIPTION

[0028] The present invention is described below with specific examples. It is necessary to point out that the examples are only used to further illustrate the present invention, but cannot be understood as limiting the scope of protection of the present invention, and the present invention is not limited thereto in any way. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention.

[0029] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0030] The α-Si3N4 carrier used in the embodiment of the present invention was purchased commercially from Shanghai Yaotian New Material Technology Co., Ltd., product number YT-BY-4-4, average particle size 1 μm, purity 99.9%, α phase, off-white.

[0031] Example 1

[0032] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.5701 g of hydrated acetylacetonate lanthanum (La(C5H7O2)3·XH2O)), measure 20 mL of ethanol and 20 mL of acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 30 min under a magnetic stirrer at a speed of 300 r / min to obtain a suspension;

[0033] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 400° C. for 4 h, and then cooled to room temperature;

[0034] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 4000 rpm for 10 min. The solid is washed twice with ethanol and acetone respectively, and then dried in a vacuum drying oven at a drying temperature of 60° C. for 8 hours. After drying, the Pd-Cu-La / α-Si3N4 supported metal catalyst is obtained.

[0035] The prepared Pd-Cu-La / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1At the initial stage of the reaction, the hydrogen conversion rate was 97.5%, and after 1000 hours of reaction, the hydrogen conversion rate was 94.2%.

[0036] Example 2

[0037] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.5609 g of hydrated acetylacetonate cerium, measure 20 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 20 min under a magnetic stirrer at a speed of 300 r / min to obtain a suspension;

[0038] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 400° C. for 4 h, and then cooled to room temperature;

[0039] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 4000 rpm for 10 min. The solid is washed twice with ethanol and acetone respectively, and then dried in a vacuum drying oven at a drying temperature of 60° C. for 6 hours. After drying, the Pd-Cu-Ce / α-Si3N4 supported metal catalyst is obtained.

[0040] The prepared Pd-Cu-Ce / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 97.7%, and after 1000 hours of reaction, the hydrogen conversion rate was 95.2%.

[0041] Example 3

[0042] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.5307 g of acetylacetonate neodymium, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 30 min under a magnetic stirrer at a speed of 400 r / min to obtain a suspension;

[0043] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 400° C. for 4 h, and then cooled to room temperature;

[0044] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at a speed of 5000 rpm for 10 minutes. The solid is washed twice with ethanol and acetone respectively, and then dried in a vacuum drying oven at a drying temperature of 60° C. for 12 hours. After drying, the Pd-Cu-Nd / α-Si3N4 supported metal catalyst is obtained.

[0045] The prepared Pd-Cu-Nd / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 98.1%, and after 1000 hours of reaction, the hydrogen conversion rate was 95.5%.

[0046] Example 4

[0047] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.5550 g of acetylacetonate praseodymium, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 40 min under a magnetic stirrer at a speed of 400 r / min to obtain a suspension;

[0048] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at a temperature of 500° C. for 5 h, and then cooled to room temperature;

[0049] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 5000 rpm for 15 minutes. The solid is washed with ethanol and acetone for 3 times each, and then dried in a vacuum drying oven at a drying temperature of 70° C. for 8 hours. After drying, the Pd-Cu-Pr / α-Si3N4 supported metal catalyst is obtained.

[0050] The prepared Pd-Cu-Pr / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 98.4%, and after 1000 hours of reaction, the hydrogen conversion rate was 95.7%.

[0051] Example 5

[0052] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.6085 g of acetylacetonate samarium, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 40 min under a magnetic stirrer at a speed of 400 r / min to obtain a suspension;

[0053] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at a temperature of 500° C. for 6 hours, and then cooled to room temperature;

[0054] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 5000 rpm for 20 minutes. The solid is washed with ethanol and acetone for 3 times each, and then dried in a vacuum drying oven at a drying temperature of 70° C. for 6 hours. After drying, the Pd-Cu-Sm / α-Si3N4 supported metal catalyst is obtained.

[0055] The prepared Pd-Cu-Sm / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 99.1%, and after 1000 hours of reaction, the hydrogen conversion rate was 96.5%.

[0056] Example 6

[0057] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.4449 g of acetylacetonate terbium, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 40 min under a magnetic stirrer at a speed of 350 r / min to obtain a suspension;

[0058] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 600° C. for 3 h, and then cooled to room temperature;

[0059] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 5000 rpm for 15 minutes. The solid is washed twice with ethanol and acetone respectively, and then dried in a vacuum drying oven at a drying temperature of 80° C. for 6 hours. After drying, the Pd-Cu-Tb / α-Si3N4 supported metal catalyst is obtained.

[0060] The prepared Pd-Cu-Tb / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 99.5%, and after 1000 hours of reaction, the hydrogen conversion rate was 96.8%.

[0061] Example 7

[0062] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 1.3888 g of hydrated acetylacetonate erbium, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 20 min under a magnetic stirrer at a speed of 400 r / min to obtain a suspension;

[0063] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 600° C. for 5 h, and then cooled to room temperature;

[0064] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 6000 rpm for 10 min. The solid is washed twice with ethanol and acetone respectively, and then dried in a vacuum drying oven at a drying temperature of 80° C. for 8 hours. After drying, the Pd-Cu-Er / α-Si3N4 supported metal catalyst is obtained.

[0065] The prepared Pd-Cu-Er / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 98.1%, and after 1000 hours of reaction, the hydrogen conversion rate was 94.5%.

[0066] Example 8

[0067] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium, 2.0595 g of acetylacetonate copper and 2.4761 g of acetylacetonate yttrium trihydrate, measure 30 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 30 min under a magnetic stirrer at a speed of 400 r / min to obtain a suspension;

[0068] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 400° C. for 6 h, and then cooled to room temperature;

[0069] Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, and the solid is centrifuged at 6000 rpm for 20 minutes. The solid is washed with ethanol and acetone for 3 times each, and then dried in a vacuum drying oven at a drying temperature of 70° C. for 12 hours. After drying, the Pd-Cu-Y / α-Si3N4 supported metal catalyst is obtained.

[0070] The prepared Pd-Cu-Y / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1 At the initial stage of the reaction, the hydrogen conversion rate was 97.6%, and after 1000 hours of reaction, the hydrogen conversion rate was 93.5%.

[0071] Comparative Example 1

[0072] Comparative Example 1 is compared with Example 1 to illustrate that the introduction of rare earth elements as additives can improve the catalyst's resistance to "poisoning" and improve its stability relative to the Pd-Cu / α-Si3N4 catalyst.

[0073] Step 1): weigh 10 g of α-Si3N4 carrier, 0.0086 g of acetylacetonate palladium and 2.0595 g of acetylacetonate copper, measure 20 mL of ethanol and acetone respectively, mix the ethanol and acetone, add the weighed acetylacetonate and α-Si3N4 carrier, and stir well for 30 min under a magnetic stirrer at a speed of 300 r / min to obtain a suspension;

[0074] Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at 400° C. for 4 h, and then cooled to room temperature;

[0075] Step 3): The suspension cooled in step 2) is centrifuged to collect solids, and the solids are centrifuged at 4000 rpm for 10 min. The solids are washed twice with ethanol and acetone, and then dried in a vacuum drying oven at a drying temperature of 60° C. for 8 h. After drying, the Pd-Cu / α-Si3N4 supported metal catalyst is obtained.

[0076] The prepared Pd-Cu / α-Si3N4 supported metal catalyst was applied to low-temperature hydrogen catalytic oxidation reaction, and the catalyst performance was evaluated in a fixed bed reactor. The evaluation conditions were as follows: 0.20 g of the catalyst was mixed with quartz sand to make 1 mL and placed in a quartz tube. The reaction temperature was 25°C, the reaction pressure was atmospheric pressure, the composition of the mixed gas was 2.2% O2, 4.4% H2, 0.05% CO and 0.05 CO2 (carrier gas was nitrogen), the flow rate was 30 mL / min, and the space velocity of hydrogen was 6000 h / min. -1At the initial stage of the reaction, the hydrogen conversion rate was 97.5%, and after 300 hours of reaction, the hydrogen conversion rate was 40.5%.

Claims

1. A method for preparing a Pd-Cu-M / α-Si3N4 supported metal catalyst, characterized in that: The preparation method comprises the following steps: Step 1): dissolving acetylacetonate palladium, acetylacetonate copper and acetylacetonate salt of metal M in a solvent to prepare a precursor solution, adding an α-Si3N4 carrier, and stirring thoroughly to obtain a suspension; the feed ratio of the α-Si3N4 carrier to acetylacetonate palladium, acetylacetonate copper and acetylacetonate salt of metal M is 100: 0.03-0.05: 4-10: 4-10 based on the mass ratio of the α-Si3N4 carrier to the palladium, copper and metal M contained in the three acetylacetonate salts; the metal M is a rare earth metal element; Step 2): The suspension obtained in step 1) is transferred to a steel autoclave lined with polytetrafluoroethylene, sealed and placed in an induction heating furnace for heating at a temperature of 400 to 600° C. for 3 to 6 hours, and then cooled to room temperature; Step 3): The suspension cooled in step 2) is centrifuged to collect the solid, which is then washed and dried to obtain a Pd-Cu-M / α-Si3N4 supported metal catalyst.

2. The preparation method according to claim 1, characterized in that: The metal M described in step 1) is selected from one or more of La, Ce, Nd, Pr, Sm, Tb, Er, and Y.

3. The preparation method according to claim 1, characterized in that: In step 1), the solvent for preparing the precursor solution is one or more of methanol, ethanol, and acetone.

4. The preparation method according to claim 1, characterized in that: In step 1), the solvent for preparing the precursor solution is a mixed solution of ethanol and acetone, wherein the volume ratio of ethanol to acetone is 1:1 to 1:

2.

5. A Pd-Cu-M / α-Si3N4 supported metal catalyst prepared according to the preparation method according to any one of claims 1 to 4.

6. Use of the Pd-Cu-M / α-Si3N4 supported metal catalyst as claimed in claim 5 in low-temperature hydrogen catalytic oxidation reaction.

7. The use according to claim 6, characterized in that: The application is specifically as follows: in a fixed bed reactor, the Pd-Cu-M / α-Si3N4 supported metal catalyst is loaded, raw gas is introduced, the raw gas includes hydrogen and oxygen, the reaction temperature is set at 25-30°C, the reaction pressure is at normal pressure, and hydrogen is oxidized to generate water under the action of the Pd-Cu-M / α-Si3N4 supported metal catalyst.

8. The use according to claim 7, characterized in that: The ratio of the amount of substances in the raw gas is n(O2):n(H2)=1:2, and the hydrogen space velocity is 6000~10000h -1 .