A Pd-Cu-M / α-Si3N4 supported metal catalyst and its preparation and application

Abstract

The application discloses a Pd-Cu-M / alpha-Si3N4 supported metal catalyst and a preparation and application thereof. The preparation method comprises the following steps: step 1): dissolving palladium acetylacetone, copper acetylacetone 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; step 2): transferring the suspension obtained in step 1) into a polytetrafluoroethylene-lined steel autoclave, sealing in an induction heating electric furnace for heating, and cooling to room temperature; step 3): centrifuging the suspension cooled in step 2) to collect the solid, washing and drying the solid, and obtaining the Pd-Cu-M / alpha-Si3N4 supported metal catalyst after the drying is completed. The application provides the application of the catalyst in a low-temperature hydrogen catalytic oxidation reaction, and the catalyst has high hydrogen conversion rate and excellent stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology and application, 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 Technology

[0002] Hydrogen energy, a highly praised environmentally friendly energy source, has a wide range of applications, covering multiple industries including chemicals, new energy, shipbuilding, submarines, and even nuclear energy. However, the properties of hydrogen also present challenges. As a highly flammable and explosive gas, when its concentration reaches 4% or higher, it can easily cause combustion or explosion accidents upon contact with a source of ignition. Therefore, taking effective measures to remove hydrogen in scenarios where it leaks or is a byproduct of production processes is crucial. For example, in nuclear submarines, hydrogen is released as a byproduct during the production of oxygen using water electrolysis technology. If this process is not properly controlled, it may lead to hydrogen leaks. In conventional submarines, batteries, as the main power source, also produce hydrogen during charging and discharging. In these environments where hydrogen is generated, especially in 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, developing and implementing safe and reliable hydrogen removal strategies is particularly critical for ensuring personnel safety and facility integrity. To address this challenge, researchers and engineers are actively exploring various technological approaches, including but not limited to catalytic conversion, adsorption, and chemical reactions, to safely process and eliminate hydrogen. This aims to ensure the effective prevention and control of potential safety hazards in all areas involving hydrogen, thereby promoting the sustainable and safe application of hydrogen energy.

[0003] Currently, the mainstream method for eliminating hydrogen is through the chemical combination of hydrogen and oxygen to produce harmless water. This hydrogen-oxygen combination process is mainly divided into three categories based on different technical approaches: direct combustion, thermal catalysis, and catalytic composite reaction. While direct combustion is rapid, its uncontrollable nature limits its application; thermal catalysis is less efficient due to the need for high temperatures; in contrast, catalytic hydrogen-oxygen composite technology, with the assistance of a catalyst, not only significantly increases the rate of hydrogen-oxygen combination but also effectively lowers the required reaction temperature, demonstrating significant advantages. Catalytic hydrogen oxidation technology, with its high-efficiency catalytic combustion, low environmental impact, and ability to react at temperatures far below those of traditional flame combustion, coupled with its high safety performance, is considered one of the most effective technologies for eliminating hydrogen, especially suitable for locations with extremely high safety requirements, such as nuclear power plants. Existing hydrogen hydroxide catalysts primarily use precious or non-precious metals as active components. However, precious metals are expensive, and non-precious metals require preheating to react. These catalysts still face challenges in practical applications. "Poisons" such as CO, CO2, iodine, and water vapor in the air can compete with reactants for adsorption sites, severely interfering with catalyst activity and even leading to complete deactivation. This has become a major obstacle to the widespread application of this technology. To overcome this challenge, researchers are working to develop novel catalysts to enhance their stability and activity under complex environments. Simultaneously, they are exploring catalyst regeneration and protection technologies to extend catalyst lifespan and ensure the high efficiency and reliability of hydrogen removal technology, thereby further promoting the widespread and safe utilization of hydrogen energy.

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

[0005] To overcome the problems of high cost of precious metal catalysts and the need for preheating at a certain temperature for non-precious metal catalysts to react in the solid-phase hydrogen catalytic oxidation reaction, this 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 reaction. The catalyst prepared by this invention has a high hydrogen conversion rate and excellent stability in the hydrogen catalytic oxidation 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 method for preparing a Pd-Cu-M / α-Si3N4 supported metal catalyst, comprising the following steps:

[0008] Step 1): Dissolve palladium acetylacetonate, copper acetylacetonate, and the acetylacetonate salt of metal M in a solvent to prepare a precursor solution. Add α-Si3N4 support and stir thoroughly to obtain a suspension. The feed ratio of α-Si3N4 support to palladium acetylacetonate, copper acetylacetonate, and the acetylacetonate salt of metal M is 100:0.03-0.05:4-10:4-10, calculated by the mass ratio of palladium, copper, and metal M contained in the three acetylacetonate salts. The metal M is a rare earth metal element.

[0009] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at a temperature of 400-600℃ for 3-6 hours, and then cool it to room temperature.

[0010] Step 3): The solid from the cooled suspension in Step 2) is collected by centrifugation, washed and dried. After drying, a Pd-Cu-M / α-Si3N4 supported metal catalyst is obtained.

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

[0012] Further, 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 and acetone is preferably 1:1 to 1:2.

[0013] Furthermore, the stirring conditions described in step 1) are: a stirring rate of 300-400 r / min and a stirring time of 20-40 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 being washed 2 to 3 times.

[0016] Furthermore, the drying process described in step 3) is carried out in a vacuum drying oven at a temperature of 60–80°C for a time of 6–12 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] Thirdly, the present invention provides the application of the Pd-Cu-M / α-Si3N4 supported metal catalyst described in the second aspect in low-temperature hydrogen catalytic oxidation reaction.

[0019] The specific application is as follows: In a fixed-bed reactor, the Pd-Cu-M / α-Si3N4 supported metal catalyst is loaded, and a feed gas including hydrogen and oxygen is introduced. The reaction temperature is set to 25-30°C and the reaction pressure is atmospheric pressure. Hydrogen is oxidized to water under the action of the Pd-Cu-M / α-Si3N4 supported metal catalyst.

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

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

[0022] The Pd-Cu-M / α-Si3N4 supported metal catalyst prepared by this invention exhibits high catalytic activity in the above-mentioned low-temperature hydrogen catalytic oxidation reaction, with a hydrogen conversion rate of up to 98% or more, and excellent catalyst stability.

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

[0024] (1) The present invention uses commercially available α-Si3N4 as a support to provide the 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 excellent stability.

[0025] (2) The catalyst uses the synergistic effect of Pd and Cu, with rare earth metals as promoters, which greatly reduces the amount of Pd without losing activity and saves costs.

[0026] (3) The present invention uses a solvothermal method to synthesize catalysts, and the resulting products have uniform phases, high purity, high yield, and simple process with low energy consumption and low cost.

[0027] (4) The present invention uses an induction heating electric furnace to heat the steel pressure vessel. This method utilizes the principle of electromagnetic induction to generate eddy currents inside the steel pressure vessel, thereby achieving rapid and uniform heating and enabling precise control of heating temperature, heating time, and heating area. Detailed Implementation

[0028] The present invention will now be illustrated with specific embodiments. It should be noted that these embodiments are merely for further illustrative purposes and should not be construed as limiting the scope of protection of the present invention. The present invention is not limited thereto in any way. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the invention.

[0029] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0030] The α-Si3N4 support used in this embodiment of the invention was commercially purchased from Shanghai Yaotian New Materials Technology Co., Ltd., product code YT-BY-4-4, with an average particle size of 1 μm, purity of 99.9%, α phase, and grayish-white color.

[0031] Example 1

[0032] Step 1): Weigh 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.5701g of lanthanum hydrated acetylacetone (La(C5H7O2)3·XH2O)), measure 20mL each of ethanol and acetone, mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 30min with a magnetic stirrer at 300r / min to obtain a suspension;

[0033] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 400°C for 4 hours, and then cool it to room temperature.

[0034] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 4000 rpm for 10 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 60℃ for 8 h. After drying, a Pd-Cu-La / α-Si3N4 supported metal catalyst was obtained.

[0035] The prepared Pd-Cu-La / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1Initially, 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.5609g of cerium acetylacetone hydrate. Measure 20mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 20min with a magnetic stirrer at 300r / min to obtain a suspension.

[0038] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 400°C for 4 hours, and then cool it to room temperature.

[0039] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 4000 rpm for 10 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 60℃ for 6 h. After drying, a Pd-Cu-Ce / α-Si3N4 supported metal catalyst was obtained.

[0040] The prepared Pd-Cu-Ce / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.5307g of neodymium acetylacetone. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 30min with a magnetic stirrer at 400r / min to obtain a suspension.

[0043] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 400°C for 4 hours, and then cool it to room temperature.

[0044] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 5000 rpm for 10 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 60℃ for 12 h. After drying, a Pd-Cu-Nd / α-Si3N4 supported metal catalyst was obtained.

[0045] The prepared Pd-Cu-Nd / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.5550g of praseodymium acetylacetone. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 40min with a magnetic stirrer at 400r / min to obtain a suspension.

[0048] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 500°C for 5 hours, and then cool it to room temperature.

[0049] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 5000 rpm for 15 min. The solid was washed three times each with ethanol and acetone, and then dried in a vacuum drying oven at 70℃ for 8 h. After drying, a Pd-Cu-Pr / α-Si3N4 supported metal catalyst was obtained.

[0050] The prepared Pd-Cu-Pr / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.6085g of samarium acetylacetone. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 40min with a magnetic stirrer at 400r / min to obtain a suspension.

[0053] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 500°C for 6 hours, and then cool it to room temperature.

[0054] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 5000 rpm for 20 min. The solid was washed three times each with ethanol and acetone, and then dried in a vacuum drying oven at 70℃ for 6 h. After drying, a Pd-Cu-Sm / α-Si3N4 supported metal catalyst was obtained.

[0055] The prepared Pd-Cu-Sm / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.4449g of terbium acetylacetone. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 40min with a magnetic stirrer at 350r / min to obtain a suspension.

[0058] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 600°C for 3 hours, and then cool it to room temperature.

[0059] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 5000 rpm for 15 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 80℃ for 6 h. After drying, a Pd-Cu-Tb / α-Si3N4 supported metal catalyst was obtained.

[0060] The prepared Pd-Cu-Tb / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 1.3888g of erbium acetylacetone hydrate. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 20min with a magnetic stirrer at 400r / min to obtain a suspension.

[0063] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 600°C for 5 hours, and then cool it to room temperature.

[0064] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 6000 rpm for 10 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 80℃ for 8 h. After drying, a Pd-Cu-Er / α-Si3N4 supported metal catalyst was obtained.

[0065] The prepared Pd-Cu-Er / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone, 2.0595g of copper acetylacetone and 2.4761g of yttrium acetylacetone trihydrate. Measure 30mL each of ethanol and acetone. Mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 30min with a magnetic stirrer at 400r / min to obtain a suspension.

[0068] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 400°C for 6 hours, and then cool it to room temperature.

[0069] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 6000 rpm for 20 min. The solid was washed three times each with ethanol and acetone, and then dried in a vacuum drying oven at 70℃ for 12 h. After drying, a Pd-Cu-Y / α-Si3N4 supported metal catalyst was obtained.

[0070] The prepared Pd-Cu-Y / α-Si3N4 supported metal catalyst was applied to a low-temperature hydrogen catalytic oxidation reaction. The catalyst performance was evaluated in a fixed-bed reactor under the following conditions: 0.20 g of the catalyst was mixed with quartz sand and placed in a quartz tube to a volume of 1 mL; the reaction temperature was 25 °C; the reaction pressure was atmospheric pressure; the mixed gas composition was 2.2% O2, 4.4% H2, 0.05% CO, and 0.05% CO2 (nitrogen as the carrier gas); the flow rate was 30 mL / min; and the hydrogen space velocity was 6000 h⁻¹. -1 In 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 demonstrates, by comparing it with Example 1, that the introduction of rare earth elements as promoters can improve the catalyst's resistance to "poisoning" and enhance its stability relative to the Pd-Cu / α-Si3N4 catalyst.

[0073] Step 1): Weigh 10g of α-Si3N4 support, 0.0086g of palladium acetylacetone and 2.0595g of copper acetylacetone, measure 20mL each of ethanol and acetone, mix the ethanol and acetone, add the weighed acetylacetone salt and α-Si3N4 support, and stir thoroughly for 30min with a magnetic stirrer at 300r / min to obtain a suspension;

[0074] Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at 400°C for 4 hours, and then cool it to room temperature.

[0075] Step 3): The cooled suspension from Step 2) was centrifuged to collect the solid. The centrifugation was performed at 4000 rpm for 10 min. The solid was washed twice with ethanol and acetone, and then dried in a vacuum drying oven at 60℃ for 8 h. After drying, a Pd-Cu / α-Si3N4 supported metal catalyst was obtained.

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

Claims

1. The application of a Pd-Cu-M / α-Si3N4 supported metal catalyst in low-temperature hydrogen catalytic oxidation reaction, characterized in that: The preparation method of the Pd-Cu-M / α-Si3N4 supported metal catalyst includes the following steps: Step 1): Dissolve palladium acetylacetonate, copper acetylacetonate, and the acetylacetonate salt of metal M in a solvent to prepare a precursor solution. Add α-Si3N4 support and stir thoroughly to obtain a suspension. The feed ratio of α-Si3N4 support to palladium acetylacetonate, copper acetylacetonate, and the acetylacetonate salt of metal M is 100:0.03-0.05:4-10:4-10, calculated by the mass ratio of palladium, copper, and metal M contained in the three acetylacetonate salts. The metal M is a rare earth metal element. Step 2): Transfer the suspension obtained in Step 1) to a steel autoclave lined with polytetrafluoroethylene, seal it and place it in an induction heating furnace for heating at a temperature of 400-600℃ for 3-6 hours, and then cool it to room temperature. Step 3): The solid from the cooled suspension in Step 2) is collected by centrifugation, washed and dried. After drying, a Pd-Cu-M / α-Si3N4 supported metal catalyst is obtained.

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

3. The application as described in 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 application as described in 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. The application as described in any one of claims 1-4, characterized in that: The specific application is as follows: In a fixed-bed reactor, the Pd-Cu-M / α-Si3N4 supported metal catalyst is loaded, and a feed gas including hydrogen and oxygen is introduced. The reaction temperature is set to 25-30°C and the reaction pressure is atmospheric pressure. Hydrogen is oxidized to water under the action of the Pd-Cu-M / α-Si3N4 supported metal catalyst.

6. The application as described in claim 5, characterized in that: The molar ratio of the raw gas, n(O2):n(H2), is 1:2, and the hydrogen space velocity is 6000–10000 h⁻¹. -1 .