A nitrogen-containing ceria-supported platinum metal catalyst, a preparation method and applications thereof

Abstract

The application discloses a nitrogen-containing cerium dioxide supported platinum metal catalyst and a preparation method and application thereof, and belongs to the technical field of material preparation and catalysis. A carrier cerium dioxide is prepared by using a cerium salt and a nitrogen-doped organic ligand, more defects are provided for the carrier, and dispersion of platinum and diffusion of reactants are facilitated. The rod-shaped nitrogen-doped cerium dioxide is high in strength and good in wear resistance, and is favorable for prolonging the service life of the catalyst; the nitrogen-doped catalyst effectively increases defects of the catalyst and improves catalytic activity. The pretreatment process of an antioxidant can improve oxygen vacancies of the nitrogen-doped cerium dioxide and improve the high efficiency of platinum anchoring to the oxygen vacancies, and has a significant promoting effect on catalytic activity. The active metal platinum is deposited to the carrier active center in a manner of impregnation and photoreduction, and the performance and stability of the catalyst in catalyzing methanol water reforming to produce hydrogen under low-temperature conditions are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation and catalysis technology, specifically relating to a nitrogen-containing cerium dioxide-supported platinum metal catalyst, its preparation method, and its application. Background Technology

[0002] With the increasing severity of environmental pollution caused by the combustion of fossil fuels, the development and utilization of new clean energy sources has become extremely urgent and important. Safety issues during hydrogen storage and transportation are one of the main technological barriers to hydrogen energy utilization. Liquid methanol, with its high C-H ratio and low reforming reaction temperature (200-400℃), has attracted increasing attention in recent years. Liquid methanol can avoid the safety problems encountered during hydrogen storage and transportation. Compared with gaseous hydrogen storage, in-situ hydrogen production from liquid methanol not only eliminates the safety risks of high-pressure hydrogen storage but also reduces transportation costs. Notably, methanol steam reforming, as a cost-effective method, provides high-yield hydrogen production under relatively mild reaction conditions, attracting attention in the field of thermocatalysis technology.

[0003] In the field of thermocatalysis, catalyst activity has always been a challenging problem. There are two sintering methods for catalysts in thermocatalysis: one is sintering via Ostwald ripening, and the other is sintering via particle aggregation and migration. Both sintering methods reduce or even deactivate the catalyst's catalytic activity. In actual production, reduced or deactivated catalyst activity can significantly impact the production process. Therefore, improving the high activity of catalysts at low temperatures has become a critical technical challenge and a hot research topic. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the present invention aims to provide a nitrogen-containing cerium dioxide supported platinum metal catalyst, its preparation method and application, which is low in cost, simple to operate, mild in reaction conditions, safe and pollution-free; it can significantly enhance the catalyst's anti-sintering performance, significantly extend the catalyst's service life, and greatly reduce the catalyst's usage cost.

[0005] This invention is achieved through the following technical solution:

[0006] This invention discloses a method for preparing a nitrogen-containing cerium dioxide-supported platinum metal catalyst, comprising the following steps:

[0007] Step 1: Dissolve cerium salt and nitrogen-doped organic ligand in deionized water under alkaline conditions, heat and stir until completely dissolved, and then carry out a hydrothermal reaction. The solid product obtained is separated, washed, and dried to obtain nitrogen-doped cerium dioxide powder.

[0008] Step 2: Add the nitrogen-doped cerium dioxide powder obtained in Step 1 and the antioxidant to deionized water, stir at room temperature, separate the solid product, wash and dry it to obtain the pretreated carrier nitrogen-doped cerium dioxide powder.

[0009] Step 3: Add the pretreated carrier nitrogen-doped cerium dioxide powder obtained in Step 2 and platinum salt to deionized water, stir at room temperature, and separate the solid product. After washing and drying, nitrogen-doped cerium dioxide supported platinum powder is obtained.

[0010] Step 4: The nitrogen-doped cerium dioxide-supported platinum powder obtained in Step 4 is calcined under an inert atmosphere to obtain a nitrogen-containing cerium dioxide-supported platinum metal catalyst.

[0011] Preferably, in step 1, the molar fraction of nitrogen doping in the obtained nitrogen-doped cerium dioxide powder is 0.6-1.

[0012] Preferably, in step 1, the alkaline condition is pH = 9-11, and the heating and stirring are carried out at 80°C for 1 hour; the hydrothermal reaction temperature is 120-200°C, and the time is 3-36 hours.

[0013] Preferably, in step 2, the stirring time is 3-4 hours, during which the system changes from light yellow to reddish-brown.

[0014] Preferably, in step 3, the stirring time is not less than 6 hours.

[0015] Preferably, in step 4, the inert atmosphere is nitrogen, the calcination temperature is 300-400℃, and the time is 4-6h.

[0016] The present invention also discloses a nitrogen-containing cerium dioxide-supported platinum metal catalyst prepared by the above preparation method.

[0017] Preferably, the cerium dioxide support is a rod-shaped structure with a length of 64-67 nm and a diameter of 6-7 nm; the particle size of the platinum metal is 5-10 nm; and the mass fraction of active metal platinum atoms in the nitrogen-containing cerium dioxide-supported platinum metal catalyst is 1-1.5%.

[0018] The present invention also discloses the application of the above-mentioned nitrogen-containing cerium dioxide supported platinum metal catalyst as a catalyst in the methanol reforming hydrogen production reaction.

[0019] Preferably, the nitrogen-containing cerium dioxide-supported platinum metal catalyst is tableted, milled, and sieved to obtain 30-60 mesh particles; at a space velocity of 25.929 mL·gcat... -1 ·h -1 The hydrogen production rate at 180℃ is 16,730 μmol·gcat. -1 ·h -1When the reaction is carried out continuously at 180℃ for 40 hours, the hydrogen production rate decreases to 1-10%.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The present invention discloses a method for preparing a nitrogen-containing cerium dioxide-supported platinum metal catalyst. The method utilizes cerium salts and nitrogen-doped organic ligands to prepare the cerium dioxide support, providing more defects to the support, which is beneficial for platinum dispersion and reactant diffusion. Rod-shaped nitrogen-doped cerium dioxide exhibits high strength and good wear resistance, which helps extend catalyst life. The nitrogen-doped catalyst effectively increases catalyst defects and improves catalytic activity. An antioxidant pretreatment process enhances the oxygen vacancies in the nitrogen-doped cerium dioxide, improving the efficiency of platinum anchoring oxygen vacancies and significantly promoting catalytic activity. Active platinum metal is deposited onto the active center of the support via impregnation and photoreduction, resulting in significantly improved catalytic performance and stability in methanol-water reforming for hydrogen production under low-temperature conditions.

[0022] Furthermore, the molar fraction of nitrogen doping in the obtained nitrogen-doped cerium dioxide powder is 0.6-1. Excessive nitrogen doping will lead to oxygen vacancy blockage, a decrease in the number of active metal platinum anchored by oxygen vacancy, and a decrease in catalytic activity. Insufficient doping will lead to carrier defects and insufficient oxygen vacancy, which will also lead to a decrease in catalytic activity.

[0023] Furthermore, the hydrothermal reaction time ranges from 3 to 36 hours. A time less than 3 hours results in a weak rod-shaped support that fails to meet the requirements; a time exceeding 36 hours leads to an excessively large rod-shaped support, reducing the number of defect sites. The hydrothermal reaction temperature is 120-200℃. Temperatures above 200℃ result in a cubic shape with fewer oxygen vacancies; temperatures below 120℃ result in a polyhedral shape with fewer oxygen vacancies. Simultaneously, combined with alkaline conditions (pH 9-11), the support collectively forms a rod-shaped morphology with sufficient oxygen vacancies and defects.

[0024] Furthermore, in step 2, the stirring time is 3-4 hours. During the stirring process, the system changes from light yellow to reddish brown, which allows more oxygen vacancies to be exposed on the rod-shaped nitrogen-doped cerium dioxide support.

[0025] The nitrogen-containing cerium dioxide-supported platinum metal catalyst disclosed in this invention, prepared using the above-described method, has a platinum metal particle size of 5-10 nm, which allows for stable embedding within the rod-shaped nitrogen-doped cerium dioxide support. If the platinum particles are too large, the support will lack sufficient strength and be prone to breakage; if they are too small, the platinum will be completely coated, failing to effectively exhibit catalytic performance. The mass fraction of active platinum atoms in the nitrogen-containing cerium dioxide-supported platinum metal catalyst is 1-1.5%. An excessively high mass fraction leads to clustering; an excessively low mass fraction does not significantly improve catalytic activity.

[0026] When the nitrogen-containing cerium dioxide-supported platinum metal catalyst prepared by this invention is used as a catalyst in the methanol reforming hydrogen production reaction, the strong and weak support effects of the metal support catalyst can effectively suppress the sintering process of the catalyst, thereby greatly enhancing the anti-sintering performance of the catalyst, significantly extending the service life of the catalyst, and greatly reducing the cost of using the catalyst. Attached Figure Description

[0027] Figure 1 This is a transmission electron microscope (TEM) image of the rod-shaped nitrogen-doped cerium dioxide support prepared in Example 1.

[0028] Figure 2 The image shows the X-ray powder diffraction (XRD) pattern of the rod-shaped nitrogen-doped cerium dioxide support prepared in Example 1.

[0029] Figure 3 This is a transmission electron microscope (TEM) image of the nitrogen-containing cerium dioxide-supported platinum metal catalyst prepared in Example 1.

[0030] Figure 4 This is an X-ray powder diffraction (XRD) image of the nitrogen-containing cerium dioxide-supported platinum metal catalyst of the present invention.

[0031] Figure 5 This is a scanning electron microscope (SEM-EDS) elemental analysis diagram of the nitrogen-containing cerium dioxide-supported platinum metal catalyst of the present invention.

[0032] Figure 6 The figure shows the performance test results of the nitrogen-containing cerium dioxide-supported platinum metal catalyst of the present invention for the methanol steam reforming hydrogen production reaction. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These descriptions are intended to explain the invention and not to limit it.

[0034] Example 1

[0035] 1) Add 2.605g of cerium nitrate hexahydrate and 0.72mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 120℃. After 36h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0036] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 3 h, and obtain the pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0037] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 6 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0038] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined under a nitrogen atmosphere at 300℃ for 6 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0039] Example 2

[0040] 1) Add 2.605g of cerium sulfate and 0.72mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L of sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 200℃. After 3h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0041] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0042] 3) Add 0.35 g of the pretreated nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 12 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0043] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 450°C for 4 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0044] Example 3

[0045] 1) Add 2.605 g of cerium trichloride and 0.72 mL of ethylenediamine to 60 mL of deionized water and stir at 80 °C for 1 h. Add 1 mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 200 °C. After 24 h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0046] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0047] 3) Add 0.35 g of the pretreated nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 18 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0048] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 350°C for 5 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0049] Example 4

[0050] 1) Add 2.605g of cerium perchlorate hexahydrate and 0.72mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 140℃. After 24h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0051] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0052] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 10 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0053] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 400℃ for 5 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0054] Example 5

[0055] 1) Add 2.605g of cerium nitrate and 0.72mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent matter is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 200℃. After 3h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0056] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0057] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 10 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0058] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at 300℃ for 6 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0059] Example 6

[0060] 1) Add 2.605 g of cerium nitrate hexahydrate and 0.72 mL of formamide to 60 mL of deionized water and stir at 80 °C for 1 h. Add 1 mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 200 °C. After 10 h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0061] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0062] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 24 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0063] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 400℃ for 6 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0064] Example 7

[0065] 1) Add 2.605g of cerium nitrate hexahydrate and 0.72mL of formamide to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 150℃. After 36h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0066] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0067] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 8 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0068] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 320°C for 5 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0069] Example 8

[0070] 1) Add 2.605 g of cerium nitrate hexahydrate and 0.72 mL of formamide to 60 mL of deionized water and stir at 80 °C for 1 h. Add 1 mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 100 °C. After 36 h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0071] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 3 h, and obtain the pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0072] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 36 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0073] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 380℃ for 6 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0074] Example 9

[0075] 1) Add 2.605g of cerium nitrate hexahydrate and 0.72mL of formamide to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 180℃. After 24h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0076] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0077] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 24 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0078] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 380℃ for 6 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0079] Example 10

[0080] 1) Add 2.605 g of cerium nitrate hexahydrate and 0.72 mL of formamide to 60 mL of deionized water and stir at 80 °C for 1 h. Add 1 mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 130 °C. After 36 h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0081] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0082] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 36 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0083] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at 320°C for 5.5 hours. The calcined powder is then pressed, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-2.

[0084] Comparative Example 1

[0085] 1) Add 2.605g of cerium nitrate hexahydrate to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 120℃. After 24h, a mixed solution is obtained. After filtration and drying, cerium dioxide powder is obtained.

[0086] 2) Add 0.5g of cerium dioxide powder and 0.198g of sodium D-isoascorbate obtained in step 1) to 200mL of deionized water, stir at 25℃ for 4h, and obtain pretreated carrier cerium dioxide powder by centrifugation and freeze drying.

[0087] 3) Add 0.35 g of the pretreated cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 20 h, and obtain cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0088] 4) The cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 300°C for 4 hours. Then, the calcined powder is pressed into tablets, ground, and sieved to obtain 30-60 mesh particles, thus obtaining the cerium dioxide-supported platinum catalyst, denoted as Pt / CeO2.

[0089] Comparative Example 2

[0090] 1) Add 2.605g of cerium nitrate hexahydrate and 0.36mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 120℃. After 20h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0091] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0092] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 36 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0093] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 300℃ for 4 hours. Then, the calcined powder is pressed into tablets, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-1.

[0094] Comparative Example 3

[0095] 1) Add 2.605g of cerium nitrate hexahydrate and 1.08mL of ethylenediamine to 60mL of deionized water and stir at 80℃ for 1h. Add 1mol / L sodium hydroxide to the above reaction solution until a large amount of white flocculent material is generated. Transfer the resulting mixed solution to a hydrothermal reactor and carry out hydrothermal reaction at 170℃. After 18h, a mixed solution is obtained. After filtration and drying, nitrogen-doped cerium dioxide powder is obtained.

[0096] 2) Add 0.5 g of nitrogen-doped cerium dioxide powder and 0.198 g of sodium D-isoascorbate obtained in step 1) to 200 mL of deionized water, stir at 25 °C for 4 h, and obtain pretreated carrier nitrogen-doped cerium dioxide powder by centrifugation and freeze drying.

[0097] 3) Add 0.35 g of the pretreated carrier nitrogen-doped cerium dioxide powder obtained in step 2) and 2000 μL of chloroplatinic acid hexahydrate with a concentration of 5 mg / mL to 100 mL of deionized water, stir at 25 °C for 8 h, and obtain nitrogen-doped cerium dioxide-supported platinum powder by centrifugation and freeze drying.

[0098] 4) The nitrogen-doped cerium dioxide-supported platinum powder obtained in step 3) is placed in a muffle furnace and calcined in air at a temperature of 360°C for 4.5 hours. The calcined powder is then pressed, milled, and sieved to obtain 30-60 mesh particles, thus obtaining the nitrogen-doped cerium dioxide-supported platinum catalyst, denoted as Pt / N-CeO2-3.

[0099] Product performance evaluation experiment

[0100] Figure 1 This is a transmission electron microscope (TEM) image of the rod-shaped nitrogen-doped cerium dioxide support prepared in Example 1. As can be seen from the image, the rod-shaped cerium dioxide is uniformly distributed, a shape that facilitates its maximum participation in the catalytic reaction.

[0101] Figure 2 The image shows the X-ray powder diffraction (XRD) pattern of the rod-shaped nitrogen-doped cerium dioxide support prepared in Example 1. As can be seen from the image, the nitrogen-doped N-CeO₂⁻ catalyst still exhibits the characteristic diffraction peaks of cerium dioxide.

[0102] Figure 3 This is a transmission electron microscope (TEM) image of the nitrogen-containing cerium dioxide-supported platinum metal catalyst prepared in Example 1. As can be seen from the image, the rod-shaped nitrogen-containing cerium dioxide-supported platinum metal is uniformly distributed, a shape that facilitates greater participation in the catalytic reaction.

[0103] Figure 4This is an X-ray powder diffraction (XRD) pattern of the nitrogen-containing cerium dioxide-supported platinum metal catalyst of the present invention. As can be seen from the figure, the platinum metal supported on the nitrogen-containing cerium dioxide carrier still exhibits the characteristic diffraction peaks of cerium dioxide.

[0104] Figure 5 This is a scanning electron microscope (SEM-EDS) elemental analysis diagram of the nitrogen-containing cerium dioxide-supported platinum metal catalyst of the present invention. As can be seen from the figure, after the nitrogen-containing cerium dioxide support is added, the platinum metal is uniformly distributed with both platinum and nitrogen elements.

[0105] The performance evaluation of the products in the above examples and comparative examples was conducted using a laboratory-built atmospheric pressure fixed-bed reactor. The catalyst was packed in a quartz tube with an inner diameter of 8 mm, at a loading rate of 0.2 g. The entire reaction was carried out at an Ar concentration of 100 mL / min. A mixture of methanol and water was introduced into the vaporizer via a micro-injection pump at a flow rate of 0.1 mL / min, with a water-to-methanol ratio of 1.2. After complete vaporization at 180°C, the mixture entered the reactor for further reaction. The reaction products were then analyzed online by a gas chromatograph via a gas pipeline, and the contents of H2, CO, and CO2 in the reformed gas were measured using a thermal conductivity detector (TCD).

[0106] from Figure 6 Pt / N-CeO2-2 showed the best activity in the methanol reforming hydrogen production reaction, with a hydrogen production rate of 16,730 μmol·gcat at 180 °C. -1 ·h -1 Compared to Pt / CeO2, the performance was improved by 77%. However, it exhibited the lowest CO selectivity among all reforming gases. This demonstrates that the appropriate addition of nitrogen improves the low-temperature activity of Pt / N-CeO2-2, and given its low noble metal loading, it shows potential for future applications.

[0107] It should be noted that the above description is only a part of the embodiments of the present invention, and all equivalent changes made to the system described in this invention are included within the protection scope of this invention. Those skilled in the art can make similar substitutions to the specific examples described, as long as they do not deviate from the structure of the invention or exceed the scope defined in these claims, all of which fall within the protection scope of this invention.

Claims

1. The application of a nitrogen-containing cerium dioxide-supported platinum metal catalyst in the methanol reforming hydrogen production reaction, characterized in that, The method for preparing the catalyst includes the following steps: Step 1: Dissolve cerium salt and ethylenediamine or formamide in deionized water under alkaline conditions, heat and stir until completely dissolved, and then carry out a hydrothermal reaction. The solid product obtained is separated, washed, and dried to obtain nitrogen-doped cerium dioxide powder. Step 2: Add the nitrogen-doped cerium dioxide powder obtained in Step 1 and the antioxidant to deionized water, stir at room temperature, separate the solid product, wash and dry it to obtain the pretreated carrier nitrogen-doped cerium dioxide powder; the antioxidant is sodium D-isoascorbate. Step 3: Add the pretreated carrier nitrogen-doped cerium dioxide powder obtained in Step 2 and platinum salt to deionized water, stir at room temperature, and separate the solid product. After washing and drying, nitrogen-doped cerium dioxide supported platinum powder is obtained. Step 4: Calcining the nitrogen-doped cerium dioxide-supported platinum powder obtained in Step 3 under an inert atmosphere to obtain a nitrogen-containing cerium dioxide-supported platinum metal catalyst.

2. The application according to claim 1, characterized in that, In step 1, the alkaline conditions are pH=9-11, and the heating and stirring are carried out at 80℃ for 1 hour; the hydrothermal reaction temperature is 120-200℃, and the time is 3-36 hours.

3. The application according to claim 1, characterized in that, In step 2, the stirring time is 3-4 hours, during which the system changes from light yellow to reddish brown.

4. The application according to claim 1, characterized in that, In step 3, the stirring time shall not be less than 6 hours.

5. The application according to claim 1, characterized in that, In step 4, the inert atmosphere is nitrogen, the calcination temperature is 300-400℃, and the time is 4-6h.

6. The application according to claim 1, characterized in that, The mass fraction of active metal platinum atoms in the nitrogen-containing cerium dioxide-supported platinum metal catalyst is 1-1.5%.

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