A preparation method of a palladium-nickel composite catalyst

Abstract

The application discloses a preparation method of a palladium-nickel composite catalyst, and the preparation process comprises the following steps: putting 15 mL of a glucose solution with a concentration of 0.1-2.1 mol / L, 0.1-1.1 mL of an ionic liquid and 0.05-0.25 g of Ni2O3 into a high-pressure reaction kettle, and then hydrothermally treating the mixture at 140-200 DEG C for 4-14 h; after that, the obtained sample is washed, dried and calcined at 200-500 DEG C under air to obtain a precursor; 15 mg of the obtained precursor and 15 mg of PdO·H2O are put into a 5 mL centrifuge tube, distilled water is added, and ultrasonic treatment is carried out for 50-90 min to obtain a uniformly dispersed suspension; the suspension is heated in the high-pressure reaction kettle at 120-220 DEG C for 1-5 h, then filtration is carried out, and the obtained solid substance is dried at 60-90 DEG C to obtain the palladium-nickel composite catalyst. The prepared palladium-nickel composite catalyst is used for modifying a glassy carbon electrode, and performance test shows that the catalyst has excellent catalytic performance on ethanol electro-oxidation and has potential commercial application value.

Description

Technical Field

[0001] The invention relates to a preparation method of a palladium-nickel composite catalyst, belonging to the technical field of energy materials. Background Art

[0002] Direct ethanol fuel cells (DECs) are considered one of the most promising fuel cells due to their high energy density and environmental friendliness. Recent studies have shown that, in addition to platinum-based catalysts, palladium-based catalysts also exhibit excellent catalytic performance for the electrooxidation of ethanol in alkaline media. Furthermore, research indicates that the reserves of palladium in the Earth's crust are significantly greater than those of platinum. Therefore, the development of Pd-based catalysts has important theoretical and practical implications for reducing the production costs of ethanol fuel cells. To further reduce production costs while maintaining good catalytic performance, the development of Pd-based binary and ternary catalysts has become a key research topic in the field of ethanol fuel cell catalysts. Among Pd-based binary catalysts, Pd-nickel catalysts are considered one of the most promising due to their safety, environmental friendliness, and excellent performance. Currently, methods for preparing Pd-nickel catalysts have been reported. For example, Patent Publication No. CN115532292A reports on "Preparation and Application of a Nitrogen-Doped Carbon-Supported Single-Atom Palladium Catalyst," which uses glucose, dicyandiamide, and ammonium tetrachloropalladate as reactants. Patent Publication No. CN115445651A reports on "Pure Silicon Molecular Sieve-Supported Palladium Catalyst for Methane Catalytic Combustion and Preparation Method," in which the metal palladium nanoparticles have a particle size of 2 to 5 nm, and the silicon molecular sieve material contains only silicon and oxygen. Patent Publication No. CN115193459A reports on "Preparation Method and Application of a Heterogeneous Palladium Catalyst," in which the palladium catalyst is prepared by mixing and dissolving a palladium salt, a calcium salt, a phosphate ion source, an alkaline solution, and water. Patent Publication No. CN115141116A discloses "A Macromolecular Diimine Nickel Palladium Catalyst and Its Application," in which the catalyst prepared contains a polymer chain and a diimine nickel palladium structure. These methods generally suffer from shortcomings such as the introduction of impurities, complex procedures, and high preparation costs. Therefore, the research and development of preparation methods for palladium-based catalysts remains one of the hot issues in the current research direction of palladium-based catalysts. Summary of the Invention

[0003] The present invention provides a method for preparing a palladium-nickel composite catalyst. The present invention utilizes a two-step process to prepare the carbon-supported palladium-nickel composite catalyst. The first step involves preparing the carbon-nickel composite material by adding an ionic liquid to a conventional aqueous solution to obtain a reaction medium. This is followed by hydrothermal calcination with air to produce the carbon-nickel composite material. Subsequently, in the second step, a hydrothermal method is again employed to prepare the carbon-supported palladium-nickel binary catalyst.

[0004] The present invention first uses glucose, nickel trioxide, and an ionic liquid as reactants, using a hydrothermal method with air calcination to prepare a precursor containing carbon and NiO. Then, using the resulting precursor and palladium oxide monohydrate (PdO·H2O) as reactants, a carbon-supported palladium-nickel composite catalyst is prepared again using a hydrothermal method.

[0005] The catalyst prepared in this patented process is free of impurities; that is, only carbon, oxygen, palladium, and nickel participate in the reaction. The resulting catalyst exhibits high catalytic activity and excellent durability for ethanol electrooxidation. Literature research suggests that the preparation of palladium-nickel composite catalysts using the method of this invention has not been reported.

[0006] Specifically, the preparation method provided by the present invention comprises the following steps:

[0007] (1) Raw material preparation

[0008] glucose;

[0009] Nickel trioxide;

[0010] Palladium oxide monohydrate (PdO·H2O);

[0011] Ionic liquid: one of 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]OTf) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6);

[0012] (2) Preparation of carbon nickel support

[0013] 15 mL of 0.1-2.1 mol / L glucose solution, 0.1-1.1 mL of ionic liquid, and 0.05-0.25 g of Ni2O3 black solid powder were placed in a high-pressure reactor and heated at 140-200°C.

[0014] Hydroheat for 4-14 h, then cool to room temperature;

[0015] Among them, the optimal concentration of glucose solution is 0.5 mol / L; the optimal temperature of hydrothermal treatment is 180°C; the optimal time of hydrothermal treatment is 10h;

[0016] (3) Filtering the product obtained in step (2) to obtain a solid, washing the solid three times with distilled water, and then drying the solid at 140-170°C for 4-9 hours. The obtained sample is calcined in an air atmosphere at 200-500°C for 2-5 hours to obtain a carbon nickel support, which is referred to as a precursor;

[0017] The solid obtained by filtering the product obtained in step (2) is preferably dried at 160°C for 8 hours; the optimal conditions are a sample calcination temperature of 450°C and a calcination time of 3 hours;

[0018] (4) Preparation of palladium nickel catalyst

[0019] Take 15 mg of the precursor obtained in step (3) and 15 mg of PdO·H2O and place them in a 5 mL centrifuge tube. Add 3.5 mL of distilled water and ultrasonicate for 50-90 min to obtain a uniformly dispersed suspension.

[0020] Among them, the ultrasonic treatment time of 70 min was the optimal;

[0021] (5) The suspension obtained in step (4) is heated in a high-pressure reactor at 120-220°C for 1-5 h, and then filtered. The solid matter obtained by filtration is dried at 60-90°C for 1-8 h to obtain a palladium-nickel composite catalyst.

[0022] Among them, the preferred reaction temperature and heating time are 200°C and 3 h respectively; the preferred drying temperature is 90°C, and the preferred drying time is 6 h.

[0023] Preparation and catalytic performance testing of palladium-nickel composite catalyst modified glassy carbon electrode.

[0024] 1.5 mg of the palladium-nickel composite catalyst was transferred to 0.5 mL of an ethanol solution containing Nafion (Nafion content of approximately 0.1 wt.%). After 70 minutes of ultrasonication, a black suspension was obtained. Subsequently, 16 μL of the above suspension was drop-coated on a glassy carbon electrode and naturally dried in air for 20 minutes to obtain a glassy carbon electrode modified with the palladium-nickel composite catalyst. This electrode was then used as the working electrode, and a platinum disk electrode and a saturated calomel electrode were used as the auxiliary electrode and reference electrode, respectively, to form a three-electrode system for electrochemical performance testing on an electrochemical workstation. Cyclic voltammetry (CV) test results showed that the prepared catalyst had good catalytic activity for the electrooxidation of ethanol. Chronoamperometry (CA) test results showed that the current density of ethanol on the electrode was still 2.03 mA / cm after 7200 s. 2 , showing excellent catalytic durability.

[0025] The present invention achieves the following beneficial effects: Using nickel trioxide and palladium oxide monohydrate as nickel and palladium sources, respectively, without introducing other impurities, and using a glucose solution containing an ionic liquid as the reaction medium, a two-step process is used to prepare a palladium-nickel composite catalyst with high catalytic activity for ethanol electrooxidation. The present invention has the advantages of a simple preparation method, low cost, and significant catalytic effect. The catalyst prepared by the present invention has potential commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the XRD pattern of the prepared catalyst.

[0027] Figure 2 is the EDS pattern of the prepared catalyst.

[0028] Figure 3 SEM image of the prepared catalyst at 100 nm scale.

[0029] Figure 4 This is the cyclic voltammogram of ethanol on the palladium-nickel composite catalyst modified glassy carbon electrode.

[0030] Figure 5 This is the chronoamperometry of ethanol on the palladium-nickel composite catalyst modified glassy carbon electrode. DETAILED DESCRIPTION

[0031] The following examples illustrate the present invention.

[0032] Example 1

[0033] 15 mL of a 0.5 mol / L glucose solution, 0.3 mL of [BMIM]OTf, and 0.08 g of black NiO powder were placed in an autoclave and hydrothermally heated at 180°C for 10 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the solid sample was calcined at 450°C in air for 2 h to obtain the carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 200°C for 2 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. Subsequently, 1.5 mg of the palladium-nickel composite catalyst was transferred to 0.5 mL of an ethanol solution containing Nafion (the mass content of Nafion was approximately 0.1 wt.%), and a black suspension was obtained after ultrasonic treatment for 70 minutes. Then, 16 μL of the above suspension was drop-coated on a glassy carbon electrode. After natural drying in air for 20 minutes, a glassy carbon electrode modified with a palladium-nickel composite catalyst was obtained. This electrode was then used as the working electrode, and a platinum disk electrode and a saturated calomel electrode were used as auxiliary electrodes and reference electrodes, respectively, to form a three-electrode system for electrochemical performance testing. The CV test results showed that the prepared catalyst had good catalytic activity for the electrooxidation of ethanol. The CA test results showed that the current density of ethanol on the electrode was still 2.03 mA / cm after 7200 s. 2, showing excellent catalytic durability.

[0034] Figure 1 The XRD pattern of the prepared catalyst is shown in Figure 4. It can be seen that its spectrum completely overlaps with the standard XRD pattern of elemental palladium (card number: 46-1043), which indicates that the prepared catalyst contains palladium and the palladium mainly exists in the form of elemental palladium.

[0035] Figure 2 The EDS spectrum of the catalyst shows characteristic peaks corresponding to C, O, Ni, and Pd, with the peaks of carbon and palladium showing high intensities. This indicates that the prepared catalyst contains high amounts of elemental palladium and carbon, indicating that the catalyst is a carbon-supported palladium-nickel composite material.

[0036] Figure 3 This is a SEM image of the prepared catalyst surface. The material's surface is characterized by numerous micropores, with numerous irregular white particles embedded within or growing on the surface. Preliminary measurements indicate that the particle size ranges from 10 nm to 100 nm, making it a nanomaterial. This porous and loose surface structure increases surface area, reduces polarization, and facilitates the flow of electrolyte solution and ethanol molecules.

[0037] Figure 4 Figure 2 shows the CV curves of the prepared catalyst. The dashed line shows the CV curve of the catalyst in 1 M KOH solution (1 M = 1 mol / L in electrochemical studies). The solid line shows the CV curve of the catalyst in 1 M KOH + 1 M CH₃CH₂OH solution. It can be seen that two distinct oxidation peaks appear in the CH₃CH₂OH-containing KOH solution, indicating that this catalyst has good catalytic performance for the electrooxidation of ethanol.

[0038] Figure 5 The chronoamperometry of the prepared catalyst in 1 M KOH + 1 M CH3CH2OH solution at an electrode potential of -0.35 V is shown. It can be seen that the current density of ethanol electrooxidation can still be measured at 2.01 mA / cm after 7200 s. 2 This indicates that the prepared catalyst has good catalytic durability and can be used in commercial ethanol fuel cells.

[0039] Example 2

[0040] 15 mL of a 1.0 mol / L glucose solution, 0.3 mL of [BMIM]PF6, and 0.10 g of black Ni2O3 solid powder were placed in an autoclave and hydrothermally heated at 180°C for 10 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the resulting sample was calcined at 400°C in air for 2 h to obtain a carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 190°C for 2 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. A three-electrode system was then assembled as in Example 1, and electrochemical performance was tested. The CV test results show that the prepared catalyst has good catalytic performance for the electrooxidation of ethanol. The CA test results show that the current density of ethanol electrooxidation is still 2.3 mA / cm after 7200 s. 2 , showing excellent catalytic durability.

[0041] Example 3

[0042] 15 mL of a 1.5 mol / L glucose solution, 0.5 mL of [BMIM]PF6, and 0.12 g of black Ni2O3 solid powder were placed in an autoclave and hydrothermally heated at 170°C for 8 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the resulting sample was calcined at 400°C in air for 2 h to obtain a carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 200°C for 2 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. A three-electrode system was then assembled as in Example 1, and electrochemical performance was tested. The CV test results show that the prepared catalyst has good catalytic performance for the electrooxidation of ethanol. The CA test results show that the current density of ethanol electrooxidation is still 2.5 mA / cm after 7200 s. 2 , showing excellent catalytic durability.

[0043] Example 4

[0044] 15 mL of a 1.8 mol / L glucose solution, 0.6 mL of [BMIM]PF6, and 0.2 g of black Ni2O3 powder were placed in an autoclave and hydrothermally heated at 150°C for 9 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the resulting sample was calcined at 480°C in air for 2 h to obtain a carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 180°C for 3 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. A three-electrode system was then assembled as in Example 1, and electrochemical performance was tested. CV tests showed that the prepared catalyst had good catalytic performance for the electrooxidation of ethanol. CA test results showed that the current density of ethanol electrooxidation was still 2.1 mA / cm after 7200 s. 2 , showing excellent catalytic durability.

[0045] Example 5

[0046] 15 mL of a 1.5 mol / L glucose solution, 0.4 mL of [BMIM]PF6, and 0.20 g of black Ni2O3 solid powder were placed in an autoclave and hydrothermally heated at 170°C for 7 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the resulting sample was calcined at 400°C in air for 2 h to obtain a carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 180°C for 4 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. A three-electrode system was then assembled as in Example 1, and electrochemical performance was tested. The CV test results show that the prepared catalyst has good catalytic performance for the electrooxidation of ethanol. The CA test results show that the current density of ethanol electrooxidation is still 2.2 mA / cm after 7200 s. 2 , showing excellent catalytic durability.

[0047] Example 6

[0048] 15 mL of a 1.2 mol / L glucose solution, 0.9 mL of [BMIM]PF6, and 0.15 g of black Ni2O3 powder were placed in an autoclave and hydrothermally heated at 150°C for 10 h. The mixture was then cooled to room temperature and filtered to obtain a solid. The solid was then washed three times with distilled water and dried at 70°C for 8 h. Finally, the resulting sample was calcined at 380°C in air for 2 h to obtain a carbon-nickel support, referred to as the precursor. Subsequently, 15 mg of the precursor and 15 mg of PdO·H2O were weighed and placed in a 5 mL centrifuge tube. 3.5 mL of distilled water was added, and the mixture was ultrasonically treated for 70 min. The mixture was then heated in an autoclave at 170°C for 3 h. The filtered solid was then dried at 70°C for 6 h to obtain the final palladium-nickel composite catalyst. A three-electrode system was then assembled as in Example 1, and electrochemical performance was tested. The CV test results show that the prepared catalyst has good catalytic performance for the electrooxidation of ethanol. The CA test results show that the current density of ethanol electrooxidation is still 2.2 mA / cm at 7200 s. 2 , showing excellent catalytic durability.

Claims

1. A method for preparing a palladium-nickel composite catalyst, characterized in that The steps include: (1) Raw material preparation glucose; Nickel trioxide; Palladium oxide monohydrate (PdO·H2O); Ionic liquid: one of 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]OTf) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6); (2) Preparation of carbon nickel support 15 mL of 0.1-2.1 mol / L glucose solution, 0.1-1.1 mL of ionic liquid, and 0.05-0.25 g of Ni2O3 black solid powder were placed in a high-pressure reactor and heated at 140-200°C. Hydroheat for 4-14 h, then cool to room temperature; (3) Filtering the product obtained in step (2) to obtain a solid, washing the solid three times with distilled water, and then drying the solid at 140-170°C for 4-9 hours. The obtained sample is calcined in an air atmosphere at 200-500°C for 2-5 hours to obtain a carbon nickel support, which is referred to as a precursor; (4) Preparation of palladium nickel catalyst Take 15 mg of the precursor obtained in step (3) and 15 mg of PdO·H2O and place them in a 5 mL centrifuge tube. Add 3.5 mL of distilled water and ultrasonicate for 50-90 min to obtain a uniformly dispersed suspension. (5) The suspension obtained in step (4) is heated in a high-pressure reactor at 120-220°C for 1-5 h, and then the resultant is filtered. The filtered solid material is dried at 60-90°C for 1-8 h to obtain a palladium-nickel composite catalyst.

2. The preparation method according to claim 1, wherein: In step (2), the concentration of the glucose solution is 0.5 mol / L.

3. The preparation method according to claim 1, wherein: In step (2), the hydrothermal temperature is 180°C and the time is 10 h.

4. The preparation method according to claim 1, wherein: In step (3), the drying temperature is 160°C and the drying time is 8 h.

5. The preparation method according to claim 1, wherein: In step (3), the sample was calcined at 450°C for 3 h.

6. The preparation method according to claim 1, wherein: In step (4), the ultrasonic treatment time is 70 min.

7. The preparation method according to claim 1, wherein: In step (5), the reaction temperature is 200°C and the heating time is 3 h.

8. The preparation method according to claim 1, wherein: In step (5), the drying temperature is 90°C and the drying time is 6 h.

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