CN113036169A

CN113036169A - Preparation method of nano palladium catalyst and application of nano palladium catalyst in small molecule oxidation

Info

Publication number: CN113036169A
Application number: CN202110273566.1A
Authority: CN
Inventors: 康毅进; 李宏健; 何胜兰; 岳秦
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2021-03-15
Filing date: 2021-03-15
Publication date: 2021-06-25

Abstract

The invention discloses a preparation method of a nano palladium catalyst and application thereof in micromolecular oxidation, wherein the catalyst is a palladium tetrahedral nano-framework (Pd TF) exposing a specific {111} crystal face. The nano-framework is prepared by dissolving a palladium precursor and a carbonyl compound in an N, N-dimethylformamide solution and carrying out hydrothermal reaction. The invention abandons the surfactants (PVP, CTAB, OAm and the like) used by the traditional preparation method of the nano material, and utilizes the reduction performance of carbonyl compounds and the adsorption performance of the carbonyl compounds on specific crystal faces to obtain the palladium catalyst with a specific shape in a highly controllable way under the condition without other ligands. The nano material prepared by the method has regular appearance, uniform size and clean surface, and shows excellent catalytic activity and stability in small molecule oxidation. Meanwhile, the synthesis method is simple, strong in operability, easy in condition control, wide in applicability and has industrial application potential.

Description

Preparation method of nano palladium catalyst and application of nano palladium catalyst in small molecule oxidation

[ technical field ] A method for producing a semiconductor device

The invention belongs to the technical field of catalysts, and particularly relates to a preparation method of a nano palladium catalyst and application of the nano palladium catalyst in small molecule oxidation.

[ background of the invention ]

With the development of nano materials and the maturation of energy conversion technology, alcohol fuel cells show a wide prospect of sustainable energy supply in the fields of portable electronic equipment and electric automobiles. Ethanol as a fuel for a cell has a higher energy density and a lower Nafion membrane penetration rate than methanol. Meanwhile, the direct ethanol fuel cell is safer in performance due to the higher boiling point and the non-toxic characteristic. The noble metal nano palladium is an effective electrocatalyst of an ethanol fuel cell, has low toxicity and excellent ethanol catalytic activity, and has attracted wide attention worldwide in recent years.

Researches show that the catalytic performance of the catalyst directly depends on the nano structure of the catalyst, and nano materials exposing different crystal faces often have different catalytic rates and selectivities. However, conventional nano-synthesis techniques usually introduce a large amount of surfactants, such as PVP, CTAB, OAm, etc., when preparing a nano-catalyst with a specific morphology. Although the addition of the surfactants is beneficial to shaping the morphological structure of the nano material, the change of the growth rate of the nano crystal is realized by changing the adsorption strength or coordination environment of the reaction intermediate. But inevitably results in a large number of active sites being capped with active agent, thereby greatly inhibiting the catalytic performance of the catalyst, and these surfactants are strongly bound and generally difficult to remove. Therefore, the development of a nano-synthesis technology without a surfactant is an important technology for improving the nano-catalytic performance and is a main target for realizing the commercial upgrade of the fuel cell.

The invention skillfully utilizes the reduction performance of carbonyl compounds and the adsorption performance of the carbonyl compounds on specific crystal faces, adopts a milder and simpler method to prepare the palladium tetrahedral framework (Pd NF) with regular appearance and uniform size without introducing a surfactant. Thanks to the clean surface and the specific nanostructure, the nano palladium catalyst shows excellent catalytic activity and stability in ethanol oxidation. Meanwhile, the invention has simple synthesis, wide applicability and potential application prospect.

[ summary of the invention ]

[ problem to be solved ]

The invention aims to provide a nano palladium catalyst and a preparation method thereof, and aims to solve the problems of low activity, poor stability and the like of a palladium nano material synthesized by a traditional preparation method.

[ technical solution ] A

Therefore, the invention adopts the following technical scheme to realize the purpose:

a nano-palladium catalyst is provided. The catalyst is a palladium tetrahedral nano-framework (Pd TF) exposing specific {111} crystal planes.

The catalyst is prepared by the following steps:

respectively dissolving a palladium precursor and a carbonyl compound in N, N-dimethylformamide, mixing and transferring to a reaction kettle after a homogeneous solution is formed. The Pd TF can be obtained through hydrothermal reaction.

Optionally, the palladium precursor in the above step may be organic palladium acetylacetonate, or inorganic palladium chloride or sodium chloropalladate, and the molar concentration is 1 to 10 mmol/L.

Optionally, the carbonyl compound in the step can be molybdenum carbonyl and tungsten carbonyl, and can also be other carbonyl compounds, and the molar concentration is 1-10 mmol/L.

Optionally, the purity of the N, N-dimethylformamide in the step is 95-1, and the volume of the N, N-dimethylformamide is 10 ml.

Optionally, the hydrothermal reaction temperature in the above steps is 25-150 ℃, the reaction time is 1-24 h, and the material filling is 20-80%.

Under the alkaline condition, the catalyst has excellent catalytic performance when catalyzing the ethanol oxidation. The maximum current density is 3.56A/mg_PdApproaching 4.5 times that of commercial Pd/C, while the chronoamperometric long-term test showed less activity decline compared to commercial Pd/C. Therefore, the catalyst of the invention can be used as a high-efficiency catalyst of an ethanol fuel cell.

The invention has the beneficial effects that:

1. the synthesis condition is mild, the preparation method is simple, the operation technology is easy, and the industrial large-scale batch production is facilitated.

2. The raw materials used for design are few and are easy to obtain; the equipment used by the design is simple and has strong operability.

3. The obtained palladium tetrahedral nano-frame is regular in shape, uniform in size and clean in surface.

4. The prepared palladium catalyst has excellent activity and stability for electrocatalytic oxidation of ethanol, and has industrial application prospect.

[ description of the drawings ]

FIG. 1 is a TEM image of a palladium tetrahedral nano-framework (Pd TF) prepared in example 1-2;

FIG. 2 is a high resolution HAADF-STEM of the palladium tetrahedral nano-framework (Pd TF) prepared in example 1 and the corresponding selected electron diffraction pattern;

FIG. 3 is an XRD pattern of palladium tetrahedral nano-frameworks (Pd TF) prepared in example 1-2;

FIG. 4 shows the results of ethanol electrooxidation activity test of palladium tetrahedral nano-framework (Pd TF) prepared in example 1.

[ detailed description ] embodiments

The invention will be further elucidated and described with reference to the embodiments of the invention described hereinafter.

Example 1:

0.5mmol of acetylacetone and 0.07mmol of molybdenum hexacarbonyl are respectively dispersed in 50ml of N, N-dimethylformamide solution, after ultrasonic dissolution, 5ml of each solution is uniformly mixed and then transferred to a 50ml high-pressure reaction kettle. Tightly screwing the hydrothermal kettle cover, and placing the kettle cover in an oven for constant temperature reaction at 60 ℃ for 3 h. And naturally cooling to room temperature after the reaction is finished, adding a mixed solution of ethanol and acetone, centrifuging and washing to obtain the palladium tetrahedral nano-framework (Pd TF).

Example 2:

0.5mmol of acetylacetone and 0.07mmol of tungsten hexacarbonyl are respectively dispersed in 50ml of N, N-dimethylformamide solution, after ultrasonic dissolution, 5ml of each solution is uniformly mixed and then transferred to a 50ml high-pressure reaction kettle. Tightly screwing the hydrothermal kettle cover, and placing the kettle cover in an oven for constant temperature reaction at 60 ℃ for 3 h. And naturally cooling to room temperature after the reaction is finished, adding a mixed solution of ethanol and acetone, centrifuging and washing to obtain the palladium tetrahedral nano-framework (Pd TF).

The above description is only for the preferred embodiment of the present invention and should not be taken as limiting the invention, but rather as the invention is intended to cover all equivalent changes and modifications which are within the scope of the invention as defined by the appended claims.

Claims

1. A nano-palladium catalyst characterized by: the catalyst is a palladium tetrahedral nano-framework (Pd TF) exposing specific {111} crystal planes.

2. The method for preparing Pd TF according to claim 1 comprises: respectively dissolving a palladium precursor and a carbonyl compound in N, N-dimethylformamide, mixing and transferring to a reaction kettle after a homogeneous solution is formed. The Pd TF can be obtained through hydrothermal reaction.

3. The preparation method according to claim 2, wherein the palladium precursor is either organic palladium acetylacetonate or inorganic palladium chloride or sodium chloropalladate, and the molar concentration is 1-10 mmol/L.

4. The preparation method according to claim 2, wherein the carbonyl compound can be molybdenum carbonyl, tungsten carbonyl or other carbonyl compounds, and the molar concentration is 1-10 mmol/L.

5. The method according to claim 2, wherein the N, N-dimethylformamide has a purity of 95 to 1 and a volume of 10 ml.

6. The preparation method according to claim 2, wherein the hydrothermal reaction temperature is 25-150 ℃, the reaction time is 1-24 h, and the material filling is 20-80%.