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Silicon dioxide-protected carbon-based catalyst as well as preparation method and application thereof

A carbon-based catalyst, silica technology, applied in physical/chemical process catalysts, chemical instruments and methods, chemical/physical processes, etc., can solve the problems of carbon material pore collapse, few catalytic active sites, affecting catalytic performance, etc. , to achieve the effect of improving electrocatalytic performance, avoiding the reduction of specific surface area, and uniformity

Inactive Publication Date: 2019-04-26
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, during the high-temperature pyrolytic carbonization process, the carbon source precursors are easy to react and fuse with each other, resulting in the collapse of the pores of the final carbon material, the small specific surface area and the lack of catalytic active sites, which greatly affect its catalytic performance. On the other hand, some single-atom or cluster metals with catalytic activity are also easy to fuse and form large metal particles under high temperature environment, resulting in catalyst deactivation

Method used

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  • Silicon dioxide-protected carbon-based catalyst as well as preparation method and application thereof
  • Silicon dioxide-protected carbon-based catalyst as well as preparation method and application thereof
  • Silicon dioxide-protected carbon-based catalyst as well as preparation method and application thereof

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preparation example Construction

[0040] The preparation method of the carbon-based catalyst protected by silicon dioxide of the present invention, the specific steps are as follows:

[0041] (1) SiO 2 Coating steps:

[0042] Dissolve ethyl orthosilicate, catalyst, and solid carbon source containing metal and nitrogen in a mixed solvent of water and alcohol, and carry out a stirring reaction; after the reaction, filter the resulting precipitate and wash it with ethanol until the supernatant is neutral , dried to obtain a coated product;

[0043] (2) High temperature annealing steps:

[0044] The coated product is subjected to high temperature treatment in an inert atmosphere to obtain an intermediate product;

[0045] (3) Removal of SiO 2 step:

[0046] The intermediate product obtained in step (2) is acid-washed or alkali-washed, etched and removed from the surface of SiO 2 coating layer to obtain a carbon-based catalyst.

[0047] In step (1), the solid carbon source containing metal and nitrogen is a ze...

Embodiment 1

[0062] ① 1mmol (241.86mg) of iron nitrate, 30mmol (8.92g) of zinc nitrate, and 240mmol (19.70g) of dimethylimidazole were weighed according to the corresponding molar ratio, and the metal salts of iron nitrate and zinc nitrate were dissolved in 500mL of methanol. Methimidazole was dissolved in 400 mL of methanol. Then the metal salt solution was slowly added to dimethylimidazole and stirred for 2h. The product is obtained by centrifugation, and the product is washed two to three times with methanol, and dried overnight to obtain the iron-zinc bimetallic ZIF (recorded as Fe-ZIF, TEM sees figure 1 (a)).

[0063] ② Dissolve 600mg of iron-zinc bimetallic ZIF in 240mL of water, add cetyltrimethylammonium bromide solution 6mL (25mg / mL), NaOH solution 10mL (6mg / mL) and tetraethyl orthosilicate solution 1.2mL Dissolve in 6mL of methanol, stir at 25°C for 0.5h; centrifuge, wash with ethanol, and dry to obtain a coated sample (referred to as Fe-ZIF-SiO 2 , TEM see figure 1 (b)).

...

Embodiment 2

[0067] ① 1mmol (290.79mg) of nickel nitrate, 4mmol (1.19g) of zinc nitrate, and 32mmol (2.63g) of dimethylimidazole were weighed according to the corresponding molar ratio, and the metal salt nickel nitrate and zinc nitrate were dissolved in 500mL of methanol. Methimidazole was dissolved in 400 mL of methanol. Then the metal salt solution was slowly added to dimethylimidazole and stirred for 2h. Centrifuge to obtain the product, wash the product two to three times with methanol, and dry overnight to obtain the nickel-zinc bimetallic ZIF;

[0068] ②Dissolve 600mg of nickel-zinc bimetallic ZIF in 240mL of water, add cetyltrimethylammonium bromide solution 6mL (25mg / mL), Na 2 CO 3 Dissolve 10mL of the solution (10mg / mL) and 1.2mL of tetraethyl orthosilicate solution in 6mL of methanol, stir at 25°C for 0.5h; centrifuge, wash with ethanol, and dry to obtain the coating;

[0069] ③Calcinate the coating at high temperature, 1000°C, 3h, Ar 100sccm;

[0070] ④ After calcination, t...

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Abstract

The invention relates to the field of carbon nanometer materials and provides a method for preparing a nitrogen-doped carbon material with uniform metal distribution and application thereof to electro-catalysis. SiO2 coating is an important link to achieve the uniform distribution of metal atoms, can also be an important means to improve the nonmetallic material performance simultaneously and is specifically divided into SiO2 coating in an acidic environment and SiO2 coating in an alkaline environment. The method for preparing the carbon material with uniform metal distribution mainly comprises the following steps: (1) SiO2 coating step; (2) high-temperature annealing step; (3) SiO2 removal step to obtain a carbon-based catalytic material with uniform metal active site distribution. The metal and nitrogen co-doped carbon material catalyst prepared by the method provided by the invention is expected to be applied to the electro-catalytic fields such as carbon dioxide electrochemical catalytic reduction, oxygen reduction, hydrogen evolution and nitrogen fixation.

Description

technical field [0001] The invention relates to the field of carbon nanomaterials, in particular to a silicon dioxide-protected carbon-based catalyst and its preparation method and application. Background technique [0002] Carbon materials and their composites are widely used in the field of catalysis due to their rich pore structure and huge specific surface area. The carbon atoms on the carbon substrate can form the catalytic active center of the M-N-C structure (M represents the metal atom) with the nitrogen atom and the metal atom, which has been proven to exhibit excellent catalytic performance in many catalytic reactions. with CO 2 Taking the electrocatalytic reduction reaction as an example, carbon-based catalysts doped with transition metals Fe / Co / Ni and N elements have high CO 2 The electrocatalytic conversion efficiency and low overpotential, the product is mainly CO. [0003] High-temperature pyrolysis and carbonization treatment using solid carbon source prec...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J27/24B01J35/10C25B1/00C25B11/06
CPCC25B1/00B01J27/24C25B11/091B01J35/399B01J35/23B01J35/33B01J35/618B01J35/617B01J35/647B01J35/615
Inventor 胡超白思林邱介山
Owner XI AN JIAOTONG UNIV
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