Molecular sieve packaged noble metal catalyst as well as preparation method and application thereof

A precious metal catalyst, precious metal technology, applied in molecular sieve catalysts, including molecular sieve catalysts, catalysts, etc., can solve problems such as affecting the catalytic performance of catalysts

Pending Publication Date: 2021-10-29
SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the multi-step crystal transformation method is also easy to form miscellaneous crystals, which affects the catalytic performance of the catalyst.

Method used

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  • Molecular sieve packaged noble metal catalyst as well as preparation method and application thereof
  • Molecular sieve packaged noble metal catalyst as well as preparation method and application thereof
  • Molecular sieve packaged noble metal catalyst as well as preparation method and application thereof

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Experimental program
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preparation example Construction

[0031] The invention provides a method for preparing a molecular sieve-encapsulated noble metal catalyst, comprising the following steps:

[0032] (1) heating and mixing the noble metal precursor with polyvinyl alcohol and water to obtain a premixed solution; the noble metal is one or more of Pd, Pt, Ru and Rh, and the noble metal precursor is a chloride of a noble metal, One or more of noble metal chloramines, noble metal nitrates, noble metal acetates and noble metal hydrochloric acid;

[0033] (2) NaBH 4 Mixing with the premixed solution, performing a reduction reaction to obtain a precious metal sol dispersion;

[0034] (3) mixing the molecular sieve with the precious metal sol dispersion, and performing the first drying and the first roasting on the obtained solid after the solid-liquid separation to obtain the molecular sieve with the precious metal loaded on the surface;

[0035] (4) Mix the molecular sieve loaded with the precious metal on the surface with the organi...

Embodiment 1

[0055] (1) Take 0.167g of palladium chloride, add it into 8g of water, stir evenly, add 0.4g of PVA, stir evenly, heat to 80°C for 10 minutes to peptize. Then 0.1mol / L NaBH 4 Aqueous solution (NaBH 4 The molar ratio to Pd is 5:1) was quickly added to the above solution to obtain a PVA-stabilized Pd sol; after vigorous stirring for 30 min, it was ready for use.

[0056] (2) Add 10 g of molecular sieve molecular sieve carriers with a grain size of 500 nm and a silicon-aluminum ratio of 30 to (1), continue stirring for 3 hours until the color of the solution fades, and finally centrifuge and wash until no Cl is detected. ﹣ Finally, the sample was dried in an oven at 100°C for 5h, and then calcined at 500°C for 5h in the air atmosphere of a muffle furnace to obtain a molecular sieve with a Pd content of 1wt% on the surface of a noble metal, which was designated as Pd / H-ZSM-5. use.

[0057] (3) Disperse the surface-loaded noble metal molecular sieve prepared in (2) in 0.1mol / L T...

Embodiment 2

[0062] (1) Take 0.133g of chloroplatinic acid, add it into 8g of water, stir evenly, add 0.4g of PVA, stir evenly, heat to 80°C for 10 minutes to peptize. Then 0.1mol / L NaBH 4 An aqueous solution (the molar ratio of NaBH4 to Pd is 4:1) was quickly added to the above solution to obtain a PVA-stabilized Pd sol; after vigorous stirring for 30 min, it was ready for use.

[0063] (2) Add 10 g of Silicalite-1 molecular sieve carrier with a grain size of 400 nm to (1), continue to stir for 3 hours until the color of the solution fades, and finally centrifuge and wash until no Cl is detected. ﹣ Finally, the sample was dried in an oven at 100°C for 5h, and then calcined at 500°C for 5h in the air atmosphere of a muffle furnace to obtain a Pd / H-ZSM-5 catalyst with a Pt content of 0.5%.

[0064] (3) Disperse the catalyst prepared in (2) in 0.1mol / L TPAOH solution (1g catalyst corresponds to 10mL TPAOH solution), stir at room temperature for 30min, then transfer it to the reaction kettle, ...

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Abstract

The invention provides a molecular sieve packaged noble metal catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. In the presence of polyvinyl alcohol, precious metal is reduced into precious metal sol under the reduction action of NaBH4, so that agglomeration of precious metal particles can be avoided; a molecular sieve and the precious metal sol dispersion liquid are mixed, the polyvinyl alcohol is removed after first roasting, and the precious metal is loaded on the surface of the molecular sieve. In the invention, the organic amine in a template agent and the noble metal on the surface of the molecular sieve form an organic ligand, the molecular sieve is subjected to secondary crystallization in the heating crystallization process, and the noble metal is brought into the pore channel of the molecular sieve; meanwhile, the molecular sieve is promoted to form a larger cavity in the heating crystallization process, so that entering and diffusion of reactants and products are facilitated. The preparation method provided by the invention is simple to operate and low in difficulty, and does not generate crystal transformation reaction, so that the catalytic performance of the catalyst is ensured, and the obtained molecular sieve packaged noble metal catalyst has good catalytic performance.

Description

technical field [0001] The invention relates to the technical field of catalysts, in particular to a molecular sieve-encapsulated noble metal catalyst and its preparation method and application. Background technique [0002] Metal particles are a common form of metal catalysts, and their size effect has a great impact on the activity, selectivity and stability of the catalyst. Especially for noble metal components, the size effect is significantly greater than that of other non-noble metals. According to the size of the metal, it can be divided into large particle clusters > 100nm, nanoparticles 1 ~ 100nm, and sub-nanometer clusters < 1nm and single-atom catalysts. Generally speaking, the smaller the particle size, the higher the surface free energy and coordination unsaturation of the particle, the more it can show some higher catalytic activity and selectivity, such as the discovery and application of Au catalyst at the end of the last century . However, because t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/068B01J29/44B01J29/74C07C5/333C07C5/41C07C11/06C07C15/06F23G7/07
CPCB01J29/44B01J29/068B01J29/7415B01J35/0013B01J35/006F23G7/07C07C5/3337C07C5/417C07C2529/068C07C2529/74B01J2229/186C07C11/06C07C15/06Y02P20/52
Inventor 吴志伟樊卫斌董梅范超秦张峰朱华青
Owner SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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