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Nanometer all-silicon molecular sieve and its preparation method and use

An all-silicon molecular sieve and nanotechnology, applied in molecular sieve catalysts, lactam preparation, chemical instruments and methods, etc., can solve problems such as reducing the diffusion efficiency of reactants and products, and achieve regular morphology, good catalytic performance, and crystallinity. high effect

Inactive Publication Date: 2012-05-02
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In 2010, the domestic apparent consumption of caprolactam reached 1124.7kt, but the total domestic output of caprolactam was only 493.9kt, and the self-sufficiency rate was only 43.9%. There is a big gap
[0012] In the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, the formation of carbon on the surface of the catalyst is the main cause of catalyst deactivation, mainly because the formed carbon deposits will cover the surface of the catalyst and block the micropores, thereby reducing the interaction between reactants and products. Diffusion efficiency

Method used

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  • Nanometer all-silicon molecular sieve and its preparation method and use
  • Nanometer all-silicon molecular sieve and its preparation method and use

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] According to the reaction mixture SiO 2 :TPAOH:H 2O=1:0.3:16 molar ratio, weigh 30.65g of 0.83M TPAOH in a two-necked bottle, and mechanically stir in an ice bath. Weigh 18.39 g of tetraethyl silicate and slowly drop it into the above solution to form a clear solution. Add 0.06g of lysine (L-Lys) to this clear solution, stir well, and then dynamically age at 80°C for 24h. The above reaction mixture was transferred into an autoclave for hydrothermal crystallization at 170°C for 72h. Filtrate, wash, dry and roast according to conventional methods to obtain 4.5 g of molecular sieve products. The catalyst morphology and particle size were characterized by Hitachi S-4800 scanning electron microscope, and the samples were vacuum-sprayed with gold before SEM analysis and testing. Scanning electron micrographs show that the obtained molecular sieve is in the shape of a regular hexagonal prism with a side length of about 50 nm.

[0032] Molecular sieve catalyzed cyclohexano...

Embodiment 2

[0035] Change the CHO mass space velocity (WHSV) of catalyst performance evaluation in embodiment 1 to 4h -1 , Other methods are similar to Example 1, the reaction time is 100h, the conversion rate of cyclohexanone oxime is not less than 99%, and the selectivity of caprolactam is not less than 96%. , The deactivated catalyst is regenerated by roasting and recycled 10 times, and its performance remains basically unchanged.

Embodiment 3

[0037] According to the reaction mixture SiO 2 :TPAOH:H 2 O=1:0.3:16 molar ratio, weigh 30.65g of 0.83M TPAOH in a two-necked bottle, and mechanically stir in an ice bath. Weigh 18.39 g of tetraethyl silicate and slowly drop it into the above solution to form a clear solution. Add 0.24g of lysine (L-Lys) to this clear solution, stir well, and then dynamically age at 80°C for 24h. The above reaction mixture was transferred into an autoclave for hydrothermal crystallization at 170°C for 72h. Filtration, washing, drying and roasting according to the usual method to obtain 4.4g of molecular sieve product. Scanning electron micrographs show that the obtained molecular sieve is in the shape of a regular hexagonal prism with a side length of about 40nm.

[0038] The prepared molecular sieve catalyzed cyclohexanone oxime gas-phase Beckmann rearrangement performance evaluation similar to Example 1. The reaction time is 6 hours, the conversion rate of cyclohexanone oxime is 99.6%, ...

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Abstract

The invention provides a nanometer all-silicon molecular sieve. The nanometer all-silicon molecular sieve is prepared from tetrapropylammonium hydroxide, a silicon source, water and amino acids. A mole ratio of the silicon source to tetrapropylammonium hydroxide to water is 1: [0.05 to 0.50]: [15 to 65]. The mass of the used amino acids is 0.5 to 5% of that of the silicon source. A mole number and a mass number of silica represent a mole number and a mass number of the silicon source. The invention also provides a preparation method of the nanometer all-silicon molecular sieve, and a use of the nanometer all-silicon molecular sieve in a cyclohexanone-oxime gas phase beckmann rearrangement reaction. The nanometer all-silicon molecular sieve has a high degree of crystallization, regular morphology and adjustable particle sizes of 40 to 160 nanometers. In a cyclohexanone-oxime gas phase beckmann rearrangement reaction, the nanometer all-silicon molecular sieve shows excellent catalytic activity, selectivity and stability.

Description

[technical field] [0001] The invention belongs to the technical field of zeolite preparation and application. Specifically, it relates to a nanometer all-silicon molecular sieve and its preparation method and application. [Background technique] [0002] Caprolactam is a monomer for synthesizing nylon-6, and it is widely used in fine chemical fields such as artificial leather, medicine, coatings and chemical additives. In 2010, the domestic apparent consumption of caprolactam reached 1124.7kt, but the total domestic production of caprolactam was only 493.9kt, and the self-sufficiency rate was only 43.9%, and there was a big gap. [0003] At present, the synthesis of caprolactam is mainly realized by the liquid-phase Beckmann rearrangement reaction of cyclohexanone oxime using concentrated sulfuric acid as a catalyst and solvent. The use of concentrated sulfuric acid not only leads to the need to use ammonia water for neutralization in the post-treatment process, thereby pro...

Claims

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Application Information

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IPC IPC(8): C01B39/08B01J29/06C07D223/10C07D201/04
CPCY02P20/584
Inventor 尹双凤邓益强
Owner HUNAN UNIV
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