Normal-pressure preparation method and application of block nanometer silver loading silica aerogel catalyst

Abstract

The invention discloses a preparation method of a block nanometer silver loading silica aerogel catalyst, and an application of the catalyst to preparation of 4-aminophenol from 4-nitrophenol through catalytic hydrogenation. A sol-gel method is adopted, and trimethylhexamethylene diisocyanate is used for cross-linking to obtain enhanced silica-based wet gel, which is dried at a normal pressure to prepare silica-based aerogel with the block shape well kept. The impregnation method is used to prepare the nanometer silver loading silica aerogel catalyst. The catalyst can have the block shape well kept. Silver is loaded on silica aerogel having a three-dimensional network porous structure, so that the dispersity of silver is increased. The chemical stability of the catalyst and the catalytic activity of the catalyst are improved. Further, the block is convenient to recycle and reuse. The catalyst is adopted to catalyze 4-nitrophenol to prepare 4-aminophenol through hydrogenation and is high in catalytic activity and good in stability.

Description

[0001] Technical neighborhood [0002] The invention belongs to the field of catalysts, and relates to a preparation method of a massive silica aerogel supported nano silver catalyst and its application in the preparation of 4-aminophenol by the catalytic hydrogenation of 4-nitrophenol. Background technique [0003] 4-nitrophenol is a non-biodegradable and toxic environmental pollutant, but 4-aminophenol is an important chemical raw material and pharmaceutical intermediate, which is widely used in the synthesis of pesticides, dyes, rubber additives, photoelectric functional molecules, etc. Fine chemicals and antipyretic and analgesic drugs. There are currently three methods for preparing 4-aminophenol: iron / acid chemical reduction method, electrochemical reduction method and catalytic hydrogenation method. These methods mainly have the following problems: although the process of iron / acid chemical reduction is simple and the technology is mature, the consumption of iron powder and...

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Problems solved by technology

These methods mainly have the following problems: Although the iron / acid chemical reduction method is simple in process and mature in technology, the consumption of iron powder and acid in production is relatively large, and a large amount of iron sludge and waste water are produced, which pollutes the environment and does not meet the requirements of green chemistry.

However, the direct use of silver nanoparticles is not only expensive and costly, but also prone to agglomeration under the influence of intermolecular forces affecting its catalytic performance, easy to sinter under high temperature conditions to deactivate the catalyst, and low reuse rate

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