Preparation method of hydrogenation catalyst for nitrobenzene and derivatives thereof

Abstract

The invention relates to a preparation method of a hydrogenation catalyst for nitrobenzene and its derivatives. A carbon material is functionally modified with a high-molecular polymer and then loadedwith noble metal. The preparation method of the catalyst comprises the following steps: (1) the carbon material and the high-molecular polymer undergo ultrasonic treatment on in a certain concentration of a salt solution at a certain temperature for 0.5 to 6 hour to obtain a functionalized carbon material; (2) noble metal particles with a certain size distribution are prepared from the salt solution of the noble metal under the action of a protective agent and a reducing agent; (3) the aqueous solution or the organic solution of the obtained noble metal particles undergoes ultrasonic treatment for 10 min and is stirred for 2-12 h and then loaded on the functional group modified carbon material so as to obtain a noble metal-loaded catalyst. The preparation method of the catalyst is simple,effective and green and environmentally-friendly. After reduction by the reducing agent, the uniformly-dispersed noble metal-loaded catalyst with a certain size distribution is obtained. In addition,the catalyst has a broad application prospect in the field of catalysis of nitrobenzene and its derivatives.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and relates to a preparation method of a hydrogenation catalyst for nitrobenzene and its derivatives. Background technique [0002] As an organic intermediate, nitroaniline compounds are widely used in the production of dyes, medicines, pesticides, rubber additives and fine chemical intermediates. For example, o-nitroaniline is mainly used as a dye intermediate, the determination of trace iodide, the production of the pesticide carbendazim, etc.; 2-amino-5-nitrophenol is used for the production of neutral pink BL, the manufacture of metal complex dyes, Reactive black, leather spray red GL, leather spray black RL, solvent red BL, solvent red KL, etc. At present, nitroaniline compounds are mainly obtained by selective reduction of nitro compounds, including iron powder reduction method, alkali sulfide reduction method and catalytic hydrogenation method. The first two synthetic methods h...

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Problems solved by technology

Publication number [CN201210366356.8] discloses a method for highly selective hydrogenation of halogenated anilines using supported noble metals treated with sulfides at 30-70°C as catalysts and halogenated nitrobenzenes as raw materials. The prepared catalyst can effectively inhibit the side reaction of hydrodehalogenation, and the selectivity of the product is high; however, the limited and high cost of precious metal resources and the high specific surface energy of metal nanoparticles are easy to agglomerate and grow when heated, resulting in surface active sites. The problem of catalyst deactivation has always been a problem restricting the application of noble metal nanoparticle catalysts.

This process can only precipitate palladium hydroxide on activated carbon with the help of alkaline earth metal hydroxide, while other alkalis cannot reach the required pH value, the preparation process is cumbersome, and the particle size of the noble metal active component And the distribution is poor, the particle size is too large, so the activity of the catalyst is not high

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