Co-N-C/SiO2 composite nanometer catalyst, preparation method thereof and application

Abstract

The invention provides a preparation method of a Co-N-C / SiO2 composite nanometer catalyst. The method comprises the following steps: uniformly mixing and sintering cobalt metal precursor salt, a nitrogen-containing organic carbon source and mesoporous silica, so as to obtain the Co-N-C / SiO2 composite nanometer catalyst. In the catalyst, ultra small cobalt metal nanometer particles can be properly stabilized in a carbon layer, proper pore structures and pore diameters can further effectively promote the diffusion and the separation of reaction matrixes and products, and the catalyst has good dispersibility in an aqueous system and further is easy to recycle. The preparation method does not need any solvents, can obtain the composite nanometer catalyst by one step, and is easy and practical. The composite nanometer catalyst prepared through the method does not need any complex pretreatments, can be applied to hydrogen production-hydrogen addition coupling reaction, and shows excellent catalytic activity and stability for preparing phenylamine and derivatives thereof though nitrobenzene compounds.

Description

technical field [0001] The invention relates to the technical field of porous composite catalytic materials loaded with non-noble metals, in particular to a Co-N-C / SiO 2 Composite nanocatalyst, its preparation method and application. Background technique [0002] Metal nanoparticles have shown irreplaceable catalytic effects in the chemical industry, and thus have received extensive attention. How to improve the utilization efficiency, catalytic activity and stability of metal catalysts has become one of the core goals of current research. At present, it is mainly realized through the following three ways. The first approach: preparing ultra-small nanoparticles, increasing their specific surface area, and enriching surface defects (active sites), thereby providing higher catalytic active sites. The second approach is to synthesize supported catalysts and introduce porous supports with special surface properties, which can not only disperse metal nanoparticles to prevent t...

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Problems solved by technology

However, these methods all have the following disadvantages: first, due to the influence of the surface properties of the carrier and the reduction conditions, the size of metal nanoparticles is usually difficult to control precisely; second, in porous materials, while obtaining stable metal nanoparticles Maintaining its accessibility and mass transfer capability is a challenge; third, porous carbon materials are poorly dispersible in aqueous solutions due to their hydrophobic and other properties

However, most noble metal catalysts show poor coupling reaction selectivity and catalytic activity due to their different activities for hydrogen production and hydrogenation reactions, while non-noble metal catalysts tend to show lower catalytic activity.

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