Supercritical hydrothermal synthesis method of nano metal or nano metal oxide particles

Abstract

The invention discloses a supercritical hydrothermal synthesis method of nano metal or nano metal oxide particles. The method includes the following steps that soluble metal salt solution and alkali liquor (or a mixture of alkali liquor, reducing agent solution and organic ligands) are fully mixed to serve as reaction precursors of supercritical hydrothermal synthesis; the reaction precursors and preheated supercritical water are pressurized and pumped into a mixer through a high-pressure pump, after temperature is raised in a direct mixing mode, supercritical hydrothermal synthesis reaction is conducted; after a period of reaction, the obtained product is cooled, centrifuged and dried, and the nano metal or nano metal oxide particles are obtained. The nano metal or nano metal nano metal oxide particles produced through the method have the advantages of being small in particle size, good in dispersibility, high in purity and the like.

Description

【Technical field】 [0001] The invention relates to a method for preparing nanoparticles, in particular to a method for supercritical hydrothermal synthesis of nanometer metal or nanometer metal oxide particles. 【Background technique】 [0002] Nano metal or nano metal oxide particles are important industrial products. Compared with ordinary metal or metal oxide powder, they have superior properties, such as large specific surface area, interface effect, quantum effect and quantum tunnel effect, etc. Endowed with various unique properties different from traditional materials and specific electrical, thermal, magnetic, optical and mechanical properties, it is widely used in various fields, such as being used as a catalyst, with small particle size, large specific surface, and particle surface Features such as large number of active centers, high catalytic efficiency and strong selectivity; in terms of sensors, it can be used as a coating film for sensors, which can greatly impro...

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Problems solved by technology

Physical methods include mechanical grinding and physical vapor deposition. The disadvantages are complex process equipment, low output, and difficulty in large-scale production.

The microemulsion method and the spray pyrolysis method generally have to undergo high-temperature heat treatment, which causes the particles to easily agglomerate and cause abnormal particle growth.

However, the conventional hydrothermal method has a long reaction cycle, usually requiring several hours or even several days of reaction time, which inevitably leads to the problem of larger particle growth.

The preparation of nano-metal particles by chemical electrolysis is a relatively mature and industrial production method, but the obtained metal powder usually needs to go through ball milling, sieving and other processes to finally obtain ultra-fine metal particles, and the electrolytic waste liquid contains a large amount of metal ions , arbitrary discharge will cause resource waste and environmental pollution, thus restricting the large-scale application of this method

The liquid-phase reduction method is a relatively active method for preparing nanoparticles in recent years, but this method usually requires the use of a large amount of organic solvents or highly toxic additives, which causes serious pollution in production and greatly limits its application.

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