Multi-section jet flow efficient mixing device and method for supercritical hydrothermal synthesis of nano metal powder

Abstract

The invention discloses a multi-section jet flow efficient mixing device and method for supercritical hydrothermal synthesis of nano metal powder. The device comprises an atomizer, a Rafal annular feeder and a static mixer which are sequentially communicated from top to bottom, wherein the top of the atomizer is a precursor material inlet and the bottom is a precursor material outlet; the top of the static mixer is an inlet and the bottom is an outlet; the interior of the Rafal annular feeder is a vertical channel gradually narrows from two ends to the middle, and a middle region is communicated with four reaction fluid inlet pipes for feeding supercritical water, a modifying agent, a reducing agent and a pH regulator. The whole device disclosed by the invention realizes quick mixing and uniform mixing of the fluid through nozzle atomization, annular feeding acceleration and disturbance, the acid-base property of a mixed solution is regulated, and the quality of the nano metal particleis effectively guaranteed.

Description

technical field [0001] The invention belongs to the technical fields of chemical industry and environmental protection, and in particular relates to a multi-stage jet high-efficiency mixing device and method for supercritical hydrothermal synthesis of nano metal powder. Background technique [0002] As a cutting-edge technology, nanotechnology will bring great changes in the fields of chemical industry, medical treatment, communication and energy. As the basis for the development of nanotechnology, nanomaterials have become a hot spot in the field of material preparation. Nanomaterials have special and superior properties such as small size effect, surface effect, quantum tunneling effect, etc. because the particle size is reduced to below 100nm. Among them, nano-metal materials not only have the special properties of nano-materials, but also have the properties of metal materials, so they are widely used in many fields. The traditional preparation methods of nano-metal mat...

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Problems solved by technology

[0004] However, the following problems occurred in the application process of supercritical hydrothermal synthesis technology: the reaction temperature of supercritical hydrothermal synthesis reaction is about 400 ° C, and the reaction rate of supercritical hydrothermal synthesis is relatively fast, and the heating rate that is too low will cause metal salts The solution will react when it does not reach the reaction temperature, and the prepared product has a large particle size and uneven distribution. The current heating method is to mix the cold material with a large flow of high-temperature supercritical water and then quickly heat up to reach Therefore, ensuring the rapid and effective mixing of cold materials and supercritical water is the key to the preparation of nanomaterials with good performance; when preparing nanometal materials, it is necessary to add a reducing agent to reduce the nanometal oxides generated by supercritical hydrothermal synthesis into For nano-metals, it is necessary to add a modifier to modify the surface of the nanoparticles to prevent particle agglomeration. It is necessary to add a pH regulator to adjust the acidity and alkalinity of the reaction system to control the shape and particle size of the particles. Due to the reaction rate of the supercritical hydrothermal synthesis process Very fast, prolonging the reaction time will lead to larger particle size and serious agglomeration, which will seriously affect the performance of nanomaterials. Therefore, how to achieve rapid and uniform mixing of multiple fluids in a short time is critical to the performance of nanomaterials

The current mixing methods mostly use T-type or Y-type mixers for mixing. Because the flow rate and density of cold materials and supercritical water fluids are too different, this mixing method will cause concentration field, Inhomogeneous temperature field and velocity field, a large number of particles agglomerate together, and the product particle size is large and unevenly distributed, which seriously affects the performance of the product

At the same time, simple T-type or Y-type mixers cannot achieve uniform and rapid mixing of various materials, and thus cannot adjust the shape and particle size of nanoparticles. The prepared product has a large particle size and uneven particle size distribution, and the agglomeration phenomenon is obvious.

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