Method for preparing heterogeneous crystal nucleus nano-metal powder by near/supercritical hydrothermal reduction
A technology of nano metal powder and supercritical water, which is applied in the field of near/supercritical hydrothermal reduction, can solve the problem that atomic metal is difficult to rapidly and uniformly nucleate nano metal powder particle size controllability, etc., and achieves a small product particle size. , Improve the controllability, the effect of uniform particle size distribution
Active Publication Date: 2017-03-01
TAIYUAN UNIV OF TECH
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Problems solved by technology
[0005] The technical problem to be solved by the present invention is: how to realize fractional crystallization (separation of nucleation and growth process), solve the problem that the atomic state metal itself is difficult to nucleate quickly and uniformly and the controllability of the particle size of nano-metal powder
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[0016] This implementation case takes the preparation of nano-copper powder in near / supercritical water as an example, using iron hydroxide sol as the crystal nucleus precursor, copper sulfate as the metal salt, ethylenediaminetetraacetic acid as the complexing agent, and hydrogen as the reducing agent. The inventive method is described:
[0017] (1) Ferric chloride is used as raw material to configure ferric hydroxide sol. The operation steps are as follows: first prepare a saturated ferric chloride solution, then add the saturated solution dropwise into boiling water, continue to boil until the liquid turns reddish brown, stop heating, and then obtain ferric hydroxide sol.
[0018] (2) Use a high-pressure pump to pressurize the ferric hydroxide sol at 25°C to 25MPa and mix it with preheated near / supercritical water (temperature 450°C, pressure 25MPa), so that the temperature of the mixture rises rapidly to 350°C (Temperature will decrease during mixing). The product genera...
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Abstract
The invention belongs to the field of near-and super-critical hydrothermal reduction and particularly relates to a method for preparing heterogeneous crystal nucleus nanometer metal powder by near-and super-critical hydrothermal reduction. The method comprises the steps that firstly, metal hydroxide sol is adopted as a crystal nucleus precursor and dehydrated in near-and super-critical water rapidly to generate a large amount of superfine metal oxide crystal nucleuses; and secondly, complex metal ions and hydrogen react to generate atomic metal which is deposited on the surfaces of the generated metal oxide crystal nucleuses and thus enables the crystal grains to grow continuously into the nanometer metal powder with a certain granularity. The method disclosed by the invention has the advantage that by controlling the number of the crystal nucleuses, the grain size of nanometer metal products can be controlled effectively.
Description
technical field [0001] The invention belongs to the field of near / supercritical hydrothermal reduction, in particular to a method for preparing heterogeneous crystal nucleus nanometer metal powder through near / supercritical hydrothermal reduction. Background technique [0002] Nano metal powder (particle size less than 100nm) has superior physical and chemical properties compared with ordinary metal powder, such as large specific surface, small size effect, interface effect, quantum effect and quantum tunnel effect, etc. It is widely used in industrial fields such as photoelectric catalysis, pharmaceutical preparation, colored coatings, lubricating oil additives and wear-resistant coatings of mechanical materials. Common nano-metal powders include platinum, silver, copper, nickel, cobalt, etc. At present, the common nano-metal preparation methods include mechanical grinding, electrolysis, microemulsion, spray pyrolysis, and liquid phase reduction. Among them, the mechanica...
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IPC IPC(8): B22F9/24
Inventor 周璐马红和马素霞李红格郑仙荣
Owner TAIYUAN UNIV OF TECH