Characteristics of amorphous alloy catalysts - preparation


Amorphous alloys can be mainly divided into quenching method and low-temperature chemical reduction method. Quenching method is currently one of the main methods for preparing various amorphous alloys, and has achieved industrial production and application.
  
Basic features: first the certain composition of nickel, aluminum, phosphorus, rare earth and other elements under the protection of inert gas heating and melting, alloy hydraulic spray to high-speed rotating copper roller, at a rate of 105~108 °C/s high-speed cooling, the disordered structure of the liquid alloy can be maintained to form an amorphous structure, crushing and screening to obtain amorphous alloy powder.
  
Amorphous alloys have the structure of "long-range disorder" and "short-range order", and the surface atoms are not saturated, which is easy to form a highly active catalytic activity center. Its composition can be modulated over a wide range, making it easy to improve the selectivity of the active center by changing the composition.

 

 

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Reni nickel catalyst science knowledge(1)

Physical and chemical properties: Reni nickel catalyst before activation is silver-gray amorphous powder (nickel-aluminum alloy powder), with a moderate degree of flammability, partial activation in the presence of water and the production of hydrogen easy agglomeration, long-term exposure to air is easy to weather. Nickel-aluminum alloy powder is activated into gray-black particles, accompanied by active hydrogen, extremely unstable, oxidative combustion in the air, must be immersed in water or ethanol for preservation. It was first used by American engineer Murray Rainey as a catalyst in the hydrogenation of vegetable oils. The preparation process is to treat nickel-aluminum alloy with concentrated sodium hydroxide solution, in this process, most of the aluminum will react with sodium hydroxide and dissolve, leaving a lot of micropores of different sizes. In this way, the surface of Raininickel is a fine gray powder, but from a microscopic point of view, each tiny particle in the powder is a three-dimensional porous structure, this porous structure greatly increases its surface area, and the large surface area brings high catalytic activity, which makes Raininickel widely used as a heterogeneous catalyst in organic synthesis and industrial hydrogenation reactions. Since "Rainey" is a registered trademark of Grace Chemicals, strictly speaking, only products manufactured by the company's Davidson Chemical Division can be called "Lanny Nickel". The term "metal backbone catalyst" or "sponge-metal catalyst" is used to refer to catalysts with a microporous structure and physical and chemical properties similar to Raney nickel.