Technical characteristics of amorphous catalysts


Compared with the corresponding crystalline alloys, amorphous alloys have more surface defects and less coordination number of surface atoms, so they have higher catalytic activity. The preparation of amorphous alloy catalysts includes the preparation of the master alloy, the pretreatment of the master alloy, and the activation of the catalyst. The original alloy composition of amorphous alloy is usually 40%-50% Ni-Al, and in equilibrium, the alloy in this composition range is mainly composed of Ni2Al3, NiAl3 and a small amount of Al/NiAl3 eutectic. The phase analysis results show that after the original alloy of the amorphous alloy catalyst is pumped by alkali, the Ni atom has an amorphous structure of "long-range disorder" and "short-range order". The XRD spectrum of the amorphous alloy catalyst has a diffuse peak at an angle of 2θ of 45o, while the same crystalline alloy has a spike. The specific surface area of BET is 145m2/g, and the amorphous alloy catalyst is a soft magnetic material with a saturation magnetization strength of 13.96emu/g.

 

 

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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.