Catalyst Preparation Method

Every method of making catalysts is actually composed of a series of operating units. For convenience, people set the name of the key and characteristic operating unit as the name of the manufacturing method. Traditional methods include mechanical mixing method, precipitation method, impregnation method, solution evaporation method, hot melting method, soaking method (leaching method), ion exchange method, etc.
1. Mechanical mixing method
Add two or more substances into the mixing equipment and mix them. This method is simple and easy. For example, the manufacture of conversion-absorption desulfurizer is to measure the powder of active components (such as manganese dioxide, zinc oxide, zinc carbonate) and a small amount of binder (such as magnesium oxide, calcium oxide) Continuously add to a turntable with adjustable speed and inclination, while spraying metered water and powder rolling, mixing and bonding to form a sphere with a uniform diameter, and the sphere is dried and roasted to become the finished product.
2. Precipitation
This method is used to make catalysts that require high dispersion and contain one or more metal oxides. When manufacturing multi-component catalysts, suitable precipitation conditions are very important to ensure the uniformity of product composition and manufacture high-quality catalysts. The usual method is to add a precipitating agent (such as sodium carbonate, calcium hydroxide) to one or more metal salt solutions, and undergo precipitation, washing, filtration, drying, molding, and roasting (or activation) to obtain the final product.
3. Dipping method
Immerse a carrier with high porosity (such as diatomaceous earth, alumina, activated carbon, etc.) into a solution containing one or more metal ions, keep a certain temperature, and the solution enters the pores of the carrier. The carrier is drained, dried and calcined, and a layer of required solid metal oxide or its salts is attached to the inner surface of the carrier.
4. Spray Evaporation
It is used to make catalysts for fluidized beds with particle diameters ranging from tens of microns to hundreds of microns. For example, in the manufacture of m-dicarbonitrile catalyst by ammonification oxidation of m-xylene fluidized bed, the metavanadate and chromium salt aqueous solution with given concentration and volume are fully mixed, and then mixed with quantitative new silica gel, pumped into In the spray dryer, after being atomized by the nozzle, the water is evaporated to dryness under the action of the hot air flow, and the material forms a microsphere catalyst, which is continuously drawn out from the bottom of the spray dryer.
5. Hot melt method
The hot melting method is a special method for preparing some catalysts, which is suitable for a small number of catalysts that have to go through the smelting process, in order to smelt each component into a uniformly distributed mixture with the help of high temperature conditions, and cooperate with necessary subsequent processing to obtain Catalyst with excellent performance.
6. Dipping method
From the multi-component system, use a suitable liquid agent (or water) to extract part of the material to make a catalyst with a porous structure. For example, in the manufacture of skeleton nickel catalyst, a certain amount of nickel and aluminum are melted in an electric furnace, and the molten material becomes an alloy after cooling. The alloy is broken into small particles, soaked in aqueous sodium hydroxide solution, and most of the aluminum is dissolved (to generate sodium metaaluminate ), which forms a porous highly active framework nickel.
7. Ion exchange method
Metal cations (such as Na) of certain crystalline materials (such as synthetic zeolite molecular sieves) can be exchanged for other cations. Put it into a solution containing other metals (such as rare earth elements and some noble metals) ions, and exchange other metal ions with Na under controlled concentration, temperature, and pH conditions.