What are the common catalyst preparation methods

Each method for making catalysts is actually a combination of a series of operating units. For convenience, the name of the key and distinctive unit of operation is used as the name of the manufacturing method. The traditional methods include mechanical mixing, precipitation, impregnation, solution evaporation, thermal melting, immersion, ion exchange, etc. The new methods developed now include chemical bonding, fibrillation, etc.

1. mechanical mixing method

More than two kinds of substances are added to the mixing equipment to mix. This method is simple and easy, for example, conversion - absorption type desulfurization agent manufacturing, is the active component (such as manganese dioxide, zinc oxide, zinc carbonate) and a small amount of binder (such as magnesium oxide, calcium oxide) of the powder measured continuously into a rotating speed and tilt can be adjusted in the turntable, while spraying into the measured water, powder rolling mixed bonding, the formation of a uniform diameter of the sphere, the sphere and then dried, roasted that is the finished product.

2. Sedimentation method

This method is used to manufacture catalysts that require high dispersion and contain one or more metal oxides. In the manufacture of multi-component catalysts, suitable precipitation conditions are very important to ensure the homogeneity of the product composition and the manufacture of high quality catalysts. The usual method is to add a precipitant (e.g. sodium carbonate, calcium hydroxide) to one or more metal salt solutions, and then precipitate, wash, filter, dry, shape, roast (or activate) the final product.

3. Impregnation method

The carrier with high porosity (such as diatomaceous earth, alumina, activated carbon, etc.) is dipped into a solution containing one or more metal ions and kept at a certain temperature, and the solution enters the pores of the carrier. The carrier is drained, dried and calcined, and a layer of solid metal oxides or their salts is attached to the inner surface of the carrier.

4. Spray evaporation method

It is used to make fluidized bed catalysts with particle diameters of tens to hundreds of microns. For the manufacture of m-xylene fluidized bed ammonia oxidation catalysts such as m-dicarbonitrile, a given concentration and volume of aqueous solution of metavanadate and chromium salts are mixed thoroughly, then mixed with a quantitative amount of freshly made silica gel and pumped into the spray dryer.

5. Hot Melt Method

The hot melt method is a special method for the preparation of certain catalysts, which is suitable for a few catalysts that have to go through the melting process, in order to melt the components into a uniformly distributed mixture with the help of high temperature conditions, and with the necessary subsequent processing, excellent catalysts can be produced.