Catalysis can be divided into the following types
1 homogeneous catalysis. Catalyst and reactants are all in the same phase of catalysis, such as homogeneous acid-base catalysis, homogeneous complex catalysis. Homogeneous catalysis is mostly carried out in the liquid phase. The active centers of homogeneous catalysts are relatively homogeneous, with higher selectivity and fewer side reactions, but the catalysts are difficult to separate, recover and regenerate.
2 heterogeneous catalysis. Catalysis occurs at the interface of the two phases. Typically the catalyst is a porous solid and the reactants are liquid or gaseous. In the heterogeneous catalytic reaction, the solid catalyst chemically adsorbs the reactant molecules, activates the reactant molecules, reduces the activation energy of the reaction, and accelerates the reaction rate. The surface of the solid catalyst is not uniform, and only a part of the point chemically adsorbs the reactant molecules, which is called the active center. Most of the catalysis in industrial production belongs to heterogeneous catalysis.
3 biocatalysis. A catalytic reaction carried out by an enzyme in an organism. The catalytic action of the enzyme has the characteristics of high selectivity, high catalytic activity and mild reaction conditions, but it is greatly affected by temperature, pH value in the solution, ionic strength and the like.
4 automatic catalysis. Self-catalysis of the reaction product. In some reactions, the products or intermediates of certain reactions have a catalytic function that allows the reaction to be greatly accelerated after an induction period. Autocatalysis is one of the necessary conditions for chemical oscillations.