First, It load catalytically active component .
1. Alumina with small specific surface area (or only a small amount of coarse-pored material) is usually used for loading more active catalyst components. The principle is that the use of such actived alumina carriers can eliminate the diffusion effect within pores, in the process of selective oxidation, it can reduce the depth of oxidation side reactions,
2. The actived alumina carrier with a large specific surface area has a well-developed pore structure, which can highly disperse the active component of the supported catalyst into fine particles, and prevent the sintering of the active component particles during use by means of the barrier effect of the carrier. It is a widely used alumina carrier.
Second, the surface of the active alumina carrier and the active components supported constitute a bifunctional catalyst.
For example, the platinum-alumina catalyst used in platinum reforming, in which alumina acts as both a support and an active component of the catalyst, of course, in some cases there is a strong relationship between the active alumina support and highly disperse metals such as platinum. Interactions can affect the catalytic properties of metals.
Since the active alumina carrier has different properties, such as density, pore structure, specific surface area, etc., even if it is of the same form, but its use is various.