Role of catalyst support
The mechanical function of catalyst support is as the skeleton of active components, which plays a role in dispersing active components and increasing the strength of catalyst. Experiments show that in addition to this pure mechanical function, the catalyst support will have a great impact on the activity and selectivity of the catalyst. For example, in the reaction of gas-phase oxidation of ethylene to vinyl acetate, the effect of different carrier composition and different calcination temperature on the yield of the reaction product. It can be seen from the table that when the catalyst support composition is the same and the calcination temperature is different, the yield of vinyl acetate of the catalyst calcined at 1200 ℃ is twice higher than that calcined at 900 ℃; In addition, when the carriers with different composition are calcined at 900 ℃, the yield is twice as high. It can be seen that the support has a great influence on the performance of the catalyst.
For the same catalytic reaction, the same active components are used, but different supports are selected, the catalyst activity and product composition will also be very different. Generally, the function of the support is to improve the physical properties of the catalyst particles, such as increasing the specific surface area and pore volume of the catalyst. However, in many cases, after the carrier loads the active component, some form of action occurs between the active component and the carrier, resulting in the change of the essence of the active surface, which can also be inspired by the examples shown above. The role of support in catalyst is sometimes very complex.