Introduction to several primary carriers-Ⅰ

1. Activated alumina: the carrier used most for industrial catalysts. Low price, high heat resistance, and good affinity of active components.

2. Silica gel: chemical composition is SiO2. It is generally produced by acidification of sodium silicate (Na2SiO3). Silica is formed after the effect of sodium silicate and acid; Silicic acid polymerizes and condenses to form polymers with uncertain structure.

SiO2 is a widely used carrier, but its application in industry is less than that of Al2O3, which is due to difficulties in preparation, weak affinity with active components, and easy sintering in the presence of water vapor.

3. Diatomite: natural SiO2. Containing a small number of metal oxides and organic compounds, the pore structure and specific surface area vary with the origin. Acid treatment should be used before use. First, in order to improve the content of SiO2, increase the specific surface, specific pore volume and primary pore radius; Second, in order to improve thermal stability, the specific surface can be further increased after acid treatment. Diatomite is mainly used to prepare fixed bed catalysts.