1. Definition and Basic Properties
Definition
Activated alumina, also known as activated bauxite, is a porous, high – dispersion solid material with a large surface area. It is widely used as a catalyst and catalyst support due to its unique surface properties.
Key Facts
- Catalyst Support Activated Alumina has a high specific surface area, which can range from several hundred to over a thousand square meters per gram. This large surface area provides more active sites for catalytic reactions.
- The density of activated alumina is approximately 3.9−4.0 g/cm3, with a melting point of 2050∘C and a boiling point of 2980∘C.
- catalyst support activated alumina is insoluble in water and can slowly dissolve in concentrated sulfuric acid.
Controversies
There is some debate about the exact crystal structure and its impact on catalytic performance. Different crystal forms such as α – alumina and γ – alumina may have different catalytic activities, and researchers are still exploring the optimal crystal structure for specific catalytic reactions.
2. Production Methods
Definition
The production of activated alumina mainly involves processes that transform raw materials into a highly porous and active form. The most common industrial method is the rapid dehydration method.
Key Facts
- The rapid dehydration method quickly removes water from the precursor materials, resulting in the formation of a porous structure. For example, starting from aluminum hydroxide, heating it under specific conditions can lead to the formation of activated alumina.
- Another approach is the calcination of aluminum salts at high temperatures. The calcination temperature and time can significantly affect the properties of the resulting activated alumina, such as its pore size distribution and specific surface area.
