Alumina is a crucial chemical raw material. To date, at least eight distinct forms of alumina have been identified, each exhibiting unique macroscopic structural properties. The term “activated alumina” typically refers to γ-Al₂O₃, though it may also denote mixtures of κ, η, and γ-type alumina.   

Observation via electron microscopy and X-ray powder diffraction reveals that activated alumina is actually composed of agglomerated microparticles, which themselves are aggregates formed by the coalescence of primary particles. Within these aggregates, micropores of varying sizes are formed. Consequently, activated alumina possesses a high specific surface area and porosity, exhibiting highly reactive chemical properties.

Activated alumina selectively adsorbs moisture or target organic compounds from various gases and certain liquid mixtures. After adsorption saturation, it can be regenerated by heating to remove water through desorption. This adsorption-regeneration cycle can be repeated multiple times. Activated alumina is primarily used as an adsorbent, water purifier, catalyst, and catalyst carrier. Significant progress has been made in research on industrial-grade activated alumina as an adsorbent for wastewater treatment.

Industrial oxygen production, textile industry, electronic industry gas drying, fluoride removal from drinking water, fluoride removal in alkylbenzene production within petrochemicals, and acid removal/regeneration in transformer oil are typically achieved using activated alumina.

In summary, activated alumina has the following applications: 

Activated alumina as a desiccant;

Activated alumina as an adsorbent;

Activated alumina as a catalyst or catalyst support;

Activated alumina can also be used in pharmaceutical applications and as a ceramic material. 

In practical applications, activated alumina with high specific surface area and a concentrated pore size distribution demonstrates significant advantages in processes such as petroleum hydrocracking, hydrofinishing, hydroprocessing, dehydrogenation reactions, and automotive exhaust purification. Therefore, beyond preparation methods, characterizing performance parameters like specific surface area, pore size, and activity level for this type of alumina is critically important.