Active alumina boasts a large specific surface area, various pore structures and pore size distributions, and rich surface properties, thus finding extensive applications in adsorbents, catalysts, and catalyst carriers.
Alumina, used as an adsorbent and catalyst carrier, is a fine chemical and a specialized chemical. Different applications require different physical and structural properties, which is why it is highly specialized and has a wide variety of grades and brands. Statistics show that the amount of alumina used as a catalyst and carrier exceeds the total usage of catalysts made from molecular sieves, silica gel, activated carbon, diatomite, and silicate gel. This highlights the crucial role of alumina in catalysts and carriers. Among them, η-Al2O3 and γ-Al2O3 are important catalysts and carriers, both being defective spinel structures. The differences between them are: the tetrahedral crystal structure (γ > η), the regularity of hexagonal layer stacking (γ > η), and the Al-O bond distance (η > γ, difference of 0.05-0.1 nm).
