With the increase of alumina varieties and the frequent use of activated alumina, many users have compared the differences between the two. What are the differences between the two and how should we distinguish them.
The dehydration temperature is 900-1000c, which is high-temperature alumina, such as δ- Al2O3, θ- AI2O3,k-Al2O3, - 0ai2o3: this kind of alumina is generally inactive and is commonly used to smelt metal aluminum. Alumina prepared with dehydration temperature less than 600C has ρ- Al2O3, η- Al2O3,x-Al2O3, - Al2O3. Generally speaking, their specific surface area and pore volume are large, and they have ' "Activated alumina", so it is also called activated alumina, commonly used as - Al2O3, η- AI2O3. The activity of alumina is due to the hydroxyl group contained in its structure. Even if it is calcined at 1200 degree , its structural water will not be completely removed. Therefore, it can also be said that alumina is activated alumina.
The production of activated alumina is generally divided into neutralization method and alcohol aluminum method. In addition, there is another production method of activated alumina in China, namely rapid dehydration method. When preparing activated alumina, its precursor pseudo boehmite is generally prepared first, and then calcined to change its crystal phase into activated alumina. When the colloidal aluminum hydroxide is detected by X-ray diffraction, some are amorphous, and some show that they are consistent with the characteristic spectral lines of well crystallized boehmite, which is called pseudo boehmite or pseudo boehmite. The decomposition product of pseudo boehmite at 450 degree is - Al2O3 and η- Al2O3. - Al2O3 belongs to alumina in transition form and belongs to tetragonal system. The lattice is very similar to that of spinel (mgal2o3).
stay - In Al2O3, only 21.1/2 aluminum atoms are distributed in 24 cation sites, 2.2/3 vacancies in octahedron sites, and 8 aluminum atoms are distributed in tetrahedral voids. - Alumina is a kind of catalyst functional seasoning with good quality. The main reason is that it has high-temperature stability. It is also called activated alumina and aluminum glue in industry. It is a kind of commonly used catalyst carrier and is widely used in the production of catalyst carrier.
In the understanding process, it is learned that alumina is the product of heating and dehydration of aluminum hydroxide. With different initial aluminum hydroxide forms, dehydration temperatures and conditions, various forms of alumina can be obtained. Alumina co ownership ρ, ,η,δ,χ,κ,θ, There are eight crystal forms. The preparation of activated alumina is the same as that of alumina. Although alumina is activated alumina, there are still some differences in use, so we must pay special attention to it.