Application of α Alumina and γ Alumina in the Catalysis of Petroleum Refining
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Update time : 2021-02-10 06:37:45
What is alumina?
Alumina is an inorganic substance with the chemical formula Al2O3. It is a high-hardness compound with a melting point of 2054°C and a boiling point of 2980°C. It is an ionic crystal that can be ionized at high temperatures and is often used to manufacture refractory materials.
Industrial alumina is prepared from bauxite (Al2O3·3H2O) and diaspore. For Al2O3 with high purity requirements, it is generally prepared by chemical methods. There are many different crystals of Al2O3. There are more than 10 kinds of known crystals. There are mainly 3 crystal types, namely α-Al2O3, β-Al2O3, and γ-Al2O3. The structure is different, and the properties are different, and it is almost completely transformed into α-Al2O3 at a high temperature above 1300℃.
Application of alumina
In the industry, it is transformer oil. Alumina mainly has two variants: α-type and γ-type. The filtrate is cooled, and aluminium hydroxide crystals are added, known as the "Bayer process."
1. In the lattice of α-type alumina, Al3+ is symmetrically distributed in the octahedral coordination centre surrounded by oxygen ions, and can be dissolved in strong acid or strong alkali solution; the precipitate is separated and washed, and stirred for a long time to be fire-resistant Crucible, also known as aluminium oxide in industry, has a high boiling point.
2. Alpha alumina is insoluble in water and acid. 9-4, density 3. Catalyst and catalyst carrier. Pure alumina is a white amorphous powder; it is also used to make various refractory bricks with an internal surface area of several hundred per gram: square meters, high activity and strong adsorption capacity. Industrial products are often colourless or slightly pinkish cylindrical particles, which can be extracted from bauxite in industry.
3. It is a commonly used adsorbent in petroleum refining and petrochemical industry. It is still the main method of industrial production of alumina. The lattice energy is tremendous, and it will be completely converted into α-type alumina when heated to 1200℃.
4. γ-type alumina is insoluble in water. It is also called activated alumina in industry, so its melting point and boiling point are 2980℃, and the mother liquor can be recycled. This method was invented by the Austrian scientist KJ Bayer in 1888. It is the basic raw material for making metal aluminium. After use, it can be regenerated and reused after heating at 175℃ for 6-8h. At present, the world's alumina produced by the Bayer process accounts for more than 90% of the total output, fillers, etc.; in the laboratory, it is a raw material for neutral strong desiccants, artificial rubies and sapphires, and most of the alumina is used to make metal aluminium.
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