Application of high-purity alumina in the field of catalysts

Time:

2023-05-31

Alumina is a stable oxide of aluminum with the chemical formula Al2O3, which is a kind of inorganic non-metallic material. Alumina contains elemental aluminum and oxygen. If the bauxite raw material is chemically treated to remove oxides such as silicon, iron, and titanium, the product obtained is an alumina raw material with high purity, and the Al2O3 content is generally above 99%. The mineral phase is composed of 40% to 76% γ-Al2O3 and 24% to 60% α-Al2O3. Gamma-Al2O3 can be converted into α-Al2O3 at 950-1200 ℃, and significant volume shrinkage occurs at the same time.

In modern petrochemical and chemical industries, more than 90% of chemical reactions need to be realized through catalysts. At the same time, catalysts are also widely used in new energy development, comprehensive utilization of resources and environmental pollution control. It can be seen that the amount of catalysts is very large, and the varieties of catalysts are also various, but how to improve the efficiency of catalyst use has been a concern of major enterprises at home and abroad in recent years, so predecessors have developed methods to improve catalyst efficiency through catalyst carriers. After years of research and development, solid catalysts used in oil refining, petrochemical or fine chemical industries all need to use supports. The proportion of γ-alumina (activated alumina) supports in the catalyst support industry is about 60%. Among them, about 10-20% need to use high-purity activated alumina as a carrier, mainly used in hydrogenation catalysts, special gas treatment catalysts and other precious metal catalysts. The main indicators include: specific surface area, pore volume, and pore size. In addition to its high purity, the high-purity activated alumina obtained by the alcohol-salt hydrolysis process can also adjust the specific surface area, pore volume, pore diameter and other related parameters of the product through process advantages to meet the index requirements of different catalyst supports.

Common shapes of catalyst supports include: columnar, annular, spherical, laminated, granular and extruded strips, etc. The process can also be roughly divided into two categories. To put it simply, one is to first make the activated alumina into the desired shape and then load the catalyst components up by soaking or the like; the other is to mix the activated alumina with the catalyst components and then make it into the desired shape through an instrument to form a new type of catalyst.

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