Microporous Activated Alumina is a porous, highly dispersed solid material with a large surface area. Its microporous surface possesses characteristics required for catalytic reactions, such as adsorption performance, surface activity, and excellent thermal stability, thus being widely used as a catalyst and catalyst carrier in chemical reactions. It is also known as activated alumina or reactive alumina.

Properties of Microporous Activated Alumina

• Large Specific Surface Area: Activated alumina has a high specific surface area. By properly controlling the calcination conditions of alumina, activated alumina with a specific surface area up to 360 m²/g prepared. Using colloidal aluminum hydroxide obtained from the decomposition of NaAlO₂ as a raw material, the prepared activated alumina has very small pore sizes and a specific surface area up to 600 m²/g.
• Adjustable Pore Structure: Generally, calcining pure aluminum hydroxide can produce products with medium pore sizes. Using aluminum gel, etc., to prepare activated alumina can produce products with smaller pore sizes. When preparing activated alumina, adding certain organic substances, such as ethylene glycol and fibers, which burn out, can produce activated alumina with larger pore sizes.

• Surface Acidity and Good Thermal Stability: The surface of activated alumina is acidic and has good thermal stability.
• Mechanical Strength: It has high mechanical strength, smooth surface, no powdering, and after absorbing water, it does not expand, crack, or deform.
• Insolubility: It is insoluble in water, ethanol, and other solvents.
• Hygroscopicity: It has strong hygroscopicity.
• Regenerability: After adsorption saturation, water removed by heating at approximately 175 – 315°C for regeneration, and adsorption and regeneration can be multiple times.

Applications of Microporous Activated Alumina

• Catalyst and Catalyst Carrier: In the petrochemical and fertilizer industries, it is widely as a catalyst and catalyst carrier. It is an extremely stable catalyst carrier and also used as a catalyst itself.
• Desiccant: It is mainly for dehydration and drying of industrial gases in chemical, metallurgical, electronic, petroleum, and other industries, such as permanent gases like air, oxygen, and nitrogen, smelting gas, and petroleum cracking gas. It can also be as a desiccant for liquids and gases. It is a desiccant for deep drying of trace water, with a drying depth up to a dew point temperature below -70°C under certain operating and regeneration conditions. It widely used in gas and liquid drying in the petrochemical industry, drying of air in the textile industry, oxygen production industry, and automation instrumentation, and pressure swing adsorption in the air separation industry.
• Fluoride and Arsenic Remover: It is for defluoridation and dearsenification of drinking water, with a fluorine adsorption capacity of 2.1 mg/g. It has a strong adsorption capacity for fluorine. It can be in conjunction with household defluoridation cylinders and is an ideal domestic drinking water defluoridation device.
• Special for Hydrogen Peroxide: Used for the purification of hydrogen peroxide working fluid.
• Oil Purifier: Used for the decolorization and purification of transformer oil.
• Gas Purification Adsorbent: It can adsorb lubricating oil vapor from contaminated oxygen, hydrogen, carbon dioxide, natural gas, etc..

• Water Treatment: It is in water treatment, such as removing colors and odors from industrial sewage.
• Other Applications: It can be as a chromatographic analysis carrier. In the ingredients of unshaped refractory materials, high-performance water-purifying activated alumina can increase the green body density, fluidity, strength, increase the amount of secondary mullite generated, reduce water addition and porosity.

Preparation of Microporous Activated Alumina

Activated alumina usually prepared by heating and dehydrating aluminum hydroxide. Aluminum hydroxide, also known as hydrated alumina, has a chemical composition of Al₂O₃·nH₂O. Depending on the amount of crystal water, it divided into trihydrate and monohydrate aluminum hydroxide. After heating and dehydrating aluminum hydroxide, γ-Al₂O₃ obtained, commonly known as activated alumina.

Precautions for Microporous Activated Alumina

• Storage: It should be in a dry place indoors. The package not opened before use to avoid moisture absorption, which affects the use effect. It protected from water and moisture, and contact with oil or oil vapor.
• Regeneration of Fluoride Removal Filter Material: The activation of household fluoride removal filter material done by preparing an aluminum sulfate solution (3 liters of water, 0.3 kg of solid aluminum sulfate), soaking the alumina fluoride removal filter material in the above solution for 5 – 10 hours, discarding the immersion liquid (stirring appropriately during soaking), and then washing with clean water 3 – 5 times, using about 2 liters of water each time, or regenerating by adjusting the pH method with the pH value controlled at 7.5. The activated alumina fluoride removal filter material used continuously for 6 – 8 years. When the surface turns yellowish – brown, the fluoride removal effect significantly reduced, caused by water impurity contamination. Therefore, it is best to treat it with 3% dilute hydrochloric acid every six months, and the operation method is the same as the regeneration method.

Specifications of Microporous Activated Alumina

• Common Sizes: 1 – 3 mm, 2 – 4 mm, 3 – 5 mm, 4 – 6 mm, 5 – 7 mm, 6 – 8 mm. Spherical common sizes are 1/16″, 1/8″, 3/16″, 1/4″.
• Packaging: 25 kg/bag (lined with plastic bags, outer layer is plastic woven bags). There are also 50 kg/bag or ton bags depending on different manufacturers.