Application Of Hydrated Alumina
In the previous article, Shandong Avant as a professional manufacturer shared and discussed the various types and corresponding properties of alumina materials.
This article will focus on the broad range of applications of hydrated alumina.
1. As a precursor of activated alumina.
Activated alumina (γ-Al2O3) has rich mesoporous structure and active chemical properties, and has good thermal and hydrothermal stability under catalytic cracking (FCC) operating conditions. It has become a commonly used method to improve matrix activity.
Both pseudo-boehmite and boehmite are precursors of activated alumina and play different roles in FCC catalysts. The catalyst prepared with acidified pseudo-boehmite as a binder has the advantages of good pore structure and strong heavy oil cracking ability; the catalyst containing boehmite has better resistance to heavy metals.
2. Preparation of flame retardants.
Aluminum hydroxide (alumina trihydrate) powder is generally regarded as an ideal choice for plastics, unsaturated polyesters, rubbers and other organic polymers because of its filling, flame retardant, smoke suppression and non-toxic and harmless functions. flame retardant filler. Flame retardant mechanism of aluminum hydroxide: when the temperature exceeds 200 °C, aluminum hydroxide begins to decompose endothermically and releases three crystal waters, and its decomposition rate is the largest at about 250 °C.
This reaction is a strong endothermic reaction, thereby inhibiting the rise of the polymer temperature, reducing its decomposition rate, and only producing water vapor, without generating toxic and harmful gases.
3. Preparation of alumina powder/ceramic.
Hydrated alumina can be calcined at high temperature to obtain α-Al2O3, which has high thermochemical stability, thermal strength, creep resistance, dielectric properties and low thermal expansion coefficient. It is usually used to prepare alumina ceramics, and can also be used as a Functional additives, widely used in various industries.
During ceramic synthesis, aluminum hydroxide activates and controls the crystallization process, thereby achieving controlled phase formation of the composite. By regulating the preparation process of the boehmite precursor, the microstructure and properties of the final product alumina can be controlled, which has also become one of the research hotspots in the preparation of nano-alumina.
4. As catalyst/drug carrier.
Due to the usually incomplete crystallinity, hydrated alumina will have a certain porosity and a large comparative area. During the preparation process, different specific surface areas, pore volumes and pore structures can be prepared by controlling the temperature, concentration and pH of the reactants. And the target product of the crystal structure can be effectively used as a catalyst carrier for the hydrogenation of unsaturated carbonyl compounds, the preparation of fullerenes, and the like.
Because it is non-toxic and harmless, and can neutralize gastric acid, it can also be used as a drug carrier to adsorb antigens on the surface, so that it can be slowly released to prolong the effect of drugs.
5. As a lithium battery separator material.
The many properties of nano-boehmite make it unique in the industrial application of lithium battery separators. Excellent thermal conductivity and flame retardancy can effectively solve the problem of thermal conductivity of lithium battery separators and avoid spontaneous combustion or even explosion of batteries; good hydrophobicity is conducive to improving the safety and stability of batteries; its low hardness is conducive to reducing machining costs . It is worth mentioning that boehmite has good compatibility with organic substances, so it has become a hot spot to blend boehmite with organic substances and apply it to lithium battery separator materials.
6. Other apps.
Aluminum hydroxide is mainly composed of Al(OH)4- in water, which can precipitate toxic heavy metals in sewage by co-precipitation and then filter to achieve the effect of water purification. The colloids, suspended solids, dyes, organics, etc. in it are adsorbed on the surface.
Because aluminum hydroxide can be produced on a large scale, the raw materials are sufficient, the product purity is high, and it is easily soluble in acid and alkali. Therefore, aluminum hydroxide is an important raw material for the preparation of aluminum salts, such as barium aluminate, aluminum sulfate, etc.
When pseudo-boehmite is used as a binder in the catalyst molding process, it can provide catalysts with high mechanical resistance and larger particle sizes, thereby simplifying their use in packed reactors. Pseudo-boehmite is also commonly used to prepare γ-Al2O3 coatings, which can increase the specific surface area of the carrier and help the active components to be effectively and uniformly distributed in the carrier. It is one of the most commonly used coating materials at present.
When preparing phosphorus-aluminum molecular sieves and heteroatom phosphorus-aluminum series molecular sieves, it is best to add oxygen sources when adding phosphorus sources and aluminum sources; in addition, the mixture before the reaction should be uniformly dispersed, and it is best to add aluminum that can be dissolved in an acidic solution. source. Hydrated alumina can not only provide an oxygen source, but also can mix and disperse the reactants uniformly, so hydrated alumina is usually preferred as the aluminum source.
