Lithium aluminum hydride is a white or off-white porous microcrystalline powder product, soluble in tetrahydrofuran, ether and dimethyl solvent, slightly soluble in dibutyl ether, almost insoluble in dioxane and hydrocarbons. Lithium aluminum hydride is stable in dry air, and undergoes violent hydrolysis in humid air, releasing a large amount of H2 and burning it. It can reduce ketones, aldehydes, acids, esters, anhydrides, quinones, etc. to alcohols, and reduce halogenated hydrocarbons to hydrocarbons. Nitriles are reduced to primary amines. Lithium aluminum hydride is widely used in medicine, pesticides, spices, dyes and other industries due to its excellent reducibility, and is used as a reducing agent in other organic synthesis.
At the same time, lithium aluminum hydride will release a large amount of heat energy when it is burned, and it is also used as an additive for missiles and launch vehicle fuels. This product has high technical content and large profit margins, but it involves high temperature, flammability, explosion and other issues in the production process, and the control requirements for process parameters are very strict, so only a small number of domestic manufacturers are carrying out small-scale production. mass production
The traditional preparation method of lithium aluminum hydride
The basic preparation reaction equation: 4LiH+AlCl3→LiAlH4+3LiCl. Among them, the preparation of lithium hydride is relatively simple, and metal lithium and hydrogen are carried out in a reactor.
However, the preparation of lithium aluminum hydride is somewhat troublesome, because in the preparation process of lithium aluminum hydride, there is an induction period, that is, a sudden explosion will occur during the reaction, making the reaction difficult to control. A small amount of aluminum bromide is added in advance, and the reaction can proceed smoothly at the beginning, which is more suitable for preparing a small amount of lithium aluminum hydride in the laboratory.
According to market demand and customer requirements, Wuxi ZhangHua Machinery Co., Ltd. has carried out a lot of design and development work, and finally successfully developed a cylinder cone reaction filter drying multifunctional machine, and successfully applied for a patent (patent number: ZL201721560677.6.), realized The major improvement in equipment technical performance, from structural design to application, closely follows the corresponding regulatory requirements of the fine chemical industry, and has been maturely applied in many fine chemical companies.
Lithium aluminum hydride special fine chemical products preparation cylinder cone multifunctional filter washing and drying machine production process
The lithium aluminum hydride product prepared by the fully enclosed reaction filter washing and drying machine has high content, mild reaction conditions and higher safety. The specific production process steps are:
(1) Under the condition of reflux, add diethyl ether and lithium hydride to the fully enclosed reaction filter washing and drying machine, after stirring evenly, add anhydrous aluminum trichloride, and continue stirring;
(2) The temperature is raised to 20-30°C and reacted for 5-8 hours;
(3) Totally closed reaction, filtering and washing, distilling off diethyl ether to obtain the finished product of lithium aluminum hydride.
(1) Fully enclosed system with good operating environment, especially suitable for handling toxic, flammable and explosive dangerous products and delicious food, biological products and pharmaceuticals that are not allowed to be polluted.
(2) It can be used for the three operations of reaction, filtration, and drying, so that the functions of the three unit equipment can be completed on this one equipment, so that the equipment cost, floor area, labor intensity, energy consumption, etc. are greatly reduced.
(3) It can be concentrated and filtered. Especially when it is necessary to wash the material, the material can be concentrated first, washed thoroughly in the suspension state, and finally press-filtered, which can reduce the handling of the material, reduce waste, and do not need to be repulped during washing. The product quality is very high.
(4) One machine is multi-purpose, and various operations such as reaction, extraction, filtration, repeated filtration, washing, and drying can be completed in one machine, and the finished product can be directly obtained.
(5) The operating flexibility is large, and the operating cycle can be adjusted by adjusting the filter pressure difference, rotating speed, screw extrusion lead, etc., so as to adapt to changes in process conditions.