Application and synthesis methods of lithium chloride

Application and synthesis methods of lithium chloride

Physical and chemical properties

Lithium chloride is a white powder or small particle at room temperature, which is the most easily deliquescent salt among all known salts; The taste is very salty, like chlorination; When heated to a dark red color, it melts into clear liquid, and evaporates when heated to white heat. Lithium chloride has a sodium chloride type structure, and its chemical bonds are not typical ionic bonds, so it is easily soluble in water with a standard solubility of 67g/100ml of water. It is also easily soluble in organic solvents such as ethanol, acetone, and pyridine, but difficult to dissolve in ether. Therefore, when preparing alkyl lithium, if chlorohalogenated hydrocarbons are used in ether to precipitate lithium chloride, free alkyl lithium reagents can be obtained (lithium bromide and lithium iodide form adducts with alkyl lithium and act as stabilizers).

Lithium chloride can form various hydrates, and the phase diagram of LiCl-H2O clearly shows that its hydrates include several types such as LiCl · H2O, LiCl · 2H2O, LiCl · 3H2O, LiCl · 5H2O, etc. The number of crystalline water depends on the temperature of crystallization, and the lower the temperature, the higher the degree of hydration.

Lithium Li can form coordination ions with ammonia [Li (NH3) 4], so the solubility of ammonia in lithium chloride solution is much higher than in water. Like other ion chlorides, lithium chloride can also provide chloride and lithium ions in aqueous solutions, and precipitate insoluble chlorides or lithium salts with certain other ions, such as silver chloride: LiCl+AgNO3 → AgCl ↓+LiNO3.

Lithium chloride can be used in the production of artificial mineral water, refrigerants, dehumidifiers for air conditioning systems, fluxes, chemical reagents, pyrotechnic, dry batteries, lithium metal, and for gas chromatography fixation.

Application

Lithium chloride has a wide range of uses, and the production of metallic lithium by electrolysis is the field with the largest consumption of lithium chloride. The only industrial method for producing metallic lithium currently is the lithium chloride molten salt electrolysis method proposed by Guntz in 1893. Lithium metal and its alloys and compounds have extensive applications in many fields such as atomic energy industry, metallurgical industry, batteries, glass, ceramics, chemical industry, aerospace industry, etc.

In recent years, lithium chloride has been widely used in fields such as biology and medicine. In medicine, it is used to treat diabetes, genetic research, etc; Used in biology for the extraction and purification of RNA and a small amount of plasmid DNA; As a mutagen, it is widely used in industries such as food (beer), medicine, and environmental protection to select high-quality bacterial strains, cultivate high-yield strains, synthesize pharmaceutical intermediates, and genetically modify bacterial strains; In organic structure analysis, LiCl is an important cationic additive; Widely used in the production of chitin in the field of new materials; As an adsorbent and dehumidifier in air conditioners and dehumidifiers.

Preparation method: Lithium carbonate or lithium hydroxide conversion method: This method is the main industrial method for producing LiCl, and most lithium chloride in China is produced using this method. In a corrosion-resistant reactor, Li2CO3 or LiOH reacts with 30% hydrochloric acid to slightly excess hydrochloric acid, resulting in a nearly saturated LiCl solution. Add an appropriate amount of BaCl2 solution to the acidic LiCl solution to remove sulfate impurities, filter and adjust the pH value to neutral with LiOH. Then, spray boiling granulation or spray drying to obtain anhydrous lithium chloride.

Dissolve lithium carbonate in hydrochloric acid and evaporate to dryness to obtain a white powder of lithium chloride. In order to produce exceptionally pure anhydrous lithium chloride, it is necessary to refine and purify it. There are three refining methods: (1) refining through carbonate; (2) Transforming lithium fluoride into lithium chloride after precipitation; (3) Refinement is carried out using ion exchange resin. The main introduction of method (3) is as follows:

The cation exchange resin adopts Amberlite IR120 hydrogen type resin with a capacity of 100mL; The anion exchange resin uses Amberlite IRA400 chlorine resin with a capacity of 100mL. Dissolve lithium chloride in a 25% (molar fraction) methanol water mixed solvent to prepare a solution with a chloride ion concentration below 1mol/L. Alternatively, 0.5mol/L hydrochloric acid with 25% (volume fraction) methanol can be used as the eluent, which can be operated at room temperature. This method can remove difficult to remove calcium ions and 70% sulfate ions to obtain pure lithium chloride.

Solubility in water (g/100ml)

Dissolved grams per 100 milliliters of water at different temperatures (℃):

69.2g/0 ℃; 74.5g/10 ℃; 83.5g/20 ℃; 86.2g/30 ℃; 89.8g/40 ℃

98.4g/60 ℃; 112g/80 ℃; 121g/90 ℃; 128g/100 ℃

toxicity

LD50 mice (mg/kg): 990i.p; Inrates (mg/kg): 600i.p., 4.8i.v. (Wielosz)

Danger

According to GB12268-2005 and the 2008 list of hazardous chemicals, lithium chloride is not classified as a hazardous material. In the 1940s, lithium chloride was used as a substitute for table salt, but it was later discovered that lithium chloride was toxic to the body, so the application was discontinued. Lithium salts act on the central nervous system, similar to lithium carbonate, which is a medication for treating mental illnesses. chemical property

White cubic crystals or powders. Easy to dissolve due to moisture. Soluble in water, ethanol, acetone, and ammonia.

Application

It is a raw material for manufacturing welding materials, air conditioning equipment, and lithium metal. Also used for making fireworks.

Application

Used as an analytical reagent, heat exchange carrier, and also in the pharmaceutical industry

Application

Used for air conditioning, fireworks, dry batteries, and lithium metal production, as well as soldering and drying agents

Application

Anhydrous lithium chloride is mainly used as a raw material for the production of metallic lithium through molten salt electrolysis. It is also used as a welding agent for aluminum, dehumidifier for air conditioning, special cement production, and catalyst for polymer material polyphenylene sulfide.

Application

Raw materials for producing metallic lithium; Used as a welding agent for aluminum, dehumidifier for air conditioning, and special cement raw materials; Used for flames, in the battery industry for producing lithium manganese battery electrolyte

Application

Analytical reagents. Gas chromatography stationary phase (maximum operating temperature 650 ℃, solvent is water). Lithium chloride can separate polynuclear aromatic hydrocarbons with boiling points as high as 600 ℃ after calcination at 700-1000 ℃. Zinc complex alloy can be separated into zinc and chromium at 620 ℃. Mainly used as raw materials for the production of metallic lithium, as well as air conditioning dehumidifiers, bleaching powders, insecticides, lithium battery electrolytes, synthetic fibers, alloy welding agents or fluxes.

Production methods

The hydrochloric acid method adds hydrochloric acid to the reactor, and slowly adds lithium carbonate in a slightly higher theoretical amount for reaction to generate lithium chloride. After filtration, the filtrate is evaporated and concentrated to precipitate crystals, which are then cooled and rapidly filtered to produce anhydrous lithium chloride products. Its Li2CO3+2HCI → 2LiCl+H2O+CO2 ↑