Chromium(VI) Oxide

Chromium trioxide chemistry:

dark red orthorhombic crystal or purple-red flake. Soluble in water, alcohol, sulfuric acid and ether, insoluble in acetone.

Uses:

Used in electroplating, high purity metal chromium, dyes, synthetic rubber and grease refining, etc.

Chromium trioxide is the main raw material for electroplating chromium. In the production of chrome plating, the chromic anhydride content varies greatly, between 50 and 500 g/L, mainly controlling the appropriate temperature and current density, and can obtain a bright coating on the smooth plated parts, and its solution can also It is used as a passivation film for zinc plating to improve its protective properties.

It is mainly used in the electroplating industry. It is used as a raw material for chrome plating of bicycles, sewing machines, watches, meters, flashlights, and daily-use hardware. It is also used to make high-purity metal chromium. It is a raw material for the production of chrome oxide green and zinc chrome yellow; it is also a raw material for producing low-temperature shift catalysts, high-temperature shift catalysts and high-pressure methanol synthesis catalysts. Wool fabrics are used as mordants when dyed and used as oxidants in the printing and dyeing industry. In addition, it is also used for wood preservation.

production method  :

The sulfuric acid method adds a sodium dichromate solution (70 ° Bé) and 98% sulfuric acid to a reactor equipped with a stirring device, and the mixture is stirred and mixed, and heated by direct fire to form a chromic anhydride and sodium hydrogen sulfate. Sulfuric acid is added at about 102% of the theoretical amount. The reaction end temperature should be controlled at 200-205 °C. When the materials are completely melted, the heating and stirring are stopped. The material is allowed to stand for stratification. The lighter sodium hydrogen sulfate floats on the upper layer, and the heavier The molten chromic acid anhydride is discharged from the bottom valve of the reactor, and is cooled and solidified by a rotary filming machine to obtain a finished chromic anhydride. Its Na2Cr2O7+2H2SO4→2CrO3+2NaHSO4+H2O molten sodium hydrogen sulphate contains a small amount of chromic anhydride, which can be solidified to be recovered when cooled. The sodium hydrogen sulphate melt is directly injected into the water (pay attention to safety, prevent spillage), dissolve into concentration It is a solution of 40 to 42 ° Bé for the production of basic chromium sulfate.