The method of anhydrous hydrogen fluoride production by catalytic decomposition of ammonium polyfluoride
A decomposition of ammonia, and ammonia ina presence of hydrogen fluoride on chromium magnesium fluoride catalystGIPH-55 has been investigated. Results showthat the conversion of ammonia in the presence of hydrogen fluoride reaches 30% at residence time about 15-20 s at the temperature about 550°С. Reaction rate constants have been calculated.Тhe recycle of ammonia is to be used for commercial development. Obtained results can become a basis for an industrial technology of anhydrous hydrogen fluoride production from ammonium polyfluoride, which can be obtained by the amination of the hexafluorosilicic acid, one of the main byproducts of phosphate fertilizersproduction.
Anhydrous hydrogen fluoride (AHF) is widely used in chemical industry, including, in a production of uranium fluorides in the nuclear fuel cycle, fluoropolymers, refrigerants, etc. (1-3).
Aconventional industrial method for AHF production is a sulfuric acid decomposition of natural mineral fluorspar CaF2. The process is performed in a rotating reactor heated to a temperature of about 300 °C, after that hydrogen fluoride is removed from outlet gas (4-6). The production of AHF requires high quality fluorspar, which contains more than95% of basic substance and less than 1.5% of silica. Assets of this natural strategic raw material in the world arelimited.Therefore, it is important to explorenew methods of AHF production from otherfluorine-containing raw materials.
It is known thatthe main source of phosphorus in phosphate fertilizer production is natural mineral apatite Ca5(PO4)3X2, where X typically is fluorine with up to 7% content, or 3–4 % on average. The global production of phosphate fertilizers is 100–150 million tons per year in terms of phosphorus pentoxide ...