A method for the preparation of rhenium hexafluoride, the method by optimizing the conditions of the fluorination reaction, so that the product is mainly rhenium hexafluoride and rhenium heptafluoride; and then regulate the conditions of the reduction reaction, so that the rhenium heptafluoride is reduced to rhenium hexafluoride. The method has a concise process flow and is characterized by safety and economy, high synthetic conversion and low impurities.
(1) 5g of rhenium powder is spread flat in reactor , and nitrogen trifluoride gas with an air velocity of 20h-1~30h-1 is introduced, and the fluorination reaction is carried out at a reaction temperature of 400~430 and a reaction pressure of 0.15MPa~0.2MPa, and the product is collected by condenser , and the nitrogen and nitrogen trifluoride in the product are excluded by an evacuation valve. and other gases are excluded through the venting valve, and rhenium hexafluoride and rhenium heptafluoride in the product are liquefied into mixed solids;
(2) the mixed solids collected in condenser were first heated and sublimated into mixed gases, and then passed into the reactor equipped with 10g rhenium powder at an air velocity of 5h-1~10h-1, and the reduction reaction was carried out at a reaction temperature of 100~120 and a reaction pressure of 0.1MPa~0.3MPa, and condenser was employed to The product was collected, and the purity of rhenium hexafluoride gas collected in condenser II was 91.2 wt%.