Preparation method of perfluoropropane

Abstract

The invention discloses a preparation method of perfluoropropane. The preparation method sequentially comprises the following steps: (1) electrolyzing potassium bifluoride to obtain a mixed fluorine gas, and sequentially carrying out dust extraction, condensation and adsorption treatments on the mixed fluorine gas to purify the mixed fluorine gas to raw material fluoride; (2) pressurizing the raw material fluoride and uniformly mixing the raw material fluoride with an inert gas to obtain a mixed gas; (3) introducing the mixed gas into a reactor filled with cobaltous fluoride to react to obtain cobaltic oxide; (4) carrying out purging and vacuumizing replacement treatments on the reactor and related pipelines and pipe fittings after the reaction; (5) introducing hexafluoropropylene into the reactor to react with the cobaltic oxide to obtain perfluoropropane containing impurities; (6) cooling and adsorbing the perfluoropropane; and (7) introducing the perfluoropropane into a rectifying column through a compressor to be rectified. By adopting the preparation method disclosed by the invention, the corrosion of impurities on the reactor can be reduced, such unfavorable side reactions as hexafluoropropylene pyrolysis, self polymerization, addition, and the like, are inhibited, and perfluoropropane with high purity is prepared.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a preparation method of octafluoropropane. Background technique [0002] Octafluoropropane is often used as an etching or cleaning gas in the process of preparing semiconductor devices. There are multiple methods for the direct preparation of octafluoropropane using hexafluoropropylene as a raw material: [0003] Japanese patent JP-B-62-61572 pointed out that a direct fluorination reaction between hexafluoropropylene and fluorine gas was used to prepare octafluoropropane; Japanese patent JP-B-1-45455 pointed out that in the presence of a catalyst, hexafluoropropylene React with fluorine to prepare octafluoropropane; Japanese patent JP-B-62-54777 pointed out that hexafluoropropylene was reacted with high-order metal fluorides to prepare octafluoropropane; Japanese patent JP-B-62-61682 pointed out that, In the case of dilution with inert gas and reaction product gas, react hexafl...

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Problems solved by technology

[0004] However, in the above method, tetrafluoromethane (CF 4 ) and hexafluoroethane (C 2 f 6 ), and addition yields C 4 f 8 and C 6 f 12 , and cycloaddition produces by-products such as 4 rings. At the same time, the fluorinating agent (advanced metal fluoride) is not treated in depth, which reduces the selectivity of the target product and the yield of octafluoropropane

In addition, some compounds in the impurities are difficult to separate by rectification, so it is almost impossible to obtain high-purity octafluoropropane

In particular, in the implementation process of the above method, the feasibility of the method is demonstrated experimentally, and the industrial production process is not mentioned.

Moreover, these methods are carried out at relatively high temperatures, and the diluent hydrogen fluoride (HF) added to the reactants during the reaction is very corrosive to the equipment. Therefore, the requirements for the material of the equipment are also very high, which aggravates the industrialization of this product. The cost of equipment seriously restricts the industrial production of octafluoropropane

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