High pure hexafluoropropylene oxide preparation method using extraction rectification

Abstract

The invention relates to a method for preparing high-purity hexafluoropropylene oxide by extraction and rectification. The method comprises the following steps: selecting epoxy chloropropane as an extracting agent, wherein the mass ratio of the extracting agent to HFPO-HFP mixture feed is controlled between (1-200): 1; introducing the HFPO-HFP mixture into an extraction rectifying tower, spraying the epoxy chloropropane from the tower top, and separating HFPO from the tower top to obtain HFPO with purity over 99 percent; and discharging HFP and the epoxy chloropropane from the bottom of the extraction rectifying tower to be pressed into a reclaiming tower once again, separating the HFP from the top of the reclaiming tower, and discharging the epoxy chloropropane from the bottom of the reclaiming tower to be pumped once again to return a spraying port on the top of the extraction rectifying tower for cycle use. The method selects the epoxy chloropropane as the extracting agent to make relative volatility of the HFPO and the HFP reach 1.5 to 3.7, so that the HFPO and the HFP can be well separated; meanwhile, the number of column plates required for rectification can be reduced, and investment cost can be reduced.

Description

technical field [0001] The invention belongs to the field of preparation of fluorine-containing fine chemicals, and in particular relates to a method for preparing high-purity hexafluoroepoxypropylene by means of extraction and rectification. Background technique [0002] Hexafluoropropylene oxide (HFPO for short), also known as perfluoropropylene oxide, is an important intermediate in the organic fluorine industry and a key raw material for the synthesis of high-performance fluorine chemical products. Due to its unique ring structure, it has a high degree of chemical activity and can be used to prepare intermediates of various fluorine-containing organic compounds and fluorine-containing fine chemicals. For example, self-polymerization can occur in the presence of a catalyst; under the catalysis of Lewis acid, it can Rearrangement into hexafluoroacetone; addition reaction with sultone and other acyl fluorides, followed by cracking to prepare perfluoroalkyl vinyl ether; nucl...

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Problems solved by technology

However, this method will lead to the occurrence of a large number of side reactions. Although the conversion rate is improved, the selectivity is greatly reduced, thereby greatly increasing the unit consumption of finished products; The pressure will have an impact on the environment; the third is that the operating pressure of the system will rise rapidly due to the addition of excessive oxygen to the system, which will increase the unsafe operation and the instability of control

[0007] If the above problems are to be solved, the occurrence of side reactions is reduced, and the unit cost of the product is reduced, that is, the amount of oxygen input needs to be reduced, thereby reducing the conversion rate and improving the selectivity, but this will bring about how to treat the generated HFPO and unreacted HFP the problem of separation

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