Method for preparing hexafluorobutadiene

Abstract

The invention discloses a method for preparing hexafluorobutadiene. The method comprises the following steps: carrying out a hydrogenation dechlorination dimerization reaction on 1,1-dichloro-1,2,2-trifluoroethane or 1,2-dichloro-1,1,2-trifluoroethane on a supported metal catalyst in H2 atmosphere, separating out a target product hexafluorobutadiene, carrying out gas phase thermal cracking on an intermediate hydroflurochlorobutane to remove HCl in order to prepare hexafluorobutadiene, filtering the product generated after above reactions, washing the filtered product with an alkali, washing the washed product with water, drying the product, compressing, and carrying out rectifying purification to obtain the highly pure hexafluorobutadiene. The method for preparing hexafluorobutadiene overcomes the disadvantages of long operating period, low unit volume output and large device investment of present technologies, and has the advantages of high yield, few steps, easy industrialization, realization of production of the highly pure hexafluorobutadiene through selection of reactants and control of reaction conditions, simple process, cheap and easily available raw material, low cost, facilitation of industrial production, continuous production, and great improvement of the unit device productivity.

Description

technical field

[0001] The invention belongs to the technical field of chlorofluoroolefin preparation, and the method is a method for preparing hexafluorobutadiene through catalytic hydrogenation dechlorination dimerization. Background technique

[0002] Hexafluorobutadiene (C 4 f 6 , also known as perfluorobutadiene), its main application is the plasma etching processing medium of semiconductor products. Compared with traditional plasma etching gas CF 4 、C 2 f 6 、C 3 f 8 , c-C 4 f 8 and NF 3 Compared to C 4 f 6 It has the characteristics of faster etch rate, high etch selectivity and high aspect ratio. At present, hexafluorobutadiene is mainly used for precision etching of critical dimensions (accuracy up to 100nm), and has better selectivity than other etching gases. in C 4 f 6 In the system of etching gas, the active radical CF x The density of (x=1~3) is lower than that of other perfluorocarbons as etching gas systems, and CF with low etching activity is ...