Catalytic equilibration to increase the relative mole fraction of CF3CHCI, CF3CHCI2 or CF3CF2H in a composition

摘要

A method is disclosed for increasing in a composition the mole fraction of a compound selected from the group CF₃CHCl₂, CF₃CHF₂ and CF₃CHClF relative to the total mole fraction of the other two compounds of the group. The method comprises (a) providing a gaseous composition comprising at least one compound of said group provided that (i) if the selected compound is either CF₃CHCl₂ or CF₃CHF₂, said gaseous composition comprises CF₃CHFCl and the mole fraction of the selected compound relative to the other two compounds in said gaseous composition is less than its equilibrium amount at 50° C., and (ii) if the selected compound is CF₃CHFCl, said gaseous composition comprises both CF₃CHCl₂ and CF₃CHF₂ and the mole fraction of the selected compound relative to the other two compounds in said gaseous composition is less than its equilibrium amount at 500° C.; (b) contacting said gaseous composition with a catalyst selected from the group of catalysts consisting of catalysts comprising chromium as an oxide, as a halide or as a halided oxide, in a valence state of three to six, and supported catalysts containing at least one metal selected from cobalt, copper, iron, manganese, nickel and zinc for a time sufficient to provide substantial equilibrium between the three compounds having said formula; and (c) providing during said catalyst contact a temperature within the range of about 50° C. to 500° C. at which the mole fraction of the selected compound relative to the other two compounds increases.