Recovery of tantalum and/or niobium pentafluorides from a hydrocarbon conversion catalyst

In a hydrocarbon conversion process which comprises contacting a hydrocarbon feedstock with a substantially liquid phase acid catalyst comprising (a) a metal pentafluoride selected from the group consisting of tantalum pentafluoride, niobium pentafluoride, and mixtures thereof and (b) hydrogen fluoride, thereby forming a hydrocarbon phase and a catalyst phase, said catalyst phase having become at least partially deactivated due to the formation of catalytically less active complexes with at least a portion of the metal pentafluoride, the improvement which comprises recovering at least a portion of the metal pentafluoride component of the catalyst according to the steps comprising:

• 1. stripping at least a portion of the hydrogen fluoride from said partially deactivated catalyst,
• 2. extracting the uncomplexed metal pentafluoride from the residue of step (1) with a liquid hydrocarbon,
• 3. distilling said catalyst at a temperature ranging from about 70.degree. to about 400.degree. C in the presence of a Lewis acid selected from the group consisting of the trihalides of aluminum, the tetrahalides of titanium, zirconium, hafnium and mixtures thereof to form the metal pentahalide of the catalyst component, and
• 4. contacting the metal pentahalide formed in step (3) with hydrogen fluoride in an amount sufficient to convert at least a portion of said metal pentahalide to the corresponding metal pentafluoride, thereby recovering the metal pentafluoride component of the catalyst possessing a lower level of said catalytically less active complexes than that possessed by the metal pentafluoride component of said deactivated catalyst.