Maintaining effective molar ratio of HF to metal pentafluoride in a hydrocarbon conversion process

Claim 1

In a hydrocarbon conversion process which comprises 1. converting 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, such that the reaction effluent from said process is separated in a settling zone into a hydrocarbon phase containing minor amounts of metal pentafluoride and a catalyst phase; 2. removing at least a portion of the metal pentafluoride from the hydrocarbon phase by contact with a solvent comprising substantially anhydrous liquid hydrogen fluoride, thereby forming a hydrocarbon phase depleted in metal pentafluoride and an extract phase containing hydrogen fluoride and the metal pentafluoride thus removed, the molar ratio of hydrogen fluoride to metal pentafluoride in said extract phase being greater than that desired in said hydrocarbon conversion process, the improvement which comprises maintaining the molar ratio of hydrogen fluoride to metal pentafluoride in the extract phase at the level desired in said hydrocarbon conversion process while inhibiting the deactivation of the catalyst phase by: 3. combining at least a portion of said extract phase with said catalyst phase in said settling zone to form a catalyst mixture and stripping said mixture with a gas containing molecular hydrogen for a time sufficient to reduce the molar ratio of hydrogen fluoride to metal pentafluoride in said catalyst mixture to the level desired in said hydrocarbon converting step (1); and 4. passing at least a portion of said stripped catalyst mixture from step (3) to said converting step (1).