Separate recycle of regenerated acid and of isoparaffin from HF catalyst regeneration zone

Abstract

An improved process for the hydrogen fluoride catalyzed alkylation of isoparaffins with olefins wherein better utilization of internal streams is achieved. Isoparaffins used as a stripping medium in the catalyst regeneration zone are reclaimed, free of a hydrogen fluoride phase, and are utilized as recycle isoparaffins to improve the quality of the alkylate product.

We claim as our invention: 
     
       1. An alkylation process comprising: (a) contacting a feed comprising an olefin and an isoparaffin with hydrogen fluoride alkylation catalyst at alkylation reaction conditions in a reaction zone;   (b) separating a reaction zone effluent into a hydrocarbon phase and a catalyst phase;   (c) returning a first portion of said catalyst phase to said reaction zone;   (d) passing a second portion of said catalyst phase to a catalyst regeneration zone to remove tar and constant boiling mixture of water and hydrogen fluoride from said .[.acid.]. .Iadd.catalyst .Iaddend.phase;   (e) passing said hydrocarbon phase to a separation zone to separate unreacted isoparaffin and to withdraw an alkylate product;   (f) mixing said unreacted isoparaffin from step (e) with said feed prior to introducing said feed into said reaction zone;   (g) separating a mixture of regenerated acid and isoparaffin from said catalyst regeneration zone;   (h) condensing said mixture into regenerated acid and isoparaffin .Iadd.substantially free of hydrogen fluoride.Iaddend.; and,   (i) recycling said regenerated acid to said reaction zone .[.in.]. .Iadd.of .Iaddend.step (a) and mixing said isoparaffin from step (h) with said feed .[.in step (a)..]. .Iadd.prior to introducing said feed into said reaction zone. .Iaddend. .[.2. The process of claim 1 further characterized in that said isoparaffin in step (h) is substantially free of a hydrogen   
     
     
        fluoride..]. 3. An alkylation process comprising: (a) contacting a feed comprising an olefin and an isoparaffin with hydrogen fluoride alkylation catalyst at alkylation reaction conditions in a reaction zone;   (b) separating a reaction zone effluent into a hydrocarbon phase and a catalyst phase;   (c) returning a first portion of said catalyst phase to said reaction zone;   (d) passing a second portion of said catalyst phase to a catalyst regeneration zone to remove tar and constant boiling mixture of water and hydrogen fluoride from said .[.acid.]. .Iadd.catalyst phase;   (e) passing said hydrocarbon phase to a separation zone to separate unreacted isoparaffin and to withdraw an alkylate product;   (f) mixing said unreacted isoparaffin from step (e) with said feed prior to introducing said feed into said reaction zone;   (g) separating regenerated acid catalyst from said catalyst regeneration zone and recycling said regenerated acid catalyst to said reaction zone .[.in.]. .Iadd.of .Iaddend.step (a); and,   (h) separating isoparaffin .Iadd.substantially free of hydrogen fluoride .Iaddend.from .Iadd.said .Iaddend.catalyst regeneration zone and mixing said separated isoparaffin with said feed .[.in step (a)..]. .Iadd.prior to introducing said feed into said reaction zone.Iaddend.. .[.4. The process of claim 3 further characterized in that said feed comprises isobutane and an olefin having 3 to 4 carbon atoms per molecule..]. .[.5. The process of claim 3 further characterized in that said hydrogen fluoride alkylation catalyst is maintained between about 80 and 90 weight percent hydrogen fluoride..].