Process for the isomerization of benzene containing feed streams

A process for the hydrogenation and decyclization of benzene and the isomerization of C4 to C6 paraffins from a hydrocarbon feedstream having a concentration of benzene that fluctuates between above and below 5 wt %, said method comprising:

• a) passing at least a portion of a feedstream comprising benzene and C.sub.4 to C.sub.6 paraffins and a hydrogen containing stream to a benzene saturation zone and into contact with a benzene saturation catalyst at benzene saturation conditions to produce an intermediate stream containing cyclohexane;
• b) passing said intermediate stream to an isomerization zone inlet and contacting said intermediate stream with and isomerization catalyst at isomerization conditions in said isomerization zone to decyclize said cyclohexane, increase the isoparaffin content of said intermediate stream and produce an isomerization zone output stream;
• c) passing at least a portion of said isomerization zone output stream into indirect heat exchange with a portion of the feedstream entering said saturation zone;
• d) passing said isomerization zone output stream to a separator to recover hydrogen and an isomerization zone effluent stream and recycling at least a portion of said hydrogen to said saturation zone;
• e) maintaining the temperature at the inlet of said isomerization zone below 350.degree. F. by charging a portion of said feedstream directly to said saturation zone without said intermediate heat exchange as long as said benzene concentration in said feedstream is below 5 wt % and passing a quench stream comprising at least a portion of one of said feedstream or said isomerization zone effluent stream directly into said isomerization zone when the benzene content of said feedstream exceeds 5 wt %.