Xylene isomerization

Claim 1

A NEW USE OF THE KNOWN APPARATUS FOR SIMULTANEOUSLY ISOMERIZING XYLNES AND CONVERTING ETHYL BRNZENE TO PRODUCTS READILY SEPARABLE BY DISTILLATION FROM THE MIXTURE OF C8 AROMATICS BY CONTACTING A MIXTURE OF C8 AROMATICS AND HYDROGEN WITH A PLATINUM ON SILICA-ALUMINA CATALYST AT PRESSURE OF 175 TO 225 POUNDS PER SQUARE INCH, A TEMPERATURE OF 830 TO 900*F. AND LIQUID HOURLY SPACE VELOCITY OF 0.6 TO 1.6 LIQUID VOLUMES OF HYDROCARBON PER VOLUME OF CATALYST PER HOUR IN A LOOP COMPRISING AN ISOMERIZATION REACTOR FOR THE CONTACT AFORESAID, DISTILLATION MEANS FOR SEPARATING C8 AROMATICS FROM LOWER BOILING AND HIGHER BOILING HYDROCARBONS, MEANS TO TRANSFER HYDROCARBON EFFLUENT OF SAID ISOMERIZATION REACTOR TO SAID DISTILLATION MEANS, MIXING MEANS FOR MIXING FRESH FEED C8 AROMATICS CONTAINING XYLENE AND ETHYL BENZENE WITH C8 AROMATICS SEPARATED BY DISTILLATION MEANS, A XYLENE SEPARATOR FOR RECOVERY OF PAR XYLENE, MEANS FOR TRANSFER OF MIXED C8 AROMATICS FROM SAID MIXING MEANS TO SAID XYLENE SEPARATOR, AND MEANS TO TRANSFER C8 AROMATICS LEAN IN PARA XYLENE FROM SAID XYLENE SEPARATOR TO SAID ISOMERIZATION REACTOR; WHICH NEW USE COMPRISES CONTACTING, IN THE ISOMERIZATION REACTION OF SAID KNOWN APPARATUS, A VAPOR PHASE MIXTURE OF HYDROGEN AND SAID C8 AROMATICS LEAN IN PARA XYLENE WITH A ZEOLITE CATALYST OF THE ZSM-5 TYPE OR ZEOLITE ZSM-12 OR ZEOLITE ZSM-21 AT A TEMPERATURE OF 550 TO 900*F., A PRESSURE OF 150 TO 300 POUNDS PER SQUARE INCH AND A WEIGHT HOURLY SPACE VELOCITY WITH RESPECT TO SAID ZEOLITE ALONE BETWEEN ABOUT 1 AND ABOUT 200.