Cyclic operation for the catalytic dehydrogenation of normally gaseous hydrocarbons

Claim 1

IN THE PROCESS FOR THE PRODUCTION OF LESS SATURATED HYDROCARBONS FROM MORE SATURATED HYDROCARBONS HAVING 3 TO 5 CARBON ATOMS BY CONTACT WITH CHROMIA ON ALUMINA CATALYST AT DEHYDROGENATION CONDITIONS IN CYCLIC OPERATION PROVIDING FIXED ON-STREAM AND REGERNERATION PERIODS IN A BATTERY OF REACTION ZONES OPERATING WITHIN SAID CYCLE, AND WHEREIN AT LEAST ONE OF SAID REACTION ZONES IS REMOVED FROM SAID CYCLE AND CATALYST THEREIN TREATED WITH AN OXIDIZING ATMOSPHERE FOR AT LEAST 2 HOURS AND NO MORE THAN 12 HOURS AT A TEMPERATURE OF MORE THAN 1100*F. AND NO MORE THAN 1500*F. AND EFFECTING THEREBY AN ACTIVATION OF SAID TREATED CATALYST OVER AN ABOVE THE ACTIVITY OF SUCH CATALYST AFTER STANDARD REGERATION, THE IMPROVEMENT WHICH COMPRISES RETURNING SAID ZONE CONTAINING SAID TREATED CATALYST TO SAID CYCLIC OPERATIONS UNDER CONDITIONS OF REDUCED SEVERITY INCLUDING INTRODUCTION OF CHARGE DURING SAID ON-STREAM PERIOD AT A SPACE VELOCITY OF AT LEAST DOUBLE NORMAL SPACE VELOCITY FOR AT LEAST THE FIRST HALF OF SAID ON-STREAM PERIOD, AND CONTINUING OPERATION OF SAID RETURNED ZONE AT SAID CONDITIONS OF REDUCED SEVERITY UNTIL SAID RETURNED ZONE IS IN SUBSTANTIALLY HEAT BALANCED OPERATION WITH THE OTHER CYCLING REACTION ZONES IN SAID BATTERY.