Dehydrogenation of hydrocarbons

Claim 1

A PROCESS FOR THE DEHYDROGENATION OF AN ALIPHATIC PARAFFIN HYDROCARBON FEED CONTAINING 3 TO 5 CARBON ATOMS PER MOLECULE TO DIOLEFIN PRODUCT, WHICH COMPRISES CONTACTING SAID HYDROCARBON FEED IN A PRIMARY DEHYDROGENATION ZONE WITH A DEHYDROGENATION CATALYST AT A TEMPERATURE OF FROM ABOUT 1000* TO 1200*F. AND A PRESSURE OF FROM ABOUT 5 TO 20 INCHES HG ABSOLUTE, THEREBY CONVERTING AN APPRECIABLE PORTION OF SAID HYDROCARBON FEED TO DIOLEFIN PRODUCT, MIXING THE DIOLEFIN-CONTAINING HYDROCARBON EFFLUENT FROM SAID DEHYDROGENATION ZONE WITH FROM ABOUT 1 TO 10 VOLUMES OF SUPERHEATED STEAM PER VOLUME OF HYDROCARBON, AND THEREAFTER CONTACTING THE RESULTING MIXTURE IN A SECONDARY DEHYDROGENATION ZONE WITH A WATER GAS-ACTIVE DEHYDROGENATION CATALYST AT A TEMPERATURE OF FROM ABOUT 1050* TO 1300*F. AND AT A PRESSURE SUBSTANTIALLY THE SAME AS THAT EMPLOYED IN THE PRIMARY DEHYDROGENATION ZONE, AND RECOVERING DIOLEFIN PRODUCT FROM THE EFFLUENT FROM SAID SECONDARY ZONE.