Process for the dehydrogenation of paraffinic hydrocarbons

A process for the dehydrogenation of a paraffinic dehydrogenatable hydrocarbon in N stages wherein N.gtoreq.2 with reheat between each stage which process comprises:

• (a) contacting said paraffinic dehydrogenatable hydrocarbon and hydrogen with a dehydrogenation catalyst at dehydrogenation conditions including a temperature, T.sub.1, in a first dehydrogenation stage wherein the endothermic dehydrogenation reaction reduces the temperature of the resulting first hydrocarbon stream containing hydrogen, dehydrogenated hydrocarbon compounds and unreacted dehydrogenatable hydrocarbon;
• (b) mixing the effluent hydrocarbon stream from the immediate preceding stage with a portion of a hereinafter produced hydrogen-rich gaseous recycle stream having a temperature, T.sub.2, which is greater than T.sub.1 to thereby increase the temperature of the resulting mixture to a temperature proximate T.sub.1 ;
• (c) contacting the resulting heated mixture produced in the preceding step with a dehydrogenation catalyst at dehydrogenation conditions in the next subsequent dehydrogenation stage to produce an effluent hydrocarbon stream containing hydrogen, dehydrogenated hydrocarbon compounds and unreacted dehydrogenatable hydrocarbons;
• (d) repeating steps (b) and (c), N-1 times;
• (e) condensing at least a portion of the effluent stream containing dehydrogenated hydrocarbon compounds recovered from the N.sup.th stage to produce a liquid hydrocarbon stream comprising dehydrogenated hydrocarbon compounds and a separated hydrogen-rich gaseous stream;
• (f) heating at least a portion of said separated hydrogen-rich gaseous stream to produce N-1 heated hydrogen-rich gaseous recycle streams for each dehydrogenation stage subsequent to said first dehydrogenation stage and recycling each heated hydrogen-rich gaseous recycle stream to its designated stage;
• and
• (g) recovering a dehydrogenated hydrocarbon product stream from step (e).