Hydrocarbon dehydrogenation process using a combination of isothermal and adiabatic dehydrogenation steps

Dehydrogenatable C2-plus feed hydrocarbons (1) are catalytically dehydrogenated by (a) passing a feed stream (1) comprising the C2-plus feed hydrocarbon through an isothermal dehydrogenation zone (3) containing dehydrogenation catalyst maintained at isothermal dehydrogenation conditions selected to convert at least 50 weight percent of the feed stream and to produce a first effluent stream (4) comprising hydrogen, unconverted C2-plus feed hydrocarbon and C2-plus product hydrocarbon; (b) passing the first effluent stream (4) and oxygen (5) through a bed of hydrogen selective oxidation catalyst to produce a second effluent stream (7) having a reduced concentration of hydrogen and an increased temperature and (c) passing the second effluent stream (7) through an adiabatic dehydrogenation zone (8) containing dehydrogenation catalyst to convert additional unconverted C2-plus feed hydrocarbon and to produce a third effluent stream (9) comprising hydrogen and C2-plus product hydrocarbon.