Methods for dehydrogenating hydrocarbons utilizing combustion units

A method for dehydrogenating hydrocarbons, the method comprising:

• contacting a feed stream comprising one or more hydrocarbons with a particulate solid in a dehydrogenation reactor, wherein the particulate solid comprises an oxygen-carrier material, and wherein in the dehydrogenation reactor:
• the one or more hydrocarbons are dehydrogenated to form hydrogen and one or more products;
• and
• at least a portion of the hydrogen is reacted with oxygen from the oxygen-carrier material to form water and reduce the oxygen content in the oxygen-carrier material;
• passing the particulate solid from the dehydrogenation reactor to a combustion unit, wherein:
• the particulate solid moves in a generally upwards direction through the combustion unit and gases move in a generally upwards direction through the combustion unit, such that the particulate solid and gases move in a co-current flow pattern through the combustion unit;
• the combustion unit comprises a first gas inlet and a second gas inlet, the first gas inlet is beneath the second gas inlet, an oxygen-containing gas enters into the combustion unit through the first gas inlet, and a fuel enters into the combustion unit through the second gas inlet;
• in an area of the combustion unit above the first gas inlet and beneath the second gas inlet, the oxygen content in at least a portion of the oxygen-carrier material of the particulate solid increases;
• and
• in an area of the combustion unit above the second gas inlet, at least a portion of the fuel is reacted with oxygen from one or both of the oxygen-containing gas or the oxygen-carrier material of the particulate solid;
• and
• passing at least a portion of the particulate solid from the combustion unit to the dehydrogenation reactor.