Patent GB-752917-A (GB)
Title: A process for effecting endothermic dehydrogenation reactions
IPC: C07C5/367
Filed: 1954-03-11
Abstract: A process for the catalytic endothermic vapour phase dehydrogenation of one or more dehydrogenatable hydrocarbons such as naphthenic hydrocarbons comprises passing a solid finely-divided dehydrogenation catalyst in a fluidized state downward through an elongated reaction zone, introducing vapours of the material to be dehydrogenated into the reaction zone at an intermediate point thereof, withdrawing a mixture of reacted vapours and recycle <PICT:0752917/IV(a)/1> gas consisting mainly of hydrogen from the top of the reaction zone, separating a recycle gas consisting mainly of hydrogen from the mixture, heating the recycle gas to a temperature higher than the average reaction temperature, introducing the larger part of the heated gas into the reaction zone near the bottom, so that the catalyst in the lower part of the reaction zone is heated and stripped of reactant vapours and the gas thereby cooled is passed upward and mixed with the feed vapours in the upper part of the reaction zone, and using a separate minor portion of the heated recycle gas to transport the heated catalyst from near the bottom of the reaction zone to near the top, so that the temperature in the reaction zone near the point of introduction of the feed vapours is below the temperature near the top and bottom of the reaction zone. In an example, a straight run gasoline fraction boiling between 113 DEG  and 228 DEG  F. is preheated in furnace 2 to a temperature approximately equal to the desired reaction temperature of 920-975 DEG  F. under a pressure of 200 pounds per square inch, a small amount of recycle gas is added and the mixture is then passed to the reactor 4.  Catalyst is withdrawn through line 5 and valve 6 and transported to the top of the reactor by a stream of hydrogen in line 7.  Grid plates 13 to 16 are provided in order to allow the catalyst to sift in a downward direction.  The main stream of hydrogen gas is heated in furnace 17 to 1150-1450 DEG  F. and passes via line 18 to the bottom of the reactor.  The vapours leaving the reactor at 910-990 DEG  F. through line 19 are cooled to separate small amounts of catalyst in tank 22, and then hydrogen sulphide is removed in unit 28.  The hydrogen is recycled.  The catalyst may contain nickel, platinum or palladium.ALSO:A process for the catalytic endothermic vapour phase dehydrogenation of one or more dehydrogenatable hydrocarbons such <PICT:0752917/III/1> as naphthenic hydrocarbons comprises passing a solid finely-divided dehydrogenation catalyts in a fluidized state downward through an elongated reaction zone, introducing vapours of the material to be dehydrogenated into the reaction zone at an intermediate point thereof, withdrawing a mixture of reacted vapours and recycle gas consisting mainly of hydrogen from the top of the reaction zone, separating a recycle gas consisting mainly of hydrogen from the mixture, heating the recycle gas to a temperature higher than the average reaction temperature, introducing the larger part of the heated gas into the reaction zone near the bottom, so that the catalyst in the lower part of the reaction zone is heated and stripped of reactant vapours and the gas thereby cooled is passed upward and mixed with the feed vapours in the upper part of the reaction zone, and using a separate minor portion of the heated recycle gas to transport the heated catalyst from near the bottom of the reaction zone to near the top, so that the temperature in the reaction zone near the point of introduction of the feed vapours is below the temperature near the top and bottom of the reaction zone. In an example, a straight run gasoline fraction boiling between 113 DEG F. and 228 DEG F. is preheated in furnace 2 to a temperature approximately equal to the desired reaction temperature of 920-975 DEG F. under a pressure of 200 pounds per square inch, a small amount of recycle gas is added and the mixture is then passed to the reactor 4.  Catalyst is withdrawn through line 5 and valve 6 and transported to the top of the reactor by a stream of hydrogen in line 7.  Grid plates 13 to 16 are provided in order to allow the catalyst to sift in a downward direction.  The main stream of hydrogen gas is heated in furnace 17 to 1150-1450 DEG F. and passes via line 18 to the bottom of the reactor.  The vapours leaving the reactor at 910-990 DEG F. through line 19 are cooled to separate small amounts of catalyst in tank 22, and then hydrogen sulphide is removed in unit 28.  The hydrogen is recycled.  The catalyst may contain nickel, platinum or palladium.