Patent GB-784414-A (GB)
Title: Method of apparatus for carrying out endothermic chemical reactions
IPC: B01J8/32
Filed: 1954-12-03
Abstract: <PICT:0784414/III/1> An endothermic hydrocarbon conversion process is carried out by contacting vaporous reactants with a fluidized bed of a mixture of a major proportion of finely-divided solid catalyst and a minor proportion of inert heat transfer solids of greater density and larger average particle size than the catalyst in a reaction zone 13, discharging the mixture into a settling zone 17, where separation takes place by means of a gas entering at 18, withdrawing a mixture of solids containing a major proportion of inert solids at 19, treating the mixture with oxygencontaining gas to burn off carbonaceous deposits, and returning the mixture to the upper part of the fluidized bed in the reaction zone.  In the hydroforming of naphthas, the feed and hot recycle gas are introduced at 11 and products leave at 16.  The mixture of catalyst and inert solid withdrawn at 19 is led to stripper 20 and treated with steam or an inert gas introduced at 21; after stripping, the mixture is carried by steam, flue gas, air, or a mixture of these gases, through line 25 to regenerator 27; additional air may be supplied direct to the regenerator.  The regenerator may also be provided with a settling zone.  In some cases, regeneration may take place in line 25, regenerator 27 then being replaced by a separator.  Regenerated solids, after stripping and treatment with hydrogen, if desired, pass through U-bend line 33 back to the reactor.  The density of the solid material, as measured by the difference of pressure between 36 and 37, may be used to control the valve in the gas inlet line 18 and so maintain the desired ratio of inert solids to catalyst in the circulating solids.  The settling vessel may be in the form of an inverted cone or a plurality of frustums of cones.  In a modified form of apparatus, Fig. 2 (not shown), the separate stripper is omitted and a U-shaped transfer pipe leads from the bottom of the settling zone to a storage vessel for the inert solids.  This storage vessel is provided with gas inlet means and also with a control valve in the gas outlet, which valve operates in response to a variation in the density of the circulating solids in order to transfer inert solids to or from the storage vessel.  For hydroforming, suitable catalysts are platinum, palladium, or oxides of molybdenum, chromium, vanadium, or tungsten, supported on activated alumina or zinc aluminate spinel; silica, calcium oxide, ceria, potassia, or zirconia may also be included in the catalyst.  Suitable inert solids are corundum, mullite, fused alumina, and fused silica.  The ratio by weight of catalyst to inert solids in the reaction zone is preferably not less than 5 : 1 and the ratio of inert solids to catalyst withdrawn from the settling zone preferably not less than 1 : 1. Naphthas boiling in the range 125-450 DEG  F. may be hydroformed in the presence of hydrogen-rich gas at temperatures of 850-1050 DEG  F. and pressures of 50-1000 lbs. per square inch.  When using molybdenum oxide on alumina catalyst, a small water partial pressure is preferably maintained in the reaction zone.  The regenerator is operated at the same pressure as the reactor and at 1000-1200 DEG  F. The catalyst may remain in the reactor for 1-4 hours and the inert solids for 3-20 minutes.  Specification 741,062 is referred to.ALSO:An endothermic hydrocarbon conversion process is carried out by contacting vaporous reactants with a fluidized bed of a mixture of a major proportion of finely divided solid catalyst and a minor proportion of inert heat transfer solids of greater density and larger average particle size than the catalyst in a reaction zone 13, discharging the mixture into a settling zone <PICT:0784414/IV (a)/1> 17, where separation takes place by means of a gas entering at 18, withdrawing a mixture of solids containing a major proportion of inert solids at 19, treating the mixture with oxygencontaining gas to burn off carbonaceous deposits, and returning the mixture to the upper part of the fluidized bed in the reaction zone.  In the hydroforming of naphthas, the feed and hot recycle gas are introduced at 11 and products leave at 16.  The mixture of catalyst and inert solid withdrawn at 19 is led to stripper 20 and treated with steam or an inert gas introduced at 21; after stripping, the mixture is carried by steam, flue gas, air, or a mixture of these gases, through line 25 to regenerator 27; additional air may be supplied direct to the regenerator.  The regenerator may also be provided with a settling zone.  In some cases, regeneration may take place in line 25, regenerator 27 then being replaced by a separator.  Regenerated solids, after stripping and treatment with hydrogen if desired, pass through U-bend line 33 back to the reactor.  The density of the solid material, as measured by the difference of pressure between 36 and 37, may be used to control the valve in the gas inlet line 18 and so maintain the desired ratio of inert solids to catalyst in the circulating solids.  The settling vessel may be in the form of an inverted cone or a plurality of frustums of cones.  In a modified form of apparatus, Fig. 2 (not shown), the separate stripper is omitted and a U-shaped transfer pipe leads from the bottom of the settling zone to a storage vessel for the inert solids.  This storage vessel is provided with gas inlet means and also with a control valve in the gas outlet, which valve operates in response to a variation in the density of the circulating solids in order to transfer inert solids to or from the storage vessel.  For hydroforming, suitable catalysts are platinum, palladium, or oxides of molybdenum, chromium, vanadium, or tungsten, supported on activated alumina or zinc aluminate spinel; silica, calcium oxide, ceria, potassia, or zirconia may also be included in the catalyst.  Suitable inert solids are corundum, mullite, fused alumina, and fused silica.  The ratio by weight of catalyst to inert solids in the reaction zone is preferably not less than 5:1 and the ration of inert solids to catalyst withdrawn from the settling zone preferably not less than 1:1. Naphthas boiling in the range 125-450 DEG  F. may be hydroformed in the presence of hydrogen-rich gas at temperatures of 850-1050 DEG  F. and pressures of 50-1000 lbs. per sq. in.  When using molybdenum oxide on alumina catalyst, a small water partial pressure is preferably maintained in the reaction zone.  The regenerator is operated at the same pressure as the reactor and at 1000-1200 DEG  F. The catalyst may remain in the reactor for 1-4 hours and the inert solids for 3-20 minutes.  Specification 741,062 is referred to.