Patent GB-733799-A (GB)
Title: Improved fluidised hydroforming operation
IPC: C10G35/14
Filed: 1952-10-16
Abstract: In a continuous process for hydroforming hydrocarbons boiling in the motor fuel boiling range in a reaction zone, in the presence of a dense turbulent bed of hydroforming catalyst, of the type wherein finely-divided particles of catalyst are withdrawn continuously from the reaction zone, are transferred to a regeneration zone wherein the carbon content of the catalyst particles is reduced and are then returned to the reaction zone, the regenerated catalyst to oil charging weight ratio is from 0.5 to 1.5 and the regenerated catalyst particles are returned directly to the reaction zone without previously contacting with hydrogen-containing gases.  It is preferred to effect substantially complete generation of the catalyst, e.g. as is shown by the presence of free oxygen in the flue gases from the regenerator and by the presence of less than 0.3 and preferably of less than 0.1 weight per cent of carbon in the regenerated catalyst and by substantially complete oxidation of the catalytic metal to the highest valency form.  The feed stock to the reactor may be a petroleum fraction, e.g. a virgin naphtha or a cracked naphtha or it may be a Fischer-Tropsch naphtha.  The feed-stock is preheated alone or in admixture with recycle gas.  The preheating is ordinarily carried out to temperatures of about 800-1000 DEG  F. and the preheated feedstock may be supplied to the reactor separately or in admixture with hydrogen-rich recycle gas. The recycle gas when introduced separately may be preheated to 1150-1300 DEG  F. prior to its introduction into the reactor.  The hydroforming reactor vessel should be operated at 550-950 DEG  F., preferably at about 900 DEG  F., and at pressures between about 50 and 500 pounds per square inch.  The regenerator is preferably operated at substantially the same pressure as the reactor vessel and at 1050-1300 DEG  F.  Suitable catalysts include Group VI metal oxides such as molybdenum oxide, chromium oxide or tungsten oxide, or mixtures thereof, upon a carrier such as activated alumina or zinc aluminate spinel.  Minor amounts of stabilizers and promoters such as silica, calcium oxide, ceria or potassia can be included in the catalyst.  Two types of reactor-regenerator systems are described and illustrated, one being a side-by-side reactor-regenerator system whilst the other has the regenerator arranged above the reactor with the regenerated catalyst stand-pipe extending downwardly through the dense reactor bed, the regenerated catalyst in each case being returned directly into the dense catalyst bed in the reactor.  The regenerated catalyst is stripped with air or nitrogen and may also be further stripped with small amounts of nitrogen before returning it into the reaction zone.  Examples are given in which catalytically cracked naphtha is used as the feed gas in a hydroforming plant operating at 200 pounds per square inch gauge pressure using a molybdenum oxide on alumina catalyst, a regenerated catalyst to oil ratio of 1 and reactor temperatures of about 900 DEG  F.  The results obtained without pretreatment of the regenerated catalyst with hydrogen are compared with those obtained with a 15-minute pretreat with hydrogen at 900 DEG  F. and 200 p.s.i.g., the heat formed during the pretreatment being quickly dissipated to a fluid sand bath surrounding the catalyst bed.  The results are also compared with those obtained by a process in which the regenerated catalyst is pretreated with hydrogen at 1004 DEG  and 996 DEG  F. respectively for 10-15 seconds.