Patent GB-745522-A (GB)
Title: Improved two-stage hydroforming process
IPC: C10G35/14
Filed: 1952-08-18
Abstract: Naphthenic petroleum hydrocarbons boiling in the motor fuel range are hydroformed by contacting the hydrocarbons in a first stage with a hydroforming catalyst, comprising platinum or palladium on a halogen-free support of low hydrocracking activity, in the presence of hydrogen and at 600 DEG  to 950 DEG  F. and a pressure from 50 to 1000 p.s.i.g., removing the resulting hydrocarbons from the first stage and contacting at least a portion of them in a second stage with a different hydroforming catalyst comprising an oxide or sulphide of a Group VI metal on a support, in the presence of hydrogen, at 900 DEG  to 1030 DEG  F. and a pressure from 0 to 350 preferably 0 to 250 p.s.i.g.  The first reaction stage is preferably operated at 800 DEG  to 900 DEG  F. and at a pressure of 500 to 750 p.s.i.g. whilst the hydrogen-hydrocarbon mol. ratio may be from 4/1 to 6/1 and the feed rates in the range of from 2 to 5 volumes of feed per volume of catalyst per hour.  The catalyst in the first reaction stage may be platinum or palladium on alumina and may contain 0.2 to 1.0 per cent of platinum or 0.5 to 2.0 per cent palladium.  It may be prepared by compositing platinum or palladium with alumina gel or activated alumina.  The catalysts in the second reaction stage are preferably those containing from 8 to 15 per cent of molybdenum oxide on 92 to 85 per cent alumina or zinc aluminate spinel or those containing about 15 to 40 per cent chromium oxide on 85-60 per cent of activated alumina or zinc aluminate spinel.  This catalyst may also contain up to about 0.75-2.0 per cent of a stabilizer or promoter such as silica, potassia or ceria and also small amounts of hydrogen fluoride and if desired the carrier may be treated with steam.  In the second stage the reaction temperature is preferably 900 DEG  to 950 DEG  F. and the pressure is preferably 150 to 200 p.s.i. for molybdena catalysts and 990-1030 DEG F. and up to 50 p.s.i. for chromia catalysts and the space velocity in this stage should be in the range of 0.2-1.5 volumes of feed per volume of catalyst per hour.  The platinum or alumina catalyst may be prepared by preparing alumina which may be mixed with a small amount of organic acid, e.g. acetic acid, and then incorporating platinum into the alumina, e.g. by adding a solution of chloroplatinic acid and hydrogen sulphide.  The catalyst is heated to 200-400 DEG  F. to dry it and is then formed into pills or pellets and heated to 800-1200 DEG  F. for up to 8 hours to activate it.  This first reaction stage may be carried out non-regeneratively in which case it may be operated as a fixed-bed process and the reaction stages may comprise more than one vessel.  Flow diagrams are given to illustrate three different procedures for carrying out the process.  In the first procedure the C4 and C5 products from the first zone are separated for gasoline blending or storage and the C6 + products together with hydrogen and C1-C3 hydrocarbons admitted to the second zone.  The two stages may be effected in either a fixed or in a moving or fluidized bed.  In the second procedure the catalyst in the first stage is in the form of a fixed bed and in the second stage is in the form of finely divided particles maintained as a dense, turbulent, fluidized bed, the catalyst particles being transferred to a regeneration zone and then returned to the dense bed.  In the third procedure the catalyst in the first stage is contained in banks of tubes disposed in the fluidized bed of catalyst in the regeneration zone for the second stage catalyst which is maintained as a dense, fluidized bed. Examples are given for the hydroforming of (1) a heavy virgin naphtha boiling between 200-360 DEG  F.; (2) a C6 light naphtha fraction containing cyclohexane, normal hexane, and methyl cyclopentane; and (3) a virgin naphtha boiling from 200-350 DEG  F. and containing 35 per cent naphthenes.  In each case the catalyst in the first stage is platinum on alumina whilst in the second stage it is molybdenum on alumina in (1) and chromium oxide on alumina containing small amounts of ceria and potassia in (2) and (3).