Patent GB-850933-A (GB)
Title: Improvements in or relating to the upgrading of petroleum fractions
IPC: C10G51/00
Filed: 1957-06-20
Abstract: <PICT:0850933/III/1> Petroleum distillates are upgraded by first reforming in the presence of hydrogen, separating the effluent into a light gasoline fraction having an end point of 165-225 DEG F., an intermediate fraction having an end point of 290-440 DEG F. and a bottoms fraction, separating the intermediate fraction into an essentially aromatic and a non-aromatic stream and treating the latter in an isomerisation-cracking zone with at least 1500 S.C.F. of hydrogen per barrel of feed to the zone in the presence of a catalyst comprising a hydrogenating-dehydrogenating component on an active cracking support at 700-850 DEG F., above 600 p.s.i.g. and at a space rate of 0.3 to 10 vol./vol./hr.  Suitable feeds include naphthas of straight run or cracked origin boiling in the range 175-550 DEG F., light cycle oils from cracking units boiling between 380 DEG  and 600 DEG F. and gas oils boiling in the range 400-750 DEG F. or mixtures of such feeds or their fractions.  The feed preferably contains less than 20 p.p.m. or nitrogen and 0.02% sulphur and may be hydrofined if necessary.  In a preferred embodiment the feed passes to the reforming zone 11 where it is treated with 2,000-6,000 S.C.F. of hydrogen per barrel at 850-1000 DEG F., 200-900 p.s.i.g. and 1-3 vol./vol./hr. over a catalyst comprising 8-12% molybdenum oxide on alumina or 0.1-1.0% platinum on alumina activated with halogens. From the product hydrogen is separated in separator 14 and recycled and other normal gases removed by separator 17 and the liquid fed to fractionator 20.  A light gasoline stream (C4 or C5 to 165-225 DEG F.) is removed as product by line 21.  An intermediate fraction (boiling up to 290-440 DEG F.) is fed by line 22 to the separation zone 23 where aromatics are separated from non-aromatics in known manner, e.g. by extractive distillation, selective adsorption or by use of selective solvents.  The aromatic fraction containing 80-100% aromatics is recovered as product by line 24, the non-aromatic fraction leaves by line 25 and may be handled in one of two ways. It may be fed to fractionator 27 from which a lighter portion (boiling up to 265-300 DEG F.) is taken to storage vessel 29 while the bottoms are recycled to the reforming stage; alternatively the fractionator is by-passed and the whole fraction led to storage. The bottoms from fractionator 20 are led to storage vessel 33. The liquids from storage vessels 29 and 33 are then passed together or preferably alternately to the isomerisation-cracking zone 37.  The catalyst in this zone may have as the hydrogenation-dehydrogenation component a Group VI or VIII metal, its oxide or sulphide such as iron, nickel or cobalt or their oxides or the oxides or sulphides of molybdenum, tungsten or chromium.  Group I or II metals such as copper or cadmium and their oxides may be used.  The amount of this component may be 0.1-15% of the entire catalyst.  The cracking support may be a silica-alumina, silicamagnesia or silica-alumina-zirconia composite or an acid treated clay.  This catalyst preferably has a severity factor, determined by a standard test which is described, between 0 and 5.  Hydrogen is also passed into the zone 37 in a preferred amount of 3,000-30,000 S.C.F. per barrel of feed, being obtained from recycle material, excess hydrogen produced in the reforming process and make-up hydrogen as necessary.  From the effluent from this zone hydrogen is separated in separator 42 and recycled and other normal gases removed in separator 44.  The remaining liquid may then be passed to fractionator 47 to give a light gasoline fraction by line 48 and a heavier gasoline by line 49, having any desired end point. The bottoms if any are preferably recycled to zone 37 or may be removed from the system.  In an alternative proccedure the liquid from separator 44 is passed to fractionator 20, eliminating fractionator 47, while in another procedure (not illustrated) the whole effluent from zone 37 is fed to separator 14 thereby also eliminating separators 42 and 44.