Patent GB-870431-A (GB)
Title: Improvements in or relating to fuels and their preparation
IPC: C10L1/04
Filed: 1959-10-06
Abstract: Jet or rocket fuels comprising naphthenes having at least three condensed rings and 14-26 carbon atoms per molecule, are prepared by concentrating the polycyclic aromatic compounds in a petroleum gas oil containing at least 35% by weight of aromatic compounds boiling in the range 250-600 DEG C., hydrodesulphurising the concentrate, further hydrogenating at a lower temperature to reduce the aromatic content to below 10% by weight and subjecting p  the product to a molecular weight separation, e.g. by fractional distillation to separate a product boiling within the range 250-600 DEG C.  The gas oil should have an aromatic content of at least 35% by weight, boil in the range 250-600 DEG C. and have a specific gravity 15,6 DEG /15,6 DEG C. of between 1,15 and 0,85. Concentration of aromatics may be effected by solvent extraction or selective thermal or catalytic cracking of aliphatic material. The aromatics may then be alkylated with olefins or methanol, the side chains introduced preferably containing not more than 3 carbon atoms.  Hydrodesulphurisation may be effected over a Group 6 or 8 metal oxide or sulphide alone, mixed or with a Group 2 metal oxide or sulphide.  Conditions are 315-485 DEG C., 35-285 kg.cm.2, 0,25-5 vol./vol./hr. and 280-5600 m.3 of hydrogen per m.3 of oil.  The second hydrogenation is effected over nickel, platinum, palladium, cobalt or iron at 145375 DEG C., 70-352 kg./cm.2, 0,25-3 vol./vol./hr. and 280-5600 m.3 of hydrogen per m.3 of oil.  The product preferably contains no more than 8 alkyl carbon atoms per molecule and has a hydrogen-to-carbon ratio of 1,67-1,88. A tricyclic naphthene fuel may boil in the range 250-500 DEG C. and have at least 64% of carbon atoms in condensed rings while a tetracyclic naphthene fuel boils in the range 300-550 DEG C. and has at least 69% carbon atoms in condensed rings.ALSO:Jet or rocket fuels comprising naphthenes having at least three condensed rings and 14-26 carbon atoms per molecule, are prepared by concentrating the polycyclic aromatic compounds in a petroleum gas oil containing at least 35% by weight of aromatic compounds boiling in the range 250-600 DEG C., hydrodesulphurising the concentrate, further hydrogenating at a lower temperature to reduce the aromatic content to below 10% by weight and subjecting the product to a molecular weight separation, e.g. by fractional distillation to separate a product boiling within the range 250-600 DEG C.  The gas oil should have an aromatic content of at least 35% by weight, boil in the range 250-600 DEG C. and have a specific gravity 15.6 DEG /15.6 DEG C. of between 1.15 and 0.85. Concentration of aromatics may be effected by solvent extraction or selective thermal or catalytic cracking of aliphatic material. The aromatics may then be alkylated, the side chains introduced preferably containing not more than 3 carbon atoms. Hydrodesulphurisation may be effected over a Group 6 or 8 metal oxide or sulphide alone, mixed or with a Group 2 metal oxide or sulphide. Conditions are 315-485 DEG C., 35-285 kg./cm.2, 0.25-5 vol./vol./hr. and 280-5600 m.3 of hydrogen per m.3 of oil.  The second hydrogenation is effected over nickel, platinum, palladium, cobalt or iron at 145-375 DEG C., 70-352 kg./cm.2, 0.25-3 vol./vol./hr. and 280-5600 m.3 of hydrogen per m.3 of oil.  The product preferably contains no more than 8 alkyl carbon atoms per molecule and has a hydrogen-to-carbon ratio of 1.67-1.88.  A tricyclic naphthene fuel may boil in the range 250-500 DEG C. and have at least 64% of carbon atoms in condensed rings while a tetracyclic naphthene fuel boils in the range 300-550 DEG C. and has at least 69% carbon atoms in condensed rings.