Patent GB-916683-A (GB)
Title: A process for obtaining aromatic compounds from cracked gasoline
IPC: B01J23/89
Filed: 1961-07-07
Abstract: Aromatic hydrocarbons are recovered from a gasoline obtained by cracking or pyrolysing a petroleum fraction at above 600 DEG C. by hydrogenating in the liquid phase to hydrogenate diolefins without affecting aromatics of monoolefins, fractionating to obtain one or more fractions rich in aromatics, subjecting one or more of these fractions to a second hydrogenation to saturate olefins without affecting aromatics and recovering the aromatics. The first hydrogenation is preferably effected in the "trickling" phase at below 50 DEG C. over platinum, palladium of nickel supported on a macroporous carrier having an internal surface area below 50 m2./g. or over combinations of nickel and/or cobalt sulphide.  Carbon monoxide and sulphur compounds should be removed beforehand if the catalyst is sensitive.  The fractionation should separate fractions containing at least 50% by weight of aromatics, e.g. benzene, toluene or xylene.  Where more than one aromatic is separated they may be removed as a single fraction or as separate fractions which may be further treated separately or together.  The second hydrogenation is effected in the vapour or liquid phase at 250 DEG -400 DEG C. 10-60 atmospheres, and 0,5-3 kg. per hour per litre of catalyst, e.g. an oxidic or sulphidic catalyst such as cobalt molybdate or molybdic acid on alumina, to obtain a product having a bromine number of zero. The aromatic hydrocarbons may be finally recovered by fine fractionation, by extraction with a glycol or sulpholane extractant or liquid sulphur dioxide or by extractive distillation with phenol. The raffinate may be combined with unused product from the first hydrogenation for use as a motor fuel or may be used as a solvent.ALSO:Aromatic hydrocarbons are recovered from a gasoline obtained by cracking or pyrolysing a petroleum fraction at above 600 DEG C. by hydrogenating in the liquid phase to hydrogenate diolefins without affecting aromatics or mono-olefins, fractionating to obtain one or more fractions rich in aromatics, subjecting one or more of these fractions to a second hydrogenation to saturate olefins without affecting aromatics and recovering the aromatics. The first hydrogenation is preferably effected in the "trickling" phase at below 50 DEG C. over platinum, palladium or nickel supported on a macroporous carrier having an internal surface area below 50 m.2/g. or over combinations of nickel and/or cobalt sulphide.  Carbon monoxide and sulphur compounds should be removed beforehand if the catalyst is sensitive.  The fractionation should separate fractions containing at least 50% by weight of aromatics, e.g. benzene, toluene or xylene.  Where more than one aromatic is separated they may be removed as a single fraction or as separate fractions which may be further treated separately or together.  The second hydrogenation is effected in the vapour or liquid phase at 250-400 DEG C., 10-60 atmospheres, and 0.5-3 kg. per hour per litre of catalyst, e.g. an oxidic or sulphidic catalyst such as cobalt molybdate or molybdic acid on alumina, to obtain a product having a bromine number of zero. The aromatic hydrocarbons may be finally recovered by fine fractionation, by extraction with a glycol or sulpholane extractant or liquid sulphur dioxide or by extractive distillation with phenol. The raffinate may be combined with unused product from the first hydrogenation for use as a motor fuel or may be used as a solvent.