Patent GB-608605-A (GB)
Title: Improvements relating to the production of cyclohexane from hydrocarbon mixtures
IPC: C07C7/163
Filed: 1945-08-09
Abstract: Cyclohexane is produced from hydrocarbon mixtures such as petroleum and other naphthas by initial fractionation of the feedstock to give a substantially olefin-free mixture of cyclohexane, benzene, 2.2- and/or 2.4-dimethylpentane, from which mixture the paraffins are taken overhead by a single stage fractionation in presence of a polar solvent such as aniline, phenol, nitrobenzene, and glycerol ethers and esters, the residue being distilled from the solvent, and hydrogenated to convert all or part of the benzene to cyclohexane. When part only of the benzene is hydrogenated, the remainder may be removed overhead as an azeotrope with cyclohexane and recycled to the extractive distillation or hydrogenation zone.  An isoheptane fraction of B.R. 68-91 DEG  C., is fractionated first to remove constituents boiling above 81 DEG  C., and then to obtain a cyclohexane concentrate of B.R. 74-81 DEG  C.  This is subjected to a single extractive distillation with the commonly used polar solvents to separate paraffin from cyclic hydrocarbons which are hydrogenated. The fraction of B.R. 68-74 DEG  C., obtained in concentrating the cyclohexane and containing n-hexane, methylcyclopentane, and benzene may be treated to isomerize methylcyclopentane to cyclohexane.  In an example, the cyclohexane concentrate obtained by fractionation is extractively distilled with aniline whose concentration in the operating hold-up is 50 per cent by weight, the hydrocarbon reflux ratio being 40 : 1.  Specifications 585,850, 606,797 and 606,800 are referred to.ALSO:Cyclohexane is produced from hydrocarbon mixtures such as petroleum and other naphthas by initial fractionation of the feedstock to give a substantially olefin-free mixture of cyclohexane, benzene, 2,2- and/or 2,4-dimethylpentane, from which mixture the paraffins are taken overhead by a single stage fractionation in presence of a polar solvent such as aniline, phenol, nitrobenzene, and glycerol ethers and esters, the residue being distilled from the solvent, and hydrogenated to convert all or part of the benzene to cyclohexane.  When part only of the benzene is hydrogenated, the remainder may be removed overhead as an azeotrope with cyclohexane and recycled to the extractive distillation or hydrogenation zone. An isoheptane fraction of B.R. 68-91 DEG  C. is fractionated first to remove constituents boiling above 81 DEG  C. and then to obtain a cyclohexane concentrate of B.R. 74-81 DEG  C.  This is subjected to a single extractive distillation with the commonly used polar solvents to separate paraffins from cyclic hydrocarbons which are hydrogenated.  The fraction of B.R. 68-74 DEG  C. obtained in concentrating the cyclohexane and containing n-hexane, methylcyclopentane, and benzene may be treated to isomerize methylcyclopentane to cyclohexane.  In an example, the cyclohexane concentrate obtained by fractionation is extractively distilled with aniline whose concentration in the operating hold-up is 50 per cent by weight; the hydrocarbon reflux ratio being 40 : 1.  Specifications 585,850; 606,797 and 606,800, [both in Group III], are referred to.