FIELD: chemistry.
SUBSTANCE: invention relates to a method for isomerisation of xylenes, involving: (a) feeding a stream of naphtha into a hydrofining zone, in which the naphtha stream comes into contact with a hydrofining catalyst under hydrofining conditions to obtain a hydrofined stream of naphtha; (b) feeding the hydrofined stream of naphtha into a reforming zone in which the said hydrofined naphtha comes into contact with a reforming catalyst under reforming conditions to obtain a stream of a reforming product containing aromatic compounds, and in which gases and C4-hydrocarbons and lighter hydrocarbons obtained in the reforming zone give out a stream of reforming product which is significantly free from gases and C4-hydrocarbons and lighter hydrocarbons; and (c) feeding the stream of reforming product and the exhaust stream from the isomerisation zone, independently or in form of a combined stream, into a zone for fractionation of reforming products using a distillation column to obtain initial material containing benzene, toluene and C5-C8-aliphatic hydrocarbons, and a stream rich in xylene an heavier hydrocarbons; (d) feeding the initial material containing benzene, toluene and C5-C8-aliphatic hydrocarbons into an extractive distillation zone and separation of the stream of a bottom product of aromatic hydrocarbons containing benzene and toluene, a lateral stream of aliphatic hydrocarbons containing C7-C8-aliphatic hydrocarbons and a stream of an overhead fraction of aliphatic hydrocarbons containing C5-C7-aliphatic hydrocarbons; (e) processing the lateral stream of aliphatic hydrocarbons containing C7-C8-aliphatic hydrocarbons to form a lateral stream of aliphatic hydrocarbons significantly free from the solvent and containing C7-C8-aliphatic hydrocarbons; (f) adding hydrogen into the lateral stream of aliphatic hydrocarbons significantly free from the solvent and containing C7-C8-aliphatic hydrocarbons, and into a non-equilibrium stream of xylene, involving contact between a non-equilibrium mixture of xylenes and an isomerisation catalyst in the isomerisation zone under isomerisation conditions and formation of an exhaust stream containing para-xylene from the isomerisation zone. The invention also relates to versions of the method of producing benzene and para-xylene from naphtha.
EFFECT: use of disclosed methods enables production of aromatic hydrocarbons while saving capital and lowering operational costs and improving investment profitability.
17 cl, 1 dwg
