XYLENE-CONTAINING NONEQUILIBRIUM FEED STOCK FLOW ISOMERISATION PROCEDURE

摘要

FIELD: chemistry.;SUBSTANCE: invention refers to xylene isomerisation in feed stock containing nonequilibrium mixture of two or more xylenes and optionally ethylbenzene characterised by that feed stock flow contacts with layered catalyst in catalytically effective amount in isomerisation environment including temperature within 100° to 550°C, absolute pressure within 10 kPa to 5 MPa and hydrogen to hydrocarbons molar ratio within 0.5:1 to 6:1, required for isomerisation product flow containing xylenes, where paraxylene takes at least 23 wt %, orthoxylene at least 21 wt %, and methaxylene at least 48 wt %. Said catalyst has an alpha-alumina frame of principal dimension at least 300 mcm coated with a layer of MFI molecular sieve structure with aperture diameter 4 to 8 angstrom, and an alumina or gamma-alumina binding material of thickness 250 mcm and less, and at least one hydrogenating metal component chosen of the group including Pt and Mo, as the binding material represents aluminium phosphate, and Re, as the binding material is represented by gamma-alumina. At least 75 wt % of hydrogenating metal component in the catalyst is accumulated in the layer wherein total amount of formed toluene and trimethylbenzene is 3 wt % and less of total xylenes and ethylbenzene in feed stock flow.;EFFECT: reduced loss of aromatic hydrocarbons and good balance approximation in isomerisation process.;7 cl, 4 tbl, 7 ex