Patent ID: 7812204

Claim:
A process for the production of 2,6-dimethylnaphthalene starting from hydrocarbon blends containing naphthalene and/or methyl naphthalene isomers and/or dimethyl naphthalene isomers and/or polymethyl naphthalene isomers, one or more benzene hydrocarbons, optionally a methylating agent, in the presence of a zeolite catalyst belonging to the MTW structural group, comprising the following steps: I. A first chemical transformation I of naphthalene blends containing naphthalene and/or methyl naphthalene isomers and/or dimethyl naphthalene isomers and/or polymethyl naphthalene isomers, effected in the presence of one or more benzene hydrocarbons, a catalyst containing a zeolite belonging to the MTW structural group, optionally a methylating agent, with the aim of producing a naphthalene blend enriched in the 2,6-dimethylnaphthalene isomer, wherein the benzene hydrocarbon is selected from benzene, toluene, xylene isomers, trimethyl benzene isomers, tetramethyl benzene isomers, pentamethyl benzene, hexamethyl benzene and blends thereof, and the overall ratio between the number of moles of methyl radicals contained in the benzene hydrocarbons and the number of moles of benzene rings is higher than the overall ratio between the number of moles of methyl radicals contained in the naphthene hydrocarbons and the number of moles of naphthalene rings of the naphthalene fraction reacted, II. A second chemical transformation II of naphthalene blends mainly containing dimethyl naphthalene isomers and/or polymethyl naphthalene isomers, effected in the presence of a catalyst containing a zeolite belonging to the MTW structural group, and one or more benzene hydrocarbons selected from benzene, toluene, xylene isomers, trimethyl benzene isomers, tetramethyl benzene isomers, pentamethyl benzene, hexamethyl benzene and blends thereof, and the overall ratio between the number of moles of methyl radicals contained in the benzene hydrocarbons and the number of moles of benzene aromatic rings is lower than the overall ratio between the number of moles of methyl radicals contained in the naphthene substrate and the number of moles of naphthalene rings of the naphthalene fraction reacted, with the aim of obtaining a naphthalene blend containing a higher concentration of naphthalene and methyl naphthalenes with respect to the blend reacted, wherein said naphthalene and methyl naphthalenes are re-used in step I; III. Optionally a third chemical transformation III of naphthalene blends mainly containing dimethyl naphthalene isomers, effected in the absence of benzene hydrocarbons and in the presence of a catalyst containing a zeolite belonging to the MTW structural group, with the aim of obtaining a blend of dimethyl naphthalene isomers, enriched in the 2,6-dimethylnaphthalene isomer, wherein hydrogen is fed in the chemical transformation step I and/or in the chemical transformation step II.