Process for producing dialklylnaphthalenes

A process for producing dialkylnaphthalenes, comprising (1), (2), (3), and (4):

• (1) catalytically hydrodealkylating, hydrodesulfurizing and hydrodenitrogenating a stock oil containing an amount of naphthalene and/or alkylnaphthalenes, separating a product oil from a product gas, and separating and recovering a fraction composed mainly of naphthalene and/or methylnaphthalene from the product oil;
• wherein the stock oil is a light cycle oil fraction of catalytic cracking of petroleum and has a boiling point in the range of 210 to 280° C.;
• and the hydrodealkylation is carried out in the presence of a hydrodealkylation catalyst comprising a carrier and an active metal component supported on the carrier, the active metal component comprising at least one metal selected from the group consisting of vanadium (V), molybdenum (Mo), chromium (Cr), cobalt (Co), nickel (Ni), platinum (Pt), rhodium (Rh), and iridium (Ir), and/or an oxide or sulfide of said metals, said carrier supporting the active metal component is a material having a porous structure, and comprises at least one member selected from the group consisting of alumina, silica, silica alumina, and kaolin;
• and said porous material has an average pore diameter in the range of 70 to 3000 Å;
• (2) catalytically alkylating or catalytically transalkylating the fraction, recovered in (1), composed mainly of naphthalene and/or methylnaphthalene directly without pretreatment for purification, with an alkylating agent or a transalkylating agent to prepare alkylnaphthalenes;
• (3) separating and recovering dialkylnaphthalenes from the alkylnaphthalenes obtained in (2);
• and
• (4) returning at least a part of the residual fraction, after the separation and recovery of dialkylnaphthalenes in (3), as at least a part of the stock oil in (1) and/or at least a part of the alkylating agent or transalkylating agent in (2) to the corresponding step.