Method for producing an aromatic compound having an alkyl group with at least three carbon atoms

Aromatic compounds having an alkyl group with at least 3 carbon atoms are produced in a process comprising at least one of the following steps: (1) a step of contacting a starting material that contains an aromatic compound having a branched alkyl group with at least 3 carbon atoms, with a zeolite-containing catalyst in a liquid phase in the presence of hydrogen therein, thereby changing the position of the carbon atoms of the alkyl group bonding to the aromatic ring of the compound; (2) a step of contacting a starting material that contains an aromatic compound having a branched alkyl group with at least 3 carbon atoms, with a catalyst containing zeolite and containing rhenium and/or silver, in a liquid phase, thereby changing the position of the carbon atoms of the alkyl group bonding to the aromatic ring of the compound; (3) a step of contacting a halogenated aromatic compound having an alkyl group with at least 3 carbon atoms, with an acid-type catalyst, thereby isomerizing the compound; and (4) a step of treating a mixture of isomers of an aromatic compound having an alkyl group with at least 3 carbon atoms, with a zeolite adsorbent that contains at least one exchangable cation selected from alkali metals, alkaline earth metals, lead, thallium and silver, thereby separating a specific isomer from the isomer mixture through adsorption.