A method is disclosed for selective simultaneous production of para-xylene, para-ethyltoluene and para-diethylbenzene from a reactant stream containing ethylbenzene and methanol, as an alkylating agent. The process comprises alkylation of the feedstock in a fluidized-bed rector under alkylating conditions, over a modified ZSM-5-based catalyst to produce streams containing above 95% para-isomers of dialkylbenzenes. The method also includes the steps of multilayer silylation to achieve simultaneous selectivity of the para-isomers of dialkylbenzenes.