Disclosed is a process for the production of alkylated aromatics by contacting a feed stream comprising an alkylatable aromatic, an alkylating agent and trace amounts of water and impurities in the presence of a first catalyst and an alkylation catalyst wherein such water and impurities are removed in order to improve the cycle length of such alkylation catalysts. Water and at least a portion of impurities are removed in a dehydration zone. A reaction zone having a first catalyst which, in some embodiments is a large pore molecular sieve, acts to remove another portion of impurities, such as nitrogenous and other species. An alkylation zone having an alkylation catalyst which, in some embodiments is a medium pore molecular sieve or a MCM-22 family material, acts to remove additional impurities, and to alkylate the alkylatable aromatic compound.