In a method for the production of ethylbenzene and the transalkylation of polyethylbenzene, which comprises: (a) supplying a raw material containing benzene and ethylene at a designated molar ratio of benzene to ethylene to a multi-stage alkylation reaction zone that It has a plurality of catalytic beds connected in series each containing an aromatic alkylation catalyst of pentasyl molecular sieve predominantly comprising monoclinic silicalite with a silica / alumina ratio of at least 300 and an average crystal size of about 0.5 microns or less, (b) operating said alkylation reaction zone at conditions of temperature and pressure where benzene is in the gas phase to cause gas phase ethylation of said benzene in the presence of said silicalite catalyst to produce an alkylation product comprising a mixture of ethylbenzene and polyalkylated aromatic components including xyle no and diethylbenzene; (c) supplying said raw material to said reaction zone at a flow rate to provide a spatial velocity of benzene in said raw material to produce a concentration of xylene in said product that is not greater than about 0.06% by weight based on ethylbenzene in the product and polyalkylated aromatic components heavier than diethylbenzene of no more than 0.2% by weight based on ethylbenzene in the product; (d) recovering said alkylation product from said reaction zone and supplying said product from said reaction zone to an intermediate recovery zone for the separation and recovery of ethylbenzene from the alkylation product and the separation and recovery of a polyalkylated aromatic component including diethylbenzene; (e) supplying at least a portion of said polyalkylated aromatic component including diethylbenzene in said polyalkylated component to a transalkylation reaction zone containing a zeolite transalkylation catalyst comprising a molecular sieve with a pore size greater than the pore size of said silicalite alkylation catalyst; (f) supplying benzene to said transalkylation reaction zone; and (g) operating said transalkylation reaction zone under conditions of temperature and pressure to maintain benzene in the liquid and effective phase to cause disproportionation of said polyalkylated aromatic fraction to produce a disproportionation product with a reduced diethylbenzene content and a content of Improved ethylbenzene, the improvement being characterized in that the method further comprises the step of decreasing the molar ratio of benzene to ethylene supplied to said alkylation reaction zone according to a value of about 20% or more to produce an increase in response in xylene in said alkylation product not exceeding 10% with respect to the production of ethylbenzene observed at said designated molar ratio and an increase in heavier polyalkylated aromatic components than diethylbenzene not exceeding 5% of the polyalkylated aromatic components produced at said ratio benzene molar versus ethylene not designated
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