ethyl benzene is produced in a catalyst bed under 0 . 25 to 50 atmospheres of pressure and at temperatures in the range of 50 ° c . to 300 ° c ., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene , thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms . the bottoms are fractionated , the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered .