The use of two transalkylation catalysts to react aromatic compounds of
carbon number nine (and heavier carbon numbers) with benzene to form
carbon number eight aromatics is disclosed. The two catalyst system
preserves ethyl-group species on the heavier aromatics that would
otherwise de-ethylate over most gas-phase transalkylation catalysts to
form undesired ethane gas with benzene or toluene. Thus, by using a
transalkylation step to save ethylbenzene, a greater yield of para-xylene
or other carbon number eight aromatics may be achieved within an
integrated complex. An apparatus and process for the two transalkylation
catalyst system is disclosed with a liquid-phase unit and a gas-phase
unit.