Patent ID: 8084657

Claim:
An integrated process for the production of p-xylene, comprising the steps of: A) separating a mixed feedstock containing benzene, toluene, C 8 aromatic hydrocarbons, C 9 and higher aromatic hydrocarbons, and non-aromatic hydrocarbons from a reforming unit, to obtain a first benzene stream, a first toluene stream, a first C 8 aromatic hydrocarbon stream, a stream of C 9 and higher aromatic hydrocarbons, and a stream of non-aromatic hydrocarbons; B) feeding the stream of C 9 and higher aromatic hydrocarbons from step A) to a C 9 and higher aromatic hydrocarbon dealkylation unit, where dealkylation reaction occurs in the presence of hydrogen, and separating the reaction effluent to obtain a second benzene stream, a second toluene stream, and a second C 8 aromatic hydrocarbon stream; C) feeding both the first toluene stream and the second toluene stream to a toluene selective disproportionation unit, where toluene selective disproportionation reaction occurs in the presence of hydrogen to produce a stream containing C 8 aromatic hydrocarbons including p-xylene and benzene, which stream is separated to obtain a third C 8 aromatic hydrocarbon stream, a third toluene stream, and a third benzene stream, with the third toluene stream being returned to an inlet of this unit; D) feeding both the first C 8 aromatic hydrocarbon stream and the second C 8 aromatic hydrocarbon stream to an adsorption separation unit, to obtain a first p-xylene product stream and a fifth C 8 aromatic hydrocarbon stream, with the fifth C 8 aromatic hydrocarbon stream being passed to an isomerization unit; E) feeding the third C 8 aromatic hydrocarbon stream to a crystallization separation unit, to obtain a fourth C 8 aromatic hydrocarbon stream and a second p-xylene product stream, with the fourth C 8 aromatic hydrocarbon stream being passed to the adsorption separation unit or the isomerization unit; and F) feeding an effluent of the isomerization unit to an inlet of the adsorption separation unit.