Catalytic distillation to produce orthoxylene and paraxylene

Abstract

An improvement to a known process in which C.sub.8 aromatic hydrocarbons are treated to recover a desired isomer of xylene, and in particular o-xylene or p-xylene. A step in recovering isomers of xylene typically includes subjecting a mixture of xylenes to fractional distillation and drawing a stream rich in o-xylene from the fractionation column. The current improvement involves the steps of contacting the contents of the fractionation column with an isomerization catalyst, thereby isomerizing C.sub.8 aromatic hydrocarbons in the fractionation column toward equilibrium and consequently enhancing the effectiveness of the fractional distillation in the recovery of the desired xylene isomer. The process can be carried out in the xylene splitter of existing apparatus by making appropriate modifications thereto. It also can be carried out in newly-designed and fabricated apparatus. Embodiments are disclosed for favoring the production either of o-xylene or p-xylene.

Dependencies are inferred from the claim text.