Xylene Isomerization Technology – GT-IsomPX℠
GT-IsomPX is Sulzer GTC’s xylene isomerization technology available in two versions: EB isomerization type and EB dealkylation type. Both versions gain high ethylbenzene conversion rates while producing equilibrium mixed xylenes. Catalysts that exhibit superior physical activity and stability are the key to this technology. The technology and catalysts are used commercially in several applications.

Process Description
For an EB dealkylation type of isomerization, the technology encompasses two main processing areas: reactor section and product distillation section. In this process, PX-depleted feed stream is first mixed with hydrogen. The mixed stream is then heated against reactor effluent and through a process furnace. The heated mixture is fed into isomerization reaction unit, where MX, OX, and PX are isomerized to equilibrium and EB is de-alkylated to Benzene.

The reactor effluent is cooled and flows to the separator, where the hydrogen-rich vapor phase is separated from the liquid stream. A small portion of the vapor phase is purged to control the purity of the recycle hydrogen. The recycle hydrogen is then compressed, mixed with makeup hydrogen, and returned to the reactor.

The liquid stream from the separator is pumped to the deheptanizer to remove light hydrocarbons. The liquid stream from the deheptanizer overhead contains benzene and toluene and is sent to the distillation section to produce high-purity benzene and toluene products. The liquid stream from the deheptanizer bottoms contains mixed xylenes and a small amount of C9+ aromatics. This liquid stream is returned to the PX recovery section.

Process Advantages

  • PX in xylenes reaches thermodynamic equilibrium after reaction
  • EB dealkylation to benzene or isomerization to xylenes. With the EB-dealkylation catalyst, the by-product benzene is produced at high purity by simple distillation
  • Low H2/HC, high WHSV, low xylenes loss
  • Long cycle length
  • Efficient heat integration scheme reduces energy consumption
  • Turnkey package for high purity benzene, toluene, and paraxylene production available