Process Technology Quick Reference Cards

Aromatics

Chapter from the Process Technology Quick Reference Cards.

AROMATICS PROCESSING

Process Objective

Produce high-purity BTX (benzene, toluene, xylenes) from reformate or pyrolysis gasoline for petrochemical feedstock.

Key Operating Variables

Variable	Typical Range	Effect / Notes
Feed Type	Reformate, pygas, condensate	Composition determines BTX yield potential
Extraction Solvent	Sulfolane, NMP, glycols	Selectivity and capacity of extraction
Isomerization Temp	750-900°F	Xylene equilibrium and ethylbenzene conversion
Adsorption	Simulated moving bed (Parex)	Para-xylene recovery from mixed xylenes
Transalkylation Temp	700-900°F	Toluene + C9 → xylenes

Process Configurations

Extraction (Sulfolane, NMP): separates aromatics from non-aromatics in reformate
Transalkylation: Toluene + C9+ aromatics → xylenes (increases PX feedstock)
Xylene isomerization: converts mixed xylenes toward equilibrium (~24% PX)
Para-xylene recovery: Parex (UOP) or Eluxyl (Axens) — simulated moving bed adsorption
Integrated Aromatics Complex: extraction → fractionation → transalkylation → PX recovery → xylene isom loop

Products & Yields

Benzene: 99.9%+ purity (petrochemical feedstock)
Para-xylene: 99.7%+ purity (PTA/PET production)
Ortho-xylene: 98%+ (phthalic anhydride production)
Toluene: solvent grade or transalkylation feed
Raffinate: non-aromatic stream (gasoline blending or steam cracker feed)

Common Troubleshooting

Low extraction efficiency: check solvent quality, water content, temperature
PX purity issues: adsorbent aging, desorbent quality in Parex unit
Catalyst deactivation: check feed pretreatment, regeneration cycle
Column flooding: aromatics columns often capacity-limited — check vapor rates

Source: Process_Tech_Quick_Reference_Cards_v1.xlsx · sheet “Aromatics”

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