Styrene: Production route
Two ways to strip hydrogen and the propylene oxide twin
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Almost all styrene is made from ethylbenzene, which is made from benzene and ethylene. Most plants dehydrogenate ethylbenzene directly. About a seventh is made as a co-product of propylene oxide in POSM plants, where the styrene-PO ratio is fixed. A small amount is extracted from pyrolysis gasoline. Plant economics are set by the spread between styrene and its two feeds, benzene and ethylene, and by the steam energy needed for dehydrogenation.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Ethylbenzene dehydrogenation (EB/SM) | about 85% (indicative) | about 0.79 t benzene, 0.28 t ethylene, plus large steam input (indicative) | 300-700 kt/yr; ZPC runs four 600 kt/yr units (Chemical Week) | about 90% on ethylbenzene (indicative) | hydrogen, toluene, benzene | feed cost about 0.79 x benzene + 0.28 x ethylene plus about $100-150/t conversion (indicative) |
| Propylene oxide/styrene monomer (POSM) | about 15% (indicative) | about 2.2-2.5 t styrene per t PO (indicative) | Maasvlakte POSM 680 kt/yr nameplate (Chemical Week); ZPC 600 kt/yr | fixed co-product | propylene oxide | shared with PO |
| Extractive distillation from pyrolysis gasoline | about 1% (indicative) | pygas | 50-150 kt/yr | by-product | none extra | low |
How each route works
Ethylbenzene dehydrogenation (EB/SM)Ethylbenzene is mixed with superheated steam and passed over potassium-promoted iron oxide catalyst at about 600 C. Conversion is 60-70% per pass, with styrene separated by vacuum distillation. Licensors include Lummus/UOP and Badger.
Simple and flexible; high steam energy.
Chemical Week, Nov 2023; indicative Propylene oxide/styrene monomer (POSM)Ethylbenzene is oxidised to its hydroperoxide, which epoxidises propylene to PO. The co-product alcohol is dehydrated to styrene. Output ratios are fixed, so styrene supply depends on PO demand.
Lower energy per t than dehydrogenation, but styrene is a by-product of PO economics.
Chemical Week, Nov 2023; indicative Extractive distillation from pyrolysis gasolineStyrene present in cracker pygas is recovered by extractive distillation (for example GT-Styrene) before hydrotreating.
Cheap but small.
indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.