Propylene oxide: Production route
Four routes, from salty wastewater to clean peroxide
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.PO is made by four route families. Chlorohydrin (PO via chlorine and lime) is the oldest and dirtiest. Indirect oxidation with organic hydroperoxides produces large co-products: styrene (PO/SM) or tert-butanol (PO/TBA, used for MTBE). Cumene hydroperoxide (Sumitomo CHP) recycles cumene and has no co-product. HPPO uses hydrogen peroxide over a titanium silicalite catalyst and has no co-product except water. New capacity in China is mostly HPPO, CHP and PO/SM.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Chlorohydrin (CHPO) | about 15-20% of global capacity, falling (indicative) | about 0.8 t propylene, 1.4 t chlorine and 1 t lime per t PO (indicative) | 30-300 kt/yr; Manali Petrochemicals (India) small scale | about 90% on propylene (indicative) | about 2 t CaCl2 in 40-50 t wastewater per t PO; some dichloropropane | competitive where chlorine is cheap, but environmental costs rising |
| PO/SM (styrene monomer co-product) | about 30% (indicative) | about 0.75 t propylene and 2.4 t ethylbenzene per t PO (indicative) | 300-600 kt/yr PO (indicative) | high on propylene | about 2.2-2.5 t styrene per t PO | depends on styrene credit |
| PO/TBA (tert-butanol co-product) | about 10-15% (indicative) | about 0.75 t propylene and 2-2.5 t isobutane per t PO (indicative) | 400-1,000 kt/yr PO; LyondellBasell PO/TBA Channelview about 470 kt PO (indicative) | high | about 2-2.5 t TBA per t PO | tied to MTBE and gasoline values |
| HPPO (hydrogen peroxide) | about 25% and rising (indicative) | about 0.75 t propylene and 0.6 t H2O2 (100% basis) per t PO (indicative) | 100-300 kt/yr; BASF-Dow Antwerp 300 kt (indicative) | over 95% selectivity (indicative) | water; small amounts of propylene glycol | about $150-250/t of H2O2 cost per t PO (indicative) |
| Cumene hydroperoxide (CHP, Sumitomo) | about 10% (indicative) | about 0.75 t propylene per t PO plus hydrogen (indicative) | 200-300 kt/yr | high | none significant | not published |
How each route works
Chlorohydrin (CHPO)Propylene reacts with chlorine and water to propylene chlorohydrin, which is dehydrochlorinated with lime or caustic soda to PO. Produces large volumes of calcium or sodium chloride brine.
Simple and small-scale, but polluting; restricted in China.
indicative PO/SM (styrene monomer co-product)Ethylbenzene is oxidised to its hydroperoxide, which epoxidises propylene; the resulting alcohol is dehydrated to styrene. About 2.2-2.5 t styrene is made per t PO.
Very large plants that tie PO to styrene markets.
indicative PO/TBA (tert-butanol co-product)Isobutane hydroperoxide epoxidises propylene; tert-butanol is converted to MTBE or isobutylene.
Large co-product exposure to fuel markets.
indicative HPPO (hydrogen peroxide)Propylene reacts with hydrogen peroxide in methanol over a titanium silicalite (TS-1) catalyst. Developed by Evonik/thyssenkrupp Uhde and BASF/Dow, now widely licensed and copied in China.
No co-product and cleaner; needs an integrated H2O2 plant.
indicative Cumene hydroperoxide (CHP, Sumitomo)Cumene hydroperoxide epoxidises propylene; cumyl alcohol is hydrogenated back to cumene and recycled.
No co-product; licensed in Japan, Saudi Arabia (Petro Rabigh) and China.
indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.