Caprolactam: Production route
How chemists cut the fertiliser by-product
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.All commercial caprolactam goes through cyclohexanone oxime and a Beckmann rearrangement. Routes differ in how the oxime is made and how much ammonium sulphate results. The conventional Raschig hydroxylamine route gives the most by-product. Ammoximation with hydrogen peroxide, now dominant in China, and DSM's HPO process give much less. Sumitomo's vapour-phase Beckmann avoids it entirely. Cyclohexanone comes from benzene via cyclohexane, or from phenol.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Ammoximation with liquid-phase Beckmann (Eni/Sinopec TS-1 process) | about 50-60% of capacity (indicative, mostly China) | about 0.9 t benzene equivalent, 0.15-0.2 t ammonia, 0.3-0.35 t H2O2 (100%) and oleum (indicative) | 200-400 kt/yr trains; Highsun 1.2 Mt/yr group capacity (Chemical Week) | high | about 1.3-1.6 t ammonium sulphate per t (indicative) | about CNY8,600/t market price in November 2025 with thin or negative margins (Chemical Week) |
| Raschig hydroxylamine sulphate route | about 20% (indicative) | about 0.9 t benzene, about 0.6-1 t ammonia, oleum and sulphur (indicative) | 50-300 kt/yr | high | about 4-4.5 t ammonium sulphate per t; N2O from ammonia oxidation (indicative) | higher; depends on ammonium sulphate credit |
| HPO process (hydroxylamine phosphate oxime, DSM/Fibrant) | about 15% (indicative) | similar benzene; less sulphur (indicative) | 100-300 kt/yr | high | about 1.6-1.8 t ammonium sulphate per t (indicative) | not published |
| Vapour-phase Beckmann (Sumitomo) | below 5% (indicative) | benzene, ammonia, H2O2, methanol (indicative) | small number of plants | slightly lower | none of significance | not published |
How each route works
Ammoximation with liquid-phase Beckmann (Eni/Sinopec TS-1 process)Cyclohexanone, ammonia and hydrogen peroxide react over a titanium silicalite catalyst to give oxime directly, avoiding hydroxylamine salts. Rearrangement in oleum still gives some ammonium sulphate. Most new Chinese capacity uses this route.
Lower by-product and capex; needs cheap H2O2.
Chemical Week, Dec 2025; indicative Raschig hydroxylamine sulphate routeAmmonia is oxidised to nitrogen oxides, converted to hydroxylamine sulphate, reacted with cyclohexanone to oxime, then rearranged in oleum. Older European, Japanese and Indian plants use variants of this route.
Proven; huge by-product and N2O.
indicative HPO process (hydroxylamine phosphate oxime, DSM/Fibrant)Hydroxylamine is made by hydrogenating nitrate in a phosphate buffer, which avoids ammonium sulphate at the oxime step.
Lower by-product; Fibrant's Geleen site is stopping caprolactam (S&P Global).
S&P Global H1 2026; indicative Vapour-phase Beckmann (Sumitomo)Ammoximation followed by gas-phase rearrangement over a zeolite catalyst, with no oleum and no ammonium sulphate.
Cleanest route; limited licensing.
indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.