Oleum (Fuming Sulphuric Acid)
20% & 65% free SO₃ for sulphonation & detergent chemistry
Oleum is sulphuric acid carrying dissolved sulphur trioxide, and it is specified by free SO₃ content rather than by acid strength: 20% oleum (about 104.5% equivalent H₂SO₄) is the standard industrial grade, 25–30% serves specific sulphonations, and 65% oleum is the concentrated form used where SO₃ is the reagent and the acid is just the carrier. The number that matters after strength is freezing point, which is the practical curse of the product: 20% oleum freezes at about minus 11 °C, 30% at around 20 °C, and 65% at a little below 0 °C, so ISO tanks are heated and insulated and a shipment planned in winter without a heating plan arrives as a solid. Iron, chloride and nitrogen oxides are the trace limits, the last because oleum made with nitrosyl catalysis carries NOₓ that ruins sulphonation products.
Buy oleum when the process consumes SO₃: sulphonation of alkylbenzene and fatty alcohols for detergents, dye and pigment intermediates, sulphamic acid, nitration acid mixes for explosives and pharmaceuticals, caprolactam, and regeneration of spent acid. The rule of thumb is that if a buyer can use 98% acid they should, because oleum costs more, ships in dedicated heated ISO tanks or small stainless parcels, and is classed for transport as UN 1831 with fuming hazards that many ports and lines restrict. CBIL brokers 20%, 30% and 65% oleum from integrated acid plants in the Gulf, India, Europe and East Asia against independent certification of free SO₃, iron, chloride and NOₓ at load, in heated ISO tanks and dedicated bulk parcels, on FOB, CFR and CIF terms.
Indicative reference
$160–290 USD / MT
as at September 2026
Reference level only — not an offer, and reviewed quarterly. Levels shown are as at September 2026. Firm pricing is quoted per RFQ, subject to volume, terms and inspection.
Typical Specification
Specifications are indicative and adjusted to the agreed contract and destination requirements. Final spec confirmed on COA / SGS.
Available Grades
Applications
- LAB & fatty alcohol sulphonation (detergents)
- Dye & pigment intermediates
- Nitration acid mixes
- Caprolactam manufacture
- Spent acid regeneration
Category
Petroleum & Energy
Incoterms
FOB · CFR · CIF
Pricing basis
USD / MT
Inspection
SGS / Intertek at load port
Oleum (Fuming Sulphuric Acid) — buyer questions
Which oleum strength should I order?
The one your reaction stoichiometry needs and your handling can cope with. 20% is the default for most sulphonation and mixed-acid duty and is the easiest to ship. 65% carries three times the SO₃ per tonne, which cuts freight per unit of reagent, but it fumes heavily, needs stainless throughout and is restricted by more carriers. 30% sits in between and freezes at room temperature, which is why it is the least shipped grade.
Why does freezing point matter so much?
Because oleum freezes at temperatures a normal winter reaches. A 20% oleum ISO tank left on a quay at minus 15 °C solidifies, and thawing it safely takes days of controlled heating. Specify heated and insulated tanks, agree who pays for heating during transit and at destination, and route around winter ports where possible. This is the item that most often turns an oleum shipment into a claim.
Can oleum be shipped in a standard chemical tanker?
Only in dedicated stainless-steel tanks with a carrier approved for UN 1831, and many parcel tanker operators will not take it. For most buyers the practical unit is the heated ISO tank moving by container line. If your volume justifies a bulk parcel, the vessel nomination has to be settled before the price, not after, because carrier availability decides whether the cargo can move at all.
What documents should accompany oleum?
An independent certificate of analysis for free SO₃, iron, chloride and nitrogen oxides at load; certificate of quantity; safety data sheet; UN 1831 dangerous-goods declaration; tank heating and cleaning certificates; and certificate of origin. Ask for the NOₓ figure specifically, because a plant using nitrose catalysis will not volunteer it and it is the number that spoils a sulphonation batch.
Ready to source Oleum?
Send your quantity, specification, preferred Incoterms and destination port. We'll verify supply and respond with a workable offer — usually within one business day.
Have Oleum to sell? Submit an offer — we'll match it against live buyer demand.