Oleum

Oleum (CAS 8014-95-7), also sold as fuming sulfuric acid or Nordhausen acid, is a solution of sulfur trioxide in concentrated sulfuric acid.

Where is Oleum used?

• Chemical manufacturing: sulfonating and acidifying agent with higher reactivity than standard sulfuric acid
• Detergent and surfactant manufacturing: sulfonates alkylbenzenes and fatty alcohols into anionic surfactant intermediates
• Dye and pigment production: introduces sulfonic acid groups into aromatic compounds for solubility and fixation in textile dyeing
• Petroleum refining: alkylation and sulfonation reactions in lubricant and specialty chemical production
• Mining and metals processing: leaching and digestion acid that dissolves refractory ores
• It is handled and shipped in dedicated acid-resistant tankers or drums under strict transport classifications.

Commercial specifications

• Free SO₃ content typically 20% to 65%
• 20%, 30%, and 65% grades most commonly traded