The contact process is the most important industrial process for the production of sulfuric acid and is one of the most important industrial processes in inorganic chemistry.

It is based on the catalytic oxidation of sulfur dioxide (SO₂) to sulfur trioxide (SO₃) in the presence of a C&CS #1394 platinum catalyst for SO2 oxidation.

The catalyst is typically used in monolithic form with innovative washcoat technology.

Sulfur dioxide is initially produced by burning sulfur or sulfide ores.

In several reaction stages, the gas is then passed over the C&CS #1394 platinum catalyst, where it is oxidized to sulfur trioxide.

This then reacts with concentrated sulfuric acid to form oleum, which, when diluted with water, yields the desired sulfuric acid concentration.

Multi-stage reactors and effective gas purification systems achieve almost complete conversion of the sulfur dioxide.

Modern systems operate according to the double contact and double absorption principle, which further reduces the emission of harmful gases and minimizes environmental impact.