Technology Type

The first commercially successful method for making sulfuric acid was developed in 1746 by English physician, chemist, and inventor John Roebuck (1718–1794). Roebuck's method is called the lead chamber process because the acid is made in large containers lined with lead. The lead chamber process involves three primary steps: the combustion of sulfur to produce sulfur dioxide; the conversion of sulfur dioxide to sulfur trioxide; and the reaction of sulfur trioxide with water to make sulfuric acid:

S + O₂ → SO₂

2SO₂ + O₂ → SO₃

SO₃ + H₂O → H₂SO₄

Although the process looks fairly simple, the reactions are actually somewhat complex because of other compounds needed to make the reactions occur.

The second method for making sulfuric acid is known as the contact process. It was invented about 1830 by an English vinegar merchant from Bristol, Peregrine Phillips. The chemical reactions involved in Phillips' process are identical to those in the lead chamber process, but they are carried out over a catalyst of finely divided platinum metal. Phillips found that the yield obtained (the amount of raw material converted to useful product) was much higher than with the lead chamber process.

As it happens, little attention was paid to Phillips' discovery because there was not much demand for sulfuric acid at the time. It was not until the invention of synthetic dyes a few decades later that the compound became commercially important. But even then, the lead chamber process was the preferred method for making sulfuric acid. Over time, improvements were made in the contact process, and it gradually became more and more popular. Today, nearly all of the sulfuric acid produced is manufactured by some modification of Peregrine Phillips' method.