Mannheim process

Mannheim process

Process type	Chemical
Industrial sector(s)	Chlor-Alkali industry
Feedstock	sodium chloride, sulphuric acid
Product(s)	hydrogen chloride

The Mannheim process is an industrial process for the production of hydrogen chloride and sodium sulfate.

History

Swedish chemist Carl Wilhelm Scheele discovered the chemical reaction in 1772.

In 1791, Nicolas Leblanc invented the Leblanc process, using the sodium sulfate (known as salt cake) obtained from this reaction as a intermediate to yield sodium carbonate (soda ash). Heavy emissions of hydrogen chloride generated in the Mannheim process were vented to the atmosphere, damaging the local environment. The British Parliament passed the 1863 Alkali Act to regulate these emissions; this Act is the first modern air pollution legislation.

In 1861, chemist and industrialist Ernest Solvay developed the Solvay process, a more direct method to obtain sodium carbonate. This soon rendered Leblanc's invention obsolete, as it was both less polluting and required less economic investment.

Chemistry

The reactants in the chemical reaction are sulfuric acid (H₂SO₄) and sodium chloride (NaCl, table salt). The reaction yields sodium sulfate (Na₂SO₄) and gaseous hydrogen chloride (HCl).

2 NaCl + H₂SO₄ → Na₂SO₄ + 2 HCl