Preparation of sulfuric acid and its application.

Today, sulfuric acid is produced mainly by two industrial methods: contact and nitric. The contact method is more progressive and in Russia it is applied more widely than the nitrous, that is, the tower.

The production of sulfuric acid begins with calcination of sulfuric raw materials, for example, iron pyrites. In special pyrite furnaces, the so-called calcined gas is obtained, which contains about 9% of sulfur dioxide. This stage is the same for both the contact and nitrosic methods.

Next, it is necessary to oxidize the resulting sulfur dioxide to sulfuric acid. However, it must first be cleaned of a number of impurities that interfere with the further process. The calcined gas is cleaned of dust in electrostatic precipitators or in cyclone units, and then fed into a device containing solid contact masses, where SO ₂ sulfur dioxide is oxidized to sulfur dioxide SO ₃ .

This exothermic reaction is reversible - an increase in temperature leads to the decomposition of the sulfuric anhydride formed. On the other hand, when the temperature is lowered, the rate of the direct reaction is very small. Therefore, the temperature in the contacting apparatus is maintained within 480 ° C, by adjusting it by the rate of passage of the gas mixture.

Later on, the contact method produces sulfuric acid when sulfuric anhydride is combined with water.

The nitroso method is characterized in that sulfur dioxide is oxidized by nitrogen oxides. The production of sulfuric acid by this method is triggered by the formation of sulfuric acid by the interaction of sulfur dioxide from the calcined gas with water. Subsequently, the resulting sulfuric acid is oxidized with nitric acid, which leads to the formation of nitrogen monoxide and sulfuric acid.

This reaction mixture is fed to a special tower. At the same time, by regulating the gas flow, it is achieved that in the gas mixture entering the absorption tower, dioxide and nitrogen monoxide is contained in a ratio of 1: 1, which is necessary for the production of nitrous anhydride.

Finally, the interaction of sulfuric acid and nitrous anhydride produces NOHSO ₄ - nitrosyl sulfuric acid.

The resulting nitrosyl sulfuric acid is fed into the production tower, where it decomposes with water and releases nitrogenous anhydride:

2NOHSO ₄ + H ₂ O = N ₂ O ₃ + 2H ₂ SO _4,

Which also oxidizes sulfurous acid formed in the tower.

Nitric oxide, released as a result of the reaction, again returns to the oxidation tower and enters a new cycle.

At present, in Russia, the production of sulfuric acid is mainly carried out by a contact method. Nitric method is rarely used.

The use of sulfuric acid is very wide and varied.

Most of it goes to the production of chemical fibers and mineral fertilizers, it is necessary in the production of drugs and dyes. With the help of sulfuric acid, ethyl and other alcohols, detergents and pesticides are produced.

Its solutions are used in the textile, food, nitration and explosives industries . Sulfuric sulfuric acid serves as an electrolyte for pouring into lead accumulators, which are widely used in transport.