Sulphuric acid

We’ll start by answering the question, “What is sulphuric acid?” Sulphuric acid, on the other hand, is a dehydrating agent, an oxidising agent, and a powerful mineral acid. H2SO4 is the chemical formula for sulphuric acid.

The acid is a colourless liquid. It is soluble in water and emits heat when it comes into contact with it. In addition, the acid is corrosive to metals and tissues. It will scorch wood and most other organic matter when it comes into contact with it, but it has little chance of catching fire. The density of the acid is 15 lb/gal. Inhalation of the acid might have harmful effects on one’s health. It is dependent on the rate and concentration of exposure.

The manufacturing process of Sulphuric acid

Because of its broad application in chemical, metallurgical, process, petrochemical, and fertiliser industries, as well as in electrical and electronics, Semiconductor companies, and a variety of labs all over the world, sulphuric acid is the world’s most manufactured chemical. The most common application is in the phosphate industry, as well as in metal extraction. Paint and pigment, explosives, detergents, plastics, and synthetic fibres are just a few of the industries that employ them.

Sulphuric acid is a clear, colourless liquid with a similar look to the water. Its molecular weight is around 98. It has a higher density than water. Sulphuric acid can be diluted with water to make acids of varied strengths for specific applications. Sulphuric acid should be added to water during the mixing procedure.

The reason for this is that because sulfuric acid is heavier than water, it will sink to the bottom and the mixing will be more uniform. In case we add water to sulphuric acid since the water is lighter than sulfuric acid, it will stay at the top.

As a result, the top layer will be water and the bottom layer will be sulfuric acid. Sulphuric acid absorbs water and releases heat at the contact. A small amount of water will evaporate near the interface as a result of the emitted heat. It will turn the water into steam. The steam will expand, splashing the mixture all over the place in an explosion form.

Contact Process produces almost all of the sulphuric acid in the world.

Harmful effect of Sulphuric acid

• Sulphuric acid can cause explosion if presented in concentrated form. 

• If inhaled can cause severe breathing issues resulting in irritation of nose and throat.

• If swallowed, can result in formation of holes in stomach

• Can cause skin burns.

Raw materials used in the Contact process

Sulphur, oxygen, and hydrogen make up sulphuric acid. As a result, the sources of Sulphuric Acid production are naturally those that are rich in certain component compositions. Sulphur elemental, Sulphur Dioxide, or Pyrite can all be used as raw materials. Air and water are also utilised.

Sulphur and Sulphur Dioxide can be found in mines, and Sulphur and Sulphur Dioxide can be found in coal or oil industry stack gases. Desulphurization of petroleum yields sulphur or hydrogen sulphide. Sulphur dioxide can be extracted from pyrite or obtained by smelting metal silicide ores.

Steps involved in the contact process

There are three basic steps in the contact procedure. The oxidation of sulphur-to-sulphur dioxide is the first stage. The catalytic oxidation of sulphur dioxide to sulphur trioxide is the second stage. The hydration of sulphur trioxide to generate sulphuric acid is the third step.

Step-1: Sulphur dioxide gas production

Sulphur dioxide gas is produced by burning sulphur derived from any source. This step must be done with caution to ensure that the air supplied for the combustion process is dry. Any residues of water in the combustion equipment will result in the creation of acid, which will cause corrosion. Sulphur must also be filtered if it includes carbonaceous contaminants. If the gas is not filtered for contaminants, the impurities will pass through the equipment and, if they reach catalysts, they will deactivate them. Sulphur oxidation to sulphur dioxide is a very irreversible reaction.

Step-2: Sulphur trioxide gas production

Vanadium pentoxide is the catalyst utilised in the catalytic oxidation of sulphur dioxide to sulphur trioxide. Before being delivered to the reactor, the sulphur dioxide is cleaned with wet scrubbing to remove any impurities that may be present, and if fine particles are present, the gas is passed via an electrostatic precipitator. Sulphur dioxide to sulphur trioxide oxidation is a reversible reaction. The temperature is kept at 410-430°C and the pressure is kept at 1.2-1.5 atm.

If the temperature rises above 430°C, the equilibrium shifts away from Sulphur Trioxide, making it critical to keep the operating temperature within this range. A four-stage bed reactor is the most common configuration for a catalytic reactor. Because the temperature of the gas climbs from 410-430°C to around 600°C when it passes through one catalyst bed, the gas must be cooled to the optimum temperature before proceeding to the next stage.

Step-3: Sulphuric acid production

Sulphur dioxide should not be allowed to leak into the atmosphere since it not only pollutes the air but also contributes to acid rain. Double absorption helps to ensure that more sulphur dioxide is converted to sulphur trioxide, and it is also advantageous to the process in terms of purity. After three stages, the purity rises to 97-98 percent, and after four stages, it rises to 99.5-99.8%.

The sulphur trioxide is hydrated through absorption in a packed tower filled with a specified range of sulphuric acid. This range is between 98 and 99 percent. If this concentration is too low, sulphur trioxide will not be properly absorbed and will generate a bothersome mist. Vapours become highly substantial inside the tower if the concentration is on the upper side. As a result, it’s critical to maintain a high level of operation concentration. The resulting acid strength can be changed by adjusting the sulphur trioxide and water flow rates. Sulphuric acid concentrations can range from 91 percent to over 100 percent.

Conclusion

The chemical formula of Sulphuric acid is H2SO4. Used as the most important acid in the chemical industries. Sulphuric acid can cause several harmful effects if used without precaution. Reaction of water and Sulphur trioxide result in the formation of Sulphuric acid.Sulphuric acid being a strong acid ionizes completely in aqueous solution.