Sulfuric acid (alternative spelling sulphuric acid), with the cas number 7664-93-9, is a highly corrosive strong mineral acid with the molecular formula H2 SO4. It is a pungent-ethereal, colorless to slightly yellow viscous liquid which is soluble in water at all concentrations. Sometimes, it may be dark brown as dyed during its industrial production process in order to alert people to its hazards.
Pure sulfuric acid is not encountered naturally on Earth in anhydrous form, due to its great affinity for water. Dilute sulfuric acid is a constituent of acid rain, which is formed by atmospheric oxidation of sulfur dioxide in the presence of water – i.e., oxidation of sulfurous acid. Sulfur dioxide is the main byproduct produced when sulfur-containing fuels such as coal or oil are burned.
Although Sulfuric acid is the common starting raw material, other sources of Sulfuric acid (CAS NO.7664-93-9) can be used, including iron, copper, lead, nickel, and zinc sulfides. Hydrogen sulfide, a by-product of petroleum refining and natural gas refining, can be burned to sulfur dioxide. Gypsum (CaSO4) can also be used but needs high temperatures to be converted to sulfur dioxide. Other uses for it include the manufacture of fertilizers, chemicals, inorganic pigments, petroleum refining, etching, as a catalyst in alkylation processes, in electroplating baths, for pickling and other operations in iron and steel production, in rayon and film manufacture, in the making of explosives, and in nonferrous metallurgy.
Preparation of Sulfuric acid: The manufacture of Sulfuric acid (CAS NO.7664-93-9) by the lead chamberprocess involves oxidation of sulfur to sulfur dioxide by oxygen, further oxidation of sulfur dioxide to sulfur trioxide with nitrogen dioxide, and, finally, hydrolysis of sulfur trioxide.
S + O2 → SO2
2NO + O2→ 2NO2
SO2 + NO2 → SO3 + NO
SO3 + H2O → H2SO4
Modifications of the process include towers to recover excess nitrogen oxides and to increase the final acid concentration from 65% (chamber acid) to 78% (tower acid).
The contact process has evolved to become the method of choice for sulfuric acid manufacture because of the ability of the process to produce stronger acid.
S + O2 → SO2
2SO2 + O2 → 2SO3
SO3 + H2O → H2SO4
In the process, sulfur and oxygen are converted to sulfur dioxide at 1000 °C and then cooled to 420 °C. The sulfur dioxide and oxygen enter the converter, which contains a catalyst such as vanadium pentoxide (V2O5). About 60 to 65% of the sulfur dioxide is converted by an exothermic reaction to sulfur trioxide in the first layer with a 2 to 4-second contact time. The gas leaves the converter at 600°C and is cooled to 400°C before it enters the second layer of catalyst. After the third layer, about 95% of the sulfur dioxide is converted into sulfur trioxide. The mixture is then fed to the initial absorption tower, where the sulfur trioxide is hydrated to sulfuric acid after which the gas mixture is reheated to 420 °C and enters the fourth layer of catalyst that gives overall a 99.7% conversion of sulfur dioxide to sulfur trioxide. It is cooled and then fed to the final absorption tower and hydrated to sulfuric acid. The final sulfuric acid concentration is 98 to 99% (1 to 2% water). A small amount of this acid is recycled by adding some water and recirculating into the towers to pick up more sulfur trioxide.
When you are using this chemical, please be cautious about it as the following:
In case of contact with eyes, rinse immediately with plenty of water and seek medical advice;
Never add water to this product;
In case of accident or if you feel unwell, seek medical advice immediately (show label where possible);
Wear suitable protective clothing and gloves;