Two processes for the production of sulfuric acid are in use today. In their initial steps, both require the use of sulfur dioxide, which is produced by burning iron pyrites, FeS2, or sulfur, in air.

The first of these methods, the lead-chamber process, employs as reaction vessels large lead-sheathed brick towers. In these towers, sulfur-dioxide gas, air, steam, and oxides of nitrogen react to yield sulfuric acid as fine droplets that fall to the bottom of the chamber. Almost all the nitrogen oxides are recovered from the outflowing gas and are brought back to the chamber to be used again. Sulfuric acid produced in this way, and labeled acid, is only about 62 to 70 percent H2SO4. The rest is water. About 20 percent of all sulfuric acid is now made by the lead-chamber process, but that percentage is diminishing.

The second method of manufacturing sulfuric acid, the contact process, which came into commercial use about 1900, depends on oxidation of sulfur dioxide to sulfur trioxide, SO3, under the accelerating influence of a catalyst (see Catalysis). Finely divided platinum, the most effective catalyst, has two disadvantages: It is very expensive, and it is vitiated by certain impurities in ordinary sulfur dioxide that reduce its activity. Many sulfuric-acid producers use two catalysts in tandem; first, a more rugged but less effective one like iron oxide or vanadium oxide to bring about the bulk reaction; then, a smaller amount of platinum to finish the job. At 400 C (752 F), the conversion of sulfur dioxide to trioxide is nearly complete. The trioxide is dissolved in concentrated sulfuric acid, and at the same time a regulated influx of water maintains the concentration at a selected level usually about 95 percent. By reducing the flow of water, a product with more SO3 than shown in the formula H2SO4 may be made. This product, called fuming sulfuric acid, or oleum, or Nordhausen acid, is needed in some organic chemical reactions.

Sulfuric Acid is shipped to large users in ICC 103 type tank cars.
Unloading is thru pumps located at the end users business.
Small users receive theirs in glasslined containers, usually shipped in box cars or trucks


Sulfuric acid is one of the most important industrial chemicals. More of it is made each year than is made of any other manufactured chemical; more than 40 million tons of it were produced in the United States in 1990. It has widely varied uses and plays some part in the production of nearly all manufactured goods. The major use of sulfuric acid is in the production of fertilizers, e.g., superphosphate of lime and ammonium sulfate. It is widely used in the manufacture of chemicals, e.g., in making hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes and pigments, explosives, and drugs. It is used in petroleum refining to wash impurities out of gasoline and other refinery products. Sulfuric acid is used in processing metals, e.g., in pickling (cleaning) iron and steel before plating them with tin or zinc. Rayon is made with sulfuric acid. It serves as the electrolyte in the lead-acid storage battery commonly used in motor vehicles ( acid for this use, containing about 33% H2SO4 and with specific gravity about 1.25, is often called battery acid).
S.A. McCall