To make sulfuric acid chemicals are heated in order to speed up the process of binding sulfur to hydrogen. In almost every industrialized nation on the earth, sulfuric acid is used to make a large number of various products and processes possible. Before the mid 1700s, the production of sulfuric acid was limited to small amounts created in a few glass bottles. Now, it is the most widely manufactured chemical in the world. Most of the contemporary production of sulfuric acid made using the contact process. Another method used to produce sulfuric acid by condensing the water from cooling sulfur trioxide gas is the wet process.
Before 1746, sulfuric acid was produced in glass bottles and could only be made in very small amounts. John Roebuck created the lead chamber manufacturing process for the production of sulfuric acid which could produce acid by the ton. This process revolutionized the production of sulfuric acid, making it available for widespread industrial use. The original process, used as recently as 1946, involved igniting sulfur and potassium nitrate in a lead-foil lined room with water covering the floor. The resulting sulfur trioxide would react with the water producing sulfuric acid.
Today, most sulfuric acid is produced using the contact process, also known as double contact double absorption (DCDA) process. This process involves burning solid sulfur dioxide to make sulfur dioxide gas. This sulfur dioxide gas is then combined with air and heated to about 450 degrees F (232 degrees C) and pressurized with a vanadium oxide catalyst, which produces sulfur trioxide. Also referred to as oleum, this sulfur trioxide is then dissolved in 98% sulfuric acid resulting in disulfuric acid. Water is added to the disulfuric acid to produce sulfuric acid.
The wet sulfuric acid process (WSA) is also used in the production of sulfuric acid. Similar to the contact process, the wet process involves burning sulfur or hydrogen sulfide gas to produce sulfur dioxide. As in the contact process, the sulfur dioxide is then combined with oxygen and a vanadium oxide catalyst to produce sulfur trioxide. The sulfur trioxide is then hydrated into sulfuric acid and eventually condensed down to the desired 97% to 98% concentration. The basic difference between the contact process and the wet process is the different way in which water is used.
Demand for the production of sulfuric acid continues to rise about 3% every year as it is part of many industrial processes. It is estimated that between 165 and 200 million tons of sulfuric acid are produced every year. Fertilizer used in agriculture takes about 65% of this amount. It is also used in many other processes including the production of dyes, plastics, explosives, and pharmaceuticals.