CONTACT PROCESS

The Contact Process is the manufacture of sulfuric acid in the high concentrations needed for industrial process.
The process can be divided into five stages

1. Combining of sulfur and oxygen (O2) to form sulfur dioxide.
2. Purifying the sulfur dioxide in a purification unit.
3. Adding an excess of dioxygen to sulfur dioxide in the presence of the catalyst Vanadium pentoxide, under temperature  450 °C and pressure of 1-2 atm.

4. The sulfur trioxide formed is added to sulfuric acid which gives rise to  oleum (disulfuric acid)

5. The oleum is then added to water to form sulfuric acid which is very concentrated