Uses

Sulfuric acid production

The most important use of vanadium (V) oxide is in the manufacture of sulfuric acid, an important industrial chemical with an annual production of 165 million metric tons in 2001, with an approximate value of US$8 billion. Vanadium(V) serves the crucial purpose of catalyzing the mildly exothermic oxidation of sulfur dioxide to sulfur trioxide by air in the contact process:

The discovery of this simple reaction, for which V2O5 is the most effective catalyst, allowed sulfuric acid to become the cheap commodity chemical it is today. The reaction is performed between 400 and 620 °C; below 400 °C the V2O5 is inactive as a catalyst, and above 620 °C; it begins to break down. Since it is known that V2O5 can be reduced to VO2 by SO2, one likely catalytic cycle is as follows:

Paradoxically, it is also used as catalyst in the selective catalytic reduction of NOx emissions in some power plants. Due to its effectiveness in converting sulfur dioxide into sulfur trioxide, and thereby sulfuric acid, special care must be taken with the operating temperatures and placement of a power plant's SCR unit when firing sulfur-containing fuels.

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