molybdenum

Molybdenum is a chemical element with the symbol Mo and atomic number 42. It is a transition metal in group 6 and is known for a very high melting point, around 2,623 degrees Celsius, and a dense, strong, corrosion-resistant metal. Molybdenum forms a variety of compounds, most commonly as oxides and sulfides, and it exhibits several oxidation states, especially +4 and +6 as molybdate (MoO4^2−).

In nature, molybdenum occurs mainly in the mineral molybdenite (MoS2), which is the principal ore. Other minerals include wulfenite and powellite. Major producers include regions rich in molybdenite deposits. Industrially, ore is mined, concentrated, and converted to MoO3, which is then reduced to metallic molybdenum or used to make alloys. Pure Mo can be produced by hydrogen reduction or other metallurgical methods and is subsequently used in various alloys and compounds.

Molybdenum’s principal use is in steel and other alloys. It strengthens stainless steels, high-strength low-alloy steels, and superalloys, improving hardenability and high-temperature performance. Molybdenum disulfide (MoS2) serves as a solid lubricant. Molybdenum-based catalysts are important in petroleum refining and chemical processing, including hydrodesulfurization and other reactions. Molybdenum oxides are used in catalysts and pigments in some applications.

Biologically, molybdenum is an essential trace element for many organisms, including humans, where it is part of several enzymes such as xanthine oxidase and sulfite oxidase. In humans, inadequate intake can impair these enzymes, while typical exposure at normal dietary levels is considered safe. A notable radiochemical application is the isotope molybdenum-99, which decays to technetium-99m for widespread medical imaging; Mo-99/99mTc generators are widely used in diagnostic nuclear medicine.