Cerium, atomic no. 57, symbol Ce, weight at 140.12, is the most abundant of the rare earths. It is strongly acidic and a strong oxidizer.
In glass industry, it is considered to be the most efficient glass polishing agent for precision optical polishing. It is also used to decolorize glass by keeping iron in its ferrous state.
Cerium is also used in a variety of ceramics, including dental compositions and as a phase stabilizer in zirconia-based products.
In catalytic converters Cerium acts as a stabilizer for the high surface area alumina, as a promoter of the water-gas shift reaction, and as an oxygen storage component. It is used in FCC catalysts containing zeolites to provide both catalytic reactivity in the reactor and thermal stability in the regenerator.
In steel manufacturing, it is used to remove free oxygen and sulfur.