Cerium is a lively silver-gray metal. Electronic layer
structure [Ce]4f15d16s2. The first ionization energy is 527.4KJ/mol.
It can be burned in the air by scraping with a knife (pure cerium is not easy to ignite spontaneously, but it is very easy to ignite when it is slightly oxidized or alloyed with iron); when heated, it burns in the air to generate cerium dioxide. Can interact with boiling water, soluble in acid but insoluble in alkali. When subjected to low temperature and high pressure, a diamagnetic body appears, which is 18% denser than the ordinary form of cerium. Cerium is the most abundant metal element among rare earth elements. There are four isotopes: Ce, Ce, Ce, Ce. Ce is a radioactive alpha emitter with a half-life of 5×10^15 years.
1. Used as reducing agent and catalyst.
2. Used as alloy additive, and used in the production of cerium salt, etc., and also used in medicine, leather making, glass, textile and other industries. 
3. Cerium can be used as catalyst, arc electrode, special glass, etc. Cerium alloy is resistant to high heat and can be used to make jet propulsion parts.
Specific examples are as follows:
Environmental protection materials
Cerium is also used as an excellent environmentally friendly material , and the most representative application is a catalyst for purifying automobile exhaust. Adding cerium to the commonly used noble metal (platinum, rhodium, palladium, etc.) three-way catalyst can improve the performance of the catalyst and reduce the amount of noble metal. The main pollutants of automobile exhaust are carbon monoxide, hydrocarbons and nitrogen oxides, which can affect human hematopoiesis Functions, forming photochemical toxic smoke and producing carcinogens, which can cause damage to humans, animals and plants. The three-way purification catalytic technology can fully oxidize hydrocarbons and carbon monoxide to produce carbon dioxide and water, and decompose nitrogen oxides into nitrogen and oxygen (hence the name three-way catalysis). Noble metals such as platinum, rhodium and palladium are excellent catalytic materials for exhaust gas purification. However, they are expensive and have high requirements on engines and gasoline, which limit their wide application. Adding cerium to the catalyst can significantly reduce the amount of precious metals and improve the catalytic performance, so that the price of the catalytic converter is greatly reduced. In the United States, automobile exhaust purification catalysts have become the largest consumer of rare earths. Cerium oxide can also be combined with nano-titanium oxide to make photocatalysts, which can be used in antibacterial ceramics and oxygen-rich environment-friendly coatings.
Hazardous metal substitution
Cerium sulfide can replace lead, cadmium and other metals that are harmful to the environment and humans as a plastic red colorant. It can also be used in industries such as paint, ink and paper. The French Rhodia company has the leading technology. Organic compounds such as cerium-rich light rare earth naphthenates are also used in paint driers, PVC plastic stabilizers and MC nylon modifiers, etc., which can not only replace lead salts and other toxic substances, but also reduce drilling salts, etc. Expensive materials.
Special functional materials
Cerium is also used to make many special functional materials, such as fluorescent grade cerium oxide green powder (CeMgA111O19:Tb3+) used to make three primary color phosphors for lamps; Ce:LiSAF laser system solid-state laser developed in the United States through monitoring tryptophan Concentration can be used to detect biological weapons and can also be used in medicine. Metal cerium can be used to make cerium diamond copper-iron permanent magnet materials; cerium pigeon electrodes can replace radioactive thorium pigeon electrodes, and so on.
Plant Growth Regulator
Cerium-based light rare earths can be used as plant growth regulators to improve crop quality, increase yield and increase crop resistance. Used as a feed additive, it can increase the egg production rate of poultry and the survival rate of fish and shrimp breeding, and it can also improve the wool quality of long-haired sheep. Cerium is a low-toxic substance. It is known as a rare earth monograph in the United States. Feeding experiments on rats showed that the oral toxicity of cerium-rich light rare earth oxides is equivalent to oral salt. So far, endemic diseases caused by rare earths have not been found in rare earth-rich areas. Chinese scientists believe through a large number of experimental studies that the agricultural use of rare earths will not cause environmental pollution and will not harm the survival of humans and animals.