Cerium is a silver-gray active metal, powder in air easily spontaneous combustion, readily soluble in acids. It is found mainly in monazite and bastesite, but also in the fission products of uranium, thorium and plutonium. It is often prepared from cerium oxide reduced by magnesium powder, or from molten cerium chloride by electrolysis. It contains about 0.0046% in the earth's crust and is the most abundant of rare earth elements.

Strictly speaking, the initial discovery of "cerium soil" can only be regarded as the enrichment of cerium, or is associated with lanthanum praseodymium neodymium and other light rare earth mixed oxides, lanthanum praseodymium neodymium and other hidden in "cerium soil" was not found at that time. But in any case, cerium is the most recognizable of rare earth's 17 similar-looking twins. Because cerium has a remarkable chemical property, in addition to the usual trivalent state of other rare earth elements, it will also be stable in a quadruvalent state. This difference in the valence state of the ion inevitably enlarges the difference in the chemical properties, which makes it easier to separate cerium from other neighboring rare earth elements, and hence the chemical extraction of cerium. This makes it easy for chemists to extract and understand cerium, plus it is abundant and easy to extract and cheaper than other rare earth products, making it one of the first rare earths to have practical uses.
 

A lively silver-gray metal. Electron shell structure [Xe]4f15d16s2. [6] First ionization energy 527.4kJ/mol. [4]

It can be burned in air by scraping with a knife (pure cerium is not prone to spontaneous combustion, but is prone to spontaneous combustion when slightly oxidized or alloyed with iron); When heated, it burns in the air to form cerium dioxide. Can interact with boiling water, soluble in acid, insoluble in alkali. When exposed to low temperatures and high pressures, a diamagnetism emerges that is 18% denser than the common cerium form. Cerium is the most abundant of the rare earth metals.

Common valence: +3,+4

Electronegativity: 1.12

Peripheral electron configuration: 4f15d16s2

Electron configuration: 2,8,18,19,9,2

First ionization energy: 528kJ·mol-1

Second ionization energy: 1047kJ·mol-1

Third ionization energy: 1880kJ·mol-1

Elemental density: 6.773g/cm3

Elemental melting point: 795ºC

Elemental boiling point: 3443ºC

Atomic radius: 2.7 angstroms

Ionic radius: 1.14 (+3) angstroms

Covalent radius: 1.65 angstroms

Main use of editing broadcast

1, used as reducing agent, catalyst.

2, used as alloy additives, and used in the production of cerium salt, also used in medicine, leather, glass, textile and other industries.

3, cerium can be used as catalyst, arc electrode, special glass, etc. Cerium is a heat-resistant alloy that can be used to make jet propulsion parts.

Environmental protection material

Cerium is also used as an excellent environmental material [5], the most representative application is the catalyst for automobile exhaust gas purification. Cerium is added to the commonly used ternary catalyst of precious metals (platinum, rhodium, palladium, etc.), which can improve the performance of the catalyst and reduce the amount of precious metals. The main pollutants of automobile exhaust are carbon monoxide, hydrocarbons and nitrogen oxides, which will affect the hematopoietic function of human body, form photochemical toxic smog and produce carcinogens, which will cause damage to human, animals and plants. Three-way purification catalytic technology can make hydrocarbons and carbon monoxide fully oxidized to carbon dioxide and water, so that nitrogen oxides are decomposed into nitrogen and oxygen (hence the name of three-way catalysis). Platinum, rhodium, palladium and other precious metals are excellent catalytic materials for tail gas purification. However, their high cost and high requirements for both engine and gasoline limit their wide application. The addition of cerium in catalyst can significantly reduce the amount of precious metal and improve the catalytic performance, so that the price of catalytic converter is greatly reduced. In the United States, catalysts for vehicle exhaust purification have become the number one consumer of rare earths. Cerium oxide can also be made with nano titanium oxide photocatalyst, used in antibacterial ceramics and oxygen - rich ion environmental coatings.

Harmful metal substitution

Cerium sulfide can replace lead, cadmium and other metals that are harmful to the environment and humans as red colorants for plastics. It can also be used in paint, ink and paper industries. Rhodia holds the leading technology. Cerium-rich light rare earth naphthenate and other organic compounds are also used in paint dryers, PVC plastic stabilizers and MC nylon modifiers, which can both replace highly toxic substances such as lead salt and reduce expensive materials such as drilling salt.

Special functional material

Cerium is also used in the manufacture of many special functional materials, such as fluorescent grade cerium oxide used in the manufacture of three primary color phosphor green powder for lamps; The CeLiSAF laser system solid-state laser, developed in the United States, can be used to detect biological weapons by monitoring tryptophan concentrations, as well as for medical applications. Cerium can be used to make cerium drill copper iron permanent magnet material; Cerium pigeon electrode can replace the radioactive thorium pigeon electrode.

Plant growth regulator

Cerium - based light rare earth as plant growth regulator can improve crop quality, yield and stress resistance. As a feed additive, it can improve the laying rate of poultry, the survival rate of fish and shrimp breeding, and improve the wool quality of long-haired sheep. Cerium is a low-toxicity substance, and an American book on rare earth said that feeding tests on mice showed that cerium-rich light rare earth oxides were as toxic by mouth as table salt. So far, no endemic diseases caused by rare earth have been found in rare earth rich areas. Through a large number of experimental studies, Chinese scientists believe that the agricultural use of rare earth will not cause environmental pollution and harm the survival of humans and animals.

Storage method editor broadcast

Store in a cool, ventilated warehouse. Keep away from fire and heat. The temperature of the warehouse should not exceed 30ºC. The package should be sealed and not in contact with air. It should be stored separately from oxidants, acids, halogens and edible chemicals, and should not be mixed. Explosion-proof lighting and ventilation facilities are adopted. Do not use mechanical equipment and tools that are prone to spark. The storage area should be equipped with leak emergency treatment equipment.