CAS Number 1317-33-5
· Linear Formula MoS2
Molybdenum disulfide is the inorganic
compound composed of only two elements: molybdenum and sulfur. Its chemical formula is MoS2.
Detailed description
The
compound is classified as a metal dichalcogenide. It is a silvery black solid that occurs as
the mineral molybdenite, the principal ore for molybdenum.[6] MoS
2 is relatively unreactive. It is unaffected by dilute acids and oxygen. In appearance and feel, molybdenum disulfide is similar to graphite. It is widely used as a solid lubricant because of its low friction properties and robustness. Bulk MoS
2 is a diamagnetic, indirect bandgap semiconductor similar to silicon, with a bandgap of 1.23 eV.
2 is relatively unreactive. It is unaffected by dilute acids and oxygen. In appearance and feel, molybdenum disulfide is similar to graphite. It is widely used as a solid lubricant because of its low friction properties and robustness. Bulk MoS
2 is a diamagnetic, indirect bandgap semiconductor similar to silicon, with a bandgap of 1.23 eV.
Applications
Lubricant
MoS
2 with particle sizes in the range of 1–100 µm is a common dry lubricant.[21] Few alternatives exist that confer high lubricity and stability at up to 350 °C in oxidizing environments. Sliding friction tests of MoS
2 using a pin on disc tester at low loads (0.1–2 N) give friction coefficient values of <0.1.
2 with particle sizes in the range of 1–100 µm is a common dry lubricant.[21] Few alternatives exist that confer high lubricity and stability at up to 350 °C in oxidizing environments. Sliding friction tests of MoS
2 using a pin on disc tester at low loads (0.1–2 N) give friction coefficient values of <0.1.
MoS
2 is often a component of blends and composites that require low friction. For example, it is added to graphite to improve sticking.[20]A variety of oils and greases are used, because they retain their lubricity even in cases of almost complete oil loss, thus finding a use in critical applications such as aircraft engines. When added to plastics, MoS
2 forms a composite with improved strength as well as reduced friction. Polymers filled with MoS
2 include nylon (with the trade name Nylatron), Teflon and Vespel. Self-lubricating composite coatings for high-temperature applications consist of molybdenum disulfide and titanium nitride, using chemical vapor deposition.
2 is often a component of blends and composites that require low friction. For example, it is added to graphite to improve sticking.[20]A variety of oils and greases are used, because they retain their lubricity even in cases of almost complete oil loss, thus finding a use in critical applications such as aircraft engines. When added to plastics, MoS
2 forms a composite with improved strength as well as reduced friction. Polymers filled with MoS
2 include nylon (with the trade name Nylatron), Teflon and Vespel. Self-lubricating composite coatings for high-temperature applications consist of molybdenum disulfide and titanium nitride, using chemical vapor deposition.
Examples of
applications of MoS
2-based lubricants include two-stroke engines (such as motorcycle engines), bicycle coaster brakes, automotive CV and universal joints, ski waxes,[24] and even bullets.[25]
2-based lubricants include two-stroke engines (such as motorcycle engines), bicycle coaster brakes, automotive CV and universal joints, ski waxes,[24] and even bullets.[25]
Catalysis
MoS
2 is employed as a cocatalyst for desulfurization in petrochemistry, for example, hydrodesulfurization.The effectiveness of the MoS
2 catalysts is enhanced by doping with small amounts of cobalt or nickel The intimate mixture of these sulfides is supported on alumina. Such catalysts are generated in situ by treating molybdate/cobalt or nickel-impregnated alumina with H
2S or an equivalent reagent. Catalysis does not occur at the regular sheet-like regions of the crystallites, but instead at the edge of these planes.[26]
2 is employed as a cocatalyst for desulfurization in petrochemistry, for example, hydrodesulfurization.The effectiveness of the MoS
2 catalysts is enhanced by doping with small amounts of cobalt or nickel The intimate mixture of these sulfides is supported on alumina. Such catalysts are generated in situ by treating molybdate/cobalt or nickel-impregnated alumina with H
2S or an equivalent reagent. Catalysis does not occur at the regular sheet-like regions of the crystallites, but instead at the edge of these planes.[26]
MoS2 also finds some use as a hydrogenation catalyst for organic
synthesis.[27] Being derived from a common transition
metal, rather than group
10 metal like many alternatives,
MoS2 is chosen when catalyst price or resistance to sulfur poisoning are of primary concern. MoS2is effective for the
hydrogenation of nitro
compounds to amines and can be used produce secondary amines via reductive alkylation.[28]The catalyst can also can effect hydrogenolysis of organosulfur compounds, aldehydes, ketones, phenols, and carboxylic
acids to their respective alkanes.[27] The catalyst suffers from rather low activity however, often
requiring hydrogen pressures above 95 atm and temperatures above 185 °C.
PRICE
$42629.21/KG OR $19376.91/IB
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