ChemicalBook > Product Catalog > Inorganic chemistry > Oxides and peroxides > Metal oxide > Molybdenum trioxide
Molybdenum trioxide Chemical Properties
- Melting point:795 °C(lit.)
- Boiling point:1155 °C
- Density 4.692
- Flash point:1155°C subl.
- storage temp. Store at +5°C to +30°C.
- solubility 0.49g/l
- form Sublimed Powder
- Specific Gravity4.69
- color White to gray
- Water Solubility 0.5 g/L (20 ºC)
- Merck 14,6239
- CAS DataBase Reference1313-27-5(CAS DataBase Reference)
- IARC2B (Vol. 118) 2018
- NIST Chemistry ReferenceMolybdenum(vi) oxide(1313-27-5)
- EPA Substance Registry SystemMolybdenum trioxide (1313-27-5)
Molybdenum trioxide Usage And Synthesis
- Chemical PropertiesMolybdenum trioxide is an odorless, white crystalline powder that turns yellow when heated.
Molybdenum trioxide is perhaps the most important compound of molybdenum. Pure molybdenum trioxide is used in chemical and catalyst manufacture. The technical product is added to steel as an alloying agent. Molybdenum trioxide also serves as a catalyst in the petroleum industry and as a component of ceramics, enamels and pigments.
- Physical propertiesSoft white powder; orthorhombic crystals; turns yellow on heating; density 4.69 g/cm3 at 21°C; melts at 795°C without decomposition to a dark yellow liquid; vapor pressure 20 torr at 851°C and 200 torr at 1,014°C; boils at 1,155°C; sparingly soluble in cold water (1.066 g/L at 18°C) and moderately soluble in hot water (20.55 g/L at 70°C); dissolves in acids and alkalies.
- UsesMolybdenum trioxide (MnO3) is a compound used to make enamels adhere to metals.
- UsesMolybdenum(VI) oxide is used in catalyst compositions to carry out desulfurization of petroleum feedstocks and to remove nitrogen-containing compounds from petroleum fractions. Other uses of this oxide include preparation of various molybdate salts and as reagents for chemical analyses.
- UsesChiefly as a reagent for chemical analysis.Used for trace metal analysis.
- PreparationMolybdenum(VI) oxide is obtained by igniting molybdenum or its compounds in air:
2Mo + 3O2 → 2MoO3
2MoS2 + 7O2 → 2MoO3 + 4SO2
MoS2 + 4O2 → MoO3 + SO2 + SO3
Roasting the sulfide is carried out in a multiple-hearth roaster under controlled temperature and airflow. The product mixture is sublimed to obtain high purity oxide.
Purified molybdenum(VI) oxide also is made by prolonged heating of ammonium molybdate in air:
(NH4)2Mo2O7 → 2MoO3 + 2NH3 + H2O
An alternative method involves repeatedly evaporating a mixture of ammonium molybdate and nitric acid. Ammonium nitrate so formed is separated from the product molybdenum(VI) oxide by extraction with water:
(NH4)2Mo2O7 + 2HNO3 → 2MoO3 + 2NH4NO3 + H2O
- General DescriptionColorless to white or yellow odorless solid. Sinks in water.
- Air & Water ReactionsInsoluble in water.
- Reactivity ProfileMolybdenum trioxide reacts violently with chlorine trifluoride, lithium, potassium and sodium. Readily combines with acids and bases to form a series of polymeric compounds. Incompatible with interhalogens and metals. A violent detonation occurs when heated with molten magnesium.
- HazardToxic material.
- Health HazardCompound is relatively nontoxic. Dust irritates eyes.
- Fire HazardFlash point data for Molybdenum trioxide are not available, but Molybdenum trioxide is probably non-flammable.
- Safety ProfilePoison by ingestion, subcutaneous, and intraperitoneal routes. Human systemic effects by inhalation: pulmonary fibrosis and cough. Questionable carcinogen with experimental neoplastigenic data. A powerful irritant. Explodes on contact with molten magnesium. Violent reaction with interhalogens (e.g., bromine pentafluoride, chlorine trifluoride). Incandescent reaction with hot sodium, potassium, or lithium. When heated to decomposition it emits toxic fumes of Mo.
- Potential ExposureMolybdenum trioxide is used in agriculture; manufacture of metallic molybdenum, ceramic glazes; enamels, pigments, and in analytical chemistry.
- ShippingUN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.
- Purification MethodsCrystallise it from water (1g/50mL) between 70o and 0o. The solubility in H2O is 0.1% at 18o, and 2% at 70o. It is a white powder which turns yellow reversibly on heating. It sublimes readily at 1155o/760mm. [Hein & Herzog Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1412 1965.]
- IncompatibilitiesExplodes on contact with molten magnesium. Violent reaction with strong oxidizers, such as chlorine trifluoride; bromine pentafluoride. Not compatible with strong acids; active metals (sodium, potassium, lithium).
Molybdenum trioxide Preparation Products And Raw materials
- Preparation ProductsFormaldehydeBenzaldehydeButylamineMOLYBDENUM(IV) SULFIDEAmmonium molybdate tetrahydrateAMMONIUM MOLYBDATEHigh temperature shift calalystMolybdenumSodium molybdate Sodium molybdate dihydrateZINC MOLYBDATEPHOSPHOMOLYBDIC ACIDAMMONIUM PHOSPHOMOLYBDATESODIUM PHOSPHOMOLYBDATE
- Raw materialsAmmonium molybdate tetrahydrateAMMONIUM MOLYBDATEHexaammonium molybdate Ammonium octamolybdate
- Chromium(III) oxide Ammonium metavanadate COPPER MOLYBDENUM OXIDE BISMUTH MOLYBDENUM OXIDE Aluminum molybdenum oxide, 99% (metals basis) LEAD MOLYBDENUM OXIDE COBALT(II) MOLYBDENUM OXIDE CESIUM MOLYBDENUM OXIDE MOLYBDENUM TRIOXIDE ACS REAGENT SILVER MOLYBDENUM OXIDE AMMONIUM 6-MOLYBDOALUMINATE COBALT OXIDE MOLYBDENUM OXIDE COBALT OXIDE-MOLYBDENUM OXIDE ON ALUMINA zirconium molybdate AMMONIUM MOLYBDENUM OXIDE (PARA) SODIUM-2-PHOSPHO-18-MOLYBDATE AMMONIUM 9-MOLYBDONICKELATE IV AMMONIUM 6-MOLYBDONICKELATE II
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