Mo2C Molybdenum Carbide Powder

Mo2C Molybdenum Carbide Powder

Chinese name: molybdenum carbide

Foreign name: Molybdenum Carbide

Chemical formula: Mo2C

Molecular weight: 107.95 CAS

CAS: 12011-97-1

EINECS Login No. 234-569-3

Melting point: 2692 ℃

Density 9,18 g/cm3

Appearance: grey black to grey

Properties: At present, chemical methods for preparing molybdenum carbide mainly include compound pyrolysis, temperature programmed reaction, high-temperature carbon reduction of molybdenum oxide, and gas phase reaction of volatile metal molybdenum compounds. At present, the temperature programmed reaction (TPRe) method is widely used, which takes the transition metal oxide, carbon source and hydrogen mixture as raw materials, through the Chemicalbook process similar to the temperature programmed reduction process, and makes the transition metal oxide go through the reaction process of reduction and carbonization (carburization) at the set temperature. Common carbon source materials include methane, ethane, ethylene or carbon oxides (CO, CO2), etc. The reaction temperature is generally controlled at 400~1000 ℃. Liang et al. used high surface area carbon materials as carbon sources to synthesize nano molybdenum carbide by temperature programmed reduction.

1. The programmed temperature rise method is to prepare MoO3 by heating ammonium molybdate at 500 ℃. The alumina carrier is immersed in ammonium molybdate and ammonia solution, stirred for 0.5h, placed at room temperature for 24h, evaporated in 80~90 ℃ water bath, dried at 115 ℃ for 12h, and calcined at 500 ℃ for 4h to prepare the supported molybdenum trioxide precursor. Molybdenum carbide was prepared with n-hexane as carbonization material by temperature programmed method. The temperature programmed process is as follows: from room temperature to 300 ℃, the temperature rise rate is 10 ℃/min; From 300 ℃ to 600 ℃, the heating rate is 1 ℃/min; Keep the temperature constant for 2h at 600 ℃.

2. Gas phase method The gas phase method generally adopts the process of high specific surface active carbon (specific surface area is more than 200m2/g) and transition metal volatile compounds, which are fed into the flowing reactor in stoichiometric proportion, reacting for a certain time under high temperature of 900~1400 ℃, cooling and recovering carbide in inert gas. The mixture of high specific surface carbon and MoO3 is heated to 800 ℃ in argon, so that MoO3 is sublimated and adsorbed on carbon, and is heated to 1300 ℃ to react for a certain time to prepare Mo2C. It is reported that hexacrystalline Mo2C can be obtained by reacting MoO3 and 1150m2/g carbon with C/Mo molar Chemicalbook ratio of 6:1, and its specific surface can reach 213m2/g. Leclercq et al. evaporate volatile metal compounds into containers containing low pressure carbon hydrides and directly carbonize them at high temperatures to form carbides. Different carbides and carbon oxides were prepared by changing the gas composition and the type of metal compound precursor in the reactor. Nagai et al. used this method to prepare Mo2C/Al2O3 catalyst with activity 3 times higher than that of immersion method under 973K vacuum condition. However, the disadvantage of this method is that the conditions are not easy to control and the synthesis amount is small.

3. Thermal decomposition method Thermal decomposition method refers to the process of using transition metal oxides or halides to react with designated organics, first forming metal organics, and then conducting thermal decomposition reaction of organics in an inert atmosphere. Bayer Company uses it to react with organic compounds containing two hydroxyl groups, remove excessive organic compounds, and decompose them into metal carbides under vacuum or inert gas. SeChemicalbookhwartzkopf and others directly carbonize metal oxide powder at high temperature, but the specific surface area of the obtained sample is low. At present, the preparation of molybdenum carbide is developing towards the practical type with high specific surface area and high dispersion.

4. Liquid phase reaction method Low temperature liquid phase reaction method: it refers to dissolving a series of substances in a suitable solvent to allow them to undergo chemical reactions so as to conduct chemical reactions under relatively mild conditions.

application

1) Production of molybdenum alloys. Molybdenum zirconium titanium alloy and molybdenum titanium zirconium carbon alloy are widely used in electronic tubes, electric light source parts, metal processing tools, turbine disks and other components due to their high strength, good conductivity and thermal conductivity and low thermal expansion coefficient.

2) As an additive to steel. The role of molybdenum in stainless steel is to improve the corrosion resistance, strength and weldability of products.

3) As the heating electrode in the glass smelting furnace. Molybdenum has good compatibility with most glass components, and will not produce harmful substances because a small amount of molybdenum is dissolved in the glass bath

4) The main catalytic reaction types of molybdenum carbide catalyst are: (1) hydrolysis reaction; (2) Hydrodesulfurization HDS and hydrodenitrogenation HDN reactions; (3) Isomerization reaction; (4) Hydrocarbon conversion and synthesis reaction; (5) Application in ammonia synthesis.