Methods for production of molybdenum carbide

Details Methods for production of molybdenum carbide Methods for production of molybdenum carbide

2001-11-07

2004-06-08

Bos, Steven (Department: 1754)

Chemistry of inorganic compounds

Silicon or compound thereof

Binary compound

C423S440000, C502S177000

Reexamination Certificate

active

06746656

ABSTRACT:

FIELD OF THE INVENTION
The invention generally pertains to molybdenum carbides, and more specifically, to apparatus and methods for production of molybdenum carbide.
BACKGROUND OF THE INVENTION
Hydrogen reacts with oxygen to generate energy while producing water instead of the pollutants typically associated with the combustion of fossil fuels. Therefore, hydrogen is potentially a significant source of “clean” energy. Among other uses, hydrogen is also used on an industrial basis for chemical synthesis (e.g., methanol and ammonia synthesis).
Sources of hydrogen include methane, a significant component of relatively abundant natural gas. Processes such as steam reforming and dry reforming of methane may be used to produce hydrogen gas and carbon monoxide. However, the catalysts required for these reactions are typically made of expensive noble metals, such as elemental gold, platinum, iridium, ruthenium, and nickel. In addition, these catalysts must be replaced frequently as they tend to become plugged and eventually deactivated by carbon deposits. Molybdenum carbides (MoC and/or Mo
2
C) have been shown to be a viable and less expensive alternative to noble metal catalysts for a variety of reactions, including oxidation of methane to form hydrogen gas.
Various processes have been developed for producing molybdenum carbide. According to one such process for producing Mo
2
C, ammonium molybdate powder is loaded into a quartz liner and placed into a rotary kiln. The system is first purged with nitrogen, then a hydrogen and carbon monoxide mixture is introduced. Initially, the temperature is set to 300° C. to decompose the ammonium molybdate. Thereafter, the temperature may only be ramped between 2° C. and 20° C. per minute. The Mo
2
C forms during a three to five hour soak at a temperature between 550° C. and 600° C. The reactor is then cooled, and the Mo
2
C powder may be passivated with diluted oxygen or air after the powder cools to room temperature.
However, this process for producing molybdenum carbide requires the temperature ramp rate not exceed 20° C. per minute, and is thus a time-consuming process. In addition, this is a batch process, which slows production and increases production costs.
SUMMARY OF THE INVENTION
An embodiment of a method for producing molybdenum carbide may comprise the steps of: heating a precursor material in a first heating zone in the presence of a reducing gas and a carbonizing gas, the first heating zone having a first temperature; and moving the precursor material into a second heating zone to form the molybdenum carbide from the precursor material, the second heating zone having a second temperature, the second temperature being at least 100° C. hotter than the first temperature.


REFERENCES:
patent: 2402084 (1946-06-01), Rennie
patent: 3077385 (1963-02-01), Robb
patent: 4331544 (1982-05-01), Takaya et al.
patent: 4515763 (1985-05-01), Boudart et al.
patent: 4851206 (1989-07-01), Boudart et al.
patent: 6042370 (2000-03-01), Weide
patent: 6207609 (2001-03-01), Gao et al.
patent: 1088788 (2001-04-01), None
patent: 1162281 (2001-12-01), None
Search Report in corresponding EPO Patent Application Serial No. 02022648.6-2122 of Cyprus Amax Minerals Company.
“Molybdenum Carbide Catalysts; II. Topotactic Synthesis of Unsupported Powders,” Lee, J. S., et al., 6113 Journal of Catalysis, vol. 112 (Jul. 1988), No. 1, pp. 44-53.
Studies in Inorganic Chemistry 19, “Molybdenum: An Outline of its Chemistry and Uses” by E.R. Braithwaite and J. Haber, 1994, pp. 14-15, 25-26, 73-75, 147, 148, 150.

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