Supported tungsten carbide material
AssigneeOsram Sylvania Inc.
InventorsJoel B. Christian, Tuan A. Dang, Robert G. Mendenhall
Life of this patent
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Abstract
A supported tungsten carbide material is provided. The material has a unique structure as defined by its x-ray diffraction pattern and consists of extremely small crystallites on the order of about 15 to about 30 angstroms in size. The tungsten carbide material is supported on a high-surface-area support to allow for a greater number of active sites for catalysis. The support consists preferably of a high-surface-area carbon.
Claims28
A method for forming a supported tungsten carbide material comprising:
- forming a mixture of a high-surface area support and a tungsten precursor selected from ammonium metatungstate, ammonium paratungstate, ammonium tungstate, sodium tungstate, or tungsten oxides;
- and, heating the mixture to a temperature from about 500° C. to about 800° C. in an atmosphere containing a hydrocarbon gas and, optionally, hydrogen gas for a time sufficient to convert the tungsten precursor to the tungsten carbide material.
A method for forming a supported tungsten carbide material comprising:
- forming an aqueous solution of ammonium metatungstate, mixing the solution with a high-surface-area support, adjusting the pH of the solution to promote the formation of ammonium paratungstate, allowing the solution to set to form crystals of ammonium paratungstate, separating the solid material from the solution, and drying the solids to form a mixture of ammonium paratungstate and a high-surface area support, heating the mixture to a temperature from about 500° C. to about 800° C. in an atmosphere containing a hydrocarbon gas and, optionally, hydrogen gas for a time sufficient to convert the tungsten precursor to the tungsten carbide material.
A method for forming a supported tungsten carbide material comprising:
- forming a mixture of a tungsten precursor selected from ammonium paratungstate or ammonium metatungstate and a high-surface-area support selected from a high-surface-area carbon or a high-surface-area alumina;
- heating the mixture to a temperature from about 500° C. to about 800° C. in an atmosphere containing a hydrocarbon gas and, optionally, hydrogen gas for a time sufficient to convert the tungsten precursor to the tungsten carbide material;
- the tungsten carbide material comprising tungsten and carbon;
- the material having an x-ray diffraction pattern containing a primary x-ray diffraction peak and first and second secondary x-ray diffraction peaks, the primary x-ray diffraction peak having a reflection angle corresponding to a d-spacing of 2.39±0.02 Å, the first secondary x-ray diffraction peak having a reflection angle corresponding to a d-spacing of 1.496±0.007 Å and a relative peak height of 25% to 40% of the peak height of the primary x-ray diffraction peak, and the second secondary x-ray diffraction peak having a reflection angle corresponding to a d-spacing of 1.268±0.005 Å and a relative peak height of 35% to 55% of the peak height of the primary x-ray diffraction peak.
Dependencies are inferred from the claim text.