US4851206A — Methods and compostions involving high specific s…

Claim 1

Independent Claim 279 words

A high specific surface area metal carbide or nitride, wherein said metal is molybdenum, tungsten, titanium, chromium, zirconium, niobium, vanadium, tantalum, hafnium, or rhenium, said carbides and nitrides being prepared from the respective metal oxides and resulting in at least a 5-fold increase in surface area over that of said oxide, produced by a method which comprises: heating said oxide substantially uniformly and continuously at a rate in the range of 0.1° to 5° C./min for at least 20 minutes in the presence of a reducing environment and a source of carbon or nitrogen from a temperature at least 25° C. prior to substantial completion of formation of said carbide or nitride, and through a temperature range wherein reduction of said oxide and reaction with carbon or nitrogen of said source occurs to form a carbide or nitride reaction product, respectively, whereby an effluent is formed comprising an unreacted portion of said source and gases resulting from reaction of said source with said oxide, and wherein said heating continues to a final temperature until said reaction is substantially complete as evidenced by the substantial absence of change in the composition of said effluent; lowering the temperature of the reaction product by at least 25° C. by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about one hour or about 50 percent of the time of said heating; and wherein said carbide or nitride is characterized by a particle of a size in the range of about 1 to 15 nm and having a specific surface area of at least about 40 m 2 /g when measured by BET method.

Claim 2

Dependent Claim 279 words

A high specific surface area metal carbide or nitride, wherein said metal is molybdenum, tungsten, titanium, chromium, zirconium, niobium, vanadium, tantalum, hafnium, or rhenium, said carbides and nitrides being prepared from the respective metal oxides and resulting in at least a 5-fold increase in surface area over that of said oxide, produced by a method which comprises: heating said oxide substantially uniformly and continuously at a rate in the range of 0.1° to 5° C./min for at least 20 minutes in the presence of a reducing environment and a source of carbon or nitrogen from a temperature at least 25° C. prior to substantial completion of formation of said carbide or nitride, and through a temperature range wherein reduction of said oxide and reaction with carbon or nitrogen of said source occurs to form a carbide or nitride reaction product, respectively, whereby an effluent is formed comprising an unreacted portion of said source and gases resulting from reaction of said source with said oxide, and wherein said heating continues to a final temperature until said reaction is substantially complete as evidenced by the substantial absence of change in the composition of said effluent; lowering the temperature of the reaction product by at least 25° C. by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about one hour or about 50 percent of the time of said heating; and wherein said carbide or nitride is characterized by a particle of a size in the range of about 1 to 15 nm and having a specific surface area of at least about 40 m 2 /g when measured by BET method.

Claim 3

Dependent Claim 14 words

A metal carbide or nitride according to claim 1, wherein said metal is molybdenum.

Claim 4

Dependent Claim 14 words

A metal carbide or nitride according to claim 1, wherein the metal is tungsten.

Claim 5

Dependent Claim 14 words

A metal carbide or nitride according to claim 1, wherein said metal is vanadium.

Claim 6

Dependent Claim 12 words

A metal carbide according to claim 1, wherein said metal is molybdenum.

Claim 7

Dependent Claim 12 words

A metal nitride according to claim 1, wherein said metal is molybdenum.

Claim 8

Dependent Claim 12 words

A metal carbide according to claim 1, wherein said metal is tungsten.

Claim 9

Dependent Claim 12 words

A metal nitride according to claim 1, wherein said metal is tungsten.

Claim 10

Independent Claim 112 words

A method for preparing a thermodynamically metastable metal carbide, wherein said metal is molybdenum, vanadium, tungsten, titanium, chromium, zirconium, niobium, tantalum, hafnium, rhenium, said method comprising: heating a nitride having a particle size in the range of about 1 to 15 nm and a specific surface area of at least about 40 m 2 /g when measured by BET method in the presence of a carbon source at a temperature in the range of about 500°-1500° C. for a sufficient time to substantially displace all of the nitrogen with carbon, wherein a thermodynamically metastable carbide is formed; and isolating said thermodynamically metastable carbide having substantially the same crystal structure as said nitride.

Claim 11

Independent Claim 112 words

A method for preparing a thermodynamically metastable metal carbide, wherein said metal is molybdenum, vanadium, tungsten, titanium, chromium, zirconium, niobium, tantalum, hafnium, rhenium, said method comprising: heating a nitride having a particle size in the range of about 1 to 15 nm and a specific surface area of at least about 40 m 2 /g when measured by BET method in the presence of a carbon source at a temperature in the range of about 500°-1500° C. for a sufficient time to substantially displace all of the nitrogen with carbon, wherein a thermodynamically metastable carbide is formed; and isolating said thermodynamically metastable carbide having substantially the same crystal structure as said nitride.

Claim 12

Dependent Claim 192 words

A method according to claim 9, wherein said nitride is prepared from an oxide of said metal according to a method which comprises: heating said oxide substantially uniformly and continuously at a rate in the range of about 0.1° to 5° C./min for at least 20 minutes in the presence of a reducing environment and a source of nitrogen from a temperature at least 25° C. prior to substantial completion of formation of said nitride, and through a temperature range wherein reduction of said oxide and reaction with nitrogen of said source occurs to form a nitride, whereby an effluent is formed comprising an unreacted portion of said source and gases resulting from reaction of said source with said oxide, and wherein said heating continues to a final temperature until said reaction is substantially complete as evidenced by the substantial absence of change in the composition of said effluent; and lowering the temperature of the nitride by at least 25° C. by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about 1 hour or about 50% of the time of said heating.

Claim 13

Dependent Claim 31 words

A method according to claim 9, comprising the additional step of mixing hydrogen with said carbon source or treating the resulting metastable cubic carbide with hydrogen to remove any free carbon.

Claim 14

Dependent Claim 11 words

A method according to claim 9, wherein said metal is molybdenum.

Claim 15

Dependent Claim 11 words

A method according to claim 9, wherein said metal is tungsten.

Claim 16

Dependent Claim 43 words

A catalyst consisting essentially of a face-centered cubic molybdenum or tungsten carbide having crystals of a mean diameter in the range of about 1-15 nm, and having a specific surface area of at least 40 m 2 /g when measured by BET method.

Claim 17

Dependent Claim 43 words

A catalyst consisting essentially of a face-centered cubic molybdenum or tungsten carbide having crystals of a mean diameter in the range of about 1-15 nm, and having a specific surface area of at least 40 m 2 /g when measured by BET method.

Claim 18

Dependent Claim 11 words

The catalyst of claim 14, wherein said carbide is molybdenum carbide.

Claim 19

Dependent Claim 11 words

The catalyst of claim 14, wherein said carbide is tungsten carbide.

Claim 20

Dependent Claim 277 words

A high specific surface area metal carbide or nitride, wherein said metal is molybdenum, tungsten, titanium, chromium, zirconium, niobium, vanadium, tantalum, hafnium, or rhenium, said carbides and nitrides being prepared from the respective metal oxides and resulting in at least a 5-fold increase in surface area over that of said oxide, produced by a method which comprises: heating said oxide uniformly and continuously at a rate in the range of about 0.1° to 5° C./min for at least 20 minutes in the presence of a reducing environment and a source of carbon or nitrogen from a temperature at least 25° C. prior to completion of formation of said carbide or nitride, and through a temperature range wherein reduction of said oxide and reaction with carbon and nitrogen of said source occurs to form a carbide or nitride reaction product, respectively, whereby an effluent is formed comprising an excess unreacted portion of said source and gases resulting from reaction of said source with said oxide, and wherein said heating continues to a final temperature until said reaction is complete as evidence by the absence of change in the composition of said effluent; lowering the temperature of the reaction product by a least 25° C. by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about one hour or about 50% of the time of said heating; and wherein said carbide or nitride is further characterized by a particle of a size in the range of about 1 to 15 nm and having a specific surface area of at least about 40 m 2 /g when measured by BET method.

Claim 21

Dependent Claim 277 words

A high specific surface area metal carbide or nitride, wherein said metal is molybdenum, tungsten, titanium, chromium, zirconium, niobium, vanadium, tantalum, hafnium, or rhenium, said carbides and nitrides being prepared from the respective metal oxides and resulting in at least a 5-fold increase in surface area over that of said oxide, produced by a method which comprises: heating said oxide uniformly and continuously at a rate in the range of about 0.1° to 5° C./min for at least 20 minutes in the presence of a reducing environment and a source of carbon or nitrogen from a temperature at least 25° C. prior to completion of formation of said carbide or nitride, and through a temperature range wherein reduction of said oxide and reaction with carbon and nitrogen of said source occurs to form a carbide or nitride reaction product, respectively, whereby an effluent is formed comprising an excess unreacted portion of said source and gases resulting from reaction of said source with said oxide, and wherein said heating continues to a final temperature until said reaction is complete as evidence by the absence of change in the composition of said effluent; lowering the temperature of the reaction product by a least 25° C. by stopping the heating after reaching the final temperature or after maintaining the final temperature for the lesser of about one hour or about 50% of the time of said heating; and wherein said carbide or nitride is further characterized by a particle of a size in the range of about 1 to 15 nm and having a specific surface area of at least about 40 m 2 /g when measured by BET method.

Claim 22

Independent Claim 110 words

A method for preparing a thermodynamically metastable metal carbide, wherein said metal is molybdenum, vanadium, tungsten, titanium, chromium, zirconium, niobium, tantalum, hafnium or rhenium, said method comprising: heating a nitride having a particle size in the range of about 1 to 15 nm and specific surface area of at least about 40 m 2 /g when measured by BET method, in the presence of a carbon source at a temperature range of about 500°-1500° C. for a sufficient time to substantially displace all of the nitrogen with carbon, wherein a thermodynamically metastable carbide is formed; and isolating said thermodynamically metastable carbide having substantially the same crystal structure as said nitride.

Claim 23

Independent Claim 110 words

A method for preparing a thermodynamically metastable metal carbide, wherein said metal is molybdenum, vanadium, tungsten, titanium, chromium, zirconium, niobium, tantalum, hafnium or rhenium, said method comprising: heating a nitride having a particle size in the range of about 1 to 15 nm and specific surface area of at least about 40 m 2 /g when measured by BET method, in the presence of a carbon source at a temperature range of about 500°-1500° C. for a sufficient time to substantially displace all of the nitrogen with carbon, wherein a thermodynamically metastable carbide is formed; and isolating said thermodynamically metastable carbide having substantially the same crystal structure as said nitride.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-07-24	1993-01-23	1993-07-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-07-24	1997-01-23	1997-07-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-07-24	2001-01-23	2001-07-25	$7700.00	Window Closed / Lapsed

Methods and compostions involving high specific surface area carbides and nitrides

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