Compositions of Matter Comprising Nanocatalyst Structures, Systems Comprising Nanocatalyst Structures, and Related Methods
Methods of forming and producing nanocatalysts mounted on or within nanofiber or nanotube structures are disclosed. The mounting structures prevent the nanocatalysts from agglomerating and retain the nanocatalysts in a reactor. The nanocatalysts may be grown over a bulk catalyst material without treating the nanotubes after forming the nanotubes. The resulting nanocatalysts remain catalytically active immediately after formation of the mounting supports and are effective in a wide variety of reactions. Systems are disclosed for reacting reaction gases to form mounting structures with at least one embedded nanocatalyst in the growth tips. The mounting structures may catalyze a different, subsequent reaction than the nanofiber formation reaction, which may take place in the same or a different reactor. Methods of forming a mass of nanocatalysts and catalyzing a reaction with the mass of nanocatalysts are disclosed. Systems are disclosed for forming a mass of nanocatalysts and catalyzing another reaction with the mass of nanocatalysts.
1 . A method, comprising:
reacting gaseous reactants in a reaction zone in the presence of a bulk catalyst material to grow nanocatalyst structures comprising a mass of nanofibers having at least one particle of the bulk catalyst material attached to a growth tip of a substantial quantity of the nanofibers of the mass of nanofibers.
2 . The method of claim 1 , further comprising catalyzing at least a second reaction with the nanocatalyst structures.
3 . The method of claim 1 wherein reacting gaseous reactants in a reaction zone comprises reacting a gaseous carbon source with a reducing gas in the reaction zone.
4 . The method of claim 1 , further comprising depositing additional catalytic material on at least one of an exterior surface and an interior surface of a substantial quantity of the nanocatalyst structures.
5 . The method of claim 4 , wherein depositing additional catalytic material on at least one of an exterior surface and an interior surface of a substantial quantity of the nanocatalyst structures comprises depositing at least one of platinum, palladium, and ruthenium on at least one of an exterior surface and an interior surface of a substantial quantity of the nanocatalyst structures.
6 - 8 . (canceled)
9 . The method of claim 3 , wherein reacting a gaseous carbon source with a reducing gas comprises reacting a carbon oxide with at least one material selected from the group consisting of hydrogen, methane, hydrocarbon gases, and alcohols.
10 . The method of claim 2 , wherein catalyzing at least a second reaction with the mass of nanocatalyst structures comprises catalyzing at least one of a catalytic reforming reaction, a hydrogenation reaction, a dehydrogenation reaction, a Fischer-Tropsch reaction, a Haber-Bosch reaction, a methane-reforming reaction, and a nitrous-oxide decomposition reaction.
11 - 12 . (canceled)
13 . The method of claim 4 , further comprising forming a layer of catalytic material on a surface of an inert substrate material to form the bulk catalyst material.
14 . The method of claim 13 , wherein forming a layer of catalytic material on a surface of an inert substrate material to form the bulk catalyst material comprises forming a layer of at least one element of Groups 5 through 11 of the periodic table.
15 . The method of claim 13 , wherein forming a layer of catalytic material on a surface of an inert substrate material to form the bulk catalyst material comprises forming a layer of the catalyst material by at least one of atomic layer deposition, chemical vapor deposition, electro-chemical deposition, and sputtering.
16 . A system for catalyzing a reaction using nanocatalysts, comprising:
at least one first reaction zone for forming a mass of nanocatalyst structures and a tail gas from a first combination of reactants, wherein at least one surface of the first reaction zone comprises a bulk catalyst material for catalyzing the formation of the mass of nanocatalyst structures; and
at least another reaction zone for catalyzing another reaction with a second combination of reactants.
17 . The system of claim 16 , wherein the at least one surface of the first reaction zone comprises at least one element of Groups 5 through 11 of the periodic table.
18 . The system of claim 16 , wherein the at least one surface of the first reaction zone comprises a film of catalytic material having a thickness less than about 10 nm.
19 . The system of any of claim 16 , wherein the at least another reaction zone comprises at least one of a packed-bed reactor and a fluidized-bed reactor, wherein the at least one of a packed bed reactor and a fluidized-bed reactor comprises pellets comprising at least some of the mass of nanocatalyst structures formed in the at least one first reaction zone.
20 . The system of claim 16 , further comprising a condensing means for removing water from the tail gas to control the concentration of water in at least one of the first combination of reactants and the second combination of reactants.
21 . (canceled)
22 . The system of claim 16 , further comprising a collection means for collecting the mass of nanocatalysts downstream of the at least one first reaction zone, the collection means comprising at least one of a cyclone separator, a bag house, a scrubber, and an electrostatic precipitator.
23 . (canceled)
24 . The system of claim 16 , further comprising a means for pelletizing the mass of nanocatalyst structures, the means for pelletizing the mass of nanocatalyst structures comprising at least one of a means for pressing, a means for extruding, and a means for sintering.
25 . (canceled)
26 . The system of claim 16 , further comprising a means for recycling at least a portion of a tail gas leaving the at least another reaction zone to at least one of the at least one first reaction zone and the at least another reaction zone.
27 . (canceled)
28 . The system of claim 16 , further comprising a means for depositing additional catalytic material onto an exterior surface of at least a portion of the mass of nanocatalyst structures.
29 . A composition of matter, comprising:
a nanocatalyst structure comprising a nanofiber with at least one particle of catalyst material embedded on at least one end of the nanofiber; and
at least another particle of catalyst material attached to an exterior surface of the nanocatalyst structure.
30 - 42 . (canceled)