U.S. patent application number 17/717544 was filed with the patent office on 2022-07-28 for methods, apparatuses, and electrodes for carbide-to-carbon conversion with nanostructured carbide chemical compounds.
The applicant listed for this patent is WEST VIRGINIA UNIVERSITY RESEARCH CORPORATION. Invention is credited to J. Steven RUTT.
Application Number | 20220235474 17/717544 |
Document ID | / |
Family ID | 1000006256001 |
Filed Date | 2022-07-28 |
United States Patent
Application |
20220235474 |
Kind Code |
A1 |
RUTT; J. Steven |
July 28, 2022 |
METHODS, APPARATUSES, AND ELECTRODES FOR CARBIDE-TO-CARBON
CONVERSION WITH NANOSTRUCTURED CARBIDE CHEMICAL COMPOUNDS
Abstract
Nanostructured carbide chemical compound is used to convert
carbide to carbon. A method comprising: providing at least one
carbide chemical compound and reducing a metal cation with use of
the carbide chemical compound to form elemental carbon, wherein the
carbide chemical compound is nanostructured. The nanostructured
carbide chemical compound can be in the form of a nanoparticle, a
nanowire, a nanotube, a nanofilm, a nanoline. The reactant can be a
metal salt. Electrochemical reaction, or reaction in the melt or in
solution, can be used to form the carbon. The nanostructured
carbide chemical compound can be an electrode.
Inventors: |
RUTT; J. Steven; (BURKE,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WEST VIRGINIA UNIVERSITY RESEARCH CORPORATION |
Morgantown |
WV |
US |
|
|
Family ID: |
1000006256001 |
Appl. No.: |
17/717544 |
Filed: |
April 11, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15491715 |
Apr 19, 2017 |
11332833 |
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17717544 |
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62325281 |
Apr 20, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25B 11/057 20210101;
C25B 1/00 20130101; C01P 2004/20 20130101; C01P 2004/64 20130101;
C01P 2006/40 20130101; C01B 32/25 20170801; C01B 32/184 20170801;
C01B 32/05 20170801; C25B 11/04 20130101; C01B 32/942 20170801;
C01B 32/914 20170801 |
International
Class: |
C25B 11/057 20060101
C25B011/057; C01B 32/184 20060101 C01B032/184; C01B 32/25 20060101
C01B032/25; C01B 32/914 20060101 C01B032/914; C25B 11/04 20060101
C25B011/04; C01B 32/942 20060101 C01B032/942; C01B 32/05 20060101
C01B032/05; C25B 1/00 20060101 C25B001/00 |
Claims
1. An apparatus comprising at least one electrochemical cell
comprising: at least one anode comprising at least one carbide
chemical compound, and at least one cathode, wherein the carbide
chemical compound is nanostructured.
2. The apparatus of claim 1, wherein the nanostructured carbide
chemical compound is in nanoparticulate form.
3. The apparatus of claim 1, wherein the nanostructured carbide
chemical compound is in nanowire form.
4. The apparatus of claim 1, wherein the nanostructured carbide
chemical compound is in nanofilm form.
5. The apparatus of claim 1, wherein the nanostructured carbide
chemical compound is characterized by at least one nanodimension of
1 nm to 1,000 nm.
6. The apparatus of claim 1, wherein the nanostructured carbide
chemical compound is characterized by at least one nanodimension of
1 nm to 100 nm.
7. The apparatus of claim 1, wherein the cathode is part of a
cathode system which includes a metal salt as reactant.
8. The apparatus of claim 1, wherein the carbide chemical compound
is a salt-like carbide.
9. The apparatus of claim 1, wherein the carbide chemical compound
is calcium carbide or aluminum carbide.
10. The apparatus of claim 1, wherein the carbide chemical compound
is calcium carbide.
11. An electrode structure comprising at least one carbide chemical
compound, wherein the carbide chemical compound is
nanostructured.
12. The electrode structure of claim 11, wherein the nanostructured
carbide chemical compound is in nanoparticulate form.
13. The electrode structure of claim 11, wherein the nanostructured
carbide chemical compound is in nanowire form.
14. The electrode structure of claim 11, wherein the nanostructured
carbide chemical compound is in nanofilm form.
15. The electrode structure of claim 11, wherein the nanostructured
carbide chemical compound is characterized by at least one
nanodimension of 1 nm to 1,000 nm.
16. The electrode structure of claim 11, wherein the nanostructured
carbide chemical compound is characterized by at least one
nanodimension of 1 nm to 100 nm.
17. The electrode structure of claim 11, wherein the electrode
structure further comprises at least one electronically conductive
structural element different from the carbide chemical compound and
contacting the carbide chemical compound.
18. The electrode structure of claim 11, wherein the carbide
chemical compound is a salt-like carbide.
19. The electrode structure of claim 11, wherein the carbide
chemical compound is calcium carbide or aluminum carbide.
20. The electrode structure of claim 11, wherein the carbide
chemical compound is calcium carbide.
Description
BACKGROUND
[0001] Carbon materials and nanomaterials are an increasingly
important area of materials science and technology. Examples of
important carbon nanomaterials include, for example, fullerenes,
carbon nanotubes, graphene, and nanocrystalline diamond.
Carbide-to-carbon reactions and so-called "carbide-derived carbon"
(CDC) are known in the art. However, better methods are needed to
prepare and control such carbon materials, particularly at the
nanoscale. Moreover, it is desirable if reaction conditions such as
temperature and pressure can be mild and economically attractive.
For example, some preparation methods suffer from a need for high
or low temperatures, or high or low pressures, in addition to a
lack of control over the product. Other preparation methods require
use of chemical such as chlorine which raise environmental and
health risks.
SUMMARY
[0002] Aspects and embodiment described herein include materials,
methods of making materials, methods of using materials, and
devices, apparatuses, and systems which comprise such
materials.
[0003] A first aspect, for example, is a method comprising:
providing at least one carbide chemical compound and reducing at
least one reactant with use of the carbide chemical compound to
form elemental carbon, wherein the carbide chemical compound is
nanostructured.
[0004] A second aspect is a method comprising: producing elemental
carbon material from the oxidation of carbide in at least one
carbide chemical compound in at least one anode of an
electrochemical cell apparatus, wherein the carbide chemical
compound is nanostructured.
[0005] A third aspect is an apparatus comprising at least one
electrochemical cell comprising: at least one anode comprising at
least one carbide chemical compound, and at least one cathode,
wherein the carbide chemical compound is nanostructured.
[0006] A fourth aspect provides for an electrode structure
comprising at least one carbide chemical compound, wherein the
carbide chemical compound is nanostructured.
[0007] Still further, a fifth aspect provides for a method
comprising operating at least one anode in an electrochemical cell,
wherein the anode comprises at least carbide chemical compound,
wherein the carbide chemical compound is nanostructured.
[0008] Still further, a sixth aspect provides for a method
comprising: producing elemental carbon material from the oxidation
of carbide in at least one carbide chemical compound which is in
contact with a melt comprising at least one salt comprising at
least one metal cation which is reduced, wherein the carbide
chemical compound is nanostructured.
[0009] Still further, a seventh aspect provides for a method
comprising: producing elemental carbon material from the oxidation
of carbide in at least one carbide chemical compound which is in
contact with a solution comprising at least one organic solvent and
at least one dissolved salt comprising at least one metal cation
which is reduced, wherein the carbide chemical compound is
nanostructured.
[0010] An eighth aspect is an elemental carbon material composition
prepared by any of the methods described or claimed herein.
[0011] A ninth aspect is a method comprising: processing at least
one carbide chemical compound into a nanostructured form of the
carbide chemical compound.
[0012] A tenth aspect is a composition comprising, consisting
essentially of, or consisting of nanostructured carbide chemical
compound such as, for example, calcium carbide.
[0013] Additional embodiments of these various aspects are provided
in the following detailed description and claims.
[0014] At least one advantage which results from at least one
embodiment described herein is better control over the reaction and
the reaction product including control at the nanoscale. This can
provide for new forms of carbon for at least some embodiments.
BRIEF DESCRIPTION OF FIGURES
[0015] FIG. 1 illustrates in cross-section one embodiment for a
nanostructured carbide chemical compound in nanoparticle form (D is
diameter which will be less than 1,000 nm).
[0016] FIG. 2 illustrates in perspective view one embodiment for a
nanostructured carbide chemical compound in an elongated form,
including a nanowire (D is width which will be less than 1,000
nm).
[0017] FIG. 3 illustrates one embodiment for a nanostructured
carbide chemical compound in a nanofilm form. The film thickness
will be less than 1,000 nm.
DETAILED DESCRIPTION
Introduction
[0018] Further details of the various embodiments are provided
herein.
[0019] References cited herein are incorporated herein by reference
in the entirety. No admission is made that any of the references
are prior art.
[0020] In addition, the claim transitions "comprising," "consisting
essentially of," and "consisting of" can be used to describe and/or
claim the various embodiments described herein, whether for
methods, compositions, or apparatuses. Basic and novel features of
the invention are described herein and allow for exclusion of
components from claimed embodiments. Claims can be open, partially
closed, or closed claims.
[0021] Carbide chemical compounds are known to be used in steel
manufacturing, but an embodiment is that the methods and
compositions described herein do not relate to the manufacture of
steel.
Carbide-to-Carbon Conversion Reaction
[0022] The carbide-to-carbon conversion reaction, and related
reactions, are generally known in the art as reflected in the
following references, which are incorporated herein by reference in
the entirety: [0023] U.S. application Ser. No. 14/213,533, filed
Mar. 14, 2014 and published as 2014/0271441, describes a method of
making carbon from carbide and molten, metal salts in a thermal
process but at relatively low temperature compared to prior art
processes. PCT Application PCT/US2014/028755, filed Mar. 14, 2014
and published as WO 2014/144374, also describes a method of making
carbon from carbide and molten, metal salts in a thermal process
but at a relatively low temperature. Also described are processing
steps to purify and treat the elemental carbon material. FIGS. 6
and 7 show examples of elemental carbon materials prepared by these
methods; [0024] U.S. patent application Ser. No. 14/886,319 filed
Oct. 19, 2015 described a method for making carbon from carbide at
mild temperature and pressure, including use of an electrochemical
apparatus at room temperature and pressure, as well as use of a
solvent process. Application Ser. No. 14/886,319 describes
embodiments for methods of making the carbon, apparatuses for
making the carbon, carbide electrodes, reaction products, post
reaction processing, and applications which are supported by
figures, data, and working examples, all of which is incorporated
herein by reference in its entirety; [0025] Y. Gogotsi, (Ed.),
Carbon Nanomaterials, 2006, Chapter 6, "Carbide-Derived Carbon,"
(G. Yushin et al.), pp. 211-254; [0026] Carbon Nanomaterials,
2.sup.nd Ed., CRC Press, 2014, Chapter 11, "Carbide-Derived
Carbon," (Y. Korenblit et al.), pp. 303-329; [0027] D. Osetzky,
Carbon, 12, 517-523, 1974; [0028] N. F. Fedorov, et al., J. Appl.
Chem. USSR, 54, 2253-2255, 1981; [0029] N. F. Federov, et al., Russ
J. Appl. Chem. 71, 584-588, 1998; [0030] N. F. Federov, et al.,
Russ. J. Appl. Chem. 71, 795-798, 1998; [0031] (Russian) Ivakhnyuk,
Z. Prikladnoi Khimii, 60, 852-856, 1987 ("Carbon enriched calcium
carbide and possibility of its application"); [0032] (Russian)
Ivakhnyuk, Z. Prikladnoi Khimii, 60, 1413-1415, 1987 ("Study of
properties of carbon derived from calcium carbide in the presence
of nitrogen"); [0033] (Russian) Samonin, Z. Prikladnoi Khimii, 60,
2357-2358, 1987 ("On mechanism of interaction between calcium
carbide and metal chlorides"); [0034] SU patent 996324; [0035] SU
patent 1175869; [0036] Han et al., J. Phys. Chem., 2011, 115,
8923-8927; [0037] U.S. Pat. No. 3,066,099; [0038] Dai et al., Mat.
Chem. Phys., 112, 2, 2008, 461-465 (CaC.sub.2-CDC, nanostructured
carbon by chlorination of CaC at moderate temperatures); [0039]
Carbide-derived carbon (CDC) is described in the patent literature
including, for example, US Patent Publications 2001/0047980;
2006/0165584; 2006/0165988; 2008/0219913; 2009/0036302;
2009/0117094; 2009/0258782; 2009/0301902; [0040] In addition, DE
1667532 Greiner (1971) describes what is said to be low temperature
diamond production from an electrochemical system which can include
use of carbide in the electrolyte with use of temperatures of
600.degree. C. to 1000.degree. C. However, no data are provided;
[0041] Also, U.S. Pat. No. 4,738,759 (1988) describes an
electrolysis process wherein calcium carbide can be subjected to
electrolysis to form graphite sponge at the anode. Temperatures are
used such as 700.degree. C. to 1,000.degree. C.; [0042] A Chen M.
S. thesis, August 2002, Univ. N. Texas, describes electrochemical
deposition of films of amorphous carbon and diamond like carbon
(DLC). Electrochemical deposition was carried out using a low
temperature (less than -40.degree. C.) solution of acetylene in
liquid ammonia; [0043] Kulak, Electrochem. Comm., 5, 2003, 301-305
describes room temperature electrodeposition of very thin, porous
film containing carbon (50-100 nm thick) from a solution of lithium
acetylide. However, the microscopic images of the film indicate a
low quality material (FIG. 2) and much of the film is not carbon
apparently; [0044] US 2011/0290655 (Nishikiori; Toyota) describes a
method for electrochemically depositing carbon film on an anode
substrate using a molten salt electrolyte bath comprising a carbide
ion and applying a DC voltage to deposit the carbon film. The bath
temperature is 250.degree. C. to 800.degree. C. The carbon film is
said to be mainly amorphous carbon including graphite-like carbon
according to x-ray diffraction.
Carbide Chemical Compound
[0045] Carbide chemical compounds or "carbides" are generally known
in the art. See, for example, Cotton & Wilkinson, Advanced
Inorganic Chemistry, 4.sup.th Ed., 1980, pages 361-363; and
Kosolapova, Carbides, Properties, Production, and Applications,
Plenum Press, 1971. This text classifies types of carbides as
saltlike carbides, interstitial carbides, and covalent carbides.
Carbides can also include other elements such as oxygen in
oxycarbides (see, for example, U.S. Pat. Nos. 6,514,897 and
5,599,624).
[0046] Known carbide chemical compounds include, for example,
aluminum, arsenic, beryllium, boron, calcium, chromium (in five
different Cr:C ratios), cobalt, hafnium, iron (in seven different
Fe:C ratios), lanthanum, manganese (in two different Mn:C ratios),
magnesium (in two different Mg:C ratios), molybdenum (in three
different Mo:C ratios), nickel (in two different Ni:C ratios),
niobium (in two different Nb:C ratios), plutonium (in two different
Pu:C ratios), phosphorous, scandium, silicon, tantalum (in two
different Ta:C ratios), thorium (in two different Th:C ratios),
titanium, tungsten (in two different W:C ratios), uranium (in two
different U:C ratios), vanadium (in two different V:C ratios), and
zirconium carbide. Also, a carbide can form with two different
metals such as cobalt tungsten carbide.
[0047] In one embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. More
particularly, the carbide chemical compound is a salt-like carbide
in one embodiment. In another embodiment, the carbide chemical
compound is a methanide, an acetylide, or a sesquicarbide.
[0048] Methanides react with water to produce methane. Methane is a
carbon atom bonded to four hydrogen atoms in an sp3 hybridization.
Two examples of methanides are aluminum carbide (Al.sub.4C.sub.3)
and beryllium carbide (Be.sub.2C). Acetylides are salts of the
acetylide anion C.sub.2.sup.-2 and also have a triple bond between
the two carbon atoms. Triple bonded carbon has an sp1 hybridization
and two examples of acetylides are sodium carbide (Na.sub.2C.sub.2)
and calcium carbide (CaC.sub.2). Sesquicarbides contain the
polyatomic anion C.sub.3.sup.-4 and contains carbon atoms with an
sp1 hybridization. Two examples of sesquicarbides are magnesium
carbide (Mg.sub.2C.sub.3) and lithium carbide
(Li.sub.4C.sub.3).
[0049] Sesquicarbides are of particular use for the preparation of
sp1 carbon. One can produce Mg.sub.2C.sub.3 in the laboratory by
bubbling methane through molten magnesium metal under an inert
argon atmosphere at over 750.degree. C. Other hydrocarbons such as
pentane may also be viable candidates. Also, molten magnesium (Mg)
reaction is another area of chemistry where little has been
conducted. Research in molten Mg reactions have been limited
because of the dangers associated with molten Mg, especially with
the process generating hydrogen gas as well. But a process very
similar to the synthesis of the magnesium sesquicarbide can be used
to convert methane directly into carbon in the form of graphite and
hydrogen gas. Methane can be bubbled through a molten solution of
Mg and magnesium chloride salt. When heated to a temperature of
over 750.degree. C. under an argon atmosphere the elemental Mg
metal and MgCl.sub.2 both melt to form a liquid solution. Similar
to the Mg sesquacarbide synthesis, methane is bubbled through the
solution to produce either MgC.sub.2 (magnesium carbide) or
Mg.sub.2C.sub.3 and hydrogen gas that can be collected as a value
added product. The carbide then reacts with the metallic salt based
on the original chemistry of the carbon producing carbide reaction.
The Mg.sub.2C.sub.3 and MgCl.sub.2 are converted to elemental
carbon in the form of graphite, elemental Mg metal and MgCl.sub.2,
which would remain as part of the liquid solution. Therefore, the
Mg metal and MgCl.sub.2 salt would remain unchanged throughout the
overall process while the methane would be converted to pure carbon
and hydrogen gas.
[0050] In particular embodiments, the carbide chemical compound is
calcium carbide, aluminum carbide, sodium carbide, magnesium
carbide, lithium carbide, beryllium carbide, iron carbide, copper
carbide, and chromium carbide. Sodium carbide has the advantage of
being lighter.
[0051] In other more particular embodiments, the carbide chemical
compound is calcium carbide or aluminum carbide. Calcium carbide is
particularly preferred.
[0052] In another embodiment, the carbide chemical compound has
sufficient electronic conductivity to function as or in an anode.
The conductivity for different carbides can vary depending on
factors such as purity and temperature. However, one skilled in the
art for a particular application can determine whether there is
sufficient electronic conductivity and how to adapt the
conductivity for the need. For example, the carbide chemical
compound can have an electronic conductivity of at least 10.sup.-8
S/cm, or at least 10.sup.-7 S/cm, or at least 10.sup.-6 S/cm, or at
least 10.sup.-5 S/cm, or at least 10.sup.-4 S/cm, or at least
10.sup.-3 S/cm, or at least 10.sup.-2 S/cm, or at least 10.sup.-1
S/cm, or at least 10.sup.0 S/cm. The electronic conductivity of
calcium carbide provides a useful benchmark for sufficient
conductivity. No particular upper limit is present except for the
limits provided by nature for a particular carbide.
[0053] The form of the carbide chemical compound can also be varied
as described herein with respect to it being nanostructured.
[0054] The carbide chemical compound can be used in compositions
and mixed with other ingredients such as binders or conductivity
agents to the extent the desired reaction can be achieved. In some
embodiment, more than one carbide chemical compound can be
used.
[0055] One can use an electronically conductive binder to hold the
pieces or particles of carbide together. This can, for example,
increase the surface area of the carbide which is in direct contact
with a conductive surface. Electronically conductive binders also
can be selected as a way to produce composite materials where the
conductive properties and other characteristics of the binder can
be used to change the characteristics of elemental carbon material
produced. Examples of electronically conductive binders include
conjugated polymers in doped or undoped form such a polythiophene
or a polyaniline. Polymeric binders can be used.
[0056] In one embodiment, the carbide chemical compound can be part
of an ink system involving a solvent vehicle. The solvent can be an
organic solvent or water, and mixtures of solvents can be used.
Additives can be used. Nanoparticles can be suspended in the
vehicle and stabilizers can be used. An ink can be useful for
processing and forming films.
[0057] In one embodiment, the carbide chemical compound is not a
covalent carbide and in another embodiment is not silicon
carbide.
[0058] The purity of the carbide chemical compound can be made as
high as possible, including, for example, at least 80 wt. %, or at
least 85 wt. %, or at least 90 wt. %, or at least 95 wt. %, or at
least 99 wt. %.
[0059] Some carbide chemical compounds are commercially available
as "nanopowders." These include, for example, TiC, SiC,
tungsten(IV)C, Cr.sub.3C.sub.2, TaC, VC, and ZrC.
[0060] The crystallinity of the carbide chemical compound is not
particularly limited, whether of uniform or mixed morphology,
whether single crystal, polycrystalline, nanocrystalline, or
amorphous.
[0061] In a preferred embodiment, the carbide chemical compound is
calcium carbide. The manufacture of calcium carbide from a carbon
source and a calcium source is well-known, particularly at a large
manufacturing scale. Calcium carbide is produced typically at very
high temperatures as a melt phase and then cooled into larger slabs
which are then crushed into particles and classified by particle
size. An electric arc furnace is typically used to generate the
high temperatures. Calcium carbide is well-known to be reactive to
water to form acetylene, and steps can be taken to keep the calcium
carbide away from moisture and air. Because of its reactivity with
moisture to form acetylene, calcium carbide can present an
explosion or fire hazard if not handled properly.
[0062] Other methods are available to make calcium carbide such as
in a microwave reactor (Pillai et al., Ind. Eng. Chem. Res., 2015,
54(44), 1001-11010, 2015).
[0063] The reaction of calcium carbide with acetylene has been
reported to useful to produce carbon nanoparticles (Rodygin et al.,
Chem. Asian J., 2016, 11, 7, 965-976).
[0064] The methods of carbide production can be adapted to provide
for nanostructured forms of the carbide chemical compound. The
carbide chemical compound can be formed directly in nanostructured
form, or after formation, it can be processed into the
nanostructured form.
Nanostructured
[0065] The carbide chemical compound is nanostructured
("nanostructured carbide chemical compound"), which is a term
generally known in the art. Nanostructures can take various forms
including, for example, one-dimensional, two-dimensional, and
three-dimensional forms as known in the art. In one embodiment, the
carbide chemical compound is nanostructured in one dimension (e.g.,
a nanofilm); in another embodiment, the carbide chemical compound
is nanostructured in two dimensions (e.g., a nanorod or a
nanowire); and in another embodiment, the carbide chemical compound
is nanostructured in three dimensions (e.g. a nanoparticle).
Nanostructured carbide chemical compounds are known in the art as
described in references cited herein (e.g., Silicon Carbide
Nanostructures, Fabrication, Structure, and Properties, (Fan, Chu,
Eds.), 2014, describing nanoparticles, nanowires, nanotubes, and
nanofilms). Nanostructured and nanostructure does not mean normal,
inherent surface features on a nanoscale which are present in any
solid material surface including a solid carbide chemical compound.
Rather, nanostructured and nanostructures are engineered into the
material through formation of, for example, nanoparticles,
nanowires, or nanofilms.
[0066] A wide variety of nanostructures are known in the art. The
nanostructures can be, for example, nanoparticles, nanopowders,
nanoclusters, nanofibers, nanowires, nanotubes, nanofilms,
nanolines, nanohorns, nanowhiskers, nanoonions, nanoplatelets,
nanorods, nanosheets, nanorings, nanobelts, nanodiscs, nanotowers,
and nanoshells. Some of these terms can be considered subsets of
other terms. In preferred embodiments, the nanostructured carbide
chemical compound is in the form of at least one nanoparticle, at
least one nanowire, at least one nanotube, at least one nanofilm,
or at least one nanoline.
[0067] As used herein, a nanowire can be hollow or non-hollow, and
a hollow nanowire can be also called a nanotube. As used herein, a
nanowire having a shorter aspect ratio (length/width) can be called
a nanorod. An aspect ratio of ten can be used to distinguish the
nanorod form of a nanowire from a nanowire which is not a nanorod,
but for purposes herein nanorods are also nanowires. As used
herein, a nanofilm can be a nanoline if the nanofilm has a length
much longer than the width, such as a length which is two, three,
or four, or more times longer than the width.
[0068] The nanostructure can be characterized by a dimension such
as 1 nm to 1,000 nm, or 1 nm to 500 nm, or 1 nm to 250 nm, or 1 nm
to 100 nm, or 1 nm to 50 nm, or 100 nm to 1,000 nm, or 100 nm to
500 nm, or 100 nm to 250 nm, or 250 nm to 500 nm, or 500 nm to
1,000 nm. The dimension can represent, for example, a diameter or
an average diameter or width, or a thickness or an average
thickness.
[0069] There is no particular upper or lower limit on the volume of
a particular nanostructure, but the volume can be, for example,
less than 20 cubic micron, or less than 10 cubic micron, or less
than one cubic micron, or less than 0.8 cubic micro, less than 0.6
cubic micron, or less than 0.4 cubic micron, or less than 0.2 cubic
micron, or less than 0.5 cubic micron, or less than 0.001 cubic
micron.
[0070] Mixtures of nanostructures can be used. For example,
nanoparticles can be mixed with nanowires, nanotubes, or
nanorods.
[0071] The nanostructures can be porous or non-porous.
[0072] In one embodiment, the nanostructured carbide chemical
compound is mixed with at least one other different material. The
different material can be within the nanostructure or it can be in
a separate structure such as a separate particle or wire. In one
embodiment, the nanostructured carbide chemical compound is held in
a matrix material. The nanostructures can be compacted before
use.
[0073] Nanostructuring of the carbide chemical compound can be
carried out with methods going back to the synthesis of the carbide
chemical compound. For example, if the carbide chemical compound is
prepared in a melt state or a soft state, it can be processed in
this melt or soft state. Molding and pressing operations can be
used. Molds can be adapted to be nanostructured. Steps can be taken
to reduce exposure of the carbide chemical compound to air, oxygen,
and moisture as it is formed. In particular, processes for forming
calcium carbide can be adapted to introduce a nanostructured form.
For example, U.S. Pat. No. 1,889,951 describes a method for cooling
calcium carbide, for example, and this method can be adapted. U.S.
Pat. No. 3,201,052 also describes a process for crushing and
cooling calcium carbide blocks. U.S. Pat. No. 4,508,666 also
describes a process for cooling and comminuting molten calcium
carbide.
[0074] El-Naas et al., Plasma Chemistry and Plasma Processing, 18,
3 (1998) describes a solid-phase synthesis of calcium carbide in a
plasma reactor using fine particle reactants to provide a granular
product with finer particle size. For example, calcium oxide can
have a 170 micron particle size and graphite can have a 130 micron
particle size.
[0075] Additional patent literature for calcium carbide includes
2011/0123428; 2002/0197200; 2005/0170181; 2014/0311292; and
2005/0171370. Known methods can be adapted to form nanostructures
in the nanostructured carbide chemical compound.
Nanoparticle
[0076] Nanoparticles are generally known in the art. The
nanoparticles can be characterized both by looking at an individual
nanoparticle and also looking at collections of pluralities of
nanoparticles, and use of statistics to characterize the
collection. The nanoparticles can be characterized by a diameter
which is nanostructured. Mixtures of nanoparticles can be used.
Methods known in the art such as SEM and TEM methods can be used to
measure particle size, shape, and diameter. The particle shape can
be generally spherical, or it can be somewhat elongated and not
spherical.
[0077] For example, in one embodiment, the nanostructured carbide
chemical compound is in the form of at least one nanoparticle,
wherein the at least one nanoparticle is part of a collection of
nanoparticles of the carbide chemical compound having an average
diameter of 1 nm to 1,000 nm.
[0078] In another example, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound having an average diameter of 100
nm to 1,000 nm.
[0079] In another example, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound having an average diameter of 1 nm
to 100 nm.
[0080] In another example, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound having an average diameter of 500
nm to 1,000 nm.
[0081] In another example, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound having an average diameter of 1 nm
to 500 nm.
[0082] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of microparticles
of the carbide chemical compound and nanoparticles of the carbide
chemical compound.
[0083] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound which are bound together with a
binder.
[0084] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound which are bound together with an
electronically conductive binder.
[0085] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanoparticle, wherein the
at least one nanoparticle is part of a collection of nanoparticles
of the carbide chemical compound which are bound together with a
polymeric binder.
[0086] In one embodiment, the nanostructured carbide chemical
compound is in the form of agglomerated nanoparticles.
[0087] In a particularly preferred embodiment, the nanoparticles
are calcium carbide nanoparticles.
[0088] Nanoparticles can be formed by grinding processes which
reduce the particle size to the desired nanodimension. Also, a
collection of particles can be separated or classified so that a
nanoparticle portion can be isolated from larger particles such as
microparticles.
[0089] One process for grinding particles is the Union process
which includes fine grinding done at micron, sub-micron, and
nanoscale levels. Wet grinding and dry grinding can be carried out.
See equipment and literature available from Union Process, Inc.
(Akron, Ohio).
[0090] CN1498976 describes a "desulfurizer based on nanocomposite
calcium carbide and calcium oxide for steel. Briefly, it describes
a nano-class composite calcium carbide (or calcium oxide)-based
desulfurizing agent for steel which contains calcium carbide or
calcium oxide nanoparticles (65-95 wt. %), calcareous high-Al
cement clinker, and a series of powders. The high energy Union
Process (Ohio) can be used with an agitating mill with 2 micron
particles crushed to 100 nm-class products.
[0091] U.S. Pat. No. 7,025,945 describes preparation of calcium
carbide minute powder having particle size of several microns or
below made mechanically.
[0092] U.S. Pat. No. 2,323,597 describes a multistage, continuous
process for grinding calcium carbide.
[0093] Vorozhtsov et al. describes Al.sub.4C.sub.3 nanoparticles
made by hot compaction (Russian J. of Non-Ferrous Metals, 2012, 53,
5, 420).
[0094] Streletskii et al., describe mechanochemical synthesis of
aluminum carbide fine powder.
[0095] Fe.sub.3C nanoparticles are described in Chemistry of
Materials, 2010, 22(18), 5340-5344.
[0096] Nanostructured Mo.sub.2C nanoparticles are described in,
Chen et al., Energy Environ. Sci. 2013, 6, 943.
[0097] Nanostructured TaC is described in, for example, de Oliveira
et al., Sintering Techniques of Materials, 2015, Chapter 6, p. 107
(InTech).
[0098] Nanostructured clusters of carbides are described in U.S.
Pat. No. 7,025,945 and US Patent Publication 2004/0028948. See also
Nishi et al., Chem. Phys. Letters, 369, 1-2, 198-203 (2003).
[0099] An example of a nanoparticle with diameter D is shown in
cross-section in FIG. 1, showing an idealized spherical
embodiment.
Nanowires/Nanotubes/Nanorods
[0100] Nanowires, nanorods, and nanotubes are generally known in
the art. The diameter of the nanowire or nanotube can be a
nanodimension. The aspect of these structures (length to diameter
ratio) may be relatively low compared to conventional nanowire or
nanotube structures, and if less than ten, the nanowire can also be
called a nanorod. Also, the carbide chemical compound can be mixed
with one or more other materials that facilitate production into a
nanowire, or nanotube form, helping to allow for elongation.
[0101] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanowire.
[0102] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanowire, wherein the at
least one nanowire is part of a collection of nanowires having an
average diameter of 1 nm to 1,000 nm.
[0103] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanowire, wherein the at
least one nanowire is part of a collection of nanowires having an
average diameter of 1 nm to 100 nm.
[0104] In one embodiment, the nanowire has an aspect ratio of less
than ten, such as 3 to 10. In another embodiment, the aspect ratio
is greater than ten.
[0105] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanotube.
[0106] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanotube, wherein the at
least one nanotube is part of a collection of nanotubes having an
average diameter of 1 nm to 1,000 nm.
[0107] In another embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanotube, wherein the at
least one nanotube is part of a collection of nanotubes having an
average diameter of 1 nm to 100 nm.
[0108] Particularly preferred embodiments are calcium carbide
nanofibers, calcium carbide nanowires, or calcium carbide
nanotubes, or calcium carbide nanorods.
[0109] Nanowires can be prepared by drawing processes.
[0110] Chen et al., describe Al.sub.4C.sub.3 nanorods (Adv. Eng.
Mat., 2014, 16, 8).
[0111] Sun et al., describe Al.sub.4C.sub.3 one-dimensional
nanostructures including nanowires (Nanoscale, 2011, 3, 2978).
[0112] Sun et al., describe Al.sub.4C.sub.3 one-dimensional
nanostructures including nanowires (ACSNano, 2011, 5, 2, 2011).
[0113] He et al, describe fabrication of aluminum carbide nanowires
by a nano-template reaction (Carbon, 48, 2010, 931).
[0114] CN101125652 describes a method for synthesizing aluminum
carbide nanobelts.
[0115] Zhang et al. describe a self-assembly process for making
aluminum carbide nanowires and nanoribbons.
[0116] U.S. Pat. No. 6,514,897 describes nanorods having carbides
and/or oxycarbides.
[0117] Schmueck et al. describe making nanostructured metal
carbides via salt flux synthesis, including making V8C7 (Inorganic
Chemistry, 2015, 54(8) 3889.
[0118] An example of a nanowire is shown in a perspective view in
FIG. 2, showing an idealized spherical representation with diameter
D.
Nanofilms and Nanolines
[0119] Nanofilms and nanolines are generally known in the art.
Here, the thickness dimension can be nanostructured. The line can
be linear or curved as in curvilinear.
[0120] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanofilm.
[0121] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanofilm, and the nanofilm
is in the form of a nanoline, wherein the line has a line width of
1 mm or less.
[0122] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanofilm having an average
film thickness of 1 nm to 1,000 nm.
[0123] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanofilm having an average
film thickness of 1 nm to 100 nm.
[0124] In one embodiment, the nanostructured carbide chemical
compound is in the form of at least one nanofilm which is disposed
on a substrate. The substrate can be inorganic or organic material,
and can be, for example, glass, metal, polymeric, ceramic,
composite, or other types of materials. The nanofilms and nanolines
can be disposed by deposition on a solid substrate including a
substrate made of inorganic or organic material. Patterning of the
nanofilm or nanoline can be carried out.
[0125] In a particularly preferred embodiment, the nanofilms and
nanolines are calcium carbide nanofilms and calcium carbide
nanolines.
[0126] Nanofilms can be made by pressing molten forms of the
carbide chemical compound. Another method is thin film deposition
methods on a substrate such as sputtering, chemical vapor
deposition, ion implantation, and the like.
[0127] Sun et al. describe Al.sub.4C.sub.3 nanowalls (Cryst. Eng.
Comm., 2012, 14, 7951).
[0128] S. Reynaud describes preparation of boron carbide
nanostructured materials made by sputtering of thin films (PhD
thesis, Rutgers Univ., 2010).
[0129] An examples of a nanofilm is shown in a perspective view in
FIG. 3.
Oxidation/Reduction Reaction; Reaction Conditions
[0130] The oxidation and reduction reactions can be carried out
under a variety of reaction conditions including temperature and
pressure. A reactant is used along with the nanostructured carbide
chemical compound. Many reaction conditions and the apparatuses and
reaction vessels to carry out the reactions are described in patent
applications cited herein including Ser. No. 14/886,319 and PCT
Application PCT/US2014/028755. Several lead embodiments include use
of an electrochemical approach, use of a melt approach, and use of
a solvent approach, which are described more hereinbelow. The
electrochemical and solvent approaches are particularly described
in U.S. Ser. No. 14/886,319, and melt approaches are particularly
described in PCT Application PCT/US2014/028755. A reactant is used
which is reduced as the nanostructured carbide chemical compound is
oxidized. The reactant can be, for example, a metal salt in which
the metal cation is reduced from the electrons of the oxidizing
carbide. In some embodiments, the carbide chemical compound can be
in direct, physical contact, wherein for example, the reactant is
in a melt or solution phase and is in direct, physical contact with
the carbide chemical compound. In other embodiments, the reactant
and carbide chemical compound cannot be in direct, physical
contact, but indirectly linked via an electrically conductive
pathway in an electrochemical cell.
[0131] Relatively low temperatures, including room temperature, can
be used for the reaction to form carbon. For example, the
temperature can be, for example, about -50.degree. C. to about
100.degree. C., or about 10.degree. C. to about 90.degree. C., or
about 0.degree. C. to about 50.degree. C., or about 15.degree. C.
to about 50.degree. C. The temperature can be, for example, about
20.degree. C. to about 30.degree. C., or about 23.degree. C.,
24.degree. C., or 25.degree. C. In some embodiments, one will want
if possible to avoid the expense of cooling, heating, and
temperature control elements. In some embodiments, one will want to
run the reaction as close to ambient as possible. As known in the
art, in a larger manufacturing operation, excess heat from one
point in the operation can be transferred to another point in the
operation which needs heat.
[0132] In other embodiments, the reducing is carried out at a
temperature of less than about 400.degree. C., or at a temperature
of about 15.degree. C. to about 400.degree. C. In other
embodiments, the reducing is carried out at a temperature of less
than about 300.degree. C.
[0133] In some embodiments, the methods described herein are
undertaken at room temperature.
[0134] Moisture free, air free, oxygen free environments can be
used for the reaction, and inert gases can be used.
[0135] The pressure can be about 1 atmosphere (760 torr) or normal
pressure. The pressure can be, for example, about 720 torr to about
800 torr. Alternatively, the pressure can be for example about 0.5
atmosphere to about 5 atmosphere, or about 0.9 atmosphere to about
1.1 atmosphere. In some embodiments, one will want if possible to
avoid the expense of using pressures below or above normal
atmospheric ambient pressure. One can use a higher pressure to
control the boiling point of the solvent. However, the equipment
must be adapted to sustain high or low pressures.
[0136] A preferred embodiment is that temperature and pressure both
are about ambient so than expensive methods to control temperature
and pressure are not needed. Hence, for example, the temperature
can be about 20.degree. C. to about 30.degree. C., or about
25.degree. C., and the pressure can be about 720 torr to about 800
torr, or about 760 torr.
[0137] Other method parameters for the reduction reaction can be
varied. For example, in one embodiment, one or more materials used
in the process can be recycled. The material can be purified as
part of the recycling. For example, solvent can be distilled and
recaptured for further use. Salts can be recaptured and reused.
[0138] In another embodiment, the current flow from a process
reactor to make carbon which is run as a galvanic cell can be used
to help power another process reactor, including one used to make
elemental carbon material, in which current is needed to help
control the voltage.
[0139] The percent yield of the reaction for elemental carbon
material product can be controlled by the amount of current flow
and the methods of isolation as known in the art. Percent yield can
be measured with respect to the amount of carbon in the carbide
chemical compound put in the reactor. In some cases, the yield is
at least one percent, or at least 5%, or at least 10%, or at least
20%.
Reactant; Metal Salt
[0140] The reactant can be, for example, a moiety which can be
reduced such as at least one metal salt, and metal salts are
well-known in the art, comprising a metal cation and an anion.
Organic reactants can also be used, in principle, if the redox
potentials allow for reaction. The reactant is selected to react
well with the nanostructured carbide chemical compound to achieve
the intended goal for the particular application (e.g., carbon
production).
[0141] In one embodiment, the reactant is selected to function in
an electrochemical reaction. In another embodiment, the reactant is
selected to function in a melt reaction. In another embodiment, the
reactant is selected to function in a solution reaction.
[0142] In the electrochemical approach, the nanostructured carbide
chemical compound is used in the form of an anode and used in
conjunction with a cathode where the reactant is reduced. For
example, the cathode can be used in conjunction with a solution
comprising a dissolved salt including a metal cation and an anion.
In principle, any ion/metal combination where the ion can be
reduced to the metal can be used for a cathode employing this
method. More specifically, in principle, any elemental metal
immersed in a solution containing ions of that metal, where the
ions can be reduced to the elemental state in order to facilitate
the oxidation of the carbide ions to elemental carbon, can be used.
Examples include zinc metal in a solution of zinc ions, tin metal
in a solution of stannous ions, silver metal in a solution of
silver ions, and iron in a solution of ferrous ions. In selecting
the cathode, practical considerations can be taken into account.
For example, issues like corrosion of the metal cathode can be
considered. Other factors to consider include, for example, the
characteristics of the solvent and the overall solution and how
they would interact with the different components of the reaction
system. Solubility of the various metallic salts in the different
solvents or solvent combinations would also be an issue.
[0143] In one embodiment, the electrochemical cell (e.g., galvanic
cell) apparatus further comprises at least one metal cathode,
wherein the cathode is a zinc, tin, iron (include steel), copper,
or silver metal cathode. In another embodiment, the electrochemical
cell (e.g., galvanic cell) apparatus further comprises at least one
metal cathode, wherein the cathode is a zinc or tin metal
cathode.
[0144] In one embodiment, the galvanic cell apparatus anode is
contacted with at least one first solution comprising at least one
first solvent and at least one first salt and a galvanic cell
apparatus cathode is also contacted with at least one second
solution comprising at least one second solvent and at least one
second salt. The solvent and salt combination for both the anode
and cathode sides of the cell should provide sufficient ionic
conductivity for the process to be enabled. The viscosity of the
solvent can be also considered in solvent selection for first and
second solvent. For first and second solvent, the solvent can be,
for example, a polar organic solvent such as an alcohol such as
methanol or ethanol, or an ether such as tetrahydrofuran, or an
aprotic solvent such as DMSO or NMP. Examples of solvents include
N-methyl pyrrolidone, dimethyl formamide, acetone, tetrahydrofuran,
pyridine, acetonitrile, methanol, ethanol, tetramethylurea, and/or
dichlorobenzene. Mixtures of solvents can be used. In general,
water is avoided in the solvent, and solvents can be dried. In some
cases, slow reaction between the solvent and the carbide chemical
compound may occur. For example, methanol can reaction with calcium
carbide to form calcium methoxide. Typically, the reaction
apparatus should be relatively inert to the solvent so that side
reactions are minimized or avoided.
[0145] The salts for the cathode and anode sides of the cell can be
selected to provide the cation or the anion which enable the
reaction to work well. For example, the cathode metal being reduced
can be used in conjunction with a salt which has the oxidized metal
as cation. The anion of the salt can be a halide such as fluoride,
chloride, bromide, or iodide. However, the fluoride can cause a
high heat of reaction which can generate problems so fluoride salts
can be avoided. Chloride salts generally are preferred. Examples of
salts include zinc chloride, calcium chloride, stannous chloride,
ferrous chloride, cupric chloride, silver chloride, aluminum
chloride, lithium chloride, calcium fluoride, stannous fluoride,
aluminum fluoride, and lithium fluoride.
[0146] An important factor also is that the cation of the carbide
must form a soluble salt with the anion of the cathode cell. This
may not be possible in some cases such as some sulfate salts
including calcium sulfate.
Electrochemical Cell Method
[0147] The electrochemical embodiments are described further. The
method of making can be based on a electrochemical cell apparatus
which can be galvanic (spontaneous reaction) or electrolytic
(non-spontaneous reaction). Preferably, the method makes use of a
galvanic reaction using a galvanic cell apparatus. Preferably, the
reaction is a spontaneous redox reaction. A galvanic reaction is
generally known in the art as a spontaneous redox reaction wherein
one moiety is oxidized and another moiety is reduced. The moieties
are connected electrically to allow current to flow and the redox
reaction to occur. A multimeter can be used to measure voltage and
current flow for such a reaction. No external electrical potential
is needed to induce the spontaneous reaction in a galvanic
reaction. However, an external electrical potential can be used to
control or modify the galvanic reaction, while the reaction is
still called a "galvanic reaction" or a "spontaneous reaction." The
discharge of the current flow can be regulated. The galvanic
reaction can be a source of power, voltage, and current, and these
reactions can be used to power other systems and loads as known in
the art.
[0148] The elements of a method using a galvanic reaction are known
and described more hereinbelow. They include, for example, at least
one anode, at least one cathode, and connections between the anode
and cathode to allow current flow and form a circuit. The
connections can provide electronic or ionic current flow. For
example, wiring can be used and devices can be used to measure the
potential and current flow. Ionic flow can be enabled with use of
salt bridges or ion exchange membranes. The salt bridge or ion
exchange membrane can have a geometry and length which help to
determine the rate of the redox reaction. The transport of the
appropriately charged moiety, an anion, can be mediated through the
salt bridge or the ion exchange membrane to complete the circuit.
For instance, in one embodiment, a cation such as a zinc cation
dissolved in the solution in the metal cell cannot migrate or
transfer through the ion exchange membrane. However the anion
(e.g., Cl.sup.-) is able to diffuse through the membrane and into
the carbide cell. In one embodiment, the salt bridge is replaced
with, or used with, or comprises an ion exchange membrane. In any
event, the salt bridge or ion exchange membrane can be adapted to
avoid being a rate limiting step ("bottle neck") for the process
and pass as much charge as possible.
[0149] The elements of a method using an electrolytic reaction are
also known.
[0150] In one embodiment, the electrochemical cell (e.g., galvanic
cell) apparatus further comprises at least one cathode which can be
a metal cathode. Mixtures of metals can be used.
[0151] The cathode can be used in conjunction with a solution
comprising a dissolved salt including a metal cation and an anion.
In principle, any ion/metal combination where the ion can be
reduced to the metal can be used for a cathode employing this
method. More specifically, in principle, any elemental metal
immersed in a solution containing ions of that metal, where the
ions can be reduced to the elemental state in order to facilitate
the oxidation of the carbide ions to elemental carbon, can be used.
Examples include zinc metal in a solution of zinc ions, tin metal
in a solution of stannous ions, silver metal in a solution of
silver ions, and iron in a solution of ferrous ions. In selecting
the cathode, practical considerations can be taken into account.
For example, issues like corrosion of the metal cathode can be
considered. Other factors to consider include, for example, the
characteristics of the solvent and the overall solution and how
they would interact with the different components of the reaction
system. Solubility of the various metallic salts in the different
solvents or solvent combinations would also be an issue.
[0152] In one embodiment, the electrochemical cell (e.g., galvanic
cell) apparatus further comprises at least one metal cathode,
wherein the cathode is a zinc, tin, iron (include steel), copper,
or silver metal cathode. In another embodiment, the electrochemical
cell (e.g., galvanic cell) apparatus further comprises at least one
metal cathode, wherein the cathode is a zinc or tin metal
cathode.
[0153] In one embodiment, the galvanic cell apparatus anode is
contacted with at least one first solution comprising at least one
first solvent and at least one first salt and a galvanic cell
apparatus cathode is also contacted with at least one second
solution comprising at least one second solvent and at least one
second salt. The solvent and salt combination for both the anode
and cathode sides of the cell should provide sufficient ionic
conductivity for the process to be enabled. The viscosity of the
solvent can be also considered in solvent selection for first and
second solvent. For first and second solvent, the solvent can be,
for example, a polar organic solvent such as an alcohol such as
methanol or ethanol, or an ether such as tetrahydrofuran, or an
aprotic solvent such as DMSO or NMP. Examples of solvents include
N-methyl pyrrolidone, dimethyl formamide, acetone, tetrahydrofuran,
pyridine, acetonitrile, methanol, ethanol, tetramethylurea, and/or
dichlorobenzene. Mixtures of solvents can be used. In general,
water is avoided in the solvent, and solvents can be dried. In some
cases, slow reaction between the solvent and the carbide chemical
compound may occur. For example, methanol can react with calcium
carbide to form calcium methoxide. Typically, the reaction
apparatus should be relatively inert to the solvent so that side
reactions are minimized or avoided.
[0154] The salts for the cathode and anode sides of the cell can be
selected to provide the cation or the anion which enable the
reaction to work well. For example, the cathode metal being reduced
can be used in conjunction with a salt which has the oxidized metal
as cation. The anion of the salt can be a halide such as fluoride,
chloride, bromide, or iodide. However, the fluoride can cause a
high heat of reaction which can generate problems so fluoride salts
can be avoided. Chloride salts generally are preferred. Examples of
salts include zinc chloride, calcium chloride, stannous chloride,
ferrous chloride, cupric chloride, silver chloride, aluminum
chloride, lithium chloride, calcium fluoride, stannous fluoride,
aluminum fluoride, and lithium fluoride.
[0155] An important factor also is that the cation of the carbide
must form a soluble salt with the anion of the cathode cell. This
may not be possible in some cases such as some sulfate salts
including calcium sulfate.
[0156] In one embodiment, the galvanic cell apparatus further
comprises at least one salt bridge and/or at least one ion exchange
membrane. Ion exchange membranes are known in the art and typically
are made of a polymeric material attached to charged ion groups.
Anion exchange membranes contain fixed cationic groups with mobile
anions; they allow the passage of anions and block cations. Cation
exchange membranes contain fixed anionic groups with mobile
cations; they allow the passage of cations and block anions. See,
for example, Y. Tanaka, Ion Exchange Membranes: Fundamentals and
Applications, 2.sup.nd Ed., 2015. Herein, the use of ion exchange
membranes can help prevent formation of unwanted side products and
migration of undesired materials from one cell to the other
cell.
[0157] In one embodiment, steps are taken so that the reaction is
carried out under anhydrous conditions. Moisture can be excluded to
the extent needed. Also, inert gases can be used such as argon or
nitrogen.
[0158] The reaction time can be adapted to the need. Reaction time
can be, for example, one minute to 30 days, or one day to 20
days.
[0159] In one embodiment, the production of carbon is carried out
without use of an external voltage source. The current flow from
the spontaneous reaction is not controlled by external voltage in
this embodiment.
[0160] In another embodiment, however, the galvanic cell apparatus
comprises an external voltage source which is used to regulate the
oxidation reaction, and in another embodiment, the production of
carbon is carried out with use of an external voltage source to
regulate the oxidation reaction. This can also be called a "forced
current" embodiment. The application of an external voltage source
allows one to control the voltage over time using a controlled
voltage over time curve, including a step curve, for example.
Constant voltage and/or constant current regimes can be used. Over
time, voltage can be increased or decreased. Reaction rate can be
controlled and increased using the external voltage. For example,
reaction rate (current flow in amperage) might increase at least
ten times, or at least twenty times, or at least fifty times, or at
least 100 time, or at least 250 times, for example, with the
application of external voltage compared to cases with no external
voltage applied. The level of external voltage can be determined
for a particular system. One wants to avoid side reactions. One
often will want to increase reaction rate. Voltage can be, for
example, 0 V to 40 V, or 0 V to 30 V, or 0 V to 20 V, or 10 V to 20
V. The external voltage source can be applied with use of a
potentiostat as known in the art.
[0161] In one embodiment, the electrochemical cell apparatus is an
electrolytic cell apparatus. Here, the reaction is not spontaneous,
and an external voltage needs to be and is applied to drive the
reaction. An example is making lithium or sodium.
Organic Solvent Reaction to Produce Carbon from Carbide
[0162] The solution reaction embodiment is described more. Another
aspect is provided for the production of elemental carbon material
from nanostructured carbide chemical compound at normal temperature
and pressure but without an electrochemical apparatus. Here, a
method is provided comprising: producing elemental carbon material
from the oxidation of carbide in at least one nanostructured
carbide chemical compound (e.g., calcium carbide) which is in
contact with a solution comprising at least one organic solvent
(e.g., methanol) and at least one reactant, such as dissolved salt
(e.g., calcium chloride), comprising at least one metal cation
which is reduced. If a cation is used, the cation is selected so
that a spontaneous reaction can occur wherein the carbide is
oxidized and the metal cation is reduced. However, in this
embodiment, the molten salt approach and the electrochemical
approach described herein are not used. Rather, in this embodiment,
the reaction can be carried out in a single reaction container and
need not be split into two cells as is done with the
electrochemical reaction.
[0163] In this embodiment, the temperature and pressure can be as
described above. Normal temperature and pressure can be used.
However, heat or cooling can be applied if desired.
[0164] The carbide chemical compound can be as described herein
using, for example, aluminum carbide or calcium carbide. The
selection of salts, cations, and anions also can be made as
described herein.
[0165] Examples of the organic solvent include solvents listed
herein for the electrochemical reaction such as an alcohol such as
methanol or ethanol as described herein. Polar solvents are needed
which can dissolve a salt. A protic solvents can be used. Ideally,
the solvent would not react with nanostructured carbide chemical
compound. Alternatively, it reacts with carbide but only very
slowly.
[0166] The elemental carbon material produced is described herein
also.
[0167] The reaction time can be adapted to the need.
[0168] Anhydrous reaction conditions can be used. For example, a
dry box can be used to avoid side reactions with water or
oxygen.
Apparatus
[0169] Devices and apparatuses for the reaction of nanostructured
carbide chemical compound can be adapted for the method, e.g.,
whether an electrochemical, melt, or solution method.
[0170] Another aspect provides for an apparatus which can be used
to carry out the methods described herein, including an apparatus
comprising at least one electrochemical cell comprising: at least
one anode comprising at least one nanostructured carbide chemical
compound, and at least one cathode. This apparatus can be used to
carry out the methods described and/or claimed herein. Carbide
electrode structures which can be used in the apparatus are
described further hereinbelow. Elemental carbon material reaction
products are described further hereinbelow. Other embodiments
include methods of making these apparatuses. A plurality of
apparatuses can be used in a larger system if desired.
[0171] The electrochemical apparatus can be a galvanic cell
apparatus or an electrolytic cell apparatus. The galvanic cell is
preferred.
[0172] In one embodiment, the nanostructured carbide chemical
compound is a salt-like carbide or an intermediate transition metal
carbide. In one embodiment, the nanostructured carbide chemical
compound is a salt-like carbide. In one embodiment, the
nanostructured carbide chemical compound is a methanide, an
acetylide, or a sesquicarbide. In one embodiment, the
nanostructured carbide chemical compound is calcium carbide,
aluminum carbide, sodium carbide, magnesium carbide, lithium
carbide, beryllium carbide, iron carbide, copper carbide, and
chromium carbide. In one embodiment, the nanostructured carbide
chemical compound is calcium carbide or aluminum carbide. In one
embodiment, the nanostructured carbide chemical compound has
sufficient electronic conductivity to function as an anode. In one
embodiment, the nanostructured carbide chemical compound has an
electronic conductivity of at least 10.sup.-8 S/cm, or at least
10.sup.-7 S/cm, or at least 10.sup.-6 S/cm, or at least 10.sup.-5
S/cm, or at least 10.sup.-4 S/cm, or at least 10.sup.-3 S/cm, or at
least 10.sup.-2 S/cm, or at least 10.sup.-1 S/cm, or at least
10.sup.0 S/cm. The electronic conductivity of calcium carbide
provides a useful benchmark for sufficient conductivity. No
particular upper limit is present except for the limits provided by
nature for a particular nanostructured carbide.
[0173] In one embodiment, the nanostructured carbide chemical
compound is held in a container.
[0174] In one embodiment, the galvanic cell apparatus anode is
contacted with a solution comprising at least one solvent and at
least one salt.
[0175] In one embodiment, the electrochemical cell apparatus anode
is contacted with a solution comprising at least one organic
solvent and at least one dissolved salt, as described above. In one
embodiment, the electrochemical cell apparatus cathode is contacted
with a solution comprising at least one organic solvent and at
least one dissolved salt as described above. In one embodiment, the
electrochemical cell apparatus cathode is a metal cathode as
described above. In one embodiment, the electrochemical cell
apparatus cathode is a metal cathode, wherein the metal is zinc,
tin, iron, copper, or silver. In one embodiment, the
electrochemical cell apparatus cathode is a metal cathode, wherein
the metal is zinc or tin.
[0176] In one embodiment, the electrochemical cell apparatus
comprises an external voltage source to regulate an oxidation
reaction of carbide in the carbide chemical compound. For example,
a potentiostat can be used to provide such an external voltage
which can be varied.
[0177] In one embodiment, the apparatus is adapted for carrying out
the methods described and/or claimed herein.
The Carbide Electrode Structure and Methods of Use
[0178] The nanostructured carbide chemical compound can be used in
and adapted for use in an electrode structure. Hence, yet another
aspect provides for an electrode structure comprising at least one
nanostructured carbide chemical compound. Optionally the carbide
chemical compound is a salt-like carbide. Optionally, at least one
electronically conductive element different from the carbide
chemical compound forms part of the electrode structure. This
electrode structure can be used to carry out the methods and to
prepare the apparatuses described and/or claimed herein.
Embodiments described herein also include methods of making and
methods of using the nanostructured carbide electrode structure.
Multiple electrode structures can be used as part of a larger
electrode system. The shape of the electrode can be varied for the
need. The conductivity of the electrode can be adapted to the need.
The solid properties and macro-, micro-, and nano-scale morphology,
such as the size and shapes of openings, porosity, and pore size,
can be adapted to the need.
[0179] The solid electrode structure and the nanostructured carbide
chemical compound can be contacted with at least one liquid for a
redox reaction. The electrode structure provides a reaction of the
carbide chemical compound which is not just a surface reaction but
can extend to the internal structure of the carbide chemical
compound. While the present inventions are not limited by theory,
it is believed that the carbon carbide layer of the carbon compound
at the surface is reacted to form elemental carbon material as the
cation (e.g, calcium) is transported away from the carbon into
solution. Multiple layers of carbon can be built up. The surface of
the carbide can have some porosity.
[0180] The carbide electrode can be an electrode (an anode) where
the chemical reaction can occur within the electrode instead of
just at the surface. The electrode material itself (e.g., calcium
carbide) is being consumed in the reaction where the calcium ion
dissolves into the solution and the elemental carbon material is
remaining.
[0181] In one embodiment, the carbide chemical compound of the
electrode is a salt-like carbide or an intermediate transition
metal carbide. In one embodiment, the carbide chemical compound is
a salt-like carbide. In one embodiment, the carbide chemical
compound is a methanide, an acetylide, or a sesquicarbide.
[0182] In one embodiment, the carbide chemical compound is calcium
carbide, aluminum carbide, sodium carbide, magnesium carbide,
lithium carbide, beryllium carbide, iron carbide, copper carbide,
chromium carbide, and chromium carbide. In one embodiment, the
carbide chemical compound is calcium carbide, aluminum carbide,
sodium carbide, magnesium carbide, lithium carbide, or beryllium
carbide. In one embodiment, the carbide chemical compound is
calcium carbide or aluminum carbide, preferably calcium carbide. In
one embodiment, the carbide chemical compound has sufficient
electronic conductivity to function as an anode. In one embodiment,
the carbide chemical compound has an electronic conductivity of at
least 10.sup.-8 S/cm or other ranges described herein such as at
least 10.sup.-7 S/cm, or at least 10.sup.-6 S/cm, or at least
10.sup.-5 S/cm, or at least 10.sup.-4 S/cm, or at least 10.sup.-3
S/cm, or at least 10.sup.-2 S/cm, or at least 10.sup.-1 S/cm, or at
least 10.sup.0 S/cm. No particular upper limit is present except
for the limits provided by nature for a particular carbide. In one
embodiment, the carbide chemical compound is an ionically bonded
solid.
[0183] In one embodiment, the carbide chemical compound is in the
form of individual pieces or particles which have to be contained
within an electrode structure. In one embodiment, the carbide
chemical compound is produced in a form to provide maximum or large
amounts of surface area. This can facilitate reaction of the
carbide at its surface. The particle size and surface area can be
adapted to the multiple needs.
[0184] In some embodiments, the carbide chemical compound can be
used with one or more additional, different materials such as an
additive. Materials and additives which are useful for making
electrodes can be used. For example, a binder can be used.
[0185] In one embodiment, the nanostructured carbide chemical
compound is held in a container. In one embodiment, the container
has openings which allow fluid, such as an electrolyte, to enter
the container and contact the carbide chemical compound. Of course,
the container must be able to contain the nanostructured carbide
chemical compound.
[0186] In one embodiment, the nanostructured carbide chemical
compound is divided into portions. In one embodiment, the carbide
chemical compound is divided into approximately equal portions.
[0187] In one embodiment, the nanostructured carbide chemical
compound used in the electrode is at least about 80 wt. % pure, or
at least 90 wt. % pure, or at least 95 wt. % pure, or at least 97
wt. % pure.
[0188] The electronically conductive element should have good
electronic conductivity such as, for example, at least 10.sup.-3
S/cm, or at least 10.sup.-2 S/cm, or at least 10.sup.-1 S/cm, or at
least 10.sup.0 S/cm.
[0189] In one embodiment, the electronically conductive element is
a binder for the carbide chemical compound.
[0190] In one embodiment, the electronically conductive element is
adapted to be non-reactive with the reaction media. For example, it
should be inert to the contacting solution, or at least inert
enough to effectively conduct the reaction for the need.
[0191] In one embodiment, the electronically conductive element is
a container and the carbide chemical compound is held in the
container.
[0192] In one embodiment, the electronically conductive element is
a metallic container and the carbide chemical compound is held in
the metallic container. In one embodiment, the electronically
conductive element is a non-metallic container such as graphite and
the carbide chemical compound is held in the non-metallic container
such as graphite. For example, graphite baskets can be used.
[0193] In one embodiment, the electronically conductive element
comprises at least one conductive rod.
[0194] In one embodiment, the electrode structure is adapted to be
removably attached to an apparatus.
[0195] In one embodiment, the electronically conductive element of
the electrode structure comprises at least one current
collector.
[0196] In one embodiment, the electrode structure is adapted for
use as an anode in, for example, an electrochemical cell
apparatus.
[0197] For example, provided is a method comprising operating at
least one anode in an electrochemical cell, wherein the anode
comprises at least carbide chemical compound which includes a
method comprising operating at least one anode in a galvanic cell,
wherein the anode comprises at least carbide chemical compound. The
electrochemical cell apparatus can be a galvanic cell apparatus or
an electrolytic cell apparatus. The apparatus can be used for
production of elemental carbon material. However, other embodiments
are possible for uses other than the production of elemental carbon
material. Other uses of the apparatus with the carbide electrode
include oxidation reactions such as, for example, conversion of
aldehyde to carboxylic acid, and oxidation of a metal such as
ferrous ion to ferric ion. Such reactions could be useful in, for
example, environmental processes such as, for example, acid mine
drainage or sewage treatment.
[0198] In most cases, the one or more nanostructured carbide
chemical compounds is the only electrochemically reactive moiety
participating in the oxidation part of the redox reaction. In one
embodiment, the anode electrochemically active material consists
essentially of at least one nanostructured carbide chemical
compound. In another embodiment, the anode electrochemically active
materials consist of at least one nanostructured carbide chemical
compound. Here, a conductor such as a metal which is not oxidized
or reduced in the anode is not considered an electrochemically
active material.
Carbon Product
[0199] Still further, another aspect provides for an elemental
carbon material composition prepared by the methods, or with use of
the apparatuses or carbide electrode structures, described and/or
claimed herein. The elemental carbon material can be described
and/or claimed by the characteristics of the elemental carbon
material and/or by how it was made. Elemental carbon materials are
materials known in the art to focus on the carbon content and do
not include organic compounds such as methane, methanol, or acetic
acid. Examples such as graphite and diamond are well-known as
elemental carbon materials. These compositions can range from the
compositions as initially prepared from the carbide chemical
compound to the compositions as they exist after one or more
treatment, purification, and/or separation steps (post-processing
steps including exfoliation and doping steps, for example). The
compositions can be mixtures of different forms of the elemental
carbon material. The composition can comprise crystalline portions
and/or amorphous portions. The carbon can be in the form of one or
more graphene layers, and it can be in an exfoliated form.
Preferred embodiments for graphene include atomically thin single
sheet graphene or few layer graphene. Graphene can have 1-10 layers
for example. Thicker forms of graphene also can be of interest.
Also, the elemental graphene material, including graphene forms,
can be disposed on substrate films.
[0200] Because the carbide chemical compound is nanostructured, the
elemental carbon products which are nanostructured are of
particular interest. In some cases, the carbon product may have a
shape that is similar to the shape of the carbide chemical compound
undergoing reaction.
[0201] Characterization methods for elemental carbon materials are
well known and include analysis of microstructure, morphology, and
physical properties. For example, carbon black materials are well
known and characterized as described in, for example, (1) Carbon
Black: Production, Properties, and Uses (Sanders et al., Eds.), and
(2) Carbon Black: Science and Technology, 2.sup.nd Ed., (Donnet et
al., Eds.) 1993. Morphological properties of elemental carbon
materials include, for example, particle size, surface area,
porosity, aggregate size, and aggregate shape. Physical properties
include density, electronic, thermal, bulk, and impurities.
Microstructure analysis includes XRD, Dark Field Electron
Microscopy, Oxidation Studies, Diffracted Beam Electron Microscopy,
Phase Contrast TEM imaging, and High Resolution SEM, STEM, STM,
SFM, and AFM imaging.
[0202] Other characterization methods for carbon are known and
described further herein. See, for example, review article by Chu
et al., Materials Chemistry and Physics, 96 (2006), 253-277, which
describes characterization of amorphous and nanocrystalline carbon
films. Methods described include optical (Raman, both visible and
UV, and IR), electron spectroscopy and microscopy (e.g, XPS, AES,
TEM of various kinds, and EELS), surface morphology (AFM, SEM),
NMR, and X-ray reflectivity. Methods described include how to
measure sp2:sp3 ratios.
[0203] The elemental carbon material can provide many novel,
interesting, and useful structures when viewed under an SEM,
including at a 200 micron scale bar view or less. Features shown in
the SEM figures can be used to describe and claim the elemental
carbon materials. Spots on the elemental carbon material also can
be selected for Raman spectroscopy, and Raman data can also be used
to describe and claim the elemental carbon materials. Other data
such as EDAX and XRD can also be used to describe and claim the
elemental carbon materials.
[0204] Generally, high purity elemental carbon materials are
desired. In one embodiment, the elemental carbon material is more
than 70%, or more than 80%, or more than 90%, or more than 95%, or
more than 98%, or more than 99% (atomic percentage) carbon. This
percentage can be measured by, for example, elemental analysis
methods including SEM-EDAX. Of course, in some embodiments, less
high purity may be acceptable. Also, in some embodiments,
non-carbon elements can be deliberately incorporated such as in a
doping process.
[0205] In one embodiment, the elemental carbon material is more
than 50%, or more than 60%, or more than 70%, or more than 80%, or
more than 90% sp2 carbon. A combination of analytical techniques
can be used to determine an accurate estimate. For example, there
is also the possibility of analysis using bromine. Sp2 carbon
absorbs a certain amount of bromine relative to amorphous carbon or
even possibly sp1 carbon if we can produce it. Sp3 carbon does not
absorb bromine at all. Therefore, we may be able to quantitatively
determine these percentages using a type of bromine absorption
test.
[0206] In one embodiment, the elemental carbon material is more
than 50%, or more than 60%, or more than 70%, or more than 80%, or
more than 90% sp3 carbon.
[0207] In one embodiment, the elemental carbon material comprises
two-dimensional plate-like structures. These structures can be
stacked on top of one another. In another embodiment, the elemental
carbon material comprises three-dimensional structures.
[0208] In some embodiments, the elemental carbon material has
amorphous carbon content. In other cases, crystalline carbon can be
present.
[0209] In some cases, particles can be isolated, and average
particle size (d.sub.50) can be, for example, 500 nm to 500
microns, or one micron to 100 microns, or two microns to 50
microns, or 10 microns to 30 microns. If desired, nanoscopic
particles can be isolated with average particle size of less than
500 nm such as, for example, 10 nm to 500 nm, or 20 nm to 100 nm.
Commercial particle size analyzers can be used to measure particle
size.
[0210] The elemental carbon material, at various stages of
purification and isolation, can be tested by methods known in the
art including, for example, optical microscopy, electron microscopy
including scanning electron microscopy (SEM) and transmission
electron microscopy (TEM), energy dispersive x-ray analysis (EDX),
Raman and FTIR spectroscopy, x-ray diffraction, X-ray photoelectron
spectroscopy (XPS), Auger electron spectroscopy (AES), low energy
and high energy electron energy loss spectroscopy (EELS), neutron
scattering, ellipsometry, electrical resistance, and atomic force
microscopy (AFM). Particle analysis can also be carried out
including measurement of particle size and surface area.
Electrochemical testing can also be carried out. Tribology, wear,
friction, indentation, modulus, hardness testing can also be
carried out.
[0211] For Raman spectroscopy, a G band (around 1590 cm.sup.-1) can
be present in crystalline graphite and a D band (around 1345
cm.sup.-1) can be present associated with disordered graphite. The
ratio of the two bands can be used to characterize the degree of
graphitization and the graphite crystallite size.
[0212] The elemental carbon material produced can be analyzed by
surface analytical methods such as AFM or XPS. For example, XPS
analysis can show higher levels of oxygen at the surface than in
the bulk material. This can mean that the surface of the material
had formed graphene oxide. Graphene oxide, in principle, could be
formed as part of the reaction or due to the separation and
purification operations. Other surface elements can include O, H,
N, S, and halogens.
[0213] In another embodiment, the elemental carbon material
comprises sp1 carbon material.
[0214] In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that is C.sub.70. In some
embodiments, the methods can be used to produce an allotrope of
carbon that is C.sub.60. Other kinds of fullerenes can be made. In
some embodiments, the methods described herein can be used to
produce an allotrope of carbon that is Herringbone Multi Wall
Carbon Nano Tubes ("MWCNT"). Single-walled carbon nanotubes also
can be made. In some embodiments, the methods described herein can
be used to produce an allotrope of carbon that is Cylindrical
MWCNT. In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that comprises carbon
fibers.
[0215] The methods described herein can produce carbon with
sp.sup.1, sp.sup.2, and/or sp.sup.3 hybridization, as well as
mixtures thereof. The sp.sup.1 hybridized carbon can be in the form
of carbyne. The sp.sup.2 hybridized carbon can be in the form of
carbene, graphite, and/or graphene. The sp.sup.3 hybridized carbon
can be in the form of diamond.
[0216] Particular carbon materials may thus be produced through the
application of external voltage to an electrolysis cell wherein at
least one of the electrodes is a carbide.
[0217] In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that is sp.sup.2 hybridized,
and contains no sp.sup.3 hybridization. In some embodiments, the
methods described herein produce an allotrope of carbon that is
sp.sup.3 hybridized, and contains no sp.sup.2 hybridization. In
some embodiments, the methods described herein produce an allotrope
of carbon that is sp.sup.1 hybridized and contains neither sp.sup.2
or sp.sup.3 hybridization.
[0218] In some cases, the elemental carbon material can have more
sp2 than sp3 hybridized carbons, and in other cases, the elemental
carbon material can have more sp3 than sp2 hybridized carbons. The
ratio of sp2:sp3 can be, for example, 1:10 to 10:1, or 1:8 to 8:1,
or 1:6 to 6:1, or 1:4 to 4:1, or 1:2 to 2:1.
[0219] The methods described herein can be used to produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.1 hybridized.
[0220] In an embodiment, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.2 hybridized.
[0221] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.3 hybridized.
[0222] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.2 hybridized in the form
of graphite.
[0223] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.3 hybridized in the form
of diamond.
[0224] Large area pieces of carbon, having high levels of elemental
carbon purity, are of particular interest. They can be, for
example, a source for large area graphene. The piece may have a
lateral dimension of, for example, at least one mm, or at least two
mm, or at least one cm, or at least two cm. The lateral dimension
can be a length or a width of a piece or particle. In some cases,
both the length and the width can be at least 1 mm, or at least 2
mm, or at least 1 cm, or at least two cm. The volume of the piece
can be, for example, at least one cubic mm, or at least one cubic
cm (cc), or at least 8 cubic cm (cc). Also important are forms of
carbon having flat surfaces whether of lower or higher flat surface
area.
[0225] Carbon structures are shown in the SEM and optical
photographs provided herein which can be of commercial use. In many
cases, it is desired to have crystalline forms of the elemental
carbon material rather than amorphous forms.
[0226] In some embodiments, the elemental carbon material comprises
at least some two-dimensional plate-like structures. In some
embodiments, the elemental carbon material comprises at least some
two-dimensional plate-like structures stacked on top of one
another. Graphene structures may be evident. Thicker graphene
structures can be converted to thinner graphene structures. In some
embodiments, the elemental carbon material comprises at least some
three-dimensional structures.
[0227] In some embodiments, the elemental carbon material shows
porous structures or voids.
[0228] In some embodiments, bent structures can be seen. The bent
structure can be characterized by an acute angle, and the angle can
be controlled by the synthesis method. In other embodiments, rods
can be formed. In some embodiments, curved elemental particles can
be observed. In some embodiments, perpendicular features can be
observed.
[0229] Further structures can be observed with higher resolution
analytical methods.
Post Reaction Processing of Elemental Carbon Material
[0230] After forming in the apparatus, the elemental carbon
material can be further treated beginning with, for example,
purification and/or mechanically changing the form into, for
example, other powder or particle forms. Treatments can be
mechanical or chemical. The piece of product can be subjected to
various mechanical steps such as grinding, exfoliation, or
polishing steps. Additional treatment steps can include, for
example, doping and intercalation steps. Some of the elemental
carbon material may be attached to the electrode and will need to
be removed from the electrode. Other elemental carbon material may
leave the electrode during the reaction and may, for example, sink
to the bottom of the reaction cell for collection. Process steps
can be carried out to separate carbon from non-carbon materials,
and separate one form of carbon from another form of carbon.
[0231] PCT Application PCT/US2014/028755, filed Mar. 14, 2014 and
published as WO 2014/144374, also describes a method of making
carbon from carbide and metal salts in a thermal process, and also
describes various post reaction processing steps which can be
used.
[0232] In another embodiment, the elemental carbon material is
removed and treated with acid and washed or flushed with water.
Strong acids such as HCl can be used.
[0233] In one embodiment, the elemental carbon material can be
converted to a different particle form, and the particles separated
based on particle size.
[0234] Graphene exfoliation steps are known in the art and
described in, for example, Bonaccorso et al., Materials Today,
December 2012, 15, 12, 564. In particular, large area graphene
sheet production is of interest. The large pieces of elemental
carbon material produced by methods described herein can enable
production of large area graphene. A solvent such as NMP can be
used for exfoliation. Sonication can also be used for exfoliation.
Larger pieces of carbon in many cases require higher power to
exfoliate. The exfoliation process can be controlled so as to
control the thickness of the exfoliated product, such as graphene.
Electrochemical exfoliation can be carried out.
[0235] Also described herein are derivative compositions associated
with the elemental carbon material compositions described herein.
For example, the elemental carbon material compositions described
herein can be mixed with or doped with other elements, compounds,
ingredients, additives, and/or materials.
Applications
[0236] Selected representative examples of applications are
described below. Devices, apparatuses, systems, kits, methods of
making, and methods of using that are associated with these
applications are also described herein including devices,
apparatuses, systems, and kits which comprise the elemental carbon
materials and their derivatives described herein (e.g., battery,
fuel cell, or filtration devices). The elemental carbon reaction
products, whether in bulk form, microscale form, or nanoscale form,
can be used in a wide-variety of applications including, for
example, applications generally known for carbon materials
including applications known, more specifically, for graphite
materials, applications known for diamond materials, applications
known for amorphous carbon, and applications known for nanoscale
forms of carbon, for example. In some cases, the elemental carbon
material can be mixed with one or more other ingredients for
application use.
[0237] Carbon black, for example, is used as filler, pigment,
toners, and reinforcement agent.
[0238] Many applications relate to the electrically conductive
properties of carbon and the electronics and semiconductor
industries. For example, carbon inks are known including conductive
inks. Carbon-based fillers or conductive agents are known.
[0239] Activated carbon has many applications. Sorbent applications
can be carried out. In general, applications of the carbon which
require high surface area carbon can be found. Sorbents can be, for
example, used as soil detoxicants, gas drying agents, chemical
adsorbents, and catalysts.
[0240] Graphite is a material found in nature and also is
synthetically produced. Examples of natural graphite are flake,
crystalline, and amorphous graphite. Graphite flakes can have flat,
plate-like particles with hexagonal or angular edges. The percent
carbon can impact the application. Graphite can be used as
electrodes, pastes, brushes, crucibles, lubricants, foundry
facings, moderator bricks in atomic reactors, paints, pencils,
brake linings, foundry operations, refractory applications, steel
making, lithium-ion batteries, fuel cells, and the like.
[0241] In particular, batteries including lithium and lithium-ion
batteries can be an application, as well as air batteries such as
zinc air batteries. Lithium-ion batteries are described in, for
example, Yoshio et al. (Eds.), Lithium-Ion Batteries: Science and
Technologies, including chapter 3 (pages 49-73) and chapter 18
(pages 329-341) which focus on carbon anode materials, as well as
chapter 5 (pages 117-154) which focuses on carbon-conductive
additives and chapter 22 (pages 427-433) which focuses on novel
hard-carbon materials.
[0242] Graphene can be used in advanced semiconductor devices.
Large area graphene is important. Other applications include
filters (including water filtration and desalinization of sea
water), batteries, touch screens, capacitors, fuel cells, sensors,
high frequency circuits, flexible electronics, computing, data
storage, solar, and photovoltaics.
[0243] Diamonds can be low quality or high quality and are applied
in applications which use hardness including abrasion resistant
materials, as well as drilling, polishing, and cutting materials.
Diamonds also can be used for sensors, electronics, medical
imaging, semiconductors, super computers, and sonar. Diamonds also
can be gems.
[0244] Carbon related materials such as CaC.sub.6 have been shown
to be superconducting. Other applications for sp1 materials relate
to use of superconductor materials and even high temperature or
room temperature superconductor materials.
[0245] Carbon nanotube products can be in the form of "forests" of
microscopic tubular structures. They can be used in, for example,
baseball bats, aerospace wiring, combat body armor, computer logic
components, and microsensors in biomedical applications. Carbon
nanotubes also can be used in lithium ion batteries and various
sporting equipment.
[0246] Another type of application is the use of the nanostructured
carbide chemical compound for other uses besides making carbon such
as a use as catalysts.
Example
[0247] In one example, a nanostructured calcium carbide material is
prepared according to CN 1498976 using the Union Process. The
average particle size is about 100 nm, although other average
particle sizes such as 50-250 nm can be made. The nanostructured
calcium carbide is then subject to reaction with a reactant to form
carbon, wherein the reactant is provided in a melt phase or in
solution. Alternatively, the nanostructured calcium carbide can be
integrated into an electrode structure and placed in an
electrochemical cell to provide the reaction to form carbon.
[0248] The various embodiments and claims described herein can be
combined with other embodiments and claims described herein.
* * * * *