Title of Invention

"A CIGARETTE COMPRISING A CATALYST TO REDUCE CARBON MONOXIDE AND NITRIC OXIDE FROM THE MAINSTREAM SMOKE THEREOF"

Abstract Cut filler compositions, cigarettes, methods for making cigarettes and methods for smoking cigarettes are provided, which involve the use of a catalyst capable converting carbon monoxide to carbon dioxide and/or nitric oxide to nitrogen. Cut filler compositions comprise tobacco and at least one catalyst. Cigarettes are provided, which comprise a cut filler having at least one catalyst. The catalyst comprises nanoscale metal and/or metal oxide particles supported on a fibrous support. The catalyst can be prepared by combining a dispersion of nanoscale particles with a fibrous support, or by combining a metal precursor solution with a fibrous support and then heat treating the fibrous support.
Full Text Field of the Invention
The invention relates generally to methods for reducing constituents such as carbon
monoxide in the mainstream smoke of a cigarette during smoking. More specifically, the invention relates to cut filler compositions, cigarettes, methods for making cigarettes and methods for smoking cigarettes, which involve the use of nanoparticle additives capable of reducing the amounts of various constituents in tobacco smoke.
Background of the Invention In the description that follows reference is made to certain structures and methods, however, such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art. Smoking articles, such as cigarettes or cigars, produce both mainstream smoke during a puff and sidestream smoke during static burning. One constituent of both mainstream smoke and sidestream smoke is carbon monoxide (CO). The reduction of carbon monoxide in smoke is desirable.
Catalysts, sorbents, and/or oxidants for smoking articles are disclosed in the following: U.S. Patent No. 6,371,127 issued to Snider et al., U.S. Patent No. 6,286,516 issued to Bowen et al., U.S. Patent No. 6,138,684 issued to Yamazaki et al., U.S. Patent No. 5,671,758 issued to Rongved, U.S. Patent No. 5,386,838 issued to Quincy, III et al., U.S. Patent No. 5,211,684 issued to Shannon et al., U.S. Patent No. 4,744,374 issued to Deffeves et al., U. S. Patent No. 4,453,553 issued to Cohn, U.S. Patent No. 4,450,847 issued to Owens, U.S. Patent No. 4,182,348 issued to Seehofer et al., U.S. Patent No. 4,108,151 issued to Martin et al., U.S. Patent No. 3,807,416, and U.S. Patent No. 3,720,214. Published applications WO 02/24005, WO 87/06104, WO 00/40104 and U.S. Patent Application Publication Nos. 2002/0002979
Al, 2003/0037792 Al and 2002/0062834 Al also refer to catalysts, sorbents, and/or oxidants.
Iron and/or iron oxide has been described for use in tobacco products (see e.g., U.S. Patent No. 4,197,861; 4,489,739 and 5,728,462). Iron oxide has been described as a coloring agent (e.g. U.S. Patent Nos. 4,119,104; 4,195,645; 5,284,166) and as a burn regulator (e.g. U.S. Patent Nos. 3,931,824; 4,109,663 and 4,195,645) and has been used to improve taste, color and/or appearance (e.g. U.S. Patent Nos. 6,095,152; 5,598,868; 5,129,408; 5,105,836 and 5,101,839).
WO 03/020058 discloses cut filler compositions, cigarettes, methods for making cigarettes and methods for smoking cigarettes involving the use of nanoparticle metal oxide additives, such as Fe2O3, CUO, TiO2, CeO2, Ce2O3 or Al2O3, capable of acting as oxidants for the conversion of carbon monoxide to carbon dioxide and/or as catalysts for the conversion of carbon monoxide to carbon dioxide.
GB 1204353 discloses a composition for use as an absorbent, catalyst and catalyst support, which comprises discrete particles of an activated alumina hydrate having activated carbon impregnated in and firmly bound thereto. The composition is formed by contacting an activated alumina hydrate in particulate form with a liquid phase carbonaceous material that can be converted to an activated carbon by heating.

Despite the developments to date, there remains a need for improved and more efficient methods and compositions for reducing the amount of carbon monoxide in the mainstream smoke of a smoking article during smoking.
Summary Tobacco cut filler compositions, cigarette fillers and/or cigarette paper, cigarettes, methods for making cigarettes and methods for smoking cigarettes that involve the use of catalysts for the conversion of carbon monoxide in mainstream smoke to carbon dioxide and/or the conversion of nitric oxide in mainstream smoke to nitrogen are provided. One embodiment provides a cut filler composition comprising tobacco and a catalyst for the conversion of carbon monoxide in mainstream smoke to carbon dioxide and/or nitric oxide in mainstream smoke to nitrogen, wherein the catalyst comprises nanoscale metal particles and/or nanoscale metal oxide particles supported on a fibrous support. Another embodiment provides a cigarette comprising cut filler and a catalyst capable of converting carbon monoxide in mainstream smoke to carbon dioxide and/or nitric oxide in mainstream smoke to nitrogen, wherein the catalyst comprises nanoscale metal particles and/or nanoscale metal oxide particles supported on a fibrous support. A further embodiment provides a method of making a cigarette, comprising (i) adding a catalyst to tobacco cut filler, cigarette paper wrapper and/or a cigarette filter, wherein the catalyst comprises nanoscale metal particles and/or nanoscale metal oxide particles supported on a fibrous support; (ii) providing the cut filler to a cigarette making machine to form a tobacco rod; (iii) placing a paper wrapper around the tobacco column to form a tobacco rod; and (iv) optionally attaching a cigarette filter to the tobacco column to form a cigarette. Cigarettes

catalyst can be added to a cigarette in an amount effective to convert at least 10% of the carbon monoxide in the mainstream smoke to carbon dioxide and/or at least 10% of the nitric oxide in the mainstream smoke to nitrogen. Preferably, less than a monolayer of the nanoscale particles are deposited within and/or on the fibrous support. For example, the catalyst can comprise from 0.1 to 50 wt.% nanoscale particles supported on a fibrous support, the catalyst being present in the cut filler, cigarette paper and/or filter of the cigarette.
0014 According to a preferred method, the catalyst is formed by (i) combining
nanoscale metal particles and/or nanoscale metal oxide particles and a liquid to form
a dispersion; (ii) combining the dispersion with a fibrous support; and (iii) heating
the fibrous support to a remove the liquid and deposit nanoscale particles within
and/or on the fibrous support.
0015 According to another preferred method, the catalyst is formed by (i)
combining a metal precursor and a solvent to form a metal precursor solution; (ii)
contacting the fibrous support with the metal precursor solution; (iii) drying the
fibrous support; and (iv) heating the fibrous support to a temperature sufficient to
thermally decompose the metal precursor to form nanoscale particles within and/or
on the fibrous support. For example, a dispersion of nanoscale particles or a metal
precursor solution can be sprayed onto a fibrous support, preferably a heated fibrous
support. Optionally, a dispersion of nanoscale particles can be added to the metal
precursor solution.
0016 The metal precursor can be one or more of metal fi-diketonates, metal
dionates, metal oxalates and metal hydroxides, and the metal in the metal precursor
can comprise at least one element selected from Groups EB-VIIB, VKI, IIIA and FVA
of the Periodic Table of Elements, and mixtures thereof. Liquids used to form a
dispersion of nanoscale particles, and solvents used to form a metal precursor
solution can include distilled water, pentanes, hexanes, aromatic hydrocarbons,
cyclohexanes, xylenes, ethyl acetates, toluene, benzenes, tetrahydrofuran, acetone,
carbon disulfide, dichlorobenzenes, nitrobenzenes, pyridine, methyl alcohol, ethyl
alcohol, butyl alcohol, aldehydes, ketones, chloroform,, mineral spirits, and mixtures
thereof. The metal precursor can be decomposed to nanoscale metal and/or metal
oxide particles by heating to a temperature of from about 200 to 400EC.
0017 Yet another embodiment provides a method of smoking the cigarette
described above, which involves lighting the cigarette to form smoke and drawing
the smoke through the cigarette, wherein during the smoking of the cigarette, the
catalyst acts as a catalyst for the conversion of carbon monoxide to carbon dioxide
and/or nitric oxide to nitrogen.
Brief Description of the Drawings
0018 Figure 1 shows SEM images of a catalyst prepared according to an
embodiment of wherein nanoscale iron oxide particles are deposited on a fibrous
quartz wool support.
0019 Figure 2 depicts a comparison between the catalytic activity of Fe^Os
nanoscale particles (NANOCATD Superfine Iron Oxide (SFIO) from MACH I, Inc.,
King of Prussia, PA) having an average particle size of about 3 nm, versus Fe2C>3
powder (from Aldrich Chemical Company) having an average particle size of about
5 urn.
0020 Figure 3 depicts the temperature dependence for the conversion rates of
CuO and Fe^C^ nanoscale particles as catalysts for the oxidation of carbon monoxide
with oxygen to produce carbon dioxide.
Detailed Description of Preferred Embodiments
0021 Tobacco cut filler compositions, cigarettes, methods for making cigarettes
and methods for smoking cigarettes that involve the use of catalysts having
nanoscale metal particles and/or nanoscale metal oxide particles on a fibrous support
capable of acting as a catalyst for the conversion of carbon monoxide (CO) to carbon
dioxide (CO2) and/or nitric oxide (NOX) to nitrogen (N2) are provided.
0022 A catalyst is capable of affecting the rate of a chemical reaction, e.g.,
increasing the rate of oxidation of carbon monoxide to carbon dioxide and/or
increasing the rate of reduction of nitric oxide to nitrogen without participating as a
reactant or product of the reaction. An oxidant is capable of oxidizing a reactant.,
e.g., by donating oxygen to the reactant, such that the oxidant itself is reduced.
0023 "Smoking" of a cigarette means the heating or combustion of the cigarette
to form smoke, which can be drawn through the cigarette. Generally, smoking of a
cigarette involves lighting one end of the cigarette and, while the tobacco contained
therein undergoes a combustion reaction, drawing the cigarette smoke through the
mouth end of the cigarette. The cigarette may also be smoked by other means. For
example, the cigarette may be smoked by heating the cigarette and/or heating using
electrical heater means, as described in commonly-assigned U.S. Patent Nos.
6,053,176; 5,934,289; 5,591,368 and 5,322,075.
0024 The term "mainstream" smoke refers to the mixture of gases passing down
the tobacco rod and issuing through the filter end, i.e., the amount of smoke issuing
or drawn from the mouth end of a cigarette during smoking of the cigarette.
0025 In addition to the constituents in the tobacco, the temperature and the
oxygen concentration within the cigarette during smoking are factors affecting the
formation and reaction of carbon monoxide, nitric oxide and carbon dioxide. For
example, the total amount of carbon monoxide formed during smoking comes from
a combination of three main sources: thermal decomposition (about 30%),
combustion (about 36%) and reduction of carbon dioxide with carbonized tobacco
(at least 23%). Formation of carbon monoxide from thermal decomposition, which
is largely controlled by chemical kinetics, starts at a temperature of about 180EC and
finishes at about 1050EC. Formation of carbon monoxide and carbon dioxide
during combustion is controlled largely by the diffusion of oxygen to the surface (ka)
and via a surface reaction (kb). At 250EC, ka and kb, are about the same. At 400EC, the reaction becomes diffusion controlled. Finally, the reduction of carbon dioxide with carbonized tobacco or charcoal occurs at temperatures around 390EC and above.
0026 During smoking there are three distinct regions in a cigarette: the
combustion zone, the pyrolysis/distillation zone, and the condensation/filtration
zone. While not wishing to be bound by theory, it is believed that the catalyst of the
invention can target the various reactions that occur in different regions of the
cigarette during smoking.
0027 First, the combustion zone is the burning zone of the cigarette produced
during smoking of the cigarette, usually at the lighted end of the cigarette. The
temperature in the combustion zone ranges from about 700EC to about 950EC, and
the heating rate can be as high as SOOEC/second. Because oxygen is being
consumed in the combustion of tobacco to produce carbon monoxide, carbon
dioxide, nitric oxide, water vapor, and various organic compounds, the concentration
of oxygen is low in the combustion zone. The low oxygen concentration coupled
with the high temperature leads to the reduction of carbon dioxide to carbon
monoxide by the carbonized tobacco. In this region, the catalyst can convert carbon
monoxide to carbon dioxide via both catalysis and oxidation mechanisms, and the
catalyst can convert nitric oxide to nitrogen via both catalysis and reduction
mechanisms. The combustion zone is highly exothermic and the heat generated is carried to the pyrolysis/distillation zone.
0028 The pyrolysis zone is the region behind the combustion zone, where the
temperatures range from about 200EC to about 600EC. The pyrolysis zone is where
most of the carbon monoxide and nitric oxide is produced. The major reaction is the
pyrolysis (i.e. the thermal degradation) of the tobacco that produces carbon
monoxide, carbon dioxide, nitric oxide, smoke components, and charcoal using the
heat generated in the combustion zone. There is some oxygen present in this region,
and thus the catalyst may act as a catalyst for the oxidation of carbon monoxide to
carbon dioxide and/or reduction of nitric oxide to nitrogen. The catalytic reaction
begins at 150EC and reaches maximum activity around 300EC.
0029 In the condensation/filtration zone the temperature ranges from ambient to
about 150EC. The major process in this zone is the condensation/filtration of the
smoke components. Some amount of carbon monoxide, carbon dioxide and nitric
oxide diffuse out of the cigarette and some oxygen diffuses into the cigarette. The
partial pressure of oxygen in the condensation/filtration zone does not generally
recover to the atmospheric level.
0030 The catalyst comprises metal and/or metal oxide nanoscale particles
supported on a fibrous support. The nanoscale particles can comprise metallic
elements selected from the group consisting of Group IB-VIIB, VIII, IIIA and IVA
elements of the Periodic Table of Elements, and mixtures thereof, e.g., B, C, Mg, Al,
Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt and Au. The fibrous support can comprise oxide-bonded silicon carbide, boria, alumina, silica, aluminosilicates, titania, yttria, ceria, glasses, zirconia optionally stabilized with calcia or magnesia, and mixtures thereof. While direct placement of the catalyst in the tobacco cut filler is preferred, the catalyst may be placed in the cigarette filter, or incorporated in the cigarette paper. The catalyst can also be placed both in the tobacco cut filler and in other locations.
0031 Nanoscale particles are a novel class of materials whose distinguishing
feature is that their average diameter, particle or other structural domain size is
below about 100 nanometers. The nanoscale particles can have an average particle
size less than about 100 nm, preferably less than about 50 nm, most preferably less
than about 10 nm. Nanoscale particles have very high surface area to volume ratios,
which makes them attractive for catalytic applications.
0032 By dispersing nanoscale particles on a fibrous support the particles are
easier to handle and easier to combine with tobacco cut filler than unsupported
nanoscale particles. Through the method nanoscale particles can be combined with
tobacco cut filler before and/or during incorporation of the tobacco cut filler into a
cigarette. The fibrous support can act as a separator, which inhibits agglomeration
or sintering together of the particles during combustion of the cut filler. Particle
sintering may disadvantageous^ elongate the combustion zone, which can result in
excess CO and NOX production. The fibrous support minimizes particle sintering,
and thus minimizes elongation of ths combustion zone and a loss of active surface area.
0033 In order to maximize the amount of surface area of the nanoscale particles
available for catalysis, preferably less than a monolayer of the nanoscale particles is
deposited within and/or on the fibrous support. For example, the catalyst can
comprise from about 0.1 to 50 wt.% nanoscale particles supported on a fibrous
support. By adjusting the loading of the nanoscale particles on the fibrous support,
the activities of the catalyst/oxidant can be regulated. By depositing less than a
monolayer of nanoscale particles, neighboring nanoscale particles will be less likely
to sinter together.
0034 The synergistic combination of catalytically active nanoscale particles with
a catalytically active fibrous support can produce a more efficient catalyst. Thus,
nanoscale particles disposed on a fibrous support advantageously allow for the use
of small quantities of catalyst to catalyze, for example, the oxidation of CO to CC>2
and/or reduction of NOX to N2.
0035 According to a preferred method, nanoscale metal particles and/or
nanoscale metal oxide particles such as nanoscale copper oxide and/or nanoscale
iron oxide particles can be dispersed in a liquid and intimately contacted with a
fibrous support, which is dried to produce an intimate dispersion of nanoscale
particles within or on the fibrous support.
0036 According to another preferred method, nanoscale particles can be formed in situ upon heating a fibrous support that has been contacted with a metal precursor compound. For example, a metal precursor such as copper pentane dionate can be dissolved in a solvent such as alcohol and contacted with a fibrous support. The impregnated support can be heated to a relatively low temperature, for example 200-400EC, wherein thermal decomposition of the metal precursor results in the formation and deposition of nanoscale metal or metal oxide particles within or on the fibrous support.
0037 An example of nanoscale metal oxide particles is iron oxide particles.
For instance, MACH I, Inc., King of Prussia, PA sells Fe2O3 nanoscale particles
under the trade names NANOCATO Superfine Iron Oxide (SFIO) and NANOCATD
Magnetic Iron Oxide. The NANOCATD Superfine Iron Oxide (SFIO) is amorphous
ferric oxide in the form of a free flowing powder, with a particle size of about 3 nm,
a specific surface area of about 250 ni2/g, and a bulk density of about 0.05 g/ml. The
NANOCATD Superfine Iron Oxide (SFIO) is synthesized by a vapor-phase process,
which renders it free of impurities that may be present in conventional catalysts, and
is suitable for use in food, drugs, and cosmetics. The NANOCATtl Magnetic Iron
Oxide is a free flowing powder with a particle size of about 25 nm and a specific
surface area of about 40 m2/g.
0038 The fibrous support can comprise a mixture of refractory carbides and
oxides, including amorphous and crystalline forms of such fibrous materials.
xemplary classes of ceramic materials that can be used as a fibrous support include fused quartz and fused silica. Fused quartz and fused silica are ultra pure, single component glasses. Both fused quartz and fused silica are inert to most substances. Fused quartz is manufactured using; powdered quartz crystal as a feedstock and is normally transparent, while fused silica products are generally produced from high purity silica sand. In both cases, the fusion process is carried out at high temperature (over 2000EC) using any suitable heating technique such as an electrically powered furnace or flame fusion process.
0039 The specific surface area of the fibers used as the fibrous support is
preferably low, typically less than about 200 rn2/g, but greater than about 0.001 m2/g,
preferably between about 0.1 to 200 m?'/g. The length of the fibers is preferably
greater than about 1 cm, e.g., greater than about 2.5 cm, but typically less than about
25 cm. Preferably, the fibers are not woven like cloth, but instead are randomly
intertwined as in a non-woven mat or rug. Preferably, the fibers are catalytically
active fibers.
0040 Molecular organic decomposition (MOD) can be used to prepare
nanoscale particles. The MOD process starts with a metal precursor containing the
desired metallic element dissolved in a suitable solvent. For example, the process
can involve a single metal precursor bearing one or more metallic atoms or the
process can involve multiple single metallic precursors that are combined in solutior
to form a solution mixture. As described above, MOD can be used to prepare
nanoscale metal particles and/or nanoscale metal oxide particles prior to adding the particles to the fibrous support, or in situ, by contacting a fibrous support with a metal precursor solution and thermally decomposing the metal precursor to give nanoscale particles.
0041 The decomposition temperature of the metal precursor is the
temperature at which the ligands substantially dissociate (or volatilize) from the
metal atoms. During this process the bonds between the ligands and the metal atoms
are broken such that the ligands are vaporized or otherwise separated from the metal.
Preferably all of the ligand(s) decompose. However, nanoscale particles may also contain carbon obtained from partial decomposition of the organic or inorganic components present in the metal precursor and/or solvent.
0042 The melal precursors used in MOD processing preferably are high
purity, non-toxic, and easy to handle and store (with long shelf lives). Desirable
physical properties include solubility in solvent systems, compatibility with other
precursors for multi-component synthesis, and volatility for low temperature
processing.
0043 Multicomponent nanoscale particles can be obtained from mixtures
of single metal (homo-metallic) precursors or from a single-source mixed metal
(hetero- metallic) precursor molecule in which one or more metallic elements are
chemically associated. The desired stoichiometry of the resultant particles can
match the stoichiometry of the metal precursor solution.
0044 In preparing multicomponent nanoscale particles, the use of different
single-metal precursors has the advantage of flexibility in designing precursor
rheology as well as product stoichiometry. Hetero-metallic precursors, on the other
hand, may offer access to metal systems whose single metal precursors have
undesirable solubility, volatility or compatibility.
0045 Mixed-metal species can be obtained via Lewis acid-base reactions or
substitution reactions by mixing metal alkoxides and/or other metal precursors such
as acetates, (3-diketonates or nitrates. Because the combination reactions are
controlled by thermodynamics, however, the stoichiometry of the hetero-compound
once isolated may not reflect the composition ratios in the mixture from which it
was prepared. On the other hand, most metal alkoxides can be combined to produce
hetero-metallic species that are often more soluble than the starting materials.
0046 An aspect of the method described herein for making a catalyst is that
a commercially desirable stoichiometry in the nanoscale particles can be obtained.
For example, the desired atomic ratio hi the nanoscale particles can be achieved by
selecting a metal precursor or mixture of metal precursors having a ratio of first
metal atoms to second metal atoms that is equal to the desired atomic ratio.
0047 The metal precursor compounds are preferably metal organic
compounds, which have a central main group, transition, lanthanide, or actinide
metal or metalloid atom or atoms bonded to a bridging atom (e.g., N, O, P or S) that
is in turn bonded to an organic radical. Examples of the central metal or metalloid
atom include, but are not limited to, B, C, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt and Au. Such metal compounds may include alkoxides, (3-diketonates, carboxylates, oxalates, citrates, hydrides, thiolates, amides, nitrates, carbonates, cyanates, sulfates, bromides, chlorides, and hydrates thereof. The metal precursor can also be a so-called organometallic compound, wherein a central metal atom is bonded to one or more carbon atoms of an organic group. Aspects of processing with these metal precursors are discussed below.
0048 Precursors for the synthesis of nanoscale oxides are molecules having pre-existing metal-oxygen bonds such as metal alkoxides M(OR)n or oxoalkoxides MO(OR)n 0 = saturated or unsaturated organic group, alkyl or aryl), p-diketonates M(p-diketonate)n (p-diketonate = RCOCHCOR1) and metal carboxylates M(O2CR)n. Metal alkoxides have both good solubility and volatility and are readily applicable to MOD processing. Generally, however, these compounds are highly hygroscopic and require storage under inert atmosphere. In contrast to silicon alkoxides, which are liquids and monomeric, the alkoxides based on most metals are solids. On the other hand, the high reactivity of the metal-alkoxide bond can make these metal precursor materials useful as starting compounds for a variety of heteroleptic species (/. e., species with different types of ligands) such as M(OR)n-xZx (Z = p-diketonate or 02CR).
0049 Metal alkoxides M(OR),, react easily with the protons of a large variety of
molecules. This allows easy chemical modification and thus control of
stoichiometry by using, for example, organic hydroxy compounds such as alcohols,
silanols (RaSiOH), glycols OH(CH2),,OH, carboxylic and hydroxycarboxylic acids,
hydroxyl surfactants, etc.
0050 Fluorinated alkoxides M(ORF)n (RF = CH(CF3)2, C6F5,...) are readily
soluble in organic solvents and less susceptible to hydrolysis than non-fluorinated
alkoxides. These materials can be used as precursors for fluorides, oxides or
fluoride-doped oxides such as F-doped tin oxide, which can be used as nanoscale
metal oxide particles.
0051 Modification of metal alkoxides reduces the number of M-OR bonds
available for hydrolysis and thus hydrolytic susceptibility. Thus, it is possible to
control the solution chemistry in situ by using, for example, metal P-diketonates
(e.g. acerylacetone) or carboxylic acids (e.g. acetic acid) as modifiers for, or in lieu
of, the alkoxide.
0052 Metal p-diketonates [M(RCOCHCOR')n]m are attractive precursors for
MOD processing because of their volatility and high solubility. Their volatility is
governed largely by the bulk of the R and R1 groups as well as the nature of the
metal, which will determine the degree of association, m, represented in the formula
above. Acetylacetonates (R=R-CH3) are advantageous because they can provide
good yields.
0053 Metal [i-diketonatcs are prone to a chelating behavior that can lead to a
decrease in the nuclearity of these precursors. These ligands can act as surface
capping reagents and polymerization inhibitors. Thus, small particles can be
obtained after hydrolysis of M(OR)n.x(p-diketonate)x. Acetylacetone can, for
instance, stabilize nanoscale colloids. Thus, metal p-diketonate precursors are
preferred for preparing nanoscale particles.
0054 Metal carboxylates such as acetates (M(O2CMe)n) are commercially
available as hydrates, which can be rendered anhydrous by heating with acetic
anhydride or with 2-methoxyethanol. Many metal carboxylates generally have poor
solubility in organic solvents and, because carboxylate ligands act mostly as
bridging-chelating ligands, readily form oligomers or polymers. However,
2-ethylhexanoates (M(O2CCHEtnBu)n), which are the carboxylates with the smallest
number of carbon atoms, are generally soluble in most organic solvents. A large
number of carboxylate derivatives are available for aluminum. Nanoscale
aluminum-oxygen macromolecules and clusters (alumoxanes) can be used as
nanoscale particles. For example, formate Al(O2CH)3(HaO) and
carboxylate-alumoxanes [AlOx(OH)y(O2CR)z]m can be prepared from the
inexpensive minerals gibsite or boelimite.
0055 The solvent(s) used in MOD processing are selected based on a number of criteria including1 high solubility for the metal precursor compounds; chemical inertness to the metal precursor compounds; rheological compatibility with
the deposition technique being used (e.g., the desired viscosity, wettability and/or compatibility with other rheology adjusters); boiling point; vapor pressure and rate of vaporization; and economic factors (e.g. cost, recoverability, toxicity, etc.).
0056 Solvents mat may be used in MOD processing include distilled water,
pentanes, hexanes, aromatic hydrocarbons, cyclohexanes, xylenes, ethyl acetates,
toluene, benzenes, tetrahydrofuran, acetone, carbon disulfide, dichlorobenzenes,
nitrobenzenes, pyridine, methyl alcohol, ethyl alcohol, butyl alcohol, aldehydes,
ketones, chloroform, mineral spirits, and mixtures thereof.
0057 Nanoscale metal particles may be incorporated into the fibrous
support by methods known in the art, such as ion exchange, impregnation, or
physical admixture. For example, nanoscale particles and/or a metal precursor may
be suspended or dissolved in a liquid, and the fibrous support may be contacted,
mixed or sprayed with the liquid having the dispersed particles and/or dissolved
metal precursor. The fibrous support can be dried and/or heat treated during or after
the coating step.
0058 According to a first embodiment, a liquid dispersion of nanoscale
particles can be combined with a fibrous support. Nanoscale particles may be
suspended or dissolved in a liquid, and the fibrous support may be mixed or sprayed
with the liquid having the dispersed particles. The liquid may be substantially
removed from the fibrous support, such as by heating the fibrous support at a
temperature higher than the boiling point of the liquid or by reducing the pressure of
ie atmosphere surrounding the fibrous support so that the particles remain on the upport. The liquid used to form a dispersion of the nanoscale particles can include listilled water, pentanes, hexanes, aromatic hydrocarbons, cyclohexanes, xylenes, ithyl acetates, toluene, benzenes, tetrahydrofuran, acetone, carbon disulfide, lichlorobenzenes, nitrobenzenes, pyridine, methyl alcohol, ethyl alcohol, butyl ilcohol, aldehydes, ketones, chloroform, mineral spirits, and mixtures thereof.
0059 In general, nanoscale particles and a fibrous support can be combined
n any suitable ratio to give a desired loading of metal particles on the support. For
sxample, nanoscale iron oxide particles or copper oxide particles can be combined
with ceramic fibers to produce from about 0.1% to 50% wt.%, e.g. 10 wt.% or 20
>vt.% nanoscale particles of iron oxide or copper oxide on ceramic fibers.
0060 By way of example, a 5 wt.% mixture of NANOCATD iron oxide
particles was dispersed in distilled water using ultrasonication. The dispersion was
sprayed onto a 200 mg quartz wool support that was heated to about 50EC during
the coating step and then dried in air to give a catalyst comprising 100 mg nanoscale
iron oxide on the quartz wool. SEM images of the resulting catalyst are shown in
Figure 1. The catalyst was incorporated into the cut filler of an experimental
cigarette that was smoked under continuous draw conditions at a flow rate of 500
ml/min. A multi-gas analyzer was used to measure CO and NO. The amount of CO
and NO drawn through the experimental cigarette was compared with the amount
drawn through a catalyst-free control cigarette. The data in Table 1 illustrate the improvement obtained by using a nanoscale particles/quartz wool catalyst. Table 1. Reduction of CO and NO using NANOCAT/quartz wool catalyst.

(TALBE REMOVED)
0061 According to a second embodiment, nanoscale particles can be
formed in situ on a fibrous support via the thermal decomposition of a metal
precursor compound. Suitable precursor compounds for the metal, or metal oxide
nanoscale particles are those that thermally decompose at relatively low
temperatures, such as discussed above. The concentration of the metal precursor in
the solvent generally ranges from about 0.001 molar (M) to 10 M, preferably from
about 0.1 to 1 M. The metal precursor solution and fibrous support can be combined
at about ambient temperature, e.g., by spraying or dip coating, or at elevated
temperatures, e.g., through reflux. The temperature of the mixing typically ranges
from about ambient, e.g., 23EC to about 50EC. The mixing is preferably conducted
at ambient pressure.
0062 After contacting the fibers with the solution containing the metal
precursor, the fibrous support material can be dried in air at a temperature ranging
from about 23EC to a temperature below the decomposition temperature of the metal precursor, typically a temperature between about 23EC and 100EC. According to one preferred embodiment, the dried precursor-fibrous support can be heated (e.g., above 1OOEC) to decompose the metal precursor and form a catalyst material comprising nanoscale particles on the fibrous support. According to another embodiment, the dried precursor-fibrous support can be combined with cut filler.
0063 The metal precursor can be decomposed to form nanoscale particles
that are dispersed within or on the fibrous support by thermally treating the metal
precursor to above its decomposition temperature. Thermal treatment causes
decomposition of the metal precursor to dissociate the constituent metal atoms,
whereby the metal atoms may combine to form nanoscale metal or metal oxide
particles. Where the metal precursor comprises more than one metallic element, the
nanoscale particles may have an atomic ratio approximately equal to the
stoichiometric ratio of the metals in the metal precursor solution.
0064 The thermal treatment can be carried out in various atmospheres. For
instance, the fibrous support can be contacted with a metal precursor solution and
the contacted support can be heated in the presence of an oxidizing atmosphere and
then heated in the substantial absence of an oxidizing atmosphere to form nanoscale
metal oxide particles. The oxidizing atmosphere can comprise air or oxygen.
Alternatively, the fibrous support can be contacted with a metal precursor solution
and the contacted support can be heated in an inert or reducing atmosphere to form nanoscale metal particles. The reducing atmosphere can comprise hydrogen, nitrogen, ammonia, carbon dioxide and mixtures thereof. A preferred reducing atmosphere is a hydrogen-nitrogen mixture (e.g., forming gas).
0065 The metal precursor-contacted support is preferably heated to a
temperature equal to or greater than the decomposition temperature of the metal
precursor. The preferred heating temperature will depend on the particular ligands
used as well as on the degradation temperature of the metal(s) and any other desired
groups which are to remain. However, the preferred temperature is from about
200EC to 400EC, for example 300EC or 350EC. Thermal decomposition of the
uniformly dispersed metal precursor preferably results in the uniform deposition of
nanoscale particles within and/or on the surface of the fibrous support.
0066 By way of example, nanoscale copper oxide particles were formed on
quartz wool by uniformly mixing quartz wool with a 0.5 M solution of copper
pentane dionate in alcohol to the point of incipient wetness. The support was dried
at room temperature overnight and then heated to 400EC in air to form a catalyst
material comprising nanoscale copper oxide particles that were intimately
coated/mixed with the quartz wool.
0067 In general, a metal precursor and a fibrous support can be combined
in any suitable ratio to give a desired loading of metal particles on the support. For
example, iron oxalate or copper pentane dionate can be combined with quartz wool
to produce from about 0.1% to 50% wt.%, e.g., 10 wt.% or 20 wt.% nanoscale particles of iron oxide, iron oxyhydroxide or copper oxide on quartz wool.
0068 The fibrous support may include any thermally stable/fire resistant
material which, when heated to a temperature at which a metal precursor is
converted to a metal on the surface thereof, does not melt, vaporize completely, or
otherwise become incapable of supporting nanoscale particles.
0069 During the conversion of CO to COa, the oxide nanoscale particles
may become reduced. For example, nanoscale FeiOs particles may be reduced to
Fe304, FeO or Fe during the reaction of CO to CO2- The fibrous support
advantageously acts as a spacer between the nanoscale particles and prevents them
from sintering together, which would result in a loss of surface area and catalytic
activity.
0070 Iron oxide is a preferred constituent in the catalyst because it may
have a dual function as a CO catalyst in the presence of oxygen, and as a CO and/or
NO oxidant for the direct oxidation of CO hi the absence of oxygen and/or reduction
of NO. A catalyst that can also be used as an oxidant is especially useful for certain
applications, such as within a burning cigarette where the partial pressure of oxygen
can be very low.
0071 Figure 2 shows a comparison between the catalytic activity of FeiOs
nanoscale particles (50 mg samples) (NANOCATD Superfine Iron Oxide (SFIO)
from MACH I, Inc., King of Prussia, PA) having an average particle size of about 3

nm (curve A), versus Fe2Os powder (from Aldrich Chemical Company) having an average particle size of about Sum (curve B). The gas (3.4% CO, 20.6% O2, balance He) flow rate was 1000 ml/min. and the heating rate was 12 KAnin. The Fe2O3 nanoscale particles show a much higher percentage of conversion of carbon monoxide to carbon dioxide than the larger Fe2Os particles.
0072 As mentioned above, Fe2O3 nanoscale particles are capable of acting
as both an oxidant for the conversion of carbon monoxide to carbon dioxide and as a
catalyst for the conversion of carbon monoxide to carbon dioxide and/or nitric oxide
to nitrogen. For example, the Fe2O3 nanoscale particles can act as a catalyst in the
pyrolysis zone and can act as an oxidant in the combustion zone.
0073 Nanoscale iron oxide particles can act as a catalyst for the conversion
of CO to CO2 according to the equation 2CO + O2 6 2CO2 and for the conversion of
NO to N2 according to the equation CO + 2NO 6 N2 + CO2. Nanoscale iron oxide
particles can act as a oxidant for the conversion of CO to CO2 according to the
equation CO + Fe2O3 6 CO2 + 2FeO.
0074 To illustrate the effectiveness of nanoscale metal oxide, Figure 3
illustrates a comparison between the temperature dependence of conversion rate for
CuO (curve A) and Fe203 (curve B) nanoscale particles using 50 mg CuO particles
and 50 mg Fe2O3 nanoscale particles as a catalyst in a quartz tube reactor. The gas
(3.4% CO, 21% O2, balance He) flow rate was 1000 ml/min. and the heating rate
was 12.4 K/min. Although the CuO nanoscale particles have higher conversion rates
at lower temperatures, at higher temperatures the CuO and FeaOs have comparable
conversion rates.
0076
0075 Table 2 shows a comparison between the ratio of carbon monoxide to carbon dioxide, and the percentage of oxygen depletion when using CuO and FeaCb nanoscale particles(Table Removed)

0078 In the absence of nanoscale particles, the ratio of carbon monoxide to
carbon dioxide is about 0.51 and the oxygen depletion is about 48%. The data in
Table 2 illustrate the improvement obtained by using nanoscale particles. The ratio
of carbon monoxide to carbon dioxide drops to 0.29 and 0.23 for CuO and Fe2Os
nanoscale particles, respectively. The oxygen depletion increases to 67% and 100%
for CuO and FeaOs nanoscale particles, respectively.
79 The catalysts will preferably be distributed throughout the tobacco
rod portion of a cigarette. By providing the catalysts throughout the tobacco rod, it
is possible to reduce the amount of carbon monoxide and/or nitric oxide drawn
through the cigarette, and particularly at both the combustion region and in the pyrolysis zone.
7 The catalysts, which comprise nanoscale particles supported on a
fibrous support, may be provided along the length of a tobacco rod by distributing
the catalysts on the tobacco or incorporating them into the cut filler tobacco. The
catalysts may also be added to the cut filler tobacco stock supplied to the cigarette
making machine or added to a tobacco rod prior to wrapping cigarette paper around
the cigarette rod. According to a preferred embodiment, when nanoscale particles
are formed in situ using MOD processing as described above, heating the fibrous
support comprising a metal precursor solution to a temperature sufficient to
Ihermally decompose the metal precursor into nanoscale particles can be performed
prior to adding the impregnated support to the cigarette.
79 The amount of the catalyst can be selected such mat the amount of
carbon monoxide and/or nitric oxide in mainstream smoke is reduced during
smoking of a cigarette. Preferably, the amount of the catalyst will be a catalytically
effective amount, e.g., from about a few milligrams, for example, 5 mg/cigarette, to
about 200 mg/cigarette or more.
80 One embodiment provides a cut filler composition comprising
tobacco and at least one catalyst, as described above, which is capable of converting
carbon monoxide to carbon dioxide and/or nitric oxide to nitrogen, where the
catalyst is in the form of a nanoscale metal particles and/or nanoscale metal oxide particles supported on a fibrous support.
81 Any suitable tobacco mixture may be used for the cut filler.
Examples of suitable types of tobacco materials include flue-cured, Burley,
Maryland or Oriental tobaccos, the rare or specialty tobaccos, and blends thereof.
The tobacco material can be provided in the form of tobacco lamina, processed
tobacco materials such as volume expanded or puffed tobacco, processed tobacco
stems such as cut-rolled or cut-puffed stems, reconstituted tobacco materials, or
blends thereof. The tobacco can also include tobacco substitutes.
82 In cigarette manufacture, the tobacco is normally employed in the
form of cut filler, i.e. in the form of shreds or strands cut into widths ranging from
about 1/10 inch to about 1/20 inch or even 1/40 inch. The lengths of the strands
range from between about 0.25 inches to about 3.0 inches. The cigarettes may
further comprise one or more flavorants or other additives (e.g. burn additives,
combustion modifying agents, coloring agents, binders, etc.) known in the art.
83 Another embodiment provides a cigarette comprising a tobacco rod,
wherein the tobacco rod comprises tobacco cut filler having at least one catalyst, as
described above, which is capable of converting carbon monoxide to carbon dioxide
and/or nitric oxide to nitrogen. In addition to being located in the tobacco cut filler,
the catalyst can be located in the cigarette paper and/or filter of the cigarette.
84 A further embodiment provides a method of making a cigarette,
comprising (i) adding a catalyst to a tobacco cut filler, cigarette paper and/or a
cigarette filter; (ii) providing the cut filler to a cigarette making machine to form a
tobacco column; (iii) placing a paper wrapper around the tobacco column to form a
tobacco rod; and (iv) optionally attaching a cigarette filter to the tobacco rod to form
a cigarette.
0085 Techniques for cigarette manufacture are known in the art. Any
conventional or modified cigarette making technique may be used to incorporate the
catalysts. The resulting cigarettes can be manufactured to any known specifications
using standard or modified cigarette making techniques and equipment. Typically,
the cut filler composition is optionally combined with other cigarette additives, and
provided to a cigarette making machine to produce a tobacco rod, which is then
wrapped in cigarette paper, and optionally tipped with filters.
0086 Cigarettes may range from about 50 mm to about 120 mm in length.
Generally, a regular cigarette is about 70 mm long, a "King Size" is about 85 mm
long, a "Super King Size" is about 100 mm long, and a "Long" is usually about 120
mm in length. The circumference is from about 15 mm to about 30 mm in
circumference, and preferably around 25 mm. The tobacco packing density is
typically between the range of about 100 mg/cm3 to about 300 mg/cm3, and
preferably 150 mg/cm3 to about 275 mg/cm3.
0087 Yet another embodiment provides a method of smoking the cigarette
described above, which involves lighting the cigarette to form smoke and drawing
the smoke through the cigarette, wherein during the smoking of the cigarette, the
catalyst acts as a catalyst tor the conversion ot' carbon monoxuk" to c;uKn\ dioxuk
and/or nitric oxide to nitrogen.
0088 While the invention has been described with reference to preferred
embodiments, it is to be understood that variations and modifications may be
resorted to as will be apparent to those skilled in the art. Such variations and
modifications are to be considered within the purview and scope of the invention as
defined by the claims appended hereto.








We Claim:
1. A cigarette comprising cut filler and a catalyst for the conversion of carbon monoxide to carbon dioxide and/or nitric oxide to nitrogen, characterized in that the catalyst comprises nanoscale metal particles and/or nanoscale metal oxide particles comprising one or more metallic elements selected from the group consisting of B, C, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt and Au supported on a fibrous support and said catalyst being present in an amount of 5 mg to 200 mg per cigarette.
2. The cigarette as claimed in claim 1, wherein the nanoscale metal oxide particles comprise oxides selected from the group consisting of iron oxide, iron oxyhydroxide and copper oxide, and mixtures thereof.
3. The cigarette as claimed in claim 1 or 2, wherein the nanoscale metal particles and/or nanoscale metal oxide partibles are carbon-free.
4. The cigarette as claimed in any of claims 1 to 3, wherein the specific surface area of the nanoscale metal particles and/or nanoscale metal oxide particles is from 20 to 2500 m2/g.
5. The cigarette as claimed in any preceding claim, wherein the nanoscale metal particles and/or nanoscale metal oxide particles have an average particle size less than about 50 nm.
6. The cigarette as claimed in any preceding claim, wherein the nanoscale metal particles and/or nanoscale metal oxide particles have an average particle size less than about 10 nm.
7. The cigarette as claimed in any preceding claim, wherein the fibrous support comprises oxides selected from the group consisting of oxide-bonded silicon

carbide, boria, alumina, silica, aluminosilicates, titania, yttria, ceria, glasses, zirconia optionally stabilized with calcia or magnesia, and mixtures thereof.
8. The cigarette as claimed in any preceding claim, wherein the fibrous support comprises ceramic fibers and/or glass fibers.
9. The cigarette as claimed in any preceding claim, wherein the specific surface area of the fibrous support is from 0.1 to 200 m /g.
10. The cigarette as claimed in any preceding claim, wherein the fibrous support comprises millimeter, micron, submicron and/or nanoscale fibers.
11. The cigarette as claimed in any preceding claim, wherein the fibrous support comprises catalytically active fibers.
12. The cigarette as claimed in any preceding claim, wherein the nanoscale metal oxide particles comprise iron oxide, the catalyst being present in the cigarette in an amount effective to convert at least 10% of the carbon monoxide in the mainstream smoke to carbon dioxide and/or at least 10% of the nitric oxide in the mainstream smoke to nitrogen.
13. The cigarette as claimed in any preceding claim, wherein less than a monolayer of the nanoscale particles are deposited within and/or on the fibrous support.
14. The cigarette as claimed in any preceding claim, wherein the catalyst comprises from 0.1 to 50 wt. % nanoscale particles supported on a fibrous support, the catalyst being present in the cut filler, cigarette paper and/or filter of the cigarette.
15. The cigarette as claimed in any preceding claim wherein the cut filler comprises tobacco and the catalyst.

16. A method of making a cigarette as claimed in any of claims 1 to 15, comprising:
(i) adding a catalyst to tobacco cut filler, cigarette paper wrapper and/or a cigarette filter, characterized in that the catalyst comprises nanoscale metal particles and/or nanoscale metal oxide particles supported on a fibrous support;
(ii) providing the cut filler to a cigarette making machine to form a tobacco column;
(iii) placing a paper wrapper around the tobacco column to form a tobacco rod; and
(iv) optionally attaching a cigarette filter to the tobacco rod to form a cigarette.

Documents:

251-DELNP-2006-Abstract-(01-02-2010).pdf

251-delnp-2006-abstract.pdf

251-DELNP-2006-Claims-(01-02-2010).pdf

251-DELNP-2006-Claims-(25-03-2010).pdf

251-delnp-2006-claims.pdf

251-DELNP-2006-Correspondence-Others (01-02-2010).pdf

251-DELNP-2006-Correspondence-Others (16-02-2010).pdf

251-DELNP-2006-Correspondence-Others-(16-11-2010).pdf

251-DELNP-2006-Correspondence-Others-(25-03-2010).pdf

251-DELNP-2006-Correspondence-Others-(26-03-2010).pdf

251-DELNP-2006-Correspondence-Others-(28-05-2010).pdf

251-DELNP-2006-Correspondence-Others.pdf

251-DELNP-2006-Description (Complete)-(01-02-2010).pdf

251-delnp-2006-description(complete).pdf

251-delnp-2006-drawings.pdf

251-DELNP-2006-Form-1-(01-02-2010).pdf

251-delnp-2006-form-1.pdf

251-DELNP-2006-Form-18.pdf

251-DELNP-2006-Form-2-(01-02-2010).pdf

251-delnp-2006-form-2.pdf

251-delnp-2006-form-3.pdf

251-delnp-2006-form-5.pdf

251-DELNP-2006-GPA-(25-03-2010).pdf

251-delnp-2006-gpa.pdf

251-delnp-2006-pct-101.pdf

251-delnp-2006-pct-210.pdf

251-delnp-2006-pct-220.pdf

251-delnp-2006-pct-237.pdf

251-delnp-2006-pct-304.pdf

abstract.jpg


Patent Number 249695
Indian Patent Application Number 251/DELNP/2006
PG Journal Number 45/2011
Publication Date 11-Nov-2011
Grant Date 03-Nov-2011
Date of Filing 13-Jan-2006
Name of Patentee PHILIP MORRIS PRODUCTS S.A.
Applicant Address QUAI JEANRENAUD 3, CH-2000 NEUCHATEL, SWITZERLAND.
Inventors:
# Inventor's Name Inventor's Address
1 LI, PING 9109 CLOISTERS EAST, RICHMOND, VA 23234 US.
2 RASOULI, FIROOZ 1807 GILDENBROUGH COURT, MIDLOTHIAN, VA 23113 US
3 HAJALIGOL, MOHAMMAD 5828 SPINNAKER COVE ROAD, MIDLOTHIAN, VA 23112 US
PCT International Classification Number A24B 15/18
PCT International Application Number PCTIB2004/002176
PCT International Filing date 2004-06-10
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/460,303 2003-06-13 U.S.A.