Ultra-fine particle catalysts for carbonaceous fuel elements

Abstract

The present invention provides fuel elements comprising a carbonaceous material and a catalyst composition comprising ultrafine particles of a metal oxide and/or metal. The present invention additionally provides smoking articles demonstrating reduced amounts of carbon monoxide in the smoke-like aerosol produced by the smoking article. In a further aspect, the present invention provides methods and apparatus for the simultaneous resolution and quantification of a carbon monoxide content and a carbon dioxide content of a gaseous mixture.

Description

Field of the Invention

The present invention relates generally to fuel elements for smoking articles, and more particularly to fuel elements comprising a carbonaceous material and ultrafine particles. In an embodiment, the fuel elements may be utilized in smoking articles to reduce the amount of carbon monoxide in the mainstream smoke and improve the thermal efficiency of the fuel.

BACKGROUND OF THE INVENTION

Cigarettes are popular smoking articles that use tobacco in various forms. Descriptions of cigarettes and the various components thereof are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) (1999).

Cigarettes generally include a substantially cylindrical rod-shaped structure and include a charge, roll or column of smokeable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air.

Carbonaceous materials can be employed as components of combustible material components in a smoking article that are designed to burn and provide heat to aerosolize physically separate aerosol-forming materials. Cigarettes having carbonaceous combustible material components have been marketed by the R. J. Reynolds Tobacco Company under the tradenames Premier and Eclipse. See, for example, U.S. Pat. No. 4,708,151 to Shelar et al.; U.S. Pat. No. 5,016,654 to Bernasek et al.; U.S. Pat. No. 4,991,596 to Lawrence et al.; U.S. Pat. No. 5,038,802 to White et al.; U.S. Pat. No. 4,793,365 to Sensabaugh et al.; U.S. Pat. No. 4,961,438 to Korte; U.S. Pat. No. 4,991,606 to Serrano et al.; U.S. Pat. No. 5,020,548 to Farrier et al.; U.S. Pat. No. 5,076,297 to Farrier et al.; U.S. Pat. No. 5,148,821 to Best et al.; U.S. Pat. No. 5,178,167 to Riggs et al.; U.S. Pat. No. 5,183,062 to Clearman et al.; U.S. Pat. No. 5,345,955 to Clearman et al.; U.S. Pat. No. 5,551,451 to Riggs et al.; and U.S. Pat. No. 5,595,577 to Bensalem et al. The disclosure of each of these patents is incorporated herein by reference. See, also, Chemical and Biological Studies on New Cigarette Prototypes that Heat Instead of Burn Tobacco, R. J. Reynolds Tobacco Company Monograph (1988).

It also has been suggested to incorporate non-combustible materials into the carbonaceous combustible material components of certain types of smoking articles. See, for example, U.S. Pat. No. 5,040,551 to Schlatter et al.; U.S. Pat. No. 5,211,684 to Shannon et al.; U.S. Pat. No. 5,240,014 to Deevi et al.; and U.S. Pat. No. 5,258,340 to Augustine et al. The disclosure of each of these patents is incorporated herein by reference.

It would be desirable to provide a fuel element for a smoking article that reduces the amount of carbon monoxide present in the aerosol of the smoking article. It would additionally be desirable to provide a fuel element that displays a more efficient combustion.

SUMMARY OF THE INVENTION

The present invention provides fuel elements comprising ultrafine particles. In an embodiment of the present invention, the ultrafine particles catalyze the conversion of carbon monoxide to carbon dioxide, thereby reducing the amount of carbon monoxide present in the combustion gases produced by burning of the fuel element. In a smoking article embodiment, a fuel element comprising ultrafine particles reduces the amount of carbon monoxide present in the aerosol and demonstrates a more efficient combustion by producing more energy per gram of fuel combusted.

The present invention also provides methods for altering the performance characteristics of smoking articles to reduce the amount of carbon monoxide present in aerosol produced by the smoking article.

In one aspect, the present invention provides a fuel element comprising a carbonaceous material and at least one catalyst composition, the catalyst composition comprising ultrafine particles.

In another aspect, the present invention provides a method for reducing the amount of carbon monoxide produced by an article comprising a fuel element, the method comprising incorporating ultrafine particles in the fuel element.

In a further aspect, the present invention provides a smoking article having reduced amounts of carbon monoxide in the aerosol produced by the smoking article. In an embodiment, the smoking article comprises: a fuel element comprising a carbonaceous material and ultrafine particles.

In a still further aspect, the present invention provides methods and apparatus for the simultaneous relative quantification of carbon monoxide and carbon dioxide in a gaseous mixture. In an embodiment, the method comprises injecting a gaseous mixture into a split single injector of a gas chromatograph for splitting the gaseous mixture onto two chromatographic columns; resolving the carbon monoxide content of the gaseous mixture on a first chromatographic column; simultaneously resolving the carbon dioxide content of the gaseous mixture on a second chromatographic column; and detecting and quantifying the resolved carbon monoxide and carbon dioxide contents with a mass spectrometer. Embodiments of the method may be utilized to simultaneously quantify the relative amounts of carbon monoxide and carbon dioxide in aerosol from a smoking article.

An advantage of the present invention is that that fuel elements of the present invention may be used in applications where it is desirable to reduce amounts of carbon monoxide.

Further features and advantages of the present invention are set forth in the following more detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a smoking article according to an embodiment of the present invention.

FIG. 2 illustrates a method according to an embodiment of the present invention.

FIG. 3 illustrates an apparatus according to an embodiment of the present invention.

FIG. 4 illustrates an ion chromatogram of a standard gaseous mixture resolved on dual columns according to an embodiment of the present invention.

FIG. 5 illustrates an ion chromatogram of a standard gaseous mixture resolved on a Molsieve column according to an embodiment of the present invention.

FIG. 6 illustrates an ion chromatogram of a standard gaseous mixture resolved on a Carbon Plot column according to an embodiment of the present invention.

FIG. 7 illustrates an ion chromatogram of heated tobaccos resolved on dual columns according to an embodiment of the present invention.

FIG. 8 illustrates an ion chromatogram of cigarette smoke resolved on dual columns according to an embodiment of the present invention.

FIG. 9 illustrates the reduced production of carbon monoxide by carbon upon combustion in the presence of various ultrafine particles according to embodiments of the present invention.

FIG. 10 illustrates the reduced production of carbon monoxide by combustion of carbon and mixtures comprising carbon, Guar gum, graphite, and tobacco in the presence of iron oxide ultrafine particles of various sizes according to embodiments of the present invention.

FIG. 11 illustrates the reduced production of carbon monoxide by combustion of carbon in the presence of various metal oxide ultrafine particles according to embodiments of the present invention.

FIG. 12 illustrates the effect of catalyst compositions on a CO/CO₂ ratio when tobacco is pyrolized in the presence of various ultrafine particles according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides fuel elements comprising a carbonaceous material and at least one catalyst composition. The present invention additionally provides articles of manufacture including, but not limited to, smoking articles. The present invention further provides methods for altering the performance characteristics of smoking articles. Moreover, the present invention provides methods and apparatus for the simultaneous quantification of the carbon monoxide content and carbon dioxide content of a gaseous mixture comprising these and various other chemical species.

Reference is made below to specific embodiments of the present invention. Each embodiment is provided by way of explanation of the invention, not as a limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment may be incorporated into another embodiment to yield a further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification are approximations that can vary, depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein, and every number between the end points. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g., 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10, as well as all ranges beginning and ending within the end points, e.g., 2 to 9, 3 to 8, 3.2 to 9.3, 4 to 7, and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 contained within the range. Additionally, any reference referred to as being “incorporated herein” is to be understood as being incorporated in its entirety.

It is further noted that, as used in this specification, the singular forms “a,” “an,” and “the” include plural referents unless expressly and unequivocally limited to one referent.

In one embodiment of the present invention, a fuel element comprises a carbonaceous material and at least one catalyst composition. The catalyst composition comprises ultrafine particles of a metal oxide, metal, or mixtures thereof. As used herein, the term ultrafine particle is generally used to indicate particles with dimensions less than 100 nanometers (one nanometer is one-billionth of a meter). The metal oxide and metal ultrafine particles can demonstrate activity for catalyzing chemical reactions, such as the oxidation of carbon monoxide to carbon dioxide.

Ultrafine particles suitable for use in catalytic compositions of the present invention comprise, but are not limited to, iron oxides (e.g. FeO, Fe₂O₃ and Fe₃O₄), gold, copper, silver, platinum, palladium, rhodium, nickel, zinc, zirconium, other transition metals, metal oxides, and mixtures thereof.

The catalyst compositions comprising ultrafine particles facilitate a more complete production of carbon dioxide by catalyzing the oxidation reaction of carbon to carbon dioxide. In an embodiment wherein combustion of a fuel element generates a gaseous stream comprising carbon monoxide, the catalyst composition acts upon carbon monoxide in the gaseous stream. Ultrafine particles of the catalyst compositions may also improve the performance characteristics of a fuel element for particular applications. For example, the ultrafine particles of the catalyst compositions can increase the caloric output of a particular fuel.

In an embodiment of the present invention, ultrafine particles of the catalyst compositions may have an average particle size of 10 nanometers, generally between 1 nanometer and 1 micron. In an embodiment of a smoking article of the present invention, the ultrafine particles may have an individual particle size of up to about five nanometers. In another embodiment of a smoking article of the present invention, the ultrafine particles may have an individual particle size between about two and four nanometers.

Ultrafine particles according to the present invention may be produced by a variety of methods including sol-gel synthesis, chemical deposition, deposition precipitation, inert gas condensation, mechanical alloying or high-energy ball milling, plasma synthesis, and electrodeposition. Using such methods, ultrafine particles can be produced in various symmetric shapes, such as spheres, cylinders, prisms, cubes, tetrapods and amorphous clusters. In embodiments of the present invention, the physical properties of the ultrafine particles, including for example, their electrical, optical, chemical, mechanical, and magnetic properties, may be selectively controlled for example by engineering the size, morphology, and/or composition of the ultrafine particles. The resulting materials may have enhanced or entirely different properties from their parent materials.

Representative types of ultrafine particles and materials for use in the present invention are of the type, and may be produced by methods, described in U.S. Pat. No. 6,503,475 to McCormick U.S. Pat. No. 6,472,459 to Morales et al., U.S. Pat. No. 6,467,897 to Wu et al., U.S. Pat. No. 6,479,146 to Caruso et al., and U.S. Pat. No. 6,479,156 to Schmidt et al. and U.S. Published Pat. Applications 2002/0194958 to Lee et al., 2002/014453 to Lilly Jr., et al., 2003/0000538 to Bereman et al., 2002/0167118, 2002/0172826 and 2002/0127351, the disclosure of each patent and published application being incorporated herein by reference.

Ultrafine particles for use in the catalyst composition can be obtained commercially. For example, Superfine Iron oxide (Fe₂O₃) can be obtained from MACH-1 Inc. of King of Prussia, Pa. Nanopowder Enterprise Inc. of Piscataway, N.J. is an additional commercial source of ultrafine particles for use in catalyst compositions of the present invention.

In embodiments of the present invention, the fuel element additionally comprises a carbonaceous material. The fuel element may additionally comprise binders like Guar gum, other metallic particles such as aluminum or the like, inert filler material like graphite, and/or burn modifiers such as sodium or potassium carbonate. In some embodiments, the carbonaceous materials for use in the fuel element include at least 50%, by weight carbon. In other embodiments the carbonaceous materials for use in the fuel element can include about 60-95% by weight carbon. In still further embodiments, the carbonaceous materials for use in the fuel element can include about 70-80% by weight carbon. The carbonaceous materials may be in powder form and may be partially activated. The carbonaceous materials may also be heat treated. The carbonaceous materials may comprise organic carbon containing materials, for example tobacco.

The carbonaceous materials of the present invention may be prepared from several starting materials. Suitable starting materials include, but are not limited to, cellulosic materials with a high (i.e., greater than about 80%) alpha-cellulose content, such as cotton, rayon, paper, and the like. The carbonaceous materials of fuel elements of the present invention may be generally prepared by pyrolysis of the starting material at a temperature between about 400° C. and 1300° C., preferably between about 500° C. and 950° C., in a non-oxidizing atmosphere, for a period of time sufficient to ensure that a large portion or substantially all of the starting material has reached the desired carbonization temperature. Although the pyrolysis may be conducted at a constant temperature, it has been found that a slow pyrolysis, employing a gradually increasing heating rate, e.g., from about 1° C. to 20° C. per hour, preferably from about 5° C. to 25° C. per hour, over many hours, produces a uniform and higher carbon yield.

After cooling, the carbonaceous material may be pulverized. In some embodiments, the carbonaceous material is pulverized to a fine powder. This powder may be subjected to a second pyrolysis or polishing step, wherein the carbonized particulate material, is again pyrolyzed in a non-oxidizing atmosphere, at a temperature between about 650° C. to about 1250° C., preferably from about 700° C. to 900° C. At this point, the carbonaceous material is ready for combination with the ultrafine particle catalyst composition along with the other components of the fuel to produce a fuel element composition.

In embodiments of the present invention, the ultrafine particles of the catalyst compositions can be combined with a carbonaceous material in a number of ways to produce the fuel element composition. One method of combination comprises intimately mixing the carbonaceous material with the ultrafine particles. Ultrafine particles in dry powder form (e.g. nanopowder) may be mixed directly in a carbon mix along with other dry ingredients for extrusion. Alternatively, the ultrafine particles may be suspended in a liquid and the suspension mixed with extrudate.

Another method of combining the ultrafine catalyst compositions with a carbonaceous material comprises forming the carbonaceous material so as to concentrate the catalytic compositions in one or more longitudinal passageways extending partially through the fuel element. For example, the fuel element may comprise an inner core/outer shell arrangement where the outer shell comprises a carbonaceous material surrounding the inner core, and the inner core comprises ultrafine particle catalyst compositions. In some embodiments, the fuel element may include at least one longitudinal passageway extending at least partially therethrough.

Other methods of combining ultrafine particle catalyst compositions with a carbonaceous material can include wash coating, dipping, painting, spraying, or other methods known to those ordinary skill in the art. In another embodiment, the ultrafine particle catalyst compositions can be placed on inert support located directly behind the fuel element in an end to end relationship. The support for the ultrafine particles can be an inert carbon material such as graphite or a porous material such as alumina or porous graphite.

Once combined with the carbonaceous material, the catalyst composition may comprise up to 10% by weight of the resulting mixture. In some embodiments, the catalyst compositions may comprise 1% by weight of the resulting mixture. In another embodiment, catalyst composition may comprise 0.5% to 2% by weight of the resulting mixture.

The density of a fuel element according to some embodiments of the present invention can be generally greater than about 0.5 g/cc, greater than about 0.7 g/cc and greater than about 1 g/cc.

The overall length of the fuel element, prior to burning, can be generally less than about 20 mm, often less than about 15 mm, and can be typically about 12 mm. However, shorter fuel elements may be used if desired, depending upon the configuration of the cigarette in which they are employed. In an embodiment, the overall outside diameter of the fuel element can be less than about 8 mm, less than about 6 mm, and can be about 4.2 mm.

The carbonaceous and binder portions of the fuel compositions useful herein may be any of those carbonaceous and binder materials described in the patents recited in the Background of the Invention, supra. Several carbonaceous and binder materials are described in U.S. application Ser. No. 07/722,993, filed 28 Jun. 1991, now U.S. Pat. No. 5,178,167 the disclosure of which is hereby incorporated herein by reference.

In a further aspect, the present invention provides smoking articles. In an embodiment, a smoking article comprises a fuel element comprising a carbonaceous material and at least one catalyst composition, the catalyst composition comprising ultrafine particles. With reference to a cigarette as a smoking article, the cigarette further includes an aerosol generating means, which includes a substrate and at least one aerosol-forming material. An aerosol-generating means includes an aerosol forming material (e.g. glycerin), tobacco in some form (e.g. tobacco powders, tobacco extract or tobacco dust) and other aerosol forming materials and/or tobacco flavoring agents such as cocoa, licorice, and sugar. The aerosol forming material generally is carried on a substrate material such as a reconstituted tobacco cut filler or on a substrate such as tobacco cut filler, gathered paper, gathered tobacco paper, or the like.

In an embodiment of the present invention, the substrate is reconstituted tobacco, which is formed into a continuous rod or substrate tube assembly on a conventional cigarette making machine. Typically, the overwrap material for the rod is a barrier material such as a paper foil laminate. The foil serves as a barrier, and is located on the inside of the overwrap. Alternatively, the substrate may be a gathered paper formed into a rod or plug. When the substrate is a paper-type material, it can be positioned in a spaced-apart relationship from the fuel element comprising a carbonaceous material and a catalyst composition. A spaced-apart relationship is desired to minimize contact between the fuel element and the substrate, thereby preventing migration of the aerosol forming materials to the fuel element, as well as limiting the scorching or burning of the paper substrate. The spacing is normally provided during manufacture of the cigarette in accordance with one method of making the present invention. Appropriately spaced substrate plugs are overwrapped with a barrier material to form a substrate tube assembly having spaced substrate plugs therein. The substrate tube assembly is cut between the substrate plugs to form substrate sections. The substrate sections include a tube with a substrate plug and void(s), which can be at each end.

The barrier material for making the tube aids in preventing migration of the aerosol former to other components of the cigarette. The barrier material forming the tube is a relatively stiff material so that when formed into a tube, it will maintain its shape and will not collapse during manufacture and use of the cigarette.

In embodiments of the present invention, fuel elements of a smoking article can be advantageously circumscribed by an insulating and/or retaining jacket material. The insulating and retaining material is adapted such that drawn air can pass therethrough, and is positioned and configured so as to hold the fuel element in place. The jacket is flush with the ends of the fuel element, however, it may extend from about 0.5 mm to about 3 mm beyond each end of the fuel element.

The components of the insulating and/or retaining material which surrounds the fuel element can vary. Examples of suitable materials include glass fibers and other materials as described in U.S. Pat. No. 5,105,838; European Patent Publication No. 339,690; and pages 48-52 of the RJR Monograph, supra. Examples of other suitable insulating and/or retaining materials are glass fiber and tobacco mixtures such as those described in U.S. Pat. Nos. 5,105,838, 5,065,776 and 4,756,318; and U.S. patent application Ser. No. 07/354,605, filed 22 May 1989 now U.S. Pat. No. 5,119,837.

Other suitable insulating and/or retaining materials are gathered paper-type materials which are spirally wrapped or otherwise wound around the fuel element, such as those described in U.S. patent application Ser. No. 07/567,520, filed 15 Aug. 1990, now U.S. Pat. No. 5,105,836. The paper-type materials can be gathered or crimped and gathered around the fuel element; gathered into a rod using a rod making unit available as CU-10 or CU2OS from DeCoufle s.a.r.b., together with a KDF-2 rod making apparatus from Hauni-Werke Korber & Co., KG, or the apparatus described in U.S. Pat. No. 4,807,809 to Pryor et al.; wound around the fuel element about its longitudinal axis; or provided as longitudinally extending strands of paper-type sheet using the types of apparatus described in U.S. Pat. No. 4,889,143 to Pryor et al. and U.S. Pat. No. 5,025,814 to Raker, the disclosures of which are incorporated herein by reference.

If desired, the fuel element may be extruded into the insulating jacket material as set forth in U.S. patent application Ser. No. 07/856,239, filed 25 Mar. 1992, the disclosure of which is incorporated herein by reference.

Examples of paper-type sheet materials are available as P-2540-136-E carbon paper and P-2674-157 tobacco paper from Kimberly-Clark Corp.; and the longitudinally extending strands of such materials (e.g., strands of about 1/32 inch width) extend along the longitude of the fuel element. The fuel element also can be circumscribed by tobacco cut filler (e.g., flue-cured tobacco cut filler treated with about 2 weight percent potassium carbonate). The number and positioning of the strands or the pattern of the gathered paper is sufficiently tight to maintain, retain or otherwise hold the composite fuel element structure within the cigarette.

In embodiments of the present invention, the fuel element-jacket assembly is combined with a substrate section or substrate tube assembly by a wrapper material, which has a propensity not to burn, to form a fuel element/substrate section. In some embodiments of the cigarettes, the wrapper typically extends from the mouthend of the substrate section, over a portion of the jacketed fuel element, whereby it is spaced from the lighting end of the fuel element. The wrapper material assists in limiting the amount of oxygen which will reach the burning portion of the fuel element during use, thereby causing the fuel element to extinguish after an appropriate number of puffs. In an embodiment of the cigarette, the wrapper is a paper/foil/paper laminate. The foil provides a path to assist in dissipating or transferring the heat generated by the fuel element during use. The jacketed fuel element and the substrate section are joined by the overwrap.

A tobacco section can be formed by a reconstituted tobacco cut filler rod, made on a typical cigarette making machine, and cut into appropriate lengths. A filter rod is formed and cut into appropriate lengths for joining to the tobacco section to form a mouthend section. The fuel element/substrate section and the mouthend section are joined by aligning the reconstituted ends of each section, and overwrapped to form a cigarette.

When a paper substrate is used, a tobacco paper rod and a reconstituted cut filler rod are formed and cut into appropriate lengths and joined to form a tobacco section. The tobacco section and the fuel element assembly/substrate section are joined by aligning the tobacco paper plug end of the tobacco section with the substrate end of the fuel element assembly/substrate section and joining the sections with a wrapper which extends from the rear end of the tobacco roll to an appropriate length past the junction of the two sections for forming the tobacco roll/fuel element assembly. The tobacco roll/fuel element assembly is then joined to a filter by a tipping material.

As described above, the substrate carries aerosol forming materials and other ingredients, e.g., flavorants and the like, which, upon exposure to heated gases passing through the aerosol generating means during puffing, are vaporized and delivered to the user as a smoke-like aerosol. Aerosol forming materials used herein include glycerin, propylene glycol, water, and the like, flavorants, and other optional ingredients. The patents referred to in the Background of the Invention (supra) teach additional useful aerosol forming materials that need not be repeated here.

Cast sheets of tobacco dust or powder, a binder, such as an alginate binder, and glycerin can also be used to form useful substrates herein. Suitable cast sheet materials for use as substrates are described in U.S. Pat. No. 5,101,839 and U.S. patent application Ser. No. 07/800,679, filed Nov. 27, 1991.

Suitable cast sheet materials typically contain between about 30 to 75 weight percent of an aerosol former such as glycerin; about 2 to 15 weight percent of a binder, such as ammonium alginate; 0 to about 2 weight percent of a sequestering agent such as potassium carbonate; about 15 to about 70 to 75 weight percent of organic, inorganic filler materials, or mixtures thereof, such as tobacco dust, aqueous extracted tobacco powder, starch powder, rice flower, ground puffed tobaccos, carbon powder, calcium carbonate powder, and the like, and from about 0 to about 20 weight percent of flavors such as tobacco extracts, and the like.

In one embodiment, a cast sheet material includes 60 weight percent glycerin, 5 weight percent ammonium alginate binder, 1 weight percent potassium carbonate, 2 weight percent flavors such as tobacco extracts and 32 weight percent aqueous extracted tobacco powder.

The cast sheets are formed by mixing aqueous extracted tobacco powder, water and the potassium carbonate in a high sheer mixer to produce a smooth, flowable paste. Glycerin and ammonium alginate are then added and the high shear mixing is continued until a homogenized mixture is produced. The homogenized mixture is cast on a heated belt (about 200.degree. F.) with a 0.0025 to 0.0035 inch casting clearance and is dried to yield a 0.0004 to 0.0008 inch thick sheet under high temperature air (about 200.degree. to 250.degree. F.). The sheet is doctored from the belt and either wound onto spools for slitting into webs or chopped into rectangular pieces about 2 inches by 1 inch which are formed into cut filler. If the cast sheet material is used in a web or cut filler form, normally the substrate will be from about 10 mm to 40 mm in length and extend from the rear end of the fuel element to the tobacco segment or the front end of an extra long filter segment (e.g., about 30 mm to 50 mm in length). In such instances the tobacco paper plug can be omitted.

In embodiments of the present invention, the combination of the fuel element and the substrate (also known as the front end assembly) is attached to a mouthend piece; although a disposable fuel element/substrate combination can be employed with a separate mouthend piece, such as a reusable cigarette holder. The mouthend piece provides a passageway which channels vaporized aerosol forming materials into the mouth of the smoker; and can also provide further flavor to the vaporized aerosol forming materials.

Flavor segments (i.e., segments of gathered tobacco paper, tobacco cut filler, or the like) can be incorporated in the mouthend piece or the substrate segment, e.g., either directly behind the substrate or spaced apart therefrom, to contribute flavors to the aerosol. Gathered carbon paper can be incorporated, particularly in order to introduce menthol flavor to the aerosol. Such papers are described in European Patent Publication No. 342,538. Other flavor segments useful herein are described in U.S. patent application Ser. No. 07/414,835, filed 29 Sep. 1989, now U.S. Pat. No. 5,076,295 Ser. No. 07/606,287, filed 6 Nov. 1990; now U.S. Pat. No. 5,105,834 and Ser. No. 07/621,499, filed 7 Dec. 1990, now abandoned.

FIG. 1 illustrates a smoking article according to an embodiment of the present invention. The smoking article depicted in FIG. 1 comprises a fuel element 10 of the present invention comprising a carbon source and at least one catalytic composition comprising ultrafine particles of a metal oxide and/or metal. The fuel element displays a plurality of passageways 11 therethrough, about thirteen passageways altogether. The fuel element 10 is surrounded by insulating sheet material 16 having a plurality of grooves which facilitate the formation of the sheet material into a jacket surrounding the fuel element. In embodiments of the smoking article, the jacket can be made of calcium sulfate (CaSO₄).

A metallic capsule 12 overlaps a portion of the mouthend of the fuel element 10 and encloses the physically separate aerosol generating means which contains a substrate material 14. The substrate material carries one or more aerosol forming materials. The substrate may be in particulate form, in the form of a rod, and other geometric shapes advantageous for generating an aerosol.

Capsule 12 is circumscribed by a roll of tobacco 18. Alternatively, in other smoking articles, the capsule may be circumscribed with an additional or continuous jacket of an insulating sheet material. Insulating sheet materials suitable for use in smoking articles of the present invention are further described in U.S. Pat. No. 5,303,720 to Banerjee which is hereby incorporated by reference. Two slit-like passageways 20 are provided at the mouth of the capsule in the center of the crimped tube.

At the mouth end of the tobacco roll 18, is a mouthend piece 22, comprising a cylindrical segment of a flavored carbon filled sheet material 24 and a segment of non-woven thermoplastic fibers 26 through which the aerosol passes to the user. The smoking article, or portions thereof, is overwrapped with one or more layers of cigarette papers 30-36

In some embodiments, catalyst compositions comprising metal oxide and/or metal ultrafine particles are incorporated into the filter element of the smoking article as described in U.S. patent application Ser. No. 10/730,962 which is hereby incorporated by reference.

In certain embodiments of the cigarettes of the present invention, convective heating is the predominant mode of energy transfer from the burning fuel element comprising a carbonaceous material and at least one catalyst composition to the aerosol-generating means disposed longitudinally behind the fuel element. When a foil/paper laminate is used as an overwrap to join the fuel/substrate section some heat may be transferred to the substrate by the foil layer. As described above, the heat transferred to the substrate volatilizes the aerosol-forming material(s) and any flavorant materials carried by the substrate, and, upon cooling, these volatilized materials are condensed to form a smoke-like aerosol which is drawn through the cigarette during puffing, and which exits the filter piece. This smoke-like aerosol can contain reduced amounts of carbon monoxide resulting from the reduced carbon monoxide production of a fuel element of the present invention upon combustion.

In some embodiments, the catalyst compositions can be deposited on a porous support such as graphite or alumina wherein the porous support is placed behind the fuel in an end to end relationship.

In a further aspect, the present invention provides a method for facilitating the reduction in the amount of carbon monoxide produced by a smoking article, comprising incorporating at least one catalyst composition comprising ultrafine particles of a metal oxide and/or metal into the fuel element of a smoking article.

In another aspect, the present invention provides methods and apparatus for the simultaneous quantification of the carbon monoxide content and carbon dioxide content of a gaseous mixture. In an embodiment, a method for quantifying the carbon monoxide content and carbon dioxide content of a gaseous mixture comprises injecting the gaseous mixture into a split injection tube of a gas chromatograph through a single injector, resolving a relative carbon monoxide content of the gaseous mixture on a first chromatographic column, simultaneously resolving a relative carbon dioxide content on a second chromatographic column, and detecting and quantifying the eluate carbon monoxide and carbon dioxide with a mass spectrometer. In further embodiments, the gaseous mixture containing carbon monoxide and carbon dioxide comprises mainstream smoke or a smoke-like aerosol produced from a smoking article.

Under some circumstances, carbon monoxide and carbon dioxide can be resolved on a single chromatographic column. Single columns that are capable of resolving both carbon monoxide and carbon dioxide, however, use carrier gas at flow rates that are too high for use with a mass spectrometer. As a result, their use precludes the numerous advantages gained by the two-dimensional analysis of GC/MS. Moreover, other single chromatographic columns that use a carrier gas at acceptable flow rates for use with a mass spectrometer cannot effectively resolve both carbon monoxide and carbon dioxide.

The utilization of dual chromatographic columns allows for the complete resolution of the carbon monoxide and carbon dioxide contents of the gaseous mixture at flow rates that are acceptable for use with a mass spectrometer. The two-dimensional analysis provided by gas chromatography/mass spectrometry (GC/MS) can provide precise relative quantifications of carbon monoxide and carbon dioxide amounts present in gaseous mixtures.

FIG. 2 illustrates a flowchart for the quantification of carbon monoxide and carbon dioxide contents of a gaseous mixture according to an embodiment of the present invention. In particular embodiments, the gaseous mixture comprises mainstream smoke or smoke-like aerosol from a smoking article. The gaseous mixture is injected into the split injector of the gas chromatogram 201. The split injector 201 splits the gaseous mixture for simultaneous resolution on dual chromatographic columns. The carbon monoxide content of the mainstream smoke is resolved on a first chromatographic column 202, and the carbon dioxide content is simultaneously resolved on a second chromatographic column 203. The first chromatographic column can be selected for optimal resolution of carbon monoxide while the second chromatographic column can be selected for the optimal resolution of carbon dioxide. For example, a Molsieve column can be used to resolve carbon monoxide and a wide-bore GS-CarbonPLOT column can be used to resolve carbon dioxide.

Once resolved, the carbon monoxide content and carbon dioxide content of the mainstream smoke are quantified by a mass spectrometer 204. The use of a mass spectrometer adds a second dimension of analysis that is not present with traditional gas chromatographic detection devices. A mass spectrometer can further resolve the carbon monoxide content and carbon dioxide content of a gaseous mixture allowing for greater accuracy and precision when quantifying these chemical species.

In an embodiment, an apparatus for quantifying the carbon monoxide content and carbon dioxide content of a gaseous mixture comprises: a gas chromatograph comprising a single split injector, dual chromatographic columns; and a mass spectrometer.

FIG. 3 illustrates an apparatus for the simultaneous quantification of the carbon monoxide content and carbon dioxide content of a gaseous mixture comprising the two-dimensional analysis of gas chromatography and mass spectrometry in an embodiment according to the present invention. The gas chromatograph 301 comprises a single injector 302 which splits the sample onto two chromatographic columns 303, 304. The temperature of the split single injector 302 can be varied in accordance with desired analytical conditions. The temperature variance of the single split injector 302 can be controlled manually by a user or can be controlled electronically with any processor-equipped device such as a computer and/or dedicated controller. As previously discussed, one of the two columns 303 is suitable for resolving the carbon monoxide content of a gaseous mixture while the other column 304 is suitable for resolving the gaseous mixture's carbon dioxide content. Chromatographic columns for use in the gas chromatograph of the present apparatus are available commercially.

The two chromatographic columns feed into a mass spectrometer 305. Mass spectrometers suitable for use in further resolving and quantifying the carbon monoxide content and carbon dioxide content eluting from the two columns of the gas chromatograph can comprise mass analyzers comprising magnetic sector analyzers, double-focusing spectrometers, quadrupole mass filters, ion trap analyzers, and time-of-flight (TOF) analyzers.

The embodiments described above in addition to other embodiments can be further understood with reference to the following examples. Several of the fuel elements provided in the examples below comprise percentages of BKO carbon, Guar gum, graphite, and tobacco. Combustion of all the fuel elements in the examples below provides energy used to generate aerosol from tobacco and other aerosol formers like glycerin. Combustion of the fuel elements, however, also produces carbon monoxide and carbon dioxide. Moreover, complete combustion of the fuel elements produces a maximum amount of energy and a carbon dioxide by-product. Complete combustion is demonstrated by the chemical reaction:
C (s)+O₂ (g)→CO₂ (g)
Incomplete combustion, nevertheless, produces much less energy and a substantial carbon monoxide by-product. Incomplete combustion is demonstrated by the reaction sequence:
C (s)+O (g)→CO (g)
C (s)+O₂ (g)→CO₂ (g)
As a result, complete combustion of the fuel element in desirable.

Graphite in the fuel elements comprising graphite, BKO carbon, Guar gum, and tobacco, is inactive up to the temperatures attained by combustion of the fuel element and remains substantially unchanged throughout the combustion of the fuel element. The remaining three carbonaceous components undergo oxidation during the combustion to provide energy and oxides of carbon. Among the carbonaceous components, BKO carbon is the major component and hence chosen for the study of the fuel elements in the examples below.

EXAMPLE 1

Several materials were prepared to evaluate the efficacy of a method and apparatus for simultaneously resolving the carbon monoxide content and carbon dioxide content of a gaseous mixture according to an embodiment of the present invention. The materials prepared for analysis by the method and apparatus were a standard gaseous mixture (CO:CO₂:N₂), tobaccos from 1R4F cigarettes, and 1R4F cigarette smoke. A small quantity of each sample was heated to 700° C. for 20 seconds in the presence of air. The standard gaseous mixture was analyzed in the absence of air to preserve the composition of the sample. A pyroprobe was used for sample heating. The temperatures of the pyroprobe interface and the gas chromatograph injector were set at ambient temperature. The gas chromatograph utilized was a Hewlett-Packard 5890 Series II. A single injection onto dual chromatographic columns was used for the carbon monoxide and carbon dioxide analysis. A Molsieve column (Chrompack, 25 M×0.32 mm I.D., 30 μm film) was used for carbon monoxide resolution, and a GS-CarbonPLOT column (J&W Scientific, 60 M×0.32 mm I.D., 1.5 μm film) was used for carbon dioxide resolution. The temperatures of the columns were held at 35° C. for 10 minutes, programmed to 150° C. at 25° C./min and held for 10 min. A single mass spectrometer was used to identify and quantify the resolved carbon monoxide and carbon dioxide peaks eluting from the chromatographic columns. The mass spectrometer utilized was a Hewlett-Packard 5972 mass selective detector. The mass spectrometer was operated at 70 eV in the EI mode with the temperature of the ion source being maintained at 180° C. The mass range scanned was 20-200 atomic mass units. The carbon monoxide and carbon dioxide quantified were only a fraction of the total carbon monoxide and carbon dioxide generated from the heated materials. Only the resolved carbon monoxide and carbon dioxide peak areas were used for quantification.

The results of the standard gaseous mixture resolved on the dual chromatographic columns are illustrated in FIG. 4. The ion chromatogram of FIG. 4 demonstrates a completely resolved carbon monoxide peak and a completely resolved carbon dioxide peak. For comparative purposes, the standard gaseous mixture (CO:CO₂:N₂) was injected and resolved on single column gas chromatographs under experimental conditions consistent with resolution on dual chromatographic columns. The standard gaseous mixture was resolved on a single column gas chromatograph comprising a Molsieve column. The results are illustrated in FIG. 5. As demonstrated in the ion chromatogram of FIG. 5, the Molsieve column completely resolved the carbon monoxide content but failed to completely resolve the carbon dioxide content of the standard gaseous mixture. Similarly, the standard gaseous mixture was additionally resolved on a single GS-CarbonPLOT chromatographic column. The results of this resolution are illustrated in FIG. 6. The ion chromatogram of FIG. 6 displays a complete resolution of carbon dioxide and an incomplete resolution of carbon monoxide. The carbon monoxide co-eluted with nitrogen and oxygen.

The results of the remaining sample materials comprising tobaccos from 1R4F cigarettes and 1R4F cigarette smoke resolved on dual chromatographic columns in accordance with the present invention are illustrated in FIGS. 7 and 8 respectively. The ion chromatograms of FIGS. 7 and 8 demonstrate completely and sharply resolved carbon monoxide and carbon dioxide peaks.

EXAMPLE 2

Seven samples were generated for analysis of carbon monoxide/carbon dioxide (CO/CO₂) ratios. These samples were: (1) Control Carbon Black 950, (2) Carbon Black 950 with 5% Fe₂O₃ ultrafine particles, (3) Carbon Black 950 with 2% Fe₂O₃ ultrafine particles, (4) Carbon Black 950 with 5% TiO₂—Au ultrafine particles and (5) Carbon Black 950 with 2% TiO₂—Au ultrafine particles, (6) Carbon Black 950 with 5% CeO₂ ultrafine particles, and (7) Carbon Black 950 with 2% CeO₂ ultrafine particles.

To simulate combustion of the fuel element, a pyroprobe was used to heat a small quantity of each sample to 700° C. for 20 seconds in the presence of air. 700° C. is the average temperature of a fuel element during combustion. The gaseous mixture resulting from the combustion of each sample was analyzed in accordance with the method delineated in FIG. 2. The pyroprobe and gas chromatogram injector were set at ambient temperature. A Molsieve chromatographic column was used for carbon monoxide resolution and a GS-CarbonPLOT chromatographic column was used for carbon dioxide resolution. A mass spectrometer was used as a second dimension of analysis in the quantification of the carbon monoxide and carbon dioxide contents generated by the samples. It should be noted that the carbon monoxide and the carbon dioxide contents quantified were only a fraction of the carbon monoxide and carbon dioxide contents produced by the samples and that the resolved peak areas were used for quantification. Table 1 summarizes the results produced by the samples in this example.

	TABLE 1
	MASS ABUNDANCE
	(COUNTS)A	CO/CO2
SAMPLES	CO	CO2	Ratio
(1) Control Carbon	383,013,104	1,284,639,516	0.298
(2) Carbon and 5% Fe2O3	53,357,015	1,202,285,067	0.0444
(3) Carbon and 2% Fe2O3	65,069,392	1,093,984,395	0.0595
(4) Carbon and 5% TiO2-Au	131,461,228	926,581,662	0.142
(5) Carbon and 2% TiO2-Au	264,095,113	956,314,408	0.276
(6) Carbon and 5% CeO2	268,205,948	965,498,063	0.278
(7) Carbon and 2% CeO2	279,547,847	977,688,888	0.286
Air Blank	655,583	7,602,213
AMass abundance is the total abundance of ions in a mass spectrum for compound with unit of counts.

The results displayed in Table 1, which are additionally illustrated in FIG. 9, demonstrate that ferric oxide (Fe₂O₃) ultrafine particles effectuate a significant reduction in the amount of carbon monoxide produced by the fuel element. Fuel element sample (2) comprising 5% ferric oxide (Fe₂O₃) ultrafine particles by weight exhibited an 85% reduction in the amount of carbon monoxide produced when heated. Similarly, fuel element sample (3) comprising 2% ferric oxide (Fe₂O₃) ultrafine particles by weight displayed an 80% reduction in the amount of carbon monoxide produced upon sample heating. The titanium oxide-gold (TiO₂—Au) ultrafine particles of sample (4) demonstrated a carbon monoxide reduction of 52% while the ceric oxide (CeO₂) ultrafine particles of sample (6) resulted in approximately a 7% reduction.

EXAMPLE 3

Eight fuel element samples were generated for analysis of (CO/CO₂) ratios. These samples were: (1) BKO Carbon 950, (2) BKO Carbon 950 with 5% gamma-Fe₂O₃-large particle, (3) BKO 950 Carbon with 5% Fe₂O₃-nanoparticle, (4) BKO 950 Carbon with 2% Fe₂O₃-nanoparticle, (5) Carbon Mix 1 (78.3% BKO 950 Carbon, 10.1% Guar gum, 6.55% graphite, and 5.05% tobacco), (6) Carbon Mix 1 with 5% Fe₂O₃-nanoparticle, (7) Carbon Mix 2 (82.4% BKO Carbon 950, 10.6% Guar gum, and 7.0% graphite) and (8) Carbon Mix 2 with 5% Fe₂O₃-nanopaticle.

To simulate combustion of the fuel element, a pyroprobe was used to heat a small quantity of each sample to 700° C. in the presence of air for 20 seconds. 700° C. is the average temperature of a fuel element during combustion. The gaseous mixture resulting from the combustion of each sample was analyzed in accordance with the method delineated in FIG. 2. The pyroprobe and gas chromatogram injector were set at ambient temperature. A Molsieve chromatographic column was used for carbon monoxide resolution and a GS-CarbonPLOT chromatographic column was used for carbon dioxide resolution. A mass spectrometer was used as a second dimension of analysis in the quantification of the carbon monoxide and carbon dioxide contents generated by the samples. It should be noted that the carbon monoxide and the carbon dioxide contents quantified were only a fraction of the carbon monoxide and carbon dioxide contents produced by the samples and that the resolved peak areas were used for quantification. Table 2 summarizes the results produced by the samples in this example.

	TABLE 2
	MASS ABUNDANCE
	(COUNTS)A
SAMPLES	CO	CO2	CO/CO2 Ratio
(1) BKO Carbon 950	136,632,880	439,836,557	0.311
(2) BKO Carbon 950 and	34,403,969	511,214,899	0.0673
5% γ-Fe2O3-large particle
(3) BKO 950 and 5%	16,068,614	489,909,229	0.0328
Fe2O3-nanoparticle
(4) BKO 950 and 2%	26,802,880	508,261,449	0.0527
Fe2O3-nanoparticle
(5) Carbon Mix 1	98,093,373	458,829,259	0.214
(6) Carbon Mix 1 and 5%	89,003,804	491,290,439	0.181
Fe2O3-nanoparticle
(7) Carbon Mix 2	105,287,470	463,439,227	0.227
(8) Carbon Mix 2 and 5%	34,534,408	478,608,718	0.0722
Fe2O3-nanoparticle
AMass abundance is the total abundance of ions in a mass spectrum for compound with unit of counts.

The results summarized in Table 2, which are further illustrated in FIG. 10, demonstrate that ferric oxide (Fe₂O₃) ultrafine particles can effectuate a reduction in the amount of carbon monoxide produced by a fuel element. Comparison of the CO/CO₂ ratios of sample (2) comprising 5% gamma-Fe₂O₃-large particle and sample (3) comprising 5% Fe₂O₃ nanoparticle reveals the dependency of catalytic activity on particle size. The smaller Fe₂O₃ ultrafine particles exhibit a greater surface area than the γ—Fe₂O₃-large particles which leads to higher catalyst turnover rates and a greater reduction in the amount of carbon monoxide produced by the fuel element upon heating. The Fe₂O₃ ultrafine particles of sample (3) reduced the carbon monoxide content of the gaseous mixture analyzed by 89.5%, which is an 11% increase over the γ—Fe₂O₃-large particles.

The results of the sample testing further demonstrate the catalytic activity of ferric oxide ultrafine particles in fuel elements that comprise the additional components of Guar gum and graphite. Sample (7) is an example of a fuel element containing these additional components. Sample (8) comprises the components of sample (7) with the addition of 5% by weight of ferric oxide (Fe₂O₃) ultrafine particles. The ferric oxide (Fe₂O₃) ultrafine particles reduced the carbon monoxide production of the fuel element of sample (8) by 68% in comparison with sample (7) which did not contain ferric oxide (Fe₂O₃) ultrafine particles.

Fuel elements containing tobacco components were additionally analyzed in this example. Sample (5) is a fuel element containing a 5.05% tobacco content in addition to BKO Carbon 950, Guar gum, and graphite. Sample (6) comprises the components of sample (5) with the addition of 5% by weight of ferric oxide (Fe₂O₃) nanoparticle. The ferric oxide (Fe₂O₃) ultrafine particles reduced the carbon monoxide production of the fuel element of sample (6) by 15.4% in comparison with sample (5) which did not contain ferric oxide (Fe₂O₃) ultrafine particles. The catalytic activity of the ferric oxide (Fe₂O₃) ultrafine particles in sample (6) was diminished due to the tobacco content in the fuel element composition. The combustion of tobacco produces several chemical species that inhibit the catalytic behavior of the ultrafine particles. This catalytic inhibition is displayed in the 15.4% reduction of carbon monoxide production.

EXAMPLE 4

Seven carbon samples were generated for analysis of CO/CO₂ ratios. The sample were: (1) Control Carbon (BKO 950), (2) Carbon with 5% Fe₂O₃ ultrafine particles obtained from MACH-1, Inc., (3) Carbon with 5% Al₂O₃ ultrafine particles obtained from NEI, Inc., (4) Carbon with 5% CeO₂ ultrafine particles obtained from NEI, Inc., (5) Carbon with 5% TiO₂ ultrafine particles obtained from NEI, Inc., (6) Carbon with 5% tobacco and 5% Fe₂O₃ ultrafine particles obtained from MACH-1, Inc., and (7) Carbon with 5% tobacco (heat treated) and 5% Fe₂O₃ ultrafine particles obtained from MACH-1, Inc.

To simulate combustion of the fuel element, a pyroprobe was used to heat a small quantity of each sample to 700° C. in the presence of air for 20 seconds. 700° C. is the average temperature of a fuel element during combustion. The gaseous mixture resulting from the combustion of each sample was analyzed in accordance with the method delineated in FIG. 2. The pyroprobe and gas chromatogram injector were set at ambient temperature. A Molsieve chromatographic column was used for carbon monoxide resolution and a GC-CarbonPLOT chromatographic column was used for carbon dioxide resolution. A mass spectrometer was used as a second dimension of analysis in the quantification of the carbon monoxide and carbon dioxide contents generated by the samples. It should be noted that the carbon monoxide and the carbon dioxide contents quantified were only a fraction of the carbon monoxide and carbon dioxide contents produced by the samples and that the resolved peak areas were used for quantification. Table 3 summarizes the results produced by the samples in this example.

	TABLE 3
	CO/
	MASS ABUNDANCE	CO2
	(COUNTS)B	Ra-
SAMPLESA	CO	CO2	tio
(1) Control Carbon (BKO	349,722,771	1,097,283,105	0.319
950)
(2) Carbon and 5% Fe2O3	73,461,112	1,171,782,023	0.0627
ultrafine particles
(3) Carbon and 5% Al2O3	323,332,586	988,477,673	0.327
ultrafine particles
(4) Carbon and 5% CeO2	285,376,477	1,032,058,820	0.277
ultrafine particles
(5) Carbon and 5% TiO2	379,654,967	1,164,775,102	0.326
ultrafine particles
(6) Carbon, 5% Tobacco,	184,501,337	1,042,248.352	0.177
and 5% Fe2O3 ultrafine
particles
(7) Carbon, 5% Tobaccoc,	199,972,837	1,165,685,787	0.172
and 5% Fe2O3 ultrafine
particles
Air Blank	2,501,751	12,070,258
AAll carbon samples were baked at 950 C. prior to the analysis.
BMass abundance is the total abundance of ions in a mass spectrum for compound with unit of counts.
cTobacco was heat-treated at 100° C. for 4 hours.

The results summarized in Table 3 and further illustrated in FIG. 11 reiterate the efficacy of ferric oxide (Fe₂O₃) ultrafine particles in reducing the carbon monoxide production of fuel elements according to the present invention. When compared to titanium oxide (TiO₂), aluminum oxide (Al₂O₃), and ceric oxide (CeO₂) ultrafine particles, ferric oxide (Fe₂O₃) ultrafine particles demonstrate a greater reduction in the carbon monoxide production of heated fuel elements. In this example, samples (3) and (5) containing aluminum oxide (Al₂O₃) and titanium oxide (TiO₂) ultrafine particles respectively exhibited a slight increase in carbon monoxide content. Moreover, sample (4) comprising ceric oxide (CeO₂) ultrafine particles displayed a carbon monoxide reduction of 13%. Sample (2) comprising ferric oxide (Fe₂O₃) ultrafine particles, however, exhibited a carbon monoxide reduction of 80%.

In samples (6) and (7), ferric oxide (Fe₂O₃) ultrafine particles were additionally incorporated into fuel elements that contained tobacco as well. The reduction of carbon monoxide produced from these fuel elements when heated was diminished due to the catalyst poisoning chemical species generated upon tobacco combustion.

EXAMPLE 5

Seven tobacco samples were generates for analysis of CO/CO₂ ratios. The samples were: (1) Control Camel LT® Tobacco, (2) Camel LT® Tobacco with 5% Fe₂O₃ ultrafine particles, (3) Camel LT® Tobacco with 2% Fe₂O₃ ultrafine particles (4) Camel LT® Tobacco with 5% TiO₂—Au ultrafine particles, (5) Camel LT® Tobacco with 2% TiO₂—Au ultrafine particles, (6) Camel LT® Tobacco with 5% CeO₂ ultrafine particles, and (7) Camel LT® Tobacco with 2% CeO₂ ultrafine particles.

A Chemical Data System (CDS) Model 2000 pyroprobe was used for sample heating. A small quantity of each sample (approximately 7 mg) was heated at 700° C. in the presence of air for 20 seconds. The gaseous mixture resulting from the heating of each sample was analyzed in accordance with the method delineated in FIG. 2. The temperatures of the pyroprobe interface and the injector on the gas chromatogram were set at ambient temperature. The GC used was a Hewlett-Packard 5890 Series II gas chromatograph. A single injection onto dual columns was used for CO and CO₂ analysis. A Molsieve column (Chrompack, 25 M×0.32 mm I.D., 30 μm film) was used for CO analysis. A GS-CarbonPLOT column (J&W Scientific, 60 M×0.32 mm I.D., 1.5 μm film) was used for CO₂ analysis. The temperature of the CG columns was held at 35° C. for 10 minutes, programmed to 150° C. at 25° C./min and held for 10 min. A mass spectrometer (MS) was used to identify and quantify the resolved CO and CO₂ peaks eluting from the gas chromatograph. The MS used was a Hewlett-Packard 5972 mass selective detector. The mass spectrometer was operated at 70 eV in the El mode. The temperature of the ion source was maintained at 180° C. and the mass range scanned was 20-200 atomic mass units. It should be noted that the CO and CO₂ quantities determined were only a fraction of the total CO and CO₂ content generates from the samples. Only the resolved CO and CO₂ peak areas were used for quantification. Table 4 summarizes the results produced by the samples in this example.

	TABLE 4
	MASS ABUNDANCE
	(COUNTS)A	CO/CO2
SAMPLES	CO	CO2	Ratio
(1) Camel LT Tobacco	544,728,554	1,383,849,048	0.394
(2) Camel LT ® Tobacco	526,196,075	1,343,828,130	0.392
with 5% Fe2O3
(3) Camel LT ® Tobacco	532,589,297	1,354,841,196	0.393
with 2% Fe2O3
(4) Camel LT ® Tobacco	540,678,974	1,370,604,676	0.395
with 5% TiO2-Au
(5) Camel LT ® Tobacco	536,124,377	1,392,004,504	0.385
with 2% TiO2-Au
(6) Camel LT ® Tobacco	529,191,513	1,361,128,568	0.389
with 5% CeO2
(7) Camel LT ® Tobacco	523,482,876	1,365,668,545	0.383
with 2% CeO2
Air Blank	655,583	7,602,213
AMass abundance is the total abundance of ions in a mass spectrum for each compound with unit of counts.

The results summarized in Table 4 and further illustrated in FIG. 12 display that the catalytic activities of the metal and metal-oxide ultrafine particles comprising the catalyst compositions of the present invention are inhibited when combined with only tobacco to compose a fuel element. These results are consistent with fuel element samples of previous examples that contained specific amounts of tobacco. When heated or combusted, the tobacco content of the fuel element produces several chemical species that poison the catalytic ultrafine particles and thereby significantly reduce, if not eliminate, the catalytic oxidation of carbon monoxide to carbon dioxide. Consequently, tobacco components of fuel elements according to the present invention are disfavored. As displayed in the previous examples, however, a small component of tobacco within the fuel element does not destroy the catalytic activity of the metal oxide and metal ultrafine particles an appreciable amount and is, therefore, tolerable. The inclusion of a tobacco component in the fuel element of a smoking article can provide more flavor to the aerosol comprising the mainstream smoke of a smoking article.

Claims

1. A fuel element comprising:

a carbonaceous material; and

at least one catalyst composition comprising ultrafine particles of a metal oxide, metal, or mixtures thereof.

2. The fuel element of claim 1, wherein the metal oxide comprises ferric oxide.

3. The fuel element of claim 1, wherein the metal comprises gold, copper, silver, platinum, palladium, rhodium, nickel, and mixtures thereof.

4. The fuel element of claim 1, wherein the catalyst composition comprises up to 5% by weight of the fuel element.

5. The fuel element of claim 1 wherein the ultrafine particles have an individual particle size up to about 1 micrometer.

6. The fuel element of claim 1, wherein the ultrafine particles have an individual particle size of up to about 5 nanometers.

7. The fuel element of claim 1, wherein the ultrafine particles have an individual particle size between about 2 and about 4 nanometers.

8. A smoking article comprising:

a fuel element comprising a carbonaceous material and at least one catalyst composition comprising ultrafine particles of a metal oxide, metal, or mixtures thereof; and

a physically separate aerosol generating means comprising at least one aerosol forming material.

9. The smoking article of claim 8 wherein the metal oxide comprises ferric oxide.

10. The smoking article of claim 8, wherein the catalyst composition is operable to convert carbon monoxide to carbon dioxide at temperatures between about 700° C. and about 950° C.

11. A method for reducing carbon monoxide production of a fuel element comprising:

incorporating a catalyst composition into the fuel element, the catalyst composition comprising:

ultrafine particles of a metal oxide, metal, or mixtures thereof.

12. The method of claim 11, wherein incorporating a catalyst composition into the fuel element comprises wash coating, dipping, painting, or spraying the fuel element with the catalyst composition.

13. The method of claim 11, wherein incorporating a catalyst composition into the fuel element comprises placing the catalyst composition in an inner core of the fuel element wherein the inner core is surrounded by an outer shell comprising carbonaceous material.

14. The method of claim 11, wherein incorporating a catalyst composition into a fuel element comprises placing the catalyst composition on a substrate located behind the fuel element.

15. The method of claim 14, wherein the substrate comprises an inert carbon material or a porous material.

16. A method for simultaneously quantifying a carbon monoxide content and a carbon dioxide content of a gaseous mixture comprising:

injecting the gaseous mixture into a split single injector of a gas chromatogram;

resolving the carbon monoxide content of the gaseous mixture on a first chromatographic column and simultaneously resolving the carbon dioxide content of the gaseous mixture on a second chromatographic column; and

detecting and quantifying the resolved carbon monoxide content and carbon dioxide content with a mass spectrometer.

17. The method of claim 16, wherein the gaseous mixture comprises smoke from a smoking article, mainstream smoke from a smoking article, smoke-like aerosol from a smoking article, or mixtures thereof.

18. An apparatus for simultaneously quantifying a carbon monoxide content and a carbon dioxide content of a gaseous mixture comprising:

a gas chromatograph comprising a split single injector and two chromatographic columns; and

a mass spectrometer.

19. The apparatus of claim 18, wherein one of the chromatographic columns possesses the ability to resolve carbon monoxide from a gaseous mixture, and the remaining chromatographic column possesses the ability to resolve carbon dioxide from a gaseous mixture.

20. The apparatus of claim 18, wherein the temperature of the split single injector of the gas chromatograph is variable.