US20050051185A1

Movatterモバイル変換

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Publication number: US20050051185A1
Application number: US10/866,181
Authority: US
Inventors: Firooz Rasouli; Ping Li; Susan Tafur; Jeffrey Allen; Shalva Gedevanishvili; Mohammad Hajaligol; Roland Dwyer; Charles Glenn
Original assignee: Philip Morris USA Inc
Current assignee: Philip Morris USA Inc
Priority date: 2003-06-13
Filing date: 2004-06-14
Publication date: 2005-03-10
Also published as: CN1806080A; TW200507770A; KR101172076B1; MA27878A1; BRPI0411362B8; AU2004253467A1; PT1635658E; EP1635658A4; WO2005002370A2; DE602004010511T2; NO20060157L; EA008260B1; US9119421B2; CA2526424C; CA2527359A1; EP1635657A2; CN1805696A; JP2007511204A; AU2004246883A1; ZA200509578B

Abstract

A wrapper for a smoking article includes a web including cellulosic fibers and a catalyst modified web-filler incorporated into the web. The catalyst modified web-filler includes a web-filler supporting a nanoparticle carbon monoxide catalyst. The nanoparticle carbon monoxide catalyst can be a nanoparticle iron oxide catalyst. Also provided is a smoking article including a cigarette tobacco rod having a wrapper including a web, a web-filler, and a nanoparticle carbon monoxide catalyst, the web-filler supporting the nanoparticle catalyst. A method of making the wrapper and a method of making a smoking article utilizing the wrapper are also provided.

Description

BACKGROUND

This application claims priority under 35 USC §119 to U.S. Provisional Application No. 60/477,922 entitled CIGARETTE WRAPPER WITH CATALYTIC FILLER AND METHODS OF MAKING SAME and filed on Jun. 13, 2003, the entire content of which is hereby incorporated by reference.

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.

Iron and/or iron oxide has been described for use in tobacco products (see e.g., U.S. Pat. Nos. 4,197,861; 4,489,739 and 5,728,462). Iron oxide has been described as a coloring agent (e.g. U.S. Pat. Nos. 4,119,104; 4,195,645; 5,284,166) and as a bum regulator (e.g. U.S. Pat. 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. Pat. Nos. 6,095,152; 5,598,868; 5,129,408; 5,105,836 and 5,101,839).

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

A preferred embodiment of a smoking article comprises a cigarette tobacco rod having a wrapper, the wrapper including a web, a web-filler material, and a nanoparticle carbon monoxide catalyst, the web-filler material supporting the nanoparticle catalyst. Preferably, the nanoparticle carbon monoxide catalyst comprises a nanoparticle iron oxide catalyst supported by calcium carbonate.

A preferred method of making a smoking article comprises (i) optionally incorporating a nanoparticle carbon monoxide catalyst with a web-filler material utilized in production of a wrapper to form a catalyst modified web-filler, (ii) optionally making the wrapper, the wrapper including the catalyst modified web-filler, (iii) providing a cut filler comprising tobacco to a cigarette making machine, and (iv) placing the wrapper including the web-filler material supporting a nanoparticle carbon monoxide catalyst around the cut filler to form a tobacco rod portion of the smoking article. The method optionally includes calcining the catalyst modified web-filler prior to step (ii) and/or (v) placing a second wrapper around the tobacco rod portion.

A preferred embodiment of a wrapper for a smoking article comprises a paper web and a catalyst modified web-filler supported on the paper web, the catalyst modified web-filler including a nanoparticle carbon monoxide catalyst supported by a web-filler material.

Another preferred method of manufacturing cigarette paper comprises (i) supplying a catalyst modified web-filler and a cellulosic material to a head box in a forming section of a papermaking machine, the catalyst modified web-filler including a web-filler material supporting a nanoparticle carbon monoxide catalyst, (ii) depositing an aqueous slurry including the catalyst modified web-filler and the cellulosic material onto the forming section of the papermaking machine to form a base web with the catalyst modified web-filler distributed therein, and (iii) removing water from the base web so as to form an intermediate web. The method optionally includes calcining the catalyst modified web-filler prior to step (iii).

A further preferred method of manufacturing cigarette paper including a catalyst modified web-filler comprises (i) supplying a cellulosic material to a first head box of a forming section of a papermaking machine, (ii) depositing an aqueous slurry from the first head box onto the forming section of the papermaking machine so as to form a base web of the cellulosic material, (iii) distributing a catalyst modified web-filler on the base web, the catalyst modified web-filler comprising a web-filler material supporting a nanoparticle carbon monoxide catalyst, and (iv) removing water from the base web so as to form an intermediate web. The method optionally includes calcining the catalyst modified web-filler prior to step (iii) and/or distributing the catalyst modified web-filler within a fibrous network of the base web, wherein the layer forms a band, a stripe, or a lattice pattern on the intermediate web.

A preferred method of manufacturing a bilayer cigarette paper comprises (i) depositing a first layer of the bilayer cigarette paper from a first head box onto a wire of a papermaking machine, the first head box holding a first furnish composition (ii) depositing a second layer of the bilayer cigarette paper from a second head box onto a portion of the first layer, the second head box holding a second furnish composition, the second furnish composition including a catalyst modified web-filler comprising a web-filler material supporting a nanoparticle carbon monoxide catalyst, and (iii) removing water from the first layer and the second layer so as to form a single sheet of intermediate web. The method optionally includes calcining the catalyst modified web-filler.

A preferred method of manufacturing cigarette paper comprises (i) supplying a furnish including a cellulosic material to a first head box of a forming section of a papermaking machine, (ii) transporting a support web through the papermaking machine, (iii) depositing a catalyst modified web-filler onto the support web, the catalyst modified web-filler including a web-filler material supporting a nanoparticle carbon monoxide catalyst, (iv) depositing an aqueous slurry from the first head box onto the support web so as to form a base web of the cellulosic material with the support web embedded therein, (v) removing water from the base web so as to form a sheet, and (vi) taking up the sheet.

A preferred catalyst modified web-filler utilized in production of a wrapper for a smoking article comprises a web-filler material and a nanoparticle carbon monoxide catalyst supported on the web-filler material.

A preferred method of making a catalyst modified web-filler including a nanoparticle carbon monoxide catalyst supported on a web-filler material comprises (i) forming an aqueous slurry of the nanoparticle carbon monoxide catalyst and the web-filler material, (ii) optionally spreading the aqueous slurry on a support surface, and (iii) drying the aqueous slurry to evaporate water and to form a catalyst modified web-filler.

A further preferred method of making a catalyst modified web-filler including a nanoparticle carbon monoxide catalyst supported on a web-filler material comprises (i) precipitating the nanoparticle carbon monoxide catalyst from a liquid phase onto the web-filler material, (ii) removing at least a portion of the liquid phase, and (iii) drying the web-filler to evaporate a remainder of the liquid phase and to form the catalyst modified web-filler.

Another preferred method of making a catalyst modified web-filler including a nanoparticle carbon monoxide catalyst supported on a web-filler material comprises depositing the nanoparticle carbon monoxide catalyst from a vapor phase onto the web-filler material, wherein the nanoparticle carbon monoxide catalyst comprises FeOOH, α-Fe₂O₃, γ-Fe₂O₃, or mixtures thereof and the web-filler material is selected from the group consisting of CaCO₃, TiO₂, SiO₂, Al₂O₃, MgCO₃, MgO and Mg(OH)₂.

A preferred embodiment of a cigarette comprises a tobacco rod having a wrapper, the wrapper comprising a web of fibrous cellulosic material and a loading of web-filler material, at least some of the web-filler material comprising a mineral particle and a nanoparticle supported by the mineral particle.

A preferred embodiment of a furnish for use in a papermaking process comprises an aqueous slurry including a catalyst modified web-filler and a cellulosic material.

A preferred embodiment of a cigarette wrapper comprises a web having a web-filler material, at least some of the web-filler material comprising FeOOH.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1(a) shows an exemplary smoking article with a nanoparticle carbon monoxide catalyst supported on the web-filler material of the wrapper.FIG. 1(b) shows a magnified view of the wrapper.

FIG. 2(a) shows an exemplary smoking article with a nanoparticle carbon monoxide catalyst supported on the web-filler material of a first wrapper with a second outermost wrapper.FIG. 2(b) shows a magnified view of the first wrapper with a second outermost wrapper.

FIG. 3(a) shows an exemplary smoking article with a wrapper including a nanoparticle carbon monoxide catalyst. An inner web region of the wrapper contains catalyst-supporting web-filler material.FIG. 3(b) shows a magnified view of the wrapper.

FIG. 4 shows a schematic of a papermaking machine wherein the chalk box may contain a catalyst modified web-filler.

FIG. 5 illustrates one type of construction of a cigarette, which can be used with an electrical smoking device.

FIG. 6 is a perspective view of a cigarette having catalyst modified paper surrounding a fuel element.

FIG. 7 shows a cross section of the cigarette shown inFIG. 6.

FIG. 8 shows a cross section of a cigarette having catalyst modified wrapper centrally located in the form of a tube.

FIG. 9 shows conversion of CO to CO₂for nanoparticle iron oxide catalyst and nanoparticle iron oxide catalyst/CaCO₃mixture.

FIG. 10 shows the effect of calcination conditions on 30% loading of nanoparticle iron oxide catalyst on web-filler material on the conversion of CO to CO₂as a function of temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Catalytic paper, compositions of catalyst modified web-filler, cigarettes, methods for making smoking articles which involve the use of nanoparticle additives incorporated into the wrapper as web-filler material are capable of acting as an oxidant for the conversion of carbon monoxide to carbon dioxide and/or as a catalyst for the conversion of carbon monoxide to carbon dioxide. The nanoparticle additives reduce the amount of carbon monoxide in mainstream smoke.

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. The mainstream smoke contains smoke that is drawn in through both the lighted region, as well as through the cigarette paper wrapper.

Carbon monoxide (CO) oxidation catalysts, such as nanoparticle iron oxide catalysts of the preferred embodiments, can be incorporated into the web-filler material of a wrapper of smoking articles, such as cigarettes. Such a wrapper is used to assemble the smoking article and is consumed during smoking. While not wishing to be bound by theory, it is believed that during smoking, the incorporated nanoparticle catalyst catalyzes a constituent gas component in the gas stream, e.g., the carbon monoxide catalyst catalyzes CO to reduce the level of CO in the mainstream and sidestream cigarette smoke by reaction with oxygen (O₂) in the gas stream of the smoking article to form carbon dioxide (CO₂) following equation 1:
2 CO+O₂=2CO₂ Eq. 1
It is also believed that subsequent to the catalytic reaction, the catalyst may also act as an oxidant, e.g., can oxidize CO in the absence of oxygen in the gas stream to reduce the level of CO in the mainstream and/or sidestream smoke.

Referring toFIG. 1(a), a preferred embodiment of asmoking article100 has atobacco rod portion90 andfiltering tip92. Optionally, embodiments of thesmoking article100 can be practiced without afiltering tip92. Preferably, thetobacco rod portion90 comprises a column oftobacco102 that is enwrapped with a cigarette (tobacco)wrapper104. As shown in expanded view inFIG. 1(b), thewrapper104 includes a web of fibrouscellulosic material106 in which is dispersed particles of web-filler material108, such as calcium carbonate (CaCO₃). In practice, the web-filler material108 serves as an agent for determining the permeability of the wrapper104 (measured typically in units of CORESTA, which is defined as the amount of air, measured in cubic centimeters, that passes through one square centimeter of material in one minute at a pressure drop of 1.0 kilopascals) and also serves as a support for nanoparticles of carbon monoxide catalyst, preferably nanoparticles of iron oxide. If desired, thewrapper104 can optionally include a catalyst-free web-filler material110. The web-filler material is a filler material utilized in production for thewrapper104.

By “nanoparticles” is meant that the particles have an average particle diameter of less than a micron. The nanoparticle catalyst preferably has an average particle diameter of less than about 500 nm, further preferably less than about 300 to 400 nm, more preferably from 1 to 50 nm, even more preferably 1 to 10 nm, and most preferably less than about 5 nm. A bulk density of the nanoparticle catalyst is preferably less than 0.25 g/cc, preferably about 0.05 g/cc. The Brunauer, Emmett, and Teller (BET) surface area of preferred nanoparticle catalyst is about 20 m²/g to 400 m²/g, more preferably about 200 m²/g to about 300 m²/g. An example of a high temperature nanoparticle carbon monoxide catalyst includes nanoparticle iron oxide catalyst. A preferred nanoparticle iron oxide catalyst is NANOCAT® Superfine Iron Oxide, available from Mach I, Inc., of King of Prussia, Pa. The nanoparticle iron oxide catalyst can comprise FeOOH, α-Fe₂O₃, γ-Fe₂O₃, or mixtures thereof.

The nanoparticle carbon monoxide catalyst is incorporated into the wrapping paper by fixing the nanoparticle carbon monoxide catalyst to filler material utilized as web-filler material in the production of cigarette wrapping paper. The web-filler material can include an oxide, a carbonate, or a hydroxide of a Group II, Group III or Group IV metal, or the web-filler material can be selected from the group consisting of CaCO₃, TiO₂, silicates such as SiO₂, Al₂O₃, MgCO₃, MgO and Mg(OH)₂. In a preferred example, the web-filler material is CaCO₃or other conventional filler material used in cigarette paper manufacture. If desired, the wrapper paper can include web-filler material which does not include the nanoparticle carbon monoxide catalyst.

In a preferred embodiment of a smoking article, the nanoparticle iron oxide catalyst includes FeOOH, α-Fe₂O₃, γ-Fe₂O₃, or mixtures thereof. The catalyst modified web-filler preferably comprises nanoparticle iron oxide catalyst fixed to filler particles selected from the group consisting of CaCO₃, TiO₂, silicates such as SiO₂, Al₂O₃, MgCO₃, MgO and Mg(OH)₂. An average particle size of the catalyst modified paper web-filler is 0.1 to 10 microns, preferably less than or equal to 1.5 microns.

In another preferred embodiment, a total amount of nanoparticle carbon monoxide catalyst in the smoking article is an amount effective to convert at least some CO to CO₂. For cigarettes, a preferred amount of catalyst per cigarette is 1 to 100 mg, 1 to 50 mg or 50 to 100 mg, 2 to 25 mg or 25 to 50 mg, 1 to 15 mg or 15 to 40 mg, or 4 to 10 mg or 10 to 20 mg.

In one approach, the nanoparticle carbon monoxide catalyst, such as nanoparticle iron oxide catalyst, is supported by web-filler material, such as CaCO₃, by forming an aqueous slurry of the nanoparticle carbon monoxide catalyst and the web-filler material. The CaCO₃used in this process can be the same as the filler material used in the papermaking process, such as ALBACAR® 5970 commercially available from Specialty Minerals of Bethlehem, Pa. The slurry is spread, by, for example, spreading the slurry with a doctors blade, and then dried to evaporate the water leaving behind a solid. One method to dry the slurry includes exposure in air while heated by a heat source, such as radiation lamp at 75° C., although other methods such as vacuum filtering followed by drying can also be used.

The catalyst and filler can be provided in any desired amounts, e.g., 10 to 90% catalyst and 90 to 10% web-filler material. The dried slurry forms a powdery substance or a self-supporting solid mass, depending on the nanoparticle carbon monoxide catalyst loading of the slurry. For example, for a slurry containing less than about 50 to 60 wt. % catalyst loading of nanoparticle iron oxide on calcium carbonate, the slurry dries to a powdery substance; for a slurry containing greater than about 60 to 70 wt. % catalyst loading of the nanoparticle iron oxide on calcium carbonate, the slurry dries to a self-supporting solid mass. Prior to incorporating the catalyst modified web-filler into the wrapper, e.g., the web-filler material supporting nanoparticle carbon monoxide catalyst such as nanoparticle iron oxide catalyst/CaCO₃particles, the average particle size of the catalyst modified web-filler can be reduced to an average particle size of 0.1 to 10 microns, preferably about 1 micron or less. For example, the catalyst modified web-filler can be ball milled to form a powder by milling, for example, with 1 cm agate milling balls for 2 to 4 hours at 100 to 300 rpm. Ball milling may not be necessary where the slurry dries to a powdery substance. Subsequently, the catalyst modified web-filler, e.g., nanoparticle carbon monoxide catalyst/web-filler material, can be incorporated into the wrapper through a papermaking process. For example, the catalyst modified web-filler can be used as filler material in the papermaking processes. In a preferred embodiment, the level of web-filler material in the wrapper (both catalyst modified web-filler and/or web-filler material without catalyst), can be from 3 to 50%.

In another approach, particles of web-filler material, such as CaCO₃, support the nanoparticle carbon monoxide catalyst, such as nanoparticle iron oxide catalyst, by forming an aqueous slurry of the nanoparticle carbon monoxide catalyst and the web-filler material, drying the slurry to form the catalyst modified web-filler, and subsequently calcining the catalyst modified web-filler. The slurry is formed substantially as described above with respect to the first approach. After drying the slurry to form a self-supporting solid mass and ball milling to form a powder (if necessary to reduce the size of the catalyst modified web-filler), the catalyst modified web-filler is calcined by heating the catalyst modified web-filler to a suitable calcining temperature, e.g., up to 500° C., preferably from 200° C. to 400° C., for a suitable period of time such as from 1 to 3 hours, preferably 2 hours.

An exemplary process of making catalyst modified web filler comprising a 50/50 NANOCAT® iron oxide nanoparticle catalyst/CaCO₃mixture utilizing milling can be carried out as follows:

1. Mix 150 lb distilled water and 25 lb CaCO₃into 55 gallon stainless steel kettle.
2. Add slowly with continued mixing 25 lb NANOCAT® iron oxide nanoparticle catalyst.
3. Mix at maximum allowable rate for 2 hours after adding remaining 50 lb water.
4. Vacuum filter the slurry into filter cakes using Buchner funnel (25 cm) and flask (2000 ml).
5. Cut the filter cake into small 1 inch pieces and place them in frying pans (pan: 14″-10″-2″).
6. Freeze dry the filter cake.
7. Place pans in vacuum bell and vacuum dry at 110° C. for 24 hours.
8. Mill the powders using (Rotary Mill), Ceramic Ball and cylinder for 6 hours.
9. Calcine in air for 2 hours. at 300° C.

An exemplary process of making catalyst modified web filler comprising a 50/50 NANOCAT® iron oxide nanoparticle catalyst/CaCO₃mixture utilizing spray drying can be carried out as follows:

1. Prepare a catalyst mixture in water slurry by adding 1 part NANOCAT® iron oxide nanoparticle catalyst and 1 part of CaCO₃with 12 parts of water by weight. Stir the mixture to get a homogenous slurry (at least 30 minutes).
2. Feed the slurry to a spray drying machine.
3. Adjust air temperature to obtain dry powder (e.g., 175° C. air temperature).
4. Depending on the temperature used for drying calcination is optional. If carried out, calcination can be performed in air for 2 hours at 300° C.

The nanoparticle carbon monoxide catalyst can be fixed to the web-filler material by any suitable technique. For example, the nanoparticle carbon monoxide catalyst can be combined with the web-filler material by precipitating the nanoparticle iron oxide catalyst from a liquid phase onto the web-filler material or depositing the nanoparticle iron oxide catalyst from a vapor phase onto the web-filler material.

According to a preferred embodiment, the catalyst modified web-filler, e.g., the nanoparticle carbon monoxide catalyst/web-filler material, is incorporated in the wrapper through conventional papermaking processes. For example, the catalyst modified web-filler can be used as all or part of the filler material in the papermaking processes or can be distributed directly onto the wrapper, such as by spraying or coating onto wet or dry base web. In production of a smoking article such as a cigarette, the wrapper is wrapped around cut filler to form a tobacco rod portion of the smoking article by a cigarette making machine, which has previously been supplied or is continuously supplied with tobacco cut filler and one or more ribbons of wrapper.

Any suitable tobacco mixture may be used for the cut filler. Examples of suitable types of tobacco materials include flue-cured, Burley, Md. 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.

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 {fraction (1/10)} inch to about {fraction (1/20)} inch or even {fraction (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.

A wrapper can be any wrapping surrounding the cut filler, including wrappers containing flax, hemp, kenaf, esparto grass, rice straw, cellulose and so forth. Optional filler materials, flavor additives, and burning additives can be included. When supplied to the cigarette making machine, the wrapper can be supplied from a single bobbin in a continuous sheet (a monowrap) or from multiple bobbins (a multiwrap, such as a dual wrap from two bobbins). Further, the wrapper can have more than one layer in cross-section, such as in a bilayer paper as disclosed in commonly-owned U.S. Pat. No. 5,143,098, issued to Rogers, the entire content of which is herein incorporated by reference.

The papermaking process can be carried out using conventional paper making equipment. An exemplary method of manufacturing paper wrapper, e.g., cigarette paper including catalyst modified web-filler comprising nanoparticle carbon monoxide catalyst supported by a web-filler material, comprises supplying the catalyst modified web-filler and a cellulosic material to a papermaking machine. For example, an aqueous slurry (or “furnish”) including the catalyst modified web-filler and the cellulosic material can be supplied to a head box of a forming section of a Fourdrinier papermaking machine. The catalyst modified web-filler includes a nanoparticle carbon monoxide catalyst, e.g., nanoparticle iron oxide catalyst, supported by a web-filler material, e.g., CaCO₃. For example, the catalyst modified web-filler can include nanoparticle iron oxide catalyst/CaCO₃particles or any other suitable nanoparticle carbon monoxide catalyst and web-filler material, such as an oxide, a carbonate, or a hydroxide of a Group II, Group III or Group IV metal, CaCO₃, TiO₂, silicates such as SiO₂, Al₂O₃, MgCO₃, MgO and Mg(OH)₂. The aqueous slurry can be supplied to the head box by a plurality of conduits which communicate with a source, such as a storage tank.

The exemplary method can optionally include calcining the catalyst modified web-filler in a step prior to supplying the furnish to the papermaking machine.

The catalyst modified web-filler can be supplied to the papermaking process in any suitable form, such as in the form of an aqueous slurry or in the form of a dry powder to be slurried during the papermaking process prior to addition to the head box. For example, the catalyst modified web-filler can be produced on site as a slurry. The aqueous slurry containing the catalyst modified web-filler can be used immediately or stored for future use. In a preferred embodiment, the head box is supplied with an aqueous slurry of furnish containing the catalyst modified web-filler and cellulosic material used to form a web. Optionally, an aqueous slurry of furnish containing catalyst modified web-filler and an aqueous slurry furnish of cellulosic material without catalyst modified web-filler or with a different concentration of catalyst modified web-filler can be supplied to separate head boxes or multiple head boxes.

An exemplary method deposits the aqueous slurry from the head box onto a forming section so as to form a base web of the cellulosic material and the catalyst modified web-filler. For example, in a typical Fourdrinier machine, the forming section is a Fourdrinier wire which is arranged as an endless forming wire immediately below the head box. A slice defined in a lower portion of the head box adjacent to the endless wire permits the aqueous slurry of catalyst modified web-filler and cellulosic material from the head box to flow through the slice onto the top surface of the endless wire to form a wet base web. Optionally, the aqueous slurry can be deposited onto a support web that is retained within the paper. For example, a support web can be transported through the forming section of a papermaking machine and can be a foundation on which the aqueous slurry is deposited. The aqueous slurry dries on the Fourdrinier wire in the forming section to an intermediate web, which may still retain an aqueous component, and is further processed to form a paper sheet (e.g., finished web) with the support web embedded therein. The support web can be a conventional web, such as a flax support web, or can include a web with an incorporated catalytic component, such as a nanoparticle carbon monoxide catalyst. If the support web includes a catalytic component, the incorporated catalytic component can be supported on a web-filler material or can be directly supported on the support web without a web-filler material.

After depositing the aqueous slurry onto the forming section, water is removed from the wet base web to form an intermediate web and, with additional processing such as further drying and pressing if necessary, forms a sheet of cigarette paper (e.g., finished web). The cigarette paper is subsequently taken up for storage or use, e.g. the cigarette paper is coiled in a sheet or roll.

Referring toFIG. 4, acigarette papermaking machine200 includes ahead box202 operatively located at one end of aFourdrinier wire204, and source of feed stock slurry such as arun tank206 in communication with thehead box202. Thehead box202 can be one typically utilized in the papermaking industry for laying down cellulosic pulp upon theFourdrinier wire204. In the usual context, thehead box202 is communicated to therun tank206 through a plurality of conduits. Therun tank206 receives furnish from a furnishsupply218. Preferably, the feed stock from therun tank206 is a refined cellulosic pulp such as a refined flax or wood pulp as is the common practice in the cigarette papermaking industry. Preferably, a chalk tank228 (containing the catalyst modified web-filler described above) is communicated with therun tank206 so as to establish a desired “chalk” level in the slurry supplied to thehead box202.

TheFourdrinier wire204 carries the laid slurry pulp (e.g., base web) from thehead box202 along a path in the general direction of arrow A inFIG. 4, whereupon water is allowed to drain from the pulp through thewire204 by the influence of gravity and (optionally) at some locations with the assistance of

vacuum boxes

210,210′,210″ at various locations along theFourdrinier wire204 as is the established practice in the art of cigarette papermaking. At some point along theFourdrinier wire204, sufficient water is removed from the base web to establish what is commonly referred to as a dry line where the texture of the slurry transforms from one of a glossy, watery appearance to a surface appearance more approximating that of the finished base web (but in a wetted condition, e.g., an intermediate web). At and about the dry line, the moisture content of the pulp material is approximately 85 to 90%, which may vary depending upon operating conditions and the like.

Downstream of the dry line, theintermediate web212 is separated from theFourdrinier wire204 at acouch roll214. From there, theFourdrinier wire204 continues on the return loop of its endless path. Beyond thecouch roll214, theintermediate web212 continues on through the remainder of the papermaking system which further dries and presses theintermediate web212 and surface conditions theintermediate web212 to a desired final moisture content and texture to form a paper220 (e.g. finished web). Such drying apparatus are well known in the art of papermaking and may include dryingsection216 including drying felts, vacuum devices, rolls and/or presses, applied thermal energy, and the like.

Thecigarette making machine200 can optionally include more than one head box and/or more than one Fourdrinier wire with either separate or common furnish supply. Referring toFIG. 4, the optionalsecond head box202′, suitably integrated with a runtank and furnish supply, can lay slurry pulp onto the slurry pulp laid from thefirst head box202 and carried alongFourdrinier wire204. The second and/or additional head box can be supplied with catalyst modified web filler to a desired “chalk” level or can be free of catalyst modified web-filler, as desired based on the number of layers of slurry pulp to be deposited and/or the use of the wrapper formed from the papermaking process. Optionally and/or in the alternative, some or all of the catalyst modified web-filler may be introduced from the first,upstream head box202.

Referring toFIG. 4, the optionalsecond Fourdrinier wire204′, suitably integrated with ahead box202′ laying slurry pulp on theFourdrinier wire204′ and draining and drying equipment, can form a secondintermediate web212′. The secondintermediate web212′ can be separated from thesecond Fourdrinier wire204′ at asecond couch roll214′ and laid on the firstintermediate web212 from theFourdrinier wire204 to be processed into double layer paper. Multiple optional Fourdrinier wires can be employed to form multiple layer paper having any desired number of layers, such as three, four and so forth, up to ten to twelve layers.

Other papermaking processes can be used to make a wrapper with a nanoparticle carbon monoxide catalyst. For example, a laminated, bilayer or multilayer wrapper can be made. Examples of bilayer and multilayer wrappers are disclosed in commonly-owned U.S. Pat. No. 5,143,098, issued to Rogers, the entire content of which is herein incorporated by reference. In an embodiment of a bilayer or multilayer wrapper including a nanoparticle carbon monoxide catalyst, at least one of a radially inner layer and/or a radially outer layer can include the nanoparticle carbon monoxide catalyst as described in embodiments herein. Preferably, for cosmetic appearance due to darkening of paper containing catalyst modified web-filler with iron oxide as the nanoparticle catalyst, a radially innermost layer of the multilayer paper adjacent the cut filler in the smoking article is the portion of the multilayer wrapper that includes the web-filler material that supports a nanoparticle carbon monoxide catalyst.

The bilayer or multilayer single sheet wrapper may be made using ordinary paper furnish such as pulped wood, flax fibers, or any standard cellulosic fiber. Preferably flax fibers are used. Different fillers, including different catalytic fillers such as the catalyst modified web-filler described herein, or different fibers may be used for each layer and may be contained in different head boxes, as disclosed in U.S. Pat. No. 5,143,098, issued to Rogers, the entire content of which is herein incorporated by reference. For example, a first head box can hold the materials for a wrapper that includes the nanoparticle carbon monoxide catalyst and a second head box can hold the materials for a conventional wrapper.

Additional examples of papermaking processes include the method for making banded smoking article wrappers disclosed in commonly-owned U.S. Pat. No. 5,342,484, the entire content of which is herein incorporated by reference, and the method for producing paper having a plurality of regions of variable basis weight in the cross direction disclosed in commonly-owned U.S. Pat. Nos. 5,474,095 and 5,997,691, the entire contents of which are herein incorporated by reference. Further and in the alternative to incorporating nanoparticle catalyst into the web of the wrapper in a papermaking process, it is contemplated that the paper (wrapper) can be manufactured first and the nanoparticle catalyst placed onto the surface. For example, the nanoparticle can be distributed directly onto the wrapper, such as by spraying or coating onto wet base web, the intermediate web or the finished web. Further, the nanoparticle can be coated and/or printed (text or images) within the papermaking process or in a separate application of nanoparticle catalyst on-line during manufacture of the cigarette. The amount of printing and/or the amount of catalyst can be varied to adjust the level of CO reduction. The use of retention aids is also contemplated.

The catalyst-containing paper can be used as a wrapper for conventional cigarettes or non-conventional cigarettes such as cigarettes for electrical smoking systems described in commonly-assigned U.S. Pat. Nos. 6,026,820; 5,988,176; 5,915,387; 5,692,526; 5,692,525; 5,666,976; 5,499,636 and 5,388,594 or non-traditional types of cigarettes having a fuel rod such as are described in commonly-assigned U.S. Pat. No. 5,345,951.

FIG. 5 illustrates one type of construction of acigarette300, which can be used with an electrical smoking device. As shown, thecigarette300 includes atobacco rod360 and afilter portion362 joined by tippingpaper364. Thefilter portion362 preferably contains a tubular free-flow filter element302 and amouthpiece filter plug304. The free-flow filter element302 andmouthpiece filter plug304 may be joined together as a combinedplug310 withplug wrap312. Thetobacco rod360 can have various forms incorporating one or more of the following items: anoverwrap371, another tubular free-flow filter element374, acylindrical tobacco plug380 preferably wrapped in aplug wrap384, atobacco web366 comprising abase web368, and avoid space391. The catalyst modified web-filler is preferably incorporated into theoverwrap371, but in addition or in the alternative, could be incorporated into any one or more of the plug wrap384 or a component or components of thetobacco web366, preferably the basedweb368 thereof.

FIG. 6 illustrates acigarette410 construction having afuel element411 as described in U.S. Pat. No. 5,345,951, the disclosure of which is hereby incorporated by reference. Thecigarette410 includes thefuel element411 and anexpansion tube412 overwrapped bycigarette wrapping paper414, and afilter element413 attached by tippingpaper405. With reference toFIG. 7, thefuel element411 includes aheat source420 and aflavor bed421 which releases flavored vapors and gases when contacted by hot gases flowing through one or more longitudinal passages in the heat source. The vapors pass into theexpansion chamber412 and then tomouthpiece element413. The heat source may contain pure substantially carbon and optionally catalysts or burn additives. One or more layers of catalyst modifiedpaper418 surrounding theheat source420 can be used to reduce CO produced by theheat source420. Alternatively, or in addition thereto, catalyst modified paper can be provided downstream of theheat source420, e.g., catalyst modified paper can be dispersed between the heat source and theflavor bed421 or in theflavor bed421.Flavor bed421 can include any material that releases desirable flavors, e.g., tobacco filler or inert substrate on which flavor forming compounds have been deposited.

Thefuel element411 is housed in a composite sleeve having a radiant energy reflector sleeve422 (e.g., perforated metallized paper) and optional inner sleeve423 (e.g., perforated metallized paper). Theinner sleeve422 can be folded in to form alip424 at the upstream end thereof to hold the heat source suspended away from the interior wall of thereflector sleeve422 with an annular space therebetween.Flavor bed421 is held withininner sleeve423. Thewrapper414 which holds the fuel element andexpansion chamber412 together preferably has sufficient porosity to allow air to be admitted through thepaper414 and support combustion of the heat source. Thefuel element411 also includes areflective end cap415 with one ormore openings416 to allow air into thefuel element411. Methods to make smoking articles can include dual paper wrappers, e.g., an inner wrapper and an outer wrapper. If desired, the catalyst modified paper can be used at other locations and/or for any of the paper layers of the cigarette shown inFIGS. 6 and 7. Further, while one embodiment of a fuel element cigarette is shown inFIGS. 6 and 7, the catalyst modified paper disclosed herein can be used to surround the fuel element and/or in place of paper layers in other fuel element cigarette arrangements than shown inFIGS. 6 and 7.

FIG. 8 illustrates acigarette500 having aconcentric tobacco rod510 that includes an inner tube or sheath ofcigarette wrapper515 whose web-filler material supports a nanoparticle carbon monoxide catalyst, such as an iron oxide and/or any other oxidation catalyst described herein. As shown, thecigarette500 comprises afilter505 and atobacco rod510 which are attached to one another with tippingpaper511 in a conventional fashion. Thetobacco rod510 is a “concentric core” or “coaxial” layout that can be produced on a Hauni Baby rod making machine available from Hauni Machinenbau AG of Hamburg, Gemany. Aninner core region512 is defined by theinner wrapper515, which is surrounded by tobaccocut filler material520. Anouter cigarette wrapper525 extends along the outside of thetobacco rod510. Thefilter505 can comprise one or more plugs of cellulose tow and optionally could include an adsorbent such as carbon. In this embodiment, any coloration in theinner wrapper515 is hidden from view.

Thecentral core region512 can be hollow and/or can be partially or wholly filled with tobacco cut filler and is preferably approximately 2-5 mm in diameter, more preferably 2-3 mm in diameter. In one alternative, theinner wrapper515 can be constructed in a layered arrangement with at least one of the layers formed of catalytic paper wherein a nanoparticle catalyst, such as nanoparticle iron oxide, is supported on a web-filler material, such a CaCO₃. Optionally, theouter wrapper525 may be constructed similarly to include a nanocatalyst.

Optionally, the central tube can be constructed such that heat applied to an end of the tube will cause the end portion of the tube to collapse upon itself and seal off (or close) the end of the tube. The collapsing feature can be achieved by a number of different embodiments of the central tube. In an alternative where the central tube collapses when heat is applied, thecentral tube515 can be constructed in a layer arrangement such that an outer or top layer is made from a material having a higher thermal expansion coefficient than an inner or bottom layer. As a result, when the end of the tube is heated, the difference in thermal expansion coefficient between the two layers will result in the end portion of the tube collapsing upon itself and, optionally, sealing off the end. The layers of thecentral tube515 can be constructed from different types of paper having the different thermal expansion coefficients. The difference in thermal expansion coefficients of the layers can be a result of the types of paper having different proportions of cellulose and/or different binders. One or more of the different types of paper can be a catalytic paper wherein a nanoparticle catalyst, such as nanoparticle iron oxide, is supported on a web-filler material, such as CaCO₃. Alternatively, other polymeric, starch or cellulosic based films can be used for thecentral tube515, anyone of which can include the catalyst modified web-filler.

If desired, the catalytic paper can be used at other locations and/or for any of the paper layers of the cigarette shown inFIG. 8. Further, while one embodiment of a cigarette with a porous heat transfer tube is shown inFIG. 8, the catalytic paper disclosed herein can be used to surround the tobacco rod portion, or can be used as the wrapper, be incorporated into a cellulosic component of the filter portion, and/or in place of paper layers in other porous heat transfer tube cigarette arrangements than shown inFIG. 8.

Referring now to the embodiment of FIGS.2(a) and2(b), the inner wrapper and the outer wrapper are individual wrappers formed in separate papermaking processes and later wrapped around tobacco cut filler to from a cigarette tobacco rod. The inner wrapper, the outer wrapper or both wrappers can include the catalyst modified web-filler, e.g., the nanoparticle carbon monoxide catalyst supported by a web-filler material. In examples where both wrappers include a catalyst modified web-filler, the specific nanoparticle carbon monoxide catalyst and the catalyst loading in each wrapper can be the same or different. In some embodiments, the addition of a catalyst modified web-filler can discolor the wrapper, e.g., the wrapper becomes non-white or brown. For aesthetic reasons, an outer wrapper that is a conventional color, e.g., white, can be placed around the inner wrapper. Both the inner wrapper and the outer wrapper can be selected to give a desired smoking article performance with respect to smoking article properties, such as puff count, tar, burn rate, and ash appearance. Accordingly and as shown and described, for example, with reference to FIGS.2(a) and2(b), preferred embodiments of smoking articles and methods of making smoking articles can include a tobacco rod portion of a cigarette with a nanoparticle carbon monoxide catalyst supported on the web-filler material of a first wrapper with a second outermost wrapper, which does not contain the catalyst modified web-filler. Also with reference toFIG. 8, the central tube formed with catalytic paper can satisfy aesthetics by placing the catalytic paper in the interior of the smoking article.

An exemplary wrapper for a smoking article comprises a paper web including cellulosic fibers and a catalyst modified web-filler incorporated into the paper web. The catalyst modified web-filler includes a web-filler material supporting a nanoparticle carbon monoxide catalyst.

The wrapper can be any suitable conventional wrapper. For example, a preferred wrapper can have a basis weight of from about 18 g/m²to about 60 g/m²and a permeability of from about 5 CORESTA units to about 80 CORESTA units. More preferably, the wrapper has a basis weight from about 30 g/m²to about 45 g/m²and the permeability is about 30 to 35 CORESTA units. However, any suitable basis weight for the wrapper can be selected. For example, a higher basis weight, e.g., 35 to 45 g/m², can support a higher loading of catalyst. If a lower catalyst loading is selected, then a lower basis weight wrapper can be used.

Other permeabilities of the wrapper (as measured by CORESTA units) can be selected based on the application and location of the wrapper. For example, in multilayer wrappers the permeability of a first layer can be up to 30,000 CORESTA units, although a permeability that is lower or higher can be utilized. Thickness of single-layer wrapper can preferably be from 15 to 100 microns, more preferably from 20 to 50 microns. Additional layers in a multilayer wrapper can be from 0.1 to 10 times the permeability of the first layer and can have a thickness of from 0.1 to 2 times the thickness of the first layer. Both the permeability and the thickness of the first layer and the second layer can be selected to achieve a desired total air permeability and total thickness for the smoking article.

Nanoparticle carbon monoxide catalyst loaded wrappers were produced and compared to wrappers without the nanoparticle carbon monoxide catalyst. Table 1 summarizes selected properties of a control paper (designated X) and a wrapper paper with a catalyst modified web-filler, e.g., nanoparticle carbon monoxide catalyst/support material (designated Y) as a filler material. The nanoparticle carbon monoxide catalyst was nanoparticle iron oxide catalyst in the form of iron oxide and was supported on the CaCO₃web-filler material at 25 wt. % catalyst loading. The nanoparticle carbon monoxide catalyst/web-filler material was formed as described herein from a slurry without calcining.

TABLE 1


Selected Properties of Wrapper with Catalyst Modified Web-filler as
Compared to Paper Wrapper Without Catalyst Modified Web-filler

		Catalyst	Catalyst
		Loading in	Modified
		Catalyst	Web-filler	Total
		Modified	Loading in	Catalyst
		Web-filler	Wrapper	Loading
		(wt. %	(% paper	in	Basis	Permeability
	Web-Filler	catalyst	filler	Sample	Weight	(CORESTA
Sample	Material	loading)	loading)	(wt. %)	(g/m²)	Units)

X	CaCO₃	—	30	—	45 ± 1	33 ± 5
	(ALBACAR ® 5970)
Y	nanoparticle	25	30	7.5	45 ± 1	33 ± 5
	iron oxide
	catalyst/CaCO³
	particles

The nanoparticle carbon monoxide catalyst to web-filler material ratio can be varied by subjecting a slurry of nanoparticle carbon monoxide catalyst/web-filler material, e.g., the slurry of nanoparticle iron oxide catalyst/CaCO₃or other catalyst modified web-filler, to calcining at different temperatures for different time periods. Also, the mixing conditions of the slurry can be selected to achieve a desired distribution of the web-filler material with the nanoparticle carbon monoxide catalyst. For example, the speed, time, blade type, and temperature can all be adjusted to achieve a desired uniformity of the nanoparticle carbon monoxide catalyst to web-filler material ratio. Alternatively, the nanoparticle carbon monoxide catalyst/web-filler material can be co-precipitated to form a particle or a powder, e.g., chemical precipitation methods can be used, such as precipitating CaCO₃from CaCl₃by adding a carbonate, such as Na₂CO₃. Gas phase precipitation methods to deposit nanoparticle carbon monoxide catalyst in-situ onto a web-filler material can also be employed. For example, vapor deposition or spray techniques can be used.

While not wishing to be bound by theory, it appears that CO catalyst in the form of nanoparticle iron oxide catalyst, such as NANOCAT® Superfine Iron Oxide, starts to convert CO to CO₂at a temperature above 150° C., preferably at a temperature above 400° C. Additionally, the conversion rate of CO to CO₂by nanoparticle iron oxide catalyst is enhanced by the rapid and efficient transport of CO to the region of the nanoparticle carbon monoxide catalyst and CO₂away from the region of the catalyst, e.g., air flow within the smoking article. Together, the operating temperature and the air flow within the smoking article can affect the operation of the nanoparticle carbon monoxide catalyst.

During the puffing process, CO in mainstream smoke flows toward the filter end of a smoking article. As carbon monoxide travels within the smoking article, oxygen diffuses into and carbon monoxide diffuses out of the smoking article through the paper wrapper. After a typical 2-second puff of a cigarette, CO is concentrated in the periphery of the cigarette, e.g., near the cigarette wrapper, in front of the burn zone. The oxygen concentration is high in the same region as high CO concentration due to diffusion of O₂from outside the cigarette. Airflow into the tobacco rod is largest near the burn zone on the periphery of the smoking article and is approximately commensurate with the gradient of temperature, e.g, larger airflow is associated with higher temperature gradients. Thus, the highest airflow is also the region of highest temperature gradient. For example in a typical smoking article, the highest temperature gradient is from >850-900° C. at the periphery of the smoking article at the burn zone to approximately 300° C. toward the center of the smoking article. The temperature further drops to near ambient near the filter end. Furthermore, the temperature drop at the lit end is very fast and within a couple of mm behind the burn zone in the axial direction the temperature drops from 900° C. to 200° C. Further information on airflow patterns, the formation of constituents in cigarettes during smoking and smoke formation and delivery can be found in Richard R. Baker, “Mechanism of Smoke Formation and Delivery”, Recent Advances in Tobacco Science, vol. 6, pp. 184-224, (1980) and Richard R. Baker, “Variation of the Gas Formation Regions within a Cigarette Combustion Coal during the Smoking Cycle”, Beitrage zur Tabakforschung International, vol. 11, no. 1, pp. 1-17, (1981), the contents of both are incorporated herein by reference.

The position and quantity of nanoparticle carbon monoxide catalyst in the wrapper can be selected as a function of the temperature and airflow characteristics exhibited in a burning cigarette in order to adjust, e.g., increase, decrease, minimize or maximize, the conversion rate of CO to CO₂, by depositing aqueous slurry with catalyst modified web-filler selectively during the papermaking process. For example, the solid coal in a smoking article reaches the peak temperature of greater than 850-900° C. at about the burn zone, e.g., within about 2 mm of the burn zone, and is at 300° C. to 400° C. within 2 to 3 mm of the burn zone. Thus, a nanoparticle carbon monoxide catalyst can be selected that operates in a given temperature range, and a wrapper can be manufactured in which the catalyst modified web-filler, e.g., nanoparticle iron oxide catalyst/CaCO₃, can be incorporated in those portions of the wrapper that are predicted to coincide with the appropriate temperature for operation of the catalyst. The selective incorporation of catalyst modified web-filler can be realized, for example, by using different head boxes containing the selected concentration of catalyst modified web-filler and/or locating head boxes with different concentrations of catalyst modified web-filler at selected positions in the papermaking process corresponding to selected locations of the catalytic paper to be produced.

For example, a preferred nanoparticle carbon monoxide catalyst for use in a wrapper for a smoking article is catalytically active at temperatures as low as ambient temperature and preferably does not deactivate even at temperatures as high as 900° C. The preferred nanoparticle carbon monoxide catalyst can be positioned along the entire axial length of the anticipated burn zone, e.g., not only at the filter end of the smoking article, and can be catalytically active from the lit end to the filter end during use. The axial distribution of the nanoparticle carbon monoxide catalyst provides sufficient contact time between the mainstream smoke and the nanoparticle carbon monoxide catalyst for the CO to be converted to CO₂. An example of a preferred nanoparticle carbon monoxide catalyst includes NANOCAT® Superfine Iron Oxide, which starts to convert CO to CO₂at a temperature above 150° C.

In a further example, a mixed catalyst, e.g., a catalyst that is a combination of individual catalyst compositions that each operate at a different temperature range or overlapping temperature ranges, can be used to broaden the temperature range at which conversion of CO to CO₂can occur and to increase the operating period of the catalyst as the smoking article burns. For example, a mixed catalyst may operate at both above about 500° C. and at 300° C. to 400° C. and thus converts CO to CO₂both at the burn zone and behind the burn zone, effectively increasing the conversion time and the area of the wrapper at which conversion occurs.

Although the catalyst is described herein as having an operating temperature, the term operating temperature refers to the preferred temperature for conversion of CO to CO₂. The catalyst may still operate to convert CO to CO₂outside the described temperature range, but the conversion rate may affected.

Samples of wrapper with CaCO₃web-filler and wrapper with catalyst modified web-filler, e.g., nanoparticle iron oxide catalyst/CaCO₃web-filler material, were produced and tested in smoking article configurations under standard FTC testing conditions. The nanoparticle iron oxide catalyst was NANOCAT® Superfine Iron Oxide. CaCO₃supported the nanoparticle iron oxide catalyst and was produced by a slurry method without calcining. Nanoparticle iron oxide catalyst loadings in the catalyst modified web-filler of from 15 wt. % to 50 wt. % were tested and compared to a control sample without nanoparticle iron oxide catalyst. Characteristics of sheets containing 30% web-filler loading (either CaCO₃web-filler material or catalyst modified web-filler) at two different basis weights of paper (35 g/m²and 45 g/m²) were investigated. The smoking article configuration included a rod length of 63 mm having a diameter of about 8 mm and a full flavor filter having a length of 21 mm. Each sample had the same conventional tobacco blend. In eachcategory20 cigarettes were smoked. The average results for mainstream smoke are summarized in Table 2.

TABLE 2


Average Results for Mainstream Smoke

Catalyst
Loading					% reduction
in Web-	Tar				in CO:Tar
Filler	(mg/	Puff Ct.	CO	CO:Tar	compared to
(wt. %)	Cig.)	(puff/Cig.)	(mg/Cig.)	Ratio	Control

45 g/m²
Samples
I	0	17.7	8.1	18.3	1.03	control
II	15	15.6	8.1	12.3	0.79	24
III	25	15.9	8.2	11.6	0.73	29
IV	50	14.4	8.7	9.9	0.69	34
35 g/m²
Samples
i	0	18.1	8.2	16.6	0.92	Control
iii	25	17.0	8.2	11.6	0.68	26
iv	50	14.5	8.7	9.5	0.66	29

The results in Table 2 indicate that there is an increasing reduction in CO:Tar ratio in the test cigarettes made with wrapper having catalyst modified web-filler as compared to the control cigarette. The percent reduction in CO:Tar ratio increases from 24% to 34% as the catalyst increases from 15 wt. % to 50 wt. % catalyst loading in the catalyst modified web-filler. Coincident to the reduction in CO:Tar, there is little variation (e.g., <1 or <10%) in the puff count. Further, the CO:Tar ratio decreased indicating correlation between the CO catalyst and the reduction in CO. When used in paper, the nanoparticle catalyst was more selective to CO and CO was reduced by a greater proportion than Tar. Advantageously, the impact of the CO catalysis upon tar level is reduced. The amount of catalyst used in the wrapper for each cigarette is about 4 to 8 mg/cigarette, depending on the loading levels.

Table 3 illustrates comparative test results of conventional cigarette designs hand made without a filter. Sample A was wrapped in a handmade 45 g/m²wrapper without catalyst modified web-filler and Sample I was wrapped in a handmade 45 g/m²wrapper having embedded catalyst modified web-filler, e.g., nanoparticle iron oxide catalyst fixed to CaCO₃support material. In the Sample I shown, the embedded nanoparticle iron oxide catalyst loading in the catalyst modified web-filler was 30 wt. % catalyst loading of NANOCAT®Superfine Iron Oxide with respect to the catalyst modified web-filler (about 9 wt. % catalyst loading with respect to the wrapper). The smoking article configuration included a rod length of 63 mm having a diameter of about 8 mm and a full flavor filter having a length of 21 mm. Each sample had the same conventional tobacco blend. The two sample cigarettes were then tested under the standard FTC conditions. Table 3 shows the change in properties of the two cigarettes.

TABLE 3


Comparative Test Results of Select Properties of Designated Cigarettes

		Total Particulate
		Matter (TPM)		CO		CO/
Sample	Puff	(mg)	TPM/puff	(mg)	CO/puff	TPM

Sample A	7.5	50.5	6.7	21.3	2.8	0.42
Sample I	8.3	48.7	5.9	13.5	1.6	0.28
change	+10.3	−3.6	−11.9	−36.6	−42.9	−33.3
(%)

FIG. 9 shows the conversation of CO to CO₂for a 50 mg sample (A) of NANOCAT® Superfine Iron Oxide (Trace i) and a sample (B) of 100 mg mixture of 25 wt. % catalyst loading of NANOCAT® Superfine Iron Oxide and CaCO₃(Trace ii). InFIG. 9, the conversion of CO to CO₂was investigated as a function of temperature in a flow tube reactor containing the samples (A) and (B) and an atmosphere with 3.7% O₂and 22% CO. The flow rate was 1000 ml/minute and the heating rate was 12° C./minute. For both the sample of NANOCAT® Superfine Iron Oxide and the mixture of NANOCAT® Superfine Iron Oxide and CaCO₃the onset of conversion occurs at about 100-125° C., indicating that the activation temperature of NANOCAT® Superfine Iron Oxide is not substantially affected by the CaCO₃.

A calcination process was also investigated for heat treating the NANOCAT® Superfine Iron Oxide on CaCO₃. Calcination is achieved by taking catalysts from the slurry method and heating them in the presence of air for an extended duration. For example, calcining at a temperature of no more than 500° C., preferably from 200° C. to 400° C., for a period of time of from 1 to 3 hours, e.g., 2 hours. Without being held to any one theory, it is believed that a calcination step can improve the bonding between the catalyst and the web-filler material and that during the calcination step the catalyst surface is improved due to evaporation of bound water molecules.

FIG. 10 shows the effect of calcination of NANOCAT® Superfine Iron Oxide and CaCO₃at a 30 wt. % catalyst loading in the catalyst modified web-filler. The conversion of CO to CO₂was determined as a function of temperature in a flow tube reactor containing catalyst modified web-filler. The atmosphere included 20.6% O₂and 3.4% CO and the atmosphere flow rate was 1000 ml/minute. The heating rate was 12° C./minute. Five traces are presented inFIG. 10. Trace A represents results of the catalyst modified web-filler without calcination, Trace B represents a sample of catalyst modified web-filler calcined at 200° C. for 2 hours, Trace C represents a sample of catalyst modified web-filler calcined at 300° C. for 2 hours, Trace D represents a sample of catalyst modified web-filler calcined 400° C. for 2 hours, and Trace E represents a sample of catalyst modified web-filler calcined at 500° C. for 1 hour. As indicated by an increase in conversion to CO₂, the onset temperature and the conversion percentage is substantially unchanged between the four samples. At temperatures above about 400° C., all calcined samples had higher conversion percentages than the noncalcined sample (Trace A).

Based on the CO to CO₂conversion percent, in the exemplary embodiment the nanoparticle carbon monoxide catalyst is present in an amount effective to convert at least 10% of carbon monoxide to carbon dioxide at a temperature of at least 400° C. to about 900° C. Preferably, the nanoparticle carbon monoxide catalyst converts at least 25% of carbon monoxide to carbon dioxide at a temperature of at least 500° C. More preferably, the nanoparticle carbon monoxide catalyst converts at least 50% of carbon monoxide to carbon dioxide at a temperature of at least 700° C.

Following the investigation into the effect of calcination, the surface area of the supported catalyst was investigated using BET surface area measurements. Three samples were tested:Sample 1 was as-prepared 30 wt. % catalyst loaded NANOCAT® Superfine Iron Oxide and CaCO₃, Sample 2 was 30 wt. % catalyst loaded NANOCAT® Superfine Iron Oxide and CaCO₃calcined at 400° C. for 2 hours, and sample 3 was CaCO₃formed by chemical precipitation (so called precipitated calcium carbonate (PCC), as opposed to natural ground CaCO₃, so called ground calcium carbonate (GCC)) and was used as a control sample. All samples were outgassed at 150° C. for 1 hour prior to the BET measurement.

It was observed that the BET surface areas for the samples with NANOCAT® Superfine Iron Oxide, e.g.,Samples1 and2, had approximately the same BET surface areas before and after calcination, e.g., within 10%, and that the BET surface area of these samples were approximately an order of magnitude greater than the BET surface area of samples without the nanoparticle carbon monoxide catalyst, e.g., Sample 3. Thus,Samples1 and2 indicate that calcining does not have an adverse effect on the catalyst surface area available for conversion of CO to CO₂.

In another exemplary embodiment, a low temperature nanoparticle carbon monoxide catalyst can be used, either alone or in combination with another catalyst, as a nanoparticle carbon monoxide catalyst. Low temperature and even room temperature catalysts can extend the effective region of the reaction zone for CO to CO₂conversion to the whole cigarette, provided the temperature rise due to the exothermic reaction remains below the ignition temperature of the wrapper.

An example of a suitable low temperature nanoparticle carbon monoxide catalyst includes ceria-based catalysts. Ceria-based catalysts can oxidize CO at near-ambient temperatures. A suitable ceria-based catalyst is disclosed in commonly-owned U.S. patent application Ser. No. 10/314,449 entitled “CERIA-BASED CATALYSTS FOR CO OXIDATION AT NEAR-AMBIENT TEMPERATURES” and filed on Dec. 9, 2002, the entire contents of which are herein incorporated by reference. Another example of a low temperature nanoparticle carbon monoxide catalyst includes nanoparticle additives capable of acting as an oxidant for the conversion of CO. A suitable nanoparticle additive includes a metal oxide, such as Fe₂O₃, CuO, CeO₂, or Ce₂O₃, a doped metal oxide, such as Y₂O₃doped with zirconium or Mn₂O₃doped with palladium, or mixtures thereof as disclosed in commonly-owned U.S. patent application Ser. No. 10/286,968 entitled “OXIDANT/CATALYST NANOPARTICLES TO REDUCE TOBACCO SMOKE CONSTITUENTS SUCH AS CARBON MONOXIDE” and filed on Nov. 4, 2002, the entire contents of which are herein incorporated by reference.

In addition, any of the wrappers, smoking articles or methods described herein can include additional additives conventionally used in wrappers for smoking articles. These additives can include, for example, additives to control the appearance, e.g., color, of the wrapper, additives to control the burn rate of the wrapper, and/or additives to result in a desired ash appearance and/or web-fillers used in cigarette paper.

The method can be implemented in an easy to use and economical manner as explained herein. The catalyst modified web-filler can be used to: (1) remove carbon monoxide in the mainstream cigarette smoke or sidestream smoke of smoking articles; (2) reduce or eliminate particle entrainment since the catalyst is embedded in the wrapper; (3) remove a target constituent, such as carbon monoxide, highly selectively since the catalyst in the wrapper only catalyzes those gases that are near the wrapper and/or for which the catalyst has an affinity; and/or (4) easily implement in large scale production through the papermaking process.

The tobacco column preferably comprises cut filler of a blend of tobaccos typical of the industry, including blends comprising bright, burley and oriental tobaccos and other blend components, including traditional cigarette flavors. In the preferred embodiment, the shredded tobacco (cut filler) of the tobacco column comprises a blend of bright, burley and oriental tobaccos with or without inclusion of reconstituted tobaccos or any after cut flavorings. Optionally, an expanded tobacco component might be included in the blend to adjust rod density, and flavors may be added. Optionally, a single variety of the aforementioned tobaccos may be used instead of a blend.

Although the present invention has been described in connection with exemplary embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.