In the description that follows reference is made to certain structures and methods, however, such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art.
Smoking articles, such as cigarettes or cigars, produce both mainstream smoke during a puff and sidestream smoke during static burning. One constituent of both mainstream smoke and sidestream smoke is carbon monoxide (CO). The reduction of carbon monoxide in smoke is desirable.
Catalysts, sorbents, and/or oxidants for smoking articles are disclosed in the following: U.S. Pat. No. 6,371,127 issued to Snider et al., U.S. Pat. No. 6,286,516 issued to Bowen et al., U.S. Pat. No. 6,138,684 issued to Yamazaki et al., U.S. Pat. No. 5,671,758 issued to Rongved, U.S. Pat. No. 5,386,838 issued to Quincy, III et al., U.S. Pat. No. 5,211,684 issued to Shannon et al., U.S. Pat. No. 4,744,374 issued to Deffeves et al., U.S. Pat. No. 4,453,553 issued to Cohn, U.S. Pat. No. 4,450,847 issued to Owens, U.S. Pat. No. 4,182,348 issued to Seehofer et al., U.S. Pat. No. 4,108,151 issued to Martin et al., U.S. Pat. No. 3,807,416, and U.S. Pat. No. 3,720,214. Published applications WO 02/24005, WO 87/06104, WO 00/40104 and U.S. Patent Application Publication Nos. 2002/0002979 A1, 2003/0037792 A1 and 2002/0062834 A1 also refer to catalysts, sorbents, and/or oxidants.
Iron and/or iron oxide has been described for use in tobacco products (see e.g., U.S. 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 burn 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.
A preferred embodiment of a smoking article comprises a cigarette tobacco rod including a wrapper surrounding a tobacco column, the tobacco column containing a cut filler and a catalytic paper including a web, a web-filler material, and a nanoparticle carbon monoxide catalyst, the web-filler material supporting said 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 supporting a nanoparticle carbon monoxide catalyst on a web-filler material to form a catalyst modified web-filler, (ii) making catalytic paper including the catalyst modified web-filler, (iii) forming a tobacco column, the tobacco column including the catalytic paper and a cut filler, (iv) placing a wrapper around the tobacco column to form the smoking article.
A preferred smokeable material for a cigarette tobacco rod comprises shredded tobacco and a catalytic paper, the catalytic paper including a web, a web-filler material, and a catalyst modified web-filler, the catalyst modified web-filler including a nanoparticle carbon monoxide catalyst supported on the web-filler material.
A preferred method of making a smokeable material for a tobacco rod comprises adding catalytic paper to shredded tobacco, the catalytic paper including a web, a web-filler material and a nanoparticle carbon monoxide catalyst supported on the web-filler material.
The following detailed description makes reference to the accompanying drawings in which like numerals designate like elements and in which:
Catalytic paper in cut filler compositions and smoking articles and methods for making smoking articles which involve the use of shredded paper with nanoparticle additives in cut filler compositions 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 tobacco cut filler formed into tobacco rods for smoking articles, such as cigarettes. Subsequently, the smoking article 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:
2CO+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.
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 composition of tobacco by directly mixing the nanoparticle carbon monoxide catalyst with the tobacco cut filler and/or by incorporating the nanoparticle carbon monoxide catalyst into a web-filler material of a catalytic paper, reducing the size of the catalytic paper (by, for example, shredding), and mixing the reduced catalytic paper with the tobacco cut filler in the composition of the tobacco. The nanoparticle carbon monoxide catalyst is incorporated into a web-filler material by fixing the nanoparticle carbon monoxide catalyst to web-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 embodiment, the web-filler material is CaCO3 or other conventional web-filler material used in cigarette paper manufacture. If desired, the catalytic paper can include web-filler materials which do not include the nanoparticle carbon monoxide catalyst.
In a preferred embodiment of a smoking article, the nanoparticle iron oxide catalytic particle includes FeOOH, α-Fe2O3, γ-Fe2O3, or mixtures thereof. The nanoparticle iron oxide catalytic particle is supported on a web-filler material selected from the group consisting of CaCO3, TiO2, silicates such as SiO2, Al2O3, MgCO3, MgO and Mg(OH)2 to form a catalyst modified web-filler. An average particle size of the catalyst modified 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 30 mg.
In one approach, the nanoparticle carbon monoxide catalyst, such as nanoparticle iron oxide catalytic particles, 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 CaCO3 used 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 a 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 amount, e.g., 10 to 90% catalyst and 90 to 10% web-filler. The solid is either 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 about 50 to 60 wt. % catalyst loading or less of nanoparticle iron oxide catalytic particle on calcium carbonate, the slurry dries to a powdery substance; for a slurry containing a catalyst loading of greater than about 60 to 70 wt. % catalyst loading of the nanoparticle iron oxide catalytic particle on calcium carbonate, the slurry dries to a self-supporting solid mass. Prior to incorporating the catalyst modified web-filler in catalytic paper, 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., the nanoparticle carbon monoxide catalyst/web-filler material, can be incorporated into the paper through the papermaking processes. For example, the catalyst modified web-filler can be used as filler material in the papermaking processes.
In another approach, particles of web-filler material, such as CaCO3, support the nanoparticle carbon monoxide catalyst, such as nanoparticle iron oxide, 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 filler), the catalyst modified web-filler is calcined by heating the catalyst modified web-filler to a suitable calcining temperature of no more than 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. The catalyst modified web-filler, e.g., the nanoparticle carbon monoxide catalyst/web-filler material, can be used as filler material in conventional papermaking processes. For example, the catalyst modified web-filler material can be used as web-filler in the papermaking processes.
An exemplary process of making catalyst modified web filler comprising a 50/50 NANOCAT® iron oxide nanoparticle catalyst/CaCO3 mixture utilizing milling can be carried out as follows:
An exemplary process of making catalyst modified web filler comprising a 50/50 NANOCAT® iron oxide nanoparticle catalyst/CaCO3 mixture utilizing spray drying can be carried out as follows:
Once produced, the catalytic paper is shredded and mixed with the tobacco cut filler to form a composition of tobacco for subsequent manufacture into a cigarette tobacco rod in a cigarette making machine. Any suitable tobacco mixture may be used for the cut filler. Examples of suitable types of tobacco materials include flue-cured, Burley, Maryland or Oriental tobaccos, the rare or specialty tobaccos, and blends thereof. The tobacco material can be provided in the form of tobacco lamina, processed tobacco materials such as volume expanded or puffed tobacco, processed tobacco stems such as cut-rolled or cut-puffed stems, reconstituted tobacco materials, or blends thereof. The tobacco can also include tobacco substitutes.
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.
In the catalytic paper, the nanoparticle carbon monoxide catalyst can be fixed to the filler material to form a catalyst modified web-filler material by any suitable technique. For example, the nanoparticle carbon monoxide catalyst can be combined with the web-filler material by co-precipitating the nanoparticle iron oxide catalytic particle from a liquid phase onto the web-filler material or co-depositing the nanoparticle iron oxide catalytic particle 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 catalytic paper through conventional papermaking processes. For example, the catalyst modified web-filler can be used as all or part of the web-filler material in the papermaking processes or can be distributed directly onto the paper, such as by spraying or coating onto wet or dry base web to form the catalytic paper. A catalytic paper can be any wrapper for smoking articles, 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. Further, the catalytic paper 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 catalytic 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/CaCO3 particles 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 and the paper sheet (e.g., finished web) is formed 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 and, with additional processing such as further drying and pressing, if necessary, forms a sheet of catalytic paper (e.g., finished web). The catalytic paper is subsequently taken up for storage or use, e.g. the catalytic paper is coiled in a sheet or roll.
Referring to
The Fourdrinier wire 204 carries the laid slurry pulp (e.g., base web) from the head box 202 along a path in the general direction of arrow A in
Downstream of the dry line, the intermediate web 212 separates from the Fourdrinier wire 204 at a couch roll 214. From there, the Fourdrinier wire 204 continues on the return loop of its endless path. Beyond the couch roll 214, the intermediate web 212 continues on through the remainder of the papermaking system which further dries and presses the intermediate web 212 and surface conditions it to a desired final moisture content and texture to form a paper 220 (e.g., finished web). Such drying apparatus are well known in the art of papermaking and may include drying section 216 including drying felts, vacuum devices, rolls, and/or presses, applied thermal energy, and the like.
The cigarette making machine 200 can optionally include more than one head box and/or more than one Fourdrinier wire with either separate or common furnish supply. Referring to
Referring to
Other papermaking processes can be used to make a catalytic paper, e.g., a paper with a nanoparticle carbon monoxide catalyst. For example, a laminated, a bilayer or multilayer catalytic paper can be made. Examples of bilayer and multilayer paper is 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 catalytic paper including a nanoparticle carbon monoxide catalyst, at least one of a first layer and a second layer can include the nanoparticle carbon monoxide catalyst as described in embodiments herein. The bilayer catalytic paper can then be reduced in size, mixed with tobacco cut filler, and the composition formed into a tobacco rod in a cigarette making machine. Additional examples of paper configurations and types of paper that can be formed as catalytic paper and used in a composition of tobacco include bilayer paper in which either the first paper layer or the second paper layer can be a banded paper, a paper having a plurality of regions of variable basis weight in the cross direction, and/or a catalytic paper formed with catalyst modified web-filler.
The bilayer or multilayer single sheet catalytic paper 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 catalytic paper that includes the nanoparticle carbon monoxide catalyst and a second head box can hold the materials for a conventional paper (wrapper).
In another example of making bilayer or multilayer single sheets of catalytic paper, the first head box can hold the materials for a catalytic paper that includes the nanoparticle carbon monoxide catalyst at a first concentration or loading level and a second head box can hold the materials for a catalytic paper that includes the nanoparticle carbon monoxide catalyst at a second concentration or loading level. In preferred embodiments, the first concentration or first loading level is different from the second concentration or second loading level. For example, the catalytic paper can have a radially inner layer and a radially outer layer, the radially inner layer having a first loading of the nanoparticle carbon monoxide catalyst and the radially outer layer having a second loading of the nanoparticle carbon monoxide catalyst. The first loading of the nanoparticle carbon monoxide catalyst can be greater than the second loading of the nanoparticle carbon monoxide catalyst. In one embodiment, the first loading of the nanoparticle carbon monoxide catalyst is up to 100 mg and the second loading of the nanoparticle carbon monoxide catalyst is less than 1 mg. Preferably, the second loading of the nanoparticle carbon monoxide catalyst is zero. In another embodiment a ratio, in weight percent, of the nanoparticle carbon monoxide catalyst to the web-filler material in the radially inner layer is from 0.1 to 3.0, more preferably from 0.1 to 1.0, most preferably from 0.33 to 1.0, and a total loading of the nanoparticle carbon monoxide catalyst in the radially outer layer is less than 1 mg, more preferably the total loading of the nanoparticle carbon monoxide catalyst in the radially outer layer is zero. Additional details on the manufacturing of bilayer and multilayer papers 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.
Additional examples of papermaking processes include the method for making banded paper for banded smoking article wrappers disclosed in U.S. Pat. No. 5,342,484, the entire content of which is herein incorporated by reference, the method for producing paper having a plurality of regions of variable basis weight in the cross direction disclosed in U.S. Pat. No. 5,474,095, the entire content of which is herein incorporated by reference, and the method of making a catalytic wrapper disclosed in commonly-owned U.S. Provisional Patent Application No. 60/477,922 (Attorney Docket No. 021238-570) entitled “CIGARETTE WRAPPER WITH CATALYTIC FILLER AND METHODS OF MAKING SAME” and filed on Jun. 13, 2003, the entire content of which is herein incorporated by reference.
Reducing the size of the catalytic paper can be by any suitable technique such as tearing, shearing, shredding and so forth. In a preferred embodiment, the catalytic paper is reduced in size to approximate the shape, size and form of tobacco cut filler. For example, the reduced catalytic paper can have an average thickness from 0.10 mm to 0.13 mm (with a range of the thickness of 0.03 mm to 0.15 mm), an average width of less than 1.0 mm (with a maximum width of 5 mm), and an average length of less than 3.0 mm (with a maximum length of 25 mm).
The nanoparticle carbon monoxide catalyst can also be directly incorporated into the catalytic paper either during or after the papermaking process. This can occur instead of, or in addition to, incorporating the nanoparticle carbon monoxide catalyst into the web-filler material. For example, during the papermaking process the nanoparticle carbon monoxide catalyst, with or without being incorporated into a web-filler material, can be distributed, e.g., sprinkled, cast, spread, sprayed, drip coated, curtain coated, or otherwise placed in contact with the spread wet base web prior to drying. The wet base web is subsequently dried to form a catalytic paper and the nanoparticle carbon monoxide catalyst is retained within the catalytic paper. In another example, during the papermaking process the nanoparticle carbon monoxide catalyst, with or without being incorporated into a web-filler material, can be distributed, e.g., sprinkled, cast, spread, sprayed, drip coated, curtain coated, or otherwise placed in contact with the finished web. In both of the examples, a retention aid can be incorporated into the papermaking process to improve the distribution of the nanoparticle carbon monoxide catalyst in the paper component, e.g., the aqueous slurry used in the paper making process can include a retention aid.
A preferred catalytic paper for inclusion in a composition of tobacco comprises a web including cellulosic fibers and a catalyst modified web-filler incorporated into the web. The catalyst modified web-filler includes a web-filler material supporting a nanoparticle carbon monoxide catalyst. In the exemplary embodiment, the nanoparticle carbon monoxide catalyst is a nanoparticle iron oxide catalytic particle. For example, the nanoparticle iron oxide catalytic particle can include FeOOH, α-Fe2O3, γ-Fe2O3, or mixtures thereof. A suitable nanoparticle iron oxide catalytic particle is NANOCAT® Superfine Iron Oxide.
The nanoparticle carbon monoxide catalyst, e.g., the nanoparticle iron oxide catalytic particle, is present in the catalyst modified web-filler up to about 60 wt. % catalyst loading, more preferably from about 10 wt. % to about 50 wt. % catalyst loading, and most preferably is at about 20 to 30 wt. % catalyst loading, relative to the total web-filler material.
A preferred catalytic paper can have a basis weight of from about 18 g/m2 to about 60 g/m2 and a permeability of from about 5 CORESTA units to about 80 CORESTA units. More preferably, the catalytic paper has a basis weight from about 30 g/m2 to about 45 g/m2 and the permeability is about 30 to 35 CORESTA units. However, any suitable basis weight for the catalytic paper 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.
The ratio of nanoparticle carbon monoxide catalyst to web-filler material can be varied by subjecting a slurry of nanoparticle carbon monoxide catalyst/web-filler material, e.g., the slurry of nanoparticle iron oxide catalyst/CaCO3 or 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 CaCO3 from CaCl3 by 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 CO2 at a temperature above 150° C., preferably at a temperature above 400° C. Additionally, the conversion rate of CO to CO2 by nanoparticle iron oxide catalyst is enhanced by the rapid and efficient transport of CO to the region of the nanoparticle carbon monoxide catalyst and CO2 away 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. During the puffing process, CO is concentrated in the periphery of the cigarette, e.g., near the cigarette paper wrapper, in front of the burn zone. The oxygen concentration is high in the same region as high CO concentration due to diffusion of O2 from outside the cigarette. Airflow into the tobacco and during the puffing process 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”, Beiträge zur Tabakforschung International, vol. 11, no. 1, pp. 1-17, (1981), the contents of both are incorporated herein by reference.
The composition of tobacco with catalytic filler can be used as cut filler 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.
The position and quantity of paper with catalyst modified web-filler, e.g., catalytic filler, in the tobacco composition, e.g., the position and quantity of the shredded paper with catalyst modified web-filler, 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. For example, 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 composition of tobacco can be manufactured in which the catalytic filler can be incorporated in those portions of the tobacco column that are predicted to coincide with the appropriate temperature for operation of the catalyst. The selective incorporation of catalytic filler can be realized, for example, by using different supply lines to the cigarette making machine, each supply line having a different catalytic filler. The different catalytic filler can differ either in concentration of catalyst modified web-filler, or type of catalyst modified web-filler, or operating temperature of catalyst modified web-filler. The different supply line can be at selected positions in the cigarette making process corresponding to selected locations of the cigarette, e.g., radially or axially positioned.
For example, a preferred nanoparticle carbon monoxide catalyst for use in a catalytic filler for a tobacco composition of a smoking article is catalytically active at temperature as low as ambient temperature and does not deactivate even at temperatures as high as 900° C. The preferred catalytic filler 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 catalytic filler provides sufficient contact time between the mainstream smoke and the nanoparticle carbon monoxide catalyst for the CO to be converted to CO2. Further exemplary distributions of the catalytic filler include a radial distribution within the tobacco column. The radial distribution of catalytic filler can produce a higher concentration of nanoparticle carbon monoxide catalyst along a radially outer portion of the tobacco column, e.g., toward the surface of the cylindrical tobacco column that is encased by the wrapper in the smoking article. Other distributions include a distribution along a length of the tobacco column. A lengthwise distribution can produce a higher distribution of nanoparticle carbon monoxide catalyst toward a butt end of the tobacco rod, e.g., toward the end with a filter in a filtered smoking article. An example of a preferred nanoparticle carbon monoxide catalyst includes NANOCAT® Superfine Iron Oxide, which starts to convert CO to CO2 at 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 CO2 can 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 CO2 both at the burn zone and behind the burn zone, effectively increasing the conversion time and the area of the smoking article 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 CO2 outside the described temperature range, but the conversion rate may be affected.
In any of these examples, the nanoparticle carbon monoxide catalyst can be distributed continuously or discretely and can be distributed radially or linearly within the tobacco column. Also, the nanoparticle carbon monoxide catalyst can be distributed uniformly within the smoking article.
The nanoparticle carbon monoxide catalyst is present in the tobacco composition as catalytic filler in an amount effective to convert at least 40% 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 50% of carbon monoxide to carbon dioxide at a temperature of at least 500° C. More preferably, the nanoparticle carbon monoxide catalyst converts at least 80% of carbon monoxide to carbon dioxide at a temperature of at least 700° C.
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 paper filler and that during the calcination step the catalyst surface is improved due to evaporation of bound water molecules.
The surface area of the supported catalyst was investigated using BET surface area measurements. It was observed that the BET surface areas for samples with NANOCAT® Superfine Iron Oxide 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. These results 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 substituted for the high temperature nanoparticle carbon monoxide catalyst in the catalytic paper. Low temperature and even room temperature catalysts can extend the effective region of the reaction zone for CO to CO2 conversion to the whole cigarette, provided the temperature rise due to the exothermic reaction remains below the ignition temperature of the tobacco rod and/or its components.
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 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 Y2O3 doped with zirconium or Mn2O3 doped with palladium, or mixtures thereof as disclosed in 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.
Advantageously, supported nanoscale particles exhibit a reduced tendency to agglomerate with each other as well as a reduced tendency to leech out of the catalytic paper during cigarette paper manufacture. The web-filler material for support of the nanoscale particles can comprise calcium carbonate (CaCO3), which is used conventionally as a filler material in cigarette paper manufacturing. The catalytic effect of nanoscale catalyst particles (e.g., for the reduction of CO and/or NOx from mainstream smoke) can be controlled by varying the loading of catalytic particles in the catalytic paper and/or the loading of catalytic paper in the tobacco composition. The catalytic paper can be reduced in size, e.g., shredded in different shapes and sizes, and can be distributed continuously or discontinuously through the tobacco rod along different dimensions of a smoking article. By controlling the shape, size and distribution of the catalytic paper within the tobacco rod, adequate gas flow through the smoking article can be achieved.
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.
This application claims priority under 35 USC §119 to U.S. Provisional Application No. 60/477,924 entitled SHREDDED PAPER WITH CATALYTIC FILLER IN TOBACCO CUT FILLER AND METHODS OF MAKING SAME and filed on Jun. 13, 2003, the entire content of which is hereby incorporated by reference.
Number | Date | Country | |
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60477924 | Jun 2003 | US |