MX2008008857A - Cigarette components having encapsulated catalyst particles and methods of making and use thereof - Google Patents

Abstract

Encapsulated catalyst particles can be incorporated in tobacco cut filler and/or cigarette paper used to form a cigarette. The encapsulated catalyst particles, which can decrease carbon monoxide and/or nitric oxide in mainstream tobacco smoke, comprise catalyst particles that are encapsulated with a volatile coating. During the smoking of a cigarette comprising the encapsulated catalyst particles, the volatile coating is volatilized to expose an active surface of the catalyst particles .

Description

CIGARETTE COMPONENTS HAVING ENCAPSULATED CATALYTIC PARTICLES AND METHODS TO MAKE AND USE THE SAME BACKGROUND Cigarettes produce both mainstream smoke during a puff and sidestream smoke during static burn. The constituents of both mainstream smoke and sidestream smoke are carbon monoxide (CO) and nitric oxide (NO). The reduction of carbon monoxide and / or nitric oxide in smoke is desirable.

BRIEF DESCRIPTION OF THE INVENTION [0002] Cigarettes and cigarette components (e.g., tobacco cut filler and cigarette paper) comprising encapsulated catalyst particles capable of decreasing carbon monoxide and / or nitric oxide in current tobacco smoke are described. Main, wherein the encapsulated catalyst particles comprise catalyst particles that are at least partially coated with a volatile encapsulant. Preferably, the catalyst particles are completely coated with the volatile encapsulant. The catalyst particles, which may comprise nanoscale particles, preferably comprise an elemental metal, alloy, oxide and / or oxyhydroxide of at least one element selected from the group consisting of Mg, Al, Si, Ti, V, Cr , Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Ag, Sn, Ce, Pr, La, Hf, Ta, W, Re, Os, Go and Au. The preferred catalyst particles can decrease tobacco smoke constituents, for example, catalyze the conversion of carbon monoxide to carbon dioxide and / or nitric oxide to nitrogen, oxidize carbon monoxide to carbon dioxide and reduce nitric oxide to nitrogen. The volatile encapsulant is preferably a wax, a water soluble polymer or a water insoluble polymer. The volatile encapsulant may comprise a flavor carrier compound, such as menthol, a menthol derivative or a menthol precursor. Preferred volatile encapsulants have a volatilization temperature of between about 40 ° C and about 350 ° C or volatilize upon exposure to an atmosphere having a relative humidity of more than about 5%. In one embodiment, the volatile encapsulant comprises a first layer (e.g., a flavor carrier layer) in contact with the catalyst particles and a second layer formed on the first layer. In a cigarette comprising encapsulated catalyst particles, the volatile encapsulant is adapted to volatilize (e.g., thermally or chemically degrade) during smoking of a cigarette to expose an active surface of the catalyst particles. In one embodiment, the encapsulated catalyst particles they can be incorporated homogeneously or non-homogeneously together with the tobacco bar of a cigarette. In a further embodiment, the encapsulated catalyst particles can be incorporated into the paper wrapper or filter of a cigarette. For example, the encapsulated catalyst particles may be incorporated in the first (i.e., inner) layer of a multilayer shell. The encapsulated catalyst particles can be distributed along the paper or printed envelope on a surface of the paper wrapper. A cigarette may comprise a mixture of different encapsulated catalyst particles. A method for making a cigarette comprises (i) incorporating catalyst particles encapsulated in and / or on at least one tobacco cut filler and a cigarette wrapper; (ii) providing the tobacco cutting filler to a cigarette making machine to form a tobacco column; and (iii) placing the cigarette wrap around the tobacco column to form a tobacco rod of a cigarette; and (iv) optionally attaching the cigarette filter to the tobacco column using tip paper. The encapsulated catalyst particles can be incorporated by atomization, pulverization or immersion. For example, the encapsulated catalyst particles can be incorporated into cigarette paper by atomizing or coating the encapsulated catalyst particles on a wet base, intermediate screen or finished screen web.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 (a) shows an optical microscope image of NANOCAT iron oxide catalyst particles as received. Figures 1 (b) and 1 (c) show NANOCAT iron oxide optical microscope images encapsulated in alginate in the form of particles and fibers, respectively.

DETAILED DESCRIPTION OF PREFERRED MODALITIES Components of cigarettes, cigarettes and cigarette smoking methods are described having encapsulated catalyst particles incorporated therein. The encapsulated catalyst particles comprise a core of one or more catalyst particles and a volatile encapsulating layer (i.e., coating) formed around the core. A volatile encapsulating layer can be a protective layer for the catalyst particles at near ambient temperatures (for example, during the storage of cigarettes and current under the combustion / pyrolysis zone in a lit cigarette), but upon exposure to an elevated temperature , moisture or gaseous phase constituents of cigarette smoke, the volatile material can volatilize (eg, thermally or chemically degrade) to expose the underlying catalyst particles.

The encapsulated catalyst particles can be incorporated into one or more components of a cigarette, such as tobacco cut filler, cigarette paper and cigarette filter of the cigarette. In cigarettes comprising encapsulated catalyst particles, the amount of carbon monoxide and / or nitric oxide in Mainstream smoke can be reduced. Methods for providing cigarettes comprising encapsulated catalyst particles include encapsulation of the catalyst particles and incorporation of the encapsulated catalyst particles in one or more components used to form a cigarette. The incorporation of catalyst particles in one or more components of a cigarette has been described in the commonly owned US patent publications. 2004/0131859; 2004/0040566 and 2004/01 1 0633, whose contents are incorporated herein by reference. The catalyst particles may be incorporated into a cigarette in order to reduce the concentration of mainstream smoke and / or sidestream smoke from one or more gas phase constituents (eg, CO or NO). However, during the smoking of a cigarette comprising catalyst particles, semi-volatile or non-volatile combustion products, such as tar may be formed on the catalyst particles. The early deposition of semi-volatile and non-volatile deposits can effectively deactivate the catalyst particles (eg, by forming a barrier between the catalyst particles and gas phase constituents and / or by interacting chemically with the catalyst particles) . For example, a layer of semi-volatile or non-volatile material can be effectively impermeable to gas phase constituents found in mainstream smoke. Additionally, at elevated temperatures, semi-volatile or non-volatile materials may react with the catalyst particles and decrease their catalytic activity. Encapsulated catalyst particles comprising a volatile coating that is formed directly on an exposed surface (eg, a catalytic surface) of the catalyst particles are described. By volatile it is meant that the encapsulating layer preferably has a volatilization temperature that is lower than the volatilization temperature of tar or other by-products of solid phase combustion / pyrolysis of tobacco. Before smoking a cigarette comprising the encapsulated catalyst particles, the volatile coating preferably encapsulates at least partially, more preferably completely encapsulates, the catalyst particles. Preferred volatile coatings are volatilized during the smoking of a cigarette. In a cigarette comprising the encapsulated catalyst particles, when the encapsulated catalyst particles are exposed to a temperature that is lower than the volatilization temperature of the coating, the volatile coating forms a protective layer over which the semi-volatile and non-volatile materials (for example, tar) can be deposited. Semi-volatile or non-volatile materials can be formed and deposited on the volatile coating and not on the catalyst particles. When the temperature reaches or exceeds the volatilization temperature of the encapsulant, the volatile coating - as well as any material formed thereon - can be removed to expose an active surface of the catalyst particles. In this way, an active surface of the catalyst particles can be exposed under smoking conditions (i.e., in advance of the combustion zone) to catalyze and / or oxidize gaseous mainstream constituents and / or sidestream smoke. Applicants have unexpectedly found that the encapsulated catalyst particles that are incorporated in a cigarette have a higher catalytic efficiency during cigarette smoking than the catalyst particles that are not encapsulated. In one embodiment, a cigarette comprises encapsulated catalyst particles, wherein during cigarette smoking the volatile encapsulant is volatilized at a distance from about 0.1 mm to about 10 mm, preferably from about 0.5 mm to about 2 mm in advance of the scorched line. As used herein, the "scorch line" is the line created in a cigarette paper wrapper on the edge of the combustion zone of the cigarette, produced during smoking of the cigarette. The encapsulating layer is formed from a volatile material that can be thermally or chemically degraded. In a first embodiment, the encapsulating material can be thermally degraded (eg, melted, sublimed or pyrolyzed) upon exposure to a temperature above an ambient temperature, but below about 350 ° C, preferably below about 200 ° C. C to expose a surface of the catalyst particles to mainstream smoke, sidestream smoke or both. The preferred encapsulating materials are thermally degraded to a temperature between approximately 40 ° C and approximately 200 ° C. In a further embodiment, the encapsulating material can be chemically degraded (e.g., dissolved) upon exposure to cigarette smoke components that are generated during smoking. For example, the mainstream smoke moisture may interact with the encapsulating layer to volatilize the encapsulating material and expose the catalyst particles. Preferred encapsulating layers are chemically degraded upon exposure to mainstream smoke or sidestream smoke having a relative numeration of more than about 5%, more preferably greater than about 20%. By providing a volatile encapsulating layer, an active catalytic surface of particles that are incorporated in a cigarette (eg, in tobacco cut filler) can be exposed in advance of the combustion region of a cigarette. The volatile encapsulating layer can minimize the physical interaction and chemical reaction between the catalyst particles and non-volatile or semi-volatile combustion and / or pyrolysis products (e.g., tar). For example, the high temperature cracking of tar molecules via reaction with the catalyst particles can be minimized. The catalyst particles, which comprise the core of the encapsulated catalyst particles, may comprise an elemental metal, alloy, oxide and / or an oxyhydroxide of at least one element selected from the group consisting of Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Ag, Sn, Ce, Pr, La, Hf, Ta, W, Re, Os, Go and Au. The catalyst walls preferably comprise nanoscale particles. By "nanoscale" it is meant that the catalyst particles have an average particle diameter of less than one miera. Preferably, the nanoscale particles have an average particle size of less than about 100 nm, more preferably less than about 50 nm, and most preferably less than about 10 nm. The preferred catalyst particles comprise iron oxides and / or oxyhydroxides. For example, MACH I, Inc., King of Prussia, Pennsylvania, U.S. sells Fe2O3 nanoscale particles under the tradenames NANOCAT® Superfine Iron Oxide (SFIO) and NANOCAT® Magnetic Iron Oxide. The NANOCAT® Superfine Iron Oxide (SFIO) is amorphous ferric oxide in the form of a free flowing powder, with a particle size of about 3 nm, a specific surface area of about 250 m2 / g and a bulk density of about 0.05 g / ml. The NANOCAT® Superfine Iron Oxide (SFIO) is synthesized by a vapor phase process, which makes it substantially free of impurities that may be present in conventional catalysts and is suitable for use in foods, medicines and cosmetics. NANOCAT® Magnetic Iron Oxide is a free-flowing powder with a particle size of approximately 25 nm and a surface area of approximately 40 m2 / g. Additional preferred catalyst particles comprise oxides and / or oxyhydroxides of manganese, copper or cerium.

The encapsulant, which forms a coating that encapsulates the catalyst particles, may comprise a wax, a water soluble polymer, a water insoluble polymer or other material capable of volatilizing during smoking of a cigarette to expose the underlying catalyst particles. . Preferred encapsulating materials are non-toxic, easily coated on catalyst particles, and stable (eg, thermally and chemically stable) under normal cigarette storage conditions. A preferred encapsulant comprises one or more compounds that carry flavor. The encapsulant may comprise a wax. Preferred waxes include hot melt materials having a melting temperature of from about 40 ° C to about 350 ° C. Exemplary waxes include beeswax, coconut wax, candelilla wax, carnauba wax, montana wax, ouricury wax, paraffin wax, rice wax or mixtures thereof. The encapsulant may comprise a water soluble polymer. Exemplary water soluble polymers include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxides, water soluble polamides, water soluble polyesters, water soluble celluloses, acrylic acid polymers, or mixtures thereof. The natural and modified water-soluble polymers include starches, dextrins, gums, gelatins, pectins, alginates, gum arabic or mixtures thereof. Preferred encapsulants are alginates. The alginates are salts of the long chain carbohydrate biopolymer, alginic acid, and include sodium alginate, calcium alginate, potassium alginate and propylene glycol alginate. Although alginic acid is insoluble in water, the salts are hydrocolloid (that is, they bind or absolve water) and can be formed into a coating. Alginates are generally acid stable and heat resistant. Adjust the concentration of calcium ions, which causes cross-linking, controls the gel strength. Combine alginate are other gums, such as pectin, can increase the viscosity. Alginates can be dispersed in water at room temperature, although the solubility is usually lower as the water temperature decreases. Alginate concentrations above 2% by weight can be dispersed by mixing high-cut suar to eliminate lumps. High-speed mixers combine high flow with high cutting to increase mixing efficiency. A preferred method for forming encapsulated catalyst particles comprising a coating of calcium alginate is discussed below. The encapsulant may comprise a water insoluble polymer. Exemplary water-soluble polymers include polyethylene, polypropylene, polyacrylates, polymethacrylates, polymethyl methacrylates, polyvinyl chloride, polyvinylidene chloride, polysaccharides or mixtures thereof. The encapsulant may comprise a flavor-carrying compound. Preferred flavor compounds include menthol, derivatives of menthol and menthol precursors. Other flavor compounds include synthetic and natural fragrances, essential oils, alcohols, aldehydes, esters, ethers, ketones, phenols and mixtures thereof. The flavor compound may be an aromatic compound or a non-aromatic compound. The catalyst particles can be coated with one or more layers of the same or different volatile encapsulates. For example, multiple coating steps can be used to achieve the desired thickness and / or coverage of a desired encapsulant. In a further example, the catalyst particles can be coated with a first volatile coating and then with a second volatile coating. In a preferred embodiment, the first volatile coating comprises a flavor-carrying compound. A variety of methods can be used to form the encapsulated catalyst particles. Suitable methods include providing the catalyst particles and forming at least one volatile encapsulating layer on the catalyst particles. The methods include gas phase techniques and liquid phase techniques. In an exemplary gaeosa phase technique, the catalyst particles can be mixed with a liquid phase encapsulant (e.g., solution or pure liquid of a volatile compound) to form a mixture. During mixing, the temperature and the amount of agitation can be controlled. For example, catalyst particles and a solution of an encapsulant can be mixed at room temperature and ultrasonicated to form a mixture homogeneous A catalyst-encapsulant particle mixture can be dried to form the encapsulated catalyst particles. According to a preferred method, the mixture can be aspirated to form an aerosol comprising catalyst particles coated with the encapsulant. The aerosolization temperature and dispensing speed can be controlled to form encapsulated solid phase catalyst particles (ie, wherein the encapsulant layer is dried to form a solid coating on the catalyst particles). By way of example, encapsulated catalyst particles comprising 50% by weight of NANOCAT® iron oxide particles coated with gum arabic can be prepared by first metering iron oxide particles (~ 1 g) with gum arabic (~ 1 g). ) in about 30 ml of deionized water under constant stirring to form a uniform suspension of the iron oxide particles. The suspension is aerosolized using a 0.5 mm nozzle at approximately 170 ° C, whereby the water present in the mixture is evaporated and iron oxide particles coated with gum arabic are formed. Depending on the processing conditions, the encapsulated catalyst particles may be in the form of a powder, granulate or agglomerate. The encapsulated catalyst particles may be in the form of spheres, spheroids, wires, fibrils and the like. In an exemplary liquid phase technique, the particles of Catalyst can be immersed in an encapsulant or liquid phase encapsulating precursor (eg, solution or pure liquid of a volatile compound) to form a mixture wherein a coating is formed in the catalyst particles. The temperature during the immersion can be controlled and the mixture can be stirred optionally (for example, stirred). The catalyst particles and an encapsulant can be mixed at room temperature to form the coating. After immersion, the coated catalyst particles may be dried and optionally further processed to form encapsulated catalyst particles. Additional processing may comprise crosslinking the encapsulating polymer, such as via an ion exchange reaction. One method for forming catalyst particles encapsulated with alginate comprises immersing the catalyst particles in a solution of an alginate salt to form coated catalyst particles, and then treating the coated catalyst particles to form a crosslinked polymeric alginate coating. By way of example, encapsulated catalyst particles comprising 50% by weight of NANOCAT® iron oxide particles coated with calcium and / or sodium alginate, can be prepared by first mixing iron oxide particles (~ 1 g) with a solution of sodium alginate (1 g of sodium alginate in 100 ml of deionized water) under constant stirring to form iron oxide particles coated with sodium alginate. The mixture is preferably homogenized (for example, for 30-1 30 seconds), it is allowed to settle in air (for example, for 10-60 minutes) and then it is homogenized again (for example, for 30-130 seconds). The sodium alginate coating can be at least partially and preferably completely converted (eg, polymerized) to a coating of calcium alginate via an ion exchange reaction. A known volume of the iron oxide particles coated with sodium alginate is preferably contacted with a solution comprising a multivalent cation. The solution may comprise an aqueous or non-aqueous (eg, alcoholic) solution. In a preferred method, the solution comprises calcium chloride (eg, 0.1 M aqueous solution of calcium chloride), whereby Ca2 + is exchanged for Na1 + via an ion exchange reaction that forms a calcium alginate lining volatile crosslinked around the iron oxide particles. Other multivalent cation solutions suitable for forming a crosslinked encapsulating layer may comprise aluminum, manganese, iron, copper, zinc, strontium, silver and barium. The hardness of a crosslinked polymer encapsulant can be controlled by varying the degree of crosslinking. The amount of crosslinking is to provide the reaction time (ie, cure time) between the encapsulant and the multivalent cation solution. Other polymers that can be crosslinked via ion exchange include polysaccharides. In a preferred method, a known volume of the iron oxide particles coated with sodium alginate is dispersed in a of drops (for example, through a syringe, such as a 26.5 gauge needle) in a calcium chloride solution. The height and speed of dispensing can be controlled to control the size of the encapsulated particles. The excess calcium chloride solution can be removed (for example, filtered or decanted) after a pre-set curing time (for example, up to about 2 hours) and the particles coated with calcium alginate can be washed and dried. Encapsulated catalyst particles comprising at least about 10, 20, 30, 40, 50, 60, 70, 80 or 90 ± 5% by weight of catalyst particles (eg, iron oxide particles) can be prepared. The optical micrographs of samples of iron oxide / calcium alginate are shown in Figure 1. Figure 1 (a) shows an optical micrograph of NANOCAT® iron oxide particles as received. Figure 1 (b) shows an optical micrograph of iron oxide particles encapsulated with caclium alginate in the form of irregular and spherical particles. Figure 1 (c) shows an optical micrograph of iron oxide particles encapsulated with calcium alginate in the form of fibrils. Additional methods for forming encapsulated catalyst particles include polymer-polymer incompatibility (wherein the catalyst particles are coated via preferential adsorption of a polymer from a solution of incompatible polymers that are dissolved in a common solvent); the encapsulation of fluidized bed and gas phase polymerization.

The encapsulated catalyst particles of micron size can have an average particle size of about 1 miera or less up to about 1,000 micras or more. The encapsulated catalyst particles can have an average particle size of 10, 20, 30, 40, 50, 60, 70, 80 or 90 micras ± 5 microns up to about 100, 200, 300, 400, 500, 600, 700, 800 or 900 micras ± 50 microns. The encapsulated catalyst particles may comprise individual particles or an agglomerate of coated catalyst particles. The preferred encapsulated catalyst particles have an average particle size of less than 1 miera. The submicron and nanoscale catalyst particles can be encapsulated to form encapsulated catalyst particles having an average particle size of 10, 20, 30, 40, 50, 60, 70, 80 or 90 nm ± 5 nm to about 100, 200 , 300, 400, 500, 600, 700, 800 or 900 nm ± 50 nm, depending on the average thickness of the encapsulant. According to a preferred method, the encapsulated catalyst particles are incorporated into at least one of tobacco cut filler, cigarette paper and cigarette filter which are used to form a cigarette. By incorporating the catalyst particles in one or more components of a cigarette, the amount of carbon monoxide and / or nitric oxide in mainstream smoke during smoking can be reduced. Preferably, the encapsulated catalyst particles are incorporated into the cut filler of tobacco, cigarette paper and / or Cigarette filter in an amount effective to reduce the mainstream smoke concentration of carbon monoxide and / or nitric oxide by at least 5% (e.g., by at least 10%, 1 5%, 20%, 25% , 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%). A preferred amount of the catalyst particles per cigarette is up to about 200 mg (eg, 1 mg to 200 mg, 1 mg to 50 mg, or 50 mg to 1000 mg). The encapsulated catalyst particles can be incorporated into a cigarette in an amount effective to convert at least 5%, more preferably at least 25%, of the carbon monoxide in mainstream tobacco smoke to carbon dioxide at a temperature of less than about 200 ° C and / or converting at least 5%, more preferably at least 25%, of the nitric oxide in mainstream tobacco smoke to nitric oxide at a temperature of less than about 200 ° C. A method for making a cigarette comprising the steps of (i) incorporating catalyst particles encapsulated in and / or on at least one of tobacco cut filler, cigarette paper and cigarette filter is described.; (ii) providing the tobacco cutting filler to a cigarette making machine to form a tobacco column; (iii) placing the cigarette wrap around the tobacco column to form a tobacco rod of a cigarette; and (iv) optionally attaching the cigarette filter to the tobacco column using tip paper.

Although it is not desired to bind to a theory, it is believed that during the smoking of a cigarette having encapsulated catalyst particles incorporated therein, CO and / or NO can be catalyzed in the presence of oxygen to reduce the level of CO and / or NO in mainstream and / or sidestream smoke. It is also believed that subsequent to the catalytic reaction, the catalyst particles can oxidize CO in the presence or absence of oxygen and / or reduce NO to decrease the level of CO and / or NO in the mainstream and / or sidestream smoke. . Preferably, the encapsulated catalyst particles can catalyze both the conversion of CO to CO2 and NO to N2. As used herein, a catalyst is capable of affecting the rate of a chemical reaction, for example, a catalyst can increase the rate of oxidation of carbon monoxide to carbon dioxide without participating as a reactant or product of the reaction. An oxidant is capable of oxidizing a reagent, for example, by donating oxygen to the reagent, so that the oxidant itself is reduced. A reducing agent is capable of reducing a reagent, for example, by receiving oxygen from the reagent, so that the reducing agent itself is oxidized. "Smoking" a cigarette means heating or combustion of the cigarette to form smoke, which can be dragged through the cigarette. Generally, the smoke from a cigarette involves lighting one end of the cigarette and, while the tobacco contained therein undergoes a combustion reaction, entrains combustion smoke through the mouth end of the cigarette. The cigarette can also be smoked by other means. For example, the cigarette can be smoked by heating the cigarette and / or heating using electric heater means as described in US patents commonly assigned to us. 6.053, 1 76; 5,934,289; 5,591, 368 or 5,322,075. The term "main stream" smoke refers to the mixture of gases passing under the tobacco rod and issuing through the filter end, ie, the smoke that is expelled or drawn from the mouth end. of a cigarette during the smoking of the cigarette. The mainstream smoke contains smoke that is drawn both through the lit region, as well as through the cigarette wrap. The term "sidestream" smoke refers to the smoke produced during static burning. Several factors contribute to the formation of carbon monoxide and nitric oxide in a cigarette. In addition to the constituents in tobacco, the temperature and concentration of oxygen in a cigarette during combustion can affect its formation. For example, the total amount of carbon monoxide formed during smoke comes from a combination of three main sources: thermal decomposition (approximately 30%), combustion (approximately 36%) and reduction of carbon dioxide with carbonized tobacco (at least 23%). %). The formation of carbon monoxide from thermal decomposition, which is largely controlled by chemical kinetics, starts at a temperature of about 180 ° C and ends at about 1050 ° C. The formation of carbon monoxide and carbon dioxide during combustion is largely controlled by the diffusion of oxygen to the surface (ka) and via a surface reaction (kb). At 250 ° C, ka and kb are approximately equal. At 400 ° C, the reaction becomes controlled by diffusion. Finally, the reduction of carbon dioxide with carbonized tobacco or coal occurs at temperatures around 390 ° C and above. During combustion, nitric oxide is produced in mainstream smoke at a concentration of approximately 0.5 mg / cigarette. However, nitric oxide can be reduced by carbon monoxide according to the following reactions: 2NO + CO - »N2O + CO2 N2O + CO -» N2 + CO2 During smoking there are three different regions in a cigarette: the combustion zone, the pyrolysis / distillation zone and the condensation / filtration zone. The combustion zone is the burning area of the cigarette produced during smoking of the cigarette, usually at the burning end of the cigarette. The temperature in the combustion zone varies from about 700 ° C to about 950 ° C, and the heating rate can be as high as 500 ° C / second. Oxygen is consumed in the combustion of tobacco to produce carbon monoxide, carbon dioxide, nitric oxide, water vapor and other organic compounds (for example, tar). The combustion zone is highly exothermic and the generated heat is transported to the pyrolysis / distillation zone. The pyrolysis zone is the region behind the combustion zone, where the temperature varies from approximately 200 ° C to approximately 600 ° C. The pyrolysis zone is where most of the carbon monoxide is produced. The main reaction is the pyrolysis (ie, thermal degradation) of tobacco that produces carbon monoxide, carbon dioxide, nitric oxide, coal and other smoke components (eg, tar) using the heat generated in the combustion zone . In the condensing / filtering zone, the temperature varies from ambient to approximately 150 ° C. The main process in this area is the condensation / filtration of the smoke components. Some amount of carbon monoxide, carbon dioxide, nitric oxide and nitrogen diffuse out of the cigarette and some oxygen (eg, air) diffuses into the cigarette. During the smoking of a cigarette, the mainstream smoke flows towards the filter end of the cigarette. As carbon monoxide and nitric oxide travel within the cigarette, oxygen diffuses to and carbon monoxide and nitric oxide diffuse out of the cigarette through the envelope. After a typical 2-second puff of a cigarette, CO and NO are concentrated at the periphery of the cigarette, ie, near the cigarette wrap, in front of the combustion zone. Due to the diffusion of O2 towards the cigarette, the concentration of oxygen is also high in the peripheral region. The air flow to the tobacco rod is larger near the combustion zone at the periphery of the cigarette and is approximately commensurate with the temperature gradient, it is say, the greater air flow is associated with higher temperature gradients. In a normal cigarette, the highest temperature gradient is from the combustion zone (> 850 ° C-900 ° C) axially towards the filter end of the cigarette. Within a few millimeters behind the combustion zone the temperature drops to almost ambient. Additional information with air flow patterns, the formation of constituents in cigarettes during smoking and the formation of smoke 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 (1986) and Richard R. Baker, "Variation of the Gas Formation Regions within a Cigarette Coal Combustion during the Smoking Cycle" (Variation of the gas formation regions within a cigarette burning coal during the cycle of smoked ", Beitráge zur Tabakforschung International, vol.1 1, No. 1, pp. 1-17, (1981), the contents of which are incorporated herein by reference.The non-volatile compounds, such as, tar produced from The combustion and / or pyrolysis of tobacco can coat non-encapsulated catalyst particles and decrease their catalytic efficiency.The non-volatile compounds that form on the surface of encapsulated catalyst particles, however, can be removed by removing the volatile encapsulating layer. of the catalyst particles, thereby exposing the catalyst particles to cigarette smoke.The encapsulated catalyst particles can be provided in the form of a dry powder, paste or dispersion in a liquid. By For example, the encapsulated catalyst particles can be sprayed on, atomized on, or combined with the cut filler tobacco or cigarette paper. In a further example, the cut filler of tobacco or cigarette paper material can be rinsed or coated by immersion with a liquid containing the encapsulated catalyst particles. The techniques for making cigarettes are well known in the art. Any conventional or modified cigarette making technique can be used to incorporate the encapsulated catalyst particles. In the production of a cigarette, the cutting filler composition is usually optionally combined with other cigarette additives and is provided to a cigarette making machine to produce a tobacco column, which is then wrapped in cigarette paper to form a cigarette. tobacco bar that is cut into sections, and optionally finished in point with filters. The resulting cigarettes can be manufactured to desired specifications using standard or modified cigarette making techniques and equipment. Cigarettes can vary from about 50 mm to about 120 mm in length. The circumference is from about 1 5 mm to about 30 mm in circumference, and preferably around 25 mm. The packing density of tobacco is usually in the range of about 1 00 mg / cm 3 to about 300 mg / cm 3, and preferably 1 50 mg / cm 3 to about 275 mg / cm 3. One mode provides a method for forming the particles of encapsulated catalyst and then depositing the catalyst particles on and / or incorporating them into tobacco cut filler, which is then used to form a cigarette. The tobacco cut filler is usually in the form of fragments or filaments cut into widths ranging from about 1/4 cm to about 1/8 cm (about 1/1 0 in to about 1/20 in) or even 1 / 16 cm (1/40 in). The lengths of the filaments vary from about 0.65 cm to about 7.6 cm (about 0.25 in. To about 3.0 in.). The cigarettes may further comprise one or more flavorings or other additives (eg, burn additives, combustion modifying agents, coloring agents, binders, etc.). Any suitable tobacco mixture can be used for cutting filler. Examples of suitable types of tobacco materials include smoke-cured tobacco, Burley, Brihth, Maryland or Oriental, rare or specialty tobacco and mixtures thereof. The tobacco material can be provided in the form of tobacco sheets, processed tobacco materials such as, blown or expanded tobacco by volume, processed tobacco stems, such as, rolled cut stems or cutting blowers, reconstituted tobacco materials , or mixtures thereof. Tobacco may also include tobacco substitutes. The encapsulated catalyst particles can be added to cut filler tobacco stock (for example, filling loose cut) provided to a cigarette making machine or incorporated directly into a tobacco rod before wrapping a cigarette wrap around the cigarette rod to form a tobacco column. Preferably, the encapsulated catalyst particles are provided continuously along the length of a tobacco rod, although the encapsulated catalyst particles may be provided at discrete locations along the length of a tobacco rod. In this way, the encapsulated catalyst particles can be distributed homogeneously or non-homogeneously along the length of a tobacco rod. For example, a tobacco rod may comprise a first charge of encapsulated catalyst particles at a location along the tobacco rod and a second charge of encapsulated particles at a second location along the tobacco rod. A preferred tobacco rod comprising encapsulated catalyst particles has a first charge of catalyst particles encapsulated at the filter end of the tobacco rod and a second charge of catalyst particles encapsulated at the distal end of the tobacco rod, where the first load is greater than the second load. The encapsulated catalyst particles and tobacco cut filler may be provided in any desired ratio, for example, 1 wt% to 90 wt% encapsulated catalyst particles and 99 wt% up to 10 wt% cut filler of tobacco, more preferably from about 1% by weight to about 50% by weight of encapsulated catalyst particles, most preferably from about 1% by weight to about 20% by weight of encapsulated catalyst particles. In addition to or instead of incorporating the encapsulated catalysts in the tobacco rod, the encapsulated catalyst particles can be incorporated in cigarette paper before or after the cigarette paper is incorporated into the cellulosic web of the paper by depositing the particles directly. in the cellulose weft or in the filling material that is incorporated into the paper. The encapsulated catalyst particles can be incorporated into cigarette paper and / or into the raw material used to make cigarette paper (for example, incorporated in the paper stock of a cigarette paper making machine). Encapsulated catalyst particles can be incorporated into cigarette paper by atomizing or coating the particles on a wet (eg, cellulosic), an intermediate web or a finished web. According to one method, the catalyst particles encapsulated in the form of a dry powder are physically mixed with the cigarette paper material during the papermaking process. In another method, paste (eg, slurry) of the encapsulated catalyst particles can be incorporated into the main casing of a papermaking machine and the encapsulated catalyst particles can be incorporated into the cigarette paper during the processing process of paper.

Encapsulated catalyst particles and cigarette paper can be provided in any desired ratio, for example, 1% by weight up to 90% by weight of catalyst and 99% by weight up to 10% by weight of cigarette paper. In a preferred embodiment, the amount of encapsulated catalyst particles comprises from about 1% by weight to about 50% by weight, more preferably from about 1% by weight to about 20% by weight of the cigarette paper. The amount, location and distribution in a cigarette of the encapsulated catalyst particles can be selected as a function of temperature and air flow characteristics exhibited during smoking in order to adjust, for example, increase or maximize the conversion rate of CO to CO2 and / or NO to N2. The amount of the encapsulated catalyst particles incorporated in a cigarette can be selected such that the amount of carbon monoxide and the amount of nitric oxide in mainstream smoke is reduced during smoking of a cigarette. The encapsulated catalyst particles can be coated and / or printed on at least one surface of a paper wrapper (eg, an inner and / or outer surface) to form text or images on the cigarette wrapper. The amount of printing and / or the amount of catalyst can be varied to adjust the amount of CO and / or NO reduction. The volatile encapsulating layer can be stained (for example, with a food dye) to control the appearance of the particles of encapsulated catalyst. For example, the color of the encapsulated catalyst particles can be provided to match or contrast with the color of the cigarette paper (or the tobacco cut filler). A cigarette may comprise a mixture of different encapsulated catalyst particles. The composition of the encapsulated catalyst particles (ie, the composition and / or size of the catalyst particles and / or the composition and / or thickness of the encapsulant) can be selected to operate in a given temperature range, and an amount The catalytically effective catalyst particles can be incorporated into a component of a cigarette (e.g., tobacco cut filler, cigarette filter and / or cigarette paper) to control the conversion efficiency and / or selectivity of the catalyst. For example, first encapsulated catalyst particles can be incorporated into the tobacco cut filler of a cigarette and second encapsulated catalyst particles can be incorporated into the cigarette paper. The cigarette paper having encapsulated catalyst particles incorporated therein can be used as a paper wrapper, paper filter and / or paper filler inside a cigarette. A cigarette wrapper can be any suitable wrapper to encircle the cutting filler, including wrappers containing flax, hemp, kenaf, esparto grass, rice straw, cellulose and so on. Optional filling materials, flavor additives and burn additives can be included in the cigarette wrap. The envelope may have more than one layer in cross section, such as in a bi-layer wrapper as described in co-owned US patent no. 5, 143, 098, the entire contents of which are incorporated herein by reference. The encapsulated catalyst particles can be incorporated into a cigarette envelope. The paper wrapper, which comprises a web of fibrous cellulosic material, may further comprise weft fill material particles, such as calcium carbonate (CaCO3). In practice, the weft filling material serves as an agent to control the permeability of the wrapper. The permeability of the envelope is usually measured in units of Coresta, which is defined as the volume of air, measured in cubic centimeters, which passes through a square centimeter of material in one minute at a pressure drop of 1 .0 kilopascals The paper wrap may comprise one or more layers. A preferred cigarette comprises a first casing, a second casing formed around the first casing and encapsulated catalyst particles incorporated in the first casing. The encapsulated catalyst particles will preferably be distributed along the tobacco rod and / or the cigarette wrap portions of a cigarette. By providing the encapsulated catalyst through one or more components of a cigarette, it is possible to reduce the amount of carbon monoxide entrained through the cigarette, in particular in combustion, pyrolysis, condensation and / or filter regions.

A further embodiment provides a method of treating tobacco smoke comprising igniting a cigarette to form tobacco smoke and entraining the smoke through the cigarette, wherein the volatile encapsulant is at least partially volatilized to expose a surface of the catalyst particles. In a preferred embodiment, the volatile encapsulant is volatilized at a distance from about 0.1 mm to 10 mm in advance of the singeing line. Although several modalities have been described, it will be understood that variations and modifications may be reclassified as will be apparent to those skilled in the art. Such variations and modifications will be considered within the scope and scope of the claims appended hereto.

Claims (18)

1. CLAIMS 1 . A component of a cigarette comprising encapsulated catalyst particles capable of at least one reduction of carbon monoxide and nitric oxide in mainstream tobacco smoke, wherein the catalyst particles are at least partially coated with a volatile encapsulant, and in where the component is selected from the group consisting of tobacco cut filler, cigarette paper and cigarette filter.
2. 2. A component according to claim 1, wherein: (a) the catalyst particles are completely coated with the volatile encapsulant; (b) the catalyst particles comprise at least one of an elemental metal, alloy, oxide and oxyhydroxide of at least one element selected from the group consisting of Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Ag, Sn, Ce, Pr, La, Hf, Ta, W, Re, Os, Go and Au; (c) the catalyst particles comprise at least one of an oxide and manganese, iron, copper or cerium oxyhydroxide; (d) the catalyst particles comprise nanoscale particles; or (e) the catalyst particles have an average particle size of less than about 100 nm or less than about 50 nm. 3. A component according to claim 1, wherein the Volatile encapsulant comprises at least one of: (a) a wax, a water soluble polymer or a water insoluble polymer; (b) a wax selected from the group consisting of beeswax, coconut wax, candelilla wax, carnauba wax, mountain wax, ouricury wax, paraffin wax, rice wax and mixtures thereof; (c) a water-soluble polymer selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxides, water-soluble polyamides, water-soluble polyesters, water-soluble celluloses, acrylic acid polymers, starches, dextrins, gums, gelatins, pectin, alginates, gum arabic and mixtures thereof; (d) a water-insoluble polymer selected from the group consisting of polyethylene, polypropylene polyacrylates, polymethacrylates, polymethyl-methacrylates, polyvinyl chloride, polyvinylidene chloride, polysaccharides and mixtures thereof. (e) a first layer in contact with the catalyst particles and a second layer formed on the first layer; and (f) a first layer comprising a flavor carrier compound and a second layer formed on the first layer. 4. A component according to claim 1, wherein: (a) the volatile encapsulant has a volatilization temperature of between about 40 ° C and about 350 ° C; (b) the volatile encapsulant is adapted to volatilize in a atmosphere having a relative humidity of more than about 5%; or (c) the volatile encapsulant has a volatilization temperature of between about 40 ° C and about 350 ° C and is adapted to be used in an atmosphere having a relative humidity of more than about 5%. 5. A component according to claim 1, wherein the volatile encapsulant comprises a flavor-carrying compound. 6. A component according to claim 5, wherein the flavor carrier compound comprises menthol, a menthol derivative, a menthol precursor or a mixture of the same. A component according to claim 5, wherein the flavor carrier comprises a synthetic fragrance, a natural fragrance, an essential oil, an aldehyde, an alcohol, an ester, a ketone, a phenol or a mixture thereof . A component according to claim 1, wherein the catalyst particles are capable of acting as an oxidant for the conversion of carbon monoxide to carbon dioxide, a reducing agent for the conversion of nitric oxide to nitrogen and as a catalyst for the conversion of at least one of carbon monoxide to carbon dioxide and nitric oxide to nitrogen. 9. A cigarette comprising a tobacco rod, cigarette paper and an optional filter, wherein at least one of the tobacco rod, filter paper and filter comprise encapsulated catalyst particles capable of at least one reduction of carbon monoxide. carbon and nitric oxide in mainstream tobacco smoke, wherein the catalyst particles are at least partially coated with a volatile encapsulant. A cigarette according to claim 9, wherein: (a) the volatile encapsulant is adapted to volatilize during smoking of a cigarette to expose an active surface of the catalyst particles; (b) the volatile encapsulant is adapted to degrade thermally or chemically during smoking of the cigarette to expose a surface of the catalyst particles; or (c) the volatile encapsulant is adapted to volatilize and degrade thermally or chemically during smoking of the cigarette to expose a surface of the catalyst particles. eleven . A cigarette according to claim 9, wherein the catalyst particles are completely coated with the volatile encapsulant. A cigarette according to claim 9, wherein the encapsulated catalyst particles are at least one of: (a) incorporated in an effective amount to convert at least 5% of the carbon monoxide in mainstream tobacco smoke to carbon dioxide or at least 5% of the nitric oxide in mainstream tobacco smoke to nitrogen or in an amount effective to convert at least 5% of the carbon monoxide into mainstream tobacco smoke to carbon dioxide and at least 5 % of nitric oxide in tobacco smoke from mainstream to nitrogen; (b) incorporated in a total amount of up to about 200 mg per cigarette; and (c) distributed homogeneously or non-homogeneously along the length of a tobacco rod.
3. 3. A cigarette according to claim 9, wherein the cigarette paper comprises at least one of: (a) an envelope having a first layer and a second layer formed around the first layer and wherein the catalyst particles encapsulated are incorporated in the first layer; and (b) an envelope and the encapsulated catalyst particles are coated, printed or coated and printed on at least one surface of the envelope. 14. A cigarette according to claim 9, wherein the cigarette comprises a mixture of different encapsulated catalyst particles. 5. A method for making a cigarette comprising: (i) incorporating catalyst particles encapsulated in, on or in and on at least one of tobacco cut filler, cigarette filter and cigarette wrapper; (ii) providing the tobacco cutting filler to a cigarette making machine to form a tobacco column; (iii) placing the cigarette wrap around the tobacco column to form a tobacco rod of a cigarette; and (iv) optionally joining the cigarette filter to the tobacco column using tip paper. 16. A method according to claim 1, wherein the incorporation comprises atomization, spraying or immersion. 17. A method according to claim 1, wherein the encapsulated catalyst particles are incorporated in the cigarette paper by atomizing or coating the encapsulated catalyst particles on a wet base, intermediate frame or finished weft. 18. A method according to claim 15, wherein the step of incorporating comprises combining the encapsulated catalyst particles and at least one of the tobacco cut filler and cigarette wrap in the absence of a liquid.