Patent Publication Number: US-2005121045-A1

Title: Treatment of mainstream smoke constituents by use of oxygen storage and donor metal oxide oxidation catalyst

Description:
RELATED INVENTION  
      This application claims benefit under 37 C.F.R. Section 1.78 of provisional application Ser. No. 60/502,665 filed Sep. 15, 2003. The full disclosure of the application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to the use of an oxygen storage and donor metal oxide oxidation catalyst to treat at least one constituent in mainstream smoke and more particularly, to reduce the amount of at least one constituent in the mainstream smoke.  
     BACKGROUND OF THE INVENTION  
      Work has been conducted to reduce sidestream smoke emissions from a burning cigarette. Oxygen storage and donor metal oxide oxidation catalysts have been used for reduction of sidestream smoke as described in various cigarette configurations of Applicant&#39;s published International Patent Applications: WO 98/16125 (U.S. Pat. No. 6,371,127); WO 99/53778 (U.S. Pat. No. 6,286,516); WO 02/24005 (U.S. patent application Ser. No. 09/954,432); WO 02/24006 (U.S. patent application Ser. No. 09/954,437); WO 04/023903; WO 03/077687 (U.S. patent application Ser. No. 10/382,218), the subject matter of these applications/patents are hereby incorporated by reference. These published patent applications/patents describe various combinations of oxygen storage and donor metal oxide oxidation catalysts and adjuncts that have been used in the reduction of the quantity of visible sidestream smoke from a burning cigarette. To provide sidestream smoke reduction in cigarettes, these particular combinations of oxygen storage and donor metal oxide oxidation catalysts and adjuncts are used in or on the cigarette paper/wrapper and/or cigarette tube. Examples of such oxygen storage and donor metal oxide oxidation catalysts used are the lanthanide metal oxides, typically, cerium oxide. In addition, these oxygen storage and donor metal oxide oxidation catalysts may be used in combination with other porous metal oxides to enhance sidestream smoke control. Furthermore, the effect on mainstream smoke was thought to be negligible. For example, in Applicant&#39;s International Patent Application WO 02/24005, it is described that the treatment paper does not materially alter the mainstream smoke. This was established by results shown in Example 2 wherein, for example, the aromatic hydrocarbons, which are a combination of phenol and hydroquinone, were at 150 μg per conventional cigarette versus 119 μg for a prototype cigarette containing treatment paper. The difference between 150 μg and 119 μg was not considered to be materially different. In addition, reviewing the other constituents listed in Table 2B reveals that the overall reported differences were not significant—and in many cases negligible or, in fact, somewhat increased. The experimental conditions for these tests were qualitative and, in view of the overall results of the tests, it was thought that there were no material differences in the mainstream smoke due to the treatment composition.  
      The use of metal oxides in cigarette tobacco for oxidation of toxic constituents in cigarette smoke, such as carbon monoxide, is described in, for example, U.S. Pat. No. 4,397,321, which uses ash in combination with a transition metal to reduce carbon monoxide content in the mainstream smoke. Regarding International Patent Applications WO 03/020058 and WO 03/020059, both assigned to Philip Morris Products Inc., International Patent Application WO 03/020058 describes a cut filler composition that comprises tobacco and a nanoparticle additive. The additive acts as an oxidant or catalyst to convert carbon monoxide to carbon dioxide. Some of the nanoparticle additives are iron oxide, titanium oxide or cerium oxide. International Patent Application WO 03/020059 describes a tobacco mixture that includes tobacco and an inorganic particulate material that reduces the burning temperature of the burning portion of the tobacco mixture, which may reduce the production of high-temperature reaction gases such as carbon monoxide. The inorganic particulate may be a metal oxide, such as titanium oxide and aluminum oxide.  
      Philip Morris continued their work on this type of cigarette and has subsequently found, as described in International Patent Application WO 2004/041008, that the presence of nanoparticle additives in the tobacco or the filter reduced the amount of certain toxic constituents in the mainstream smoke. Those toxic constituents are selected from the group consisting of aldehydes, carbon monoxide, 1,3-butadiene, isoprene, acrolein, acrylonitrile, hydrogen cyanide, o-toluidine, 2-naphthylamine, nitrogen oxide, benzene, N-nitrosonornicotine, phenol, catechol, benz(a)anthracene, benzo(a)pyrene, and mixtures thereof. International Patent Application WO 2004/041008 claims priority from two earlier U.S. applications, namely U.S. patent application Ser. No. 2004/0025895 published Feb.12, 2004 and U.S. patent application Ser. No. 2003/0131859 published Jul. 17, 2003.  
      Applicant has described in its published International Patent Application WO 98/16125 that catalytic material or particles can be used to convert odour-causing gases such as ammonia and aldehyde constituents. It was found that suitable catalysts such as precious metals, rare earth metals and the like and mixtures thereof and, in particular, platinum or cerium may be used to oxidize the odour-causing gases.  
      When using a very active oxygen donor oxidation catalyst, such as cerium oxide, flare ups can be a problem when puffing on the cigarette and on lighting the cigarette. It has been suggested that combining cerium oxide with other forms of oxides can reduce flare ups, as taught in Applicant&#39;s published International Patent Application, WO 03/077687.  
      Although it is desirable to reduce the amount of sidestream smoke emitted from a cigarette, there is a desire to also reduce toxic constituents in mainstream smoke or, in the alternative, regardless of sidestream smoke modification, treating the mainstream smoke constituents.  
     SUMMARY OF THE INVENTION  
      Quite surprisingly and contrary to the teachings of Applicant&#39;s International Patent Application WO 02/24005, the treatment composition is also useful for treating mainstream smoke, where such treatment entails the reduction of at least one constituent, such as carbon monoxide; constituents from the group of phenols; constituents from the group of carbonyls; and other constituents such as ammonia; aromatic amines; 1,3-butadiene, isoprene; acrylonitrile; and benzene.  
      The same benefit is also achievable with the compositions and cigarette structures defined in Applicant&#39;s International Patent Applications: WO 02/24006 and WO 03/077687. This treatment of mainstream smoke may also be carried out with the reduction of sidestream smoke. Quite surprisingly, the use of the treatment composition in the paper, with or without sidestream smoke control, is capable of treating and reducing toxic constituents in the mainstream smoke.  
      To further enhance the activity of the oxygen donor material in the treatment composition, precious metals may also be used with the smoke treatment materials to enhance this action particularly when the treatment material is used in the paper or wrapper.  
      The present invention entails a method for reducing at least one constituent of mainstream smoke from a burning cigarette comprising a step of using an oxygen storage and donor metal oxide oxidation catalyst in a cigarette.  
      The present invention also entails the use of an oxygen storage and donor metal oxide oxidation catalyst in a cigarette to reduce at least one constituent of mainstream smoke from a burning cigarette.  
      In one aspect of the present invention, the method for reducing at least one constituent from a group of carbonyls and at least one constituent from a group of phenols of mainstream smoke from a burning cigarette comprising a step of using a treatment composition for a cigarette paper/wrapper, wherein the treatment composition comprises, in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In another aspect of the present invention, the method for reducing at least one constituent from a group of carbonyls and at least one constituent from a group of phenols of mainstream smoke from a burning cigarette, comprising treating mainstream smoke with a treatment composition for a cigarette paper/wrapper, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In another aspect of the present invention, the method for reducing at least one constituent of mainstream smoke emitted from a burning cigarette, the method comprising a step of using a treatment composition for cigarette tobacco and/or a cigarette filter, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst, an essentially non-combustible finely divided porous particulate adjunct, and a precious metal.  
      In another aspect of the present invention, the method for reducing at least one constituent of mainstream smoke emitted from a burning cigarette, comprising treating mainstream smoke with a treatment composition in cigarette tobacco and/or a cigarette filter, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst, an essentially non-combustible finely divided porous particulate adjunct, and a precious metal.  
      In another aspect of the present invention, the use of a treatment composition for a cigarette paper/wrapper to reduce at least one constituent from a group of carbonyls and at least one constituent from a group of phenols of mainstream smoke from a burning cigarette, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In another aspect of the present invention, the use of a treatment composition in the manufacture of a cigarette paper/wrapper for a cigarette to reduce at least one constituent from a group of carbonyls and at least one constituent from a group of phenols of mainstream smoke from a burning cigarette, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In another aspect of the present invention, the use of a treatment composition for cigarette tobacco and/or a cigarette filter to reduce at least one constituent of mainstream smoke from a burning cigarette, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst, an essentially non-combustible finely divided porous particulate adjunct, and a precious metal.  
      In another aspect of the present invention, a method of smoking a cigarette comprising lighting the cigarette to form smoke and drawing the smoke through the cigarette to reduce at least one constituent from a group of carbonyls and at least one constituent from a group of phenols of mainstream smoke, wherein the cigarette comprises a treatment composition comprising, in combination, the oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In another aspect of the present invention, the use of a treatment composition in the manufacture of a low ignition propensity cigarette for reducing at least one constituent of mainstream smoke of a burning cigarette, the treatment composition comprising, in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct.  
      In what follows, all embodiments concerning the oxygen storage and donor metal oxide oxidation catalyst, an essentially non-combustible finely divided porous particulate adjunct, other metal oxides and precious metals, are envisaged as being applicable to all treatment compositions, uses of treatment compositions, methods involving treatment compositions, and methods of smoking described within the present specification.  
      For ease of description, whenever the term cigarette is used, it is understood not only to include smokable cigarettes but any form of wrapped smokable product, such as cigars or the like. Whenever the term cigarette paper/wrapper is used, it is understood to encompass combustible and non-combustible papers and the like which may be used on cigarettes, cigars and the like. The paper/wrapper may be used as a single layer of cigarette paper or multiple layers of cigarette paper. The paper/wrapper may be applied as the sole layer of cigarette paper or as a wrap over conventional cigarette paper of a cigarette.  
     DETAILED DESCRIPTION OF THE INVENTION  
      Although the treatment composition of this invention produces good results for reducing mainstream smoke constituents when used in a cigarette paper/wrapper, acceptable mainstream smoke treatment has also been realized when the treatment material is used in tobacco and/or a cigarette filter. This has been achieved by the use of a treatment composition in a cigarette comprising an oxygen storage and donor metal oxide oxidation catalyst, an adjunct and, optionally, a precious metal.  
      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 the lighted region and to this end, the smoke drawn from the mouth end may be further modified by ventilated cigarette paper or cigarette filter.  
      The term “sidestream” smoke refers to the mixture of gases given off from the end of a burning cigarette between puffs and is not directly inhaled by the smoker. Sidestream smoke is made up of visible components, as well as invisible gases.  
      Using the treatment composition, at least one constituent of mainstream smoke is reduced. Some of the constituents are as follows: carbonyls such as aldehydes and ketones, carbon monoxide, 1,3-butadiene, isoprene, acrolein, acrylonitrile, hydrogen cyanide, o-toluidine, 2-naphthylamine, nitrogen oxide, benzene, N-nitrosonornicotine, phenols such as catechol, benz(a)anthracene, benzo(a)pyrene, and mixtures thereof. More specifically, at least one of formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone (MEK), butyraldehyde, hydroquinone, resorcinol, catechol, phenol, o-cresol, m+p-cresol, 1,3-butadiene, isoprene, acrylonitrile, o-toluidine, benzene, and ammonia has been reduced using the treatment composition described. These constituents form part of the Hoffman analytes, which are recognized in the cigarette industry as describing a group of constituents in mainstream smoke. A complete listing of the Hoffman analytes is as follows: carbon monoxide; constituents from the group of phenols (e.g. catechol, phenol, hydroquinone, resorcinol, o-cresol, m+p-cresol); constituents from the group of carbonyls (e.g. formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, butyraldehyde, methyl ethyl ketone); ammonia; aromatic amines I (1-aminonaphthalene; 2-aminonaphthalene; 3-aminobiphenyl, 4-aminobiphenyl); aromatic amines II (o-toluidine, o-anisidine, aniline, m-toluidine); aza-arene; eugenol; hydrogen cyanide; metals I (nickel, cadmium, arsenic, lead, chromium, selenium); mercury; nitric oxide; nitrosamines (N-nitrosonomicotine, 4-(N-nitrosomethylamino) -1-(3-pyridyl)-1-butanone, N-nitrosoanatabine, N-nitrosoanabasine); PAHs (benzo[e]pyrene, naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, benzo[a] anthracene, chrysene, benzo(a)pyrene, indeno[1,2,3-cd]pyrene); pyridine; quinoline; 3-vinylpyridine; 1,3-butadiene, isoprene; acrylonitrile; benzene; toluene; and styrene. At least one Hoffman analyte is reduced using the treatment composition. In particular, when the treatment composition is used in or on the cigarette paper/wrapper of a cigarette, the reduction of at least one constituent from a group: of carbonyls and at least one constituent from a group of phenols of mainstream smoke from a burning cigarette can be achieved.  
      Although the mechanism for the treatment of carbon monoxide in mainstream smoke may not be fully understood, the principles behind the mechanism of the treatment of carbon monoxide in mainstream smoke also appear to be applicable to the treatment of other Hoffman analytes in mainstream smoke.  
      Depending on the amount of treatment composition in the cigarette paper/wrapper, one may design a cigarette which emits varying degrees of sidestream smoke. By increasing the amount of treatment composition in the cigarette paper/wrapper, one can reduce the visible sidestream smoke to a negligible amount and conversely, by decreasing the amount of treatment composition, one can increase the visible sidestream smoke to normal levels. At decreased amounts of the treatment composition, mainstream smoke is treated while visible sidestream smoke is apparent. By varying the amount of treatment composition in the cigarette paper/wrapper, one may design a cigarette having a selected level of sidestream smoke emission while still achieving the desired degree of mainstream smoke treatment.  
      The adjunct, as described in Applicant&#39;s International Patent Application WO 02/24005 (U.S. patent application Ser. No. 09/954,432), incorporated herein by reference, may be any suitable essentially non-combustible, finely divided particulate material which typically does not affect the flavour and taste of the mainstream smoke and does not give off any undesirable odours in the sidestream vapours. The particulate material is physically stable at the elevated temperatures of the burning cigarette coal. The adjunct may have a low surface area usually less than 20 m 2 /g and preferably 1 m 2 /g to 15 m 2  /g and most preferably 3 m 2 /g to 10 m 2 /g. It is understood for the low surface area materials the particulates are finely ground and are usually not porous. However, as the surface area increases towards 20 m 2 /g it is understood that the particles may be porous. Conversely the adjunct may also have a high surface area usually greater than 20 m 2 /g and at this level of surface area usually the particulate material is porous. The porous adjunct may have pores with an average diameter of less than 100 nm (1000 Å). In embodiments of the adjunct, the pores have an average diameter of less than 20 nm (200 Å), typically, the pores have an average diameter of 0.5 to 10 nm (5-100 Å). With zeolite based materials, the pores have an average diameter in the range of about 0.5 to 1.3 nm (5-13 Å). The porous adjunct may therefore provide adsorption sites, which retain certain mainstream smoke constituents which are catalytically converted into smaller molecules and released.  
      The particulate adjunct may have an average particle size of less than about 30 μm, less than about 20 μm or range from about 1 μm up to about 10 μm. Non-combustible materials may be porous clays of various categories commonly used in cigarette paper manufacture, such as the bentonite clays or treated clays having high surface areas. Non-combustible carbon materials may also be used including milled porous carbon fibres and particulates. Various metal oxides and/or carbonates may be used such as porous monolithic mineral based materials such as zirconium oxide, titanium oxides, magnesium oxide, aluminum oxide, cerium oxide, tin oxide, iron oxide, manganese oxide, calcium carbonate, zirconium carbonate, magnesium carbonate and mixtures thereof, metal oxide fibres such as zirconium fibres and other ceramics such as milled porous ceramic fibres and mixtures thereof In respect of cerium oxide, it is capable of functioning as a finely divided adjunct and as an oxygen storage and donor metal oxide oxidation catalyst.  
      The adjunct may also comprise high surface area highly sorptive materials which are non-combustible, inorganic finely divided particulate, such as molecular sieves which include zeolites and amorphous materials such as silica/alumina and the like. Typical adjuncts used are zeolites such as silicalites, faujasites X, Y and L zeolites, beta zeolites, Mordenite zeolites and ZSM zeolites. In certain embodiments, the adjuncts are zeolites such as hydrophobic zeolites and mildly hydrophobic zeolites which have affinity for hydrophobic and mildly hydrophobic organic compounds. The Zeolite materials provide a highly porous structure which selectively absorbs and adsorbs components of smoke. The highly porous structure generally comprise macropores amongst the particles and micropores within the particles which branch off of the macropores.  
      The zeolite materials may be characterized by the following formula: 
 
M m M′ n M″ p [aAlO 2 ·b SiO 2 ·cTO 2 ]
 
 wherein 
          M is a monovalent cation,     M′ is a divalent cation,     M″ is a trivalent cation,     a, b, c, n, m, and p are numbers which reflect the stoichiometric proportions,     c, m, n or p can also be zero,     Al and Si are tetrahedrally coordinated Al and Si atoms, and     T is a tetrahedrally coordinated metal atom being able to replace Al or Si,     wherein the ratio of b/a of the zeolite or the zeolite-like material, has a value of about 5 to 300 and the micropore size is within the range of about 0.5 to 1.3 nm (5 to 13 Å).        

      In typical embodiments, zeolites of the above formula have the specific formulas of faujasites ((Na 2 , Ca, Mg) 29 [Al 58 Si 134 O 384 ]·240 H 2 O; cubic), β-zeolites (Na n [Al n Si 64−n O 128 ] with n&lt;7; tetragonal), Mordenite zeolites (Na 8 [Al 8 Si 40 O 96 ]·24 H 2 O; orthorhombic), ZSM zeolites (Na n [Al n Si 96−n O 192 ]˜16 H 2 O with n&lt;27; orthorhombic), and mixtures thereof.  
      It is appreciated that various grades of the sorptive material may be used. This is particularly true with gradients of zeolites which can be custom designed to selectively adsorb, for example, high boiling point materials, mid boiling point materials and low boiling point materials. This can lead to layers of the zeolite composition where the oxygen storage and donor metal oxide oxidation catalyst may be dispersed throughout these layers. The layers may then be, for instance, bound on cigarette paper/wrapper for the tobacco rod by using a binder or an adhesive which may be, for example, polyvinylacetate, polyvinyl alcohol, carboxy methyl cellulose (CMC), starches and casein or soya proteins, and mixtures thereof.  
      The oxygen donor and oxygen storage metal oxide oxidation catalyst may be selected from the transition metal oxides (such as the group of metals from the Periodic Table consisting of groups VB, VIB, VIIB, VIII and IB metals), rare earth metal oxides, (such as scandium, yttrium, and lanthanide metal series, i.e. lanthanum) and mixtures thereof. It is appreciated that the catalyst may be in its metal oxide form or a precursor of the metal oxide which, at the temperature of the burning cigarette, is converted to a metal oxide to perform its catalytic activities. For example, a cerium catalyst precursor for ceria may be in the form of a cerium salt such as a cerium nitrate or other dispersible forms of cerium which are applied in solution or sol to the sorptive material and which is converted to cerium oxide at the high temperature of the burning cigarette to then function as a catalyst. For purposes of describing the invention, the term catalyst is intended to include any catalyst precursor.  
      In typical embodiments, the oxygen donor and oxygen storage metal oxide oxidation catalyst of the lanthanide metal oxides are oxides such as lanthanum, cerium, praseodymium, neodymium and mixtures thereof and the transition metal oxides are oxides of iron, copper, silver, manganese, vanadium, tungsten and mixtures thereof. More typically, oxides of cerium, praseodymium, iron or mixtures thereof are used.  
      The oxygen donor and oxygen storage metal oxide oxidation catalyst may be selected from a mixture of transition metal oxides (such as the group of metals from the Periodic Table consisting of groups IVB, VB, VIB, VIIB, VIII and IB metals) and rare earth metal oxides, (such as scandium, yttrium, and lanthanide metal series, i.e. lanthanum). Typical transition metal oxides used in the mixture are oxides of iron, copper, silver, manganese, titanium, zirconium, vanadium, tungsten and mixtures thereof.  
      It is appreciated that other catalysts may be used with the oxygen storage and oxygen donor type of catalyst. Such other catalysts include precious metals and metals from groups IIA, IVA and mixtures thereof. Examples include, for instance, tin, platinum, palladium and mixtures thereof.  
      Solid solutions of mixed oxygen donor and oxygen storage metal oxide oxidation catalysts, and optionally precious metals, can be prepared for use in the cigarette. In examples, the oxygen donor and oxygen storage metal oxide oxidation catalyst used may be cerium oxide in admixture with any one of the transition metal oxides such as zirconium. Some combinations of metal oxide(s) may include cerium/lanthanum mixed oxide, cerium/zirconium mixed oxide, cerium/zirconium/lanthanum mixed oxide, cerium/zirconium/ praseodymium mixed oxide, cerium/zirconium/lanthanum/praseodymium mixed oxide, cerium/zirconium/neodymium mixed oxide and mixtures thereof Some examples with precious metals include: cerium/zirconium mixed oxide/palladium, cerium/zirconium mixed oxide/zeolite/palladium, cerium/lanthanum mixed oxide/palladium, cerium/zirconium/lanthanum mixed oxide/palladium, cerium/zirconium/praseodymium mixed oxide/palladium, cerium/zirconium/lanthanum/praseodymium mixed oxide/palladium, cerium/zirconium/neodymium mixed oxide/palladium, cerium/lanthanum mixed oxide/platinum, cerium/zirconium mixed oxide/platinum, cerium/ zirconium/lanthanum mixed oxide/platinum, cerium/zirconium/praseodymium mixed oxide/platinum, cerium/zirconium/lanthanum/praseodymium mixed oxide/platinum, cerium/zirconium/neodymium mixed oxide/platinum, cerium/lanthanum mixed oxide/rhodium, cerium/zirconium mixed oxide/rhodium, cerium/zirconium/lanthanum mixed oxide/rhodium, cerium/zirconium/praseodymium mixed oxide/rhodium, cerium/zirconium/ lanthanum/praseodymium mixed oxide/rhodium, cerium/zirconium/ neodymium mixed oxide/rhodium and mixtures thereof.  
      When a precious metal is combined with the oxygen donor and oxygen storage metal oxide oxidation catalyst and incorporated into or onto the individual component of the cigarette, the temperature at which the oxygen donor and oxygen storage metal oxide oxidation catalyst releases oxygen is favorably affected. For example, as described in U.S. patent application Ser. No. 2003/0004060, hereby incorporated by reference, the precious metal, in combination with the oxygen storage and donor metal oxide oxidation catalyst, acts to lower the activation temperature at which the oxygen storage and donor metal oxide oxidation catalyst releases oxygen, as shown in Example 4.  
      The catalyst such as, cerium oxide, is used in combination with the adjunct material. In typical embodiments, the catalyst is substantially adjacent to the adjunct material. The mixture of catalyst and adjunct may be formulated in a variety of ways, for instance, as described in International Patent Application WO 02/24005. This can be achieved by co-mingling the oxygen storage and donor metal oxide oxidation catalyst in admixture with the adjunct, contacting a layer of the adjunct with a catalyst layer, coating the catalyst on the adjunct or impregnating the catalyst within or on the porous surfaces of the adjunct to bring about the desired surprising mainstream smoke control properties. It should be appreciated that many other constituents may be used in addition to the combination of the oxygen storage and donor metal oxide oxidation catalyst and the adjunct. For example, when porous cerium oxide is used as the oxygen storage and donor metal oxide oxidation catalyst and the adjunct, one need simply combine it with palladium or other precious metal.  
      The typical amounts of oxygen donor and oxygen storage metal oxide oxidation catalyst with the adjunct may range from about 1% to 75% by weight, more typically from about 10% to 70% by weight, and most typically from about 20% to 70% by weight of the oxygen donor and oxygen storage metal oxide oxidation catalyst based on the total equivalent oxygen donor and oxygen storage metal oxide oxidation catalyst and adjunct content.  
      Additional additives may be used to further enhance the treatment of the mainstream smoke or alter other characteristics of the cigarette. Such additional additives may be mixed in with the treatment composition or used elsewhere in the cigarette construction, providing, of course, that such additives do not appreciably impact negatively on the ability of the treatment composition to treat the mainstream smoke.  
      The composition may be formulated in a variety of ways which achieve co-mingling of the oxygen donor and oxygen storage metal oxide oxidation catalyst, such as cerium oxide, with the adsorptive material. For example, the adsorptive material may be sprayed with or dipped in a cerium salt solution such as cerium nitrate or cerium sol to impregnate the surface of the adsorptive material with cerium. Cerium oxide may be prepared as a separate fine powder which is mixed with the fine powder of the adsorptive material. In embodiments, the catalyst powders have an average particle size of less than about 30 μm, less than about 20 μm, or about 1.0 to about 5 μm to ensure intimate mixing and co-mingling of the materials. Catalyst activity may be improved by increasing the surface area of the catalyst particles. Hence, it may be desirable to use nanoparticles of catalysts, such as particles having an average particle size of about 5 nm to about 500 nm, as described in Philip Morris&#39;s International Patent Application WO 2004/041008.  
      As a general guide to selecting catalyst particle size and surface area, it is appreciated by one skilled in the art that the selected catalyst has a surface area which is such to ensure that the catalyst action sites are available to the mainstream smoke constituents. In keeping with the catalyst design, and as an alternative to smaller particle sizes, one may use larger particle sizes, for example, greater than 30 μm in certain embodiments, where the catalyst particles are porous, having surface areas in excess of 20 m 2 /g or even 100 m 2 /g. The larger porous particles have the ability to adsorb smoke constituents, catalytically convert them to smaller molecules and release them. These larger particles may be particularly useful in tobacco or cigarette filters providing that they are properly distributed to achieve the necessary degree of mainstream smoke oxidation.  
      It has been surprisingly found that the cerium oxide is one of the few metal oxides which can perform both functions, namely as the oxygen storage and oxygen donor catalyst and as well as the adjunct. The porous cerium oxide particles can be made with the high surface areas and having average particle sizes equivalent to the adjunct. The cerium oxide is used with the cigarette paper/wrapper, tobacco, and/or cigarette filter in a first amount as the catalyst and a second amount as the adjunct in the treatment composition. Such amounts of the cerium oxide correspond generally with the amounts used for the catalyst and adjunct in accordance with other aspects of the invention to make up the total loading.  
      The cerium may be formulated as a solution dispersion, such as cerium oxide sol, or the like and applied to the sorptive material such as zeolite. It is then dried and fired to provide cerium oxide particles fixed on the surfaces of the adsorptive material. When the cerium oxide particles are fixed to adjunct surfaces such as surfaces of zeolite, the average particle size may be less than about 1.0 μm. The relative amounts of cerium oxide fixed to the zeolite may range from about 1% to 75% by weight based on the total equivalent cerium oxide and zeolite content. Typical relative amounts of cerium oxide fixed to the zeolite may range from about 10% to 70% by weight based on the total equivalent cerium oxide and zeolite content.  
      One method for making the combination product of cerium oxide fixed on the surfaces of the zeolite is described in a co-pending application, U.S. Ser. No. 10/242,675, entitled A Process For Making Metal Oxide-Coated Microporous Materials, filed in the U.S. Patent Office on Sep. 13, 2002, the subject matter of which is incorporated herein by reference.  
      Although a detailed specification for the manufacture of the combination product is provided in the above application, for ease of reference, the method generally involves making a catalytic cerium oxide-coated zeolite particulate material having at least 1% by weight of cerium oxide coated on outer surfaces of the zeolite particulate material, based on the total equivalent cerium oxide and zeolite content. In one aspect, the method generally comprises the steps of: 
          i) combining an amount of a colloidal dispersion of cerium oxide hydrate with a compatible zeolite particulate material to form a slurry, the amount of the colloidal dispersion being sufficient to provide, when heat treated as per step (ii), greater than 20% by weight of the cerium oxide, the zeolite particulate material having an average pore size of less than 20 Å and the colloidal dispersion having an average particle size of at least 20 Å, to position thereby, the colloidal dispersion on the outer surfaces of the zeolite; and     ii) heat treating the slurry firstly, at temperatures below about 200° C. and secondly, above about 400° C., to fix the resultant cerium oxide on the outer surfaces of the zeolite particulate material, to provide a free flowing bulk particulate.        

      Alternatively to this method, the adjunct sorptive material may be dipped in a solution of cerium salt and dried and heat treated to form the cerium oxide on the surfaces of the sorptive material.  
      With respect to the precious metal, the precious metals are usually included in the treatment composition at levels up to about 5% by weight of the total weight of the treatment composition, typically from about 0.05% to about 1%. The precious metals may be selected from the group consisting of palladium, platinum, rhodium, iridium, ruthenium, gold and silver. Typical precious metals used are selected from the group consisting of palladium, platinum, and rhodium and mixtures thereof, more typically, palladium is used.  
      Synergistic effects of precious metals on the reduction of the amount of constituents in mainstream smoke have been surprisingly found in the combined use of oxygen donor and storage metal oxide oxidation catalyst, adjunct and precious metal. The cumulative effect of oxygen storage and donor metal oxide oxidation catalyst, adjunct and precious metal has been found to be more than the sum of the amount of reduction of mainstream smoke constituents due to a) oxygen storage and donor metal oxide oxidation catalyst and precious metal mixture plus b) an adjunct and precious metal mixture.  
      The treatment composition, optionally including the precious metal, may be applied to the cigarette paper/wrapper in various ways to reduce the amount of constituents in mainstream smoke. The treatment composition may be used as a filler in the manufacture of the cigarette paper/wrapper, impregnated in the cigarette paper/wrapper, or as a coating(s) or a layer(s) on the exterior or interior of the cigarette paper/wrapper. The cigarette paper/wrapper containing the treatment composition may be applied as an outer wrap over a cigarette having conventional cigarette paper.  
      The paper/wrappers described herein may be used as a single layer of cigarette paper/wrapper or multiple layers of cigarette paper/wrappers.  
      Reference to a normal or conventional cigarette, cigarette paper, or cigarette paper/wrapper fibres implies commercially available cigarettes, typically, having a porosity in the range of about 5 to about 50 Coresta units, sometimes as high as 110 to 120 Coresta units, and a conventional free-burn rate of about 3 to about 5 mm/min given conventional tobacco densities of about 0.20 to about 0.26 g/cc. Conventional cigarettes, at least in North America, have a circumference of about 20 to 30 mm, usually about 23 to 27 mm and a tobacco rod length of at least about 40 mm and preferably of about 55 mm, about 64 mm and about 74 mm, which has acceptable draw resistance.  
      When a cigarette paper/wrapper comprising the treatment composition is wrapped over and in substantial contact with cigarette paper of a cigarette, this arrangement permits the use of a conventional cigarette and when smoked, burns at conventional free-burn rates.  
      Other uses of the treatment composition include the incorporation of this composition into tobacco to reduce the amount of constituents in mainstream smoke. Incorporation of the treatment composition may take place at any time prior to the final packaging of the tobacco product. In the case of cigarette tobacco, the treatment composition may be incorporated before or after blending of the various tobaccos if, in fact, blended tobacco is employed. In addition, the treatment composition is dispersed throughout the treated tobacco and may be used in one or all of the blend constituents. Typically, the treatment composition is well dispersed throughout the tobacco so that it is uniformly effective during the entire period during which the tobacco composition is smoked. Alternatively, the treatment composition may be sprayed on to the tobacco rod as it is formed.  
      The weight proportions of the components described above for use in tobacco are usually within the following approximate weight ranges to provide useful tobacco products. The amount of the treatment composition added to the tobacco may be about 1 to about 15% by weight, preferably, about 1% to about 10% by weight based upon the weight of the tobacco.  
      The tobacco may be further processed and formed into any desired shape or used loosely (i.e. cigars, cigarettes, and pipe tobacco) in a manner well-known to those skilled in the tobacco art. Other conventional tobacco additive materials, such as flavourants and humectants may be used in the practice of the present invention without deviating from the scope thereof.  
      Other uses of the treatment composition to reduce the amount of constituents in mainstream smoke include the incorporation of the treatment composition into a filter. The treatment composition may be placed in a cavity within the filter of the cigarette and sealed. Concentric filters may also be used, wherein the treatment composition is incorporated into the filter layers or between the filter layers. Examples of concentric filters are described in Applicant&#39;s International Patent Application WO 98/16125.  
      In embodiments, the treatment composition may be simply sprayed onto either side or both sides of the cigarette paper/wrapper and absorbed into the paper, and/or may be sprayed onto the tobacco fibres and/or cigarette filter fibres. Alternatively, the composition may be extruded as a film to the surface of a tobacco rod, a filter, and/or the cigarette paper/wrapper and may be used as a single or multiple wrap. The treatment composition may be applied to a conventional cigarette on the exterior of the cigarette paper. Impregnation may also be used to impregnate the tobacco fibres, filter fibres and/or cigarette paper/wrapper with the treatment composition. For example, pressure rollers may be used to force the treatment composition into tobacco fibres, filter fibres and/or cigarette paper/wrapper to thereby impregnate constituents of the treatment composition therein.  
      It is also understood by one of skill in the art that various other coating processes including transfer coating processes, may be used for making the treatment paper of the invention. In the transfer coating process, Mylar™ sheet or other suitable continuous sheet may be used to transfer a coating composition from the Mylar™ sheet to the surface of the cigarette paper. This type of transfer coating is useful when the substrate sheet may not readily accept the roll coating of a composition due to physical strength characteristics of the paper or the like.  
      The composition may be introduced to the paper furnish as a slurry composition. Another alternative is to sandwich the treatment composition between paper layers to form a double cigarette paper wrap on tobacco rods. For example, the composition may be applied such as by a spraying technique on the interior of the outer paper or the exterior of the inner paper. Once the two papers are applied to the tobacco rod the composition as a layer is sandwiched between the two papers. Each paper may be of half of the thickness of conventional cigarette paper so that the double wrap does not add appreciably to the overall diameter of the cigarette as is readily handled by cigarette making machines. Also, the cigarette paper can be used with a coating, comprising the treatment composition, on the inner surface of the paper adjacent the tobacco rod.  
      The surprising activity of the treatment composition permits its use in cigarette papers/wrappers having a wide range of porosities; both combustible and non-combustible. The treatment composition may be used in papers with very low porosities of about 0.5 through to very high porosity of about 1,000 Coresta units. In certain embodiments, the porosities may be less than 200 Coresta units or in the range of about 30 to 60 Coresta units. It is appreciated that the paper/wrapper may be used as a single, double or multiple wrap. The paper/wrapper may be applied as an outer wrap over a cigarette having conventional cigarette paper. It is appreciated that depending upon the porosity, certain combinations of the catalyst and adjunct may work better than others.  
      As is appreciated by one of skill in the art, the aforementioned procedures for providing treatment composition within or onto a desired cigarette paper/wrapper, tobacco and/or filter may be varied with respect to the loadings provided and, with respect to the paper/wrapper, the number of wraps used on a tobacco rod. For example, two or more papers with various loadings of the composition, on both sides of the papers, may be used such that the loading to one side is lowered, making the coating application easier.  
      With any of these combinations, it has been surprisingly found that mainstream smoke constituents are reduced. It is particularly surprising that the application of the composition to the cigarette paper/wrapper can have such a substantial effect on mainstream smoke constituents.  
      It is appreciated that depending upon the manner in which the composition is used and applied to a cigarette, various processing aids and mixtures thereof may be required to facilitate the particular application of the treatment composition. Such processing aids include laminating materials such as polyvinylalcohol, starches, CMC, casein and other types of acceptable glues, various types of binding clays, inert fillers, whiteners, viscosity modifying agents, inert fibrous material such as zirconium fibres and zirconium/cerium fibres, such as described in U.S. application Ser. No. 10/242,676, entitled Zirconium/Metal Oxide Fibres, filed Sep. 13, 2002, the subject matter of which is incorporated hereby by reference. Penetrating agents may also be employed to carry the composition into the paper, tobacco and/or filter. Suitable diluents such as water are also used to dilute the composition so that it may be spray coated, curtain coated, air knife coated, rod coated, blade coated, print coated, size press coated, roller coated, slot die coated, technique of transfer coating and the like onto a conventional cigarette paper, tobacco and/or filter fibres.  
      The treatment composition is used normally as a water slurry of the composition. The slurry may be incorporated in the furnish of the paper in the paper making process, or is coated onto the paper, tobacco and/or filter by various coating processes or impregnated into the paper by various impregnating methods. The typical average particle size of the catalyst and adjunct for the slurry is in the range of about 1 μm to about 30 μm and more typically about 1 μm to about 5 μm.  
      Desirable loadings of the treatment composition onto or into the cigarette paper/wrapper or the like is preferably in the range of from about 2.5 g/m 2  to about 125 g/m 2 . Most preferably the loading is in the range of about 2.5 g/m 2  to about 100 g/m 2 . Expressed as a percent by weight, the paper may have from about 10% to 500% by weight and more typically about 10% to 400% by weight of the treatment composition. Typically, the upper end of the range applies to multiple papers/wrappers. Loadings for single paper/wrapper are, typically, from about 5% to 200% by weight and more typically about 10% to 100% by weight of the treatment composition.  
      The mixture of metal oxide(s) and optionally the precious metal is used normally as a water slurry. The make up of the dry composition which can be made into a slurry, may vary depending on its use as a paper coating, incorporation or impregnation.  
      In accordance with the present invention, at least one of the various cigarette components (tobacco, filter and cigarette paper/wrapper) of the present invention comprise the treatment composition to reduce at least one constituent in mainstream smoke. For instance, the treatment composition may be used in several different combinations of the cigarette components (ie. the cigarette paper/wrapper and filter may comprise the treatment composition, whereas the tobacco is conventional cigarette tobacco). Alternatively, all of the cigarette components may comprise the treatment composition.  
      With little or no adverse cytotoxic affect, the ability of the treatment composition to reduce at least one of the Hoffman analytes in mainstream smoke provides a desirable cigarette. This was confirmed by cytotoxicity tests and mutagenicity tests on the mainstream smoke. The cytotoxicity tests were done using the in vitro Neutral Red Uptake assay with the BALB/c 3T3 cell line and the mutagenicity tests were done using the in vitro AMES reverse mutation assay.  
    
    
     EXAMPLES  
      Cigarette Sample 100 (Control)  
      Cigarette sample 100 (control) was a conventional cigarette comprising Virginia-type tobacco blend, conventional cigarette paper/wrapper and filter. The cigarette was manufactured using a standard cigarette making machine, as known to one skilled in the art.  
      Cigarette Sample 101  
      Cigarette sample 101 was prepared using a single-incorporated paper/wrapper. The paper/wrapper has a 68 g/m 2  basis weight with approximately 43% treatment composition (e.g. 29 g/m 2 ). The remainder of the basis weight was flax. The treatment composition was prepared using about 44% ceria from ceria sol (from AMR Technologies, Inc. of Toronto, Canada)/56% Y-type zeolite CBV 720 (from Zeolyst International of Valley Forge, Pa., U.S.A..), the method for making this particular treatment composition is described in co-pending application, U.S. Ser. No. 10/242,675, entitled A Process For Making Metal Oxide-Coated Microporous Materials, filed in the U.S. Patent Office on Sep. 13, 2002, the subject matter of which is incorporated herein by reference. For example, cerium carbonate (50 g, 99.9% purity) containing 69.3% by weight cerium oxide equivalent was slurried with distilled water (0.1 L) and dissolved by adding nitric acid (38.4 ml; 16 M). The resulting neutral solution was boiled for a few minutes, filtered to remove traces of insoluble matter, and diluted to 1 L with water to give a cerous nitrate solution. A mixture comprising ammonium hydroxide (40 ml, 18 M), hydrogen peroxide (20 ml, “100 volume”) and water (160 ml) was added with stirring to the cerous nitrate solution prepared and maintained at 75° C. The resulting insoluble, dark brown cerium (IV) peroxide complex rapidly faded in colour and after the complete addition of the ammonium hydroxide/hydrogen peroxide mixture, a creamy-white precipitate of cerium (IV) hydroxide was obtained, having a pH of 7.0.  
      The precipitate was centrifuged and washed twice by stirring with successive 1 L volumes of distilled water. The separated precipitate was stirred with distilled water (750 ml) and nitric acid (12.5 ml of 16 M) to give a nitric acid/ cerium oxide mole ratio of 1. The resulting slurry was heated to about 70° C. for 15 minutes to deaggregate the cerium (IV) hydroxide and give a conditioned slurry. The pH of the conditioned slurry was less than 1. After cooling, the slurry was centrifuged and the residue was collected.  
      Using a scaled-up method of the above, 1.22 kg of the residue (a dispersible ceria gel) was made and stirred for 30 minutes with 5.5 L of demineralized water. The resultant colloidal dispersion contained 200 g/L of cerium oxide. The colloidal dispersion has a density of 1.15 g/ml and a pH of 1.8.  
      0.30 kg of a zeolite powder (Zeolyst™ CBV 720 obtained from Zeolyst International; pH 3 to 5) was added with stirring to 1.0 L of the cerium oxide colloidal dispersion. The thixotropic mixture (density 1.27 g/ml, pH 3.1) containing a nominal 44% by weight cerium oxide (based on the total equivalent cerium oxide and zeolite content) and 56% by weight zeolite (based on the total equivalent cerium oxide and zeolite content) was spray dried (an inlet temperature of 180° C. and an outlet temperature of 105° C.) to yield a free flowing gel powder.  
      About 0.22% by weight of palladium was also added to the treatment composition, which is based on the weight of the treatment composition. The treatment composition was introduced to a paper furnish as a slurry. The treatment composition in the furnish was stirred to form a slurry. The slurry was transferred in the conventional paper making manner and was laid as a layer on a moving conveyor to form the resultant incorporated cigarette paper. Once the paper was prepared, the paper was coated with calcium carbonate to improve the colour of the paper and to improve the ash. The cigarette sample itself was then prepared using the incorporated cigarette paper/wrapper and the same components (e.g. filter and tobacco blend) and manufacturing process as for the cigarette control sample 100.  
      Cigarette Sample 102  
      Cigarette sample 102 was prepared using Virginia-type tobacco blend, coated with the treatment composition. The cigarette itself had the same components (e.g. filter and conventional cigarette paper/wrapper) as for the cigarette control sample 100 and was prepared using the same manufacturing process as for the cigarette control sample 100. The treatment composition was a mixture of 44% ceria/zirconia (75/25) (from AMR Technologies, Inc. of Toronto, Canada) and 56% Y-type zeolite CBV 720 (from Zeolyst International of Valley Forge, Pa., U.S.A..) doped with 0.125% by weight of palladium, based on the weight of zeolite. About 7.6% by weight of the treatment composition (based on the weight of tobacco) was sprayed onto the tobacco blend in a conditioning cylinder.  
      Cigarette Sample 103  
      Cigarette sample 103 was prepared using Virginia-type tobacco blend, incorporated with the treatment composition. The cigarette itself had the same components (e.g. filter and conventional cigarette paper/wrapper) as for the cigarette control sample 100 and was prepared using the same manufacturing process as for the cigarette control sample 100. The treatment composition was prepared using about 44% ceria from ceria sol (from AMR Technologies, Inc. of Toronto, Canada)/56% Y-type zeolite CBV 720 (from Zeolyst International of Valley Forge, Pa., U.S.A..), the method for making this particular treatment composition is described in co-pending application, U.S. Ser. No. 10/242,675, entitled A Process For Making Metal Oxide-Coated Microporous Materials, filed in the U.S. Patent Office on Sep. 13, 2002, the subject matter of which is incorporated herein by reference, and is described above for cigarette sample 103. About 0.22% by weight of palladium was also added to the treatment composition, which is based on the weight of the treatment composition. About 8.1% by weight of the treatment composition (based on the weight of tobacco) was mixed with the tobacco blend in a conditioning cylinder.  
      The following examples are based on quantitative analyses performed in accordance with official methodologies prescribed by Health Canada.  
      These standard methods are:  
      Method T-104: Determination of selected carbonyls in mainstream tobacco smoke, prescribed by Health Canada, dated Dec. 31, 1999.  
      Method T-114: Determination of phenolic compounds in mainstream tobacco smoke, prescribed by Health Canada, dated Dec. 31, 1999.  
     Example 1  
      This example is directed to analysis of carbon monoxide in mainstream smoke with respect to a cigarette sample control (100) in comparison to a cigarette sample (101) with treatment composition incorporated into the cigarette paper/wrapper.  
      In carrying out the above analysis, sidestream smoke production was also analysed. The amount of sidestream smoke was quantified visually on a scale of 0 to 8, 0 being no sidestream smoke and 8 being sidestream smoke as generated by a conventional cigarette. Considerable experimentation in this area has revealed that there is an essentially linear relationship between sidestream smoke visual reading and the amount of tar remaining in the sidestream. Generally, when it comes to sidestream smoke control, a visual reading of about 2 or less is preferred. Although it is understood that there may be circumstances where a visual reading greater than 2 may be justified, for example, where the mainstream smoke reduction is the primary focus. In the remaining Example 3, sidestream smoke is correspondingly quantified.  
                               TABLE 1                                   Type of Cigarette   100 (Control)   101           Smoke   (mg per cigarette)   (mg per cigarette)                                                        Mainstream Smoke                   Constituents           Tar   5.7   3.6           Nicotine   0.67   0.37           Carbon Monoxide   4.9   4.1           Sidestream Smoke           Constituents           Visible Sidestream   8.0   2.0           Smoke                      
 
      Compared to the control, the treatment composition in the cigarette paper/wrapper is able to reduce the amount of tar whereas, in actual fact, the expectation is that the amount of tar would increase due to reduced porosity of the paper. Secondly, reduced porosity should produce a higher amount of carbon monoxide. The above test results show, contrary to expectations, that the treatment composition reduces the amount of carbon monoxide in mainstream smoke.  
     Example 2  
      This example is directed to analysis of the groups of carbonyl and phenol analytes in mainstream smoke with respect to a cigarette sample control (100) of Example 1 in comparison to a cigarette sample (101) of Example 1 with treatment composition incorporated into the cigarette paper/wrapper.  
                               TABLE 2                                       100 (Control)   101           Analyte   (μg per cigarette)   (μg per cigarette)                                        Group of Carbonyl Analytes                                 Formaldehyde   24.76   7.65           Acetaldehyde   292.96   146.75           Acetone   129.75   70.70           Acrolein   29.70   9.02           Propionaldehyde   23.41   11.60           Crotonaldehyde   23.58   7.74           MEK   29.08   11.13           Butyraldehyde   12.54   7.72           Total Carbonyls   565.79   272.30           Tar   5.7   3.6                 Group of Phenol Analytes                                 Hydroquinone   44.02   27.82           Resorcinol   3.15   0.82           Catechol   57.30   29.52           Phenol   12.53   3.85           o-Cresol   3.40   1.17           m + p-Cresol   5.05   1.92           Total Phenols   125.45   65.09           Tar   5.7   3.6                      
 
      The above results show that the treatment composition in the cigarette paper/wrapper substantially resuces selected Hoffman analytes in the mainstream smoke. Although the mechanism for the treatment of carbon monoxide in mainstream smoke is not fully understood, the principles behind the mechanism of the treatment of carbon monoxide in Example 1 also appear to be applicable to the treatment of the selected Hoffman analytes.  
     Example 3  
      This example is directed to analysis of carbon monoxide and the groups of carbonyl and phenol analytes in mainstream smoke with respect to a cigarette sample control (100) in comparison to a cigarette sample (102) with treatment composition coated on the tobacco and a cigarette sample (103) having tobacco incorporated with the treatment composition (e.g. treatment composition intermixed with the tobacco).  
      In carrying out the above analysis, sidestream smoke production was also analysed in the same manner as outlined in Example 1.  
               TABLE 3                          Mainstream Smoke Constituents                             Carbon   100 (Control)   102   103       Monoxide   (mg per cigarette)   (mg per cigarette)   (mg per cigarette)               Tar   5.7   4.3   4.5       Nicotine   0.67   0.55   0.62       Carbon   4.9   4.9   4.9       Monoxide                         Group of Carbonyl Analytes                                 100 (Control)   102   103       Analyte   (μg per cigarette)   (μg per cigarette)   (μg per cigarette)               Formaldehyde   24.76   23.75   18.34       Acetaldehyde   292.96   277.71   241.32       Acetone   129.75   112.12   130.71       Acrolein   29.70   29.75   35.12       Propion-   23.41   20.94   21.90       aldehyde       Crotonaldehyde   23.58   23.81   20.61       MEK   29.08   27.07   28.28       Butyraldehyde   12.54   11.75   16.28       Total   565.79   526.91   512.56       Carbonyls       Tar   5.7   4.3   4.5                         Group of Phenol Analytes                                 100 (Control)   102   103       Analyte   (μg per cigarette)   (μg per cigarette)   (μg per cigarette)               Hydroquinone   44.02   37.85   46.93       Resorcinol   3.15   2.44   2.82       Catechol   57.30   46.51   55.29       Phenol   12.53   9.31   11.11       o-Cresol   3.40   2.59   2.88       m + p-Cresol   5.05   3.86   4.74       Total Phenols   125.45   102.56   123.77       Tar   5.7   4.3   4.5                         Sidestream Smoke Constituents                                 100 (Control)   102   103           (mg per cigarette)   (mg per cigarette)   (mg per cigarette)               Visible   8.0   8.0   8.0       Sidestream       Smoke                  
 
 Compared to the control, the treatment composition in the tobacco reduced the amount of tar. It would be expected with the reduction of tar, due to the catalytic oxidation by the oxygen storage and donor metal oxide oxidation catalyst, that there would be a corresponding increase in the amount of carbon monoxide, whereas, in actual fact, the amount of carbon monoxide is essentially the same. This would indicate an overall reduction in the amount of carbon monoxide in mainstream smoke given that the amount of carbon monoxide did not increase relative to the control. 
 
      Correspondingly, selected Hoffman analytes would also be expected to increase with the reduction of the amount of tar due to the catalytic oxidation by the oxygen storage and donor metal oxide oxidation catalyst. The above results show that the treatment composition in the tobacco actually reduces the amount of selected Hoffman analytes in the mainstream smoke because the overall amount is slightly reduced.  
     Example 4  
     TPR Method for Oxygen Storage Capacity Measurement  
      Methodology  
      Oxygen Storage Capacity (OSC) of a treatment material can be quantitatively measured using Temperature Programmed Reduction (TPR) method. The treatment material is exposed to a continual flow of H 2 /N 2  gas mixture. The removal of H 2  from the gas stream as it reacts with oxygen released from the treatment material is measured as a function of temperature. The OSC of the treatment material is calculated from the measured quantity of H 2  in the gas stream consumed during the reduction reaction. The OSC is listed in Table 4.  
      The oxygen storage capacity is reported in μmol O 2 /g powder, and is reported at certain temperatures to provide information concerning the efficiency of oxygen release and utility of the material for a particular application. The temperatures of the cigarette wrapper at the location of the burn zone is about 300° C. on the outside of the paper and about 550° C. just underneathe the paper during cigarette free burn. The temperature at about 900° C. represents the temperature in the burn zone during cigarette puff.  
                               TABLE 4                           OSC*   OSC   OSC   OSC           300° C.   550° C.   900° C.   Total           (μmol of   (μmol of   (μmol of   (μmol of       Composition   O 2 /g)   O 2 /g)   O 2 /g))   O 2 /g)                                                    75% CeO 2 /25% ZrO 2     2   284   866   1196       75% CeO 2 /25% ZrO 2 /Pd   563   729   1047   1368       75% CeO 2 /12.5% ZrO 2 /   0   144   624   889       12.5% Pr       75% CeO 2 /12.5% ZrO 2 /   442   711   1054   1373       12.5% PrOy/Pd       75% PrOy/25% ZrO 2     6   265   790   816       75% PrOy/25% ZrO 2  w/   292   1124   1253   1253       Pd       CBV 720 Zeolite/Pd   31   89   145   300       56% CBV 720 Zeolite/Pd   266   532   840   1374       and 44% CeO 2 /ZrO 2 /       Pd***       56% CBV 720 Zeolite   5   332   683   979       and 44% CeO 2 ****       56% CBV 720 Zeolite/Pd   105   502   758   1075       and 44% CeO 2 ****       30% Nanocat ™**/70%   7   679   2110   3769       alumina       30% Nanocat ™/70%   248   810   2276   3759       alumina/Pd       10% Fe 2 O 3 /90% alumina   3   159   285   360                 *OSC = Oxygen Storage Capacity            **Nanocat ™ = NANOCAT Superfine Iron Oxide (SFIO) from MACH I, Inc., King of Prussia, PA            ***Admixture            ****Ceria is coated on the surface of the zeolite             
 
 These examples show the impact of the presence of precious metals on lowering the activation temperature for release of oxygen. For instance, with ceria/zirconia/Pd versus ceria/zirconia, significantly greater amounts of oxygen is released at 300° C. and 550° C., thus, indicating superior treatment of the mainstream smoke constituents when a precious metal, such as palladium, is used. Corresponding comparisons may be drawn for other combinations, such as 56% CBV 720 Zeolite/Pd and 44% CeO 2  versus 56% CBV 720 Zeolite and 15 44% CeO 2 . 
 
     Example 5  
     Carbon monoxide removal efficiencies of treatment materials  
      Methodology  
      The capability of the treatment material to remove carbon monoxide can be quantitatively measured in a reaction chamber on a synthetic gas test bench. The treatment material is applied on a honeycomb substrate, and the coated substrate is placed in a heated reaction chamber. The treatment material is exposed to a continuous flow of carbon monoxide gas mixture as described in Table 5. The removal of carbon monoxide from the gas stream is measured quantitatively (using a (Infrared) carbon monoxide analyzer) as the carbon monoxide is oxidized over the treatment material to form CO 2 . The carbon monoxide removal efficiencies of each of the treatment materials at temperatures of 260° C. and 316° C. are shown in Table 6. These removal efficiencies further confirms the reduction of carbon monoxide in mainstream smoke, as established in Example 1.  
               TABLE 5                          Flue Gas Composition and Flow Rates                                                                               Air   58.2           Nitrogen   11.6           Carbon Dioxide   2.4           Water   8.1           Carbon Monoxide (8,253 ppm/   0.75           N 2 )                      
 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                   
               
               
                 CO Removal Efficiencies of the Treatment Materials 
               
            
           
           
               
               
               
               
            
               
                   
                 
                   
                 
                 
                   
                 
                 
                   
                 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 56 CVB 720 - 44 Ce/Zr 
                 2.0 
                 2.0 
               
               
                   
                 56 CVB 720 - 44 Ce/Zr w/Pd 
                 6.1 
                 7.1 
               
               
                   
                 56 CBV 720 w/Pd - 44 Ce/Zr 
                 51.0 
                 56.1 
               
               
                   
                 56 CBV 720 w/Pd - 44 Ce/Zr w/Pd 
                 70.4 
                 76.5 
               
               
                   
                   
               
            
           
         
       
     
      Although preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.