US20030005940A1

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Publication number: US20030005940A1
Application number: US10/233,876
Authority: US
Inventors: Alexander Dyakonov; David Grider
Original assignee: Individual
Current assignee: Lorillard Licensing Co LLC
Priority date: 2000-11-28
Filing date: 2002-09-03
Publication date: 2003-01-09
Also published as: AU2002220121A1; WO2002043514A1; WO2002043514A9

Abstract

A smoking article includes a tobacco column, a wrapper and a carbon monoxide pump. The pump includes a separator, an adsorbent for carbon monoxide downstream from said separator and may include a catalyst for oxidizing carbon monoxide to carbon dioxide and venting holes adjacent to the adsorbent. In use, the carbon monoxide pump selectively diverts carbon monoxide from main stream combustion products, the separator impedes the entry of large molecules into the carbon monoxide pump, the catalyst at least partially oxidizes the carbon monoxide to carbon dioxide and the venting holes provide an alternative path for the diverted carbon monoxide and the oxidized carbon monoxide to check or reduce carbon monoxide inhalation by a smoker.

Description

CLAIM TO THE BENEFIT OF A PRIOR UNITED STATES APPLICATIONS

The present application is a continuation-in-part application of Ser. No. 09/723,585 filed Nov. 28, 2000, the disclosure of which is hereby incorporated by reference herein in its entirety.[0001]

BACKGROUND OF THE INVENTION

The present invention relates generally to a smoking article and, more particularly, to a carbon monoxide pump for removing carbon monoxide from main stream smoke during the combustion of a smoking article.[0002]

Investigators have been trying now for about twenty years to find ways to lower the amount of carbon monoxide experienced by smokers when main stream smoke is inhaled. One of the issues with respect to carbon monoxide is the amount of carbon monoxide actually contained or produced by a smoking article. For example, an average amount of carbon monoxide produced by a smoking cigarette is as high as about 10-15 milligrams (mg). To adsorb this amount of carbon monoxide would require a very large amount of adsorbent for carbon monoxide if it was all intended to be trapped by such an adsorbent. This is impractical and cost prohibited.[0003]

An alternative approach to adsorbing carbon monoxide is to oxidize it, for example, by the catalytic oxidation to carbon dioxide. A difficulty with this approach is that the temperature of the main stream smoke is substantially that of the environment. These low temperatures make it difficult to oxidize carbon monoxide to carbon dioxide even when using a catalyst.[0004]

Thus, there remains a need for a method and apparatus for carbon monoxide reduction in cigarette smoke.[0005]

SUMMARY OF THE INVENTION

The present invention fulfills this need by providing a smoking article including a tobacco column; a wrapper surrounding the tobacco column; and a carbon monoxide pump. The pump includes a separator, an adsorbent for carbon monoxide downstream from said separator and may include a catalyst for oxidizing carbon monoxide to carbon dioxide. In use, the carbon monoxide pump selectively diverts carbon monoxide from main stream combustion products, the separator impedes the entry of large molecules into the carbon monoxide pump, the catalyst at least partially oxidizes the carbon monoxide to carbon dioxide and the venting holes provide an alternative path for the diverted carbon monoxide and the oxidized carbon monoxide to reduce inhalation by a smoker. In a preferred embodiment, venting holes adjacent to the adsorbent to facilitate the further diversion of carbon monoxide from main stream smoke.[0006]

The catalyst may be at least one of a transition metal, an oxide of a transition metal, and a transition metal and an oxide of a transition metal, such as any one of a rare earth metal, a platinum group metal, their alloys, their mixtures and combinations thereof. Some transition metals that may work well include at least one of copper, cobalt, iron, silver, nickel, palladium.[0007]

Applicants have found that at least silver, its alloys, mixtures including silver and combinations thereof and, preferably, with silver in the form of an oxide work satisfactorily. Also, applicants have found that at least one of silver and palladium, their alloys, their mixtures and combinations thereof and, preferably, with silver in the form of an oxide of silver work satisfactorily. Further, applicants have found that at least nickel, its alloys, mixtures including nickel and combinations thereof and, preferably, with nickel in the form of an oxide of nickel work satisfactorily. Moreover, applicants have found that at least one of copper and palladium, their alloys, their mixtures and combinations thereof and, preferably, in the form of a Wacker type catalyst and, more preferably, in the form of a modified Wacker type catalyst work well.[0008]

In an embodiment, the CO pump includes at least one additional filter element, preferably cellulose acetate. A catalyst may be distributed through the at least one additional filter element.[0009]

In the vicinity of the adsorbent, the concentration of carbon monoxide is increased, thereby increasing the flux of carbon monoxide from the adsorbent. The adsorbing is momentary, preferably for between about 0.1 and about 10 seconds.[0010]

In a preferred embodiment, the separator is a molecular sieve. To that end, the effective aperture size is selected to be large enough to permit carbon monoxide to pass while at the same time preventing larger molecules from entering. Applicants believe that an effective aperture size from about 3 angstroms (Å) and greater will permit carbon monoxide to enter while a the same time an effective aperture size is up to about 9 angstroms (Å) will prevent certain larger molecules from entering. Alternatively if there is any hydrolyzation anticipated, a good starting point may be an effective aperture size from about 5 angstroms (Å) and greater may permit carbon monoxide to enter while at the same time an effective aperture size is up to about 9 angstroms (Å) will prevent certain larger molecules from entering. The molecular sieve may exhibit properties of an adsorbent.[0011]

The molecular sieve may be any one of a zeolite, whether occurring in nature, or synthetic or combination thereof, and an oxide. The oxide may be an oxide of at least one of silicon, aluminum, magnesium, their mixtures and their compounds. Also, the oxide may be a dehydrated oxide, such as an oxide of aluminum. Alternatively, the oxide may be amorphous.[0012]

In a preferred embodiment, the adsorbent is a zeolite such as an oxide, more preferably, at least one of silicon, aluminum, magnesium, their mixtures and their compounds. A dehydrated oxide, particularly of aluminum has been found to be effective. An amorphous oxide may also work.[0013]

In a preferred embodiment, the adsorbent is a support for the catalyst. However, anyone of the one of the separator, the adsorbent, and the separator and the adsorbent may be a support for the catalyst.[0014]

Accordingly, one aspect of the present invention is to provide a smoking article including a tobacco column, a wrapper surrounding the tobacco column; and a carbon monoxide pump. The carbon monoxide pump may include a separator and an adsorbent for carbon monoxide downstream from said separator. The separator may impede the entry of large molecules into the carbon monoxide pump while permitting the adsorbent to accumulate the carbon monoxide from main stream combustion products. When the carbon monoxide pump is aligned with the tobacco column so as to selectively divert carbon monoxide from main stream combustion products prior to inhaling by a smoker.[0015]

Another aspect of the present invention is to provide a carbon monoxide pump for use in a smoking article including a tobacco column and a wrapper surrounding the tobacco column. The carbon monoxide pump includes a separator, an adsorbent for carbon monoxide downstream from said separator; and a catalyst. When placed adjacent to the tobacco column, the carbon monoxide pump selectively diverts carbon monoxide from main stream combustion products by having the separator to impede the entry of large molecules into the carbon monoxide pump while permitting the adsorbent to accumulate the carbon monoxide from main stream combustion products and the catalyst at least partially oxidizes the carbon monoxide to carbon dioxide prior to being inhaled by a smoker. Still another aspect of the present invention is to provide a smoking article including a tobacco column; a wrapper surrounding the tobacco column; and a carbon monoxide pump. The pump includes a separator, an adsorbent for carbon monoxide downstream from said separator; a catalyst for oxidizing carbon monoxide to carbon dioxide, and venting holes adjacent to the adsorbent. In use, the carbon monoxide pump selectively diverts carbon monoxide from main stream combustion products by having the separator to impede the entry of large molecules into the carbon monoxide pump while permitting the adsorbent to accumulate the carbon monoxide from main stream combustion products, the catalyst at least partially oxidizes the carbon monoxide to carbon dioxide and the venting holes providing an alternative path for the diverted carbon monoxide and the oxidized carbon monoxide to check inhalation by a smoker.[0016]

The invention also provides a mouthpiece for a smoking article including a fitting to receive a smoking article, and a carbon monoxide pump including an adsorbent for adsorbing carbon monoxide, wherein the carbon monoxide pump is positioned with respect to the smoking article so as to selectively divert carbon monoxide from main stream combustion products prior to inhaling by a smoker.[0017]

These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.[0018]

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a smoking article according to the present invention;[0019]

FIG. 1B is an exploded view of the smoking article of FIG. 1A;[0020]

FIG. 2 is a schematic of a tobacco column adjacent to a selective carbon monoxide pump according to the present invention;[0021]

FIG. 3 is a block flow diagram for a carbon monoxide pump according to the present invention;[0022]

FIG. 4 is a partial perspective view of a mouthpiece according to the invention;[0023]

FIG. 5 shows retention time of an about 1 ml about 2%CO in He pulse in an about 10 ml zeolite bed at about ambient temperature against about 3, 4, 5 and 9 Å pore size zeolites equilibrated with about 60% humidity room air (o) and annealed at about 300° C. for about 10 hrs (*) prior to injection;[0024]

FIG. 6 shows retention time of CO (o) and N[0025]₂(Δ) pulses in an about 5 Å zeolite vs. time elapsed from purging of dry zeolite with an about 60% humid air for about 1 hour, the other experiment conditions are in FIG. 5;

FIG. 7[0026]ashows concentration profiles of CO and CO₂during CO oxidation on air-dry (PdCl₂+CuCl₂)/C catalyst at about ambient temperature with about 50 ml/min (about 3% CO+12% O₂+He) gas mixture passing through about 1 g of catalyst;

FIG. 7[0027]bshows the concentration profiles of water and O₂during CO oxidation on air-dry (PdCl₂+CuCl₂)/C catalyst at about ambient temperature with about 50 ml/min (about 3% CO+12% O₂+He) gas mixture passing through about 1 g of catalyst;

FIG. 8[0028]ashows concentration profile of the outlet gas after the 1^stpulse of about 1 ml CO through (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst at about ambient temperature in an about 100 ml/min flow of about 10%O₂in He;

FIG. 8[0029]bshows concentration profile of the outlet gas after the 7^thpulse of about 1 ml CO through (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst at about ambient temperature in an about 100 ml/min flow of about 10%O₂in He;

FIG. 8[0030]cshows concentration profile of the outlet gas after the 42^ndpulse of about 1 ml CO through (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst at about ambient temperature in an about 100 ml/min flow of about 10%O₂in He;

FIG. 9[0031]ashows profiles of the catalyst temperature during CO oxidation in a series of pulses of about 1 ml CO pulses through (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst at ambient temperature in a about 100 ml/min flow of 10%O₂in He;

FIG. 9[0032]bshows the integral value of the heats of CO during CO oxidation in a series of pulses of about 1 ml CO pulses through (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst at ambient temperature in a about 100 ml/min flow of 10%O₂in He;

FIG. 10[0033]ashows concentration profiles of the outlet gas after the 1^stpulse of about 1 ml CO through the dehydrated (PdCl₂+CuCl₂+Cu(NO3)2)/C catalyst under the experimental catalysis conditions described in FIG. 9;

FIG. 10[0034]bshows concentration profiles of the outlet gas after the 15^thpulse of about 1 ml CO through the dehydrated (PdCl₂+CuCl₂+Cu(NO₃)₂)/C catalyst under the experimental catalysis conditions described in FIG. 9;

FIG. 11[0035]ashows the removal of CO from mainstream smoke by a freshly prepared partially reduced and dehydrated Pd/Cu/C catalyst;

FIG. 11[0036]bshows the removal of CO from mainstream smoke by the Pd/Cu/C catalyst of FIG. 11aafter aging; and

FIG. 12 shows the temperature dependence of CO oxidation on Pd/9 Å zeolite.[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in general and FIG. 1 in particular, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. As best seen in FIGS. 1A and 1B a smoking article includes a[0038]

wrapper

12 surrounding atobacco column14 adjacent tocarbon monoxide pump16. Preferably, thepump16 selects carbon monoxide for diversion from main stream smoke. A further feature of the embodiment shown in FIG. 1 is the presence of venting holes18. As best seen in FIG. 1B, which is an exploded view of the smoking article in FIG. 1A, thewrapper12 surroundstobacco column14. As best seen in FIGS. 1B and 2, the selectivecarbon monoxide pump16 may be placed adjacent to, but not necessary abutting thetobacco column14. Typically it is aligned with the tobacco rod so that smoke from the tobacco combustion passes through thepump16. Other paths that expose the smoke to the pump may be used.

Additionally, as seen in FIG. 2, at least one[0039]

additional filter element

24 may be included in thesmoking article10. Although FIG. 2 depicts the selectivecarbon monoxide pump16 between twoadditional filter elements24, there may be a singleadditional filter element24. In such case, the at least onefilter element24 may be at either between thetobacco column14 and the selectedcarbon monoxide pump16. Alternatively, thecarbon monoxide pump16 may be between thetobacco column14 and the at least oneadditional filter element24. Thefilter element24 is typically of a conventional filter material such as cellulose acetate.

In operation, the selected[0040]

carbon monoxide pump

16 diverts carbon monoxide from main stream smoke to, for example, side stream smoke. A block diagram of the pump's operation is seen in FIG. 3. Starting at the top of FIG. 3, after asmoking article10 including thecarbon monoxide pump16 is lit, a smoker draws on the article from the filtered end. As the smoker draws on thesmoking article10, the combustion products are drawn through thecarbon monoxide pump16 for diverting carbon monoxide from the main stream smoke.

In an embodiment having a catalyst, the carbon monoxide diverted from the combustion products interacts with the catalyst and is oxidized to carbon dioxide. When venting holes[0041]18 are placed proximate to the carbon monoxide pump, the carbon dioxide is expressed through the venting holes18 and inherent pores in the wrapping paper around thecarbon monoxide pump16. The inclusion of ventingholes18 proximate to thecarbon monoxide pump16 and the inherent porosity provide a passage for the oxidized carbon monoxide, which is carbon dioxide, to be expressed from smoking article. In embodiments having no venting holes18, inherent pores within the paper provide a path for the expression of oxidized carbon monoxide. Carbon dioxide, generated from carbon monoxide, may also remain in the main stream smoke, providing no harm to the smoker.

In an alternative embodiment, having no catalyst, the[0042]

carbon monoxide pump

16 includes an adsorbent material. In this embodiment, as the main stream smoke passes over the adsorbent material, carbon monoxide is adsorbed from the main stream smoke onto the adsorbent material. During the delay between the current puff and the successive puff, which may be called an inter-puff period, the concentration of carbon monoxide increases in gas phase within the adsorbent material due to its desorption. The higher concentration of the carbon monoxide in the vicinity of the adsorbent material creates a driving force that increases the flux of carbon monoxide from the adsorbent material so that it exits holes18 proximate to thecarbon monoxide pump16.

As best seen in FIG. 3, the drawing, diversion and expression cycles continue during the consumption of the smoking article and in this manner, the amount of carbon monoxide inhaled by the smoker is substantially reduced.[0043]

The following examples provided to give a better understanding of the invention and its operation through a discussion of the synthesis, testing and characterization. The examples are in no way meant to limit the scope of the claimed invention.[0044]

EXAMPLE 1

Gas chromatographic analysis using a Model No. 6890, manufactured by Hewlett Packard, and an infrared CO sensor, manufactured by Filtrona, Inc., were used to determine the gas phase content of cigarette smoke under standard smoking conditions using a filling machine, manufactured by Filamatic, Inc., reconstructed to a smoking machine. As part of this analysis, the removal of CO from the gas was studied using an artificial mixture comprising helium with about 2% carbon monoxide by volume. About 1% by volume nitrogen was added to this mixture as an internal standard. Catalytic oxidation of CO was also studied using a mixture of helium, about 2% CO by volume, and about 13% oxygen. The above concentrations were prepared to simulate the average characteristics of tobacco smoke.[0045]

During analysis, the gas mixture was passed through the an about 2 milliliter (ml) GC gas loop, manufactured by Hewlett Packard, at about atmospheric pressure. The adsorbent to be studied was loaded into a stainless steel tube reactor. Adsorption was then studied by injecting the content of the gas loop into a pure helium flow of about 200 ml/min rate; the CO mixture with the carrier gas was then passed through the adsorbent in the reactor. The resultant gas was then passed to the GC for analysis. The reactor was maintained at about room temperature during these experiments. The reactor was also used to pre-treat solid adsorbent samples at elevated temperatures.[0046]

Aluminum oxide was tested for CO adsorption application because of its Lewis acidity; this property is known to promote CO chemisorption. The experimental results showed that fresh alumina is inactive in adsorption of CO at about room temperature. It is believed that the equilibration of the ambient atmosphere with the alumina surface blocks any CO active adsorption sites. For example, water molecules from the ambient atmosphere may occupy the CO active adsorption sites.[0047]

Heating of alumina (Al[0048]₂O₃) to about 300-350° C. in air provided an improvement in CO. If water molecules occupy the CO active adsorption sites, a dehydration (e.g., desorption of water molecules) of the CO adsorption sites may explain the increased activity after heat treating. Applicants believe that the CO adsorption property of alumina may be enhanced by altering the surface structure of alumina by for example making it more irregular, as for example, in zeolites.

EXAMPLE 2

Zeolites ranging in aperture size from about 3 to about 9 angstroms (Å) were applied in a study of CO adsorption from a pulsed gas. A fixed bed reactor, filled with zeolite, produced delays in the CO pulse; these delays resulted from a relatively weak adsorption. Size-selective dry molecular sieves created larger delay times when a 5 Å aperture size approximately matched the diameter of CO molecule.[0049]

It was determined that the high affinity of zeolites for water reduces the CO trapping activity of about 5 Å zeolite. An effective decrease in the zeolite pore sizes caused by the adsorption of water molecules appears to initiate this reduction. Experiments supported this idea, showing that a hydrated about 9 Å zeolite possessed substantially the same CO adsorption activity as that of an about 5 Å dehydrated sample. Results also suggest that zeolites with a pore size of about 5 Å or greater may be used as a starting material to develop a carbon monoxide pump that diverts CO from main stream smoke.[0050]

EXAMPLE 3

An Ag[0051]₂O/ about 5 Å zeolite and an Ag₂O/about 9 Å 13×zeolite catalyst/adsorbents were prepared. About 5 grams (g) of silver nitrate were dissolved in about 15 ml of an about 10M NH₄OH solution that was then combined with water for dilution to about 50 ml. About 20 g of about 0.4 to about 0.8 millimeter (mm) beads of a zeolite were added and allowed to remain overnight for a silver exchange. Each zeolite mixture was shaken frequently for about the first hour to remove evolved air. The catalyst was thoroughly washed with about 2L of water, dried for about 2 hours in air at about 60° C. and overnight at about 150° C. to decompose [Ag(NH₃)₂]NO₃. After this treatment the resulting light-yellow catalyst was stored in a jar.

The removal of CO from a gas was studied using freshly prepared samples in the reactor and the gas mixtures described in Example 1. About 300 milligrams (mg) of each CO pump material were loaded in a filter. Experimental results showed reductions of CO in main stream smoke as high as about 50-60% by volume.[0052]

EXAMPLE 4

Catalyst/adsorbent samples comprising Ag[0053]₂O-on-about 13×zeolite (about 9 Å) from Lancaster, and CP861E (about 7 Å) and CBV5524G (about 5 Å) from Zeolyst International were prepared substantially as described in Example 3. Atomic absorption analyses using a Spectr AA-100, manufactured by Varian, provided the concentrations of silver in the samples. These concentrations are summarized in Table 1 and the corresponding CO removal activities are summarized in Table 2.

TABLE 1


Concentration of Silver in Zeolite-Supported
Catalysts/Adsorbents from AA Analysis Data.

Sample	Support	% silver

1	13X zeolite (Lancaster)	8.5
2	CBV5524G (NN 2..4 are from Zeolyst)	4.0
3	CP861E (exchanged/milled/sieved)	10.0
4	CP861E (milled/sieved/exchanged)	7.8

Also, zeolites containing silver showed high activity in the catalytic oxidation of CO at higher temperatures. A study of the kinetics of oxidation of CO on silver oxide and a partially reduced silver catalyst revealed that silver catalysts reduced at about 110-150° C. were more active in oxidation of CO, and may provide about 70% removal of CO from main stream smoke. However, applicants believe that an excessively active catalyst may provide poor CO removal because of its irreversible deactivation by of other combustion products[0054]

TABLE 2


CO Removal from Main stream Smoke by Modified Cigarette
Filters, Containing Ag/zeolite CBV5524G (about 5Å)

Sample	Filter and Cigarette	% CO removed

1	Ag₂O/Z in vented filter	about 60
2	#1, reduced CO at about 120° C.	about 0
3	Ag₂O/Z in non-vented filter	about 22
4	Ag₂O/Z in tobacco	about 37

The results summarized in Table 3 indicate that a similar treatment of Ag/zeolite at about 120° C. in a reducing gas containing CO may led to an increase in CO removal from about 50 to about 71%, when zeolite as large as about 9 Å was used. Even after about 3 hours in humid room air, CO removal activity was not decreased and was measured as at about 81%. These results were confirmed when zeolite CP861E with an aperture size of about 7 Å was used. Corresponding data are summarized in Table 5.[0055]

As indicated by the results summarized in Table 3, a higher reduction temperature of about 150° C. does not further improve the performance of a catalyst compared to the sample, heat-treated at 120° C. These results imply that a partial reduction of silver in a Ag/zeolite adsorbent/catalyst may be a useful treatment, positively affecting the CO removal effectiveness. CO removal conditions however, must be carefully predetermined and controlled to avoid an over-reduction of silver.[0056]

As the results summarized in Table 2 shows, an about 5 Å zeolite, used in a non-vented cigarette, provides a lower degree of CO removal of about 22%. Also, the results indicate that the performance of this CO pump material may be slightly improved when Ag/zeolite material is mixed with tobacco rather than placed in a filter. Applicants believe this occurs since CO concentrated on an adsorbent during a puff is diffused out of the cigarette between puffs. Diffusion of CO through the porous cigarette paper in the case of an adsorbent mixed into the tobacco may be faster than that through a filter paper of a vented CO pump.[0057]

The results summarized in Table 6 indicate that venting holes in the CO pump as well as a thinner paper, facilitate the removal of CO from main stream smoke (e.g., an about 7 Å zeolite, modified with silver, was used in a vented and a CO pump). The effectiveness of CO removal was found to be about 73% and about 27% respectively.[0058]

The results of Table 3 show that an Ag/zeolite 13×-based materials did not completely lose its activity after about one cigarette smoked. These materials retained enough activity to provide about 30% CO removal from a second cigarette. This may allow less material in a CO pump.[0059]

TABLE 3


CO Removal from Main stream Smoke by
Modified Vented Cigarette Filters
Containing Ag/zeolite 13X (about 9Å).

Sample	Filter	% CO removed

5	Ag₂O/Z	about 50
6	#5, reduced CO at 120° C.	about 71
7	#6 oxidized 3 hrs in air at room T	about 81
8	2^ndrun of #7 with a new tobacco rod	about 32
9	#5, reduced CO at 150° C.	about 55
10	2^ndrun of #9 with a new tobacco rod	about 30

[0060]

TABLE 4


CO Removal from Main stream Smoke by
Modified Vented Cigarette Filters
Containing (Ag + Pd)/zeolite 13X.

Sample	Filter	% CO removed

11	(Ag₂O + Pd)/Z	about 50
12	#11, reduced CO at 120° C.	about 75

[0061]

TABLE 5


CO Removal from Main stream Smoke by
Modified Vented Cigarette Filters
Containing Ag/zeolite CP861E (about 7Å).

Sample	Filter	% CO removed

13	Ag₂O/Z	about 42
14	#13, reduced CO at 120° C.	about 56
15	#14, oxidized 5 hrs in air at room T	about 37

[0062]

TABLE 6


CO Removal from Main stream Smoke by
Modified Cigarette Filters
Containing Ag/zeolite CP861.

Sample	Filter and Cigarette	% CO removed

16	Ag₂O/Z in vented filter	about 73
17	#16, kept in cigarette for 2 hrs	about 48
18	#16, kept in cigarette for 1 day	about 45
19	#16, kept in cigarette for 2 days	about 26
20	#16, kept in cigarette for 3 days	about 22
21	#16, kept in cigarette for 10 days	about 50
22	Ag₂O/Z in non-vented filter	about 27
23	#22, kept in cigarette for 0.5 hr	about 9

A feature of adsorbent preparation appears evident from data summarized in tables 5 and 6. Sample 13 in Table 5 was prepared beginning with a silver water phase exchange procedure done to whole zeolite grains of about 2×6 mm ter silver deposition the adsorbent was milled, sieved and packed in a filter. The effectiveness of this filter was about 42%; this effectiveness varied from both an about 120° C. reduction material and a long-term storage material.[0063]

[0064]Sample 16 in Table 6, was made starting with a milled and sieved CP861 zeolite. Removal of CO by this material exceeded about 70%; its activity remained significant, although reduced, even after about 10 days at about room temperature in a vented CO pump. This result suggests that it may be preferred to a shape and sieve a zeolite prior to silver incorporation.

EXAMPLE 5

Nickel oxide particles, modified with the rare-earth element dysprosium, were embedded into large-pore molecular sieves. These materials readily adsorb substantially all of the GC-detected, gas-phase organic molecules except light hydrocarbons. The filtering properties of the adsorbent appeared to be similar to that of activated carbon. The Ni/Dy/zeolite system also demonstrated significant carbon monoxide adsorption activity.[0065]

About 10 g of nickel acetate Ni(CH[0066]₃HOO)₂*4H₂O, from the Fisher y, dissolved in 100 ml water, were mixed with about 30 g zeolite CBV300-X16 from the Zeolist International Company. The zeolites were used as about 1×4 mm extruded granules. The mixture was retained at about room temperature for about 5 days to factilitate nickel ion exchange. The solution was then decanted and the zeolites were thoroughly washed with cold water.

About 3 g of dysprosium chloride DyCl[0067]₃(grade REO), from Strem Chemicals, were dissolved in about 50 ml water and mixed with the solid material. The mixture was retained at about room temperature for about 5 additional days to exchange Dy³⁺ ions into the matrix. The solution was decanted. The solid material was washed with plenty of water, dried at about 50° C. for about 2 days and annealed at about 350° C. for about 2 days in air. The catalyst was stored in air as about 1×4 mm granules. Before conducting experiments, the sample was milled and about 40-60 mesh size particles were sieved off to be used in a CO pump.

About 500 mg of the catalyst were packed adjacent to tobacco in non-vented and vented research cigarettes. About 70% CO removal from main stream smoke was obtained in both cases. Also, GC analysis of the filtered tobacco smoke showed about 90% removal of acetaldehyde, acrolein and other functional derivatives, as well as unsaturated hydrocarbons. The adsorbent behaved essentially like an activated carbon with respect to these compounds (e.g., low selectivity).[0068]

EXAMPLE 6

Zeolite samples impregnated with copper and palladium ions were similarly prepared using their corresponding chlorides. Palladium salt was dissolved in aqueous HCl so that the H[0069]₂PdCl₄complex was used in place of the ammoniacal complex.

Copper- and palladium-containing zeolite of about 5 Å showed minor CO activity at about room temperature. Applicants believe that the high temperature activity and sensitivity to poisons (both known characteristics of copper and palladium compounds) explain the results.[0070]

EXAMPLE 7

Three samples were formed by distributing hydrochloric acid-doped polyaniline in both about 3 Å and about 9 Å zeolite samples, and on the surface of a cellulose/acetyl cellulosic cigarette filter. About 5 g of the corresponding zeolite or the cellulose acetate filters, taken from research cigarettes, were placed in about 300 ml solution of 5 g aniline in an about 1M aqueous HCl. This suspension was mixed for about 20 hrs at about room temperature for aniline adsorption on carbon. The resulting solids were filtered and washed with about 500 ml water and about 100 ml of an about 1M HCl solution. The supported aniline was suspended in about 300 ml of an about 1M HCl solution that was then cooled on ice.[0071]

About 11 g of ammonium persulfate (about 98% pure) were dissolved in about 200 ml of an about 1M HCl solution. The solution was cooled on ice and slowly added to the suspension, while maintaining the temperature below about 10° C. under a vigorous magnetic stirring. The temperature was allowed to self-equilibrate to about room temperature in about 2 hrs and stirring was continued for about another 20 hrs.[0072]

The resulting solids were filtered and washed with about 1L water on a filter and suspended in about 300 ml of an about 1M NH[0073]₄OH solution under mixing for about another 20 hrs. The supported polymers were washed with about 1L of water on a filter. The solid materials were suspended in about 300 ml of an about 1M HCl solution under mixing for about another 20 hrs. The final products, the HCl-doped supported polymers, were thoroughly washed in about 2L of water, filtered, dried in air at about room temperature for about 24 hrs and stored.

Polyaniline embedded into about 3 Å and about 9 Å zeolite matrices showed very low CO adsorption activity. However, the same polymer supported on a cellulose/cellulose acetate cigarette filter adsorbed CO from the first cigarette puff. The following puffs remained unchanged because of the low adsorptive, irreversible capacity of polyaniline.[0074]

EXAMPLE 8

A Pd-Cu supported catalyst was formed as a result of the degradation of a heterogenized homogeneous Wacker-type catalyst in a reaction gas. An optimum surface concentration of the CO oxidation products, and possibly water, appears to have created a catalyst state that could resist the deactivating action of smoke compounds, remaining active for a few minutes in a smoke atmosphere.[0075]

In this example, the results of tests of palladium catalysts with silver and copper as catalyst promoters supported on carbon or zeolite to promote shape-selectivity are discussed. A heterogenized Wacker-type catalysts as well as catalysts obtained by decomposition/reduction are also considered. Oxidation in a model mixture of CO+O[0076]₂in He with the addition of water, and in few cases the oxidation of carbon monoxide in smoke, was used for testing the catalysts.

Several catalysts were prepared substantially as described in A. I. Kozlov, A. P. Kozlova, H. Liu, Y. Iwasawa, A New Approach To Active Supported Au Catalysts, Review,[0077]Applied Catalysis A: General182 (1999) 9-28; A. P. Koziova, A. I. Kozlov, K. Asakura, Y. Matsui, T. Kogure, T. Shido, Y. Iwasawa. Supported Gold Catalysts Prepared From A Gold Phosphine Precursor And As-Precipitated Metal-Hydroxide Precursors: Effect Of Preparation Conditions On The Catalytic Performance,Journal of Catalysis196 (2000) 56-65; Y. Yuan, K. Asakura, A. P. Kozlova, H. Wan, K. Tsai, Y. Iwasawa. Supported Gold Catalysts Derived From The Interaction Of A Au-Phosphine Complex With As-Precipitated Titanium Hydroxide And Titanium Oxide,Catalysis Today44 (1998) 333-342; and Y. Yuan, A. P. Kozlova, K. Asakura, H. Wan, K. Tsai, Y. Iwasawa. Supported Au Catalysts Prepared From Au Phosphine Complexes And As-Precipitated Metal Hydroxides: Characterization And Low-Temperature CO Oxidation,Journal of Catalysis170 (1997) 191., e.g., a low-temperature active catalyst Au/Fe₃O₄ from tri-phenyl-phosphine-Au-nitrate. These appeared to be sensitive to other reactive smoke compounds.

EXAMPLE 9

A series of Zeolite sieves having about 3, 4, 5 and 9 Å apertures were tested for carbon monoxide chemisorption using a pulse reactor technique connected to the gas chromatography analysis of carbon monoxide[0078]

Catalysis and chemisorption experiments were performed in: a) The 2 ml quartz pulse/flow reactor of an AutoChem 2910 catalyst characterization system from Micromeritics and b) a Setaram model DSC/TG-111 DSC/TGA setup. Reaction gases were analyzed using: a) a ThermoStar mass-spectrometer from Balzers; b) an infrared CO analyzers from Thermo Environmental Instruments, Inc. (model 48C) and from Filtrona; c) a TC detector on the outlet of the AutoChem reactor; and d) an HP6890 gas chromatography (GC) with an about 10 m column having an about 3 mm diameter, packed with[0079]HayeSep DB 100/120.

All gas flow rates, gas compositions, pulse injections, temperature ramps, etc. were controlled via programming of the AutoChem instrument. A mixture of about 2% CO in He was prepared for adsorption experiments. About 1% N[0080]₂was added to this mixture as an internal standard for GC analysis. The catalytic oxidation of carbon monoxide was studied using CO, O₂and a mixture of about 3% CO+12% O₂in He. Gas mixtures were prepared by the Matheson Company.

The pre-treatments, performed in the same adsorption reactor, comprised either dehydration by a dry gas or hydration by humid air. The residence time of a CO pulse passed through about 10 ml of about 0.4 mm wide pore silica gel beads did not differ from that of a CO pulse passed through about 0.4 mm glass beads; this therefore provided a reference for adsorption measurements.[0081]

FIG. 5 is plots of the retention time (as well as the reference time) of a CO pulse within a zeolite bed as a function of the pore size of the zeolite. The data represented by the upper curve were obtained for zeolites annealed at about 300° C. for about ten hours prior to carbon monoxide injection. This curve indicates that zeolite apertures up to about 4 Å do not show significant carbon monoxide adsorption activity. Adsorptive delay increased dramatically at about 5 Å aperture; which is reasonable since the effective diameter of a CO molecule given in D. M. Young, A. D. Crowell. Physical Adsorption Of Gases. 426 pages. Butterworth , London, 1962, p. 226., for example, is approximately 4.5 Å. Retention times may have decreased as zeolite aperture increased beyond about 5 Å since CO molecules may have been more easily released.[0082]

The maximum measured carbon monoxide retention time was about 7.5 min. and was evident in dehydrated zeolites. Hydrated zeolites are represented by the lower curve in FIG. 5, which shows that hydration decreases delay times nearly sevenfold. Hydration may become an important factor in almost any practical application due to equilibration with ambient moisture over time. The dynamics of this change in adsorptive properties with hydration may be used to estimate the lifetime of an active site within the adsorptive material.[0083]

An airflow of about 200 ml/min at about 60% relative humidity was passed through the reactor loaded with previously dehydrated, active about 5 Å zeolite for one hour. The purge gas was then switched to dry helium and the delay times of carbon monoxide pulses passing through the reactor were measured as a function of time. FIG. 6 shows a rapid decrease of zeolite adsorptive activity, as indicated by a reduction in retention time to about 1.5 min. This result is quite close to the result shown in FIG. 5 for hydrated zeolites.[0084]

EXAMPLE 10

This example describes a study of a Wacker catalyst for carbon monoxide oxidation in a model gas mixture and in smoke. This catalyst type seemed to be promising for carbon monoxide removal from smoke at ambient temperature because of its high activity at low temperatures and its use of water, chloride and possibly other ligands as co-catalysts or promoters. In most other catalyst types such constituents of the reaction mixture would slow the catalysis or even poison the active metal. These compounds are always present in smoke, however, which imposes tough requirements on a catalyst design.[0085]

In a typical experiment, about 1 g of a catalyst was placed in the reactor and purged with about 50 ml/min He for about 10 min, then exposed to about 50 ml/min (3% CO+12% O[0086]₂+He) gas mixture at about room temperature. The results showed that a complete CO conversion was observed on an air-dried (PdCl₂+CuCl₂)/C catalyst. This oxidation reaction provided a strong exothermal effect, resulting in an increase of the catalyst temperature by about 10° C.

Desorption of water, facilitated by the self-elevated temperature of the catalyst due to exothermic carbon monoxide oxidation, accompanied this non-heated catalysis. Deactivation of the catalyst appeared to be synchronized with the end of the catalyst dehydration process. Results shown in FIGS. 7[0087]aand7bindicate that the catalyst may stay active under the described experimental conditions at ambient temperature for about 2 hours without water supplied in the reaction gas. This corresponds to approximately 8 mmol of carbon monoxide oxidized before the catalyst deactivated.

Deactivation of the catalyst due to its dehydration was found to be reversible. The experiment to verify this was performed as follows: right after the catalyst lost its activity, about 10 microliters of water were injected into the evaporator before the reactor. The catalyst, therefore, was purged with approximately 12 ml of water vapor. This treatment provided the recovery of the deactivated catalyst, lasting only approximately 1 hour. The necessity of water in the reaction gas to keep the catalyst active may, in fact, be advantageous for some applications when treatment of a humid smoke is required. In a smoke test, however, just one about 35 ml pulse of combustion products deactivated this catalyst, removing only about 20% of CO in the pulse.[0088]

Smoke tests showed that the supported PdCl[0089]₂+CuCl₂Wacker-type catalyst is capable of carbon monoxide oxidation at ambient temperature even in smoke. However, the active sites of this particular carbon-supported catalyst are equally accessible to all constituents of the smoke, providing very low selectivity, quickly saturating the catalyst with strongly bonded ligands, and deactivating the palladium. The selectivity of the Wacker type catalyst therefore appears to be a very important issue. This could be approached by using molecular sieves, such as zeolites, to exclude large molecules from interacting with the catalyst active sites.

EXAMPLE 11

The composition of supported PdCl[0090]₂—CuCl₂catalyst described above- in Example 10 and made substantially according to the methods of E. D. Park, S. H. Choi, J. S. Lee. Active States Of Pd And Cu In Carbon-Supported Wacker-Type Catalysts For Low-Temperature CO Oxidation,Journal of Physical ChemistryB 104 (2000) 5586-5594, was somewhat altered according to E. D. Park, J. S. Lee. Effect Of Surface Treatment Of The Support On CO Oxidation Over Carbon-Supported Wacker-Type Catalysts.Journal of Catalysis193 (2000) 5-15. Specifically, copper nitrate was added to enhance a redox activity of the catalyst. It was found that addition of a copper nitrate facilitates the formation of the active copper-containing phase Cu₂Cl(OH)₃, and enhances hydrophilicity of the support. A similar effect had been achieved by introduction of carboxylic and carbonyl groups onto a carbon support by the pretreatment of the support with nitric acid. Applicants believe that the activated carbons of a Centaur family, manufactured by Calgon for a low temperature phosphine oxidation, is a commercially available product already having this feature. Therefore, the activated carbons of a Centaur family was tested as a Wacker-type PdCl₂—CuCl₂—Cu(NO₃)₂catalyst support.

A Series of substantially about 100% CO about 1 ml gas pulses in the number of about 50 were passed through about 1 g of the air-dry catalyst. Carbon monoxide gas was saturated with water at about 70° C. prior to injection. The profiles of the product concentrations, measured by a mass-spectrometer, are shown in FIGS. 8[0091]a,8band8cfor the 1^st, 7^thand 42^ndpulses, respectively. Evidently from these curves, the concentration profiles of carbon oxides undergo broadening, whereas the width of oxygen peak remains the same. This may suggest that the Pd²⁺ . . . Pd⁰-based active sites, responsible for CO_xchemisorption change their composition, whereas Cu⁰. . . Cu²⁺-based oxygen chemisorption sites appear more stable.

The most probable transformation that Pd[0092]²⁺ may undergo in a carbon monoxide-containing atmosphere is its reduction to Pd⁰, consistant with A. Boulahouche, G. Kons, H. G. Lintz, P. Schultz. Oxidation Of Carbon Monoxide On Platinum-Tin Dioxide Catalysts At Low Temperatures,Applied Catalysis A: General91(1992) 115-123. Presence of oxygen in this case may promote this process by releasing some CO catalytic oxidation energy, therefore, elevating a local temperature. A significant increase in the catalyst temperature was always noticed in such experiments as exemplified by FIG. 9a.Areas under these temperature curves were integrated, which represent the heat of all oxidation processes in the system. Due to the relatively slow change in an average oxidation state of palladium, this heat can be attributed mostly to the intensity of CO to CO₂oxidation.

The integral values of the reaction heat are shown in FIG. 9[0093]bas a function of the pulse number. The initial increase of this heat may be explained by endothermic evaporation of excessive water from the catalyst. This exothermic effect must also provide somewhat lower necessary temperature for efficient catalysis. On the other hand, a progressing monotonous decrease of this heat, and therefore, of the maximum catalysis rate in a pulse, could be caused by a change in the palladium oxidation state, and by its covering with CO molecules.

This catalyst deactivation process may involve an accumulation of carbon dioxide in a water film on the catalyst, thus providing more diffusion limitations for all molecules. A verification of this model was attempted in the experiment with the catalyst, which was exposed to about 50 pulses of CO+O[0094]₂+ He as described above. This catalyst was purged with about 50 ml/min of about 10% O₂in He at ambient temperature for about 2 days. This was done to remove the possibly accumulated water solution of carbon dioxide and thus the diffusion limitations, associated with it. After this treatment the pulse catalysis experiment was resumed under the same conditions.

As is seen from FIG. 10[0095]a,the concentration profiles of CO and CO₂even in the first pulse remained as broad as before the described treatment. This suggests that the possible diffusion control by the water-dissolved or even by just chemisorbed products must not be a significant factor in the catalyst deactivation. However, a further deactivation of the catalyst has progressed even faster after removal of most of water from the catalyst surface. FIG. 10bshows the concentration profile of pulse15 in the scale of FIG. 10a.This result indicates a large widening of both CO_xpeaks.

This may be explained by an increased CO coverage on Pd[0096]⁰, which slowed the catalysis and forced it to proceed far beyond the duration of a CO pulse. In fact, an about 5 minutes period between pulses appeared to be not long enough for all carbon monoxide to oxidize or desorb in the flow of O₂- containing gas, as monitored by a mass-spectrometer. Therefore, accumulation of carbon monoxide in the catalyst was usually observed in such experiments. This phenomenon was used to entrap carbon monoxide from smoke.

The experimental results suggest that the Pd[0097]²⁺ . . . Pd⁰-based active sites, responsible for CO_xchemisorption change their composition during catalysis, whereas Cu⁰. . . Cu²⁺-based oxygen chemisorption sites appear more stable. Pd²⁺ may undergo a reduction to Pd⁰. Oxygen may promote this process by releasing some CO catalytic oxidation energy, therefore, elevating a local temperature. A significant increase in the catalyst temperature was always noticed. Accumulation of carbon monoxide in a catalyst was observed. Experiments were performed in a dry gas flow regime to elucidate the interdependence of changes in the product concentrations in a matter of time. The evidence of decomposition of copper nitrate, which may include hydrolysis, was found.

The results suggest that the drying and heat treatment in a CO+O[0098]₂reaction gas lead to a transfer of a Wacker-type transition metal complex catalyst to a Pd⁰atoms or small clusters. This new system composes a very active chemisorbent of carbon monoxide and a stable oxidation catalyst, active at higher temperatures. The prepared Wacker-type catalyst showed to become active in CO removal from a smoke flow after it has been treated in a diluted CO+O₂gas. Thus, a reduced catalyst showed about 70% conversion of carbon monoxide.

EXAMPLE 12

The activity of the Wacker-type catalyst described in the above examples appeared to be higher than that of the Wacker catalyst on PCB carbon from Calgon. However, this did not provide new catalyst with a better activity when it is used in a smoke. The experiment showed that about 20% of carbon monoxide could be removed by about 400 mg of the fresh catalyst only from the first about 35 ml pulse of smoke, which completely deactivated the catalyst. The effectiveness of the catalyst somewhat increased if approximately 20% more air is supplied.[0099]

A less active at room temperature, but more stable catalyst, which was formed during a partial reduction of palladium in the course of the above described CO+O[0100]₂treatments, was tested in a similar smoke pulse conditions. More specifically, the catalyst for this test was prepared by a treatment of the fresh Wacker-type Centaur carbon-supported catalyst in a 3000 hr⁻¹flow of 3% CO+12% O₂+ He dry gas mixture at 100° C. for 5 hours. The following treatment was desorption of products in 10% O₂+ He flow for 1 hr at cooling.

About 400 mg of the resultant catalyst was loaded in the reactor and purged with about 9 pulses, each of about 35 ml smoke with approximately about 3% CO in it. Atmospheric air in the amount of about 20% of smoke volume was added in the reaction zone to improve the catalyst performance. As is seen in FIG. 11[0101]a,a ventilated reactor, composed of the reduced catalyst, showed about 80% less amount of carbon monoxide delivered within about 9 smoke pulses. Another portion of the same reduced catalyst was kept in a sealed jar for 5 days, followed by its smoke test under the same conditions. The aged catalyst showed only 25% CO removed from smoke under the same conditions.

The distribution of carbon monoxide removal efficiency of the catalysts versus the pulse number, shown in FIG. 11[0102]afor the just activated and for the aged catalysts, indicate that some change on the catalyst surface took place. Since the catalyst was kept sealed in a jar between its pretreatment and a smoke test, the lowering of its efficiency was most likely caused by a redistribution of some surface compounds, i.e., oxygen, water and CO_x, accumulated in the catalyst during its CO/O₂treatment. This suggestion seems consistent with an increase of the aged catalyst efficiency with the pulse number (FIG. 11b), or with the exposition of the catalyst to some possible co-catalyst compounds in smoke.

EXAMPLE 13

A literature review of the most recent studies in the area of the low-temperature oxidation of carbon monoxide on noble-metal containing catalysts was made. The mechanisms of oscillating activation of oxygen and CO by Pd, Pt and Au-containing catalysts, energetic and electron transfer aspects were considered. The effects of surface properties and structure of support, catalyst preparation conditions, presence of the second transition metal, etc. on the catalytic oxidation activity were briefly analyzed. Some of the literature results were utilized to develop a catalytic system, capable of working at ambient temperature at very high reaction gas flow rates in the atmosphere of smoke.[0103]

Zeolites of particularly about 5 Å aperture retain carbon monoxide at room temperature with a typical time of seconds, whereas amorphous silica does not have such activity. Silver clusters, embedded into a zeolite cavity, increase this time by a factor of ten. This provides much longer time for carbon monoxide to react with oxygen. However, mainly Pd and Au catalysts were found to be capable of oxidizing CO at an ambient temperature.[0104]

FIG. 12 shows an Arrhenius plot of carbon monoxide conversion up to about 20% for Pd/zeolite. These measurements of CO oxidation on a zeolite 13× supported palladium provided an activation energy of 5 kJ/mol at temperatures below 130° C., whereas an abrupt increase in E[0105]_actto nearly 42 kJ/mol was found at higher temperatures. Activation energy tended to increase even higher at a further elevated temperature, as illustrated by FIG. 12.

The invention can also be carried out by providing a mouthpiece for a smoking article (such as a cigarette or cigar) to which the smoking article is attached when smoked. If the pumping capacity of the mouthpiece is great enough, it may be reused with multiple smoking articles. The mouthpiece can be configured in numerous shapes and sizes as desired, but an example is seen in FIG. 4. The mouthpiece M includes a fitting[0106]22 to receive a smoking article C, and acarbon monoxide pump24 including an adsorbent116 for adsorbing carbon monoxide, wherein the carbon monoxide pump is positioned with respect to the smoking article C so as to selectively divert carbon monoxide from main stream combustion products prior to inhaling by a smoker.Vents20 &118 can be provided like thevents18 mentioned above. If desired, portions of the mouthpiece M may include aconventional filter material120, such as cellulose acetate or other filter material.

Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. By way of example, CO removal may be attempted by changing the smolder of a tobacco column, which in turn changes the chemical makeup of the main stream smoke. Even with changing the smolder of the tobacco column, the present invention may be effective. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.[0107]