WO2019229280A1 - Mixture of tobacco with a synergetic composition of additives and carboxylic acid salts for reducing the generation of tocix compounds in the tobacco smoke - Google Patents

Abstract

The invention relates to a mixture of tobacco and a composition comprising a mesoporous compound (preferably SBA-15 type aluminosilicate, MCM-41 type aluminosilicate or activated carbon) and an alkali-metal or alkaline-earth-metal salt of carboxylic acid (preferably potassium citrate), which produces a synergetic effect in the reduction of toxic products in the tobacco smoke. In this way, reductions in nicotine, tar and carbon monoxide can be achieved in the order of 70%, 90% and 50% respectively, much greater than what can be expected from the combination of both additives, confirming that they strengthen their effects or produce a synergetic effect.

Description

 TOBACCO MIXTURE WITH A SYNERGIC COMPOSITION OF ADDITIVES AND SALTS OF CARBOXYLIC ACIDS TO REDUCE THE GENERATION OF COMPOUNDS

TOXICS IN TOBACCO SMOKE

DESCRIPTION

Mixture of tobacco with a synergistic composition of additives and salts of carboxylic acids to reduce the generation of toxic compounds in tobacco smoke.

FIELD OF THE INVENTION

The present invention falls within the general field of tobacco preparations and in particular refers to a mixture comprising tobacco and a synergistic composition of additives and salts of carboxylic acids for the reduction of toxic compounds in tobacco smoke.

STATE OF THE PREVIOUS TECHNIQUE

The use of alkali metal, alkaline earth and other metal salts such as iron, and particularly those of potassium, has received some attention in the scientific and patent literature in relation to tobacco. Numerous patent references can be found where the role of potassium as a combustion modifier and carbon monoxide emission reducer is described, both in tobacco and paper mixtures and various items that can be smoked including tobacco substitutes.

Patent application WO8102379A1 describes the elimination of nitrate and potassium ions from tobacco and then reinstate the potassium ion in the form of a salt other than nitrate. In this way they describe the reduction of a series of compounds of the gaseous stream of tobacco smoke such as nitrogen oxides, CO, HCN.

US4489739 describes the formulation of tobacco compositions including (in the range of 6.5 to 20%) potassium salts of carboxylic acids (carbonic, formic, acetic, propionic, malic, lactic, glycolic, citric, tartaric, fumaric, malonic and succinic ) with reduced tendency to the formation of carbon monoxide. US8590542 describes the use of potassium citrate incorporated into the paper in proportions of 0.6 to 2% in order to provide it with thermoresilient properties, so as to maintain the shape and ash after combustion providing an improved appearance to the cigarette being smoked. .

CN patent 103284321 describes a tobacco that produces a lower amount of CO by adding potassium citrate between 6 and 10%. It also describes the reduction of nicotine and tar for this same reason.

US4505282 describes the use of activated carbon particles coated with calcium citrate for the production of a paper with which to form an internal wrapper for smoking articles, in order to reduce the emission of tars and nicotine in the secondary stream of smoke of tobacco Additives are also added to this package to modify the taste of smoke.

Chinese patent CN1123118 describes the formation of a species of reconstituted tobacco made from the remains of tobacco, sepiolite, glycerin, phosphoric acid potassium citrate, activated carbon, perfume and pigments, to be ground and added to tobacco. They indicate that it can reduce hazardous materials such as tars, benzopyrene, CO and acetone, due to the adsorption capacity of sepiolite and improve the quality of cigarettes. Very low tar reductions are indicated, of the order of 13%.

US5161549 describes the use of solutions of potassium citrate and other salts in the filter in order to retain nicotine tars and other harmful gases.

US5860428 describes the use of these salts, and in particular potassium citrate in the tobacco filter, which act as humectants by adsorbing the moisture of the tobacco and providing a moist and more effective filtrate of tobacco smoke.

Patent W02014005418 describes the use of alkali metal salts of tetracarboxylic acids in smoking paper, in order to reduce the emission of carbon monoxide, phenol and tar. In the scientific literature you can also find articles in reference to this effect. For example, the article by C. Liu and A. Perry "Potassium Organic Salts as Burn Additives in Cigarettes", Beitráge zur Tabakforschung International / Contributions to Tobacco Research, vol 20, No. 5, 2003, 341-347, is indicated as the addition of potassium in the form of citrate tartrate or malate in proportions of 3.1 to 8% produces reductions of carbon monoxide of the order of 27% with respect to the control and the like of nicotine and tars, in addition to reductions in the combustion temperature. On the other hand, the use of catalysts of the meso porous aluminosilicate type type MCM-41 (EP2092838), SBA-15 (ES2482490) and mesoporous carbons of high degree of activation as additives of tobacco (ES2543851), or of reconstituted tobacco, ES 2499990), to reduce the emission of toxic products, has been described as an effective method for the reduction of carbon monoxide and various components of the gaseous stream of tobacco smoke and especially nicotine and tars. Its effect on the reduction of nitrous oxides, tobacco-specific nitrosamines, polyaromatics, phenols and other components of the gas stream has also been described (CN1460641).

The use of these additives mixed with tobacco produces concentration dependent reductions that can reach in the order of 30% in CO and up to 80% in nicotine and tar. However, these catalysts are more effective on the particulate stream (nicotine and tars) than in the gas stream, where at low concentrations they even produce yield increases with respect to the reference tobacco smoked without catalyst. In fact, to achieve the aforementioned reductions in CO it is necessary to use concentrations greater than 6% by weight.

In Marcilla et al. "TGA-FTIR study of the thermal and SBA-15-catalytic pyrolysis of potassium citrate under nitrogen and air atmospheres." J. Anal. Appl. Pyrol, 125, 144-152, 2017, Marcilla et al.), Describes the effect of SBA-15 on the pyrolysis and oxidation of potassium citrate at low heating rates in a TG-FTIR equipment. It can be concluded that decomposition processes are significantly modified, but it cannot be expected from these results that a remarkable effect will occur when both additives are added to a cigarette.

There is therefore a need to find compounds that, when added to tobacco, reduce the emission of toxic compounds from tobacco smoke, such as tars, nicotine and carbon monoxide, as well as many of the components of the gaseous and particulate fraction of smoke.

EXPLANATION OF THE INVENTION

The present invention solves the problems described in the state of the art since it provides a mixture comprising tobacco and a composition of additives that when used together have a marked synergistic effect on the emission of toxic compounds from tobacco smoke, such as tars , nicotine and carbon monoxide, as well as many of the components of the gaseous and particulate fraction of the smoke, providing excellent reductions that were not predictable of their combined effect.

Thus, in a first aspect, the present invention relates to a mixture comprising tobacco and a synergistic composition (hereinafter, mixture of the present invention) comprising:

 - at least one mesoporous compound and,

 - at least one alkali metal or alkaline earth metal salt of carboxylic acid.

In the present invention tobacco refers to conventional tobacco, which is that which is processed from the leaves of the tobacco plant; reconstituted tobacco, which is that which is made from tobacco stalks, leaf remains, tobacco fines or plant-derived tobacco plant processed by typical papermaking processes and tobacco fines that are not usable in the primary processes of cigarette making; expanded tobacco, which is one whose volume has expanded by rapid evaporation of a substance, such as dry ice; rolling tobacco, pipe tobacco and mixtures thereof.

In a particular embodiment, the mesoporous compound of the mixture of the present invention is selected from SBA-15 type aluminosilicate, MCM-41 type mesoporous aluminosilicate and mesoporous activated carbon with high degree of activation.

In a particular embodiment, the aluminosilicate type SBA-15 of the mixture of the present invention is selected from among the aluminosilicate type SBA-15, its acidic, sodium forms, exchanged with iron, sodium, potassium, calcium, cerium, zirconium, iron oxides, sodium, potassium, calcium, cerium, zirconium and mixtures thereof.

In a particular embodiment, the MCM-41 type mesoporous aluminosilicate of the mixture of the present invention is selected from among the MCM-41 type mesoporous aluminosilicate, its acidic, sodium forms, its forms exchanged with iron, zirconium, and mixtures thereof.

In the present invention, mesoporous activated carbon refers to mesoporous activated carbons with a particle size between 1-100 pm, of high degree of activation, with a SBET surface comprised between 1200-4200 m ² / g, a VMIC volume comprised between 0.4-1.2 cm ³ / g and a VMESO volume between 0.6-2.8 cm ³ / g as an additive to reduce the toxic and carcinogenic substances present in tobacco smoke. In a particular embodiment, the carboxylic acid of the mixture of the present invention is selected from carbonic acid, formic acid, acetic acid, propionic acid, malic acid, lactic acid, glycolic acid, citric acid, tartaric acid, fumaric acid, acid. Malonic and succinic acid.

In a particular embodiment of the present invention, the mesoporous compound is an SBA-15 aluminosilicate and the alkali metal or alkaline earth metal salt of carboxylic acid is potassium citrate.

In a particular embodiment, the mixture of the present invention further comprises at least one of the compounds selected from water, glycerin, ethyl alcohol, pigment, flavoring and odorant.

In another particular embodiment, the mesoporous compound of the mixture of the present invention is in a concentration between 0.5-15% by weight.

In another particular embodiment, the alkali metal or alkaline earth metal carboxylic acid salt of the mixture of the present invention is in a concentration comprised between 0.1-20% by weight. In another aspect, the present invention relates to the use of the synergistic mixture of the present invention for the reduction of toxic and carcinogenic substances present in tobacco smoke.

DETAILED EXHIBITION OF REALIZATION MODES

The following materials were used in the examples:

 Reference tobacco (TR). Tobacco 3R4F from the University of Kentucky.

 Tribasic potassium citrate monohydrate, purum p.a.,> = 99% of Sigma Aldrich (C).

 SBA-15 (S) type catalyst, synthesized in our laboratory according to the procedure described in the work of Zhang et al. (F. Zhang, Y. Yan, H. Yang, Y. Meng, C. Yu, B. Tu, D. Zhao, Journal of Physical Chemistry B.109 (18), (2005), 8723), which is the preparation of a solution of pluronic P 123 in acidic medium and the addition of a stoichiometric amount of tetraethylorthosilicate (TEOS). After keeping the resulting solution under stirring at 38 ° C for 20 h, it was transferred to an autoclave and kept at 100 ° C for 24h. The resulting suspension was washed with water, dried 100 ° C and finally calcined at 550 ° C for 5h. The textural characteristics of the synthesized catalyst are shown in Table 1.

 Type MCM-41 (M) catalyst, synthesized in our laboratory according to the procedure described in EP2092838 and with the characteristics described in Table 1.

 Mesoporous activated carbon (CA) type catalyst, synthesized according to the method described in the following references (Coal, 47 (2009) 195-200; Chemistry and Physics of Carbon (2008), 30, 1-62; Energy & Fuels 2002, 16, 1321-1328; Journal of Porous Materials 5, 43-58 (1998); Carbon 48 (2010) 636-644; Fuel Processing Technology (2013), 106, 501-510), described in P201300305.

Table 1. Textural properties of the catalysts used.

(a: BJH; b: método BET, isotermas de adsorción de N₂; c: método t, isotermas de adsorción de N₂; d: medido a P/P0=0.995, isotermas de adsorción de N₂; e: XRF).

(a: BJH; b: BET method, adsorption isotherms of N ₂ ; c: t method, adsorption isotherms of N ₂ ; d: measured at P / P0 = 0.995, adsorption isotherms of N ₂ ; e: XRF) .

The smoking conditions of prepared cigarettes and the analysis of the products generated are detailed below.

The reference tobacco was used in all the examples, which was obtained by emptying the cigarettes and reserving the filter and paper tubes thereof. Next, the tobacco mixtures with the selected additives (potassium citrate (C) and catalyst (S)) were prepared.

The following samples were prepared: reference tobacco (TR), TR + 6% potassium citrate (TRC), TR + 4% SBA-15 (TRS) and TR + 6% potassium citrate + 4% SBA-15 (TRCS ). TR + 4% samples of MCM-41 (TRM) and TR + 4% of MCM-41 + 6% potassium citrate (TRMC) were also prepared. Finally, samples with similar concentrations of activated carbon (TRCA) and activated carbon and potassium citrate (TRCAC) were prepared.

The potassium citrate was added in the form of a concentrated solution, adding a sufficient volume to wet the tobacco strands, so that after the evaporation of the water the desired citrate concentration was obtained. The catalyst was subsequently added in both cases directly to the tobacco and mixed by hand, without using any additive to improve dispersion. It was observed that, by adding potassium citrate, the strands had a certain adhesion or unctuousness. This fact clearly favored the dispersion of the catalyst thereon providing greater stability to the final mixture, where no separation of materials was observed, which occurred partially in the case of the mixture of tobacco and catalyst without citrate. This partial separation effect was also observed in the cases previously described in the patents (EP2092838, ES2482490 and ES2543851). Therefore, the use of potassium citrate has an additional practical advantage over the described behavior of the catalysts, which can justify the observed results.

The reserved tubes of the cigarettes emptied of 3R4F tobacco were refilled and 15 cigarettes of each sample were smoked (in three batches of 5) following the specifications of the ISO 3308 standard (puffs of 2 s duration, aspirated volume 35 mL, frequency of drafts 60 s and pressure loss in the draft less than 300 Pa). The cigarettes were conditioned at room temperature and 60% relative humidity, keeping them in a desiccator provided with a saturated solution of sodium nitrite, for at least 48 h.

During the smoking process, smoke, including CO, C0 ₂ and other non-condensable products, passed through the cigarette filter, as well as a trap (fiberglass filter) located before the gas collection bag. The non-condensable products were collected in a Tediar gas bag, which was reserved for subsequent analysis by gas chromatography (GC) and the condensable products were collected in the cigarette filter and in the subsequent trap, formed by a Cambridge filter, where condensed products that were directly inhaled by smokers were retained. The condensable products retained in the post filter trap were extracted with 2-propanol, making sure that all the compounds retained in the trap are recovered. Then, the extract was dried with sodium sulfate and reserved for further GC analysis.

The CO and CO2 in the gas fraction was determined by GC, using a thermal conductivity detector (GC-TCD) and a concentric CTRL column. The response factor method (grams of compound / peak area) of these compounds was used, determined by injecting different volumes (between 0.5 and 2.5 mL) of the corresponding standard (carbon monoxide, carbon dioxide and methane).

The conditions of the analysis were:

 Carrier gas: He

 Injector temperature: 28 ° C

 Detector temperature: 110 ° C

 Injected volume: 2.5 mL

 Constant column flow: 40 mL / min

 Oven temperature program: isothermal at 110 ° C

 Analysis time 20 min

The remaining non-condensable components were analyzed by GC using a flame ionization detector (GC-FID) and a GAS-PRO column, under the following conditions: Injector temperature: 150 ° C

Detector temperature: 210 ° C

Carrier gas: Helium

 Injected sample volume: 150 pl_

 Constant column flow: 2 mL / min

Oven temperature program:

 Initial column temperature 35 ° C for 10 min

Heating up to 100 ° C with a ramp of 5 ° C / min

Heating up to 200 ° C with a ramp of 15 ° C / min

Final time: 10 min

Compounds extracted with 2-propanol from cigarette filters and traps were analyzed by GC with mass spectrometry detector (GC-MS), using an HP-5MS column and the following conditions:

 Injector temperature: 250 ° C

Carrier gas: Helium

Injected sample volume: 1 pL

Constant column flow: 2 mL / min

Oven temperature program:

 Initial column temperature 40 ° C for 5 min

Heating up to 320 ° C with a ramp of 12 ° C / min

Final time: 25 min

For the quantification of the condensed phase compounds, a calibration line for nicotine was obtained, for which nicotine standards of different concentrations (between 5 and 300 ppm) were prepared. For the rest of the compounds analyzed, the response factor obtained for nicotine was used. Quantification was carried out analogously for gases, where an average response factor was used in cases where the corresponding response factor was not available. This procedure made it possible to estimate in a simple and sufficiently precise way the effect of the catalyst and potassium citrate on the same reference tobacco.

Below are the most significant data corresponding to some examples that illustrate the results that can be achieved with the use of The proposed additives. The results presented are the average of the three smoking series of 5 cigarettes, where a variable dispersion was always obtained less than 20% and reached the highest values for minority compounds. Compounds such as nicotine, carbon monoxide and tars showed dispersions of less than 10%.

Table 2 Yields in mg / cigarette of reference tobacco 3R4F.

Table 3. Reductions in%.

Table 4. Reductions in some compounds of the gas stream (%).

 Table 5. Reductions of some compounds in the tars collected in the traps.

Los resultados obtenidos mostraron claramente lo ya conocido respecto a la capacidad de reducción de monóxido de carbono del citrato potásico, que además también proporcionó una reducción similar de nicotina y alquitranes (alrededor, todas ellas, del 30%). Por otra parte, se confirmaron los resultados descritos sobre el efecto del catalizador, proporcionando unas reducciones significativas de nicotina y alquitranes, del orden del 40% y 60%, respectivamente) y una reducción prácticamente nula en el monóxido de carbono e incluso un incremento de un 20% aproximadamente en los gases generados. Sin embargo, lo más destacable fue el efecto combinado de ambos materiales que condujo a reducciones del orden del 70% en nicotina, próximo al 90% en alquitranes y al 50% en monóxido de carbono, que es el componente sobre el que el catalizador resulta menos efectivo. Además, sobre la corriente gaseosa se obtuvo también una reducción del orden del 50%. El efecto sobre los componentes de los gases y los líquidos condensados resultó además muy significativo, siendo especialmente destacable el hecho que la acción combinada de ambos materiales hizo que muchos compuestos vieran reducida su generación prácticamente a cero.

The results obtained clearly showed what was already known regarding the carbon monoxide reduction capacity of potassium citrate, which also also provided a similar reduction of nicotine and tars (around, all of them, 30%). On the other hand, the results described on the effect of the catalyst were confirmed, providing significant reductions of nicotine and tars, of the order of 40% and 60%, respectively) and a practically zero reduction in carbon monoxide and even an increase in approximately 20% in the gases generated. However, the most notable was the combined effect of both materials that led to reductions of the order of 70% in nicotine, close to 90% in tars and 50% in carbon monoxide, which is the component on which the catalyst results less effective In addition, a reduction of the order of 50% was also obtained on the gas stream. The effect on the components of gases and condensed liquids was also very significant, the fact that the combined action of both materials caused many compounds to see their generation reduced to almost zero was especially remarkable.

Examples made with MCM-41 and potassium citrate, on the one hand, and activated carbon and potassium citrate, on the other, showed similar results. As an example, the reductions obtained for nicotine, carbon monoxide and tar are shown in Table 6.

Table 6. Reductions in%.

Another fact that is relevant, and that is not directly deduced from the results obtained, was that the moisturizing and adherent effect of potassium citrate caused the mixtures with the catalyst (which has the opposite effect, moisture adsorbent) to be carried out in a manner more effective resulting in a much more stable end product than catalyst-only mixtures, even when agents were used to improve the dispersion of the glycerin type. This aspect represented an additional advantage when it came to incorporate the catalyst in the tobacco mixtures since it significantly simplified the process. The improvement of the stability of the mixture could mean that the mixing, on an industrial scale, could be carried out in conventional equipment without significant modifications in the machinery, which in the case of incorporating only the catalyst could require significant modifications. This effect of improving the dispersion and its stability, increased the effectiveness of the catalyst and caused cigarettes to be smoked in a manner more similar to the reference tobacco without any additive, so that the effect achieved was even greater than what would suppose the linear combination of the two types of materials. On the other hand, it has also been proven that the preparation of mixtures of potassium citrate, a catalyst among those mentioned, water and glycerin, with the possibility of including flavors or aromas, to be added to tobacco, both for preparing conventional cigarettes and for being added to rolling tobacco or pipe tobacco, it provides excellent results, both in terms of reducing toxic compounds, and in improving the mixing of tobacco with the catalyst and the rest of the additives.

Claims

1. Mixture comprising tobacco and a synergistic composition which, in turn, comprises:  - at least one mesoporous compound and  - at least one alkali metal or alkaline earth metal salt of carboxylic acid. 2. A mixture according to claim 1, wherein the mesoporous compound is selected from among aluminosilicate type SBA-15, mesoporous aluminosilicate type MCM-41 and mesoporous activated carbon with high degree of activation. 3. Mixture according to claim 2, wherein the aluminosilicate type SBA-15 is selected from among aliminosilicate type SBA-15, its acidic, sodium forms, exchanged with iron, sodium, potassium, calcium, cerium, zirconium, iron oxides, sodium , potassium, calcium, cerium, zirconium and mixtures thereof. 4. Mixture according to claim 2, wherein the MCM-41 type mesoporous aluminosilicate is selected from among the MCM-41 mesoporous aluminosilicate, its acidic, sodium forms, its forms exchanged with iron, zirconium, and mixtures thereof. 5. Mixture according to any of the preceding claims, wherein the carboxylic acid is selected from carbonic acid, formic acid, acetic acid, propionic acid, malic acid, lactic acid, glycolic acid, citric acid, tartaric acid, fumaric acid, malonic acid and succinic acid. 6. Synergistic mixture according to any of the preceding claims, wherein the additive is an SBA-15 aluminosilicate and the alkali metal or alkaline earth metal salt of carboxylic acid is potassium citrate. 7. Synergistic mixture according to any of the preceding claims, comprising at least one of the compounds selected from water, glycerin, ethyl alcohol, pigment, flavoring and odorant. 8. Synergistic mixture according to any of the preceding claims, wherein the mesoporous compound is in a concentration comprised between 0.5-15% by weight. 9. A synergistic mixture according to any of the preceding claims, wherein the alkali metal or alkaline earth metal salt of carboxylic acid is in a concentration of 0.1-20% by weight. 10. Use of a mixture according to any of the preceding claims for the reduction of toxic and carcinogenic substances present in tobacco smoke.