A porous foamed ceramic molecular sieve filter cigarette and a method for preparing the same

Abstract

The application of "a kind of porous foam molecular sieve filter cigarette and its preparation method" belongs to the technical field of new tobacco materials.Most of the present are in the addition of tar-reducing and harm-reducing materials in cellulose acetate or polypropylene fiber filter to filter harmful substances in cigarette smoke, but cannot simultaneously remove a variety of toxic carcinogens efficiently.The application takes attapulgite, activated carbon, natural zeolite, metal oxide and other materials as main raw materials, and is made into porous foam ceramic molecular sieve filter through mixing, pressing forming, dewaxing, pore making, vacuum sintering and other methods, and can be impregnated with other tar-reducing and harm-reducing materials.Then, the filter is directly connected and spliced with the end of cigarette tobacco, and is wrapped together with cigarette paper to obtain a porous foam ceramic molecular sieve filter cigarette product.The application is the first porous foam ceramic molecular sieve filter cigarette product in the world, which can selectively and efficiently remove a variety of harmful substances in cigarette smoke.

Description

Technical Field

[0001] This invention, "A porous foam ceramic molecular sieve filter cigarette and its preparation method," belongs to the field of new tobacco materials technology. Technical Background

[0002] Cigarette smoke is a complex aerosol composed of gaseous, vaporous, and solid substances, and is made up of thousands of chemical substances. Cigarette combustion is considered one of the most complex chemical systems in the world. When smoking, the burning tobacco, exposed to temperatures ranging from room temperature to as high as 950°C and with constantly changing oxygen concentrations, causes volatile components in the tobacco to evaporate directly into the smoke, as well as tobacco components to break down. These components are distributed in the gaseous and particulate phases of the smoke aerosol, forming a complex compound of thousands of chemical substances in cigarette smoke.

[0003] According to relevant reports, more than 5,000 compounds have been identified in tobacco and cigarette smoke, of which approximately 149 are harmful and carcinogenic, mainly small molecules. A significant portion of the harmful substances in cigarette smoke are found in tar, and countries worldwide unanimously use the tar content of cigarette smoke as an indicator of the harmfulness of cigarettes.

[0004] With the continuous advancement of tobacco control measures, the international community is no longer only focusing on reducing tar content, but also on reducing harmful components and even the overall risk of tobacco products, which has become a trend.

[0005] The World Health Organization's Scientific Advisory Committee on Tobacco Control (WHO FCTC) identified 18 hazardous substances requiring regulation: NNK, NNN, acrylonitrile, acetaldehyde, benzo[a]pyrene, 1,3-butadiene, formaldehyde, 4-aminobiphenyl, 2-naphthylamine, catechol, crotonaldehyde, acrolein, cadmium, benzene, carbon monoxide, hydrogen cyanide, hydroquinone, and nitrogen oxides. Based on the toxicity of these 18 compounds, the World Health Organization (WHO) identified nine hazardous substances requiring priority control: NNK, NNN, acetaldehyde, acrolein, benzene, benzo[a]pyrene, 1,3-butadiene, cobalt, and formaldehyde.

[0006] After comprehensive data analysis, relevant Chinese institutions have identified the seven most important components affecting the harm of cigarettes: CO, HCN, NNK, ammonia, benzo[a]pyrene, phenol, and crotonaldehyde. Relevant experimental data show that among these seven harmful substances, HCN is a highly toxic substance, widely distributed in mainstream cigarette smoke, with a release rate generally of 20-200 ug / cigarette; benzo[a]pyrene is a carcinogen, with a low release rate, generally 10 ng / cigarette, and exists in the particulate matter of mainstream smoke; NNK (butanone) is a tobacco-specific nitrosamine, a nitrosation product of nicotine, and is carcinogenic, one of the main harmful components of cigarette smoke, with a release rate generally of 5 ng / cigarette; crotonaldehyde is toxic and irritating, with a release rate of 10-20 ug / cigarette; phenol has a pungent odor, with a release rate of 10-20 ug / cigarette; ammonia can weaken the body's resistance to disease, with a release rate of 5-10 ug / cigarette; and CO poisoning easily leads to hypoxia in the human body and is one of the main inducing factors of cardiovascular disease, with the highest release rate among harmful components of cigarette smoke, at the milligram level / cigarette.

[0007] However, cigarette packs sold on the market only list three common harmful components in cigarette smoke: approximately 10mg of tar per cigarette, approximately 10mg of carbon dioxide per cigarette, and approximately 1mg of nicotine per cigarette. The reasons for this are twofold: first, identifying the harmful components of tobacco smoke is currently an extremely difficult task; second, the acetate / polypropylene fiber filters currently used in cigarettes, while filtering tar, nicotine, and carbon dioxide, cannot simultaneously and effectively filter out carcinogens and other highly toxic harmful substances.

[0008] With increasing societal attention to the health effects of smoking and the growing demand for tar reduction and harm reduction in cigarettes, the role of improving cigarette quality and reducing the release of harmful components in smoke is receiving increasing attention. Since the world's first filter tip with activated carbon appeared in 1958, research on tar reduction and harm reduction functional materials has begun abroad, and a number of functional materials with significant tar reduction and harm reduction effects have been developed domestically. Currently, the reported tar reduction and harm reduction functional materials mainly include porous carbon materials (such as activated carbon), molecular sieves, catalytic materials, polymer materials, and natural plant extracts. Although there are cigarettes on the market with activated carbon, polymer materials, or other tar reduction and harm reduction functional materials added to cellulose acetate / polypropylene fiber filters, the different effects of these materials and the different filter preparation methods result in complex manufacturing processes, limitations in the filling amount, coverage, and uniformity of additives, and difficulties in controlling quality stability during large-scale industrial production. Furthermore, the types and effectiveness of filtered harmful substances vary, allowing only partial and selective reduction. They cannot simultaneously and efficiently remove carcinogens and other harmful substances, exhibiting significant deficiencies and limitations in their harm reduction capabilities. To date, no cigarette filter worldwide utilizes porous foam ceramic molecular sieves to remove harmful substances from cigarettes. Summary of the Invention

[0009] The core of this invention is that it can significantly reduce the impact and damage of smoking on the body, efficiently filter most of the harmful substances in cigarette smoke, especially effectively remove carcinogens and toxic substances from cigarette smoke, selectively adjust and control the aroma and taste of cigarettes, and make the production and use of filter tips environmentally friendly and non-polluting.

[0010] This invention is based on modern scientific experiments confirming that porous materials (such as activated carbon), molecular sieve materials (such as zeolite), polymer materials, and plant extracts possess adsorption capabilities, enabling the concentration of harmful gases in cigarette smoke at the interface between two phases. It also incorporates the catalytic principle that catalytic materials can convert harmful gases in cigarette smoke into harmless substances through catalytic action. The invention creatively utilizes attapulgite (or kaolin and other clay-like materials), activated carbon (or activated carbon short fibers), graphene oxide (or graphene and its derivatives), natural zeolite (or diatomaceous earth), metal oxides (such as alumina, zinc oxide, etc.), and porous activated minerals. Using materials such as maifan stone as the main material, and through special processes such as powder (or slurry) mixing / wet grinding, drying, wax (glue) addition, granulation, pressing (or extrusion) molding, dewaxing (glue) pore-forming, high-temperature sintering (or vacuum sintering), as well as methods such as re-impregnation (solution impregnation or gas phase impregnation), inorganic / organic polymers and other active materials and natural plant extracts, a porous foam ceramic molecular sieve filter for cigarettes is prepared. This filter can efficiently filter most harmful substances in cigarette smoke as a whole, and can even cleanly and effectively remove carcinogens and toxic substances from cigarette smoke. It can selectively adjust and control the aroma and taste of cigarettes while maintaining sensory consistency.

[0011] The main raw materials used in the porous foam ceramic molecular sieve filter of this invention have all been verified by modern scientific research results, and have different degrees of tar reduction and harm reduction effects on harmful substances in cigarette smoke.

[0012] Based on the different characteristics and functions of the aforementioned tar-reducing and harm-mitigating functional materials, this invention creatively and scientifically constructs and combines them to achieve effects that cannot be achieved by a single material. Its principles and functions are as follows:

[0013] 1. Attapulgite (or kaolin and other clay-like materials) is the main porous foam ceramic framework used in this invention to manufacture porous foam ceramic molecular sieve filters. On one hand, it acts as a binder phase to firmly bond and polymerize other tar-reducing and harm-reducing materials (such as activated carbon, natural zeolite, and metal oxides). On the other hand, the porosity of the attapulgite material itself and the high-porosity open-pore mesoporous-macroporous porous foam ceramic framework prepared from it, with a surface area reaching 2000 m² / g, also adsorb and filter large molecular harmful elements and heavy metal particles (such as mercury, arsenic, chromium, lead, and cadmium) in cigarette smoke. Statistics show that the particle diameter in cigarette smoke is generally 0.1-1.0 micrometers, and the average particle number concentration of cigarette smoke is 1.33 × 10⁻⁶. 10 pcs / cm 3 Harmful substances in these particles can be adsorbed and filtered by the porous foam ceramic skeleton.

[0014] Porous foam ceramic frameworks serve as carriers for active porous materials and catalysts such as activated carbon, natural zeolites, and metal oxides. They offer a large specific surface area and suitable pore structure, significantly improving the adsorption efficiency of activated carbon and natural zeolites, and increasing the catalytic strength of metal oxides. Reports indicate that porous ceramics, as catalytic purification carriers for automotive exhaust, can convert harmful gases such as CO, NO, and hydrocarbons into non-toxic CO2, H2O, and N2, with conversion rates exceeding 90%.

[0015] Porous foam ceramic skeletons are used as cigarette filters, featuring high strength, light weight, and good thermal stability.

[0016] 2. Activated carbon (or short carbon fibers) possesses a well-developed microporous structure, a large specific surface area, and abundant surface functional groups, making it a carbon material with extremely strong adsorption capacity. The activated carbon used in this invention is prepared from coconut shells through high-temperature carbonization and activation processing. It is composed of microcrystalline amorphous carbon, with a carbon content typically ranging from 90-95%, and a specific surface area of ​​500-2000 m². 2 / g (special super activated carbon can even reach 4000m 2 The apparent density is typically between 0.08 and 0.45 cm³ (g). 3 / g. The pore size of activated carbon ranges from sub-nanometer to micrometer scale, with most micropores reaching below 1 nm. This is comparable to the molecular diameter of many harmful substances in cigarette smoke. The potential fields relative to the pore walls then superimpose, resulting in adsorption between the activated carbon and the solid. The micropore volume of activated carbon is approximately 0.15-0.9 mL / g, accounting for over 80% of the total pore volume, and its specific surface area can account for 95% of the total specific surface area of ​​activated carbon. This is the main reason why activated carbon has a strong adsorption capacity for small molecules or small-diameter ions in cigarette smoke, making it the primary adsorbent. Activated carbon has relatively small and numerous mesopores (pore size 2-50 nm), with a volume of approximately 0.02-0.10 mL / g. Its specific surface area generally does not exceed 5% of the total activated carbon. These mesopores serve two main purposes: firstly, they act as channels for transporting adsorbed substances (cigarette smoke) to the edges of the micropores; secondly, they act as adsorbates for larger molecules (harmful substances) in cigarette smoke, and under sufficiently high suction, capillary condensation causes harmful substance vapors to be adsorbed into the mesopores. Activated carbon also has larger macropores, generally around 50-200 nm, but their volume proportion is smaller, limiting their specific surface area effect. They have a weaker adsorption capacity for small-molecule harmful substances, primarily adsorbing large-molecule harmful substances and particulate matter in cigarette smoke, and also acting as transport channels for the adsorbate (cigarette smoke).

[0017] This invention utilizes the highly developed pore structure, high micropore content, abundant surface functional groups, large specific surface area, and strong adsorption performance of activated carbon. It can rapidly enrich harmful substances in cigarette smoke, and with sufficient activated carbon, it exhibits significant and efficient adsorption and purification effects on volatile and semi-volatile harmful components in cigarette smoke. For example, it shows high adsorption efficiency for small molecule compounds such as formaldehyde, acetaldehyde, butanone, acrolein, 1,3-butadiene, hydrogen cyanide, toluene, styrene, and isoprene. However, activated carbon lacks uniform pore size; its pore size distribution is very wide, and it does not possess sieving capabilities. Activated carbon with high micropore content also suffers from high mass transfer resistance. Its adsorption effect on particulate matter and CO is poor, and its adsorption of phenolic macromolecules is relatively low. Therefore, this invention utilizes the mesopores and macropores of a porous foam ceramic framework to adsorb particulate matter and phenolic macromolecules, and uses natural zeolite molecular sieves to adsorb CO and ionicly charged polar small molecules, thus compensating for the insufficient adsorption capacity of activated carbon.

[0018] 3. Natural zeolite (or diatomaceous earth) possesses molecular sieve functionality and is a mineral composed of aluminosilicate crystals with a regular pore structure. my country possesses abundant deposits of mordenite and clinoptilolite. Due to the uniform pore size and extremely high specific surface area, natural zeolite molecular sieves exhibit excellent adsorption properties. They selectively adsorb molecules of different sizes and shapes, as well as molecules with different polarities and unsaturated polarized oxygen molecules, demonstrating strong affinity.

[0019] The pore diameter of natural zeolite molecular sieves is generally 0.6-1.5 nm, which is comparable to the size of small molecules of common harmful substances in cigarette smoke. The pore size of the molecular sieve determines that small molecules of harmful substances that can enter the pores are easily adsorbed, while large molecules in cigarette smoke cannot enter the sieve channels and therefore cannot be adsorbed. At the same time, strongly polar or easily polarized molecules are also easily adsorbed by molecular sieves. For example, in a mixture of carbon monoxide (CO) and argon (Ar), both have similar diameters, less than 0.4 nm, but CO is a polar molecule while Ar is a nonpolar molecule; therefore, the amount of CO adsorbed by natural zeolite molecular sieves is much greater than that of Ar. In addition, small molecules of harmful substances containing double bonds are polarizable molecules and have a strong affinity for molecular sieves; the greater the degree of unsaturation of the molecule, the stronger the adsorption.

[0020] Natural zeolite molecular sieves exhibit varying degrees of adsorption and filtration effects on harmful components in cigarette smoke, such as benzene compounds, polycyclic aromatic hydrocarbons, phenolic components, and tobacco-specific nitrosamines.

[0021] The purpose of this invention in using natural zeolite molecular sieves is to enhance the adsorption capacity of small molecule harmful substances in cigarette smoke on the basis of activated carbon, making up for the shortcomings of activated carbon, and effectively filtering, adsorbing and purifying carcinogens and toxic substances in cigarette smoke.

[0022] However, the pore size of natural zeolite molecular sieves is generally less than 2 nm, resulting in poor adsorption of large molecular harmful substances. Therefore, this invention combines natural zeolite with activated ash and attapulgite, creating a porous foam ceramic framework. This framework overcomes the limitations of individual micropores, mesopores, and macropores found in attapulgite, activated carbon, and natural zeolite. It can comprehensively adsorb NNK, benzo[a]pyrene, HCN, phenol, crotonaldehyde, CO, ammonia, and tar from cigarette smoke without affecting the sensory quality of cigarettes, significantly improving the effect that cannot be achieved by a single material.

[0023] 4. Based on attapulgite (porous foam ceramic skeleton), activated carbon, and natural zeolite molecular sieve, the present invention adds graphene oxide (or carbon nanotubes, graphene and its derivatives) to further improve the adsorption and catalytic effect on harmful components of cigarette smoke.

[0024] Graphene oxide is a product of chemical oxidation of graphite powder. It is a novel carbon material with excellent performance, extremely high specific surface area and abundant surface functional groups, and has extremely high adsorption and catalytic effects.

[0025] Graphene oxide contains oxygen-containing functional groups such as carbonyl, epoxy, hydroxyl, carboxyl, and ester groups. Due to the presence of these functional groups, the thickness of graphene oxide can reach 1.1 ± 0.2 nm. These oxygen-containing functional groups in graphene oxide readily react with compounds in cigarette smoke containing harmful groups such as amino, carboxyl, and isocyanate groups to form harmless substances. This can significantly and effectively reduce the release of HCN, crotonaldehyde, and tar in cigarette smoke, thereby increasing the purification effect on harmful substances in cigarette smoke.

[0026] 5. In this invention, metal oxides (such as alumina and zinc oxide) are mixed and added to attapulgite, activated carbon, and natural zeolite. The purpose is the same as adding graphene oxide. It is based on attapulgite (porous foam ceramic skeleton), activated carbon, and natural zeolite molecular sieves, in order to further improve the adsorption and catalytic effect on harmful components of cigarette smoke.

[0027] Metal oxides are multi-component solid catalysts, consisting of particles of a specific shape and size, formed by the aggregation of numerous fine particles. Different aggregation methods result in surfaces with varying roughness, i.e., surface textures, while the interior of the particles forms a porous structure, which manifests as the catalyst's microstructural characteristics, namely specific surface area, pore volume, pore size, and pore distribution. The microstructural characteristics of metal oxide catalysts affect their catalytic reaction performance.

[0028] This invention utilizes catalytic metal oxide materials as additives, primarily through catalysis, to convert harmful substances in cigarette smoke into harmless substances. Among the seven representative harmful components of cigarette smoke, Co and crotonaldehyde are converted using catalytic metal oxide materials. For example, CO is converted to CO2 or undergoes a disproportionation reaction to form CO2 and C under the catalysis of metal oxide catalysts; crotonaldehyde can be oxidized to crotonic acid under the catalysis of metal oxide catalysts. Furthermore, adding catalytic materials such as metal oxides to activated carbon and natural zeolite carriers with large specific surface areas and mixing them together can enhance their activity, achieving almost efficient and clean removal of CO and crotonaldehyde.

[0029] 6. This invention employs an impregnation method, in which attapulgite, activated carbon, natural zeolite, graphene oxide and metal oxide are used as carriers to overlap and add polymer materials in the sintered porous foam ceramic molecular sieve filter tip. This is also to further improve the adsorption effect on harmful components of cigarette smoke, so as to achieve maximum clean removal of harmful substances.

[0030] Polymer materials are a type of polymer material, including natural and synthetic polymers. Natural polymers (such as cellulose, chitosan, porous starch, sodium alginate, etc.) contain functional groups such as active hydroxyl and amino groups, which can adsorb harmful substances in cigarette smoke through physical and chemical adsorption. Different types of polymers have varying degrees of adsorption effects on tar, nicotine, phenol, benzo[a]pyrene, CO, ammonia, volatile carbonyl compounds, NNK, HCN, and crotonaldehyde in cigarette smoke.

[0031] The addition of natural polymer materials during impregnation also helps to enhance the aroma of the smoke, improve the smoking quality of cigarettes, enhance the aroma and reduce the irritation of the smoke. While reducing the tar content of the smoke, it helps to maintain the sensory quality of cigarettes unchanged and stable.

[0032] 7. Natural plant extracts are natural organic compounds extracted from natural plants (such as tea polyphenols, flavonoid flavorings, gallic acid, carotene, glutathione, lutein, etc.). These materials have high nutritional value and bioactivity, and compared with chemically synthesized materials, they have lower toxicity and side effects. The final product of plant extracts can be in liquid, oil, or other forms.

[0033] This invention employs an impregnation method, in which attapulgite, activated carbon, natural zeolite, graphene oxide and metal oxide are used as carriers to impregnate and add natural plant extracts in a porous foam ceramic molecular sieve filter tip prepared by sintering. This is also to further purify and reduce various harmful components in the mainstream cigarette smoke, to achieve the maximum clean removal of harmful substances, and to adjust the quality and aroma of cigarettes.

[0034] Natural plant extracts typically contain antioxidant chemical components and possess a porous structure and large specific surface area. They react with harmful components in mainstream cigarette smoke, efficiently removing phenol, benzo[a]pyrene, nicotine, HCN, free radicals in tar, various polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, and free radicals through physical and chemical adsorption, thus achieving the goal of reducing tar and harm. Furthermore, they can significantly reduce the irritation to the respiratory system during inhalation, alleviate respiratory discomfort, and improve the comfort of cigarette smoking.

[0035] This invention relates to a porous foam ceramic molecular sieve filter tip, which primarily reduces tar and harm by adsorbing and enriching harmful substances in the particulate phase of cigarette smoke. The adsorption process in the filter tip is mainly physical adsorption, supplemented by catalytic and chemical adsorption. Activated carbon and natural zeolite, due to their well-developed pore structure and large specific surface area, possess superior adsorption performance, rapidly enriching harmful gaseous components in cigarette smoke to achieve a filtration effect. The filtration (separation) and adsorption principle is as follows: when cigarette smoke comes into contact with the porous foam / molecular sieve pore wall solid, one or more harmful substance components in the cigarette smoke accumulate on the pore wall solid surface due to physical action (assisted by van der Waals forces), thereby filtering (separating) and adsorbing and enriching one or more harmful substances. Essentially, the atoms on the porous pore walls and molecular sieve pore surface of the cigarette filter tip are subjected to asymmetrical effects, forming a residual force field that attracts harmful gas molecules and gas-solid particles near the surface.

[0036] The porous foam ceramic molecular sieve filter tip of this invention for cigarettes has a pore structure composed of three parts. The first part is a mesoporous-macroporous structure formed by a porous foam ceramic framework made of a mixture of attapulgite (or kaolin and other clay-like materials) and powder particles such as natural zeolite, activated carbon, graphene oxide, and metal oxides. The second part is the microporous-mesoporous structure inherent in the activated carbon particles themselves. The third part is the microporous structure inherent in the natural zeolite. The pore size of the porous foam ceramic molecular sieve filter tip is determined by the size of its internal specific surface area, and is also the main reason affecting the diffusion and adsorption of cigarette smoke gas molecules within the pores. Different pore structures obviously also have their own unique adsorption behaviors.

[0037] This invention relates to a porous foam ceramic filter tip that constructs pore structures of varying sizes. By utilizing different proportions of the main raw materials and different impregnation components, the selective adsorption of harmful substances in cigarette smoke can be optimized, including adsorption rate, number of adsorption layers, and maximum adsorption capacity. This adapts to the filtration and purification of different harmful substances in cigarette smoke, improves the diffusion performance of cigarette smoke, and thus increases the adsorption rate of harmful substances. It maximizes the clean removal of carcinogens and toxic substances from cigarette smoke, which is something that cellulose acetate / polypropylene fiber filters cannot achieve.

[0038] The porous foam ceramic molecular sieve filter of this invention exhibits different functions and effects based on the different pore structure distributions and adsorption behaviors. It can be designed and prepared into a porous foam ceramic skeleton with a porosity of about 40%-70% and a pore size between 0.5-100 micrometers, according to the needs of filtering, purifying and removing harmful substances from cigarette smoke.

[0039] The porous foam ceramic framework is composed of attapulgite mixed with activated carbon, natural zeolite, metal oxides, and other powder particles as sintering agents. Its macropores have a relatively large spatial structure (volume 0.2-0.8 cm³). 3 / g), with a relatively small specific surface area (less than 0.5cm²). 2 / g), with weak adsorption capacity, it easily forms a molecular layer adsorption on the surface, and can adsorb large molecules and heavy metal particles in the gas phase, mainly acting as a channel for the adsorbate (cigarette smoke gas); while the mesoporous structure formed by porous foam ceramic framework and activated carbon has a smaller pore size, about 5-100 nanometers, and a volume of 0.1-0.5 cm³. 3 / g, numerous, specific surface area 20-70m² 2 With a pore volume of approximately 0.02-0.10 mL / g, it serves as a channel for transporting adsorbed substances (cigarette smoke) to the edges of the micropores; simultaneously, it adsorbs larger molecules and particles in cigarette smoke, acting as a porosity that connects with both macropores and micropores. In the porous foam ceramic framework, due to the mixing and filling of a large (sufficient) amount of activated carbon and natural zeolite, the number of micropores is high, the pore size is small, and the micropore volume is 0.2-0.6 cm³. 3 / g, microporous bodies can account for more than 80% of the total pore volume, and their specific surface area can reach 200m². 2 / g, accounting for more than 95% of the total specific surface area of ​​the ceramic skeleton filter, the flue gas does not undergo capillary condensation in these microporous structures, and is the main body for adsorbing small molecule carcinogens and toxic and harmful substances in the mainstream flue gas.

[0040] The preparation of the porous foam ceramic filter tip of the present invention utilizes the easy sintering properties (clay function) of attapulgite particles (or kaolin and other clay-like materials) and combines them with raw materials such as activated carbon (or activated carbon short fibers), graphene oxide (or graphene and its derivatives), natural zeolite (or diatomaceous earth), metal oxides, and porous active minerals (such as maifanite). Activated carbon and natural zeolite, depending on requirements, can account for about 70% of the solid phase, mainly used for filtering and adsorbing small-molecule carcinogens and harmful substances in cigarette smoke. Graphene oxide and metal oxides account for about 10-20%, mainly playing an adsorption and catalytic role, adsorbing harmful substances in cigarette smoke and converting them into harmless substances. Attapulgite accounts for about 10-20%, mainly used to bind and construct a porous foam ceramic skeleton with macropores and mesopores, which can filter and condense some large-molecule harmful substances and heavy metals in cigarette smoke. Its porous foam skeleton can also be used to impregnate various polymer materials and natural plant extracts to further improve the removal of harmful substances and improve the quality, taste, and comfort of cigarettes. Through mixing (wet milling), the powder particles of attapulgite, activated carbon, natural zeolite, graphene oxide, and metal oxides are passed through a 300-mesh sieve, with a particle size of about 30-50 micrometers. The finer the powder particles of these main raw materials, the larger the specific surface area and the stronger the adsorption capacity. Then, the wet-milled slurry is subjected to vibration drying, wax (or adhesive) addition, spray granulation, pressing (or extrusion) molding, dewaxing and pore creation, and vacuum sintering at around 800℃ (at this temperature, activated carbon will not be carbonized again) to obtain a porous foam ceramic molecular sieve filter for cigarettes. In the sintered porous foam ceramic molecular sieve filter, each attapulgite / activated carbon / natural zeolite / graphene oxide / metal oxide particle connects with other particles at only a few points, thus forming a large number of three-dimensional interconnected pore structures. Generally, the average pore size of the formed porous foam ceramic (excluding the internal pore size of activated carbon and natural zeolite) increases with the increase of the size of the attapulgite / activated carbon / natural zeolite / graphene oxide / metal oxide particle skeleton, while the uniformity of pore distribution increases with the decrease of the size range of its skeleton particles.

[0041] This invention uses granular coconut shell or walnut shell activated carbon. Coconut shell activated carbon has a small pore size, a high specific surface area, and an adsorption capacity, which is beneficial for adsorbing small molecule harmful substances. (The coconut shell activated carbon granules used in this invention were provided by other manufacturers, and their preparation process technology is not within the scope of this invention). Attapulgite is relatively easy to obtain in nature; it is produced in Xuyi County, Jiangsu Province, my country.

[0042] This invention can control and adjust the pore size, porosity, and air permeability of porous foam ceramic molecular sieve filters by adjusting the composition ratio of the main raw materials and the process method. It can also efficiently and cleanly remove or precisely control the content of harmful substances such as tar, nicotine, carbon monoxide, HCN, benzo[a]pyrene, phenol, crotonaldehyde, and NNK, as well as the taste and comfort of cigarettes.

[0043] For example, porous foam ceramic molecular sieve filters for cigarettes with a pore size of approximately 1-50 micrometers and a porosity of approximately 60% can be prepared according to requirements. As another example: to cleanly adsorb phenolic substances, the proportion of graphene oxide added can be increased; to enhance the reduction of tar and nicotine content, the proportion of activated carbon (or activated carbon short fibers) added can be increased; to cleanly remove Co from cigarette smoke, the proportion of natural zeolite added can be increased; to cleanly filter and remove benzo[a]pyrene, Fe can be used. 2+ Porous foam ceramic molecular sieve filter tips impregnated and sintered with protoporphyrin compound solution.

[0044] In addition, the present invention can also, as needed, use an impregnation method to further impregnate the sintered porous foam ceramic molecular sieve filter tip with various natural plant extracts (fragrances, essential oils, etc.) to achieve further selective and clean removal of harmful substances in cigarette smoke, as well as to improve and adjust the quality, aroma and taste of cigarettes.

[0045] This invention relates to a porous foam ceramic molecular sieve filter for cigarettes. Due to the large and uniform distribution of activated carbon and natural zeolite, combined with the porous foam ceramic framework formed by attapulgite and the adsorption and catalytic effect of metal oxides, as well as the impregnation with polymers and natural plant extracts, it can efficiently remove harmful substances from cigarette smoke. Furthermore, it allows for the selective and overlapping impregnation of tar-reducing and harm-mitigating materials as needed, achieving even cleaner removal of carcinogens, toxic substances, and other harmful substances from cigarette smoke—something difficult to achieve with cellulose acetate / polypropylene fiber filters.

[0046] This invention can produce porous foam ceramic molecular sieve filters of different lengths, thicknesses, and fineness according to the needs of different brands of cigarettes, and directly connect and splice them with the ends of cigarette tobacco, and then wrap them with cigarette paper to form a porous foam ceramic molecular sieve filter cigarette.

[0047] This invention is the world's first porous foam ceramic molecular filter cigarette product.

[0048] The porous foam ceramic molecular sieve filter tip for cigarettes of this invention is easy to produce on an industrial scale, easy to operate, has controllable quality, and can reduce production costs. Detailed Implementation

[0049] The specific implementation method of the present invention, "A porous foam ceramic molecular sieve filter cigarette and its preparation method," is as follows:

[0050] (Due to the different equipment and requirements for producing porous foam ceramic molecular sieve filter cigarettes, the specific preparation process, parameters, and proportions of main raw materials such as attapulgite, activated carbon, natural zeolite, metal oxides, and graphene oxide can be adjusted to achieve the best / expected performance indicators.)

[0051] 1. Main raw material proportioning process

[0052] The main raw materials for preparing the porous foam ceramic molecular sieve filter tip for cigarettes of this invention are: attapulgite (or kaolin and other clay-like materials), activated carbon (or activated carbon short fibers), natural zeolite (or diatomaceous earth), graphene oxide (or graphene and its derivatives), and metal oxides (such as zinc oxide, aluminum oxide, etc.). The raw material ratio is usually: attapulgite accounts for about 10-20%, activated carbon and natural zeolite account for about 70%, and metal oxides and graphene oxide account for about 10-20%. The addition or reduction of these main raw materials and the precise proportion of the ingredients can be adjusted and varied to a wide range according to needs or experimental research results, so as to achieve the best clean and efficient filtration and removal of carcinogens, toxic substances and harmful substances in cigarette smoke.

[0053] 2. Mixing (wet grinding) process

[0054] The main raw materials, such as attapulgite particles, natural zeolite particles, activated carbon particles, metal oxide particles, and graphene oxide particles, are mixed according to the proportion of the ingredients. Then, they are placed in a steel drum ball mill (using wet grinding method with alcohol as the grinding medium) and wet ground for about 4-6 hours. After that, the alcohol is recovered by vibration drying and sieved through a 300-mesh sieve to obtain a powder mixture with a particle size of about 30-50 micrometers.

[0055] Typically, the pore size forming the porous foam ceramic skeleton increases with the increase in particle size of the powder mixture, while the uniformity of pore distribution increases with the decrease in the particle size range of the powder mixture. The finer the powder mixture particles, the larger the specific surface area, and the stronger the ability to adsorb harmful substances in cigarette smoke. The main purpose of the wet milling process is to grind the main raw material powder particles uniformly, ensuring consistent size, and grinding the powder particles into round shapes and finer particles. (Note: The raw and auxiliary materials used in this invention, such as coconut shell activated carbon particles, attapulgite particles, natural zeolite particles, metal oxide particles, graphene oxide particles, industrial alcohol, paraffin wax, etc., are all provided by other specialized manufacturers and are not within the scope of this invention.)

[0056] 3. Granulation process with added wax (or adhesive)

[0057] The above-mentioned dried and sieved main raw material powder mixture is placed in a spiral mixer, and about 40-60% (by volume) of liquid paraffin is added. After mixing evenly, it is dried by spray dryer to produce round powder particles of about 0.2-0.5 mm.

[0058] The purpose of adding wax is twofold: firstly, it acts as a forming agent, primarily to give the pressed (extruded) filter preform, composed of powders such as attapulgite, activated carbon, natural zeolite, metal oxides, and graphene oxide, a certain strength, preventing it from collapsing during subsequent processes (such as handling and transportation); secondly, paraffin wax acts as a pore-forming agent. After the pressed (extruded) filter has solidified, the paraffin wax is removed through dewaxing, leaving a large number of pores in the filter preform. The content, size, and distribution of these pores depend on the amount of paraffin wax and the size of the main raw material powder mixture particles. The open porosity increases with the amount of paraffin wax used; when the paraffin wax content reaches a certain level, the open porosity becomes very close to the porosity. Therefore, the amount of paraffin wax added can control the final porosity and pore size of the porous foam ceramic molecular sieve filter framework for cigarettes (excluding the molecular sieve pore size within the activated carbon particles and natural zeolite particles themselves).

[0059] The purpose of the granulation process is to ensure that the powder mixture particles have good flowability, so that they can fill the mold cavity during pressing (extrusion) molding.

[0060] 4. Compression (extrusion) molding process

[0061] Based on the size and shape specifications of cigarette filters (generally, cigarette filters are cylindrical, with a diameter × length of approximately ∮8 × 25 mm; the length, thickness, and other dimensions can be flexibly adjusted according to the needs of the cigarette brand), design and manufacture the molds for pressing (or extrusion) molding, including the loose packing space of the main raw material powder mixture and the relationship between dense pressing and sintering shrinkage ratio, etc.

[0062] (Note: The molds used for compression (extrusion) molding are usually designed and manufactured by specialized mold designers and process departments. The scope of this invention does not involve the design and manufacture of compression (extrusion) molding molds.)

[0063] The main raw material powder mixture particles, which are spray-granulated with wax, are placed in a pressing (extrusion) molding die and pressed (extruded) in a press (extruder) with a capacity of about 15 tons to obtain a porous foam ceramic filter tip semi-finished product compact.

[0064] In the pressing (extrusion) molding process, under certain pressure, the strength of the compact increases with increasing pressure, the powder mixture particles are densified, and the density of the filter tip also increases. Consequently, in the subsequent sintering process, the pore walls of the porous foam skeleton become denser, thereby improving the pore wall strength and the overall strength of the ceramic skeleton, thus increasing the strength of the porous foam ceramic molecular sieve filter tip.

[0065] Furthermore, considering the tail end of the porous foam ceramic molecular sieve filter tip (the end in contact with the lip), the black spots of activated carbon are exposed, affecting its appearance. To address this, a two-stage feeding method can be used in the pressing and molding process: first, the wax-coated spray-granulated main raw material powder mixture is fed into the pressing mold; then, it is fed again, covering it with a 1-2 mm layer of main raw material powder mixture containing activated carbon; finally, it is pressed and molded in a press (extruder). This method prevents the black activated carbon from showing at the tail end of the filter tip.

[0066] 5. Dewaxing and pore-forming process

[0067] The porous foam ceramic molecular sieve filter tip semi-finished product, which has been pressed (extruded), is placed in a bell-type dewaxing furnace and held at a temperature of approximately 100-200℃ (the temperature at which paraffin wax melts and flows out but has not yet decomposed) for about 4-6 hours to dewax (recover the paraffin wax). Although the paraffin wax is solidified during the pressing (extruded) process, it will flow out and be discharged during the dewaxing process. As a result, a large number of pores are left in the porous foam ceramic molecular sieve filter tip semi-finished product, resulting in the dewaxed porous foam ceramic molecular sieve filter tip semi-finished product blank.

[0068] 6. Sintering (vacuum sintering / sintering in inert gas) process.

[0069] The semi-finished blank of the porous foam ceramic molecular sieve filter for cigarettes, obtained by pressing (extrusion) molding, dewaxing and pore-forming, is placed in a vacuum sintering furnace (or under inert gas protection) and held at a temperature of about 800-1000℃ (at which activated carbon will not be carbonized again) for about 2-4 hours for solid-phase sintering. After cooling, the finished filter is obtained, which has a porous foam ceramic framework with a large specific surface area, high specific strength, pore size of 0.1-100 micrometers and porosity of 40-60%, and a porous foam ceramic molecular sieve with a pore size (mesopore) of 2-100 nanometers and a pore size (micropore) of less than 1 nanometer, and a solid phase accounting for more than 70%.

[0070] Sintering is a crucial step in the process, primarily aimed at controlling the microstructure and properties of the porous foam ceramic molecular sieve filter. During sintering, due to the excellent sintering properties of attapulgite, attapulgite particles connect and aggregate activated carbon particles, natural zeolite particles, metal oxide particles, and graphene oxide particles together, thereby obtaining the desired porous foam ceramic molecular sieve filter with highly efficient and clean filtration and adsorption capabilities for removing carcinogens, toxic substances, and harmful substances from cigarette smoke, as well as the ability to convert harmful substances into harmless substances through catalytic reactions.

[0071] 7. Impregnation and finishing process (optional)

[0072] This step is optional, primarily depending on the needs of smokers. It's an additional process to selectively adsorb and filter harmful substances from cigarette smoke, improving the quality, taste, comfort, and aroma of cigarettes. The method involves immersing the sintered porous foam ceramic molecular sieve filter tip in solutions of various natural polymers (such as cellulose, chitosan, sodium alginate, and porous starch) or natural plant extracts (such as jasmine, rose, peppermint, woody notes, sandalwood, tea polyphenols, flavonoids, gallic acid, and lutein). This mixture is then coated onto the pores of the porous foam ceramic framework and the surfaces of activated carbon particles, natural zeolite particles, metal oxide particles, and graphene oxide particles. After drying, the aroma of these natural polymers and plant extracts remains inside the porous foam ceramic molecular sieve filter tip, further adsorbing and filtration harmful substances from cigarette smoke, thus improving the quality, taste, aroma, and comfort of cigarettes.

[0073] 8. Assembly process

[0074] The porous foam ceramic molecular sieve filter tip, which has been sintered and impregnated, is connected and spliced ​​to the end of the cigarette tobacco. Then, it is wrapped together with cigarette paper. The splicing method is basically the same as that of the cellulose acetate / polypropylene fiber filter tip. In this way, the porous foam ceramic molecular sieve filter tip cigarette product can be obtained.

[0075] Of course, porous foam ceramic molecular sieve filters can also be assembled on the same production line that assembles cellulose acetate / polypropylene fiber filters.

[0076] 9. Packaging.

[0077] The assembled porous foam ceramic molecular sieve filter cigarette products are then packaged into cigarette boxes according to requirements for refined and personalized product packaging.

Claims

1. A porous foam ceramic molecular sieve filter cigarette and its preparation method, comprising the following steps: (1) Using materials such as attapulgite (or kaolin and other clay-like materials), activated carbon (or activated carbon short fibers), natural zeolite (or diatomaceous earth), graphene oxide (or graphene and its derivatives), and porous active minerals as the main raw materials, a porous foam ceramic molecular sieve filter for cigarettes is prepared by special processes such as mixing, waxing (or glue), pressing (or extrusion) molding, and high-temperature sintering. (2) The porous foam ceramic molecular sieve filter tip described in claim (1) is connected and spliced ​​with the end of the cigarette tobacco, and then wrapped together with cigarette paper to make a porous foam ceramic molecular sieve filter tip cigarette product. (3) In the porous foam ceramic molecular sieve filter tip described in claim (1), various tar-reducing and harm-reducing functional materials or high molecular polymers and natural plant extracts are further (or overlapped) added by impregnation method, thereby improving the efficiency of filtering harmful substances in cigarette smoke and improving the quality, taste and comfort of cigarettes.