CN101611927B - Catalyst capable of reducing carbon monoxide content in cigarette smoke, preparation method and application of same - Google Patents

Abstract

The invention belongs to the field of cigarette harm reduction and coke reduction, and relates to a catalyst capable of reducing the carbon monoxide content of cigarette smoke at normal temperature, a preparation method and an application. Mesoporous alumina with higher surface area and more surface basic sites was synthesized with different structure-directing agents as the carrier of the catalyst, and the nano-metal The catalytically active components are highly dispersed on the surface of the carrier, and a mesoporous metal alumina catalyst is prepared. The specific surface of the catalyst is 100-400m ² /g, the pore diameter is 2.0-10.0nm, the surface alkalinity of the mesoporous metal alumina is 0.01-0.08mmol/g, and the surface isoelectric point (IEP value) is pH=8～ 10. The catalytically active component is nanometer metal. The catalyst of the invention can completely oxidize carbon monoxide into carbon dioxide at normal temperature, and can selectively reduce the content of carbon monoxide in cigarette smoke by 10-30% when added to cigarette filter sticks.

Description

Catalyst for reducing carbon monoxide content in cigarette smoke, preparation method and application

technical field

The invention belongs to the field of cigarette harm reduction and coke reduction, and specifically relates to a catalyst capable of reducing the carbon monoxide content of cigarette smoke at normal temperature, a preparation method and application thereof.

Background technique

The study found that the main harmful substances in cigarette smoke include: carbon monoxide, nitrogen oxides, acrolein, volatile aromatic hydrocarbons, hydrocyanic acid, volatile nitrosamines, etc. in the gas phase of smoke; Polycyclic aromatic hydrocarbons, phenols, nicotine, nitrosamines (especially tobacco-specific nitrosamines), some heterocyclic compounds and trace radioactive elements, etc.; and free radicals that exist in both the gas phase and the particle phase. Among them, the content of CO and cigarette tar in the gas phase of the smoke is the highest, so it is also the most harmful to the human body. Once inhaled, it will combine with hemoglobin, and its affinity is more than 200 times greater than that of oxygen, resulting in hypoxia in the human body. For smokers, the crown The incidence of heart disease is high. Therefore, how to choose to reduce and eliminate harmful components such as carbon monoxide in cigarette smoke is very important to improve the safety of cigarette smoking, and it is also increasingly concerned by people.

In burning cigarettes, about 30% of carbon monoxide is produced by thermal decomposition of tobacco components, about 36% of carbon monoxide is produced by incomplete combustion of tobacco, and at least 23% of carbon monoxide is produced by the combination of carbon dioxide at high temperature produced by the carbon reduction reaction

In recent years, people have carried out a lot of research on reducing the amount of CO released in cigarette smoke. The methods that can be used mainly include punching holes in cigarette tipping paper and increasing the natural air permeability of cigarette paper to dilute the smoke concentration and add expanded shredded tobacco. Or tobacco flakes to reduce the amount of shredded tobacco, adding combustion enhancers to make shredded tobacco burn more completely, using composite filters to trap CO through adsorption, and using catalysts to convert CO into _CO2 , etc. In the early 1980s, Japan's Ichikawa Kiyoshi invented a porous material (such as activated carbon) filter [USPatent 4414988] containing a protoporphyrin compound solution impregnated with chelated ferrous ions, which can effectively remove the CO, benzo[a]pyrene and its derivatives, etc. The catalyst is added to the filter forming paper, and it can also be loaded on porous substances such as activated carbon and molecular sieve, and then made into a composite filter [USPatent, 4022223]. BAT proposed to add composite oxide M ₂ M'RuO ₆ (M is a divalent metal ion, M' is a trivalent rare earth metal, and the valence of Ru is pentavalent) [USPatent, 4182348] in the mouth rod, which can make the flue gas The content of CO decreased by 15% to 43%; the content of NO decreased by 36% to 73%. British Gallaher company has invented a kind of low-temperature catalytic oxidation CO to be the filter tip additive [USPatent, 4450245] of _CO , this catalyzer is to be composed of Cr, Sn, precious metal, transition metal and VI, VII, the crystallite (multiple metals of group VIII) In the form of crystal particles), highly dispersed in the entire pore system of the carrier (molecular sieve, diatomaceous earth, etc.), in addition, the carrier itself can sometimes play a catalytic role, so that this type of catalyst often plays a dual-function role. In 1980, a British patent reported a catalyst [UK Patent, 2042364A] loaded with active components such as 6 wt% Cu and 0.5 wt% Pd on 13X molecular sieve, which was used for CO oxidation in cigarette smoke. When the reaction temperature was 150 °C, CO The conversion rate can reach 76%, and the increase or decrease of the reaction temperature will reduce the activity of the catalyst. In 1997, a U.S. patent report [USPatent, 5671758] used simple oxides such as V ₂ O ₅ , Mo ₂ O ₃ or Rh ₂ O as catalysts to be loaded on activated carbon or other filter materials and then added to the filter. , can oxidize CO in flue gas to CO ₂ . K. B. Kohler et al. supported nanometer metal oxide catalysts [CN1805694] on high surface area carrier particles and added them to shredded tobacco or cigarette paper, which is said to reduce the carbon monoxide content in mainstream smoke. S. Godvanishvili et al. have incorporated catalyst particles into tobacco shreds and/or cigarette paper used to form cigarettes, which can reduce carbon monoxide and/or nitrogen oxides in mainstream smoke [CN101374429]. Lu Gongxuan and others invented a nano-precious metal catalyst [CN1460548] that can reduce the amount of carbon monoxide released in mainstream cigarette smoke, which can reduce the amount of carbon monoxide released in mainstream smoke by 20-45% when applied to cigarettes. Zhu Jianhua and others invented a mesoporous silicon-based functional material containing rare earth metal or transition metal atoms [CN1460641], which can reduce the total content of nitroso compounds in cigarette smoke by 30-47%. Meng Zhaoyu et al. have invented a surface-modified mesoporous silicon-based molecular sieve (such as MCM-41, SBA-15, etc.) adsorbent for cigarette tip rods and its preparation method [CN101077223]. This adsorbent is added to cigarette filters to make The composite mouth stick can significantly reduce the content of tar, low molecular aldehydes and ketones, nitrosamines, fused ring aromatics and other harmful substances in the smoke, and at the same time improve the sensory quality of cigarettes. Recently, Philip Morris company announced relevant nanometer metal and its oxide catalyst and its addition in shredded tobacco or cigarette paper, can reduce the carbon monoxide content [US Patent 7,243,658] in mainstream smoke, [US Patent, 7,228,862], [US Patent , 7,165,553], [US Patent, 7,152,609], [US Patent, 7,011,096]. Therefore, how to research and develop new materials and new methods for reducing CO content in flue gas has always been a hot issue in this field.

However, the preparation of mesoporous metal alumina catalysts with surface basicity and its use in reducing harmful substances such as carbon monoxide in cigarette smoke have not been reported yet.

Contents of the invention

The purpose of the present invention is to provide a catalyst with high catalytic activity for removing CO in flue gas and its application.

Another object of the present invention is to provide several preparation methods of the above-mentioned catalysts.

The invention provides a mesoporous aluminum oxide with surface basicity and its catalyst containing nanometer metal, which is applied in cigarettes to reduce the emission of carbon monoxide in mainstream smoke of cigarettes.

The purpose of the present invention is achieved in the following manner:

The catalyst of the invention contains mesoporous alumina carrier and nanometer metal; the basic position on the surface of the mesoporous alumina carrier is: 0.01-0.08mmol [OH ^- ]/g, and the surface isoelectric point is pH=8-10.

The specific surface of the mesoporous alumina carrier of the catalyst of the invention is 100-400m ² /g, and the pore diameter is 2.0-10nm.

The catalyst also contains one or more of rare metals, transition metals or their oxides.

The nanometer metal is selected from one or more of Au, Pt, and Pd.

The preparation method of the mesoporous alumina (Al ₂ O ₃ ) carrier of the present invention is:

In the present invention, one or more of chitosan, surfactant P123 (EO ₂₀ PO ₇₀ EO ₂₀ ), and cetyltrimethylammonium bromide (CTABr) are used as structure-directing agents, and aluminum nitrate, secondary Aluminum butoxide is used as the aluminum source, and a mesoporous alumina (Al ₂ O ₃ ) carrier with a higher specific surface area and more basic sites on the surface is prepared by hydrolysis, separation by filtration, drying, and calcination.

During the preparation process of the mesoporous alumina (Al ₂ O ₃ ) support, it can also be prepared by doping with rare earth metal compounds.

Using the mesoporous alumina (Al ₂ O ₃ ) carrier prepared above, the nano-metal catalytic active components (such as gold (Au), platinum Pt One or several catalytically active components in precious metals such as palladium and Pd) are highly dispersed on the surface of the support, and a mesoporous metal alumina catalyst containing nanometer metals is prepared.

The prepared mesoporous metal-containing alumina catalyst is added to cigarette filter sticks or cigarette forming paper and grooved paper to reduce the amount of carbon monoxide released in cigarette mainstream smoke.

The catalyst prepared by the present invention preferably contains one or more catalytically active components of precious metals such as gold (Au), platinum Pt or palladium Pd, and rare earth metals or oxides thereof (such as La, Ce, etc.).

The mass content of the nano metal particles is 0.01-2.5%, and the size of the nano metal particles is 2-10nm.

Preparation method concrete steps of the present invention are as follows:

1. Preparation of mesoporous Al ₂ O ₃ support

One or more of chitosan, P123 (EO ₂₀ PO ₇₀ EO ₂₀ ) and cetyltrimethylammonium bromide (CTABr) are used as structure-directing agents, and aluminum nitrate and aluminum sec-butoxide are used as Aluminum source, adding certain rare earth metal compounds (such as La, Ce, etc.), prepared mesoporous alumina (Al ₂ O ₃ ) carrier.

2. The catalyst preparation method is:

(1) Preparation by homogeneous deposition-precipitation method (HDP), take HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution and mesoporous Al ₂ O ₃ carrier, mix well, and slowly heat to 70-80°C. At the same time, add urea to adjust the pH of the solution to 7, and keep at this temperature for 3.5-4.5h. Filter, wash with hot water (preferably 70-80°C) several times, use AgNO ₃ (preferably 0.10mol/L) to detect the absence of Cl ^- , and dry at 65-75°C for 8-10h. Then calcined at 330-370°C for 0.5-1.5h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h.

(2) Preparation by deposition-precipitation (DP), using Na ₂ CO ₃ as precipitant to adjust HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution to pH = 7, under vigorous stirring, oxidize 1.0 g of mesoporous metal Add the carrier to it, react for 3.5-4.5h, wash with hot water at 70-80°C for several times, detect no Cl ^- with AgNO ₃ (preferably 0.10mol/L), and dry at 65-75°C for 8-10h. Then calcined at 330-370°C for 0.5-1.5h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h. .

(3) Preparation by anion exchange method (DAE), mix uniformly a certain concentration of HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution and 1.0 g of mesoporous metal oxide carrier, and stir at room temperature for 1-2 hours. Filter, wash with ammonia water (20% V/V) three times, and then wash with water several times, detect no Cl ^- with AgNO ₃ (preferably 0.10mol/L), and dry at 65-75°C for 8-10h. Then calcined at 330-370°C for 0.5-1.5h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h.

Preferably HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution concentration 9.71mmol/L and 1.0g mesoporous Al ₂ O ₃ carrier.

In the process of preparing the catalyst by the above three methods, a transition metal salt may also be added and mixed with the mesoporous alumina carrier.

3. The application method of the present invention is:

(1) Catalyst tableting, sieving, selecting 20-80 mesh particles;

(2) Disperse the 20-80 mesh catalyst particles in the cellulose acetate tow to make a binary composite filter rod for cigarettes, each cigarette filter rod contains 5-50 mg of catalyst, and roll the composite filter rod to form a cigarette.

(3) Coat 20-80 mesh catalyst particles on the surface of cigarette forming paper and grooved paper, each cigarette contains 5-50 mg of catalyst, and roll into cigarettes.

The mesoporous alumina carrier used in the present invention is different from the traditional mesoporous silicon-based carrier, and its characteristic is that the surface of the carrier has abundant surface basic sites, and the surface isoelectric point is high, which is conducive to loading highly dispersed precious metals such as nano-Au, Pt and Pd Catalytically active components, while the isoelectric point of the surface of traditional mesoporous silicon-based mesoporous supports is low, it is difficult to obtain highly dispersed nano-Au, Pt and Pd catalysts. In addition, using the mesoporous alumina prepared in the present invention as a carrier, the prepared nano-metal catalyst has low metal content, high dispersion, and higher catalytic activity for removing CO in flue gas. The catalyst prepared by the invention also has the characteristics of significantly reducing the carbon monoxide content in mainstream smoke of cigarettes at normal temperature, and the removal rate can reach 10-30%. The invention is simple in preparation, convenient in operation and low in cost.

Description of drawings

Accompanying drawing 1: The TEM photo of the 2.0% Au (HDP) catalyst supported on the mesoporous alumina (meso-Al ₂ O ₃ -a) of the present invention and the gold particle size distribution diagram.

Accompanying drawing 2: The TEM photo of the 2.0% Au (HDP) catalyst loaded on the mesoporous alumina (meso-Al ₂ O ₃ -b) of the present invention and the distribution diagram of gold particle size.

Accompanying drawing 3: The TEM photo of the 2.0% Au(HDP) catalyst loaded on the mesoporous alumina (meso-Al ₂ O ₃ -c) of the present invention and the distribution diagram of gold particle size.

Accompanying drawing 4: The TEM photo and the gold particle size distribution diagram of the 2.0% Au(HDP) catalyst loaded on the mesoporous alumina (meso-Al ₂ O ₃ -d) of the present invention.

Detailed ways

The following examples are intended to illustrate the present invention without further limiting the invention.

Example 1

Synthesis of carrier meso-Al ₂ O ₃ -a: 6.078g template agent P123 (EO ₂₀ PO ₇₀ EO ₂₀ ) and 0.060g LaCl ₃ were dissolved in 25ml sec-butanol, and 5.4ml aluminum sec-butoxide was added under stirring. After stirring at room temperature for 1 hour, a mixture of water and sec-butanol (1.14ml H ₂ O/10mlsec-butanol) was slowly added dropwise, and the composition of the mixture was 0.01 La ³⁺ : 1.0Al(Bu ^s O) ₃ : 0.10EO ₂₀ PO ₇₀ EO ₂₀ : 3.0 H ₂ O: 15.5 Bu ^s OH. The mixture was stirred at 45°C for 48 hours, filtered, dried, and calcined at 500°C for 6 hours in an air atmosphere to obtain the product, which was labeled as meso-Al ₂ O ₃ -a. The specific surface of meso-Al ₂ O ₃ -a measured by low temperature N ₂ adsorption-desorption method is 325m ² /g, the _pore volume is 0.93cm ³ /g, and the average pore diameter is 7.5nm; The surface alkalinity measured by CO ₂ -TPD method is 0.0369 mmol [OH ^- ]/g; the isoelectric point IEP of the carrier surface is pH=8.4.

Prepared by homogeneous deposition-precipitation method (HDP), take a certain amount of HAuCl ₄ (concentration: 9.71mmol/L) and 1.0g carrier meso-Al ₂ O ₃ -a, mix uniformly, and slowly heat to 70-80°C. At the same time, urea was added to adjust the pH of the solution to 7, and the temperature was maintained for 4 hours. Filter, wash with hot water (70-80°C) several times, detect no Cl ^- with AgNO ₃ (0.10mol/L), and dry at 70°C for 8-10h. Then calcined at 350°C for 1.0h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 1.0h to obtain the catalyst Au/meso-Al ₂ O ₃ -a(HDP). The specific surface of Au/meso-Al ₂ O ₃ -a (HDP) was determined by low-temperature N ₂ adsorption-desorption method to be 258m ² /g, the pore volume was 0.49cm ³ /g, and the average pore diameter was 4.9nm; (TEM) observed that the average size of nano-Au particles on the surface of the carrier was 4.4nm. (see accompanying drawing 1).

The catalyst Au/meso-Al ₂ O ₃ -a (HDP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Smoke on a Filtrona COA200 linear smoking machine (puffing capacity 35ml/min), measure the CO content in the cigarette smoke according to YC/T-30-1996 (non-scattering infrared method), and compare it with the cigarette without adding catalyst, The results show that, compared with the control cigarette, the catalyst prepared by the invention can reduce the CO content in mainstream smoke by 15%.

Example 2

Precipitation-precipitation method (DP) preparation, with meso-Al ₂ O ₃ -a prepared in Example 1 as carrier, with Na ₂ CO ₃ as precipitant, HAuCl ₄ solution (concentration is 9.71mmol/L) is adjusted to pH =7, under vigorous stirring, add 1.0g carrier meso-Al ₂ O ₃ -a to it, react for 4h, filter, wash with hot water (70-80°C) several times, detect with AgNO ₃ (0.10mol/L) Without Cl ^- , dry at 70°C for 10h. Then calcined at 350°C for 1.0h, cooled to room temperature, and then reduced with hydrogen at 300°C for 1.0h to obtain the catalyst Au/meso-Al ₂ O ₃ -a(DP). The specific surface of Au/meso-Al ₂ O ₃ -a (DP) measured by low temperature N ₂ adsorption-desorption method is 209m ² /g, the pore volume is 0.45cm ³ /g, and the average pore diameter is 4.7nm; the surface of the carrier is nanometer The average size of the Au particles is 4.9 nm.

The catalyst Au/meso-Al ₂ O ₃ -a (DP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 12%.

Example 3

Prepared by anion exchange method (DAE), using the meso-Al ₂ O ₃ -a prepared in Example 1 as a carrier, mix the HAuCl4 solution with a concentration of 9.71mmol/L and 1.0g carrier evenly, and stir at room temperature for 1.5h. Filter, wash with ammonia water (20% V/V) three times, and then wash with water several times until no Cl ^- is detected by AgNO3 (0.10 mol/L). Dry at 70°C for 10h, calcinate at 350°C for 1.0h, cool to room temperature, and reduce with hydrogen at 300°C for 1.0h to obtain the catalyst Au/meso-Al ₂ O ₃ -a (DAE). The specific surface of Au/meso-Al ₂ O ₃ -a (DAE) measured by low temperature N ₂ adsorption-desorption method is 300m ² /g, the pore volume is 0.87cm ³ /g, and the average pore diameter is 6.7nm; the surface of the carrier is nanometer The average size of the Au particles is 3.9 nm.

The catalyst Au/meso-Al ₂ O ₃ -a (DAE) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 10%.

Example 4

Synthesis of carrier meso-Al ₂ O ₃ -b: (a) 0.8g NaOH was dissolved in 4ml H ₂ O, added to 80ml triethanolamine, heated at 120°C for 5min to remove the water, and 21.8ml Add aluminum sec-butoxide dropwise, heat to 150°C and keep it for 10 minutes, this is solution one; (b) Dissolve 14.56g of cetyltrimethylammonium bromide (CTABr) in 240ml of water at 60°C , this is solution two; (c) maintain a constant temperature of 60 ° C, under vigorous stirring, slowly add solution one to solution two, and age for 72 hours. Filtered, washed twice with absolute ethanol, dried at 30°C, and calcined at 500°C for 5 hours in an air atmosphere to obtain the product, which was marked as meso-Al ₂ O ₃ -b. The specific surface of meso-Al ₂ O ₃ -b measured by low temperature N ₂ adsorption-desorption method is 302m ² / _g , the pore volume is 0.78cm ³ /g, and the average pore diameter is 7.2nm; The basicity of the surface measured by CO ₂ -TPD method is 0.0606mmol [OH ^- ]/g; the isoelectric point IEP of the carrier surface is pH=9.4.

The catalyst Au/meso-Al ₂ O ₃ -b (HDP) was prepared according to the homogeneous deposition precipitation method (HDP) in Example 1. The specific surface of Au/meso-Al ₂ O ₃ -b (HDP) was determined by low-temperature N ₂ adsorption-desorption method to be 310m ² /g, the pore volume was 0.48cm ³ /g, and the average pore diameter was 4.0nm; (TEM) observed that the average size of nano-Au particles on the surface of the carrier was 3.2nm. (See Attachment 2)

The catalyst Au/meso-Al ₂ O ₃ -b (HDP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 26.4%.

Example 5

Using the meso-Al ₂ O ₃ -b prepared in Example 4 as a carrier, the catalyst Au/meso-Al ₂ O ₃ -b (DP) was prepared according to the deposition precipitation method (DP) in Example 2. The specific surface of Au/meso-Al ₂ O ₃ -b (DP) measured by low temperature N ₂ adsorption-desorption method is 259m ² /g, the pore volume is 0.54cm ³ /g, and the average pore diameter is 4.0nm; the surface of the carrier is nanometer The average size of the Au particles is 4.2 nm.

The catalyst Au/meso-Al ₂ O ₃ -b (DP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. In each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 23.5%.

Example 6

Using the meso-Al ₂ O ₃ -b prepared in Example 4 as a carrier, the catalyst Au/meso-Al ₂ O ₃ -b (DAE) was prepared according to the anion exchange method (DAE) in Example 3. The specific surface of Au/meso-Al ₂ O ₃ -b (DAE) measured by low temperature N ₂ adsorption-desorption method is 305m ² /g, the pore volume is 0.59cm ³ /g, and the average pore diameter is 4.3nm; the surface of the carrier is nanometer The average size of the Au particles is 3.5 nm.

The catalyst Au/meso-Al ₂ O ₃ -b (DAE) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 19.3%.

Example 7

Synthesis of carrier meso-Al ₂ O ₃ -c: Dissolve 4.60g Al(NO ₃ ) ₃ 9H ₂ O in 20ml deionized water, then slowly add this solution to 50ml CH ₃ COOH solution containing 1.50g chitosan (5% V/V) under vigorous stirring for one hour. This solution was then slowly added to 800 ml (50% V/V) ammonia solution and kept under vigorous stirring for one hour. Then filter and dry at room temperature for 72 hours. Calcined at 550°C for 1.5 hours in air atmosphere to obtain the product, which is marked as meso-Al ₂ O ₃ -c. The specific surface of meso-Al ₂ O ₃ -c measured by low temperature N ₂ adsorption-desorption method is _271m ² /g, the pore volume is 0.48cm ³ /g, and the average pore diameter is 4.9nm; The surface alkalinity measured by the CO ₂ -TPD method is 0.0503 mmol [OH ^- ]/g; the isoelectric point IEP of the carrier surface is pH=9.2.

The catalyst Au/meso-Al ₂ O ₃ -c (HDP) was prepared according to the homogeneous deposition precipitation method (HDP) in Example 1. The specific surface of Au/meso-Al ₂ O ₃ -c (HDP) was determined by low-temperature N ₂ adsorption-desorption method to be 292m ² /g, the pore volume was 0.47cm ³ /g, and the average pore diameter was 4.5nm; (TEM) observed that the average size of the nano-Au particles on the surface of the carrier is 3.6nm, see Figure 3.

The catalyst Au/meso-Al ₂ O ₃ -c (HDP) was pressed into tablets and sieved, and the particles of 40-60 mesh were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. In each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 24.3%.

Example 8

Using the meso-Al ₂ O ₃ -c prepared in Example 7 as a carrier, the catalyst Au/meso-Al ₂ O ₃ -c (DP) was prepared according to the deposition precipitation method (DP) in Example 2. The specific surface of Au/meso-Al ₂ O ₃ -c (DP) measured by low temperature N ₂ adsorption-desorption method is 259m ² /g, the pore volume is 0.54cm ³ /g, and the average pore diameter is 4.0nm; the surface of the carrier is nanometer The average size of the Au particles is 4.2 nm.

The catalyst Au/meso-Al ₂ O ₃ -c (DP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. Each cigarette filter rod Containing 40 mg of catalyst, the composite filter rod is wound into cigarettes. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 22.1%.

Example 9

Using the meso-Al ₂ O ₃ -c prepared in Example 7 as a carrier, the catalyst Pt-Au/meso-Al ₂ O ₃ -c (HDP) catalyst was prepared according to the homogeneous deposition precipitation method (HDP) in Example 1 (Pt:Au atomic ratio=1:1). The catalyst Pt-Au/meso-Al ₂ O ₃ -c (HDP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. The rod contains 40 mg of catalyst, and the composite filter rod is wound into a cigarette. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 25.1%.

Example 10

Using the meso-Al ₂ O ₃ -c prepared in Example 7 as a carrier, prepare by homogeneous deposition-precipitation method (HDP), take a certain amount of HAuCl ₄ (concentration is 9.71mmol/L) and Cu(NO ₃ ) ₂ Mix the solution, impregnate the carrier meso-Al ₂ O ₃ -c in equal volume, and heat slowly to 70-80°C. At the same time, urea was added to adjust the pH of the solution to 7, and the temperature was maintained for 4 hours. Filter, wash with hot water (70-80°C) several times, detect no Cl ^- with AgNO ₃ (0.10mol/L), and dry at 70°C for 8-10h. Then calcined at 350°C for 1.0h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 1.0h to obtain the catalyst Au-Cu/meso-Al ₂ O ₃ -c(HDP).

The catalyst Au-Cu/meso-Al ₂ O ₃ -c (HDP) was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes. The stick contains 40 mg of catalyst. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 28.7%.

Example 11

The Au/meso-Al ₂ O ₃ -c catalyst prepared in Example 7 was pressed into tablets and sieved, and the 40-60 mesh particles were selected to be coated on the surface of the forming paper of the cigarette paper, and rolled into cigarettes, each cigarette containing Catalyst 20 mg. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 20.9%.

Example 12

Synthesis of carrier meso-Al ₂ O ₃ -d: 3.038g template agent P123 (EO ₂₀ PO ₇₀ EO ₂₀ ) and 0.030g LaCl ₃ were dissolved in 12.5ml sec-butanol to form solution 1; 1.0 g of chitosan was dissolved in 30 ml of CH ₃ COOH solution (5% V/V) to form solution 2. With stirring at room temperature, slowly add the mixture of water and sec-butanol (1.14ml H ₂ O/10ml sec-butanol) dropwise into the mixed solution of solution 1 and solution 2, continue stirring at 45°C for 48 hours, and filter. Dry and calcinate at 500°C for 6h in an air atmosphere to obtain the product, which is marked as meso-Al ₂ O ₃ -d. The specific surface of meso-Al ₂ O ₃ -d measured by low temperature N ₂ adsorption-desorption method is _290m ² /g, the pore volume is 0.76cm ³ /g, and the average pore diameter is 7.0nm; The basicity of the surface measured by CO ₂ -TPD method is 0.0467mmol [OH ^- ]/g; the isoelectric point IEP of the carrier surface is pH=8.9.

The catalyst Au/meso-Al ₂ O ₃ -d(HDP) was prepared according to the homogeneous deposition-precipitation method (HDP) in Example 1. The specific surface of Au/meso-Al ₂ O ₃ -a (HDP) was determined by low-temperature N ₂ adsorption-desorption method to be 236m ² /g, the pore volume was 0.54cm ³ /g, and the average pore diameter was 5.3nm; (TEM) observed that the average size of the nano-Au particles on the surface of the carrier was 4.9 nm (see Figure 4).

The catalyst Au/meso-Al ₂ O ₃ -d was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter rod for cigarettes, each cigarette filter rod contained 40 mg of the catalyst , and the composite filter rod is wound into a cigarette. Measure the CO content in the mainstream smoke of cigarettes by the method in embodiment example 1, compare with the cigarette without adding catalyst, the result shows, compare with contrast cigarette, the catalyst prepared by the present invention can make the CO content in the mainstream smoke decline 20%.

Example 13

Using the meso-Al ₂ O ₃ -b prepared in Example 4 as a carrier, prepare a mesoporous Al ₂ O ₃ -b carrier surface supported Au and Pt alloy catalyst according to the homogeneous deposition-precipitation method (HDP) in Example 1 , take a certain amount of HAuCl ₄ and H ₂ PtCl ₂ solutions (concentrations are 9.71mmol/L, Au:Pt=1:1 (atomic ratio)) and 1.0g carrier meso-Al ₂ O ₃ -b, mix well, Heat slowly to 70-80°C. At the same time, urea was added to adjust the pH of the solution to 7, and the temperature was maintained for 4 hours. Filter, wash with hot water (70-80°C) several times, detect no Cl ^- with AgNO ₃ (0.10mol/L), and dry at 70°C for 8-10h. Then calcined at 350°C for 1.0h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 1.0h to obtain the catalyst Au-Pt/meso-Al ₂ O ₃ -b(HDP). The specific surface of the catalyst is 293m ² /g, the pore volume is 0.47cm ³ /g, the average pore diameter is 4.5nm, and the average size of nano- _Au particles on the carrier surface is 3.8nm. The catalyst Au-Pt/meso-Al ₂ O ₃ -b was pressed into tablets and sieved, and the 40-60 mesh particles were selected and dispersed in the cellulose acetate tow to make a binary composite filter stick for cigarettes, each cigarette filter stick contained Catalyst 40mg, the composite filter stick is rolled into cigarette. Measure the CO content in cigarette mainstream smoke by the method in embodiment example 1, carry out contrast with the cigarette that does not add catalyst, the result shows, compared with contrast cigarette, the Au-Pt nanometer that the mesoporous alumina load of the present invention prepares The catalyst can reduce the CO content in mainstream smoke by 26%.

Claims (21)

1. A catalyst for reducing carbon monoxide content in cigarette smoke, characterized in that the catalyst contains a mesoporous alumina carrier and nano-metals; the basic position on the surface of the mesoporous alumina carrier is: 0.01～0.08mmol[OH ^- ]/g, the surface isoelectric point is pH=8～10; the nanometer metal is selected from Au, Pt or Pd. 2. A catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1, characterized in that the specific surface of the mesoporous alumina carrier is 100-400 m ² /g, and the pore diameter is 2.0-10 nm. 3. A catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1 or 2, said catalyst also contains one or more of rare metals or transition metals or their oxides. 4. A catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1 or 2, wherein the nano-metal particles account for 0.01 to 2.5% of the mass content of the catalyst, and the size of the nano-metal particles is 2 to 2.5%. 10nm. 5. The application method of a catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1, characterized in that, the catalyst is pressed into tablets, sieved, and 20-80 mesh particles are selected to be dispersed in the cellulose acetate silk of the cigarette filter rod In the bundle, a binary or ternary composite filter rod is made, and the composite filter rod is wound into a cigarette, and each cigarette filter rod contains 5-50 mg of catalyst. 6. The application method of a catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1, characterized in that, the catalyst is pressed into tablets, sieved, and 20-80 mesh particles are selected, and coated on cigarette forming paper and grooves Paper surface, rolled into cigarettes, each cigarette contains 5-50mg of catalyst. 7. prepare a kind of catalyst method for reducing carbon monoxide content in cigarette smoke described in claim 1, it is characterized in that, HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution and mesoporous alumina carrier are mixed uniformly, slowly heated to At 70-80°C, add urea at the same time to adjust the pH of the solution to 7, and keep at this temperature for 3.5-4.5h; filter, wash with hot water several times, detect no C1 ^- with AgNO ₃ , dry at 65-75°C for 8 -10h; then calcined at 330-370°C for 1.0h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h; the preparation of the mesoporous alumina carrier includes the following steps: using chitosan One or more of sugar, surfactant P123, and cetyltrimethylammonium bromide are used as a structure-directing agent, and aluminum nitrate or sec-butanol is used as an aluminum source. It is prepared by hydrolysis, filtration, separation, drying, and roasting have to. 8. The preparation method of a mesoporous alumina carrier according to claim 7, characterized in that, a rare earth metal compound is also doped. 9. The preparation method according to claim 7, characterized in that HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution with a concentration of 9.71 mmol/L is mixed evenly with 1.0 g of mesoporous alumina carrier. 10. The preparation method according to claim 7, characterized in that, washing with hot water at 70-80°C. 11. The preparation method according to claim 7, characterized in that a transition metal salt is also added to mix with the mesoporous alumina carrier. 12. A method for preparing a catalyst for reducing carbon monoxide content in cigarette smoke according to claim 1, characterized in that Na ₂ CO ₃ is used as a precipitant to adjust the HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution to pH=7 , under vigorous stirring, add the mesoporous alumina carrier, react for 3.5-4.5h, wash with hot water several times, detect no Cl ^- with AgNO ₃ , and dry at 65-75°C for 8-10h. Then calcined at 330-370°C for 0.5-1.5h, cooled to normal temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h; the preparation of the mesoporous alumina carrier includes the following steps: using chitosan , Surfactant P123, one or more of cetyltrimethylammonium bromide as a structure-directing agent, using aluminum nitrate or sec-butanol as an aluminum source, through hydrolysis, filtration separation, drying, and roasting . 13. The preparation method according to claim 12, characterized in that the mesoporous alumina support is also doped with a rare earth metal compound. 14. The preparation method according to claim 12, characterized in that HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution with a concentration of 9.71 mmol/L is mixed evenly with 1.0 g of mesoporous alumina carrier. 15. The preparation method according to claim 12, characterized in that, washing with hot water at 70-80°C. 16. The preparation method according to claim 12, characterized in that a transition metal salt is also added to mix with the mesoporous alumina carrier. 17. A method for preparing a catalyst for reducing carbon monoxide content in cigarette smoke, characterized in that HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution and a mesoporous alumina carrier are mixed uniformly, stirred at room temperature for 1-2 hours, Filter, wash with ammonia water several times, and then wash with water several times, detect no Cl ^- with AgNO ₃ , and dry at 65-75°C for 8-10h. Then calcined at 330-370°C for 0.5-1.5h, cooled to room temperature, and then reduced with hydrogen at 300-350°C for 0.5-1.5h; the preparation of mesoporous alumina carrier includes the following steps: using chitosan, surface active One or more of the agent P123 and cetyltrimethylammonium bromide are used as structure-directing agents, and aluminum nitrate or sec-butanol is used as the aluminum source, and it is obtained by hydrolysis, filtration separation, drying and roasting. 18. The method for preparing a mesoporous alumina carrier according to claim 17, characterized in that, a rare earth metal compound is also doped. 19. The preparation method according to claim 17, characterized in that HAuCl ₄ , H ₂ PtCl ₂ or PdCl ₂ solution with a concentration of 9.71 mmol/L is mixed evenly with 1.0 g of mesoporous alumina carrier. 20. The preparation method according to claim 17, characterized in that, washing with 20% V/V ammonia water three times. 21. The preparation method according to claim 17, characterized in that a transition metal salt is also added to mix with the mesoporous alumina carrier.

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