Dual-support catalysts for tobacco industry off-gas remediation, methods of making and use thereof

Abstract

The present invention relates to a dual-support catalyst for tobacco industry organic waste gas treatment, a preparation method and use thereof, the catalyst comprising (a) 0.5-5 wt% of a supported active component Pt / α-Fe2O3 (loading amount of Pt is 0.1-5 wt%), (b) 0.5-5 wt% of a catalytic aid MoO3, (c) 1-10 wt% of a molding aid SiO2, (d) 1-10 wt% of a molding aid Al2O3, and (e) 70-97 wt% of a composite oxide carrier Zr x Ti (1‑x) Co 1.5 O4 (x is 0.15-0.25). The dual-support catalyst of the present invention has excellent catalytic oxidation activity on volatile organic compounds (VOC) in tobacco industry organic waste gas, and has persistent catalytic oxidation activity due to the anti-sulfur and anti-chlorine poisoning performance. In addition, the catalyst of the present invention can be molded into a desired shape and has excellent compressive strength, meeting the deep purification needs of VOC in tobacco industry organic waste gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of waste gas treatment and catalysis, and particularly relates to a dual-loaded catalyst for waste gas treatment in the tobacco industry, and a preparation method and use thereof. BACKGROUND

[0002] In the cigarette manufacturing process of the tobacco industry, especially in the manufacturing and storage process from tobacco sheet to tobacco, different odors are generated in each process. The odor is mainly caused by volatile organic compounds (VOC) components in waste gas, including polycyclic aromatic hydrocarbons, lipids, alcohols, pyrazines, aldehydes and ketones, etc. In the cigarette processing process, part of the odor gas escapes into the surrounding environment by diffusion and further diffuses in the atmospheric environment, causing unorganized emission. The waste gas generated by the tobacco industry has the characteristics of large emission amount, complex composition and great harm, and is the focus of current air pollution control.

[0003] At present, the methods for treating odor of waste gas in the tobacco industry at home and abroad mainly include chemical absorption method, biological method, adsorption method, low-temperature plasma method, catalytic oxidation method, etc. These methods have differences in principle and equipment structure, and the treatment effects are also different. The chemical absorption method is to treat harmful gas by using chemical reagents, which is suitable for waste gas with large gas volume and low concentration, but the investment and operation cost is high, and secondary pollution is easy to occur; the biological method uses the metabolic action of microorganisms to oxidize and decompose organic gas in waste gas, so as to achieve the effect of removing odor. This method has low investment, but the treatment speed is slow, and the microorganisms are sensitive to environmental changes, so the treatment effect is easily affected by the environment.

[0004] The catalytic oxidation method is to catalytically oxidize VOC molecules in waste gas into harmless carbon dioxide and water under the action of a catalyst, which has high purification efficiency and no secondary pollution, and is the most effective method for treating odor of waste gas. The core of catalytic oxidation technology is the catalyst. The current commercial catalyst for VOC catalytic oxidation is mainly in the form of honeycomb, and the typical active component is noble metal Pd, Pt, etc. However, due to the complex composition of tobacco organic waste gas, especially the presence of sulfur, chlorine and other elements, such catalysts are easy to be poisoned and deactivated, resulting in shortening of the service life of the catalyst; and other non-metallic catalysts have low activity and poor purification effect.

[0005] CN110404543A discloses a VOC catalyst characterized by ordered arrangement of composite metal oxide and ferroferric oxide and a preparation method thereof, wherein electroplating sludge is used as a synthetic material, the temperature and pressure are changed in an acidic environment, and the metal elements in the electroplating sludge are dissolved into the solution and fully reacted under the atmosphere of alternating air and nitrogen to form a stable nanomaterial catalyst of ordered arrangement of composite metal oxide and ferroferric oxide. The catalyst can achieve a conversion rate of toluene of more than 98% at about 330°C. However, the catalyst not only needs to use composite metal oxide of a specific source and a specific size and ferroferric oxide of a specific size, but also has a high activation temperature and low catalyst activity. In addition, the document does not mention the catalyst's ability to resist sulfur and chlorine poisoning and any content for tobacco waste gas treatment.

[0006] Therefore, there is a need in the art to develop a new catalyst suitable for tobacco industry waste gas treatment. SUMMARY

[0007] The purpose of the present application is to solve one or more problems of the existing VOC treatment catalyst for organic waste gas in the tobacco industry, such as low activity, easy poisoning and deactivation, high activation temperature, etc. In order to seek a new catalyst suitable for tobacco industry waste gas treatment, which has high catalytic oxidation activity, resistance to poisoning, long-term effectiveness and lower activation temperature, the present inventors have found through in-depth and extensive research that: (a) by using a supported composite Pt / α-Fe2O3 as the catalyst active component supported on a composite oxide carrier Zr x Ti (1-x) Co 1.5On O4, the obtained double-loaded catalyst can basically maintain the spinel-like structure of the composite oxide carrier, thus having a larger specific surface area to enhance the adsorption of VOC molecules in tobacco industry waste gas, while increasing the contact area of the reaction to improve the catalytic oxidation activity; (b) the composite oxide carrier used has excellent anti-poisoning performance for elements such as sulfur (S) and chlorine (Cl) in tobacco industry waste gas, thereby improving the anti-S and Cl poisoning performance of the obtained catalyst, so that the catalytic oxidation activity can be maintained for a longer time, i.e. has a longer catalytic life; (c) compared with the single-loaded metal Pt, the active component Pt / α-Fe2O3 used in the present application can further enhance the dispersion of the active metal Pt on the surface of the composite oxide carrier (preferably having a quadrangular prism tubular shape), so that a smaller amount of metal Pt can be used while maintaining equivalent or higher catalytic oxidation activity; at the same time, the catalyst of the present application has a lower activation temperature (for example, 220℃-250℃); (d) by using a specific amount of molding aid, the catalyst can be molded into a specific shape (especially spherical particles) with excellent compressive strength through a simple molding process, thus being able to meet the deep purification of VOC in tobacco industry organic waste gas; (e) by adding the catalytic aid MoO3, not only can the activity of the catalyst be further improved, but also the catalyst can have higher heat resistance.

[0008] Based on the above findings, in one aspect, the present application provides a double-loaded catalyst for tobacco industry organic waste gas treatment, the double-loaded catalyst comprising: (a) 0.5-5 wt% of a loaded active component Pt / α-Fe2O3; (b) 0.5-5 wt% of a catalytic aid MoO3; (c) 1-10 wt% of a molding aid SiO2; (d) 1-10 wt% of a molding aid Al2O3; and (e) 70-97 wt% of a composite oxide carrier Zr x Ti (1-x) Co 1.5 O4, wherein x is 0.15-0.25, wherein the wt% of components (a)-(e) are all based on the total weight of the double-loaded catalyst, and wherein the loading of metal Pt is 0.1-5 wt% based on the total weight of the loaded active component Pt / α-Fe2O3.

[0009] In a preferred embodiment, the sum of the wt% of components (a)-(e) is 100 wt% of the double-loaded catalyst.

[0010] In a preferred embodiment, the composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 has a spinel-like structure.

[0011] In a preferred embodiment, the composite oxide support Zr x Ti (1-x) Co 1.5 O4 is a tetrapod tubular composite oxide support having a spinel-like structure.

[0012] In a preferred embodiment, the tetrapod tubular composite oxide support has a length of 400 nm to 500 nm and an outer diameter of 50 nm to 120 nm.

[0013] In a preferred embodiment, the dual-support catalyst has a spherical, spheroid, cylindrical or pyramid shape.

[0014] In a preferred embodiment, the dual-support catalyst has a spherical shape, for example a sphere having a diameter of 6.2 mm to 6.8 mm.

[0015] In a preferred embodiment, the dual-support catalyst has a spherical shape, for example a sphere having a diameter of 6.2 mm to 6.8 mm.

[0016] In another aspect, the present application provides a method for preparing the above-mentioned dual-support catalyst, the method comprising:

[0017] (1) after mixing a solution containing a titanium precursor with a solution containing a zirconium precursor and a cobalt precursor in stoichiometric amounts, adjusting to alkalinity with an alkaline reagent to produce a precipitate, then drying the precipitate obtained by filtration, followed by hydrothermal treatment, and finally washing the resulting crystals and calcining in an air atmosphere, thereby providing a composite oxide support Zr x Ti (1-x) Co 1.5 O4;

[0018] (2) providing a supported active component Pt / α-Fe2O3 by commercial purchase or by a conventional impregnation method;

[0019] (3) providing a catalytic aid MoO3 by commercial purchase or by heat-treating a molybdenum precursor compound;

[0020] (4) mixing the above-mentioned composite oxide support, supported active component and catalytic aid in the desired amounts and heat-treating under an inert atmosphere to obtain a catalyst precursor; and

[0021] (5) mixing the resulting catalyst precursor with a molding aid SiO2 and Al2O3 in the desired amounts, then adding a binder solution and molding into the desired shape in a molding machine, followed by drying and calcining under a nitrogen atmosphere at 100 to 450°C to obtain the desired dual-support catalyst.

[0022] In a preferred embodiment, in step (5), the dual-support catalyst is shaped into a spherical shape by a rotary table shaper.

[0023] In a preferred embodiment, in step (5), the calcination is a stepwise heat treatment in the following manner: after being kept at 100-120°C for 1-5h, the temperature is raised to 150-200°C for 1-5h, then raised to 300-400°C for 1-5h, and finally raised to 420-450°C for 1-5h.

[0024] In a preferred embodiment, the titanium precursor comprises tetrabutyl titanate or tetraethyl titanate; the zirconium precursor comprises zirconium oxychloride, zirconium n-propylate or zirconium acetate; the cobalt precursor comprises cobalt acetate or cobalt chloride; and the molybdenum precursor comprises ammonium heptamolybdate or molybdenum acetate.

[0025] In another aspect, the present application provides a use of the above-mentioned dual-support catalyst for treating organic waste gas in the tobacco industry, wherein volatile organic compounds in the organic waste gas in the tobacco industry are catalytically oxidized into carbon dioxide and water by using the dual-support catalyst.

[0026] In a preferred embodiment, the volatile organic compounds comprise ethyl acetate, acetaldehyde and benzaldehyde.

[0027] The present application obtains a dual-support catalyst with excellent catalytic oxidation activity for volatile organic compounds (VOC) in organic waste gas emitted by the tobacco industry, and the catalyst also has excellent resistance to sulfur and / or chlorine poisoning, longer or more persistent catalytic life, lower activation temperature, lower manufacturing cost and energy consumption, etc., by loading specific supported active components and catalytic aids onto a composite oxide carrier with specific composition, and shaping the catalyst into a desired shape via a specific shaping agent.

[0028] In addition, the preparation process of the dual-support catalyst of the present application is simple, and the shaped catalyst particles obtained have excellent compressive strength, meeting the deep purification requirements of VOC in organic waste gas in the tobacco industry.

[0029] In addition, by adding the catalytic aid MoO3, the present application can provide more B acid sites and L acid sites for the catalyst, thereby not only improving the activity of the catalyst, but also enabling the catalyst to have higher thermal stability or heat resistance (short-term maximum tolerance temperature up to 850°C). DETAILED DESCRIPTION

[0030] The double-loaded catalyst for treating tobacco industry organic waste gas provided by the present application comprises the following components (based on the total weight of the catalyst): (a) 0.5-5 wt%, preferably 0.5-2 wt% of a supported active component Pt / α-Fe2O3; (b) 0.5-5 wt%, preferably 2-4 wt% of a catalytic aid MoO3; (c) 1-10 wt%, preferably 4-6 wt% of a molding aid SiO2; (d) 1-10 wt%, preferably 3-6 wt% of a molding aid Al2O3; and (e) 70-97 wt%, preferably 80-95 wt% of a composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 (x is 0.15-0.25), and in the supported active component Pt / α-Fe2O3, the loading of the metal Pt is 0.1-5 wt%, preferably 0.5-2 wt%. Preferably, in the catalyst of the present application, the sum of the wt% of components (a)-(e) is 100 wt%, i.e. the double-loaded catalyst of the present application is composed of the above-mentioned components (a)-(e).

[0031] In the present application, preferably, the composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 has a spinel-like structure, more preferably, the composite oxide carrier is a tetrapod tube-shaped composite oxide carrier with a spinel-like structure. Further preferably, the length of the tetrapod tube-shaped composite oxide carrier can be, for example, 400-500 nm, and the outer diameter can be, for example, 50-120 nm.

[0032] The present inventors have found that, by using the above-mentioned composition by weight, by adopting the supported composite Pt / α-Fe2O3 as the catalyst active component and loading it together with the catalytic aid MoO3 on the composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 (x is 0.15-0.25), the obtained double-loaded catalyst can basically maintain the spinel-like structure of the composite oxide carrier, thus having a larger specific surface area to enhance the adsorption of VOC molecules in the tobacco industry waste gas, and can increase the contact area of the reaction, resulting in the improvement of the catalytic oxidation activity. In addition, the present inventors have confirmed in the research that, in sharp contrast, if the metal Pt is directly loaded together with the aid MoO3 on the mixture including α-Fe2O3 and the composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 (x is 0.15-0.25) as the carrier according to the conventional method, the metal Pt will be dispersed in α-Fe2O3, the composite oxide carrier Zrx Ti (1-x) Co 1.5 O4 and MoO3 surface, namely single-loaded Pt / α-Fe2O3-Zr x Ti (1-x) Co 1.5 O4-MoO3 catalyst, so that the two catalyst carriers are completely different in structural composition, and α-Fe2O3-Zr x Ti (1-x) Co 1.5 O4-MoO3 mixture also cannot maintain a spinel-like structure, thereby significantly reducing the catalytic oxidation activity.

[0033] The present inventors have also found that the use of the supported composite Pt / α-Fe2O3 as the catalyst active component can further enhance the dispersion of the active metal Pt on the surface of the composite oxide carrier (preferably having a quadrangular tubular shape), so that, compared with conventional catalysts prepared by directly loading the active metal component on the carrier, such as Pt / γ-Al2O3, the amount of active metal Pt in the catalyst of the present application can be less while maintaining the same or higher catalytic oxidation activity, and the catalyst of the present application has a lower activation temperature, thereby significantly reducing energy consumption and cost in industrial applications. In addition, since the composite oxide carrier used in the present application has excellent resistance to poisoning by elements such as sulfur (S) and chlorine (Cl) in tobacco industry waste gas, the obtained catalyst also has improved resistance to S and Cl poisoning, so that it can maintain catalytic oxidation activity for a longer period of time, thereby having a longer catalytic life.

[0034] In the present application, in order to be suitable for industrial applications for VOC treatment in tobacco industry organic waste gas, the catalyst of the present application needs to be shaped using the above-mentioned weight content of the shaping aid SiO2 and Al2O3. Preferably, the catalyst of the present application can be shaped into a spherical, ellipsoidal, cylindrical or pyramidal shape. More preferably, the double-loaded catalyst of the present application is in the shape of a sphere, for example, it can be a spherical particle with a diameter of 6.2 mm to 6.8 mm. Further preferably, the compressive strength (i.e. the maximum force that can be withstood before each spherical particle breaks) of the obtained spherical particle-shaped catalyst can be 75 to 100 N / particle, which is significantly higher than the compressive strength (30 to 35 N / particle) of conventional spherical catalysts, so that the catalyst has a low attrition rate in actual flue gas and is not easily broken, so that the catalyst has a longer mechanical life.

[0035] The double-loaded catalyst of the present application can be prepared by the following method:

[0036] (1) Preparation of the composite oxide carrier (sometimes also referred to as "titanium-zirconium-cobalt oxide template"):

[0037] Zr x Ti (1-x) Co 1.5 O4(x is 0.15 to 0.25) in stoichiometric amounts, after mixing the solution containing the titanium precursor with the solutions containing the zirconium precursor and the cobalt precursor, adjusting to alkalinity with an alkaline reagent to produce a precipitate, then drying the precipitate obtained by filtration, followed by hydrothermal treatment, and finally washing the crystals obtained and calcining in an air atmosphere, thereby providing the desired composite oxide support. In this preparation step, in order to better dissolve and form the solution of the titanium precursor, the titanium precursor can be dissolved together with an organic acid reagent.

[0038] More specifically, for example, first the titanium precursor such as tetrabutyl titanate is dissolved in a solvent such as formamide together with an organic acid reagent such as isophthalic acid, and the zirconium precursor such as zirconium oxychloride and the cobalt precursor such as cobalt acetate are dissolved in a solvent such as water, after sufficient dissolution with stirring, the two solutions obtained above are mixed, and the pH is adjusted to alkalinity such as pH of about 10 with an alkaline reagent such as aqueous ammonia, thereby causing precipitation and aging for 8 to 10 h. The precipitate obtained by filtration, for example, reduced pressure filtration, is dried (for example, oven dried at 110°C for 4 h), after which it is transferred to a hydrothermal autoclave for hydrothermal treatment (for example, at 110 to 130°C for 60 to 72 h). After the end of the hydrothermal treatment, the crystals obtained by filtration or centrifugation are washed several times with a solvent such as ethanol, and finally calcined (for example, at about 650°C for 4 to 6 h in an air atmosphere), thereby obtaining the desired composite oxide support.

[0039] (2) Provision of the active component:

[0040] The supported active component Pt / α-Fe2O3 of the present application can be obtained commercially, but is preferably provided by a conventional impregnation method. For example, using a conventional impregnation method, a solution of chloroplatinic acid can be added and impregnated in α-Fe2O3 powder, and the resulting material after uniform impregnation can be calcined in a hydrogen atmosphere at 400 to 420°C for 2 to 4 h.

[0041] (3) Provision of the catalytic aid MoO3:

[0042] The catalytic aid MoO3 of the present application can be obtained commercially, or can be provided by heat-treating a molybdenum precursor compound such as ammonium heptamolybdate in the presence of an organic acid aid such as citric acid under an inert atmosphere such as nitrogen atmosphere (for example, at 180°C for 2 h). In addition, the above-mentioned molybdenum precursor compound can also be directly heat-treated with the organic acid aid together with the support and the active component in the next step, thereby providing the desired catalytic aid. In other words, this step (3) can exist alone, or can be combined with the next step (4) as one step.

[0043] (4) Preparation of the catalyst precursor:

[0044] The above obtained composite oxide support, supported active component and catalytic adjuvant are mixed in the desired weight ratio and heat-treated under an inert atmosphere such as nitrogen atmosphere, for example at a temperature of 60 to 200°C (e.g. at a temperature rising rate of 1 to 2°C / min up to 180°C, and constant temperature for 2h), and finally optionally naturally cooled to room temperature; and

[0045] (5) Preparation of the catalyst:

[0046] The obtained catalyst precursor (preferably previously subjected to a pulverization treatment, for example to 400 mesh or more) is uniformly mixed with a molding adjuvant SiO2 (for example, a common white carbon) and Al2O3 (for example, a common pseudo-boehmite) in the desired weight ratio. Then, a binder solution (for example, a common aqueous sodium carboxymethyl cellulose solution is sprayed via a spray gun) is added and molded into the desired shape (for example, spherical embryos) in a molding machine (for example, a rotary table molding machine), and finally dried and calcined at 100 to 450°C under a nitrogen atmosphere to obtain the desired double-supported catalyst.

[0047] In the above step (5), preferably, the inclination angle of the rotary table of the rotary table molding machine can be set to, for example, 40 to 45°, and the rotary table rotation speed can be set to, for example, 20 to 25 r / min.

[0048] In the above step (5), preferably, the drying temperature of the spherical embryos can be, for example, 30 to 50°C, and the drying time can be, for example, 34 to 72h, and typically, the drying can be completed when the water content in the spherical embryos is 4% or less.

[0049] In the above step (5), preferably, the calcination is a stepwise heat treatment performed as follows: after being kept at 100 to 120°C for 1 to 5h, the temperature is raised to 150 to 200°C for 1 to 5h, then to 300 to 400°C for 1 to 5h, and finally to 400 to 420°C for 1 to 5h. More specifically, for example, the heat treatment can be completed in four stages: the first stage is a temperature rise to 105°C in 1.5h, keeping at 105°C for 3h, the second stage is a temperature rise from 105°C to 180°C in 3h, keeping at 180°C for 2h, the third stage is a temperature rise from 180°C to 350°C in 2h, keeping at 350°C for 3h, and the fourth stage is a temperature rise from 350°C to 420°C in 4h, keeping at 420°C for 3h, and then naturally cooled to room temperature.

[0050] In the present application, the titanium precursor that can be used includes tetrabutyl titanate or tetraethyl titanate; the zirconium precursor includes zirconium oxychloride or zirconium n-propylate or zirconium acetate; the cobalt precursor includes cobalt acetate or cobalt chloride; and the molybdenum precursor includes ammonium heptamolybdate or molybdenum acetate.

[0051] The dual-support catalyst of the present application can be used for the abatement of organic waste gases, in particular for the abatement of organic waste gases in the tobacco industry, wherein the volatile organic compounds (VOCs) in the organic waste gases of the tobacco industry are catalytically oxidized to carbon dioxide and water using the catalyst of the present application. Typically, such catalytic oxidation is accomplished by flowing the organic waste gases through a flow bed or a pipe containing the catalyst of the present application at a suitable temperature in the presence of oxygen at a suitable space velocity, as known to those skilled in the art. Although a plurality of components are included in the organic waste gases, typically, representative examples thereof can be mentioned such as ethyl acetate, acetaldehyde and benzaldehyde.

[0052] The present application will be described in detail below in the form of non-limiting examples. These examples are merely non-limiting examples for illustrating the specific implementation and realization process of the present application, and are not intended to limit the scope of the present application.

[0053] In the following examples, the equipment, reagents and raw materials used are commercially available and can be used directly after purchase without further treatment, unless otherwise specified. Also, the reaction processes and treatment methods involved are known in the art or are routine operations, unless otherwise specified.

[0054] Example 1

[0055] In a beaker, 128 g of isophthalic acid (Shanghai Aldrich Biochemical Technology Co., Ltd., hereinafter referred to as Aldrich) and 97 g of tetrabutyl titanate (Aldrich) were dissolved in formamide, fully dissolved under mechanical stirring, and in a beaker, 241.5 g of zirconium oxychloride (Aldrich) and 265.5 g of cobalt acetate (Aldrich) were dissolved in 2.15 L of water, fully dissolved under mechanical stirring. Then, in a beaker, the two solutions were mixed, and the pH of the mixed solution was adjusted to about 10 by dropwise addition of ammonia water, and after the appearance of the precipitate, it was aged for 10 h. The precipitate was obtained by reduced pressure filtration, and was dried in an oven at 110°C for 4 h, then transferred to an autoclave, and incubated at 120°C for 72 h. After the hydrothermal treatment was completed, the crystal material was obtained by filtration, washed with ethanol three times, and then calcined in a muffle furnace under an air atmosphere at 650°C for 4 h, thereby obtaining a composite oxide support, and its composition was Zr 0.25 Ti 0.75 Co 1.5 O4.

[0056] In a beaker, 5 ml of a solution containing 0.41 g of chloroplatinic acid (Aldrich) was added to 19.3 g of a-Fe2O3 powder (Aldrich), and after uniform mechanical stirring, the mud was calcined in a muffle furnace at 420°C for 3 h, to obtain an active component 1% Pt / a-Fe2O3 with a Pt content of 1% by weight (based on the total weight of the obtained supported Pt / a-Fe2O3).

[0057] In a small beaker, 5.6 g of citric acid (Aldrich) and 2.8 g of ammonium heptamolybdate (Aldrich) were mixed homogeneously with 100 g of the composite oxide support obtained above, 2.3 g of the active component Pt / α-Fe2O3obtained above. Then, after raising the temperature to 180°C at a rate of 2°C / min under a nitrogen atmosphere and maintaining the temperature for 2 h, the temperature was then lowered to room temperature, thereby obtaining a catalyst precursor.

[0058] After the catalyst precursor obtained above was pulverized to 400 mesh or more using a pulverizer, it was mixed homogeneously with 3.45 g of pseudoboehmite (Aldrich) and 6.9 g of white carbon (Aldrich) in a small beaker under magnetic stirring. Then, the resulting mixture was put into the feeder of a rotary table molding machine (Model: XSS-ZDCX), and a 0.5% aqueous solution of sodium carboxymethyl cellulose was sprayed from a spray gun to produce spherical bodies. After that, the resulting spherical bodies were dried in a drying room at 35°C for 40 h. Finally, the dried spherical bodies were calcined in a muffle furnace according to the following stepwise program: the first stage was to raise the temperature to 105°C in 1.5 h and maintain the temperature for 3 h; the second stage was to raise the temperature from 105°C to 180°C in 3 h and maintain the temperature for 2 h; the third stage was to raise the temperature from 180°C to 350°C in 2 h and maintain the temperature for 3 h; the fourth stage was to raise the temperature from 350°C to 420°C in 4 h and maintain the temperature for 3 h; and finally, the temperature was naturally lowered to room temperature, thereby obtaining the final catalyst product.

[0059] The prepared dual-support catalyst had the following composition (based on the total weight of the catalyst): 1% Pt / α-Fe2O3content of 2 wt%, MoO3content of 2 wt%, Zr 0.25 Ti 0.75 Co 1.5 O4content of 87 wt%, SiO2content of 6 wt%, and Al2O3content of 3 wt%.

[0060] Example 2

[0061] A dual-support catalyst of the present application was prepared in the same manner as described in Example 1, except that the contents of the components were changed, and had the following composition (based on the total weight of the catalyst): 1% Pt / α-Fe2O3content of 0.5 wt%, MoO3content of 4 wt%, Zr 0.25 Ti 0.75 Co 1.5 O4content of 86.5 wt%, SiO2content of 5 wt%, and Al2O3content of 4 wt%.

[0062] Example 3

[0063] A dual-support catalyst of the present application was prepared in the same procedure as described in Example 1 with the exception of varying the content of each component. The composition of the catalyst was (based on the total weight of the catalyst): 1% Pt / α-Fe2O3 content of 1 wt%, MoO3 content of 3 wt%, Zr 0.4 Ti 0.6 Co 1.5 O4 content of 86.5 wt%, SiO2 content of 4.5 wt%, Al2O3 content of 5 wt%.

[0064] Example 4

[0065] A dual-support catalyst of the present application was prepared in the same procedure as described in Example 1 with the exception of varying the content of each component. The composition of the catalyst was (based on the total weight of the catalyst): 1% Pt / α-Fe2O3 content of 1.5 wt%, MoO3 content of 2.5 wt%, Zr 0.4 Ti 0.6 Co 1.5 O4 content of 86.5 wt%, SiO2 content of 4.5 wt%, Al2O3 content of 5 wt%.

[0066] Comparative Example 1

[0067] A commercially available commercial honeycomb VOC catalytic oxidation catalyst (catalyst model number SX-HC-400, main active component Pt) was selected as Comparative Example 1.

[0068] Comparative Example 2

[0069] In a beaker, 2.1 g of α-Fe2O3 powder (Aldrich), 5.6 g of citric acid (Aldrich) and 2.8 g of ammonium heptamolybdate (Aldrich) were uniformly mechanically stirred with 100 g of the composite oxide support Zr 0.25 Ti 0.75 Co 1.5 O4, and then 100 mL of a solution containing 48 mg of chloroplatinic acid (Aldrich) was added to the mixed powder and stirred for 30 min. Finally, the obtained mud was calcined in a muffle furnace at 420°C for 3 h to obtain a catalyst precursor. The final product was prepared according to the procedure described in Example 1.

[0070] A single-support catalyst was obtained by the above preparation process, and the composition of the catalyst was (based on the total weight of the catalyst): Pt content of 0.02 wt%, α-Fe2O3 content of 2 wt%, MoO3 content of 2 wt%, Zr 0.25 Ti 0.75 Co 1.5 O4 content of 87 wt%, SiO2 content of 6 wt%, Al2O3 content of 2.98 wt%.

[0071] Application Example: VOC in tobacco industry organic waste gas

[0072] The double-loaded catalysts obtained in Examples 1-4 above and the comparative catalyst obtained in Comparative Examples 1-2 were used to simulate VOC in tobacco industry organic waste gas with ethyl acetate, acetaldehyde and benzaldehyde as models, wherein the concentration of ethyl acetate was 1000 ppm, the concentration of acetaldehyde was 500 ppm, the concentration of benzaldehyde was 500 ppm, the H2O content was 5% by volume, and in order to test the sulfur and chlorine resistance of the catalyst, the HCl concentration in the simulated gas was 100 ppm and the H2S concentration was 100 ppm. The reaction conditions for catalytic oxidation: temperature was 260°C, space velocity was 20000 h -1 , O2 content was 4% by volume.

[0073] A fixed bed reactor was used to test the activity and durability of the catalyst. Among them, ethyl acetate, acetaldehyde, benzaldehyde, HCl were prepared into an aqueous solution according to the above ratio, and then atomized and sprayed into the flue through a peristaltic pump (BT100-2J). O2, N2 and H2S were prepared by steel cylinder gas, the gas flow was controlled by a gas mass flow meter, and the concentrations of ethyl acetate, acetaldehyde and benzaldehyde at the inlet and outlet of the flue gas were detected by gas chromatography, and finally the conversion rates of ethyl acetate, acetaldehyde and benzaldehyde were calculated.

[0074] Table 1: Catalytic oxidation of ethyl acetate

[0075]

[0076] 168h (i.e. 7 days) is the acceptance time of the conventional tobacco industry waste gas treatment project.

[0077] Table 2: Catalytic oxidation of acetaldehyde

[0078]

[0079] Table 3: Catalytic oxidation of benzaldehyde

[0080]

[0081] The results of Tables 1-3 show that in the organic waste gas containing HCl and H2S, compared with the comparative catalysts of Comparative Examples 1 and 2, the double-loaded catalysts of the present application not only have significantly better catalytic oxidation activity or efficiency on ethyl acetate, acetaldehyde and benzaldehyde in the organic waste gas, but also have better sulfur and chlorine resistance (basically not affected by the S and / or Cl containing gas in the organic waste gas), and therefore have longer durability or catalytic life.

[0082] It should be understood that the above-mentioned embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and is not an exhaustive embodiment of the specific implementation, and cannot limit the protection scope of the present application. Any modification or equivalent replacement according to the technical scheme of the present application without departing from the purpose and scope of the technical scheme of the present application should be covered in the scope of the claims of the present application.

Claims

1. A dual-supported catalyst for treating organic waste gas in the tobacco industry, the dual-supported catalyst comprising: (a) 0.5~5% by weight of the supported active component Pt / α-Fe2O3; (b) 0.5-5% by weight of the catalyst promoter MoO3; (c) 1-10% by weight of molding aid SiO2; (d) 1-10% by weight of molding aid Al2O3; and (e) 70-97% by weight of composite oxide support Zr x Ti (1-x) Co 1.5 O4, where x is 0.15~0.25, Wherein, the weight percentages of components (a) to (e) are based on the total weight of the dual-supported catalyst. Furthermore, based on the total weight of the supported active component Pt / α-Fe2O3, the loading of metallic Pt is 0.1~5% by weight.

2. The dual-supported catalyst according to claim 1, characterized in that, The dual-supported catalyst having a total weight percentage of components (a) to (e) of 100% by weight.

3. The dual-supported catalyst according to claim 1, characterized in that, The composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 has a spinel-like structure.

4. The dual-supported catalyst according to claim 3, characterized in that, The composite oxide carrier Zr x Ti (1-x) Co 1.5 O4 is a tetragonal prism-shaped composite oxide carrier with a spinel-like structure.

5. The dual-supported catalyst according to claim 4, characterized in that, The length of the quadrangular prism tubular composite oxide carrier is 400nm~500nm and the outer diameter is 50nm~120nm.

6. The dual-supported catalyst according to claim 1, characterized in that, The dual-supported catalyst has a spherical, ellipsoidal, cylindrical, or pyramidal shape.

7. The dual-supported catalyst according to claim 6, characterized in that, The dual-supported catalyst has a spherical shape with a diameter of 6.2 mm to 6.8 mm.

8. The dual-supported catalyst according to claim 7, characterized in that, The compressive strength of the spherical particles of the dual-supported catalyst is 75~100 N / particle.

9. A method for preparing the dual-supported catalyst according to claim 1, the method comprising: (1) After mixing the solution containing titanium precursor with the solutions containing zirconium precursor and cobalt precursor according to stoichiometry, the solution is adjusted to alkalinity with an alkaline reagent to produce a precipitate. The precipitate is then dried by filtration, followed by hydrothermal treatment. Finally, the resulting crystal is washed and calcined in air, thereby providing a composite oxide support Zr. x Ti (1-x) Co 1.5 O4; (2) The supported active component Pt / α-Fe2O3 is provided by commercial purchase or by conventional impregnation method; (3) Provide the catalyst MoO3 by commercial purchase or by heat treatment of the molybdenum precursor compound; (4) Mix the above-obtained composite oxide support, supported active component and catalyst promoter in the required amount and heat treat under an inert atmosphere to obtain catalyst precursor; and (5) Mix the obtained catalyst precursor with molding aids SiO2 and Al2O3 in the required amount, then add binder solution and mold it into the required shape in a molding machine. After drying and calcining at 100~450℃ in a nitrogen atmosphere, the desired dual-supported catalyst is obtained.

10. The method according to claim 9, characterized in that, In step (5), the dual-loaded catalyst is shaped into a spherical shape using a rotary forming machine.

11. The method according to claim 9, characterized in that, In step (5), the calcination is carried out in a segmented heat treatment as follows: after holding at 100~120℃ for 1~5 h, the temperature is raised to 150~200℃ and held for 1~5 h, then the temperature is raised to 300~400℃ and held for 1~5 h, and finally the temperature is raised to 420~450℃ and held for 1~5 h.

12. The method according to claim 9, characterized in that, The titanium precursor includes tetrabutyl titanate or tetraethyl titanate; the zirconium precursor includes zirconium oxychloride, zirconium n-propoxide or zirconium acetate; the cobalt precursor includes cobalt acetate or cobalt chloride; and the molybdenum precursor includes ammonium heptamolybdate or molybdenum acetate.

13. Use of the dual-supported catalyst according to any one of claims 1-8 for the treatment of organic waste gas in the tobacco industry, wherein the dual-supported catalyst is used to catalytically oxidize the volatile organic compounds in the organic waste gas from the tobacco industry into carbon dioxide and water.

14. The use according to claim 13, characterized in that, The volatile organic compounds include ethyl acetate, acetaldehyde, and benzaldehyde.

Images