Monolithic catalysts, methods for their preparation and use, and methods for the simultaneous purification of carbon monoxide and volatile organic compounds

Abstract

The present application relates to the technical field of atmospheric pollution control, and discloses a monolithic catalyst, a preparation method and application thereof, and a method for synergistically purifying carbon monoxide and volatile organic compounds. The monolithic catalyst comprises a porous substrate, manganese oxide supported on the porous substrate, and a protective agent selected from at least one of an acidic substance, an alkaline substance, and a metal oxide; wherein the average valence of manganese in the monolithic catalyst is 3.6-4. The monolithic catalyst has excellent oxidation capacity and is applied to the synergistic purification of carbon monoxide and volatile organic compounds, and has the advantages of good carbon monoxide and volatile organic compound removal effect.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, specifically to an integral catalyst, its preparation method and application, and a method for synergistically purifying carbon monoxide and volatile organic compounds. Background Technology

[0002] Volatile organic compounds (VOCs) are a class of volatile organic compounds with boiling points between 50-260℃. They are highly toxic and cause severe pollution. Many VOCs can cause illness in humans and even cancer; under sunlight, VOCs generate photochemical smog, and some halogenated hydrocarbons can lead to ozone layer depletion. Given the catastrophic harm that VOC pollution brings to the Earth's environment and human health, seeking effective treatment technologies has become the only way to solve VOC pollution problems. For industries such as steel sintering and waste incineration, as well as vehicle exhaust, the emitted gases contain a large number of pollutants such as particulate matter, SO2, and NO. x And acidic gases such as VOCs. For example, in the steel industry, in 2012, the Ministry of Environmental Protection issued the "Emission Standard of Air Pollutants for Iron and Steel Sintering and Pelletizing Industry" (GB28662-2012), which stipulates that the main pollutants produced by sintering equipment must meet the particulate matter standard of 50 mg / m³. 3 SO2 200mg / m 3 NO x 300mg / m 3 CO 5000mg / m³ 3 The limiting standards. Among them, CO is a reducing gas widely present in steel sintering, waste incineration flue gas, and automobile exhaust. NO in the atmosphere... x The interaction between sulfur oxides and VOCs causes primary particulate matter in the atmosphere to transform into secondary particulate pollutants, leading to smog. Therefore, controlling VOCs and CO emissions is of great significance for improving air quality in my country.

[0003] CN107519871A discloses a method for preparing AuAg@SiO2 nanocatalysts for catalytic oxidation of CO. The specific steps of the method are as follows: (1) Mix 10mM HAuCl4 solution and 10mM AgNO3 solution, add 0.1g / ml surfactant solution, stir at room temperature for 20-30min, add 0.1M sodium borohydride solution, stir for 3h to obtain AuAg alloy sol; the 10mM The volume ratio of HAuCl4 solution, 10mM MgNO3 solution, 0.1g / ml surfactant and 0.1M sodium borohydride is 1:0.25-4:0.5-10:1-10; (2) Take the AuAg alloy sol obtained in step (1) and add it to the solvent. Add tetraethyl orthosilicate (TEOS) while stirring. After mixing evenly, add 28wt% ammonia water dropwise and continue stirring for 2-5 hours. The solvent is a mixture of water and alcohol, and the volume ratio of water to alcohol is 1:1.25-5. The volume ratio of AuAg alloy sol, tetraethyl orthosilicate and 28wt% ammonia water is 1:0.05-0.3:0.1-1. The above scheme has the problem that the preparation method of the catalyst is complicated and the preparation cost is high.

[0004] CN103263917A discloses a method for preparing a Pt-BaTiO3 nanocatalyst for CO catalytic oxidation. This method employs a wet chemical reaction, using tetragonal perovskite BaTiO3 nanoparticles synthesized via a hydrothermal method, H2PtCl6·6H2O, NaBH4, and deionized water as reactants. Utilizing the reducing properties of NaBH4, Pt is reduced to the surface of the BaTiO3 nanoparticles, forming unstable Pt nanoparticles. These nanoparticles then undergo complete crystallization on the surface of the BaTiO3 ferroelectric nanoparticles during subsequent drying, thus obtaining the Pt-BaTiO3 nanocatalyst for CO catalytic oxidation. However, the CO purification catalyst provided by this method is not suitable for large-scale use due to the poor economic viability of using the precious metal Pt, the complex preparation method, and the harsh reaction conditions.

[0005] In the field of air pollution control, although the aforementioned catalysts can improve the purification capacity of CO and VOCs to some extent, there is still room for further improvement. Moreover, previous patents and literature have not studied the synergistic purification of VOCs and CO by catalysts. Therefore, developing a catalytic oxidation catalyst that can simultaneously remove CO and VOCs is of great practical significance. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide a monolithic catalyst, its preparation method and application, as well as a method for synergistically purifying carbon monoxide and volatile organic compounds. This monolithic catalyst possesses excellent oxidation capacity and, when applied to the synergistic purification of carbon monoxide and volatile organic compounds, offers the advantage of high removal efficiency for both.

[0007] To achieve the above objectives, a first aspect of the present invention provides an integral catalyst comprising a porous matrix and manganese oxide and a protective agent supported on the porous matrix, wherein the protective agent is selected from at least one of acidic substances, basic substances and metal oxides.

[0008] The average valence of manganese in the monolithic catalyst is 3.6-4.

[0009] A second aspect of the present invention provides a method for preparing a monolithic catalyst, the method comprising the following steps:

[0010] (1) Manganese-based material is mixed with dispersant and binder to obtain manganese oxide suspension, wherein the average oxidation state of manganese in manganese-based material is 3.6-4;

[0011] (2) The porous matrix is ​​impregnated in a suspension of manganese oxide and a protective agent by an impregnation method, and then dried and optionally calcined.

[0012] The protective agent is selected from at least one of acidic substances, alkaline substances, and metal oxides.

[0013] The third aspect of this invention provides the application of the monolithic catalyst described in the first aspect or the monolithic catalyst prepared by the preparation method described in the second aspect in waste gas treatment, preferably in the synergistic purification of carbon monoxide and volatile organic compounds.

[0014] A fourth aspect of the present invention provides a method for synergistically purifying carbon monoxide and volatile organic compounds, the method comprising: contacting exhaust gas containing carbon monoxide and volatile organic compounds with an integral catalyst;

[0015] The monolithic catalyst is either the monolithic catalyst described in the first aspect or the monolithic catalyst prepared by the preparation method described in the second aspect.

[0016] The beneficial effects of the present invention through the above technical solution include:

[0017] The monolithic catalyst provided by this invention exhibits a synergistic effect of porous matrix, manganese oxide, and protective agent, and the average oxidation state of manganese in the monolithic catalyst is controlled to 3.6-4, giving the catalyst excellent oxidation capacity. When applied to the synergistic purification of carbon monoxide and volatile organic compounds, it can efficiently and stably remove carbon monoxide and volatile organic compounds (VOCs), meeting the atmospheric requirements for the concentration of carbon monoxide and volatile organic compounds.

[0018] The monolithic catalyst provided by this invention has a simple preparation process, low cost, and high decarbonization accuracy, which is conducive to industrial promotion. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] The first aspect of the present invention provides an integral catalyst, the catalyst comprising a porous matrix and manganese oxide and a protective agent supported on the porous matrix, wherein the protective agent is selected from at least one of acidic substances, basic substances and metal oxides;

[0021] The average valence of manganese in the monolithic catalyst is 3.6-4.

[0022] The inventors of this invention have discovered that the integral catalyst utilizes a porous matrix, manganese oxide, and a protective agent to achieve a synergistic effect. By leveraging the adsorption and catalytic oxidation capabilities of manganese oxide, the impurity removal capabilities of the protective agent, and the stability of the porous matrix, it can achieve the goal of efficiently and stably eliminating volatile organic pollutants such as CO and VOCs in the synergistic purification of carbon monoxide and volatile organic compounds.

[0023] In this invention, the average oxidation state of manganese in the monolithic catalyst is 3.6-4. Maintaining a high average oxidation state of manganese in the monolithic catalyst is beneficial for the complete oxidation of CO and VOCs, achieving synergistic purification of carbon monoxide and volatile organic compounds.

[0024] The average oxidation state (AOS) of manganese described in this invention is calculated using the following formula:

[0025] AOS = 8.956 - 1.126 × ΔE, where ΔE is the difference between the high binding energy and low binding energy of manganese as measured by XPS Mn3S.

[0026] According to the present invention, preferably, based on the total weight of the monolithic catalyst, the content of the porous matrix in the monolithic catalyst is 50-80% by weight, preferably 55-80% by weight; the content of manganese oxide is 10-40% by weight, preferably 15-35% by weight; and the content of the protective agent is 5-35% by weight, preferably 5-30% by weight. This preferred embodiment is beneficial for improving the oxidation capacity of the monolithic catalyst and protecting the active phase of the catalyst from poisoning by exhaust gas, thereby extending the catalyst's service life.

[0027] The content of each component in the monolithic catalyst of the present invention is calculated by the amount of feed.

[0028] Preferably, the monolithic catalyst further contains a binder. In the monolithic catalyst of the present invention, the remainder is a binder.

[0029] The present invention does not particularly limit the type of adhesive, and can be a conventional choice in the art, which will not be described in detail here.

[0030] The total amount of all components in the catalyst described in this invention is 100%.

[0031] The monolithic catalyst of this invention has a special active phase crystal structure, which is beneficial to improving the conversion efficiency of CO and VOCs. Preferably, the manganese oxide has an α-MnO2 structure.

[0032] The crystal structure of manganese oxide described in this invention was obtained by XRD determination.

[0033] The protective agent in the monolithic catalyst of the present invention has a strong ability to remove impurities and can preferentially contact the exhaust gas, which is beneficial to protecting the active phase of the catalyst from poisoning by poisonous gases in the exhaust gas and extending the service life of the catalyst.

[0034] According to the present invention, preferably, the protective agent is selected from at least two of acidic substances, basic substances, and metal oxides.

[0035] According to the present invention, preferably, the protective agent is a metal oxide, as well as an alkaline substance and / or an acidic substance. The synergistic effect of using multiple protective agents is more conducive to improving the long-term performance of the catalyst.

[0036] According to the present invention, preferably, the mass ratio of the metal oxide to the alkaline substance and / or acidic substance is 1:1-8, more preferably 1:1-4. This preferred embodiment further enhances the long-term performance of the catalyst.

[0037] Preferably, the acidic substance is selected from at least one of ethyl titanate, isopropyl titanate, tetrabutyl titanate, tetraethyl silicate, tetraethyl orthosilicate, methyl orthosilicate, and methyl ethyl silicate, more preferably tetrabutyl titanate and / or tetraethyl orthosilicate.

[0038] Preferably, the alkaline substance is an inorganic alkali, and is preferably selected from at least one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0039] Preferably, the metal oxide is zinc oxide and / or iron oxide.

[0040] Using the aforementioned specific types of protective agents is beneficial for improving the long-term performance of catalysts.

[0041] In this invention, the structure (structure type) of the porous matrix can be at least one of particle stacking type, straight pore mesh type, fiber mesh type and foam type, preferably a honeycomb carrier.

[0042] The present invention does not particularly limit the type of the honeycomb carrier, and any conventional choice in the art can be used. Preferably, the porous matrix is ​​selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier, alumina honeycomb carrier, and metal alloy honeycomb carrier, and more preferably cordierite honeycomb carrier.

[0043] A second aspect of the present invention provides a method for preparing a monolithic catalyst, the method comprising the following steps:

[0044] (1) Manganese-based material is mixed with dispersant and binder to obtain manganese oxide suspension, wherein the average oxidation state of manganese in manganese-based material is 3.6-4;

[0045] (2) The porous matrix is ​​impregnated in a suspension of manganese oxide and a protective agent by an impregnation method, and then dried and optionally calcined.

[0046] The protective agent is selected from at least one of acidic substances, alkaline substances, and metal oxides.

[0047] According to the present invention, preferably, the amounts of manganese-based material, protective agent, and porous matrix are such that, based on the total weight of the monolithic catalyst, the content of porous matrix is ​​50-80% by weight, preferably 55-80% by weight; the content of manganese oxide is 10-40% by weight, preferably 15-35% by weight; and the content of protective agent is 5-35% by weight, preferably 5-30% by weight.

[0048] According to the present invention, preferably, in the manganese oxide suspension, the D of the manganese-based material 90The coating size is no larger than 10 micrometers, preferably 1-5 micrometers. This preferred embodiment makes it easier to form a stable coating layer.

[0049] The present invention does not have any particular limitation on how to obtain the average particle size within the above-mentioned range of the manganese-based material, and it can be achieved by conventional technical means, such as grinding.

[0050] According to the present invention, preferably, the mass ratio of manganese-based material to dispersant and binder on a dry basis is 1:0.05-0.7:0.05-0.8, more preferably 1:0.1-0.4:0.1-0.4.

[0051] The present invention allows for a wide range of choices of the dispersant. Preferably, the dispersant is selected from at least one of polyvinyl alcohol, acrylic acid, and methyl acrylate.

[0052] The present invention allows for a wide range of choices of the adhesive, including various adhesives conventionally used in the art. Preferably, the adhesive is selected from at least one of silica sol, alumina sol, boehmite, and aluminum phosphate sol.

[0053] According to the present invention, preferably, the manganese oxide suspension also contains water, and the amount of water used is 30-200g relative to 1g of manganese-based material.

[0054] According to the present invention, preferably, the manganese oxide suspension does not contain a surfactant. The surfactant can be a conventional choice in the art, and will not be described in detail here.

[0055] According to a specific embodiment of the present invention, step (1) includes: mixing manganese-based material with dispersant and binder, and then grinding for 1-3 hours to obtain a uniformly mixed manganese oxide suspension.

[0056] According to the present invention, preferably, the preparation method of the manganese-based material includes the following steps: precipitating a first aqueous solution of a manganese-containing compound and an aqueous solution of a second aqueous solution of a manganese-containing compound, and then crystallizing them to obtain the manganese-based material.

[0057] According to the present invention, preferably, the conditions for the precipitation reaction include: a temperature of 30-90°C and a time of 0.3-3h.

[0058] According to the present invention, preferably, the crystallization conditions include: a temperature of 100-150°C and a time of 1-20 hours.

[0059] Preferably, the method further includes filtering and washing the crystallized product to obtain a manganese-based material.

[0060] The present invention does not particularly limit the specific methods of filtration and washing, and can refer to conventional methods in the art.

[0061] The present invention does not have a particular limitation on the number of washing cycles, but the pH of the detergent used for washing is 7.

[0062] According to the present invention, preferably, the first manganese-containing compound is potassium permanganate and / or sodium permanganate.

[0063] According to the present invention, preferably, the second manganese-containing compound is selected from at least one of manganese sulfate, manganese nitrate and manganese acetate.

[0064] In this invention, a first manganese-containing compound containing high-valence manganese and a second manganese-containing compound containing low-valence manganese are reacted to regulate the average valence of manganese in the manganese-based material.

[0065] According to the present invention, preferably, the concentration of the first aqueous solution containing manganese compound is 2-15 wt%.

[0066] According to the present invention, preferably, the concentration of the second manganese-containing aqueous solution is 30-70 wt%.

[0067] In the preparation of the first and second aqueous solutions containing manganese compounds, ultrasonication or stirring can be used to ensure uniform mixing. The same applies to the preparation of the following solutions.

[0068] The present invention does not particularly limit the amount of the first manganese-containing compound and the second manganese-containing compound, but the average valence of manganese in the manganese-based material is within the above-mentioned range.

[0069] According to the present invention, preferably, the impregnation method in step (2) includes: contacting a porous matrix with a manganese oxide suspension, then drying and calcining to obtain a solid product; contacting the solid product with a protective agent suspension, then drying.

[0070] The present invention does not particularly limit the contact temperature in step (2), and it can be any temperature that the impregnation liquid can reach. There is also no particular limitation on the contact time, as long as the required amount of metal precursor is loaded onto the carrier. Generally, the higher the contact temperature and the greater the concentration of the impregnation liquid, the shorter the time required to achieve the same impregnation amount (i.e., the weight difference between the carrier after impregnation and before impregnation); conversely, the lower the contact temperature and the greater the concentration of the impregnation liquid, the shorter the time required; and vice versa. Once the required impregnation amount and conditions are determined, it is easy to select a suitable contact time. The specific operation of the impregnation method is well known to those skilled in the art. The impregnation method can be a saturated impregnation method or a supersaturated impregnation method. There is no particular limitation on the environment of the impregnation method. It can be carried out under sealed conditions or in an open environment according to conventional methods in the art. Solvent lost during the contact process can be replenished or not. Various gases, such as air, nitrogen, and water vapor, can be introduced during the contact process, or no new components can be introduced.

[0071] The present invention does not particularly limit the specific conditions for drying, and can refer to conventional methods in the art. Preferably, the drying conditions include: a temperature of 80-120°C and a time of 1-5 hours.

[0072] According to the present invention, preferably, the calcination conditions include a temperature of 300-500°C and a time of 1-5 hours. This preferred embodiment is beneficial for improving the oxidation capacity of the catalyst.

[0073] Preferably, the protective agent is selected from at least two of acidic substances, alkaline substances, and metal oxides.

[0074] More preferably, the protective agent is a metal oxide, as well as an alkaline substance and / or an acidic substance.

[0075] According to the present invention, preferably, the mass ratio of the metal oxide to the alkaline substance and / or acidic substance is 1:1-8, more preferably 1:1-4.

[0076] Preferably, the acidic substance is selected from at least one of ethyl titanate, isopropyl titanate, tetrabutyl titanate, tetraethyl silicate, tetraethyl orthosilicate, methyl orthosilicate, and methyl ethyl silicate, more preferably tetrabutyl titanate and / or tetraethyl orthosilicate.

[0077] Preferably, the alkaline substance is an inorganic alkali, and is preferably selected from at least one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0078] Preferably, the metal oxide is zinc oxide and / or iron oxide.

[0079] Preferably, in the protective agent suspension, the D of the protective agent... 90 The coating size is no larger than 10 micrometers, preferably 1-10 micrometers. This preferred embodiment allows for effective contact with manganese oxide, making it easier to form a uniform and stable coating layer.

[0080] The present invention does not have any particular limitation on how to obtain the average particle size of the protective agent within the above-mentioned range, and it can be achieved by conventional technical means, such as grinding.

[0081] According to the present invention, preferably, the concentration of the protective agent suspension is 50-250 g / L.

[0082] Preferably, the protective agent is dissolved in water to obtain an activated carbon suspension.

[0083] In this invention, the structure (structure type) of the porous matrix can be at least one of particle stacking type, straight pore mesh type, fiber mesh type and foam type, preferably a honeycomb carrier.

[0084] The present invention does not particularly limit the type of the honeycomb carrier, and any conventional choice in the art can be used. Preferably, the porous matrix is ​​selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier, alumina honeycomb carrier, and metal alloy honeycomb carrier, and more preferably cordierite honeycomb carrier.

[0085] The present invention does not impose any particular limitation on the size of the porous matrix, and can make appropriate selections according to different application scenarios.

[0086] According to the present invention, preferably, the method further includes: activating the material obtained in step (2) to obtain an integral catalyst.

[0087] According to the present invention, preferably, the activation conditions include: an activation temperature of 50-350°C, more preferably 100-300°C; and an activation time of 0.5-5 hours, more preferably 0.8-3 hours.

[0088] Preferably, the activation is carried out in the presence of an activating gas, which includes oxygen and an inert gas, wherein the volume content of the inert gas in the activating gas is 1-50%, preferably 2-30%.

[0089] Preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon, and is preferably nitrogen.

[0090] Using the specific activation method described above is beneficial for improving the reaction conversion rate.

[0091] The third aspect of the present invention provides the application of the monolithic catalyst described in the first aspect or the monolithic catalyst prepared by the preparation method described in the second aspect in waste gas treatment, preferably in the synergistic purification of carbon monoxide and volatile organic compounds, more preferably in the synergistic purification of carbon monoxide and volatile organic compounds in at least one of refinery tail gas, power plant tail gas, steel plant tail gas, flue gas generated from municipal solid waste incineration and motor vehicle exhaust.

[0092] A fourth aspect of the present invention provides a method for synergistically purifying carbon monoxide and volatile organic compounds, the method comprising: contacting exhaust gas containing carbon monoxide and volatile organic compounds with an integral catalyst; wherein the integral catalyst is the integral catalyst described in the first aspect or the integral catalyst prepared by the preparation method described in the second aspect.

[0093] Preferably, the contact conditions include: a temperature of 20-500°C, more preferably 100-400°C; and a volume hourly space velocity of 500-100,000 h⁻¹. -1 Preferably 2000-20000h -1 .

[0094] The monolithic catalyst described in this invention is applicable to the treatment of carbon monoxide and volatile organic compounds of different concentrations.

[0095] Preferably, the carbon monoxide content in the exhaust gas is 0.1-5000 ppm.

[0096] According to the present invention, preferably, the content of volatile organic compounds in the exhaust gas is 10-300 ppm.

[0097] The monolithic catalyst described in this invention can be applied to the treatment of various types of exhaust gases. Preferably, the exhaust gases include at least one of the following: refinery exhaust gas, power plant exhaust gas, steel plant exhaust gas, flue gas from municipal waste incineration, and vehicle exhaust gas. These exhaust gases contain a significant amount of toxic gases, such as SO2, NO2, and NH3, which can severely poison the catalyst. The monolithic catalyst provided by this invention not only has the advantage of excellent removal of carbon monoxide and volatile organic compounds, but also greatly inhibits the poisoning effect of these toxic substances, extending the catalyst's lifespan.

[0098] In this invention, the terms "first" and "second" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0099] The present invention will be described in detail below through embodiments.

[0100] The concentrations of carbon monoxide, sulfur dioxide, and volatile organic compounds in the exhaust gas were determined by gas chromatography.

[0101] Example 1

[0102] Preparation of manganese oxide suspension: 4.17 g of potassium permanganate was dissolved in 40.55 g of deionized water, heated to 60 °C and stirred to form a potassium permanganate solution. This solution was then mixed with 5.78 g of 50% manganese sulfate solution for 3 h, and reacted at 130 °C for 18 h. The resulting brown precipitate was filtered and washed multiple times with deionized water until the pH of the washing solution reached 7. The resulting filter cake was a manganese-based material. The average valence of manganese in the manganese-based material was 3.88. The manganese-based material was ground to D using a ball mill. 90 The sample was 4 micrometers thick. Then, polyvinyl alcohol (Shanghai Petrochemical): silica sol (15% by weight SiO2) on a dry basis: manganese-based material: water in a mass ratio of 1:1:10:88 was added. The mixture was then further milled in a ball mill for 2 hours to obtain a manganese oxide suspension.

[0103] Impregnated with manganese oxide suspension: The cordierite matrix was impregnated in the manganese oxide suspension for 2 min, then dried at 80 °C for 3 h, and calcined at 350 °C for 2 h to obtain a solid product.

[0104] Impregnating protective agent suspension: Zinc oxide and sodium carbonate are placed in water at a mass ratio of 1:1 and ground in a ball mill until D... 90 =8 micrometers, to obtain a protective agent suspension with a concentration of 200 g / L. The above solid product was immersed in the protective agent suspension for 2 min, dried at 120°C for 3 h, and then activated: the activation temperature was 350°C; the activation time was 4 h, and the activation gas consisted of 5% by volume oxygen and 95% by volume nitrogen.

[0105] The monolithic catalyst A1 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0106] Example 2

[0107] Preparation of manganese oxide suspension: 3.88 g of potassium permanganate was dissolved in 40.55 g of deionized water, heated to 60 °C and stirred to form a potassium permanganate solution. This solution was then mixed with 5.78 g of a 50% (w / w) manganese sulfate aqueous solution for 3 h, and reacted at 130 °C for 18 h. The resulting brown precipitate was filtered and washed multiple times with deionized water until the pH of the washing solution reached 7. The resulting filter cake was a manganese-based material. The average valence of manganese in the manganese-based material was 3.88.

[0108] The manganese-based material was ground to D using a ball mill. 90 The sample was 5 micrometers thick. Then, polyvinyl alcohol (Shanghai Petrochemical): silica sol (15% by weight SiO2) on a dry basis: manganese-based material: water in a mass ratio of 1:1:8:90 was added. The mixture was then further milled in a ball mill for 2 hours to obtain a manganese oxide suspension.

[0109] Impregnated with manganese oxide suspension: The cordierite matrix was impregnated in the manganese oxide suspension for 2 min, then dried at 80 °C for 3 h, and calcined at 350 °C for 2 h to obtain a solid product.

[0110] Impregnating protective agent suspension: Zinc oxide and sodium carbonate are placed in water at a mass ratio of 1:3 and ground in a ball mill until D... 90 =6 micrometers, to obtain a protective agent suspension with a concentration of 200 g / L. The above solid product was immersed in the protective agent suspension for 2 min, dried at 120°C for 3 h, and then activated: the activation temperature was 450°C; the activation time was 3 h, and the activation gas consisted of 3 vol% oxygen and 97 vol% nitrogen.

[0111] The monolithic catalyst A2 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0112] Example 3

[0113] Preparation of manganese oxide suspension: 3.64 g of potassium permanganate was dissolved in 40.55 g of deionized water, heated to 60 °C and stirred to form a potassium permanganate solution. This solution was then mixed with 5.78 g of a 50% (w / w) manganese sulfate aqueous solution for 3 h, and reacted at 130 °C for 18 h. The resulting brown precipitate was filtered and washed multiple times with deionized water until the pH of the washing solution reached 7. The resulting filter cake was a manganese-based material. The average valence of manganese in the manganese-based material was 3.62. The manganese-based material was ground to D using a ball mill. 90 The sample was 3 micrometers thick. Then, polymethyl acrylate, aluminum sol (20 wt% Al2O3), manganese-based material, and water were added in a mass ratio of 1:1:10:88. The mixture was then further milled in a ball mill for 2 hours to obtain a manganese oxide suspension.

[0114] Impregnated with manganese oxide suspension: The cordierite matrix was impregnated in the manganese oxide suspension for 2 min, then dried at 80 °C for 3 h, and calcined at 400 °C for 2 h to obtain a solid product.

[0115] Impregnating protective agent suspension: Zinc oxide and potassium carbonate are placed in water at a mass ratio of 1:1 and ground in a ball mill until D... 90 =6 micrometers, to obtain a protective agent suspension with a concentration of 200 g / L. The above solid product was immersed in the protective agent suspension for 2 min, dried at 120°C for 3 h, and then activated: the activation temperature was 450°C; the activation time was 3 h, and the activation gas consisted of 3 vol% oxygen and 97 vol% nitrogen.

[0116] The monolithic catalyst A3 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0117] Example 4

[0118] Preparation of manganese oxide suspension: 4.17 g of potassium permanganate was dissolved in 40.55 g of deionized water, heated to 60 °C and stirred to form a potassium permanganate solution. This solution was then mixed with 5.01 g of a 50% (w / w) manganese sulfate aqueous solution for 3 h, and reacted at 130 °C for 3 h. The resulting brown precipitate was filtered and washed multiple times with deionized water until the pH of the washing solution reached 7. The resulting filter cake was a manganese-based material. The average valence of manganese in the manganese-based material was 3.94. The manganese-based material was ground to D using a ball mill. 90 The sample was 3 micrometers thick. Then, polyvinyl alcohol (Shanghai Petrochemical): silica sol (15% by weight SiO2) on a dry basis: manganese-based material: water in a mass ratio of 1:1:10:88 was added. The mixture was then further milled in a ball mill for 2 hours to obtain a manganese oxide suspension.

[0119] Impregnated with manganese oxide suspension: The cordierite matrix was impregnated in the manganese oxide suspension for 2 min, then dried at 80 °C for 3 h, and calcined at 350 °C for 2 h to obtain a solid product.

[0120] Impregnating protective agent suspension: Iron oxide and tetrabutyl titanate are placed in water at a mass ratio of 1:1 and ground in a ball mill until D... 90 =5 micrometers, to obtain a protective agent suspension with a concentration of 200 g / L. The above solid product was immersed in the protective agent suspension for 2 min, dried at 120°C for 3 h, and then activated: the activation temperature was 450°C; the activation time was 3 h, and the activation gas consisted of 3 vol% oxygen and 97 vol% nitrogen.

[0121] The monolithic catalyst A4 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0122] Example 5

[0123] The method of Example 1 was followed, except that no binder or dispersant was added to the manganese oxide suspension.

[0124] The monolithic catalyst A5 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0125] Example 6

[0126] The method of Example 1 was followed, except that the manganese-based material was ground to D during the preparation of the manganese oxide suspension. 90 = 20 micrometers.

[0127] The monolithic catalyst A6 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0128] Example 7

[0129] The procedure was carried out according to Example 1, except that the protective agent was ground to D during the preparation of the protective agent suspension. 90 = 30 micrometers.

[0130] The monolithic catalyst A7 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0131] Comparative Example 1

[0132] The method of Example 1 was followed, except that potassium permanganate was not added, but only manganese sulfate was added, so that the manganese oxide content in the prepared monolithic catalyst was still 22% by weight. Specifically, manganese sulfate was mixed with polyvinyl alcohol, silica sol and water to obtain a manganese-containing solution.

[0133] The monolithic catalyst D1 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0134] Comparative Example 2

[0135] The method of Example 1 was followed, except that manganese sulfate was not added, only potassium permanganate was added, so that the manganese oxide content in the prepared monolithic catalyst was still 22% by weight. Specifically, potassium permanganate was mixed with polyvinyl alcohol, silica sol and water to obtain a manganese-containing solution.

[0136] The monolithic catalyst D2 was obtained. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0137] Comparative Example 3

[0138] The procedure was carried out according to Example 1, except that no protective agent was added, and the resulting solid product was catalyst D3. The composition and characteristics of the monolithic catalyst are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142] Note: The remainder in the catalyst is a binder.

[0143] Test Example 1

[0144] This test case also includes a coating stability test, in which the coating stability test is measured by the weight loss before and after 30 minutes of ultrasonic testing at 50 Hz.

[0145] The monolithic catalysts prepared in the examples and comparative examples were placed in a fixed-bed reactor. Then, refinery tail gas containing SO2, CO, and VOCs (CO concentration of 3500 ppm, VOCs concentration of 300 ppm, SO2 concentration of 50 ppm, and water vapor content of 5 wt%) was introduced into the fixed-bed reactor and reacted at 400°C and atmospheric pressure with a volume hourly space velocity of 10000 h⁻¹. -1 After the reaction has stabilized for 1 hour, samples were taken for analysis, and the concentrations of CO and VOCs in the exhaust gas were recorded. The mixed gas after the reaction was passed into the exhaust gas absorption tank. After testing and confirming that it meets environmental protection requirements, it can be further treated or vented. The test results are shown in Table 2.

[0146] Table 2

[0147]

[0148]

[0149] As can be seen from the results in Table 2, the monolithic catalyst provided by this invention has an excellent removal effect on carbon monoxide and volatile organic compounds.

[0150] As can be seen from Table 2, the integral catalyst coating described in this invention has good stability, better performance, and longer lifespan.

[0151] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An integral catalyst, the catalyst comprising a porous matrix and manganese oxide and a protective agent supported on the porous matrix; in, The average valence of manganese in the monolithic catalyst is 3.6-4; The protective agent is a metal oxide, and an alkaline and / or acidic substance, wherein the mass ratio of the metal oxide to the alkaline and / or acidic substance is 1:1-8. Based on the total weight of the monolithic catalyst, the content of the porous matrix in the monolithic catalyst is 50-80% by weight, the content of manganese oxide is 10-40% by weight, and the content of the protective agent is 5-35% by weight. The alkaline substance is an inorganic base; Wherein, the metal oxide is zinc oxide and / or iron oxide; The acidic substance is selected from at least one of ethyl titanate, isopropyl titanate, tetrabutyl titanate, tetraethyl silicate, tetraethyl orthosilicate, methyl orthosilicate, and methyl ethyl silicate. The preparation method of the monolithic catalyst includes the following steps: (1) Manganese-based material is mixed with dispersant and binder to obtain manganese oxide suspension, wherein the average oxidation state of manganese in manganese-based material is 3.6-4; (2) The porous matrix is ​​contacted with manganese oxide suspension by impregnation, and then dried and calcined to obtain a solid product; the solid product is contacted with protective agent suspension and then dried.

2. The catalyst according to claim 1, wherein, Based on the total weight of the monolithic catalyst, the content of porous matrix in the monolithic catalyst is 55-80% by weight, the content of manganese oxide is 15-35% by weight, and the content of protective agent is 5-30% by weight.

3. The catalyst according to claim 1, wherein, The manganese oxide has an α-MnO2 structure.

4. The catalyst according to claim 1, wherein, The mass ratio of the metal oxide to the alkaline and / or acidic substances is 1:1-4.

5. The catalyst according to claim 1, wherein, The acidic substance is selected from tetrabutyl titanate and / or tetraethyl orthosilicate.

6. The catalyst according to claim 1, wherein, The alkaline substance is selected from at least one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

7. The catalyst according to any one of claims 1-4, wherein, The porous matrix is ​​selected from at least one of cordierite honeycomb carriers, mullite honeycomb carriers, diamond honeycomb carriers, corundum honeycomb carriers, zirconium corundum honeycomb carriers, quartz honeycomb carriers, nepheline honeycomb carriers, feldspar honeycomb carriers, alumina honeycomb carriers, and metal alloy honeycomb carriers.

8. The catalyst according to claim 7, wherein the porous matrix is ​​selected from cordierite honeycomb carrier.

9. A method for preparing the monolithic catalyst according to any one of claims 1-8, the method comprising the following steps: (1) Manganese-based material is mixed with dispersant and binder to obtain manganese oxide suspension, wherein the average oxidation state of manganese in manganese-based material is 3.6-4; (2) The porous matrix is ​​contacted with manganese oxide suspension by impregnation, and then dried and calcined to obtain a solid product; the solid product is contacted with protective agent suspension and then dried.

10. The method according to claim 9, wherein, In manganese oxide suspension, the D of manganese-based materials 90 No larger than 10 micrometers.

11. The method according to claim 10, wherein, In the manganese oxide suspension, the D of the manganese-based material 90 It is 1-5 micrometers.

12. The method according to claim 9, wherein, The mass ratio of the manganese-based material to the dispersant and the binder on a dry basis is 1:0.05-0.7:0.05-0.

8.

13. The method according to claim 12, wherein, The mass ratio of the manganese-based material to the dispersant and the binder on a dry basis is 1:0.1-0.4:0.1-0.

4.

14. The method according to any one of claims 9-13, wherein, The dispersant is selected from at least one of polyvinyl alcohol, acrylic acid, and methyl acrylate.

15. The method according to any one of claims 9-13, wherein, The binder is selected from at least one of silica sol, alumina sol, boehmite, and phosphogypsum sol.

16. The method according to any one of claims 9-13, wherein, The manganese oxide suspension does not contain surfactants.

17. The method according to any one of claims 9-13, wherein, The preparation method of the manganese-based material includes the following steps: precipitating a first aqueous solution of a manganese-containing compound and an aqueous solution of a second aqueous solution of a manganese-containing compound, and then crystallizing them to obtain the manganese-based material.

18. The method according to claim 17, wherein, The precipitation conditions include a temperature of 30-90℃ and a time of 0.3-3h.

19. The method of claim 17, wherein, The crystallization conditions include a temperature of 100-150℃ and a time of 1-20h.

20. The method of claim 17, wherein, The first manganese-containing compound is potassium permanganate and / or sodium permanganate.

21. The method according to claim 20, wherein, The concentration of the first manganese-containing aqueous solution is 2-15 wt%.

22. The method according to claim 17, wherein, The second manganese-containing compound is at least one of manganese sulfate, manganese nitrate, and manganese acetate.

23. The method according to claim 22, wherein, The concentration of the second manganese-containing aqueous solution is 30-70 wt%.

24. The method according to any one of claims 9-13, wherein, The roasting conditions include: a temperature of 300-500℃ and a time of 1-5 hours.

25. The method according to any one of claims 9-13, wherein, In the protective agent suspension, the D of the protective agent 90 No larger than 10 micrometers.

26. The method of claim 25, wherein, In the protective agent suspension, the D of the protective agent 90 It ranges from 1 to 10 micrometers.

27. The method of claim 25, wherein, The concentration of the protective agent suspension is 50-250 g / L.

28. The method according to any one of claims 9-13, wherein, The method further includes: activating the material obtained in step (2) to obtain an integral catalyst.

29. The method according to claim 28, wherein, The activation conditions include: an activation temperature of 50-350℃ and an activation time of 0.5-5 hours.

30. The method according to claim 29, wherein, The activation conditions include: an activation temperature of 100-300℃ and an activation time of 0.8-3 hours.

31. The method according to claim 28, wherein, The activation is carried out in the presence of an activating gas, which includes oxygen and an inert gas, wherein the volume content of the inert gas in the activating gas is 1-50%.

32. The method according to claim 31, wherein, The activation is carried out in the presence of an activating gas, which includes oxygen and an inert gas, with the volume content of the inert gas in the activating gas being 2-30%.

33. A method for synergistically purifying carbon monoxide and volatile organic compounds, the method comprising: The exhaust gas containing carbon monoxide and volatile organic compounds is brought into contact with an integral catalyst. The monolithic catalyst is the monolithic catalyst according to any one of claims 1-8 or the monolithic catalyst prepared by the preparation method according to any one of claims 9-32.

34. The method according to claim 33, wherein, The contact conditions include: a temperature of 20-500°C and a volume hourly space velocity of 500-100,000 h⁻¹. -1 .

35. The method according to claim 34, wherein, The contact conditions include: a temperature of 100-400℃ and a volume hourly space velocity of 2000-20000 h⁻¹. -1 .

36. The method according to claim 33, wherein, The carbon monoxide content in the exhaust gas is 0.1-5000 ppm.

37. The method according to claim 33, wherein, The content of volatile organic compounds in the exhaust gas is 10-300 ppm.

38. The method according to any one of claims 33-37, wherein, The exhaust gas includes at least one of the following: refinery exhaust gas, power plant exhaust gas, steel plant exhaust gas, flue gas from municipal waste incineration, and motor vehicle exhaust gas.

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