Monolithic catalyst for CO and VOCs removal and preparation method thereof

Abstract

The present invention belongs to the field of catalysts, and specifically relates to a monolithic catalyst for removing CO and VOCs and a preparation method thereof. The preparation method comprises the following steps: 1) pre-treating the carrier by soaking it in dilute nitric acid, washing it, and drying it; 2) preparing a compound containing a coating of a loading aid into a slurry, impregnating the pre-treated carrier in the slurry, drying it, and then calcining it to obtain a carrier containing a coating of the loading aid; 3) immersing the carrier containing the coating of the loading aid obtained in step 2) in a solution of a compound containing a catalytically active component, and then drying and calcining the carrier obtained by the impregnation to obtain a carrier containing a catalyst component. The monolithic catalyst of the present invention has good catalytic conversion efficiency of CO and VOCs, and has good practical application value and prospects.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and in particular relates to an integral catalyst for removing CO and VOCs and a preparation method thereof. Background Art

[0002] Volatile organic compounds (VOCs) refer to organic compounds with a saturated vapor pressure greater than 70 Pa at room temperature and a boiling point below 260°C at normal pressure. CO is a colorless, odorless, and toxic gas. Vehicle exhaust emissions, the steel industry, coal and biofuel combustion, gasoline or industrial solvent volatilization, liquefied petroleum gas or natural gas leakage, natural plant releases, and other processes will emit large amounts of VOCs and CO into the atmosphere. With the increase in the number of cars today and the large-scale production of industrial waste gas, the types and concentrations of VOCs have also increased linearly. When the human body ingests VOCs and CO in excess of a certain dose, it will cause poisoning, and long-term exposure can also cause cancer. Therefore, the development of technical means to efficiently degrade CO and VOCs has become an urgent problem to be solved.

[0003] Currently, commonly used CO and VOC treatment technologies fall into two main categories: selective recovery and reuse, applicable to high-concentration organic waste gases with recycling value. Key methods include adsorption, absorption, condensation, and membrane separation. Second, rational conversion and destruction, primarily suited to treating industrial waste gases characterized by high air volume and low concentrations, primarily include biological, plasma, catalytic oxidation, and photocatalytic methods. Catalytic oxidation utilizes catalysts to reduce the activation energy required for the oxidation reaction of organic pollutants, enabling flameless combustion at relatively low temperatures, converting organic matter into harmless substances such as CO2 and H2O. Compared to direct combustion, catalytic oxidation boasts a lower ignition temperature, typically between 100 and 400°C, significantly reducing energy consumption in exhaust gas treatment. Furthermore, catalytic oxidation offers a simple process flow and broad applicability, adapting to CO and VOC degradation in a variety of scenarios. Therefore, catalytic oxidation has become the preferred option for treating CO and VOC waste gases in industry.

[0004] The catalysts currently used for catalytic combustion at home and abroad are mainly divided into supported precious metal catalysts and non-precious metal oxide catalysts. Supported precious metal catalysts use precious metals such as Pt, Pd, and Au as active components. They can convert VOCs and CO into CO2 and H2O at relatively low temperatures, but the high cost and easy sintering of precious metals limit their use to a certain extent. Non-precious metal oxide catalysts use metal oxides such as Co, Mn, and Ce as active components. These catalysts are relatively cheap and widely available compared to precious metal catalysts, but they also have disadvantages such as unsatisfactory activity and poor durability. In addition, the preparation of integral catalysts usually requires the addition of a binder to ensure the full combination of the active component and the carrier, and the preparation process is complex and the cycle is long. After use, it is inevitable that the catalyst will fall off and crack, which will lead to a decrease in the catalytic effect of the catalyst. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a monolithic catalyst for removing CO and VOCs and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a monolithic catalyst for removing CO and VOCs comprises the following steps:

[0008] 1) pre-treating the support by soaking it in dilute nitric acid, then washing and drying it;

[0009] 2) preparing a slurry containing a compound for loading an auxiliary agent coating, impregnating the pretreated carrier into the slurry, drying, and then calcining to obtain a carrier containing an auxiliary agent coating;

[0010] 3) The support containing the auxiliary agent coating obtained in step 2) is immersed in a solution containing a compound of a catalytically active component, and then the support obtained by the impregnation is dried and calcined to obtain a catalyst component-loaded support.

[0011] Preferably, the drying means adopts microwave drying;

[0012] The compound containing the loading aid coating layer is a compound containing at least Ti.

[0013] The compound containing the loading auxiliary agent coating is Ti, or a mixture of Ti and one or two of Ce and Al.

[0014] The compound containing the loading aid coating is a mixture of Ti and Ce, and the molar ratio of the two is 1-5:1; preferably 1:3;

[0015] Alternatively, the compound containing the loading auxiliary agent coating is a mixture of Ti, Ce, and Al; the molar ratio of the three is 3:0.2-0.8:0.2-0.8; preferably 3:0.5:0.5.

[0016] The catalytically active component contains at least Pt.

[0017] The catalytically active component is Pt, or a combination of Pt and Pd, or a combination of Pt, Pd and Mn.

[0018] The catalytic active component is a composition of Pt and Pd, and the molar ratio of the two is 1:1.

[0019] The catalytically active component is a composition of Pt, Pd and Mn, and the molar ratio of the three is 1:1:1-5, preferably 1:1:3.

[0020] The carrier is cordierite.

[0021] The present invention also includes an integral catalyst for removing CO and VOCs obtained by the preparation method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The monolithic catalyst of the present invention is loaded with an auxiliary agent coating and catalytically active components by an impregnation method, which allows the catalytically active components to be fully exposed without the need for additional binders. At the same time, combined with microwave rapid drying technology, the active components are dispersed more evenly on the surface. This method is simple and easy to implement, and the active components are not easily lost.

[0024] (2) The additive coating in the monolithic catalyst of the present invention can dissociate H2O into hydroxyl species to participate in the reaction, so that the catalyst has a good catalytic effect under aqueous conditions. At the same time, it can regulate the redox properties and acidity and alkalinity of the carrier, thereby improving the adsorption of the catalyst and the interaction with the metal carrier.

[0025] (3) As a preferred form, the monolithic catalyst of the present invention can minimize the use of precious metals by regulating the ratio between precious metals and non-precious metals, saving costs and achieving optimal catalytic effects. In addition, the strong interaction between the precious metals and non-precious metals increases the surface dispersion of the active components, inhibits the weak adsorption of SO2 on the catalyst surface, reduces the desorption temperature of strongly adsorbed SO2 and the decomposition temperature of sulfate, and exhibits good catalytic activity and sulfur tolerance.

[0026] (4) The monolithic catalyst of the present invention has good catalytic conversion efficiency of CO and VOCs, and has good practical application value and prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a graph showing the stability of the catalyst of Example 5 of the present invention to CO;

[0028] Figure 2 is a graph showing the catalytic activity of the catalyst of Example 6 of the present invention against various VOCs;

[0029] Figure 3 This is a diagram showing the catalytic activity of the catalyst of Comparative Example 9 of the present invention toward various VOCs. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and the best embodiments.

[0031] Example 1: A method for preparing a monolithic catalyst for removing CO and VOCs, comprising the following steps:

[0032] 1) Soak cordierite (46 mesh, length × width = 15 cm × 15 cm, thickness = 20 cm) in 5% dilute nitric acid for 2 h, rinse with deionized water, and dry at 100°C for 3 h before use.

[0033] 2) Immersing the cordierite support treated in step 1) in a 25% by weight titanium sulfate solution for 10 minutes, then purging the residual liquid from the inner and outer walls of the cordierite, and then rapidly drying the support in a 2450 MHz microwave drying apparatus for 10 minutes;

[0034] 3) placing the support obtained in step 2) in a muffle furnace and calcining at 550° C. for 4 h at a heating rate of 5° C. / min in a dry air atmosphere to obtain a catalyst;

[0035] 4) adding chloroplatinic acid to deionized water and stirring thoroughly until uniform to prepare a slurry to be impregnated; the concentration of chloroplatinic acid is 0.5%;

[0036] 5) The catalyst obtained in step 3) was placed in the slurry prepared in step (4) and immersed for 10 minutes, and then the residual liquid on the inner and outer walls of the catalyst was purged, and then placed in a 2450 MHz microwave drying equipment for rapid drying for 10 minutes;

[0037] 6) The catalyst obtained in step 5) was placed in a muffle furnace and calcined at 550°C for 4 hours at a heating rate of 5°C / min. After cooling after the calcination, a monolithic catalyst A for CO and VOCs removal was obtained, wherein the weight gain ratio of the precious metal was 0.043% and the mass percentage of the additive coating was 7%.

[0038] Example 2: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce atomic molar ratio of 3:1 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst B for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 9.3%.

[0039] Example 3: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst C for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 8.7%.

[0040] Example 4: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, except that the following parts are different: in step (2), a cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid and palladium chloride is added to a certain amount of deionized water in a ratio of Pt:Pd atomic molar ratio of 1:1 and stirred until uniform to obtain a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.5%. The other steps are the same as those in Example 1, and a monolithic catalyst D for removing CO and VOCs is obtained, wherein the weight gain ratio of the precious metal is 0.067%, and the mass percentage of the additive coating is 8.7%.

[0041] Example 5: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, except that the following parts are different: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added to a certain amount of deionized water in a Pt:Pd:Mn atomic molar ratio of 1:1:3 and stirred until uniform to obtain a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.5%. The other steps are the same as those in Example 1, and a monolithic catalyst E for removing CO and VOCs is obtained, wherein the weight gain ratio of the precious metal is 0.067%, and the mass percentage of the additive coating is 8.7%.

[0042] Example 6: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, except that: in step (1), the size of the cordierite is changed to 200 mesh, length × width = 10 cm × 10 cm, thickness = 10 cm; in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added to a certain amount of deionized water in a Pt:Pd:Mn atomic molar ratio of 1:1:3 and stirred until uniform to obtain a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.5%, and the other steps are the same as in Example 1, thereby obtaining a monolithic catalyst F for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.046%, and the mass percentage of the additive coating is 8.7%.

[0043] Comparative Example 1: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite support is placed in a solution with a Ti:Ce atomic molar ratio of 1:1 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst G for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 7.1%.

[0044] Comparative Example 2: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite support is placed in a solution having a Ti:Ce atomic molar ratio of 5:1 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst H for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 9.7%.

[0045] Comparative Example 3: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite support is placed in a solution with a Ti:Al atomic molar ratio of 3:1 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst I for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 6.8%.

[0046] Comparative Example 4: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.8:0.2 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst J for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 9.1%.

[0047] Comparative Example 5: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.2:0.8 and immersed for 10 minutes, and the other steps are the same as in Example 1, to obtain a monolithic catalyst K for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.043%, and the mass percentage of the additive coating is 7.3%.

[0048] Comparative Example 6: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution with a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added in a ratio of Pt:Pd:Mn atomic molar ratio of 1:1:1, and a certain amount of deionized water is fully stirred until uniform to prepare a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.5%, and the other steps are as in Example 1, thereby obtaining a monolithic catalyst L for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.067%, and the mass percentage of the additive coating is 8.7%.

[0049] Comparative Example 7: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, except that the following parts are different: in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added to a certain amount of deionized water in a Pt:Pd:Mn atomic molar ratio of 1:1:5 and stirred until uniform to obtain a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.5%. The other steps are the same as in Example 1, and a monolithic catalyst M for removing CO and VOCs is obtained, wherein the weight gain ratio of the precious metal is 0.067%, and the mass percentage of the additive coating is 8.7%.

[0050] Comparative Example 8: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, and the different parts include: in step (2), the cordierite carrier is placed in a solution with a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added in a Pt:Pd:Mn atomic molar ratio of 1:1:3, and a certain amount of deionized water is fully stirred until uniform to prepare a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.3%. The other steps are as in Example 1, and a monolithic catalyst N for removing CO and VOCs can be obtained, wherein the weight gain ratio of the precious metal is 0.019%, and the mass percentage of the additive coating is 8.7%.

[0051] Comparative Example 9: A method for preparing a monolithic catalyst for removing CO and VOCs, wherein the basic synthesis steps are the same as those in Example 1, except that: in step (1), the size of the cordierite is changed to 200 mesh, length × width = 10 cm × 10 cm, thickness = 10 cm; in step (2), the cordierite carrier is placed in a solution having a Ti:Ce:Al atomic molar ratio of 3:0.5:0.5 and immersed for 10 minutes; in step (4), a certain amount of chloroplatinic acid, palladium chloride, and manganese acetate is added to a certain amount of deionized water in a Pt:Pd:Mn atomic molar ratio of 1:1:3 and stirred until uniform to obtain a slurry to be impregnated, wherein the total concentration of chloroplatinic acid and palladium chloride is 0.3%, and the other steps are as in Example 1, thereby obtaining a monolithic catalyst O for removing CO and VOCs, wherein the weight gain ratio of the precious metal is 0.013%, and the mass percentage of the additive coating is 8.6%.

[0052] It should be noted that the comparative examples of this application are only for the convenience of comparison and are still part of the embodiments and are within the scope of protection of this application.

[0053] The prepared catalysts of the embodiment and the comparative example were subjected to a fixed bed reaction, with CO gas concentration of 8000 ppm, benzene gas concentration of 1000 ppm, acetone gas concentration of 1000 ppm, cyclohexane gas concentration of 1000 ppm, n-hexane gas concentration of 1000 ppm, ethyl acetate gas concentration of 1000 ppm, O2 concentration of 20 vol.%, N2 as balance gas, and gas space velocity of 18000 h -1 , reaction temperature: 100-400 ° C. Under this condition, the catalyst activity test was carried out, and the test results for CO are shown in Table 1;

[0054] Table 1

[0055] CO complete conversion temperature / ℃ Example 1 255 Example 2 240 Example 3 235 Example 4 225 Example 5 200 Comparative Example 1 250 Comparative Example 2 248 Comparative Example 3 254 Comparative Example 4 240 Comparative Example 5 247 Comparative Example 6 205 Comparative Example 7 208 Comparative Example 8 216

[0056] As can be seen from the table, the effects of the compounds of the loading aid coating are shown in Table 1 (PtTi), 2 (PtTiCe (Ti:Ce=3:1)), 3 (PtTiCeAl (Ti:Ce:Al=3:0.5:0.5)), Comparative Example 1 (PtTiCe (Ti:Ce=1:1)), Comparative Example 2 (PtTiCe (Ti:Ce=5:1)), Comparative Example 3 (PtTiAl (Ti:Al=3:1)), Comparative Example 4 (PtTiCeAl l(Ti:Ce:Al=3:0.8:0.2)), comparative example 5(PtTiCeAl(Ti:Ce:Al=3:0.2:0.8)), it can be seen that the combination of Ti and Ce as auxiliary coating has better effect than the combination of Ti and Al. Among the combination of Ti and Ce, Ti:Ce=3:1 has the best effect, and the combination of Ti, Ce and Al is better than the combination of Ti and Ce, among which Ti:Ce:Al=3:0.5:0.5 has the best effect.

[0057] The effects of the catalytically active components are compared, for example, in Example 3 (PtTiCeAl (Ti:Ce:Al=3:0.5:0.5)), Example 4 (PtPdTiCeAl (Pt:Pd=1:1, Ti:Ce:Al=3:0.5:0.5)), Example 5 (PtPdMnTiCeAl (Pt:Pd:Mn=1:1:3, Ti:Ce:Al=3:0.5:0.5)), Comparative Example 6 (PtPdMnTiCeAl (Pt:Pd:Mn=1:1:1 , Ti:Ce:Al=3:0.5:0.5)), and Comparative Example 7 (PtPdMnTiCeAl (Pt:Pd:Mn=1:1:5, Ti:Ce:Al=3:0.5:0.5)). It can be seen that increasing the catalytically active component Pd is beneficial to improving the catalytic conversion of CO. At the same time, increasing the non-metallic component Mn, due to the strong interaction between the precious metal and the non-precious metal, increases the dispersion of the active component surface, which can improve the catalytic conversion of CO. Among them, Pt:Pd:Mn=1:1:3 has the best effect. In summary, it can be seen that Example 5 ((PtPdMnTiCeAl (Pt:Pd:Mn=1:1:3, Ti:Ce:Al=3:0.5:0.5))) has the best improvement in CO catalytic conversion effect compared to Examples 1-4 and Comparative Examples 1 to 8.

[0058] Figure 1 The catalyst E prepared in Example 5 was heated in an atmosphere containing 60 ppm SO2, 15-20% water content, 8000 ppm CO concentration, and 18000 h-1 velocity. -1 Under the conditions, the catalytic oxidation of CO at 220°C for 60 hours still maintains a conversion rate of more than 98%, reflecting the good sulfur and water resistance of the catalyst.

[0059] Figure 2 Figure 2 shows the catalytic performance of Catalyst F prepared in Example 6 of the present invention for the conversion of benzene, acetone, cyclohexane, n-hexane, and ethyl acetate at temperatures between 180°C and 300°C. The results show that, with the exception of acetone and ethyl acetate, the catalytic efficiency for all other VOC gases, except for acetone and ethyl acetate, exceeds 90% at temperatures between 195°C and 210°C, maintaining stable catalyst activity. Acetone and ethyl acetate also achieve conversion rates of 90% at 270°C and 290°C, respectively.

[0060] Figure 3 This is a diagram showing the catalytic effect of catalyst O prepared in comparative example 9 on benzene, acetone, cyclohexane, n-hexane and ethyl acetate at 180-320°C.

[0061] In summary, the monolithic catalyst of the present invention utilizes an impregnation method to load the additive coating and catalytically active components, fully exposing the catalytically active components without the need for additional binders. Combined with microwave rapid drying technology, the active components are uniformly dispersed on the surface. This method is simple and easy to implement, and the active components are not easily lost. The additive coating in the monolithic catalyst of the present invention dissociates H₂O into hydroxyl species that participate in the reaction, ensuring a strong catalytic effect even in aqueous conditions. Furthermore, the redox properties and acidity of the support can be manipulated, thereby improving catalyst adsorption and metal-support interaction. By manipulating the ratio of precious metals to non-precious metals, the monolithic catalyst of the present invention can minimize the amount of precious metals used, saving costs and achieving optimal catalytic performance. Furthermore, the strong interaction between the precious metals and non-precious metals increases the surface dispersion of the active components, inhibits weak adsorption of SO₂ on the catalyst surface, lowers the desorption temperature of strongly adsorbed SO₂ and the decomposition temperature of sulfates, and exhibits excellent catalytic activity and sulfur tolerance. The monolithic catalyst of the present invention exhibits excellent catalytic conversion efficiency for CO and VOCs, and has promising practical applications and prospects.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Application of a monolithic catalyst for removing CO and VOCs in removing CO and VOCs, characterized in that: The preparation method of the monolithic catalyst comprises the following steps: 1) Pre-treat the carrier by soaking it in dilute nitric acid, then washing and drying it; 2) The compound containing the additive coating is prepared into a slurry, the pretreated carrier is immersed in the slurry, dried, and then calcined to obtain the carrier containing the additive coating; The compound containing the additive coating is a mixture of Ti, Ce, and Al; the molar ratio of the three is 3:0.5:0.5; the drying method is microwave drying; 3) Immersing the support containing the additive coating obtained in step 2) in a solution of a compound containing a catalytically active component, wherein the catalytically active component is a combination of Pt, Pd, and Mn in a molar ratio of 1:1:3; Thereafter, the carrier obtained after impregnation with the catalytically active components is dried and then calcined to obtain the monolithic catalyst.

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