Catalyst for CO catalytic oxidation and SCR (selective catalytic reduction) denitration and preparation method and application thereof

Abstract

The invention discloses a catalyst for CO catalytic oxidation and SCR denitration and a preparation method and application thereof, and belongs to the technical field of environmental catalytic materials, Pt single atoms only having catalytic oxidation activity and TiO2 are used as shells, and CO and NO are preferentially subjected to catalytic oxidation. Due to the fact that the loading capacity of Pt single atoms is low, CO and NO are oxidized to generate CO2 and NO2, and NH3 is not oxidized. And enabling NO2, NO and NH3 to enter the Ce core wrapped by TiO2 at the same time to carry out rapid SCR reaction. According to the method, the advantages that NH3 is difficult to oxidize due to oxidability of a small amount of Pt, but NO can be oxidized are mainly utilized, and CO oxidation and NH3-SCR denitration are efficiently carried out through reaction partition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental catalytic materials, and particularly relates to a catalyst for CO catalytic oxidation and SCR denitration, and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of global industrialization and urbanization, air pollution problems are becoming increasingly serious. Nitrogen oxides (NO x , x is 1 or 2) and carbon monoxide (CO) are two major gaseous pollutants. NOx is an important precursor of photochemical smog, acid rain and haze (PM2.5), which poses a serious threat to the human respiratory system and the ecosystem. CO is a colorless and odorless toxic gas with extremely strong binding ability to human hemoglobin, which can cause tissue hypoxia and even suffocation death. These pollutants are mainly derived from the combustion process of fossil fuels, such as automobile exhaust, coal-fired power plants, industrial kilns, etc. Therefore, developing efficient and economical NOx and CO purification technology has great practical significance for protecting the environment and human health.

[0003] Currently, the widely used NOx purification technology in industry is NH3-SCR technology. The catalyst mainly used in this technology is V2O5-WO3 / TiO2 catalyst, and its optimal activity window is usually high (300-400℃). However, this catalyst has some inherent defects: first, its low-temperature (<250℃) activity is poor, which cannot meet the needs of low-temperature exhaust gas of many industrial devices (such as gas turbines, chemical boilers) during low-load operation or cold start, resulting in secondary pollution caused by escaped NOx; second, vanadium species have certain biological toxicity, and the disposal of waste catalysts can easily cause environmental risks; third, the catalyst has weak CO oxidation ability and cannot achieve the simultaneous removal of CO. At the same time, the purification of CO usually relies on the catalytic oxidation technology of noble metals (such as Pt, Pd). Although this kind of catalyst shows extremely high low-temperature oxidation activity for CO, it has almost no effect on the SCR reaction of NOx, and even in some cases, the noble metal can excessively activate NH3, leading to its direct oxidation instead of being used to reduce NOx, which has adverse effects. Therefore, in the complex flue gas environment where multiple pollutants coexist, it is often necessary to design multiple-stage and multi-section purification devices to treat NOx and CO respectively, which undoubtedly increases the complexity of the system, the occupied area and the investment and operation cost.

[0004] To solve the above problems, developing a multifunctional catalyst that can simultaneously remove NOx and CO at low temperatures has become a research hotspot and an urgent need in this field. The core challenge lies in how to ingeniously integrate different active sites to efficiently catalyze NH3-SCR and CO oxidation reactions at low temperatures while avoiding mutual inhibition between the two reactions. Although some studies have been conducted on the simultaneous removal of NOx and CO (Selective NH3 trapping as the enabler for efficient bifunctional catalysis of NH3-SCR and CO oxidation reactions, Catalysis B: Environmental, 2025.10.15); Novel insights for simultaneous NOx and CO Removal: Cu + -Sm 3+ -Ov-Ti 4+ asymmetric active site promoting NH3-SCR coupled with CO oxidation reaction, Chemical Engineering Journal, 2024.2.1), although these studies demonstrate efficient removal of NO and CO, when CO is completely oxidized, NH3 is oxidized to N2O, resulting in a sharp decline in the selectivity of NH3-SCR. Therefore, how to achieve high-selectivity catalysis of CO catalytic oxidation and NH3-SCR has been a difficult problem that has plagued the development of this technology. SUMMARY

[0005] To overcome the shortcomings of the prior art, the present application provides a catalyst for CO catalytic oxidation and SCR denitrification, as well as a preparation method and application thereof. The catalyst for CO catalytic oxidation and SCR denitrification of the present application is a Pt monatomic nanocatalyst with ultra-low loading. The catalyst of the present application can realize the oxidation of NO to NO2 and promote the rapid NH3-SCR reaction, thereby ultimately achieving high-selectivity catalysis of CO catalytic oxidation and NH3-SCR, solving the technical problem of efficient cooperation between CO and NH3-SCR reactions.

[0006] To achieve the above object, the present application provides the following technical solutions:

[0007] The application provides a catalyst for CO catalytic oxidation and SCR denitration, which is characterized in that the catalyst is an asymmetric spherical core-shell nanoparticle CeO2@TiO2 formed by wrapping CeO2 with TiO2, and the asymmetric spherical core-shell nanoparticle CeO2@TiO2 is used as a carrier and loaded with an active component Pt monatomic.

[0008] The principle of the application is that in the CeO2@TiO2 of the application, TiO2 is used as a shell and CeO2 is used as a core. The catalyst for CO catalytic oxidation and SCR denitration of the application is a CO and NH3-SCR collaborative denitration catalyst with high activity, high selectivity and good stability. The catalyst of the application is loaded with Pt monatomic with only catalytic oxidation activity and TiO2 as an outer shell, and preferentially catalyzes and oxidizes CO and NO. Because the loading amount of Pt monatomic is low, CO and NO are oxidized to generate CO2 and NO2, and NH3 is not oxidized. NO2, NO and NH3 simultaneously enter the Ce inner core wrapped by TiO2 to perform a rapid SCR reaction. The application mainly utilizes the advantage that a small amount of Pt is difficult to oxidize NH3 but can oxidize NO, and realizes efficient CO oxidation and NH3-SCR denitration through reaction zoning.

[0009] Further, the particle size of the CeO2 core is 50-200 nm, and the thickness of the TiO2 shell is 10-50 nm.

[0010] The application further provides a preparation method of the catalyst for CO catalytic oxidation and SCR denitration.

[0011] The CeO2 nanospheres are synthesized by a hydrothermal method.

[0012] The CeO2 nanospheres are mixed with tetrabutyl titanate, and a hydrothermal reaction is performed, so that tetrabutyl titanate is hydrolyzed to wrap amorphous TiO2 on the surface of the CeO2 nanospheres, and after calcination, the asymmetric spherical core-shell nanoparticle CeO2@TiO2 is obtained.

[0013] The asymmetric spherical core-shell nanoparticle CeO2@TiO2 is mixed with a Pt source solution, Pt is loaded on the asymmetric spherical core-shell nanoparticle CeO2@TiO2 by an equal-volume impregnation method, and after drying and calcination, the monatomic Pt / CeO2@TiO2 catalyst is obtained.

[0014] The monatomic Pt / CeO2@TiO2 catalyst is heat-treated in a CO-containing atmosphere to obtain the catalyst for CO catalytic oxidation and SCR denitration.

[0015] The application wraps an amorphous TiO2 layer on the surface of CeO2 nanospheres by hydrolyzing tetrabutyl titanate, and obtains asymmetric core-shell nanoparticles CeO2@TiO2 of anatase type after calcination. The asymmetric core-shell nanoparticles CeO2@TiO2 are used as a carrier, and monatomic Pt is loaded by an equal-volume impregnation method. After heat treatment in a CO-containing atmosphere, the pretreatment process stabilizes the Pt species into a monatomic state, which can not only catalyze CO oxidation efficiently, but also promote the rapid SCR reaction path by promoting the oxidation of NO into NO2, and at the same time, avoids the non-selective oxidation of NH3 by noble metals.

[0016] Further, the process for synthesizing the CeO2 nanospheres by a hydrothermal method is as follows: soluble cerium salt is added to water, and then urea is added, and after stirring uniformly, hydrothermal reaction is carried out at 150-200 DEG C to obtain the CeO2 nanospheres.

[0017] Illustratively, the soluble cerium salt is Ce(NO3)3·6H2O.

[0018] Further, when the asymmetric core-shell nanoparticles CeO2@TiO2 are prepared, the calcination temperature is 500-600 DEG C.

[0019] Further, when Pt is loaded by an equal-volume impregnation method, the calcination temperature is 500-600 DEG C.

[0020] Further, the Pt source solution is selected from a chloroplatinic acid (H2PtCl6·6H2O) solution or a platinum nitrate solution.

[0021] Further, the heat treatment temperature is 300-400 DEG C, and the heat treatment time is 1-2 hours.

[0022] The application also provides an application of the above-mentioned catalyst for CO catalytic oxidation and SCR denitration in CO catalytic oxidation and SCR denitration.

[0023] The catalyst for CO catalytic oxidation and SCR denitration provided by the application can catalyze CO oxidation and NH3-SCR reaction simultaneously under medium-high temperature conditions.

[0024] Further, the CO catalytic oxidation and SCR denitration temperature is 200-325 DEG C. Within the above-mentioned temperature range, the NO conversion rate can be as high as 90% or more, and the N2 selectivity is 97% or more; at the same time, CO can be converted by 100% within the temperature range.

[0025] When the temperature of the CO catalytic oxidation cooperated with the SCR denitration is 250-325℃, the loading of Pt is 0.05-0.1 wt%; when the temperature of the CO catalytic oxidation cooperated with the SCR denitration is 200-250℃, the loading of Pt is 0.1-0.15 wt%.

[0026] Compared with the prior art, the present application has the following advantages and technical effects:

[0027] 1. Excellent high-efficiency synergistic activity: the catalyst of the present application realizes high-efficiency synergy of CO oxidation and NH3-SCR in a medium-high temperature window of 250-325℃. The NO conversion rate is above 90% at 225-325℃, and the N2 selectivity is above 97%; CO is completely converted after >250℃, solving the industry problem that CO and NH3-SCR are difficult to be purified cooperatively.

[0028] 2. Unique structural design: the CeO2@TiO2 asymmetric interface spherical structure ingeniously combines the excellent redox performance of CeO2 and the good surface acidity and stability of TiO2, providing high-efficiency bifunctional active sites for the two reactions.

[0029] 3. Ultra-low noble metal dosage and innovative pretreatment: only 0.05-0.15 wt% of ultra-low Pt loading is used, greatly reducing the cost of the catalyst. Through the key step of 2% CO (nitrogen as the balance gas) pretreatment, the chemical state of Pt is effectively adjusted, the non-selective oxidation side reaction of NH3 is inhibited, and the oxidation activity of CO is greatly improved, realizing the effect of taking advantages and avoiding disadvantages.

[0030] 4. Wide application prospect: the preparation method of the catalyst of the present application is simple, and the performance is stable, which is very suitable for treating low-temperature flue gas with low sulfur content, such as tail gas purification of gas turbine, natural gas boiler, chemical process, etc., and has great industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the application and are incorporated herein in their entirety. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 The scanning electron microscope (SEM) image of the monatomic Pt / CeO2@TiO2 catalyst prepared for Example 2 of the present application;

[0033] Figure 2 The NO conversion rate curve (A) and N2 selectivity graph (B) of catalysts B1-B3 and catalysts A1-A3 at different reaction temperatures;

[0034] Figure 3Figures showing CO conversion curves for catalysts A1-A3 and catalysts B1-B3 at different reaction temperatures;

[0035] Figure 4 Figures showing CO conversion curves for catalysts C1-C3 and catalysts D1-D3 at different reaction temperatures. DETAILED DESCRIPTION

[0036] The present application will now be described in detail with reference to various exemplary embodiments thereof, which description is not to be considered as limiting the application to the described embodiments, but rather to be understood as a description of certain aspects, features and embodiments of the application.

[0037] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, for a range of values of a parameter, unless otherwise stated, each intervening value of the parameter is also specifically included within the scope of the present application. The intervening values of the parameter are combined with a stated value of the parameter in range form. These are only exemplary of the various preferred embodiments and are not intended to be limiting on the scope of the application. Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. Various embodiments of the present application will be described in detail with reference to drawings, which are intended to illustrate but not limit the application.

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described herein. In case of conflict, the content of the specification will control.

[0039] It will be apparent to those skilled in the art that various modifications and variations can be made to the specific embodiments of the application described and illustrated herein without departing from the spirit or scope of the application. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples are illustrative only and not restrictive of the application.

[0040] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or the like are open-ended and do not exclude additional, unrecited elements or method steps.

[0041] The embodiments of the present application provide a catalyst for CO catalytic oxidation and SCR denitration, which is a catalyst with TiO2-coated CeO2 asymmetric spherical core-shell nanoparticles CeO2@TiO2 as a carrier, and active component Pt monomers loaded on the carrier, the loading amount of the Pt monomers being 0.05-0.15 wt%, preferably 0.1 wt%.

[0042] In the embodiment of the present application, the particle size of the CeO2 core is 50-200 nm, and the thickness of the TiO2 shell is 10-50 nm.

[0043] The embodiment of the present application also provides a preparation method of the catalyst for catalytic oxidation of CO and SCR denitration.

[0044] The CeO2 nanospheres are synthesized by a hydrothermal method.

[0045] The CeO2 nanospheres are mixed with tetrabutyl titanate, and a hydrothermal reaction is performed, so that tetrabutyl titanate is hydrolyzed to wrap amorphous TiO2 on the surface of the CeO2 nanospheres, and after calcination, the asymmetric core-shell nanospheres CeO2@TiO2 are obtained.

[0046] The asymmetric core-shell nanospheres CeO2@TiO2 are mixed with a Pt source solution, Pt is loaded on the asymmetric core-shell nanospheres CeO2@TiO2 by an equal-volume impregnation method, and after drying and calcination, the monatomic Pt / CeO2@TiO2 catalyst is obtained.

[0047] The monatomic Pt / CeO2@TiO2 catalyst is heat-treated in a CO-containing atmosphere to obtain the catalyst for catalytic oxidation of CO and SCR denitration.

[0048] In the embodiment of the present application, the process for synthesizing the CeO2 nanospheres by the hydrothermal method is as follows: a soluble cerium salt is added to water, and then urea is added, and after stirring uniformly, a hydrothermal reaction is performed at 150-200℃ to obtain the CeO2 nanospheres.

[0049] For example, the soluble cerium salt is Ce(NO3)3·6H2O.

[0050] In the embodiment of the present application, when the CeO2 nanospheres are synthesized by the hydrothermal method, the temperature of the hydrothermal reaction is preferably 180℃, and the time is 12 hours.

[0051] In the embodiment of the present application, after the CeO2 nanospheres are mixed with tetrabutyl titanate, the temperature of the hydrothermal reaction is 180℃, and the time of the hydrothermal reaction is 3 hours.

[0052] In the embodiment of the present application, when the asymmetric core-shell nanospheres CeO2@TiO2 are prepared, the temperature of calcination is 500-600℃; preferably, the temperature of calcination is 500℃, and the time is 3 hours.

[0053] In the embodiment of the present application, when Pt is loaded by the equal-volume impregnation method, the temperature of calcination is 500-600℃; preferably, the temperature of calcination is 500℃, and the time is 2h.

[0054] In the embodiment of the present application, the Pt source solution is selected from a chloroplatinic acid (H2PtCl6·6H2O) solution or a platinum nitrate solution.

[0055] In the embodiment of the present application, the temperature of the heat treatment is 300-400℃, and the time of the heat treatment is 1-2 hours; preferably, the temperature of the heat treatment is 400℃, and the time of the heat treatment is 1 hour.

[0056] In the embodiment of the present application, the process of heat treatment of the single-atom Pt / CeO2@TiO2 catalyst in the CO-containing atmosphere is as follows: the single-atom Pt / CeO2@TiO2 catalyst is loaded in a fixed bed reactor, a gas composed of 2% CO and 98% N2 is introduced at normal pressure, the space velocity is 60000 h-1, and the temperature is raised from room temperature to 400℃ at a rate of 5℃ / min, and the catalyst is kept at 400℃ for 1 hour, and the catalyst for CO catalytic oxidation and SCR denitration is obtained after natural cooling. -1 , and the catalyst for CO catalytic oxidation and SCR denitration is obtained after natural cooling.

[0057] The embodiment of the present application also provides an application of the above-mentioned catalyst for CO catalytic oxidation and SCR denitration in CO catalytic oxidation and SCR denitration.

[0058] The catalyst for CO catalytic oxidation and SCR denitration provided by the present application can simultaneously catalyze CO oxidation and NH3-SCR reaction under medium-high temperature conditions.

[0059] In the embodiment of the present application, the temperature of CO catalytic oxidation and SCR denitration is 200-325℃.

[0060] When the temperature of CO catalytic oxidation and SCR denitration is 250-325℃, the loading amount of Pt is 0.05-0.1 wt%; when the temperature of CO catalytic oxidation and SCR denitration is 200-250℃, the loading amount of Pt is 0.1-0.15 wt%.

[0061] The catalyst for CO catalytic oxidation and SCR denitration of the application takes an asymmetric interface core-shell spherical structure (CeO2@TiO2) formed by TiO2 wrapping CeO2 as a carrier, and a mass fraction of 0.05-0.15% of Pt monatomic atoms are loaded on the carrier. The catalyst is preprocessed at 300-400°C using a mixed gas containing 2% (volume fraction, the same below) of CO (N2 as the balancing gas), which stabilizes the Pt species into a monatomic state, so that the Pt species can efficiently catalyze CO oxidation, promote the rapid SCR reaction path by promoting the oxidation of NO into NO2, and at the same time avoid the non-selective oxidation of NH3 by the noble metal. The catalyst for CO catalytic oxidation and SCR denitration of the application can realize 100% conversion of CO and high conversion rate (>90%) and high N2 selectivity (>97%) of NO at the same time in the medium-high temperature window of 250-325°C, and solves the technical problem that CO and NH3-SCR reaction are difficult to efficiently cooperate. The catalyst for CO catalytic oxidation and SCR denitration of the application has a simple preparation method and low cost, and has a broad application prospect in the field of flue gas purification containing CO and NOx (x is 1 or 2) at the same time.

[0062] Unless otherwise specified, atmospheric pressure refers to a standard atmospheric pressure, i.e. the atmospheric pressure at sea level, which is about 101.325 kilopascals (kPa), or 760 millimeters of mercury (mmHg), and is often simplified as 1 atmosphere (atm).

[0063] The isochoric impregnation method, also known as the incipient wetness impregnation method or the pore saturation impregnation method, is a method for preparing a supported catalyst or a composite material. The core principle is to use an impregnation liquid (a solution containing an active component) with a volume equal to the total pore volume of the carrier material, and through capillary action, the precursor of the active component is uniformly absorbed and filled into all the pores of the carrier. In simple terms, "as many pores as much solution", the solution just enough to wet the carrier, but there is no excess liquid left outside.

[0064] Unless otherwise specified, the room temperature in the application is 25±2°C.

[0065] The raw materials used in the embodiments of the application are all commercially available.

[0066] The technical solutions of the application are further described below through examples.

[0067] Example 1

[0068] A preparation method of a catalyst for CO catalytic oxidation and SCR denitration, the steps are as follows:

[0069] (1) CeO2 nanospheres were synthesized by hydrothermal method: 2.17 g Ce(NO3)3·6H2O was dissolved in 40 mL of deionized water, 1.8 g of urea was added, and after stirring for 30 minutes, the mixture was transferred to a high-pressure reactor lined with 100 mL of polytetrafluoroethylene and reacted at 180 °C for 12 hours to obtain CeO2 nanospheres.

[0070] (2) Preparation of asymmetric spherical core-shell nanoparticles CeO2@TiO2 support: 1.5 mL of tetrabutyl titanate was added dropwise to CeO2 nanospheres, and hydrothermal treatment was continued at 180℃ for 3 hours. The product was collected by centrifugation, dried at 80℃, and calcined at 500℃ for 3 hours to obtain asymmetric spherical core-shell nanoparticles CeO2@TiO2 support (the particle size of CeO2 core is 100 nm, and the thickness of TiO2 shell is about 20 nm).

[0071] (3) Loading Pt single atoms: H2PtCl6·6H2O was added to deionized water and stirred evenly to prepare a solution containing 0.1 mg / mL of Pt. The above solution was mixed with asymmetric spherical core-shell nanoparticle CeO2@TiO2 support. Pt was loaded onto 0.5 g of asymmetric spherical core-shell nanoparticle CeO2@TiO2 support by the equal volume impregnation method, so that the loading amount of Pt was 0.05 wt%. After standing at room temperature for 12 hours, it was dried at 80℃ and then calcined in air at 500℃ for 2 hours to obtain a single-atom Pt / CeO2@TiO2 catalyst, denoted as A1.

[0072] (4) CO pretreatment: 100 mg of single-atom Pt / CeO2@TiO2 catalyst was packed into a fixed-bed reactor, and a gas consisting of 2% CO and 98% N2 was introduced at atmospheric pressure with a space velocity of 60,000 h⁻¹. -1 The temperature was increased from room temperature to 400℃ at a rate of 5℃ / min and maintained at 400℃ for 1 hour. After natural cooling, Pt catalyst for CO catalytic oxidation and SCR denitrification was obtained. NC / CeO2@TiO2, denoted as B1.

[0073] Example 2

[0074] A method for preparing a catalyst for synergistic CO catalytic oxidation and SCR denitration is the same as in Example 1, except that the loading of Pt in step (3) is 0.1 wt%. The resulting single-atom Pt / CeO2@TiO2 catalyst is denoted as A2, and its SEM image is shown below. Figure 1 As shown, Pt is uniformly dispersed and does not form aggregated particles; the catalyst obtained for CO catalytic oxidation and SCR denitrification is denoted as B2.

[0075] Example 3

[0076] A preparation method of a catalyst for CO catalytic oxidation and SCR denitration, same as example 1, except that the loading of Pt in step (3) is 0.15 wt%, the obtained single-atom Pt / CeO2@TiO2 catalyst is recorded as A3, and the obtained catalyst for CO catalytic oxidation and SCR denitration is recorded as B3.

[0077] Comparative example 1

[0078] 100 mg of the single-atom Pt / CeO2@TiO2 catalyst obtained in step (3) of example 1 was loaded into a fixed bed reactor, and a gas composed of 2% H2 and 98% N2 was passed at atmospheric pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at a rate of 5℃ / min, and treated at 400℃ for 1 hour, and after natural cooling, the final catalyst C1 was obtained.

[0079] Comparative example 2

[0080] 100 mg of the single-atom Pt / CeO2@TiO2 catalyst obtained in step (3) of example 2 was loaded into a fixed bed reactor, and a gas composed of 2% H2 and 98% N2 was passed at atmospheric pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at a rate of 5℃ / min, and treated at 400℃ for 1 hour, and after natural cooling, the final catalyst C2 was obtained.

[0081] Comparative example 3

[0082] 100 mg of the single-atom Pt / CeO2@TiO2 catalyst obtained in step (3) of example 3 was loaded into a fixed bed reactor, and a gas composed of 2% H2 and 98% N2 was passed at atmospheric pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at a rate of 5℃ / min, and treated at 400℃ for 1 hour, and after natural cooling, the final catalyst C3 was obtained.

[0083] Comparative example 4

[0084] 100 mg of the single-atom Pt / CeO2@TiO2 catalyst obtained in step (3) of example 1 was loaded into a fixed bed reactor, and a gas composed of pure N2 was passed at atmospheric pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at a rate of 5℃ / min, and treated at 400℃ for 1 hour, and after natural cooling, the final catalyst D1 was obtained.

[0085] Comparative example 5

[0086] The 100 mg of monatomic Pt / CeO2@TiO2 catalyst obtained in step (3) of Example 2 was loaded into a fixed bed reactor, and pure N2 was passed through at normal pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at 5℃ / min, and kept at 400℃ for 1 hour, and after natural cooling, the final catalyst D2 was obtained.

[0087] Comparative Example 6

[0088] The 100 mg of monatomic Pt / CeO2@TiO2 catalyst obtained in step (3) of Example 3 was loaded into a fixed bed reactor, and pure N2 was passed through at normal pressure, with a space velocity of 60000 h-1. -1 From room temperature to 400℃ at 5℃ / min, and kept at 400℃ for 1 hour, and after natural cooling, the final catalyst D3 was obtained.

[0089] Performance test

[0090] The activity of the catalysts prepared in each example and comparative example was evaluated on a micro fixed bed reactor. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 10000 ppm CO and 16% O2, with N2 as the balance gas, and the space velocity was 60000 h-1. -1 The NO and CO concentrations at the inlet and outlet were measured using an infrared detector.

[0091] The test results are shown in Table 1. Figures 2-4 Catalysts B1-B3 exhibited the best synergistic catalytic performance: the NO conversion of B1 and B2 reached more than 90% at 225-325℃, and the N2 selectivity was more than 97%; the CO conversion reached 100% at 250℃; the NO conversion of B3 reached more than 90% at 200-250℃, and the N2 selectivity was more than 99%; the CO conversion reached 100% at 225℃. In contrast, the CO oxidation activity of catalysts A1-A3 without any treatment was significantly lower, and the NO conversion window moved to high temperature. The CO catalytic activity of catalysts C1-C3 pretreated with H2 and catalysts D1-D3 pretreated under pure N2 conditions was not much different from A1-A3, mainly because CO as a strong reducing gas not only changed the coordination environment of Pt, but also adjusted the oxygen vacancy content between Ce and Ti. And as can be seen from Table 1, B, the present application solves the problem of "when CO is completely oxidized, NH3 will be oxidized to N2O, resulting in a sharp decline in the selectivity of NH3-SCR, due to the excessive oxidation ability of the catalyst". Figure 2

[0092] ​The above results show that the catalyst design strategy and pretreatment method of the application are crucial for realizing efficient synergy of CO and NH3-SCR under medium-high temperature conditions.

[0093] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A catalyst for the catalytic oxidation of CO in conjunction with SCR denitration, characterized by, The catalyst uses asymmetric spherical core-shell nanoparticles CeO2@TiO2 formed by TiO2 wrapping CeO2 as a carrier, and the carrier is loaded with active component Pt monatomic atoms, and the loading amount of the Pt monatomic atoms is 0.05-0.15 wt%.

2. The catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 1, characterized in that, The particle size of the CeO2 core is 50-200 nm, and the thickness of the TiO2 shell is 10-50 nm.

3. A method for preparing the catalyst for the catalytic oxidation of CO in conjunction with SCR denitration according to any one of claims 1-2, characterized in that, The method comprises the following steps: CeO2 nanospheres are synthesized by using a hydrothermal method; The CeO2 nanospheres are mixed with tetrabutyl titanate, hydrothermal reaction is performed, and after calcination, asymmetric spherical core-shell nanoparticles CeO2@TiO2 are obtained; The asymmetric spherical core-shell nanoparticles CeO2@TiO2 are mixed with a Pt source solution, Pt is loaded on the asymmetric spherical core-shell nanoparticles CeO2@TiO2 by using an equal-volume impregnation method, and after drying and calcination, a monatomic Pt / CeO2@TiO2 catalyst is obtained; The monatomic Pt / CeO2@TiO2 catalyst is subjected to heat treatment in a CO-containing atmosphere, and the catalyst for CO catalytic oxidation and SCR denitration is obtained.

4. The preparation method of the catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 3, characterized in that, The process for synthesizing CeO2 nanospheres by using a hydrothermal method is as follows: soluble cerium salt is added to water, urea is added, uniform stirring is performed, and then hydrothermal reaction is performed at 150-200 DEG C to obtain the CeO2 nanospheres.

5. The preparation method of the catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 3, characterized in that, When the asymmetric spherical core-shell nanoparticles CeO2@TiO2 are prepared, the calcination temperature is 500-600 DEG C.

6. The preparation method of the catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 3, characterized in that, When Pt is loaded by using an equal-volume impregnation method, the calcination temperature is 500-600 DEG C.

7. The preparation method of the catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 3, characterized in that, The Pt source solution is selected from a chloroplatinic acid solution or a platinum nitrate solution.

8. The preparation method of the catalyst for CO catalytic oxidation synergized with SCR denitration according to claim 3, characterized in that, The heat treatment temperature is 300-400 DEG C, and the heat treatment time is 1-2 hours. 9.A use of the catalyst for CO catalytic oxidation and SCR denitration according to any one of claims 1-2 in CO catalytic oxidation and SCR denitration.

10. Use according to claim 9, characterized in that, The CO catalytic oxidation and SCR denitration temperature is 200-325 DEG C.

Images