Transition metal oxide composite catalyst as well as preparation method and application thereof

Abstract

The invention relates to a transition metal oxide composite catalyst and a preparation method and application thereof, the transition metal oxide composite catalyst comprises a transition metal oxide and a carrier, the carrier comprises a noble metal-coated molecular sieve, and the noble metal-coated molecular sieve is composed of a molecular sieve and a noble metal dispersed in the molecular sieve; wherein the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated in the molecular sieve. The transition metal oxide composite catalyst prepared by compounding the transition metal oxide and the noble metal-coated molecular sieve has surface lattice oxygen capable of participating in CO catalytic combustion, further has excellent catalytic combustion activity on CO, and still keeps the structure integrity of the noble metal-coated molecular sieve in the presence of a small amount of transition metal oxide; the transition metal oxide composite catalyst has low-temperature high activity, and also has relatively strong SO2 poisoning resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of CO control and catalytic purification in environmental protection, and in particular to a transition metal oxide composite catalyst and a preparation method and application thereof. Background Art

[0002] In industrial production and motor vehicle exhaust, due to the incomplete combustion of various carbon sources, there is a high concentration of CO gas inside, which is seriously harmful to human health and the ecological environment. Among the existing treatment methods, catalytic combustion of CO into CO2 is considered to be the most effective and energy-saving treatment method, but some wastes containing CO also contain a certain amount of SO2 gas, and the presence of SO2 has a poisonous effect on the catalyst.

[0003] To alleviate the poisoning effect, currently, strategies such as coating the active sites of precious metals with molecular sieves and building molecular fences to block SO2 are mainly used to resist sulfur, enhance the anti-sulfur performance of the catalyst, and increase the catalyst's action time in SO2-containing exhaust gas. However, due to the limitation of the amount of precious metals that can be loaded and the catalytic mechanism of the catalyst itself, the ignition temperature of the catalytic combustion of CO by precious metal@molecular sieve catalysts is high, which hinders their application in treating low-temperature flue gas.

[0004] For the catalytic combustion of CO, CN116851002A discloses a CO catalyst in which the surface of an activated alumina ball is loaded with gadolinium oxide, iron oxide and manganese oxide. 100 =200°C, but the catalyst activity in the presence of SO2 atmosphere was not tested or explained.

[0005] CN116251586A discloses a sulfur-resistant CO oxidation catalyst, a preparation method and an application. In the preparation method of the sulfur-resistant CO oxidation catalyst, a coating slurry is prepared, the coating is applied to a honeycomb ceramic carrier, and the coating is dried and calcined to obtain a honeycomb ceramic area coated with a composite oxide firm coating, that is, it mainly uses a microwave-assisted method to increase the specific surface area and pore volume of the TiO2-SiO2 coating, optimize the pore structure of the catalyst, and improve the problem of sulfate generated by the impurity SO2 participating in the side reaction blocking the catalyst micropores and causing the catalyst to deactivate. However, the preparation method is cumbersome and complicated, and the stability of the catalyst still needs to be further improved.

[0006] Therefore, how to provide a CO catalytic combustion catalyst with high activity at low temperature and resistance to SO2 poisoning is of great significance and has become a problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a transition metal oxide composite catalyst and a preparation method and application thereof. By compounding a transition metal oxide with a noble metal@molecular sieve, the prepared transition metal oxide composite catalyst has surface lattice oxygen that can participate in the catalytic combustion of CO, and thus has excellent catalytic combustion activity for CO. In addition, in the presence of a small amount of transition metal oxide, the structure of the noble metal@molecular sieve is still kept intact, so that the transition metal oxide composite catalyst has high activity at low temperature and strong resistance to SO2 poisoning.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a transition metal oxide composite catalyst, the transition metal oxide composite catalyst comprises a transition metal oxide and a carrier, the carrier comprises a noble metal@molecular sieve, and the noble metal@molecular sieve comprises a molecular sieve and a noble metal dispersed inside the molecular sieve;

[0010] Wherein, the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve.

[0011] The present invention composites a transition metal oxide with a noble metal@molecular sieve to prepare a transition metal oxide composite catalyst. The composite transition metal oxide activates the oxygen reverse overflow process in the noble metal@molecular sieve under low temperature conditions (<250°C), that is, the surface lattice oxygen in the transition metal oxide is thermally activated to form active oxygen species, which exist on the catalyst surface or in a free state, migrate to the noble metal site, and then can oxidize CO to CO2, significantly improving the CO oxidation activity of the transition metal oxide composite noble metal@molecular sieve, while taking into account the strong resistance to SO2 poisoning.

[0012] As a preferred technical solution of the present invention, based on the mass of the carrier, the loading amount of the transition metal oxide is 2 to 20wt%, for example, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc., preferably 5 to 10wt%.

[0013] In the present invention, if the loading amount of the transition metal oxide is too high, there will no longer be an obvious activity enhancement effect, resulting in a waste of raw materials, and it will block the molecular sieve pores, resulting in a decrease in the catalyst's ability to resist SO2 poisoning; if the loading amount of the transition metal oxide is too low, there will still be no obvious activity enhancement effect, and the effect of improving the catalytic combustion activity of CO is not obvious.

[0014] Preferably, based on the mass of the precious metal@molecular sieve, the loading amount of the precious metal is 0.1-1wt%, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1wt%, etc., preferably 0.2-0.5wt%.

[0015] In the present invention, if the loading amount of the precious metal in the carrier is too high, the precious metal cannot be completely dispersed in the molecular sieve, and clusters are formed on the surface or in the pores; if the loading amount of the precious metal in the carrier is too low, the catalyst active components are too few, resulting in poor catalyst activity, and thus the effect of improving the catalytic combustion activity of CO is not obvious.

[0016] As a preferred technical solution of the present invention, the transition metal oxide includes any one of Fe3O4, TiO2, MoO3, WO3, Co3O4 or CeO2 or a combination of at least two, preferably any one of TiO2, MoO3 or WO3.

[0017] Preferably, the particle size of the transition metal oxide is 3 to 20 nm, for example, 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm or 20 nm, etc., preferably 5 to 10 nm.

[0018] Preferably, the noble metal includes any one of Pt, Pd, Ru, Rh, Ag, Au or Ir or a combination of at least two of them, preferably any one of Pt, Ru or Ir.

[0019] As a preferred technical solution of the present invention, the molecular sieve includes CHA molecular sieve.

[0020] In the present invention, the CHA molecular sieve has high stability and high specific surface area, which is convenient for loading transition metal oxides and noble metals, and further improves the stability of the catalyst.

[0021] Preferably, the CHA molecular sieve comprises any one of SSZ-13, SAPO-34, SAPO-47 or AIPO-34 or a combination of at least two thereof, preferably SSZ-13 or SAPO-34.

[0022] In a second aspect, the present invention further provides a method for preparing the transition metal oxide composite catalyst according to the first aspect, the preparation method comprising the following steps:

[0023] The transition metal oxide is prepared by using a transition metal oxide precursor, and then the transition metal oxide is impregnated and loaded on a carrier, or the transition metal oxide precursor is directly impregnated and loaded on a carrier, and then calcined to obtain the transition metal oxide composite catalyst;

[0024] The noble metal@molecular sieve is composed of a molecular sieve and a noble metal dispersed inside the molecular sieve; and the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve.

[0025] As a preferred technical solution of the present invention, the carrier is a noble metal@molecular sieve with a noble metal loading of 0.1 to 1 wt%.

[0026] It should be noted that the present invention uses a noble metal@molecular sieve with a noble metal loading of 0.1 to 1 wt % as a carrier, which can be prepared by adjusting the concentration and addition amount of the raw materials based on the existing technology.

[0027] Preferably, the preparation method of the carrier comprises a one-pot hydrothermal method, an ion exchange method or a crystallization method, preferably a one-pot hydrothermal method.

[0028] Preferably, the impregnation process includes stirring.

[0029] Preferably, the stirring time is 2 to 6 hours, for example 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0030] Preferably, drying is further included after the impregnation and before the calcination.

[0031] Preferably, the drying method is stirring and evaporating to dryness.

[0032] Preferably, the drying temperature is 50-100°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C.

[0033] As a preferred technical solution of the present invention, the transition metal oxide precursor material includes any one of ferric nitrate, tetrabutyl titanate, cerium nitrate, cobalt nitrate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate, or a combination of at least two thereof, preferably any one of tetrabutyl titanate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate.

[0034] Preferably, the calcination temperature is 300-600°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C.

[0035] Preferably, the calcination holding time is 2 to 6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0036] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0037] The transition metal oxide prepared from the transition metal oxide precursor, the solvent and the carrier are mixed and stirred for 2 to 6 hours, or the transition metal oxide precursor, the aqueous solution and the carrier are mixed and stirred for 2 to 6 hours, and ultrasonic dispersion is performed, and the mixture is stirred and evaporated to dryness at 50 to 100° C., and the evaporated product is calcined at 300 to 600° C. for 2 to 6 hours to obtain the transition metal oxide composite catalyst;

[0038] Among them, the noble metal@molecular sieve is composed of a molecular sieve and a noble metal dispersed inside the molecular sieve; the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve; the carrier is a noble metal@molecular sieve with a noble metal loading of 0.1 to 1wt%; the preparation method of the carrier includes a one-pot hydrothermal method, an ion exchange method or a crystal transformation method; the transition metal oxide precursor includes any one of ferric nitrate, tetrabutyl titanate, cerium nitrate, cobalt nitrate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate, or a combination of at least two of them; the solvent includes any one of n-propane, water, ethanol or acetone.

[0039] In the third aspect, the present invention also provides an application of a transition metal oxide composite catalyst, wherein the transition metal oxide composite catalyst described in the first aspect, or the transition metal oxide composite catalyst prepared by the preparation method described in the second aspect, is applied to the removal of gaseous pollutants in mobile sources and / or fixed sources.

[0040] As a preferred technical solution of the present invention, the gaseous pollutants include CO gas containing SO2.

[0041] Preferably, the removal temperature is 150-300°C, such as 150°C, 180°C, 200°C, 230°C, 250°C, 280°C or 300°C, etc., preferably 200-250°C.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] 1) The present invention combines a transition metal oxide with a noble metal @ molecular sieve, and utilizes the special phenomenon of oxygen reverse overflow of the transition metal oxide to provide active oxygen, so that the transition metal oxide composite noble metal @ molecular sieve catalyst has surface lattice oxygen that can participate in the catalytic combustion of CO, changes the catalytic combustion pathway of the noble metal @ molecular sieve, and thus has excellent catalytic combustion activity for CO. In addition, in the presence of a small amount of transition metal oxide, the structure of the noble metal @ molecular sieve is still kept intact, so that the transition metal oxide composite catalyst has high activity at low temperature and strong resistance to SO2 poisoning;

[0044] 2) The preparation process of the present invention is simple and easy to operate, and can be applied to the efficient removal of pollutants such as CO in mobile sources and / or fixed sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a comparison chart of the anti-SO2 stability of the 5% TiO2 / Pt@SSZ-13 catalyst of Example 1 of the present invention, the 5% WO3 / Pt@SSZ-13 of Example 5 and the 5% V2O5 / Pt@SSZ-13 catalyst of Example 11. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0047] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0048] In a specific embodiment of the present invention, a Pt@SSZ-13 carrier with a Pt loading of 0.1 to 1 wt% is prepared by the following method, which comprises the following steps:

[0049] 0.70 g NaOH and 6.5 g TMAdaOH were added to 7 mL deionized water, followed by the addition of 282-2826 μL 0.02 g / mL chloroplatinic acid aqueous solution and 0.03-0.3 g (3-mercaptopropyl)-trimethoxysilane. After stirring for 12 h, 0.62 g NaAlO2 was added, and the mixture was stirred until it became clear. Subsequently, 7.5 g silica sol solution (40 wt%) was added, and the resulting gel was stirred continuously for 4 h. The gel was poured into a 100 mL polytetrafluoroethylene autoclave and heated at 160 ° C for 5 days. The reaction product was then calcined at 550 ° C for 6 h to obtain a Pt@SSZ-13 carrier with a Pt loading of 0.1-1 wt%.

[0050] The TiO2 nanoparticles used in the specific implementation of the present invention are prepared by the following method, which comprises the following steps:

[0051] A mixture of 1.2 mL of deionized water and 10 mL of ethanol was slowly added to a mixed solution containing 10 mL of tetrabutyl titanate, 25 mL of ethanol, and 1.5 mL of acetic acid, and the product was further stirred for 1 h to obtain a transparent sol, which was then transferred to a polytetrafluoroethylene autoclave and heated in an electric drying oven at 150°C for 20 h. The resulting precipitated product was washed 4 times with ethanol, separated by high-speed centrifugation, and dried to obtain TiO2 nanoparticles.

[0052] Example 1

[0053] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof, wherein the transition metal oxide composite catalyst is a 5% TiO2 / Pt@SSZ-13 catalyst, wherein the Pt loading is 0.25wt% and the TiO2 loading is 5wt%;

[0054] The preparation method of the 5% TiO2 / Pt@SSZ-13 catalyst comprises the following steps:

[0055] TiO2 nanoparticles were dispersed in n-propane to obtain a 2 mg / mL TiO2 nanoparticle solution, 1 g Pt@SSZ-13 carrier was added to 25 mL TiO2 nanoparticle solution and stirred for 4 h, then evaporated with stirring at 75 °C, and then calcined at 400 °C for 4 h to obtain the 5% TiO2 / Pt@SSZ-13 catalyst.

[0056] Example 2

[0057] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the transition metal oxide composite catalyst is a 10% TiO2 / Pt@SSZ-13 catalyst, and the loading amount of TiO2 is 10wt%;

[0058] In the preparation method, the addition amount of the TiO2 nanoparticle solution is 50 mL, and the other preparation methods and parameters are consistent with those in Example 1.

[0059] Example 3

[0060] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the transition metal oxide composite catalyst is a 15% TiO2 / Pt@SSZ-13 catalyst, and the loading amount of TiO2 is 15wt%;

[0061] In the preparation method, the addition amount of the TiO2 nanoparticle solution is 75 mL, and the other preparation methods and parameters are consistent with those in Example 1.

[0062] Example 4

[0063] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the transition metal oxide composite catalyst is a 20% TiO2 / Pt@SSZ-13 catalyst, and the loading amount of TiO2 is 20wt%;

[0064] In the preparation method, the addition amount of the TiO2 nanoparticle solution is 100 mL, and the other preparation methods and parameters are consistent with those in Example 1.

[0065] Example 5

[0066] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof, wherein the transition metal oxide composite catalyst is a 5% WO3 / Pt@SSZ-13 catalyst, wherein the Pt loading is 0.25wt% and the WO3 loading is 5wt%;

[0067] The preparation method of the 5% WO3 / Pt@SSZ-13 catalyst comprises the following steps:

[0068] 56.25 mg of ammonium paratungstate was dissolved in 100 mL of water, and then 1 g of Pt@SSZ-13 carrier was added, stirred for 4 h, then evaporated to dryness with stirring at 75°C, and then calcined at 600°C for 6 h to obtain the 5% WO3 / Pt@SSZ-13 catalyst.

[0069] Example 6

[0070] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 5 is that the transition metal oxide composite catalyst is a 10% WO3 / Pt@SSZ-13 catalyst, and the loading amount of WO3 is 10wt%;

[0071] In the preparation method, the addition amount of the WO3 nanoparticle solution is 112.5 mg, and the other preparation methods and parameters are consistent with those in Example 5.

[0072] Example 7

[0073] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 5 is that the transition metal oxide composite catalyst is a 15% WO3 / Pt@SSZ-13 catalyst, and the loading amount of WO3 is 15wt%;

[0074] In the preparation method, the addition amount of the WO3 nanoparticle solution is 168.75 mg, and the other preparation methods and parameters are consistent with Example 5.

[0075] Example 8

[0076] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 5 is that the transition metal oxide composite catalyst is a 20% WO3 / Pt@SSZ-13 catalyst, and the loading amount of WO3 is 20wt%;

[0077] In the preparation method, the addition amount of the WO3 nanoparticle solution is 225 mg, and the other preparation methods and parameters are consistent with those in Example 5.

[0078] Example 9

[0079] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the transition metal oxide composite catalyst is a 50% TiO2 / Pt@SSZ-13 catalyst, and the loading amount of TiO2 is 50wt%;

[0080] In the preparation method, the addition amount of the TiO2 nanoparticle solution is 250 mL, and the other preparation methods and parameters are consistent with Example 1.

[0081] Example 10

[0082] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the transition metal oxide composite catalyst is a 1% TiO2 / Pt@SSZ-13 catalyst, and the loading amount of TiO2 is 1wt%;

[0083] In the preparation method, the addition amount of the TiO2 nanoparticle solution is 5 mL, and the other preparation methods and parameters are consistent with Example 1.

[0084] Embodiment 11

[0085] This embodiment provides a transition metal oxide composite catalyst and a preparation method thereof. The difference between this embodiment and embodiment 5 is that the transition metal oxide composite catalyst is 5% V2O5 / Pt@SSZ-13, and the loading amount of V2O5 is 5wt%;

[0086] In the preparation method, 56.25 mg of ammonium paratungstate was replaced by 32.15 mg of ammonium metavanadate, and the remaining preparation methods and parameters were consistent with those in Example 5.

[0087] Comparative Example 1

[0088] The catalyst provided in this comparative example is Pt@SSZ-13 with a Pt loading of 0.25 wt %, that is, no transition metal oxide compounding is performed.

[0089] Comparative Example 2

[0090] This comparative example provides a Pt / SiO2 catalyst and a preparation method thereof, wherein the preparation method comprises the following steps:

[0091] 0.3 g of platinum nitrate solution (mass fraction of 16.76 wt%) was dispersed in 100 mL of water, and 2 g of SiO2 nanoparticles were added and stirred and dispersed for 4 h, then stirred and evaporated at 75°C, and then calcined at 550°C for 4 h to obtain the Pt / SiO2 catalyst.

[0092] Comparative Example 3

[0093] This comparative example provides a Pt / TiO2 catalyst and a preparation method thereof, wherein the preparation method comprises the following steps:

[0094] 0.3 g of platinum nitrate solution (mass fraction of 16.76 wt%) was dispersed in 100 mL of water, and 2 g of TiO2 nanoparticles were added and stirred and dispersed for 4 h, then stirred and evaporated at 75° C., and then calcined at 550° C. for 4 h to obtain the Pt / TiO2 catalyst.

[0095] Test Method

[0096] The transition metal oxide composite catalysts prepared in Examples 1 to 11 and the catalysts prepared in Comparative Examples 1 to 3 were evaluated for catalytic activity. The unpurified flue gas composition was: 7500ppmCO, 200ppmSO2, 15%O2, and the rest was N2. The total flow rate of the simulated flue gas was 50mL / min, and the reaction space velocity was 60000mL·h -1 ·g -1 The activity test results of each catalyst and the anti-SO2 performance data are shown in Table 1.

[0097] Figure 1 It is a comparison chart of the anti-SO2 stability of the 5% TiO2 / Pt@SSZ-13 catalyst of Example 1 of the present invention, the 5% WO3 / Pt@SSZ-13 of Example 5 and the 5% V2O5 / Pt@SSZ-13 catalyst of Example 11. It can be seen from the figure that under the low temperature condition of 240°C, with the increase of time, the 5% TiO2 / Pt@SSZ-13 and 5% WO3 / Pt@SSZ-13 catalysts have stronger resistance to SO2 poisoning and higher anti-SO2 stability, while the 5% V2O5 / Pt@SSZ-13 catalyst has weaker resistance to SO2 poisoning.

[0098] Table 1

[0099]

[0100]

[0101]

[0102]

[0103] The test results show that:

[0104] (1) It can be seen from Examples 1 to 4 that when the TiO2 loading is 5 to 20 wt%, the CO catalytic combustion activity of the catalyst is relatively high at low temperature conditions of 200°C and 225°C, both of which are above 99.5%. Furthermore, at 225°C, the anti-SO2 activity is also significantly improved, both of which are above 73.5%, and the CO catalytic combustion activity and the anti-SO2 activity are relatively high; It can be seen from Examples 5 to 8 that when the WO3 loading is 5 to 20 wt%, at 225°C, the CO catalytic combustion activity and the anti-SO2 activity are relatively high;

[0105] (2) It can be seen from Examples 1 and 9-10 that the TiO2 loading in Example 9 is too high, the CO catalytic combustion activity has no obvious improvement effect, and it will block the molecular sieve pores, resulting in a decrease in the catalyst's anti-SO2 activity; the TiO2 loading in Example 10 is too low, at a temperature of 200°C, its CO catalytic combustion activity and anti-SO2 activity are significantly reduced, and at a temperature of 225°C, the anti-SO2 activity is also significantly reduced;

[0106] (3) It can be seen from Examples 1 and 11 that when TiO2 is replaced with V2O5, due to the strong redox ability of V2O5 itself, a large amount of O2 is adsorbed on the outer surface, blocking the molecular sieve pores on the outer surface, and then at low temperatures of 200°C and 225°C, the CO catalytic combustion activity and anti-SO2 activity are significantly reduced, and the activity is relatively low;

[0107] (4) It can be seen from Example 1 and Comparative Example 1 that when the composite of transition metal oxide is omitted and only Pt@SSZ-13 is used as a catalyst, its CO catalytic combustion activity and anti-SO2 activity are significantly reduced at a temperature of 200°C, and the anti-SO2 activity is also significantly reduced at a temperature of 225°C;

[0108] (5) It can be seen from Example 1 and Comparative Examples 2 to 3 that in Comparative Example 2, Pt / SiO2 catalyst was used, and the CO catalytic combustion activity and anti-SO2 activity decreased significantly at low temperatures of 200°C and 225°C, and both activities were relatively low; in Comparative Example 3, Pt / TiO2 agent was used, and the anti-SO2 activity decreased significantly at low temperatures of 200°C and 225°C, which further indicates that the transition metal oxide composite catalyst of the present invention has an effect on CO catalytic combustion activity that is not inferior to Pt / TiO2, while also having a strong resistance to SO2 poisoning. By adopting the strategy of loading transition metal oxides, the CO catalytic combustion activity of the catalyst is enhanced by utilizing the oxygen reverse overflow process of the transition metal oxides, and the diffusion of SO2 is inhibited by utilizing the steric hindrance of the molecular sieve, thereby achieving the effect of complementary advantages.

[0109] In summary, the transition metal oxide composite catalyst prepared by the present invention by compounding transition metal oxide with precious metal @ molecular sieve has surface lattice oxygen that can participate in the catalytic combustion of CO, and thus has excellent catalytic combustion activity for CO. In addition, in the presence of a small amount of transition metal oxide, the structure of the precious metal @ molecular sieve is still kept intact, so that the transition metal oxide composite catalyst has high activity at low temperature and strong resistance to SO2 poisoning.

[0110] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A transition metal oxide composite catalyst, characterized in that: The transition metal oxide composite catalyst comprises a transition metal oxide and a carrier, wherein the carrier comprises a noble metal@molecular sieve, and the noble metal@molecular sieve comprises a molecular sieve and a noble metal dispersed inside the molecular sieve; Wherein, the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve.

2. The transition metal oxide composite catalyst according to claim 1, characterized in that Based on the mass of the carrier, the loading amount of the transition metal oxide is 2 to 20 wt%, preferably 5 to 10 wt%; Preferably, based on the mass of the noble metal@molecular sieve, the loading amount of the noble metal is 0.1-1 wt%, preferably 0.2-0.5 wt%.

3. The transition metal oxide composite catalyst according to claim 1 or 2, characterized in that: The transition metal oxide includes any one of Fe3O4, TiO2, MoO3, WO3, Co3O4 or CeO2 or a combination of at least two thereof, preferably any one of TiO2, MoO3 or WO3; Preferably, the particle size of the transition metal oxide is 3 to 20 nm, preferably 5 to 10 nm; Preferably, the noble metal includes any one of Pt, Pd, Ru, Rh, Ag, Au or Ir or a combination of at least two thereof, preferably any one of Pt, Ru or Ir.

4. The transition metal oxide composite catalyst according to any one of claims 1 to 3, characterized in that: The molecular sieve comprises CHA molecular sieve; Preferably, the CHA molecular sieve comprises any one of SSZ-13, SAPO-34, SAPO-47 or AIPO-34 or a combination of at least two thereof, preferably SSZ-13 or SAPO-34.

5. A method for preparing a transition metal oxide composite catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The transition metal oxide is prepared by using a transition metal oxide precursor, and then the transition metal oxide is impregnated and loaded on a carrier, or the transition metal oxide precursor is directly impregnated and loaded on a carrier, and then calcined to obtain the transition metal oxide composite catalyst; The noble metal@molecular sieve is composed of a molecular sieve and a noble metal dispersed inside the molecular sieve; and the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve.

6. The preparation method according to claim 5, characterized in that: The carrier is a noble metal@molecular sieve with a noble metal loading of 0.1 to 1 wt%; Preferably, the preparation method of the carrier comprises a one-pot hydrothermal method, an ion exchange method or a crystallization method, preferably a one-pot hydrothermal method.

7. The preparation method according to claim 5 or 6, characterized in that: The transition metal oxide precursor material includes any one of ferric nitrate, tetrabutyl titanate, cerium nitrate, cobalt nitrate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate, or a combination of at least two thereof, preferably any one of tetrabutyl titanate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate; Preferably, the calcination temperature is 300-600°C; Preferably, the calcination holding time is 2 to 6 hours.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The preparation method comprises the following steps: The transition metal oxide prepared from the transition metal oxide precursor, the solvent and the carrier are mixed and stirred for 2 to 6 hours, or the transition metal oxide precursor, the aqueous solution and the carrier are mixed and stirred for 2 to 6 hours, and ultrasonic dispersion is performed, and the mixture is stirred and evaporated to dryness at 50 to 100° C., and the evaporated product is calcined at 300 to 600° C. for 2 to 6 hours to obtain the transition metal oxide composite catalyst; Among them, the noble metal@molecular sieve is composed of a molecular sieve and a noble metal dispersed inside the molecular sieve; the transition metal oxide is dispersed on the surface of the molecular sieve and / or coated inside the molecular sieve; the carrier is a noble metal@molecular sieve with a noble metal loading of 0.1 to 1wt%; the preparation method of the carrier includes a one-pot hydrothermal method, an ion exchange method or a crystal transformation method; the transition metal oxide precursor includes any one of ferric nitrate, tetrabutyl titanate, cerium nitrate, cobalt nitrate, ammonium metamolybdate, ammonium paratungstate or ammonium metatungstate, or a combination of at least two of them; the solvent includes any one of n-propane, water, ethanol or acetone.

9. An application of a transition metal oxide composite catalyst, characterized in that: The transition metal oxide composite catalyst described in any one of claims 1 to 4, or the transition metal oxide composite catalyst prepared by the preparation method described in any one of claims 5 to 8, is applied to the removal of gaseous pollutants in mobile sources and / or fixed sources.

10. The use according to claim 9, characterized in that: The gaseous pollutants include CO gas containing SO2; Preferably, the removal temperature is 150-300°C, preferably 200-250°C.

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