A TiO2 and molecular sieve composite support for Pt catalyst, its preparation and its application in CO oxidation reaction.

Abstract

The present application relates to a TiO2 and molecular sieve composite carrier loaded Pt catalyst, preparation and application thereof in CO oxidation reaction, and belongs to the technical field of industrial catalysis. The preparation process of the catalyst mainly includes: preparing a molecular sieve gel, adding TiO2 powder into the molecular sieve gel for sufficient mixing, and then performing hydrothermal reaction to obtain a TiO2-molecular sieve composite material. Then, the obtained composite material is calcined at high temperature to remove a template agent, and then ammonium exchange treatment is performed to obtain an ammonium type TiO2-molecular sieve composite powder. Finally, a Pt precursor solution is mixed with the composite carrier by using an impregnation method, and then drying and high temperature calcination are performed to prepare a Pt / TiO2-molecular sieve composite catalyst. The catalyst shows excellent activity and sulfur poisoning resistance in the CO catalytic oxidation reaction, and is suitable for application scenarios such as mobile source and industrial tail gas treatment.

Description

Technical Field

[0001] This invention relates to the field of industrial catalysis technology, and more specifically, to Pt catalysts supported on TiO2 and molecular sieve composite supports, their preparation, and their application in CO oxidation reactions. Background Technology

[0002] Carbon monoxide (CO) is a common air pollutant, primarily originating from the incomplete combustion of fossil fuels, vehicle exhaust emissions, and industrial waste gas emissions, particularly in energy-intensive industries. Therefore, reducing CO emissions has become an urgent environmental governance task. Catalytic oxidation technology, as an effective means of CO emission reduction, has attracted widespread attention. This technology uses a catalyst to efficiently convert CO into harmless carbon dioxide (CO2), thereby purifying the air. The selection and design of the catalyst are crucial to this technology. Pt / TiO2 catalysts have become a focus of research due to their excellent CO catalytic oxidation performance. However, the flue gas composition in vehicle exhaust and industrial waste gas is complex, with SO2 causing catalyst deactivation, posing a significant challenge to the CO oxidation reaction. Deactivation of Pt / TiO2 catalysts typically occurs because SO2 can be adsorbed and oxidized at Pt sites, subsequently transferring to the TiO2 support to form sulfates, which block the catalyst pores and hinder the interaction between –OH and CO. Therefore, improving the SO2 poisoning resistance of Pt / TiO2 catalysts is of great significance. Summary of the Invention

[0003] To address the limitations of existing technologies, this invention proposes a method for preparing a Pt catalyst supported on a TiO2 / molecular sieve composite support. This method is simple, easily repeatable, and exhibits good consistency. The Pt / TiO2-molecular sieve catalyst prepared by this method demonstrates excellent CO catalytic oxidation performance and superior resistance to sulfur poisoning, making it suitable for both mobile and stationary CO catalytic oxidation.

[0004] According to a first aspect of the present invention, a method for preparing a Pt catalyst supported on a TiO2 and molecular sieve composite support is provided, comprising the following steps:

[0005] (1) Dissolve the inorganic base in deionized water, add the aluminum source, and mix thoroughly; then add the silicon source, and then add the template agent to obtain the molecular sieve gel; add TiO2 powder to the molecular sieve gel, and then carry out a hydrothermal reaction.

[0006] (2) After the hydrothermal reaction is completed, the solid product is cooled and separated, washed with water to remove impurities and dried; then calcined to remove the template agent to obtain a composite support of TiO2 and molecular sieve; the composite support of TiO2 and molecular sieve is subjected to ammonium exchange to obtain an ammonium-type composite support of TiO2 and molecular sieve.

[0007] (3) The ammonium-type TiO2 and molecular sieve composite support obtained in step (2) is immersed in a platinum precursor solution, then dried and calcined to obtain a Pt catalyst supported on the TiO2 and molecular sieve composite support.

[0008] Preferably, in step (1), the inorganic base is lithium hydroxide, sodium hydroxide, or potassium hydroxide;

[0009] The aluminum source is sodium aluminate, aluminum nitrate, boehmite, or boehmite.

[0010] The silicon source is tetraethoxysilane, silica sol, tetraethyl orthosilicate, or sodium silicate.

[0011] The template agents used are N,N,N-trimethyl-1-adamantyl ammonium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium chloride, N,N-dimethyl-2,6-dimethylpiperidinium hydroxide, N,N-dimethyl-3,5-dimethylpiperidinium iodide, tetrapropylammonium hydroxide, or tetrapropylammonium bromide.

[0012] Preferably, the molecular sieve gel is SSZ-13, SSZ-39, or BEA molecular sieve gel.

[0013] Preferably, in step (2), the calcination temperature is 400-700°C, and the ammonium salt used for ammonium exchange is ammonium bicarbonate, ammonium bisulfate, or ammonium acetate.

[0014] Preferably, in step (3), the calcination temperature is 400-700°C, and the platinum precursor is chloroplatinic acid, platinum nitrate, or dichlorodiammineplatinum;

[0015] The calcination atmosphere in step (3) is carbon monoxide, ammonia, nitrogen, oxygen or air.

[0016] According to another aspect of the present invention, a Pt catalyst supported on a TiO2 and molecular sieve composite support is provided.

[0017] Preferably, the loading of the active component Pt in the Pt catalyst supported by the TiO2 and molecular sieve composite support is 0.4 wt.% to 4 wt.%, and the mass ratio of TiO2 to molecular sieve in the support is 0.5 to 5.

[0018] According to another aspect of the present invention, the application of the TiO2 and molecular sieve composite support-supported Pt catalyst in the catalytic oxidation reaction of CO is provided.

[0019] According to another aspect of the present invention, a CO catalytic oxidizer is provided, comprising a Pt catalyst supported on a TiO2 and molecular sieve composite support.

[0020] According to another aspect of the present invention, a system for treating exhaust gases from mobile or stationary sources is provided, including the aforementioned CO catalytic oxidizer.

[0021] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0022] (1) This invention proposes a method for preparing a Pt / TiO2-molecular sieve catalyst. This method is simple to operate, easy to repeat, and has good controllability and consistency, aiming to optimize the catalytic oxidation performance of CO. Compared with traditional Pt / TiO2 catalysts (T... 90 Compared to 218℃, the T values ​​of the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, and Pt / TiO2-BEA catalysts provided by this invention are significantly higher. 90 The temperatures were 198℃, 191℃, and 208℃, respectively. After introducing SO2 into the reaction atmosphere, the T values ​​of the Pt / TiO2, Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, and Pt / TiO2-BEA catalysts were [not specified]. 90 Increasing the temperature to 269℃, 227℃, 218℃, and 239℃ respectively indicates that the CO catalytic oxidation activity of all catalysts decreased in the presence of SO2. The Pt / TiO2 catalyst showed the most significant activity decrease. In contrast, the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, and Pt / TiO2-BEA catalysts exhibited relatively smaller decreases in CO catalytic oxidation performance, demonstrating superior resistance to sulfur poisoning. This indicates that the TiO2-molecular sieve composite support can significantly improve the CO catalytic oxidation activity and sulfur resistance of the Pt / TiO2 catalyst. The Pt / TiO2-molecular sieve catalyst of this invention, with its higher CO oxidation activity and sulfur poisoning resistance, is particularly suitable for tail gas purification treatment from both mobile and stationary sources, providing a more advantageous solution for practical applications.

[0023] (2) Using molecular sieves and TiO2 composites as a support for Pt enables more uniform dispersion of Pt nanoparticles within the molecular sieve, thereby reducing Pt particle agglomeration and enhancing catalyst activity. This is because molecular sieves possess abundant micropores and mesopores; this highly ordered pore system increases the specific surface area of ​​the catalyst and provides more exposed active sites. Furthermore, the presence of numerous acidic sites in the molecular sieve promotes CO adsorption and activation, contributing to improved CO conversion efficiency. TiO2 itself is an excellent oxidation support, providing lattice oxygen in CO catalytic oxidation. However, the composite of molecular sieves and TiO2 further enhances the redox performance of the support, improving oxygen migration and supply. The unique environment within the molecular sieve pores further promotes oxygen activation and transfer, making it easier for reactive oxygen species to generate and participate in the reaction, thus improving the overall CO catalytic oxidation efficiency of the catalyst. Regarding sulfur poisoning resistance, the composite support of TiO2 and molecular sieves, with its more acidic sites and unique pore structure, effectively restricts the binding of SO2 and Pt. Furthermore, the acidic sites of the molecular sieve can interact with SO2, weakening the interaction between SO2 and Pt particles, thereby alleviating sulfur poisoning of the catalyst. More importantly, the TiO2 and molecular sieve composite support can form a unique interfacial structure, enhancing electron transfer between Pt and the support and optimizing the electronic state of Pt, thus improving its sulfur resistance. These mechanisms work together to give the modified catalyst superior catalytic performance and stability in complex atmospheres, making it suitable for a wide range of practical applications. Attached Figure Description

[0024] Figure 1 X-ray diffraction (XRD) patterns of the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, Pt / TiO2-BEA and Pt / TiO2 catalysts prepared in Examples 1-3 and Comparative Example 1.

[0025] Figure 2 The graph shows the CO catalytic oxidation conversion rates of the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, Pt / TiO2-BEA, and Pt / TiO2 catalysts prepared in Examples 1-3 and Comparative Example 1.

[0026] Figure 3 The graph shows the CO catalytic oxidation conversion rates of the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, Pt / TiO2-BEA and Pt / TiO2 catalysts prepared in Examples 1-3 and Comparative Example 1 in the presence of 200 ppm SO2. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In a first aspect, the present invention provides a method for preparing a Pt catalyst supported on a TiO2 and molecular sieve composite support, comprising the following steps:

[0029] (1) Dissolve the titanium source in an appropriate amount of anhydrous ethanol or isopropanol, and stir at 30–80°C for 0.5–3 hours to ensure complete dissolution. During stirring, add an appropriate amount of deionized water dropwise, controlling the reaction temperature and the rate of water addition. The entire water addition process should continue for 1–3 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 6–24 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 70–100°C for 12 hours to obtain TiO2 powder.

[0030] (2) Dissolve the inorganic base in deionized water and stir at room temperature for 2–15 minutes. Then, add the aluminum source and continue stirring for 5–30 minutes to ensure that the aluminum source is uniformly dispersed in the solution. Next, slowly add the silicon source and stir for 1–3 hours. Then, add the template agent and continue stirring for 0.5–3 hours to obtain the molecular sieve gel. On this basis, slowly add the pre-prepared TiO2 powder to the molecular sieve gel and stir for 0.5–4 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-molecular sieve gel in a hydrothermal reactor and carry out a hydrothermal reaction at 120–200℃ for 1–7 days.

[0031] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 70-100℃ for 12 hours, and then calcined at 400-700℃ for 2-8 hours to remove the template agent and other organic residues, finally obtaining the TiO2-molecular sieve composite material. The obtained TiO2-molecular sieve composite powder is subjected to ammonium exchange using ammonium bicarbonate, ammonium bisulfate or ammonium acetate to obtain ammonium-type TiO2-molecular sieve composite powder.

[0032] (4) Dissolve Pt salt in distilled water and stir at 30–80°C for 0.5–2 hours. Immerse the ammonium-type TiO2-molecular sieve composite support in the platinum precursor solution and stir for 1–5 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 70–100°C for 12 hours and calcine it at 400–700°C for 2–8 hours in a special atmosphere to finally obtain the Pt / TiO2-molecular sieve composite support catalyst.

[0033] Preferably, the titanium source in step (1) is tetrabutyl titanate, isopropyl titanate, tetraethyl titanate, or titanium tetrachloride.

[0034] Preferably, the inorganic base in step (2) is lithium hydroxide, sodium hydroxide, or potassium hydroxide. The aluminum source is sodium aluminate, aluminum nitrate, USY molecular sieve, BEA molecular sieve, boehmite, or boehmite. The silicon source is tetraethoxysilane, silica sol, tetraethyl orthosilicate, or sodium silicate. The template agent used is N,N,N-trimethyl-1-adamantyl ammonium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium chloride, N,N-dimethyl-2,6-dimethylpiperidinium hydroxide, N,N-dimethyl-3,5-dimethylpiperidinium iodide, tetrapropylammonium hydroxide, or tetrapropylammonium bromide. The molecular sieve gel is SSZ-13, SSZ-39, or BEA molecular sieve gel.

[0035] Preferably, the calcination temperature in step (3) is 400-700°C, and the ammonium salt used for ammonium exchange is ammonium bicarbonate, ammonium bisulfate, or ammonium acetate.

[0036] Preferably, the Pt salt in step (4) is chloroplatinic acid, platinum nitrate, or dichlorodiammineplatinum. The calcination temperature is 400–700°C, and the special atmosphere is carbon monoxide, ammonia, nitrogen, oxygen, or air.

[0037] In some embodiments, the titanium source used in step (1) is tetrabutyl titanate, isopropyl titanate, tetraethyl titanate or titanium tetrachloride.

[0038] In some embodiments, the inorganic base used in step (2) is lithium hydroxide, sodium hydroxide, or potassium hydroxide. The aluminum source used is sodium aluminate, aluminum nitrate, USY molecular sieve, BEA molecular sieve, boehmite, or boehmite. The silicon source used is tetraethoxysilane, silica sol, tetraethyl orthosilicate, or sodium silicate. The template agent used is N,N,N-trimethyl-1-adamantyl ammonium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium chloride, N,N-dimethyl-2,6-dimethylpiperidinium hydroxide, N,N-dimethyl-3,5-dimethylpiperidinium iodide, tetrapropylammonium hydroxide, or tetrapropylammonium bromide. The resulting molecular sieve gel is SSZ-13, SSZ-39, or BEA molecular sieve gel.

[0039] In some embodiments, the calcination temperature used in step (3) is 400–700°C, and the ammonium salt used for ammonium exchange is ammonium bicarbonate, ammonium bisulfate, or ammonium acetate.

[0040] In some embodiments, the Pt salt used in step (4) is chloroplatinic acid, platinum nitrate, or dichlorodiammineplatinum. The calcination temperature is 400–700°C, and the calcination atmosphere is carbon monoxide, ammonia, nitrogen, oxygen, or air.

[0041] In a second aspect, the present invention provides a Pt / TiO2-molecular sieve catalyst for the catalytic oxidation of CO, comprising an active component and a support; wherein the active component is a Pt species, and the support is a TiO2 and SSZ-13, SSZ-39 or BEA molecular sieve complex.

[0042] In some embodiments, the loading of the active component Pt in the support is 0.4 wt.% to 4 wt.%, more preferably 0.8 wt.%. The mass ratio of TiO2 to molecular sieve in the support is 0.5 to 5, more preferably 2.

[0043] In a third aspect, the present invention provides a CO catalytic oxidizer comprising the above-described Pt / TiO2-molecular sieve catalyst.

[0044] In a fourth aspect, the present invention provides a mobile source and a stationary source exhaust gas treatment system comprising the above-described CO catalytic oxidizer.

[0045] The following are specific embodiments.

[0046] Example 1

[0047] A method for preparing a Pt / TiO2-SSZ-13 catalyst includes the following steps:

[0048] (1) Dissolve 16.86 g of tetrabutyl titanate in 50 mL of anhydrous ethanol and stir at 50 °C for 2 hours to ensure complete dissolution. During stirring, add 50 mL of deionized water dropwise, maintaining the reaction temperature at 50 °C and controlling the water addition rate. The entire water addition process lasts for 2 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 10 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 80 °C for 12 hours to obtain TiO2 powder.

[0049] (2) Dissolve 0.5g of sodium hydroxide in deionized water and stir for 5 minutes at room temperature. Then, add 1g of aluminum nitrate and continue stirring for 15 minutes. Next, slowly add 6g of silica sol and stir for 2 hours. Then, add 5g of N,N,N-trimethyl-1-adamantyl ammonium chloride and continue stirring for 1 hour to obtain SSZ-13 molecular sieve gel. Based on this, slowly add pre-prepared TiO2 powder to the SSZ-13 gel and stir for 2 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-SSZ-13 gel in a hydrothermal reactor and carry out a hydrothermal reaction at 140℃ for 6 days.

[0050] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 80°C for 12 hours, and then calcined at 500°C for 4 hours to remove the template agent and other organic residues, finally obtaining the TiO2-SSZ-13 composite material. The obtained TiO2-SSZ-13 composite powder is subjected to ammonium exchange with 1M ammonium bicarbonate to obtain ammonium-type TiO2-SSZ-13 composite powder.

[0051] (4) Dissolve 0.12 g of chloroplatinic acid in distilled water and stir at 60 °C for 1 hour. Immerse the ammonium-type TiO2-SSZ-13 composite support in the chloroplatinic acid solution and stir for 5 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 70 °C for 12 hours and calcine it at 500 °C for 4 hours in a CO atmosphere to finally obtain a Pt / TiO2-SSZ-13 composite support catalyst with a Pt content of 0.8 wt.%.

[0052] Comparative Example 1

[0053] A method for preparing a Pt / TiO2 catalyst includes the following steps:

[0054] (1) Dissolve 25.29 g of tetrabutyl titanate in 50 mL of anhydrous ethanol and stir at 50 °C for 2 hours to ensure complete dissolution. During stirring, add 50 mL of deionized water dropwise, maintaining the reaction temperature at 50 °C and controlling the water addition rate. The entire water addition process lasts for 2 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 10 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 80 °C for 12 hours to obtain TiO2 powder. Perform ammonium exchange on the obtained TiO2 powder using 1 M ammonium bicarbonate to obtain ammonium-type TiO2 powder.

[0055] (2) Dissolve 0.12 g of chloroplatinic acid in distilled water and stir at 60 °C for 1 hour. Immerse the ammonium-type TiO2 support in the chloroplatinic acid solution and stir for 5 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 70 °C for 12 hours and calcine it at 500 °C for 4 hours in a CO atmosphere to finally obtain a Pt / TiO2 catalyst with a Pt content of 0.8 wt.%.

[0056] Example 2

[0057] A method for preparing a Pt / TiO2-SSZ-39 catalyst includes the following steps:

[0058] (1) Dissolve 14.09 g of isopropyl titanate in 50 mL of anhydrous ethanol and stir at 60 °C for 1.5 hours to ensure complete dissolution. During stirring, add 50 mL of deionized water dropwise, maintaining the reaction temperature at 60 °C and controlling the water addition rate. The entire water addition process lasts for 2 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 12 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 90 °C for 12 hours to obtain TiO2 powder.

[0059] (2) Dissolve 0.8 g of lithium hydroxide in deionized water and stir for 6 minutes at room temperature. Then, add 2 g of BEA molecular sieve and continue stirring for 30 minutes. Next, slowly add 6.5 g of sodium silicate and stir for 2 hours. Then, add 6 g of N,N-dimethyl-2,6-dimethylpiperidinium hydroxide and continue stirring for 1.5 hours to obtain SSZ-39 molecular sieve gel. Based on this, slowly add pre-prepared TiO2 powder to the SSZ-39 gel and stir for 2.5 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-SSZ-39 gel in a hydrothermal reactor and carry out a hydrothermal reaction at 200℃ for 2 days.

[0060] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 90°C for 12 hours, and then calcined at 550°C for 3 hours to remove the template agent and other organic residues, finally obtaining the TiO2-SSZ-39 composite material. The obtained TiO2-SSZ-39 composite powder is subjected to ammonium exchange with 1M ammonium bisulfate to obtain ammonium-type TiO2-SSZ-39 composite powder.

[0061] (4) Dissolve 0.12 g of chloroplatinic acid in distilled water and stir at 70 °C for 1 hour. Immerse the ammonium-type TiO2-SSZ-39 composite support in the chloroplatinic acid solution and stir for 4 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 90 °C for 12 hours and calcine it at 550 °C for 3 hours in an ammonia atmosphere to finally obtain a Pt / TiO2-SSZ-39 composite support catalyst with a Pt content of 0.8 wt.%.

[0062] Example 3

[0063] A method for preparing a Pt / TiO2-BEA catalyst includes the following steps:

[0064] (1) Dissolve 12.31 g of tetraethyl titanate in 60 mL of isopropanol and stir at 70 °C for 1.5 hours to ensure complete dissolution. During stirring, add 60 mL of deionized water dropwise, maintaining the reaction temperature at 70 °C and controlling the water addition rate. The entire water addition process lasts for 1 hour to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 20 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 100 °C for 12 hours to obtain TiO2 powder.

[0065] (2) Dissolve 1.4 g of potassium hydroxide in deionized water and stir for 15 minutes at room temperature. Then, add 8 g of boehmite and continue stirring for 25 minutes. Next, slowly add 8 g of tetraethoxysilane and stir for 2 hours. Then, add 10 g of tetrapropylammonium bromide and continue stirring for 1.5 hours to obtain BEA molecular sieve gel. Based on this, slowly add pre-prepared TiO2 powder to the BEA molecular sieve gel and stir for 3 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-BEA gel in a hydrothermal reactor and carry out a hydrothermal reaction at 120°C for 5 days.

[0066] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 80°C for 12 hours, and then calcined at 600°C for 5 hours to remove the template agent and other organic residues, finally obtaining the TiO2-BEA composite material. The obtained TiO2-BEA composite powder is subjected to ammonium exchange with 1M ammonium acetate to obtain ammonium-type TiO2-BEA composite powder.

[0067] (4) Dissolve 0.20 g of platinum nitrate in distilled water and stir at 50 °C for 2 hours. Immerse the ammonium-type TiO2-BEA composite support in the platinum nitrate solution and stir for 3 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 80 °C for 12 hours and calcine it at 600 °C for 5 hours in a nitrogen atmosphere to finally obtain a Pt / TiO2-BEA composite support catalyst with a Pt content of 1.0 wt.%.

[0068] XRD tests were performed on the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, Pt / TiO2-BEA, and Pt / TiO2 catalysts prepared in Examples 1-3 and Comparative Example 1. The results are as follows: Figure 1As shown, Pt / TiO2-SSZ-13 exhibits typical structures of anatase TiO2 and CHA-type molecular sieves; Pt / TiO2-SSZ-39 displays typical structures of anatase TiO2 and AEI molecular sieves; while Pt / TiO2-BEA shows typical structural characteristics of anatase TiO2 and BEA-type molecular sieves. Pt / TiO2 also exhibits diffraction peaks characteristic of anatase TiO2.

[0069] Examples 4-7

[0070] The preparation method of Pt / TiO2-SSZ-39 catalysts with different Pt loadings includes the following steps:

[0071] (1) Dissolve 13.47 g of tetraethyl titanate in 60 mL of isopropanol and stir at 80 °C for 3 hours to ensure complete dissolution. During stirring, add 60 mL of deionized water dropwise, maintaining the reaction temperature at 80 °C and controlling the water addition rate. The entire water addition process lasts for 3 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 20 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 100 °C for 12 hours to obtain TiO2 powder.

[0072] (2) Dissolve 1.0 g of sodium hydroxide in deionized water and stir for 15 minutes at room temperature. Then, add 3 g of USY molecular sieve and continue stirring for 30 minutes. Next, slowly add 8 g of tetraethyl orthosilicate and stir for 3 hours. Then, add 12 g of N,N-dimethyl-3,5-dimethylpiperidinium iodide and continue stirring for another 3 hours to obtain SSZ-39 molecular sieve gel. Based on this, slowly add pre-prepared TiO2 powder to the SSZ-39 gel and stir for 4 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-SSZ-39 gel in a hydrothermal reactor and carry out a hydrothermal reaction at 190℃ for 3 days.

[0073] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 100°C for 12 hours, and then calcined at 700°C for 5 hours to remove the template agent and other organic residues, finally obtaining the TiO2-SSZ-39 composite material. The obtained TiO2-SSZ-39 composite powder is subjected to ammonium exchange with 1M ammonium acetate to obtain ammonium-type TiO2-SSZ-39 composite powder.

[0074] (4) Dissolve 0.045 g, 0.09 g, 0.135 g, or 0.179 g of diammonium chloride platinum in distilled water and stir at 80 °C for 2 hours. Immerse the ammonium-type TiO2-SSZ-39 composite support into the diammonium chloride platinum solution and stir for 5 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 100 °C for 12 hours and calcine it at 700 °C for 5 hours in air atmosphere to finally obtain Pt / TiO2-SSZ-39 composite support catalysts with Pt contents of 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, and 2.0 wt.%.

[0075] Examples 8-11

[0076] The preparation method of Pt / TiO2-SSZ-13 catalysts with different mass ratios of TiO2 and SSZ-13 molecular sieves includes the following steps:

[0077] (1) Dissolve 16.86 g, 25.3 g, 30.35 g, or 33.73 g of tetraethyl titanate in 70 mL of anhydrous ethanol and stir at 40 °C for 1 hour to ensure complete dissolution. During stirring, add 70 mL of deionized water dropwise, maintaining the reaction temperature at 40 °C and controlling the water addition rate. The entire water addition process should continue for 1 hour to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 6 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 70 °C for 12 hours to obtain TiO2 powder.

[0078] (2) Dissolve 1.5g of sodium hydroxide in deionized water and stir for 3 minutes at room temperature. Then, add 0.5g of sodium aluminate and continue stirring for 5 minutes. Next, slowly add 15g of tetraethoxysilane and stir for 1 hour. Then, add 10g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and continue stirring for 1.5 hours to obtain SSZ-13 molecular sieve gel. Based on this, slowly add the pre-prepared TiO2 powder to the SSZ-13 gel and stir for 1 hour to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-SSZ-13 gel in a hydrothermal reactor and carry out a hydrothermal reaction at 170℃ for 3 days.

[0079] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 70°C for 12 hours, and then calcined at 400°C for 6 hours to remove the template agent and other organic residues, finally obtaining the TiO2-SSZ-13 composite material. The obtained TiO2-SSZ-13 composite powder is subjected to ammonium exchange with 1M ammonium bisulfate to obtain ammonium-type TiO2-SSZ-13 composite powder.

[0080] (4) Dissolve 0.24 g of platinum nitrate in distilled water and stir at 40 °C for 1 hour. Immerse the ammonium-type TiO2-SSZ-13 composite support in the platinum nitrate solution and stir for 3 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 70 °C for 12 hours and calcine it at 400 °C for 6 hours in an oxygen atmosphere to finally obtain a Pt / TiO2-SSZ-13 composite support catalyst with a TiO2 to SSZ-13 molecular sieve mass ratio of 0.5, 1, 1.5 or 2 and a Pt content of 1.2 wt.%.

[0081] Examples 12-15

[0082] The preparation methods of Pt / TiO2-BEA catalysts prepared from different titanium sources include the following steps:

[0083] (1) Dissolve 17.54 g tetraethyl titanate, 14.65 g isopropyl titanate, 11.75 g tetraethyl titanate or 9.77 g titanium tetrachloride in 80 mL of isopropanol and stir at 60 °C for 2 hours to ensure complete dissolution. During stirring, add 80 mL of deionized water dropwise, maintaining the reaction temperature at 60 °C and controlling the water addition rate. The entire water addition process should continue for 2 hours to ensure slow hydrolysis. After hydrolysis, allow the resulting sol to stand for 20 hours to promote aging and the formation of a stable TiO2 sol. Dry the TiO2 sol at 90 °C for 12 hours to obtain TiO2 powder.

[0084] (2) Dissolve 1.7g of sodium hydroxide in deionized water and stir for 7 minutes at room temperature. Then, add 7g of boehmite and continue stirring for 12 minutes. Next, slowly add 10g of silica sol and stir for 2 hours. Then, add 17g of tetrapropylammonium hydroxide and continue stirring for 2.5 hours to obtain BEA molecular sieve gel. Based on this, slowly add pre-prepared TiO2 powder to the BEA molecular sieve gel and stir for 3.5 hours to ensure that the composite material is fully mixed. Finally, place the uniformly mixed TiO2-BEA gel in a hydrothermal reactor and carry out a hydrothermal reaction at 160℃ for 4 days.

[0085] (3) After the hydrothermal reaction is completed, the solid product is cooled and separated, and impurities are removed by multiple water washings. The washed product is dried at 80°C for 12 hours, and then calcined at 650°C for 4 hours to remove the template agent and other organic residues, finally obtaining the TiO2-BEA composite material. The obtained TiO2-BEA composite powder is subjected to ammonium exchange with 1M ammonium bisulfate to obtain ammonium-type TiO2-BEA composite powder.

[0086] (4) Dissolve 0.21 g of diammonium dichloroplatinum in distilled water and stir at 30 °C for 2 hours. Immerse the ammonium-type TiO2-BEA composite support into the diammonium dichloroplatinum solution and stir for 3 hours to ensure that the Pt precursor is fully adsorbed onto the support. Then dry the mixed slurry at 80 °C for 12 hours and calcine it at 650 °C for 4 hours in a carbon monoxide atmosphere to finally obtain a Pt / TiO2-BEA composite support catalyst with a Pt content of 2.0 wt.%.

[0087] Example 16

[0088] The CO catalytic oxidation performance and sulfur resistance of the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, Pt / TiO2-BEA, and Pt / TiO2 catalysts prepared in Examples 1-3 and Comparative Example 1 were tested. The test conditions were: catalyst dosage 0.2 g (60-80 mesh), simulated flue gas composition of 1000 ppm CO, 15% H2O, 10% O2, and 200 ppm SO2 (introduced if necessary), and reaction space velocity of 150,000 h⁻¹. -1 .

[0089] The results of CO catalytic oxidation performance test and sulfur resistance performance test are as follows: Figure 2 and Figure 3 As shown. By Figure 2 It is evident that the Pt / TiO2-molecular sieve catalyst exhibits higher CO catalytic oxidation performance compared to the Pt / TiO2 catalyst. This is because molecular sieves possess abundant microporous and mesoporous structures. This highly ordered pore system increases the specific surface area of ​​the catalyst, resulting in more uniform dispersion of Pt nanoparticles within the molecular sieve, thereby reducing Pt particle agglomeration and enhancing catalyst activity. Furthermore, the presence of numerous acidic sites in the molecular sieve promotes CO adsorption and activation. The composite of molecular sieve and TiO2 further enhances the redox performance of the support, improving oxygen migration and supply, which contributes to increasing the catalyst's CO conversion rate. The introduction of SO2 into the reaction atmosphere led to a decrease in CO catalytic oxidation activity in all catalysts. The Pt / TiO2 catalyst showed the most significant decrease in activity. In contrast, the Pt / TiO2-SSZ-13, Pt / TiO2-SSZ-39, and Pt / TiO2-BEA catalysts exhibited relatively smaller decreases in CO catalytic oxidation performance, demonstrating superior resistance to sulfur poisoning. This is because the composite support of TiO2 and molecular sieves, with its more acidic sites and unique pore structure, can effectively limit the binding of SO2 and Pt, reducing the deposition of sulfur species on the catalyst surface and the poisoning of active sites. Molecular sieves can also act as sacrificial sites to adsorb SO2, protecting active species from sulfur poisoning to some extent, thereby improving the catalyst's resistance to sulfur poisoning.

[0090] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Pt catalyst supported on a TiO2 and molecular sieve composite support, characterized in that, Includes the following steps: (1) Dissolve the inorganic base in deionized water, add the aluminum source, and mix thoroughly; then add the silicon source, and then add the template agent to obtain the molecular sieve gel; add TiO2 powder to the molecular sieve gel, and then carry out a hydrothermal reaction; the template agent used is N,N,N-trimethyl-1-adamantyl ammonium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium chloride, N,N-dimethyl-2,6-dimethylpiperidinium hydroxide or N,N-dimethyl-3,5-dimethylpiperidinium iodide; the molecular sieve gel is SSZ-13 or SSZ-39 molecular sieve gel; (2) After the hydrothermal reaction is completed, the solid product is cooled and separated, washed with water to remove impurities and then dried; then calcined to remove the template agent to obtain a composite support of TiO2 and molecular sieve; the composite support of TiO2 and molecular sieve is subjected to ammonium exchange to obtain an ammonium-type composite support of TiO2 and molecular sieve. (3) The ammonium-type TiO2 and molecular sieve composite support obtained in step (2) is immersed in a platinum precursor solution, then dried and calcined to obtain a Pt catalyst supported on the TiO2 and molecular sieve composite support.

2. The method for preparing the Pt catalyst supported on the TiO2 and molecular sieve composite support as described in claim 1, characterized in that, In step (1), the inorganic base is lithium hydroxide, sodium hydroxide, or potassium hydroxide; The aluminum source is sodium aluminate, aluminum nitrate, boehmite, or boehmite. The silicon source is tetraethoxysilane, silica sol, or sodium silicate.

3. The method for preparing the Pt catalyst supported on the TiO2 and molecular sieve composite support as described in claim 1, characterized in that, In step (2), the calcination temperature is 400~700 ℃, and the ammonium salt used for ammonium exchange is ammonium bicarbonate, ammonium bisulfate or ammonium acetate.

4. The method for preparing the Pt catalyst supported on the TiO2 and molecular sieve composite support as described in claim 1, characterized in that, In step (3), the calcination temperature is 400~700 ℃, and the platinum precursor is chloroplatinic acid, platinum nitrate or dichlorodiammineplatinum; The calcination atmosphere described in step (3) is carbon monoxide, ammonia, nitrogen, oxygen or air.

5. The TiO2 and molecular sieve composite support for Pt catalyst prepared by any one of claims 1-4.

6. The Pt catalyst supported on a TiO2 and molecular sieve composite support as described in claim 5, characterized in that, The loading of active component Pt in the TiO2 and molecular sieve composite support for the Pt catalyst is 0.4 wt.% to 4 wt.%, and the mass ratio of TiO2 to molecular sieve in the support is 0.5 to 5.

7. The application of the TiO2 and molecular sieve composite support for Pt catalyst in CO catalytic oxidation reaction as described in claim 5 or 6.

8. A CO catalytic oxidizer, characterized in that, The catalyst includes the Pt catalyst supported on the TiO2 and molecular sieve composite support as described in claim 5 or 6.

9. A system for treating exhaust gases from mobile or stationary sources, characterized in that, Includes the CO catalytic oxidizer as described in claim 8.

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