A catalyst for the oxidation of co and a method for its preparation and use

Abstract

The present application relates to a kind of catalyst for CO oxidation and its preparation method and application, the preparation method includes the following steps: (1) mixing titanium source, silicon source and solvent, after calcination, Ti-Si composite is obtained;(2) the Ti-Si composite is etched, and TiO2 carrier is obtained;(3) the TiO2 carrier is activated, and the catalyst is obtained.The Ti-Si composite prepared by co-hydrolysis method combined with calcination process, combined with etching means and activation process, can obtain TiO2 carrier with (101) high-energy crystal face and abundant defect sites, the carrier prepared by this method itself has higher activity, has excellent catalytic effect, can effectively realize the complete conversion of CO, greatly reduces the cost input of catalyst.

Description

Technical Field

[0001] This invention relates to the technical field of catalysts, and more particularly to a catalyst for CO oxidation, its preparation method, and its application. Background Technology

[0002] In the steel production process, the sintering process emits the highest proportion of air pollutants, with NO emissions from the sintering process being the largest. x The total emissions of SO2, particulate matter, and CO pollutants account for more than half of the total pollutant emissions from the entire steel industry. With the implementation of ultra-low emission standards in the steel industry, the emissions of particulate matter, SO2, and NO in the sintering process are becoming increasingly significant. x Emissions of pollutants such as dioxins have been reduced by more than 80%.

[0003] Currently, the most effective method for purifying CO in flue gas is catalytic oxidation technology, the core of which lies in the development of catalysts. In particular, research on precious metal catalysts has attracted widespread attention due to their excellent catalytic activity and sulfur resistance.

[0004] Xiaole Weng et al. (DOI: 10.1002 / anie.202310191) prepared a Pd / TiO2 catalyst with unconventional oxygen saturation (Pd content ≈ 1 wt%) under an oxidizing atmosphere. This catalyst contains ultra-small Pd metal and support particles with special reactivity and stability. Under the conditions of 21 vol% O2, 100 ppm SO2 and 10 vol% water, the catalyst can stably and efficiently catalyze the oxidation of CO at 120 °C.

[0005] Hongliang Xin et al. (DOI: 10.1021 / jacs.2c08902) prepared Pt1 single-atom catalysts (Pt1), Pt atom monolayer (PtASL), and Pt multilayer cluster (PtC) catalysts with different local coordination environments using defective CeO2 / Al2O3 supports. All or some Pt ​​atoms were embedded in the CeO2 surface lattice, and the total content of surface-loaded Pt was 0.25 wt%, achieving catalytic oxidation of CO at 270 °C.

[0006] CN113751024B discloses a catalyst for the catalytic oxidation of CO and its preparation method. The invention uses a mixture of noble metals and non-noble metals as active components, and has high stability and activity above 110℃. The content of noble metals in its active components is 0.09~0.12wt%.

[0007] In all the studies mentioned above, the synthesized catalysts generally required a precious metal content greater than 0.1%. For example, a 0.1% precious metal content per cubic meter of catalyst would increase the cost by over 200,000 RMB, significantly increasing the operating costs of the steel industry. In short, current catalyst research generally suffers from excessively high precious metal costs, severely hindering the industrialization of catalysts.

[0008] Therefore, providing a method for preparing a catalyst that can achieve excellent catalytic oxidation performance while further reducing the cost of the catalyst is an urgent problem to be solved. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a catalyst for CO oxidation, its preparation method, and its application. The present invention utilizes a co-hydrolysis method combined with a calcination process to prepare a Ti-Si composite, which, when combined with etching and activation techniques, yields a TiO2 support with a (101) high-energy crystal plane and abundant defect sites. The support prepared by this method exhibits high activity and excellent catalytic performance, effectively achieving complete CO conversion and significantly reducing catalyst costs.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a catalyst, the method comprising the following steps:

[0012] (1) A Ti-Si composite was obtained by mixing a titanium source, a silicon source and a solvent and then calcining it.

[0013] (2) The Ti-Si composite was etched to obtain a TiO2 support;

[0014] (3) The TiO2 support is activated to obtain the catalyst.

[0015] This invention uses titanium and silicon sources as raw materials to perform a co-hydrolysis reaction in a solvent, followed by calcination to prepare a Ti-Si composite. Then, etching is used to remove silicon sites in the Ti-Si composite, resulting in a large number of defect sites. The abundant defect structure on the catalyst surface enhances the active oxygen transfer capacity. The calcination process in this invention promotes TiO2 growth towards the 101 plane, while the presence of SiO2 formed from the silicon source inhibits the transformation of TiO2 from the anatase to the rutile phase, ultimately yielding anatase-type TiO2 rich in the 101 high-energy crystal facet.

[0016] The present invention prepares a Ti-Si composite by co-hydrolysis combined with calcination process, and combines etching and activation processes to perform high-energy crystal plane orientation construction and defect synthesis on the support, thereby obtaining a TiO2 support with (101) high-energy crystal plane and abundant defect sites. The support prepared by this method has high activity and excellent catalytic effect, and can effectively realize the complete conversion of CO, greatly reducing the cost of catalyst.

[0017] As a further preferred technical solution of the present invention, the preparation method further includes loading single-atom Pt onto the TiO2 support in step (2).

[0018] Preferably, the specific process of loading the single-atom Pt includes: mixing the platinum source solution with the TiO2 support, drying and then calcining to obtain the TiO2 support loaded with single-atom Pt.

[0019] The preparation method used in this invention involves the directional construction of high-energy crystal planes on the support and defect synthesis, which enables the efficient utilization of single-atom Pt. Only ppm-level amounts of platinum are needed to obtain a catalyst with excellent catalytic effect, greatly reducing the cost of existing CO catalysts. At the same time, it can further reduce the temperature for complete CO conversion, effectively achieving complete catalytic oxidation of CO at 200-400℃.

[0020] Preferably, the platinum source in the platinum source solution includes any one or a combination of at least two of chloroplatinic acid, platinum nitrate, or platinum tetrachloride.

[0021] Preferably, the loading of the single-atom Pt is 0 to 100 ppm by weight percentage, excluding 0 ppm, for example, 1 ppm, 3 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm or 100 ppm, etc.

[0022] In one embodiment, the platinum source solution used in this invention is obtained by diluting a high-concentration platinum solution.

[0023] Preferably, during the loading process, the calcination temperature is 400~600℃, such as 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃.

[0024] In this invention, if the calcination temperature during the loading process is too low, Pt cannot exist in the form of a single atom; if the calcination temperature during the loading process is too high, TiO2 will change from anatase to rutile.

[0025] Preferably, during the loading process, the calcination time is 3 to 5 hours, such as 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours.

[0026] Preferably, the molar ratio of titanium in the titanium source to silicon in the silicon source in step (1) is (3~5):1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, etc.

[0027] Preferably, the titanium source in step (1) includes any one or a combination of at least two of tetrabutyl titanate, titanium tetrachloride, or tetraethyl titanate.

[0028] Preferably, the silicon source in step (1) includes any one or a combination of at least two of tetraethyl silicate, polyethoxysiloxane, or methyltrimethoxysilane.

[0029] Preferably, the specific steps of mixing in step (1) include: mixing the titanium source and the silicon source in the first step, and then adding a solvent for the second mixing.

[0030] This invention does not impose specific limitations on the mixing method, which includes, but is not limited to, manual stirring, magnetic stirring, or ball milling, and those skilled in the art can choose according to their needs.

[0031] Preferably, the first mixing time is 0.5 to 2 hours, for example, 0.5 hours, 0.8 hours, 1.1 hours, 1.4 hours, 1.7 hours or 2 hours.

[0032] Preferably, the second mixing time is 9 to 15 hours, such as 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours.

[0033] Preferably, the mixture obtained in step (1) is dried before roasting.

[0034] Preferably, the drying temperature is 100~140℃, such as 100℃, 110℃, 120℃, 130℃ or 150℃.

[0035] Preferably, the drying time is 1 to 3 hours, such as 1 hour, 2 hours, or 3 hours.

[0036] Preferably, the roasting temperature in step (1) is 500~800℃, for example 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃.

[0037] Preferably, the roasting time in step (1) is 2 to 5 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0038] Preferably, the etching agent used in step (2) includes any one or a combination of at least two of sodium hydroxide solution, potassium hydroxide solution or ammonia water.

[0039] Preferably, the concentration of the etchant is 0.5~3 mol / L, such as 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0040] Preferably, the etching temperature in step (2) is 40~60℃, such as 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃ or 60℃.

[0041] Optionally, the etching in step (2) of the present invention is performed under water bath conditions.

[0042] Preferably, the etching time in step (2) is 9 to 15 hours, such as 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours.

[0043] Preferably, step (2) further includes the steps of separating, washing and drying the etched product.

[0044] This invention does not impose specific limitations on the separation method, which includes, but is not limited to, centrifugation, filtration, or vacuum filtration, and those skilled in the art can choose according to their needs.

[0045] The present invention does not specifically limit the washing reagents, which include, but are not limited to, deionized water or ethanol, and those skilled in the art can choose them as needed.

[0046] Preferably, the activation temperature in step (3) is 300~500℃, such as 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃ or 500℃.

[0047] Preferably, the activation time in step (3) is 0.2 to 1 hour, for example, 0.2 hours, 0.3 hours, 0.4 hours, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours or 1 hour.

[0048] Preferably, the gas used for activation in step (3) includes any one or a combination of at least two of hydrogen, oxygen or carbon monoxide.

[0049] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0050] (1) The titanium source and the silicon source are first mixed according to the molar ratio of titanium to silicon (3~5):1, and the mixing time is 0.5~2h. Then, the solvent is added for the second mixing, and the mixing time is 9~15h. After drying, the mixture is calcined at 500~800℃ for 2~5h to obtain the Ti-Si composite.

[0051] (2) The Ti-Si composite is etched with an etchant of 0.5~3 mol / L at a temperature of 40~60℃. The etchant includes any one or at least two of sodium hydroxide solution, potassium hydroxide solution or ammonia water. The etching time is 9~15h. After separation, washing and drying, TiO2 support is obtained.

[0052] (3) The platinum source solution is mixed with the TiO2 support, dried, and calcined at 400~600℃ for 3~5h to obtain a TiO2 support loaded with single-atom Pt, wherein the loading amount of single-atom Pt is 0~100ppm and does not include 0ppm. Then, the TiO2 support loaded with single-atom Pt is activated at 300~500℃ for 0.2~1h. The gas used for activation includes any one or at least two combinations of hydrogen, oxygen or carbon monoxide to obtain the catalyst.

[0053] In a second aspect, the present invention provides a catalyst prepared by the preparation method described in the first aspect, wherein the catalyst comprises a TiO2 support.

[0054] The TiO2 support prepared by this invention has a (101) high-energy crystal plane and abundant defect sites, and has high activity itself. It has excellent catalytic effect and can effectively achieve complete CO conversion, greatly reducing the cost of catalyst.

[0055] Preferably, the catalyst further includes single-atom Pt supported on the TiO2 support.

[0056] Preferably, the loading of the single-atom Pt is 0 to 100 ppm by weight percentage, excluding 0 ppm, for example, 1 ppm, 3 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm or 100 ppm, etc.

[0057] The catalyst support supported by Pt in this invention has a (101) high-energy crystal plane and abundant defect sites, which can improve the interaction between the TiO2 support and single-atom Pt, achieving excellent catalytic effect at an ultra-low loading of ppm level, greatly reducing the cost of existing CO catalysts, and further reducing the temperature for complete CO conversion.

[0058] Thirdly, the present invention provides an application of the catalyst as described in the second aspect, said catalyst being used for CO catalytic oxidation treatment.

[0059] Compared with the prior art, the present invention has at least the following beneficial effects:

[0060] (1) The Ti-Si composite prepared by the co-hydrolysis method combined with the calcination process of the present invention, combined with etching and activation process, can obtain TiO2 support with (101) high-energy crystal plane and abundant defect sites. The support prepared by this method has high activity and excellent catalytic effect, which can effectively realize the complete conversion of CO and greatly reduce the cost of catalyst.

[0061] (2) The preparation method adopted in this invention can achieve efficient utilization of single-atom Pt by directional construction of high-energy crystal planes and defect synthesis of the support. Only ppm level of platinum element needs to be added to obtain a catalyst with excellent catalytic effect, which greatly reduces the cost of existing CO catalysts. At the same time, it can further reduce the temperature of complete CO conversion and effectively achieve complete catalytic oxidation of CO under 200-400℃ conditions.

[0062] (3) The required loading and types of catalysts in this invention are much lower than those in the prior art, thus achieving the preparation of catalysts with low cost. At the same time, the catalysts prepared can effectively achieve complete catalytic oxidation of CO, with a CO conversion efficiency of 100%, and can reduce the temperature of complete CO conversion. The temperature of complete CO conversion using this catalyst is below 400°C. Attached Figure Description

[0063] Figure 1These are XRD data images of the TiO2 supports prepared by the methods described in Examples 1, 2, 3, and 4.

[0064] Figure 2 These are the CO catalytic oxidation efficiency curves for Examples 1, 5-7, and Comparative Example 5.

[0065] Figure 3 This is a flowchart of the catalyst preparation method described in Example 5 of the present invention. Detailed Implementation

[0066] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely 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 is determined by the claims.

[0067] Example 1

[0068] This embodiment provides a method for preparing a catalyst, the method comprising the following steps:

[0069] (1) Weigh 42.61g of tetrabutyl titanate and 5.216g of tetraethyl silicate according to the molar ratio of titanium to silicon of 5:1, mix and stir for 0.5h, add deionized water and hydrolyze for 12h, dry the hydrolyzed product at 120℃ for 2h, place it in a muffle furnace and calcine at 800℃ for 4h to obtain Ti-Si composite.

[0070] (2) The obtained Ti-Si composite was etched in a 2 mol / L NaOH solution at a water bath temperature of 50℃ for 12 h. The etched product was separated, washed with water until neutral, and dried to obtain TiO2 support.

[0071] (3) The TiO2 support was activated under oxygen conditions at 400℃ for 0.5h to finally obtain an unloaded catalyst.

[0072] Example 2

[0073] The only difference between this embodiment and Embodiment 1 is that the calcination temperature in step (1) of this embodiment is 700°C. All other aspects are the same as in Embodiment 1.

[0074] Example 3

[0075] The only difference between this embodiment and Embodiment 1 is that the calcination temperature in step (1) of this embodiment is 600°C. All other aspects are the same as in Embodiment 1.

[0076] Example 4

[0077] The only difference between this embodiment and Embodiment 1 is that the calcination temperature in step (1) of this embodiment is 500°C. All other aspects are the same as in Embodiment 1.

[0078] Example 5

[0079] This preparation example provides a method for preparing a catalyst, the flowchart of which is shown below. Figure 3 The preparation method includes the following steps:

[0080] (1) Weigh 42.61g of titanium tetrachloride and 5.216g of polyethoxysiloxane according to the molar ratio of titanium to silicon of 5:1, mix and stir for 0.5h, add deionized water and hydrolyze for 12h, dry the hydrolyzed product at 120℃ for 2h, place it in a muffle furnace and calcine at 800℃ for 4h to obtain Ti-Si composite.

[0081] (2) The obtained Ti-Si composite was etched in a 2 mol / L potassium hydroxide solution at a water bath temperature of 50 °C for 12 h. The etched product was separated, washed with water until neutral, and dried to obtain TiO2 support.

[0082] (3) Dilute 8wt% chloroplatinic acid solution by 1000 times, weigh 0.2626g of the diluted solution and mix it with 10g of TiO2 support for 1h, then dry it. Place the dried sample in a muffle furnace and calcine it at 500℃ for 4h to obtain TiO2 support with single atom Pt loaded with 1ppm single atom Pt. Then, activate the TiO2 support loaded with single atom Pt at 400℃ under oxygen conditions for 0.5h to finally obtain a catalyst with 1ppm single atom Pt loaded on TiO2 support.

[0083] Example 6

[0084] This preparation example provides a method for preparing a catalyst, the method comprising the following steps:

[0085] (1) Weigh tetraethyl titanate and methyltrimethoxysilane according to a molar ratio of titanium to silicon of 3:1, mix and stir for 1 h, add deionized water and hydrolyze for 9 h, dry the hydrolyzed product at 140 °C for 1 h, place it in a muffle furnace and calcine at 600 °C for 2 h to obtain Ti-Si composite.

[0086] (2) The obtained Ti-Si composite was etched in a 3 mol / L NaOH solution in a water bath at 40°C for 14 h. The etched product was separated, washed with water until neutral, and dried to obtain TiO2 support.

[0087] (3) Dilute 8wt% chloroplatinic acid solution by 1000 times, weigh 2.626g of the diluted solution and mix it with 10g of TiO2 support for 1h, then dry it. Place the dried sample in a muffle furnace and calcine it at 400℃ for 5h to obtain TiO2 support with single-atom Pt loading of 10ppm. Then, activate the TiO2 support with single-atom Pt at 500℃ under oxygen conditions for 0.5h to finally obtain a catalyst with 10ppm single-atom Pt loaded on the TiO2 support.

[0088] Example 7

[0089] This preparation example provides a method for preparing a catalyst, the method comprising the following steps:

[0090] (1) Weigh tetrabutyl titanate and tetraethyl silicate according to a molar ratio of titanium to silicon of 4:1, mix and stir for 2 hours, add deionized water and hydrolyze for 14 hours, dry the hydrolyzed product at 100°C for 3 hours, place it in a muffle furnace and calcine at 500°C for 5 hours to obtain Ti-Si composite.

[0091] (2) The obtained Ti-Si composite was etched in a 1 mol / L NaOH solution in a water bath at 60°C for 10 h. The etched product was separated, washed with water until neutral, and dried to obtain TiO2 support.

[0092] (3) Dilute 8wt% chloroplatinic acid solution by 100 times, weigh 2.626g of the diluted solution and mix it with 10g of TiO2 support for 1h, then dry it. Place the dried sample in a muffle furnace and calcine it at 600℃ for 3h to obtain TiO2 support with single-atom Pt loading of 100ppm. Then, activate the TiO2 support with single-atom Pt at 300℃ under oxygen conditions for 0.5h to finally obtain a catalyst with 100ppm single-atom Pt loaded on the TiO2 support.

[0093] Example 8

[0094] The only difference between this embodiment and Example 6 is that the single-atom Pt loading in step (3) of this embodiment is 110 ppm. Correspondingly, in step (3), 8 wt% chloroplatinic acid solution is diluted 100 times, 2.889 g of diluted solution is weighed and mixed with 10 g of TiO2 support for 1 h and then dried. The rest is the same as in Example 6.

[0095] Example 9

[0096] The only difference between this embodiment and Example 6 is that the single-atom Pt loading in step (3) of this embodiment is 150 ppm. Correspondingly, in step (3), 8 wt% chloroplatinic acid solution is diluted 100 times, 3.939 g of diluted solution is weighed and mixed with 10 g of TiO2 support for 1 h and then dried. The rest is the same as in Example 6.

[0097] Example 10

[0098] The only difference between this embodiment and Example 6 is that the single-atom Pt loading in step (3) of this embodiment is 200 ppm. Correspondingly, in step (3), the 8 wt% chloroplatinic acid solution is diluted 100 times, and 5.252 g of the diluted solution is weighed and mixed with 10 g of TiO2 support for 1 h before drying. The rest is the same as in Example 6.

[0099] Example 11

[0100] The only difference between this embodiment and Example 6 is that the calcination temperature in step (1) of this embodiment is 400°C. All other aspects are the same as in Example 6.

[0101] Example 12

[0102] The only difference between this embodiment and Embodiment 6 is that the calcination temperature in step (1) of this embodiment is 900°C. All other aspects are the same as in Embodiment 6.

[0103] Example 13

[0104] The only difference between this embodiment and Example 6 is that the concentration of the NaOH solution in step (2) of this embodiment is 0.1 mol / L. Everything else is the same as in Example 6.

[0105] Example 14

[0106] The only difference between this embodiment and Example 6 is that the concentration of the NaOH solution in step (2) of this embodiment is 4 mol / L. Everything else is the same as in Example 6.

[0107] Comparative Example 1

[0108] The only difference between this comparative example and Example 5 is that the silicon source in step (1) is omitted, that is, tetraethyl silicate is not added to the raw materials in step (1), and all etching processes in step (2) are omitted. The TiO2 support is prepared directly by hydrolyzing and calcining titanium source as raw material. All other aspects are the same as in Example 5.

[0109] Comparative Example 2

[0110] The only difference between this comparative example and Example 5 is that the etching process in step (2) is omitted, and the Ti-Si composite is directly activated to obtain a TiO2-SiO2 support for Pt loading. All other aspects are the same as in Example 5.

[0111] Comparative Example 3

[0112] The only difference between this comparative example and Example 5 is that steps (1) and (2) are omitted, and Pt is loaded directly using a commercially available TiO2 support. All other aspects are the same as in Example 5.

[0113] Comparative Example 4

[0114] The only difference between this comparative example and Example 5 is that the activation process in step (3) is omitted. Everything else is the same as in Example 5.

[0115] Comparative Example 5

[0116] The only difference between this comparative example and Example 5 is that commercial TiO2 was used and the active component Pt was not loaded.

[0117] The TiO2 catalysts provided in the examples and comparative examples were used to conduct experiments on the catalytic oxidation effect of CO. The experimental instruments used were a fixed-bed gas chromatograph coupled experimental platform and an infrared analysis experimental platform.

[0118] The method for the CO catalytic oxidation effect experiment was as follows: 0.2 g of the catalyst samples obtained in Examples 1-14 and Comparative Examples 1-5 were loaded into a self-made quartz reaction apparatus, with a CO concentration of 10000 ppm, an O2 concentration of 16%, and a space velocity of 60000 h⁻¹. -1 CO catalytic oxidation experiments were conducted under experimental conditions with a flue gas flow rate of 200 ml / L. The catalyst performance was further tested using an infrared platform. The CO removal rate at temperatures below 400℃ and the CO conversion temperature corresponding to achieving the removal rate were recorded. The performance test results are shown in Table 1.

[0119] Table 1

[0120]

[0121] The test results show that:

[0122] (1) As can be seen from Examples 1 to 4, the Ti-Si composite prepared by the present invention through co-hydrolysis combined with calcination process, combined with etching and activation process, can obtain TiO2 support with (101) high-energy crystal plane and abundant defect sites. The support prepared by this method has high activity and excellent catalytic effect, and can effectively realize the complete conversion of CO, greatly reducing the cost of catalyst.

[0123] Figure 1 The XRD data of the TiO2 supports prepared by the preparation methods in Examples 1, 2, 3 and 4 show that TiO2 still maintains the anatase crystal form after high-temperature calcination. As the temperature increases, the strength of the 101 crystal plane in anatase TiO2 increases.

[0124] (2) As can be seen from Examples 5 to 7, the preparation method of the present invention achieves efficient utilization of single-atom Pt by directional construction of high-energy crystal planes of the support and defect synthesis. Only ppm level of platinum element needs to be added to obtain a catalyst with better catalytic effect. It can effectively achieve complete catalytic oxidation of CO under 200-400℃ conditions, which greatly reduces the cost of existing CO catalysts.

[0125] Depend on Figure 2 The CO catalytic oxidation efficiency curves of catalysts with different single-atom Pt loadings prepared by the preparation methods provided in Examples 1 and 5-7 show that when the Pt loading is 1-100 ppm, complete CO catalysis can be achieved in the range of 200-300℃.

[0126] (3) By comparing Examples 6 and Examples 8-10, it can be seen that even if the single-atom Pt loading in the catalyst is further increased, the cost is greatly increased, but the temperature of complete CO conversion is only slightly reduced. Therefore, it can be seen that the Pt-based catalyst with a loading of ppm level prepared by the present invention reduces the cost input while ensuring the catalytic effect of the catalyst.

[0127] (4) By comparing Example 6 with Examples 11-12, it can be seen that if the calcination temperature of the Ti-Si composite prepared in this invention is too low or too high, the catalytic performance of the catalyst will decrease, thereby increasing the temperature required for a CO removal rate of 100%.

[0128] (5) By comparing Example 6 with Examples 13-14, it can be seen that if the concentration of the etching agent used in this invention is too high or too low, the catalytic activity of the obtained catalyst will be weakened, resulting in an increase in the temperature corresponding to a CO removal rate of 100%.

[0129] (6) By comparing Example 5 with Comparative Example 1, it can be seen that the absence of tetraethyl silicate in step (1) will lead to a decrease in catalyst activity, which will result in the inability to achieve a 100% removal rate of CO in the temperature range below 400°C.

[0130] (7) By comparing Example 5 with Comparative Example 2, it can be seen that the etching process in step (2) is omitted in this invention, and the Ti-Si composite is directly activated to obtain TiO2-SiO2 support. When single-atom Pt is loaded on TiO2-SiO2 support, the catalyst activity is reduced, and the removal rate is still low at a temperature of 400℃.

[0131] (8) By comparing Example 5 with Comparative Example 3, it can be seen that if commercially available TiO2 support is used directly, the catalyst activity will be reduced.

[0132] (9) By comparing Example 5 with Comparative Example 4, it can be seen that if the TiO2 support with single-atom Pt is not activated, the catalyst activity will decrease.

[0133] (10) By comparing Example 5 with Comparative Example 5, it can be seen that if commercial TiO2 support is directly used as catalyst in this invention, the catalyst activity is extremely poor and the CO removal rate is extremely low at a temperature of 400℃.

[0134] Depend on Figure 2 The CO catalytic oxidation efficiency curves of Examples 1, 5-7 and Comparative Example 5 clearly show that the catalyst provided in the comparative example has extremely poor catalytic performance.

[0135] In summary, this invention, through a co-hydrolysis method combined with a calcination process to prepare a Ti-Si composite, and by combining etching and activation techniques, yields a TiO2 support with a (101) high-energy crystal facet and abundant defect sites. The support prepared by this method exhibits high activity and excellent catalytic performance, effectively achieving complete CO conversion and significantly reducing catalyst costs. Furthermore, the preparation method employed in this invention utilizes the directional construction of the high-energy crystal facet and defect synthesis to achieve efficient utilization of single-atom Pt. Only ppm-level amounts of platinum are needed to obtain a catalyst with superior catalytic performance, lowering the temperature required for complete CO catalytic oxidation. This effectively achieves complete CO catalytic oxidation at 200-400℃, greatly reducing the cost of existing CO catalysts.

[0136] The applicant declares that the above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that, The preparation method includes the following steps: (1) A Ti-Si composite was obtained by mixing a titanium source, a silicon source and a solvent and then calcining it. (2) The Ti-Si composite was etched to obtain a TiO2 support; (3) The platinum source solution is mixed with the TiO2 support, dried and calcined to obtain a TiO2 support loaded with single-atom Pt. Then, the TiO2 support loaded with single-atom Pt is activated at 300~500℃ for 0.2~1h. The gas used for activation includes any one or at least two of hydrogen, oxygen or carbon monoxide to obtain the catalyst.

2. The method for preparing the catalyst according to claim 1, characterized in that, The platinum source in the platinum source solution includes any one or a combination of at least two of chloroplatinic acid, platinum nitrate, or platinum tetrachloride.

3. The method for preparing the catalyst according to claim 1, characterized in that, The loading of the single-atom Pt is 0 to 100 ppm by weight percentage, excluding 0 ppm.

4. The method for preparing the catalyst according to claim 1, characterized in that, During the loading process, the calcination temperature in step (3) is 400~600℃.

5. The method for preparing the catalyst according to claim 1, characterized in that, During the loading process, the calcination time in step (3) is 3~5h.

6. The method for preparing the catalyst according to claim 1, characterized in that, In step (1), the molar ratio of titanium in the titanium source to silicon in the silicon source is (3~5):

1.

7. The method for preparing the catalyst according to claim 1, characterized in that, The titanium source in step (1) includes any one or a combination of at least two of tetrabutyl titanate, titanium tetrachloride, or tetraethyl titanate.

8. The method for preparing the catalyst according to claim 1, characterized in that, The silicon source in step (1) includes any one or a combination of at least two of tetraethyl silicate, polyethoxysiloxane, or methyltrimethoxysilane.

9. The method for preparing the catalyst according to claim 1, characterized in that, The specific steps of mixing in step (1) include: mixing the titanium source and the silicon source in the first step, and then adding a solvent for the second step.

10. The method for preparing the catalyst according to claim 9, characterized in that, The first mixing time is 0.5~2h.

11. The method for preparing the catalyst according to claim 9, characterized in that, The second mixing time is 9-15 hours.

12. The method for preparing the catalyst according to claim 1, characterized in that, Before roasting in step (1), the mixture obtained by mixing is also dried.

13. The method for preparing the catalyst according to claim 1, characterized in that, The roasting temperature in step (1) is 500~800℃.

14. The method for preparing the catalyst according to claim 1, characterized in that, The roasting time in step (1) is 2 to 5 hours.

15. The method for preparing the catalyst according to claim 1, characterized in that, The etching agent used in step (2) includes any one or a combination of at least two of sodium hydroxide solution, potassium hydroxide solution or ammonia water.

16. The method for preparing the catalyst according to claim 15, characterized in that, The concentration of the etching agent is 0.5~3 mol / L.

17. The method for preparing the catalyst according to claim 1, characterized in that, The etching temperature in step (2) is 40~60℃.

18. The method for preparing the catalyst according to claim 1, characterized in that, The etching time in step (2) is 9~15h.

19. The method for preparing the catalyst according to claim 1, characterized in that, Step (2) also includes the steps of separating, washing and drying the etched product.

20. The method for preparing the catalyst according to claim 1, characterized in that, The preparation method includes the following steps: (1) The titanium source and the silicon source are first mixed according to the molar ratio of titanium to silicon (3~5):1, and the mixing time is 0.5~2h. Then, the solvent is added for the second mixing, and the mixing time is 9~15h. After drying, the mixture is calcined at 500~800℃ for 2~5h to obtain the Ti-Si composite. (2) The Ti-Si composite is etched with an etchant of 0.5~3 mol / L at a temperature of 40~60℃. The etchant includes any one or at least two of sodium hydroxide solution, potassium hydroxide solution or ammonia water. The etching time is 9~15h. After separation, washing and drying, TiO2 support is obtained. (3) The platinum source solution is mixed with the TiO2 support, dried, and calcined at 400~600℃ for 3~5h to obtain a TiO2 support loaded with single-atom Pt, wherein the loading amount of single-atom Pt is 0~100ppm and does not include 0ppm. Then, the TiO2 support loaded with single-atom Pt is activated at 300~500℃ for 0.2~1h. The gas used for activation includes any one or at least two combinations of hydrogen, oxygen or carbon monoxide to obtain the catalyst.

21. A catalyst prepared by the method according to any one of claims 1-20, wherein the catalyst comprises a TiO2 support.

22. The catalyst according to claim 21, characterized in that, The catalyst also includes single-atom Pt supported on the TiO2 support.

23. The catalyst according to claim 22, characterized in that, The loading of the single-atom Pt is 0 to 100 ppm by weight percentage, excluding 0 ppm.

24. The application of a catalyst according to any one of claims 21-23, characterized in that, The catalyst is used for the catalytic oxidation of CO.

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