SnO2 nano material as well as preparation method and application thereof

Abstract

The invention provides a SnO2 nano material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a tin source with a solvent and a conditioning agent in sequence to obtain a precursor solution, then carrying out hydrothermal crystallization treatment on the precursor solution, and carrying out first calcination on the obtained solid product to obtain the SnO2 nano material. According to the preparation method, the SnO2 nano material is prepared through the hydrothermal synthesis method, the SnO2 morphology is regulated and controlled through the tin source, the regulator and the technological process, the prepared SnO2 material has the three-dimensional nano flower-shaped morphology, the size is uniform, the crystallinity is high, the preparation condition is mild, and the yield is high; when the catalyst is used as a carrier of a CO oxidation catalyst, the catalytic performance and the long-period stability of the catalyst can be improved through metal-carrier interaction.

Description

Technical Field

[0001] This invention belongs to the field of carbon monoxide catalytic oxidation technology, and relates to a SnO2 nanomaterial, its preparation method and application. Background Technology

[0002] With the advancement of science and technology and the continuous progress of global industrialization and modernization, environmental pollution has become a major concern. Carbon monoxide (CO), a primary gaseous pollutant produced by the incomplete combustion of carbon-containing substances, is widely present in vehicle exhaust, industrial emissions, and indoor coal combustion. Therefore, developing efficient CO removal technologies is of urgent practical significance. Among various treatment methods, catalytic oxidation technology is considered the most promising solution due to its ability to completely convert CO into non-toxic CO2 under relatively mild conditions. The core of this technology lies in the development of high-performance catalysts.

[0003] Currently, catalyst systems for CO oxidation mainly fall into two categories: noble metals and non-noble metals. Although non-noble metal catalysts based on transition metal oxides have a cost advantage, their low-temperature activity and stability often fail to meet the demanding requirements of practical applications. In contrast, supported noble metal catalysts, represented by platinum (Pt), palladium (Pd), and gold (Au), have always been the irreplaceable core technology in this field due to their superior low-temperature catalytic activity. In supported noble metal catalysts, performance largely depends on the structure and properties of the metal support surface and interface. The support is far from an inert supporting component; it provides a high specific surface area to disperse and stabilize metal nanoparticles, modulates the electronic state of the active center through unique metal-support interaction (SMSI), and even directly participates in the catalytic cycle, thus having a decisive influence on the overall performance.

[0004] Among numerous candidate support materials, tin dioxide (SnO2), as an n-type semiconductor metal oxide, exhibits unique potential. Its tunable acid-base and redox properties, along with its ability to form strong interactions with noble metals (such as Pd), are considered to effectively optimize the adsorption-desorption behavior of reactants and intermediates, weaken the CO poisoning effect, and thus enhance oxidation reaction kinetics. However, SnO2 materials prepared by traditional synthesis methods (such as co-precipitation and conventional sol-gel methods) generally suffer from inherent defects such as poor controllability of product morphology and size, and poor crystallinity. These structural limitations severely restrict the effective dispersion of noble metals and limit the full realization of the metal-support synergistic effect, resulting in catalyst performance that fails to meet theoretical expectations, with significant room for improvement in its low-temperature activity and long-term stability.

[0005] Therefore, developing a novel preparation method that can precisely control the microstructure (such as morphology, grain size, crystal faces and defects) of SnO2 supports is key to unlocking their superior catalytic support potential. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a SnO2 nanomaterial, its preparation method, and its applications. This invention prepares SnO2 nanomaterials via hydrothermal synthesis, and controls the morphology of SnO2 through the use of a tin source, regulators, and process control. The resulting SnO2 material exhibits a three-dimensional nanoflower-like morphology, uniform size, and high crystallinity. Furthermore, the preparation conditions are mild and the yield is high, making it suitable for large-scale production. When used as a support for CO oxidation catalysts, the metal-support interaction enhances the catalyst's catalytic performance and long-term stability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing SnO2 nanomaterials, the method comprising:

[0009] The tin source is mixed sequentially with a solvent and a modifier to obtain a precursor solution. The precursor solution is then subjected to hydrothermal crystallization treatment, and the resulting solid product is subjected to a first calcination to obtain the SnO2 nanomaterial.

[0010] In this invention, calcination plays a crucial role in the morphology and structure of the material. On the one hand, calcination can remove organic matter that may remain during the hydrothermal process, improving product purity. On the other hand, calcination, under certain high-temperature treatment, can eliminate internal stress in the material and enhance crystallinity. Ultimately, calcination enhances the structural and thermal stability of the material, ensuring its stable and efficient use as a support for the synthesis of supported noble metal catalysts.

[0011] Furthermore, in this invention, the tin source must be mixed with the solvent and the regulator in sequence to first form a uniform and stable tin source solution. The hydrolysis process of tin ions is carried out when the regulator is added. If all of them are directly mixed in, it will lead to insufficient dissolution of the tin source solid, non-uniform tin source state, inconsistent degree of hydrolysis and other complex situations, resulting in disordered and inconsistent morphology of the products after the hydrothermal reaction.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0013] Preferably, the tin source comprises a soluble tin salt, wherein the soluble tin salt comprises tin tetrachloride pentahydrate.

[0014] Preferably, the solvent includes water and / or ethanol, and more preferably water and ethanol.

[0015] Preferably, when the solvent is water and ethanol, the volume ratio of water to ethanol is 1:(1~2.5), such as 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2 or 1:2.5, etc.

[0016] In this invention, the type of solvent affects the morphology and structure of the product, ultimately influencing the material's properties. Ethanol plays two roles: 1. Regulating the crystallization growth process: It can slow down the crystallization rate and inhibit excessively rapid crystal growth, promoting the formation of a regular and uniform morphology; 2. Controlling the morphology: It induces anisotropic growth. Therefore, the absence of ethanol or insufficient ethanol addition may lead to particle agglomeration, while excessive ethanol may significantly alter the reaction pathway and chemical environment, causing the reaction to proceed in the wrong direction and preventing the synthesis of the product. By controlling the ethanol content within the preferred range of this invention, it is more beneficial to obtain materials with uniform morphology and excellent performance.

[0017] Preferably, the regulator comprises any one or a combination of at least two of NaOH aqueous solution, KOH aqueous solution or TMAH aqueous solution, and more preferably TMAH (tetramethylammonium hydroxide) aqueous solution.

[0018] In this invention, different types of regulators produce different effects, but all can synthesize SnO2 with regular and uniform morphology. Under the same conditions, SnO2 synthesized using TMAH aqueous solution as a regulator exhibits the best CO oxidation performance when used as a support for CO oxidation catalyst.

[0019] Preferably, the concentration of the regulator is 0.5 mol / L to 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.

[0020] Preferably, the process of mixing the tin source with the solvent and the regulator in sequence includes: mixing the tin source and the solvent to obtain a tin source solution, and then adding the regulator dropwise to the tin source solution.

[0021] Preferably, the dripping rate is 5 mL / min to 15 mL / min, for example, 5 mL / min, 7 mL / min, 10 mL / min, 13 mL / min or 15 mL / min.

[0022] In this invention, the regulator needs to be added dropwise at a constant flow rate to avoid the reaction being too rapid and to facilitate the formation of a uniform and regular morphology.

[0023] Preferably, the temperature of the hydrothermal crystallization treatment is 120℃~250℃, such as 120℃, 150℃, 170℃, 200℃, 220℃ or 250℃, and the time is 6h~48h, such as 6h, 10h, 15h, 20h, 25h, 30h, 35h, 40h or 48h.

[0024] Preferably, the product after hydrothermal crystallization is subjected to centrifugation, washing, and drying in sequence to obtain the solid product.

[0025] Preferably, the temperature of the first calcination is 500℃~1000℃, such as 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃, and the time is 2h~12h, such as 2h, 4h, 6h, 8h, 10h or 12h.

[0026] In this invention, controlling the temperature and time of the first calcination within the aforementioned preferred range is more conducive to obtaining pure and stable SnO2. If the temperature is too low, some organic pollutants or impurities cannot be effectively removed, which will affect the impregnation and loading process and thus affect the activity; while if the temperature is too high, it will destroy the regularity of the morphology.

[0027] In a second aspect, the present invention provides a SnO2 nanomaterial, which is prepared by the preparation method described in the first aspect.

[0028] Preferably, the SnO2 nanomaterial has a three-dimensional nanoflower-like morphology.

[0029] Preferably, the average size of the SnO2 nanomaterial is 200nm~500nm, such as 200nm, 250nm, 300nm, 350nm, 380nm, 400nm, 420nm, 450nm, 480nm or 500nm.

[0030] Thirdly, the present invention provides a CO oxidation catalyst, the CO oxidation catalyst comprising a support and Pd supported on the support, wherein the support is the SnO2 nanomaterial described in the second aspect.

[0031] The CO oxidation catalyst provided by this invention exhibits excellent CO catalytic oxidation activity and stability due to the synergistic effect of Pd and SnO2 supports.

[0032] Preferably, the loading amount of Pd on the carrier is 0.05wt.% to 5wt.%, for example, 0.05wt.%, 0.1wt.%, 0.5wt.%, 1wt.%, 2wt.%, 3wt.%, 4wt.% or 5wt.%.

[0033] Fourthly, the present invention provides a method for preparing the CO oxidation catalyst as described in the third aspect, the method comprising: impregnating the SnO2 nanomaterial described in the second aspect in an aqueous solution of palladium salt, and after the impregnation is completed, subjecting the impregnated product to a second calcination to obtain the CO oxidation catalyst.

[0034] Preferably, after the impregnation is completed, the product is dried to obtain the impregnated product.

[0035] Preferably, the palladium salt comprises palladium nitrate, and more preferably tetraaminopalladium nitrate.

[0036] Preferably, the second calcination temperature is 500℃~1000℃, such as 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃, and the time is 2h~12h, such as 2h, 4h, 6h, 8h, 10h or 12h.

[0037] Fifthly, the present invention also provides the application of the CO oxidation catalyst as described in the third aspect in the CO catalytic oxidation reaction.

[0038] Preferably, the atmosphere used in the application is an oxygen-rich atmosphere, wherein the volume concentration ratio of O2 to CO in the oxygen-rich atmosphere is >5.

[0039] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This invention, through creative improvements to the CO oxidation catalyst support itself, fundamentally stimulates the synergistic catalytic effect between the noble metal and the support, thereby enhancing catalytic activity and stability. Furthermore, the synthesis method provided by this invention is simple, convenient, and environmentally friendly, offering a highly efficient and reliable novel catalyst solution for addressing CO pollution, possessing significant industrial application value and market potential. Attached Figure Description

[0042] Figure 1 This is a SEM image of the SnO2 nanomaterials prepared in Example 6.

[0043] Figure 2 This is the XRD pattern of the SnO2 nanomaterial prepared in Example 6.

[0044] Figure 3 These are performance test graphs of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 for CO catalytic oxidation.

[0045] Figure 4 These are performance test graphs of the catalysts prepared in Examples 3 and 5-9 for CO catalytic oxidation. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0048] Example 1

[0049] This embodiment provides a SnO2 nanomaterial and a 1wt.%Pd / SnO2 catalyst.

[0050] The preparation method is as follows:

[0051] 1. Preparation of SnO2 nanomaterials: 3.5 mmol of tin chloride pentahydrate (IV) was dissolved in 10 mL of deionized water. 40 mL of a 1 mol / L NaOH solution was added as a regulator at a constant flow rate of 10 mL / min. After stirring evenly, a precursor solution was prepared and transferred to a hydrothermal reactor. The reactor was hydrothermally heated at 200 °C for 12 h. After the reaction was completed and cooled to room temperature, the precipitate was collected by centrifugation, washed repeatedly with water and ethanol, and then dried in an oven. The precipitate was then calcined at 600 °C for 3 h in air at a heating rate of 2 °C / min to obtain the SnO2 nanomaterials, denoted as SnO2-1.0N(W), which was prepared using a 1 mol / L NaOH solution as a regulator and water as the solvent.

[0052] 2. Preparation method of 1wt.%Pd / SnO2 catalyst: Weigh a certain amount of tetraaminopalladium nitrate and dissolve it in water, add SnO2-1.0N(W) as support, stir, and rotary evaporate; calcine in air at 500℃ for 3h with a heating rate of 2℃ / min to obtain the catalyst, denoted as 1wt.%Pd / SnO2-1.0N(W).

[0053] Example 2

[0054] The difference between this embodiment and Example 1 is that, in the preparation process of SnO2 nanomaterials, 3.5 mmol of tin chloride pentahydrate (IV) was dissolved in a mixed solvent consisting of 10 mL of deionized water and 10 mL of anhydrous ethanol. The resulting SnO2 nanomaterials are denoted as SnO2-1.0N(W+E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-1.0N(W+E).

[0055] The remaining preparation methods and parameters are consistent with those in Example 1.

[0056] Example 3

[0057] The difference between this embodiment and Example 1 is that, in the preparation process of SnO2 nanomaterials, 3.5 mmol of tin chloride pentahydrate (IV) was dissolved in a mixed solvent consisting of 10 mL of deionized water and 20 mL of anhydrous ethanol. The resulting SnO2 nanomaterials are denoted as SnO2-1.0N(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-1.0N(W+2E).

[0058] The remaining preparation methods and parameters are consistent with those in Example 1.

[0059] Example 4

[0060] The difference between this embodiment and Example 1 is that, in the preparation process of SnO2 nanomaterials, 3.5 mmol of tin chloride pentahydrate (IV) was dissolved in a mixed solvent consisting of 10 mL of deionized water and 25 mL of anhydrous ethanol. The resulting SnO2 nanomaterials are denoted as SnO2-1.0N(W+2.5E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-1.0N(W+2.5E).

[0061] The remaining preparation methods and parameters are consistent with those in Example 1.

[0062] Example 5

[0063] The difference between this embodiment and Example 3 is that, in the preparation process of SnO2 nanomaterials, the modifier is a 1 mol / L KOH solution, the obtained SnO2 nanomaterials are denoted as SnO2-1.0K(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-1.0K(W+2E).

[0064] The remaining preparation methods and parameters are consistent with those in Example 3.

[0065] Example 6

[0066] The difference between this embodiment and Example 3 is that, in the preparation process of SnO2 nanomaterials, the regulator is a 1 mol / L TMAH solution, the obtained SnO2 nanomaterials are denoted as SnO2-1.0T(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-1.0T(W+2E).

[0067] The remaining preparation methods and parameters are consistent with those in Example 3.

[0068] Example 7

[0069] The difference between this embodiment and Example 6 is that, in the preparation process of SnO2 nanomaterials, the modifier is a 0.5 mol / L TMAH solution, the obtained SnO2 nanomaterials are denoted as SnO2-0.5T(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-0.5T(W+2E).

[0070] The remaining preparation methods and parameters are consistent with those in Example 6.

[0071] Example 8

[0072] The difference between this embodiment and Example 6 is that, in the preparation process of SnO2 nanomaterials, the regulator is a 2 mol / L TMAH solution, the obtained SnO2 nanomaterials are denoted as SnO2-2T(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-2T(W+2E).

[0073] The remaining preparation methods and parameters are consistent with those in Example 6.

[0074] Example 9

[0075] The difference between this embodiment and Example 6 is that, in the preparation process of SnO2 nanomaterials, the regulator is a 3 mol / L TMAH solution, the obtained SnO2 nanomaterials are denoted as SnO2-3T(W+2E), and the Pd / SnO2 catalyst is denoted as 1 wt.% Pd / SnO2-3T(W+2E).

[0076] The remaining preparation methods and parameters are consistent with those in Example 6.

[0077] Example 10

[0078] The difference between this embodiment and Example 3 is that, in the preparation process of SnO2 nanomaterials, hydrothermal crystallization was carried out at 120°C for 48 hours. After the reaction was completed and the material was cooled to room temperature, the precipitate was collected by centrifugation, washed repeatedly with water and ethanol, and then placed in an oven to dry. The material was then calcined at 500°C for 12 hours in an air atmosphere.

[0079] The remaining preparation methods and parameters are consistent with those in Example 3.

[0080] Example 11

[0081] The difference between this embodiment and Example 3 is that, in the preparation process of SnO2 nanomaterials, hydrothermal crystallization was carried out at 250°C for 6 hours. After the reaction was completed and the material was cooled to room temperature, the precipitate was collected by centrifugation, washed repeatedly with water and ethanol, and then placed in an oven to dry. The material was then calcined at 1000°C for 2 hours in an air atmosphere.

[0082] The remaining preparation methods and parameters are consistent with those in Example 3.

[0083] Example 12

[0084] The difference between this embodiment and Embodiment 3 is that, in the preparation process of SnO2 nanomaterials, the material is calcined at 1200°C for 3 hours in an air atmosphere;

[0085] The remaining preparation methods and parameters are consistent with those in Example 3.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 3 is that, in the preparation process of SnO2 nanomaterials, 10 mmol of tin chloride pentahydrate (IV) was dissolved in a mixed solution of 20 mL of water and 40 mL of anhydrous ethanol without adding any modifier. The resulting SnO2 nanomaterials are referred to as a-SnO2, and the Pd / SnO2 catalyst is referred to as 1 wt.% Pd / a-SnO2.

[0088] The remaining preparation methods and parameters are consistent with those in Example 3.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 3 is that the SnO2 nanomaterials were prepared by precipitation method. The specific process is as follows: 3.5 mmol of tin chloride pentahydrate (IV) was dissolved in a mixed solvent consisting of 10 mL of deionized water and 20 mL of anhydrous ethanol. The mixture was stirred continuously. A 0.5 mol / L NaOH solution was slowly added dropwise until the pH reached 8.0. After the addition was complete, the mixture was stirred at room temperature for 3 hours. After the addition was completed, the precipitate was collected by centrifugation, washed repeatedly with water and ethanol, and then dried in an oven. The precipitate was then calcined at 600°C for 3 hours in air atmosphere at a heating rate of 2°C / min to obtain the SnO2 nanomaterials, denoted as b-SnO2. The Pd / SnO2 catalyst was denoted as 1 wt.% Pd / b-SnO2.

[0091] The remaining preparation methods and parameters are consistent with those in Example 3.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 3 is that calcination is not performed during the preparation of SnO2 nanomaterials;

[0094] The remaining preparation methods and parameters are consistent with those in Example 3.

[0095] Comparative Example 4

[0096] The difference between this comparative example and Example 3 is that, in the preparation process of SnO2 nanomaterials, 3.5 mmol of tin chloride pentahydrate (IV), 0.4 mol of NaOH powder and 70 mL of deionized water were directly mixed to obtain a precursor solution;

[0097] The remaining preparation methods and parameters are consistent with those in Example 3.

[0098] Performance testing

[0099] 1. Catalyst performance evaluation

[0100] 0.2 g of the catalysts prepared in Examples 1-12 and Comparative Examples 1-4 were used respectively, with a mass hourly space velocity (GHSV) of 300,000 mL / (g). h), gas composition: CO = 1000 ppm, O2 = 3.5 vol.%, N2 equilibrium; the reaction was carried out in a continuous flow micro fixed bed, and the concentration change of CO in the tail gas was determined by Fourier transform infrared spectroscopy. The test results are shown in […]. Figure 3 , Figure 4 See Table 1.

[0101] 2. Long-term stability test of catalyst

[0102] 0.2 g of the catalysts prepared in Example 6 and Comparative Examples 1-2 were used respectively, with a mass hourly space velocity (GHSV) of 300,000 mL / (g). h), gas composition: CO = 1000 ppm, O2 = 3.5 vol.%, N2 equilibrium; a long-term test was conducted for 32 h at a constant temperature (stabilizing the reaction temperature at the point where the initial conversion rate of each catalyst is 80%) in a continuous flow micro fixed bed. The change in CO concentration in the tail gas was measured by Fourier transform infrared spectroscopy, and the test results are shown in Table 2. The difference in Table 2 refers to the CO conversion rate measured after 32 h minus the initial CO conversion rate.

[0103] Table 1

[0104]

[0105] Table 2

[0106]

[0107] The catalyst prepared in Example 6 was subjected to SEM and XRD tests, respectively, and the results are as follows: Figure 1 and Figure 2 As shown in the figure, the SnO2 nanomaterials prepared by the preparation method provided by the present invention have a three-dimensional nanoflower-like morphology with a size of about 450 nm and good crystallinity.

[0108] Through analysis Figure 3 The results from the examples and comparative examples in Table 1 show that the hydrothermal synthesis of SnO2 nanomaterials is significantly better than that of the precipitation method as a catalyst support for CO oxidation. Furthermore, the addition of a regulator significantly improves the structure of the SnO2 nanomaterials, enhancing their catalytic performance. In addition, the order of calcination and the addition of raw materials also affects the structure of the SnO2 nanomaterials, thus influencing the catalyst's performance. By comparing the experimental data from Examples 1-4, the effects of adding ethanol to the precursor solution and the water-to-ethanol ratio on catalytic performance were studied. It was found that the addition of ethanol improves the catalyst's performance, and the catalytic performance is optimal when the amount of ethanol added is twice that of water, i.e., W:E = 1:2 (v:v) with 1 wt.% Pd / SnO2-1.0N(W+2E).

[0109] Through analysis and comparison Figure 4 Based on the experimental data of Examples 5-9 in Table 1, the influence of the type and concentration of regulator on catalytic performance was studied. It can be concluded that when the three preferred regulators of the present invention are used and their concentrations are controlled within the preferred range provided by the present invention, the catalysts all exhibit superior performance. Moreover, when the regulator is a 1.0 mol / L TMAH solution, the catalytic performance of 1 wt.% Pd / SnO2-1.0T(W+2E) is the best.

[0110] As can be seen from the comparison of the data of Example 3 and Examples 10-12 in Table 1, using the hydrothermal temperature and time and the first calcination temperature and time within the preferred range of the present invention can yield a catalyst with excellent performance. However, when the first calcination temperature is too high, the catalyst performance will decrease.

[0111] As shown in Table 2, the SnO2 nanomaterials prepared by the method provided in this invention have a better synergistic effect with Pd when used as a CO oxidation catalyst support compared with SnO2 materials prepared without the addition of a regulator or by precipitation method. Therefore, the catalyst can exhibit better long-term stability.

[0112] 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 SnO2 nanomaterials, characterized in that, The preparation method includes: The tin source is mixed sequentially with a solvent and a modifier to obtain a precursor solution. The precursor solution is then subjected to hydrothermal crystallization treatment, and the resulting solid product is subjected to a first calcination to obtain the SnO2 nanomaterial.

2. The preparation method according to claim 1, characterized in that, The tin source includes a soluble tin salt, which includes tin tetrachloride pentahydrate; Preferably, the solvent comprises water and / or ethanol, more preferably water and ethanol; Preferably, when the solvent is water and ethanol, the volume ratio of water to ethanol is 1:(1~2.5); Preferably, the regulator comprises any one or a combination of at least two of NaOH aqueous solution, KOH aqueous solution or TMAH aqueous solution, and more preferably TMAH aqueous solution; Preferably, the concentration of the regulator is 0.5 mol / L to 3 mol / L; Preferably, the process of mixing the tin source with the solvent and the regulator in sequence includes: mixing the tin source and the solvent to obtain a tin source solution, and then adding the regulator dropwise to the tin source solution.

3. The preparation method according to claim 1 or 2, characterized in that, The hydrothermal crystallization treatment is carried out at a temperature of 120℃~250℃ for a time of 6h~48h. Preferably, the product after hydrothermal crystallization is subjected to centrifugation, washing, and drying in sequence to obtain the solid product; Preferably, the first calcination temperature is 500℃~1000℃ and the time is 2h~12h.

4. A SnO2 nanomaterial, characterized in that, The SnO2 nanomaterial is prepared by the preparation method according to any one of claims 1-3.

5. The SnO2 nanomaterial according to claim 4, characterized in that, The SnO2 nanomaterial has a three-dimensional nanoflower-like morphology; Preferably, the average size of the SnO2 nanomaterial is 200nm~500nm.

6. A CO oxidation catalyst, characterized in that, The CO oxidation catalyst includes a support and Pd supported on the support, wherein the support is the SnO2 nanomaterial as described in claim 4 or 5.

7. The CO oxidation catalyst according to claim 6, characterized in that, The loading of Pd on the carrier is 0.05 wt.% to 5 wt.%.

8. A method for preparing the CO oxidation catalyst as described in claim 6 or 7, characterized in that, The preparation method includes: impregnating the SnO2 nanomaterial as described in claim 4 or 5 in an aqueous solution of palladium salt, and after the impregnation is completed, subjecting the impregnated product to a second calcination to obtain the CO oxidation catalyst.

9. The method for preparing the Pd / SnO2 catalyst according to claim 8, characterized in that, The palladium salt includes palladium nitrate, and is more preferably tetraaminopalladium nitrate; Preferably, the second calcination temperature is 500℃~1000℃ and the time is 2h~12h.

10. The application of the CO oxidation catalyst as described in claim 6 or 7 in the catalytic oxidation reaction of CO.

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