Titanium dioxide-based catalyst for catalytic oxidation of toluene and method for its preparation

Abstract

The application discloses a titanium dioxide-based catalyst for catalytic oxidation of toluene and a preparation method thereof, and belongs to the technical field of pollution control. The catalyst is prepared by a sol-gel method and comprises a titanium dioxide carrier and a doped metal active component. The active component is in two cases: one is only manganese element, and the molar ratio of manganese to titanium is 5-10:1; the other is that the active component comprises manganese and one second metal element selected from copper, cobalt or cerium, and the molar ratio of the total molar amount of manganese and the second metal element to the molar amount of titanium is 10:1, and the molar ratio of the two is 1:1. The preparation method comprises the following steps: dissolving metal precursors and a titanium source in ethanol to form solutions, mixing and stirring to obtain a gel, and then performing drying and calcination treatment. According to the application, the sol-gel method is used to realize high dispersion of the active component and close combination with the carrier, the prepared catalyst has excellent low-temperature catalytic oxidation activity for toluene, and meanwhile, the catalyst has good stability in a complex atmosphere containing sulfur and water.

Description

Technical Field

[0001] This invention belongs to the field of pollution control technology, specifically relating to a titanium dioxide-based catalyst for the catalytic oxidation of toluene and its preparation method. Background Technology

[0002] Volatile organic compounds (VOCs) are a significant source of air pollution. Toluene, as a typical aromatic hydrocarbon VOC, poses a significant threat to human health and the ecological environment. Catalytic oxidation technology can convert VOCs into harmless carbon dioxide and water at relatively low temperatures. Due to its high efficiency, relatively low energy consumption, and minimal secondary pollution, it is considered one of the most promising end-of-pipe treatment technologies for VOCs.

[0003] The commercial application of this technology heavily relies on the development of high-performance catalysts. Currently, transition metal oxide-based catalysts have attracted widespread attention due to their relatively low cost and good catalytic activity. However, such catalysts often face severe challenges in real-world industrial applications (e.g., petrochemical, spraying, etc.). Real industrial waste gases are complex in composition, and target VOCs (such as toluene) often coexist with multiple interfering components, among which sulfur dioxide (SO2) and water vapor (H2O) have particularly significant effects. SO2 can adsorb and react on the catalyst surface to form stable sulfate species, leading to permanent coverage of active sites or damage to the support structure, resulting in severe chemical deactivation. Water vapor, on the other hand, readily competes with reactant molecules for adsorption at active sites, thus inhibiting the catalytic reaction. These factors collectively cause a significant decrease in catalyst activity and stability in real-world complex atmospheres, shortening their lifespan and increasing operating costs.

[0004] Therefore, developing a catalyst that can maintain high catalytic activity such as that of toluene while effectively tolerating complex industrial waste gas environments containing sulfur and water is a key technical challenge that urgently needs to be solved to promote the large-scale industrial application of catalytic oxidation technology. Summary of the Invention

[0005] The purpose of this invention is to provide a titanium dioxide-based catalyst with high catalytic oxidation activity for toluene. Another purpose of this invention is to provide a method for preparing the above-mentioned catalyst, which uses a sol-gel method to prepare the titanium dioxide-based catalyst. This catalyst maintains high activity while also being able to withstand complex industrial waste gas environments containing sulfur and water, thereby improving its operational stability in practical applications.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows: On the one hand, the present invention provides a titanium dioxide-based catalyst for the catalytic oxidation of toluene, which is prepared by the sol-gel method and comprises titanium dioxide as a support and a metal active component doped therein; The active metal component satisfies either of the following two conditions: Case 1: The active metal component contains only manganese, and the molar ratio of manganese to titanium is 5~10:1; Case 2: The active metal component contains manganese and a second metal element selected from copper, cobalt, or cerium, wherein the total molar ratio of manganese and the second metal element to the molar ratio of titanium is 10:1, and the molar ratio of manganese to the second metal element is 1:1.

[0007] Furthermore, the second metallic element is copper.

[0008] On one hand, the present invention provides a method for preparing the above-mentioned titanium dioxide-based catalyst, comprising the following steps: Step 1: Dissolve the metal precursor in ethanol, then add acid and stir for 0.5-3 hours to obtain a homogeneous solution A, wherein the metal precursor contains at least manganese nitrate; Step 2: Dissolve the titanium source in ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: Dry and calcine the gel obtained in Step 3 to obtain the titanium dioxide-based catalyst.

[0009] Further, the acid solution in step one is one or more of hydrochloric acid, sulfuric acid, nitric acid or glacial acetic acid; and / or, the titanium source in step two is one or more of titanium tetrachloride, tetrabutyl titanate, titanium isopropoxide or titanium oxysulfate.

[0010] Furthermore, the calcination temperature in step four is 300℃-500℃, and the calcination time is 4-6 hours.

[0011] Furthermore, in step one, the metal precursor contains only manganese nitrate.

[0012] Specifically, it includes the following steps: Step 1: Dissolve 1.55 mL to 2.33 mL of manganese nitrate solution in 0.5 to 1 mL of ethanol, then add 0.5 to 1 mL of acid solution and stir for 0.5 to 3 hours to obtain a homogeneous solution A; Step 2: Dissolve 3.4 mL of tetrabutyl titanate in 5 mL of ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: The gel obtained in Step 3 is dried and calcined to obtain the titanium dioxide-based catalyst; In the obtained titanium dioxide-based catalyst, the molar ratio of manganese to titanium is 5~10:1.

[0013] Furthermore, in step one, the metal precursor comprises manganese nitrate and any one of copper nitrate, cobalt nitrate, or cerium nitrate.

[0014] Specifically, it includes the following steps: Step 1: Dissolve 1.15 mL of manganese nitrate solution together with one of the second metal nitrates selected from 1.20 g of copper nitrate, 1.45 g of cobalt nitrate, or 2.17 g of cerium nitrate in 0.5 mL of ethanol. Then add 0.7 mL of acid solution and stir for 0.5-3 hours to obtain a homogeneous solution A. Step 2: Dissolve 3.4 mL of tetrabutyl titanate in 5 mL of ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: The gel obtained in Step 3 is dried and calcined to obtain the titanium dioxide-based catalyst; In the obtained titanium dioxide-based catalyst, the ratio of the total molar amount of manganese and the second metal element to the molar amount of titanium element is 10:1, and the molar ratio of manganese to the second metal element is 1:1.

[0015] Beneficial effects: (1) This invention employs the sol-gel method to achieve uniform doping and high dispersion of the active metal component during the formation of the TiO2 support. This method effectively avoids the loss of active sites caused by the aggregation of the active component, thereby significantly improving the specific surface area and intrinsic activity of the catalyst. Experimental results show that the single manganese catalyst prepared by this method has a higher To of toluene. 90 (90% conversion temperature) can be as low as 263℃, while the optimal manganese-copper bimetallic catalyst has a T 90 It can be further reduced to 248℃, exhibiting excellent low-temperature catalytic oxidation performance.

[0016] (2) The sol-gel process, through co-hydrolysis and condensation reactions, enables the active metal precursor and titanium source to achieve uniform molecular-level mixing and chemical bonding during gel formation. After calcination, the active components are highly dispersed and form strong interactions with the titanium dioxide support. This composite state, determined by the preparation method, allows the catalyst to exhibit excellent stability in simulated complex atmospheres containing sulfur or water. Comparative experiments show that, under the same accelerated aging conditions, the catalyst prepared by the method of this invention exhibits significantly lower performance degradation than the catalyst prepared by the traditional impregnation method, demonstrating stronger resistance to sulfur and water interference.

[0017] (3) When copper (Cu) is introduced as the second metal, a significant synergistic enhancement effect is generated between it and manganese (Mn), which further improves the catalytic activity. This effect may stem from the optimized electronic interactions at the bimetallic interface, thereby improving the redox cycle capability of the catalyst. In addition, the introduction of cobalt (Co) or cerium (Ce) can also form a catalyst combination with good activity. This invention provides a variety of feasible solutions.

[0018] (4) The preparation method of this invention has a simple process and mild reaction conditions. The content and proportion of active components in the final catalyst can be precisely controlled by adjusting the molar ratio of the metal precursor to the titanium source. This process has excellent repeatability and controllability, laying the foundation for large-scale production. Attached Figure Description

[0019] Figure 1 The images show the catalytic activity curves of the catalysts prepared in Examples 1 and 2 and Comparative Examples 1-4 of this invention.

[0020] Figure 2 The graph shows the stability test results of the catalysts prepared in Example 1 and Comparative Example 4 of this invention under an atmosphere containing SO2.

[0021] Figure 3 The image shows the stability test results of the catalysts prepared in Example 1 and Comparative Example 4 of this invention under a water-containing atmosphere.

[0022] Figure 4 This is a comparison diagram of the catalytic activity of the bimetallic catalysts prepared in Examples 1, 3, 4, 5 and Comparative Example 5 of the present invention. Detailed Implementation

[0023] This invention provides a titanium dioxide-based catalyst specifically for the catalytic oxidation and removal of toluene. The catalyst is prepared using a sol-gel method and is essentially a composite metal oxide material containing a specific active metal component. The preparation method aims to achieve a high degree of dispersion and tight bonding between the active metal element (manganese, or manganese and a second metal) and the titanium dioxide (TiO2) support.

[0024] Specifically, the active component of the catalyst follows one of the following two designs: (1) Single-metal active type: The active component contains only one metal element, manganese (Mn). In this case, the molar ratio of manganese to titanium (Ti) support is controlled in a high range of 5:1 to 10:1. This high loading is the key to ensuring that the catalyst has a sufficient number of active sites, thereby achieving high activity.

[0025] (2) Bimetallic active type: The active component contains manganese (Mn) and another second metal element selected from copper (Cu), cobalt (Co), or cerium (Ce). In this case, the ratio of the total molar amount of the two metal elements to the molar amount of titanium (Ti) is fixed at 10:1, and the molar ratio of manganese to the selected second metal is 1:1. This specific combination and ratio is designed to optimize performance by utilizing the interaction between the metals.

[0026] Regardless of the type mentioned above, the catalysts are prepared via the sol-gel method. The core advantage of this method is that it enables the active component to be uniformly mixed with the support precursor at the molecular level in the early stages of material formation (liquid sol stage), thereby obtaining a microstructure in the final solid catalyst with a highly dispersed active component and a strong bond to the support.

[0027] The preparation method of the catalyst of this invention, namely the sol-gel method, generally includes the following four core steps, as detailed below: Step 1: Preparation of the active metal precursor solution (Solution A): Dissolve the required metal precursor in a certain amount of ethanol, then add an acid solution (one or more of hydrochloric acid, sulfuric acid, nitric acid, or glacial acetic acid), and stir continuously for 0.5-3 hours to obtain a homogeneous and transparent solution A. The metal precursor must contain at least manganese nitrate to provide manganese. For bimetallic solutions, one of copper nitrate, cobalt nitrate, or cerium nitrate must also be added in proportion. The purpose of this step is to convert the active metal element into a precursor state soluble in the alcohol solvent. The key role of the added acid solution here is as a "hydrolysis control agent," which can regulate the subsequent hydrolysis reaction rate of the titanium source and prevent it from precipitating too quickly. Simultaneously, the anions in the acid (such as acetate) can coordinate with the metal ions, contributing to the formation of a stable precursor solution, which is the basis for obtaining a homogeneous gel. Step 2: Preparation of Titanium Source Solution (Solution B): Dissolve the titanium source (one or more of titanium tetrachloride, tetrabutyl titanate, titanium isopropoxide, or titanium oxysulfate) in a certain amount of ethanol to obtain a homogeneous and transparent solution B. This step prepares the precursor solution for the titanium dioxide support. The titanium source compound is the "raw material" for forming the final TiO2 support; Step 3, Mixing and Gelation: Under continuous stirring, solution A obtained in Step 1 is slowly added dropwise to solution B to avoid excessively high local concentrations. After the addition is complete, stirring continues for 0.5-3 hours. The entire system gradually transforms from a flowing solution into a non-flowing, somewhat elastic, pale yellow gel. This step is the core transformation process of the sol-gel method. In the presence of stirring and acid (as a hydrolysis control agent), the titanium source and metal precursor gradually undergo hydrolysis and condensation reactions. This process promotes uniform mixing and chemical bonding at the molecular level between the active metal component and the titanium species in the early stages of the solution-to-gel transition, forming a homogeneous gel system. This lays the foundation for obtaining a catalyst with highly dispersed active components. Step 4, Drying and Calcination: The wet gel obtained in Step 3 is dried (usually at 80-120℃ for several to over ten hours) to remove the solvent and water. The dried solid is then calcined at high temperature for a period of time (300℃ to 500℃, 4 to 6 hours) to obtain the final catalyst powder. This step is crucial: First, the high temperature completely decomposes and removes residual nitrate ions, organic acid ions, and other organic matter from the gel, purifying the material. Second, the high-temperature treatment promotes the transformation of the amorphous TiO2 precursor into a well-crystallized titanium dioxide support, thereby enhancing the overall thermal and structural stability of the catalyst. Third, the calcination process transforms the active metal precursor into the corresponding metal oxide active phase, ultimately fixing the active components formed during the sol-gel process into a uniformly mixed and tightly bound state with the support precursor, thus obtaining a final catalyst with highly dispersed active components and good thermal stability.

[0028] The following detailed embodiments and comparative examples further illustrate the implementation process of the present invention and demonstrate its technical effects.

[0029] Example 1 (Single-metal highly supported catalyst 10Mn-TiO2(SG)) The catalyst preparation method in this embodiment is as follows: Step 1 (Preparation of active component solution): Mix 2.33 mL of manganese nitrate solution (50 wt% aqueous solution) with 1 mL of anhydrous ethanol, dissolve, add 0.7 mL of glacial acetic acid, stir for 30 min to obtain a colorless, transparent, homogeneous solution A; Step 2 (Preparation of titanium source solution): Mix 3.4 mL of tetrabutyl titanate with 5 mL of anhydrous ethanol, stir gently to dissolve, and obtain a colorless, transparent, and homogeneous solution B; Step 3 (sol-gel process): While stirring, slowly add solution A to solution B dropwise. After the addition is complete, continue stirring for 0.5 hours. The system gradually transforms into a pale yellow transparent gel. Step 4 (drying and calcination): The gel was dried at 80°C for 12 hours, ground, and then calcined at 400°C for 4 hours in a muffle furnace to obtain 10Mn-TiO2(SG) catalyst, wherein the molar ratio of Mn to Ti is approximately 10:1.

[0030] Example 2 (Single metal catalyst 5Mn-TiO2(SG)) The preparation steps were the same as in Example 1, except that the amount of manganese nitrate solution used in step one was changed to 1.55 mL and glacial acetic acid to 0.5 mL. A 5Mn-TiO2 (SG) catalyst was obtained, wherein the molar ratio of Mn to Ti was approximately 5:1.

[0031] Example 3 (Bimetallic catalyst 5Cu5Mn-TiO2(SG)) The catalyst preparation method in this embodiment is as follows: Step 1: Mix 1.15 mL of manganese nitrate solution and 1.20 g of copper nitrate trihydrate with 0.5 mL of anhydrous ethanol, dissolve, add 0.7 mL of glacial acetic acid, stir for 30 min to obtain blue solution A; Step 2 (Preparation of titanium source solution): Mix 3.4 mL of tetrabutyl titanate with 5 mL of anhydrous ethanol, stir gently to dissolve, and obtain a colorless, transparent, and homogeneous solution B; Step 3 (sol-gel process): Under stirring, solution A is slowly added dropwise to solution B. After the addition is complete, stirring continues for 0.5 hours, and the system gradually transforms into a pale yellow transparent gel. This process is crucial for the molecular-level mixing and bonding of the active component and the carrier precursor. Step 4 (drying and calcination): The gel was dried at 80℃ for 12 hours, ground, and then calcined at 400℃ for 4 hours in a muffle furnace to obtain 5Cu5Mn-TiO2(SG) catalyst, wherein (Mn+Cu):Ti≈10:1 and Mn:Cu≈1:1.

[0032] Example 4 (Bimetallic catalyst 5Ce5Mn-TiO2(SG)) The preparation method in this embodiment differs from that in Example 3 only in that copper nitrate is replaced with 2.17g of cerium nitrate hexahydrate. The resulting catalyst is denoted as 5Ce5Mn-TiO2(SG), where (Mn+Ce):Ti≈10:1 and Mn:Ce≈1:1.

[0033] Example 5 (Bimetallic catalyst 5Co5Mn-TiO2(SG)) The preparation method in this embodiment differs from that in Example 3 only in that copper nitrate is replaced with 1.45g of cobalt nitrate hexahydrate. The resulting catalyst is denoted as 5Co5Mn-TiO2(SG), where (Mn+Co):Ti≈10:1 and Mn:Co≈1:1.

[0034] Comparative Example 1 (0.5Mn-TiO2(SG)) The only difference between this comparative preparation method and Example 1 is that the amount of manganese nitrate used is 0.11 mL. The resulting catalyst is denoted as 0.5Mn-TiO2(SG), and the Mn:Ti ratio in the resulting catalyst is approximately 0.5:1.

[0035] Comparative Example 2 (1Mn-TiO2(SG)) The only difference between this comparative preparation method and Example 1 is that the amount of manganese nitrate used is 0.23 mL. The resulting catalyst is denoted as 1Mn-TiO2(SG), and the Mn:Ti ratio in the resulting catalyst is approximately 1:1.

[0036] Comparative Example 3 (2Mn-TiO2(SG)) The only difference between this comparative preparation method and Example 1 is that the amount of manganese nitrate used is 0.46 mL. The resulting catalyst is denoted as 2Mn-TiO2(SG), and the Mn:Ti ratio in the resulting catalyst is approximately 2:1.

[0037] Comparative Example 4 (Preparation of catalyst 10Mn-TiO2 (IWI) by impregnation method) Step 1: Mix 0.5 mL of glacial acetic acid with 0.5 mL of ethanol to dissolve the solution, obtaining a colorless, transparent, and homogeneous solution A; Step 2: Mix 3.4 mL of tetrabutyl titanate with 5 mL of ethanol to dissolve and obtain a colorless, transparent, homogeneous solution B; Step 3: Under stirring conditions, slowly add solution A to solution B, then stir for 0.5 hours to obtain a white gel; Step 4: Place the obtained gel in an oven at 80°C for 12 hours and then calcine it in a muffle furnace at 400°C for 4 hours to obtain the TiO2 support. Step 5: Mix 1.06 mL of manganese nitrate solution with 2 mL of anhydrous ethanol, dissolve, add 1 g of TiO2 carrier, stir for 2 h until completely dissolved, and then let stand for 12 h. Step 6: After drying the above solution, place the solid in a muffle furnace and calcine at 400°C for 4 hours to obtain the 10Mn-TiO2 (IWI) catalyst.

[0038] Comparative Example 5 (Bimetallic catalyst 5Ni5Mn-TiO2(SG)) The only difference between this comparative preparation method and Example 3 is that copper nitrate is replaced with 1.45g of nickel nitrate hexahydrate. The second metal in the obtained catalyst is Ni, and the obtained catalyst is denoted as 5Ni5Mn-TiO2(SG), where (Mn+Ni):Ti≈10:1 and Mn:Cu≈1:1.

[0039] Catalyst performance testing methods and results analysis The toluene oxidation activity of the catalyst was evaluated in a fixed-bed reactor. The reaction gas was a toluene / air mixture of ~1000 ppm. The catalyst dosage was 0.05 g, and it was pretreated in oxygen at 250 °C for 1 h before testing. The conversion rate was determined by programmed temperature increase (200-350 °C), and T was calculated. 50 and T 90 .

[0040] Stability testing: at the catalyst's T 90 At the specified temperature, 20 ppm SO2 or a certain concentration of water vapor was introduced into the reaction gas, and the process was continued for 8 hours while monitoring the change in conversion rate.

[0041] The test results are shown in Table 1.

[0042] Table 1. T values ​​of the catalysts prepared in Examples 1-5 and Comparative Examples 1-5 50 and T 90 Data table The following conclusions can be drawn from Table 1: (1) Among the single-metal catalyst series (Mn-TiO2(SG)), the catalytic activity (in terms of T) 50 and T 90 The index (as an indicator) is strongly dependent on the manganese loading. As the Mn / Ti molar ratio increases from 0.5:1 (Comparative Example 1) to 10:1 (Example 1), T 90 The temperature dropped significantly from 344℃ to 263℃, indicating that increasing the manganese loading effectively increases the number of active sites, which is key to improving the intrinsic activity of the catalyst. It is noteworthy that when the Mn / Ti ratio reaches or exceeds 5:1 (Examples 1-2), the catalyst enters the high-activity range (T...). 90 ≤268℃), which is the high activity range protected by this invention.

[0043] (2) Comparative Example 1 (10Mn-TiO2(SG)) and Comparative Example 4 (10Mn-TiO2(IWI)) have the same manganese loading, but the former has a different T 90 The temperature of the sol-gel method (263℃) is significantly lower than that of the traditional impregnation method (300℃). This directly proves that the sol-gel method, compared with the traditional impregnation method, can impart higher catalytic activity to the product when preparing catalysts with the same composition. The fundamental reason lies in the essential difference in the microstructure of the catalysts obtained by the two methods.

[0044] (3) In the bimetallic catalyst series, under the premise of fixed total metal loading (M+Ti=10:1) and manganese to second metal ratio (1:1), the type of second metal has a decisive influence on the activity. Example 3 (5Cu5Mn-TiO2(SG)) showed the best activity (T 90 =248℃), its T90 The activity was 15°C lower than that of Example 1, which showed the best activity among single metals, indicating a positive synergistic effect between Cu and Mn. Examples 4 (Ce) and 5 (Co) exhibited activities comparable to or slightly better than Example 1, while Comparative Example 5 (Ni) showed relatively poor activity. This systematically demonstrates that the choice of the second metal is not arbitrary; copper (Cu), cobalt (Co), and cerium (Ce) are preferred elements for effective co-doping with manganese, with Cu showing the most significant effect.

[0045] Figure 1 The activity curves visually demonstrate the activity order of the single-metal catalyst series: 10Mn > 5Mn > 2Mn > 1Mn > 0.5Mn, which corresponds perfectly with the data in Table 1. Meanwhile, Figure 1 The significant positional difference between the curves in Example 1 and Comparative Example 4 vividly demonstrates the activity advantage of the sol-gel method.

[0046] Figure 2 and Figure 3 The stability test results reveal the structural stability of the catalyst of this invention from a kinetic perspective. Figure 2 The results show that, in an atmosphere containing SO2, the catalyst of Example 1 maintained stable activity (conversion >95%) with minimal degradation during the 8-hour test; while the catalyst of Comparative Example 4 showed a sharp decline in activity. This strongly demonstrates that the highly dispersed active components and strong interaction with the TiO2 support facilitated by the sol-gel method can effectively inhibit the poisoning effect of SO2 on the active sites. Figure 3 The similar trend (the stability of Example 1 is much better than that of Comparative Example 4) indicates that this structure can also mitigate the adverse effects of competitive adsorption of water vapor. These two figures, from the perspective of "anti-interference," further illustrate the outstanding value of the method of this invention in improving the practical performance and lifespan of the catalyst.

[0047] Figure 4 The focus is on comparing the activity of the bimetallic catalyst and the reference catalyst. It can be clearly seen that the curve of 5Cu5Mn-TiO2(SG) is on the far left (highest activity in the low temperature region), while the curve of 5Ni5Mn-TiO2(SG) is relatively to the right, which intuitively confirms the data analysis on the bimetallic synergistic effect in Table 1.

[0048] In summary, based on the quantitative data in Table 1 and... Figure 1-4The intuitive characterization fully verifies the effectiveness of the technical solution of the present invention: the sol-gel method, and by controlling the active components to fall into a specific high-load single manganese range (Mn / Ti=5~10:1) or a specific ratio of bimetallic range ((Mn+second metal element) / Ti=10:1, Mn / second metal element=1:1, second metal element=Cu, Co, Ce), is a reliable way to obtain catalysts with high toluene oxidation activity, excellent stability and practical prospects.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A titanium dioxide-based catalyst for the catalytic oxidation of toluene, characterized in that, Prepared by the sol-gel method, it contains titanium dioxide as a carrier and active metal components doped therein; The active metal component satisfies either of the following two conditions: Case 1: The active metal component contains only manganese, and the molar ratio of manganese to titanium is 5~10:1; Case 2: The active metal component contains manganese and a second metal element selected from copper, cobalt, or cerium, wherein the total molar ratio of manganese and the second metal element to the molar ratio of titanium is 10:1, and the molar ratio of manganese to the second metal element is 1:

1.

2. The titanium dioxide-based catalyst according to claim 1, characterized in that, The second metallic element is copper.

3. A method for preparing the titanium dioxide-based catalyst as described in claim 1, characterized in that, Includes the following steps: Step 1: Dissolve the metal precursor in ethanol, then add acid and stir for 0.5-3 hours to obtain a homogeneous solution A, wherein the metal precursor contains at least manganese nitrate; Step 2: Dissolve the titanium source in ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: Dry and calcine the gel obtained in Step 3 to obtain the titanium dioxide-based catalyst.

4. The method according to claim 3, characterized in that, The acid solution in step one is one or more of hydrochloric acid, sulfuric acid, nitric acid or glacial acetic acid; and / or, the titanium source in step two is one or more of titanium tetrachloride, tetrabutyl titanate, titanium isopropoxide or titanium oxysulfate.

5. The method according to claim 3, characterized in that, The calcination temperature in step four is 300℃-500℃, and the calcination time is 4-6 hours.

6. The method according to claim 3, characterized in that, In step one, the metal precursor contains only manganese nitrate.

7. The method according to claim 6, characterized in that, Includes the following steps: Step 1: Dissolve 1.55 mL to 2.33 mL of manganese nitrate solution in 0.5 to 1 mL of ethanol, then add 0.5 to 1 mL of acid solution and stir for 0.5 to 3 hours to obtain a homogeneous solution A; Step 2: Dissolve 3.4 mL of tetrabutyl titanate in 5 mL of ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: The gel obtained in Step 3 is dried and calcined to obtain the titanium dioxide-based catalyst; In the obtained titanium dioxide-based catalyst, the molar ratio of manganese to titanium is 5~10:

1.

8. The method according to claim 3, characterized in that, In step one, the metal precursor includes manganese nitrate and any one of copper nitrate, cobalt nitrate, or cerium nitrate.

9. The method according to claim 8, characterized in that, Includes the following steps: Step 1: Dissolve 1.15 mL of manganese nitrate solution together with one of the second metal nitrates selected from 1.20 g of copper nitrate, 1.45 g of cobalt nitrate, or 2.17 g of cerium nitrate in 0.5 mL of ethanol. Then add 0.7 mL of acid solution and stir for 0.5-3 hours to obtain a homogeneous solution A. Step 2: Dissolve 3.4 mL of tetrabutyl titanate in 5 mL of ethanol to obtain a homogeneous solution B; Step 3: Add solution A obtained in Step 1 dropwise to solution B obtained in Step 2 while stirring, and then continue stirring for 0.5-3 hours to obtain a gel; Step 4: The gel obtained in Step 3 is dried and calcined to obtain the titanium dioxide-based catalyst; In the obtained titanium dioxide-based catalyst, the total molar ratio of manganese and the second metal element to the molar ratio of titanium element is 10:1, and the molar ratio of manganese to the second metal element is 1:1.

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