Preparation method and application of bimetallic single atom / attapulgite composite catalytic material
By preparing PdM/ATP composite catalytic materials using a modified attapulgite support and a microwave solvothermal method, the problems of complex and costly support preparation were solved, and a highly efficient toluene catalytic oxidation effect was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGZHOU UNIV
- Filing Date
- 2024-05-30
- Publication Date
- 2026-08-04
AI Technical Summary
In existing technologies, the preparation process of single-atom catalyst supports is complex and costly, traditional Pd catalysts have low atom utilization, and the catalytic efficiency of noble metal SACs is close to the maximum activity limit. Improving catalytic efficiency remains a challenge.
Using hydrogen peroxide-modified attapulgite as a support, PdM/ATP composite catalysts were synthesized via a microwave solvothermal method. By controlling the process parameters, bimetallic single-atom catalysts were formed by utilizing the synergistic effect between Pd and transition metals.
A simple and low-cost bimetallic single-atom catalyst was developed, which improved the catalytic oxidation efficiency of toluene, lowered the reaction barrier, and enhanced the stability and selectivity of the catalyst.
Smart Images
Figure CN118594564B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental protection, specifically relating to a method for preparing and applying a bimetallic single-atom / attapulgite composite catalytic material. Background Technology
[0002] Volatile organic compounds (VOCs) are a class of organic chemical substances widely generated in various industrial and daily life processes, including various hydrocarbons and organic solvents. VOCs are not only toxic, volatile, and carcinogenic, but also contribute to climate change and the formation of ground-based ozone, aerosols, and smog. Therefore, there is an urgent need to develop catalytic materials for the effective degradation of VOCs.
[0003] In recent years, Pd has shown promising application prospects in the field of catalysis. However, the low atom utilization rate and high price of traditional Pd catalysts still greatly limit their industrial application. Single-atom catalysts (SACs) have become one of the best choices for homogeneous and heterogeneous catalysis. CN107008290B provides a method for preparing a single-atom catalyst with a hydrotalcite-like structure, including the preparation of semiconductor hydrotalcite by a double-drop method and the reduction of palladium atoms by photodeposition. Although it uses inexpensive mineral-like materials as supports, a large number of chemical reagents are used in the treatment of the supports, and the catalyst preparation process is complex. CN107890881A involves a method for confining a single-atom catalyst using the internal pore structure of ZSM5 molecular sieve. It first prepares a rhodium-containing gel, then hydrothermally calcines the gel in a high-temperature furnace under a fixed atmosphere to synthesize ZSM5 molecular sieve and promote the decomposition of rhodium groups. The rhodium is dispersed in the molecular sieve in single-atom form by confinement through the internal pore structure of the molecular sieve. However, the preparation process of ZSM5 molecular sieve is complex and expensive, which is not conducive to practical application. CN111905794A provides a high-temperature calcination method for preparing single-atom catalysts, using sucrose and melamine as carbon and nitrogen sources, respectively. After adding an Fe source, Fe-N4 sites are formed through high-temperature calcination to stabilize Fe single atoms. However, the synthesis conditions are quite harsh and consume a lot of energy, which is not conducive to actual production.
[0004] In summary, it can be seen that the preparation and processing of single-atom catalyst supports in existing technologies are complex and costly. Furthermore, noble metal SACs are approaching their maximum activity limit, and further improving catalytic efficiency will face a series of challenges. In recent years, due to the high activity and stability resulting from the synergistic effect between different atoms and the relatively stable dimer structure, bimetallic SACs constructed from noble metals and transition metals have been developed, and their catalytic efficiency is superior to that of single-metal atom catalysts. Therefore, developing a simple method for preparing dual single-atom Pd-based catalysts is of great significance.
[0005] Attapulgite (ATP), also known as palygorskite, is a naturally occurring one-dimensional magnesium-rich silicate clay mineral with a unique layered chain structure, fibrous morphology, and high specific surface area. Therefore, attapulgite offers significant advantages as a support for active components in terms of mass transfer and synergistic reactivity. Furthermore, to further enhance attapulgite's performance as a support, processes such as acid leaching have been employed to increase specific surface area and pore volume, improving the deposition of active sites on its surface. Attapulgite, as a catalyst support, exhibits unique support effects such as co-catalyst properties, co-dispersion, and environmental friendliness, which are beneficial for anchoring the formation of single atoms. To date, no method has been reported for preparing palladium-based bimetallic single-atom catalysts by combining palladium salts and transition metal salts with attapulgite, utilizing the synergistic effect between palladium and transition metal ions to achieve highly efficient catalytic oxidation of toluene. Summary of the Invention
[0006] To address the aforementioned problems, this invention provides a method for preparing and applying a bimetallic single-atom / attapulgite composite catalytic material. Using hydrogen peroxide-modified attapulgite as a support, this invention employs a simple microwave solvothermal method for synthesis. By controlling process parameters such as raw material ratio and calcination temperature, a PdM / ATP composite catalytic material is obtained. The resulting catalyst can degrade toluene to the maximum extent. This invention overcomes the shortcomings of traditional Pd catalysts, such as low atom utilization, poor selectivity and stability, and the complex and costly preparation and processing of single-atom catalyst supports. It successfully obtains a bimetallic single-atom catalyst with a simple synthesis method and low cost.
[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:
[0008] A method for preparing a bimetallic single-atom / attapulgite composite catalytic material is provided, the method comprising the following steps:
[0009] (1) Attapulgite was immersed in an aqueous solution of hydrogen peroxide, stirred in a water bath, filtered, washed and dried to obtain modified attapulgite.
[0010] (2) Weigh palladium salt and transition metal salt and add them to an organic solvent. After ultrasonic dissolution, add the modified attapulgite from step (1) and stir thoroughly until homogeneous to obtain a mixture.
[0011] (3) Transfer the mixture from step (2) to a reaction vessel and place it in a microwave chemical reactor for microwave hydrothermal reaction. After the reaction is completed, cool, centrifuge, wash, and dry.
[0012] (4) Place the dried product from step (3) into a muffle furnace, calcine it, collect the sample and grind it thoroughly to obtain a bimetallic single-atom / attapulgite composite catalytic material.
[0013] Further, the mass fraction of the hydrogen peroxide aqueous solution in step (1) is 30%; the solid-liquid ratio of attapulgite to hydrogen peroxide aqueous solution is 1.5g:100mL.
[0014] Further, in step (2), the molar ratio of palladium salt to transition metal salt is 1:1; the ratio of the sum of the molars of palladium salt and transition metal salt to the volume of organic solvent is 0.0125 to 0.025 mmol: 40 mL.
[0015] Furthermore, the transition metal salt mentioned in step (2) is any one of Cu, Fe, and Co salts.
[0016] Further, the organic solvent mentioned in step (2) is any one of ethylene glycol, N,N-dimethylformamide, and ethylenediaminetetraacetic acid.
[0017] Furthermore, the microwave hydrothermal reaction temperature in step (3) is 80–120°C, and the reaction time is 0.5–2 h.
[0018] Furthermore, the calcination temperature in step (4) is 400-500℃ and the calcination time is 4h.
[0019] Furthermore, in the bimetallic single-atom / attapulgite composite catalytic material prepared by the above method, the total mass of palladium metal and transition metal accounts for 0.1% to 0.15% of the mass fraction of modified attapulgite.
[0020] The present invention also provides an application of the bimetallic single-atom / attapulgite composite catalytic material prepared by the above method. The catalytic material is placed in the quartz tube of the evaluation device, toluene is bubbled with N2, and air is used as the balance gas. At the same time, the reaction device is introduced, and then the reactor is heated to catalytically oxidize and degrade toluene and evaluate its catalytic activity.
[0021] Compared with the prior art, the beneficial effects of the present invention are reflected in:
[0022] 1. Attapulgite, as a catalyst support, possesses a unique support effect. This invention modifies attapulgite using hydrogen peroxide, thereby altering the surface functional groups and increasing the number of hydroxyl groups on the attapulgite surface, which is beneficial for the formation of anchored single atoms at active sites. Simultaneously, attapulgite not only prevents the collapse of the supporting structure but also promotes the activation of surface oxygen by facilitating electron transfer to the support. Furthermore, it establishes strong metal-support interactions to stabilize and activate atomically dispersed PdCu species, ensuring that surface single-atom active species do not form oxides.
[0023] 2. The present invention uses a microwave solvothermal method to synthesize composite materials. Under microwave conditions, microwaves cause organic solvent molecules to vibrate. Under this environment, Pd and transition metal atoms M grow in situ on the ATP surface. By generating an alternating electromagnetic field, the temperature of the reaction system can be rapidly increased in a very short time by utilizing the thermal effect of electromagnetic radiation, so that there is less chance of metal agglomeration. As a result, the atomic metal species dominate in the support, which is conducive to the formation of bimetallic single-atom catalysts.
[0024] 3. The synergistic effect between Pd and M atoms facilitates the catalytic oxidation of toluene, with the transition metal M atom altering the spatial and electronic properties of the Pd subatomic atom. This unique diatomic structure promotes the adsorption and dissociation of toluene, ultimately changing the reaction pathway and lowering the reaction barrier for the catalytic oxidation of toluene. Attached Figure Description
[0025] Figure 1 The XRD pattern of the PdCu / ATP bimetallic single-atom catalyst prepared in Example 1;
[0026] Figure 2 HAADF-STEM image of the PdCu / ATP bimetallic single-atom catalyst prepared in Example 1;
[0027] Figure 3 EDS mapping image of PdCu / ATP bimetallic single atoms prepared in Example 1;
[0028] Figure 4 FTIR spectra of attapulgite, modified attapulgite, and PdCu / ATP bimetallic single atoms prepared in Example 1;
[0029] Figure 5 TEM images of the PdCu / ATP non-bimetallic single-atom catalysts prepared for Comparative Examples 1, 3, 4, 5, and 6; where (a) is Comparative Example 1; (b) is Comparative Example 3; (c) is Comparative Example 4; (d) is Comparative Example 5; and (e) is Comparative Example 6. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to the embodiments:
[0031] Example 1
[0032] (1) Weigh 1.5g of purified attapulgite and immerse it in 100mL of 30% hydrogen peroxide solution. Place it in a water bath at 25℃ and stir for 1h. Then filter, wash and dry to obtain modified attapulgite, denoted as H-ATP.
[0033] (2) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O (3.33 mg by mass) and 0.0125 mmol of Cu(NO3)2·5H2O (3.12 mg by mass) in 40 mL of ethylene glycol solution, dissolve by sonication, add 1.4 g of modified attapulgite from (1), and stir thoroughly until homogeneous to obtain a mixed solution;
[0034] (3) Transfer the mixture obtained in step (2) to a 100 mL reactor, place it in a microwave chemical reactor, react at 80 °C for 0.5 h, cool after the reaction is finished, collect the product by centrifugation, wash with water 3 times and alcohol once, and vacuum dry at 60 °C overnight.
[0035] (4) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain a 0.15% PdCu / ATP bimetallic single-atom catalyst.
[0036] XRD patterns as follows Figure 1 As shown: the characteristic diffraction peaks of ATP appear in the PdCu / ATP composite material, while no peaks are observed for Pd and Cu elements, indicating that the particle size of Pd and Cu in this composite material is very small, possibly forming single atoms; furthermore, the HAADF-STEM and EDS mapping images of the PdCu / ATP sample are shown below. Figure 2 and 3 As shown in the figure, Pd and Cu single atoms are relatively uniformly combined with attapulgite, which is consistent with the XRD results. Figure 4 The infrared spectrum shown indicates that the number of hydroxyl groups on the surface of attapulgite significantly increased after hydrogen peroxide modification, while the number of hydroxyl groups decreased significantly after loading PdCu single atoms. This suggests that the increased hydroxyl groups after modification promoted the anchoring of single atoms and enhanced the formation of single-atom catalysts. Figure 5 The images show the spectra of non-bimetallic single-atom catalysts prepared by different methods, with PdCu agglomerated in the form of nanoparticles on the surface of attapulgite.
[0037] This invention also provides a method for using PdM / ATP catalyst for the thermocatalytic degradation of toluene.
[0038] The method is as follows: 0.75g of the PdCu / ATP catalyst obtained in Example 1 is placed in the quartz tube of the evaluation device. Toluene is bubbled with N2, and air is used as the equilibrium gas. The reaction device is simultaneously purged with air to test the initial concentration (1500ppm). The reactor temperature is then increased, and the real-time concentration is recorded every 10°C. The degradation rate of toluene is calculated. Generally, the temperature at which the degradation rate reaches 90% is used to evaluate the ability to degrade toluene, i.e., T. 90 .
[0039] The above method was used to test the T of the PdM / ATP catalyst in the degradation of toluene. 90 The temperature is 160℃.
[0040] Example 2
[0041] (1) Weigh 1.5g of purified attapulgite and dissolve it in 100mL of 30% hydrogen peroxide solution. Place it in a water bath at 25℃ and stir for 1h. Then filter, wash and dry to obtain modified attapulgite.
[0042] (2) Dissolve 0.00625 mmol of Pd(NO3)2·2H2O (1.67 mg by mass) and 0.00625 mmol of Cu(NO3)2·5H2O (1.56 mg by mass) in 40 mL of ethylene glycol solution, dissolve by sonication, add 1 g of modified attapulgite from (1), and stir thoroughly until homogeneous to obtain a mixed solution;
[0043] (3) Transfer the mixture from (2) to a 100 mL reactor, place it in a microwave chemical reactor, react at 80 °C for 0.5 h, cool after the reaction is complete, collect the product by centrifugation, wash with water three times and alcohol once, and dry under vacuum at 60 °C overnight.
[0044] (4) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain a 0.1% PdCu / ATP bimetallic single-atom catalyst.
[0045] (5) The T value of the catalyst obtained in Example 2 during the degradation of toluene was measured using the method of Example 1. 90 It is 168℃.
[0046] Example 3
[0047] (1) Weigh 1.5g of purified attapulgite and dissolve it in 100mL of 30% hydrogen peroxide solution. Place it in a water bath at 25℃ and stir for 1h. Then filter, wash and dry to obtain modified attapulgite.
[0048] (2) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O (3.33 mg by mass) and 0.0125 mmol of Cu(NO3)2·5H2O (3.12 mg by mass) in 40 mL of ethylene glycol solution, dissolve by sonication, add 1.4 g of modified attapulgite from (1), and stir thoroughly until homogeneous to obtain a mixed solution;
[0049] (3) Transfer the mixture from (2) to a 100 mL reactor, place it in a microwave chemical reactor, and react at 120 °C for 0.5 h. After the reaction is complete, cool it, centrifuge to collect the product, wash it with water three times and alcohol once, and vacuum dry it overnight at 60 °C.
[0050] (4) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain a 0.15% PdCu / ATP bimetallic single-atom catalyst.
[0051] (5) The catalyst obtained in Example 3 was tested for T during the degradation of toluene using the method of Example 1. 90 The temperature is 175℃.
[0052] Example 4
[0053] (1) Weigh 1.5g of purified attapulgite and dissolve it in 100mL of 30% hydrogen peroxide solution. Place it in a water bath at 25℃ and stir for 1h. Then filter, wash and dry to obtain modified attapulgite.
[0054] (2) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O (3.33 mg by mass) and 0.0125 mmol of Fe(NO3)3·9H2O (5.05 mg by mass) in 40 mL of N,N-dimethylformamide solution, dissolve by sonication, add 1.4 g of modified attapulgite from (1), and stir thoroughly until homogeneous to obtain a mixed solution;
[0055] (3) Transfer the mixture from (2) to a 100 mL reactor, place it in a microwave chemical reactor, react at 80 °C for 2 h, cool after the reaction is complete, collect the product by centrifugation, wash with water 3 times and alcohol once, and dry under vacuum at 60 °C overnight.
[0056] (4) The dried product was placed in a muffle furnace and calcined at 400°C for 4 hours; the sample was collected and ground thoroughly to obtain a 0.15% PdFe / ATP bimetallic single-atom catalyst.
[0057] (5) The catalyst obtained in Example 4 was tested for T in the degradation of toluene using the method of Example 1. 90 It is 163℃.
[0058] Example 5
[0059] (1) Weigh 1.5g of purified attapulgite and dissolve it in 100mL of 30% hydrogen peroxide solution. Place it in a water bath at 25℃ and stir for 1h. Then filter, wash and dry to obtain modified attapulgite.
[0060] (2) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O (3.33 mg by mass) and 0.0125 mmol of Co(NO3)2·6H2O (3.63 mg by mass) in 40 mL of ethylene glycol solution, sonicate to dissolve, add 1.4 g of modified attapulgite from (1), and stir thoroughly until homogeneous to obtain a mixed solution;
[0061] (3) Transfer the mixture from (2) to a 100 mL reactor, place it in a microwave chemical reactor, react at 80 °C for 0.5 h, cool after the reaction is complete, collect the product by centrifugation, wash with water three times and alcohol once, and dry under vacuum at 60 °C overnight.
[0062] (4) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain a 0.15% PdCo / ATP bimetallic single-atom catalyst.
[0063] (5) The catalyst obtained in Example 5 was tested for T during the degradation of toluene using the method of Example 1. 90 It is 164℃.
[0064] Comparative Example 1
[0065] The difference between this comparative example and Example 1 is that the calcination temperature in step (4) is 600℃. All other steps and parameters are the same as in Example 1, resulting in the preparation of a comparative sample of 0.15% PdCu / ATP non-bimetallic single-atom catalyst. The reason for this difference may be that the excessively high calcination temperature is not conducive to the dispersion of metal elements on attapulgite, easily leading to agglomeration and the formation of nanoparticles.
[0066] The method of Example 1 was used to test the T value of the catalyst in Example 1 during the degradation of toluene. 90 It reaches as high as 276℃.
[0067] Comparative Example 2
[0068] The difference between this comparative example and Example 1 is that step (2) is replaced with "dissolving 0.025 mol of Pd(NO3)2·2H2O in 40 mL of ethylene glycol solution, sonicating to dissolve, adding 1.8 g of modified attapulgite, and stirring thoroughly until homogeneous to obtain a mixed solution". Other steps and parameters are the same as in Example 1, and the comparative sample 0.15% Pd / ATP single-atom catalyst is prepared.
[0069] The method of Example 1 was used to test the T value of the catalyst in Example 2 during the degradation of toluene. 90 It reached a temperature as high as 283℃.
[0070] Comparative Example 3
[0071] The difference between this comparative example and Example 1 is that the ethylene glycol solution in step (2) is replaced with a distilled aqueous solution. All other steps and parameters are the same as in Example 1, resulting in the preparation of the comparative sample 0.15% PdCu / ATP non-bimetallic single-atom catalyst. The reason may be that the organic solvent stabilizes the surface groups of attapulgite during microwave synthesis, while distilled water cannot stabilize these groups, thus preventing the formation of single-atom sites on the attapulgite surface.
[0072] The method of Example 1 was used to test the T value of the catalyst in Example 3 during the degradation of toluene. 90 It reaches as high as 277℃.
[0073] Comparative Example 4
[0074] The difference between this comparative example and Example 1 is the absence of a microwave chemical reactor reaction. Specifically, step (3) is replaced by "directly centrifuging the mixture obtained in step (2), collecting the product after centrifugation, washing it three times with water and once with alcohol, and then vacuum drying it overnight at 60°C." Other steps and parameters are the same as in Example 1, resulting in the preparation of a comparative sample of 0.15% PdCu / ATP non-bimetallic single-atom catalyst. The reason for this may be the lack of a microwave reaction; catalysts synthesized through ordinary impregnation have poor surface atomic dispersion and are prone to agglomeration during calcination, forming nanoparticles.
[0075] The T value of the catalyst in Example 4 during the degradation of toluene was tested using the method described in Example 1. 90 Temperatures can reach as high as 295°C.
[0076] Comparative Example 5
[0077] This comparative example is intended to highlight the effect of modification on the synthesis of single-atom catalysts from attapulgite. The specific operations are as follows:
[0078] (1) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O and 0.0125 mmol of Cu(NO3)2·5H2O in 40 mL of ethylene glycol solution, sonicate to dissolve, add 1.4 g of unmodified attapulgite, and stir thoroughly until homogeneous to obtain a mixed solution.
[0079] (2) Transfer the mixture to a 100mL reactor, place it in a microwave chemical reactor, react at 80℃ for 0.5h, cool after the reaction is finished, collect the product by centrifugation, wash with water 3 times and alcohol once, and vacuum dry at 60℃ overnight.
[0080] (3) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain the control sample 0.15% PdCu / ATP non-bimetallic single-atom catalyst. The reason may be that the unmodified attapulgite surface has fewer hydroxyl groups, which is not conducive to the dispersion and anchoring of single atoms.
[0081] The method of Example 1 was used to test the T value of the catalyst in Example 5 during the degradation of toluene. 90 It reaches as high as 286℃.
[0082] Comparative Example 6
[0083] This comparative example is intended to highlight the effect of hydrogen peroxide modification on the synthesis of single-atom catalysts from attapulgite. The specific operation is as follows:
[0084] (1) Weigh 1.5g of purified attapulgite and immerse it in 100mL of 3mol / L hydrochloric acid solution. Heat it in an 80℃ water bath, wash it three times with deionized water, and dry it in an oven to obtain acid-modified attapulgite.
[0085] (2) Dissolve 0.0125 mmol of Pd(NO3)2·2H2O and 0.0125 mmol of Cu(NO3)2·5H2O in 40 mL of ethylene glycol solution, sonicate to dissolve, add 1.4 g of acid-modified attapulgite, and stir thoroughly until homogeneous to obtain a mixed solution.
[0086] (3) Transfer the mixture to a 100mL reactor, place it in a microwave chemical reactor, react at 80℃ for 0.5h, cool after the reaction is finished, collect the product by centrifugation, wash with water 3 times and alcohol once, and vacuum dry at 60℃ overnight.
[0087] (4) The dried product was placed in a muffle furnace and calcined at 500°C for 4 hours; the sample was collected and ground thoroughly to obtain the control sample 0.15% PdCu / ATP non-bimetallic single-atom catalyst. The reason may be that acid-modified attapulgite is easy to etch the surface, producing larger pits, which is not conducive to the dispersion and anchoring of single atoms on the surface of attapulgite, and cannot form single-atom sites.
[0088] The method of Example 1 was used to test the T value of the catalyst in Example 6 during the degradation of toluene. 90 It reached a high of 293℃.
Claims
1. A method for preparing a bimetallic single-atom / attapulgite composite catalytic material, characterized in that, The preparation method includes the following steps: (1) Attapulgite was immersed in an aqueous solution of hydrogen peroxide, stirred in a water bath, filtered, washed and dried to obtain modified attapulgite. (2) Weigh palladium salt and transition metal salt and add them to an organic solvent. After ultrasonic dissolution, add the modified attapulgite from step (1) and stir thoroughly until homogeneous to obtain a mixture. (3) Transfer the mixture from step (2) to a reaction vessel and place it in a microwave chemical reactor for microwave hydrothermal reaction. After the reaction is completed, cool, centrifuge, wash, and dry. (4) Place the dried product from step (3) into a muffle furnace, calcine it, collect the sample and grind it thoroughly to obtain a bimetallic single-atom / attapulgite composite catalytic material. In step (2), the transition metal salt is any one of Cu, Fe, or Co salt; in step (4), the calcination temperature is 400–500 °C and the calcination time is 4 h.
2. The preparation method of the bimetallic single-atom / attapulgite composite catalytic material according to claim 1, characterized in that, The mass fraction of the hydrogen peroxide aqueous solution in step (1) is 30%; the solid-liquid ratio of the attapulgite to the hydrogen peroxide aqueous solution is 1.5g:100mL.
3. The preparation method of the bimetallic single-atom / attapulgite composite catalytic material according to claim 1, characterized in that, The molar ratio of palladium salt and transition metal salt in step (2) is 1:1; the ratio of the sum of the molars of palladium salt and transition metal salt to the volume of organic solvent is 0.0125 to 0.025 mmol: 40 mL.
4. The preparation method of the bimetallic single-atom / attapulgite composite catalytic material according to claim 1, characterized in that, The organic solvent mentioned in step (2) is any one of ethylene glycol, N,N-dimethylformamide, and ethylenediaminetetraacetic acid.
5. The preparation method of the bimetallic single-atom / attapulgite composite catalytic material according to claim 1, characterized in that, The microwave hydrothermal reaction temperature in step (3) is 80-120℃ and the reaction time is 0.5-2h.
6. The bimetallic single-atom / attapulgite composite catalytic material prepared by the method according to any one of claims 1-5, characterized in that, In the bimetallic single-atom / attapulgite composite catalytic material, the total mass of palladium metal and transition metals accounts for 0.1% to 0.15% of the mass fraction of modified attapulgite.
7. The application of the bimetallic single-atom / attapulgite composite catalytic material according to claim 6, characterized in that, The bimetallic single-atom / attapulgite composite catalytic material is used for the catalytic oxidation and degradation of VOCs.