Preparation method of efficient Pd-based bimetallic catalyst and application of efficient Pd-based bimetallic catalyst in air purification

Abstract

According to the preparation method of the efficient Pd-based bimetallic catalyst and the application of the efficient Pd-based bimetallic catalyst in air purification, Ba < 2 + > and Pd < 2 + > are introduced, the loading capacity and dispersity of Pd < 2 + > are improved, the formaldehyde degradation performance is improved, meanwhile, compared with a traditional high-loading-capacity Pd-based bimetallic catalyst, the usage amount of precious metal Pd is effectively reduced, and the cost is reduced. Therefore, the preparation cost of the Pd-based bimetallic catalyst is reduced. By adopting a step-by-step Ba < 2 + > and Pd < 2 + > adsorption treatment mode, Pd < 2 + > can be more uniformly distributed on the TiO2 carrier and has high dispersity, and more Pd active sites can be exposed and participate in a catalytic reaction during application, so that the utilization rate of Pd is increased, and material waste is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of catalyst preparation and application, and more specifically, to a preparation method of a highly efficient Pd-based bimetallic catalyst and its application in air purification. Background Art

[0002] Formaldehyde is one of the most typical indoor pollutants and poses a serious threat to human health. Catalysts loaded with noble metals (Pt, Au, Pd) exhibit excellent formaldehyde degradation performance at room temperature. However, the high cost limits their widespread application. Among them, Pd has a certain cost advantage compared to Pt and Au.

[0003] Among the current Pd-based catalysts with the ability to degrade formaldehyde at room temperature, there is a problem of high Pd loading but low dispersion, resulting in most Pd active sites being unable to participate in the reaction and causing material waste. Summary of the Invention

[0004] To solve the above problems, the present invention provides a preparation method of a highly efficient Pd-based bimetallic catalyst and its application in air purification. By introducing Ba 2+ and Pd 2+ , and improving the loading and dispersion of Pd 2+ , while improving the formaldehyde degradation performance, compared with the traditional high-loading Pd-based bimetallic catalyst, the usage amount of the noble metal Pd is effectively reduced, thereby reducing the preparation cost of the Pd-based bimetallic catalyst. By adopting a stepwise adsorption method for treating Ba 2+ and Pd 2+ , Pd 2+ can be more uniformly distributed on the TiO2 support, with high dispersion. During application, more Pd active sites can be exposed and participate in the catalytic reaction, improving the utilization rate of Pd and reducing material waste.

[0005] In a first aspect, the present invention provides a highly efficient Pd-based bimetallic catalyst, which is composed of TiO2 loaded with Ba 2+ and Pd 2+ . The loading amount of Ba 2+ in the Pd-based bimetallic catalyst is (15-30) wt.%, and the loading amount of Pd 2+ is (0.05-2) wt.%.

[0006] Optionally, the loading amount of Ba 2+ in the Pd-based bimetallic catalyst is (15-30) wt.%, and the loading amount of Pd 2+ is (0.5-2) wt.%.

[0007] Second aspect, the present invention provides a method for preparing the above-mentioned high-efficiency Pd-based bimetallic catalyst according to the first aspect, and the preparation method includes: S1. Disperse the TiO2 support in deionized water and stir to obtain a suspension; S2. Dissolve the barium salt and palladium salt in the deionized water and stir to obtain a mixed solution; S3. Mix the mixed solution with the suspension and stir for 0.1 h to 2 h to load Ba 2+ and Pd 2+ on the TiO2. After the obtained solid product is dried overnight, it is calcined at 300 °C to 600 °C for 1 h to 4 h and ground to obtain a Pd-based bimetallic catalyst; S4. Repeat steps S1-S3 until a Pd-based bimetallic catalyst with a Ba 2+ loading of (15-30) wt.% and a Pd 2+ loading of (0.05-2) wt.% is obtained; Among them, when repeating step S1, the Pd-based bimetallic catalyst prepared in step S3 is dissolved in the deionized water to prepare the suspension.

[0008] Optionally, the barium salt is barium nitrate or barium carbonate.

[0009] Optionally, the palladium salt is palladium nitrate or palladium chloride.

[0010] Optionally, in step S2, the mass ratio of the barium salt to the palladium salt is (5-5.5):(0.1-0.5).

[0011] Optionally, in step S3, the particle size of the Pd-based bimetallic catalyst is 0.1 mm to 2 mm.

[0012] Optionally, in step S3, the loading of Ba 2+ on the Pd-based bimetallic catalyst is (5-5.5) wt.%, and the loading of Pd 2+ is (0.1-0.5) wt.%.

[0013] Optionally, in step S4, the particle size of the Pd-based bimetallic catalyst is 40 mesh to 60 mesh.

[0014] Third aspect, the present invention provides an application of a high-efficiency Pd-based bimetallic catalyst in air purification. The Pd-based bimetallic catalyst is the one described in the first aspect above or obtained by the preparation method described in the second aspect above. The Pd-based bimetallic catalyst is suitable for decomposing formaldehyde in the air at room temperature.

[0015] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The present invention provides a Pd-based bimetallic catalyst, which is composed of TiO2 supporting Ba 2+ and Pd 2+ . Among them, the loading amount of Ba 2+ in the Pd-based bimetallic catalyst is (15-30) wt.%, and the loading amount of Pd 2+ is (0.05-2) wt.%. By precisely controlling the loading amounts of Ba 2+ and Pd 2+ , the present invention greatly reduces the dependence on the noble metal Pd. While improving the catalytic performance of the catalyst, it significantly reduces the preparation cost of the catalyst. Moreover, the co-introduction of Ba 2+ and Pd 2+ can achieve the formation of more new active sites by changing the surface properties and electronic structure of the catalyst, thereby enhancing the adsorption and conversion ability of the catalyst to formaldehyde molecules, enabling efficient degradation at a lower temperature, and having a higher catalytic reaction rate and efficiency; 2. The present invention provides a preparation method for a Pd-based bimetallic catalyst. During implementation, the TiO2 support is dispersed in deionized water and stirred to obtain a suspension. The barium salt and palladium salt are dissolved in deionized water and stirred to obtain a mixed solution. The mixed solution is mixed with the suspension and stirred for 0.1 h to 2 h to load Ba 2+ and Pd 2+ onto TiO2. The obtained solid product is dried overnight and then calcined at 200 °C to 600 °C for 1 h to 4 h, and ground to obtain a Pd-based bimetallic catalyst; repeat the above steps until a Pd-based bimetallic catalyst with a Ba 2+ loading amount of (15-30) wt.% and a Pd 2+ loading amount of (0.05-2) wt.% is obtained. By repeating the above steps and precisely adjusting the amounts of the barium salt and palladium salt in each operation, the present invention can accurately control the loading amounts of Ba 2+ and Pd 2+ on the TiO2 support, enabling Ba 2+ and Pd 2+ to be uniformly and firmly loaded on the TiO2 support, forming highly dispersed active sites. The calcination step helps to further stabilize the structure of the Pd-based bimetallic catalyst and promote the formation and distribution of the active components. Therefore, when applied, it can improve the degradation efficiency and stability of the Pd-based bimetallic catalyst to formaldehyde; at the same time, through the grinding step, a Pd-based bimetallic catalyst powder with good dispersibility and particle size can be obtained, enabling more Ba 2+ and Pd 2+ to be uniformly dispersed on the TiO2 support during subsequent processing; 3. The present invention provides an application of a Pd-based bimetallic catalyst, which is suitable for decomposing formaldehyde at room temperature. Since the Ba 2+ and Pd 2+ in the Pd-based bimetallic catalyst have a higher dispersion degree, the catalyst has more active sites, so it has higher catalytic activity and can quickly convert formaldehyde into harmless substances, thereby significantly reducing the indoor formaldehyde concentration and improving the indoor air quality; the catalyst can carry out catalytic reactions at room temperature, avoiding the need for high-temperature treatment, reducing energy consumption and potential secondary pollution, and conforming to the development trend of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 Shows the flowchart of the preparation method of the Pd-based bimetallic catalyst proposed by the embodiment of the present application; Figure 2 Shows the TEM of the Pd dispersion degree in the catalyst prepared in Comparative Example 1 of the present application; Figure 3 Shows the TEM of the Pd dispersion degree in the catalyst prepared in Example 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0019] In the drawings, sometimes for clarity, the sizes of the components, the thicknesses of the layers or the regions may be exaggerated. Therefore, any implementation of the present disclosure is not necessarily limited to the sizes shown in the figures, and the shapes and sizes of the components in the figures do not reflect the true proportions. In addition, the drawings schematically show ideal examples, and any implementation of the present disclosure is not limited to the shapes or values shown in the drawings.

[0020] In related technologies, formaldehyde is one of the most typical indoor pollutants and poses a serious threat to human health. Catalysts loaded with noble metals (Pt, Au, Pd) exhibit excellent formaldehyde degradation performance at room temperature. However, the high cost limits their widespread application. Compared with Pt and Au, Pd has a certain cost advantage. Currently, the main method for preparing Pd-based catalysts with the ability to degrade formaldehyde at room temperature is the impregnation-calcination method.

[0021] The impregnation-calcination method mainly includes: placing a certain amount of carrier in deionized water and stirring it into a suspension, then adding the corresponding amounts of Ba salt and Pd salt solutions to the deionized water. After a clear solution is formed, it is poured into the above suspension. After stirring for 1 h, the suspension is transferred to a rotary evaporator to remove the excess water. The obtained solid sample is dried overnight in an oven at 100 °C and then calcined in a muffle furnace at 400 °C for 2 h to obtain the Pd catalyst.

[0022] However, the Pd-based catalyst prepared by the impregnation-calcination method has the problems of high Pd loading and low dispersion, resulting in most of the Pd active sites being unable to participate in the reaction and causing material waste.

[0023] Based on the problems existing in the related technologies, the present invention proposes to use TiO2 as the carrier and adopt the impregnation-calcination cycle method to prepare a Pd-based bimetallic catalyst with high dispersion and low noble metal loading, so that Ba 2+ and Pd 2+ can be uniformly and firmly loaded on the TiO2 carrier to form highly dispersed active sites, thereby reducing material waste during application.

[0024] Specifically, the present invention provides a highly efficient Pd-based bimetallic catalyst, which is composed of TiO2 loaded with Ba 2+ and Pd 2+ . The loading amount of Ba 2+ in the Pd-based bimetallic catalyst is (15~30) wt.%, and the loading amount of Pd 2+ is (0.05~2) wt.%.

[0025] Specifically in implementation, by introducing Ba 2+ and Pd 2+ , new active sites can be formed in the Pd-based bimetallic catalyst, and the catalytic ability of the original active sites can be enhanced, thereby improving the degradation efficiency of the Pd-based bimetallic catalyst for formaldehyde. By precisely controlling the loading amounts of Ba 2+ and Pd 2+ , while maintaining the high catalytic performance of the Pd-based bimetallic catalyst, the usage amount of the noble metal Pd can be significantly reduced, thereby reducing the preparation cost of the Pd-based bimetallic catalyst and making the Pd-based bimetallic catalyst more economical and practical in actual applications.

[0026] It should be noted that the loading of Ba 2+ and Pd 2+ also helps to stabilize the structure of the Pd-based bimetallic catalyst, prevent the agglomeration or deactivation of the Pd-based bimetallic catalyst during the reaction, and thus extend the service life and stability of the Pd-based bimetallic catalyst.

[0027] In specific implementation, the loading of Ba 2+ in the Pd-based bimetallic catalyst can be 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.%, 30 wt.%; The loading of Pd 2+ can be 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, 2 wt.%.

[0028] In some embodiments, the loading of Ba 2+ in the Pd-based bimetallic catalyst is (22-26) wt.%, and the loading of Pd 2+ is (0.5-1.5) wt.%.

[0029] In specific implementation, by further precisely setting the loadings of Ba 2+ and Pd 2+ in the Pd-based bimetallic catalyst, the amount of precious metal used can be reduced, thereby further reducing the preparation cost of the Pd-based bimetallic catalyst, making it more economically feasible in practical applications, and facilitating large-scale promotion and application. It also helps to improve the distribution of active sites in the Pd-based bimetallic catalyst, thereby increasing the degradation efficiency and rate of the Pd-based bimetallic catalyst for formaldehyde, enabling the Pd-based bimetallic catalyst to decompose formaldehyde more efficiently at room temperature.

[0030] In specific implementation, Ba in the Pd-based bimetallic catalyst 2+The loading amount can be 22 wt.%, 22.1 wt.%, 22.3 wt.%, 22.5 wt.%, 22.7 wt.%, 22.9 wt.%, 23.1 wt.%, 23.5 wt.%, 23.8 wt.%, 24.1 wt.%, 24.5 wt.%, 24.7 wt.%, 24.9 wt.%, 25.1 wt.%, 25.3 wt.%, 25.6 wt.%, 25.8 wt.%, 26 wt.%. Pd 2+ The loading amount can be 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%.

[0031] The present invention also provides a preparation method of the above-mentioned high-efficiency Pd-based bimetallic catalyst. See Figure 1 , and the preparation method includes: S1. Disperse the TiO2 support in deionized water and stir to obtain a suspension; S2. Dissolve barium salt and palladium salt in the deionized water and stir to obtain a mixed solution; S3. Mix the mixed solution with the suspension and stir for 0.1 h to 2 h to load Ba 2+ and Pd 2+ on the TiO2. After the obtained solid product is dried overnight, it is calcined at 300 °C to 600 °C for 1 h to 4 h, and ground to obtain the Pd-based bimetallic catalyst; S4. Repeat steps S1 - S3 until the Pd-based bimetallic catalyst with a Ba 2+ loading amount of (15 - 30) wt.% and a Pd 2+ loading amount of (0.05 - 2) wt.% is obtained; Wherein, when repeating step S1, the Pd-based bimetallic catalyst prepared in step S3 is dissolved in the deionized water to prepare the suspension.

[0032] It should be noted that the TiO2 support refers to TiO2 with a porous structure; a TiO2 microsphere with a porous hierarchical structure can be obtained by microwave-assisted solvothermal method. This microsphere is composed of ultrathin nanosheets and has a high specific surface area and a three-dimensional porous structure; The formation of the suspension means that since TiO2 is insoluble in deionized water, after it is dispersed in deionized water, the TiO2 particles exist in a suspended state in the deionized water; Overnight drying includes: first, transfer the suspension after stirring in step S2 for 0.1 h to 2 h to a rotary evaporator to remove excess water, and then subject the obtained solid product to overnight drying in an oven at 100 °C to obtain a dried solid product; for example, the time for overnight drying is 12 h to 24 h.

[0033] In specific implementation, first disperse an appropriate amount of TiO2 support in deionized water. Since the solubility of the TiO2 support is extremely low, after dispersing it in deionized water, a colloidal liquid is formed, and after refining, a suspension is obtained. Then, put palladium salt and barium salt into deionized water in sequence, and after stirring, make the palladium salt and barium salt fully dissolve in deionized water to obtain a mixed solution containing Ba 2+ and Pd 2+ . Pour the mixed solution into the suspension to mix Ba 2+ and Pd 2+ with the TiO2 support. Through the adsorption of the TiO2 support, make Ba 2+ and Pd 2+ uniformly loaded on the TiO2 support. After the obtained solid product is dried overnight, it is calcined at a high temperature. After calcining for a sufficient time, a Pd-based bimetallic catalyst is obtained. Then, replace the TiO2 support in step S1 with the obtained Pd-based bimetallic catalyst, disperse the Pd-based bimetallic catalyst in deionized water to obtain a new suspension, and then repeat steps S2 - S3 to obtain a new Pd-based bimetallic catalyst. After continuously repeating steps S1 - S3 until a Pd-based bimetallic catalyst with a Ba 2+ loading of (15 - 30) wt.% and a Pd 2+ loading of (0.05 - 2) wt.% is obtained, stop the reaction, and output the Pd-based bimetallic catalyst with a Ba 2+ loading of (15 - 30) wt.% and a Pd 2+ loading of (0.05 - 2) wt.% as the product.

[0034] By repeating steps S1 to S3 and precisely adjusting the amounts of barium salt and palladium salt in each operation, the present invention can accurately control the loadings of Ba 2+ and Pd 2+ on the TiO2 support, reduce the usage amount of the precious metal Pd, and improve the cost-effectiveness. And the distributed loading method enables Ba 2+ and Pd 2+It can be evenly and firmly loaded on the TiO2 support to form highly dispersed active sites. The subsequent calcination step can further stabilize the structure of the catalyst and promote the formation and distribution of the active components. Each operation in the preparation method provided by the present invention is relatively simple and easy to control. Using deionized water as the solvent helps to reduce the influence of impurities on the performance of the catalyst. At the same time, through the grinding step, a Pd-based bimetallic catalyst powder with good dispersibility and particle size can be obtained, which is convenient for subsequent application and treatment, enabling highly dispersed loading for each repeated loading.

[0035] In some embodiments, the barium salt is barium nitrate or barium carbonate.

[0036] In specific implementation, by selecting barium nitrate or barium carbonate as the barium source and combining with repeated preparation steps, the present invention can precisely adjust the loading amounts of Ba 2+ and Pd 2+ on the TiO2 support, ensure the uniform distribution of the active components in the catalyst, thereby improving the performance of the catalyst and enhancing the degradation efficiency and stability of formaldehyde.

[0037] Barium nitrate and barium carbonate have the advantages of being easily obtainable and relatively low in cost, providing more raw material choices for the preparation of the Pd-based bimetallic catalyst. Moreover, barium nitrate and barium carbonate do not produce harmful by-products during the preparation process, reducing energy consumption and potential secondary pollution, which conforms to the concepts of green chemistry and sustainable development.

[0038] In some embodiments, the palladium salt is palladium nitrate or palladium chloride.

[0039] By selecting palladium nitrate or palladium chloride as the palladium source, the present invention has the advantages of being easily obtainable and relatively low in cost. At the same time, these two palladium salts are easily soluble and dispersed during the preparation process, which is beneficial to the uniform loading of the active components on the support.

[0040] In some embodiments, in step S2, the mass ratio of the barium salt to the palladium salt is (5 - 5.5):(0.1 - 0.5).

[0041] By precisely setting the mass ratio of the barium salt to the palladium salt, the present invention enables the ratio of Ba 2+ and Pd 2+ in the prepared Pd-based bimetallic catalyst to reach the optimum, thereby further enhancing the activity of the catalyst, forming more active sites, and improving the adsorption and degradation ability of the Pd-based bimetallic catalyst for formaldehyde. The Pd-based bimetallic catalyst with this ratio of active components can degrade formaldehyde more rapidly under the same reaction conditions, with higher catalytic efficiency. It can not only reduce the reaction time but also maintain high-efficiency degradation while reducing energy consumption and costs.

[0042] In specific implementation, the mass ratio of the barium salt to the palladium salt can be 5:(0.1 - 0.5), 5.1:(0.1 - 0.5), 5.2:(0.1 - 0.5), 5.3:(0.1 - 0.5), 5.4:(0.1 - 0.5), 5.5:(0.1 - 0.5); or, (5 - 5.5):0.1, (5 - 5.5):0.2, (5 - 5.5):0.3, (5 - 5.5):0.4, (5 - 5.5):0.5; or, 5:0.1, 5.1:0.2, 5.2:0.3, 5.3:0.4, 5.5:0.5.

[0043] In some embodiments, in step S3, the particle size of the Pd-based bimetallic catalyst is 0.1 mm - 2 mm.

[0044] In specific implementation, the particle size of the Pd-based bimetallic catalyst can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm.

[0045] By setting the Pd-based bimetallic catalyst to have a small particle size, the present invention enables the Pd-based bimetallic catalyst particles to have a larger specific surface area, and Ba 2+ and Pd 2+ ions can be more uniformly attached to the surface of the TiO2 support during the loading process, thereby increasing the number of active sites of the Pd-based bimetallic catalyst, enhancing the dispersion between the Pd-based bimetallic catalyst particles, and reducing the occurrence of agglomeration. During the cyclic preparation process of step S4, this dispersion advantage can be maintained each time steps S1 to S3 are repeated, ensuring that the finally prepared Pd-based bimetallic catalyst maintains a high utilization rate of active sites in subsequent catalytic reactions, and improving the catalytic reaction rate and conversion rate. Due to the higher catalytic efficiency and stability of the small particle size Pd-based bimetallic catalyst, under the condition of meeting the same catalytic performance requirements, the present invention can also reduce the usage amount of the precious metal Pd, not only reducing the preparation cost of the Pd-based bimetallic catalyst, but also reducing the waste of precious metal resources, which conforms to the concepts of green chemistry and sustainable development.

[0046] In some embodiments, in step S3, the loading amount of Ba 2+ on the Pd-based bimetallic catalyst is (5 - 5.5) wt.%, and the loading amount of Pd 2+ is (0.1 - 0.5) wt.%.

[0047] In specific implementation, Ba on the Pd-based bimetallic catalyst2+ The loading amount of [substance] can be 5 wt.%, 5.12 wt.%, 5.14 wt.%, 5.16 wt.%, 5.18 wt.%, 5.2 wt.%, 5.22 wt.%, 5.24 wt.%, 5.26 wt.%, 5.28 wt.%, 5.3 wt.%, 5.32 wt.%, 5.34 wt.%, 5.36 wt.%, 5.38 wt.%, 5.4 wt.%, 5.42 wt.%, 5.43 wt.%, 5.44 wt.%, 5.46 wt.%, 5.48 wt.%, 5.5 wt.%; Pd 2+ The loading amount of [substance] can be 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%.

[0048] In the present invention, by precisely adjusting the loading amounts of Ba 2+ and Pd 2+ , while ensuring the activity of the Pd-based bimetallic catalyst, its catalytic performance is further improved. Among them, the introduction of Ba 2+ also helps to improve the acidity and basicity of the Pd-based bimetallic catalyst and enhance its adsorption capacity for formaldehyde molecules, while an appropriate amount of Pd 2+ acts as the active center to catalyze the decomposition reaction of formaldehyde, so that the degradation efficiency of the Pd-based bimetallic catalyst for formaldehyde at room temperature is significantly improved. The appropriate loading amount also helps to reduce the agglomeration and deactivation phenomena between the particles of the Pd-based bimetallic catalyst and improve the stability of the Pd-based bimetallic catalyst. The uniform distribution and firm attachment of Ba 2+ and Pd 2+ on the TiO2 support enable the catalyst to still maintain high activity after multiple cycles of use, thereby extending the service life of the Pd-based bimetallic catalyst and reducing the replacement frequency and cost.

[0049] In some embodiments, in the step S4, the particle size of the Pd-based bimetallic catalyst is 40 mesh to 60 mesh.

[0050] Specifically in implementation, the particle size of the Pd-based bimetallic catalyst can be 40 mesh, 50 mesh, 60 mesh.

[0051] By controlling the particle size of the Pd-based bimetallic catalyst within the range of 40 mesh to 60 mesh in the present invention, it helps to improve the activity and selectivity of the catalyst, enables it to have an appropriate specific surface area and pore structure, and can more effectively adsorb and catalyze formaldehyde molecules, thereby increasing the rate and conversion rate of the catalytic reaction. At the same time, the appropriate particle size also helps to reduce the occurrence of side reactions and improve the selectivity of the catalyst.

[0052] The present invention also provides an application of an efficient Pd-based bimetallic catalyst in air purification, and the Pd-based bimetallic catalyst is suitable for decomposing formaldehyde in the air at room temperature.

[0053] The Pd-based bimetallic catalyst provided by the present invention can efficiently decompose formaldehyde in the air at room temperature, which solves the problem that traditional catalysts need high temperature or specific conditions to exert their catalytic effects. The efficient catalysis at room temperature makes this catalyst more convenient and practical in practical applications, and can be widely applied to places such as homes, offices, hospitals, schools, etc. that need to improve indoor air quality. Since this catalyst can work at room temperature, no additional heating or cooling equipment is required, thus reducing energy consumption and operating costs. This is particularly important for long-term operation and large-scale application scenarios, and helps to achieve energy conservation, emission reduction and sustainable development.

[0054] To enable those skilled in the art to understand the present invention more clearly, the preparation method of the efficient Pd-based bimetallic catalyst and its application in air purification described in the present invention will be described in detail through the following examples.

[0055] Example 1 (1) Disperse 10 g of TiO2 support in 200 mL of deionized water and stir to obtain a suspension; (2) Dissolve 18.55 mL of 5.12 wt.% barium nitrate and 21.5 mL of 0.2 wt.% palladium nitrate in 100 ml of deionized water, stir until a clear solution is formed, and then obtain a mixed solution; (3) Pour the mixed solution into the suspension and mix, stir for 1 h to load Ba 2+ and Pd 2+ on TiO2, transfer the treated suspension to a rotary evaporator to remove the excess water, and then obtain a solid product; (4) Dry the obtained solid product overnight in an oven at 100 °C, then place it in a muffle furnace and calcine it at 400 °C for 2 h; (5) Grind and crush the calcined material to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (6) Dissolve the Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm in 200 mL of deionized water and stir to obtain a new suspension; (7) Dissolve 18.55 mL of 5.12 wt.% barium nitrate and 21.5 mL of 0.2 wt.% palladium nitrate in 100 mL of deionized water, stir until a clear solution is formed, and then obtain a new mixed solution; (8) Pour the new mixed solution into the new suspension and mix, stir for 1 h to load Ba 2+and Pd 2+ Loaded on TiO2, the treated suspension was transferred to a rotary evaporator to remove the excess water, obtaining a solid product; (9)After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 400 °C for 2 h; (10)The calcined material was ball-milled and pulverized to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (11)Steps (6) - (10) were repeated until a Pd-based bimetallic catalyst with a Ba 2+ loading of 25.8 wt.% and a Pd 2+ loading of 1 wt.% was obtained, denoted as the 25.8Ba-1Pd / TiO2(A) sample.

[0056] Based on Example 1, Comparative Example 1 was set up. Comparative Example 1 included: (1)10 g of TiO2 support was placed in 200 mL of deionized water and stirred into a suspension; (2)18.55 mL of 25.8 wt.% barium nitrate and 21.5 mL of 1 wt.% palladium nitrate were added to deionized water, and after forming a clear solution, a mixed solution was obtained; (3)The mixed solution was poured into the above suspension, stirred for 1 h, then the suspension was transferred to a rotary evaporator to remove the excess water, and the obtained solid sample was dried overnight in an oven at 100 °C; (4)The solid sample dried overnight was placed in a muffle furnace and calcined at 400 °C for 2 h to prepare a Pd-based bimetallic catalyst, denoted as the 25.8 Ba-1Pd / TiO2(B) sample.

[0057] Based on Example 1 and Comparative Example 1, the conversion rate of methane at different reaction times was detected at room temperature, specifically including: 15 mg of the samples prepared in Example 1 and Comparative Example 1, 40 - 60 mesh, were respectively taken and put into a catalyst activity evaluation device. The activity evaluation was carried out in a fixed-bed reactor. The simulated flue gas composition was: 150 ppm HCHO, 20% O2, relative humidity 40%, He as the balance gas, the total flow rate was 200 mL / min, and the reaction space velocity was 760000 h-1. The test results (conversion rate of methane) are shown in Table 1 below.

[0058]

[0059] According to Figure 2 and Figure 3TEM electron microscopy showed that the dispersion of the noble metal Pd in Example 1 was uniform, and the shape and size ratio were close. In contrast, the dispersion of the noble metal Pd in Comparative Example 1 was poor, with obvious agglomeration phenomena.

[0060] It can be obtained from Table 1 that after multiple repeated loading of Ba 2+ and Pd 2+ and repeated calcination, the removal rate of formaldehyde of the Pd-based bimetallic catalyst sample prepared by the preparation method of Example 1 of the present invention was stable at 50% at room temperature, while the removal rate of formaldehyde of the 25.8 Ba-1Pd / TiO2(B) sample catalyst prepared by the preparation method provided in Comparative Example 1 was only 15% at room temperature, proving that the preparation method provided in the examples of the present invention can further improve the catalytic effect of the Pd-based bimetallic catalyst. This is because the Pd-based bimetallic catalyst prepared in Example 1 of the present invention has a high dispersion degree, can provide more active sites during application, and through the introduced Pd 2+ ions, more new active sites are formed in the Pd-based bimetallic catalyst, thus greatly improving the catalytic efficiency.

[0061] Example 2 (1) Disperse 10 g of TiO2 support in 200 mL of deionized water and stir to obtain a suspension; (2) Dissolve 19.06 mL of 1.5 wt.% barium nitrate and 10.75 mL of 0.1 wt.% palladium nitrate in 100 mL of deionized water, stir until a clear solution is formed, and then obtain a mixed solution; (3) Pour the mixed solution into the suspension and mix, stir for 0.1 h to load Ba 2+ and Pd 2+ onto TiO2, transfer the treated suspension to a rotary evaporator to remove the excess water, and then obtain a solid product; (4) Dry the obtained solid product overnight in an oven at 300 °C, then place it in a muffle furnace and calcine it at 400 °C for 4 h; (5) Ball-mill and crush the calcined material to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (6) Dissolve the Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm in 200 mL of deionized water and stir to obtain a new suspension; (7) Dissolve 19.06 mL of 1.5 wt.% barium nitrate and 10.75 mL of 0.1 wt.% palladium nitrate in 100 mL of deionized water, stir until a clear solution is formed, and then obtain a new mixed solution; (8) Pour the new mixed solution into the new suspension and mix, stir for 1 h to load Ba 2+ and Pd2+ Loaded on TiO2, the treated suspension was transferred to a rotary evaporator to remove the excess water, obtaining a solid product; (9) After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 300 °C for 4 h; (10) The calcined material was ball-milled and pulverized to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (11) Repeat steps (6) - (10) until a Pd-based bimetallic catalyst with a Ba 2+ loading of 15 wt.% and a Pd 2+ loading of 1 wt.% was obtained, denoted as the 15Ba-1Pd / TiO2(A) sample.

[0062] Example 3 (1) 10 g of TiO2 support was dispersed in 200 mL of deionized water and stirred to obtain a suspension; (2) 18.55 mL of 5 wt.% barium nitrate and 21.5 mL of 0.2 wt.% palladium nitrate were dissolved in 100 mL of deionized water, and after stirring until a clear solution was formed, a mixed solution was obtained; (3) The mixed solution was poured into the suspension and mixed, stirred for 1 h to load Ba 2+ and Pd 2+ on TiO2, and the treated suspension was transferred to a rotary evaporator to remove the excess water, and then a solid product was obtained; (4) After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 600 °C for 1 h; (5) The calcined material was ball-milled and pulverized to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (6) The Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm was dissolved in 200 mL of deionized water and stirred to obtain a new suspension; (7) 18.55 ml of 5 wt.% barium nitrate and 21.5 mL of 0.2 wt.% palladium nitrate were dissolved in 100 mL of deionized water, and after stirring until a clear solution was formed, a new mixed solution was obtained; (8) The new mixed solution was poured into the new suspension and mixed, stirred for 1 h to load Ba 2+ and Pd 2+ on TiO2, and the treated suspension was transferred to a rotary evaporator to remove the excess water, obtaining a solid product; (9) After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 600 °C for 1 h; (10) The calcined material was ball-milled and pulverized to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (11) Steps (6) - (10) were repeated until a Pd-based bimetallic catalyst with a Ba 2+ loading of 30 wt.% and a Pd 2+ loading of 2 wt.% was obtained, denoted as the 30Ba-2Pd / TiO2(A) sample.

[0063] Example 4 (1) 10 g of TiO2 support was dispersed in 200 mL of deionized water and stirred to obtain a suspension; (2) 20.03 mL of 5.23 wt.% barium nitrate and 12.28 ml of 0.35 wt.% palladium nitrate were dissolved in 100 ml of deionized water. After stirring until a clear solution was formed, a mixed solution was obtained; (3) The mixed solution was poured into the suspension and mixed, and stirred for 1 h to load Ba 2+ and Pd 2+ on TiO2. The treated suspension was transferred to a rotary evaporator to remove the excess water, and then a solid product was obtained; (4) After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 500 °C for 2 h; (5) The calcined material was ball-milled and pulverized to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (6) The Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm was dissolved in 200 mL of deionized water and stirred to obtain a new suspension; (7) 20.03 mL of 5.23 wt.% barium nitrate and 12.28 mL of 0.35 wt.% palladium nitrate were dissolved in 100 mL of deionized water. After stirring until a clear solution was formed, a new mixed solution was obtained; (8) The new mixed solution was poured into the new suspension and mixed, and stirred for 1 h to load Ba 2+ and Pd 2+ on TiO2. The treated suspension was transferred to a rotary evaporator to remove the excess water, and a solid product was obtained; (9) After drying the obtained solid product overnight in an oven at 100 °C, it was placed in a muffle furnace and calcined at 500 °C for 2 h; (10) Grind the calcined material by ball milling to obtain a Pd-based bimetallic catalyst with a particle size of 0.3 - 0.4 mm; (11) Repeat steps (6) to (10) until a Pd-based bimetallic catalyst with a Ba loading of 22.5 wt.% and a Pd loading of 1 wt.% is obtained, denoted as the 22.5Ba-1Pd / TiO2(A) sample. 2+ loading of 22.5 wt.%, Pd 2+ loading of 1 wt.%

[0064] In summary, the Pd-based bimetallic catalyst prepared by the preparation method provided by the present invention has highly dispersed active components, can withstand more stringent reaction conditions during application, and can greatly reduce the dosage of the Pd-based bimetallic catalyst under the same reaction conditions and the same formaldehyde conversion rate, thereby reducing costs.

[0065] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same and similar parts among the embodiments, reference can be made to each other.

[0066] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0067] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or terminal device comprising the element.

[0068] The above has introduced in detail the preparation method of the efficient Pd-based bimetallic catalyst provided by the present application and its application in air purification. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A highly efficient Pd-based bimetallic catalyst, characterized in that: The Pd-based bimetallic catalyst is composed of TiO2 loaded with Ba 2+ and Pd 2+ Composition, the Pd-based bimetallic catalyst has Ba 2+ The loading amount is (15~30) wt.%, Pd 2+ The loading amount is (0.05~2)wt.%.

2. The high-efficiency Pd-based bimetallic catalyst according to claim 1, characterized in that: The Pd-based bimetallic catalyst contains Ba 2+ The loading amount is (15~30) wt.%, Pd 2+ The loading amount is (0.5~2) wt.%.

3. A method for preparing the highly efficient Pd-based bimetallic catalyst according to claim 1 or 2, characterized in that: The preparation method comprises: S1. Dispersing the TiO2 carrier in deionized water and stirring to obtain a suspension; S2, dissolving the barium salt and the palladium salt in the deionized water, and stirring to obtain a mixed solution; S3, mixing the mixed solution with the suspension, stirring for 0.1 h to 2 h, so that Ba 2+ and Pd 2+ The solid product is loaded on the TiO2, dried overnight, calcined at 300°C to 600°C for 1 h to 4 h, and ground to obtain a Pd-based bimetallic catalyst; S4, repeat steps S1-S3 until Ba is obtained 2+ The loading amount is (15~30) wt.%, Pd 2+ The Pd-based bimetallic catalyst with a loading amount of (0.05-2) wt.%; Wherein, when repeating the step S1, the Pd-based bimetallic catalyst obtained in the step S3 is dissolved in the deionized water to obtain the suspension.

4. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: The barium salt is barium nitrate or barium carbonate.

5. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: The palladium salt is palladium nitrate or palladium chloride.

6. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: In step S2, the mass ratio of the barium salt to the palladium salt is (5-5.5): (0.1-0.5).

7. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: In step S3, the particle size of the Pd-based bimetallic catalyst is 0.1 mm to 2 mm.

8. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: In step S3, the Ba 2+ The loading amount is (5~5.5) wt.%, and the Pd 2+ The loading amount is (0.1~0.5) wt.%.

9. The method for preparing a highly efficient Pd-based bimetallic catalyst according to claim 3, characterized in that: In the step S4, the particle size of the Pd-based bimetallic catalyst is 40 mesh to 60 mesh.

10. Application of an efficient Pd-based bimetallic catalyst in air purification, characterized in that: The Pd-based bimetallic catalyst is obtained by the preparation method described in any one of claims 1 to 2 or any one of claims 3 to 9, and the Pd-based bimetallic catalyst is suitable for decomposing formaldehyde in the air at room temperature.

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