A noble metal-doped copper-based catalyst and a method for preparing the same

Abstract

The present application relates to the technical field of environmental catalytic materials, and particularly relates to a noble metal doped copper-based catalyst and a preparation method thereof.The composition of the catalyst comprises, in percentage by mass, CuO: 11-14%, Pd: 0.3-0.4%, Pt: 0.05-0.1%, MnO2: 11.2-13.2%, Fe2O3: 2-4%, CeO2: 4.7-7%, ZrO2: 3.3-5%, La2O3: 1.5-3%, BaO: 0.8-1.5%, SiO2: 2-4%, and gamma-Al2O3: the balance.The catalyst of the present application successfully constructs high-dispersed Pd-Pt-Cu ternary alloy active centers and super-oleophobic surfaces through precise cooperation of multiple components, and has excellent low-temperature catalytic activity, long-term stability and excellent resistance to oil poisoning, and is particularly suitable for efficient purification of complex oil-containing waste gas such as kitchen fume.

Description

Technical Field

[0001] This invention relates to the field of environmental catalytic materials technology, specifically to a copper-based catalyst doped with noble metals and its preparation method. Background Technology

[0002] With the rapid development of urbanization and the catering industry, restaurant fumes have become a significant source of urban air pollution. Restaurant fumes are a major source of indoor environmental and air pollution, and their composition is extremely complex, mainly consisting of gaseous organic compounds (such as volatile organic compounds like aldehydes, ketones, and olefins) produced by the high-temperature decomposition of oils during cooking, as well as liquid oil droplets and aerosol particles (such as PM2.5). These pollutants not only pose a threat to human health but also damage the ecological environment. Therefore, catalytic degradation technology for kitchen fumes is crucial.

[0003] Among numerous purification technologies, catalytic oxidation is considered a highly efficient and thorough treatment solution because it can completely oxidize pollutants into harmless CO2 and H2O at relatively low temperatures. The core of this technology lies in the development of high-performance catalysts. Currently, catalysts used for oil fume purification are mainly divided into two categories: noble metal catalysts (such as Pt and Pd-based catalysts) and transition metal oxide catalysts (such as Cu, Mn, Co, and Fe oxide-based catalysts).

[0004] Chinese patent application CN116920829A discloses a Pt-Pd alloy catalyst, which uses γ-Al2O3 as a support to load the noble metal elements Pt and Pd. Although it has excellent low-temperature catalytic activity, when this catalyst is applied to the purification of kitchen fumes, the noble metal particles are prone to sintering and growing in the high-temperature and high-humidity fume environment, resulting in a decrease in activity. Furthermore, it is easily poisoned and deactivated by oil mist and carbon deposit precursors in the fumes, resulting in a short service life.

[0005] Chinese patent application CN105344360A discloses a doped nano-MnO2-CuO / Al2O3 catalyst. Although the catalytic activity of the doped catalyst is higher than that of the supported catalyst, the catalyst has a high ignition temperature and insufficient purification efficiency for low-concentration VOCs. It is particularly unstable in scenarios with large concentration fluctuations, such as kitchen fumes. Furthermore, the simple transition metal oxide catalyst has many acidic sites on its surface. When treating fumes rich in large-molecule oils, it is prone to incomplete oxidation reactions, leading to the formation of a large amount of carbon deposits, which quickly block the catalyst channels, cover the active sites, and cause a sharp decline in catalytic efficiency.

[0006] Therefore, there is an urgent need in this field for a new type of catalyst that can not only achieve high activity at low temperatures, but also fundamentally solve the problems of resistance to oil poisoning and long-term stability, thereby meeting the comprehensive and stringent requirements for catalyst performance, lifespan and cost in practical applications of kitchen fume purification. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a copper-based catalyst doped with noble metals, comprising, by mass percentage: CuO: 11-14%, Pd: 0.3-0.4%, Pt: 0.05-0.1%, MnO2: 11.2-13.2%, Fe2O3: 2-4%, CeO2: 4.7-7%, ZrO2: 3.3-5%, La2O3: 1.5-3%, BaO: 0.8-1.5%, SiO2: 2-4%, γ-Al2O3: balance; and satisfying the following relationship:

[0008] w(Pd) / w(Pt)=6:1-4:1;

[0009] w(MnO2) / w(CuO)=0.8:1-1.2:1;

[0010] n(CeO2) / n(ZrO2)=1:1;

[0011] Where: w(Pd) represents the mass percentage of Pd, (Pt) represents the mass percentage of Pt, w(MnO2) represents the mass percentage of MnO2, w(CuO) represents the mass percentage of CuO, n(CeO2) represents the molar amount of CeO2, and n(ZrO2) represents the molar amount of ZrO2.

[0012] Preferably, CeO2 and ZrO2 in the catalyst exist in the form of a CeO2-ZrO2 solid solution.

[0013] Preferably, the Pd and Pt elements in the catalyst, together with the partially reduced Cu elements, form Pd-Pt-Cu ternary alloy nanoparticles, and the particle size of the Pd-Pt-Cu ternary alloy nanoparticles is 2-5 nm.

[0014] Preferably, the macroscopic surface of the catalyst is superoleophobic, with a contact angle to edible vegetable oil greater than 150°.

[0015] Preferably, the La2O3 and BaO are preferentially modified on the strong acid sites on the surface of the γ-Al2O3 support, making the catalyst surface alkaline.

[0016] Preferably, the catalyst is in the shape of either a honeycomb ceramic body or granules.

[0017] This invention also discloses a method for preparing a noble metal-doped copper-based catalyst as described above, comprising the following steps:

[0018] Step 1: Prepare CeO2 using a co-precipitation method at a molar ratio of n(CeO2) / n(ZrO2) = 1:1. 0.5 Zr 0.5 O2 solid solution powder;

[0019] Step 2: Add copper source, manganese source, iron source, and Ce. 0.5 Zr 0.5 O2 solid solution powder, La2O3, barium source, silicon source and γ-Al2O3 are mixed, ball-milled, dried, shaped and calcined to obtain a composite oxide carrier;

[0020] Step 3: Using the equal-volume impregnation method, a noble metal solution containing Pd and Pt is loaded onto a composite oxide support. After drying, it is treated in a reducing atmosphere at 400-500℃ to obtain the noble metal-doped copper-based catalyst.

[0021] Preferably, step one specifically includes:

[0022] Weigh out cerium nitrate hexahydrate and zirconium oxychloride octahydrate according to the molar ratio of n(Ce):n(Zr)=1:1, dissolve them together in deionized water, and prepare a mixed salt solution.

[0023] The mixed salts were heated to 50-70℃ with stirring, and ammonia water was added dropwise. During the addition, the pH value of the solution was monitored in real time using a pH meter to maintain the final pH value between 9.0 and 10.5. After the addition was complete, the temperature was maintained at 50-70℃, and the reaction was continuously stirred for 2-4 hours. After the reaction was completed, the mixture was cooled, and the resulting precipitate was filtered, washed, dried, and calcined. After calcination, the precipitate was allowed to cool naturally, then ground and sieved to obtain Ce. 0.5 Zr 0.5 O2 solid solution powder.

[0024] Preferably, in step two, the ball milling is a high-energy ball milling, and the ball milling time is 4-8 hours; the calcination adopts a stepped heating program: first, it is kept at 250-350℃ for 1-2 hours, then the temperature is increased to 550-650℃ and kept for 2-4 hours, and finally it is kept at 680-720℃ for 0.5-1.5 hours.

[0025] Preferably, in step three, the precious metal solution contains a surfactant, cetyltrimethylammonium bromide, at a concentration of 5%-15% of the precious metal mass.

[0026] Preferably, in step three, the reducing atmosphere is a mixture of hydrogen and nitrogen with a volume fraction of 5%-10%, and the reduction treatment is a programmed temperature reduction with a heating rate of 1-3℃ / minute.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] In this invention, highly dispersed Pd-Pt-Cu ternary alloy nanoparticles were successfully constructed as catalytic active centers by precisely controlling w(Pd) / w(Pt) = 6:1-4:1. The ternary alloy structure can optimize the electronic structure, generate a strong synergistic effect, and significantly enhance its activation ability for C=O and C=C bonds. It exhibits excellent low-temperature activity for typical pollutants (nonanal, propylene), and can achieve low-temperature and high-efficiency purification with great energy-saving potential.

[0029] In this invention, La2O3 and BaO are preferentially modified on the strong acid sites on the surface of the γ-Al2O3 support, making the catalyst surface alkaline. Combined with the special microstructure formed by the multi-components, the contact angle of the catalyst macroscopic surface with edible vegetable oil is greater than 150°, giving the catalyst superoleophobic surface properties. When treating oily waste gas, the catalyst can effectively repel the adhesion and wetting of oil mist particles, fundamentally avoiding physical deactivation and pore blockage caused by oil covering the active sites. It has excellent anti-deactivation ability, maintains high stability during long-term operation, and has a long service life.

[0030] In this invention, the pre-prepared Ce 0.5 Zr 0.5 The O2 solid solution provides strong oxygen storage capacity and excellent thermal stability, ensuring that the catalyst can work continuously and efficiently under fluctuating conditions and resist high-temperature sintering; the precise control of w(MnO2) / w(CuO)=0.8:1-1.2:1 optimizes the redox synergy between copper and manganese oxides, enhances the lattice oxygen migration and replenishment ability, and the support structure has excellent structural stability and resistance to hydrothermal sintering and carbon deposition.

[0031] In this invention, the components are not simply superimposed, but rather, through precise ratio control (w(Pd) / w(Pt), w(MnO2) / w(CuO), n(CeO2) / n(ZrO2)) and preparation process, multifunctional integration and synergy among active centers, co-catalysts, and supports are achieved at the atomic / nanoscale. The catalyst of this invention successfully solves the technical bottlenecks of traditional catalysts in treating complex oily waste gases, such as insufficient low-temperature activity, easy poisoning and deactivation by oil, and poor high-temperature stability. It is a high-performance catalytic material with broad application prospects in fields such as kitchen fume purification. Attached Figure Description

[0032] Figure 1 Ce obtained in Example 1 0.5 Zr 0.5 XRD pattern of O2 solid solution sample;

[0033] Figure 2 The image shows a HAADF-STEM image of the catalyst sample prepared in Example 1.

[0034] Figure 3 The image shows the contact angle test results of the catalyst samples prepared in Examples 1-3 and Comparative Examples 1-4 with edible vegetable oil.

[0035] Figure 4 The graph shows the catalytic activity test results of the catalyst samples prepared in Examples 1-3 and Comparative Examples 1-4 for nonanal;

[0036] Figure 5 The graph shows the catalytic activity test results of the catalyst samples prepared in Examples 1-3 and Comparative Examples 1-4 for propylene.

[0037] Figure 6 The graph shows the conversion retention rate test results of the catalyst samples prepared in Examples 1-3 and Comparative Examples 1-4. Detailed Implementation

[0038] Example 1

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 12.5%, Pd: 0.35%, Pt: 0.07%, MnO2: 12.2%, Fe2O3: 3%, CeO2: 5.85%, ZrO2: 4.15%, La2O3: 2.25%, BaO: 1.15%, SiO2: 3.0%, γ-Al2O3: balance (55.48%).

[0042] Calculated:

[0043] w(Pd) / w(Pt)=0.35% / 0.07%=5:1, which meets the requirements;

[0044] w(MnO2) / w(CuO) = 12.2% / 12.5% ​​≈ 1:1, which meets the requirements;

[0045] n(CeO2)=5.85g / 172.11g / mol≈0.0340mol,

[0046] n(ZrO2)=4.15g / 123.22g / mol≈0.0337mol,

[0047] n(CeO2) / n(ZrO2)≈1:1, which meets the requirements;

[0048] The method for preparing the noble metal-doped copper-based catalyst includes the following steps:

[0049] Step 1: Weigh cerium nitrate hexahydrate and zirconium oxychloride octahydrate according to a molar ratio of n(Ce):n(Zr) = 1:1, and dissolve them together in deionized water to prepare a 0.3 mol / L mixed salt solution. Heat the mixed salt solution to 60°C with stirring at 400 r / min, and add 2 mol / L ammonia solution dropwise at a constant rate of 3 mL / min until the pH reaches 10. After the addition is complete, maintain the temperature at 60°C and continue stirring for an aging reaction for 3 hours. After the reaction is complete, cool the solution, filter the precipitate, and repeatedly wash the precipitate with deionized water to remove impurity ions. Dry the precipitate at 100°C for 12 hours to obtain the precursor powder.

[0050] The precursor powder was placed in a programmed temperature-increasing furnace and calcined in air atmosphere. The calcination process was as follows: the temperature was increased from room temperature to 400℃ at a rate of 3℃ / min and held at 400℃ for 2.5 hours; then, the temperature was increased to 600℃ at a rate of 3℃ / min and held at 600℃ for 4 hours. After calcination, the powder was allowed to cool naturally, gently ground in an agate mortar, and passed through a 200-mesh sieve to obtain Ce. 0.5 Zr 0.5 O2 solid solution powder;

[0051] Step 2: Based on the mass relationship between CuO, MnO2, and Fe2O3 in the composition of the noble metal-doped copper-based catalyst, weigh out copper nitrate, manganese nitrate, and iron nitrate, and dissolve them in deionized water to prepare a 1 mol / L Cu-Mn-Fe mixed nitrate solution. Add the Cu-Mn-Fe mixed nitrate solution and Ce... 0.5 Zr 0.5 O2 solid solution powder, La2O3, BaCO3, silica sol, and γ-Al2O3 powder were mixed and ball-milled for 6 hours. After spray drying, the slurry was placed in a programmed temperature furnace and calcined according to a stepwise procedure: first, holding at 300℃ for 1.5 hours, then at 600℃ for 3 hours, and finally at 700℃ for 1 hour, to obtain a particulate composite oxide carrier.

[0052] Step 3: First, determine the saturated water absorption rate of the composite oxide carrier prepared in Step 2. The saturated water absorption rate is 0.48 mL / g.

[0053] According to the material usage relationship of 48 mL of Pd and Pt noble metal solution for every 100 g of composite oxide support, the composite oxide support obtained in step two was placed in an impregnation container. Under stirring, 48 mL of Pd and Pt noble metal solution was slowly added to the support to ensure that the noble metal solution and the composite oxide support were fully contacted and uniformly adsorbed (i.e., equal volume impregnation method). After impregnation, the support was dried and heated to 450 °C at a rate of 2 °C / min in a 5% H2 / N2 atmosphere. The support was kept at 450 °C for 2 h for reduction to obtain particulate noble metal doped copper-based catalyst.

[0054] The noble metal solution containing Pd and Pt is prepared from chloropalladium acid, chloroplatinic acid, and CTAB (hexadecyltrimethylammonium bromide). 2+ The concentration of Pt is 0.0685 mol / L. 4+ The concentration was 0.00748 mol / L, and the mass of CTAB accounted for 10% of the combined mass of chloropalladium acid and chloroplatinic acid.

[0055] Example 2

[0056] This embodiment provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 14%, Pd: 0.4%, Pt: 0.1%, MnO2: 11.2%, Fe2O3: 4%, CeO2: 7%, ZrO2: 5%, La2O3: 3%, BaO: 1.5%, SiO2: 4%, γ-Al2O3: balance (47.8%).

[0057] Calculated:

[0058] w(Pd) / w(Pt)=0.4% / 0.1%=4:1, which meets the requirements;

[0059] w(MnO2) / w(CuO)=11.2% / 14%=0.8, which meets the requirements;

[0060] n(CeO2)=7g / 172.11g / mol≈0.0407mol,

[0061] n(ZrO2)=5g / 123.22g / mol≈0.0406mol,

[0062] n(CeO2) / n(ZrO2)≈1:1, which meets the requirements;

[0063] The method for preparing the noble metal-doped copper-based catalyst includes the following steps:

[0064] Step 1: Weigh cerium nitrate hexahydrate and zirconium oxychloride octahydrate according to a molar ratio of n(Ce):n(Zr) = 1:1, and dissolve them together in deionized water to prepare a 0.3 mol / L mixed salt solution. Heat the mixed salt solution to 60°C with stirring at 400 r / min, and add 2 mol / L ammonia solution dropwise at a constant rate of 3 mL / min until the pH reaches 10.5. After the addition is complete, maintain the temperature at 60°C and continue stirring for an aging reaction for 3 hours. After the reaction is complete, cool the solution, filter the precipitate, and repeatedly wash the precipitate with deionized water to remove impurity ions. Dry the precipitate at 100°C for 12 hours to obtain the precursor powder.

[0065] The precursor powder was placed in a programmed temperature-increasing furnace and calcined in air. The calcination process was as follows: the temperature was increased from room temperature to 450°C at a rate of 4°C / min and held at 450°C for 2 hours; then, the temperature was increased to 650°C at a rate of 4°C / min and held at 650°C for 3 hours. After calcination, the powder was allowed to cool naturally, gently ground in an agate mortar, and passed through a 200-mesh sieve to obtain Ce. 0.5 Zr 0.5 O2 solid solution powder;

[0066] Step 2: Based on the mass relationship between CuO, MnO2, and Fe2O3 in the composition of the noble metal-doped copper-based catalyst, weigh out copper nitrate, manganese nitrate, and iron nitrate, and dissolve them in deionized water to prepare a 1 mol / L Cu-Mn-Fe mixed nitrate solution. Add the Cu-Mn-Fe mixed nitrate solution and Ce... 0.5 Zr 0.5 O2 solid solution powder, La2O3, BaCO3, silica sol, and γ-Al2O3 powder were mixed and ball-milled for 6 hours. After spray drying, the slurry was placed in a programmed temperature furnace and calcined according to a step-by-step procedure of holding at 250°C for 2 hours, then at 550°C for 4 hours, and finally at 680°C for 1.5 hours to obtain a composite oxide carrier.

[0067] Step 3: First, determine the saturated water absorption rate of the composite oxide carrier prepared in Step 2. The saturated water absorption rate is 0.45 mL / g.

[0068] According to the material usage relationship of 45 mL of Pd and Pt noble metal solution for every 100 g of composite oxide support, the composite oxide support obtained in step two was placed in an impregnation container. Under stirring, 45 mL of Pd and Pt noble metal solution was slowly added to the support to ensure that the noble metal solution and the composite oxide support were fully contacted and uniformly adsorbed (i.e., equal volume impregnation method). After impregnation, the support was dried and heated to 400 °C at a rate of 1 °C / min in a 5% H2 / N2 atmosphere. The support was then kept at 400 °C for 2.5 h for reduction to obtain particulate noble metal doped copper-based catalyst.

[0069] The noble metal solution containing Pd and Pt is prepared from chloropalladium acid, chloroplatinic acid, and CTAB. 2+ The concentration of Pt is 0.0835 mol / L. 4+ The concentration was 0.0114 mol / L, and the mass of CTAB accounted for 5% of the combined mass of chloropalladium acid and chloroplatinic acid.

[0070] Example 3

[0071] This embodiment provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 11%, Pd: 0.3%, Pt: 0.05%, MnO2: 13.2%, Fe2O3: 2%, CeO2: 4.7%, ZrO2: 3.3%, La2O3: 1.5%, BaO: 0.8%, SiO2: 2%, γ-Al2O3: balance (61.4%).

[0072] Calculated:

[0073] w(Pd) / w(Pt)=0.3% / 0.05%=6:1, which meets the requirements;

[0074] w(MnO2) / w(CuO)=13.2% / 11%=1.2:1, which meets the requirements;

[0075] n(CeO2)=4.7g / 172.11g / mol≈0.0273mol,

[0076] n(ZrO2)=3.3g / 123.22g / mol≈0.0268mol,

[0077] n(CeO2) / n(ZrO2)≈1:1, which meets the requirements;

[0078] The method for preparing the noble metal-doped copper-based catalyst includes the following steps:

[0079] Step 1: Weigh cerium nitrate hexahydrate and zirconium oxychloride octahydrate according to a molar ratio of n(Ce):n(Zr) = 1:1, and dissolve them together in deionized water to prepare a 0.3 mol / L mixed salt solution. Heat the mixed salt solution to 60°C with stirring at 400 r / min, and add 2 mol / L ammonia solution dropwise at a constant rate of 3 mL / min until the pH reaches 9.5. After the addition is complete, maintain the temperature at 60°C and continue stirring for an aging reaction for 3 hours. After the reaction is complete, cool the solution, filter the precipitate, and repeatedly wash the precipitate with deionized water to remove impurity ions. Dry the precipitate at 100°C for 12 hours to obtain the precursor powder.

[0080] The precursor powder was placed in a programmed temperature-increasing furnace and calcined in air. The calcination process was as follows: the temperature was increased from room temperature to 350°C at a rate of 2°C / min and held at 350°C for 3 hours; then, the temperature was increased to 550°C at a rate of 2°C / min and held at 550°C for 5 hours. After calcination, the powder was allowed to cool naturally, gently ground in an agate mortar, and passed through a 200-mesh sieve to obtain Ce. 0.5 Zr 0.5 O2 solid solution powder;

[0081] Step 2: Based on the mass relationship between CuO, MnO2, and Fe2O3 in the composition of the noble metal-doped copper-based catalyst, weigh out copper nitrate, manganese nitrate, and iron nitrate, and dissolve them in deionized water to prepare a 1 mol / L Cu-Mn-Fe mixed nitrate solution. Add the Cu-Mn-Fe mixed nitrate solution and Ce... 0.5 Zr 0.5 O2 solid solution powder, La2O3, BaCO3, silica sol, and γ-Al2O3 powder were mixed and ball-milled for 6 hours. After spray drying, the slurry was placed in a programmed temperature furnace and calcined according to a step-by-step procedure of holding at 350℃ for 1 hour, then at 650℃ for 2 hours, and finally at 720℃ for 1 hour to obtain a composite oxide carrier.

[0082] Step 3: First, determine the saturated water absorption rate of the composite oxide carrier prepared in Step 2. The saturated water absorption rate is 0.44 mL / g.

[0083] According to the material ratio of 44 mL of Pd and Pt noble metal solution for every 100 g of composite oxide support, the composite oxide support obtained in step two was placed in an impregnation container. Under stirring, 44 mL of Pd and Pt noble metal solution was slowly added to the support to ensure that the noble metal solution and the composite oxide support were fully contacted and uniformly adsorbed (i.e., equal volume impregnation method). After impregnation, the support was dried and heated to 500 °C at a rate of 3 °C / min in a 5% H2 / N2 atmosphere. The support was then kept at 500 °C for 3 h for reduction to obtain particulate noble metal doped copper-based catalyst.

[0084] The noble metal solution containing Pd and Pt is prepared from chloropalladium acid, chloroplatinic acid, and CTAB. 2+ The concentration of Pt is 0.0641 mol / L. 4+ The concentration was 0.00583 mol / L, and the mass of CTAB accounted for 15% of the combined mass of chloropalladium acid and chloroplatinic acid.

[0085] Comparative Example 1

[0086] This comparative example provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 12.5%, Pd: 0.42%, Pt: 0%, MnO2: 12.2%, Fe2O3: 3%, CeO2: 5.85%, ZrO2: 4.15%, La2O3: 2.25%, BaO: 1.15%, SiO2: 3.0%, γ-Al2O3: balance (55.48%).

[0087] In this component:

[0088] Adding Pt would disrupt the Pd / Pt ratio;

[0089] The preparation method of the noble metal-doped copper-based catalyst is the same as in Example 1, except that in step three, the noble metal solution does not contain Pt. 4+ Contains only Pd 2+ The saturated water absorption rate of the composite oxide carrier obtained in step two was determined to be 0.47 mL / g. The noble metal solution in step three was prepared from chloropalladium acid and CTAB. (Pd) 2+ The concentration was 0.0840 mol / L, and the mass of CTAB accounted for 10% of the combined mass of chloropalladium acid and chloroplatinic acid.

[0090] Comparative Example 2

[0091] This comparative example provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 12.5%, Pd: 0.35%, Pt: 0.07%, MnO2: 6.25%, Fe2O3: 3%, CeO2: 5.85%, ZrO2: 4.15%, La2O3: 2.25%, BaO: 1.15%, SiO2: 3.0%, γ-Al2O3: balance (61.43%).

[0092] In this component:

[0093] w(MnO2) / w(CuO)=6.25% / 12.5%=0.5:1, which is lower than the lower limit requirement of 0.8:1 in this invention;

[0094] The preparation method of the noble metal-doped copper-based catalyst is the same as in Example 1. The difference is that in step two, the amount of manganese nitrate is reduced according to the component ratio (from 12.2% based on MnO2 to 6.25%).

[0095] Comparative Example 3

[0096] This comparative example provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 8.13%, Pd: 0.35%, Pt: 0.07%, MnO2: 12.2%, Fe2O3: 3%, CeO2: 5.85%, ZrO2: 4.15%, La2O3: 2.25%, BaO: 1.15%, SiO2: 3.0%, γ-Al2O3: balance (59.85%).

[0097] In this component:

[0098] w(MnO2) / w(CuO)=12.2% / 8.13%=1.5:1, which is higher than the lower limit requirement of 1.2:1 in this invention;

[0099] The preparation method of the noble metal-doped copper-based catalyst is the same as in Example 1. The difference is that in step two, the amount of manganese nitrate is increased according to the component ratio (from 12.2% based on MnO2 to 8.13%).

[0100] Comparative Example 4

[0101] This comparative example provides a copper-based catalyst doped with noble metals, the composition of which, by mass percentage, includes: CuO: 12.5%, Pd: 0.42%, γ-Al2O3: balance (87.08%).

[0102] The method for preparing the noble metal-doped copper-based catalyst includes the following steps:

[0103] Step 1: Weigh copper nitrate according to the proportion of CuO in the composition of the copper-based catalyst doped with precious metals, dissolve it in deionized water to prepare a 1 mol / L copper nitrate solution, mix the copper nitrate solution with γ-Al2O3 powder, and ball mill it for 6 hours. After spray drying the slurry, place it in a programmed temperature furnace and calcine it according to a step-by-step procedure of holding it at 300℃ for 1.5 hours, then at 600℃ for 3 hours, and finally at 700℃ for 1 hour to obtain a particulate composite oxide support.

[0104] Step 2: First, determine the saturated water absorption rate of the composite oxide carrier prepared in Step 2. The saturated water absorption rate is 0.46 mL / g.

[0105] According to the material ratio of 46 mL of Pd-containing noble metal solution to 100 g of composite oxide support, the composite oxide support obtained in step two was placed in an impregnation container. Under stirring, 46 mL of Pd-containing noble metal solution was slowly added to the support to ensure that the noble metal solution and the composite oxide support were fully contacted and uniformly adsorbed (i.e., equal volume impregnation method). After impregnation, the support was dried and heated to 450 °C at a rate of 2 °C / min in a 5% H2 / N2 atmosphere. The support was kept at 450 °C for 2 h for reduction to obtain particulate noble metal-doped copper-based catalyst.

[0106] The Pd-containing noble metal solution is prepared from chloropalladium acid and CTAB, and Pd 2+ The concentration of Pt is 0.0685 mol / L. 4+ The concentration was 0.0858 mol / L, and the mass of CTAB accounted for 10% of the combined mass of chloropalladium acid and chloroplatinic acid.

[0107] Structural characterization and performance testing:

[0108] (1) Ce prepared in Example 1 0.5 Zr 0.5 The O2 solid solution powder was subjected to XRD (X-ray diffraction) testing, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that, compared with the XRD peaks of pure CeO2 (peak marked #) and pure ZrO2 (peak marked ), Ce 0.5 Zr 0.5 The formation of new diffraction peaks in the XRD pattern of O2, along with peak shifting and rearrangement—typical characteristics of solid solution formation—indicates that Ce and Zr dissolve into each other within the crystal structure, forming Ce2. 0.5 Zr 0.5 O2 solid solution;

[0109] (2) The catalyst sample prepared in Example 1 was subjected to high-angle annular dark-field imaging-scanning transmission electron microscopy (HAADF-STEM), and the results are as follows: Figure 2 As shown. By Figure 2 From (a), (b), and (c), it can be seen that Cu, Pt, and Pd are all uniformly distributed as fine particles. Figure 2 As shown in (d), the signals of Cu, Pt, and Pd completely overlap at the nanoparticle positions, indicating that Cu, Pd, and Pt are atomically uniformly distributed in the same particle, successfully forming a Pd-Pt-Cu ternary alloy. In addition, particle size statistics show that the size of the Pd-Pt-Cu ternary alloy nanoparticles is mainly distributed in the range of 2-5 nm.

[0110] (3) The contact angles of the precious metal-doped copper-based catalysts for edible vegetable oils prepared in Examples 1-3 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1:

[0111] Table 1

[0112]

[0113] As shown in Table 1, the catalysts prepared in the embodiments of the present invention exhibit superoleophobic properties, with contact angles to edible vegetable oils all exceeding 150°. This is attributed to: 1) the preferential modification of La2O3 and BaO on the strong acid sites of the γ-Al2O3 support surface, making the catalyst surface alkaline and reducing the adsorption of oily substances; and 2) the synergistic effect of multiple components achieving the optimal oleophobic effect. In Comparative Example 1, the lack of Pt disrupted the ideal structure of the Pd-Pt-Cu ternary alloy, potentially affecting the electronic state of the active sites and consequently the final modification effect and physical structure of the support surface, leading to a decrease in oleophobicity. In Comparative Example 2, insufficient MnO2 content affected the redox properties of the catalyst and the construction of the surface structure, resulting in the oleophobic performance failing to reach its optimal level. In Comparative Example 3, excessive MnO2 may have coated some of the surface modifiers (La2O3 / BaO) or altered the pore structure of the support surface, which is not conducive to the formation of a superoleophobic surface. In Comparative Example 4, no superoleophobic surface mechanism was constructed. This catalyst only contained CuO / Pd / γ-Al2O3, completely lacking key components such as the surface alkaline modification of La2O3 / BaO and the CeO2-ZrO2 solid solution. The unmodified γ-Al2O3 surface has a large number of strong acid sites, which readily adsorb oily molecules, resulting in a oleophilic surface.

[0114] (4) Simulated kitchen oil fume catalytic performance test:

[0115] 1. Test conditions:

[0116] 1.1 Reactor: Fixed-bed reactor;

[0117] 1.2 Simulated oil fume composition:

[0118] Nononal: 100ppm (representing aldehyde odor molecules), Propylene: 200ppm (representing incomplete combustion products and olefins), Water vapor: 10vol% (simulating cooking steam), Atomized cooking oil particles: 50mg / m (simulating oil mist), Balance gas: Air;

[0119] Airspeed: 30,000 h -1 .

[0120] Temperature program: from 100℃ to 300℃, with online chromatographic monitoring of pollutant conversion rate;

[0121] Evaluation indicators: T of nonanal and propylene 90 (The temperature at which the conversion rate reaches 90% is lower, and the activity is better) and the conversion rate retention rate after running at 250℃ for 24 hours (the higher the retention rate, the better the stability).

[0122] The measurement results are shown in Table 2:

[0123] Table 2

[0124]

[0125] As shown in Table 2, the catalyst of this invention exhibits good catalytic activity and long-term stability. It achieves efficient purification of typical oil fume pollutants at relatively low temperatures. Even after 24 hours of operation under harsh conditions (250°C, containing water and oil), the conversion rate remains as high as 93%-96%, demonstrating excellent stability. Regarding catalytic activity, compared to Example 1, the TC of Comparative Example 1... 90The significant increase in activity demonstrates that the introduction of Pt is crucial for the formation of a highly active Pd-Pt-Cu ternary alloy. Pt can optimize the electronic structure of the alloy and significantly enhance the activation ability of C=O and C=C bonds. In Comparative Example 2, the w(MnO2) / w(CuO) ratio is low, while in Comparative Example 3, the w(MnO2) / w(CuO) ratio is high, resulting in decreased catalytic activity. This demonstrates that an imbalance in the w(MnO2) / w(CuO) ratio leads to poorer lattice oxygen migration and release capabilities, resulting in reduced activity. In Comparative Example 4, the catalyst only contains CuO / Pd / γ-Al2O3, completely lacking key components such as the surface alkaline modification of La2O3 / BaO and the CeO2-ZrO2 solid solution. The catalytic activity is extremely degraded, demonstrating that components such as the CeO2-ZrO2 solid solution (providing oxygen storage and release capabilities) and La2O3 / BaO (modifying acidity and stabilizing the structure) are not simply "additives," but are indispensable components for forming a highly active support. Regarding stability, compared with Example 1, Comparative Example 1 lacks Pt, making it difficult to form stable ternary alloy nanoparticles. Under reaction conditions, these nanoparticles are prone to sintering and growth (Ostwald ripening), resulting in a reduction of active sites and decreased stability. In Comparative Examples 2 and 3, an inappropriate w(MnO2) / w(CuO) ratio affects the structural stability and oxidizability of the support. If the w(MnO2) / w(CuO) ratio is too low, the reducing power is too strong, and carbon deposition is easy. If the w(MnO2) / w(CuO) ratio is too high, it may cover the active sites, both of which lead to poor stability. In Comparative Example 4, firstly, as shown in Table 1, there is no superoleophobicity, and oil mist directly covers the active sites. Secondly, the active alloy was not successfully constructed, and the Pd-Cu particles are prone to sintering. Thirdly, there is no oxygen storage capacity, and the nanoparticles are prone to deactivation under atmospheric fluctuations. Finally, the thermal stability is poor, and the γ-Al2O3 support is prone to sintering.

[0126] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A noble metal-doped copper-based catalyst, characterized in that, The composition ingredients, by mass percentage, include: CuO: 11-14%, Pd: 0.3-0.4%, Pt: 0.05-0.1%, MnO2: 11.2-13.2%, Fe2O3: 2-4%, CeO2: 4.7-7%, ZrO2: 3.3-5%, La2O3: 1.5-3%, BaO: 0.8-1.5%, SiO2: 2-4%, and γ-Al2O3: the balance; and the following relationships are satisfied: w(Pd) / w(Pt)=6:1-4:1; w(MnO2) / w(CuO)=0.8:1-1.2:1; n(CeO2) / n(ZrO2)=1:1; Wherein: w(Pd) represents the mass percentage of Pd, w(Pt) represents the mass percentage of Pt, w(MnO2) represents the mass percentage of MnO2, w(CuO) represents the mass percentage of CuO, n(CeO2) represents the molar amount of CeO2, and n(ZrO2) represents the molar amount of ZrO2; The CeO2 and ZrO2 in the catalyst exist in the form of a CeO2-ZrO2 solid solution; The Pd element, Pt element and partially reduced Cu element in the catalyst collectively form Pd-Pt-Cu ternary alloy nanoparticles, and the particle size of the Pd-Pt-Cu ternary alloy nanoparticles is 2-5 nm; The macroscopic surface of the catalyst has super-oleophobicity, and the contact angle with edible vegetable oil is greater than 150°; The preparation method of the catalyst comprises the following steps: Step one, using coprecipitation method to prepare Ce 0.5 Zr 0.5 O2 solid solution powder with n(CeO2) / n(ZrO2)=1:1 molar ratio; Step two, copper source, manganese source, iron source, Ce 0.5 Zr 0.5 O2 solid solution powder, La2O3, barium source, silicon source and γ-Al2O3 are mixed, ball milled, dried, shaped, calcined to obtain a composite oxide carrier; Step three, an equal volume impregnation method is used to load a Pd and Pt-containing noble metal solution onto the composite oxide carrier, and after drying, treatment is performed in a reducing atmosphere at 400-500°C to obtain the noble metal-doped copper-based catalyst.

2. The noble metal-doped copper-based catalyst of claim 1, wherein, The shape of the catalyst is any one of a honeycomb ceramic body and a granular shape.

3. A method for the preparation of a noble metal doped copper-based catalyst according to any one of claims 1-2, characterized in that, The preparation method comprises the following steps: Step one, using coprecipitation method to prepare Ce 0.5 Zr 0.5 O2 solid solution powder with n(CeO2) / n(ZrO2)=1:1 molar ratio; Step two, copper source, manganese source, iron source, Ce 0.5 Zr 0.5 O2 solid solution powder, La2O3, barium source, silicon source and γ-Al2O3 are mixed, ball milled, dried, shaped, calcined to obtain a composite oxide carrier; Step three, an equal volume impregnation method is used to load a Pd and Pt-containing noble metal solution onto the composite oxide carrier, and after drying, treatment is performed in a reducing atmosphere at 400-500°C to obtain the noble metal-doped copper-based catalyst.

4. A method of preparing a noble metal-doped copper-based catalyst according to claim 3, characterized in that, The step one specifically comprises: According to a molar ratio of n(Ce):n(Zr)=1:1, cerium nitrate hexahydrate and zirconium oxychloride octahydrate are weighed and dissolved in deionized water to prepare a mixed salt solution; After the mixed salt is heated to 50-70℃ under stirring, ammonia water is added dropwise; during the dropwise addition, the pH value of the solution is monitored in real time by a pH meter, so that the final pH value is controlled between 9.0-10.5; after the dropwise addition is completed, the temperature is kept at 50-70℃, and the stirring reaction is continued for 2-4h; after the reaction is completed, cooling is performed, the obtained precipitate is suction-filtered, washed, dried, calcined, after the calcination is completed, natural cooling is performed, grinding is performed, sieving is performed, and Ce 0.5 Zr 0.5 O2 solid solution powder is obtained.

5. The method for preparing a noble metal-doped copper-based catalyst according to claim 3, characterized in that, In the step two, the ball milling is high-energy ball milling, and the ball milling time is 4-8h; the calcination adopts a stepwise heating program: first, heat preservation at 250-350°C for 1-2h, then heat preservation at 550-650°C for 2-4h, and finally heat preservation at 680-720°C for 0.5-1.5h.

6. The method for preparing a noble metal-doped copper-based catalyst according to claim 3, characterized in that, In the step three, 5%-15% of a surfactant cetyltrimethylammonium bromide by mass of the noble metal is added to the noble metal solution.

7. The method for preparing a noble metal-doped copper-based catalyst according to claim 3, characterized in that, In step three, the reducing atmosphere is a mixture of 5%-10% hydrogen and nitrogen by volume fraction, and the reduction treatment is programmed temperature reduction with a heating rate of 1-3°C / min.

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