Catalyst for efficient catalytic synthesis of hydrogen peroxide as well as preparation method and application of catalyst

Abstract

The invention relates to the field of catalyst materials, in particular to a catalyst for efficient catalytic synthesis of hydrogen peroxide as well as a preparation method and application thereof. A catalyst for efficient catalytic synthesis of hydrogen peroxide comprises a porous carrier and alloy sites loaded on the surface of the functional carrier, and the alloy sites are Pd-Cu bimetallic monatomic alloy sites. Pd-Cu bimetallic monatomic alloy sites are adopted, and through the synergistic effect of two metal atoms, the electron density and coordination environment of an active center can be precisely regulated and controlled, the oxygen reduction reaction path is optimized, and side reactions are inhibited; meanwhile, the monatomic alloy structure can maximize the exposure degree of active sites and improve the catalytic efficiency. According to the scheme, starting from the composition and structural design of an active center, aiming at the core defects that the activity and selectivity of the existing catalyst are difficult to consider and the dispersity is poor, through the synergistic effect of a bimetallic monatomic alloy and the bearing effect of a porous carrier, the catalyst is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst materials, in particular to a high-efficiency catalyst for catalytic synthesis of hydrogen peroxide, a preparation method and application thereof. BACKGROUND

[0002] Hydrogen peroxide, as an environmentally friendly oxidant, has been widely used in chemical synthesis, wastewater treatment, medical disinfection and other fields. The mainstream production method of hydrogen peroxide in industry has defects such as complex process, high energy consumption and environmental pollution, while the direct synthesis method of hydrogen and oxygen is considered to be a promising alternative due to its high atom economy and environmental protection.

[0003] However, the existing direct synthesis method faces many technical bottlenecks: on the one hand, traditional catalysts mostly use single metal active sites or ordinary alloy particles, which have problems of uneven distribution of active centers and difficulty in controlling electronic structure, resulting in limited efficiency of selective reduction of oxygen to hydrogen peroxide, and easy occurrence of side reactions such as water generation or oxygen decomposition; on the other hand, the design of the carrier of the catalyst lacks pertinence, which is difficult to effectively anchor the active center, resulting in easy agglomeration and deactivation of the active site, and insufficient stability; at the same time, the existing reaction often needs harsh reaction conditions, and the product separation process is complex, the catalyst regeneration is difficult, which restricts the industrial application of the direct synthesis method. SUMMARY

[0004] Based on the technical problems existing in the prior art, the present application provides a high-efficiency catalyst for catalytic synthesis of hydrogen peroxide, a preparation method and application thereof.

[0005] A high-efficiency catalyst for catalytic synthesis of hydrogen peroxide, a preparation method and application thereof adopt the following technical solutions: In a first aspect, the present application discloses a high-efficiency catalyst for catalytic synthesis of hydrogen peroxide, which adopts the following technical solutions: A high-efficiency catalyst for catalytic synthesis of hydrogen peroxide, comprising a porous carrier and an alloy site loaded on the surface of the functionalized carrier, wherein the alloy site is a Pd-Cu bimetallic single-atom alloy site.

[0006] Through the above technical solutions, the core technical solution of this application is a porous support combined with Pd-Cu bimetallic single-atom alloy sites supported thereon, clarifying the core composition and structural characteristics of the catalyst. This application employs Pd-Cu bimetallic single-atom alloy sites, and through the synergistic effect of the two metal atoms, the electron density and coordination environment of the active center can be precisely controlled, optimizing the oxygen reduction reaction pathway and suppressing side reactions. Simultaneously, the single-atom alloy structure maximizes the exposure of the active sites, improving catalytic efficiency, while the porous support provides a stable supporting substrate for the active sites, preventing their aggregation and deactivation. This solution, starting from the composition and structural design of the active center, directly addresses the core defects of existing catalysts, such as the difficulty in simultaneously achieving activity and selectivity and poor dispersibility, through the synergistic effect of the bimetallic single-atom alloy and the supporting role of the porous support.

[0007] Furthermore, the porous support is an NP-co-doped porous carbon support.

[0008] Through the above technical solutions, this application further specifies the porous support as an NP-co-doped porous carbon support, clarifying the specific type of support and doping elements. This application employs an NP co-doping design, where N atoms can form strong interactions with Pd-Cu bimetallic single atoms through coordination, achieving stable anchoring of the active center and inhibiting aggregation; the introduction of P atoms can further regulate the electronic environment of the support surface, producing a synergistic effect with the bimetallic active center and optimizing the kinetics of the catalytic reaction. Compared to existing single-doped or undoped supports, the design of NP-co-doped porous carbon supports is more targeted, solving both the dispersion and stability problems of the active center and improving catalytic selectivity and activity through electronic regulation.

[0009] Furthermore, the MOF is a UiO-66 metal-organic framework material, and the mass ratio of the UiO-66 metal-organic framework material to diammonium hydrogen phosphate is 10:1-10:3.

[0010] Through the above technical solution, this application further specifies the MOF as UiO-66 metal-organic framework material and clarifies its mass ratio with diammonium hydrogen phosphate. This application selects UiO-66 as the MOF precursor because it has the characteristics of structural stability, large specific surface area, and controllable pore structure, which can provide an excellent framework foundation for subsequent carbon support derivation. The specified mass ratio is based on the precise design of the support doping uniformity and pore structure integrity, which can ensure that the NP co-doped porous carbon support formed after calcination has a suitable doping concentration and pore structure, providing a guarantee for the uniform loading and efficient catalysis of Pd-Cu bimetallic single-atom alloy sites.

[0011] Secondly, this application provides a method for preparing a highly efficient catalyst for the catalytic synthesis of hydrogen peroxide, employing the following technical solution: A method for preparing a highly efficient catalyst for the catalytic synthesis of hydrogen peroxide includes the following preparation steps: MOF was mixed with diammonium hydrogen phosphate and calcined at 500-600℃ for 3-5 hours under an inert atmosphere to obtain NP co-doped porous carbon support. NP co-doped porous carbon support was dispersed in an ethanol solution, and a mixed aqueous solution of Pd and Cu salts was added. The pH of the system was adjusted to 5.5-6.5, and the mixture was stirred at room temperature to form a composite. The composite was calcined at 300-400℃ for 1-3 hours under an inert atmosphere, and then reduced at 250-300℃ under a mixed H2 / Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0012] This application discloses a method for preparing a catalyst using the above technical solution. First, the direct calcination of MOF and diammonium hydrogen phosphate achieves the preparation of the support and NP co-doping in one step, simplifying the process and ensuring the uniform distribution of dopant elements. Second, the metal salt solution is mixed with the support for coordination, utilizing the coordination between the NP doping sites on the support surface and the metal ions to achieve uniform loading of Pd-Cu bimetallic ions. Finally, through stepwise calcination and reduction, the formation process of active centers is precisely controlled, avoiding bimetallic atom aggregation and ensuring the stable existence of single-atom alloy sites. This preparation method is simple, highly controllable, and can efficiently prepare the target catalyst, solving the problems of "complex processes and difficulty in precisely controlling active centers" in existing preparation technologies.

[0013] Furthermore, the Cu salt is copper nitrate; the volume fraction of H2 in the H2 / Ar mixed atmosphere is 5%-10%.

[0014] Through the above technical solution, this application specifies copper nitrate as the Cu salt and clarifies the volume fraction of H2 in the H2 / Ar mixed atmosphere, optimizing key raw materials and process parameters in the preparation process. Copper nitrate is chosen as the Cu salt because it has good solubility in solution, can form a homogeneous mixture with Pd salt, and leaves no harmful residues after decomposition, ensuring uniform loading of metal ions and the purity of subsequent active centers. The specified H2 volume fraction is precisely optimized to ensure that Pd and Cu ions are fully reduced to bimetallic single-atom alloy sites while avoiding metal particle agglomeration caused by over-reduction. Simultaneously, the presence of Ar gas protects the active centers from oxidation. This solves the problems of uneven metal ion loading and poor reduction effect in existing preparation processes.

[0015] Thirdly, this application provides a method for using a catalyst for the efficient catalytic synthesis of hydrogen peroxide, employing the following technical solution: A method for applying a highly efficient catalyst in the catalytic synthesis of hydrogen peroxide, characterized by comprising the following steps: Using deionized water as a solvent, a proton modifier was added to adjust the pH of the system to 3.0-4.0; the highly efficient catalytic synthesis of hydrogen peroxide was carried out in a fixed-bed reactor with the catalyst filling the catalyst bed height to inner diameter ratio of 5:1-8:1; H2 and O2 are mixed at a volume ratio of 1:3 to 1:5 and introduced into the reaction system at a flow rate of 100 to 200 mL / min under normal pressure and 25-40℃ conditions; the space velocity of the reaction solution through the fixed-bed reactor is 1-3 h⁻¹. -1 H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2; The reaction effluent is separated by a separation membrane to remove trace catalyst particles, yielding hydrogen peroxide product; after continuous operation of the catalyst, it is treated at 300℃ for 2 hours under an O2 / Ar mixed atmosphere to achieve active regeneration.

[0016] Through the above technical solution, this application discloses a method for applying the catalyst. First, the reaction system uses water as a solvent and adds a proton modifier to optimize the reaction environment, which is green and environmentally friendly and can improve catalytic selectivity. Second, it adopts atmospheric pressure and mild temperature conditions, combined with a fixed-bed reactor and a specific gas mixing ratio, which reduces equipment requirements and safety risks while ensuring efficient reaction. Finally, it achieves efficient separation of products and catalyst through a separation membrane and designs a special catalyst regeneration step, which significantly improves the service life of the catalyst and the economics of the process.

[0017] Furthermore, the proton regulator is formic acid, and the concentration of formic acid is 0.05-0.1 mol / L.

[0018] Through the above technical solution, this application specifies formic acid as the proton modifier, clarifying the selection of key auxiliary reagents in the reaction system. Formic acid, as a proton modifier, possesses suitable proton dissociation capabilities, enabling precise control of the pH environment of the reaction system and providing optimal reaction conditions for the selective reduction of oxygen to hydrogen peroxide. Simultaneously, formic acid exhibits good compatibility with the catalyst of this application, avoiding harmful interactions with Pd-Cu bimetallic single-atom alloy sites and preventing the residue of difficult-to-remove impurities after the reaction, thus ensuring product purity. Compared to other proton modifiers that may be used in existing technologies, the selection of formic acid is more targeted, forming a synergistic effect with the catalyst and reaction system, maximizing catalytic efficiency and selectivity, and solving the problem of poor compatibility between proton modifiers and the catalytic system.

[0019] Furthermore, the molecular weight cutoff of the separation membrane is 1000 Da.

[0020] Furthermore, the volume fraction of O2 in the O2 / Ar mixed atmosphere is 10%.

[0021] In summary, this application has the following beneficial effects: First, this invention significantly improves the catalytic performance of hydrogen peroxide synthesis through the synergistic design of Pd-Cu bimetallic single-atom alloy sites and NP-co-doped porous carbon supports. The bimetallic single-atom alloy sites, leveraging the electronic synergistic effect of the two metals, precisely regulate the electron density and coordination environment of the active centers, effectively optimizing the balance between oxygen adsorption and hydrogen peroxide desorption, and significantly suppressing side reactions such as water or oxygen decomposition. This solves the core problem of traditional single-metal catalysts' difficulty in simultaneously achieving both activity and selectivity. Simultaneously, the NP-co-doped porous carbon support, with its abundant anchoring sites and unique electronic regulation, achieves uniform dispersion and stable loading of the active centers, avoiding the defects of easy aggregation and deactivation of active sites in traditional catalysts, and extending the catalyst's service life. This structural synergistic effect makes the catalytic reaction kinetics more efficient, providing a superior catalytic system for the direct synthesis of hydrogen peroxide, and completely breaking through the bottlenecks of catalytic efficiency and stability in existing technologies.

[0022] Secondly, the hydrogen peroxide synthesis system constructed in this invention possesses outstanding green and safe advantages, perfectly aligning with the development needs of modern green chemical engineering. The reaction uses deionized water as a solvent, combined with an environmentally friendly formic acid proton modifier. The entire process produces no harmful waste liquid or gas emissions, reducing environmental pollution at its source. The reaction conditions are designed with atmospheric pressure and a mild temperature, abandoning the harsh high-pressure conditions of traditional processes. This not only reduces equipment investment and operational difficulty but also completely avoids the safety risks of hydrogen and oxygen mixing under high pressure, enhancing the safety of the production process. Product separation employs highly efficient membrane technology, eliminating the need for complex purification steps. This ensures the high purity of the hydrogen peroxide product while avoiding product loss or pollution that may occur with traditional separation methods. Furthermore, the catalyst can be efficiently regenerated through simple atmosphere treatment, reducing catalyst waste generation and further reducing the environmental burden, thus achieving the greening and sustainability of hydrogen peroxide synthesis. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the embodiments.

[0024] Example 1 A method for preparing a highly efficient catalyst for the catalytic synthesis of hydrogen peroxide includes the following steps: Mix 0.5g of UiO-66 type MOF with 0.05g of diammonium hydrogen phosphate, grind in an agate mortar for 10 minutes until uniform powder is formed; place the mixed powder in a tube furnace, heat to 500℃ at a rate of 5℃ / min under nitrogen atmosphere, and calcine at a constant temperature for 3 hours; after naturally cooling to room temperature, pulverize and pass through a 200-mesh sieve to obtain NP co-doped porous carbon support.

[0025] 0.2 g of N-P co-doped porous carbon support was dispersed in 20 mL of anhydrous ethanol and ultrasonically dispersed for 30 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.01 mol / L and copper nitrate concentration of 0.003 mol / L was prepared. 5 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.005. The pH of the system was adjusted to 5.5 with 0.1 mol / L hydrochloric acid and magnetically stirred at 25 °C for 12 h. The solution was then filtered, washed three times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 60 °C for 8 h to form the complex.

[0026] The dried composite was placed in a tube furnace and heated to 300°C at a rate of 3°C / min under a nitrogen atmosphere, and calcined at a constant temperature for 1 hour. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 5%, and the temperature was maintained at 250°C for reduction for 1 hour. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0027] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 50 mL of deionized water as a solvent, add 10 mL of 0.05 mol / L formic acid (proton regulator), and adjust the pH of the system to 3.0 with 0.1 mol / L hydrochloric acid; fill the catalyst into a fixed-bed reactor with an inner diameter of 5 mm and a catalyst bed height of 25 mm (bed height to inner diameter ratio 5:1), and the catalyst loading volume is 10 mL.

[0028] H2 and O2 were mixed at a volume ratio of 1:3 (H2 volume percentage 25%) and introduced into the reaction system at a flow rate of 100 mL / min under normal pressure (0.1 MPa) and 25 °C; the volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 1 h⁻¹. -1 (Reaction flow rate 10 mL / h), H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 24 h.

[0029] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.1 MPa and the membrane flux was controlled at 5 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 24 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 50 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0030] Example 2 Take 1g of UiO-66 type MOF and mix it with 0.2g of diammonium hydrogen phosphate. Grind it in an agate mortar for 20 minutes until it becomes a uniform powder. Place the mixed powder in a tube furnace and heat it to 550℃ at a heating rate of 7℃ / min under an argon atmosphere. Then, calcine it at a constant temperature for 4 hours. After naturally cooling to room temperature, crush it and pass it through a 250-mesh sieve to obtain an NP co-doped porous carbon support.

[0031] 0.5 g of N-P co-doped porous carbon support was dispersed in 40 mL of anhydrous ethanol and ultrasonically dispersed for 40 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.02 mol / L and copper nitrate concentration of 0.01 mol / L was prepared. 10 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.01. The pH of the system was adjusted to 6.0 with 0.1 mol / L sodium hydroxide solution and magnetically stirred at 28 °C for 16 h. The solution was then filtered, washed four times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 70 °C for 10 h to form the complex.

[0032] The dried composite was placed in a tube furnace and heated to 350°C at a rate of 4°C / min under an argon atmosphere, and calcined at this temperature for 2 hours. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 7%, and the temperature was maintained at 270°C for reduction for 2 hours. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0033] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 150 mL of deionized water as a solvent, add 20 mL of formic acid with a concentration of 0.06 mol / L, and adjust the pH of the system to 3.2 with 0.1 mol / L sodium hydroxide solution; fill the catalyst into a fixed bed reactor with an inner diameter of 8 mm, a catalyst bed height of 56 mm (bed height to inner diameter ratio 7:1), and a catalyst loading volume of 20 mL.

[0034] H2 and O2 were mixed at a volume ratio of 1:4 (H2 accounted for 20% by volume) and introduced into the reaction system at a flow rate of 120 mL / min under normal pressure (0.1 MPa) and 30 °C; the volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 1.5 h⁻¹. -1 (Reaction flow rate 30 mL / h), H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 48 h.

[0035] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.15 MPa, and the membrane flux was controlled at 8 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 48 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 60 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0036] Example 3 Take 2g of UiO-66 type MOF and 0.6g of diammonium hydrogen phosphate, mix them, and grind them in an agate mortar for 30min until they are uniform powder. Place the mixed powder in a tube furnace and heat it to 600℃ at a rate of 10℃ / min under a nitrogen atmosphere. Then, calcine it at a constant temperature for 5h. After naturally cooling to room temperature, crush it and pass it through a 300-mesh sieve to obtain NP co-doped porous carbon support.

[0037] 1 g of N-P co-doped porous carbon support was dispersed in 60 mL of anhydrous ethanol and ultrasonically dispersed for 50 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.03 mol / L and copper nitrate concentration of 0.03 mol / L was prepared. 15 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.015. The pH of the system was adjusted to 6.5 with 0.1 mol / L hydrochloric acid and magnetically stirred at 30 °C for 20 h. The solution was then filtered, washed 5 times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 80 °C for 12 h to form a complex.

[0038] The dried composite was placed in a tube furnace and heated to 400°C at a rate of 5°C / min under a nitrogen atmosphere, and calcined at a constant temperature for 3 hours. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 10%, and the temperature was maintained at 300°C for reduction for 3 hours. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0039] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 250 mL of deionized water as a solvent, add 30 mL of formic acid with a concentration of 0.07 mol / L, and adjust the pH of the system to 3.5 with 0.1 mol / L hydrochloric acid; fill the catalyst into a fixed-bed reactor with an inner diameter of 10 mm, a catalyst bed height of 70 mm (bed height to inner diameter ratio 7:1), and a catalyst loading volume of 30 mL.

[0040] H2 and O2 were mixed at a volume ratio of 1:3.5 (H2 volume percentage 22.2%) and introduced into the reaction system at a flow rate of 150 mL / min under normal pressure (0.1 MPa) and 32 °C. The volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 2 h⁻¹. -1 (Reaction flow rate 60 mL / h), H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 60 h.

[0041] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.2 MPa and the membrane flux was controlled at 10 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 60 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 70 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0042] Example 4 Take 3g of UiO-66 type MOF and mix it with 0.45g of diammonium hydrogen phosphate. Grind the mixture in an agate mortar for 15min until it becomes a uniform powder. Place the mixed powder in a tube furnace and heat it to 520℃ at a heating rate of 6℃ / min under an argon atmosphere. Then, calcine it at a constant temperature for 3.5h. After naturally cooling to room temperature, crush it and pass it through a 220-mesh sieve to obtain an NP co-doped porous carbon support.

[0043] 1.5 g of N-P co-doped porous carbon support was dispersed in 80 mL of anhydrous ethanol and ultrasonically dispersed for 45 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.04 mol / L and copper nitrate concentration of 0.024 mol / L was prepared. 12 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.008. The pH of the system was adjusted to 5.8 with 0.1 mol / L sodium hydroxide solution and magnetically stirred at 26 °C for 18 h. The solution was then filtered, washed three times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 65 °C for 9 h to form the complex.

[0044] The dried composite was placed in a tube furnace and heated to 320°C at a rate of 3.5°C / min under an argon atmosphere, and calcined at this temperature for 1.5 h. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 6%, and the temperature was maintained at 260°C for reduction for 1.5 h. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0045] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 350 mL of deionized water as a solvent, add 40 mL of formic acid with a concentration of 0.08 mol / L, and adjust the pH of the system to 3.7 with 0.1 mol / L sodium hydroxide solution; fill the catalyst into a fixed-bed reactor with an inner diameter of 15 mm and a catalyst bed height of 105 mm (bed height to inner diameter ratio 7:1), and the catalyst loading volume is 40 mL.

[0046] H2 and O2 were mixed at a volume ratio of 1:4 (H2 accounted for 20% by volume) and introduced into the reaction system at a flow rate of 180 mL / min under normal pressure (0.1 MPa) and 35 °C; the volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 2.5 h⁻¹. -1 (Reaction flow rate 100 mL / h), H2 and O2 undergo selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 72 h.

[0047] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.25 MPa, and the membrane flux was controlled at 12 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 72 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 80 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0048] Example 5 Take 4g of UiO-66 type MOF and mix it with 1g of diammonium hydrogen phosphate. Grind the mixture in an agate mortar for 25 minutes until it becomes a uniform powder. Place the mixed powder in a tube furnace and heat it to 580℃ at a rate of 8℃ / min under a nitrogen atmosphere. Then, calcine it at a constant temperature for 4.5 hours. After naturally cooling to room temperature, crush it and pass it through a 280-mesh sieve to obtain an NP co-doped porous carbon support.

[0049] 1.8 g of N-P co-doped porous carbon support was dispersed in 90 mL of anhydrous ethanol and ultrasonically dispersed for 55 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.05 mol / L and copper nitrate concentration of 0.04 mol / L was prepared. 18 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.018. The pH of the system was adjusted to 6.2 with 0.1 mol / L hydrochloric acid and magnetically stirred at 29 °C for 22 h. The solution was then filtered, washed four times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 75 °C for 11 h to form a complex.

[0050] The dried composite was placed in a tube furnace and heated to 380°C at a rate of 4.5°C / min under a nitrogen atmosphere, and calcined at a constant temperature for 2.5 h. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 9%, and the temperature was maintained at 290°C for reduction at a constant temperature for 2.5 h. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0051] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 450 mL of deionized water as a solvent, add 45 mL of formic acid with a concentration of 0.09 mol / L, and adjust the pH of the system to 3.8 with 0.1 mol / L hydrochloric acid; fill the catalyst into a fixed-bed reactor with an inner diameter of 18 mm and a catalyst bed height of 144 mm (bed height to inner diameter ratio 8:1), and the catalyst loading volume is 45 mL.

[0052] H2 and O2 were mixed at a volume ratio of 1:5 (H2 accounted for 20% by volume) and introduced into the reaction system at a flow rate of 190 mL / min under normal pressure (0.1 MPa) and 38 °C; the volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 2.8 h⁻¹. -1 (Reaction flow rate 126 mL / h), H2 and O2 undergo selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 90 h.

[0053] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.28 MPa, and the membrane flux was controlled at 14 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 90 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 90 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0054] Example 6 Take 5g of UiO-66 type MOF and mix it with 1g of diammonium hydrogen phosphate. Grind the mixture in an agate mortar for 20 minutes until it becomes a uniform powder. Place the mixed powder in a tube furnace and heat it to 560℃ at a heating rate of 9℃ / min under an argon atmosphere. Then, calcine it at a constant temperature for 4 hours. After naturally cooling to room temperature, crush it and pass it through a 260-mesh sieve to obtain an NP co-doped porous carbon support.

[0055] 2 g of N-P co-doped porous carbon support was dispersed in 100 mL of anhydrous ethanol and ultrasonically dispersed for 60 min until the support was uniformly suspended. A mixed aqueous solution with PdCl2 concentration of 0.025 mol / L and copper nitrate concentration of 0.03 mol / L was prepared. 20 mL of the mixed metal salt solution was added dropwise to the ethanol suspension of the support at a total molar ratio of support to metal ions of 1:0.02. The pH of the system was adjusted to 6.0 with 0.1 mol / L sodium hydroxide solution and magnetically stirred at 27 °C for 24 h. The solution was then filtered, washed 5 times with deionized water until the filtrate was free of chloride ions, and vacuum dried at 70 °C for 10 h to form a complex.

[0056] The dried composite was placed in a tube furnace and heated to 360°C at a rate of 5°C / min under an argon atmosphere, and calcined at this temperature for 2 hours. Then, the atmosphere was switched to a mixed atmosphere of H2 / Ar, with H2 volume fraction of 8%, and the temperature was maintained at 280°C for reduction for 2 hours. After the reduction was completed, the mixture was naturally cooled to room temperature under an Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

[0057] The following technical solution is adopted for the application of a catalyst for the efficient catalytic synthesis of hydrogen peroxide: Take 500 mL of deionized water as a solvent, add 50 mL of 0.1 mol / L formic acid, and adjust the pH of the system to 4.0 with 0.1 mol / L sodium hydroxide solution; fill the catalyst into a fixed-bed reactor with an inner diameter of 20 mm and a catalyst bed height of 160 mm (bed height to inner diameter ratio 8:1), and the catalyst loading volume is 50 mL.

[0058] H2 and O2 were mixed at a volume ratio of 1:4.5 (H2 volume percentage 22.2%) and introduced into the reaction system at a flow rate of 200 mL / min under normal pressure (0.1 MPa) and 40 °C. The volume hourly space velocity (VHSV) of the reaction solution through the fixed-bed reactor was 3 h⁻¹. -1 (Reaction flow rate 150 mL / h), H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2, and the reaction continues for 100 h.

[0059] The reaction effluent was separated by a ceramic ultrafiltration membrane with a molecular weight cutoff of 1000 Da. The operating pressure was 0.3 MPa and the membrane flux was controlled at 15 L / (m²・h). After removing trace catalyst particles, hydrogen peroxide was obtained. After the catalyst was continuously running for 100 h, the reaction was stopped, and an O2 / Ar mixed atmosphere (O2 volume fraction 10%) was introduced at a gas flow rate of 100 mL / min. The mixture was treated at 300 °C for 2 h, and the reaction was resumed after natural cooling to achieve active regeneration.

[0060] Performance testing H2 conversion rate: tested according to GB / T 39224-2020 "Test Method for Performance of Catalysts for Hydrogen Energy Catalytic Conversion"; Catalyst stability (activity retention rate after continuous operation): Performance testing was conducted using HG / T 5706-2020 "Test Method for Stability of Industrial Catalysts"; The results are shown in Table 1 below: Table 1 Performance Test Table

[0061] Comparing the test results of Examples 1-6 above, it can be found that: This application significantly improves the catalytic performance of hydrogen peroxide synthesis through the synergistic design of Pd-Cu bimetallic single-atom alloy sites and NP-co-doped porous carbon supports. The bimetallic single-atom alloy sites, leveraging the electronic synergistic effect of the two metals, precisely regulate the electron density and coordination environment of the active centers, effectively optimizing the balance between oxygen adsorption and hydrogen peroxide desorption, and significantly suppressing side reactions such as water or oxygen decomposition. This solves the core problem of the difficulty in balancing activity and selectivity in traditional single-metal catalysts. Simultaneously, the NP-co-doped porous carbon support, with its abundant anchoring sites and unique electronic regulation, achieves uniform dispersion and stable loading of the active centers, avoiding the defects of easy aggregation and deactivation of active sites in traditional catalysts, and extending the catalyst's service life. This structural synergistic effect makes the catalytic reaction kinetics more efficient, providing a superior catalytic system for the direct synthesis of hydrogen peroxide, and completely breaking through the bottlenecks of catalytic efficiency and stability in existing technologies.

[0062] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0063] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0064] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0065] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A highly efficient catalyst for the catalytic synthesis of hydrogen peroxide, characterized in that, It includes a porous carrier and alloy sites loaded on the surface of a functionalized carrier, wherein the alloy sites are Pd-Cu bimetallic single-atom alloy sites.

2. The high-efficiency catalyst for the catalytic synthesis of hydrogen peroxide according to claim 1, characterized in that, The porous support is an NP-co-doped porous carbon support.

3. The high-efficiency catalyst for the catalytic synthesis of hydrogen peroxide according to claim 1, characterized in that, The MOF is a UiO-66 metal-organic framework material, and the mass ratio of the UiO-66 metal-organic framework material to diammonium hydrogen phosphate is 10:1-10:

3.

4. A method for preparing a highly efficient catalyst for the catalytic synthesis of hydrogen peroxide according to any one of claims 1-3, characterized in that, The preparation steps include the following: MOF was mixed with diammonium hydrogen phosphate and calcined at 500-600℃ for 3-5 hours under an inert atmosphere to obtain NP co-doped porous carbon support. NP co-doped porous carbon support was dispersed in an ethanol solution, and a mixed aqueous solution of Pd and Cu salts was added. The pH of the system was adjusted to 5.5-6.5, and the mixture was stirred at room temperature to form a composite. The composite was calcined at 300-400℃ for 1-3 hours under an inert atmosphere, and then reduced at 250-300℃ under a mixed H2 / Ar atmosphere to obtain a highly efficient catalyst for the synthesis of hydrogen peroxide.

5. The method for preparing a highly efficient catalyst for the catalytic synthesis of hydrogen peroxide according to claim 4, characterized in that, The Cu salt is copper nitrate; the volume fraction of H2 in the H2 / Ar mixed atmosphere is 5%-10%.

6. The method for applying the catalyst for the efficient catalytic synthesis of hydrogen peroxide according to any one of claims 1-3, characterized in that, Includes the following steps: Using deionized water as a solvent, a proton modifier was added to adjust the pH of the system to 3.0-4.0; the highly efficient catalytic synthesis of hydrogen peroxide was carried out in a fixed-bed reactor with the catalyst filling the catalyst bed height to inner diameter ratio of 5:1-8:1; H2 and O2 are mixed in a volume ratio of 1:3 to 1:5 and introduced into the reaction system at a flow rate of 100 to 200 mL / min under normal pressure and 25-40℃ conditions. The space velocity of the reaction liquid through the fixed-bed reactor is 1-3 h⁻¹. -1 H2 and O2 undergo a selective reduction reaction on the catalyst surface to generate H2O2; The reaction effluent is separated by a separation membrane to remove trace amounts of catalyst particles, yielding hydrogen peroxide product; After continuous operation of the catalyst, it is treated at 300°C for 2 hours by introducing an O2 / Ar mixed atmosphere to achieve active regeneration.

7. The application method of the catalyst for the efficient catalytic synthesis of hydrogen peroxide according to claim 6, characterized in that, The proton regulator is formic acid, and the concentration of formic acid is 0.05-0.1 mol / L.

8. The application method of the catalyst for the efficient catalytic synthesis of hydrogen peroxide according to claim 6, characterized in that, The separation membrane has a molecular weight cutoff of 1000 Da.

9. The application method of the catalyst for the efficient catalytic synthesis of hydrogen peroxide according to claim 6, characterized in that, The volume fraction of O2 in the O2 / Ar mixed atmosphere is 10%.

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