Preparation method of copper monatomic catalyst, catalyst and application of catalyst in continuous catalytic oxidation removal of hydrogen phosphide

Abstract

The invention discloses a preparation method of a copper monatomic catalyst, the catalyst and application of the catalyst in continuous catalytic oxidation removal of hydrogen phosphide, and belongs to the technical field of environmental functional materials and air pollution control. The preparation method comprises the steps of pretreatment, preparation of a mixed solution, drying, primary calcination, preparation of a precursor and secondary calcination. The catalyst is prepared according to the preparation method. The application comprises the steps of introducing industrial waste gas, controlling reaction conditions and regenerating the catalyst. The catalyst disclosed by the invention has a definite monatomic active site and a developed pore structure, shows excellent catalytic oxidation activity on hydrogen phosphide under a low-temperature condition, has the removal efficiency of 99% or above, and can realize deep purification when the concentration of hydrogen phosphide is reduced to 1 mg. M <-3 > or below. Meanwhile, the catalyst has good regeneration performance and stability, is suitable for treatment of industrial waste gas with different oxygen concentrations, and provides an efficient and economical technical scheme for air pollution treatment.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials and air pollution control technology, specifically relating to a method for preparing a copper single-atom catalyst and the application of the catalyst in continuous catalytic oxidation for the removal of phosphine. Background Technology

[0002] Phosphine (PH3), a highly toxic, flammable gas with global warming potential, presents a significant challenge for environmental engineering and industrial waste gas treatment in terms of emission control. The unique electronic structure (lone pairs of electrons) and physical properties (kinetic diameter of only 0.32 nm and dipole moment of only 0.58 D) of the PH3 molecule result in its chemical stability, making it difficult to be efficiently adsorbed or catalytically converted. This gas is widely present in waste gases from various industrial processes, including white phosphorus (yellow phosphorus) production, the semiconductor and optoelectronic industries, acetylene production (calcium carbide furnace waste gas), and biomass anaerobic fermentation processes such as biogas and landfill gas. Particularly in the warehousing industry, although the concentration of phosphine in exhaust gas is not high, its extremely high toxicity (human exposure to levels of 50 ppm can be fatal) and stringent emission standards make the development of advanced purification technologies for phosphine urgently needed.

[0003] Existing phosphine removal methods are mainly divided into two categories: wet and dry methods. Wet purification technologies, such as those using strong acids or strong oxidizing solutions like concentrated sulfuric acid, sodium hypochlorite, and potassium permanganate for absorption, can achieve high initial purification efficiencies, but their inherent drawbacks limit large-scale application: the process system is complex, requiring large absorption towers and liquid circulation systems, resulting in a large footprint; the absorbent is prone to failure and has high consumption, leading to high operating costs; more importantly, the reaction produces a variety of byproducts, such as phosphites and phosphates, generating large amounts of difficult-to-treat phosphorus-containing wastewater and solid waste, posing a serious risk of secondary pollution. In contrast, dry purification technologies have become a research hotspot due to their simple processes and lack of secondary pollution (or minimal pollution). Dry methods involve the adsorption and conversion of PH3 by adsorbents / catalysts or the direct catalytic decomposition of PH3 using catalysts, including physical / chemical adsorption methods, catalytic decomposition methods, plasma degradation methods, combustion methods, and biological methods.

[0004] Although adsorption is one of the commonly used dry technologies, which relies on impregnated activated carbon or molecular sieves and other porous materials to remove PH3 through physical adsorption or surface chemical reaction, it has significant limitations: On the one hand, ordinary activated carbon has a limited adsorption capacity for PH3, and its adsorption performance is easily inhibited by the large amount of water vapor (kinetic diameter 0.28 nm) and carbon dioxide (0.33 nm) coexisting in the waste gas - since these molecules are similar in size to PH3 (0.32 nm), they produce a strong competitive adsorption effect; on the other hand, the material is difficult to regenerate after adsorption saturation, the thermal regeneration process is energy-intensive and has a large carbon loss, while direct disposal brings secondary solid waste problems. In comparison, catalytic decomposition and catalytic oxidation show greater potential for deep purification. Catalytic decomposition requires high temperature to decompose PH3 into phosphorus and hydrogen, but it has disadvantages such as high reaction temperature and high risk of elemental phosphorus blockage. Catalytic oxidation, on the other hand, directly oxidizes PH3 into P2O5 and further converts it into phosphoric acid under aerobic conditions with the help of a catalyst, thereby achieving stable solidification of phosphorus. It is currently a more promising technical route. Its core challenge lies in developing a catalyst that combines low temperature, high activity, high stability, and low cost.

[0005] In the selection of active components for catalytic oxidation catalysts, inexpensive transition metal oxides, especially CuO, have been proven to have the best intrinsic activity for PH3. However, traditional supported CuO nanoparticle catalysts still face several key bottlenecks: First, only surface atoms of nanoscale CuO participate in the reaction, resulting in low metal atom utilization; second, during the reaction, the generated P2O5 or phosphoric acid easily covers the active sites, causing rapid catalyst deactivation, and nanoparticles are prone to migration and sintering under thermal conditions, further exacerbating activity degradation; in addition, such catalysts have weak resistance to complex waste gas environments (such as water vapor and impurity gases), and regeneration after deactivation is particularly difficult—phosphorus-containing species deposited on the surface are difficult to completely remove through thermal regeneration, and the regeneration process may even trigger sintering of the active components, leading to irrecoverable performance. Although noble metal catalysts (such as Pd and Pt) perform better in terms of low-temperature activity and anti-toxicity, their high cost severely limits their large-scale application in industrial scenarios.

[0006] In recent years, the emergence of single-atom catalysts (SACs) has provided a revolutionary approach to solving the aforementioned challenges. SACs, by anchoring metal atoms as isolated individual atoms on a support, can theoretically achieve 100% atomic utilization. Due to changes in the electronic structure and coordination environment of the metal center, they often exhibit unique catalytic activity and selectivity different from their nanoparticle form. However, successfully applying the single-atom catalysis concept to the field of PH3 purification still requires overcoming two major challenges: first, how to design suitable supports and preparation processes to achieve the long-term stable existence of copper single atoms in complex reaction environments and prevent their migration and aggregation; second, how to find an inexpensive and scalable support and precursor to match the stringent cost requirements of PH3 waste gas treatment.

[0007] In summary, existing technologies all have significant shortcomings: wet processes cause severe secondary pollution, dry processes have limited adsorption capacity and are difficult to regenerate, and traditional catalytic methods face the dilemma of balancing activity, stability, and cost. Therefore, developing a novel catalyst based on inexpensive materials, simple to prepare, possessing high-density stable active sites, and easily regenerable is key to overcoming the bottlenecks in deep PH3 purification technology. Summary of the Invention

[0008] To address the problems of low catalyst activity, poor stability, high cost, and insufficient renewability in existing phosphine purification technologies, the primary objective of this invention is to provide a method for preparing a copper single-atom catalyst. This method uses waste biomass as raw material and constructs a single-atom active center with a clear Cu–N4 coordination structure through nitric acid pretreatment, urea and potassium hydroxide-assisted activation, and a two-step calcination process.

[0009] A second objective of this invention is to provide a copper single-atom catalyst prepared according to the method described above.

[0010] The third objective of this invention is to provide the application of the copper single-atom catalyst in the continuous catalytic oxidation removal of phosphine, thereby achieving efficient and stable catalytic oxidation removal of phosphine under continuous operating conditions.

[0011] The first objective of this invention is achieved by the following steps: S1. The biomass is soaked in dilute nitric acid and shaken. After the treatment, the biomass is taken out, washed until neutral, and then dried to obtain pretreated biomass. S2. Dissolve urea and potassium hydroxide in water to form a mixed solution. Add the pretreated biomass obtained in step S1 to the mixed solution and treat it with ultrasound to obtain a uniformly dispersed mixed solution. S3. Dry the mixed solution obtained in step S2 to obtain a brown powder; S4. The brown powder obtained in step S3 is calcined under an inert atmosphere to obtain biomass-derived biochar. S5. Dissolve copper nitrate and urea in anhydrous ethanol, add the biomass-derived biochar obtained in step S4, and then treat with ultrasound and dry to obtain the precursor. S6. The precursor obtained in step S5 is calcined under an inert atmosphere or under Joule heating to obtain a copper single-atom catalyst. In the copper single-atom catalyst, copper exists in the form of single atoms in the nitrogen-rich carbon framework, forming a Cu-N4 coordination structure.

[0012] In the preparation method of this invention, the time for all ultrasonic treatment steps is 0.5h to 3h.

[0013] Preferably, the biomass in step S1 includes one or more of coffee grounds, rice husks, straw, and sawdust.

[0014] Preferably, the volume concentration of dilute nitric acid in step S1 is 0.5%~10%, and the shaking treatment time is not less than 24 hours.

[0015] Preferably, in step S2, the mass ratio of urea to pretreated biomass is 1-5:1, and the mass ratio of potassium hydroxide to pretreated biomass is 1:2-10.

[0016] Preferably, the calcination temperature in step S4 is 400℃~1000℃ and the calcination time is 0.5h~5h, and the calcination temperature in step S6 is 500℃~900℃.

[0017] Preferably, in step S5, the amount of copper nitrate added is 0.5% to 5% of the mass of biomass-derived biochar based on the mass of copper element, and the amount of urea added is 5% to 10% of the mass of biomass-derived biochar.

[0018] The second objective of this invention is achieved by preparing a copper single-atom catalyst according to the aforementioned method, wherein the catalyst has a specific surface area of ​​800 m². 2 / g~1500m 2 g, with a saturated adsorption capacity of 0 mg·g for phosphine. -1 ~12000mg·g -1 .

[0019] The third objective of this invention is achieved by the following steps in the application method: (1) The industrial waste gas containing phosphine is passed into a fixed-bed reactor filled with copper single-atom biomass biochar catalyst; (2) Control the reaction temperature at 90℃~150℃ and the space velocity at 10000mL·h -1 ·g -1 ~30000 mL·h -1 ·g-1 Under certain conditions, phosphine is brought into contact with a catalyst and catalytically oxidized to phosphoric acid or phosphorus pentoxide; (3) When the catalyst is deactivated by penetration, it is regenerated by washing with deionized water at 50℃~80℃, or by heat treatment at 100℃~150℃ in an inert atmosphere to achieve continuous operation of the system.

[0020] Preferably, the industrial waste gas in step (1) is semiconductor process waste gas containing phosphine, calcium carbide furnace tail gas, warehouse fumigation waste gas or biogas, with an initial concentration of 10ppm to 5000ppm and an oxygen content of 0.5% to 10%.

[0021] Preferably, the reaction temperature in step (2) is 90℃~150℃, and the space velocity is 10000mL·h. -1 ·g -1 ~30000 mL·h -1 ·g -1 .

[0022] In step (3), after five regeneration cycles, the catalyst still maintains a removal efficiency of over 85% for 1000 ppm phosphine.

[0023] Compared with the prior art, the present invention has the following technical effects: 1. The preparation method of this invention has low raw material cost and is green and sustainable. The preparation method of this invention uses waste biomass as the main raw material and successfully prepares high-performance copper single-atom catalyst through simple chemical activation and calcination process. It not only realizes the resource utilization of "waste treatment", but also significantly reduces the production cost of catalyst and has economic feasibility for large-scale application. 2. The preparation method of this invention is precise and controllable; by adjusting the amount of urea and the two-step calcination process, the degree of nitrogen doping is precisely controlled and the atomic-level dispersion of copper atoms is achieved, ensuring the high density and uniformity of the catalyst active sites. 3. The copper single-atom catalyst of this invention exhibits excellent catalytic performance and a wide range of applications. Under conditions close to actual industrial tail gas, the copper single-atom catalyst prepared according to the method of this invention demonstrates high removal capacity and excellent catalytic oxidation efficiency for phosphine, achieving a phosphine concentration reduction to 1 mg∙m⁻¹. -3 The following deep purification effects can meet the stringent requirements of different industries for phosphine purification; 3. The copper single-atom catalyst of this invention has clearly defined active sites and a stable structure; through the synergistic effect of the nitrogen element of biomass itself and urea modification, abundant nitrogen doping sites are constructed in the carbon framework, providing an ideal coordination environment for copper atoms, forming a stable Cu-N4 single-atom active center, which significantly improves the intrinsic activity and stability of the catalyst. 4. The copper single-atom catalyst of this invention has a reasonable pore structure and excellent mass transfer performance; the dilute nitric acid pretreatment not only effectively removes impurities such as oils from biomass, but also optimizes the pore structure of the catalyst, forming a well-developed pore system and a high specific surface area, which provides convenient conditions for the mass transfer and diffusion of reactants and products. 6. The copper single-atom catalyst of this invention has excellent regeneration performance and long service life; the unique Cu-N4 coordination structure endows the catalyst with excellent anti-sintering ability and structural stability. After deactivation, most of the activity can be restored through simple regeneration treatment, overcoming the technical difficulties of easy deactivation and difficult regeneration of traditional copper-based catalysts, and significantly extending the service life of the catalyst. 7. The application method for removing phosphine in this invention has a high degree of process integration and is easy to operate; it organically combines the preparation of catalyst with the continuous catalytic oxidation removal process of phosphine to form a complete technical solution. The system operates stably and is easy to operate and maintain, providing reliable technical support for industrial applications. Attached Figure Description

[0024] Figure 1 The BET plot for the copper single-atom catalyst in Example 5 is shown below. Figure 2 The image shows the XRD pattern of the copper single-atom catalyst in Example 5. Figure 3 The graph shows the dephosphorization efficiency at different reaction temperatures in Comparative Example 1. Figure 4 The calculated phosphorus capacity diagram for different reaction temperatures in Comparative Example 1; Figure 5 The graph shows the phosphorus removal efficiency at different oxygen concentrations in Comparative Example 2. Figure 6 The calculated phosphorus capacity diagram for different oxygen concentrations in Comparative Example 2; Figure 7 The graph shows the dephosphorization efficiency after multiple regenerations in Test Example 1. Figure 8 The phosphorus content diagram for multiple regenerations in Test Example 1. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0026] Example 1 The preparation method of the copper single-atom catalyst in this embodiment includes the following steps: S1. Soak coffee grounds in 5% dilute nitric acid and shake for 24 hours. After the treatment, remove the raw material, wash it until neutral, and then dry it to obtain pretreated coffee grounds. S2. Dissolve 12g of urea and 3g of potassium hydroxide in 160mL of water to form a mixed solution. Add 6g of the pretreated coffee grounds obtained in step S1 to the mixed solution and sonicate to obtain a uniformly dispersed mixed solution. S3. Dry the mixed solution obtained in step S2 at 80°C to obtain a brown powder; S4. Under a nitrogen atmosphere, the brown powder obtained in step S3 is calcined at 400°C for 1 hour, and then heated to 700°C for 1 hour to obtain NrC support material. S5. Dissolve 0.0058g of copper nitrate trihydrate and 0.2g of urea in 160mL of anhydrous ethanol, add 2g of NrC carrier material obtained in step S4, ultrasonically disperse for 30min, and dry at 80℃ to obtain the precursor. S6. The precursor obtained in step S5 is calcined at 500°C under Joule heating to obtain the copper single-atom catalyst Cu1 / NC-P. In the copper single-atom catalyst, copper exists in the form of single atoms in the nitrogen-rich carbon framework, forming a Cu-N4 coordination structure.

[0027] Example 2 The preparation method of the copper single-atom catalyst in this embodiment is based on Example 1, but differs from Example 1 in the following ways: In step S1, rice husks are used as biomass, the volume concentration of dilute nitric acid is 0.5%, and the mixture is shaken for 26 hours; In step S2, 8g of urea, 0.8g of potassium hydroxide, and 8g of pretreated rice husks are used; In step S4, the calcination temperature is 400℃ and the calcination time is 0.5 hours; In step S5, 0.0030g of copper nitrate trihydrate, 0.01g of urea, and 0.2g of NrC support material are used; In step S6, the calcination temperature is 500℃.

[0028] Example 3 The preparation method of the copper single-atom catalyst in this embodiment is based on Example 1, but differs from Example 1 in the following ways: In step S1, the biomass used is straw, the volume concentration of dilute nitric acid is 10%, and the treatment is shaken for 28 hours; in step S2, 40g of urea, 4g of potassium hydroxide, and 8g of pretreated rice husks are used; in step S4, the calcination temperature is 1000℃ and the calcination time is 5 hours; in step S5, 0.030g of copper nitrate trihydrate, 0.2g of urea, and 2g of NrC support material are used; and in step S6, the calcination temperature is 900℃.

[0029] Example 4 The preparation method of the copper single-atom catalyst in this embodiment is based on Example 1, but differs from Example 1 in the following ways: In step S1, the biomass used is coffee grounds, rice husks, straw, and sawdust in a mass ratio of 1:1:1:1, the volume concentration of dilute nitric acid is 5.25%, and the mixture is shaken for 30 hours; In step S2, 24g of urea, 1.33g of potassium hydroxide, and 8g of pretreated rice husks are used; In step S4, the calcination temperature is 700℃, and the calcination time is 2 hours and 45 minutes; In step S5, 0.0148g of copper nitrate trihydrate, 0.15g of urea, and 2g of NrC support material are used; In step S6, the calcination temperature is 700℃.

[0030] Example 5 The copper single-atom catalyst was prepared according to the preparation method of copper single-atom catalyst in Example 1.

[0031] Example 6 The copper single-atom catalyst was prepared according to the preparation method of copper single-atom catalyst in Example 2.

[0032] Example 7 The copper single-atom catalyst was prepared according to the preparation method of copper single-atom catalyst in Example 3.

[0033] Example 8 The copper single-atom catalyst was prepared according to the preparation method of copper single-atom catalyst in Example 4.

[0034] Example 9 The application of copper single-atom catalysts in the continuous catalytic oxidation removal of phosphine includes the following steps: (1) A mixed gas of PH3 1000ppm, O2 1%, and N2 balance gas was introduced into a fixed-bed reactor packed with the copper single-atom catalyst of Example 5; (2) The reaction temperature was controlled at 150℃, and the space velocity was 30000 mL·h. -1 ·g -1 Under certain conditions, phosphine is brought into contact with the catalyst and catalytically oxidized. The concentration of pH3 at the outlet is continuously monitored by an online monitoring system during the reaction process. (3) When the outlet pH3 concentration reaches 100ppm, it is considered to be breakthrough, and it is regenerated by washing with 50℃ deionized water.

[0035] Experimental Example 1 The copper single-atom catalyst of Example 5 was subjected to N2 adsorption-desorption tests using a fully automated specific surface area and porosity analyzer (Quantachrome EVO, USA) to analyze its pore structure characteristics. Before the test, the sample was degassed under vacuum at 453 K for 6 h to remove surface adsorbates. The BET specific surface area, total pore volume, and pore size distribution of the material were calculated by analyzing the adsorption / desorption isotherms. The results are as follows: Figure 1As shown, the Cu1 / NC-P sample exhibits typical mesoporous characteristics with a well-developed pore structure and a BET specific surface area as high as 1262.553 m². 2 ·g -1 This indicates that the material has abundant gas adsorption and mass transfer channels.

[0036] Experiment Example 2 The copper single-atom catalyst of Example 5 was analyzed by X-ray diffraction (Rigaku Miniflex 600, CuKα radiation). The test conditions were: scan range 5–90° (2θ), scan rate 5... ° ·min -1 The result is as follows Figure 2 As shown, no obvious crystallization diffraction peaks belonging to copper species (such as Cu, CuO, or Cu2O) appeared in the XRD spectra of any of the samples, indicating that the copper species are highly dispersed in the carbon support and exist in an amorphous or atomic form, further confirming the successful construction of copper single-atom active sites.

[0037] Comparative Example 1: Effect of different reaction temperatures Based on Example 9, the reaction temperatures in step (2) were set at 30°C, 60°C, 90°C, and 120°C as comparative examples, with other conditions being the same as in Example 9. The PH3 removal performance at different temperatures was investigated, and the removal efficiency and phosphorus capacity of each catalyst for phosphine in the simulated mixed gas were calculated based on the measurement results. The change in PH3 removal efficiency with reaction time is as follows: Figure 3 As shown in the figure, the reaction temperature has a significant impact on the catalyst performance: within the range of 30℃ to 150℃, the removal efficiency and duration of PH3 by the catalyst are significantly improved with increasing temperature. At 150℃, the catalyst in Example 1 can achieve nearly 100% PH3 removal in the initial stage of the reaction, and its 90% breakthrough time is significantly prolonged, indicating that it has excellent low-temperature catalytic activity and stability.

[0038] Phosphine adsorption capacity of catalyst at different reaction temperatures, such as Figure 4 As shown. In Example 1, the catalyst exhibited a high PH3 adsorption capacity of 836.231 mg·g at 150°C. -1 The concentration was significantly higher than that of other comparative studies and under low-temperature conditions (e.g., only 42.715 mg·g at 30°C). -1 This further confirms that increasing the reaction temperature helps enhance the catalyst's catalytic oxidation ability for PH3, significantly increasing its phosphorus capacity. (Summary) Figure 3 and Figure 4It is known that the copper single-atom biomass biochar catalyst prepared by the present invention has good PH3 purification performance and high phosphorus capacity at medium temperature (90℃~150℃), and is suitable for efficient removal of phosphine under medium and low temperature conditions.

[0039] Comparative Example 2: Effect of Different Oxygen Concentrations Based on Example 9, in step (1), the O2 concentration was set to 0% and 21% respectively as comparative examples, and other conditions were the same as in Example 9. The effect of different oxygen concentrations on the removal of PH3 was investigated, and the removal efficiency and phosphorus capacity of the catalyst at different oxygen concentrations were calculated based on the measurement results. The change in PH3 removal efficiency with reaction time is as follows: Figure 5 As shown in the figure, oxygen concentration has a significant impact on catalyst performance. Under different oxygen concentrations, the catalyst exhibits different removal characteristics: under anaerobic conditions (0%), the catalyst mainly removes PH3 through physical adsorption, with a low removal efficiency; at a 1% oxygen concentration, the catalyst exhibits the best catalytic oxidation performance; while under a high oxygen concentration of 21%, the removal efficiency decreases.

[0040] Phosphine adsorption capacity of catalysts under different oxygen concentrations, as follows Figure 6 As shown. The PH3 adsorption capacity of the catalyst in Example 1 at different oxygen concentrations was: 11.052 mg / g at 0% oxygen concentration. -1 At a 1% oxygen concentration, the concentration is 836.231 mg / g. -1 At a 21% oxygen concentration, the result was 601.669 mg / g. -1 The results show that oxygen concentration has a decisive influence on the phosphine removal capacity of the catalyst.

[0041] Test Example 1: Regeneration Performance Test of Copper Single-Atom Catalyst The catalyst deactivated by breakthrough in Example 9 was removed, washed with deionized water at 50°C for 1 hour, and then dried at 100°C for 24 hours to complete the regeneration process. This regeneration-test cycle was performed twice to systematically evaluate the catalyst's regeneration performance. The changes in phosphine removal efficiency in three consecutive tests are shown below. Figure 7 As shown in the figure. The results show that after two rounds of regeneration, the catalyst still maintains excellent PH3 removal capacity under the same reaction conditions, and its 90% breakthrough time is not significantly shortened. The removal efficiency curves of each cycle highly overlap, indicating that the catalyst prepared by this invention has significant and stable regenerability.

[0042] Changes in the phosphorus capacity of the catalyst during regeneration, such as Figure 8 As shown. The initial phosphorus capacity of the fresh catalyst is 1634.693 mg·g. -1After the first regeneration (Re-Cu-SAs / NC-800), the phosphorus capacity was 736.387 mg·g. -1 After the second regeneration, the phosphorus capacity remained at 597.793 mg·g. -1 The results showed that although the phosphorus capacity of the catalyst decreased after regeneration, it still maintained a considerable level of phosphine removal capacity after two regeneration cycles, demonstrating that the catalyst has good regeneration stability and recycling potential. Figure 7 and Figure 8 It is evident that the copper single-atom catalyst provided by this invention not only possesses excellent initial phosphine removal performance, but also exhibits good regeneration stability. This characteristic provides an important guarantee for its long-term application in continuous industrial operation.

[0043] Example 10 The application of copper single-atom catalyst in the continuous catalytic oxidation removal of phosphine is based on Example 9, but differs from Example 9 in the following ways: Step (1) uses the copper single-atom catalyst of Example 6, and the industrial waste gas is semiconductor process waste gas containing phosphine, with an initial concentration of 10 ppm and an oxygen content of 0.5%; Step (2) the reaction temperature is 90℃ and the space velocity is 10000 mL·h. -1 ·g -1 Step (3) Regeneration by heat treatment at 100°C in an inert atmosphere.

[0044] Example 11 The application of copper single-atom catalyst in continuous catalytic oxidation for the removal of phosphine is based on Example 9, but differs from Example 9 in the following ways: Step (1) uses the copper single-atom catalyst of Example 7, and the industrial waste gas is selected as calcium carbide furnace tail gas containing phosphine, with an initial concentration of 5000 ppm and an oxygen content of 10% in the waste gas; Step (2) the reaction temperature is 150℃ and the space velocity is 30000 mL·h. -1 ·g -1 Step (3) Wash and regenerate with 80℃ deionized water.

[0045] Example 12 The application of copper single-atom catalyst in the continuous catalytic oxidation removal of phosphine is based on Example 9, but differs from Example 9 in the following ways: Step (1) uses the copper single-atom catalyst of Example 8, and the industrial waste gas is selected as phosphine-containing warehouse fumigation waste gas with an initial concentration of 2505 ppm and an oxygen content of 5.25%; Step (2) the reaction temperature is 120℃ and the space velocity is 20000 mL·h. -1 ·g -1 Step (3) involves heat treatment and regeneration at 125°C under an inert atmosphere.

Claims

1. A method for preparing a copper single-atom catalyst, characterized in that... Includes the following steps: S1. The biomass is soaked in dilute nitric acid and shaken. After the treatment, the biomass is taken out, washed until neutral, and then dried to obtain pretreated biomass. S2. Dissolve urea and potassium hydroxide in water to form a mixed solution. Add the pretreated biomass obtained in step S1 to the mixed solution and treat it with ultrasound to obtain a uniformly dispersed mixed solution. S3. Dry the mixed solution obtained in step S2 to obtain a brown powder; S4. The brown powder obtained in step S3 is calcined under an inert atmosphere to obtain biomass-derived biochar. S5. Dissolve copper nitrate and urea in anhydrous ethanol, add the biomass-derived biochar obtained in step S4, and then treat with ultrasound and dry to obtain the precursor. S6. The precursor obtained in step S5 is calcined under an inert atmosphere or under Joule heating to obtain a copper single-atom catalyst. In the copper single-atom catalyst, copper exists in the form of single atoms in the nitrogen-rich carbon framework, forming a Cu-N4 coordination structure.

2. The method for preparing the copper single-atom catalyst according to claim 1, characterized in that... The biomass mentioned in step S1 includes one or more of coffee grounds, rice husks, straw, and sawdust.

3. The method for preparing the copper single-atom catalyst according to claim 1, characterized in that... The volume concentration of dilute nitric acid in step S1 is 0.5%~10%, and the shaking treatment time is not less than 24 hours.

4. The method for preparing the copper single-atom catalyst according to claim 1, characterized in that... In step S2, the mass ratio of urea to pretreated biomass is 1~5:1, and the mass ratio of potassium hydroxide to pretreated biomass is 1:2~10.

5. The method for preparing the copper single-atom catalyst according to claim 1, characterized in that... The calcination temperature for step S4 is 400℃~1000℃, and the calcination time is 0.5h~5h. The calcination temperature for step S6 is 500℃~900℃.

6. The method for preparing the copper single-atom catalyst according to claim 1, characterized in that... In step S5, the amount of copper nitrate added is 0.5% to 5% of the mass of biomass-derived biochar, and the amount of urea added is 5% to 10% of the mass of biomass-derived biochar.

7. A copper single-atom catalyst prepared by the method according to any one of claims 1 to 6.

8. The application of a copper single-atom catalyst according to claim 7 in the continuous catalytic oxidation removal of phosphine.

9. The application according to claim 8, characterized in that... The application method includes the following steps: (1) The industrial waste gas containing phosphine is passed into a fixed-bed reactor filled with copper single-atom biomass biochar catalyst; (2) Control the reaction temperature at 90℃~150℃ and the space velocity at 10000mL·h -1 ·g -1 ~30000 mL·h -1 ·g -1 Under certain conditions, phosphine is brought into contact with the catalyst and catalytically oxidized; (3) When the catalyst is deactivated by penetration, it is regenerated by washing with deionized water at 50℃~80℃, or by heat treatment at 100℃~150℃ in an inert atmosphere.

10. The application method according to claim 9, characterized in that... The industrial waste gas mentioned in step (1) is semiconductor process waste gas containing phosphine, calcium carbide furnace tail gas, warehouse fumigation waste gas or biogas, with an initial concentration of 10ppm~5000ppm and an oxygen content of 0.5%~10%.

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