A biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst and its preparation method and application

Abstract

The present invention belongs to the technical field of catalysts and catalytic methods, and specifically relates to a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst, its preparation method, and application. Furthermore, the present invention also discloses a method for the catalytic oxidation of sulfur-containing volatile organic pollutants using ozone. The preparation method of the catalyst comprises the following steps: mixing a biomass raw material and a metal salt, pre-pyrolyzing at 450-600°C under a nitrogen atmosphere, then heating to 700-900°C for annealing, and post-processing to prepare a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst; the metal salt accounts for 0.8-3.0 wt.% of the mass percentage of the biomass raw material; the metal in the metal salt is a transition metal; the catalyst comprises carbon nanotubes and a metal supported on the walls of the carbon nanotubes; and the average diameter of the carbon nanotubes is 8-50 nm. The catalyst provided by the present invention has excellent catalytic activity and exhibits excellent removal efficiency and stability for S-VOCs.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and catalytic methods, and particularly relates to a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Sulfur-containing volatile organic compounds (S-VOCs), due to their sulfur content, not only share typical VOC characteristics but also possess a very low olfactory threshold, are often accompanied by a foul odor, and are prone to acid deposition, posing a significant threat to the ecological environment and human health. These pollutants are difficult to purify due to the generation of sulfur-containing byproducts during the purification process and the complexity of S-VOC emission sources and categories. This makes their removal particularly challenging.

[0003] Heterogeneous ozone catalytic oxidation technology has become a highly promising technology for S-VOC removal due to its simple operation, high efficiency, low energy consumption, and minimal secondary pollution. Electrophilic ozone molecules are adsorbed and activated by the active sites of the catalyst at room temperature and pressure, producing a large number of highly oxidizing reactive oxygen species, enabling the sustained and efficient removal of S-VOCs. During the S-VOC removal process, the mass transfer and diffusion behavior of pollutant and oxidant molecules at the catalyst surface, as well as the electronic interactions between the active sites of the catalyst and different molecules, are crucial for understanding the source of activity and promoting the long-term use of the catalyst.

[0004] Patent Publication No. CN118237062A discloses a nitrogen-doped carbon nanotube-coated metal cobalt composite material. The method comprises mixing melamine, graphite-phase carbon nitride, and an inorganic cobalt salt to obtain a mixed raw material; calcining the mixed raw material in a protective atmosphere to obtain a calcined material; and washing and drying the calcined material to obtain the nitrogen-doped carbon nanotube-coated metal cobalt composite material. The patent also discloses that the composite material can be used for the catalytic degradation of methylene blue. However, the composite material still has poor performance in removing S-VOCs. Summary of the Invention

[0005] In response to the above-mentioned existing technical problems, the primary objective of the present invention is to provide a method for preparing a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst. The catalyst prepared by this method exhibits excellent catalytic activity during ozone catalytic oxidation, and demonstrates excellent removal efficiency and stability for S-VOCs.

[0006] The second object of the present invention is to provide a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst prepared by the above preparation method.

[0007] The third object of the present invention is to provide an application of biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst in the ozone catalytic oxidation of sulfur-containing volatile organic pollutants.

[0008] A fourth object of the present invention is to provide a method for catalytically oxidizing sulfur-containing volatile organic pollutants using ozone.

[0009] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A method for preparing a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises the following steps: mixing a biomass raw material and a metal salt, pre-pyrolyzing the mixture at 450-600°C in a nitrogen atmosphere, then heating the mixture to 700-900°C for annealing, and post-treating the mixture to obtain a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst;

[0011] The mass percentage of the metal salt in the biomass raw material is 0.8-3.0 wt.%; the metal in the metal salt is a transition metal;

[0012] The biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises carbon nanotubes and metals supported on the walls of the carbon nanotubes; the average diameter of the carbon nanotubes is 8-50 nm.

[0013] Traditional planar carbon supports loaded with atomically dispersed catalysts have a highly symmetrical in-plane ordered structure, and the electronic interaction between the support and the metal active sites is strong, which inhibits the reactivity between the catalytic active sites and pollutant molecules, resulting in low catalytic activity. The present invention uses biomass and transition metals with rich d-orbital electronic structures as carbon sources and metal precursors, which can effectively introduce different mesoscopic and microstructures, form flexible and adjustable curvature structures and atomic states, and thus promote the accessibility and reactivity of active sites. Specifically:

[0014] In the present invention, the carbon nanotubes are given a specific curvature structure by controlling their average diameter. Compared to a planar graphite structure, the carbon nanotube structure can improve the mass transfer efficiency of each molecule during the catalytic process, reduce the accumulation of carbon-containing species and sulfur-containing species on the surface, and enable the catalyst to maintain excellent catalytic activity and cyclic stability. Furthermore, the catalyst can be repeatedly regenerated and reused through a simple annealing treatment. It is very important to control the average diameter of the carbon nanotubes within a specific range. When the average diameter of the carbon nanotubes is small, the molecular diffusion rate is too high and the catalytic activity is low. When the average diameter of the carbon nanotubes is large, ineffective collisions between molecules increase, and the catalytic activity remains low.

[0015] Furthermore, atomically dispersed metals are anchored on the walls of carbon nanotubes, and their curvature effect is utilized to form an asymmetric metal-carbon coordination structure. The curved metal sites are charged, which enhances electron utilization and effectively improves O3 activation ability, thereby significantly improving catalytic activity.

[0016] Furthermore, the mass percentage of metal salts and biomass raw materials will also greatly affect the catalytic performance of the catalyst for S-VOCs. It is difficult to achieve excellent catalytic oxidation effects when the mass percentage is low or high.

[0017] Furthermore, the present invention first performs an initial pre-pyrolysis at a relatively low temperature. Because the types and concentrations of oxygen-containing groups (-OH, -COOH, -O) on the surfaces of different biomasses vary, these oxygen-containing groups can complex with transition metal atoms to varying degrees during the initial pre-pyrolysis process, forming complex intermediates that prevent metal atom aggregation. When the pre-pyrolysis temperature is too low, effective complexation of metal atoms is difficult, resulting in a low loading and low atomic utilization. When the pre-pyrolysis temperature is too high, the oxygen-containing groups are destroyed, causing metal ions to aggregate and become encapsulated in carbon nanotubes, affecting the exposure of their active sites.

[0018] After the complex intermediate is pre-pyrolyzed, it is annealed to promote the complete carbonization of the biomass, and to induce it to undergo thermal polymerization and radial self-assembly at high temperature to form a nanotube curvature structure with a specific average diameter. At the same time, the oxygen-containing groups of the complex metal atoms are volatilized, so that the metal atoms are fully exposed on the surface of the carbon nanotubes. The degree of polymerization can be effectively controlled by the selection of specific biomass, thereby forming biomass-derived curvature carbon nanotubes of different diameters and anchored atomic dispersed metal catalysts.

[0019] Preferably, the biomass raw material is selected from one or more of coconut shell, tea oil shell, orange peel or grapefruit peel. Further preferably, the biomass raw material is selected from tea oil shell. The inventors need to further clarify that the type of biomass raw material also has a significant impact on the catalytic activity of the catalyst finally prepared. By selecting a specific biomass raw material, the surface curvature of the carbon nanotubes can be optimized, and the one-dimensional radial constraint structure of carbon nanotubes with different curvatures can regulate the mass transfer and diffusion behavior of gaseous pollutant molecules, effectively avoiding catalyst carbon deposition and sulfur poisoning, thereby maintaining the high activity and high stability of the catalyst.

[0020] Preferably, the average diameter of the carbon nanotubes is 15-50 nm. Further preferably, the average diameter of the carbon nanotubes is 15-25 nm. Most preferably, the average diameter of the carbon nanotubes is 20 nm. Specifically, the average diameter of the carbon nanotubes can be 10 nm, 15 nm, 20 nm, 15 nm, 30 nm, 35 nm, 40 nm, 50 nm, etc., or an interval range formed by any of the above values, such as 15-40 nm, 15-25 nm, etc., but the present invention is not limited thereto. The test method for the average diameter of the carbon nanotubes is: the average diameter of the carbon nanotubes is counted in a scanning electron microscope image and the arithmetic mean is taken.

[0021] Preferably, the metal salt accounts for 0.8-2.0 wt.% of the biomass raw material. Further preferably, the metal salt accounts for 1.0-1.5 wt.% of the biomass raw material. More preferably, the metal salt accounts for 1.0-1.2 wt.% of the biomass raw material. Most preferably, the metal salt accounts for 1.0 wt.% of the biomass raw material. Specifically, the mass percentage of metal salt in the biomass raw material can be 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, 2.0 wt.%, 2.1 wt.%, 2.2 wt.%, 2.3 wt.%, 2.4 wt.%, 2.5 wt.%, 2.6 wt.%, 2.7 wt.%, 2.8 wt.%, 2.9 wt.%, etc., or an interval range formed by any of the above numerical values, but the present invention is not limited thereto.

[0022] Preferably, the metal salt is selected from one or more of copper salts, manganese salts, iron salts, and cobalt salts. Further preferably, the metal salt is selected from copper salts.

[0023] Preferably, at least one selected from the following (a) to (d):

[0024] (a) the copper salt is selected from one or more of Cu(NO3)2·3H2O, CuCl2·4H2O, CuSO4·5H2O, and Cu(CH3COO)2·H2O;

[0025] (b) the manganese salt is selected from one or more of Mn(NO3)2·4H2O, MnCl2·4H2O, MnSO4, and Mn(CH3COO)2·H2O;

[0026] (c) the iron salt is selected from one or more of Fe(NO3)3·9H2O, FeCl3, FeSO4, and Fe(CH3COO)2·4H2O;

[0027] (d) The cobalt salt is selected from one or more of Co(NO3)2·6H2O, CoCl2·6H2O, CoSO4, and (CH3COO)2Co·4H2O.

[0028] Preferably, the pre-pyrolysis time is 1-4 h; and / or the annealing time is 1-4 h.

[0029] More preferably, the pre-pyrolysis time is 2-3 h; most preferably, the pre-pyrolysis time is 2 h.

[0030] More preferably, the annealing time is 2-3 h; most preferably, the annealing time is 3 h.

[0031] Preferably, the pre-pyrolysis is carried out at 480-520°C under a nitrogen atmosphere; most preferably, the pre-pyrolysis is carried out at 500°C under a nitrogen atmosphere.

[0032] Preferably, the temperature is raised to 750-850°C for annealing; more preferably, the temperature is raised to 780-820°C for annealing; most preferably, the temperature is raised to 800°C for annealing.

[0033] Preferably, in the pre-pyrolysis step and the annealing step, the heating rate is 3-8 ° C min -1 ; and / or nitrogen flow rate of 20-60 mL min -1 .

[0034] Preferably, the post-treatment comprises the following steps: dispersing the annealed product into an alkaline solution for mixing, removing excess metal salts, washing, and drying.

[0035] Preferably, the mixing time is 6-18 h. Preferably, the mixture is washed with deionized water until the pH is about 7.0.

[0036] Furthermore, the present invention seeks to protect the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst prepared by the above preparation method.

[0037] Furthermore, the present invention claims the use of biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalysts in the ozone-catalytic oxidation of sulfur-containing volatile organic pollutants.

[0038] The catalyst provided by the present invention not only has excellent pollutant removal efficiency during ozone catalytic oxidation to remove S-VOCs, but also effectively avoids carbon accumulation and sulfur poisoning on the catalyst surface, achieving efficient S-VOC removal while maintaining excellent stability. Furthermore, the unique surface curvature effect maximizes the utilization of metal atoms and significantly enhances ozone utilization efficiency. The ozone concentration in the tail gas is significantly lower than the national standard, with minimal secondary pollution to the environment. This new environmentally friendly material offers the unique advantages of low cost, ease of preparation, and environmental friendliness.

[0039] Furthermore, the present invention claims protection for a method for ozone-catalyzed oxidation of sulfur-containing volatile organic pollutants, wherein the sulfur-containing volatile organic pollutants are catalytically oxidized using the above-mentioned biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst in the presence of ozone.

[0040] Preferably, the sulfur-containing volatile organic pollutants are selected from one or more of methyl mercaptan (CH3SH), ethyl mercaptan (CH3CH2SH), hydrogen sulfide (H2S), dimethyl sulfide (CH3SCH3), and carbon disulfide (CS2).

[0041] Preferably, the concentration of ozone in the catalytic oxidation reaction system is 10-40 ppm. Preferably, the concentration of sulfur-containing volatile organic pollutants is 30-100 ppm.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The catalyst provided by the present invention can achieve efficient utilization of ozone molecules, show excellent removal efficiency for S-VOCs, and has extremely low secondary pollution, making it more environmentally friendly.

[0044] (2) The radially constrained structure of the carbon nanotubes in the catalyst provided by the present invention can improve the mass transfer efficiency of molecules, enhance the accessibility of active sites, and promote the rapid transfer of sulfur-containing intermediates, thereby avoiding catalyst deactivation due to the accumulation of sulfur-containing species, thereby maintaining excellent cyclic stability.

[0045] (3) The catalyst provided by the present invention is prepared from widely available biomass raw materials, has a simple preparation method, and exhibits good structural stability. Furthermore, the curvature effect of the carbon nanotubes anchors the metal atoms in an atomically dispersed state, maximizing the utilization of the metal atoms and significantly reducing the amount of metal precursor added, thereby lowering the catalyst preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The scanning electron microscope images of the catalysts prepared in Comparative Example 1 and Example 1 are shown. Figure 1(a) is a scanning electron microscope image of the catalyst prepared in Comparative Example 1; Figure 1 (b) is a scanning electron microscope image of the catalyst prepared in Example 1.

[0047] Figure 2 This is a scanning electron microscope image of the catalyst prepared in Comparative Example 4.

[0048] Figure 3 The X-ray diffraction patterns of the catalysts prepared in Comparative Example 1 and Example 1 are shown.

[0049] Figure 4 The Raman spectra of the catalysts prepared in Comparative Example 1 and Example 1 are shown.

[0050] Figure 5 This is the structural model of the catalyst prepared in Comparative Example 1 and Example 1. Figure 5 (a) is the structural model of the catalyst prepared in Comparative Example 1; Figure 5 (b) is the structural model of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0051] The present invention is further described below with reference to the specification and specific examples, which are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0052] Example 11.0% Preparation of Cu-BCNT-M Catalyst

[0053] (1) Wash and dry the camellia husks, sieve them to 400 mesh, dry them in a vacuum oven for 12 h to remove moisture, and then store them in a drying container for later use.

[0054] (2) Then, 0.03 g of Cu(NO3)2·3H2O and 3.0 g of camellia oleifera shell powder were weighed and mixed evenly. The mixture was then transferred to a tube furnace and pre-pyrolyzed at 500 °C for 2 h under nitrogen atmosphere (heating rate: 5 °C min -1 , N2 flow rate: 30 mL min -1 ), and then heated to 800 ℃ for annealing for 3 h (heating rate: 5 ℃ min -1 , N2 flow rate: 20 mL min -1 ), to obtain a black product.

[0055] (3) Collect the obtained black product and add 3.0 mol L -1The mixture was stirred in a NaOH solution for 12 h to remove excess metal salts, and then washed repeatedly with deionized water until the pH was about 7.0. The mixture was dried in a vacuum oven overnight to obtain the final catalyst sample, named 1.0% Cu-BCNT-M, in which the average diameter of the carbon nanotubes was 20 nm.

[0056] Example 2 Preparation of 2.0% Cu-BCNT-M Catalyst

[0057] The difference between this embodiment and embodiment 1 is that in step (2), 0.06 g Cu(NO3)2·3H2O was weighed.

[0058] Example 3 Preparation of 3.0% Cu-BCNT-M Catalyst

[0059] The difference between this embodiment and embodiment 1 is that in step (2), 0.09 g Cu(NO3)2·3H2O was weighed.

[0060] Example 4 Preparation of 1.0% Cu-BCNT-M Catalyst

[0061] The difference between this embodiment and embodiment 1 is that in step (2), the temperature is raised to 800°C for annealing for 1 h, and the average diameter of the carbon nanotubes is 30 nm.

[0062] Example 5 Preparation of 1.0% Cu-BCNT-M Catalyst

[0063] The difference between this embodiment and embodiment 1 is that in step (2), the temperature is raised to 800°C for annealing for 4 h, and the average diameter of the carbon nanotubes is 8 nm.

[0064] Example 6 Preparation of 1.0% Mn-BCNT-M Catalyst

[0065] The difference between this embodiment and embodiment 1 is that Cu(NO3)2·3H2O is replaced by an equal amount of Mn(NO3)2·4H2O.

[0066] Example 7 Preparation of 1.0% Fe-BCNT-M Catalyst

[0067] The difference between this embodiment and embodiment 1 is that Cu(NO3)2·3H2O is replaced by an equal amount of Fe(NO3)3·9H2O.

[0068] Example 8 Preparation of 1.0% Co-BCNT-M Catalyst

[0069] The difference between this embodiment and embodiment 1 is that Cu(NO3)2·3H2O is replaced by an equal amount of Co(NO3)2·6H2O.

[0070] Example 9 Preparation of 1.0% Cu-BCNT-H Catalyst

[0071] The difference between this embodiment and embodiment 1 is that in step (1), the camellia shell is replaced with coconut shell.

[0072] Example 10 Preparation of 1.0% Cu-BCNT-L Catalyst

[0073] The difference between this embodiment and embodiment 1 is that in step (1), the oil-tea camellia shell is replaced with orange peel.

[0074] Example 1 Preparation of 11.0% Cu-BCNT-UL Catalyst

[0075] The difference between this embodiment and embodiment 1 is that in step (1), the oil-tea camellia shell is replaced with pomelo peel.

[0076] Comparative Example 1 Preparation of BCNT-M Catalyst

[0077] The difference between this comparative example and Example 1 is that no metal salt precursor is added, and the average diameter of the obtained camellia oleifera shell-derived carbon nanotubes is 20 nm.

[0078] Comparative Example 21.0% Preparation of Cu-BCNT-M Catalyst

[0079] The difference between this comparative example and Example 1 is that in step (2), the temperature is raised to 800°C for annealing for 0.5 h, and the average diameter of the carbon nanotubes is 150 nm.

[0080] Comparative Example 31.0% Preparation of Cu-BCNT-M Catalyst

[0081] The difference between this comparative example and Example 1 is that in step (2), the temperature is raised to 800°C for annealing for 6 h, and the average diameter of the carbon nanotubes is 4 nm.

[0082] Comparative Example 4 Preparation of 1.0% Cu-CNT Catalyst

[0083] 1.5 g melamine, 1.5 g g-C3N4 and 0.03 g Cu(NO3)2·3H2O were weighed and ground evenly, then transferred to a tube furnace and annealed at 500 °C for 2 h under nitrogen atmosphere (heating rate: 5 °C min -1 , N2 flow rate: 30 mL min -1 ), then heated to 800 °C and annealed for 3 h (heating rate: 5 °C min -1 , N2 flow rate: 20 mL min -1 The black product was collected and concentrated to 3.0 mol L -1The mixture was stirred in a NaOH solution for 12 h to remove excess metal salts, and then washed repeatedly with deionized water until the pH was about 7.0. The mixture was dried in a vacuum oven overnight to obtain the final catalyst sample, named 1.0% Cu-CNT. The average diameter of the carbon nanotubes was 200 nm.

[0084] Comparative Example 5 Commercial MnO2 catalyst (99.0%)

[0085] Commercial MnO2 catalyst was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0086] Comparative Example 6 Preparation of 0.1% Cu-BCNT-M Catalyst

[0087] The difference between this comparative example and Example 1 is that in step (2), 0.003 g of Cu(NO3)2·3H2O was weighed.

[0088] Comparative Example 7 Preparation of 0.5% Cu-BCNT-M Catalyst

[0089] The difference between this comparative example and Example 1 is that in step (2), 0.015 g of Cu(NO3)2·3H2O was weighed.

[0090] Test Example 1

[0091] Experimental materials: catalysts prepared in various examples and comparative examples.

[0092] (1) Pollutant removal efficiency: 30.0 mg of the prepared catalysts were weighed and placed in a continuous flow reactor. Oxygen was ionized by an ozone generator to produce high-purity ozone. The initial concentration of ozone entering the reactor (C O3 ) was controlled at 20.0 ppm and the flow rate was 10 ml min -1 Dilute CH3SH with high-purity nitrogen to 50.0 ppm, and use a mass flow meter to control the total mass flow rate of the raw gas to 100 ml min -1 , corresponding to a space velocity of 200,000 mg h -1 g -1 At the same time, sensors are used to detect the initial concentration of CH3SH at the reactor inlet (C0) and the real-time concentration of CH3SH at the outlet (C t ).

[0093] The catalytic activity was measured by the removal rate of methyl mercaptan (η = 1-C t / C0) were evaluated, and the results are shown in Table 1 below.

[0094] (2) Cyclic stability: 30.0 mg of the catalyst was placed in a continuous flow reactor and subjected to a cyclic test for 5 cycles using the pollutant removal efficiency test method described in (1).

[0095] The test results are expressed as the removal efficiency of methyl mercaptan, and the results are shown in Table 2 below.

[0096] (3) Ozone utilization efficiency: The test process is based on the above (1) pollutant removal efficiency test process, and at the end of the reaction, the ozone concentration at the reactor outlet is measured (C t- o3).

[0097] Ozone utilization efficiency is expressed as the ozone decomposition rate (η O3 = 1- C t- o3 / C O3 ), and the results are shown in Table 3 below.

[0098] (4) Average catalyst diameter: The prepared catalyst was placed under a scanning electron microscope (SEM) at an appropriate magnification to obtain the catalyst morphology. ImageJ software was then used to count the diameters of the carbon nanotubes in the SEM image. After a sufficient number of carbon nanotubes were counted, the arithmetic mean was calculated and used as the average catalyst diameter.

[0099] Table 1 Comparison of CH3SH removal efficiency

[0100]

[0101] As can be seen from Table 1, the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst provided by the present invention has an excellent removal effect on CH3SH, with a CH3SH removal rate of ≥84.7%; further preferably, the CH3SH removal rate is ≥90.8%; most preferably, the CH3SH removal rate is 99.6%.

[0102] It can be seen from Examples 1, 2, 3, Comparative Examples 6 and 7 that the ratio of metal to biomass raw material in the catalyst has a great influence on the removal rate of CH3SH. When the mass percentage of metal salt in the biomass raw material is within a specific range, an excellent CH3SH removal rate is achieved.

[0103] It can be seen from Example 1, Example 4, Example 5, Comparative Example 2 and Comparative Example 3 that the average diameter of the carbon nanotubes in the catalyst has a great influence on the removal rate of CH3SH. When the average diameter of the carbon nanotubes in the catalyst is within a specific range, it has an excellent CH3SH removal rate.

[0104] It can be seen from Examples 1, 9, 10 and 11 that when the biomass raw material is camellia oleifera shell, it has a better CH3SH removal rate than other biomass raw materials.

[0105] It can be seen from Example 1, Comparative Example 4 and Comparative Example 5 that, compared with existing catalysts, the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst provided by the present invention has a better removal effect on CH3SH.

[0106] Table 2 Cyclic stability test results

[0107]

[0108] As shown in Table 2, the biomass-derived curved carbon nanotube-anchored atomically dispersed metal catalyst provided by the present invention exhibits excellent cyclic stability. After five reuses, the CH₃SH removal rate decreased by ≤2.7%. In contrast, the CH₃SH removal rate of the catalyst prepared in the comparative example decreased significantly after five reuses, by ≥4.7%.

[0109] Table 3 Comparison of ozone utilization efficiency

[0110]

[0111] As can be seen from Table 3 above, the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst provided by the present invention has excellent ozone utilization efficiency.

[0112] Test Example 2

[0113] Figure 1 The scanning electron microscope images of BCNT-M (Comparative Example 1) and 1.0% Cu-BCNT-M (Example 1) are shown in FIG. Figure 1 It can be seen that the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst obtained in Example 1 is a uniform nanotube structure with an average diameter of about 20 nm. Moreover, after anchoring Cu atoms, its morphology does not change significantly, indicating that the curvature structure of the carbon nanotube remains unchanged.

[0114] Figure 2 The scanning electron microscope image of 1.0% Cu-CNT (Comparative Example 4). Figure 2 As can be seen, the diameter of the 1.0% Cu-CNT is approximately 200 nm. The larger diameter of conventional carbon nanotubes makes it difficult to effectively regulate the mass transfer and diffusion behavior of gaseous molecules, resulting in poor catalytic activity. This effectively demonstrates the importance of selecting specific biomass for producing carbon nanotubes with the appropriate curvature effect. Therefore, the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst described in this invention can achieve efficient O₃ utilization and promote effective mass transfer of gaseous molecules.

[0115] Figure 3 The X-ray diffraction patterns of BCNT-M (Comparative Example 1) and 1.0% Cu-BCNT-M (Example 1) are shown. The characteristic peak at 23.2° is attributed to the (002) arrangement of graphitic carbon. However, after anchoring Cu atoms, the diffraction peak shifts to smaller angles, indicating that the coordination of Cu with the graphitic carbon atoms on the tube wall only affects the local microenvironment of the curved surface. Furthermore, no Cu diffraction peak is observed after anchoring Cu atoms, indicating that Cu is atomically dispersed and does not disrupt the microstructure of the biomass-derived carbon nanotubes.

[0116] Figure 4 Figure 1 is the Raman spectra of BCNT-M (Comparative Example 1) and 1.0% Cu-BCNT-M (Example 1). Figure 4 It can be seen that the -1 and 1580 cm -1 The vibration peaks at are respectively attributed to the D band of disordered vibration in the form of defects in the graphite structure and the sp 2 The G band formed by the hybrid carbon bonding. D / I G Ratio (I D / I G = 1.30) indicates that more carbon defects are introduced after the biomass-derived carbon nanotubes anchor Cu atoms. These defects may be due to the Cu atoms occupying some C atomic sites to form a Cu-C coordination structure, thereby effectively enhancing the bonding strength between Cu and carbon nanotubes.

[0117] Figure 5 The structural models of BCNT-M (Comparative Example 1) and 1.0% Cu-BCNT-M (Example 1). Figure 5 It can be seen that the C atoms of the graphite structure are arranged to form a nanotube structure. The curvature effect can effectively anchor Cu atoms and present an atomically dispersed state, thereby significantly improving the utilization efficiency of Cu atoms. In the catalytic ozonation process, the medium-curvature biomass-derived carbon nanotubes can also effectively enhance the mass transfer efficiency between oxidant molecules (O3) and pollutant molecules (CH3SH), increase the molecular accessibility of active sites, and achieve efficient and stable removal of sulfur-containing volatile organic pollutants.

[0118] The foregoing examples are merely illustrative, serving to illustrate some of the features of the method of the present invention. The appended claims are intended to claim the widest possible scope that can be envisioned, and the embodiments presented herein are demonstrated by the applicant's actual experimental results. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include subranges therein, and variations in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. Application of a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst in the ozone catalytic oxidation of sulfur-containing volatile organic pollutants, characterized in that: The preparation method of a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises the following steps: mixing a biomass raw material and a metal salt, pre-pyrolyzing the mixture at 450-600°C in a nitrogen atmosphere, then heating the mixture to 700-900°C for annealing, and post-treating the mixture to obtain a biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst; The mass percentage of the metal salt in the biomass raw material is 0.8-2.0 wt.%; The biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises carbon nanotubes and a metal supported on the walls of the carbon nanotubes; the average diameter of the carbon nanotubes is 15-25 nm; The biomass raw material is camellia oleifera shell; The metal salt is selected from copper salts.

2. The application according to claim 1, characterized in that The pre-pyrolysis time is 1-4 h; and / or the annealing time is 1-4 h.

3. The application according to claim 1, characterized in that The sulfur-containing volatile organic pollutants are selected from one or more of methyl mercaptan, ethyl mercaptan, hydrogen sulfide, dimethyl sulfide, and carbon disulfide.

4. The application according to claim 1, characterized in that The copper salt is selected from one or more of Cu(NO3)2·3H2O, CuCl2·4H2O, CuSO4·5H2O, and Cu(CH3COO)2·H2O.

5. A method for catalytic oxidation of sulfur-containing volatile organic pollutants using ozone, characterized in that: In the presence of ozone, biomass-derived curvature carbon nanotubes anchored atomically dispersed metal catalysts were used to catalytically oxidize sulfur-containing volatile organic pollutants. The preparation method of the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises the following steps: mixing a biomass raw material and a metal salt, pre-pyrolyzing the mixture at 450-600°C in a nitrogen atmosphere, then heating the mixture to 700-900°C for annealing, and post-treating the mixture to obtain the biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst; The mass percentage of the metal salt in the biomass raw material is 0.8-2.0 wt.%; The biomass-derived curvature carbon nanotube-anchored atomically dispersed metal catalyst comprises carbon nanotubes and a metal supported on the walls of the carbon nanotubes; the average diameter of the carbon nanotubes is 15-25 nm; The biomass raw material is camellia oleifera shell; The metal salt is selected from copper salts.

6. The method according to claim 5, characterized in that The concentration of ozone in the catalytic oxidation reaction system is 10-40 ppm.

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