Biochar-doped aluminum-cobalt spinel catalyst as well as preparation method and application thereof
By doping biochar into aluminum-cobalt spinel catalysts, the problems of low activity and high cost of traditional catalysts have been solved, enabling efficient degradation of volatile organic compounds and resource utilization of agricultural and forestry waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional aluminum-cobalt spinel catalysts have low active site density, making it difficult for reactant molecules to be effectively adsorbed and activated. They also have low electron mobility and complex and costly synthesis processes.
A solvothermal method was used to dope biochar into the lattice of aluminum cobalt spinel. By controlling the biochar content, a lattice-carbon-controlled aluminum cobalt spinel catalyst was prepared. Agricultural and forestry waste was used as raw materials, which simplified the synthesis process and improved the catalytic performance.
This improved the exposure of active sites and electron migration rate of the catalyst, lowered the reaction energy barrier, enabled efficient degradation of volatile organic compounds, and facilitated the reuse of agricultural and forestry waste, while reducing preparation costs.
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Figure CN121732170A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a biochar-doped aluminum cobalt spinel catalyst, its preparation method, and its application. Background Technology
[0002] Volatile organic compounds (VOCs) are important precursors to urban haze and photochemical smog, with complex emission sources covering multiple fields such as industrial production, vehicle exhaust, and solvent evaporation. With accelerated industrialization, VOC emissions continue to grow, posing a serious threat to the ecological environment and human health. Among VOC treatment technologies, catalytic oxidation has become a widely adopted industrial treatment technology due to its advantages such as high purification efficiency, wide applicability, energy saving, and environmental protection. Developing efficient and low-cost catalytic materials is a key focus of this research.
[0003] Cobalt aluminum spinel catalysts (CoAl2O4) exhibit excellent catalytic performance in catalytic reactions due to their unique crystal structure and tunable electronic properties. However, traditional spinel materials have low active site density, making it difficult for reactant molecules to be effectively adsorbed and activated, and their low electron mobility in catalytic reactions limits their catalytic efficiency. In addition, existing spinel material synthesis processes are complex and costly. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a biochar-doped aluminum-cobalt spinel catalyst, its preparation method, and its application. This invention uses agricultural and forestry waste and aluminum-cobalt metal salts as raw materials, and employs a solvothermal method to prepare a lattice-carbon-controlled aluminum-cobalt spinel catalyst by adjusting the biochar content, thereby achieving efficient VOCs degradation and the reuse of agricultural and forestry waste.
[0005] The first objective of this invention is to provide a biochar-doped aluminum cobalt spinel catalyst, wherein the biochar-doped aluminum cobalt spinel catalyst is formed by doping biochar in the crystal lattice of aluminum cobalt spinel as a matrix.
[0006] The biochar-doped aluminum-cobalt spinel catalyst is made of soluble Al 3+ Source, soluble Co 2+ It is obtained by using raw materials such as agricultural and forestry waste, obtaining precursors through solvothermal reaction, and then calcining them.
[0007] The soluble Al 3+ Source, soluble Co 2+ The ratio of the amount of the source material to the agricultural and forestry waste powder is 0.01 mol: 0.01 mol: 0.5 g to 2 g.
[0008] For the above-mentioned biochar-doped aluminum-cobalt spinel catalyst, while maintaining soluble Al3+ Sources and soluble Co 2+ Under the premise that the molar amount of the source is 0.01 mol, if the amount of agricultural and forestry waste powder is too low, that is, less than the limit of 0.5 g here, the degradation effect of volatile organic compounds will be poor. If the amount of agricultural and forestry waste powder is too high, that is, greater than the limit of 2 g here, the obtained biochar doped aluminum cobalt spinel catalyst will be unstable and its quality will be greatly reduced after high temperature degradation.
[0009] A second objective of this invention is to provide a method for preparing the above-described biochar-doped aluminum-cobalt spinel catalyst, comprising the following steps: Soluble Al 3+ Source, soluble Co 2+ The precursor is obtained by reacting raw materials and agricultural and forestry waste powders in a solvent through a solvothermal reaction. The precursor is calcined, and the agricultural and forestry waste powder is converted into biochar, which is then doped into the lattice of aluminum cobalt spinel to obtain a biochar-doped aluminum cobalt spinel catalyst.
[0010] In the above preparation process, after a solvothermal reaction, soluble Al 3+ Sources and soluble Co 2+ A precursor is obtained by loading agricultural and forestry waste powder onto the precursor. After calcination, the agricultural and forestry waste powder is converted into biochar, which is then doped into the crystal lattice of aluminum cobalt spinel to obtain a biochar-doped aluminum cobalt spinel catalyst. As an environmentally friendly renewable resource, agricultural and forestry waste is an excellent precursor for constructing carbon materials due to its diverse microstructures, well-developed pore structure, low cost, and ease of modification.
[0011] This invention employs a simple solvothermal method to composite biochar derived from agricultural and forestry waste with an aluminum-cobalt spinel precursor. Biochar atoms are introduced into the spinel lattice, optimizing the spinel structure, promoting crystal formation, inducing lattice distortion and electron rearrangement, and thus enhancing catalytic performance. This overcomes the activity and stability bottlenecks of traditional catalysts, providing a new approach for the design of efficient, low-cost catalytic materials. Furthermore, this invention utilizes a simple solvothermal method to construct a low-cost, high-performance lattice-carbon-regulated aluminum-cobalt spinel catalyst. This method is not only simple to operate, uses inexpensive and readily available raw materials, has a high yield, and is energy-efficient and environmentally friendly, but also achieves the resource utilization of agricultural and forestry waste, synergistically promoting pollution reduction and carbon reduction.
[0012] In a preferred embodiment, the temperature of the solvothermal reaction is 100℃~250℃ and the time is 2h~8h.
[0013] In a preferred embodiment, the calcination specifically involves heating to 400℃ to 600℃ at a rate of 1℃ / min to 10℃ / min and calcining for 2h to 6h.
[0014] In a preferred embodiment, the solvent is a mixture of isopropanol and acetic acid, with a volume ratio of isopropanol to acetic acid of 2 / 3 to 6:1. This invention uses isopropanol as a solvent, providing a suitable medium environment for the reaction, ensuring that the reactants can be fully dissolved and uniformly dispersed, thereby promoting the reaction. Simultaneously, isopropanol also possesses certain reducing properties and can participate in the reaction in a reducing atmosphere, assisting in the reduction of metal precursors to metals or metal oxides; acetic acid, as a weak acid, can provide an acidic environment in solvothermal synthesis, contributing to the efficient conduct of the solvothermal reaction.
[0015] As a preferred embodiment, the soluble Al 3+ The source is selected from aluminum nitrate, aluminum acetate, or aluminum chloride; the soluble Co 2+ The source is selected from cobalt nitrate, cobalt acetate or cobalt chloride.
[0016] In a preferred embodiment, the agricultural and forestry waste is crop straw or forestry residue; the method for preparing the agricultural and forestry waste powder is as follows: the agricultural and forestry waste is washed, dried, crushed, and passed through a 40-100 mesh sieve.
[0017] The third objective of this invention is to provide an application of the above-described biochar-doped aluminum cobalt spinel catalyst in the degradation of volatile organic compounds. Specifically, the application method involves: in a mixed atmosphere of oxygen and nitrogen, at 250°C to 400°C, controlling the mass hourly space velocity (HSV) at 30000 mL / (g⁻¹). cat ·h)~120000mL / (g cat •h) is a process that uses volatile organic compounds as raw materials and degrades them under the action of a biochar-doped aluminum cobalt spinel catalyst.
[0018] In a preferred embodiment, the amount of the biochar-doped aluminum cobalt spinel catalyst is 5 mg to 150 mg, based on a concentration of 1000 ppm of volatile organic compounds.
[0019] In a preferred embodiment, the volume ratio of oxygen to nitrogen in the mixed atmosphere is 1:4.
[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a biochar-doped aluminum-cobalt spinel catalyst. Using aluminum-cobalt spinel as a matrix, biochar is doped into the crystal lattice of the aluminum-cobalt spinel to obtain the biochar-doped aluminum-cobalt spinel catalyst. This invention incorporates biochar into the crystal structure of aluminum-cobalt spinel to form lattice carbon, inducing lattice distortion and electron rearrangement in the aluminum-cobalt spinel, thereby resulting in highly catalytically active Co. 3+The increased biochar content led to the reorganization of valence bonds and optimization of the electronic structure of the catalyst, thereby lowering the reaction energy barrier. Simultaneously, as a highly conductive atom, carbon atoms act as electron transfer channels in the crystal lattice, increasing the electron migration rate and thus improving the degradation efficiency of VOCs molecules. This invention effectively modulates the crystal structure of aluminum-cobalt spinel by adjusting the doping amount of biochar, thereby achieving better catalytic degradation performance.
[0021] This invention utilizes biochar made from agricultural and forestry waste, achieving not only efficient VOCs degradation and the reuse of these wastes, but also providing new ideas for the design of efficient, low-cost catalytic materials. This application synthesizes a low-cost, high-performance, and highly stable biochar-doped aluminum-cobalt spinel catalyst using a simple solvothermal method with straightforward operation steps and readily available, inexpensive raw materials. The preparation method of this invention is simple, yields high efficiency, and is energy-saving and environmentally friendly, contributing to the synergistic effect of pollution reduction and carbon reduction. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 The images show the X-ray diffraction patterns of the biochar-doped aluminum cobalt spinel catalysts prepared in Examples 1 to 3 of this invention and the aluminum cobalt spinel catalyst prepared in Comparative Example 1. (a) is the X-ray diffraction pattern of the catalysts obtained in Examples 1 to 3 and Comparative Example 1, and (b) is an enlarged view of the diffraction peak near 37°.
[0024] Figure 2 The images shown are scanning electron microscope (SEM) images of the catalysts prepared in Example 1 and Comparative Example 1 of this invention. In the images, a1 and a2 are morphological scans of Comparative Example 1, c is an elemental surface scan of Comparative Example 1, and e is a line scan of Comparative Example 1; b1 and b2 are morphological scans of Example 1, d is an elemental surface scan of Example 1, and f and g are line scans of Example 1.
[0025] Figure 3 The images show the X-ray photoelectron spectroscopy (XPS) spectra of the catalysts prepared in Examples 1 to 3 of this invention, where (a) is the C 1s XPS spectrum and (b) is the Co 2p XPS spectrum.
[0026] Figure 4 The figures show the catalytic performance of the catalysts prepared in Examples 1 to 3 and Comparative Example 1 of this invention.
[0027] Figure 5 The diagram shows the catalytic performance of the catalysts prepared in Examples 1, 4 and 5 of this invention.
[0028] Figure 6 The heating and cooling cycle test and stability test of the biochar-doped aluminum cobalt spinel catalyst prepared in Example 1 of the present invention are shown in (a) and (b). Detailed Implementation
[0029] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.
[0030] To address the problems of existing spinel catalysts: First, traditional spinel materials have low active site density, making it difficult for reactant molecules to be effectively adsorbed and activated, resulting in low electron mobility in the catalytic reaction and limited catalytic efficiency; second, existing spinel material synthesis processes are complex and costly. Based on these technical problems, this invention provides a biochar-doped aluminum-cobalt spinel catalyst, its preparation method, and its applications.
[0031] The technical concept of the present invention will be described below.
[0032] This invention provides a biochar-doped aluminum cobalt spinel catalyst, which uses aluminum cobalt spinel as a matrix and incorporates biochar into the crystal lattice of aluminum cobalt spinel to form a biochar-doped aluminum cobalt spinel catalyst.
[0033] The biochar-doped aluminum-cobalt spinel catalyst is made of soluble Al 3+ Source, soluble Co 2+ It is obtained by using raw materials such as agricultural and forestry waste, obtaining precursors through solvothermal reaction, and then calcining them.
[0034] The soluble Al 3+ Source, soluble Co 2+ The ratio of the amount of the source material to the agricultural and forestry waste powder is 0.01 mol: 0.01 mol: 0.5 g to 2 g.
[0035] In the above technical solution, biochar is doped into the lattice of aluminum-cobalt spinel. The introduction of biochar increases the exposure of active sites in the aluminum-cobalt spinel catalyst and introduces new active centers, reducing electron migration resistance. Furthermore, introducing biochar into the spinel lattice optimizes the valence bond rearrangement and electronic structure of the catalyst, modulates the catalyst's band structure, and thus lowers the reaction energy barrier. This invention uses biochar to form lattice carbon within the spinel structure, which not only induces lattice distortion and electron rearrangement but also enhances the high-activity Co... 3+ The carbon atom, being an atom with good electrical conductivity, acts as a channel for electron transfer in the crystal lattice, increasing the electron migration rate and thus facilitating the efficient degradation of VOCs.
[0036] The technical effects of the present invention will be described below through specific embodiments and comparative examples.
[0037] Example 1 A method for preparing a biochar-doped aluminum-cobalt spinel catalyst includes the following steps: S1. Cut the paulownia branches into small pieces of wood 3cm to 5cm in length, wash them with pure water, dry them, and then pulverize them into 40-60 mesh paulownia branch powder using a pulverizer as a source of biochar.
[0038] S2: 2g of paulownia branch powder from S1, 4.43g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 3.44g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were mixed and placed in a polytetrafluoroethylene (PTFE) liner. Then, 40mL of 99.7wt% isopropanol was added, and the mixture was stirred at 500r / min for 10min on a magnetic stirrer. Next, 20mL of 99.5wt% acetic acid was added, and the mixture was stirred at 500r / min for another 30min. After uniform mixing, the PTFE liner was transferred to a stainless steel autoclave and placed in a preheated oven at 200℃ for 4h for a solvothermal reaction. After naturally cooling to room temperature, the mixture was removed, washed alternately with water and ethanol, and then dried in a vacuum oven at 60℃ to obtain the precursor. The resulting product was weighed and sealed for storage. In this step, isopropanol and acetic acid, as a mixed solvent, can fully dissolve aluminum cobalt metal salts and participate in the solvothermal reaction.
[0039] S3, in a muffle furnace, the precursor of S2 was heated to 400℃ for 4h at a heating rate of 10℃ / min and then cooled to room temperature to obtain a biochar-doped aluminum cobalt spinel catalyst, denoted as AlCo-C2.
[0040] The biochar-doped aluminum-cobalt spinel catalyst prepared in Example 1 was weighed and sealed for storage. This step involves converting agricultural and forestry waste powder into biochar through high-temperature calcination, and then doping it into the crystal lattice of aluminum-cobalt spinel to obtain the biochar-doped aluminum-cobalt spinel catalyst.
[0041] In this invention, the biochar-doped aluminum cobalt spinel catalyst exhibits the best performance and catalytic effect when the biochar content is 20 wt%.
[0042] Example 2 A method for preparing a biochar-doped aluminum-cobalt spinel catalyst includes the following steps: S1. Cut the paulownia branches into small pieces of wood 3cm to 5cm in length, wash them with pure water, dry them, and then pulverize them into 40-60 mesh paulownia branch powder using a pulverizer as a source of biochar.
[0043] S2: 0.5g of paulownia branch powder from S1, 4.43g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 3.44g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were mixed and placed in a polytetrafluoroethylene (PTFE) liner. Then, 40mL of 99.7wt% isopropanol was added, and the mixture was stirred at 500r / min for 10min on a magnetic stirrer. Next, 20mL of 99.5wt% acetic acid was added, and the mixture was stirred at 500r / min for another 30min. After uniform mixing, the PTFE liner was transferred to a stainless steel autoclave and placed in a preheated oven at 200℃ for 4h for a solvothermal reaction. After naturally cooling to room temperature, the mixture was removed, washed alternately with water and ethanol, and then dried in a vacuum oven at 60℃ to obtain the precursor. The resulting product was weighed and sealed for storage. In this step, isopropanol and acetic acid, as a mixed solvent, can fully dissolve aluminum cobalt metal salts and participate in the solvothermal reaction.
[0044] S3, the precursor of S2 was calcined in a muffle furnace at a heating rate of 10℃ / min to 400℃ for 4h, and then cooled to room temperature with the furnace to obtain a biochar-doped aluminum cobalt spinel catalyst, denoted as AlCo-C. 0.5 .
[0045] Example 3 A method for preparing a biochar-regulated aluminum-cobalt spinel catalyst includes the following steps: S1. Cut the paulownia branches into small pieces of wood 3cm to 5cm in length, wash them with pure water, dry them, and then pulverize them into 40-60 mesh paulownia branch powder using a pulverizer as a source of biochar.
[0046] S2: 1g of paulownia branch powder from S1, 4.43g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 3.44g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were mixed and placed in a polytetrafluoroethylene (PTFE) liner. Then, 40mL of 99.7wt% isopropanol was added, and the mixture was stirred at 500r / min for 10min on a magnetic stirrer. Next, 20mL of 99.5wt% acetic acid was added, and the mixture was stirred at 500r / min for another 30min. After uniform mixing, the PTFE liner was transferred to a stainless steel autoclave and placed in a preheated oven at 200℃ for 4h for a solvothermal reaction. After naturally cooling to room temperature, the mixture was removed, washed alternately with water and ethanol, and then dried in a vacuum oven at 60℃ to obtain the precursor. The resulting product was weighed and sealed for storage. In this step, isopropanol and acetic acid, as a mixed solvent, can fully dissolve aluminum cobalt metal salts and participate in the solvothermal reaction.
[0047] S3, in a muffle furnace, the precursor of S2 was heated to 400℃ for 4h at a heating rate of 10℃ / min and then cooled to room temperature to obtain a biochar-doped aluminum cobalt spinel catalyst, denoted as AlCo-C1.
[0048] Example 4 A method for preparing a biochar-doped aluminum-cobalt spinel catalyst includes the following steps: S1. Cut the paulownia branches into small pieces of wood 3cm to 5cm in length, wash them with pure water, dry them, and then pulverize them into 40-60 mesh paulownia branch powder using a pulverizer as a source of biochar.
[0049] S2: 2g of paulownia branch powder from S1, 4.43g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 3.44g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were mixed and placed in a polytetrafluoroethylene (PTFE) liner. Then, 40mL of 99.7wt% isopropanol was added, and the mixture was stirred at 500r / min for 10min on a magnetic stirrer. Next, 20mL of 99.5wt% acetic acid was added, and the mixture was stirred at 500r / min for another 30min. After uniform mixing, the PTFE liner was transferred to a stainless steel autoclave and placed in a preheated oven at 200℃ for 4h for a solvothermal reaction. After naturally cooling to room temperature, the mixture was removed, washed alternately with water and ethanol, and then dried in a vacuum oven at 60℃ to obtain the precursor. The resulting product was weighed and sealed for storage. In this step, isopropanol and acetic acid, as a mixed solvent, can fully dissolve aluminum cobalt metal salts and participate in the solvothermal reaction.
[0050] S3, in a muffle furnace, the precursor of S2 was heated to 400℃ for 4h at a heating rate of 1℃ / min, and then cooled to room temperature with the furnace to obtain a biochar-doped aluminum cobalt spinel catalyst.
[0051] Example 5 A method for preparing a biochar-doped aluminum-cobalt spinel catalyst includes the following steps: S1. Cut the paulownia branches into small pieces of wood 3cm to 5cm in length, wash them with pure water, dry them, and then pulverize them into 40-60 mesh paulownia branch powder using a pulverizer as a source of biochar.
[0052] S2: 2g of paulownia branch powder from S1, 4.43g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 3.44g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were mixed and placed in a polytetrafluoroethylene (PTFE) liner. Then, 40mL of 99.7wt% isopropanol was added, and the mixture was stirred at 500r / min for 10min on a magnetic stirrer. Next, 20mL of 99.5wt% acetic acid was added, and the mixture was stirred at 500r / min for another 30min. After uniform mixing, the PTFE liner was transferred to a stainless steel autoclave and placed in a preheated oven at 200℃ for 4h for a solvothermal reaction. After naturally cooling to room temperature, the mixture was removed, washed alternately with water and ethanol, and then dried in a vacuum oven at 60℃ to obtain the precursor. The resulting product was weighed and sealed for storage. In this step, isopropanol and acetic acid, as a mixed solvent, can fully dissolve aluminum cobalt metal salts and participate in the solvothermal reaction.
[0053] S3, in a muffle furnace, the precursor of S2 was heated to 400℃ for 4h at a heating rate of 5℃ / min, and then cooled to room temperature with the furnace to obtain a biochar-doped aluminum cobalt spinel catalyst.
[0054] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows.
[0055] Comparative Example 1 A method for preparing a latticeless carbon-regulated aluminum-cobalt spinel catalyst specifically includes the following steps: S1, mix 4.43g Al(NO3)3·9H2O and 3.44g Co(NO3)2·6H2O, then add 40mL isopropanol and stir at 500r / min for 10min on a magnetic stirrer; then add 20mL acetic acid and continue stirring at 500r / min for 30min. After mixing, place in an oven preheated to 200℃ for 4h, then remove after cooling to room temperature. Wash alternately with water and ethanol, then dry in a vacuum oven at 60℃. Weigh the product and seal for storage.
[0056] S2, take the product obtained in step 1 and calcine it in a muffle furnace. The calcine temperature is set to 400℃, the heating rate is 10℃ / min, and the holding time is 4h to obtain the aluminum cobalt spinel catalyst, denoted as AlCo. After weighing, seal and store it.
[0057] To illustrate the catalytic effect of the biochar-doped aluminum cobalt spinel catalyst prepared in this invention, application examples are also provided, as follows.
[0058] Application Example 1 The application of a biochar-doped aluminum-cobalt spinel catalyst in the catalytic degradation of volatile organic compounds, the application comprising the following steps: Using toluene as the reactant gas, 50 mg of the aluminum-cobalt spinel catalyst prepared in Example 1 was placed in a quartz tube reactor with an inner diameter of 6 mm and a length of 400 mm. The experimental conditions were set as follows: 1000 ppm toluene + 20% O2 (N2 balance gas), total flow rate of 50 mL / min, and mass hourly space velocity (WHSV) of 60000 mL / (g) cat ·h).
[0059] The catalytic performance was tested by measuring the exhaust gas composition at a heating rate of 10℃ / min, from 250℃ to 400℃ at 10℃ increments for 24 min. The catalytic activity of the catalyst was expressed as the conversion rate of toluene.
[0060] The temperature cycling test involved raising the temperature from 250℃ to 350℃ at intervals of 10℃ / min, and then lowering it back to 250℃ at intervals of 10℃ / min. This process was repeated three times. The composition of the exhaust gas was determined by an online gas chromatograph using a Techcomp GC-7980. The catalytic activity of the catalyst was expressed as the conversion rate of toluene.
[0061] The stability test was conducted continuously at 320℃ for 54 hours. The composition of the exhaust gas was determined by Tianmei Techcomp GC-7980 online gas chromatograph. The catalytic activity of the catalyst was expressed as the conversion rate of toluene.
[0062] The morphology and performance of the biochar-doped aluminum cobalt spinel catalysts prepared in Examples 1 to 5 and the lattice-free carbon-controlled aluminum cobalt spinel catalyst prepared in Comparative Example 1 were characterized, and the results are as follows.
[0063] Figure 1The images show X-ray powder diffraction (XRD) patterns of the biochar-doped aluminum-cobalt spinel catalysts prepared in Examples 1-3 of this invention and the latticeless carbon-controlled aluminum-cobalt spinel catalyst of Comparative Example 1. (a) is the XRD pattern, and (b) is a magnified view of the diffraction peak near 37°. Figure 1 As shown in (a), the biochar-doped aluminum cobalt spinel catalyst prepared in the example and the latticeless carbon-controlled aluminum cobalt spinel catalyst in the comparative example all showed obvious diffraction peaks at 19.1°, 31.5°, 37.0°, 45.0°, 59.4°, and 65.3°, which can be attributed to the (111), (220), (311), (400), (511), and (440) crystal planes of CoAl2O4 (PDF#38-0814). This indicates that the introduction of biochar did not change the crystal structure of aluminum cobalt spinel, and the characteristic diffraction peaks attributed to CoAl2O4 gradually increased with the increase of biochar content. Figure 1 As can be seen in (b), with the introduction of biochar, the diffraction angles corresponding to the characteristic diffraction peaks belonging to the (311) crystal plane gradually shift to lower angles, indicating that the biochar has successfully entered the lattice of AlCo-C spinel and along the AlCo-C plane... 0.5 The content of AlCo-C1 and AlCo-C2 sequential lattice carbon gradually increases.
[0064] Figure 2 The images show scanning electron microscope (SEM) images of the catalysts prepared in Example 1 and Comparative Example 1 of this invention. As can be seen from the images, the AlCo spinel sample has a spherical structure formed by stacked nanowires (a1, a2). As shown in (c), Al and Co atoms are uniformly distributed in the catalyst. When biochar derived from waste biomass was introduced, the biochar also exhibited a uniform distribution on the catalyst surface, without any stacking phenomenon (d). Simultaneously, its morphology changed; while maintaining the overall spherical structure, the original nanowire structure transformed into a layered lamellar structure (b1, b2). The layered lamellar structure created more irregularly arranged voids and channels on the catalyst surface, facilitating the exposure of more reactive sites in the AlCo-C2 sample of Example 1, providing more space for the adsorption and reaction of VOCs gas molecules, thus improving the catalytic performance. Furthermore, comparative analysis with the line scan image of the AlCo sample (e) revealed that the biochar was not simply attached to the catalyst surface, but successfully entered the spinel lattice structure of the AlCo-C2 sample of Example 1 (f). This lattice-embedded structure makes the bond between biochar and spinel tighter and more stable, which is beneficial for controlling the catalyst structure and improving electron mobility, thereby enhancing the overall performance of biochar-doped aluminum cobalt spinel catalysts.
[0065] Figure 3The images show the X-ray photoelectron spectroscopy (XPS) spectra of the biochar-doped aluminum-cobalt spinel catalysts obtained in Examples 1 to 3 of this invention, where (a) is the C 1s XPS spectrum and (b) is the Co 2p XPS spectrum. Figure 3 As shown in (a), the C 1s XPS spectra of all samples can be fitted with three peaks at 284.8 eV, 286.1 eV, and 289.0 eV, which are assigned to OC=O, CO-Co, and CC, respectively. The presence of CO-Co bonds confirms the presence of lattice carbon, which is consistent with the XRD results, and the CO-Co bond content increases from AlCo-C in Example 2. 0.5 The percentage of carbon in the lattice increased from 22.2% to 30.4% in AlCo-C2 of Example 1, further confirming the gradual increase in the amount of carbon in the lattice. Figure 3 (b) shows the Co 2p XPS spectra of the biochar-doped aluminum cobalt spinel catalysts prepared in Examples 1 to 3. The binding energies of 780.9 eV and 796.1 eV correspond to the Co 2p of the Co species. 3 / 2 and Co 2p 1 / 2 The spin-orbit splitting peaks, with satellite peaks around 803.5 eV and 787.1 eV, correspond to the Co 2p peaks in all samples. 1 / 2 and Co 2p 3 / 2 The XPS spectra can be fitted to two peaks, with binding energies at 795.7 eV, 797.4 eV and 780.4 eV, 781.61 eV, respectively, corresponding to Co 2+ and Co 3+ Species. In the catalysts obtained in Examples 1 to 3, Co 3+ The ratio is from Example 2 AlCo-C 0.5 The concentration of AlCo-C2 in Example 1 increased from 0.56 to 0.70, indicating that the introduction of biochar can effectively promote the highly active octahedral coordination of Co. 3+ The formation of this substance helps to improve the catalytic performance of the catalyst.
[0066] Figure 4 The figures show the catalytic performance of the catalysts obtained in Examples 1-3 and Comparative Example 1. As can be seen from the figures, within the temperature range of 250℃ to 400℃, the biochar-doped AlCo spinel catalysts of Examples 1-3 all exhibited better catalytic performance than the undoped biochar AlCo spinel catalyst of Comparative Example 1. Furthermore, the catalytic degradation efficiency of toluene significantly improved with increasing biochar content. Specifically, the temperature at which the toluene conversion rate reached 50% (T0) was the highest. 50 ) and the temperature at which the conversion rate reaches 90% (T 90 The temperatures of AlCo catalysts were reduced from 342℃ and 385℃ to AlCo-C, respectively. 0.5The catalyst's temperatures were 319℃ and 347℃, then further reduced to 303℃ and 315℃ for the AlCo-C2 catalyst. This demonstrates that biochar doping optimized the toluene degradation performance of the aluminum-cobalt spinel catalyst, and that increasing the biochar content effectively improved catalytic efficiency. Figure 5 The graphs show the catalytic performance of the biochar-doped aluminum cobalt spinel catalysts prepared in Examples 1, 4, and 5. As can be seen from the graphs, the change in calcination heating rate has almost no effect on the catalytic performance.
[0067] Figure 6 The above are the heating and cooling cycle tests and stability tests of the biochar-doped aluminum cobalt spinel catalyst obtained in Example 1. (a) is the heating and cooling cycle test diagram of the biochar-doped aluminum cobalt spinel catalyst, and (b) is the stability test diagram of the biochar-doped aluminum cobalt spinel catalyst. Figure 6 (a) shows that the prepared AlCo-C2 spinel catalyst exhibits excellent heating and cooling cycle performance, and the change of reaction temperature does not affect the structure and performance of the catalyst. Figure 6 (b) The stability test at 320℃ shows that even after 54 hours of continuous high-temperature use, the AlCo-C2 spinel catalyst's toluene degradation efficiency only decreased from 95% to 93%, maintaining a high toluene conversion rate. This clearly demonstrates the excellent thermal stability of the prepared lattice-carbon-regulated aluminum-cobalt spinel catalyst. Therefore, it can be seen that the biochar-doped spinel catalyst prepared by a simple solvothermal method not only enables the reuse of agricultural and forestry waste but also effectively improves the efficiency of VOCs catalytic degradation, contributing to synergistic effects of pollution reduction and carbon reduction.
[0068] This invention uses agricultural and forestry waste and aluminum-cobalt precursors as raw materials to prepare biochar-doped aluminum-cobalt spinel catalysts via a simple solvothermal method. The biochar-doped spinel catalyst was prepared by adding agricultural and forestry waste, and the optimal biochar doping amount was screened. The catalyst prepared by this method not only achieves efficient VOCs degradation but also utilizes agricultural and forestry waste as a resource. Its preparation process is environmentally friendly and pollution-free, providing a new approach to the resource utilization of agricultural and forestry waste.
[0069] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.
[0070] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.
Claims
1. A biochar-doped aluminum-cobalt spinel catalyst, characterized in that, The biochar-doped aluminum cobalt spinel catalyst is formed by doping aluminum cobalt spinel into the crystal lattice of aluminum cobalt spinel as aluminum cobalt spinel. The biochar-doped aluminum-cobalt spinel catalyst is made of soluble Al 3+ Source, soluble Co 2+ The precursor is obtained by using raw materials such as waste from agriculture and forestry through a solvothermal reaction, followed by calcination. The soluble Al 3+ Source, soluble Co 2+ The ratio of the amount of the source material to the agricultural and forestry waste powder is 0.01 mol: 0.01 mol: 0.5 g to 2 g.
2. A method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 1, characterized in that, Includes the following steps: Soluble Al 3+ Source, soluble Co 2+ The precursor is obtained by reacting raw materials and agricultural and forestry waste powder in a solvent through a solvothermal reaction. The precursor is calcined, and the agricultural and forestry waste powder is converted into biochar, which is then doped into the lattice of aluminum cobalt spinel to obtain a biochar-doped aluminum cobalt spinel catalyst.
3. The method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 2, characterized in that, The temperature of the solvothermal reaction is 100℃~250℃, and the time is 2h~8h.
4. The method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 2, characterized in that, The calcination process specifically involves heating the temperature to 400℃ to 600℃ at a rate of 1℃ / min to 10℃ / min and calcining for 2 hours to 6 hours.
5. The method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 2, characterized in that, The solvent is a mixture of isopropanol and acetic acid, and the volume ratio of isopropanol to acetic acid is 2 / 3 to 6:
1.
6. The method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 2, characterized in that, The soluble Al 3+ The source is selected from aluminum nitrate, aluminum acetate, or aluminum chloride; the soluble Co 2+ The source is selected from cobalt nitrate, cobalt acetate or cobalt chloride.
7. The method for preparing the biochar-doped aluminum-cobalt spinel catalyst according to claim 2, characterized in that, The agricultural and forestry waste is crop straw or forestry residue; the preparation method of the agricultural and forestry waste powder is as follows: the agricultural and forestry waste is washed, dried, crushed, and passed through a 40-100 mesh sieve.
8. The application of the biochar-doped aluminum-cobalt spinel catalyst according to claim 1 in the degradation of volatile organic compounds, characterized in that, The specific application method is as follows: In a mixed atmosphere of oxygen and nitrogen, at 250℃~400℃, control the mass hourly space velocity (HSV) at 30000 mL / (g). cat ·h)~120000mL / (g cat •h) is a process that uses volatile organic compounds as raw materials and degrades them under the action of a biochar-doped aluminum cobalt spinel catalyst.
9. The application of the biochar-doped aluminum-cobalt spinel catalyst according to claim 8 in the degradation of volatile organic compounds, characterized in that, The amount of the biochar-doped aluminum cobalt spinel catalyst is 5 mg to 150 mg, based on a concentration of 1000 ppm of volatile organic compounds.
10. The application of the biochar-doped aluminum-cobalt spinel catalyst according to claim 8 in the degradation of volatile organic compounds, characterized in that, In the mixed atmosphere, the volume ratio of oxygen to nitrogen is 1:4.