Fe-cu-mn ternary hydrotalcite-like catalyst and preparation method thereof

Abstract

The application relates to the field of wastewater treatment catalysis, and discloses a Fe-Cu-Mn ternary hydrotalcite-like catalyst and a preparation method thereof, which comprises iron, copper and manganese; the iron, copper and manganese are distributed in the layer plate metal central site in an atomic dispersion mode; the layer plate oxygen octahedron is in a non-symmetrical stretching distortion state; a 3.2-4.8 degree deviation is generated in the manganese oxygen copper bond angle in the layer plate; the lattice parameter a of the layer plate 110 crystal face direction is 0.305-0.312 nm; the molar ratio of copper to manganese is 1:2-1:5; and the molar sum of copper and manganese to the molar ratio of iron is 2:1-4:1. According to the application, the lattice non-symmetrical distortion induces the space overlap of the auxiliary metal and the iron active center orbit, an electron transfer path is constructed, the shielding effect of the hydroxyl ion on the iron active site under the alkaline environment is eliminated, the catalytic site activity is maintained, and stable and efficient catalytic treatment under wide pH working conditions is realized.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment catalysis technology, and particularly relates to a Fe-Cu-Mn ternary hydrotalcite catalyst and its preparation method. Background Technology

[0002] Currently, heterogeneous Fenton reactions are widely used in the field of industrial wastewater treatment. These reactions induce hydrogen peroxide to generate highly oxidizing hydroxyl radicals through solid catalysts, effectively degrading organic pollutants and reducing chemical sludge production. Hydrotalcite-like materials, with their unique layered structure and tunable metal composition, demonstrate significant application value as catalytic centers for such reactions. However, in practical engineering applications, drastic fluctuations in the pH of raw water place demands on the stability of the catalytic system. The efficient reaction range of traditional iron-based catalytic materials is usually limited to a narrow acidic environment. As the alkalinity of the system increases, the active sites on the catalyst surface are prone to physicochemical transformation, leading to a rapid decline in catalytic efficiency. To maintain continuous process operation, large amounts of acid and alkali reagents are usually added in the upstream process to adjust the pH of the wastewater. This operation mode not only incurs high reagent costs but also causes an accumulation of total dissolved solids in the effluent, representing a hidden cost that the industry has long accepted in order to maintain process operation.

[0003] Industry attempts to broaden the catalytic response window by increasing metal loading or introducing organic complexing agents often lead to the leaching of metal ions and shorten the material's lifespan. Furthermore, the introduction of complexing agents faces the risk of self-degradation under oxidative conditions, resulting in secondary pollution. Besides limitations at the chemical composition level, existing technologies often rely on overall phase stability when exploring multi-metal systems, neglecting the profound influence of the lattice microenvironment on electron transfer. For example, Chinese invention patent CN101302031A discloses a magnesium-aluminum rare earth ternary hydrotalcite, its preparation method, and its uses. It utilizes rare earth elements to improve crystallinity and morphological regularity. However, when addressing the problem of alkaline passivation in the Fenton reaction, the traditional highly symmetrical lattice structure cannot provide the necessary electronic pathways for the active centers, making it difficult to release the polarization binding of hydroxide ions at the atomic scale. Single-active-center systems face a fundamental constraint between electron migration rate and structural stability. Existing technologies struggle to maintain high-density active-center circulation and long-term lattice structure stability over a wide pH range.

[0004] Therefore, the technical problem to be solved by this invention is how to provide a Fe-Cu-Mn ternary hydrotalcite catalyst that solves the problems of narrow pH range, blocked electron circulation and poor structural stability of existing heterogeneous catalytic systems. Summary of the Invention

[0005] This invention provides a Fe-Cu-Mn ternary hydrotalcite catalyst, comprising:

[0006] The catalyst is a ternary layered double hydroxide with a distorted lamellar structure, consisting of iron, copper and manganese elements, which are distributed in an atomically dispersed state at the metal central sites of the layered double hydroxide lamellar structure.

[0007] The oxygen octahedrons in the laminate structure exhibit an asymmetric stretched distortion state, causing the manganese-oxygen-copper bond angles within the laminate to shift by 3.2° to 4.8° relative to the ideal hexagonal symmetric lattice.

[0008] The molar ratio of metal elements in the catalyst satisfies the following conditions: the molar ratio of copper to manganese is 1:2 to 1:5, and the molar ratio of the sum of the molar amounts of copper and manganese to that of iron is 2:1 to 4:1.

[0009] Lattice parameters of the catalyst in the 110 crystal plane direction of the layer The interlayer spacing is 0.305 nm to 0.312 nm, and in the 003 crystal plane direction. The wavelength ranges from 0.75nm to 0.79nm.

[0010] Copper and manganese in the layer Tracks and iron The orbitals construct an electron transfer path through spatial overlap. Under pH conditions of 7.0 to 10.0, the electron transfer path achieves electron cloud shift through the internal stress field generated by the asymmetric stretching distortion state, thereby releasing the polarization binding of hydroxide ions on the iron active site and maintaining the catalytic activity of the iron active site surface.

[0011] The catalyst has a specific surface area of ​​85 m² / g to 135 m² / g, and by controlling the supersaturation of the nucleation environment, the persistent internal stress generated by iron, copper and manganese elements during the crystal lattice formation process locks the shift of the manganese-oxygen-copper bond angle.

[0012] Preferably, the general chemical formula of the catalyst is: ;in, , and Let be the mole fraction of the metallic element, satisfying , , ,and ; The mole fraction of carbonate ions satisfies ; The value represents the water of crystallization, ranging from 0.5 to 2.0. The catalyst maintains electroneutrality by compensating for the charge of the layer structure through carbonate ions within the interlayer gaps.

[0013] Preferably, the catalyst has a microstructure of stacked hexagonal plates with a lateral particle size of 150 nm to 400 nm and a thickness of 15 nm to 35 nm. The hexagonal plates form an open-layered structure with step defects at the edges through heterogeneous nucleation of ternary metals during the co-precipitation process.

[0014] Preferably, the crystal structure characteristics of the catalyst are defined by the intensity of X-ray diffraction peaks, and the ratio of the diffraction peak intensity of the 003 crystal plane to that of the 006 crystal plane is 1.8 to 2.5; the intensity ratio characterizes the highly ordered arrangement of iron, copper and manganese elements in the laminate structure.

[0015] Preferably, the hydroxyl coverage density on the catalyst surface is 8.5 μmol / m² to 12.0 μmol / m²; and in a reaction system with a pH of 7.0 to 10.0, the adsorption energy of hydrogen peroxide molecules by the iron active center of the catalyst is 0.35 eV to 0.55 eV.

[0016] Preferably, the degree of lattice distortion of the catalyst is measured by the ratio of interatomic spacing. Measurement, interatomic spacing ratio Satisfy the following formula: ,in, The distortion factor characterizes the degree of lattice stretching in laminates; This represents the average interatomic distance between manganese and copper atoms in the laminate structure. The average interatomic distance between iron atoms in a laminated structure; interatomic distance ratio. It meets the range of 1.05 to 1.12.

[0017] Preferably, the catalyst has magnetic recovery characteristics, with a saturation magnetization of 1.2 emu / g to 3.5 emu / g; the magnetic characteristics originate from the ferromagnetic arrangement generated by the superexchange interaction between iron and manganese elements within the layers.

[0018] Preferably, the layer structure contains metal central site vacancies, and the number of metal central site vacancies accounts for 1.5% to 3.0% of the total number of metal central sites; the metal central site vacancies induce the activation of oxygen molecules on the catalyst surface by adjusting the local electronic state density of the layer.

[0019] Preferably, the catalyst exhibits erosion resistance and, after continuous operation for 100 hours in a reaction system with a pH of 7.0 to 10.0, the mass dissolution rate of metal ions is less than 0.5 mg / L, and the offset of the manganese-oxygen-copper bond angle remains constant. The catalyst is prepared by reacting a mixed metal salt solution containing iron, copper, and manganese salts with an alkaline solution in a precipitation environment with a pH of 9.5 to 10.5. In-situ encapsulation of enduring internal stress is achieved by controlling the mechanical shear rate during the precipitation process.

[0020] A method for preparing a Fe-Cu-Mn ternary hydrotalcite catalyst includes the following steps:

[0021] Step 111: Dissolve iron salt, copper salt and manganese salt in water to obtain a mixed metal salt solution, wherein the molar ratio of copper to manganese is 1:2 to 1:5, and the molar ratio of the sum of the molar amounts of copper and manganese to that of iron is 2:1 to 4:1.

[0022] Step 112: The mixed metal salt solution and the alkaline solution are added dropwise to the reactor in parallel to carry out a co-precipitation reaction. During the reaction, the pH of the reaction system is maintained at 9.5 to 10.5 by adjusting the dropping rate of the mixed metal salt solution and the alkaline solution, while the shear rate of the reaction system is controlled at 2800 rpm to 4000 rpm, so as to generate persistent internal stress by adjusting the supersaturation of the nucleation environment during the formation of the lamination lattice.

[0023] Step 113, the product after the co-precipitation reaction is heated at 60°C. Up to 80 The catalyst is obtained by aging at a certain temperature for 12 to 24 hours, followed by filtration, washing and drying.

[0024] Compared with existing technologies, the present invention provides a Fe-Cu-Mn ternary hydrotalcite catalyst and its preparation method, which have the following advantages:

[0025] 1. In Fe-Cu-Mn ternary hydrotalcite catalysts, a multi-active-center system with high electronic interaction is constructed through the atomic-level coordination of three metal elements (iron, copper, and manganese) in the hydrotalcite-like lattice. This spatial synergistic distribution of the ternary components enables electrons to migrate rapidly between metal ions of different valence states, breaking the constraint of the electron gain and loss rate of a single metal center on the overall reaction process. During the reaction, copper and manganese elements act as auxiliary centers, inducing electrons to flow to the iron active sites and promoting the cyclic generation of active species. This results in an overall improvement in catalytic reaction efficiency and optimization of reagent consumption.

[0026] 2. By utilizing the layered structure of hydrotalcite-like materials and the regulatory capabilities of their surface functional groups, a self-regulating microenvironment response layer is formed on the catalyst surface. Through local intervention in the interfacial charge state and hydrogen ion distribution, the catalytic decomposition reaction of hydrogen peroxide can be successfully triggered under complex conditions that are close to neutral or even weakly alkaline. This solves the dependence of traditional processes on strongly acidic conditions, avoids process fluctuations caused by frequent adjustments to the pH of the reaction system, and enhances the engineering adaptability of the technical solution to raw water with different properties.

[0027] 3. During the co-precipitation nucleation process, ternary metal ions achieve mutual support and structural complementarity, enhancing the chemical stability and anti-leakage ability of the layered framework. The coexistence of multiple metal elements not only increases the density of active sites, but also reduces the dissolution tendency of components in strong oxidizing environments through the optimization of lattice energy. The establishment of this solid-phase surface reaction mode locks the active components in the catalyst body, ensuring long-term and stable catalytic efficiency, while also simplifying the subsequent solid-liquid separation and disposal process, reflecting the high degree of unity between material structure and function. Attached Figure Description

[0028] Figure 1 This is a flowchart of the heterogeneous Fenton reaction catalytic mechanism with a wide pH range in response to the distorted laminate structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the asymmetric stretched and distorted Fe-Cu-Mn ternary hydrotalcite layer crystal structure of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0031] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, low, lateral, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated.

[0032] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication between two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0033] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The present invention will be described in detail below through specific embodiments; it should be understood that the following embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0035] A Fe-Cu-Mn ternary hydrotalcite-like catalyst and its preparation method are disclosed. The catalyst is a metal hydroxide composition with an asymmetric distorted lamellar structure. Iron, copper, and manganese are used as active components, and these metal elements are atomically dispersed at the metal central sites of the hydrotalcite-like lamellar structure. The oxygen octahedrons in the lamellar structure are in an asymmetric stretched distorted state, causing the manganese-oxygen-copper bond angles within the lamellar structure to change relative to an ideal hexagonal symmetric lattice. to The offset; in In a weakly alkaline reaction system with a pH of 7.0 to 10.0, the internal stress field generated by this asymmetric stretching distortion induces a directional shift in the electron cloud, which is mediated by copper and manganese. Tracks and iron The spatial overlap between orbitals constructs electron transfer pathways, neutralizing the polarization binding of hydroxide ions on iron active sites to maintain the catalytic activity of the iron active site surface; in heterogeneous phases... In the reaction, the efficient reaction range of conventional iron-based catalysts is usually limited to a narrow acidic environment. As the alkalinity of the system increases, the active sites on the catalyst surface are easily deactivated by the shielding effect of hydroxide ions. To address this technical challenge, this invention creates persistent internal stress within the catalyst layers by adjusting the metal component ratio and the supersaturation during lattice formation to lock the shift of the manganese-copper bond angle. The molar ratio of metal elements in the catalyst satisfies the following conditions: the molar ratio of copper to manganese is 1:2 to 1:5, and the sum of the molar amounts of copper and manganese relative to the molar ratio of iron is 2:1 to 4:1. This specific ratio constructs electron tunnels within the lattice that guide the active iron centers, ensuring high efficiency under alkaline conditions. cycle.

[0036] Lattice parameters of the catalyst in the 110 crystal plane direction of the layer The interlayer spacing is 0.305 nm to 0.312 nm along the 003 crystal plane. The interatomic spacing ranges from 0.75 nm to 0.79 nm; to quantify the stretching of the layer lattice, the interatomic spacing ratio is used. As a distortion factor, this ratio satisfies the following formula: ,in, The distortion factor characterizes the degree of lattice stretching in laminates; This represents the average interatomic distance between manganese and copper atoms in the laminate structure. The average interatomic distance between iron atoms in a laminated structure; interatomic distance ratio. The numerical range is limited to between 1.05 and 1.12; this metastable distorted lattice effectively reduces the energy barrier in the free radical generation process, enabling the catalyst to... It maintains comparable catalytic performance to that under acidic conditions even in a strongly alkaline environment with a pH of 10.0; the general chemical formula of the catalyst is represented as follows: ;in, , and Let be the mole fraction of the metallic element, satisfying , , ,and ; The mole fraction of carbonate ions satisfies ; The crystal water content ranges from 0.5 to 2.0. The catalyst interlayer gaps are maintained electrically neutral by compensating for charge with carbonate ions. In addition, the interlayer structure contains metal central site vacancies, which account for 1.5% to 3.0% of the total number of metal central sites. These vacancies are used to adjust the local electronic state density of the interlayer and induce dissolved oxygen to be activated on the catalyst surface.

[0037] In a laminated structure Bond corner generation to Offset, using synchrotron radiation X-ray absorption fine structure spectrum combined Full spectrum fitting refinement procedure calibration, through the calibration of the full spectrum fitting refinement procedure ... Edge and Edge expansion Fourier transform of X-ray absorption fine structure data to extract the average interatomic spacing of the first coordination shell. and Substitute into the distortion factor formula ,in The distance between manganese and copper atoms in the layered structure is the average interatomic distance, in units of... , The average interatomic distance between iron atoms in the layered structure is given by . , To characterize the lattice stretching distortion factor of the laminate, according to The bond angle offset is determined numerically; the vacancy concentration at the metal center site is determined by... The peak area integrals of each metal orbital in X-ray photoelectron spectroscopy were calculated using normalized atomic percentages, and low-temperature electron paramagnetic resonance spectroscopy was used to further analyze the results. The steps involve capturing symmetry breaking to generate a paramagnetic signal and performing vacancy type verification. The initial acidity of the mixed metal salt solution was determined by adding a concentration of [missing information]. of Adjust the solution to for to The difference in the instantaneous dissolution rate of metal ions caused by a strong acid environment generates the total number of metal central sites. to Empty seat.

[0038] The arrangement of metal elements in the catalyst within the layered structure is determined by... The peak intensity ratio of the 003 crystal plane to the 006 crystal plane in the X-ray diffraction pattern was used to confirm this. The setting is based on characterizing the uniformity of interlayer electron density distribution. When the ternary metals iron, copper, and manganese achieve atomic-level high dispersion and do not produce independent phase states, the intensity ratio is... The concentration was stabilized between 1.8 and 2.5. In the preparation procedure, the instantaneous supersaturation of metal ions was maintained within the range of 1.2 to 1.5 by controlling the co-current droplet loading rate in step 112. This was used to drive the alternating arrangement of heterogeneous metal atoms at nucleation sites, thereby suppressing the agglomeration tendency of the same metal element in the early stages of lattice growth. The catalyst preparation procedure is as follows: Step 111, iron salt, copper salt, and manganese salt are dissolved in water to prepare a mixed metal salt solution, controlling the molar ratio of copper to manganese between 1:2 and 1:5, and the sum of the molar amounts of copper and manganese relative to the molar ratio of iron between 2:1 and 4:1; Step 112, the mixed metal salt solution and the alkaline solution are added co-currently to the reactor for a co-precipitation reaction, with the reaction temperature set at 25°C. Up to 40 Between; the system is maintained by adjusting the dropping rate. The supersaturation was controlled at 9.5 to 10.5, while the shear rate of the stirring system was controlled at 2800 rpm to 4000 rpm. Under this high-intensity mechanical shear environment, the supersaturation in the early stage of nucleation fluctuated instantaneously, thereby generating and encapsulating persistent internal stress in the crystal lattice. In step 113, the co-precipitated product was subjected to a process at 60°C. Up to 80 Aging for 12 to 24 hours under controlled conditions; at the end of aging, a controlled rapid cooling treatment is performed, with the cooling rate controlled to be no less than 10°C. / min, until the temperature drops to 35 The following; this rapid cooling process locked down and Collaborative generation - The distorted pinned state causes a geometric shift in the manganese-oxygen-copper bond angle; the resulting product is filtered, washed until neutral, and dried to obtain the finished catalyst.

[0039] In industrial scale-up production processes, steps The mechanical shear rate involves the impeller linear velocity of a high-shear mixing device. Control, calculation formula is ,in The impeller linear velocity, in units of , The impeller diameter is expressed in units of 1000 mm. , Rotational speed, unit: The linear velocity is set at to The interval is used to maintain the instantaneous supersaturation pulse in the early stage of nucleation, and the steps are as follows. The controlled rapid cooling process involves pumping the aged slurry into a plate heat exchanger and introducing a temperature of [temperature value missing]. to The cooling water process ensures that the overall cooling rate of the slurry is maintained by adjusting the cooling water flow rate. to Within the range, until the material temperature drops to The following describes the asymmetric stretching distortion state; the catalyst's microstructure is a stacked hexagonal lamellar crystal with a lateral particle size of 150 nm to 400 nm and a thickness of 15 nm to 35 nm; through the interaction of ternary metals in the heterogeneous nucleation process, an open lamellar structure with step defects at the edges is formed; the catalyst's... X-ray diffraction characteristics show that the intensity ratio of the diffraction peaks of the 003 crystal plane to that of the 006 crystal plane is 1.8 to 2.5, which characterizes the highly ordered arrangement of metal elements in the layers; the hydroxyl group coverage density on the catalyst surface is 8.5. Up to 12.0 ;exist In reaction systems with a concentration of 7.0 to 10.0, the adsorption energy of hydrogen peroxide molecules by the iron active centers is between 0.35 eV and 0.55 eV, ensuring efficient activation of reactant molecules. To achieve magnetic recovery of the catalyst, iron and manganese elements form a ferromagnetic arrangement through superexchange within the layers, resulting in a saturation magnetization of 1.2 emu / g to 3.5 emu / g. This catalyst exhibits erosion resistance. After running continuously for 100 hours in a high-load reaction system of 7.0 to 10.0, the mass dissolution rate of metal ions remained below 0.5 mg / L, and the offset of the manganese-oxygen-copper bond angle did not decrease. This distorted structure, which is solidified by controlled thermal stress, enhances the chemical bonding force of the catalyst and effectively inhibits the hydrolysis and shedding of active components under complex water quality conditions.

[0040] Example 1: Wastewater system in landfill leachate treatment operation With a value of 9.0, hydroxide ions in the water undergo strong polarization coordination with the active sites of conventional iron-based catalysts, leading to an increase in electron cloud density around the iron active centers and generating an electrostatic shielding effect, thus enhancing the traditional heterogeneous... The reaction stalls due to the locking of active sites. To address the aforementioned alkaline passivation phenomenon, a layered structure with asymmetric distortion is employed. - - Ternary hydrotalcite catalyst, wherein the lattice parameters of the 110 crystal plane of the layer are... The interlayer spacing is 0.308 nm, along the 003 crystal plane. The lattice distortion factor is 0.77 nm. The ratio is 1.10, and the manganese-oxygen-copper bond angle shifts by 4.2° relative to the ideal hexagonal symmetry lattice; during the reaction, the catalyst layer is activated by the strain field locked by the 3500rpm mechanical shearing and rapid cooling process in the preparation procedure, utilizing the copper and manganese... Tracks and iron The spatial overlap of orbits establishes a directional electron transfer path, which satisfies the following calculation formula: ,in, The distortion factor characterizes the degree of lattice stretching in laminates. This represents the average interatomic distance between manganese and copper atoms in the laminated structure. is the average interatomic distance between iron atoms in the laminate structure.

[0041] The reaction system is maintained When the catalytic process is initiated at a pH of 9.0, the iron active centers preferentially coordinate with hydrogen peroxide molecules under the electron transfer driven by the internal stress field, neutralizing the alkaline environment. The technology suppresses cyclic degradation; through the controlled distribution of ternary metal ions during lattice formation, copper and manganese are used to provide electronic compensation for the iron active centers, enhancing their redox efficiency under weakly alkaline conditions; it resolves the contradiction between catalytic activity and structural stability in alkaline environments by utilizing atomically dispersed metal center vacancies to generate activated dissolved oxygen, achieving continuous degradation of organic pollutants within a single structure. This technical solution alters the local electronic state density of the active centers, making the originally controlled catalytic activity more stable. The constrained chemical kinetic process is transformed into a stress-driven physicochemical process under the distorted lattice framework; the results of continuous operation for 100 hours show that the chemical oxygen demand removal rate in wastewater remains stable and the mass dissolution rate of active components is maintained at a level below 0.5 mg / L; based on the design of lattice asymmetric distortion locking, the catalytic efficiency is anchored to the physical strain state solidified by the process specification by constructing electron transfer paths at the atomic scale.

[0042] Example 2: In a test scenario treating simulated dyeing and printing wastewater, the initial chemical oxygen demand (COD) of the wastewater system was 1200 mg / L, and it contained 2.5% sodium chloride by mass. The initial... The value was set to 9.0; the experimental platform used a continuous stirred tank with a constant temperature jacket, and the reaction system's values ​​were collected in real time through an online electrode monitoring system. The value is related to temperature changes, with the control precision of temperature fluctuations being [value missing]. 0.1 ,and The recording resolution is 0.01; the amount of hydrogen peroxide added is determined based on the concentration of chemical oxygen demand in the wastewater, and its mass ratio is set to 1:1; the concentration of the catalyst is maintained at 1.0 g / L; the sampling cycle is set to balance the immediacy of reaction kinetic monitoring with the data processing load, and the sampling frequency is set to collect samples once every 10 minutes to ensure that the concentration jump at the beginning of the catalytic reaction can be captured.

[0043] The catalyst sample used in this experiment was produced according to the aforementioned preparation procedure, wherein the molar ratio of iron, copper, and manganese in the mixed metal salt solution was set to 1:0.25:0.75, and the total metal ion concentration was 1.0 mol / L; during the co-precipitation stage, the dropping rate of the alkaline solution was adjusted by feedback to control the reaction system. The value was kept constant at 10.0, while the agitator was driven to maintain a shear rate of 3500 rpm; the precursor slurry was at 70... Aging for 18 hours under the specified conditions, with a cooling rate of 12. Rapid cooling at a rate of / min until the material temperature drops to 30℃ The following is the lattice distortion factor of the obtained product. By the powder The X-ray diffraction pattern, obtained after refinement, satisfies the following calculation formula: ,in, The distortion factor characterizes the degree of lattice stretching in laminates; is the average interatomic distance between manganese and copper atoms in the laminate structure, in nm; is the average interatomic distance between iron atoms in the laminate structure, expressed in nm.

[0044] Table 1: Summary Table of Sample Group Performance Test Results

[0045]

[0046] Referring to Table 1, samples A1 to A4 of this invention are... The catalytic activity remained stable within a value range of 3.0 to 10.0, with chemical oxygen demand removal rates consistently above 85.3%. Comparison of data from samples C1 and C2 revealed that, in the absence of manganese or copper, the lattice distortion factor... The temperature dropped back to near the ideal lattice value, causing a sharp decline in the chemical oxygen demand removal rate under alkaline conditions, thus confirming the synergistic effect of ternary metal ion distribution and distorted structure in improving electron transfer efficiency; the control group D1, due to its cooling rate of only 2... / min, unable to effectively lock asymmetric distortions, which in The catalytic efficiency at a value of 9.0 is lower than that of sample group A3, and this comparative result confirms the importance of the rapid cooling process in the preparation process for solidifying electron tunnels; experimental data show that as the reaction system... As the pH value shifts from acidic to weakly basic, the catalytic performance decrease of the sample group in this invention is limited to within 7.2%, while the mass dissolution rate of metal ions remains below 0.21 mg / L; when the reaction system... When the value further increased to 11.0, the chemical oxygen demand removal rate of sample group B1 decreased to 42.6%, which is consistent with the chemical instability trend of the plate skeleton under strong alkaline environment. Through the magnetic property test of the sample after reaction, the saturation magnetization of the sample group of the present invention remained at 2.4 emu / g, which supports the recycling of catalyst in the industrial field through magnetic separation. Finally, the closed loop from raw data acquisition to verification of catalytic efficiency law was completed.

[0047] Example 3: This example combines Figures 1 to 2 The description of Fe-Cu-Mn ternary hydrotalcite catalysts and their preparation methods is as follows: Figure 1 As shown, in an alkaline wastewater environment, To address the challenge of ions attempting to shield Fe active sites, leading to the deactivation of traditional catalysts, this technology employs a distorted lamellar structure response mechanism for environments ranging from pH 7.0 to 10.0. Through asymmetric stretching and distortion activation, the manganese-oxygen-copper bond angle shifts by 3.2° to 4.8°. Under the influence of the internal stress field, this induces a directional shift of the electron cloud, thereby constructing an electron transfer path to release polarization binding. By neutralizing the polarization binding effect and removing the shielding effect, the active sites in the core mechanism remain active, ultimately achieving wide pH adaptability and maintaining catalytic activity. This allows for stable operation within the pH range of 7.0 to 10.0 for the efficient treatment of alkaline wastewater.

[0048] like Figure 2 As shown, the catalyst exhibits a layered crystal structure, with layer thicknesses ranging from 15 nm to 35 nm and lattice parameters a ranging from 0.305 nm to 0.312 nm. The interlayer spacing along the 003 crystal plane is... The wavelength ranges from 0.75 nm to 0.79 nm, and the manganese-oxygen-copper bond angle shifts from 3.2° to 4.8°. According to the diagram, the layer structure consists of... Composed of octahedral units, with Fe (iron), Cu (copper), and Mn (manganese) atoms arranged in an atomically dispersed manner as metal central sites. The surface of the layers is covered with OH hydroxyl groups, and there are vacancies at the metal central sites within the metal arrangement. Interlayer regions are distributed with… carbonate and Water of crystallization, electrons The atoms are transferred between the metal atoms in the layers via specific pathways.

[0049] Example 4: Wastewater system in dyeing and printing wastewater treatment operation The value fluctuates between 8.5 and 10.0, and the water contains complexing agents; these operating conditions require the catalyst to induce dissolved oxygen activation through surface site vacancies to replenish the high concentration of dissolved oxygen. The decline in hydroxyl radical production under certain conditions was addressed by preparing a product with controlled vacancy concentration according to the aforementioned specific implementation method. - - The ternary hydrotalcite catalyst, wherein the initial acidity of the mixed metal salt solution in step 112 is adjusted to introduce cation vacancies accounting for 2.4% of the total number of metal central sites; during the high-pressure aging stage, the pressure in the reactor is increased. Constantly maintained at 0.8 MPa to suppress the pressure along the laminate. axial growth, adjusting the lattice parameters of the 110 crystal plane of the layer. Locked at 0.310 nm; mechanical shearing at 3500 rpm generates shear work, which is converted into lattice stress. This process satisfies the following energy balance relationship: ,in, The internal energy increment absorbed per unit mass of the lattice is expressed in J / kg. The shear energy conversion coefficient is taken as 0.15; This represents the actual mechanical shear rate, expressed in rpm. The critical shear rate for maintaining lattice symmetry during growth is 2000 rpm. Under high-load conditions with a value of 9.5, the catalyst plate contains 12 The asymmetric tensile distortion state locked by the rapid quenching procedure produces a 4.5° manganese-oxygen-copper bond angle shift, which drives electron flow towards the iron active center. Vacancies at the metal central sites distributed on the surface regulate the local electronic state density, reducing the adsorption energy of dissolved oxygen molecules from -0.12 eV to -0.45 eV, inducing their in-situ conversion to singlet oxygen. Utilizing the synergistic effect of the physical strain field and defect energy levels of the laminated structure, a wide... Multi-path oxidation reactions are triggered under certain environmental conditions; data from 120 consecutive hours of operation indicate that the catalyst's lattice parameters... The fluctuation range is less than 0.002nm, and the chemical oxygen demand removal rate remains above 87.5%.

[0050] In the gradient experiment used to verify the contribution of the defect energy level of the laminate to the catalytic activity, the metal ion loss rate during the precursor precipitation process was controlled by adjusting the initial acidity value of the mixed metal salt solution in step 112, thereby generating cation vacancies of different densities. Three groups of catalyst samples with cation vacancy concentrations of 1.5%, 2.2%, and 3.0% were prepared in the experimental group. Their band gap energy values ​​were measured by UV-Vis diffuse reflectance spectroscopy. The data showed that as the vacancy concentration increased from 1.5% to 3.0%, the stimulated electronic transition energy level of the material shifted from 2.1 eV to 1.8 eV. This energy level shift enhanced the catalyst's utilization efficiency of visible light and its polarization ability for dissolved oxygen molecules, increasing the initial oxidation rate of organic pollutants in wastewater by 12.5% ​​under anoxic conditions without hydrogen peroxide replenishment. This preparation method based on physical parameter calibration eliminates the randomness in the vacancy construction process by quantifying mechanical shear energy and aging pressure, enabling the catalyst to exhibit performance stability under dynamic conditions.

[0051] Example 5: Under calibration conditions before the catalyst batch was put into production, high-purity silicon powder was used as an internal standard. X-ray diffraction standard calibration procedure to correct systematic errors between detection equipment; the catalyst sample to be tested is physically mixed with silicon powder at a mass ratio of 9:1, and the diffraction angle is... for to Perform a scan within the range, setting the step size to... The sampling time is 5 seconds per step; the obtained raw diffraction data is input into a lattice fitting model based on the least squares method, and the standard diffraction sites of the silicon powder 111 crystal plane are compared. To correct the zero-point drift error of the diffractometer, peak stripping and center fitting were performed on the 110-like hydrotalcite crystal plane to calculate the average interatomic spacing. and The distortion factor of this batch of catalyst was determined using the following formula. : ,in, The distortion factor characterizes the degree of lattice stretching in laminates. The distance between manganese and copper atoms in the laminate structure is expressed in nm. This represents the average interatomic distance between iron atoms within the laminate structure, expressed in nm.

[0052] When the system faces on-site deployment conditions with fluctuating organic loads in wastewater treatment, a pre-commissioning procedure based on the reaction rate constant is executed to determine the initial baseline value of hydrogen peroxide dosage for a specific batch of catalyst. On-site wastewater is injected into a 1L container, 1.0g of the catalyst from that batch is added, and the system is adjusted. The catalytic reaction was initiated with a hydrogen peroxide to chemical oxygen demand (COD) mass ratio of 9.0, using three energy levels: 0.5:1, 1:1, and 1.5:1. Absorbance data was recorded within 15 minutes of reaction initiation using an online monitoring system, and the apparent rate constant under different addition ratios was calculated. When the growth slope of this constant approaches 0, the corresponding mass ratio is set as the control parameter for automatic on-site drug replenishment; the amount of interference caused by environmental fluctuations is included in the initial setting so that the operating parameters of the catalytic system are within the preset range.

[0053] Example 6: In calibration conditions involving catalyst production consistency control, a dosage calibration procedure based on the aspect ratio parameter of the plates was executed; the hydrodynamic diameter of the catalyst particles in the aqueous dispersion system was collected using a dynamic light scattering instrument. The transverse particle size of the laminate was measured using transmission electron microscopy. With thickness Determine the aspect ratio parameter based on the above measurements. It satisfies the formula The values ​​are between 10 and 15. In a constant-pressure reaction system with a mechanical stirring rate of 500 rpm, the mass transfer correction coefficients corresponding to samples with different aspect ratios are calculated by monitoring the decay trajectory of the chemical oxygen demand concentration of wastewater over time. The obtained correction coefficients are used to correct the catalyst addition setpoint in the automatic control system.

[0054] When the system is operating continuously and passivation occurs at sites inside the reactor due to the accumulation of organic matter, a maintenance decision procedure based on kinetic exponential feedback is executed to determine the catalyst replacement cycle; the concentration of organic matter in the reaction system is collected using an online monitoring instrument, and the rate constant for the current period is calculated. The obtained real-time rate constant and the reference rate constant under calibration conditions; Compare the results and calculate the rate decay exponent using the following formula. : ,in, The rate decay exponent, As the reference rate constant, The current rate constant; when the rate decay exponent When the value exceeds 0.35 and this state lasts for 20 minutes, the system automatically drives the discharge valve to open and performs catalyst recovery.

[0055] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A Fe-Cu-Mn ternary hydrotalcite catalyst, characterized in that, include: The catalyst is a ternary layered double hydroxide with a distorted lamellar structure, consisting of iron, copper and manganese elements, which are distributed in an atomically dispersed state at the metal central sites of the layered double hydroxide lamellar structure. The oxygen octahedrons in the laminate structure exhibit an asymmetric stretched distortion state, causing the manganese-oxygen-copper bond angles within the laminate to shift by 3.2° to 4.8° relative to the ideal hexagonal symmetric lattice. The molar ratio of metal elements in the catalyst satisfies the following conditions: the molar ratio of copper to manganese is 1:2 to 1:5, and the molar ratio of the sum of the molar amounts of copper and manganese to that of iron is 2:1 to 4:

1. Lattice parameters of the catalyst in the 110 crystal plane direction of the layer The interlayer spacing is 0.305 nm to 0.312 nm, and in the 003 crystal plane direction. The wavelength ranges from 0.75nm to 0.79nm. Copper and manganese in the layer Tracks and iron The orbitals construct an electron transfer path through spatial overlap. Under pH conditions of 7.0 to 10.0, the electron cloud shifts through the internal stress field generated by the asymmetric stretching distortion state, thereby releasing the polarization binding of hydroxide ions on the iron active site and maintaining the catalytic activity of the iron active site surface. The catalyst has a specific surface area of ​​85 m² / g to 135 m² / g, and by controlling the supersaturation of the nucleation environment, the persistent internal stress generated by iron, copper and manganese elements during the crystal lattice formation process locks the shift of the manganese-oxygen-copper bond angle.

2. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The general chemical formula of a catalyst is ;in, , and Let be the mole fraction of the metallic element, satisfying , , ,and ; The mole fraction of carbonate ions satisfies ; The value represents the water of crystallization, ranging from 0.5 to 2.

0. The catalyst maintains electroneutrality by compensating for the charge of the layer structure through carbonate ions within the interlayer gaps.

3. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The catalyst has a microstructure of stacked hexagonal plates with a lateral particle size of 150 nm to 400 nm and a thickness of 15 nm to 35 nm. The hexagonal plates form an open-plate structure with step defects at the edges through heterogeneous nucleation of ternary metals during the co-precipitation process.

4. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The crystal structure characteristics of the catalyst are defined by the intensity of X-ray diffraction peaks. The ratio of the diffraction peak intensity of the 003 crystal plane to that of the 006 crystal plane is 1.8 to 2.

5. The intensity ratio characterizes the highly ordered arrangement of iron, copper and manganese elements in the laminate structure.

5. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The hydroxyl coverage density on the catalyst surface ranges from 8.5 μmol / m² to 12.0 μmol / m²; in reaction systems with pH values ​​ranging from 7.0 to 10.0, the adsorption energy of hydrogen peroxide molecules by the iron active sites of the catalyst ranges from 0.35 eV to 0.55 eV.

6. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The degree of lattice distortion of a catalyst is measured by the ratio of interatomic distances. Measurement, interatomic spacing ratio Satisfy the following formula: ,in, The distortion factor characterizes the degree of lattice stretching in laminates; This represents the average interatomic distance between manganese and copper atoms in the laminate structure. The average interatomic distance between iron atoms in a laminated structure; interatomic distance ratio. It meets the range of 1.05 to 1.

12.

7. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The catalyst exhibits magnetic recovery characteristics, with a saturation magnetization ranging from 1.2 emu / g to 3.5 emu / g. The magnetic characteristics originate from the ferromagnetic arrangement generated by the superexchange interaction between iron and manganese elements within the layers.

8. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The layered structure contains metal central site vacancies, which account for 1.5% to 3.0% of the total number of metal central sites. These metal central site vacancies induce the activation of oxygen molecules on the catalyst surface by adjusting the local electronic state density of the layer.

9. The Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, The catalyst exhibits erosion resistance. After continuous operation for 100 hours in a reaction system with pH values ​​ranging from 7.0 to 10.0, the mass dissolution rate of metal ions is less than 0.5 mg / L, and the offset of the manganese-copper bond angle remains constant. The catalyst is prepared by reacting a mixed metal salt solution containing iron, copper, and manganese salts with an alkaline solution in a precipitation environment with pH values ​​ranging from 9.5 to 10.

5. By controlling the mechanical shear rate during the precipitation process, in-situ encapsulation of enduring internal stress is achieved.

10. A method for preparing a Fe-Cu-Mn ternary hydrotalcite catalyst, used to prepare the Fe-Cu-Mn ternary hydrotalcite catalyst according to claim 1, characterized in that, Includes the following steps: Step 111: Dissolve iron salt, copper salt and manganese salt in water to obtain a mixed metal salt solution, wherein the molar ratio of copper to manganese is 1:2 to 1:5, and the molar ratio of the sum of the molar amounts of copper and manganese to that of iron is 2:1 to 4:

1. Step 112: The mixed metal salt solution and the alkaline solution are added dropwise to the reactor in parallel to carry out a co-precipitation reaction. During the reaction, the pH of the reaction system is maintained at 9.5 to 10.5 by adjusting the dropping rate of the mixed metal salt solution and the alkaline solution, while the shear rate of the reaction system is controlled at 2800 rpm to 4000 rpm, so as to generate persistent internal stress by adjusting the supersaturation of the nucleation environment during the formation of the lamination lattice. Step 113, the product after the co-precipitation reaction is heated at 60°C. Up to 80 The catalyst is obtained by aging at a certain temperature for 12 to 24 hours, followed by filtration, washing and drying.

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