Process for treating carbon capture waste amine with persulfate activated by a hydroxyl confined polymorph cobalt catalyst

Abstract

This invention discloses a method for activating persulfate treatment of carbon-capturing waste amines using a hydroxyl-confined cobalt catalyst of multiple forms; belonging to the technical field of industrial wastewater treatment, this invention uses SiO2 rich in silanol groups as a carrier, loads cobalt species through strong electrostatic adsorption, and controls the Si:Co molar ratio to allow cobalt to coexist in multiple forms such as single atoms, clusters, and nanoparticles; utilizes the in-situ buffering effect of surface hydroxyl groups to promote the deprotonation of protonated MEA and restore its reactivity, while simultaneously inhibiting metal leaching by anchoring cobalt species through Co-O-Si covalent bonds; the multiple forms of cobalt synergistically activate PMS to directionally generate SO4. •‑ , • OH、 1 This method utilizes reactive oxygen species such as O2 and Co(IV)=O to achieve deep mineralization of amine-contaminated wastewater. It solves problems such as low mass transfer efficiency, catalyst deactivation, and uncontrollable reaction pathways, providing technical support for the environmentally friendly transformation of the entire CCUS process.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment and relates to a method for treating carbon and capturing waste amines by activating a hydroxyl-confined cobalt catalyst with persulfate. Specifically, it is a method for treating carbon and capturing waste amines by activating a hydroxyl-confined cobalt catalyst with persulfate. Background Technology

[0002] In recent years, the rise of metal-organic framework (MOF)-derived metal single-atom catalysts (M-SACs) has opened up a completely new pathway for heterogeneous catalysis. By controlling the pore structure and metal coordination environment of MOF precursors, atomically dispersed metal active sites, such as Co-N4 and Fe-N4, can be generated after carbonization. x Coordination structure. From a structure-activity relationship perspective, the intrinsic activity of the metal active center is highly correlated with its electronic structure: taking Co-SACs as an example, when Co coordinates with nitrogen atoms to form a Co-N4 structure, its activation performance for PMS is significantly better than that of ordinary carbon-based materials; and changes in the coordination environment (such as from Co-N4 to Co-N3) can lead to a shift in the PMS activation pathway from being dominated by free radicals to being dominated by high-valence metal oxo species. From the perspective of selective degradation, a single M-N4 site tends to produce SO4. •- , • The OH radical pathway is highly efficient at degrading pollutants, but radicals are easily quenched in high-salt wastewater. However, low-coordination M-N3 structures or co-doping with other heteroatoms (O / S) can enhance the degradation efficiency of high-valence metal species (Co(IV)=O) or... 1The O2 yield demonstrates a selective degradation advantage for specific pollutants (such as electron-rich structure pollutants) and exhibits good resistance to interference from coexisting ions. The atomic-level dispersion characteristics and tunable coordination environment of M-SACs provide new possibilities for mass transfer and reaction pathway regulation. However, current PMS activation systems based on MOF-derived M-SACs still face the following common bottlenecks in applications to industrial wastewater (especially highly alkaline, high-salt, and high-concentration amine-contaminated wastewater): First, the pore size distribution of MOF-derived materials is relatively uniform, with insufficient hierarchical pore structures and limited mass transfer channels, resulting in low utilization of internal active sites; second, background matrices and reaction intermediates in complex wastewater are easily adsorbed around the pores, causing "pore blockage and inactivation" of active sites; third, there is currently a lack of systematic theoretical guidance on how to accurately design and screen suitable metal-ligand coordination environments based on the molecular structure and electric field distribution characteristics of actual pollutants in the wastewater to achieve targeted degradation of specific pollutants, relying mostly on empirical trial and error. Furthermore, the synthesis conditions of MOF-derived M-SACs are harsh, and the surface hydroxyl content is usually low, so they do not have the function of using hydroxyl groups to regulate the local microchemical environment of waste liquid to promote substrate activation. At the same time, existing studies have mostly focused on single atomic-level dispersions and have not yet explored the multi-form cobalt synergistic catalytic mode of coexistence of single atoms, clusters and nanoparticles, which cannot fully realize the orthogonal regulation potential of different cobalt species on PMS activation pathway.

[0003] Therefore, the core technical problem to be solved by this invention is: how to simultaneously achieve deep mineralization and destruction of pollutants, rapid mass transfer of reactants, long-term stable operation of catalysts, and directional generation of reactive oxygen species in the highly alkaline, high-salinity, multi-component, and highly ecotoxic amine-polluted wastewater generated during the amine carbon capture process. In particular, how to simultaneously solve the two deep-seated scientific problems of "directional selection of PMS activation pathway" and "substrate quantification deactivation" that have not been fully solved in the prior art through the synergistic regulation of cobalt atomic-level morphology distribution and surface hydroxyl function, thereby providing a method for deep treatment of amine-polluted wastewater with high efficiency, high stability, and high selectivity to meet the environmentally friendly engineering requirements of the entire CCUS technology process. Summary of the Invention

[0004] To address the problems in the background art, the present invention adopts the following technical solution: This invention provides a method for activating a hydroxyl-confined cobalt catalyst to treat carbon-captured waste amines using persulfate, the method comprising the following steps: S101: Prepare a SiO2 support rich in silanol groups on its surface, and load cobalt species onto the support by strong electrostatic adsorption. By adjusting the molar ratio of Si to Co in the precursor, the cobalt species can be in at least two forms, namely single atoms, clusters and nanoparticles, to obtain a hydroxyl-confined multi-form cobalt catalyst. S102: The catalyst obtained in step S101, persulfate PMS, and amine-polluted waste liquid discharged from the carbon capture system are mixed in a reactor, and the temperature is controlled at 15-35°C. S103: The silanol groups on the surface of the multi-form cobalt catalyst provide in-situ buffering against the acidic effect introduced by PMS, promoting the deprotonation of organic amine molecules in the waste liquid that have been deactivated due to protonation, thus restoring them to neutral amine molecules. Simultaneously, the silanol groups chemically confine pollutant molecules, compressing the mass transfer distance to the nanoscale. The multi-form cobalt species synergistically activate PMS, generating sulfate radicals (SO4). •- hydroxyl radicals • OH, singlet oxygen 1 O2 and various reactive oxygen species, including the high-valent cobalt oxygen species Co(IV)=O; S104: By directionally selecting the generation pathway of reactive oxygen species through the atomic-level morphological distribution of cobalt species regulated in step S101, deep mineralization of organic components in amine-contaminated wastewater is achieved.

[0005] Preferably, the preparation process of the SiO2 support with silanol-rich surface in step S101 is as follows: triblock copolymer P123, deionized water and hydrochloric acid solution are mixed and stirred at 35-45°C for 4-8 hours. Tetraethyl orthosilicate (TEOS) is added and stirred at 35-45°C for 20-28 hours. The mixture is then transferred to an autoclave and hydrothermally crystallized at 85-95°C for 20-28 hours. After filtration, washing and drying, the mixture is calcined at 500-560°C for 4-8 hours to remove the template agent. The resulting white solid is then immersed in a 1-5% H2O2 solution and allowed to stand at room temperature for 8-16 hours. After washing and drying, the SiO2 support with silanol-rich surface is obtained.

[0006] Preferably, when the molar ratio of Si to Co is 8:1, the cobalt species are in a single-atom form; when the molar ratio of Si to Co is 4:1, the cobalt species are in a cluster form; when the molar ratio of Si to Co is 2:1, the cobalt species are in a nanoparticle form; the hydroxyl density on the catalyst surface, as determined by Boehm titration, is 0.1–1.13 mmol / g, and increases with the increase of the molar ratio of Si to Co.

[0007] Preferably, the specific operation of the strong electrostatic adsorption method in step S101 is as follows: Cobalt acetate is dissolved in a mixture of ammonia and deionized water. After complete dissolution, the SiO2 support is added, and the mixture is stirred at 30-40°C for 8-16 hours. The precipitate is collected by centrifugation, and the supernatant is repeatedly washed with deionized water until the pH of the supernatant drops to 8-10. The supernatant is then dried at 80-120°C for 2-6 hours to obtain the multi-form cobalt catalyst.

[0008] Preferably, the reactor in step S102 is a continuous flow reactor directly coupled to the downstream waste liquid discharge port of the carbon capture system absorption tower and regeneration tower circulation loop, and the continuous flow reactor is selected from either a catalyst membrane filtration device or a catalyst-loaded cotton ball packed bed reactor. In the catalyst membrane filtration device, the waste liquid vertically penetrates the filter membrane layer loaded with catalyst at a flow rate of 3 to 10 mL / min, and PMS is injected synchronously through a bypass injection pump. In the catalyst-loaded cotton ball packed bed reactor, waste liquid flows through the catalyst-loaded cotton ball packed bed at a flow rate of 10-30 mL / min, and PMS is injected through another channel.

[0009] Preferably, the endpoint criterion for the deep mineralization process in step S104 is: the organic pollutants in the waste liquid are completely oxidized and decomposed, the total organic carbon (TOC) removal rate is not less than 50%, and the final products are CO2, H2O, and harmless inorganic salt ions NO3. - SO4 2- NH4 + One or more of them, with a cobalt ion leaching concentration in the effluent below 0.1 mg / L.

[0010] Preferably, the silanol group in step S103 performs a dual function: On the one hand, the silanol group acts as a basic buffer site, in situ counteracting the acidic effect introduced by PMS, promoting the protonation of monoethanolamine MEA, i.e., -NH3. + Deprotonation restores the highly reactive neutral amine molecule -NH2; on the other hand, the silanol groups form Co-O-Si covalent bonds with the cobalt species, chemically anchoring the cobalt active centers in the form of single atoms, clusters and nanoparticles into the SiO2 support framework, inhibiting metal leaching and particle agglomeration under strong alkaline and high salt conditions.

[0011] Preferably, the pathway for the generation of reactive oxygen species through the morphological selection of cobalt species in step S104 is as follows: Single-atom cobalt species preferentially induce the generation of high-valence cobalt oxide species Co(IV)=O, which breaks the CN bond in organic amine molecules via electrophilic attack; clustered cobalt species tend to generate SO4. •- and • OH radicals; cobalt species in nanoparticle form tend to generate 1 O2 is a non-radical reactive oxygen species; by regulating the ratio of single atoms, clusters and nanoparticles, the radical pathway, non-radical pathway and high-valence metal oxygen species pathway in the PMS activation pathway can be selected on demand.

[0012] On the other hand, the present invention provides a hydroxyl-confined multi-form cobalt catalyst obtained by the method described above, characterized in that it comprises a SiO2 support, multi-form cobalt species supported on the support, and abundant silanol groups (Si-OH) on the surface of the support; the multi-form cobalt species include at least two of single atoms, clusters, and nanoparticles; the density of the silanol groups is 0.1 to 1.13 mmol / g; and the silanol groups are connected to the cobalt species by Co-O-Si covalent bonds.

[0013] Finally, this invention provides a carbon capture-catalytic oxidation coupling system, which includes a catalyst and directly integrates the catalytic oxidation unit downstream of the waste liquid discharge port of the absorption tower and regeneration tower circulation loop of the amine carbon capture process. The catalytic oxidation unit operates at 15-35°C and uses persulfate as an oxidant to perform online deep mineralization treatment of amine-contaminated waste liquid.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Complete destruction of pollutants: Through the synergistic effect of hydroxyl confinement and cobalt species morphology regulation, pollutant molecules are completely mineralized into inorganic small molecules, overcoming the defect of existing physical separation technology that only achieves phase transfer of pollutants.

[0015] (2) Significantly improved mass transfer and reaction efficiency: The acidic effect introduced by the in-situ buffer PMS of the abundant hydroxyl (-OH) on the catalyst surface promotes the deactivation of MEA (-NH3) due to protonation. + The deprotonation process restores the highly reactive neutral amine molecule (-NH2), eliminating the mass transfer and reaction kinetic barriers caused by the change in the charge state of the substrate. In addition, the confinement effect of the hydroxyl group on the protonated MEA greatly compresses the diffusion distance, confining the pollutant molecule to the vicinity of the ROS generated at the cobalt site, thereby improving the collision efficiency between ROS and pollutants.

[0016] (3) Ensures long-term stable operation of the catalyst: Through the strong Co-O-Si covalent bonds formed between the hydroxyl groups on the SiO2 support surface and the cobalt species, the active centers of various forms such as single atoms, clusters and nanoparticles are firmly chemically anchored to the support skeleton, effectively inhibiting the leaching, migration and aggregation of metal active centers under strong alkaline and high salt conditions; at the same time, the chemical inertness of the SiO2 skeleton is used to resist the erosion of complex waste liquid environment, giving the catalyst excellent long-term operating stability.

[0017] (4) Directional control of reaction pathways and synergistic activation of substrates were achieved: By precisely controlling the atomic-level morphological distribution of cobalt—from single atoms to clusters and then to nanoparticles—different degrees of lattice strain and coordination symmetry breaking were induced, thereby achieving control over the electronic structure of the metal center (such as d-band centers, e-band centers, etc.). gAtomic-scale tailoring of orbital occupancy allows for "on-demand" directional selection of PMS activation pathways (radical / non-radical). More importantly, the regulatory function of cobalt speciation on ROS generation pathways is coupled with the regulatory function of surface hydroxyl groups on substrate protonation states. That is, "cobalt speciation determines which ROS is generated, and hydroxyl groups determine whether the substrate is in an attackable active state." This simultaneous intervention from the two dimensions of active species generation and substrate activation fundamentally solves the problems of uncontrollable reaction pathways and high ineffective consumption of oxidants in existing technologies. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope.

[0019] Figure 1 Flow diagram of carbon capture amine polluted waste liquid catalytic degradation process based on PMS-AOPs; Figure 2 TEM images and EDS elemental distribution mappings of single-atom (ac), cluster (df), and nanoparticle (gi) catalysts; Figure 3 (a) XRD and (b) XPS characterization results of single-atom, cluster, and nanoparticle catalysts; Figure 4 (a) Degradation performance tests of different systems; Figure 4 (b) In H2 18 In O, the CoSA+PMS system consists of PMS 16 PMS generated by O 16 O 16 O and PMS 16 O 18 Ion chromatogram of O species; Figure 4 (c) In H2 18 O and H2 16 In-situ Raman spectra collected during the reaction in O; Figure 4 (d) In H2 18 PMS generated in O 16 O 18 High-resolution mass spectrometry detection of O; Figure 4 (e) Degradation efficiency under different operating conditions; Figure 5 (a) Schematic diagram of a continuous flow catalytic unit for an integrated membrane microreactor or scaled-up microreactor; Figure 5 (b) Degradation of MEA in membrane microreactors and Figure 5 (c) TOC removal status; Figure 5 (d) Degradation of MEA in scaled-up microreactors and Figure 5 (e) TOC removal status. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0023] To facilitate the explanation of the overall technical structure of the method of this invention, the current embodiment first summarizes and describes the main functional modules included in this invention. It should be noted that the following functional module division is only used to clearly illustrate the technical concept and implementation logic of this invention and does not constitute a limitation on the scope of protection of this invention. Each functional module can be executed independently in sequence, or it can be implemented collaboratively in combination by a unified bearing defect detection system.

[0024] Example 1: Principle of Preparation Method This invention provides a method for activating persulfate treatment of carbon-captured waste amines using a hydroxyl-confined multi-form cobalt catalyst, comprising the following steps: Step 1: Provide a hydroxyl-confined catalyst Synthesis steps: Synthesis of SiO2 support First, 24 g of triblock copolymer P123 and 650 mL of deionized water were added to 140 mL of 2M HCl solution and stirred at 40 °C for 6 hours. Then, 55 mL of tetraethyl orthosilicate (TEOS) was added, and stirring was continued at 40 °C for 24 hours. The resulting solution was transferred to a polytetrafluoroethylene-lined autoclave and subjected to hydrothermal crystallization at 90 °C for 24 hours. Finally, the solution was filtered, washed with deionized water, and dried at 80 °C for 24 hours to obtain a white solid.

[0025] Synthesis of hydroxyl-containing supports The above-mentioned support was calcined at 550 °C for 6 hours to remove the template agent. It was then immersed in a dilute H₂O₂ solution (3 wt%) and allowed to stand at room temperature for 12 hours. After removal, it was thoroughly washed with deionized water and dried at room temperature for 1 day to obtain a support rich in silanol groups (denoted as SiO₂-OH).

[0026] Synthesis of CoSA-SiO2 catalysts in the form of single atoms, CoAC-SiO2 in the form of clusters, and CoNP-SiO2 catalysts in the form of nanoparticles (hereinafter referred to as CoSA, CoAC, and CoNP). Catalysts of different cobalt species were prepared using strong electrostatic adsorption (SEA). For each batch of synthesis, the Si:Co molar ratio was adjusted to 8:1, 4:1, and 2:1 by varying the amount of cobalt acetate precursor added, respectively, to obtain cobalt single atoms, clusters, and nanoparticles.

[0027] The specific procedure is as follows: Cobalt acetate (Co(CH3COO)2·4H2O) of corresponding masses was dissolved in a 150 mL ammonia solution (50 mL deionized water + 100 mL ammonia, 30 wt%). After complete dissolution, the hydroxyl-containing support synthesized in the previous step was added to the above solution. The mixture was stirred continuously at 35°C for 12 hours. After the reaction was complete, the precipitate was collected by centrifugation and repeatedly washed with deionized water until the pH of the supernatant dropped to 9. Finally, the product was dried at 100°C for 4 hours to obtain the catalyst.

[0028] Typical feed amounts for each catalyst (total silicon moles = 0.2463 mol): CoSA (Si:Co = 8:1): Approximately 0.03079 mol of Co is required; weigh out 7.67 g of cobalt acetate. CoAC (Si:Co = 4:1): Approximately 0.06158 mol of Co is required; weigh out 15.34 g of cobalt acetate. CoNP (Si:Co = 2:1): Approximately 0.12316 mol of Co is required, and 30.68 g of cobalt acetate is weighed out.

[0029] Step 2: Constructing a confined catalytic reaction system The catalyst obtained in step 1, persulfate (PMS), and the amine-contaminated waste liquid to be treated were mixed in a reactor at a temperature of 25°C. The catalyst contains a precisely controlled distribution of cobalt morphologies (single atoms, clusters, nanoparticles) and abundant surface hydroxyl (-OH) sites.

[0030] Step 3: Implement hydroxyl-confined synergistic catalytic oxidation In the reaction system constructed in step 2, the hydroxyl groups (-OH) in the catalyst are used to chemically confine pollutant molecules, reducing the mass transfer distance between ROS and pollutants to the nanoscale. Simultaneously, the acidic effect introduced by the in-situ buffering of PMS by surface hydroxyl groups promotes the deactivation of MEA (-NH3) due to acid protonation. + The deprotonation process restores the highly reactive neutral amine molecule (-NH2), eliminating the hindrance of substrate charge state to mass transfer and reaction kinetics. Confined activation of PMS using the Co site, through the synergistic effect of various cobalt species including single atoms, clusters, and nanoparticles, generates sulfate radicals (SO42-). •- ), hydroxyl radicals ( • OH), singlet oxygen ( 1 Various reactive oxygen species (ROS), including O2 and high-valence metal oxygen species.

[0031] Step 4: Regulating the reactive oxygen species generation pathway By precisely controlling the cobalt species morphology of the catalyst described in step 1—from atomically dispersed single atoms to sub-nano clusters and then to nanoparticles—lattice strain is induced, thereby regulating the coordination symmetry of the Co-O active sites and achieving rearrangement of the electronic structure of the metal center. Through this electronic structure regulation, the target ROS is quantitatively and directionally generated to achieve selective attack and bond breaking on pollutants with different chemical structures (such as CN bonds, amino groups, and other sensitive functional groups). This step synergizes with the regulation of the substrate quantification state by hydroxyl groups in step 3: the cobalt morphology determines "what kind of ROS is generated," and the hydroxyl group determines "whether the substrate is in an attackable active state," together achieving precise control over the degradation pathway.

[0032] Step 5: Achieve deep mineralization of pollutants Through the synergistic effect of steps 3 and 4, the recalcitrant components in the amine-contaminated wastewater, such as organic amines, organic acids, and aldehydes, are oxidized and decomposed, and ultimately mineralized into CO2, H2O, and a small amount of harmless inorganic salt ions (such as NO3). - SO4 2- The treated wastewater meets the discharge or reuse standards with significantly reduced ecotoxicity.

[0033] Example 2: Beaker Experiment (Batch Processing Experiment) Equipment and materials: Reactor: 500 mL jacketed glass beaker reactor, equipped with magnetic stirring and temperature control system.

[0034] Catalysts: CoSA, CoAC, and CoNP catalysts, with silanol (Si-OH) rich on the catalyst surface. The hydroxyl density was determined by Boehm titration to be 1.13, 0.57, and 0.1 mmol / g, respectively.

[0035] Waste liquid: Actual amine-contaminated waste liquid taken from the carbon capture system of a coal-fired power plant, with a total organic carbon (TOC) of 2500 mg / L. The main organic components are monoethanolamine (MEA) and its degradation products, and the pH is 10.5.

[0036] Processing steps: 200 mL of amine-contaminated waste liquid was added to the reactor, along with 0.2 g of catalyst (1.0 g / L). The mixture was stirred and dispersed thoroughly. 1.5 g of PMS was then added to the reaction system. The reaction was carried out at 25 °C and 300 rpm for 30 minutes. Samples were taken periodically, filtered through a 0.45 μm filter membrane, and the residual MEA concentration was determined.

[0037] Processing effect: CoSA has the best performance ( Figure 4 a) After 30 minutes of reaction, the TOC removal rate of the solution in the beaker reached 74%. Ion chromatography analysis showed that organic amines (MEA) were completely degraded, with NO3 as the main end product. - (32.3%), NH4 + (47.1%) and CO2. The concentration of Co ions leached from the solution after the reaction was less than 0.05 mg / L as detected by ICP-MS.

[0038] Mechanistic analysis shows that the abundant hydroxyl groups on the surface of the CoSA catalyst effectively buffer the local acidity introduced by PMS, promoting the deactivation of MEA (-NH3) due to protonation. + The deprotonation process restores the highly reactive neutral amine molecule (-NH2), eliminating the hindrance of substrate charge state to mass transfer and reaction kinetics. Simultaneously, atomically dispersed Co single-atom sites efficiently activate PMS to generate high-valence cobalt-oxygen species (Co(IV)=O). Figure 4 (bd), which enables selective electrophilic attack and breakage of CN bonds in MEA. Figure 4 e represents the degradation performance test under different operating conditions, confirming the universality of the CoSA catalyst.

[0039] Example 3: Continuous Flow Experiment (Two types of continuous flow devices) Figure 5 a) Device 1: Catalyst membrane filtration device (vacuum filtration membrane continuous flow reactor) Equipment and Assembly: A continuous flow reactor modified with a sand core filtration device was used. 50 mg of powdered CoSA catalyst was dispersed in 50 mL of deionized water and ultrasonically dispersed for 30 minutes to form a homogeneous suspension. This suspension was slowly poured into a sand core filtration cup equipped with a 0.22 μm mixed cellulose filter membrane, and filtration was performed under a vacuum of -0.05 MPa, allowing the catalyst to be uniformly deposited on the filter membrane surface to form a dense catalyst film (membrane area approximately 12.56 cm²). 2 (The membrane thickness is approximately 80~120 μm). After assembly, the membrane surface is slowly rinsed with deionized water to remove loose particles, thus obtaining the catalyst membrane reaction unit.

[0040] Catalyst characteristics: The Si:Co molar ratio in the precursor was adjusted to 8:1, causing the Co species to exhibit single-atom characteristics. The hydroxyl density on the catalyst surface was determined to be 1.13 mmol / g by Boehm titration.

[0041] The Si:Co molar ratio in the precursor was adjusted to 4:1, causing the Co species to exhibit cluster characteristics. The hydroxyl density on the catalyst surface was determined to be 0.57 mmol / g by Boehm titration.

[0042] By adjusting the Si:Co molar ratio in the precursor to 2:1, the Co species exhibited a nanoparticle distribution. The hydroxyl density on the catalyst surface was determined to be 0.1 mmol / g by Boehm titration.

[0043] Waste liquid: Simulated amine-contaminated wastewater (containing 50 mg / L MEA).

[0044] Processing steps: The assembled membrane reactor unit was connected to a continuous flow system, and the waste liquid was allowed to pass vertically through the catalyst membrane layer from the top of the membrane at a flow rate of 5 mL / min. A PMS solution (10 g / L concentration) was injected synchronously via a bypass injection pump and mixed with the waste liquid before entering the membrane layer. The reaction temperature was controlled at 25°C, and the treated effluent was collected and analyzed at the membrane outlet.

[0045] Processing effect: After stable operation, the TOC removal rate of the CoSA system effluent remained at 50-60%. Figure 5 c). Membrane filtration forces the wastewater to penetrate the catalyst membrane, effectively shortening the mass transfer path of pollutants to the active sites and significantly improving the contact efficiency between reactants and the catalyst. After 20 hours of continuous operation, no significant detachment of the catalyst membrane was observed, and the leaching concentration of Co ions in the effluent remained below 0.08 mg / L. The physical confinement of the membrane and the chemical confinement of the hydroxyl groups on the catalyst surface create a dual mass transfer enhancement effect. Simultaneously, the deprotonation function of the hydroxyl groups ensures that the MEA maintains high reactivity in the acidic microenvironment of the PMS.

[0046] Example 4: Catalyst-supported cotton ball packed bed reactor (impregnated supported continuous flow reactor) Equipment and Assembly: A glass column with an inner diameter of 50 mm was used as a packed bed reactor. 1.0 g of defatted cotton balls (total mass approximately 1.0 g, loose packing volume approximately 15 mL) were immersed in 50 mL of deionized water suspension containing 100 mg of CoSA (or CoAC, CoNP) catalyst powder, and the immersion was ultrasonically assisted for 30 minutes. The cotton balls were then removed and dried at 60 °C for 2 hours, and the catalyst loading was determined to be approximately 80 mg / g cotton balls. The catalyst-loaded cotton balls were then loosely packed into the glass column, and both ends were secured with quartz wool to obtain the cotton ball packed bed reactor unit.

[0047] Catalyst characteristics: The Si:Co molar ratio in the precursor was adjusted to 8:1, causing the Co species to exhibit single-atom characteristics. The hydroxyl density on the catalyst surface was determined to be 1.13 mmol / g by Boehm titration.

[0048] The Si:Co molar ratio in the precursor was adjusted to 4:1, causing the Co species to exhibit cluster characteristics. The hydroxyl density on the catalyst surface was determined to be 0.57 mmol / g by Boehm titration.

[0049] By adjusting the Si:Co molar ratio in the precursor to 2:1, the Co species exhibited a nanoparticle distribution. The hydroxyl density on the catalyst surface was determined to be 0.1 mmol / g by Boehm titration.

[0050] Waste liquid: Simulated amine-contaminated wastewater (containing 50 mg / L MEA).

[0051] Processing steps: Simulated waste liquid was pumped into the column top at a flow rate of 20 mL / min, while the PMS solution entered the packed bed through another channel. The reaction temperature was controlled at 25°C, and the effluent was collected at the bottom of the column. The reaction was run continuously for 5 hours.

[0052] Processing effect: The TOC removal rate in the effluent of the CoSA system remained stable at 60%. Figure 5 e). The three-dimensional porous fiber structure of the cotton balls provides an excellent dispersion support for the catalyst, avoiding the high pressure drop and channeling problems caused by direct packing of powdered catalysts. After 5 hours of continuous operation, the catalyst shedding amount was less than 5% of the initial loading, and the effluent Co concentration was less than 0.1 mg / L. The advantages of this approach are its simple preparation, low pressure drop, suitability for treating actual wastewater containing suspended particulate matter, and the anchoring effect of cobalt species in nanoparticle form with hydroxyl groups endowing the catalyst with good anti-leakage properties.

[0053] Overall review: Both pathways validated the advanced treatment capability of hydroxyl-confined cobalt catalysts for carbon-captured waste amines under continuous flow conditions. Surface hydroxyl groups played a dual role in both reactor configurations: firstly, buffering the acidic effect of PMS to activate the substrate; and secondly, anchoring cobalt species through Co-O-Si covalent bonds to inhibit metal leaching. Device 1, due to forced transmembrane mass transfer, exhibited slightly higher degradation efficiency and is suitable for fine-treatment scenarios; Device 2, due to its simple preparation, low pressure drop, and strong anti-fouling properties, is more suitable for engineering scale-up and practical wastewater treatment scenarios.

[0054] The following technical effects were achieved: 1. Synergistic construction of multi-morphological cobalt species and hydroxyl groups on catalyst surface By adjusting the Si / Co ratio in the precursor, precise control over the atomic-level morphology of cobalt species supported on the SiO2 support is achieved—from single atoms (CoSA) to clusters (CoAC) and then to nanoparticles (CoNP). Simultaneously, by utilizing the abundant silanol groups (Si-OH) on the surface of the SiO2 support, a bifunctional catalyst with both "multi-morphological cobalt active centers" and "high-density surface hydroxyl groups" is constructed.

[0055] 2. The "two birds with one stone" function of hydroxyl groups: deprotonation and chemical anchoring This innovative approach utilizes hydroxyl groups on the catalyst surface to address two inherent challenges in treating amine waste liquid with PMS-AOPs: firstly, to act as alkaline buffer sites to counteract the acidic effect introduced by PMS and promote the protonation and deactivation of MEA (-NH3). + First, it deprotonates to restore the highly reactive neutral amine molecule (-NH2); second, it forms Co-O-Si covalent bonds to achieve chemical anchoring of different cobalt species and inhibit metal leaching.

[0056] 3. Targeted regulation of the reactive oxygen species (ROS) generation pathway by cobalt speciation By utilizing the differences in lattice strain and coordination symmetry induced by different cobalt species (single atoms, clusters, and nanoparticles), the electronic structure of the metal center can be controlled at the atomic scale, thereby achieving on-demand selection of the PMS activation pathway—single atom sites dominate the generation of high-valence cobalt-oxygen species (Co(IV)=O) to electrophilically attack CN bonds, thereby achieving deep mineralization.

[0057] 4. Synergistic degradation mechanism of "active species generation" and "substrate state activation" A novel synergistic catalytic degradation strategy was established, in which "the cobalt form determines the type of ROS generated, and the hydroxyl group determines whether the substrate is in an attackable state." This strategy intervenes in the reaction simultaneously from two dimensions, thereby significantly improving the degradation efficiency and mineralization depth of pollutants in complex waste liquids.

[0058] 5. Continuous flow process integration for real carbon capture wastewater A continuous flow catalytic oxidation unit that can be directly coupled to the end of a carbon capture system was developed. Two engineering pathways, namely a catalyst membrane reactor and a supported packed bed, were verified. The unit achieved long-term stable operation and deep mineralization of pollutants for more than 20 hours in real strong alkaline and high-salt amine waste liquid.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for activating persulfate treatment of carbon-based waste amines using a hydroxyl-confined cobalt catalyst with multiple forms, characterized in that... The method includes the following steps: S101: Prepare a SiO2 support rich in silanol groups on its surface, and load cobalt species onto the support by strong electrostatic adsorption. By adjusting the molar ratio of Si to Co in the precursor, the cobalt species can be in at least two forms, namely single atoms, clusters and nanoparticles, to obtain a hydroxyl-confined multi-form cobalt catalyst. S102: The catalyst obtained in step S101, persulfate PMS, and amine-polluted waste liquid discharged from the carbon capture system are mixed in a reactor, and the temperature is controlled at 15-35°C. S103: The silanol groups on the surface of the multi-form cobalt catalyst provide in-situ buffering against the acidic effect introduced by PMS, promoting the deprotonation of organic amine molecules in the waste liquid that have been deactivated due to protonation, thus restoring them to neutral amine molecules. Simultaneously, the silanol groups chemically confine pollutant molecules, compressing the mass transfer distance to the nanoscale. The multi-form cobalt species synergistically activate PMS, generating sulfate radicals (SO4). •- hydroxyl radicals • OH, singlet oxygen 1 O2 and various reactive oxygen species, including the high-valent cobalt oxygen species Co(IV)=O; S104: By directionally selecting the generation pathway of reactive oxygen species through the atomic-level morphological distribution of cobalt species regulated in step S101, deep mineralization of organic components in amine-contaminated wastewater is achieved.

2. The method according to claim 1, characterized in that, The preparation process of the SiO2 support with silanol-rich surface in step S101 is as follows: Triblock copolymer P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide), deionized water, and hydrochloric acid solution are mixed and stirred at 35–45°C for 4–8 hours. Tetraethyl orthosilicate (TEOS) is added, and stirring continues at 35–45°C for 20–28 hours. The mixture is then transferred to an autoclave and hydrothermally crystallized at 85–95°C for 20–28 hours. After filtration, washing, and drying, the mixture is calcined at 500–560°C for 4–8 hours to remove the template agent. The resulting white solid is then immersed in a 1–5% (w / w) H2O2 solution and allowed to stand at room temperature for 8–16 hours. After washing and drying, the SiO2 support with silanol-rich surface is obtained.

3. The method according to claim 2, characterized in that, When the molar ratio of Si to Co is 8:1, the cobalt species are in a single-atom form; when the molar ratio of Si to Co is 4:1, the cobalt species are in a cluster form; when the molar ratio of Si to Co is 2:1, the cobalt species are in a nanoparticle form; the hydroxyl density on the catalyst surface was determined by Boehm titration to be 0.1–1.13 mmol / g, and it increases with the increase of the molar ratio of Si to Co.

4. The method according to claim 1, characterized in that, The specific operation of the strong electrostatic adsorption method in step S101 is as follows: Cobalt acetate is dissolved in a mixture of ammonia and deionized water. After complete dissolution, the SiO2 support is added, and the mixture is stirred at 30-40°C for 8-16 hours. The precipitate is collected by centrifugation and repeatedly washed with deionized water until the pH of the supernatant drops to 8-10. The supernatant is then dried at 80-120°C for 2-6 hours to obtain the multi-form cobalt catalyst.

5. The method according to claim 1, characterized in that, The reactor mentioned in step S102 is a continuous flow reactor directly coupled to the downstream waste liquid discharge port of the carbon capture system absorption tower and regeneration tower circulation loop. The continuous flow reactor is selected from either a catalyst membrane filtration device or a catalyst-loaded cotton ball packed bed reactor. In the catalyst membrane filtration device, the waste liquid vertically penetrates the filter membrane layer loaded with catalyst at a flow rate of 3 to 10 mL / min, and PMS is injected synchronously through a bypass injection pump. In the catalyst-loaded cotton ball packed bed reactor, waste liquid flows through the catalyst-loaded cotton ball packed bed at a flow rate of 10-30 mL / min, and PMS is injected through another channel.

6. The method according to claim 1, characterized in that, The endpoint criterion for deep mineralization in step S104 is: the organic pollutants in the waste liquid are completely oxidized and decomposed, the total organic carbon (TOC) removal rate is not less than 50%, and the final products are CO2, H2O, and harmless inorganic salt ions NO3. - SO4 2- NH4 + One or more of them, with a cobalt ion leaching concentration in the effluent below 0.1 mg / L.

7. A hydroxyl-confined multi-form cobalt catalyst obtained by the method according to any one of claims 1 to 6, characterized in that, The invention comprises a SiO2 support, multiple cobalt species supported on the support, and abundant silanol groups (Si-OH) on the surface of the support; the multiple cobalt species include at least two of the following: single atoms, clusters, and nanoparticles; the density of the silanol groups is 0.1–1.13 mmol / g; and the silanol groups are connected to the cobalt species by Co-O-Si covalent bonds.

8. A carbon capture-catalytic oxidation coupled system, characterized in that, The device includes the catalyst described in claim 7, and the catalytic oxidation unit is directly integrated downstream of the waste liquid discharge port in the circulation loop of the absorption tower and regeneration tower of the amine carbon capture process. The catalytic oxidation unit operates at 15-35°C and uses persulfate as the oxidant to perform online deep mineralization treatment of amine-contaminated waste liquid.

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