Metal and amine functionalized imidazole-based porous organic polymer capable of catalyzing in-situ conversion of low-concentration CO2, as well as preparation method and application thereof

Abstract

This invention discloses a metal- and amine-functionalized imidazole-based porous organic polymer (POPs-n@Ag2O) capable of catalyzing the in situ conversion of low-concentration CO2, as well as its preparation method and application. To prepare POPs-n@Ag2O, the active monomer, divinylbenzene (DVB), amino units, and 2,2'-azobis(2-methylpropionitrile) (AIBN) are first dissolved in dimethyl sulfoxide for polymerization. The reaction is heated to 100°C for 24 hours. POPs-n and Ag2O are then mixed in CH2Cl2 and stirred for 24 hours. The resulting precipitate is washed with ethyl acetate, H2O, and MeOH, and then vacuum-dried to obtain POPs-n@Ag2O. Using POP-6@Ag2O as a catalyst, the POPs-n@Ag2O can convert CO2 from actual coal-fired flue gas into oxazolidine-2,4-dione in situ, with a maximum yield of 92%. In addition, the structure-activity relationship of POP‑6@Ag2O was studied by correlating the BET specific surface area, average pore volume and nitrogen content with the CO2 absorption capacity and conversion efficiency, thereby clarifying the mechanism by which the structural characteristics of POP‑6@Ag2O affect the catalytic activity, providing an effective catalytic framework for in situ CO2 conversion under practical conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ catalytic conversion of CO2 from coal-fired flue gas, specifically to a metal and amine-functionalized imidazole-based porous organic polymer capable of catalyzing the in-situ conversion of low-concentration CO2, as well as a preparation method and application thereof. Background Art

[0002] Carbon capture, utilization, and storage (CCUS) is an indispensable technology for mitigating climate change and achieving carbon neutrality. Current CCUS technology typically involves multiple steps: first, capturing and separating a small amount of CO2 from flue gas to produce pure CO2, which is then transported to a utilization or storage site. The high energy consumption and cost of the entire CCUS process limit its application. In fact, 60%-80% of the energy consumed in the CCUS process occurs in the capture and separation stages.

[0003] Related technologies involve in-situ (or direct) catalysis to convert low-concentration CO2 directly into high-value organic chemicals, enabling simultaneous CO2 capture and utilization. This technology has the potential to transform CCUS from a traditional multi-step approach to a one-step model, eliminating the separate steps of CO2 capture, separation, and transportation. This one-step approach significantly reduces overall process energy consumption and costs, increasing emission reduction potential and economic feasibility, and holds broad application prospects.

[0004] Studies have shown that the coexisting components in the actual anaerobic fermentation gas have no effect on the catalytic reaction activity of specific catalysts; however, these catalysts are not suitable for gases with CO2 concentrations below 15 vol%, which are usually present in various actual flue gases, such as coal-fired flue gas.

[0005] Flue gas from coal combustion typically contains approximately 7-15% CO₂. Studying the in-situ catalytic conversion of CO₂ in coal flue gas is a significant and innovative research direction. To this end, the development of novel catalytic materials is crucial. Summary of the Invention

[0006] The purpose of the present invention is to provide a metal and amine functionalized imidazole porous organic polymer that can catalyze the in situ conversion of low-concentration CO2, as well as a preparation method and application, to solve the problems raised in the above background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a porous organic polymer functionalized with metal and amine groups that can catalyze the in-situ conversion of low-concentration CO2, comprising the following steps:

[0008] Step 1: Synthesis of an active monomer: 1,2-bis(bromomethyl)benzene and 1-vinylimidazole were added to toluene and magnetically stirred at 100°C for 24 hours to obtain an active monomer;

[0009] Step 2: Preparation of POPs-n@Ag2O. First, the active monomer, DVB, amino units, and AIBN were dissolved in dimethyl sulfoxide for polymerization, heated to 100°C for 24 hours. POPs-n and Ag2O were then mixed in CH2Cl2 and stirred for 24 hours. The resulting precipitate was washed with ethyl acetate, H2O, and MeOH, and then vacuum dried to obtain POPs-n@Ag2O, where n = 1, 2, ..., 9.

[0010] Furthermore, in steps one and two, by optimizing the amino unit and cross-linking agent type, six different metal- and amino-functionalized imidazole-based porous organic polymers (POPs-n@Ag2O) were obtained. The six POPs-n@Ag2O structures are as follows:

[0011] .

[0012] The invention discloses an application of a metal and amine functionalized imidazole porous organic polymer in the treatment of CO2 conversion in coal-fired flue gas. When treating CO2 in coal-fired flue gas, POPs-n@Ag2O is used as a catalyst, and POPs-n@Ag2O is POP-6@Ag2O.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) When POPs-6@Ag2O is used as a catalyst, the bonded amino units in the catalyst can selectively adsorb CO2 in complex component gases, while the bonded imidazole groups and nanosilver can activate CO2 and reaction substrates. Under mild reaction conditions of room temperature and ambient pressure, the POP-6@Ag2O catalyst exhibits excellent catalytic efficiency in the in situ conversion of CO2 (8 vol%) in actual coal-fired flue gas.

[0015] (2) In SO2 (<428 mg / m 3 ) and NO2 (<221 mg / m 3 ) coexisted, the catalytic efficiency of POPs-6@Ag2O was not significantly affected. In addition, the catalytic performance of POP-6@Ag2O did not decrease significantly after six uses, and the microstructure remained intact. The structure-activity relationship of POP-6@Ag2O shows that the catalyst bonded with amino groups can significantly improve the adsorption capacity of CO2, thereby improving its catalytic efficiency.

[0016] (3) Using POP-6@Ag2O as a catalyst, CO2 in actual coal-fired flue gas can be converted into oxazolidine-2,4-dione in situ, with the highest yield reaching 92%.

[0017] (4) Without the need for a co-catalyst, POP-6@Ag2O can efficiently catalyze the in situ conversion of CO2 from actual coal-fired flue gas to oxazolidine-2,4-dione. Structure-activity relationship analysis of POP-6@Ag2O shows that increasing the nitrogen content in the catalyst improves its CO2 adsorption capacity. This finding provides guidance for the rational design and optimization of such catalysts, thereby enhancing their practical application in the in situ conversion of CO2 from coal-fired flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of POPs-n@Ag2O of the present invention;

[0019] Figure 2 Schematic diagram of the chemical formula of the CO2 conversion reaction of the present invention;

[0020] Figure 3 Comparison of the catalytic effects of the 15 vol% CO2 conversion reaction under different conditions of the present invention: (a) Effect of solvent type; (b) Effect of solvent usage; (c) Effect of temperature; (d) Catalytic effects of different catalysts; (e) Effect of catalyst components; (f) Effect of crosslinking agent and amine type.

[0021] Figure 4 Structure-activity relationship analysis of the catalyst of the present invention: (a) Pearson correlation coefficient; (b) P value test of Pearson correlation coefficient;

[0022] Figure 5 Schematic diagram of the structural characterization of POP-6@Ag2O of the present invention: (a) Fourier transform infrared spectra of POP-6@Ag2O and POP-6; (b) thermogravimetric analysis of POP-6@Ag2O; (c) 13 C NMR solid state nuclear magnetic spectrum;

[0023] Figure 6 Schematic diagram of the microstructure of the present invention: (a) SEM image of freshly prepared POP-6@Ag2O; (b) SEM image of POP-6@Ag2O recycled four times; (c) SEM image of POP-6@Ag2O recycled six times; (d) TEM image of freshly prepared POP-6@Ag2O; (e) TEM image of POP-6@Ag2O recycled four times; (f) TEM image of POP-6@Ag2O recycled six times.

[0024] Figure 7Schematic diagrams of the characterization of the catalytic mechanism of POP-6@Ag2O of the present invention: (a, b) CO2 and N2 selective adsorption capacity tests of POP-1@Ag2O and POP-6@Ag2O; (c) in situ Raman spectra of POP-6@Ag2O in CO2 and N2 atmospheres; (d) kinetic and leaching experiments under 15 vol% CO2 conditions;

[0025] Figure 8 Schematic diagram of the possible reaction mechanism of the conversion reaction of phenylpropynamide and CO2 in coal-fired flue gas catalyzed by POP-6@Ag2O of the present invention;

[0026] Figure 9 Schematic diagram of substrate expansion for the chemical reaction of the present invention;

[0027] Figure 10 Schematic diagram of the effect of gas components on yield: (a) the effect of coexisting components in the simulated exhaust gas on yield; (b) the effect of CO2 concentration on yield;

[0028] Figure 11 Schematic diagram of the synthesis reaction equation of phenylpropiolic acid of the present invention;

[0029] Figure 12 Schematic diagram of the synthesis reaction equation of phenylpropynamide of the present invention;

[0030] Figure 13 Schematic diagram of the control reaction equation of the present invention;

[0031] Figure 14 Schematic diagram of the amplified reaction equation of the present invention;

[0032] Figure 15 TEM image and element mapping of POP-6@Ag2O of the present invention;

[0033] Figure 16 This is the XPS graph of POP-6@Ag2O of the present invention;

[0034] Figure 17 This is a schematic diagram of the catalytic effect of the catalyst recycling of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Example:

[0037] See also Figure 1-17 , the present invention provides a technical solution: a metal and amine-functionalized imidazole-based porous organic polymer capable of catalyzing the in-situ conversion of low-concentration CO2, as well as a preparation method and application;

[0038] 1. Experimental part

[0039] 1.1 Materials and Reagents

[0040] Toluene (AR, ≥98%), acetonitrile (AR, ≥98%), tetrahydrofuran (THF, AR, ≥98%), methanol (AR, ≥98%), dimethyl sulfoxide (DMSO, AR, ≥98%), ethyl acetate (AR, ≥99.5%), petroleum ether (AR, ≥99.5%), 1,2-bis(bromomethyl)benzene (AR, ≥98%), 1-vinylimidazole (AR, ≥99%), 2,2'-azobis(2-methylpropionitrile) (AIBN, AR, ≥98%), divinylbenzene (DVB, ≥98 ...,2-bis(bromomethyl)benzene (AR, ≥98%), 1,2-bis(bromomethyl)benzene (AIBN, AR, ≥98%), 1,2-bis(bromomethyl)benzene (1,2-bis(bromomethyl)benzene) (1,2-bis(bromomethyl)benzene) (1,2-bis(bromomethyl)benzene) (1,2-bis(bromomethyl)benzene) (1,2-bis(bromomethyl)benzene) The following chemicals were used: TBC stabilizer), ethylene dimethacrylate (EGDMA, AR, ≥99%), silver oxide (AgO, AR, ≥99%), phenylpropiolic acid (AR, ≥98.1%), 4-dimethylaminopyridine (DMAP, AR, ≥99.83%), dicyclohexylcarbodiimide (DCC, AR, ≥98%), 4-methylbenzylamine (AR, ≥98%), and N-allylamine (AR, ≥99%). All of these chemicals are commercially available and require no additional purification. After synthesis, compounds 1a-1r were subsequently purified by flash silica gel column chromatography.

[0041] 1.2 Synthesis of S1

[0042] 1,2-Bis(bromomethyl)benzene (10 mmol) and 1-vinylimidazole (21 mmol) were added to 25 mL of toluene and magnetically stirred at 100°C for 24 h. The mixture was then cooled to room temperature (RT). The precipitate was collected by filtration, washed several times with ethyl acetate, and dried under vacuum to obtain monomer (S1).

[0043] 1.3 Preparation of POPs-n@Ag2O (metal and amine functionalized imidazole-based porous organic polymer)

[0044] First, S1 (0.5 mmol), DVB (1.0 mmol), amino units (2.0 mmol), and AIBN (0.060 g) were dissolved in 2.5 mL of dimethyl sulfoxide. The polymerization reaction was carried out in a Teflon high-pressure reaction tube and heated to 100°C for 24 h. Subsequently, POPs-n (200 mg) and Ag2O (50 mg) were mixed in CH2Cl2 and stirred for 24 h. The resulting precipitate was washed with ethyl acetate, H2O, and MeOH, and then dried in vacuum to obtain POPs-n@Ag2O. By using six different amino units and two different cross-linkers, six different metal- and amine-functionalized imidazole-based porous organic polymers POPs-n@Ag2O (n=3, 4, ...8) and three POPs-n@Ag2O for control experiments (n=1, 2, 9) were obtained. The structures of POPs-n@Ag2O are shown in Figure 2. Figure 1 .

[0045] 1.4. Cyclization reaction of CO2 with phenylpropionamide ( Figure 2 )

[0046] The reaction was typically performed in a 10 mL glass tube with a sidewall. Phenylpropargylamide (0.1 mmol) and POP-6@Ag2O (7 mg) were added to a reaction tube containing 0.5 mL of MeCN. A CO2 balloon (15 vol% CO2 / air, simulated flue gas or actual coal-fired flue gas) was used as the CO2 source. The reaction mixture was stirred for 7 hours under light-shielded conditions. Product yield was determined by liquid chromatography using phenylenediamine as an internal standard.

[0047] 1.5 Characterization

[0048] Acquired using a Bruker AVANCE-III 400 / 500 spectrometer 1 H / 13 C nuclear magnetic resonance (NMR) spectroscopy. 13C solid-state NMR spectra were obtained using a Bruker AVANCE NEO 400WB spectrometer. Functional groups were analyzed using a Thermo Scientific iN10 Fourier transform infrared spectroscopy (FT-IR) instrument. Composition and morphology were analyzed using a scanning electron microscope (Tesken MIRA.LMS, Czech Republic). BET surface area and pore size distribution were determined using a KUBO-X1000 instrument at 77 K. Transmission electron microscopy (TEM, JEOL JEM 2100) and energy-dispersive X-ray spectroscopy (EDX) were used to investigate the catalyst structure and elemental dispersion on the support. Surface elemental composition was analyzed using X-ray photoelectron spectroscopy (XPS, Thermo Scientific Nexsa). Thermogravimetric analysis was performed using a Rigaku Corporation thermogravimetric analyzer (TG, DTA8112). Thermal stability and decomposition temperature were determined using the thermogravimetric analyzer. The carbon, nitrogen, and hydrogen content of the materials was determined using an Elementar elemental analyzer. In addition, a Horiba HREvolution Raman spectrometer was used to observe the activation process of CO2.

[0049] 2. Example Results

[0050] 2.1 Optimization of reaction conditions

[0051] In this example, POPs-n@Ag2O was used as the catalyst to study the effect of 15 vol% CO2 / air on the N -(4-methylbenzyl)-3-phenylpropionylamine cyclization to generate ( Z )-5-benzyl-3-(4-methylbenzyl)oxazolidine-2,4-dione. Initially, different solvents were screened, and the results were as follows: Figure 3 shown.

[0052] like Figure 3 As shown in a, when tetrahydrofuran was used as the solvent, the yield was 16%; when 1,4-dioxane was used, the target product was not observed, which indicates that the non-polar solvent is not suitable for the reaction system. The target product was also not observed when the polar solvent MeOH was used. When the reaction was carried out in the non-polar solvents DMF, DMSO and MeCN, the yields increased rapidly to 45%, 60% and 95%, respectively. Polar aprotic solvents promote the solvation effect of Ag, thereby improving the activity of the catalyst. At the same time, high polarity solvents are also conducive to the adsorption of CO2 and increase the solubility of CO2. After optimizing the amount of MeCN, it was found that the catalytic effect was best when 0.5 mL MeCN was used ( Figure 3 b), which may be because reducing the amount of solvent can lead to a closer interaction between the reactants and the catalyst.

[0053] The effect of temperature on the reaction Figure 3 As shown in Figure c, the yield increased from 53% to 95% as the temperature increased from 5°C to room temperature, but then decreased with further temperature increases, reaching a low of 28% at 60°C. This trend may be due to the decreased catalytic efficiency with increasing temperature and the weakened interaction between the solvent and CO2. Therefore, the optimal conditions for this reaction are as follows: substrate (0.1 mmol), POP-6@Ag2O (7 mg), MeCN (0.5 mL), and reaction time of 7 h.

[0054] like Figure 3 As shown in Figure d, under the optimized optimal reaction conditions, the types of loaded metals were screened. Different Ag, Cu, and Pd salts were loaded in POP-6. The experimental results showed that the formation of the target product was monitored only in the reactions of the catalysts loaded with AgO and Ag2O, with yields of 30% and 95%, respectively. Without the addition of an additional organic base catalyst, metal salts such as CuSO4, Cu2O, Cu(OAc)2, Pd(OAc)2, and Pd(PPh3)4 did not show catalytic activity on the system. The influence mechanism of each component in the catalyst on the system was clarified through control experiments ( Figure 3 e) No product formation was observed using POP-6 and Ag2O as catalysts. When both POP-6 and Ag2O were added, the yield was only 54%, indicating that the Ag2O loading process is essential. No product formation was observed when both POP-9 and Ag2O were added, indicating that the imidazole group in the active monomer S1 plays a crucial role in CO2 activation.

[0055] Subsequently, this example explores the effects of various amino units and cross-linking agents on catalytic efficiency ( Figure 3 f). The results show that the catalytic efficiency of secondary amines is significantly higher than that of tertiary amines and primary amines. N POP-6@Ag2O, containing an amino group containing 1-allylaniline, exhibited the highest catalytic efficiency. This example speculates that the steric and coupling effects of the benzene ring of the amino unit in POP-6@Ag2O increase the electrophilicity of the amine and improve the catalyst's CO2 adsorption capacity. Furthermore, while POP-8@Ag2O also exhibited high CO2 adsorption capacity, its catalytic efficiency was lower, likely due to the greater energy required for the primary amine to release the adsorbed CO2. Therefore, this example conducted a series of CO2 isothermal adsorption tests on these catalysts, and the results demonstrated that their respective CO2 adsorption capacities and corresponding catalytic performance were consistent.

[0056] 2.2 Structure-activity relationship study of POP-6@Ag2O

[0057] In order to study the structure-activity relationship of the catalyst, this example uses the Pearson correlation coefficient to quantitatively evaluate the association between variables. The Pearson correlation coefficient is a widely used measurement method to evaluate the strength of the linear relationship between two variables, and its range is between -1 and 1. Positive values ​​indicate positive correlation, and negative values ​​indicate negative correlation. The closer the correlation coefficient is to 1 or -1, the stronger the linear relationship between the two variables. Figure 4 As shown in Figure 2, the N content and CO2 adsorption capacity of POP-6@Ag2O are positively correlated with the yield ( Figure 4 a). In addition, this example also evaluates the statistical significance of the research results by determining the p-value, which is a commonly used indicator in hypothesis testing to determine whether the results are statistically significant. Results with a p-value less than 0.05 are considered significant. Figure 4 As shown in b, there is a significant positive correlation between the nitrogen content and the yield and CO2 adsorption capacity. Therefore, the copolymerization of amino units in the catalyst is crucial to improving the CO2 adsorption capacity and catalytic efficiency.

[0058] 2.3 Characterization and analysis of POP-6@Ag2O

[0059] To understand the composition and structural characteristics of the catalyst, the synthesized polymer was characterized. The structure of S1 was determined by nuclear magnetic resonance spectroscopy. The Fourier transform infrared spectrum of POP-6@Ag2O ( Figure 5 a), 1640 cm -1 and 1445 cm -1 The peaks of NH are attributed to the vibration of C=N and CN bonds, confirming the existence of the imidazole ring. In addition, the stretching vibration and bending vibration of NH are at 3300-3500 cm -1 and 1599 cm -1 A characteristic peak appears. 718cm -1 The peak at indicates the bending vibration of -CH2-. 13 C NMR spectroscopy ( Figure 5 c) shows the signals of the aromatic ring related peaks in the range of 120-145 ppm. The peaks from the polyethylene group were observed in the range of 20-60 ppm in the spectrum, while C6 on the imidazole ring appeared at 138 ppm. Figure 5 As shown in (b), POP-6@Ag2O also exhibits good thermal stability and can maintain structural stability at 360°C.

[0060] Figure 6 The scanning electron microscope image in a shows that there are a large number of pores and interconnected channels in POP-6@Ag2O, forming a rich pore network structure. The specific surface area of ​​POP-6@Ag2O is 212m 2 / g, and a total pore volume of 0.197 cm 3 / g. The rich pore structure and large specific surface area contribute to the efficient accumulation of CO2 and mass transfer. TEM image ( Figure 6 d) shows that there are a large number of silver nanoparticles in POP-6@Ag2O, and their sizes are mainly around 50nm ( Figure 15 ). The EDX elemental spectrum of POP-6@Ag2O shows that the distribution of C, Br, N and Ag in the polymer is relatively uniform. In addition, the surface elements of POP-6@Ag2O were determined by XPS analysis, and the results showed that N, Ag, Br and other elements were present in the polymer components ( Figure 16 Due to the presence of N in both the imidazole ring and the amino structure, three characteristic peaks were observed at 400.5eV, 399.5eV, and 393.00eV. In addition, Br showed characteristic peaks at 74.6eV and 69.0eV, confirming the presence of Br in the polymer ( Figure 16 The two peaks with binding energies of 368.2 eV and 374.4 eV correspond to Ag3d 5 / 2 and Ag3d 3 / 2 .

[0061] 2.4 Reaction Mechanism

[0062] like Figure 7 As shown in ab, at 298K, POP-1@Ag2O and POP-6@Ag2O have good selective adsorption performance for CO2. In addition, the adsorption capacity of POP-6@Ag2O for CO2 is significantly higher than that of POP-1@Ag2O, which indicates that the addition of amino groups to the catalyst enhances the adsorption of CO2. In situ Raman spectroscopy shows that the imidazole groups in POP-6@Ag2O can activate CO2 ( Figure 7 c). When the atmosphere is switched from N2 to CO2, at 2211cm -1 The vibration signal corresponding to the antisymmetric stretching of CO2 adsorbed on N appears at Figure 13 As shown, the C source in the target product comes from the simulated exhaust gas containing CO2. The catalyst was filtered and separated after 2 hours of reaction ( Figure 7 d) Continuous monitoring confirmed that the reaction had stopped, proving that the catalytic system was heterogeneous catalysis.

[0063] Based on the above experimental results, this example proposes a reasonable reaction mechanism. Figure 8. First, CO2 is adsorbed in the pores of the polymer and then adsorbed onto the amino group. Subsequently, the CO2 adsorbed by the amino unit is transferred to the imidazole group for activation. At the same time, the free amino unit adsorbs new CO2 molecules from the atmosphere in the pores of the polymer. Then, the activated CO2 reacts with the Ag-activated alkyne by the N in the matrix. Ultimately, the intermediate is cyclized to generate the target product, and the catalyst is regenerated for subsequent cycles.

[0064] 2.5. Feasibility of the reaction for CO2 conversion in coal-fired flue gas

[0065] like Figure 9 As shown (using 15vol% CO2 / air as the CO2 source or actual coal-fired flue gas as the CO2 source);

[0066] Under optimized reaction conditions of low-concentration CO₂ (15 vol% CO₂ / air), POP-6@Ag₂O was evaluated for the cyclization of a series of phenylpropynamides. The results demonstrated that all substrates were efficiently converted to the target products (2a-2r). However, the yields decreased slightly when the substituents were strongly electron-withdrawing or exhibited significant steric hindrance.

[0067] In order to comprehensively study the potential application of this catalytic system in actual flue gas, this example studies the possible effects of coexisting SO2 and NO2 on the catalyst performance and intrinsic reactivity ( Figure 10 a and Table 1). SO2 concentration ranged from 71 mg / m 3 Increased to 428 mg / m 3 , NO2 concentration from 51 mg / m 3 Increased to 221 mg / m 3 The catalytic efficiency of POP-6@Ag2O remained stable, which verified the feasibility of applying the catalytic system in coal-fired flue gas. In addition, under the condition of low CO2 concentration of 10 vol%, the catalytic efficiency was also very high, with a product yield of up to 91% ( Figure 10 b).

[0068] Table 1 Coexisting components of simulated exhaust gas

[0069]

[0070] In order to further study the potential of in-situ catalytic conversion of actual coal-fired flue gas, this example collected flue gas emitted by a coal-fired boiler in a power plant. Figure 9As shown in the results, POP-6@Ag2O exhibited remarkable efficiency in catalyzing the cyclization of phenylpropargylamide with low concentrations of CO2 (8 vol%) in actual coal-fired flue gas. It is worth noting that the presence of SO2, NO2, and volatile organic compounds (VOCs) in actual coal-fired flue gas did not have any significant effect on the cyclization of CO2. In addition, when the reaction was scaled up to the gram level, POP-6@Ag2O was still able to catalyze the conversion of CO2 to the target product with a yield of up to 90%, highlighting its potential for industrial applications ( Figure 14 The catalyst recycling experiment showed that the catalytic efficiency did not decrease significantly after the catalyst was used six times ( Figure 17 ), the catalyst structure has no obvious change ( Figure 6 ).

[0071] In summary, this example developed a novel imidazolylamino-functionalized nanosilver porous organic polymer heterogeneous catalyst. Without the need for a cocatalyst, POP-6@Ag2O efficiently catalyzes the in situ conversion of CO2 from real coal-fired flue gas to oxazolidine-2,4-dione. Structure-activity relationship analysis of POP-6@Ag2O indicates that increasing the nitrogen content of the catalyst improves its CO2 adsorption capacity. This finding provides guidance for the rational design and optimization of such catalysts, thereby enhancing their practical application in the in situ conversion of CO2 from coal-fired flue gas.

[0072] Synthesis of substrates: Synthesis of phenylpropiolic acid compounds

[0073] Aryl iodide (1.1 equiv., 11 mmol) and Pd(PPh3)4 (5 mol%, 0.5 mmol) were added to a 50 mL vial, and the N2 protection was withdrawn and replaced three times. DBU (2.4 equiv., 24 mmol) was then dissolved in DMSO (10 mL) and transferred to the vial. To this solution was added 10 mL of a DMSO solution containing propiolic acid (10 mmol). The mixture was stirred at room temperature for 12 h. After completion of the reaction, the reaction mixture was quenched with saturated aqueous NaHCO3 and extracted with ethyl acetate. The organic layer was separated. The aqueous phase was adjusted to pH 2 with 2 M HCl and extracted three times with CHCl2. The organic layers were combined. The organic layer was dried over anhydrous Na2SO4 and the solvent was removed by rotary evaporation. The resulting phenylpropiolic acid derivatives were used directly in subsequent reactions without further column chromatography purification.

[0074] Synthesis of Propylene Amides: A phenylpropiolic acid compound (10 mmol, 1.0 equiv.) was weighed into a side-necked flask. After replacing the N2 protection three times, CH2Cl2 (10 mL) was added at -20°C to dissolve the phenylpropiolic acid compound. DCC (11 mmol, 1.1 equiv.) and DMAP (1 mmol, 0.1 equiv.) were then dissolved in CH2Cl2 (20 mL) and slowly added to the side-necked flask. The reaction was stirred at -20°C for 10 min, and the amine compound was dissolved in CH2Cl2 and slowly added to the reaction flask. After completion of the reaction, the mixture was extracted three times with brine and ethyl acetate (20 mL). The organic layers were combined and dried over anhydrous Na2SO4, filtered, and concentrated by rotary evaporation. The crude product was isolated and purified by silica gel column chromatography to yield phenylpropiolic acid amides.

[0075] ( Z Quantification of 5-benzyl-3-(4-methylbenzyl)oxazolidine-2,4-dione: The reaction mixture was accurately quantitatively analyzed using a Thermo Fisher Scientific high-performance liquid chromatography system (DIONEX Ultimate 3000 UHPLC) with phenylenediamine as the internal standard. A C18 column (4.6 × 250 nm, 5 μm 120 Å) was used, and a fluorescence detector was used at a wavelength of 281 nm. The mobile phase consisted of a mixture of acetonitrile and water (75:25) at a flow rate of 1 mL / min.

[0076] Controlled test methods

[0077] A control experiment was conducted under the optimized conditions. The 15 vol% CO₂ gas used in the model reaction was replaced with N₂. The results showed that no target product was detected under the N₂ atmosphere, confirming that the carbon source was CO₂.

[0078] Experimental methods for amplifying reactions

[0079] Based on the CO2 in coal-fired flue gas and N -(4-methylbenzyl)-3-phenylpropionamide (1b) gram-scale reaction. After the relevant reagents of the model reaction were amplified 35 times, the experiment was carried out under the optimized optimal reaction conditions. N4-(4-Methylbenzyl)-3-phenylpropionamide (3.4 mmol, 872 mg) and POP-6@Ag2O (255 mg) were placed in a 100 mL tube. The reaction system was then purged with coal flue gas three times, and MeCN (10 mL) was added. The reaction was incubated at room temperature in the dark for 10 h. After completion of the reaction, the product was purified by column chromatography, concentrated by rotary evaporation, and dried under vacuum.

[0080] Cyclic experiment method

[0081] Under the optimal reaction conditions determined by the model reaction, POP-6@Ag2O catalyzed the reaction of coal-fired flue gas with N After the reaction of 4-(4-methylbenzyl)-3-phenylpropionamide, the catalyst was collected by filtration. The collected catalyst was first washed with 0.5 N nitric acid, then alkalized with 0.5 N NaOH aqueous solution, and washed with ultrapure water until the catalyst was neutral. The vacuum-dried catalyst was reloaded with Ag2O and used as the catalyst for the next cycle experiment.

[0082] Monomer and product 1 H, 13 The C NMR spectrum data are as follows: corresponding to monomer S1 and Figure 9 Middle 2a-2r;

[0083] 3,3'-(1,2-phenylenebis(methylene))bis(1-vinyl-1H-imidazol-3-ium)→3,3-(1,2-phenylenebis(methylene)))bis(1-vinyl-1H-imidazol-3-ium),(S1). 1 HNMR (400 MHz, DMSO- d 6)δ9.67(d, J =1.7Hz,2H),8.32(t, J =1.9Hz,2H),7.95(t, J =1.9Hz,2H),7.50(dd, J =5.7,3.4Hz,2H),7.43(dd, J =5.7,3.5Hz,2H),7.34(dd, J =15.6,8.8Hz,2H),6.02(dd, J =15.6,2.4Hz,2H),5.74(s,4H),5.43(dd, J =8.7,2.4Hz,2H). 13 CNMR (100 MHz, DMSO- d6) δ135.8,132.6,130.2,129.9,128.9,123.5,119.4,109.0,49.5.

[0084] ( Z )-3-benzyl-5-benzylideneoxazolidine-2,4-dione,→(Z)-3-benzyl-5-benzylideneoxazolidine-2,4-dione; (2a). White solid, 92% yield (25.7 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.76-7.72(m,2H),7.47-7.40(m,5H),7.39-7.32(m,3H),6.78(s,1H),4.80(s,2H). 13 CNMR (100MHz, Chloroform- d )δ162.2,152.2,137.7,134.6,131.3,130.8,130.7,129.2,129.1,129.0,128.7,113.9,44.0.

[0085] ( Z )-5-benzylidene-3-(4-methylbenzyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(4-methylbenzyl)oxazolidine-2,4-dione, (2b). White solid, 93% yield (27.3 mg). 1 HNMR (400 MHz, DMSO- d 6)δ7.83-7.79(m,2H),7.53-7.44(m,3H),7.25(d, J =8.0Hz,2H),7.16(d, J =7.9Hz,2H),6.91(s,1H),4.67(s,2H),2.28(s,3H). 13 CNMR (100 MHz, DMSO- d 6) δ162.1,152.1,138.1,137.2,132.7,131.2,130.2,130.1,129.1,129.1,127.7,111.7,42.9,20.7.

[0086] ( Z)-5-benzylidene-3-(4-methoxybenzyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(4-methoxybenzyl)oxazolidine-2,4-dione, (2c). White solid, 94% yield (29.1 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.76-7.71(m,2H),7.44-7.37(m,5H),6.87(d, J =8.7Hz,2H),6.76(s,1H),4.73(s,2H),3.79(s,3H). 13 CNMR (100MHz, Chloroform- d )δ162.2,159.9,152.2,137.7,131.2,130.8,130.6,130.6,129.1,126.8,114.4,113.8,55.4,43.5.

[0087] ( Z )-5-benzylidene-3-(4-(tert-butyl)benzyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(4-(tert-butyl)benzyl)oxazolidine-2,4-dione, (2d). White solid, 93% yield (31.2 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.76-7.72(m,2H),7.43-7.35(m,7H),6.77(s,1H),4.77(s,2H),1.30(s,9H). 13 CNMR (100MHz, Chloroform- d )δ162.2,152.2,151.8,137.7,131.6,131.2,130.9,130.6,129.2,128.8,126.0,113.8,43.6,34.7,31.4.

[0088] ( Z )-5-benzylidene-3-(2-methylbenzyl)oxazolidine-2,4-dione→

[0089] (Z)-5-Benzylidene-3-(2-methylbenzyl)oxazolidine-2,4-dione, (2e), White solid, 85% yield (24.9 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.78-7.73(m,2H),7.43(dd, J =5.9,1.7Hz,3H),7.36(dd, J =7.7,1.9Hz,1H),7.21(tt, J =6.0,3.4Hz,3H),6.79(s,1H),4.84(s,2H),2.48(s,3H). 13 CNMR (100MHz, Chloroform- d )δ162.3,152.2,137.6,136.6,132.4,131.3,130.9,130.8,130.7,129.2,129.2,128.6,126.5,113.9,41.5,19.6.

[0090] ( Z )-5-benzylidene-3-(4-(trifluoromethyl)benzyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(4-(trifluoromethyl)benzyl)oxazolidine-2,4-dione, (2f). White solid, 89% yield (30.9 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.81-7.71(m,2H),7.66-7.53(m,4H),7.49-7.39(m,3H),6.81(s,1H),4.85(s,2H). 13 CNMR (100MHz, Chloroform- d )δ162.0,152.0,138.3,137.4,131.4,130.9,130.7,129.3,129.2,126.2,126.1,126.1,126.0,114.5,43.4.

[0091] ( Z)-5-benzylidene-3-(4-bromobenzyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(4-bromobenzyl)oxazolidine-2,4-dione, (2 g). White solid, 86% yield (30.8 mg). 1 HNMR (500 MHz, Chloroform- d )δ7.77-7.71(m,2H),7.49(d, J =8.3Hz,2H),7.46-7.41(m,3H),7.33(d, J =8.3Hz,2H),6.79(s,1H),4.75(s,2H). 13 CNMR (125MHz, Chloroform- d )δ162.1,152.0,137.5,133.5,132.3,131.3,130.8,130.8,130.7,129.2,123.0,114.3,43.3.

[0092] ( Z )-5-benzylidene-3-(thiophen-2-ylmethyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(thiophen-2-ylmethyl)oxazolidine-2,4-dione, (2h). White solid, 82% yield (23.4 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.76-7.72(m,2H),7.43(dd, J =5.5,1.9Hz,3H),7.28(dd, J =5.1,1.2Hz,1H),7.20(dd, J =3.6,1.1Hz,1H),6.98(dd, J =5.2,3.5Hz,1H),6.79(s,1H),4.98(s,2H). 13 CNMR (100MHz, Chloroform- d )δ161.7,151.7,137.5,135.7,131.3,130.7,129.2,128.9,127.3,126.9,114.2,38.0.

[0093] ( Z)-5-benzylidene-3-(furan-2-ylmethyl)oxazolidine-2,4-dione→(Z)-5-benzylidene-3-(furan-2-ylmethyl)oxazolidine-2,4-dione, (2i). White solid, 85% yield (22.9 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.74(dd, J =7.2,2.7Hz,2H),7.42(d, J =5.6Hz,4H),6.79(s,1H),6.45(d, J =3.2Hz,1H),6.34(dd, J =3.2,1.8Hz,1H),4.82(s,2H). 13 CNMR (100MHz, Chloroform- d )δ161.6,151.7,147.3,143.3,137.5,131.3,130.7,130.7,129.2,114.1,110.8,110.1,36.5.

[0094] Ethyl-( Z )-2-(5-benzylidene-2,4-dioxooxazolidin-3-yl)acetate→ethyl-(Z)-2-(5-benzylidene-2,4-dioxooxazolidin-3-yl)acetate, (2j). White solid, 82% yield (22.6 mg). 1 HNMR (500 MHz, Chloroform- d )δ7.79-7.76(m,2H),7.47-7.43(m,3H),6.84(s,1H),4.39(s,2H),4.27(q, J =7.1Hz,2H),1.31(t, J =7.1Hz,3H). 13 CNMR (125MHz, Chloroform- d )δ165.9,161.7,151.7,137.5,131.4,130.9,130.7,129.2,114.7,62.6,40.7,14.2.

[0095] ( Z)-5-benzylidene-3-phenethyloxazolidine-2,4-dione→(Z)-5-benzylidene-3-phenethyloxazolidine-2,4-dione, (2k). White solid, 98% yield (28.7 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.79-7.70(m,2H),7.47-7.40(m,3H),7.35-7.28(m,2H),7.26-7.20(m,3H),6.74(s,1H),3.93-3.86(m,2H),3.03(dd, J =8.6,6.7Hz,2H). 13 CNMR (100MHz, Chloroform- d )δ162.3,152.2,137.6,137.0,131.3,130.8,130.6,129.2,128.9,128.9,127.2,113.6,41.5,33.7.

[0096] ( Z )-3-(2-(benzo[d][1,3]dioxol-5-yl)ethyl)-5-benzylideneoxazolidine-2,4-dione→(Z)-3-(2-(Benzo[d][1,3]dioxol-5-yl)ethyl)-5-benzylideneoxazolidine-2,4-dione, (2l). White solid, 98% yield (33.1 mg). 1 HNMR (500 MHz, Chloroform- d )δ7.78-7.73(m,2H),7.43(d, J =6.8Hz,3H),6.77-6.71(m,3H),6.67(dd, J =8.0,1.6Hz,1H),5.93(s,2H),3.87-3.82(m,2H),2.95(t, J =7.6Hz,2H). 13 CNMR (125MHz, Chloroform- d )δ162.3,152.2,148.0,146.7,137.5,131.3,130.8,130.7,130.7,129.2,122.0,113.7,109.3,108.6,101.1,41.7,33.4.

[0097] ( Z )-5-benzylidene-3-(1-(2,6-dimethylphenoxy)propan-2-yl)oxazolidine-2,4-dione→(Z)-5-Benzylidene-3-(1-(2,6-dimethylphenoxy)propan-2-yl)oxazolidine-2,4-dione, (2 m). White solid, 67% yield (23.5 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.80-7.76(m,2H),7.48-7.42(m,3H),6.98(d, J =7.4Hz,2H),6.91(dd, J =8.4,6.4Hz,1H),6.79(s,1H),4.81-4.72(m,1H),4.37(t, J =9.7Hz,1H),3.84(dd, J =9.7,5.1Hz,1H),2.24(s,6H),1.55(d, J =7.1Hz,3H). 13 CNMR (100MHz, Chloroform- d )δ162.7,155.0,151.8,137.4,131.3,130.9,130.8,130.6,129.2,129.1,124.3,113.5,70.6,49.4,16.3,14.4.

[0098] ( Z )-3-benzyl-5-(4-bromobenzylidene)oxazolidine-2,4-dione→(Z)-3-benzyl-5-(4-bromobenzaldehyde)oxazolidine-2,4-dione, (2n). White solid, 83% yield (29.7 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.57(q, J =8.7Hz,4H),7.47-7.41(m,2H),7.40-7.31(m,3H),6.70(s,1H),4.79(s,2H). 13 CNMR (100MHz, Chloroform- d)δ162.0,151.900,138.0,134.4,132.5,132.5,129.7,129.1,129.0,128.8,125.2,112.5,44.1.

[0099] ( Z )-3-benzyl-5-(3-methoxybenzylidene)oxazolidine-2,4-dione→(Z)-3-benzyl-5-(3-methoxybenzylidene)oxazolidine-2,4-dione, (2o). White solid, 90% yield (27.8 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.64(d, J =8.0Hz,2H),7.48-7.44(m,2H),7.38-7.32(m,3H),7.23(d, J =7.9Hz,2H),6.76(s,1H),4.79(s,2H),2.39(s,3H). 13 CNMR (100MHz, Chloroform- d )δ162.3,152.2,141.4,137.0,134.6,131.3,129.9,129.0,129.0,128.7,128.0,114.1,43.9,21.7.

[0100] (Z)-3-benzyl-5-(4-methylbenzylidene)oxazolidine-2,4-dione→(Z)-3-Benzyl-5-(4-methylbenzylidene)oxazolidine-2,4-dione, (2p). White solid, 92% yield (27.0 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.64(d, J =7.9Hz,2H),7.48-7.43(m,2H),7.40-7.31(m,3H),7.23(d, J =7.9Hz,2H),6.75(s,1H),4.79(s,2H),2.39(s,3H). 13 CNMR (100MHz, Chloroform- d)δ162.2,152.2,141.3,137.0,134.6,131.3,129.9,129.0,129.0,128.7,128.0,114.1,43.9,21.7.

[0101] ( Z )-3-benzyl-5-(4-(tert-butyl)benzylidene)oxazolidine-2,4-dione→(Z)-3-benzyl-5-(4-(tert-butyl)benzylidene)oxazolidine-2,4-dione, (2q). White solid, 91% yield (30.5 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.69(d, J =8.5Hz,2H),7.48-7.43(m,4H),7.39-7.32(m,3H),6.77(s,1H),4.79(s,2H),1.34(s,9H). 13 CNMR (100MHz, Chloroform- d )δ162.3,154.3,152.2,137.2,134.6,131.1,129.0,129.0,128.7,128.0,126.2,114.0,43.9,35.1,31.2.

[0102] ( Z )-5-(4-acetylbenzylidene)-3-benzyloxazolidine-2,4-dione→(Z)-5-(4-acetylbenzylidene)-3-benzyloxazolidine-2,4-dione, (2r). White solid, 92% yield (29.6 mg). 1 HNMR (400 MHz, Chloroform- d )δ7.98(d, J =8.5Hz,2H),7.81(d, J =8.5Hz,2H),7.47-7.42(m,2H),7.38-7.32(m,3H),6.77(s,1H),4.80(s,2H),2.62(s,3H). 13 CNMR (100MHz, Chloroform- d)δ197.4,161.8,151.8,138.9,137.8,135.1,134.3,131.2,129.1,129.0,128.9,128.8,112.1,44.1,26.8.

[0103] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A metal and amine functionalized imidazole porous organic polymer capable of catalyzing the in situ conversion of low-concentration CO2, characterized in that: Metal and amine groups are simultaneously functionalized into imidazole-based porous organic polymers, and the chemical structure is as follows: 。 2. A method for preparing a porous organic polymer with metal and amine functionalized imidazole groups capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 1, characterized in that: The following steps are involved: Step 1: Synthesis of an active monomer: 1,2-bis(bromomethyl)benzene and 1-vinylimidazole were added to toluene and magnetically stirred at 100°C for 24 hours to obtain an active monomer; Step 2: Preparation of POPs-n@Ag2O. First, the active monomer, DVB, amino units, and AIBN were dissolved in dimethyl sulfoxide for polymerization, heated to 100°C for 24 hours. POPs-n and Ag2O were then mixed in CH2Cl2 and stirred for 24 hours. The resulting precipitate was washed with ethyl acetate, H2O, and MeOH, and then vacuum-dried to obtain POPs-n@Ag2O, where n = 3, 4, 5, 6, 7, or 8.

3. The method for preparing a porous organic polymer with metal and amine functionalized imidazole groups capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 2, characterized in that: In steps one and two, by optimizing the amino unit and cross-linker type, six different metal- and amino-functionalized imidazole-based porous organic polymers (POPs-n@Ag2O) were obtained. The six POPs-n@Ag2O structures are as follows: 。 4. The method for preparing a porous organic polymer with metal and amine functionalized imidazole groups capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 2, characterized in that: In step 1, the amount of toluene is 25 mL, the amount of 1,2-bis(bromomethyl)benzene is 10 mmol, and the amount of 1-vinylimidazole is 21 mmol.

5. The method for preparing a porous organic polymer with metal and amine functionalized imidazole groups capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 2, characterized in that: In step 2, the mixture is cooled to room temperature after stirring, and the precipitate is collected by filtration, washed several times with ethyl acetate, and dried in vacuo.

6. The method for preparing a porous organic polymer with metal and amine functionalized imidazole groups capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 2, characterized in that: In step 2, the active monomer is 0.5 mmol, DVB is 1.0 mmol, the amino unit is 2.0 mmol, AIBN is 0.060 g, dimethyl sulfoxide is 2.5 mL, POPs-n is 200 mg, and Ag2O is 50 mg.

7. Use of the organic polymer according to claim 1 in treating CO2 conversion in coal-fired flue gas.

8. The use of a metal- and amine-functionalized imidazole-based porous organic polymer capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 7 in treating CO2 conversion in coal-fired flue gas, characterized in that: When treating CO2 in coal-fired flue gas, POPs-n@Ag2O is used as a catalyst.

9. Use of a metal- and amine-functionalized imidazole-based porous organic polymer capable of catalyzing the in-situ conversion of low-concentration CO2 according to claim 8 in treating CO2 conversion in coal-fired flue gas, characterized in that: POPs-n@Ag2O is POP-6@Ag2O.

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