Precoordinated silver-nitrogen heterocyclic carbene polymer catalyst and its preparation method and application

Abstract

The present invention discloses a pre-coordinated nano silver-azacyclic carbene polymer catalyst, its preparation method and application. The preparation method includes S1, the preparation of an azacyclic carbene precursor (NL-3); S2, the preparation of an azacyclic carbene-silver complex (Ag@NL-3); S3, the preparation of a nano silver-azacyclic carbene polymer (Ag@POP-NL-3): uniformly dispersing the monomer Ag@NL-3, divinylbenzene and azobisisobutyronitrile in dimethyl sulfoxide or N,N-dimethylformamide; under a nitrogen atmosphere, polymerizing the uniformly mixed turbid liquid in a Teflon high-pressure reaction tube, washing the obtained polymer with ethyl acetate and methanol, and then drying it under vacuum to obtain the nano silver-azacyclic carbene polymer. This pre-coordinated nano silver-azacyclic carbene polymer avoids the use of stabilizers, minimizes the particle size of the metal, improves the surface reaction activity of the catalyst, improves the stability, and can efficiently catalyze the reaction of low-concentration CO2 with alkynols to generate cyclic carbonates.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and relates to the field of carbon dioxide fixation. Specifically, it is a pre-coordinated nano silver-azacyclic carbene polymer catalyst and its preparation method and application. Background Art

[0002] Using chemical carbon fixation technology to convert carbon dioxide into high-value chemicals such as methanol, methane, oxazolidinone, and cyclic carbonates is an effective means to realize the resource utilization of carbon dioxide. However, due to the very difficult activation of highly stable carbon dioxide linear molecules, many early carbon dioxide conversion reactions required harsh reaction conditions such as high temperature and high pressure. With a series of new catalytic materials being applied to the chemical conversion of carbon dioxide, many current reactions involving carbon dioxide can be carried out under relatively mild reaction conditions. The capture and conversion of low-concentration carbon dioxide have been realized using some efficient heterogeneous catalysts.

[0003] However, most current studies use a mixed gas of carbon dioxide and nitrogen, and there are few reports on the resource utilization of low-concentration carbon dioxide in actual waste gas. Therefore, developing a catalytic material for efficiently converting carbon dioxide in waste gas is crucial for the fixation of carbon dioxide emitted in actual production.

[0004] In recent years, N-heterocyclic carbene (NHC) metal complexes have been widely used to catalyze the conversion of CO2 into high-value chemicals such as formic acid and carbon monoxide. NHC has a six-electron valence layer ring structure with at least one nitrogen (N) atom and one divalent carbon (C) atom, which can form bonds with specific metals to form corresponding metal complexes. Nitrogen-containing heterocyclic organic polymers retain the relevant properties of NHC, and have the functions of modifying metals, enriching substrates, and realizing the recycling of catalysts. After introducing nitrogen-containing groups into the polymer backbone, the metal centers have better coordination sites and can be well dispersed in the backbone, and their catalytic activity is significantly improved. In addition, it has also been found that such porous materials containing rich active N sites have excellent carbon dioxide adsorption performance. Therefore, integrating functional sites such as metal centers and active N into porous materials through pre-coordination is an ideal strategy for capturing and converting CO2 in industrial waste gas.

[0005] Therefore, in this work, a new type of nano silver-azacyclic carbene polymer (Ag@POP-NL-3) was synthesized by a pre-coordination method. It was found through research that when loading metals on the nitrogen-doped carbene polymer by the traditional impregnation method, most of the metals can only be distributed on the surface of the material and are prone to agglomeration. Therefore, in order to obtain smaller silver nanoparticles, many stabilizers and surfactants often need to be added, which greatly increases the synthesis cost, and the synthesis steps are cumbersome and the operation difficulty is large. Summary of the Invention

[0006] The object of the present invention is to provide a pre-coordinated nano silver-azacyclic carbene polymer catalyst, its preparation method and application in view of the deficiencies of the prior art. This pre-coordinated nano silver-azacyclic carbene polymer avoids the use of stabilizers, minimizes the particle size of the metal, improves the surface reactivity of the catalyst, enhances the stability, and can efficiently catalyze the reaction of low-concentration CO2 with alkynols to produce cyclic carbonates.

[0007] The technical solution for achieving the object of the present invention is as follows:

[0008] A pre-coordinated nano silver-azacyclic carbene polymer catalyst, and the preparation route is as follows:

[0009]

[0010] * represents a repeating backbone extending outwards.

[0011] The preferred technical solution of the present invention, a preparation method of a pre-coordinated nano silver-azacyclic carbene polymer catalyst, includes the following steps:

[0012] S1, Preparation of azacyclic carbene precursor (NL-3):

[0013] Add 1,3,5-tris(bromomethyl)benzene and 1-vinylimidazole into toluene or acetonitrile, magnetically stir at 70 °C - 110 °C for 24 - 48 h, and then cool to room temperature; filter, and then wash the precipitate with ethyl acetate multiple times, collect the precipitate, and vacuum dry to obtain the azacyclic carbene precursor;

[0014] S2, Preparation of azacyclic carbene-silver complex (Ag@NL-3):

[0015] Add silver nitrate into methanol, and ultrasonically dissolve it in the dark until completely dissolved; NL-3 is dissolved in methanol under a nitrogen atmosphere; drop the silver nitrate methanol solution into the NL-3 methanol solution, and stir in the dark for 12 - 24 h; after the precipitate is collected by centrifugation, wash it with methanol, and vacuum dry to obtain the azacyclic carbene-silver complex;

[0016] S3, Preparation of nano silver-azacyclic carbene polymer (Ag@POP-NL-3):

[0017] Uniformly disperse the monomer Ag@NL-3, divinylbenzene (DVB) and azobisisobutyronitrile (AIBN) in dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF); under a nitrogen atmosphere, polymerize the uniformly mixed turbid liquid in a Teflon high-pressure reaction tube, wash the obtained polymer with ethyl acetate and methanol, and then dry it under vacuum to obtain the nano silver-azacyclic carbene polymer.

[0018] As a further preferred technical solution of the present invention, in the preparation method:

[0019] In S1, the volume molar ratio of toluene or acetonitrile, 1,3,5-tris(bromomethyl)benzene and 1-vinylimidazole is 25 mL: 5.0 mmol: 15.5 mmol.

[0020] In S2, the molar volume ratio of silver nitrate to methanol is 0.5 mmol: 20 mL; the molar volume ratio of NL-3 to methanol is 1 mmol: 10 mL.

[0021] In S3, the mass volume ratio of Ag@NL-3, DVB, AIBN and DMSO is 0.20 g: 0.40 g: 0.060 g: 2.5 mL.

[0022] In S3, the turbid liquid is polymerized at 100 - 120 °C for 24 - 36 h in a Teflon high-pressure reaction tube.

[0023] As a specific application of the Ag@POP-NL-3 polymer of the present invention, in an atmosphere of a mixture of carbon dioxide and air with a carbon dioxide content of 30%, alkynol and Ag@POP-NL-3 are added to acetonitrile and mixed. Using Ag@POP-NL-3 as a catalyst, stir at room temperature for at least 12 h. After the reaction, the catalyst is recovered and reused.

[0024] As a preferred technical solution of a specific application of the present invention:

[0025] The molar mass volume ratio of alkynol, Ag@POP-NL-3 and acetonitrile is 1.0 mmol: 80 mg: 2 mL.

[0026] After the reaction, the catalyst Ag@POP-NL-3 is separated by filtration. The solvent in the filtrate is evaporated under vacuum to obtain a crude product, and the crude product is further purified by a silica gel chromatography column to obtain a high-purity cyclic carbonate.

[0027] Furthermore, Ag@POP-NL-3 is used as a catalyst to fix carbon dioxide in the waste gas of a lime kiln, and the waste gas of the lime kiln can be used instead of the mixture of carbon dioxide and air.

[0028] Compared with the prior art, the beneficial effects or advantages of the present invention are as follows:

[0029] 1. The pre-coordination method avoids the use of stabilizers, enables the metal to coordinate with the active sites in the monomer in a homogeneous system before polymerization, avoids the agglomeration of the metal during the subsequent polymerization process, and minimizes the particle size of the metal.

[0030] 2. The reduction of the size of the nano-silver particles can directly affect the atomic arrangement of the material, adjust the binding energy of the intermediate state and the transition state on the catalyst surface, and improve the surface reaction activity of the catalyst.

[0031] 3. Ag is uniformly distributed inside the polymer, effectively avoiding the direct exposure of the catalyst metal to the external environment and improving its stability;

[0032] 4. Since the polymer contains abundant N sites, it has both good CO2 adsorption capacity and activation ability. The results show that the synthesized Ag@POP-NL-3 can effectively catalyze the reaction of carbon dioxide with alkynol compounds, and efficiently catalyze the reaction of low-concentration CO2 in lime kiln waste gas with alkynol to produce cyclic carbonates. Description of the Drawings

[0033] Figure 1 It is the scanning electron microscope image of Ag@POP-NL-3 of the present invention;

[0034] Figure 2 It is the N2 adsorption-desorption isotherm and pore size distribution diagram in the physical and chemical structure analysis diagram of Ag@POP-NL-3 of the present invention;

[0035] Figure 3 It is the thermogravimetric curve diagram of Ag@POP-NL-3 in the physical and chemical structure analysis diagram of Ag@POP-NL-3 of the present invention;

[0036] Figure 4 It is the Fourier transform infrared spectrum diagram in the physical and chemical structure analysis diagram of Ag@POP-NL-3 of the present invention;

[0037] Figure 5 It is the X-ray photoelectron spectrum in the physical and chemical structure analysis diagram of Ag@POP-NL-3 of the present invention;

[0038] Figure 6 、 Figure 7 It is the transmission electron microscope (TEM) image of the material with AgNO3 directly loaded on POP-NL-3;

[0039] Figure 8 、 Figure 9 It is the transmission electron microscope (TEM) image of Ag@POP-NL-3 of the present invention;

[0040] Figure 10 It is the CO2 adsorption isotherm diagram of the CO2 adsorption performance test of Ag@POP-NL-3;

[0041] Figure 11 It is for the CO2 adsorption performance test of Ag@POP-NL-3, the 1 1H NMR spectrum diagram of the solution of 2-methyl-3-butyn-2-ol (using deuterated chloroform as the solvent) before and after the adsorption of Ag@POP-NL-3;

[0042] Figure 12 For use 13Products obtained after catalytic experiments using C-labeled carbon dioxide as a substrate 13 C NMR spectrum;

[0043] Figure 13 It is a possible mechanism diagram for the carboxylation cyclization of low-concentration CO2 and alkynol catalyzed by Ag@POP-NL-3. Specific implementation manners

[0044] The content of the present invention will be further described below in conjunction with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0045] Example 1:

[0046] A preparation method of a pre-coordinated nano silver-azacyclic carbene polymer catalyst includes the following steps:

[0047] S1, Preparation of azacyclic carbene precursor (NL-3):

[0048] Add 1,3,5-tris(bromomethyl)benzene (5.0 mmol) and 1-vinylimidazole (15.5 mmol) to 25 mL of toluene, stir magnetically at 90 °C for 48 h, and then cool to room temperature; after filtration, wash the precipitate with ethyl acetate multiple times, collect the precipitate, and dry it under vacuum to obtain the azacyclic carbene precursor;

[0049] S2, Preparation of azacyclic carbene-silver complex (Ag@NL-3):

[0050] Add 0.5 mmol of silver nitrate to 20 mL of methanol, and ultrasonicate for 30 min in the dark; dissolve 1 mmol of NL-3 in 20 mL of methanol under a nitrogen atmosphere; drop the silver nitrate methanol solution into the NL-3 methanol solution, and stir in the dark for 24 h; after the precipitate is collected by centrifugation, wash it with methanol and dry it under vacuum to obtain the azacyclic carbene-silver complex;

[0051] S3, Preparation of nano silver-azacyclic carbene polymer (Ag@POP-NL-3):

[0052] Dissolve 0.20 g of monomer Ag@NL-3, 0.40 g of divinylbenzene (DVB), and 0.060 g of azobisisobutyronitrile (AIBN) in 2.5 mL of dimethyl sulfoxide (DMSO); under a nitrogen atmosphere, polymerize the uniformly mixed turbid liquid in a Teflon high-pressure reaction tube at 100 °C for 24 h, wash the obtained polymer with ethyl acetate and methanol, and then dry it under vacuum to obtain the nano silver-azacyclic carbene polymer.

[0053] In the traditional impregnation method for loading silver metal on polymers, most of the silver can only be distributed on the surface of the material and is very prone to agglomeration, resulting in low catalytic activity in many chemical reactions. In addition, due to the different binding angles of polymer monomers during the polymerization process, the structure of the polymer cannot be unified, leading to unstable properties of the polymer itself. In the present invention, the metal is pre-coordinated to the monomer, and during the polymerization process, the metal can fix the polymerization angle of the monomer, making the polymer structure uniform. At the same time, the metal is uniformly dispersed within the polymer framework, further reducing the size of the metal particles within the polymer framework and significantly improving its catalytic activity and stability.

[0054] The synthesis route of the silver-nanoparticle-azacyclic carbene polymer (Ag@POP-NL-3) is as follows:

[0055]

[0056]

[0057] Using 1,3,5-tris(bromomethyl)benzene and 1-vinylimidazole as raw materials, the imidazolium salt (NL-3) is synthesized as a monomer. Silver nitrate and the monomer are dissolved in methanol, and the monomer is coordinated with the metal to obtain Ag@NL-3. Using azobisisobutyronitrile (AIBN) as an initiator, Ag@NL-3 and divinylbenzene (DVB) are copolymerized to form Ag@POP-NL-3 with a hierarchical pore structure.

[0058] It can be found from the SEM micrograph of Ag@POP-NL-3 that there are a large number of pores and channels inside the polymer, forming a huge network-like space, as Figure 1 shown. There are also many stacks of particles with a size of 200 - 500 nm inside, making its internal structure more diverse. The specific surface area of the material is approximately 485.43 m 2 / g, and the pore volume is about 0.99 cm 3 / g. As Figure 2 shown by N2 adsorption / desorption analysis, both materials conform to the characteristics of type IV isotherms with obvious H3 hysteresis at high P / P0, showing the characteristics of typical mesoporous materials. The pore size distribution of the polymer is mainly concentrated at 20 nm, which further proves this conclusion. The large specific surface area, rich pore channels, and particle structure enable the polymer to have more exposed catalytic sites, enhancing its catalytic activity. In order to determine the structure of the polymer, infrared spectroscopy analysis was performed on Ag@POP-NL-3. In addition, as Figure 3 shown, the thermogravimetric data shows that Ag@POP-NL-3 has thermal stability and can withstand a relatively high temperature close to 280 °C. Figure 4 Among them, 3100 - 2850 cm -1It shows a very broad and strong band, which is caused by the stretching vibration of the CH group of the imidazole ring and the aromatic ring. The three peaks near 1632, 1565, and 1157 are caused by the vibration of the imidazole ring, corresponding to C=N, C=C, and CN respectively, which shows that the carbene structure remains intact during the polymerization process and is not destroyed. Figure 5 As shown, the types of surface elements and corresponding electronic valence states in Ag@POP-NL-3 were determined by X-ray photoelectron spectroscopy (XPS) analysis, which further verified the conclusion. The two peaks at 401.5 eV are attributed to the pyrrolic nitrogen in the imidazole ring, and the peak at the binding energy of 399.5 eV is attributed to the pyridine nitrogen in the imidazole ring. In the peak separation diagram of Ag 3d, the two peaks at 367.6 eV and 373.6 eV correspond to the binding energies of Ag(Ⅰ)3d5 / 2 and Ag(Ⅰ)3d3 / 2, respectively, which are the characteristic peaks of Ag(Ⅰ). The characteristic peak of bromine at 68.0 eV also indicates the presence of bromine in the material. Figure 6 and Figure 7 As shown in the TEM images, it can be seen that the silver particles of the material prepared by the traditional impregnation method are aggregated on the polymer surface and are unevenly distributed. However, in the Ag@POP-NL-3 synthesized by pre-coordination, the silver particles are evenly distributed in the polymer, and the metal particle size is about 2-5nm, as shown in Figure 2. Figure 8 and Figure 9 As shown in Figure 2, the parallel crystal strips of these nanoparticles show that Figure 9 As shown, the stripe spacing is 0.24 nm, which is consistent with the characteristics of the Ag (111) crystal plane.

[0059] In order to verify the carbon dioxide enrichment ability of Ag@POP-NL-3, the carbon dioxide adsorption performance of the material was tested. The results show that Ag@POP-NL-3 does have a good adsorption capacity for carbon dioxide. Figure 10 In addition, the material also has a good adsorption effect on the reaction substrate, such as Figure 11 As shown, this creates an environment of local high concentration of carbon dioxide and reaction substrate inside Ag@POP-NL-3, making the reaction between the two easier to proceed.

[0060] Embodiment 2:

[0061] As a specific application of the Ag@POP-NL-3 polymer of the present invention, 1.0 mmol of acetylene alcohol and 80 mg of Ag@POP-NL-3 were added to 2 mL of acetonitrile to obtain a mixture. Ag@POP-NL-3 was used as a catalyst. The mixture was stirred at room temperature for 12 h in an atmosphere of a mixture of carbon dioxide and air containing 30 vol.% CO2. After the reaction was completed, the catalyst was recovered and reused.

[0062] After the reaction was completed, the catalyst Ag@POP-NL-3 was separated by filtration, and the solvent in the filtrate was evaporated under vacuum to obtain the crude product.

[0063] The crude product was further purified by silica gel column chromatography to obtain cyclic carbonate.

[0064] Taking the carboxylation cyclization reaction of the mixture of CO2 and air (carbon dioxide concentration is 30 vol.%) and 2-methyl-3-butyn-2-ol as a model, the reaction conditions were optimized. Without adding any catalyst, the reaction could not proceed, as shown in Table 1, entry 1. When silver nitrate was added to the reaction, a small amount of the target product could be obtained, but the yield was not ideal. Increasing the dosage of silver nitrate could not improve the yield of the target product. It can be seen that directly using silver nitrate as a catalyst could not achieve the ideal effect. However, when POP-NL-3 was added to the reaction, the reaction effect was significantly improved, and the yield increased from 26% to 63% with the same metal dosage, as shown in Table 1, entry 6. Thus, it can be seen that the heterogeneous organometallic ligand has a great influence on the catalytic effect of the catalyst. Therefore, the catalytic effects of different organometallic ligands coordinated with silver were tested, and it was found that POP-NL-3 showed the best catalytic effect on this reaction. However, the surface-doped metal complexes could not ensure the consistent catalytic activity of the catalyst. After changing to Ag@POP-NL-3, the catalytic activity of the catalyst was more stable, and the yield of the target product was always >99% in multiple experiments, as shown in Table 1, entry 9. In addition, the influence of base on the reaction of 2-methyl-3-butyn-2-ol and carbon dioxide was also very significant. Without adding base, the reaction could not proceed, and at the same time, when DBU was replaced with other bases, the reaction could not achieve the ideal effect, as shown in Table 1, entries 11-14.

[0065] Table 1. Optimization of the carboxylation cyclization reaction conditions of 2-methyl-3-butyn-2-ol with 30 vol.% low-concentration CO2a

[0066]

[0067] In Table 1, 1a is 2-methyl-3-butyn-2-ol, and 2a is 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one;

[0068] In Table 1, a Reaction conditions: 1a 1 mmol, catalyst 80 mg, metal content 4.5 mol%, additive 0.6 eq, MeCN 2 mL, room temperature, 12 h, and 30 vol.% CO2 placed in an airbag;

[0069] b1 The content of the compound was determined by 1H NMR method: 1,3,5-trimethylbenzene was used as the internal standard;

[0070] Catalyst 20 mol%

[0071] Catalyst d 80 mg, metal content 4.5 mol%

[0072] Under the optimal reaction conditions, the substrate applicability of the catalyst was discussed. When alkyl substituents such as methyl, ethyl, isopropyl, etc. were introduced into the substrate, Ag@POP-NL-3 had excellent catalytic activity for the reaction of most substrates with low-concentration 30 vol.% CO2 and the corresponding target products, and the yields were relatively high. However, the study also found that the increase in the alkyl alkane chain length was not conducive to the reaction, as shown in Table 2, 2a - 2j. When the substrate contained long-chain alkyl groups, for the catalyst with Ag particles directly loaded on POP-NL-3, the yield of the target product was only about 30%, as shown in Table 2, 2g, 2h. This indicates that reducing the particle size of the metal in the catalyst and optimizing its spatial distribution in the polymer are crucial for improving the catalytic performance of the metal catalyst.

[0073] Table 2. Substrate scope of the carboxyl cyclization reaction catalyzed by Ag@POP-NL-3 a,b

[0074]

[0075] In Table 2, 1 is the alkynol compound, 2 is the corresponding cyclic carbonate, R 1 , R 2 represents a functional group, and R 1 , R 2 can be the same or different;

[0076] In Table 2, a Reaction conditions: 11 mmol, 80 mg of Ag@POP-NL-3 (containing 4.5 mol% Ag), 0.6 eq of DBU, 2 mL of MeCN, room temperature, 12 h, 30 vol.% CO2 placed in an airbag.

[0077] b1 Determination of the compound content by 1H NMR method: Using 1,3,5-trimethylbenzene as the internal standard;

[0078] c 80 mg of the catalyst, 4.5 mol% Ag was directly loaded onto POP-NL-3.

[0079] Since the actual exhaust gas is more complex than the simulated gas (including 30% carbon dioxide and 70% dry air), there are more factors affecting the carbon fixation process, which puts higher requirements on the stability of the catalyst performance. Taking the actual lime kiln exhaust gas as the source of CO2, the lime kiln exhaust gas contains 30% CO2, 67.9% N2, 2% O2, 0.1% CO and 15ppm SO2, and the applicability of Ag@POP-NL-3 in the actual exhaust gas was studied. The results show that Ag@POP-NL-3 can effectively catalyze the conversion of low-concentration CO2 in lime kiln exhaust gas into cyclic carbonates, see Table 3.

[0080] Table 3. Fixation of low concentration CO2 in lime kiln exhaust gasa,b

[0081]

[0082] In Table 3, 1 is an alkynol compound, 2 is the corresponding cyclic carbonate, R 1 , R 2 Represents a functional group, R 1 , R 2 Can be the same or different;

[0083] In Table 3, a Reaction conditions: 1 1 mmol, Ag@POP-NL-3 80 mg (containing 4.5 mol%), DBU 0.6 eq., MeCN 2 mL, room temperature, 12 h, lime kiln waste gas bag.

[0084] b1 The content of the compound was determined by H NMR method: 1,3,5-trimethylbenzene was used as the internal standard.

[0085] As shown in the following formula, the carboxyl cyclization reaction was carried out on a gram scale using lime kiln waste gas. When the reaction was scaled up on a gram scale, the catalyst Ag@POP-NL-3 could convert CO2 into the desired target product and still had a high catalytic activity.

[0086]

[0087] According to the isotope experiment results, 13 CO2 is the carbon source, and through nuclear magnetic hydrogen spectrum analysis, 13 C was successfully introduced into the product, such as Figure 12 Based on previous studies, a low-concentration CO2 and propargyl alcohol carboxylation cyclization reaction mechanism using Ag@POP-NL-3 as a catalyst can be proposed, as shown in Figure 13 Initially, in the system of Ag@POP-NL-3 and DBU, DBU captured a proton of the hydroxyl group of 2-methyl-3-butyn-2-ol by forming a hydrogen bond.+ The empty orbitals on it combine with the π electrons of the C≡C in 2-methyl-3-butyn-2-ol to form intermediate 3. Then, a nucleophilic attack on carbon dioxide is initiated by generating an alkoxide ion pair, enabling carbon dioxide to be smoothly inserted. Subsequently, intramolecular cyclization addition of intermediate 4 occurs to generate vinyl-silver intermediate 5. Finally, after the metal is removed in situ, cyclic carbonate 2a is formed, and the catalyst combines with carbon dioxide to enter the next cycle.

[0088] In summary, nano silver-N-heterocyclic carbene polymer was successfully synthesized by the pre-coordination method of silver and monomers, effectively avoiding the metal aggregation phenomenon in the traditional impregnation method, enabling silver nanoparticles to be evenly dispersed in the polymer, and greatly improving the catalytic performance of silver. Due to the rich CO2 adsorption sites in the polymer itself, the CO2 capture ability and catalytic activity of Ag@POP-NL-3 were further improved, and it was successfully applied to the resource utilization of carbon dioxide in lime kiln waste gas.

[0089] Attachment: Products 1 H, 13 C NMR data

[0090]

[0091] NL-3: White solid. 1 H NMR(500MHz,DMSO-d6)δ10.03(s,3H),8.39(s,3H),8.15(s,3H),7.82(s,3H),7.43 - 7.34(m,3H),6.12 - 6.02(m,3H),5.58(s,6H),5.39(dd,J1=8.7,J2=2.2Hz,3H). 13 C NMR(125MHz,DMSO-d6)δ135.6,135.5,129.6,128.7,123.3,119.6,109.1,51.5.

[0092]

[0093] 2a: Colorless liquid. 1 H NMR(500MHz,Chloroform-d)δ4.75(d,J=4.0Hz,1H),4.30(d,J=3.9Hz,1H),1.59(s,6H). 13 C NMR(125MHz,Chloroform-d)δ158.9,151.3,85.3,84.6,27.6.HRMS(m / z)(ESI):calcd for C6H8O3[M+Na] +151.0366, found 151.0365.

[0094]

[0095] 2b: Bright yellow liquid. 1 H NMR(500MHz, Chloroform-d)δ4.74(d, J=3.9Hz, 1H), 4.25(d, J=3.9Hz, 1H), 1.81 - 1.74(m, 2H), 1.68 - 1.62(m, 1H), 1.54(s, 3H), 0.95 - 0.90(m, 6H). 13 C NMR(125MHz, Chloroform-d)δ158.4, 151.5, 87.4, 85.6, 48.5, 27.0, 24.3, 24.0, 23.7. HRMS(m / z)(ESI): calcd for C9H 14 O3[M + Na] + 193.0835, found 193.0832.

[0096]

[0097] 2c: Colorless liquid. 1 H NMR(500MHz, Chloroform-d)δ4.80(d, J=3.8Hz, 1H), 4.26(d, J=3.8Hz, 1H), 1.97 - 1.89(m, 1H), 1.56(s, 3H), 1.03 - 0.97(m, 6H). 13 C NMR(125MHz, Chloroform-d)δ157.3, 151.8, 89.9, 86.3, 37.1, 24.1, 16.4, 16.1. HRMS(m / z)(ESI): calcd for C8H 12 O3[M + Na] + 179.0679, found 179.0677.

[0098]

[0099] 2d: Bright yellow liquid. 1 H NMR(500MHz, Chloroform-d)δ4.79(d, J=3.9Hz, 1H), 4.26(d, J=3.7Hz, 1H), 1.93 - 1.84(m, 1H), 1.78 - 1.70(m, 1H), 1.56(s, 3H), 0.96(t, J=7.4Hz, 3H). 1313C NMR (125 MHz, Chloroform-d) δ 157.5, 151.6, 87.7, 85.6, 33.5, 26.0, 7.4. HRMS (m / z) (ESI): calcd for C7H 10 O3 [M+Na] + 165.0522, found 165.0518.

[0100]

[0101] 2e: Colorless liquid. 1 1H NMR (500 MHz, Chloroform-d) δ 4.86 (d, J = 3.8 Hz, 1H), 4.22 (d, J = 3.8 Hz, 1H), 1.97 - 1.88 (m, 2H), 1.76 - 1.67 (m, 2H), 0.98 (t, J = 7.4 Hz, 6H). 13 13C NMR (125 MHz, Chloroform-d) δ 156.0, 152.0, 90.9, 85.9, 32.1, 7.2. HRMS (m / z) (ESI): calcd for C8H 12 O3 [M+Na] + 179.0679, found 179.0678.

[0102]

[0103] 2f: Colorless liquid. 1 1H NMR (500 MHz, Chloroform-d) δ 4.78 (d, J = 3.9 Hz, 1H), 4.26 (d, J = 3.9 Hz, 1H), 1.87 - 1.80 (m, 1H), 1.71 - 1.64 (m, 1H), 1.57 (s, 3H), 1.47 - 1.37 (m, 2H), 0.94 (t, J = 7.4 Hz, 3H). 13 13C NMR (125 MHz, CDCl3) δ 158.0, 151.6, 87.3, 85.5, 42.7, 26.4, 16.5, 13.9. HRMS (m / z) (ESI): calcd for C8H 12 O3 [M+Na] + 179.0679, found 179.0678.

[0104]

[0105] 2g: Colorless liquid. 11H NMR (500 MHz, Chloroform-d) δ 4.77 (d, J = 3.9 Hz, 1H), 4.25 (d, J = 3.8 Hz, 1H), 1.87 - 1.81 (m, 1H), 1.71 - 1.65 (m, 1H), 1.56 (s, 3H), 1.39 - 1.23 (m, 12H), 0.86 (t, J = 6.9 Hz, 3H). 13 13C NMR (125 MHz, Chloroform-d) δ 158.0, 151.6, 87.3, 85.5, 40.5, 31.9, 29.4, 29.3, 26.4, 23.1, 22.7, 14.1. HRMS (m / z) (ESI): calcd for C 12 H 20 O3 [M + NH4] + 230.1751, found 230.1747.

[0106]

[0107] 2h: Colorless liquid. 1 1H NMR (500 MHz, Chloroform-d) δ 5.05 (t, J = 7.1 Hz, 1H), 4.81 (d, J = 3.9 Hz, 1H), 4.27 (d, J = 3.9 Hz, 1H), 2.16 - 2.02 (m, 2H), 1.94 - 1.86 (m, 1H), 1.76 - 1.70 (m, 1H), 1.68 (s, 3H), 1.62 - 1.52 (m, 6H). 13 13C NMR (125 MHz, Chloroform-d) δ 157.8, 151.6, 133.4, 122.1, 87.2, 85.6, 40.4, 26.7, 25.8, 22.1, 17.8. HRMS (m / z) (ESI): calcd for C 11 H 16 O3 [M + NH4] + 214.1438, found 214.1436.

[0108]

[0109] 2i: Colorless liquid. 1 1H NMR (500 MHz, Chloroform-d) δ 4.78 (d, J = 3.9 Hz, 1H), 4.33 (d, J = Hz, 1H), 2.26 - 2.19 (m, 2H), 1.97 - 1.83 (m, 6H). 1313C NMR (125 MHz, Chloroform-d) δ 157.9, 151.4, 94.2, 85.3, 40.7, 24.3. HRMS (m / z) (ESI): calcd for C9H 10 O3 [M+Na] + 177.0522, found 177.0521.

[0110]

[0111] 2j: Colorless liquid. 1 1H NMR (500 MHz, Chloroform-d) δ 4.71 (d, J = 3.9 Hz, 1H), 4.27 (d, J = 3.8 Hz, 1H), 1.96 (d, J = 11.2 Hz, 2H), 1.74 - 1.57 (m, 7H), 1.35 - 1.23 (m, 1H). 13 13C NMR (125 MHz, Chloroform-d) δ 158.8, 151.5, 86.4, 85.5, 36.5, 24.4, 21.7. HRMS (m / z) (ESI): calcd for C9H 12 O3 [M+Na] + 191.0679, found 191.0676.

[0112] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of precoordinated nano silver - N - heterocyclic carbene polymer catalyst, characterized in that, It includes the following steps: S1, Preparation of N-heterocyclic carbene precursor (NL-3): Add 1,3,5-tris(bromomethyl)benzene and 1-vinylimidazole into toluene or acetonitrile, magnetically stir at 70 °C - 110 °C for 24 - 48 h, and then cool to room temperature; filter, and then wash the precipitate with ethyl acetate multiple times, collect the precipitate, and dry it under vacuum to obtain the N-heterocyclic carbene precursor; S2, Preparation of N-heterocyclic carbene-silver complex (Ag@NL-3): Add silver nitrate into methanol, and ultrasonically dissolve it in the dark until completely dissolved; dissolve NL-3 in methanol under a nitrogen atmosphere; drop the silver nitrate methanol solution into the NL-3 methanol solution, and stir in the dark for 12 - 24 h; after the precipitate is collected by centrifugation, wash it with methanol and dry it under vacuum to obtain the N-heterocyclic carbene-silver complex; S3, Preparation of silver nanometer-N-heterocyclic carbene polymer (Ag@POP-NL-3): Uniformly disperse the monomer Ag@NL-3, divinylbenzene (DVB), and azobisisobutyronitrile (AIBN) in dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF); under a nitrogen atmosphere, polymerize the uniformly mixed turbid liquid in a Teflon high-pressure reaction tube, wash the obtained polymer with ethyl acetate and methanol, and then dry it under vacuum to obtain the silver nanometer-N-heterocyclic carbene polymer; In S1, the volume molar ratio of toluene or acetonitrile to 1,3,5-tris(bromomethyl)benzene and 1-vinylimidazole is 25 mL : 5.0 mmol : 15.5 mmol; In S2, the molar volume ratio of silver nitrate to methanol is 0.5 mmol : 20 mL; the molar volume ratio of NL-3 to methanol is 1 mmol : 10 mL; In S3, the mass volume ratio of Ag@NL-3 to DVB, AIBN, and DMSO is 0.20 g : 0.40 g : 0.060 g : 2.5 mL; In S3, the turbid liquid is polymerized in a Teflon high-pressure reaction tube at 100 - 120 °C for 24 - 36 h.

2. The Ag@POP-NL-3 polymer prepared by the preparation method of the pre-coordinated silver nanometer-N-heterocyclic carbene polymer catalyst described in claim 1.

3. Use of the pre-coordinated nano silver-azacyclic carbene polymer catalyst prepared by the method according to claim 1 in the reaction of fixing carbon dioxide, characterized in that, Add alkynol and Ag@POP-NL-3 into acetonitrile to obtain a mixture. Using Ag@POP-NL-3 as a catalyst, stir the mixture at room temperature for at least 12 h in an atmosphere of air containing carbon dioxide or lime kiln waste gas. After the reaction, recover the catalyst and reuse it; The molar mass volume ratio of alkynol to Ag@POP-NL-3 and acetonitrile is 1.0 mmol : 80 mg : 2 mL; After the reaction, filter to separate the filtrate as the catalyst Ag@POP-NL-3. Evaporate the solvent in the filtrate under vacuum to obtain a crude product, and further purify the crude product through a silica gel chromatography column to obtain cyclic carbonate.

4. The application according to claim 3, characterized in that, Ag@POP-NL-3 is used as a catalyst for fixing carbon dioxide in lime kiln waste gas.

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