A pyrimidinyl ionic polymer catalyst, its preparation and use in the catalytic conversion of carbon dioxide

Abstract

The application discloses a kind of pyrimidine-based ionic polymer catalyst and its preparation and application in catalyzing carbon dioxide conversion, comprising, the pyrimidine-based ionic polymer catalyst has secondary amine and pyridine salt functionalized pyrimidine-based ionic polymer, it contains a large number of nitrogen atom basic site, can efficiently activate carbon dioxide, abundant hydrogen bond donor site can activate alkylene oxide and the intermediate after alkylene oxide ring-opening is stabilized, under the condition of solvent-free and without auxiliary catalyst, catalytic reaction process can be high selectivity to carbon dioxide synthesis cyclic carbonate. After reaction, catalyst and product can be separated by only filtering and washing operation.This achievement overcomes the defects of current reported catalytic system, such as poor activity, insufficient stability, poor cycle performance and dependence on difficult-to-separate cocatalyst.In addition, the raw material of the present application is easy to obtain, the reaction condition is mild, the synthesis efficiency is high, and it has certain industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a pyrimidin-based ionic polymer catalyst, its preparation, and its application in catalytic carbon dioxide conversion. Background Technology

[0002] The continued consumption of fossil fuels has led to a sustained increase in carbon dioxide emissions into the atmosphere, causing environmental problems including an exacerbated greenhouse effect, disruption of ecological balance, and significant changes in global climate patterns. To address these challenges, innovative and environmentally sustainable methods are urgently needed to curb carbon dioxide emissions and reduce its concentration in the atmosphere. A key approach to reducing carbon emissions lies in implementing carbon capture, utilization, and storage (CCS). These methods not only reduce carbon emissions but also facilitate the conversion of renewable carbon sources into valuable chemical products. Among various strategies for carbon dioxide utilization, the chemical conversion of carbon dioxide with epoxides has received widespread attention as a promising approach, particularly the cycloaddition reaction between carbon dioxide and epoxides, which produces cyclic carbonates. These carbonates can be used as solvents or monomers in polymer synthesis, components in composite materials, fine chemicals, and industrial lubricants.

[0003] However, the efficient utilization of carbon dioxide through chemical conversion depends on the development of efficient, sustainable, and recyclable catalysts capable of activating inert carbon dioxide molecules under mild conditions. While significant progress has been made in previous studies of organic ionic polymers for carbon dioxide conversion, conventional preparation methods suffer from uncontrollable active site density, leading to unstable catalytic performance or the need for co-catalysts and solvents. On the other hand, many such catalysts require harsh reaction conditions, such as high reaction temperatures (>100 °C) and high pressures (>1.0 MPa), due to limited pore structure, insufficient exposure of active sites, or weak affinity for carbon dioxide.

[0004] Therefore, developing heterogeneous catalysts with abundant porous structures, high-density active sites, and strong carbon dioxide affinity to achieve carbon dioxide catalytic conversion under mild conditions is one of the important research topics in the field of carbon dioxide catalytic conversion. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] The purpose of this invention is to overcome the deficiencies in the existing technology and provide a pyrimidine-based ionic polymer material that is easy to synthesize, highly active, and recyclable, for use in catalyzing the conversion of carbon dioxide to cyclic carbonates. This invention is proposed in view of the problems existing in the carbon dioxide catalysis of organic ionic polymers. Therefore, one objective of this invention is to overcome the high temperature and high pressure problems of existing carbon dioxide catalytic systems. This invention provides a pyrimidine-based ionic polymer material, characterized by being prepared by a method comprising the following steps: (1) Preparation of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalides: Pyridine carboxaldehyde and 1,4-bis(halomethyl)benzene were dissolved in acetonitrile solution, and then reacted at a constant temperature of 25~120℃ for 1~48 hours; after the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalides; (2) The above-mentioned 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalide and 2,4,6-triaminopyrimidine were dissolved in DMF, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 90~180℃ for 10-100 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material was obtained.

[0007] The pyridine carboxaldehyde in step (1) is one of 2-pyridine carboxaldehyde, 3-pyridine carboxaldehyde, and 4-pyridine carboxaldehyde, preferably 4-pyridine carboxaldehyde.

[0008] The 1,4-di(halomethyl)benzene in step (1) is one of 1,4-di(chloromethyl)benzene and 1,4-di(bromomethyl)benzene, preferably 1,4-di(bromomethyl)benzene.

[0009] In step (1), the molar ratio of 2,4,6-triaminopyrimidine to 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalide is 1:1 to 5, preferably 1:1.5.

[0010] Another aspect of the present invention provides a method for synthesizing cyclic carbonates by reacting low-concentration carbon dioxide with epoxides using the aforementioned pyrimidinyl ionic polymer material. The method is characterized by using a pyrimidinyl ionic polymer as a catalyst to synthesize cyclic carbonates via a cycloaddition reaction between the epoxide and carbon dioxide. As some preferred embodiments of the present invention, the amount of the pyrimidinyl ionic polymer catalyst is 1 wt% to 20 wt% of the epoxide, preferably 10%.

[0011] As some preferred embodiments of the present invention, the cycloaddition reaction temperature is 60~150℃, the reaction pressure is atmospheric pressure, and the time is 1~48 hours, preferably the reaction temperature is 80℃ and the reaction time is 24 hours.

[0012] Beneficial effects of this invention: The pyrimidinyl ionic polymer catalyst of this invention contains a large number of nitrogen-based basic sites, which can efficiently activate carbon dioxide. Abundant hydrogen bond donor sites can activate epoxides and stabilize intermediates after ring-opening. Under solvent-free and co-catalyst-free conditions, the catalytic reaction can highly selectively promote the synthesis of cyclic carbonates from carbon dioxide. After the reaction, the catalyst and product can be separated simply by filtration and washing. This achievement overcomes the shortcomings of currently reported catalytic systems, such as poor activity, insufficient stability, poor cycling performance, and dependence on difficult-to-separate co-catalysts. Furthermore, the raw materials of this invention are readily available, the reaction conditions are mild, and the synthesis efficiency is high, showing promising prospects for industrial application. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a reaction flow diagram of the present invention; Figure 2 The infrared spectrum of the pyrimidine-based ionic polymer catalyst of this invention is shown below. Figure 3 The XPS spectrum of the pyrimidine-based ionomer catalyst of this invention is shown below. Figure 4 This is a scanning electron microscope image of the pyrimidin-based ionic polymer catalyst of the present invention; Figure 5 The 1H NMR spectrum of the 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide monomer of this invention; Figure 6 The photon nuclear magnetic resonance (NMR) spectrum of 4-chloromethyl cyclocarbonate, the product of the cycloaddition reaction of epichlorohydrin and carbon dioxide catalyzed by the pyrimidin-based ionic polymer of this invention, is shown. Detailed Implementation

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0015] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0016] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0017] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0018] Table 1

[0019] Example 1 This embodiment provides a method for preparing a pyrimidin-based ionic polymer catalyst and its application in the catalytic reaction of carbon dioxide and epichlorohydrin, specifically: In this embodiment section, the synthetic route of the pyrimidine-based ionomer catalyst material is shown below. Figure 1 .

[0020] (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide (DPFB) monomer: 10 mmol of 4-pyridinecarboxaldehyde and 5 mmol of 1,4-di(bromomethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide (DPFB) with a yield of 95%. DPFB 1H NMR spectroscopy data: 1 HNMR (400 MHz, D2O) δ 8.80 (d, J = 6.8 Hz, 4H), 8.02 (d, J = 6.6 Hz, 4H), 7.42 (s, 4H), 6.07 (s, 2H), 5.74 (s, 4H).

[0021] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP): 3 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dibromide and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LMF solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP was obtained with a yield of 75%.

[0022] (3) The reaction of CO2 with epichlorohydrin catalyzed by pyrimidine-based ion polymer catalyst (DT-HIP): 45 mg of pyrimidine-based organic ion polymer catalyst DT-HIP, accounting for 10 wt% of the reactant, was placed in a 10 mL Schlenk reaction tube, connected to the CO2-vacuum line, evacuated and filled with CO2 (×10), and 0.45 g of epichlorohydrin was added with a syringe. The reaction was stirred at 120 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature. The product was quantitatively analyzed by gas chromatography, and the yield was 89%.

[0023] Figure 2 This is the infrared spectrum of the pyrimidine-based ionic polymer catalyst of the present invention. When 2,4,6-triaminopyrimidine (TAP) reacts with an ionic crosslinking agent (DPFB) containing two aldehyde functional groups via a Schiff base reaction, an imine polymer can be generated. However, the carbon-nitrogen double bond in the imine structure may be further reduced to a carbon-nitrogen single bond by the amino group on the adjacent pyrimidine ring. To verify the chemical structure of the polymer DT-HIP, Fourier transform infrared spectroscopy (FT-IR) analysis was performed on the precursor triaminopyrimidine (TAP), the ionic crosslinking agent (DPFB), and the prepared polymer. The results are as follows. Figure 2 As shown. The precursor triaminopyrimidine (TAP) at 3416 cm⁻¹ -1 and 3450 cm -1 The characteristic peak at [location] is attributed to the stretching vibration of the amino group; however, in the polymer DT-HIP, the stretching vibration peak of the amino group disappears, and a peak appears at 3338 cm⁻¹. -1 The new peak at this point indicates that the primary amine has been converted into a secondary amine. Furthermore, at 2974 cm⁻¹... -1 and 2981 cm -1 The peaks at 1709 cm⁻¹ correspond to the stretching vibrations of the methylene groups in the ionic crosslinking agent and the polymer DT-HIP, respectively. The peak at 1709 cm⁻¹ corresponds to the stretching vibrations of the methylene groups in the ionic crosslinking agent. -1 A distinct carbonyl (C=O) stretching vibration peak was observed at 1570 cm⁻¹, but this peak disappeared in the polymer DT-HIP, further confirming that triaminopyrimidine (TAP) had successfully bound to the ionic crosslinking agent (DPFB) via a Schiff base reaction. Furthermore, at 1570 cm⁻¹... -1 and 1419 cm-1 The peak at 1560 cm⁻¹ is attributed to the C=N stretching vibration of the pyrimidine ring, and is also present in the polymer DT-HIP at 1560 cm⁻¹. -1 and 1421 cm -1 Similar peaks were observed at [location], indicating the presence of pyrimidine structures in the polymer. Furthermore, the ionic crosslinking agent DPFB and CN [in the polymer] [were observed]. + The stretching vibration peaks are located at 1188 cm⁻¹. -1 and 1143 cm -1 The above results confirm that the polymer DT-HIP has been successfully prepared by the Schiff base reaction of triaminopyrimidine (TAP) with an ionic crosslinking agent (DPFB).

[0024] Figure 3 The figure shows the XPS spectrum of the pyrimidine-based ionic polymer catalyst of this invention. As can be seen from the figure, the X-ray photoelectron spectroscopy (XPS) spectrum further confirms the surface composition of DT-HIP. In the full-spectrum XPS spectrum of DT-HIP, characteristic peaks of O1s, N1s, C1s, and Br3d can be observed, with binding energies at 532.3 eV, 400.2 eV, 284.8 eV, and 67.8 eV, respectively. The Br3d spectrum of the DT-HIP polymer can be split into two peaks, located at 68.2 eV and 67.2 eV, respectively, belonging to Br3d3 / 2 and Br3d5 / 2. Furthermore, in the high-resolution N1s spectrum of DT-HIP, the peaks with binding energies at 401.8 eV, 401.8 eV, and 399.8 eV are attributed to C1s and C1s, respectively. ＋ C=N and CN. These characterization data indicate that ionic polymers containing bromide ions have been successfully obtained.

[0025] Figure 4 This is a scanning electron microscope (SEM) image of the pyrimidine-based ionic polymer catalyst of the present invention. The surface morphology of the polymer DT-HIP was observed using SEM. This polymer material exhibits a highly porous three-dimensional network structure, with its abundant pore structure composed of numerous interconnected or independently distributed pores, providing ample channels for mass transport and diffusion. From the pore characteristics, the pore size distribution shows significant polydispersity, encompassing various structural levels from macropores to micropores. The presence of macropores promotes rapid diffusion and transport of substrate molecules within the material, effectively reducing mass transfer resistance; while the microporous structure has an extremely high specific surface area, providing a large number of active sites. Furthermore, the pore wall surface is not smooth and flat, but rather rough and adhered with many tiny particles or protrusions, further enhancing the surface activity of the material. In addition, the EDS elemental distribution map of DT-HIP shows that carbon (C), nitrogen (N), and bromine (Br) elements are uniformly distributed in the sample, indicating that triaminopyrimidine (TPA) and the ionic crosslinking agent DPFB units are uniformly dispersed within the polymer backbone.

[0026] Figure 5 This is the 1H NMR spectrum of the 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide monomer (DPFB) of this invention; Figure 6 The photon nuclear magnetic resonance (NMR) spectrum of 4-chloromethyl cyclocarbonate, the product of the cycloaddition reaction of epichlorohydrin and carbon dioxide catalyzed by the pyrimidin-based ionic polymer of this invention, is shown.

[0027] Example 2 (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(3,3′-dipyridinium)dibromide monomer: 10 mmol of 3-pyridinecarboxaldehyde and 5 mmol of 1,4-bis(bromomethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(3,3′-dipyridinium)dibromide with a yield of 90%.

[0028] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP-1): 3 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(3,3′-dipyridinium) dibromide and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LDM solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP-1 was obtained with a yield of 81%.

[0029] Example 3 (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(2,2′-dipyridinium)dibromide monomer: 10 mmol of 2-pyridinecarboxaldehyde and 5 mmol of 1,4-bis(bromomethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(2,2′-dipyridinium)dibromide with a yield of 90%.

[0030] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP-2): 3 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(2,2′-dipyridinium) dibromide and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LDM solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP-2 was obtained with a yield of 72%.

[0031] Example 4 (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(2,2′-dipyridinium) dichloride monomer: 10 mmol of 4-pyridinecarboxaldehyde and 5 mmol of 1,4-di(chloromethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dichloride with a yield of 88%.

[0032] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP-3): 3 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dichloride and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LDM solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP-3 was obtained with a yield of 77%.

[0033] Example 5 (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide monomer: 10 mmol of 4-pyridinecarboxaldehyde and 5 mmol of 1,4-bis(bromomethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide with a yield of 95%.

[0034] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP-4): 2 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dibromide and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LMF solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP-4 was obtained with a yield of 56%.

[0035] Example 6 (1) Synthesis of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide monomer: 10 mmol of 4-pyridinecarboxaldehyde and 5 mmol of 1,4-bis(bromomethyl)benzene were dissolved in 20 mL of acetonitrile solution, and then reacted at 70 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide with a yield of 95%.

[0036] (2) Synthesis of pyrimidine-based ionic polymer catalyst (DT-HIP-5): 6 mmol of 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dibromide and 2 mmol of 2,4,6-triaminopyrimidine were dissolved in 8 mL of LDM solution, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 150 °C for 72 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based organic ionic polymer material DT-HIP-5 was obtained with a yield of 70%.

[0037] Example 7 Take 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to a CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.45 g of epichlorohydrin as a reactant using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 90%.

[0038] Example 8 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP-1, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated, and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 73%.

[0039] Example 9 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP-2, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated, and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 56%.

[0040] Example 10 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP-3, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 80%.

[0041] Example 11 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP-4, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 55%.

[0042] Example 12 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP-5, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated, and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 88%.

[0043] Example 13 22.5 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 5 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 44%.

[0044] Example 14 Take 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 15 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to the CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.45 g of epichlorohydrin as a reactant using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 90%.

[0045] Example 15 Take 90 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 20 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to a CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.45 g of epichlorohydrin as a reactant using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 91%.

[0046] Example 16 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 25 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 18%.

[0047] Example 17 Take 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to the CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.45 g of epichlorohydrin as a reactant using a syringe, stir the reaction at 100 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 88%.

[0048] Example 18 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated and filled with CO2 (×10). 0.45 g of epichlorohydrin was added using a syringe, and the reaction was stirred at 80 °C for 12 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 78%.

[0049] Example 19 Take 45 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to a CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.45 g of epichlorohydrin as a reactant using a syringe, stir the reaction at 80 °C for 36 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 90%.

[0050] The products obtained in Examples 7-19 are shown in the 1H NMR spectra as follows: Figure 6 The results shown are exactly the same. The proton NMR data are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.02 – 4.90 (m, 1H), 4.59 (t, J = 8.5Hz, 1H), 4.41 (dd, J = 8.8, 5.8 Hz, 1H), 3.81 – 3.72 (m, 2H). Example 20 Take 68 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to a CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.68 g of epichlorohydrin using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 92%.

[0051] Example 21 Take 50 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to a CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.50 g of 1,2-epoxyhexane as reactant using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 87%.

[0052] Example 22 49 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, evacuated, and filled with CO2 (×10). 0.49 g of 1,2-epoxy-5-hexene was added using a syringe. The reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature. The product was quantitatively analyzed by gas chromatography, and the yield was 89%.

[0053] Example 23 75 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, was placed in a 10 mL Schlenk reaction tube, connected to a CO2-vacuum line, and evacuated and filled with CO2 (×10). 0.75 g of 2,3-epoxypropylphenyl ether was added using a syringe, and the reaction was stirred at 80 °C for 24 hours. After the reaction was completed, the temperature was lowered to room temperature, and the product was quantitatively analyzed by gas chromatography, with a yield of 86%.

[0054] Example 24 Take 60 mg of pyrimidine-based organic ionic polymer catalyst DT-HIP, accounting for 10 wt% of the reactants, into a 10 mL Schlenk reaction tube, connect it to the CO2-vacuum line, evacuate and fill with CO2 (×10), add 0.60 g of epoxy styrene as reactant using a syringe, stir the reaction at 80 °C for 24 hours, after the reaction is completed, cool to room temperature, and the product is quantitatively analyzed by gas chromatography, with a yield of 76%.

[0055] Comparative Example 1 The difference between this comparative example and Example 1 is that 4-pyridinecarboxaldehyde in step (1) is replaced with 2-methyl-4-pyridinecarboxaldehyde, and the remaining steps are the same as in Example 1. The resulting catalyst catalyzes carbon dioxide and epichlorohydrin with a yield of 77%.

[0056] Comparative Example 2 The difference between this comparative example and Example 1 is that 2,4,6-triaminopyrimidine in step (2) is replaced with melamine, and the remaining steps are the same as in Example 1. The resulting catalyst catalyzes carbon dioxide and epichlorohydrin with a yield of 15%.

[0057] Comparative Example 3 The difference between this comparative example and Example 1 is that the reaction temperature in step (2) is changed to 25°C, while the rest of the steps are the same as in Example 1. The catalyst material preparation failed (no product was obtained).

[0058] Comparative Example 4 The difference between this comparative example and Example 1 is that the reaction temperature in step (2) is changed to 200°C, while the rest of the steps are the same as in Example 1. The resulting catalyst catalyzes carbon dioxide and epichlorohydrin with a yield of 40%.

[0059] Comparative Example 5 The difference between this comparative example and Example 1 is that the reaction time in step (2) is changed to 5 hours, while the rest of the steps are the same as in Example 1. The yield of the catalyst obtained is only 13%, and the yield of catalytic carbon dioxide and epichlorohydrin is 66%.

[0060] Comparative Example 6 The difference between this comparative example and Example 1 is that the reaction time in step (2) is changed to 120 hours, while the rest of the steps are the same as in Example 1. The resulting catalyst catalyzes carbon dioxide and epichlorohydrin with a yield of 86%.

[0061] Comparative Example 7 The difference between this comparative example and Example 1 is that the molar ratio of 2,4,6-triaminopyrimidine to 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide in step (2) was changed from 1:1.5 to 1:0.5. The remaining steps are the same as in Example 1. The yield of the catalyst obtained is only 43%, and the yield of catalytic carbon dioxide and epichlorohydrin is 76%.

[0062] Comparative Example 8 The difference between this comparative example and Example 1 is that the molar ratio of 2,4,6-triaminopyrimidine to 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium)dibromide in step (2) was changed from 1:1.5 to 1:6. The remaining steps were the same as in Example 1. The yield of the catalyst was 58%, and the yield of catalytic carbon dioxide and epichlorohydrin was 86%.

[0063] The catalyst preparation process of this invention is simple, the steps are convenient, the yield is high, the raw materials are readily available, the synthesis cost is controllable, the catalytic carbon dioxide conversion can be carried out under normal pressure, the reaction conditions are relatively mild, the post-processing is simple, the efficiency is high, and it can be produced on a large scale.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A pyrimidin-based ionic polymer catalyst, characterized in that: The catalyst is a pyrimidinyl ionic polymer functionalized with secondary amine and pyridine salts, and its structural formula is shown in formula (1): Equation (1); Where X is selected from Br and Cl.

2. A method for preparing a pyrimidin-based ionic polymer catalyst as described in claim 1, characterized in that: include, Pyridine carboxaldehyde and 1,4-bis(halomethyl)benzene were dissolved in acetonitrile solution, and then reacted at a constant temperature of 25~120℃ for 1~48 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalide. The above-mentioned 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalide and 2,4,6-triaminopyrimidine were dissolved in DMF, mixed evenly, and then transferred to a polytetrafluoroethylene high-pressure reactor. The reaction was carried out at 90~180℃ for 10-100 hours. After cooling to room temperature, the resulting mixture was ground and washed with methanol until colorless. After drying, the pyrimidine-based ionic polymer catalyst was obtained.

3. The preparation method according to claim 2, characterized in that: The pyridine carboxaldehyde includes one of 2-pyridine carboxaldehyde, 3-pyridine carboxaldehyde, and 4-pyridine carboxaldehyde.

4. The preparation method according to claim 2, characterized in that: The 1,4-di(halomethyl)benzene includes one of 1,4-di(chloromethyl)benzene and 1,4-di(bromomethyl)benzene.

5. The preparation method according to claim 2, characterized in that: The molar ratio of 2,4,6-triaminopyrimidine to 1,1′-[1,4-phenylbis(methylene)]bis(4,4′-dipyridinium) dihalide is 1:1~5.

6. The application of the pyrimidin-based ionic polymer catalyst as described in claim 1 in the catalytic conversion of carbon dioxide.

7. The application as described in claim 6, characterized in that: The synthesis of cyclic carbonates by reacting carbon dioxide with epoxides using a pyrimidine-based ionic polymer catalyst involves using a pyrimidine-based organic ionic polymer as a catalyst to synthesize cyclic carbonates through a cycloaddition reaction between epoxides and carbon dioxide. The epoxides include epichlorohydrin, epibromopropane, 1,2-epoxyhexane, 1,2-epoxy-5-hexene, epistyrene, and 2,3-epoxypropylphenyl ether.

8. The application according to claim 7, characterized in that: The amount of the pyrimidin-based ionic polymer catalyst is 1 wt% to 20 wt% of the epoxide.

9. The application according to claim 7, characterized in that: The cycloaddition reaction is carried out at a temperature of 60~150℃, a pressure of atmospheric pressure, and a time of 1~48h.

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