Carbon dioxide conversion catalysts, methods of making and using the same

Abstract

The present application relates to a kind of carbon dioxide conversion catalyst and its preparation method and application, carbon dioxide conversion catalyst, with structural unit as general formula (I): Wherein, R1 And R2 It is at least one from H and -CH2-* Respectively independently selected;R3 It is chloromethyl or -CH2-*;N is the integer of >0.The coordination ability of pyridine group in above structure with carbon dioxide is very strong, can form complex, further make carbon dioxide conversion be activated, activated carbon dioxide conversion can form cyclic carbonate with epoxide compound, to realize the conversion catalysis of carbon dioxide.It is also due to the coordination ability of pyridine group in above-mentioned catalyst with carbon dioxide conversion is very strong, above-mentioned catalyst has higher catalytic activity.Meanwhile after once catalytic reaction, recovered catalyst still can maintain higher catalytic activity, can be recycled multiple times, so above-mentioned catalyst has good stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a carbon dioxide conversion catalyst, its preparation method, and its application. Background Technology

[0002] CO2 is a major byproduct of fossil fuel combustion, and excessive emissions into the atmosphere lead to global warming and increased extreme weather events. CO2 is inexpensive, non-toxic, and renewable, making its capture and conversion into value-added chemicals a focus of widespread attention. Among various available chemical reactions for CO2 fixation, the synthesis of cyclic carbonates from CO2 and epoxides is an efficient and environmentally friendly method. Cyclic carbonates can be used as polar aprotic solvents, lithium-ion battery electrolytes, and intermediates in organic synthesis. The synthesis of cyclic carbonates from CO2 and epoxides boasts 100% atom economy; however, due to the demanding reaction conditions, the development of catalysts for this reaction is currently a hot research topic.

[0003] Microporous organic polymers (MOPs) are a class of porous polymer materials with high specific surface area and abundant microporous structures. The polymer molecular chains of MOPs are mainly composed of relatively light elements such as C, N, O, and H. Compared to inorganic porous materials and MOFs, it is easier to introduce various functional groups into the carbon chain, and they exhibit good thermal stability. Therefore, they are often used as catalysts for the catalytic conversion of carbon dioxide. However, current supported catalysts also suffer from poor catalytic activity and easy deactivation of catalytic active sites. Summary of the Invention

[0004] Therefore, it is necessary to provide carbon dioxide conversion catalysts with high catalytic activity and good stability, as well as their preparation methods and applications.

[0005] In a first aspect, the present invention provides a carbon dioxide conversion catalyst having a structural unit of the following general formula (I):

[0006]

[0007] in,

[0008] R1 and R2 are each independently selected from at least one of H and -CH2-*;

[0009] R3 is chloromethyl or -CH2-*;

[0010] n is an integer greater than 0.

[0011] The aforementioned carbon dioxide conversion catalyst possesses a structural unit of general formula (I). The pyridine group in this structural unit has a strong coordination ability with carbon dioxide, forming a complex that activates the carbon dioxide conversion process. The activated carbon dioxide can then form cyclic carbonates with epoxides, thereby achieving the catalytic conversion of carbon dioxide. Because the catalyst contains a pyridine group with a strong coordination ability with carbon dioxide, it exhibits high catalytic activity. Furthermore, after one catalytic reaction, the recovered catalyst still maintains high catalytic activity and can be recycled multiple times, thus demonstrating good stability.

[0012] In some embodiments, the catalyst has a specific surface area of ​​300 m². 2 / g~350m 2 / g.

[0013] In some embodiments, the catalyst has a pore volume of 0.5 m³. 2 / g~0.6m 2 / g.

[0014] In some embodiments, the catalyst has an average pore size of 6 nm to 8 nm.

[0015] A second aspect of this invention provides a method for preparing a carbon dioxide conversion catalyst, comprising the following preparation steps:

[0016] The first intermediate was obtained by amination of chloromethylpyridine hydrochloride and benzimidazole.

[0017] The first intermediate and chloromethylated polystyrene were subjected to a Hoffmann alkylation reaction to obtain the second intermediate;

[0018] The second intermediate and dimethoxymethane were subjected to an electrophilic substitution reaction under the catalysis of a halometallic salt to obtain a carbon dioxide conversion catalyst.

[0019] In some embodiments, the conditions for the amination reaction include: reacting at 20°C to 30°C for 20 to 30 hours;

[0020] The conditions for the Hoffmann alkylation reaction include: reacting at 90℃~100℃ for 20h~30h;

[0021] The electrophilic substitution reaction conditions include: reacting at 40℃~50℃ for 4h~6h, then raising the temperature to 70℃~90℃ and continuing the reaction for 45h~50h.

[0022] A third aspect of the present invention provides the application of the above-mentioned catalyst in the cycloaddition reaction of carbon dioxide and epoxide.

[0023] In some embodiments, the epoxy compound has the following structural formula:

[0024] , or

[0025] R6 is H, alkyl, cycloalkyl, or aryl;

[0026] n1 is an integer greater than 0, and R7 is a halogen or aryloxy group;

[0027] A″ is a cycloalkyl group with at least 3 cyclic carbon atoms.

[0028] In some embodiments, the epoxy compound is selected from at least one of compounds with the following structural formulas:

[0029] , , , , , and .

[0030] In some embodiments, the reaction conditions for the cycloaddition reaction include: a pressure of 0.1 MPa to 2 MPa, a temperature of 60°C to 120°C, and a time of 4 h to 15 h. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0032] Figure 1 Fourier transform infrared spectra of CMPS, CMPS-NHC and HCPs-NHC in Example 1;

[0033] Figure 2 XPS spectrum of HCPs-NHC prepared in Example 1;

[0034] Figure 3 The adsorption-desorption isotherms and pore size distribution diagrams of CMPS, CMPS-NHC and HCPs-NHC in Example 1 are shown.

[0035] Figure 4 The TGA curves of thermogravimetric analysis of CMPS, CMPS-NHC and HCPs-NHC in Example 1, and the temperature statistics tables when the weight loss is 5% and 10%;

[0036] Figure 5 The XRD patterns of CMPS, CMPS-NHC, and HCPs-NHC in Example 1 are shown.

[0037] Figure 6 The TEM image of HCPs-NHC prepared in Example 1 is shown. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] the term

[0042] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0043] The term "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C9 alkyl," refer to alkyl groups containing 1 to 9 carbon atoms, and each occurrence can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, or C9 alkyl.

[0044] The term "cycloalkyl" refers to a non-aromatic hydrocarbon containing a ring of carbon atoms, which can be monocycloalkyl, spirocycloalkyl, or bridged cycloalkyl. Phrases containing this term, such as "C3-C9 cycloalkyl," refer to cycloalkyl compounds containing 3 to 9 carbon atoms, and each occurrence can independently be C3, C4, C5, C6, C7, C8, or C9 cycloalkyl. Suitable examples include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. Additionally, "cycloalkyl" may contain one or more double bonds; representative examples of cycloalkyl compounds containing double bonds include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

[0045] "Aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. It can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic compounds, at least one ring must be an aromatic ring system. For example, "C5-C20 aryl" refers to an aryl group containing 5 to 20 carbon atoms, and each occurrence can be independently C5, C6, C10, C14, C18, or C20. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene, and their derivatives.

[0046] "Aryloxy group" refers to a group formed by replacing an aryl group with at least one oxygen atom, and when an aryloxy group is connected to other groups, the connection site is at an oxygen atom.

[0047] "Halogen" or "halogen group" refers to F, Cl, Br or I.

[0048] * indicates a linking site or fusion site. In this invention, when no linking site is specified in the group, it means that any linkable site in the group is selected as the linking site; in this invention, when no fusion site is specified in the group, it means that any fusionable site in the group is selected as the fusion site, preferably two or more sites in adjacent positions of the group are fusion sites; a non-aromatic ring system refers to a ring system containing at least one non-aromatic ring. In this invention, preferably, the non-aromatic ring system contains only rings formed by carbon-carbon single bonds.

[0049] In this invention, the single bond connecting the substituents extends through the corresponding ring, indicating that the substituent can be connected to any position on the ring, for example... R is attached to any substituted site on the benzene ring.

[0050] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0051] One embodiment of this application provides a carbon dioxide conversion catalyst having a structural unit of the following general formula (I):

[0052]

[0053] in,

[0054] R1 and R2 are each independently selected from at least one of H and -CH2-*;

[0055] R3 is chloromethyl or -CH2-*;

[0056] n is an integer greater than 0.

[0057] The aforementioned carbon dioxide conversion catalyst has a structure as shown in general formula (I). The pyridine group in this structure has a strong coordination ability with carbon dioxide, forming a complex that activates the carbon dioxide. The activated carbon dioxide then reacts with epoxides to form cyclic carbonates, thus achieving the catalytic conversion of carbon dioxide. Because the catalyst contains a pyridine group with a strong coordination ability with carbon dioxide, it exhibits high catalytic activity. Furthermore, after one catalytic reaction, the recovered catalyst still maintains high catalytic activity and can be recycled multiple times, demonstrating good stability.

[0058] In some specific examples, the structural unit of general formula (I) can be one of the following formulas (I-1) to (I-3):

[0059] , and

[0060]

[0061] The carbon dioxide conversion catalyst may have one or more of the structural units of the above formulas (I-1) to (I-3).

[0062] In some examples, when n≥2 and at least one of R1, R2, and R3 is -CH2-*, it indicates that the benzene ring or pyridine ring connected to R1, R2, or R3 can crosslink with other benzene rings or pyridine rings. In some examples, when n>2, R3 is methylene, and R1 and R2 are both H, the benzene ring connected to R3 can crosslink with the same ring in another monomer structure to form a crosslinked network structure.

[0063] In some specific examples, the above-mentioned carbon dioxide catalyst has cross-linked network structural units of the following formulas (I-4) to (I-5);

[0064] ,

[0065]

[0066] In some embodiments, the specific surface area of ​​the catalyst is 300 m². 2 / g~350m 2 / g.

[0067] In some embodiments, the pore volume of the catalyst is 0.5 m³. 2 / g~0.6m 2 / g.

[0068] In some embodiments, the average pore size of the catalyst is 6 nm to 8 nm.

[0069] The catalyst described above contains numerous specific microporous structures, within which carbon dioxide can be adsorbed and enriched. The epoxide can then form hydrogen bonds with the C2 protons of the imidazole groups in the catalyst. Subsequently, carbon dioxide is partially adsorbed by pyridine to form a complex, yielding activated carbon dioxide. Simultaneously, the epoxide reacts with nucleophilic chloride ions to generate chloroalkoxides. These chloroalkoxides then react with the activated carbon dioxide to prepare halocarbonates. Finally, the halocarbonates undergo an intramolecular nucleophilic reaction to form cyclic carbonates, eliminating Cl... - This completes the catalytic cycle. Simultaneously, the catalyst is released and reformed, allowing for recycling.

[0070] One embodiment of this application provides a method for preparing a carbon dioxide conversion catalyst, comprising the following preparation steps S1-S3:

[0071] S1. Chloromethylpyridine hydrochloride and benzimidazole are subjected to an amination reaction to obtain the first intermediate;

[0072] S2. The first intermediate and chloromethylated polystyrene are subjected to a Hofmann alkylation reaction to obtain the second intermediate;

[0073] S3. The second intermediate and dimethoxymethane undergo an electrophilic substitution reaction under the catalysis of a halometallic salt to obtain a carbon dioxide conversion catalyst. Further, the carbon dioxide conversion catalyst possesses the structural unit of the above general formula (I). Further, the first intermediate possesses the structure of the following general formula (II).

[0074] .

[0075] In some embodiments, the second intermediate has a structural unit of the following general formula (III):

[0076]

[0077] R4 and R5 are each independently selected from chloromethyl or -CH2-*.

[0078] The statement "R4 and R5 are independently selected from chloromethyl or -CH2-*" can be understood as follows: when R4 and R5 in the second intermediate are both chloromethyl, it indicates that the structure of the second intermediate polymer contains chloromethyl groups that have not undergone Hoffmann alkylation. When at least one of R4 and R5 is -CH2-*, it indicates that the benzene ring connected to R4 or R5 is cross-linked with other benzene rings on the side chain.

[0079] In some examples, the second intermediate has at least one structural unit of the following general formulas (III-1) and (III-2):

[0080] , .

[0081] In some embodiments, the chlorine atomic mass content in the above-mentioned chloromethylated polystyrene is 13% to 20%.

[0082] In some embodiments, the conditions for the above-mentioned amination reaction include: reacting at 20°C to 30°C for 20 to 30 hours.

[0083] In some embodiments, the above-described amination reaction is carried out in an aqueous solution.

[0084] In some embodiments, a phase transfer catalyst is also required to be added to the conditions of the above-described amination reaction.

[0085] In some embodiments, the addition phase transfer catalyst is at least one of dodecyltrimethylammonium bromide (DTAB) and tetrabutylammonium bromide (TBAB).

[0086] In some embodiments, the conditions for the above-described amination reaction also require the addition of a first basic substance. Adding the first basic substance neutralizes the acidic substances produced during the amination reaction, thereby further promoting the amination reaction process.

[0087] In some embodiments, the first alkaline substance is at least one of sodium hydroxide, potassium hydroxide, or sodium carbonate.

[0088] In some embodiments, step S1 further includes filtering after the amination reaction is completed to obtain a first product, stirring the first product in saturated brine, extracting it with ethyl acetate extractant, removing ethyl acetate by vacuum distillation, and then cooling to precipitate a solid, which is the first intermediate.

[0089] In some embodiments, the conditions for the above-mentioned Hoffmann alkylation reaction include: reacting at 90°C to 100°C for 20 to 30 hours.

[0090] In some embodiments, the Hoffmann alkylation reaction step S2 above further includes: first swelling chloromethylated polystyrene (CMPS) in a first organic solvent, then adding a first intermediate and a second basic substance, and then carrying out the Hoffmann alkylation reaction.

[0091] In some embodiments, the first organic solvent is dimethylformamide.

[0092] In some embodiments, step S2 further includes filtering after the Hoffmann alkylation reaction is completed to obtain a second product, washing the second product sequentially with water and ethanol, purifying it with ethanol in a Soxhlet extractor for 20-28 hours, and then drying it under vacuum at 50-70°C to obtain a second intermediate.

[0093] In a specific example, the Hoffmann alkylation reaction that occurs in step S2 to prepare the second intermediate is shown below:

[0094]

[0095] Note: Some cross-linking structural units of CMPS in the above reaction process are not given.

[0096] In some embodiments, the conditions for the electrophilic substitution reaction include: reacting at 40°C to 50°C for 4 to 6 hours, then raising the temperature to 70°C to 90°C and continuing the reaction for 45 to 50 hours.

[0097] In some embodiments, the electrophilic substitution reaction step further includes: first swelling the second intermediate in a second organic solvent, and then mixing it with dimethoxymethane and a halometallic salt catalyst to carry out the electrophilic substitution reaction.

[0098] In some embodiments, the second organic solvent is selected from 1,2-dichloroethane (DCE), chloroform, or carbon tetrachloride.

[0099] In some embodiments, step S3 above further includes filtering after the electrophilic substitution reaction is completed to obtain a third product, washing the third product sequentially with dilute hydrochloric acid and ethanol, then washing it with ethanol in a Soxhlet still for 45-50 hours, and then drying it under reduced pressure at 50°C to 70°C for 20-26 hours to obtain the carbon dioxide conversion catalyst (HCPs-NHC).

[0100] In some specific examples, the electrophilic substitution reaction that occurs in step S3 is shown below:

[0101]

[0102] In this context, the asterisk (*) in -CH2-* indicates that the methylene group is linked to other benzene or pyridine rings on the side chain.

[0103] A third aspect of the present invention provides the application of the above-mentioned catalyst in the cycloaddition reaction of carbon dioxide and epoxide.

[0104] In some embodiments, the above-mentioned epoxy compound has the following structural formula:

[0105] , or

[0106] R6 is H, alkyl, cycloalkyl, or aryl;

[0107] n1 is an integer greater than 0, and R7 is a halogen or aryloxy group;

[0108] A″ is a cycloalkyl group with at least 3 cyclic carbon atoms.

[0109] In some embodiments, the epoxy compound is selected from at least one of compounds with the following structural formulas:

[0110] , , , , , and .

[0111] In some embodiments, the pressure of the cycloaddition reaction is 0.1 MPa to 2 MPa.

[0112] In some embodiments, the temperature of the cycloaddition reaction is 60°C to 120°C.

[0113] In some embodiments, the cycloaddition reaction takes 4 to 15 hours.

[0114] To make the objectives, technical solutions, and advantages of this invention clearer and more concise, the invention is described using the following specific embodiments, but the invention is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of the invention and can be used to describe the invention, but should not be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0115] To better illustrate the present invention, the following description, in conjunction with specific embodiments, further clarifies the content of the invention. The following are specific embodiments.

[0116] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are commercially available conventional products. The chloromethylated polystyrene (CMPS, CAS No. 55844-94-5) used in this application has a chlorine content of 17.3% and is manufactured by Tianjin Nankai University Chemical Plant.

[0117] Example 1

[0118] 1) Synthesis of the first intermediate

[0119] 2-Chloromethylpyridine hydrochloride (40.63 mmol, 6.70 g) and NaOH (90 mmol, 3.6 g) were added to a round-bottom flask, followed by benzimidazole (33.86 mmol, 4.00 g). Then, 0.13 g of dodecyltrimethylammonium bromide (DTAB) and 50 mL of deionized water were added. The system was stirred at room temperature for 24 h. After the reaction was complete, the product was collected. The product was poured into saturated brine and stirred until homogeneous. The mixture was then extracted three times with ethyl acetate. The ethyl acetate solutions from the three extractions were combined, the solvent was removed under reduced pressure, and the solid precipitated after cooling, yielding intermediate (I). The synthesis reaction of the first intermediate is shown below:

[0120]

[0121] 2) Synthesis of the second intermediate (CMPS-NHC):

[0122] 20 g of chloromethylated polystyrene (CMPS) was swollen in 250 mL of dimethylformamide (DMF) for 24 hours. Then, 14.4 g of the first intermediate and 20.4 g of K₂CO₃ were added, and the mixture was stirred at 95 °C for 24 hours to proceed with the reaction. After the first intermediate was completely consumed, the mixture was cooled to room temperature and then filtered. The resulting crude solid product was washed successively with water and ethanol, and then further purified with ethanol in a Soxhlet extractor for 24 hours. Finally, it was dried under vacuum at 60 °C for 5 hours to obtain the second intermediate (CMPS-NHC). The synthesis reaction of the second intermediate (CMPS-NHC) is shown below:

[0123]

[0124] 3) Synthesis of carbon dioxide conversion catalysts (HCPs-NHC):

[0125] 20 g of the second intermediate (CMPS-NHC) was swollen in 250 mL of 1,2-dichloroethane for 24 hours. Then, 20 g of dimethoxymethane (FDA) and 20 g of FeCl3 were added with stirring. The mixture was stirred evenly at room temperature, and then stirred at 45 °C for 5 hours to form a low-crosslinked intermediate. The mixture was then heated at 80 °C for 48 hours to complete the reaction and form a highly crosslinked product. The resulting product was washed three times with dilute hydrochloric acid and ethanol, then washed with ethanol in a Soxhlet distillation apparatus for 48 hours. Finally, it was dried under reduced pressure at 60 °C for 24 hours to obtain the carbon dioxide conversion catalyst (HCPs-NHC). The synthesis reaction of HCPs-NHC is shown below:

[0126]

[0127] Figure 1 The Fourier transform infrared spectra of CMPS, CMPS-NHC, and HCPs-NHC in Example 1 are shown below, where the horizontal axis represents wavelength (in cm). -1 The vertical axis represents absorption intensity (transmittance, in %), and different substances have different absorption intensities in different wavelength bands. From... Figure 1 It can be observed that it is located at 3022cm. -1 and 2920cm -1 At the wavelength range, CMPS, CMPS-NHC, and HCPs-NHC all exhibit absorption peaks. This is due to the CH extension absorption on the phenyl group and the vibration of the methylene group in the structures of CMPS, CMPS-NHC, and HCPs-NHC.

[0128] Comparing the curves of CMPs with those of CMPS-NHC and HCPs-NHC, it was found that CMPS-NHC and HCPs-NHC were at 1260 cm⁻¹. -1 The C-Cl stretching vibration at the location almost disappeared, indicating that NHC had been successfully grafted into CMPS-NHC and HCPs-NHC; CMPS-NHC and HCPs-NHC were at 1560 cm⁻¹, respectively. -1 1183cm -1 and 1016cm -1 Absorption peaks appeared at all locations, which can be attributed to the C=N extension and CH in-plane bending of the pyridine and imidazole skeletons.

[0129] Furthermore, compared to the infrared spectrum of CMPS, CMPS-NHC exhibits a higher infrared spectrum at 823 cm⁻¹. -1 and 671cm -1 The absorption peak weakens at 754 cm⁻¹, and then decreases to 754 cm⁻¹. -1 A new peak appeared at 823 cm⁻¹; HCPs-NHC reached a peak at 823 cm⁻¹. -1 and 671cm -1 The absorption peak disappears at 754 cm⁻¹, and then disappears at 754 cm⁻¹. -1 The enhanced peak at this point indicates a change in the chemical environment of the aromatic ring.

[0130] Figure 2 XPS spectrum of HCPs-NHC prepared in Example 1, where the horizontal axis represents binding energy (eV) and the vertical axis represents absorption intensity. Figure 2 Figures B, C, and D in the image are high-resolution XPS spectra of HCPs-NHC at different binding energy positions. From... Figure 2 As can be seen, HCPs-NHC exhibits distinct peaks at 284.8 eV, 286.3 eV, and 291.8 eV, primarily attributed to the presence of CC, CN, and π-π* compounds in the HCPs-NHC structure. This indicates that the first intermediate was successfully incorporated into the HCPs-NHC structure. Notably, the peaks at 399.6 eV and 398.9 eV are attributed to imidazole and pyridine, respectively. In the Cl 2p XPS spectrum (… Figure 2 In D), two peaks appear in the relatively high BindingEnergy region, at 199.7 eV and 198.4 eV respectively. These two peaks correspond to the C-Cl bonds of the incompletely polymerized monomers. In the relatively low BE region, the peaks at 197.4 eV and 196.6 eV are attributed to free chloride anions.

[0131] Figure 3 The adsorption-desorption isotherms of CMPS, CMPS-NHC, and HCPs-NHC in Example 1 are shown below. Figure 3 The left image in the figure) and the aperture distribution map ( Figure 3 (See the right figure in the image). In the adsorption-desorption isotherm graph, the horizontal axis represents relative pressure (P / P0), and the vertical axis represents adsorption volume (in cm³). 3 / g); The horizontal axis of the pore size distribution diagram represents pore width (nm), and the vertical axis represents differential pore volume (cm). 3 / g). Table 1 shows the statistical table of specific surface area, pore volume and average pore size parameters of CMPS, CMPS-NHC and HCPs-NHC.

[0132] from Figure 3 As can be seen, the nitrogen adsorption capacity of CMPS-NHC is close to that of CMPS, indicating that the substitution of imidazole salt did not change the porosity. Table 1 shows that the specific surface area of ​​CMPS-NHC (126 m²) is... 2 g -1 Less than CMPS (155 m) 2 g -1 The decrease in specific surface area can be attributed to partial pore filling and simple mass increase. Compared with the adsorption-desorption isotherms of CMPS-NHC and CMPS, the nitrogen adsorption curve of HCPs-NHC at low relative pressure (P / P0 < 0.001) is steeper, reflecting the presence of a richer microporous structure in the polymer (HCPs-NHC) generated by FeCl3-catalyzed alkylation. The final polymer has a larger specific surface area (325 m²). 2 g -1 ) and pore volume (0.558 m 3 g -1 This means that their porosities differ significantly. Figure 3 Aperture distribution diagram in ( Figure 3 As can be seen from the right figure in the figure and the data in Table 1, the pore size distribution of HCPs-NHC is mainly concentrated between 1.2 nm and 3.8 nm, with an average pore width of 7.256 nm.

[0133] Table 1

[0134]

[0135] from Figure 4 Thermogravimetric analysis (TGA) curves of CMPS, CMPS-NHC, and HCPs-NHC from Example 1, along with temperature statistics at weight loss of 5% and 10%, are shown in Example 1. In the TGA curves, the horizontal axis represents temperature (in °C), and the vertical axis represents weight (in %). It can be seen that the three polymers are stable below 200 °C and do not decompose. (HCPs are also mentioned as a carbon dioxide conversion catalyst.) S -NHC can reach a weight loss of 5% at 235℃ and 10% at 251℃, respectively, indicating that the carbon dioxide conversion catalyst of this application has good heat resistance.

[0136] from Figure 5The XRD patterns of CMPS, CMPS-NHC and HCPs-NHC in Example 1 are shown in Example 1. The horizontal axis represents the 2θ (2 Theta) angle and the vertical axis represents the absorption intensity. It can be seen that the above three polymers are amorphous and do not show obvious crystallization.

[0137] from Figure 6 The TEM image of HCPs-NHC prepared in Example 1 shows that there are many alternating bright and dark photoelectric fields, indicating that there are a large number of microporous structures in the carbon dioxide conversion catalyst HCPs-NHC.

[0138] Catalytic application examples:

[0139] Example 2-11

[0140] In Examples 2-11, cyclochloropropane (3g) and a catalyst were added to a 50mL high-pressure stainless steel reactor equipped with a magnetic stirrer. To ensure a sufficient CO2 concentration in the reactor, three gas exchange cycles were performed, and the pressure was then stabilized to a specified value. Subsequently, the reaction mixture was heated to the target temperature and time under stirring. Specific parameters such as the amounts of reactants and catalyst, and reaction conditions for each example are shown in Table 2. The material transformations in the above catalytic reactions are as follows:

[0141]

[0142] After the reaction was complete, the reactor was cooled to 0°C and excess CO2 was carefully removed. A small portion of the reaction mixture was then subjected to proton nuclear magnetic resonance (NMR) analysis in deuterated chloroform (CDCl3). 1 (H NMR), and calculate the yield of cyclic carbonates.

[0143] Comparative Examples 1-2

[0144] Comparative Examples 1 and 2 were prepared using the same method as in Example 10, except for the type of catalyst. Comparative Example 1 used an equal mass of chloromethylated polystyrene (CMPS) as the catalyst, while Comparative Example 2 used an equal mass of the second intermediate (CMPS-NHC) prepared in Example 1 as the catalyst.

[0145] Comparative Example 3

[0146] Comparative Example 3 uses a preparation method that is basically the same as that of Example 10, except that the type of catalyst used is different. Specifically, an equal mass of HCPs-Ph having the following general formula (VII) structural units is used instead of the catalyst in Example 10 of this application:

[0147]

[0148] R4 and R5 are independently selected from chloromethyl or -CH2-*.

[0149] The synthesis method of the chemical catalyst (HCPs-Ph) includes two steps:

[0150] (1) Synthesis of the third intermediate (CMPS-Ph):

[0151] 20 g of chloromethylated polystyrene (CMPS) was swollen in 250 mL of dimethylformamide (DMF) for 24 hours. Then, 14.4 g of N-benzylbenzimidazole and 20.4 g of K₂CO₃ were added, and the mixture was stirred at 95 °C for 24 hours to allow the reaction to proceed. After the N-benzylbenzimidazole was completely consumed, the mixture was cooled to room temperature and then filtered. The resulting crude solid product was washed successively with water and ethanol, and then further purified with ethanol in a Soxh extractor for 24 hours. Finally, it was dried under vacuum at 60 °C for 5 hours to obtain the third intermediate (CMPS-Ph). The synthesis reaction of the third intermediate CMPS-Ph is shown below:

[0152]

[0153] (2) Synthesis of catalyst (HCPs-Ph):

[0154] 20 g of the third intermediate (CMPS-Ph) was swollen in 250 mL of 1,2-dichloroethane for 24 hours. Then, 20 g of dimethoxymethane (FDA) and 20 g of FeCl3 were added with stirring. The mixture was stirred evenly at room temperature, then stirred at 45 °C for 5 hours to form a low-crosslinked intermediate. The mixture was then heated at 80 °C for 48 hours to complete the reaction and form a highly crosslinked product. The resulting product was washed three times with dilute hydrochloric acid and ethanol, then washed with ethanol in a Soxhlet distillation apparatus for 48 hours. Finally, it was dried under reduced pressure at 60 °C for 24 hours to obtain the catalyst (HCPs-Ph). The synthesis reaction of the catalyst (HCPs-Ph) is shown below:

[0155]

[0156] The catalyst components and catalytic reaction conditions used in each embodiment and comparative example are shown in Table 2.

[0157] Table 2

[0158]

[0159] As shown in Table 2, the catalyst HCPs-NHC of this application can achieve the addition reaction of cyclochloropropane with CO2 under relatively low pressure and temperature conditions, with a yield of cyclic carbonate compounds as high as 81%~99%. Furthermore, under the same conditions, the catalytic effect of HCPs-NHC is better than that of the HCPs-Ph catalyst. This indicates that the catalyst HCPs-NHC has good catalytic activity.

[0160] Comparative Example 1, using CMPS as a catalyst, showed a 0% yield of cyclic carbonate compounds, indicating that CMPS has no catalytic effect on the cycloaddition reaction between epichlorohydrin and CO2. Comparative Example 2, using CMPS-NHC as a catalyst, achieved a 60% yield of cyclic carbonate compounds, demonstrating that the catalytic effect of CMPS-NHC is inferior to that of HCPs-NHC. Comparative Example 3, using HCPs-Ph catalyst, achieved an 85% yield of cyclic carbonate compounds, which is lower than the yield of cyclic carbonate compounds in Example 10.

[0161] Examples 12-18

[0162] Examples 12-18 use the same preparation method as Example 10, the only difference being that the epoxides in Examples 12-18 are different from those in Example 10. The specific components of the epoxides used in Examples 12-18 are shown in Table 3 below.

[0163]

[0164] Table 3

[0165]

[0166] As can be seen from Table 3, HCPs-NHC catalysts can realize the reaction of various ethylene oxide compounds with different substituents with CO2, which can improve the application range of CO2.

[0167] Example 19

[0168] A mixture of epichlorohydrin (3 g) and HCPs-NHC catalyst (0.15 g) was added to a 50 mL high-pressure stainless steel reactor equipped with a magnetic stirrer. Three gas exchange cycles were performed to ensure a sufficient CO2 concentration in the reactor, and the pressure was then stabilized to the specified value. The reaction mixture was then heated to 100 °C and reacted at 1.0 MPa for 8 hours with stirring. After cooling the reactor to room temperature and carefully removing excess CO2, a small portion of the reaction mixture was subjected to proton nuclear magnetic resonance (NMR) analysis in CDCl3. 1The conversion rate of epichlorohydrin was determined by ¹H NMR. The catalyst was then recovered by sequentially filtering, washing with ethanol, and drying in a vacuum drying oven for 3.0 hours. The recovered catalyst was then used to repeat the cycloaddition reaction of epichlorohydrin with CO2. The catalyst was recycled 5 times, and the yield of cyclic carbonates in each catalytic reaction is shown in Table 4 below.

[0169] Table 4

[0170]

[0171] As shown in Table 4, the HCPs-NHC catalyst still exhibits good catalytic performance in the epoxidation reaction of epichlorohydrin and CO2 even after being reused 6 times, which also demonstrates the good stability of the catalytic effect of the HCPs-NHC catalyst.

[0172] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A carbon dioxide conversion catalyst, characterized in that, Structural units with the following general formula (I): in, R1 and R2 are each independently selected from at least one of H and -CH2-*; R3 is chloromethyl or -CH2-*; n is an integer greater than 0; the specific surface area of ​​the catalyst is 300 m². 2 / g~350m 2 / g.

2. The catalyst according to claim 1, characterized in that, The catalyst has a pore volume of 0.5 m³. 2 / g~0.6m 2 / g.

3. The catalyst according to any one of claims 1 to 2, characterized in that, The catalyst has an average pore size of 6 nm to 8 nm.

4. A method for preparing a carbon dioxide conversion catalyst, characterized in that, The preparation steps include the following: The first intermediate was obtained by amination of chloromethylpyridine hydrochloride and benzimidazole. The first intermediate and chloromethylated polystyrene were subjected to a Hoffmann alkylation reaction to obtain the second intermediate; The second intermediate and dimethoxymethane were subjected to an electrophilic substitution reaction under the catalysis of a halometallic salt to obtain a carbon dioxide conversion catalyst with a specific surface area of ​​300 m². 2 / g~350m 2 / g.

5. The preparation method according to claim 4, characterized in that, The conditions for the amination reaction include: reacting at 20℃~30℃ for 20h~30h; The conditions for the Hoffmann alkylation reaction include: reacting at 90℃~100℃ for 20h~30h; The electrophilic substitution reaction conditions include: reacting at 40℃~50℃ for 4h~6h, then raising the temperature to 70℃~90℃ and continuing the reaction for 45h~50h.

6. The use of the catalyst according to any one of claims 1 to 3 in the cycloaddition reaction of carbon dioxide and epoxide.

7. The application as described in claim 6, characterized in that, The epoxy compound has the following structural formula. , or R6 is H, alkyl, cycloalkyl, or aryl; n1 is an integer greater than 0, and R7 is a halogen or aryloxy group; A″ is a cycloalkyl group with at least 3 cyclic carbon atoms.

8. The application as described in claim 7, characterized in that, The epoxy compound is selected from at least one of the following compounds with the following structural formulas: , , , , , and .

9. The application as described in any one of claims 6 to 8, characterized in that, The reaction conditions for the cycloaddition reaction include: pressure of 0.1 MPa to 2 MPa, temperature of 60℃ to 120℃, and time of 4h to 15h.

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