Preparation and application of a Cu-based functional ionized polymer

Abstract

This invention discloses a method for preparing a Cu-based functional ionized polymer and its application in the catalytic hydrogenation of CO2 to ethanol. The method involves polymerizing a benzylimidazolium monomer with a monomer containing a halogenated methyl polycyclic ring in a solvent to obtain an ionized polymer. This polymer is then functionalized with a pyridyl anion after ion exchange, and finally loaded with Cu to obtain the Cu-based functional ionized polymer. The Cu-based functional ionized polymer obtained by this invention not only possesses the ability to activate CO2 and H2, but also the ability to selectively generate corresponding intermediates to trigger C-C coupling. Therefore, it can achieve nearly 100% ethanol selectivity under mild conditions during the catalytic hydrogenation of CO2, exhibiting advantages such as high ethanol selectivity, simple preparation process, and low cost. This contributes to my country's world-leading position in the sustainable catalytic hydrogenation of CO2 to ethanol.

Description

Technical Field

[0001] This invention relates to the field of ionized polymer complexation of metal ions and CO2 hydrogenation catalysis, specifically to a method for preparing a Cu-based functional ionized polymer and its application in the catalytic hydrogenation of CO2 to ethanol. Background Technology

[0002] With the rapid development of industry, a large amount of fossil energy is being rapidly consumed, resulting in the emission of more than 30 billion tons of carbon dioxide (CO2) into the environment every year, and the greenhouse effect caused by it has attracted much attention. Therefore, the efficient capture and utilization of CO2 is of strategic significance. Among them, the conversion of carbon dioxide into high-value-added chemicals or fuels, such as alcohols, alkanes, alkenes, and acetone, has greatly attracted the interest of scientists. Among the hydrogenation products of CO2, ethanol has received widespread attention not only as a disinfectant and solvent, but also as a fuel additive. At present, the process of producing ethanol by CO2 hydrogenation mainly faces the following key problems: (1) CO2 is a thermodynamically stable and kinetically inert molecule with low reactivity; (2) it is difficult to obtain both surface alkyl groups and C(H)O by dissociation and non-dissociation adsorption of CO bonds; (3) the complex reaction route and the difficulty of CC coupling result in low CO2 conversion rate and selectivity. Therefore, developing high-performance catalysts for the production of ethanol by CO2 hydrogenation is a very challenging task.

[0003] Currently, catalysts for CO2 hydrogenation to ethanol are mainly divided into noble metal catalysts and non-noble metal catalysts. Noble metal catalysts mainly include Rh, Pt, Pd, and Au, but their CO2 conversion rates are relatively low, and their high cost makes them difficult to apply industrially. In contrast, non-noble metal catalysts such as Cu, Co, and Fe have attracted widespread attention due to their wide availability, low cost, and higher CO2 conversion rates. Cu-based catalysts, in particular, can not only activate hydrogen to promote CO2 hydrogenation reduction but also fix intermediate products, exhibiting good catalytic performance in the preparation of alcohols. Furthermore, Cu-based catalysts have a significant price advantage and are therefore widely used in research on CO2 hydrogenation to ethanol. Cu-based catalysts still face several challenges in the catalytic hydrogenation of CO2 to ethanol: First, Cu needs to be highly dispersed to exhibit good catalytic performance, but traditional metal oxide supports are prone to Cu agglomeration during continuous use, leading to catalyst deactivation. Second, Cu-based catalysts require the addition of good promoters to activate CO2 and enable them to simultaneously possess the ability to dissociate and non-dissociate CO bonds. Furthermore, the performance of catalyzing carbon-carbon coupling processes using only Cu as a single catalytic site is very limited, and further design is still needed. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a Cu-based functional ionized polymer with highly selective catalytic CO2 hydrogenation to ethanol and a method for preparing the same.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A Cu-based functional ionized polymer, the preparation method of which includes the following steps:

[0007] 1) A benzylimidazolium monomer and a monomer containing a halogenated methyl polycyclic ring are polymerized in a solvent to obtain an ionized polymer;

[0008] 2) After ion exchange, the obtained ionized polymer is functionalized with pyridyl anions and then loaded with Cu to obtain the Cu-based functionalized ionized polymer.

[0009] Further, the benzylimidazolium monomer mentioned in step 1) includes at least one of 1,4-bis[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-triimidazolylbenzene, 1,3,5-tris(4-imidazolylphenyl)amine, and 1,3,5-tris(4-imidazol-1-yl)phenyl)benzene.

[0010] Further, the halogenated methyl polycyclic monomer mentioned in step 1) includes at least one of 1,3,5-tris(bromomethyl)benzene, 1,2,4,5-tetra(bromomethyl)benzene, cyanuric chloride, and 4,4-biphenyl dichlorobenzyl.

[0011] Further, the molar ratio of the benzylimidazolium monomer to the halogenated methyl polycyclic monomer used in step 1) is 100:1 to 1:100.

[0012] Further, the solvent mentioned in step 1) includes at least one of acetonitrile, toluene, water, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and N-methylpyrrolidone.

[0013] Furthermore, the polymerization reaction in step 1) is carried out at a temperature of 10-300 °C for a time of 0.1-72 h.

[0014] Further, the ion exchange described in step 2) involves immersion in a 0.01-10 mol / L NaOH solution for 0.1-1000 h followed by washing until neutral.

[0015] Further, the functionalization described in step 2) involves mixing the ion-exchanged polymer with a compound containing a pyridyl anion in water and reacting at 10-200 °C for 0.1-72 h.

[0016] Furthermore, the compound containing the pyridyl anion is at least one of 2-aminopyridine, 2-hydroxypyridine, 2-mercaptopyridine, and 2-pyridinemethanol.

[0017] Furthermore, the amount of the compound containing the pyridyl anion is calculated based on a molar ratio of 1:1 to 1:1000 between the ion-exchanged polymer and the pyridyl anion.

[0018] Furthermore, in step 2), Cu loading is performed by adsorption, using a solution with a copper ion content of 1-100,000 ppm.

[0019] Furthermore, the Cu loading in the obtained Cu-based functional ionized polymer is 0.01-100 wt%.

[0020] The anionic functionalized polymer of this invention not only has the function of fixing and activating CO2, but also the lone pair electrons on the anion can interact with Cu. 2+ Coordination complexes are formed to create specific coordination sites, which stably load Cu into the ionized framework and provide substrate activation sites. Under the combined action of the anionic basic sites and the formed Cu coordination active centers, Cu-based functional ionized polymers not only have the ability to activate CO2 and H2, but also can selectively generate corresponding intermediates to trigger CC coupling, thus making them suitable for CO2 hydrogenation to ethanol.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) The Cu-based functional ionized polymer prepared in this invention activates CO2 and H2 by means of the catalytic active center formed by the functionalized anion and Cu coordination, achieving the effect of highly efficient catalytic hydrogenation of CO2 and highly selective preparation of ethanol. It can achieve nearly 100% ethanol selectivity under mild conditions during the catalytic hydrogenation of CO2, and has the advantages of high ethanol selectivity, simple preparation process and low cost, which are significantly better than all types of catalysts currently published.

[0023] (2) The preparation conditions of the polymer of the present invention are mild and the preparation process is simple. It is a multifunctional catalyst that can be used for large-scale production. Attached Figure Description

[0024] Figure 1 The reaction flow diagram for preparing Cu-based functional ionized polymer C and Cu-based ionized polymer D is shown in the example.

[0025] Figure 2 Infrared spectra of functional ionized polymer B and Cu-based functional ionized polymer C prepared for the examples.

[0026] Figure 3This is a comparison chart of the catalytic performance of ionized polymer A, functional ionized polymer B, Cu-based functional ionized polymer C, and Cu-based ionized polymer D in the application examples.

[0027] Figure 4 In-situ infrared diffuse reflectance of the Cu-based functionalized ionized polymer C-catalyzed CO2 hydrogenation process in the application examples ( in-situ DRIFTS map.

[0028] Figure 5 The images show scanning electron microscope (SEM) and transmission electron microscope (TEM) images of Cu-based functional ionized polymer C before (left) and after (right) catalytic CO2 hydrogenation in the application examples.

[0029] Figure 6 The figure shows the effect of different Cu loadings on the catalytic performance of Cu-based work ionization polymer C in the application examples. Detailed Implementation

[0030] A Cu-based functional ionized polymer, the preparation of which includes the following steps:

[0031] 1) Add benzylimidazolium monomer and halogenated methyl polycyclic monomer to solvent at a molar ratio of 1:100-100:1, and polymerize at 10-300 °C for 0.1-72 h. Then filter and dry the product to obtain ionized polymer.

[0032] 2) The obtained ionized polymer was impregnated with 0.01-10 mol / L NaOH solution for 0.1-1000 h and washed until neutral. Then, the ion-exchanged polymer and the compound containing pyridyl anion were mixed in water at a molar ratio of polymer to pyridyl anion of 1:1-1:1000. The mixture was reacted at 10-200 °C for 0.1-72 h, filtered, dried, and then adsorbed in a solution with a copper ion content of 1-100000 ppm to obtain a Cu-based functional ionized polymer with a loading of 0.01-100 wt%.

[0033] The benzylimidazolium monomer comprises at least one of 1,4-bis[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-triimidazolylbenzene, 1,3,5-tris(4-imidazolylphenyl)amine, and 1,3,5-tris(4-imidazol-1-yl)phenyl)benzene. The halogenated methyl polycyclic monomer comprises at least one of 1,3,5-tris(bromomethyl)benzene, 1,2,4,5-tetra(bromomethyl)benzene, cyanuric chloride, and 4,4-biphenyl dichlorobenzene. The solvent comprises at least one of acetonitrile, toluene, water, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and N-methylpyrrolidone. The compound containing a pyridyl anion is at least one of 2-aminopyridine, 2-hydroxypyridine, 2-mercaptopyridine, and 2-pyridinemethanol.

[0034] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto. Example

[0035] 1) Preparation of functionalized ionized polymer B:

[0036] 3.56 g of 1,4-bis[(1H-imidazol-1-yl)methyl]benzene, 3.56 g of 1,3,5-tris(bromomethyl)benzene, and 30 ml of acetonitrile were added to a 100 mL pressure-resistant flask. The mixture was placed in a magnetic stirrer and reacted at 70 °C for 20 h. Then, 30 ml of deionized water was added, and the reaction was continued at 70 °C for another 4 h. After filtration, the obtained solid was dried to obtain 7.0 g of ionized polymer A. Immersed the obtained ionized polymer A in 50 ml of 1 M NaOH solution for 8 h, then filtered. The obtained solid was washed with deionized water until neutral, then mixed with 2.0 g of 2-hydroxypyridine and 30 ml of water. The mixture was reacted at room temperature for 24 h, then filtered. The obtained solid was freeze-dried to obtain functional ionized polymer B.

[0037] 2) Preparation of Cu-based functionalized ionized polymers:

[0038] 50 mL, 2000 mg L -1 Copper nitrate solution was added to the prepared ionized polymer A and functional ionized polymer B, respectively. After reacting at room temperature for 24 h, the supernatant was removed by centrifugation to obtain a blue-green solid. After washing three times with deionized water, the solid was freeze-dried for 24 h to obtain Cu-based functional ionized polymer C and Cu-based ionized polymer D with a Cu loading of 5.6 wt%.

[0039] Figure 3The infrared spectra of the prepared functional ionized polymer B and Cu-based functional ionized polymer C are shown in the figure. As can be seen from the figure, compared with functional ionized polymer B, Cu-based functional ionized polymer C has a higher infrared spectrum at 1354 cm⁻¹. -1 and 1381 cm -1 A stretching vibration peak indicating CN-Cu appears at 1509 cm⁻¹. -1 and 1258 cm -1 The presence of stretching vibration peaks indicating CO-Cu suggests that Cu coordinates with N and O, which have lone pairs of electrons on the anions, to form special structures.

[0040] Application Examples

[0041] 1. Under catalytic conditions of 150 °C, 4 MPa (gas ratio H2:CO2:Ar=66:22:12, v / v / v), 5 mL of 1,4-dioxane as solvent, 0.2 g of catalyst, and 8 h of reaction time, the catalytic performance of ionized polymer A obtained in the comparative examples, functionalized ionized polymer B without Cu loading, Cu-based functionalized ionized polymer C, and Cu-based ionized polymer D without anion functionalization but loaded with Cu was compared for CO2 hydrogenation to ethanol. The results are shown in [Figure number missing]. Figure 3 .

[0042] As shown in the figure, ionized polymer A, unsupported Cu functionalized ionized polymer B, and Cu-based ionized polymer D exhibited virtually no catalytic activity. In contrast, Cu-based functionalized ionized polymer C achieved a 5.9% CO2 conversion and 100% ethanol selectivity in the catalytic hydrogenation of CO2, with an ethanol space-time yield (STY) of 0.29 mmol g. -1 h -1 It exhibited excellent catalytic activity and ethanol selectivity, which fully demonstrates that the special structure formed by the coordination of Cu with anionic functionalized polymers and Cu presents unique catalytic performance for the hydrogenation of CO2 to ethanol.

[0043] 2. The Cu-based functionalized ionizing polymer C obtained in the examples was applied to a fixed-bed reactor at a temperature of 150°C, a reaction pressure of 4 MPa (gas ratio of H2:CO2:Ar = 72:24:4, v / v / v), and a flow rate of 10 mL·min. -1 Under catalytic conditions with a catalyst dosage of 0.2 g, the CO2 conversion rate was 3.7%, the ethanol selectivity was 95.6%, the methanol selectivity was 4.4%, and there were no other gaseous products (including CO, CH4, etc.), further demonstrating its excellent catalytic performance.

[0044] Figure 4In-situ infrared diffuse reflectance of Cu-based functionalized ionized polymer C-catalyzed CO2 hydrogenation process ( in- situ DRIFTS spectrum. The process of CO2 hydrogenation catalyzed by Cu-based functionalized ionized polymer C. in-situ The DRIFTS spectrum reveals characteristic peaks of CO2 activation by basic sites and Cu catalytic sites, as well as peaks of characteristic groups such as COOH*, HCOOH*, HCO*, *H2COH, and CH3* generated during CO2 hydrogenation. This further demonstrates that the Cu-based functional ionized polymer catalyzes the highly selective preparation of ethanol from CO2 hydrogenation under the synergistic effect of basic sites and Cu catalytic sites, and its catalytic pathway may be: CO2→COO*→*COOH→HCOOH*→HCO*→*H2COH→CH3OH*→CH3*→CH3CH2OH.

[0045] Figure 5 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the Cu-based functionalized ionized polymer before (left) and after (right) CO2 hydrogenation catalyzed by C. As can be seen from the images, the microstructure of the polymer remains essentially unchanged before and after the reaction, indicating its good recyclability in the reaction.

[0046] Figure 6 The figure compares the catalytic performance of Cu-based functionalized ionized polymer C with different Cu loadings in the hydrogenation of CO2 to ethanol under the following conditions: temperature 150 °C, pressure 4 MPa (gas ratio H2:CO2:Ar=66:22:12, v / v / v), solvent 5 mL of 1,4-dioxane, catalyst dosage 0.2 g, and reaction time 8 h. As can be seen from the figure, when the Cu loading is 5.6 wt%, higher ethanol selectivity is observed, possibly due to more complete coordination between Cu and the anion. This indicates that the synergistic effect of the two sites is key to obtaining high ethanol selectivity.

[0047] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. Use of a Cu-based functional ionic polymer in the production of ethanol by hydrogenation of CO2, characterized in that, The preparation of the Cu-based functional ionized polymer includes the following steps: 1) A benzylimidazolium monomer and a monomer containing a halogenated methyl polycyclic ring are polymerized in a solvent to obtain an ionized polymer; 2) After ion exchange, the obtained ionized polymer is functionalized with pyridyl anions and then loaded with Cu to obtain the Cu-based functionalized ionized polymer. The benzylimidazolium monomer comprises at least one of 1,4-bis[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene, 1,3,5-triimidazolylbenzene, 1,3,5-tris(4-imidazolylphenyl)amine, and 1,3,5-tris(4-imidazol-1-yl)phenyl)benzene; The halogenated methyl polycyclic monomer includes at least one of 1,3,5-tris(bromomethyl)benzene, 1,2,4,5-tetra(bromomethyl)benzene, cyanuric chloride, and 4,4-biphenyl dichlorobenzyl. The compound containing the pyridyl anion is at least one of 2-aminopyridine, 2-hydroxypyridine, 2-mercaptopyridine, and 2-pyridinemethanol.

2. Use according to claim 1, characterized in that, The molar ratio of benzylimidazolium monomer to halogenated methyl polycyclic monomer used in step 1) is 100:1 to 1:

100.

3. The application according to claim 1, characterized in that, The solvent mentioned in step 1) includes at least one of acetonitrile, toluene, water, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, and N-methylpyrrolidone.

4. The application according to claim 1, characterized in that, The polymerization reaction in step 1) is carried out at a temperature of 10-300℃ for a time of 0.1-72 h.

5. The application according to claim 1, characterized in that, The ion exchange described in step 2) involves immersing the sample in a 0.01-10 mol / L NaOH solution for 0.1-1000 h and then washing it until it is neutral.

6. The application according to claim 1, characterized in that, The functionalization described in step 2) involves mixing the ion-exchanged polymer with a compound containing pyridyl anions in water and reacting at 10-200 °C for 0.1-72 h; the amount of the compound containing pyridyl anions is calculated based on a molar ratio of polymer to pyridyl anions of 1:1-1:1000.

7. The application according to claim 1, characterized in that, In step 2), Cu loading is performed by adsorption using a solution with a copper ion content of 1-100,000 ppm.

8. The application according to claim 1, characterized in that, The Cu loading in the obtained Cu-based functional ionized polymers ranged from 0.01 to 100 wt%.

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