Porous organic polymer catalyst as well as preparation method and application thereof
The porous organic polymer catalyst was prepared by the Pickering emulsion method, which solved the problems of high cost of precious metal catalysts and easy agglomeration of transition metal catalysts, achieved efficient and stable nitrobenzene hydrogenation reaction, and improved the conversion rate and selectivity of the catalyst.
Patent Information
- Application Number
- CN202510793572.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-19
AI Technical Summary
Existing precious metal catalysts are expensive and easily deactivated, transition metal catalysts have poor catalytic selectivity and are prone to agglomeration, and the preparation of porous organic polymers relies on complex templates or surfactants that affect stability, making it difficult to meet industrial needs.
Porous organic polymers were prepared by the Pickering emulsion method, and porous organic polymer catalysts with high specific surface area and suitable pores were prepared through a surfactant-free emulsion curing strategy. Pickering emulsion was used as a template to avoid surfactants. A mixture of vinyl monomers, acrylate monomers and polyacrylates was combined, loaded with nickel salts and catalyst carriers to form a stable porous structure.
The mechanical strength and stability of the catalyst are improved, efficient diffusion in the nitrobenzene hydrogenation reaction is achieved, the conversion rate and aniline selectivity are significantly improved, and the service life of the catalyst is extended.
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Figure CN120665229A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of catalyst preparation, and in particular to a porous organic polymer catalyst and a preparation method and application thereof. Background Art
[0002] In the field of fine chemical preparation, the hydrogenation reaction of nitrobenzene is a core process for producing important chemical products such as aniline. Traditional catalytic systems mostly use precious metal catalysts such as silver (Ag) and platinum (Pt). Although these precious metal catalysts exhibit excellent catalytic activity, they are limited by their high cost and rapid deactivation characteristics, making it difficult to meet the needs of large-scale industrial production. Transition metal nickel (Ni) has become an ideal alternative to precious metal catalysts due to its high catalytic activity and low cost. However, its inherent poor catalytic selectivity and easy agglomeration characteristics seriously restrict the catalytic efficiency and service life in practical applications.
[0003] Porous organic polymers (POPs), with their high surface area and precisely tunable pore structure, provide an ideal platform for loading metal active centers. However, the current preparation of POPs generally relies on complex templates or surfactants. The introduction of surfactants can significantly weaken the mechanical strength of the catalyst, affecting its stability and reusability under industrial reaction conditions. Summary of the Invention
[0004] The present disclosure provides a porous organic polymer catalyst and a preparation method and application thereof, to at least solve the above technical problems existing in the prior art.
[0005] According to a first aspect of the present disclosure, a method for preparing a porous organic polymer catalyst is provided, the method comprising:
[0006] Mixing and stirring a vinyl monomer having a cross-linking function, an acrylate monomer and a polyacrylate until uniform, to obtain an oil phase;
[0007] Dispersing the soluble nickel salt and the catalyst support in deionized water, adding a reducing agent, reacting uniformly, centrifuging, and drying to obtain a nickel-loaded catalyst precursor;
[0008] Dispersing the nickel-loaded catalyst precursor in deionized water, adding a modifier to make the nickel-loaded catalyst precursor hydrophobic, to obtain a first dispersion; dispersing inorganic particles in deionized water, adding a modifier to make the inorganic particles hydrophobic, to obtain a second dispersion;
[0009] uniformly mixing the first dispersion liquid and the second dispersion liquid to obtain an aqueous phase;
[0010] mixing the oil phase and the water phase, and emulsifying them to obtain a Pickering emulsion;
[0011] An initiator is added to the Pickering emulsion, and the mixture is transferred to a reaction container, where a polymerization reaction is carried out under the protection of an inert gas, and a porous organic polymer catalyst is obtained after drying.
[0012] In one embodiment, the vinyl monomer having cross-linking function in the oil phase is at least one of divinylbenzene and styrene;
[0013] The acrylic acid ester monomer is at least one of methyl acrylate and methyl methacrylate;
[0014] The polyacrylate is pentaerythritol triacrylate.
[0015] In one embodiment, in the oil phase, the mass ratio of divinylbenzene, methyl acrylate and pentaerythritol triacrylate is (1-3):(4-7):(1-3).
[0016] In one embodiment, the catalyst support is γ-Al2O3.
[0017] In one embodiment, the mass ratio of the catalyst support to the soluble nickel salt is (1-100):1.
[0018] In one embodiment, in the aqueous phase, the mass ratio of the first dispersion to the second dispersion is 2:1.
[0019] In one embodiment, the mass ratio of the water phase to the oil phase is (3-5):1.
[0020] In one embodiment, the polymerization temperature of the polymerization reaction is 70-90° C., and the polymerization time is 10-15 hours.
[0021] According to a second aspect of the present disclosure, a porous organic polymer catalyst is provided, which is prepared according to the above preparation method.
[0022] According to a third aspect of the present disclosure, there is provided a use of a porous organic polymer catalyst in a nitrobenzene hydrogenation reaction.
[0023] The present disclosure provides a method for preparing a porous organic polymer catalyst, which utilizes Pickering emulsion as a template to prepare a porous structure, thereby preparing a porous organic polymer catalyst with high specific surface area and suitable pores, which is conducive to the efficient diffusion of reactants and products. In addition, through the surfactant-free emulsion curing strategy, the mechanical strength of the catalyst is improved, effectively avoiding the collapse of the pores in the high-pressure reaction. At the same time, the catalyst support has good stability and mechanical strength, and can maintain the structural integrity of the catalyst during the reaction, thereby extending the service life of the catalyst. The catalyst is applied to the hydrogenation reaction of nitrobenzene, and the nickel-loaded catalyst precursor forms a strong electronic interaction with the oxygen-containing functional groups of the organic skeleton, thereby achieving directional activation of the C=O bond in the nitrobenzene hydrogenation reaction, and significantly improving the conversion rate and aniline selectivity.
[0024] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings, in which several embodiments of the present disclosure are shown by way of example and not limitation, wherein:
[0026] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.
[0027] Figure 1 A schematic flow chart of a method for preparing a porous organic polymer according to an embodiment of the present disclosure is shown;
[0028] Figure 2 The emulsion state of POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure before solidification is shown;
[0029] Figure 3 The figure shows the state of POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure after solidification in a catalytic tube;
[0030] Figure 4 Schematic diagram showing the microscopic morphology characteristics of POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure;
[0031] Figure 5 The EDS elemental analysis diagram of POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure is shown;
[0032] Figure 6A comparison of the mechanical strength of POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure and that of the HIPE with span80 added is shown;
[0033] Figure 7 The results of applying the POP-PETA / Ni@HIPE prepared in Example 1 of the present disclosure and the catalysts prepared in Comparative Examples 1-5 in the nitrobenzene hydrogenation reaction (conversion rate and selectivity of the nitrobenzene hydrogenation reaction) are shown. DETAILED DESCRIPTION
[0034] To make the purposes, features, and advantages of the present disclosure more apparent and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative work shall fall within the scope of protection of the present disclosure.
[0035] Porous organic polymers are widely used in the field of catalysts due to their advantages of high specific surface area and controllable pore structure, but existing preparation methods rely on complex templates or surfactants, which will reduce the mechanical strength of the catalyst. In related technologies, the Pickering emulsion method, as an emerging porous material construction technology, uses the characteristics of solid particles to stabilize the emulsion interface, opening up a new path for the preparation of catalyst supports. However, in the catalytic system constructed by this method, the synergistic effect between the metal active sites and the support is weak, resulting in the activity and stability of the catalyst being difficult to meet the stringent requirements of industrial production for high efficiency and long-term operation. Based on this, the development of a preparation method for porous organic polymer catalysts with high activity, low cost and excellent stability is of great significance to promoting the green and efficient development of nitrobenzene hydrogenation processes.
[0036] like Figure 1 The present invention provides a schematic flow diagram of a method for preparing a porous organic polymer catalyst, which comprises the following steps:
[0037] S1. Mix and stir a vinyl monomer having a cross-linking function, an acrylate monomer, and a polyacrylate until uniform, to obtain an oil phase.
[0038] Vinyl monomers provide cross-linking structures, forming a three-dimensional network structure through double bond cross-linking, giving the polymer a certain network skeleton; acrylate monomers participate in the polymerization reaction, adjust the pore size distribution of the polymer, and enhance the formation of through-hole structure; polyacrylates are used to regulate catalytic activity, further regulating the distribution of catalytic active sites through multi-functional group cross-linking, thereby enhancing the functional modification ability of the material.
[0039] In one example, the vinyl monomer is at least one of divinylbenzene (DVB) and styrene.
[0040] The acrylic acid ester monomer is at least one of methyl acrylate (MA) and methyl methacrylate (MMA).
[0041] The polyacrylate is pentaerythritol triacrylate (PETA).
[0042] The mass ratio of divinylbenzene (DVB), methyl acrylate (MA) and pentaerythritol triacrylate (PETA) is (1-3):(4-7):(1-3).
[0043] In one specific example, divinylbenzene (DVB), methyl acrylate (MA), and pentaerythritol triacrylate (PETA) are added to a container in a mass ratio of 1:4:3 and thoroughly mixed using magnetic or mechanical stirring to form a homogeneous, transparent oil phase. DVB acts as a crosslinker, providing a diene structure for forming a three-dimensional network backbone in the subsequent polymerization reaction; MA serves as a primary monomer, building the polymer base segment through double bond polymerization; and PETA, a functional monomer, introduces more active sites through its polyacrylate structure, which can be used to modulate the catalytic activity of the catalyst.
[0044] S2. Dispersing the soluble nickel salt and the catalyst support in deionized water, adding a reducing agent, and after uniform reaction, centrifuging and drying to obtain a nickel-loaded catalyst precursor.
[0045] The mass ratio of catalyst support to soluble nickel salt is (1-100):1. The soluble nickel salt is dissolved in deionized water, the catalyst support is evenly dispersed in the nickel salt solution, and stirred at room temperature to make nickel ions (Ni 2+ ) is adsorbed on the surface of the catalyst support by electrostatic or coordination effects. Then a reducing agent is added to reduce Ni 2 + is reduced to metallic Ni nanoparticles to obtain a nickel-loaded catalyst precursor. Specifically, the reduction reaction is continuously stirred at room temperature. After the reduction is complete, the solid particles are collected by centrifugation and washed multiple times with deionized water and ethanol alternately to remove residual reducing agent and byproducts. Finally, the solid particles are freeze-dried to obtain a nickel-loaded catalyst precursor.
[0046] In one example, the soluble nickel salt is nickel nitrate hexahydrate Ni(NO 3 ) 2 ·6H 2 O, nickel chloride NiCl 2 or other nickel salts.
[0047] The catalyst support can be γ-Al2O3, molecular sieve, zeolite, etc. In this embodiment, γ-Al2O3 is preferably used as the catalyst support. γ-Al2O3 can support Ni nanoparticles and provide catalytic active sites. Furthermore, after hydrophobic modification, γ-Al2O3 can also serve as a stabilizing particle in the subsequent Pickering emulsion.
[0048] In one example, the reducing agent is a NaBH4 solution, or it may be a reducing substance such as vitamin C. The present disclosure does not limit the specific type of the reducing agent.
[0049] S3. Dispersing the nickel-loaded catalyst precursor in deionized water, adding a modifier to make the nickel-loaded catalyst precursor hydrophobic, and obtaining a first dispersion; dispersing inorganic particles in deionized water, adding a modifier to make the inorganic particles hydrophobic, and obtaining a second dispersion.
[0050] The nickel-loaded catalyst precursor prepared in step S2 is uniformly dispersed in deionized water, and then a modifier is added, for example, a sodium oleate solution with a mass fraction of 7 wt% is added as a modifier. Ultrasonic dispersion and stirring are used to allow sodium oleate molecules to be adsorbed on the surface of the nickel-loaded catalyst precursor particles, thereby converting the originally hydrophilic surface of the catalyst support into a hydrophobic state.
[0051] The inorganic particles act as through-holes, allowing the different pores of the prepared porous material to connect. In one example, the inorganic particles are silicon dioxide (SiO2). Similarly, the SiO2 inorganic particles are dispersed in deionized water, and then a modifier is added, such as a 5 wt% solution of cetyltrimethylammonium bromide (CTAB). Ultrasonic dispersion and stirring are used to allow the modifier molecules to adsorb on the surface of the inorganic particles, converting the hydrophilic surface of the inorganic particles to a hydrophobic state.
[0052] S4. Evenly mix the first dispersion liquid and the second dispersion liquid to obtain an aqueous phase.
[0053] In one example, the mass ratio of the first dispersion liquid to the second dispersion liquid is 2:1.
[0054] S5. Mixing the oil phase and the water phase, and emulsifying to obtain a Pickering emulsion.
[0055] The mass ratio of the water phase to the oil phase is (3-5):1. The water phase is slowly added to the oil phase, and the oil phase and the water phase are emulsified in a vortex mixer or oscillator. The hydrophobically modified particles are used to form stable adsorption at the oil-water interface to construct a Pickering emulsion.
[0056] The stability of Pickering emulsions relies on the adsorption and alignment of solid particles at the oil-water interface. The modified SiO2 and modified nickel-loaded catalyst precursor work synergistically to form a denser, more stable particle adsorption layer at the oil-water interface. The two types of particles work together to fill the gaps between them, reducing interfacial tension and preventing the aggregation and coalescence of emulsion droplets. This significantly improves the stability of the Pickering emulsion, ensuring that the emulsion structure is not destroyed during subsequent polymerization reactions and maintaining the uniformity and integrity of the porous structure.
[0057] S6. Add an initiator to the Pickering emulsion, transfer the mixture into a reaction vessel, perform polymerization under the protection of an inert gas, and obtain a porous organic polymer catalyst after drying.
[0058] An initiator is added to the Pickering emulsion prepared in step S5. For example, in this example, the initiator is azobisisobutyronitrile (ABVN). 3 wt% of azobisisobutyronitrile (ABVN) by weight of the oil phase is added to the Pickering emulsion, stirred thoroughly to dissolve, and then transferred to a glass catalytic tube. Nitrogen is introduced into the air 3-5 times to remove oxygen and prevent free radical quenching. The mixture is then polymerized in a constant temperature oil bath at 70-90°C for 10-15 hours. During the reaction, ABVN is thermally decomposed to produce free radicals, which trigger free radical polymerization of DVB, MA, and PETA in the oil phase, forming a porous structure using the Pickering emulsion droplets as a template. After polymerization, the product is washed with deionized water and ethanol to remove unreacted monomers and modifiers, and then vacuum dried, such as at 60°C for 12 hours, to remove the solvent. A porous organic polymer catalyst is finally obtained, the internal pore structure of which is formed by template formation of the emulsion droplets, and the nickel-loaded catalyst precursor particles are uniformly dispersed in the polymer network.
[0059] In the above scheme, Pickering emulsion is used as a template to prepare a porous structure, and a porous organic polymer catalyst with a high specific surface area and suitable pores is prepared, which is conducive to the efficient diffusion of reactants and products. In addition, the mechanical strength of the catalyst is improved through the surfactant-free emulsion curing strategy, effectively avoiding the collapse of the pores during high-pressure reactions. At the same time, the catalyst support has good stability and mechanical strength, which can maintain the structural integrity of the catalyst during the reaction and extend the service life of the catalyst. When this catalyst is applied to the nitrobenzene hydrogenation reaction, the nickel-loaded catalyst precursor forms a strong electronic interaction with the oxygen-containing functional groups of the organic skeleton, achieving directional activation of the C=O bond in the nitrobenzene hydrogenation reaction, and significantly improving the conversion rate and aniline selectivity.
[0060] The present solution will be described in detail below with reference to specific embodiments.
[0061] Example 1
[0062] Step S11: preparing the oil phase.
[0063] Divinylbenzene (DVB, 0.1 g), methyl acrylate (MA, 0.4 g) and pentaerythritol triacrylate (PETA, 0.3 g) were weighed in a mass ratio of 1:4:3, mixed and stirred until uniform and transparent to obtain an oil phase.
[0064] Step S12: preparing the aqueous phase.
[0065] Ni / γ-Al2O3 modification: 20g γ-Al2O3 was dispersed in 80g deionized water to obtain a γ-Al2O3 dispersion with a mass fraction of 20wt%. 10g γ-Al2O3 dispersion (20wt%) was taken, 5g Ni(NO3)2·6H2O was added, dissolved in 10g deionized water, and stirred at 700rpm at 25℃ for 2 hours to make Ni 2 + fully loaded on the γ-Al2O3 surface. Then, 4 g of 0.5 mmol / L NaBH4 solution was added dropwise and stirred for 4 hours to allow the reduction reaction to proceed. After the reaction, the mixture was centrifuged at 8000 rpm for 10 minutes, washed three times with deionized water until neutral, and freeze-dried at -70°C for 24 hours to obtain Ni / γ-Al2O3 powder. The Ni / γ-Al2O3 powder was dissolved in deionized water and modified with 7 wt% sodium oleate to obtain modified Ni / γ-Al2O3 powder.
[0066] SiO2 modification: 50 nm SiO2 nanoparticles were dispersed in deionized water to prepare a colloid with a mass fraction of 5 wt%, and 5 wt% of hexadecyltrimethylammonium bromide (CTAB) was added to modify the SiO2 to obtain modified SiO2 powder.
[0067] Weigh 0.4g of the modified Ni / γ-Al2O3 powder prepared above and disperse it in 9.6g of deionized water. Oscillate the mixture for 2 minutes to obtain a 4wt% modified Ni / γ-Al2O3 dispersion. Weigh 0.2g of the modified SiO2 powder and disperse it in 9.8g of deionized water. Oscillate the mixture for 2 minutes to obtain a 2wt% modified SiO2 dispersion. Mix the modified Ni / γ-Al2O3 dispersion and the modified SiO2 dispersion in a 1:1 ratio to obtain an aqueous phase.
[0068] Step S13 prepares a Pickering emulsion.
[0069] The aqueous phase prepared in step S12 and the oil phase prepared in step S11 were mixed in a mass ratio of 4:1. It should be noted that the aqueous phase was gradually added to the oil phase. For example, when mixing 4 g of aqueous phase with 1 g of oil phase, the aqueous phase was added to the oil phase in 4 times, 1 g each time, and after each mixing, it was shaken with an oscillator or vortex mixer for 2 minutes to finally form a stable high internal phase Pickering emulsion (HIPE).
[0070] After the emulsion was left standing for 24 hours, no delamination occurred. The structure of the prepared Pickering emulsion was characterized using a confocal laser scanning microscope (CLSM, Olympus CKX53) equipped with a 510 nm excitation wavelength laser. Before the experiment, the oil phase was pre-mixed with 0.001 wt% Nile red fluorescent dye, and the microscopic morphology and stability of the emulsion droplets were observed in real time using laser confocal three-dimensional imaging technology. Figure 2 Microscopic observation showed that the droplet size was 50-200 μm, indicating that the Pickering emulsion was successfully prepared.
[0071] Step S14: preparing a porous organic polymer catalyst.
[0072] To the Pickering emulsion prepared in step S13, 3 wt% of azobisisobutyronitrile (ABVN) was added as an initiator, based on the total weight of the oil phase. After thorough stirring, the mixture was transferred to a pressure-resistant glass tube and nitrogen was introduced for 30 minutes to remove oxygen. The tube was then placed in an 80°C oil bath and polymerized at this constant temperature for 12 hours.
[0073] After the polymerization was completed, the product was immersed in ethanol for 48 hours, and the solvent was changed every 12 hours to remove unreacted monomers and surfactants. It was then dried in a vacuum oven at 80°C for 12 hours to obtain a gray porous block catalyst, which was recorded as POP-PETA / Ni@HIPE catalyst. Figure 3 The figure shows the state of the POP-PETA / Ni@HIPE catalyst after solidification in the catalytic tube.
[0074] POP-PETA / Ni@HIPE catalyst structure characterization: Place the dried catalyst sample into the sample cell of the mercury intrusion instrument to ensure that the sample is evenly and tightly packed. Then seal the sample cell and place it in the mercury intrusion instrument. Slowly increase the pressure from normal pressure, first through the low pressure stage, then the high pressure stage, so that mercury enters pores of different sizes, and measure and record the volume of mercury at each pressure. Using the data recorded by the mercury intrusion instrument, parameters such as pore volume, pore size distribution and specific surface area are calculated using relevant equations and software. Characterization results are as follows: Figure 4 shown.
[0075] The specific surface area of the catalyst was measured by mercury intrusion porosimetry and was 23.07 m 2 / g, median pore size of 1140.38nm, volume density of 0.19g / mL, and porosity of 80.82%. Scanning electron microscopy (SEM) shows that the material has a continuous macroporous structure, such as Figure 4 As shown in the middle (a), the pore size is 10-200 μm; Figure 4 The through-hole structure can be seen in Figure (b); Figure 4 As can be seen in Figure (c), Ni / γ-Al2O3 and SiO2 particles are evenly distributed on the pore wall surface.
[0076] Elemental analysis: Through EDS elemental analysis, the characterization results obtained are as follows Figure 5 As shown in the figure, the upper left image shows the porous structure of the POP-PETA / Ni@HIPE surface. This porous structure provides a large specific surface area, providing sufficient sites for the loading of Ni / γ-Al2O3 and SiO2. The distribution images of aluminum elements in the upper right corner (corresponding to Al in γ-Al2O3), silicon elements in the lower left corner (corresponding to SiO2), and nickel elements in the lower right corner (corresponding to Ni) show that these elements are relatively evenly distributed. This means that Ni / γ-Al2O3 and SiO2 as the loading materials are evenly loaded on the POP-PETA / Ni@HIPE surface, which is beneficial to the uniform distribution of the catalyst active sites and has positive significance for improving the catalytic performance and ensuring the consistency of the reaction.
[0077] Mechanical strength test: Through the tensile test, axial tension is applied to the catalyst, and the relationship between stress and strain is measured, which can reflect the mechanical properties of the catalyst during the tensile process. Figure 6 Figure 2 shows a comparison of the mechanical strength of POP-PETA / Ni@HIPE prepared in this example and a catalyst modified with Span80. The horizontal axis represents strain, and the vertical axis represents stress. The catalyst exhibits a 3.35-fold increase in mechanical strength compared to conventional Span80-modified materials (at 75% strain), effectively preventing pore collapse during high-pressure reactions.
[0078] Example 2
[0079] Catalytic Performance Test: To evaluate the performance of the POP-PETA / Ni@HIPE catalyst prepared in Example 1 in the hydrogenation of nitrobenzene, relevant tests were carried out using a PY-GC / MS reactor (model 3050TR-7890B-5977B). The specific process is as follows:
[0080] (1) Construction of reaction device
[0081] This experiment used a tandem micro-pyrolyzer (Rx-3050 TR, Frontier Laboratories, Japan) equipped with a high-pressure module, achieving a maximum pressure of 3.5 MPa. A high-pressure mass flow controller (HP-3050FC) controlled the reaction pressure (BP-1) and the column inlet pressure (BP-2, maintained at a constant 31 kPa). A H2 / He mixture was used during the reaction, with a total gas flow rate of 56 mL / min.
[0082] (2) Setting of detection conditions
[0083] The gas chromatograph was equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD) to ensure comprehensive and accurate detection of reaction products. The injection needle was cleaned with acetone before and after each liquid injection to prevent sample carryover from interfering with subsequent analysis. Reaction products were quantitatively analyzed using external standards, including nitrobenzene, aniline, cyclohexylamine, nitrosobenzene, and azobenzene.
[0084] (3) Reaction parameter setting
[0085] Accurately weigh 20 mg of POP-PETA / Ni@HIPE catalyst and place it in the reaction system. Use a microinjector to accurately pipette 0.4 μL of nitrobenzene as the reaction substrate. Set the reaction temperature to 220°C and maintain the hydrogen pressure at 1 MPa.
[0086] (4) Reaction results
[0087] Under these reaction conditions, detailed analysis of the reaction products revealed 100% nitrobenzene conversion, over 99% aniline selectivity, and no detectable byproducts. This result demonstrates the excellent catalytic activity and selectivity of the POP-PETA / Ni@HIPE catalyst in nitrobenzene hydrogenation, demonstrating its promising industrial application prospects.
[0088] Comparative Example 1
[0089] A method for preparing a POP-PETA / Co@HIPE catalyst is described. Referring to the method for preparing POP-PETA / Ni@HIPE in Example 1, the metal salt in step (2) is replaced with an equal amount of cobalt nitrate (Co(NO3)2·6H2O). The remaining steps and parameters remain unchanged to obtain a POP-PETA / Co@HIPE catalyst.
[0090] Comparative Example 2
[0091] A method for preparing a POP-PETA / Fe@HIPE catalyst is described. Referring to the method for preparing POP-PETA / Ni@HIPE in Example 1, the metal salt in step (2) is replaced with an equal amount of ferric nitrate (Fe(NO3)3·9H2O). The remaining steps and parameters remain unchanged to obtain a POP-PETA / Fe@HIPE catalyst.
[0092] Comparative Example 3
[0093] A method for preparing a POP-PETA / Ag@HIPE catalyst is described. Referring to the method for preparing POP-PETA / Ni@HIPE in Example 1, the metal salt in step (2) is replaced with an equal amount of silver nitrate (AgNO3). The remaining steps and parameters remain unchanged to obtain a POP-PETA / Ag@HIPE catalyst.
[0094] Comparative Example 4
[0095] A method for preparing a POP-PETA / Pt@HIPE catalyst is described. Referring to the method for preparing POP-PETA / Ni@HIPE in Example 1, the metal salt in step (2) is replaced with an equal amount of chloroplatinic acid (H2PtCl6·6H2O). The remaining steps and parameters remain unchanged to obtain a POP-PETA / Pt@HIPE catalyst.
[0096] Comparative Example 5
[0097] A method for preparing a Ni / γ-Al2O3 catalyst comprises dispersing 20g of γ-Al2O3 in 80g of deionized water to obtain a γ-Al2O3 dispersion with a mass fraction of 20wt%. 10g of the γ-Al2O3 dispersion (20wt%) is taken, 5g of Ni(NO3)2·6H2O is added, and the mixture is dissolved in 10g of deionized water. The mixture is stirred at 700rpm for 2 hours at 25°C to allow Ni to dissolve. 2 + was fully loaded on the γ-Al2O3 surface. Subsequently, 4 g of 0.5 mmol / L NaBH4 solution was added dropwise and stirred for 4 hours to allow for reduction. After the reaction, the mixture was centrifuged at 8000 rpm for 10 minutes, washed three times with deionized water until neutral, and freeze-dried at -70°C for 24 hours to obtain the Ni / γ-Al2O3 catalyst.
[0098] Using the same reactor, reaction apparatus, detection conditions and reaction parameters as in Example 2, the catalysts containing different metals prepared in Comparative Examples 1 to 5 were tested for nitrobenzene hydrogenation performance.
[0099] The performance of catalysts containing different metals in the hydrogenation of nitrobenzene varies significantly. The results are as follows (refer to Figure 7 ):
[0100] Comparative Example 1, catalyst containing Co: nitrobenzene conversion decreased to 83.48%, and aniline selectivity decreased to 77.40%;
[0101] Comparative Example 2, Fe-containing catalyst: nitrobenzene conversion decreased to 81.93%, and aniline selectivity decreased to 55.01%;
[0102] Comparative Example 3, Ag-containing catalyst: nitrobenzene conversion decreased to 85.17%, and aniline selectivity decreased to 76.18%;
[0103] Comparative Example 4, Pt-containing catalyst: Although the nitrobenzene conversion rate reached 99.70%, no aniline product was generated, and the main product was cyclohexylamine, accounting for 68.933%.
[0104] Comparative Example 5, Ni / γ-Al2O3 catalyst: Although the conversion rate of nitrobenzene reached 100%, no aniline product appeared, and the main product was cyclohexylamine, accounting for 72.54%.
[0105] Compared with the excellent performance of the POP-PETA / Ni@HIPE catalyst prepared in Example 1, which achieved a nitrobenzene conversion rate of 100%, an aniline selectivity of >99%, and no by-products, catalysts containing other metals had significant disadvantages in both conversion rate and selectivity, fully demonstrating the unique advantages of the POP-PETA / Ni@HIPE catalyst in the nitrobenzene hydrogenation reaction and the key role of metal Ni.
[0106] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not a limitation herein.
[0107] Furthermore, 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 technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means two or more, unless otherwise specifically defined.
[0108] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.
Claims
1. A method for preparing a porous organic polymer catalyst, characterized in that: The method comprises: Mixing and stirring a vinyl monomer having a cross-linking function, an acrylate monomer and a polyacrylate until uniform, to obtain an oil phase; Dispersing the soluble nickel salt and the catalyst support in deionized water, adding a reducing agent, reacting uniformly, centrifuging, and drying to obtain a nickel-loaded catalyst precursor; Dispersing the nickel-loaded catalyst precursor in deionized water, adding a modifier to make the nickel-loaded catalyst precursor hydrophobic, to obtain a first dispersion; dispersing inorganic particles in deionized water, adding a modifier to make the inorganic particles hydrophobic, to obtain a second dispersion; uniformly mixing the first dispersion liquid and the second dispersion liquid to obtain an aqueous phase; mixing the oil phase and the water phase, and emulsifying them to obtain a Pickering emulsion; An initiator is added to the Pickering emulsion, and the mixture is transferred to a reaction container, where a polymerization reaction is carried out under the protection of an inert gas, and a porous organic polymer catalyst is obtained after drying.
2. The preparation method according to claim 1, characterized in that In the oil phase, the vinyl monomer having a cross-linking function is at least one of divinylbenzene and styrene; The acrylic acid ester monomer is at least one of methyl acrylate and methyl methacrylate; The polyacrylate is pentaerythritol triacrylate.
3. The preparation method according to claim 2, characterized in that In the oil phase, the mass ratio of divinylbenzene, methyl acrylate and pentaerythritol triacrylate is (1-3): (4-7): (1-3).
4. The preparation method according to claim 1, characterized in that The catalyst support is γ-Al2O3.
5. The preparation method according to claim 4, characterized in that The mass ratio of the catalyst carrier to the soluble nickel salt is (1-100):
1.
6. The preparation method according to claim 1, characterized in that In the aqueous phase, the mass ratio of the first dispersion liquid to the second dispersion liquid is 2:
1.
7. The preparation method according to claim 1, characterized in that The mass ratio of the water phase to the oil phase is (3-5):
1.
8. The preparation method according to claim 1, characterized in that The polymerization temperature of the polymerization reaction is 70-90° C., and the polymerization time is 10-15 hours.
9. A porous organic polymer catalyst, characterized in that Prepared according to the preparation method according to any one of claims 1 to 8.
10. Use of a porous organic polymer catalyst prepared according to the preparation method according to any one of claims 1 to 8 in nitrobenzene hydrogenation reaction.