Nickel-based bifunctional nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses a nickel-based bifunctional nano-catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) preparing a nickel-based nitrogen-containing porous carbon carrier Ni-NPC; (2) carrying out in-situ polymerization to obtain PSSA < x > / Ni-NPC; and (3) carrying out in-situ reduction to obtain the nickel-based bifunctional nano catalyst NiRu-PSSA < x > / Ni-NPC. According to the present invention, anchoring of the metal site and the acid site on the carrier is precisely regulated, such that the synergistic catalysis bifunctional catalyst having the acid site and the hydrogenation active site is constructed, the catalyst is applied to the esterification-hydrogenation cascade reaction, the reaction efficiency can be effectively improved, and the economic benefit is good.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic materials, and in particular to a nickel-based dual-function nanocatalyst and a preparation method and application thereof. Background Art

[0002] Benzocaine, a local anesthetic, is widely used in clinical medicine and other fields due to its rapid onset of action and low irritation. The traditional preparation method of benzocaine is mainly through an esterification reaction, in which p-aminobenzoic acid and ethanol are reacted in the presence of an acid catalyst to synthesize it. However, the insufficient selectivity of this catalytic system and the difficulty in controlling the process parameters seriously restrict the improvement of production efficiency and product purity. However, p-aminobenzoic acid can be obtained by reduction conversion of inexpensive and readily available p-nitrobenzoic acid, which provides an alternative synthetic route for the synthesis of benzocaine. That is, using p-nitrobenzoic acid, ethanol and hydrogen as raw materials, benzocaine can be synthesized in a one-step series connection through an efficient bifunctional catalyst with both esterification and hydrogenation properties, which can effectively eliminate the need for separation of intermediate products and significantly reduce equipment investment and energy consumption.

[0003] Cyclohexane-1,2-dicarboxylic acid dibutyl ester (CDADE), a leading environmentally friendly plasticizer, exhibits significant benefits in polyolefin processing flexibility and plasticity due to its cyclic backbone and ester group. This structure also mitigates the environmental risks associated with traditional phthalates, demonstrating its potential for application in high-end polymer products such as medical devices. However, the current industrial synthesis of CDADE primarily relies on the esterification of cyclohexane-1,2-dicarboxylic acid with butanol, which presents challenges such as limited raw material availability, difficulty in separation, and potential pollution. Despite ongoing research in China, a large-scale production system has yet to be established, and the product remains heavily reliant on imports. Designing and preparing an efficient bifunctional catalyst with both esterification and hydrogenation capabilities could allow the tandem synthesis of CDADE, the esterification of phthalic anhydride with n-butanol to produce dibutyl phthalate and the hydrogenation of dibutyl phthalate to produce CDADE. This could enable the efficient and green synthesis of CDADE. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a nickel-based bifunctional nanocatalyst and its preparation method and application. By precisely controlling the anchoring of metal sites and acidic sites on the carrier, a bifunctional catalyst with synergistic catalysis of both acidic sites and hydrogenation active sites is constructed. When applied to the esterification-hydrogenation tandem reaction, the reaction efficiency can be effectively improved, with good economic benefits.

[0005] The present invention provides a method for preparing a nickel-based bifunctional nanocatalyst, comprising the following steps:

[0006] 1) Preparation of nickel-based nitrogen-containing porous carbon support Ni-NPC;

[0007] 2) mixing an acidic solution obtained by mixing sodium styrene sulfonate monomer with an ion exchange resin with Ni-NPC; then heating the mixed solution, allowing the sodium styrene sulfonate monomer to react with the ion exchange resin to form polystyrene sulfonic acid, and in situ polymerization of the Ni-NPC and polystyrene sulfonic acid to produce PSSAx / Ni-NPC;

[0008] 3) adding a metal salt to the PSSAx / Ni-NPC and heating it under a nitrogen atmosphere; after cooling to room temperature, sodium borohydride is added dropwise for in situ reduction, followed by washing and vacuum drying to obtain a nickel-based bifunctional nanocatalyst NiRu-PSSAx / Ni-NPC; wherein x is 1, 1.5, 2 or 3.

[0009] Furthermore, in step 1), the preparation of the nickel-based nitrogen-containing porous carbon support Ni-NPC comprises the following steps:

[0010] 11) mixing cellulose powder, NaOH, and urea to obtain a transparent cellulose / NaOH / urea sol;

[0011] 12) adding an inorganic salt aqueous solution of nickel to the cellulose / NaOH / urea sol, stirring, and then heating to fully gelate to obtain a hydrogel;

[0012] 13) freeze-drying the hydrogel, heating it under a nitrogen atmosphere, and then carbonizing it; washing the carbonized product with hydrochloric acid and deionized water in sequence to remove residual chemicals and nickel; and drying it to obtain a nickel-based nitrogen-containing porous carbon support Ni-NPC.

[0013] Furthermore, in step 11), the mass ratio of cellulose powder, NaOH and urea is 1:0.1-5:0.1-10;

[0014] In the step 12), the amount of the nickel inorganic salt aqueous solution added is 2-3 g, 1-20 wt%, and the mixture is stirred for 1-10 h; and the mixture is heated at 35-40° C. for 30-36 h to obtain a hydrogel;

[0015] In the step 13), the hydrogel is freeze-dried at -65 to -55°C for 10 to 100 hours; heated to 300 to 1000°C at a heating rate of 4 to 5°C / min and maintained for 1 to 5 hours for carbonization; and dried at 50 to 60°C for 45 to 48 hours to obtain a nickel-based nitrogen-containing porous carbon support Ni-NPC.

[0016] Furthermore, in step 2), the mixed solution is heated to a temperature of 50-100° C., and an initiator K 2 S 2 O 8 is added.

[0017] Furthermore, in step 2), the mass ratio of Ni-NPC to polystyrene sulfonic acid is 1:1-10.

[0018] Furthermore, in the step 3), the metal salts added are inorganic salts of nickel and inorganic salts of ruthenium, and the molar ratio is 1:0.1-10.

[0019] Furthermore, in the step 3), heating is performed at 50-120° C. for 1-10 h under a nitrogen atmosphere.

[0020] In addition, the present invention also provides a nickel-based bifunctional nanocatalyst prepared by the above-mentioned preparation method.

[0021] In addition, the present invention also provides a use of the above-mentioned nickel-based bifunctional nanocatalyst in catalytic esterification-hydrogenation synthesis reaction.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention designs a bifunctional metal-acid catalyst, in which the acidic site is an esterification site (polystyrene sulfonic acid chain) and the metal site is a hydrogenation site (nano-nickel ruthenium). The two active sites are spatially integrated by utilizing the confinement effect of porous carbon cavities. This catalyst can be applied to the one-step esterification-hydrogenation synthesis of benzocaine from p-nitrobenzoic acid and the one-step esterification-hydrogenation synthesis of dibutyl cyclohexane-1,2-dicarboxylate from phthalic anhydride.

[0024] Cellulose aerogel, a carrier material, provides an ideal platform for constructing nanoscale tandem reactors due to its unique three-dimensional porous network structure, high specific surface area, and confinement effect. Acidic active sites are constructed through interfacial modification with polystyrene sulfonic acid (PSSA), and ruthenium is introduced to form a Ni-Ru bimetallic system. The orderly arrangement of metal sites is achieved through the anchoring effect of the sulfonic acid groups of PSSA; hydrogen activation is synergistically optimized using bimetallic electrons; and mass transfer limitations in multi-step reactions are suppressed by the aerogel confinement effect. The aerogel demonstrates significant advantages in the esterification-hydrogenation tandem reaction, with high catalytic efficiency and good stability, providing a new strategy for the integrated design and green synthesis of multi-step reactions.

[0025] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 is the SEM spectrum of NiRu-PSSA2 / Ni-NPC of Example 1;

[0028] Figure 2 Figure a is a TEM spectrum of NiRu-PSSA2 / Ni-NPC of Example 1, and Figure b is a HRTEM spectrum of NiRu-PSSA2 / Ni-NPC of Example 1;

[0029] Figure 3 Figure a is the SEM spectrum of Ni-NPC of Comparative Example 1, and Figure b is the TEM spectrum of Ni-NPC of Comparative Example 1;

[0030] Figure 4 Figure a is the SEM spectrum of NiRu / Ni-NPC of Comparative Example 2, and Figure b is the TEM spectrum of NiRu / Ni-NPC of Comparative Example 2;

[0031] Figure 5 N2 adsorption-desorption curve and pore size distribution diagram of Ni-NPC of comparative example 1;

[0032] Figure 6 N2 adsorption-desorption isotherm distribution diagram of NiRu-PSSA2 / Ni-NPC of Example 1, Ni-NPC of Comparative Example 1, and NiRu / Ni-NPC of Comparative Example 2;

[0033] Figure 7 1 is a Fourier transform infrared spectra of NiRu-PSSA2 / Ni-NPC of Example 1, Ni-NPC of Comparative Example 1, and NiRu / Ni-NPC of Comparative Example 2;

[0034] Figure 8 XPS Ru 3p spectra of NiRu-PSSA2 / Ni-NPC of Example 1 and NiRu / Ni-NPC of Comparative Example 2;

[0035] Figure 9 The XPS Ni 2p spectra of NiRu-PSSA2 / Ni-NPC of Example 1 and NiRu / Ni-NPC of Comparative Example 2 are shown;

[0036] Figure 10 The XPS N 1s spectra of NiRu-PSSA2 / Ni-NPC of Example 1 and NiRu / Ni-NPC of Comparative Example 2 are shown;

[0037] Figure 11 This is the XPS S2p spectrum of NiRu-PSSA2 / Ni-NPC in Example 1. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0039] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] Please refer to Figures 1 to 11 The embodiment of the present invention provides a method for preparing a nickel-based bifunctional nanocatalyst, comprising the following steps:

[0041] 1) Preparation of nickel-based nitrogen-containing porous carbon support Ni-NPC;

[0042] 11) Mixing cellulose powder, NaOH, and urea in a mass ratio of 1:0.1-5:0.1-10 to obtain a transparent cellulose / NaOH / urea sol (CNUS); preferably, the mass ratio is 1:1.68:2.88;

[0043] 12) adding 2-3 g of an inorganic salt aqueous solution of nickel with a weight percentage of 1-20 wt % to the cellulose / NaOH / urea sol and stirring for 1-10 h, and then heating at 35-40° C. for 30-36 h to fully gelate to obtain a hydrogel;

[0044] 13) freeze-drying the hydrogel at -65 to -55°C for 10 to 100 hours, preferably 48 hours; heating the hydrogel to 300 to 1000°C, preferably 500°C, at a heating rate of 4 to 5°C / min under a nitrogen atmosphere, and maintaining the temperature for 1 to 5 hours, preferably 2 hours, for carbonization; washing the carbonized product with hydrochloric acid and deionized water in sequence to remove residual chemicals and nickel; and drying the product at 50 to 60°C for 45 to 48 hours to obtain a nickel-based nitrogen-containing porous carbon support Ni-NPC;

[0045] 2) mixing an acidic solution obtained by mixing sodium styrene sulfonate monomer with an ion exchange resin with Ni-NPC; then heating the mixed solution at 50-100°C, preferably 75°C, and adding an initiator K2S2O8. The sodium styrene sulfonate monomer reacts with the ion exchange resin to form polystyrene sulfonic acid (PSSA), and the Ni-NPC and the polystyrene sulfonic acid are in situ polymerized to obtain PSSAx / Ni-NPC;

[0046] The mass ratio of Ni-NPC to polystyrene sulfonic acid (PSSA) is 1:1-10, preferably 1:1;

[0047] 3) adding a nickel inorganic salt and a ruthenium inorganic salt in a molar ratio of 1:0.1-10, preferably 1:1, to PSSAx / Ni-NPC, and heating at 50-120°C for 1-10 hours under a nitrogen atmosphere; after cooling to room temperature, sodium borohydride is added dropwise for in situ reduction, followed by washing and vacuum drying to obtain a nickel-based bifunctional nanocatalyst NiRu-PSSAx / Ni-NPC; wherein x is 1, 1.5, 2, or 3;

[0048] The specific surface area of ​​NiRu-PSSAx / Ni-NPC is >100m 2 / g, pore volume>0.1cm 3 / g, pore size>5nm, acidic sites>1mmol / g.

[0049] In this embodiment, the construction of an efficient tandem catalytic system is not only a simple integration of multiple active sites, but also requires the spatiotemporal coordination of the reaction cascade through the precise spatial arrangement of catalytic sites. Studies have shown that an ideal tandem catalyst should have a high density of active sites, reaction intermediates with rapid mass transfer, and kinetically matched step reactions. Cellulose aerogel provides an ideal platform for the construction of nanoscale tandem reactors due to its unique three-dimensional porous network structure, high specific surface area and confinement effect. The abundant hydroxyl groups on the surface of cellulose aerogel can stabilize metal nanoparticles through coordination, and its adjustable pore structure can optimize the mass transfer path of reactants.

[0050] Compared with single catalysts, bimetallic systems can simultaneously enhance catalytic activity, selectivity, and stability through synergistic interactions between metals. In bimetallic catalytic systems, the primary metal acts as the active center, undertaking key catalytic functions, while the auxiliary metal effectively improves the dispersion, sintering resistance, and surface stability of the active components through mechanisms such as electronic regulation (such as charge transfer) or structural modification (such as spatial confinement). In particular, by precisely controlling electron transfer and intermetallic interface structure, bimetallic systems can effectively optimize reactant adsorption strength and hydrogen dissociation kinetics, thereby accelerating the target reaction while suppressing side reaction pathways.

[0051] Nickel metal exhibits excellent intrinsic activity in hydrogenation reactions, but it is susceptible to particle sintering and surface passivation under high-temperature reaction conditions, leading to structural deactivation. Research has demonstrated that constructing a Ni-Ru bimetallic system can produce significant synergistic effects: the ruthenium component inhibits nickel particle migration and aggregation through physical barrier action; ruthenium regulates surface oxygen species adsorption, enhancing antioxidant capacity; and electron transfer from ruthenium to nickel optimizes the d-band center position of the active site, significantly improving catalyst life while maintaining high catalytic activity. This dual advantage of intermetallic electronic regulation and structural stability lays the theoretical foundation for the development of highly efficient tandem catalysts.

[0052] In addition, an embodiment of the present invention further provides a nickel-based bifunctional nanocatalyst prepared by the above-mentioned preparation method.

[0053] In addition, an embodiment of the present invention further provides a use of the above-mentioned nickel-based bifunctional nanocatalyst in catalytic esterification-hydrogenation synthesis reaction.

[0054] Example 1

[0055] Sodium styrene sulfonate monomer was mixed with 0.5 g of ion exchange resin to obtain an acidic monomer; after filtration, the solution was mixed with 0.5 g of Ni-NPC support in a 25 mL round-bottom flask and stirred at room temperature for 24 h; then K2S2O8 (3% mol) was added and heated at 75°C under N2 atmosphere for 12 h; the black product was washed several times with acetone and dried at room temperature to obtain PSSA / Ni-NPC.

[0056] A round-bottom flask was filled with 1 mL of NiCl₂·6H₂O, 1 mL of RuCl₃, 3 mL of H₂O, and Ni-NPC. The mixture was heated at 80°C under a nitrogen atmosphere for 5 h. Then, 1.5 mmol of NaBH₄ methanol solution was slowly added dropwise and stirred at room temperature for 3 h. The NaBH₄ reduction step was repeated once. The final product was washed with methanol and dried at room temperature to obtain NiRu-PSSA₂ / Ni-NPC.

[0057] Comparative Example 1

[0058] 1 g of cellulose powder was added to 12 g of NaOH solution (14 wt %) and stirred in an ice-water bath at 0°C for 1 min; then 12 g of urea solution (24 wt %) was added and stirred for 2 min to obtain a transparent cellulose / NaOH / urea sol (CNUS).

[0059] 2.5g Ni(NO3)2 aqueous solution (10wt%) was added to the above CNUS and stirred for 2h, then heated at 40℃ for 36h to fully gel. The obtained hydrogel was freeze-dried at -65℃ for 48h, then heated to 600℃ at a heating rate of 5℃ / min under N2 atmosphere and maintained for 2h for carbonization. The carbonized product was washed with hydrochloric acid and deionized water in turn to remove residual chemicals and nickel. After drying at 60℃ for 48h, the nickel-based nitrogen-containing porous carbon support Ni-NPC was obtained.

[0060] Comparative Example 2

[0061] A round-bottom flask was filled with 1 mL of NiCl₂·6H₂O, 1 mL of RuCl₃, 3 mL of H₂O, and Ni-NPC. The mixture was heated at 80°C under a nitrogen atmosphere for 5 h. Then, 1.5 mmol of a methanolic NaBH₄ solution was slowly added dropwise, and the mixture was stirred at room temperature for 3 h. The NaBH₄ reduction step was repeated once, and the final product was washed with methanol and dried at room temperature to obtain NiRu / Ni-NPC.

[0062] The catalyst prepared in Example 1 was characterized by SEM, and its SEM spectrum is as follows: Figure 1 As shown in Figure 2, spherical particles with a diameter of approximately 1.6 nm were formed on the surface of the NiRu-PSSA2 / Ni-NPC catalyst, confirming the successful anchoring of the polymer PSSA on the support surface. This unique surface morphology change provides the catalyst with more active sites and mass transfer channels, which has a significant impact on the catalytic performance.

[0063] The catalyst prepared in Example 1 was characterized by TEM, and its TEM spectrum is shown as follows: Figure 2 As shown in Figure 2, polymer nanospheres were observed in the NiRu-PSSA2 / Ni-NPC catalyst, consistent with the SEM results. High-resolution TEM images showed that the lattice spacing of the metal particles was 0.203 nm and 0.208 nm, corresponding to the Ni(111) and Ru(101) crystal planes, respectively, confirming the successful formation of bimetallic nanoparticles.

[0064] Figure 3 The SEM and TEM spectra of the catalyst support (Ni-NPC) prepared in Comparative Example 1 are shown. It can be found that Ni-NPC exhibits a typical porous network structure with uniform pore size distribution.

[0065] Figure 4 The SEM and TEM spectra of the catalyst (NiRu / Ni-NPC) prepared in Comparative Example 2 are shown. The surface of NiRu / Ni-NPC has a slightly wrinkled structure compared to the surface of Ni-NPC, which is due to the increased surface roughness of the support due to the dispersion of metal nanoparticles.

[0066] Figure 5 The N2 adsorption-desorption curve and pore size distribution of the catalyst support (Ni-NPC) prepared in Comparative Example 1 are shown. The N2 adsorption-desorption curve of the catalyst support is a typical type IV isotherm, indicating the presence of a mesoporous structure in the catalyst and a large specific surface area.

[0067] Figure 6The N2 adsorption-desorption isotherms of NiRu-PSSA2 / Ni-NPC of Example 1, Ni-NPC of Comparative Example 1, and NiRu / Ni-NPC of Comparative Example 2 are shown. Due to the loading of metal nanoparticles and the anchoring of polymer, the specific surface area of ​​NiRu-PSSA2 / Ni-NPC is reduced to 86 m 2 / g, but the average pore diameter increases to 11.7nm. This macroporous structure is conducive to the mass transfer of reactants and products and has a positive effect on tandem catalytic reactions.

[0068] Figure 7 The following are the Fourier transform infrared spectra of NiRu-PSSA2 / Ni-NPC of Example 1, Ni-NPC of Comparative Example 1, and NiRu / Ni-NPC of Comparative Example 2. Fourier transform infrared spectroscopy analysis also confirmed the successful anchoring of polymer PPSA. The catalyst NiRu-PSSA / NPC has a peak at 1030 cm -1 The CS stretching vibration peak appeared at 1182 cm -1 , 1122cm -1 and 1008cm -1 The absorption peaks at 3 and 4 are caused by the symmetric and asymmetric stretching vibrations and bending vibrations of O=S=O, respectively. These characteristic peaks prove the presence of sulfonic acid groups, which provide the necessary acid sites for the catalytic esterification-hydrogenation reaction.

[0069] Figure 8 The following are the XPS Ru 3p spectra of NiRu-PSSA2 / Ni-NPC of Example 1 and NiRu / Ni-NPC of Comparative Example 2. In the Ru 3p spectra, the peak around 465.3 eV indicates the presence of RuOx in the catalyst, which is caused by the inevitable partial oxidation of Ru when transferring the catalyst in the XPS test. 3 / 2 and Ru 3p 1 / 2 The binding energies of Ru and Ru shifted from 461.5 and 484.0 eV to 462.8 and 485.1 eV, respectively, indicating that electron transfer occurred from Ru to the carrier.

[0070] Figure 9 The Ni 2p spectra of the catalyst NiRu-PSSA2 / Ni-NPC of Example 1 and the NiRu / Ni-NPC of Comparative 2 are shown in the XPS Ni 2p spectra. The Ni 2p spectra show that there are three valence states of nickel in the catalysts NiRu / NPC and NiRu-PSSA / NPC. The peak at around 852 eV is attributed to the reduced nickel; the peak at around 855 eV is attributed to the Ni in NiO. 2+The characteristic peak of NiRu-PSSA / NPC is located at 861 eV, with a corresponding satellite peak at around 861 eV. Further analysis revealed that the NiO binding energy of NiRu-PSSA / NPC (852.7 eV) is significantly higher than that of NiRu / NPC (851.6 eV), indicating electron transfer from Ni to the support and confirming the presence of a strong metal-support interaction. This electronic interaction helps optimize the electronic structure of the active site and enhance catalytic performance.

[0071] Figure 10 Figure 1 is the XPS N 1s spectrum of NiRu-PSSA2 / Ni-NPC of Example 1 and NiRu / Ni-NPC of Comparison 2. There are three nitrogen species in both the catalyst NiRu / Ni-NPC and NiRu-PSSA2 / Ni-NPC, namely pyridine-N (397.4eV), graphite-N (399.5eV), and oxidation-N (402.7eV). Compared with the catalyst NiRu / Ni-NPC, the binding energy of each nitrogen species in NiRu-PSSA2 / Ni-NPC is significantly shifted (from 397.4eV to 397.9eV, from 399.1eV to 399.7eV, and from 402.8eV to 402.4eV), indicating that the sulfonic acid group of the polymer PPSA interacts electronically with the nitrogen-doped carbon support, resulting in electron deficiency in the nitrogen atom.

[0072] Figure 11 This is the XPS S2p spectrum of NiRu-PSSA2 / Ni-NPC in Example 1. The characteristic peaks at 168.5 and 169.7 eV in the S2p spectrum confirm the presence of -SO3H groups, which provide acidic sites for the esterification reaction.

[0073] Example 2

[0074] p-Nitrobenzoic acid was selected as a substrate for the synthesis of benzocaine. The reaction involved the hydrogenation product, p-aminobenzoic acid, and the esterification product, ethyl 4-nitrobenzoate. The tandem reaction was performed in a stainless steel reactor equipped with an inner lining, mechanical stirring, and an electric heating system. The specific steps are as follows:

[0075] p-Nitrobenzoic acid, 0.05g of catalyst, and ethanol were added sequentially to a 100mL reactor. The reactor was then filled with hydrogen five times to displace the air. The reactor was then pressurized to 1.0MPa with hydrogen, and the temperature was set to 80°C. The reaction was stirred at 400rpm for 1 hour. After the reaction was complete and cooled to room temperature, the product was separated and analyzed using an Agilent 7820A gas chromatograph equipped with a hydrogen flame ionization detector. Its structure was identified using an Agilent 5975C GC-MS. The experimental results showed that the NiRu / NPC catalyst, which was not anchored to PSSA, also exhibited excellent hydrogenation performance, with a p-nitrobenzoic acid conversion rate of >99%, primarily producing p-aminobenzoic acid (78.9%). However, 14.6% of over-hydrogenation byproducts was present.

[0076] After the introduction of PPSA, overhydrogenation was suppressed to a certain extent, and the selectivity of benzocaine increased significantly with the PSSA loading. The benzocaine selectivity of the NiRu-PSSA2 / NPC catalyst increased significantly to 93.2%, and the overhydrogenation byproduct content decreased to 5.3%. However, the higher PSSA loading resulted in lower p-nitrobenzoic acid conversion (93.8%) and benzocaine selectivity (51.2%).

[0077] The best catalyst NiRu-PSSA2 / NPC was subjected to a cyclic stability test. After NiRu-PSSA2 / NPC was recycled five times, the benzocaine yield remained above 85%, confirming the good stability of the catalyst.

[0078] Example 3

[0079] Using phthalic anhydride as the substrate, the performance of different catalysts in the esterification-hydrogenation cascade reaction to synthesize cyclohexane-1,2-dicarboxylic acid dibutyl ester (CDADE) was systematically investigated. The reaction involves two key intermediates: monobutyl phthalate (MBP) and the diester product, dibutyl phthalate (DBP).

[0080] Experimental results show that the unanchored NiRu / NPC catalyst, lacking sufficient acidic sites, cannot effectively catalyze the cascade reaction at 140°C and 6 MPa, resulting in a near-zero yield of the target product, CDADE. However, the introduction of PSSA to construct a bifunctional catalyst significantly improved catalytic performance, with the selectivity of the target product first increasing and then decreasing with increasing PSSA loading.

[0081] The CDADE yield reached 8.7% over the NiRu-PSSA1 / NPC catalyst, and further increased to 32.3% over the NiRu-PSSA2 / NPC catalyst. This performance improvement is attributed to the acidic sites provided by the PSSA, which effectively promote the esterification reaction. Furthermore, the Ni-Ru bimetallic synergy enhances hydrogenation activity.

[0082] Example 4

[0083] The versatility of the NiRu-PSSA2 / NPC catalyst in the esterification-hydrogenation reactions of various substrates was evaluated, as shown in Table 1. The results show that the NiRu-PSSA2 / NPC catalyst exhibits high activity and selectivity for the esterification-hydrogenation of these different compounds, demonstrating the versatility of the catalyst in terms of reaction substrates and confirming its potential for application.

[0084] Table 1 Esterification-hydrogenation performance of different substrates over NiRu-PSSA2 / NPC catalyst

[0085] Serial number reactants product solvent Conversion rate Selectivity 1 Furfural, acetic acid Furfuryl acetate Toluene 83 72 2 Furfural Furfuryl esters Acetic acid 98 29 3 Furoic acid Tetrahydroethyl 2-furoate ethanol 100 99 4 acetaldehyde Ethyl acetate Acetic acid 81 43 5 Butyraldehyde, acetic acid Butyl acetate n-hexane 100 47

[0086] Throughout this specification, terms such as "one embodiment" or "some embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0087] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a nickel-based bifunctional nanocatalyst, characterized in that: The steps include: 1) Preparation of nickel-based nitrogen-containing porous carbon support Ni-NPC; 2) mixing an acidic solution obtained by mixing sodium styrene sulfonate monomer with an ion exchange resin with Ni-NPC; then heating the mixed solution, allowing the sodium styrene sulfonate monomer to react with the ion exchange resin to form polystyrene sulfonic acid, and in situ polymerization of the Ni-NPC and polystyrene sulfonic acid to produce PSSAx / Ni-NPC; 3) adding a metal salt to the PSSAx / Ni-NPC and heating it under a nitrogen atmosphere; after cooling to room temperature, sodium borohydride is added dropwise for in-situ reduction, followed by washing and vacuum drying to obtain a nickel-based bifunctional nanocatalyst NiRu-PSSAx / Ni-NPC; wherein x is 1, 1.5, 2 or 3.

2. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 1, wherein: In the step 1), the preparation of the nickel-based nitrogen-containing porous carbon support Ni-NPC comprises the following steps: 11) mixing cellulose powder, NaOH, and urea to obtain a transparent cellulose / NaOH / urea sol; 12) adding an inorganic salt aqueous solution of nickel to the cellulose / NaOH / urea sol, stirring, and then heating to fully gelate to obtain a hydrogel; 13) freeze-drying the hydrogel, heating it under a nitrogen atmosphere, and then carbonizing it; The carbonized product is washed with hydrochloric acid and deionized water in sequence to remove residual chemicals and nickel; after drying, a nickel-based nitrogen-containing porous carbon support Ni-NPC is obtained.

3. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 2, wherein: In the step 11), the mass ratio of cellulose powder, NaOH and urea is 1:0.1-5:0.1-10; In the step 12), the amount of the nickel inorganic salt aqueous solution added is 2-3 g, 1-20 wt%, and the mixture is stirred for 1-10 h; and the mixture is heated at 35-40° C. for 30-36 h to obtain a hydrogel; In the step 13), the hydrogel is freeze-dried at -65 to -55°C for 10 to 100 hours; heated to 300 to 1000°C at a heating rate of 4 to 5°C / min and maintained for 1 to 5 hours for carbonization; and dried at 50 to 60°C for 45 to 48 hours to obtain a nickel-based nitrogen-containing porous carbon support Ni-NPC.

4. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 1, wherein: In the step 2), the mixed solution is heated to a temperature of 50-100° C., and an initiator K 2 S 2 O 8 is added.

5. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 1, characterized in that: In the step 2), the mass ratio of Ni-NPC to polystyrene sulfonic acid is 1:1-10.

6. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 1, characterized in that: In the step 3), the added metal salts are an inorganic salt of nickel and an inorganic salt of ruthenium, and the molar ratio is 1:0.1-10.

7. The method for preparing the nickel-based bifunctional nanocatalyst according to claim 1, characterized in that: In the step 3), heating is performed at 50-120° C. for 1-10 h under a nitrogen atmosphere.

8. A nickel-based bifunctional nanocatalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the nickel-based bifunctional nanocatalyst according to claim 8 in catalytic esterification-hydrogenation synthesis reaction.

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