Method for selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde

Abstract

This invention provides a method for the selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and a 2D amorphous semiconductor hybrid nanostructure catalyst. The method includes: the preparation of p-aminobenzaldehyde by hydrogenation of the raw material p-nitrobenzaldehyde under specific solvent (anhydrous ethanol), catalyst Pt / @-ZrO2 / MCM-22, and preset hydrogenation reaction conditions. The preset hydrogenation reaction conditions include: hydrogen pressure of 0.7 MPa to 0.9 MPa, reaction temperature of 50°C to 70°C, and reaction time of 60 min to 80 min. The Pt / @-ZrO2 / MCM-22 catalyst contains 0.07 to 0.2 wt% Pt, and the ZrO2 in the catalyst is a 2D amorphous semiconductor film that spontaneously spreads as a monolayer within the pores of the MCM-22 molecular sieve, while the active component Pt is anchored on the ZrO2 film. The method provided by this invention can achieve 100% conversion of p-nitrobenzaldehyde and selectivity for p-aminobenzaldehyde under mild reaction conditions, and has the advantages of low Pt loading of active component, low catalyst dosage, and high catalytic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for the selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde. Background Technology

[0002] Catalytic hydrogenation is a core process in many industries, with approximately 25% of chemical processes involving at least one catalytic hydrogenation step. As the most widely used reaction in chemical manufacturing, hydrogenation remains one of the most extensive research areas in catalysis. The products of catalytic hydrogenation have wide applications in chemistry, pharmaceuticals, food, coatings, and petrochemical materials, among others. Statistics show that catalysts are used in over 90% of chemical processes.

[0003] In hydrogenation reactions, the most commonly used catalysts are traditional metal catalysts with metals directly supported on a support. Their activity is often affected by the size, dispersion, and morphology of the metal particles, making it difficult to simultaneously achieve high catalytic activity and selectivity. In recent years, three types of catalysts have been developed: oxide-like catalysts, organic-inorganic hybrid catalysts, and single-atom catalysts. Compared with traditional metal catalysts, these catalysts have higher activity and selectivity. Single-atom catalysts, in particular, have high stability, but they still have problems such as low loading and easy aggregation of single atoms. Summary of the Invention

[0004] This invention employs a reduction method under ultraviolet light to prepare a Pt / @-ZrO2 / MCM-22 catalyst, a hybrid nanostructure of metal Pt and 2D amorphous semiconductor. The Pt / @-ZrO2 / MCM-22 catalyst is then applied to the hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde. Under mild reaction conditions, 100% conversion and 100% selectivity are achieved. This method offers advantages such as low Pt loading, low Pt consumption, mild reaction conditions, high catalytic efficiency, and environmental friendliness and energy saving, demonstrating promising prospects for industrial application.

[0005] To achieve the above objectives, this invention provides a method for the selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a Pt / @-ZrO2 / MCM-22 catalyst. The method includes: under specific solvent, catalyst, and predetermined hydrogenation reaction conditions, p-nitrobenzaldehyde is hydrogenated to obtain p-aminobenzaldehyde. The specific solvent is anhydrous ethanol, the catalyst is a Pt / @-ZrO2 / MCM-22 catalyst, and the predetermined hydrogenation reaction conditions include: hydrogen pressure... The reaction pressure is 0.7 MPa to 0.9 MPa, the reaction temperature is 50℃ to 70℃, and the reaction time is 60 min to 80 min. The Pt / @-ZrO2 / MCM-22 catalyst contains 0.07 to 0.2 wt% Pt. In the Pt / @-ZrO2 / MCM-22 catalyst, ZrO2 is a 2D amorphous semiconductor film that spontaneously spreads as a monolayer within the pores of the MCM-22 molecular sieve, while the active component Pt is anchored on the ZrO2 film.

[0006] In one specific embodiment, the molar ratio of Pt to p-nitrobenzaldehyde in the Pt / @-ZrO2 / MCM-22 catalyst is 0.04%-0.14%.

[0007] In one specific embodiment, the preset hydrogenation reaction conditions include: the hydrogen pressure is 0.7 MPa, the reaction temperature is 50°C, and the reaction time is 60 min.

[0008] In one specific embodiment, the ZrO2 content in the composite carrier ZrO2 / MCM-22 is 10-15% by mass.

[0009] In one specific embodiment, the Pt content in the Pt / @-ZrO2 / MCM-22 catalyst is 0.1 wt%, and the ZrO2 content in the composite support ZrO2 / MCM-22 is 10% by mass.

[0010] In one specific embodiment, the Pt / @-ZrO2 / MCM-22 catalyst is prepared by the following method, including:

[0011] ZrO2 was spontaneously spread in a monolayer form within the pores of MCM-22 molecular sieve by precipitation, forming a 2D amorphous semiconductor film, thus obtaining the composite carrier ZrO2 / MCM-22.

[0012] The Pt / @-ZrO2 / MCM-22 catalyst was obtained by anchoring Pt nanoparticles onto the 2D amorphous semiconductor film of the composite support ZrO2 / MCM-22 using a photocatalytic reduction method. The Pt nanoparticles, as the active component, have a synergistic effect with the ZrO2 semiconductor film.

[0013] In one specific embodiment, the precipitation method is as follows: first, ZrOCl2·8H2O is dissolved in deionized water, then molecular sieve MCM-22 is added, and after stirring evenly, an alkaline solution is added to adjust the pH value to 8.5-10, and then stirred for 30-240 minutes. The resulting solution is then subjected to static aging, washing, solid-liquid separation, drying, and calcination to obtain the composite carrier ZrO2 / MCM-22.

[0014] In one specific embodiment, the precipitation method involves a drying temperature of 70–90°C and a calcination temperature of 450°C–600°C.

[0015] In one specific embodiment, the photocatalytic reduction method is as follows: the composite support ZrO2 / MCM-22 is dissolved in deionized water, an appropriate amount of anhydrous methanol is added, and the mixture is ultrasonically dispersed evenly. Then, H2PtCl4 solution is added, and ultrasonic vibration is continued for a preset time. The mixture is then placed under an ultraviolet lamp and stirred under light irradiation. The resulting solution is filtered, washed, and vacuum dried to obtain the Pt / @-ZrO2 / MCM-22 catalyst.

[0016] In one specific embodiment, in the photocatalytic reduction method, the preset time for ultrasonic oscillation is 10-20 min, the stirring time under light irradiation is 12-16 h, and the vacuum drying temperature is 75-85℃.

[0017] The beneficial effects of the present invention include at least the following:

[0018] The catalyst provided by this invention is a Pt hybrid nanostructure catalyst constructed by assembling metallic Pt nanoparticles and 2D amorphous semiconductor metal oxides on a large specific surface area support. It exhibits a synergistic catalytic effect between metallic Pt nanoparticles (3D) and 2D amorphous semiconductor metal oxides. The strong electronic effect at the interface between metallic Pt nanoparticles and 2D amorphous semiconductor metal oxides demonstrates ultra-high catalytic activity (high conversion rate and high selectivity) when catalyzing the hydrogenation of p-nitrobenzaldehyde under mild conditions, and also has the advantage of low loading.

[0019] 2. The loading of metal oxide was controlled according to the principle of spontaneous monolayer dispersion to form a 2D amorphous semiconductor metal oxide film layer on the surface of the support MCM-22 in a monolayer form (XRD confirmed that it is amorphous, not crystalline). This is equivalent to coating a metal oxide "glue" on a large specific surface area support (such as MCM-22). The results show that the stability is good and the catalyst is stable when reused.

[0020] Third, zirconium oxide is a unique inorganic non-metallic material. It is the only substance whose surface simultaneously possesses both acidic and basic centers, and it also exhibits excellent ion exchange performance and abundant surface-enriched oxygen sites. Furthermore, nano-zirconia is an important oxide due to its large specific surface area and high activity, holding an irreplaceable position in the field of catalysis. Moreover, because nanomaterials possess unique properties such as quantum size effect, small size effect, surface effect, and macroscopic quantum tunneling effect, nano-zirconia also possesses a variety of unique physical and chemical properties.

[0021] MCM-22 is a microporous molecular sieve with a large specific surface area and a regular pore structure, providing more contact interfaces and active sites, which enables the 2D amorphous semiconductor film ZrO2 to be monolayer dispersed on the surface of the MCM-22 carrier.

[0022] This invention utilizes a precipitation method to load zirconium oxide in a monolayer onto a ZrO2 molecular sieve support, forming a semiconductor film. Palladium nanoparticles are then anchored onto this semiconductor film. Due to the large specific surface area of ​​the MCM-22 molecular sieve support, the resulting ZrO2 semiconductor film has a large surface area. On one hand, the active component, palladium nanoparticles, exhibits high surface dispersion and small particle size on the ZrO2 / MCM-22 composite support, resulting in excellent activity. On the other hand, the palladium nanoparticles and the ZrO2 semiconductor film demonstrate a strong synergistic effect. An interfacial electronic effect is generated, thereby improving the catalytic performance of the catalyst. Thus, the Pt / @-ZrO2 / MCM-22 catalyst provided by this invention can achieve higher selectivity and conversion rate in the hydrogenation of p-nitrobenzaldehyde under mild reaction conditions. The 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst can achieve 100% selectivity and 100% conversion rate in the hydrogenation of p-nitrobenzaldehyde under the conditions of a reaction temperature of 50°C, a reaction time of 60 minutes, and a hydrogen pressure of 0.7 MPa.

[0023] Fourth, the catalyst in this invention is applied to the selective hydrogenation reaction of p-nitrobenzaldehyde. Compared with the prior art, it has the advantages of mild reaction conditions, low catalyst dosage, high catalytic activity, and good selectivity, and has good prospects for industrial application. Attached Figure Description

[0024] Figure 1 XRD wide-angle diffraction patterns of the catalysts prepared in Example 1 and Comparative Example 1, as well as crystalline ZrO2 and the support MCM-22;

[0025] Figure 2 The XRD wide-angle diffraction patterns of the composite supports in the catalysts prepared in Examples 1 and 6-8 are shown below.

[0026] Figure 3(a) is a TEM image of the catalyst prepared in Comparative Example 1;

[0027] Figures 3(b), 3(c), and 3(d) are HRTEM images of the catalyst prepared in Example 1.

[0028] Figure 3(e) shows the particle size distribution of the catalyst prepared in Example 1;

[0029] Figure 3(f) is the EDX diagram of the catalyst prepared in Example 1. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. However, the present invention may be implemented in many different ways as limited and covered by the claims.

[0031] Example 1

[0032] 1) Preparation of catalysts:

[0033] (1) Preparation of the composite support ZrO2 / MCM-22 in the catalyst:

[0034] Dissolve 0.2905g of ZrOCl2·8H2O in 10mL of deionized water. Stir at room temperature until ZrOCl2·8H2O is completely dissolved. Add 1g of MCM-22 molecular sieve and 50mL of deionized water and stir until homogeneous. Then adjust the pH to 10 with 0.1mol / L NH3·H2O. Continue stirring for 30min, let stand for 24h, filter, wash the resulting solution with deionized water, dry in a drying oven at 80℃ for 12h, and calcine in a muffle furnace at 500℃ for 3h to obtain a composite carrier ZrO2 / MCM-22 with a ZrO2 mass fraction of 10%, i.e., 10% ZrO2 / MCM-22.

[0035] (2) Catalyst preparation:

[0036] 0.629 g of the composite support ZrO2 / MCM-22 was dispersed in 100 mL of deionized water, 10 mL of anhydrous methanol was added, and the mixture was ultrasonically dispersed for 10 min. Then, an appropriate amount of H2PtCl4 (0.0074 g / mL) solution was added, and the mixture was ultrasonically vibrated for another 20 min. The solution was then placed under a UV lamp and stirred for 12 h under illumination. The resulting solution was filtered, washed until neutral, and vacuum dried at 80 °C for 12 h to obtain 0.1% Pt / @-10% ZrO2 / MCM-22, meaning that the mass content of Pt in the Pt / @-10% ZrO2 / MCM-22 catalyst was 0.1%; the mass content of ZrO2 in the composite support ZrO2 / MCM-22 was 10%.

[0037] 2) Preparation of p-aminobenzaldehyde by hydrogenation of p-nitrobenzaldehyde: p-nitrobenzaldehyde, 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst (molar ratio of Pt to p-nitrobenzaldehyde is 0.062%) and 20 mL of anhydrous ethanol were placed in a high-pressure reactor. The hydrogen pressure was set to 0.7 MPa and the reaction temperature to 50 °C. After H2 was introduced to displace the air in the reactor, the H2 valve was closed. When the temperature inside the reactor reached the reaction temperature of 50 °C, H2 was introduced and the stirring was turned on to start the reaction. The reaction time was 60 min. After the reaction was completed, the mixture was cooled, and an appropriate amount of the reaction solution was centrifuged and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0038] Example 2

[0039] Similar to Example 1, except that the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst is 0.05%, that is, 0.05%Pt / @-10%ZrO2 / MCM-2.

[0040] Example 3

[0041] Similar to Example 1, except that the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst is 0.07%, that is, 0.07%Pt / @-10%ZrO2 / MCM-2.

[0042] Example 4

[0043] Similar to Example 1, except that the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst is 0.15%, that is, 0.15%Pt / @-10%ZrO2 / MCM-2.

[0044] Example 5

[0045] Similar to Example 1, except that the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst is 0.20%, i.e., 0.20%Pt / @-10%ZrO2 / MCM-2.

[0046] Comparative Example 1

[0047] Similar to Example 1, except that Pt / @-ZrO2 / MCM-22 does not contain palladium nanoparticles, and the mass fraction of Pt is 0, i.e., 10% ZrO2 / MCM-22.

[0048] The catalytic reaction results of the catalysts used in Examples 1-5 and Comparative Example 1 for the hydrogenation of p-nitrobenzaldehyde are shown in Table 1.

[0049] Table 1. Results of hydrogenation of p-nitrobenzaldehyde using Pt / @-ZrO2 / MCM-22 catalysts with different Pt loadings.

[0050] catalyst p-Nitrobenzaldehyde conversion rate (%) Selectivity of p-aminobenzaldehyde (%) Example 1 <![CDATA[0.10%Pt / @-10%ZrO2 / MCM-22]]> 100 100 Example 2 <![CDATA[0.05%Pt / @-10%ZrO2 / MCM-22]]> 93.72 100 Example 3 <![CDATA[0.07%Pt / @-10%ZrO2 / MCM-22]]> 99.6 100 Example 4 <![CDATA[0.15%Pt / @-10%ZrO2 / MCM-22]]> 100 100 Example 5 <![CDATA[0.20%Pt / @-10%ZrO2 / MCM-22]]> 100 100 Comparative Example 1 <![CDATA[10%ZrO2 / MCM-22]]> 0 100

[0051] Table 1 examines the hydrogenation reaction of p-nitrobenzaldehyde catalyzed by Pt / @-ZrO2 / MCM-22 catalysts with different Pt loadings. When the theoretical Pt loading is 0.05 wt%, under the conditions of a reaction temperature of 50 °C, a hydrogen pressure of 0.7 MPa, and a molar ratio of Pt metal nanoparticles to p-nitrobenzaldehyde (n(Pt) / n(p-nitrobenzaldehyde)) = 0.031%, the conversion rate of p-nitrobenzaldehyde is only 93.72%, while the selectivity for p-aminobenzaldehyde is 100% when the chemoselective hydrogenation reaction time is 60 min. When the theoretical Pt metal nanoparticle loading increases to 0.10 wt%, under the same reaction conditions, both the conversion rate and the selectivity for p-aminobenzaldehyde reach 100%, with a TOF of 3641 h⁻¹. -1 Experimental results show that as the number of active sites on the catalyst increases, the amount of H2 that can be activated also increases within the same time frame, thereby promoting the increased conversion rate of the chemoselective hydrogenation reaction of p-nitrobenzaldehyde. As can be seen from the data in Table 1, further increasing the loading of Pt metal nanoparticles does not change the catalytic activity; therefore, under the same conditions, a theoretical loading of 0.1 wt% Pt is optimal.

[0052] Preferably, the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst is 0.1-0.15%, and more preferably, it is 0.1% by mass.

[0053] It should be noted that, unless otherwise specified, the mass content of Pt in the Pt / @-ZrO2 / MCM-22 catalyst in this invention refers to the theoretical loading. Measurements show that when the theoretical loading of Pt metal nanoparticles is 0.10 wt%, the corresponding actual loading is 0.0537 wt%.

[0054] It should be noted that in this invention, the amounts of catalyst and nitrobenzaldehyde added in different embodiments and comparative examples are the same.

[0055] Example 6

[0056] Similar to Example 1, except that the mass fraction of ZrO2 in Pt / @-ZrO2 / MCM-22 is 5%, i.e., 0.1%Pt / @-5%ZrO2 / MCM-22.

[0057] Example 7

[0058] Similar to Example 1, except that the mass fraction of ZrO2 in Pt / @-ZrO2 / MCM-22 is 15%, i.e., 0.1%Pt / @-15%ZrO2 / MCM-22.

[0059] Example 8

[0060] Similar to Example 1, except that the mass fraction of ZrO2 in Pt / @-ZrO2 / MCM-22 is 15%, i.e., 0.1%Pt / @-20%ZrO2 / MCM-22.

[0061] Comparative Example 2

[0062] Similar to Example 1, except that the mass fraction of ZrO2 in Pt / @-ZrO2 / MCM-22 is 0, i.e., 0.1% Pt / MCM-22.

[0063] Comparative Example 3

[0064] Similar to Example 1, except that the mass fraction of MCM-22 in Pt / @-ZrO2 / MCM-22 is 0, i.e., 0.1% Pt / ZrO2.

[0065] It should be noted that the mass fraction of ZrO2 in the above embodiments refers to the mass fraction of ZrO2 in the composite support ZrO2 / MCM-22. The catalytic reaction results of the catalysts used in Examples 1, 6-8 and Comparative Examples 2-3 for the hydrogenation of p-nitrobenzaldehyde are shown in Table 2.

[0066] Table 2. Results of hydrogenation of p-nitrobenzaldehyde using Pt / @-ZrO2 / MCM-22 catalysts with different ZrO2 loadings.

[0067]

[0068] Table 2 examines the effect of different ZrO2 loadings on the catalytic activity of Pt / @-ZrO2 / MCM-22. With increasing ZrO2 loading, the specific surface area and pore volume of the support gradually decrease. When the ZrO2 loading is 0%, the conversion rate of p-nitrobenzaldehyde is only 3.41%, and the selectivity for p-aminobenzaldehyde is 100%. With increasing ZrO2 loading, the conversion rate of p-nitrobenzaldehyde gradually increases. When the ZrO2 loading increases to 5%, the conversion rate of p-nitrobenzaldehyde is 62.53%, and the selectivity for p-aminobenzaldehyde is 100%. Further increasing the ZrO2 loading to 10% results in both the conversion rate and the selectivity for p-aminobenzaldehyde reaching 100%. Further increasing the ZrO2 loading decreases both the conversion rate and the selectivity for p-nitrobenzaldehyde, indicating that excessive ZrO2 clogs the pores of MCM-22, causing multilayer dispersion and affecting the reaction.

[0069] Preferably, the optimal loading of ZrO2 in the catalyst is 10 wt%. Theoretically, the semiconductor film formed by zirconium dioxide is exactly a single layer loaded in the microporous molecular sieve MCM-22, resulting in the best catalytic activity and lower cost.

[0070] Examples 9A to 9D

[0071] Examples 9A to 9D all used the 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst prepared in Example 1. The difference lies in the different hydrogenation reaction conditions. Specifically, the hydrogenation reaction conditions for Example 1 were: hydrogen pressure 0.7 MPa, reaction temperature 50°C, and reaction time 60 min; for Example 9A, the hydrogenation reaction conditions were: hydrogen pressure 0.7 MPa, reaction temperature 30°C, and reaction time 60 min; for Example 9B, the hydrogenation reaction conditions were: hydrogen pressure 0.7 MPa, reaction temperature 50°C, and reaction time 30 min; for Example 9C, the hydrogenation reaction conditions were: hydrogen pressure 0.7 MPa, reaction temperature 50°C, and reaction time 40 min; and for Example 9D, the hydrogenation reaction conditions were: hydrogen pressure 0.5 MPa, reaction temperature 50°C, and reaction time 60 min. The catalytic reaction results of the hydrogenation reaction of p-nitrobenzaldehyde in Examples 1, 9A-9D are shown in Table 3.

[0072] Table 3. Results of hydrogenation of p-nitrobenzaldehyde under different hydrogenation reaction conditions.

[0073]

[0074] Table 3 shows that when the hydrogen pressure is 0.7 MPa and the reaction temperature is 50℃, the conversion rate of p-nitrobenzaldehyde increases with increasing reaction time, while the selectivity of p-aminobenzaldehyde remains at 100% and is not affected by the reaction time. When the hydrogen pressure is less than 0.7 MPa and the reaction time is 60 min, the conversion rate of p-nitrobenzaldehyde decreases, and the selectivity of p-aminobenzaldehyde decreases significantly. When the hydrogen pressure is 0.7 MPa, the reaction time is 60 min, and the reaction temperature is less than 50℃, the conversion rate of nitrobenzaldehyde decreases, but the selectivity of p-aminobenzaldehyde remains essentially unchanged.

[0075] Therefore, by changing any one of the reaction conditions (temperature, time, or pressure) while keeping the other two conditions constant, and comparing different conditions, the most suitable conditions for the selective hydrogenation of p-nitrobenzaldehyde can be found. The hydrogenation reaction of p-nitrobenzaldehyde catalyzed by the 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst achieved 100% conversion of p-nitrobenzaldehyde and 100% selectivity for p-aminobenzaldehyde under the conditions of a reaction temperature of 50℃, a reaction time of 60 min, and a hydrogen pressure of 0.7 MPa.

[0076] Examples 10A-10C

[0077] Examples 10A to 10C all used the 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst prepared in Example 1, and the catalytic hydrogenation reaction conditions were the same. The difference was that the solvents for the hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde were not exactly the same. Specifically, the solvent for Example 1 was anhydrous ethanol; the solvent for Example 10A was anhydrous methanol; the solvent for Example 10B was isopropanol; and the solvent for Example 10C was water.

[0078] The catalytic reaction results of the hydrogenation of p-nitrobenzaldehyde in Examples 1, 10A to 10C are shown in Table 4.

[0079] Table 4 Results of the hydrogenation reaction of p-nitrobenzaldehyde in different solvents

[0080] solvent p-Nitrobenzaldehyde conversion rate (%) Selectivity of p-aminobenzaldehyde (%) Example 1 Anhydrous ethanol 100 100 Example 10A Anhydrous methanol 100 90.2 Example 10B Isopropanol 100 78.9 Example 10C water 15.18 22.4

[0081] Table 4 shows the effect of 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst on the chemoselective hydrogenation performance of p-nitrobenzaldehyde in different reaction media. The comparison results show that the catalytic effect is least ideal when water is used as a solvent, the selectivity of p-nitrobenzaldehyde decreases when anhydrous methanol and isopropanol are used as solvents, and the catalytic effect is best when anhydrous ethanol is used as a solvent.

[0082] Examples 11A to 11I

[0083] Examples 11A to 11I all used the 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst prepared in Example 1. The catalytic reaction conditions were the same as in Example 1, except that the number of times the catalyst was used to catalyze the selective hydrogenation reaction of p-nitrobenzaldehyde was increased. The catalytic reaction results of p-nitrobenzaldehyde hydrogenation reaction in Examples 1, 11A to 11I are shown in Table 5.

[0084] Table 5 Results of catalyst usage number on benzaldehyde hydrogenation

[0085]

[0086] Table 5 shows the experimental results of the reusability of the 0.1% Pt / @-10% ZrO2 / MCM-22 catalyst. The specific experimental method is as follows: Under the conditions of 50℃, 0.7 MPa hydrogen pressure, 60 min, and n(Pt):n(p-nitrobenzaldehyde) = 0.062%, the selective hydrogenation of p-nitrobenzaldehyde was catalyzed using the 0.1 wt% Pt / @-10% ZrO2 / MCM-22 catalyst. The reaction solution was centrifuged to separate the catalyst from the reaction solution. The recovered catalyst was then washed three times with anhydrous ethanol by centrifugation and dried overnight in a forced-air drying oven at 80℃. A second catalytic hydrogenation reaction was then carried out under the same experimental conditions. The above operation was repeated 10 times. The results showed that the conversion rate of p-nitrobenzaldehyde remained essentially constant at 100%; however, from the 7th time onwards, the selectivity of p-aminobenzaldehyde gradually decreased. It is preliminarily speculated that this is due to some loss of the active component Pt after washing and drying, indicating that the catalyst has relatively good stability.

[0087] As can be seen from the above embodiments, the catalysts provided by the present invention with different mass fractions are all active for the selective hydrogenation reaction of p-nitrobenzaldehyde. Moreover, under the premise of adjusting and changing the catalytic reaction temperature, hydrogen pressure, and reaction time, most catalysts can achieve relatively excellent catalytic activity. The scope of the present invention is not limited to the above embodiments. As long as the mass fraction of the active component of the catalyst and the reaction conditions are well controlled, good results can be achieved for the hydrogenation reaction of p-nitrobenzaldehyde.

[0088] Please see Figure 1 As shown in Figure 3, Figure 1 The XRD wide-angle diffraction patterns of the catalysts prepared in Example 1 and Comparative Example 1, as well as the support MCM-22 and crystalline ZrO2; wherein, the XRD wide-angle diffraction patterns from top to bottom correspond to 0.1% Pt / @-10% ZrO2. 2 / MCM-22, 10% ZrO2 / MCM-22, MCM-22 support and crystalline ZrO2.

[0089] Figure 2 The XRD wide-angle diffraction patterns are of the composite supports in the catalysts prepared in Examples 1 and 6-8.

[0090] Figure 3(a) is a TEM image of the catalyst prepared in Example 1; Figures 3(b), 3(c), and 3(d) are HR-TEM images of the catalyst prepared in Example 1; Figure 3(e) is a particle size distribution diagram of the catalyst prepared in Example 1; Figure 3(f) is an EDX image of the catalyst prepared in Example 1.

[0091] Depend on Figure 1As shown in Figure 3, the pore structure of the support MCM-22 in the catalyst provided in this embodiment of the invention has not changed. ZrO2 is loaded on the support MCM-22 in the form of a 2D amorphous semiconductor film, and Pt and ZrO2 film have a synergistic effect. A strong electronic effect is generated at the interface between Pt nanoparticles and 2D amorphous ZrO2, thereby improving the catalytic activity of the catalyst.

[0092] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for the selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and a 2D amorphous semiconductor hybrid nanostructure catalyst, characterized in that, The method includes: preparing p-aminobenzaldehyde by hydrogenation of p-nitrobenzaldehyde as a raw material under specific solvent, catalyst, and preset hydrogenation reaction conditions. The specific solvent is anhydrous ethanol, the catalyst is a Pt / @-ZrO2 / MCM-22 catalyst, and the preset hydrogenation reaction conditions include: hydrogen pressure of 0.7 MPa to 0.9 MPa, reaction temperature of 50°C to 70°C, and reaction time of 60 min to 80 min. The Pt content in the Pt / @-ZrO2 / MCM-22 catalyst is 0.07 to 0.2 wt%, the ZrO2 content in the composite support ZrO2 / MCM-22 is 10 to 15%, and the ZrO2 in the Pt / @-ZrO2 / MCM-22 catalyst is a 2D amorphous semiconductor film layer spontaneously spread in the pores of the MCM-22 molecular sieve, while the active component Pt is anchored on the ZrO2 film layer. The Pt / @-ZrO2 / MCM-22 catalyst is prepared by the following method: ZrO2 is spontaneously spread in a monolayer form within the pores of MCM-22 molecular sieve using a precipitation method to form a 2D amorphous semiconductor film, thus obtaining a composite support ZrO2 / MCM-22; Pt nanoparticles are anchored onto the 2D amorphous semiconductor film of the composite support ZrO2 / MCM-22 using a photocatalytic reduction method to obtain the Pt / @-ZrO2 / MCM-22 catalyst. The Pt nanoparticles, as the active component, have a synergistic effect with the ZrO2 semiconductor film.

2. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 1, characterized in that, The molar ratio of Pt to p-nitrobenzaldehyde in the Pt / @-ZrO2 / MCM-22 catalyst is 0.0004~0.0014.

3. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 1, characterized in that, The preset hydrogenation reaction conditions include: a hydrogen pressure of 0.7 MPa, a reaction temperature of 50°C, and a reaction time of 60 min.

4. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 1, characterized in that, The Pt content in the Pt / @-ZrO2 / MCM-22 catalyst is 0.1 wt%, and the ZrO2 content in the composite support ZrO2 / MCM-22 is 10%.

5. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 1, characterized in that, The precipitation method is as follows: First, ZrOCl2·8H2O is dissolved in deionized water, then molecular sieve MCM-22 is added, and after stirring evenly, an alkaline solution is added to adjust the pH value to 8.5~10, and then stirred for 30~240 min. The resulting solution is then subjected to static aging, washing, solid-liquid separation, drying, and calcination to obtain the composite carrier ZrO2 / MCM-22.

6. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 5, characterized in that, In the precipitation method, the drying temperature is 70~90℃ and the calcination temperature is 450℃~600℃.

7. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and a 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 1, characterized in that, The photocatalytic reduction method is as follows: the composite support ZrO2 / MCM-22 is dissolved in deionized water, an appropriate amount of anhydrous methanol is added, and the mixture is ultrasonically dispersed evenly. Then, H2PtCl4 solution is added, and ultrasonic vibration is continued for a preset time. The mixture is then placed under a UV lamp and stirred under light irradiation. The resulting solution is filtered, washed, and vacuum dried to obtain the Pt / @-ZrO2 / MCM-22 catalyst.

8. The method for selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde catalyzed by a metal Pt and 2D amorphous semiconductor hybrid nanostructure catalyst according to claim 7, characterized in that, In the photocatalytic reduction method, the preset time for ultrasonic oscillation is 10-20 min, the stirring time under light irradiation is 12-16 h, and the vacuum drying temperature is 75-85℃.

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