Preparation method and application of organic phosphine shell modified nanocatalyst

Abstract

The present application relates to the technical field of catalytic hydrogenation reaction, and discloses a preparation method and application of an organic phosphine shell modified nanocatalyst, which comprises the following steps: adding a carbon carrier in an alcohol solvent and ultrasonic dispersion, then adding a chloroplatinic acid containing alcohol solution, and stirring at 0-15 DEG C; subsequently, an organic phosphine containing alcohol solution and a reducing agent are added, and the stirring is continued; finally, rotary evaporation is carried out, and drying is performed to obtain the nanocatalyst; the nanocatalyst is a platinum catalyst with a core-shell structure loaded on the surface of the carbon carrier. By introducing the organic phosphine ligand to the surface of the nanometer platinum particles, the core-shell structure nanoparticles with a flexible organic phosphine ligand modified shell are constructed, the adsorption and desorption strength and configuration of the active site electronic structure, the reaction microenvironment, the reactants and the intermediate state of the reaction interface are regulated, and the selective and efficient hydrogenation of the aromatic hydrocarbon containing nitro or carbon-carbon double bond is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic hydrogenation reaction, and in particular to a preparation method and application of an organic phosphine shell modified nanocatalyst. BACKGROUND

[0002] The products generated by the selective hydrogenation of nitroarenes or styrenes are highly relevant to key intermediates for the synthesis of pharmaceuticals, polymers, herbicides and dyes. However, for substrates with multiple easily reduced groups such as p-nitrobenzaldehyde, it is still difficult to achieve the coexistence of high activity and high selectivity. In recent years, most of the production of such nitroarenes uses Raney nickel as a catalyst to achieve the conversion from nitro to amino by catalytic hydrogenation, but Raney nickel catalyst has the problems of large consumption, active material properties (dangerous), and multiple by-products. Pt-based catalysts are considered ideal hydrogenation active catalysts due to their strong H2 activation ability, but they have the problems of poor selectivity and indiscriminate activation of functional groups.

[0003] Currently, non-organic shell modification catalysts are commonly used to improve their catalytic activity and selectivity, but traditional metal-based shells will cover part of the active sites, and the adjustment range of the reaction microenvironment is generally located in the vicinity of the active center. Organic modification of nanoparticles such as PEI can change the optical and electronic properties, catalytic activity, and geometric structure of the active particles, and effectively regulate the larger reaction microenvironment. By selecting and controlling the content of the ligand, modification of the ligand shell on the surface of the nanoparticles can effectively control the selectivity and activity of the liquid phase catalytic reaction, and also solves the problem of recycling of homogeneous ligand-metal materials. This not only can change the adsorption configuration and strength of the reactants, etc. according to the steric hindrance effect, and reduce the possibility of non-selective pathways, but also can regulate the electronic structure or the state process of active intermediates based on electronic effects and chelation effects to achieve customized modification for the reaction. Currently, carbonitride, mercaptan, halogen, and other organic modifications of active sites have been reported for carbonyl hydrogenation, ester hydrogenation, polymer degradation, and electrocatalysis reactions.

[0004] For example, the patent with publication number CN120532499A discloses a preparation method and application of a hydrophobic core-shell structure catalyst, specifically discloses a hydrophobic core-shell structure catalyst with silica coated with metal oxide and surface grafted with organosilane. The patent with publication number CN114892215A discloses an organic ligand modified Cu(OH)2 / Cu core-shell structure catalyst, a preparation method and application thereof, specifically discloses that inorganic copper salt is mixed with organic matter containing carboxyl to obtain organic ligand modified Cu(OH)2, wherein the organic matter containing carboxyl is one or a mixture of several of 1,4-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2-naphthalene carboxylic acid and oxalic acid; the surface of the organic ligand modified Cu(OH)2 is electrochemically reduced to electron-deficient Cu to obtain the organic ligand modified Cu(OH)2 / Cu core-shell structure catalyst. The patent with publication number CN120132839A discloses a supported ruthenium-based ammonia synthesis catalyst prepared by modifying activated carbon with organic matter, specifically discloses that the activated carbon modified with organic matter is used as a carrier, the organic matter is polyparapyrrolidone or L-ascorbic acid, and the carrier is immersed in a ruthenium salt solution and a barium salt solution in sequence to obtain the supported ruthenium-based ammonia synthesis catalyst.

[0005] However, in general, the modification of the existing catalysts with organic matter is only performed at the microscopic interface, and the content of the organic matter layer is not accurately controlled, which may cause the catalytic performance to be not optimal; the state of the ligand and the active site at the nanoscale is unclear, and a metal-organic matter reaction nanoenvironment with strong interaction is not constructed; the modification strategy of the organic matter is not expanded to phosphine with stronger electron-donating ligand, and the selection of the appropriate ligand is not based on the reaction; the flexible ligand strategy is not developed; the target surface to be modified is not expanded to ultra-small nanoparticles, that is, the coupling of the high-activity multi-defect nanosurface and the modification strategy of the organic matter is not performed; the metal-based shell layer covers a large area of the reaction active site, causing the selectivity of the hydrogenation activity to decrease. SUMMARY

[0006] In order to solve the technical problems of poor selectivity and low activity of the existing catalysts in the hydrogenation of aromatic hydrocarbons containing nitro groups or carbon-carbon double bonds, the present application provides a preparation method and application of an organic phosphine shell modified nanocatalyst, which introduces an organic phosphine ligand to the surface of a nanoparticle to construct an ultra-small nanoparticle with a layer of ligand modified shell, controls the adsorption and desorption strength and configuration of the active site electronic structure, reaction microenvironment, reactants and intermediate states of the reaction interface, and realizes the selective and efficient hydrogenation of aromatic hydrocarbons containing nitro groups or carbon-carbon double bonds.

[0007] The object of the present application is achieved by the following technical solutions:

[0008] In a first aspect, the present application provides a method for preparing an organic phosphine shell modified nanocatalyst, comprising the following steps: adding a carbon carrier in an alcohol solvent and ultrasonic dispersion, then adding a chloroplatinic acid containing alcohol solution, and stirring at 0-15°C; subsequently adding an organic phosphine containing alcohol solution and a reducing agent, and continuing to stir; finally, rotary evaporation and drying to obtain a nanocatalyst; the nanocatalyst is a platinum catalyst with a core-shell structure supported on the surface of a carbon carrier, wherein the platinum catalyst has a nanometer platinum particle as a core layer and an organic phosphine as a shell layer; the mass loading of Pt in the nanocatalyst is 1-10 wt%, and the molar ratio of organic phosphine to Pt is 1:0.1-5.

[0009] Since the activation and adsorption tendency of nitro group on the platinum active site is not overwhelmingly superior to other functional groups, the hydrogen isomerization ability of the platinum active site in the reaction interface needs to be improved, and the current technology has not realized the direct metal-ligand strong interaction to regulate the nano environment in the electronic and geometric structure, and has not broken through the design of the adjustable organic modification layer on the surface of the ultra-small nanoparticles for the reaction. Therefore, the present application synthesizes an ultra-small Pt NPs nanocatalyst modified by an organic phosphine ligand shell supported on the surface of a carbon carrier, and constructs a metal-organic reaction nano environment with strong interaction by the steric hindrance effect (by the structure of a flexible long chain, the reactant molecules are more likely to contact the active site in a vertical adsorption manner) and the electronic effect (electrons are transferred from a strong electron-donating phosphine to the Pt active site, promoting the performance of the nitro electrophilic reaction) of the flexible organic phosphine ligand, and realizes the regulation of the electronic structure of the catalyst by the design of the modified structure of the ultra-small nanoparticles, thereby realizing the selective and efficient hydrogenation of nitro-containing aromatic hydrocarbons.

[0010] Similarly, due to the introduction of the organic phosphine shell, the electronic density of the catalyst Pt active site surface is increased, the hydrogen dissociation activation and hydrogen overflow ability are enhanced, and the concentration of active hydrogen species is increased, which also makes the selective hydrogenation reaction of aromatic hydrocarbons containing carbon-carbon double bonds more easily performed, and the electron-rich Pt domain also accelerates the activation of carbon-carbon double bond in the carbon-carbon double bond hydrogenation reaction, thereby improving the catalytic activity and selectivity of the reaction.

[0011] As a preferred, the carbon carrier comprises one or more of carbon black, carbon nanotube, nitrogen-doped carbon and graphene.

[0012] As preferred, the organic phosphine includes one or more of triethylphosphine, tributylphosphine, tri-n-octylphosphine, di-tert-butylmethylphosphine, diphenylethylphosphine, diphenylmethoxyphosphine, di-1-adamantylphosphine, n-butyldi(1-adamantyl)phosphine, dicyclohexylchlorophosphine, tri(2-furyl)phosphine, diphenyl-2-pyridylphosphine, triphenylphosphine, tri(o-methylphenyl)phosphine, tri(4-fluorophenyl)phosphine, tri(3-methoxyphenyl)phosphine, tri(3,5-dimethylphenyl)phosphine, 2-diphenylphosphinobenzoic acid, 1,3-bis(diphenylphosphino)propane and 1,5-bis(diphenylphosphino)pentane. Further preferred, the organic phosphine includes one or more of triethylphosphine, tributylphosphine, tri-n-octylphosphine, di-tert-butylmethylphosphine, tri(3-methoxyphenyl)phosphine, tri(3,5-dimethylphenyl)phosphine and 2-diphenylphosphinobenzoic acid. Still further preferred, the organic phosphine is tri-n-octylphosphine.

[0013] By exploring the influence of organic phosphine pairs containing different alkanes on catalysis, it is found that the flexible tri-n-octylphosphine ligand has the best performance. With tri-n-octylphosphine as the optimal ligand, the influence of ligand modification amount on catalysis is investigated. Within the range of ligand modification defined in the present application, the modulation of the geometric / electronic structure of the active site by ligand modification promotes the selective nitro hydrogenation performance. The catalyst can also be applied to a wide range of nitro aromatic hydrogenation and styrene C=C double bond hydrogenation, providing research support for the design and construction of related metal-organic core-shell structures.

[0014] As preferred, the alcohol solvent is one or more of ethanol, isopropanol and n-propanol; the alcohol solvent used in the alcohol solution containing chloroplatinic acid and the alcohol solution containing organic phosphine is one or more of ethanol, isopropanol and n-propanol.

[0015] As preferred, the reducing agent is NaBH4 powder or an alcohol solution containing NaBH4; the amount of the reducing agent added is calculated according to the molar ratio of NaBH4 to Pt in chloroplatinic acid of 3-15:1.

[0016] As preferred, in the organic phosphine ligand modified nanocatalyst, the particle size of the nanometer platinum particles is 1-3 nm.

[0017] In a second aspect, the present application provides an application of an organic phosphine shell modified nanocatalyst in a nitro-containing aromatic hydrocarbon substrate hydrogenation reaction.

[0018] As preferred, the nitro-containing aromatic hydrocarbon substrate includes one or more of p-chloronitrobenzene, 3,5-dichloronitrobenzene, m-bromonitrobenzene, 4-nitrotoluene and p-nitroacetophenone.

[0019] In a third aspect, the present application provides an application of the organic phosphine shell modified nanocatalyst in a hydrogenation reaction of an aromatic hydrocarbon substrate containing carbon-carbon double bond.

[0020] Preferably, the aromatic hydrocarbon substrate containing carbon-carbon double bond comprises one or more of 4-methoxystyrene, 4-methylstyrene, p-chlorostyrene and p-bromostyrene.

[0021] Compared with the prior art, the nanocatalyst in the present application has the following beneficial effects:

[0022] (1) The organic phosphine ligand regulates the electron density and electron spin state of the Pt active site, the electron is transferred from the ligand to the Pt active site, the electron cloud density of the Pt site is improved, thereby promoting the hydrogenation of nitro and C=C double bond;

[0023] (2) After introducing a suitable flexible organic phosphine ligand, the hydrogen overflow is strengthened, the reaction energy barrier is reduced, and the hydrogenation reaction performance is further improved;

[0024] (3) In the nanometer environment on the surface of Pt, there are ligand molecules, which optimize the adsorption configuration and diffusion of the p-nitro aromatic hydrocarbon substrate, so that it tends to contact the Pt site at the -NO2 end, thereby improving the product selectivity;

[0025] (4) The hydrogenation reaction condition temperature is low, the hydrogen pressure is normal pressure, and the hydrogenation reaction has the advantages of low energy consumption and easy conversion.

[0026] In summary, the in-situ synthesis process of the nanocatalyst in the present application can cause abundant defect sites and retain the organic phosphine ligand on the surface. The flexible organic phosphine modification layer optimizes the nanometer environment of the active interface through space effect, electronic effect and coordination chelation effect, promotes the adsorption and activation of the reaction substrate, and greatly improves the catalytic activity and selectivity of the hydrogenation reaction. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of the synthesis route of the nanocatalyst in the present application.

[0028] Figure 2 The figure is a transmission electron microscope image of Pt1@ (P3)1 / C catalyst.

[0029] Figure 3 The figure is a high-resolution transmission electron microscope image of Pt1@ (P3)1 / C catalyst.

[0030] Figure 4 The figure is the HAADF-TEM-EDS element distribution of Pt1@ (P3)1 / C catalyst; (a) high-angle annular dark field image; (b) element distribution of platinum; (c) element distribution of phosphorus. DETAILED DESCRIPTION

[0031] The technical solutions of the present application are described below with specific examples, but the scope of protection of the present application is not limited thereto.

[0032] In the specific examples of the present application, the organic phosphine used is (triethylphosphine (P1), tributylphosphine (P2), tri-n-octylphosphine (P3), di-tert-butylmethylphosphine (P4), diphenylethylphosphine (P5), diphenylmethoxyphosphine (P6), di-1-adamantylphosphine (P7), n-butyldi(1-adamantyl)phosphine (P8), dicyclohexylchlorophosphine (P9), tri(2-furyl)phosphine (P10), diphenyl-2-pyridylphosphine (P11), triphenylphosphine (P12), tri(o-methylphenyl)phosphine (P13), tri(4-fluorophenyl)phosphine (P14), tri(3-methoxyphenyl)phosphine (P15), tri(3,5-dimethylphenyl)phosphine (P16), 2-diphenylphosphinobenzoic acid (P17), 1,3-bis(diphenylphosphino)propane (P18), or 1,5-bis(diphenylphosphino)pentane (P19). 10 11 12 13 14 15 16 17 18 19

[0033] In the specific examples of the present application, the finally prepared nanocatalyst comprises a carbon carrier, nanometer platinum particles and an organic phosphine, and the addition amount of the carbon carrier is calculated according to the Pt loading content in the catalyst and the addition amount of the organic phosphine.

[0034] Example 1 (Pt1@ (P3)1 / C, loading content of 1 wt%)

[0035] (1) 1.894 g of carbon black was added to 100 mL of isopropyl alcohol under ultrasonication to form a mixture A;

[0036] (2) 25 mL of isopropyl alcohol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading content in the catalyst was controlled to be 1 wt%) was slowly added to the mixture A, and the system temperature was controlled at 5°C to form a mixture B;

[0037] (3) 25 mL of isopropyl alcohol solution containing 0.1 mmol of tri-n-octylphosphine (the molar ratio of tri-n-octylphosphine to Pt was controlled to be 1:1) was slowly added to the mixture B, and the system temperature was controlled at 5°C to form a mixture C;

[0038] ​​​​​​​​​​(4) NaBH4 powder was quickly added to the mixture C, the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled to be 5°C, and the mixture was stirred for 6h to form mixture D;

[0039] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain the Pt1@ (P3)1 / C catalyst, i.e., 1 wt% Pt1@ (Tri-octyl-P)1 / C catalyst.

[0040] Example 2 (Pt1@ (P3) 0.25 / C)

[0041] (1) 1.921 g of carbon black was added to 100 mL of isopropyl alcohol under ultrasonic, to form a mixture A;

[0042] (2) 25 mL of isopropyl alcohol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (the Pt loading in the catalyst was controlled to be 1 wt%) was slowly added to the mixture A, and the system temperature was controlled to be 5°C to form a mixture B;

[0043] (3) 25 mL of isopropyl alcohol solution containing 0.025 mmol of tri-n-octyl phosphine (the molar ratio of tri-n-octyl phosphine to Pt was controlled to be 1:0.25) was slowly added to the mixture B, and the system temperature was controlled to be 5°C to form a mixture C;

[0044] (4) NaBH4 powder was quickly added to the mixture C, the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled to be 5°C, and the mixture was stirred for 6h to form mixture D;

[0045] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain the Pt1@ (P3) 0.25 / C catalyst, i.e., Pt1@ (Tri-octyl-P) 0.25 / C catalyst.

[0046] Example 3 (Pt1@ (P3) 0.5 / C)

[0047] (1) 1.913 g of carbon black was added to 100 mL of isopropyl alcohol under ultrasonic, to form a mixture A;

[0048] (2) 25 mL of isopropyl alcohol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (the Pt loading in the catalyst was controlled to be 1 wt%) was slowly added to the mixture A, and the system temperature was controlled to be 5°C to form a mixture B;

[0049] (3) slowly add 25 mL of tri-n-octylphosphine solution dissolved in isopropanol (control the molar ratio of tri-n-octylphosphine to Pt to be 1:0.5) to the mixture B, control the temperature of the system to be 5°C, to form a mixture C;

[0050] (4) quickly add NaBH4 powder to the mixture C, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the temperature of the system to be 5°C, fully stir for 6 h, to form a mixture D;

[0051] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain Pt1@ (P3)2 / C, i.e., Pt1@ (Tri-octyl-P)2 / C catalyst. 0.5 0.5 / C catalyst.

[0052] Example 4 (Pt1@ (P3)2 / C)

[0053] (1) add 1.857 g of carbon black to 100 mL of isopropanol under ultrasonic, to form a mixture A;

[0054] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (control the Pt loading in the catalyst to be 1 wt%) to the mixture A, control the temperature of the system to be 5°C, to form a mixture B;

[0055] (3) slowly add 25 mL of tri-n-octylphosphine solution dissolved in isopropanol (control the molar ratio of tri-n-octylphosphine to Pt to be 1:2) to the mixture B, control the temperature of the system to be 5°C, to form a mixture C;

[0056] (4) quickly add NaBH4 powder to the mixture C, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the temperature of the system to be 5°C, fully stir for 6 h, to form a mixture D;

[0057] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain Pt1@ (P3)2 / C, i.e., Pt1@ (Tri-octyl-P)2 / C catalyst.

[0058] Example 5 (Pt1@ (P3)3 / C)

[0059] (1) add 1.820 g of carbon black to 100 mL of isopropanol under ultrasonic, to form a mixture A;

[0060] ​(2) Slowly add 25 mL of isopropyl alcohol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0061] (3) Slowly add 25 mL of isopropyl alcohol solution containing 0.3 mmol of tri-n-octylphosphine (the molar ratio of tri-n-octylphosphine to Pt is controlled to be 1:3) into the mixture B, and control the temperature of the system at 5°C to form a mixture C;

[0062] (4) Rapidly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0063] (5) After rotary evaporation of the mixture D, grind and then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P3)1 / C, i.e., Pt1@ (Tri-octyl-P)1 / C catalyst.

[0064] Example 6 (Pt1@ (P1)1 / C)

[0065] (1) Add 1.919 g of carbon black into 100 mL of isopropyl alcohol under ultrasonic to form a mixture A;

[0066] (2) Slowly add 25 mL of isopropyl alcohol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0067] (3) Slowly add 25 mL of isopropyl alcohol solution containing 0.1 mmol of triethylphosphine (the molar ratio of triethylphosphine to Pt is controlled to be 1:1) into the mixture B, and control the temperature of the system at 5°C to form a mixture C;

[0068] (4) Rapidly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0069] (5) After rotary evaporation of the mixture D, grind and then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P1)1 / C catalyst.

[0070] Example 7 (Pt1@ (P2)1 / C)

[0071] (1) Add 1.911 g of carbon black into 100 mL of isopropyl alcohol under ultrasonic to form a mixture A;

[0072] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of hexahydrate chloroplatinic acid (Pt loading in the catalyst is controlled to be 1 wt%) to the mixture A, and control the system temperature at 5°C to form a mixture B;

[0073] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of tributylphosphine to the mixture B (the molar ratio of tributylphosphine to Pt is controlled to be 1:1), and control the system temperature at 5°C to form a mixture C;

[0074] (4) quickly add NaBH4 powder to the mixture C, and control the molar ratio of NaBH4 to Pt in the chloroplatinic acid to be 10:1, and control the system temperature at 5°C, and fully stir for 6 h to form a mixture D;

[0075] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P2)1 / C catalyst.

[0076] Example 8 (Pt1@ (P4)1 / C)

[0077] (1) add 1.915 g of carbon black to 100 mL of isopropanol under ultrasonication to form a mixture A;

[0078] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of hexahydrate chloroplatinic acid (Pt loading in the catalyst is controlled to be 1 wt%) to the mixture A, and control the system temperature at 5°C to form a mixture B;

[0079] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of di-tert-butylmethylphosphine to the mixture B (the molar ratio of di-tert-butylmethylphosphine to Pt is controlled to be 1:1), and control the system temperature at 5°C to form a mixture C;

[0080] (4) quickly add NaBH4 powder to the mixture C, and control the molar ratio of NaBH4 to Pt in the chloroplatinic acid to be 10:1, and control the system temperature at 5°C, and fully stir for 6 h to form a mixture D;

[0081] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P4)1 / C catalyst.

[0082] Example 9 (Pt1@ (P5)1 / C)

[0083] (1) add 1.910 g of carbon black to 100 mL of isopropanol under ultrasonication to form a mixture A;

[0084] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of hexahydrate chloroplatinic acid (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0085] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of diphenyl ethyl phosphine into the mixture B (the molar ratio of diphenyl ethyl phosphine to Pt is controlled to be 1:1), and control the temperature of the system at 5°C to form a mixture C;

[0086] (4) quickly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0087] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P5)1 / C catalyst.

[0088] Example 10 (Pt1@ (P6)1 / C)

[0089] (1) add 1.909 g of carbon black into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0090] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of hexahydrate chloroplatinic acid (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0091] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of diphenyl ethyl phosphine into the mixture B (the molar ratio of diphenyl ethyl phosphine to Pt is controlled to be 1:1), and control the temperature of the system at 5°C to form a mixture C;

[0092] (4) quickly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0093] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P6)1 / C catalyst.

[0094] Example 11 (Pt1@ (P7)1 / C)

[0095] (1) add 1.895 g of carbon black into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0096] (2) slowly add 25 mL of 0.1 mmol hexahydrate chloroplatinic acid isopropanol solution (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and the temperature of the system is controlled to be 5°C to form a mixture B;

[0097] (3) slowly add 25 mL of 0.1 mmol di-1-adamantyl phosphine isopropanol solution (the molar ratio of di-1-adamantyl phosphine to Pt is controlled to be 1:1) into the mixture B, and the temperature of the system is controlled to be 5°C to form a mixture C;

[0098] (4) rapidly add NaBH4 powder into the mixture C, and the molar ratio of NaBH4 to Pt in the chloroplatinic acid is controlled to be 10:1, the temperature of the system is controlled to be 5°C, and the mixture is fully stirred for 6 h to form a mixture D;

[0099] (5) the mixture D is rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried under vacuum at 15°C to obtain the Pt1@ (P7)1 / C catalyst.

[0100] Example 12 (Pt1@ (P8)1 / C)

[0101] (1) 1.895 g of carbon black is added into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0102] (2) 25 mL of 0.1 mmol hexahydrate chloroplatinic acid isopropanol solution (Pt loading in the catalyst is controlled to be 1 wt%) is slowly added into the mixture A, and the temperature of the system is controlled to be 5°C to form a mixture B;

[0103] (3) 25 mL of 0.1 mmol n-butyl di(1-adamantyl) phosphine isopropanol solution (the molar ratio of n-butyl di(1-adamantyl) phosphine to Pt is controlled to be 1:1) is slowly added into the mixture B, and the temperature of the system is controlled to be 5°C to form a mixture C;

[0104] (4) NaBH4 powder is rapidly added into the mixture C, and the molar ratio of NaBH4 to Pt in the chloroplatinic acid is controlled to be 10:1, the temperature of the system is controlled to be 5°C, and the mixture is fully stirred for 6 h to form a mixture D;

[0105] (5) the mixture D is rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried under vacuum at 15°C to obtain the Pt1@ (P8)1 / C catalyst.

[0106] Example 13 (Pt1@ (P9)1 / C)

[0107] (1) 1.908 g of carbon black is added into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0108] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0109] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of dicyclohexylphosphine chloride (the molar ratio of dicyclohexylphosphine chloride to Pt is controlled to be 1:1) into the mixture B, and control the temperature of the system at 5°C to form a mixture C;

[0110] (4) quickly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0111] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P9)1 / C catalyst.

[0112] Example 14 (Pt1@ (P 10 )1 / C)

[0113] (1) add 1.908 g of carbon black into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0114] (2) slowly add 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst is controlled to be 1 wt%) into the mixture A, and control the temperature of the system at 5°C to form a mixture B;

[0115] (3) slowly add 25 mL of isopropanol solution containing 0.1 mmol of tris(2-furyl)phosphine (the molar ratio of tris(2-furyl)phosphine to Pt is controlled to be 1:1) into the mixture B, and control the temperature of the system at 5°C to form a mixture C;

[0116] (4) quickly add NaBH4 powder into the mixture C, and control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, and control the temperature of the system at 5°C, and fully stir for 6 h to form a mixture D;

[0117] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P 10 )1 / C catalyst.

[0118] Example 15 (Pt1@ (P 11 )1 / C)

[0119] (1) 1.905 g carbon black was added into 100 mL isopropanol under ultrasonic to form mixture A;

[0120] (2) 25 mL isopropanol solution containing 0.1 mmol hexahydrate chloroplatinic acid (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added into mixture A, and the system temperature was controlled at 5°C to form mixture B;

[0121] (3) 25 mL isopropanol solution containing 0.1 mmol diphenyl-2-pyridyl phosphine (the molar ratio of diphenyl-2-pyridyl phosphine to Pt was controlled to be 1:1) was slowly added into mixture B, and the system temperature was controlled at 5°C to form mixture C;

[0122] (4) NaBH4 powder was rapidly added into mixture C, and the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the mixture was fully stirred for 6 h to form mixture D;

[0123] (5) After mixture D was rotary evaporated and ground, it was washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain Pt1@ (P 11 )1 / C catalyst.

[0124] Example 16 (Pt1@ (P 12 )1 / C)

[0125] (1) 1.905 g carbon black was added into 100 mL isopropanol under ultrasonic to form mixture A;

[0126] (2) 25 mL isopropanol solution containing 0.1 mmol hexahydrate chloroplatinic acid (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added into mixture A, and the system temperature was controlled at 5°C to form mixture B;

[0127] (3) 25 mL isopropanol solution containing 0.1 mmol triphenylphosphine (the molar ratio of triphenylphosphine to Pt was controlled to be 1:1) was slowly added into mixture B, and the system temperature was controlled at 5°C to form mixture C;

[0128] (4) NaBH4 powder was rapidly added into mixture C, and the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the mixture was fully stirred for 6 h to form mixture D;

[0129] (5) After mixture D was rotary evaporated and ground, it was washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain Pt1@ (P 12 )1 / C catalyst.

[0130] Example 17 (Pt1@ (P13 )1 / C)

[0131] (1) 1.901 g of carbon black was added into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0132] (2) 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added into the mixture A, and the system temperature was controlled at 5°C to form a mixture B;

[0133] (3) 25 mL of isopropanol solution containing 0.1 mmol of tris (o-methylphenyl) phosphine (the molar ratio of tris (o-methylphenyl) phosphine to Pt was controlled to be 1:1) was slowly added into the mixture B, and the system temperature was controlled at 5°C to form a mixture C;

[0134] (4) NaBH4 powder was rapidly added into the mixture C, and the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the mixture was fully stirred for 6 h to form a mixture D;

[0135] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain Pt1@ (P 13 )1 / C catalyst.

[0136] Example 18 (Pt1@ (P 14 )1 / C)

[0137] (1) 1.915 g of carbon black was added into 100 mL of isopropanol under ultrasonic to form a mixture A;

[0138] (2) 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added into the mixture A, and the system temperature was controlled at 5°C to form a mixture B;

[0139] (3) 25 mL of isopropanol solution containing 0.1 mmol of tris (4-fluorophenyl) phosphine (the molar ratio of tris (4-fluorophenyl) phosphine to Pt was controlled to be 1:1) was slowly added into the mixture B, and the system temperature was controlled at 5°C to form a mixture C;

[0140] (4) NaBH4 powder was rapidly added into the mixture C, and the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the mixture was fully stirred for 6 h to form a mixture D;

[0141] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain Pt1@ (P 14)1 / C catalyst.

[0142] Example 19 (Pt1@ (P 15 )1 / C)

[0143] (1) Add 1.896 g of carbon black to 100 mL of isopropanol while sonicating to form mixture A;

[0144] (2) Slowly add 25 mL of isopropanol solution containing 0.1 mmol chloroplatinic acid hexahydrate (Pt loading in catalyst is controlled at 1 wt%) to mixture A, and control the system temperature at 5 °C to form mixture B;

[0145] (3) Slowly add 25 mL of isopropanol solution containing 0.1 mmol of tris(3-methoxyphenyl)phosphine to mixture B (controlling the molar ratio of tris(3-methoxyphenyl)phosphine to Pt to be 1:1), and control the system temperature at 5 °C to form mixture C;

[0146] (4) Add NaBH4 powder to mixture C quickly, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the system temperature at 5℃, stir thoroughly for 6h to form mixture D;

[0147] (5) The mixture D was rotary evaporated and then ground, followed by washing several times with a mixture of ethanol and acetone, and finally dried under vacuum at 15°C to obtain Pt1@(P 15 )1 / C catalyst.

[0148] Example 20 (Pt1@ (P 16 )1 / C)

[0149] (1) Add 1.896 g of carbon black to 100 mL of isopropanol while sonicating to form mixture A;

[0150] (2) Slowly add 25 mL of isopropanol solution containing 0.1 mmol chloroplatinic acid hexahydrate (Pt loading in catalyst is controlled at 1 wt%) to mixture A, and control the system temperature at 5 °C to form mixture B;

[0151] (3) Slowly add 25 mL of isopropanol solution containing 0.1 mmol of tris(3,5-dimethyl)phosphine to mixture B (controlling the molar ratio of tris(3,5-dimethyl)phosphine to Pt to 1:1), and control the system temperature at 5 °C to form mixture C;

[0152] (4) Add NaBH4 powder to mixture C quickly, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the system temperature at 5℃, stir thoroughly for 6h to form mixture D;

[0153] (5) The mixture D was rotary evaporated and grinded, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain the Pt1@ (P 16 )1 / C catalyst.

[0154] Example 21 (Pt1@ (P 17 )1 / C)

[0155] (1) 1.900 g of carbon black was added to 100 mL of isopropanol under ultrasonic to form mixture A;

[0156] (2) 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added to the mixture A, and the system temperature was controlled at 5°C to form mixture B;

[0157] (3) 25 mL of isopropanol solution containing 0.1 mmol of 2-diphenylphosphinobenzoic acid (the molar ratio of 2-diphenylphosphinobenzoic acid to Pt was controlled to be 1:1) was slowly added to the mixture B, and the system temperature was controlled at 5°C to form mixture C;

[0158] (4) NaBH4 powder was quickly added to the mixture C, and the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the stirring was performed for 6 h to form mixture D;

[0159] (5) The mixture D was rotary evaporated and grinded, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain the Pt1@ (P 17 )1 / C catalyst.

[0160] Example 22 (Pt1@ (P 18 )1 / C)

[0161] (1) 1.900 g of carbon black was added to 100 mL of isopropanol under ultrasonic to form mixture A;

[0162] (2) 25 mL of isopropanol solution containing 0.1 mmol of chloroplatinic acid hexahydrate (Pt loading in the catalyst was controlled to be 1 wt%) was slowly added to the mixture A, and the system temperature was controlled at 5°C to form mixture B;

[0163] (3) 25 mL of isopropanol solution containing 0.1 mmol of 1,3-bis(diphenylphosphino)propane (the molar ratio of 1,3-bis(diphenylphosphino)propane to Pt was controlled to be 1:1) was slowly added to the mixture B, and the system temperature was controlled at 5°C to form mixture C;

[0164] (4) NaBH4 powder was quickly added into the mixture C, the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled to be 5°C, and the mixture was fully stirred for 6h to form a mixture D;

[0165] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain a Pt1@ (P3)1 / C catalyst. 18 )1 / C catalyst.

[0166] Example 23 (Pt1@ (P3)1 / C) 19 )1 / C catalyst.

[0167] (1) 1.887g carbon black was added into 100mL isopropanol under ultrasonic to form a mixture A;

[0168] (2) 25mL isopropanol solution containing 0.1mmol chloroplatinic acid hexahydrate (the Pt loading in the catalyst was controlled to be 1wt%) was slowly added into the mixture A, and the system temperature was controlled to be 5°C to form a mixture B;

[0169] (3) 25mL isopropanol solution containing 0.1mmol 1,5-bis(diphenylphosphino)pentane was slowly added into the mixture B (the molar ratio of 1,5-bis(diphenylphosphino)pentane to Pt was controlled to be 1:1), and the system temperature was controlled to be 5°C to form a mixture C;

[0170] (4) NaBH4 powder was quickly added into the mixture C, the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled to be 5°C, and the mixture was fully stirred for 6h to form a mixture D;

[0171] (5) The mixture D was rotary evaporated and ground, then washed several times with a mixed solution of ethanol and acetone, and finally dried at 15°C under vacuum to obtain a Pt1@ (P3)1 / C catalyst. 19 )1 / C catalyst.

[0172] Example 24 (Pt1@ (P3)1 / C, loading of 5 wt%)

[0173] (1) 1.887g carbon black was added into 100mL isopropanol under ultrasonic to form a mixture A;

[0174] (2) 25mL isopropanol solution containing 0.1mmol chloroplatinic acid hexahydrate (the Pt loading in the catalyst was controlled to be 1wt%) was slowly added into the mixture A, and the system temperature was controlled to be 5°C to form a mixture B;

[0175] (3) slowly add 25 mL of tri-n-octylphosphine in isopropanol solution (0.5 mmol, control the molar ratio of tri-n-octylphosphine to Pt to be 1:1) to the mixture B, control the temperature of the system to be 5°C, to form a mixture C;

[0176] (4) quickly add NaBH4 powder to the mixture C, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the temperature of the system to be 5°C, fully stir for 6 h, to form a mixture D;

[0177] (5) grind the mixture D after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt1@ (P3)1 / C, i.e. 5 wt% Pt1@ (Tri-octyl-P)1 / C catalyst.

[0178] Comparative Example 1 (Pt / C)

[0179] (1) add 1.931 g of carbon black to 100 mL of isopropanol under ultrasonication, to form a mixture A;

[0180] (2) slowly add 25 mL of chloroplatinic acid hexahydrate in isopropanol solution (0.1 mmol, control the Pt loading in the catalyst to be 1 wt%) to the mixture A, control the temperature of the system to be 5°C, to form a mixture B;

[0181] (4) quickly add NaBH4 powder to the mixture B, control the molar ratio of NaBH4 to Pt in chloroplatinic acid to be 10:1, control the temperature of the system to be 5°C, fully stir for 6 h, to form a mixture C;

[0182] (5) grind the mixture C after rotary evaporation, then wash several times with a mixed solution of ethanol and acetone, and finally dry under vacuum at 15°C to obtain the Pt / C catalyst.

[0183] Comparative Example 2 (Pt1@ (P3)1 / C (change the order of feeding))

[0184] (1) add 1.931 g of carbon black to 100 mL of isopropanol under ultrasonication, to form a mixture A;

[0185] (2) slowly add 25 mL of tri-n-octylphosphine in isopropanol solution (0.1 mmol, control the molar ratio of tri-n-octylphosphine to Pt to be 1:1) to the mixture A, control the temperature of the system to be 5°C, to form a mixture B;

[0186] (3) slowly add 25 mL of chloroplatinic acid hexahydrate in isopropanol solution (0.1 mmol, control the Pt loading in the catalyst to be 1 wt%) to the mixture B, control the temperature of the system to be 5°C, to form a mixture C;

[0187] (4) NaBH4 powder was quickly added to the mixture C, the molar ratio of NaBH4 to Pt in chloroplatinic acid was controlled to be 10:1, the system temperature was controlled at 5°C, and the stirring was performed for 6 h to form mixture D;

[0188] (5) The mixture D was rotary evaporated, ground, washed with a mixed solution of ethanol and acetone for several times, and finally dried at 15°C under vacuum to obtain the Pt1@ (P3)1 / C catalyst.

[0189] The nano-catalysts in Examples 1-24 and Comparative Examples 1-2 were used for the hydrogenation reaction of p-nitrobenzaldehyde, and the reaction conditions were as follows: solvent (ethanol), 10.0 mL; nano-catalyst, 20.0 mg; p-nitrobenzaldehyde, 1.0 mmol; H2 pressure, 0.1 MPa; reaction temperature, 45°C; and reaction time, 30 min for Examples 1-23 and 5 min for Example 24. The content of p-aminobenzaldehyde in the reaction product was determined, and the conversion rate and selectivity were calculated, and the specific data are shown in Tables 1-3.

[0190] Table 1 Catalytic performance of the nano-catalysts in Examples 1, 6-24 and Comparative Examples 1-2 in the hydrogenation reaction of p-nitrobenzaldehyde

[0191]

[0192] Table 2 Catalytic performance of the nano-catalysts in Examples 1-5 in the hydrogenation reaction of p-nitrobenzaldehyde

[0193]

[0194] Table 3 Catalytic performance of the nano-catalysts in Example 1 after the hydrogenation reaction of p-nitrobenzaldehyde was repeated five times

[0195]

[0196] The nano-catalysts in Example 1 and Comparative Example 1 were used for the hydrogenation reaction of styrene, and the reaction conditions were as follows: solvent (ethanol), 10.0 mL; catalyst, 10.0 mg; styrene, 5.0 mmol; H2 pressure, 0.1 MPa; reaction temperature, 25°C; and reaction time, 90 min. The content of ethylbenzene in the reaction product was determined, and the conversion rate and selectivity were calculated, and the specific data are shown in Table 4.

[0197] Table 4 Catalytic performance of the nano-catalysts in Example 1 and Comparative Example 1 in the hydrogenation reaction of styrene

[0198]

[0199] As Figure 1The synthesis route of the nano-catalyst is shown in the present application. As shown in Figure 2 The high-resolution TEM image of the nano-catalyst is shown, from which it can be seen that the ultra-small platinum nanoparticles are distributed on the surface of the carrier (darker color), which can prove that the particle size of the platinum nanoparticles is 1-3 nm. As shown in Figure 3 As shown, the high-resolution TEM image can also see the lattice fringes of the platinum nanoparticles, and the lattice spacing is 0.228 nm, which is consistent with the Pt (111) lattice spacing, indicating the formation of Pt nanoparticles, i.e. the formation of Pt core layer. As shown in Figure 4 As shown, the element distribution of the nano-catalyst can be analyzed from the EDS-mapping image, and it can be seen that the element distribution positions of P and Pt elements are consistent, which indicates that the Pt is closely combined with the organic phosphine ligand, i.e. the organic phosphine ligand is coated on the surface of the Pt NPs. The nano-catalyst has a core-shell nanostructure of the organic phosphine shell layer coating the Pt core layer.

[0200] As can be seen from Table 1, the selectivity of p-aminobenzaldehyde is obviously improved after introducing the organic phosphine, especially the catalytic effect of the nano-catalyst in Example 1 is significantly improved compared with the Pt / C catalyst in Comparative Example 1, the hydrogenation activity is increased from 28.6 % to 90.1 %, and the selectivity of p-aminobenzaldehyde is increased from 46.7 % to 96.2 %, which indicates that the organic phosphine has a significant regulating effect on the reaction process. However, due to the rigid structure of some phosphines containing benzene ring, the diffusion of the reactants is blocked, the apparent kinetic rate decreases, and the activity decreases. On the contrary, the flexible ligand can ensure the selectivity while the reactant molecules can quickly diffuse to the reaction interface due to its flexible structure, so that the activity and selectivity are doubled. In addition, Comparative Example 2 shows that if the organic phosphine ligand is added first and then the chloroplatinic acid is added in the preparation process of the nano-catalyst, the catalytic performance will decrease, which may be due to the uneven thickness of the ligand shell layer.

[0201] In order to make the flexible ligand modification layer have the best result on the reaction kinetics and reaction path, the present application adjusts the addition amount of the flexible organic phosphine to control the thickness of the modification layer. As can be seen from Table 2, with the increase of the addition amount of tri-n-octylphosphine, the activity first increases and then decreases, and considering the conversion rate and selectivity comprehensively, the performance is best when the molar ratio of Pt to tri-n-octylphosphine is 1:1. In terms of stability, as shown in Table 3, the nano-catalyst in Example 1 is used to perform the hydrogenation reaction of p-aminobenzaldehyde again, and the catalytic activity of the nano-catalyst does not decrease after five repeated hydrogenation reactions. Moreover, due to the dynamic reconstruction of the surface in the presence of hydrogen and reactants, the catalytic sites are more conducive to the reaction, so the activity and selectivity are slightly improved.

[0202] As shown in Table 4, the nano-catalyst in the application is also used in the C=C normal pressure hydrogenation reaction, and compared with the Pt / C catalyst in Comparative Example 1, the conversion rate of styrene is increased from 13.3% to 81.4%, i.e. the activity is increased by five times, which shows that the nano-catalyst can also have good catalytic activity in the C=C hydrogenation reaction.

[0203] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent process transformation made by using the specification of the application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A method for preparing an organophosphorus compound-shell-modified nanocatalyst, characterized in that, The process includes the following steps: adding a carbon support to an alcohol solvent and ultrasonically dispersing it; then adding an alcohol solution containing chloroplatinic acid and stirring at 0-15°C; subsequently adding an alcohol solution containing an organophosphorus compound and a reducing agent, and continuing stirring; finally, rotary evaporation and drying to obtain a nano-catalyst; wherein the organophosphorus compound includes one or more of triethylphosphine, tributylphosphine, tri-n-octylphosphine, di-tert-butylmethylphosphine, tris(3-methoxyphenyl)phosphine, tris(3,5-dimethyl)phosphine, and 2-diphenylphosphinebenzoic acid; and wherein the reducing agent is NaBH4 powder or an alcohol solution containing NaBH4. The nanocatalyst is a core-shell structure of a platinum catalyst supported on a carbon support surface, wherein the platinum catalyst has a core layer of platinum nanoparticles and a shell layer of organophosphorus compounds; the mass loading of Pt in the nanocatalyst is 1~10wt%, the molar ratio of organophosphorus compounds to Pt is 1:1, and the particle size of the platinum nanoparticles is 1~3nm.

2. The method for preparing the organophosphorus shell-modified nanocatalyst according to claim 1, characterized in that, The carbon support includes one or more of carbon black, carbon nanotubes, nitrogen-doped carbon, and graphene.

3. The method for preparing the organophosphorus shell-modified nanocatalyst according to claim 1, characterized in that, The alcohol solvent is one or more of ethanol, isopropanol, and n-propanol; the alcohol solvent used in the chloroplatinic acid-containing alcohol solution and the organophosphoric acid-containing alcohol solution is one or more of ethanol, isopropanol, and n-propanol.

4. The method for preparing the organophosphorus shell-modified nanocatalyst according to claim 1 or 3, characterized in that, The amount of reducing agent added is calculated based on a molar ratio of NaBH4 to Pt in chloroplatinic acid of 3~15:

1.

5. The application of a nanocatalyst prepared by any one of claims 1-4 in the hydrogenation reaction of nitro-containing aromatic substrates.

6. The application according to claim 5, characterized in that, The nitro-containing aromatic substrates include one or more of p-chloronitrobenzene, 3,5-dichloronitrobenzene, m-bromonitrobenzene, 4-nitrotoluene, and p-nitroacetophenone.

7. The application according to claim 5, characterized in that, The nitro-containing aromatic substrate is p-nitrobenzaldehyde.

8. The application of a nanocatalyst prepared by any one of claims 1-4 in the hydrogenation reaction of aromatic substrates containing carbon-carbon double bonds.

9. The application according to claim 8, characterized in that, The aromatic substrates containing carbon-carbon double bonds include one or more of 4-methoxystyrene, 4-methylstyrene, p-chlorostyrene, and p-bromostyrene.

10. The application according to claim 8, characterized in that, The aromatic substrate containing carbon-carbon double bonds is styrene.

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