CN120079413A

CN120079413A - Three-dimensional honeycomb structure g-C3N4 carrier, Pt/CN catalyst for phenol hydrogenation and preparation method

Info

Publication number: CN120079413A
Application number: CN202510236265.XA
Authority: CN
Inventors: 王欢; 王诗语; 赵阳; 董秀丽; 陈彦广; 宋华
Original assignee: Northeast Petroleum University
Current assignee: Northeast Petroleum University
Priority date: 2025-02-28
Filing date: 2025-02-28
Publication date: 2025-06-03

Abstract

The invention discloses a three-dimensional honeycomb structure g-C ₃ N ₄ carrier, a Pt/CN catalyst for phenol hydrogenation and a preparation method. The carrier has a specific surface area of up to 264.79 ^{m 2} /g and a pore size of up to 21.61 nm. Pt nanoparticles are highly dispersed and the interaction between the carrier and the g-C ₃ N ₄ interface is enhanced, which is beneficial to mass transfer and matrix adsorption processes. The catalyst preparation method is simple and can be prepared by a simple hydrothermal ethylene glycol reduction method without using H ₂ reduction. The catalyst is used for catalyzing phenol hydrogenation. Compared with the existing hydrogenation method, the reaction conditions are mild, and the catalyst has the characteristics of high reaction activity and high selectivity for cyclohexanol. Moreover, since the carrier has a large pore size and specific surface area, it is easier to adsorb simulated phenol molecules and accurately anchor Pt nanoparticles to make them highly dispersed, so that phenol can be completely converted into cyclohexanol through a hydrogenation reaction under the conditions of 0.5 MPa, 120° C. and 80 min.

Description

Three-dimensional honeycomb structure g-C 3N4 carrier, pt/CN catalyst for phenol hydrogenation and preparation method

Technical Field

The invention relates to the technical field of catalysts for phenol selective hydrogenation reaction, in particular to a metal catalyst taking a nitrogen-doped carbon graphite phase carbon nitride material as a load carrier.

Background

The selective hydrogenation of phenol is an important feedstock (cyclohexanone and cyclohexanol) in petroleum industry chemistry for the production of adipic acid, caprolactam, nylon-6, nylon-66 and KA oil. There are two routes for industrial cyclohexanol production, one is oxidation of cyclohexane and the other is hydrogenation of phenol. The oxidation process requires high temperature and pressure, the yield of the product is low, and the recovery step is also complicated. The non-ring-opening hydrogenation reaction way of phenol is generally that (1) phenol is directly hydrogenated to cyclohexanol, and (2) phenol is firstly selectively hydrogenated to cyclohexanone, and then cyclohexanone is further hydrogenated to cyclohexanol. In pathway (2), the formation of cyclohexanone, an intermediate, has some effect on the selectivity of cyclohexanol. Thus, of all the above reactions, the one-step selective hydrogenation of phenol to c=o is most preferred because it shortens the reaction steps and time, improves the efficiency of hydrogen utilization, reduces byproducts, and does not require separation of phenol from other byproducts.

In the catalyst for phenol hydrogenation reaction, besides the metal active component, the carrier is a support for the catalytic active component in the catalyst, which can provide a highly stable support structure, so that the catalyst has good thermal stability and mechanical strength, and therefore, the carrier plays a vital role. Typically, the support material is predominantly Al ₂O₃,SiO₂, MOF, carbon material, or the like.

The preparation process of the common carrier material is relatively complex and has high cost. Literature [Agnieszka Feliczak-Guzik：The effect ofmetal(Nb,Ru,Pd,Pt)supported on SBA-16on the hydrodeoxygenation reaction of phenol,doi:https://doi.org/10.1016/j.cattod.2018.06.046] uses a sol-gel method to obtain SBA-16 mesoporous SiO ₂ by stirring triblock copolymer Pluronic F127 (Sigma-Aldrich), hydrochloric acid and TEOS (Sigma-Aldrich) of ethylene oxide and structural directing agent propylene oxide for 0.5h and aging for 48h at 90 ℃ and then calcining for 6h at 550 ℃ in air. Then, 3wt.% Pt was supported on the SBA-16 carrier by an impregnation method to obtain an SBA-16/Pt catalyst. Dodecane was used as a solvent for reaction at 130 ℃ and 6MPa for 4 hours to give 2, 4-dimethylhexane with a selectivity of 84.2% at almost 100% phenol conversion. However, SBA-16/Pt catalysts have the problems of complex preparation and higher reaction conditions. Likewise, document [ PeterMortensen：Screening of Catalysts for Hydrodeoxygenation of Phenol as Model Compound for Bio-oil,doi:https://doi.org/10.1021/cs400266e] The Pt/C catalyst synthesized by taking C as a carrier can completely convert phenol hydrogenation reaction into cyclohexanol at 10MPa, 275 ℃ and 5 hours. Therefore, the method has important practical significance in developing and preparing the phenol cyclohexanol catalyst which is simple and easy to prepare, low in cost, short in reaction time, high in selectivity and good in activity.

In the technical field of 'photo' catalysts, a metal catalyst loaded by taking a nitrogen-doped carbon material as a carrier is a good hydrogenation catalyst. The introduction of nitrogen can stabilize metal nano particles, regulate electronic structure and improve electron migration capability, so that the photocatalytic activity is improved. g-C ₃N₄ is a special carbon-nitrogen material with easy preparation, low cost and unique surface properties such as functional Bronsted acid base sites, which can give the system catalytic activity not present in the original material. The band gap of g-C ₃N₄ is about 2.7eV, the visible light with the wavelength smaller than 460nm can be absorbed, solar energy is effectively utilized, the high photon-generated carrier separation efficiency is further shown, and the photocatalysis effect is improved. Therefore, people only use the catalyst as a photocatalyst in the fields of photocatalytic water hydrogen production, pollutant catalytic degradation, CO ₂ catalytic reforming and the like, and do not use the catalyst as a catalyst carrier for traditional organic catalytic conversion.

In addition, in the organic catalytic conversion reaction, a good carrier needs to have stable chemical properties, uniformly disperse active components, strong interaction with the active components, and the like. The traditional g-C ₃N₄ is generally of a two-dimensional lamellar graphene structure, and the specific surface area is 10-20cm ²/g. The CN atoms in the structure are hybridized by sp ² to form a highly delocalized pi conjugated system, so that the surface of the CN atoms is completely exposed with fewer active sites, which is not beneficial to the catalytic hydrogenation reaction.

Disclosure of Invention

In view of the above, the invention provides a three-dimensional honeycomb structure g-C ₃N₄ carrier, a Pt/CN catalyst for phenol hydrogenation and a preparation method thereof, which solve the problems that the preparation process of a carrier material for preparing cyclohexanol by catalytic hydrogenation of common phenol is relatively complex and has higher cost, and the activity of the Pt/C catalyst synthesized by taking C as the carrier can be converted under a certain temperature and pressure condition, so that the development and preparation of a simple and low-cost carrier are required, thereby providing a catalyst for preparing cyclohexanol by phenol with short reaction time, high selectivity and good activity.

In order to achieve the above object, according to a first aspect, the present invention provides a three-dimensional honeycomb structure g-C ₃N₄ carrier, which is prepared by:

Respectively dissolving melamine and cyanuric acid in DMSO, adding phosphoric acid into cyanuric acid solution, dropwise adding the melamine solution into the cyanuric acid solution added with phosphoric acid under stirring, stirring uniformly, completing self-assembly of melamine and cyanuric acid supermolecules, washing, drying and calcining white precipitate after centrifugal separation, and obtaining the three-dimensional honeycomb structure g-C ₃N₄ carrier.

Preferably, the phosphoric acid is concentrated phosphoric acid.

Preferably, the mass ratio of the melamine to the cyanuric acid is 1:1.

Preferably, preparing a DMSO solution of melamine in a molar ratio of 0.2:1, and preparing a DMSO solution of cyanuric acid in a molar ratio of 0.4:1;

the molar ratio of the concentrated phosphoric acid to the cyanuric acid is 0.1-0.3:1.

Preferably, the time for dropping the melamine solution is limited to 1.5 hours.

Preferably, the calcination treatment means heating to 550-600 ℃ at 2.3-5 ℃ per min under nitrogen atmosphere and maintaining for 2-4 hours.

In a second aspect, the Pt/CN catalyst for hydrogenating phenol of the present invention comprises:

A carrier and an active component, wherein the carrier is the three-dimensional honeycomb structure g-C ₃N₄ according to any one of the first aspect, and the active component is Pt nanoparticles supported on the carrier.

In a third aspect, the preparation method of the Pt/CN catalyst for phenol hydrogenation of the invention comprises the following steps:

Dispersing the three-dimensional honeycomb structure g-C ₃N₄ carrier in a mixed solution of glycol and distilled water, dropwise adding a platinum source solution, uniformly dispersing, carrying out hydrothermal reaction on the uniform dispersion, and carrying out centrifugation, washing and drying treatment on a hydrothermal product to obtain the Pt/CN catalyst.

Preferably, the platinum source solution is 1wt% sodium chloroplatinate aqueous solution, 0.2-0.4g of the carrier is ultrasonically dispersed in a mixed solution of 25-50mL of ethylene glycol and 15-30mL of distilled water for 30-60min, 1.5-3.5g of 1wt% sodium chloroplatinate aqueous solution is dropwise added under magnetic stirring, and the uniform dispersion is obtained by continuing ultrasonic.

Preferably, the hydrothermal reaction is at 140-180 ℃ for 22-26 hours.

The invention has the beneficial effects that:

The three-dimensional honeycomb structure g-C ₃N₄ carrier has the specific surface area as high as 264.79m ²/g, the pore diameter as high as 21.61nm, pt nano particles are highly dispersed and the interaction between the Pt nano particles and the g-C ₃N₄ interface is enhanced, the mass transfer and matrix adsorption processes are facilitated, and the three-dimensional honeycomb structure g-C ₃N₄ carrier has the following advantages:

(1) The preparation method of the catalyst is simple, and the platinum-loaded honeycomb catalyst is prepared by a simple hydrothermal glycol reduction method and can be obtained without H ₂ reduction;

(2) The catalyst is used for catalyzing phenol hydrogenation, and has the characteristics of mild reaction conditions, high reaction activity and high selectivity to cyclohexanol compared with the existing hydrogenation method;

(3) The catalyst carrier used in the invention is easy to prepare, has larger aperture and specific surface area, is easier to adsorb simulative phenol molecules, accurately anchors Pt nano particles to enable the simulative phenol molecules to be highly dispersed, and enables phenol to be completely converted into cyclohexanol through hydrogenation reaction under the conditions of 0.5MPa, 120 ℃ and 80 min;

(4) The catalyst of the invention has excellent stability and good repeated use performance.

Drawings

FIG. 1 is a synthetic route diagram of a supported CN-x (where x represents the amount of phosphoric acid, x=0.34 mL, 0.89mL, 1.36 mL) catalyst;

FIG. 2 is an XRD pattern for a catalyst of 1% Pt/CN-x (1% platinum nanoparticles supported on carrier CN-x, where x represents the amount of phosphoric acid, x=0.34 mL, 0.89mL, 1.36 mL);

In FIG. 3 (a), SEM (scanning electron microscope) image of CN-0.89 (added amount of phosphoric acid in carrier CN preparation process x=0.89 mL of CN-0.89) catalyst;

FIG. 4 is an X-ray photoelectron spectrum XPS of carrier CN-0.89 (the addition amount of phosphoric acid in the preparation process of carrier CN is x=0.89 mL), wherein (a) the total energy spectrum (b) is a 1s orbit energy spectrum of C element (C) and N element (d) are 1s orbit energy spectrum of O element (e) and P element (e) are 2P orbit energy spectrum;

In fig. 5, (a) and (b) are specific surface area and porosity analyzer BET plots of CN-x (where x represents the amount of phosphoric acid, x=0.34 mL, 0.89mL, 1.36 mL) catalyst, respectively;

FIG. 6 is a plot of phenol conversion versus cyclohexanol selectivity as a function of reaction time for a 1% Pt/CN-0.89 catalyst (reaction temperature 120 ℃ C. At 0.5 MPa);

FIG. 7 is a graph of the reusability of a catalyst with 1% Pt/CN-0.89 (1% platinum nanoparticles supported on carrier CN-x, where x represents the amount of phosphoric acid, x=0.89 mL).

Detailed Description

The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the following detailed description of the present disclosure, certain specific details are set forth in detail. However, for portions not described in detail, those skilled in the art can also fully understand the present disclosure.

Meanwhile, unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense rather than an exclusive or exhaustive sense, that is, in the sense of "including but not limited to".

In order to solve the problems described in the background art part of the present disclosure, the present disclosure provides a three-dimensional honeycomb structure g-C ₃N₄ (hereinafter abbreviated as CN) carrier with a high specific area, which is easy to be synthesized simply, and after Pt nanoparticles are loaded on the carrier, the carrier is used for preparing cyclohexanol by efficient catalytic hydrogenation of phenol. The method widens the application field of CN materials which are used as photocatalyst only in the past by utilizing the characteristics of easy preparation, low cost, stable chemical property and the like of CN, thereby being applied to an organic catalytic conversion system.

The disclosure also provides a preparation method of the CN carrier and the phenol hydrogenation catalyst.

As shown in fig. 1, the method for preparing the CN carrier according to each embodiment of the present disclosure is as follows:

Dissolving a certain amount of melamine and cyanuric acid in dimethyl sulfoxide DMSO respectively, then adding concentrated phosphoric acid into cyanuric acid solution, dropwise adding the melamine solution into cyanuric acid solution added with concentrated phosphoric acid under stirring, continuously stirring for a set time, centrifuging, washing the white precipitate obtained by centrifuging with water and ethanol for several times, drying, and finally calcining the white powder in a tube furnace, wherein the calcined product is used as a CN carrier and is expressed as CN-x, and x represents the amount of phosphoric acid.

In a specific embodiment, the step of respectively dissolving melamine and cyanuric acid in a certain amount of DMSO refers to respectively taking melamine and cyanuric acid with the mass ratio of 1:1, dissolving melamine in DMSO according to the molar ratio of 0.2:1, and dissolving cyanuric acid in DMSO according to the molar ratio of 0.4:1.

In a specific embodiment, the amount of concentrated phosphoric acid added to the cyanuric acid solution is in a molar ratio of 0.1-0.3:1, preferably 0.075-0.298:1, based on the molar ratio of concentrated phosphoric acid to cyanuric acid.

In a specific embodiment, the time for adding the melamine solution dropwise is limited to 1.5 hours, and the setting time for continuing stirring after the end of adding dropwise is 1.5-2.5 hours, preferably 2 hours.

In a specific embodiment, the calcination refers to heating to 550-600 ℃ at 2.3-5 ℃ per minute in a tube furnace under nitrogen atmosphere and holding for 2-4 hours.

The method for preparing the catalyst for phenol hydrogenation by loading Pt nano particles on the CN carrier comprises the following steps:

(1) Preparing a platinum source solution, preferably the platinum source solution of the present disclosure is a 1wt% aqueous solution of sodium chloroplatinate;

(2) Dispersing CN carrier in the mixed solution of glycol and distilled water, dropping sodium chloroplatinate aqueous solution while stirring, hydrothermal reaction at 140-180 deg.C for 22-26 hr, preferably 24 hr, centrifuging, washing and drying to obtain catalyst for hydrogenating phenol with carbon nitride as carrier and platinum.

In one embodiment, 0.2-0.4g of CN carrier is ultrasonically dispersed in a mixed solution of 25-50mL of ethylene glycol and 15-30mL of distilled water for 30-60min, and 1.5-3.5 g of 1wt% sodium chloroplatinate aqueous solution is dropwise added under magnetic stirring for further ultrasonic treatment for 30min, and the amount of 1wt% sodium chloroplatinate aqueous solution is preferably 1.593-3.186g.

The following are preferred embodiments of the present disclosure.

Example 1:

The preparation and characterization of the supported CN-0.34 and 1% Pt/CN-0.34 catalysts were carried out in this example, as follows:

1. Preparation of vector CN-0.34:

0.5g melamine and 0.51g cyanuric acid were dissolved in 20mL and 10mL DMSO, respectively. To the cyanuric acid solution was added 0.34mL of concentrated phosphoric acid, and the melamine solution was added dropwise to the cyanuric acid solution under magnetic stirring over 1.5h, followed by stirring for 2h and centrifugation, and the white precipitate was washed several times with water and ethanol and dried at 60 ℃ for 24h. The dried white powder was calcined in a tube furnace at 2.3 ℃ per minute to 550 ℃ for 4 hours to give carrier CN-0.34.

2. Preparation and characterization of 1% Pt/CN-0.34 catalyst:

1) Preparation of platinum Source solution (1 wt% sodium chloroplatinate aqueous solution):

0.1g of sodium chloroplatinate was dissolved in 9.9g of distilled water to obtain a 1% by weight aqueous solution of sodium chloroplatinate.

2) Preparation of 1% Pt/CN-0.34 catalyst:

Dispersing 0.2g of CN-0.34 carrier in a mixed solution of 25mL of glycol and 15mL of distilled water, carrying out ultrasonic treatment for 30min, dropwise adding 1.593g of 1wt% sodium chloroplatinate aqueous solution under strong magnetic stirring, continuing ultrasonic treatment for 30min, carrying out hydrothermal treatment at 140 ℃ for 24h, and finally carrying out centrifugal treatment at 800rpm, washing and drying treatment on the hydrothermal product to obtain the 1% Pt/CN-0.34 catalyst.

3) XRD, BET characterization of 1% Pt/CN-0.34 catalyst:

XRD characterization was performed on 1% Pt/CN-0.34 catalyst, and the result is shown in FIG. 2, wherein diffraction peaks of Pt nanoparticles appear on the (111) plane, which indicates that the Pt nanoparticles are successfully loaded on the CN-0.34 carrier.

BET characterization was performed on 1% Pt/CN-0.34 catalyst, and the specific surface area of 1% Pt/CN-0.34 catalyst was 180.2m ²/g and the pore diameter was 15.36nm as shown in FIGS. 5 (a) and (b).

Example 2:

The preparation and characterization of the supported CN-0.89 and 1% Pt/CN-0.89 catalysts were carried out in this example, and are described in detail as follows:

1. preparation and characterization of vector CN-0.89:

1) Preparation of vector CN-0.89:

0.5g melamine and 0.51g cyanuric acid were dissolved in 20mL and 10mL DMSO, respectively. Adding 0.89mL of concentrated phosphoric acid into the cyanuric acid solution, dropwise adding the melamine solution into the cyanuric acid solution in 1.5h under magnetic stirring, continuously stirring for 2h, and centrifuging. The white precipitate was washed several times with water and ethanol and dried at 60 ℃ for 24 hours. The dried white powder was calcined in a tube furnace at 2.3 ℃ per minute to 550 ℃ for 4 hours to give carrier CN-0.89.

2) XPS, SEM, BET characterization of CN-0.89 vector:

SEM characterization was performed on the CN-0.89 carrier, and the surface morphology of the carrier was observed by analysis, and the result is that the CN-0.89 carrier forms a three-dimensional porous honeycomb structure formed by assembling sheets as shown in FIG. 3.

XPS characterization is carried out on the CN-0.89 carrier, the result is shown in figure 4, and the figure 4 shows that trace P element exists in a sample, so that the phosphoric acid can regulate the morphology and specific surface area of the carrier, so that the CN-0.89 carrier exposes more active sites, and has the effect of promoting mass transfer.

As a result of BET characterization of the CN-0.89 carrier, the specific surface area of the CN-0.89 carrier was 264.7858m2/g and the average pore diameter was 21.610nm as shown in FIGS. 5 (a) and (b). The BET characterization result shows that the specific surface area and the pore diameter of the self-assembled CN-0.89 carrier are increased, so that the uniform dispersion of the active component Pt nano particles on the surface of the carrier is facilitated, and the catalytic activity is improved.

2. Preparation and characterization of 1% Pt/CN-0.89 catalyst:

2) Preparation of 1% Pt/CN-0.89 catalyst:

Dispersing 0.2g of CN-0.89 carrier in a mixed solution of 25mL of glycol and 15mL of distilled water, carrying out ultrasonic treatment for 30min, dropwise adding 1.593g of 1wt% sodium chloroplatinate aqueous solution under strong magnetic stirring, continuing ultrasonic treatment for 30min, carrying out hydrothermal treatment at 140 ℃ for 24h, and finally carrying out centrifugal treatment at 800rpm, washing and drying treatment on the hydrothermal product to obtain the 1% Pt/CN-0.89 catalyst.

3) XRD characterization of 1% Pt/CN-0.89 catalyst:

XRD characterization was performed on 1% Pt/CN-0.89 catalyst, and the result is shown in FIG. 2, wherein diffraction peaks of Pt nanoparticles appear on the (111) plane, which indicates that the Pt nanoparticles are successfully loaded on the CN-0.89 carrier.

Example 3:

the preparation and characterization of the supported CN-1.36 and 1% Pt/CN-1.36 catalysts were carried out in this example, and are described in detail as follows:

1. preparation of vector CN-1.36:

0.5g melamine and 0.51g cyanuric acid were dissolved in 20mL and 10mL DMSO, respectively. 1.36mL of concentrated phosphoric acid is added into the cyanuric acid solution, the melamine solution is added into the cyanuric acid solution in a dropwise manner within 1.5h under magnetic stirring, and the stirring is continued for 2h and then the solution is centrifuged. The white precipitate was washed several times with water and ethanol and dried at 60 ℃ for 24 hours. The dried white powder was calcined in a tube furnace at 2.3 ℃ per minute to 550 ℃ for 4 hours to give carrier CN-1.36.

2. Preparation and characterization of 1% Pt/CN-1.36 catalyst:

2) Preparation of 1% Pt/CN-1.36 catalyst:

dispersing 0.2g of CN-1.36 carrier in a mixed solution of 25mL of glycol and 15mL of distilled water, carrying out ultrasonic treatment for 30min, dropwise adding 1.593g of 1wt% sodium chloroplatinate aqueous solution under strong magnetic stirring, continuing ultrasonic treatment for 30min, carrying out hydrothermal treatment at 140 ℃ for 24h, and finally carrying out centrifugal treatment at 800rpm, washing and drying treatment on the hydrothermal product to obtain the 1% Pt/CN-1.36 catalyst.

3) XRD characterization of 1% Pt/CN-1.36 catalyst:

XRD characterization was performed on the 1% Pt/CN-1.36 catalyst, and the result is shown in FIG. 2, wherein diffraction peaks of Pt nanoparticles appear on the (111) plane, which indicates that the Pt nanoparticles are successfully loaded on the CN-1.36 carrier.

BET characterization was performed on 1% Pt/CN-1.36 catalyst, and the specific surface area of 1% Pt/CN-1.36 catalyst was 190.5m ²/g and the pore diameter was 12.6nm as shown in FIGS. 5 (a) and (b).

Example 4:

This example used a 1% pt/CN-0.89 catalyst for the selective hydrogenation of phenol to make cyclohexanol experiments, as follows:

And preparing a reaction solution system with the mass fraction of phenol of 3% by taking decalin as a solvent. Adding 1% Pt/CN-0.89 catalyst, wherein the mass ratio of the catalyst to the phenol solution is 0.002:1, sealing the reaction kettle, detecting the leakage of nitrogen, replacing with hydrogen for three times, introducing hydrogen, stirring and reacting at 600rpm under the conditions of 0.5MPa and 120 ℃, and obtaining a curve of the conversion rate of phenol and the selectivity of cyclohexanol as the reaction time changes, wherein the curve is shown in figure 6.

Wherein, the selectivity of the cyclohexanol can reach 90.4% under the conditions of 0.5MPa, 120 ℃ and 80min of reaction time of the 1% Pt/CN-0.89 catalyst, and the conversion rate of phenol can reach 94.1%. The reason is that the CN-0.89 carrier exposes more active sites and promotes mass transfer, thereby being beneficial to the uniform dispersion of the active component Pt nano particles on the surface of the carrier and further improving the catalytic activity.

The 1% Pt/CN-0.89 catalyst has the characteristics of high phenol hydrogenation activity, good cyclohexanol selectivity and short reaction time.

Example 5:

The recycling experiment of the 1% Pt/CN-0.89 catalyst is carried out in the embodiment, and the recycling experiment is carried out for 5 times after the phenol hydrogenation reaction, and the experimental process is as follows:

And (3) centrifugally drying and recycling the catalyst after each catalytic hydrogenation reaction. And preparing a reaction solution system with the mass fraction of phenol of 3% by taking decalin as a solvent. Adding 1% Pt/CN-0.89 catalyst, wherein the mass ratio of the catalyst to the phenol solution is 0.002:1, sealing the reaction kettle, detecting the leakage of nitrogen, replacing with hydrogen for three times, introducing hydrogen, stirring and reacting for 80min at the temperature of 0.5MPa and 120 ℃, and after five circulation experiments, the catalytic activity and the selectivity of the target product cyclohexanol are not obviously changed, thus proving that the catalyst has excellent stability.

The above examples are merely representative of embodiments of the present disclosure, which are described in more detail and are not to be construed as limiting the scope of the present disclosure. It should be noted that modifications, equivalent substitutions, improvements, etc. can be made by those skilled in the art without departing from the spirit of the present disclosure, which are all within the scope of the present disclosure. Accordingly, the scope of protection of the present disclosure should be determined by the following claims.

Claims

1. A three-dimensional honeycomb structure g-C ₃N₄ carrier, characterized in that the carrier is prepared by a method comprising:

Respectively dissolving melamine and cyanuric acid in DMSO, adding phosphoric acid into cyanuric acid solution, dropwise adding the melamine solution into the cyanuric acid solution added with phosphoric acid under stirring, stirring uniformly, washing, drying and calcining the centrifugally separated white precipitate to obtain the three-dimensional honeycomb structure g-C ₃N₄ carrier.

2. The three-dimensional honeycomb structure g-C ₃N₄ carrier according to claim 1, wherein:

The phosphoric acid is concentrated phosphoric acid.

3. The three-dimensional honeycomb structure g-C ₃N₄ carrier according to claim 2, wherein:

The mass ratio of the melamine to the cyanuric acid is 1:1.

4. The three-dimensional honeycomb structure g-C ₃N₄ carrier according to claim 3, wherein:

preparing a DMSO solution of melamine according to a molar ratio of 0.2:1, and preparing a DMSO solution of cyanuric acid according to a molar ratio of 0.4:1;

5. The three-dimensional honeycomb structure g-C ₃N₄ support according to any one of claims 1 to 4, wherein:

The time for dropping the melamine solution is limited to 1.5 hours.

6. The three-dimensional honeycomb structure g-C ₃N₄ carrier according to claim 5, wherein:

The calcination treatment is to heat to 550-600 ℃ at 2.3-5 ℃ per min under nitrogen atmosphere and keep for 2-4h.

7. A Pt/CN catalyst for the hydrogenation of phenol, comprising:

a carrier and an active component, wherein the carrier is the three-dimensional honeycomb structure g-C ₃N₄ according to any one of claims 1 to 6, and the active component is Pt nanoparticles supported on the carrier.

8. The preparation method of the Pt/CN catalyst for phenol hydrogenation is characterized by comprising the following steps:

9. The method for preparing a Pt/CN catalyst for hydrogenating phenol according to claim 8, wherein:

The platinum source solution is 1wt% of sodium chloroplatinate aqueous solution, 0.2-0.4g of the carrier is ultrasonically dispersed in a mixed solution of 25-50mL of ethylene glycol and 15-30mL of distilled water for 30-60min, 1.5-3.5g of 1wt% of sodium chloroplatinate aqueous solution is dropwise added under magnetic stirring, and the uniform dispersion is obtained by continuing ultrasonic.

10. The method for preparing a Pt/CN catalyst for the hydrogenation of phenol according to claim 8 or 9, characterized in that:

the hydrothermal reaction is carried out for 22-26 hours at 140-180 ℃.