CN110665522A - Application of catalyst for depositing metal particles in carbon nano tube in reaction of synthesizing cyclohexane through selective catalytic hydrogenation of benzene - Google Patents

Abstract

The invention discloses the application of a carbon nanotube-deposited metal particle catalyst in the selective catalytic hydrogenation of benzene to synthesize cyclohexane. The catalyst is composed of carbon nanotubes, phosphorus-doped carbon quantum dots and metal nanoparticles , the carbon nanotubes are single-walled or multi-walled carbon tubes with openings, the outer walls of the carbon nanotubes are loaded with carbon quantum dots, and the inner walls of the carbon nanotubes are inlaid with metal nanoparticles; the metals are palladium, platinum, gold, ruthenium , one of iridium, nickel, and cobalt; the size of the phosphorus-doped carbon quantum dots is not greater than 10 nm, and the phosphorus content is 0.1-8.0 wt%; in the carbon nanotube deposition metal particle catalyst, phosphorus-doped carbon quantum dots are The loading amount of carbon quantum dots is 0.5-8.0 wt%, and the loading amount of metal is 0.1-10.0 wt%. When the catalyst is applied to the selective catalytic hydrogenation of benzene to cyclohexane, under the synergistic effect of the confinement effect of carbon quantum dots, embedded metal particles and carbon nanotubes, high conversion rate, high selectivity and high Stability, high catalytic efficiency and long catalyst life.

Description

Application of metal particle catalysts deposited inside carbon nanotubes in selective catalytic hydrogenation of benzene to cyclohexane

(1) Technical field

The invention relates to the application of a metal particle catalyst deposited in carbon nanotubes in the reaction of benzene selective catalytic hydrogenation to synthesize cyclohexane.

(2) Technical background

Carbon nanotubes are excellent catalytic materials due to their structural defects, curved surfaces, unique lumen structure, and electrical conductivity. Based on the collision theory of chemical reactions, there is a significantly reduced reaction space in the tube, and the unique interaction between reactants, products and the inner wall of carbon nanotubes will affect the progress of chemical reactions. Through theoretical calculations, Santis et al. learned that when the chemical reaction is confined within a small-sized pore size, the reaction kinetics are significantly changed, and the reaction speed can jump by orders of magnitude. Lu et al. used DFT theory to calculate the reaction mechanism of confinement in carbon nanotubes, and found that when the reaction confinement was inside carbon nanotubes, the barrier affecting the progress of the reaction was significantly reduced, and as the diameter of carbon nanotubes decreased, the inside of the carbon nanotubes decreased. The reactivity of the reactants is enhanced. Therefore, the carbon nanotube-embedded metal particle catalyst showed excellent catalytic performance in synthesis gas conversion to ethanol, Fischer _- Tropsch reaction, benzene hydrogenation reaction and NH decomposition reaction.

At present, the main preparation methods of metal catalysts supported in tubes are: in-situ packing method, gas phase packing method and liquid phase packing method. In the in-situ filling method, in the process of preparing carbon nanotubes by means of arc method, microwave method, etc., metals or compounds are formed in-situ in the cavities and shells of carbon nanotubes. Generally speaking, the in-situ filling method can fill a variety of metals with higher melting points and higher surface tension, but the filling yield obtained by the in-situ filling method is relatively low, and some metal carbides or metal particles will be assembled during the filling process. into the carbon nanotube shell. The gas phase filling method is a method for carrying out high temperature reaction in the gas phase. That is, the carbon nanotubes are mixed with the filler under a certain pressure and temperature, and the filler is vaporized by heating and enters the interior of the carbon nanotubes. The advantage of the gas phase method is that only the gas that can react with carbon nanotubes is needed in the reaction, no more reagents are required, no pollution to the environment, and no other substances are introduced into the system; the disadvantage is that the opening rate of carbon nanotubes is low, requiring 500 At a high temperature of ~1000 °C, it is difficult to control the appropriate reaction time and temperature, and there is amorphous carbon accumulated in the lumen, which is not easy to fill. The liquid filling method mixes and grinds the filler and carbon nanotubes to make the two fully contact, and then raises the temperature to above the melting point of the filler, and the melted filler enters the carbon nanotube under capillary action. The filling of salts such as metal halides and oxides is often carried out by melting the filling.

However, the existing methods for preparing metal particles embedded in carbon nanotubes have defects such as complicated process, difficult regulation, and low catalyst product yield. In the hydrogenation of benzene, its catalytic performance still has problems such as low activity and low selectivity.

(3) Contents of the invention

The object of the present invention is to provide a kind of application of metal particle catalyst deposited in carbon nanotubes with carbon quantum dots supported on the outer wall of the tube in the reaction of benzene selective catalytic hydrogenation to synthesize cyclohexane, in carbon quantum dots, embedded metal particles and carbon Under the synergistic effect of the confinement effect of nanotubes, high conversion rate, high selectivity and high stability, high catalytic efficiency and long catalyst life are achieved.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention provides the application of a catalyst for depositing metal particles in carbon nanotubes in the selective catalytic hydrogenation of benzene to synthesize cyclohexane. The catalyst is composed of carbon nanotubes, phosphorus-doped carbon quantum dots and metal nanoparticles , the carbon nanotubes are single-walled or multi-walled carbon tubes with openings, the outer walls of the carbon nanotubes are loaded with carbon quantum dots, and the inner walls of the carbon nanotubes are inlaid with metal nanoparticles; the metals are palladium, platinum, gold, ruthenium , one of iridium, nickel, and cobalt; the size of the phosphorus-doped carbon quantum dots is not more than 10nm, and the phosphorus content is 0.1-8.0wt%; in the metal particle catalyst deposited in the carbon nanotubes, phosphorus-doped carbon quantum dots are The loading amount of carbon quantum dots (the mass ratio of carbon quantum dots to carbon nanotubes) is 0.5-8.0 wt %, and the loading amount of metal is 0.1-10.0 wt %.

Preferably, in the catalyst for depositing metal particles in carbon nanotubes, the loading amount of carbon quantum dots is 0.5-5.0 wt %. Preferably, in the catalyst, the metal loading is 0.5-5.0 wt%.

Preferably, the size of the phosphorus-doped carbon quantum dots is 2.5-5.5 nm.

Preferably, the catalyst for depositing metal particles in the carbon nanotubes can be prepared by the following method:

1) The carbon nanotubes are placed in concentrated nitric acid (65-68wt%) and heated to reflux, cooled to air temperature after the end, washed with water until the filtrate is neutral, and then dried to obtain acid-treated carbon nanotubes; Freshly prepared carbon nanotubes are tubes grown on metal particles, usually closed. In order to use the inner space of the tube to remove the metal particles of the long carbon tubes, concentrated nitric acid is used for pretreatment;

2) Disposing the phosphorus-doped carbon quantum dot solution and the acid-treated carbon nanotubes obtained in step 1) into a dispersion liquid, fully stirring so that the carbon quantum dots are loaded on the outer wall of the carbon nanotubes, suction filtration, and drying to obtain Carbon nanotubes loaded with carbon dots;

3) configuring the carbon nanotubes loaded with carbon dots obtained in step 2) into a slurry with deionized water, adding an aqueous solution containing metal ions under stirring, and the metal ions and chloride ions in the aqueous solution form complex anions, After fully stirring, suction filtration, washing until the pH value of the filtrate is neutral, and drying to obtain a catalyst for depositing metal particles in carbon nanotubes.

In the above preparation method of the present invention, the phosphorus-doped carbon quantum dots and carbon nanotubes are adsorbed on the outer wall of the carbon tube through π-π conjugation, and then converted into excellent electron donating centers, and then the electron donating centers of the phosphorus-doped carbon quantum dots are used. The characteristic induces negatively charged metal complex ions to spontaneously enter the tube and deposit on the inner wall. The electron-rich nature of phosphorus atoms is conducive to metal ions entering the tube and being loaded on the inner wall of the tube, so as to realize the small particle size of metal active components in the carbon nanotube and even distribution.

In the above step 1), the nitric acid treatment is a conventional treatment method for opening the carbon tube and removing residual metal. Preferably, in the acid treatment process of carbon nanotubes in step 1), the ratio of carbon nanotubes and nitric acid is 1-10g:20-100ml, the treatment temperature is 45-95°C, and the condensation reflux is 2-15h. Preferably, the drying conditions are: drying at 50-100° C. for 1-10 hours. Preferably, the diameter distribution of the carbon nanotubes is 20-40 nm, and the specific surface area is >150 m ² /g.

In the present invention, the phosphorus-doped carbon quantum dots can be prepared with reference to the prior art. Preferably, the phosphorus-doped carbon quantum dots use humic acid as a raw material, and are synthesized by hydrothermal method. The specific process is as follows: take humic acid and ethanol in a beaker, the ratio is 0.5-5.0g:5-100mL, and the mechanical Stir until the mixture is uniform; then transfer to a hydrothermal kettle, hydrothermally heat it for 10-24 hours at 120-200 ° C, and then naturally cool; then carry out centrifugation under the condition that the rotating speed is 20000r/min (remove the organic particles that are not carbonized completely) ), the supernatant is transferred to the dialysis treatment in the two-layer dialysis bag with a molecular weight cut-off of 100-10000 Daltons, and the carbon dot solution in the middle of the two layers is the carbon quantum dot solution of the present invention, and finally concentrated to The concentration is 0.5-25.0mg/L. In this method, the size of the quantum dots can be controlled by controlling the molecular weight cut-off of the dialysis bag. As a further preference, the molecular weight cut-off of the dialysis bag is 3000-7000 Daltons, more preferably 3500-6500 Daltons.

Step 2) of the present invention is preferably implemented as follows: the phosphorus-doped carbon quantum dot solution and the acid-treated carbon nanotubes are fed according to the loading of the phosphorus-doped carbon quantum dots, stirred for 10-60 min, and the solid obtained is filtered. The particles are placed in a vacuum oven and dried at a temperature of 50-100° C. for 2-15 hours to obtain carbon nanotubes loaded with carbon dots.

Step 3) of the present invention is preferably implemented as follows: the carbon nanotubes loaded with carbon dots obtained in step 2) are configured into a slurry according to the feeding ratio of the carbon nanotubes loaded with carbon dots to water as 1g: 5-35ml, and at 5 Under -40°C and stirring, add the corresponding aqueous solution containing metal ions according to the metal loading. The drop rate of the aqueous solution containing metal ions is 1d/1-10s. After the addition is completed, continue to stir for 2-6h and suction , washed until the pH value is neutral, and dried at 50-100° C. for 3-15 hours to obtain the catalyst.

Preferably, the application method is as follows: evenly mixing the metal particle catalyst deposited in carbon nanotubes with quartz sand particles, the quartz sand particle size is 0.5-2mm, put into a fixed-bed reactor, and preheated with hydrogen at 50-150°C. Treat for 0.5-2h, then heat up to 150-250°C and maintain a constant temperature; set the temperature of the container containing benzene to 20-50°C, and flow 1-10ml/min of hydrogen through this container to bring benzene vapor into the reactor, and carry out benzene The hydrogenation reaction produces cyclohexane. The hydrogenation products were analyzed online by an Agilent 7890A gas chromatograph.

Compared with the prior art, the beneficial effects of the present invention are embodied in:

1) In the deposition of metal particle catalysts in carbon nanotubes, the present invention designs the catalyst structure to load carbon quantum dots outside the tube, inlaid metal particles in the tube, electron donating characteristics of carbon quantum dots, carbon tubes to metal particles and carbon tubes to reactants The confinement effect of molecules makes the catalyst have specific catalytic properties. When the catalyst is applied to the selective catalytic hydrogenation of benzene to cyclohexane, under the synergistic effect of the confinement effect of carbon quantum dots, embedded metal particles and carbon nanotubes, high conversion rate, high selectivity and high Stability, high catalytic efficiency and long catalyst life.

2) In the preparation method of the catalyst of the present invention, the metal ions of anions are driven to the inner wall of the carbon tube by electrostatic action through the electron-rich characteristics of the carbon quantum dots supported on the outer wall of the carbon tube, which significantly improves the utilization rate of the metal. The method is simple, easy to implement, easy to control and low in cost.

(4) Description of drawings

a and b in FIG. 1 are the electron microscope images of the catalysts prepared in Comparative Example 1 and Example 1, respectively.

Figure 2 shows the percentage of metal particles in carbon nanotubes in the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 3, where 1 is Comparative Example 1; 2 is Comparative Example 3; 3 is Example 1, data source Statistically obtained by randomly selecting 500 particles (characterized by TEM).

(5) Specific implementation methods

The technical scheme of the present invention is described in detail below with specific embodiments, but the protection scope of the present invention is not limited thereto:

The activated carbon used in the examples was Norit 800, the carbon tube was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd., and the graphene was purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

Example 1

1) Take humic acid and ethanol in a beaker, the ratio is 0.5g:15mL, and mechanically stir until the mixture is uniform. Then transferred to a hydrothermal kettle, hydrothermally heated at 160°C for 15 hours, and then cooled naturally. Subsequently, centrifugation was carried out at a rotational speed of 20,000 r/min (to remove uncarbonized organic particles), and the supernatant was transferred to a two-layer dialysis bag with a molecular weight of 3500-5000 Daltons for dialysis treatment. The dot solution is the required carbon quantum dot solution, which is finally concentrated to a concentration of 5.0 mg/L under shading and low temperature. After testing, the phosphorus content in the carbon dots is 5%.

2) Weigh 10g of carbon nanotubes (diameter distribution 20-40nm, specific surface area>150m ² /g) and put it into a round-bottomed flask, then measure concentrated nitric acid (65-68wt%) and add it to the flask, carbon nanotubes and nitric acid The ratio was 5g:50ml, and then the flask was placed in a hydrothermal pot at 90°C for heating and refluxing for 5h. After refluxing, take out the flask and cool it to room temperature, transfer it to the funnel, add deionized water, and continuously perform water washing and suction filtration until the filtrate is neutral. The acid-treated carbon nanotubes are obtained and used for later use.

3) The carbon quantum dots solution prepared in step 1) and the acid-treated carbon nanotubes were prepared into a mixed solution, and the mass ratio of carbon dots to carbon nanotubes was 5.0 wt %, then the solution was placed on a magnetic stirrer and stirred, and pumped after 30 minutes. filter, and then put the obtained solid particles into a vacuum oven to dry at 100° C. for 5 h to obtain carbon nanotubes loaded with carbon dots.

4) The solid obtained in step 3) and deionized water are configured into a slurry, the ratio of solid:water is 1g: 5ml, and the loading is 5.0wt% corresponding palladium ion [PdCl ₄ ] ^2- The aqueous solution, the dropping rate is 1d/5S. After stirring for 6 hours, suction filtration, washing until the pH value is neutral, and drying at 100° C. for 15 hours to obtain the catalyst of the invention.

Examples 2-15

The catalyst was prepared with reference to Example 1, and the specific reaction parameters were shown in Table 1.

Table 1

Note: Forms of metal ions in the immersion solution: [PdCl ₄ ] ^2- , [PtCl ₄ ] ^2- , [IrCl ₄ ] ^2- , [AuCl ₄ ] ^2- , [NiCl ₄ ] ^2- , [CoCl 4 ] 2- , [CoCl ₄ ] ^2- , [RuCl ₄ ] ^2- .

Comparative Example 1

No carbon quantum dots were added, and other preparation methods were the same as those in Example 1.

Comparative Example 2

Graphene is used to replace carbon nanotubes, and the rest of the preparation methods are the same as those in Example 1. Graphene is a two-dimensional carbon nanomaterial with a hexagonal honeycomb lattice composed of carbon atoms with sp ² hybrid orbitals, and does not have a tubular structure.

Comparative Example 3

The carbon tube deposited metal particle Pd/CNT (5%) catalyst was prepared by the preparation method reported in Journal of Molecular Catalysis A: Chemical 323 (2010) 33-39.

Comparative Example 4

Dialysis was carried out using a dialysis membrane with a molecular weight of 1000-1500 Daltons, and the other preparation methods were the same as those in Example 1.

Comparative Example 5

1) Take citric acid and ethanol in a beaker, the ratio is 0.5g:15mL, and mechanically stir until the mixture is uniform. Then transferred to a hydrothermal kettle, hydrothermally heated at 160°C for 15 hours, and then cooled naturally. Subsequently, centrifugation was carried out at a rotational speed of 20,000 r/min (to remove uncarbonized organic particles), and the supernatant was transferred to a two-layer dialysis bag with a molecular weight of 3500-5000 Daltons for dialysis treatment. The dot solution is the desired carbon quantum dot solution (the carbon quantum dots do not contain heteroatoms), and finally concentrated to a concentration of 5.0 mg/L under shading and low temperature.

Steps 2)-4) are the same as in Example 1 to obtain a catalyst.

Example 16

The catalyst of Example 1 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120 ° C for 1.5 h, and then heated to 160 ° C and kept at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 89% after 5 hours, the test benzene conversion rate was 90% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 17

The catalyst of Example 2 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 100 ° C for 1.5 h, and then heated to 200 ° C and kept at a constant temperature. The temperature of the container containing benzene was set to 20°C, and 8ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 92% after 5 hours, the test benzene conversion rate was 93% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 18

The catalyst of Example 3 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 50 °C for 2 hours, and then heated to 180 °C and kept at a constant temperature. The temperature of the container containing benzene was set to 40°C, and 10 ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 91% after 5 hours, the test benzene conversion rate was 92% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 19

The catalyst of Example 4 was mixed evenly with quartz sand particles, the quartz sand particle size was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.0h, and then heated to 250°C at a constant temperature. The temperature of the container containing benzene was set to 50°C, and 2ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 95% after 5 hours, the test benzene conversion rate was 96% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 20

The catalyst of Example 5 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 80°C for 1.5h, and then heated to 180°C at a constant temperature. The temperature of the container filled with benzene is set to 20°C, and the hydrogen of 6 ml/min flows through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 94% after 5 hours, the test benzene conversion rate was 96% after 20 hours, and the cyclohexane selectivity was both 100%.

Example 21

The catalyst of Example 6 was mixed with quartz sand particles, the quartz sand particle size was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 60 ° C for 2.0 h, and then heated to 220 ° C and kept at a constant temperature. The temperature of the container containing benzene was set to 35°C, and 1ml/min of hydrogen flowed through this container to bring benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 96% after 5 hours, the test benzene conversion rate was 97% after 20 hours, and the cyclohexane selectivity was both 100%.

Example 22

The catalyst of Example 7 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 80°C for 1.5h, and then heated to 150°C at a constant temperature. The temperature of the container containing benzene was set to 40°C, and 5ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 98% after 5 hours, the test benzene conversion rate was 98% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 23

The catalyst of Example 8 was mixed with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 200°C at a constant temperature. The temperature of the container containing benzene was set to 30°C, and 8ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 95% after 5 hours, the test benzene conversion rate was 94% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 24

The catalyst of Example 9 and quartz sand particles were mixed evenly, and the quartz sand particle size was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 140 ° C for 0.5 h, and then heated to 150 ° C and kept at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 93% after 5 hours, the test benzene conversion rate was 94% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 25

The catalyst of Example 10 was mixed evenly with quartz sand particles, the quartz sand particle size was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 93% after 5 hours, the test benzene conversion rate was 94% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 26

The catalyst of Example 11 was mixed with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 110 ° C for 2.0 h, and then heated to 160 ° C and kept at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 97% after 5 hours, the test benzene conversion rate was 97% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 27

The catalyst of Example 12 was mixed evenly with quartz sand particles, the quartz sand particle size was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 130°C for 1.5h, and then heated to 180°C at a constant temperature. The temperature of the container filled with benzene was set to 40°C, and 6ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 92% after 5 hours, the test benzene conversion rate was 92% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 28

The catalyst of Example 13 was mixed evenly with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 100°C for 1.5h, and then heated to 180°C at a constant temperature. The temperature of the container filled with benzene is set to 20°C, and the hydrogen of 6 ml/min flows through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 95% after 5 hours, the test benzene conversion rate was 96% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 29

The catalyst of Example 14 was mixed evenly with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 200°C at a constant temperature. The temperature of the container containing benzene was set to 20°C, and 5ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 96% after 5 hours, the test benzene conversion rate was 96% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 30

The catalyst of Example 15 was mixed evenly with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 150°C for 0.5h, and then heated to 240°C at a constant temperature. The temperature of the container containing benzene was set to 20°C, and 8ml/min of hydrogen flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 94% after 5 hours, the test benzene conversion rate was 96% after 20 hours, and the cyclohexane selectivity was both 100%.

Example 31

The catalyst of Comparative Example 1 was mixed evenly with quartz sand particles, the particle size of the quartz sand was 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 65% after 5 hours, the test benzene conversion rate was 66% after 20 hours, and the cyclohexane selectivity was both 100%.

Example 32

The catalyst of Comparative Example 2 was mixed evenly with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 45% after 5 hours, the test benzene conversion rate was 46% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 33

The catalyst of Comparative Example 3 was evenly mixed with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 55% after 5 hours, the test benzene conversion rate was 56% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 34

The catalyst of Comparative Example 4 was evenly mixed with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 86% after 5 hours, the test benzene conversion rate was 87% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 35

The catalyst of Comparative Example 5 was mixed evenly with quartz sand particles with a particle size of 0.5-2 mm, put into a fixed bed reactor, pretreated with hydrogen at 120°C for 1.5h, and then heated to 160°C at a constant temperature. The temperature of the container filled with benzene was set to 30°C, and the hydrogen of 6 ml/min flowed through this container to bring the benzene vapor into the reactor to carry out the benzene hydrogenation reaction. The hydrogenation products were analyzed online using an Agilent 7890A gas chromatograph. The test benzene conversion rate was 80.1% after 5 hours, the test benzene conversion rate was 80.1% after 20 hours, and the cyclohexane selectivity was all 100%.

Example 36

Example 23 The catalyst stability test was carried out, and the results showed that within 100 hours, the average conversion rate was 95.5%, and the average selectivity of C=C double bond hydrogenation was 100%.

Claims (8)

1. the application in the reaction of benzene selective catalytic hydrogenation to synthesize cyclohexane by depositing metal particle catalyst in carbon nanotube, it is characterized in that: described catalyst is made of carbon nanotube, phosphorus-doped carbon quantum dots and metal nanotubes. Particle composition, the carbon nanotubes are single-walled or multi-walled carbon tubes with openings, the outer walls of the carbon nanotubes are loaded with carbon quantum dots, and the inner walls of the carbon nanotubes are inlaid with metal nanoparticles; the metals are palladium, platinum, gold , one of ruthenium, iridium, nickel, and cobalt; the size of the phosphorus-doped carbon quantum dots is not more than 10nm, and the phosphorus content is 0.1-8.0wt%; in the carbon nanotube deposition metal particle catalyst, phosphorus-doped The loading amount of heterocarbon quantum dots is 0.5-8.0 wt%, and the loading amount of metal is 0.1-10.0 wt%. 2 . The application according to claim 1 , wherein the size of the phosphorus-doped carbon quantum dots is 2.5-5.5 nm. 3 . 3. The application according to claim 1, wherein: the catalyst for depositing metal particles in the carbon nanotube is prepared by the following method: 1) placing the carbon nanotubes in concentrated nitric acid for heating and refluxing, cooling to room temperature after finishing, washing with water until the filtrate is neutral, and then drying to obtain acid-treated carbon nanotubes; 2) Disposing the phosphorus-doped carbon quantum dot solution and the acid-treated carbon nanotubes obtained in step 1) into a dispersion liquid, fully stirring so that the carbon quantum dots are loaded on the outer wall of the carbon nanotubes, suction filtration, and drying to obtain Carbon nanotubes loaded with carbon dots; 3) configuring the carbon nanotubes loaded with carbon dots obtained in step 2) into a slurry with deionized water, adding an aqueous solution containing metal ions under stirring, and the metal ions and chloride ions in the aqueous solution form complex anions, After fully stirring, suction filtration, washing until the pH value of the filtrate is neutral, and drying to obtain a catalyst for depositing metal particles in carbon nanotubes. 4. The application according to claim 3, wherein: the phosphorus-doped carbon quantum dots are prepared by the following method: take humic acid and ethanol in a beaker, and the ratio is 0.5-5.0g:5-100mL, Stir mechanically until the mixture is uniform; then transfer to a hydrothermal kettle, hydrothermally heat it at 120-200°C for 10-24 hours, and then naturally cool; then perform centrifugation at a rotational speed of 20,000 r/min, and the supernatant is transferred to interception Dialysis treatment is carried out in a two-layer dialysis bag with a molecular weight of 100-10,000 Daltons, and the carbon dot solution in the middle of the two layers is the carbon quantum dot solution, which is finally concentrated to a concentration of 0.5-25.0 mg/L under shading and low temperature. 5. The application according to claim 4, wherein the molecular weight cut-off of the dialysis bag is 3000-7000 Daltons. 6. The application according to one of claims 3-5, characterized in that: step 2) is implemented as follows: the carbon nanotubes after the phosphorus-doped carbon quantum dot solution and acid treatment are treated according to phosphorus-doped carbon quantum dots The loading amount of the dots is charged, stirred for 10-60min, and the solid particles obtained by filtration are placed in a vacuum oven and dried at a temperature of 50-100°C for 2-15h to obtain carbon nanotubes loaded with carbon dots. 7. The application according to one of claims 3-5, characterized in that: step 3) is implemented as follows: the carbon nanotubes loaded with carbon dots obtained in step 2) are carried out according to the carbon nanotubes loaded with carbon dots and The feeding ratio of water is 1g: 5-35ml to prepare a slurry. Under the state of 5-40°C and stirring, add the corresponding aqueous solution containing metal ions according to the metal loading, and the dropping rate of the aqueous solution containing metal ions is 1d/1 -10s, after the dropwise addition is completed, continue to stir for 2-6h, filter with suction, wash until the pH value is neutral, and dry at 50-100°C for 3-15h to obtain the catalyst. 8. The application according to claim 1 or 2, characterized in that: the application method is as follows: evenly mixing the metal particle catalyst deposited in the carbon nanotube with the quartz sand particles, the quartz sand particle size is 0.5-2mm, put into In the fixed-bed reactor, pass hydrogen gas at 50-150°C for pretreatment for 0.5-2h, then heat up to 150-250°C and keep a constant temperature; set the temperature of the container filled with benzene to 20-50°C, 1-10ml/min of hydrogen Through this vessel, benzene vapor is brought into the reactor, and the benzene hydrogenation reaction is carried out to generate cyclohexane.

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