Preparation method of eggshell type catalyst, obtained catalyst, used device and application of catalyst

Abstract

The invention discloses a preparation method of an eggshell type catalyst, the obtained catalyst, a used device and application of the catalyst. The preparation method comprises the following steps: (1) impregnating carrier particles in an organic solvent dissolved with furfural and aniline in an isopyknic manner to obtain a mixture; (2) carrying out heat treatment on the mixture, cooling to room temperature, washing with water, and carrying out vacuum drying to obtain a pretreated carrier; (3) putting the pretreated carrier into a carrier container, stirring and heating; (4) dissolving a soluble salt containing a metal active component to obtain a mixed solution; adding a ligand containing an N or P coordination element into the mixed solution to obtain a precursor solution, inputting the precursor solution into a carrier container for atomization treatment, then mixing the atomized precursor solution with gas to form micron-level liquid drops, and carrying out electrostatic adsorption on a soluble salt of a metal active component on the surface of the pretreated carrier to obtain the metal active carrier. And quickly drying to form the eggshell type catalyst with metal active components distributed on the surface layer of the carrier. The catalyst is good in dispersity, stable and wide in application.

Description

Technical Field

[0001] The invention relates to an eggshell-type catalyst and a preparation method, a preparation device and application thereof, and specifically belongs to the field of catalyst synthesis and application. Background Art

[0002] Catalytic reaction is the core and key step in the production process of most chemical products. Choosing a catalytic reaction system with the safest and most efficient operation is the key to whether a chemical company is economically successful or not, because the catalytic reaction system determines the energy consumption of the subsequent separation steps and the economic efficiency of the process. The catalyst is the core of controlling the catalytic reaction process, which determines whether the catalytic reaction process can improve efficiency, save energy and reduce waste. Catalysts are divided into homogeneous catalytic systems and heterogeneous catalytic systems. Homogeneous catalytic systems have many advantages such as high catalytic activity and high selectivity, but they are not easy to separate from products and solvents, which limits their expansion in industrial applications. Granular catalysts currently play an important role in industrial catalysis due to their easy separation from products and excellent catalytic performance. For granular catalysts, most of the catalytic reactions occur on the surface of the catalyst particles. In order to make the catalyst have more active sites to improve the efficiency of the catalytic reaction, the catalyst is required to have a larger specific surface area or to make the active sites highly dispersed in the shell of the catalyst. Eggshell catalysts are widely used in industrial catalytic systems and fine chemical system production due to the active components located on the surface of the particles.

[0003] The preparation of eggshell catalysts is generally to place spherical silica and alumina in a pelletizer, then sprinkle metal salt solution on the surface of spherical silica and alumina, and start the pelletizer to make the alumina roll inside the pelletizer, so that the liquid metal salt solution adheres to the surface of silica and alumina. The disadvantage of adopting such a method is that on the one hand, the liquid salt solution metal precursor / liquid organic metal precursor is unevenly adsorbed on the surface of silica and alumina, which easily causes the problem of low utilization rate of precious metals, which is not conducive to achieving the principle of low cost and high efficiency when the catalyst is used, and the particle size of the metal particles loaded on the carrier is uncontrollable, which limits the scope of use of the prepared catalyst. On the other hand, it limits the use of irregular granular catalyst carriers. Irregular granular carriers are difficult to achieve tumbling action in the pelletizer, resulting in the effect of the prepared catalyst not meeting expectations. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an eggshell-type catalyst with simple preparation process, low cost, high stability, high activity and high selectivity and a preparation method thereof, and to apply the catalyst to catalytic hydrogenation reaction.

[0005] In order to solve the above technical problems, the present invention first discloses a method for preparing an eggshell-type catalyst, which comprises:

[0006] (1) immersing an equal volume of a quantitative carrier particle in an organic solvent containing furfural and aniline at -20°C to 10°C, and standing at room temperature for 0.5 h to 10 h to obtain a mixture;

[0007] (2) placing the mixture obtained in step (1) in a reaction kettle, and heat treating it at 100° C. to 200° C. for 3 h to 10 h, cooling it to room temperature, washing it with water several times, and then drying it in a vacuum drying oven for 1 h to 24 h to obtain a pretreated carrier, thereby achieving the operation goal of "polymer pore blocking", wherein the pressure in the vacuum drying oven is 0.05 to 0.3 atmospheres, and the drying temperature is 30° C. to 100° C.;

[0008] (3) placing the pretreated carrier obtained in step (2) in a carrier container, stirring, and heating at 30° C. to 200° C.;

[0009] (4) A soluble salt of a quantitative amount of metal active components is dissolved in an ethanol-water solution or a methanol-water solution to obtain a mixed solution; a ligand containing a N or P coordination element is added to the mixed solution to obtain a precursor solution, the precursor solution is input into a carrier container and atomized, the droplets obtained after atomization are mixed with a gas input into the carrier container separately to form micron-sized droplets, the micron-sized droplets are transported to a position where a pretreated carrier is placed along with the flow of gas, the soluble salt of the metal active component therein is electrostatically adsorbed on the surface of the pretreated carrier, and after rapid drying, an eggshell-type catalyst with the metal active component distributed on the surface of the carrier is formed, thereby completing the "atomization adsorption" process.

[0010] Furthermore, in step (1), the carrier particles are one of silicon dioxide, aluminum oxide, activated carbon, molecular sieve or magnesium dioxide.

[0011] Furthermore, in step (1), the mass ratio of furfural to aniline is 1:1-4, and the total mass of furfural and aniline accounts for 0.5%-5.0% of the mass of the carrier particles.

[0012] Furthermore, the organic solvent for dissolving furfural and aniline in step (1) is one or more of methanol, ethanol, tetrahydrofuran or DMF (N,N-dimethylformamide), and the mass of the organic solvent used is 120% to 160% of the mass of the carrier particles used; the organic solvent can be selected specifically according to the type of carrier, wherein tetrahydrofuran or DMF is preferably selected as the activated carbon carrier, and methanol or ethanol is preferably selected as the silica, alumina, molecular sieve or magnesium dioxide carrier.

[0013] Furthermore, in step (4), the soluble salt of the metal active component is one or more of chloroplatinic acid, platinum nitrate, tetraammineplatinum dichloride, tetraammineplatinum nitrate, chloroauric acid, palladium nitrate, palladium chloride, chloropalladic acid, palladium acetate, sodium chloropalladate, potassium chloropalladate, ruthenium trichloride, ruthenium acetylacetonate, ruthenium nitrate, rhodium trichloride or rhodium acetylacetonate; the ligand containing N or P coordination elements is one or more of pyridine, ammonia water (the ammonia concentration in commercially available ammonia water is about 25%), bipyridine, triphenylphosphine, tetraphenylphosphine bromide, dicyandiamide or melamine; the ethanol aqueous solution is one or more of The mass ratio of the ethanol aqueous solution or methanol aqueous solution to the carrier particles used in step (1) is 1:1, and the mass concentration of ethanol or methanol in the ethanol aqueous solution or methanol aqueous solution is 40%; the mass of the N or P element in the ligand containing the N or P coordination element does not exceed 2% of the mass of the carrier particles in step (1); the ligand containing the N or P coordination element is selected according to the carrier type, wherein the activated carbon carrier is preferably pyridine, ammonia water, and tetraphenylphosphine bromide; the silicon dioxide, aluminum oxide, molecular sieve or magnesium dioxide carrier is preferably bipyridine, triphenylphosphine, dicyandiamide, and melamine.

[0014] Furthermore, in step (4), the precursor solution is input into the carrier container at a rate of 0.1 mL / min to 0.3 mL / min; the gas input into the carrier container is one or more of hydrogen, nitrogen, argon, helium or air, and the flow rate is 10 mL to 5 L / min.

[0015] The present invention also discloses an eggshell-type catalyst prepared according to the method as described above, wherein a metal active component is loaded on the surface of a carrier to form an eggshell structure, the metal active component is one or more of platinum, gold, palladium, ruthenium or rhodium, the carrier is one of silicon dioxide, aluminum oxide, activated carbon, molecular sieve or magnesium dioxide, and polymers are blocked in the pores of the carrier; the mass fraction of the metal active component is 0.01% to 3.0%, and the rest is the carrier with polymers blocked in the pores.

[0016] The present invention also discloses a device for preparing an eggshell-type catalyst according to the method described above, the device comprising a carrier container, a gas disperser is provided at the top inlet of the carrier container, the gas disperser is connected to a gas input pipeline with a gas compressor; a liquid input pipeline with an infusion pump extends from the top of the carrier container and an atomizer is provided at the bottom thereof, the atomizer is preferably an ultrasonic atomizer; a sieve plate is provided inside the carrier container, and sieve plate holes are distributed on the sieve plate; a stirrer is provided above the sieve plate, the stirrer is preferably a mechanical stirrer; an exhaust port is provided at the bottom of the carrier container. The carrier container has a three-section structure, the upper section is conical, the middle section is cylindrical, and the lower section is inverted conical. The sieve plate is located at the bottom of the middle section and the top of the lower section.

[0017] Furthermore, the diameter of the sieve plate holes ranges from 0.01 mm to 0.05 mm.

[0018] The present invention also discloses an eggshell-type catalyst prepared by the method as described above, which is used in a hydrogenation reaction after being reduced with hydrogen, methanol, hydrazine hydrate, sodium borohydride or potassium borohydride, and the applicable reactor is one of a fixed bed, a micro-packed bed and a trickle bed.

[0019] The present invention has the following advantages:

[0020] 1. Pretreatment of the carrier: Furfural and aniline complete polymerization inside the carrier pores, and the polymer pore blocking principle is used to block the internal pores of the carrier, that is, to block the core of the catalyst. The thickness of the catalyst shell can be controlled by the amount of polymer, which is suitable for the preparation of different types of catalysts and can be flexibly used in different reactions.

[0021] 2. The loading of metal active components adopts the method of "coordination adsorption": the metal active component precursor solution is atomized into micron-sized "droplets" by ultrasound, and the metal salt component is coordinated and protected by ligands containing N or P to avoid sintering and growth of the metal component during the preparation process; in addition, the N or P ligand has a certain electronic effect, which makes the entire "droplet" have a certain charge in the small droplets formed by atomization, so that it can be adsorbed on the surface of the shell carrier through electronic force, so that the metal active component has a high degree of dispersion and exhibits excellent catalytic performance in a variety of reactions. In addition, the strong interaction between the carrier and the active component precursor is used to suppress the active component of the eggshell catalyst from falling off during the reaction process.

[0022] 3. The device provided by the present invention is specifically prepared according to the characteristics of the catalyst. The droplet size of the precursor solution after atomization can be controlled by adjusting the liquid intake of the precursor solution and the gas flow rate input into the carrier container, thereby controlling the number of corresponding metal elements contained in a single atomized droplet, and further controlling the size of the prepared metal nanoparticles loaded on the carrier surface to have a diameter of 0.5nm to 3nm; the uniformity of dispersion of the metal nanoparticles on the carrier surface can be controlled by adjusting the gas flow input by the gas compressor; the introduction of mechanical stirring expands the use range of the particle-type carrier shape from single spherical particles to amorphous particles, which can significantly improve the use range of the eggshell-type catalytic carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the device for preparing eggshell-type solid particle catalyst according to the present invention;

[0024] Figure 2 is a cross-sectional view of the 1-Pt / Al2O3 eggshell catalyst of Example 1;

[0025] Figure 3 is a cross-sectional view of the 2-PtRu / Al2O3 eggshell catalyst of Example 2;

[0026] Figure 4 TEM image of the 6-Rh / Al2O3 eggshell catalyst of Example 6;

[0027] Figure 5 TEM image of the 3-Pt / C eggshell catalyst of Example 3;

[0028] Figure 6 It is the 2-PtRu / Al2O3 eggshell-type catalyst of Example 2.

[0029] Figure 1 Winning bid number: 1-infusion pump; 2-gas disperser; 3-atomizer; 4-carrier container; 5-agitator; 6-gas compressor; 7-sieve plate hole; 8-sieve plate; 9-exhaust port. DETAILED DESCRIPTION

[0030] The present invention is further explained below in conjunction with the examples. The following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] The device for preparing the eggshell catalyst of the present invention is as follows Figure 1 As shown, the device includes a carrier container 4, a gas disperser 2 is provided at the top inlet of the carrier container 4, and the gas disperser 2 is connected to a gas input pipeline with a gas compressor 6; a liquid input pipeline with an infusion pump 1 extends from the top of the carrier container 4 and an atomizer 3 is provided at the bottom thereof, and the atomizer is an ultrasonic atomizer; a sieve plate 8 is provided inside the carrier container 4, and sieve plate holes 7 are distributed on the sieve plate 8; a stirrer 5 is provided above the sieve plate 8, and the stirrer 5 is a mechanical stirrer; an exhaust port 9 is provided at the bottom of the carrier container 4, and the exhaust port 9 is used to discharge the gas introduced. The carrier container 4 has a three-section structure, the upper section is conical, the middle section is cylindrical, and the lower section is inverted conical. The sieve plate 8 is located at the bottom of the middle section and the top of the lower section.

[0032] Example 1

[0033] At 0°C, 5 g of Al2O3 particles were immersed in an equal volume of a methanol solvent containing 0.05 g of furfural and 0.05 g of aniline, with a methanol mass of 7 g. The mixture was allowed to stand at room temperature for 5 hours to obtain a mixture.

[0034] Subsequently, the mixture was transferred to a solvent thermal reactor with a volume of 50 mL under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and then placed in a vacuum drying oven for drying at 65°C for 24 h. The pressure in the vacuum drying oven was 0.1 atmospheres to obtain a pretreated carrier.

[0035] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator 5 is turned on first to make the pretreated carrier particles move on the sieve plate 8, and the heating temperature is set to 80°C.

[0036] Take 0.172g of platinum nitrate and dissolve it in 5g of ethanol aqueous solution to obtain a mixed solution after dissolution, and then take 0.07g of bipyridine and add it to the above mixed solution to obtain a precursor solution of platinum nitrate. The precursor solution of platinum nitrate is pumped into the atomizer 3 at a flow rate of 0.2mL / min through the infusion pump 1, and atomized droplets are formed under the action of the atomizer 3. At the same time, the gas flow meter is turned on to adjust the flow rate to 200mL / min, and the nitrogen from the gas compressor 6 enters the carrier container 4 and mixes with the atomized droplets to form micron-level droplets. Driven by nitrogen, it reaches the pretreated carrier on the sieve plate 8. Through the electrostatic force between the soluble salt of the metal active component in the droplet and the pretreated carrier, the metal salt precursor solution is uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried with the help of the heating function at the sieve plate 8. Catalyst 1-Pt / Al2O3 is obtained, and the theoretical loading of metal platinum is 2wt%. The cross-sectional diagram of the catalyst is as follows Figure 2 As shown, it can be clearly seen that the catalyst exhibits an obvious eggshell structure at the microscopic scale.

[0037] Weigh 2.5 g of the above 1-Pt / Al2O3 catalyst and load it into a micro-packed bed reactor.

[0038] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 200 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 1 mL / min. After the reaction was completed, the conversion rate was 100% and the selectivity was 99.8%.

[0039] Example 2

[0040] At 0°C, 5 g of Al2O3 particles were immersed in an equal volume of a methanol solvent containing 0.1 g of furfural and 0.1 g of aniline, with a methanol mass of 7 g. The mixture was allowed to stand at room temperature for 5 hours to obtain a mixture.

[0041] Subsequently, the mixture was transferred to a 50 mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and then placed in a vacuum drying oven at 65°C for 24 h. The pressure in the vacuum drying oven was 0.1 atmospheres to obtain a pretreated carrier.

[0042] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator 5 is turned on first to make the carrier particles move on the sieve plate 8, and the heating temperature is set to 80°C.

[0043] Take 0.086g of platinum nitrate and 0.135g of ruthenium trichloride and dissolve them in 5g of ethanol aqueous solution to obtain a mixed solution. Then take 0.07g of bipyridine and 0.07g of dicyandiamide and add them to the above mixed solution to obtain a precursor solution of platinum ruthenium mixed. Infusion pump 1 pumps platinum nitrate and ruthenium trichloride precursor solution into atomizer 3 at a flow rate of 0.2mL / min to form atomized droplets. At the same time, turn on the gas flowmeter to adjust the flow rate to 200mL / min, and the air from the gas compressor 6 enters the carrier container 4, mixes with the atomized droplets, and obtains micron-level droplets, and drives the droplets to the pretreated carrier on the sieve plate 8. Through the electrostatic force between the soluble salt of the metal active component in the droplet and the carrier, the metal salt precursor solution is uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried with the help of the heating function at the sieve plate 8. The catalyst 2-PtRu / Al2O3 was obtained, the theoretical loading amount of metal platinum was 1wt%, and the theoretical loading amount of metal ruthenium was 1wt%. The cross-sectional view of the catalyst is shown in FIG. Figure 3 As shown, it can be clearly seen that the catalyst presents an obvious eggshell structure at the microscopic scale; in the TEM transmission electron microscope image of the catalyst, the Pt and Ru nanoparticles are highly dispersed.

[0044] Weigh 2.5 g of the above 2-PtRu / Al2O3 catalyst and load it into a micro-packed bed reactor.

[0045] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 200 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 1 mL / min. After the reaction was completed, the conversion rate was 100% and the selectivity was 99.7%.

[0046] Example 3

[0047] At 0°C, 5 g of activated carbon (C) particles were immersed in an equal volume of tetrahydrofuran solvent containing 0.05 g of furfural and 0.1 g of aniline, with the mass of tetrahydrofuran being 7.5 g. The mixture was allowed to stand at room temperature for 5 hours to obtain a mixture.

[0048] Then, the mixture was transferred to a 50 mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and dried in a vacuum drying oven at 65°C for 24 h to obtain the pretreated carrier. The pressure in the vacuum drying oven was 0.1 atmosphere.

[0049] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator 5 is turned on first to make the carrier particles move on the sieve plate 8, and the heating temperature is set to 80°C.

[0050] Take 0.172g of platinum nitrate and dissolve it in 5g of ethanol aqueous solution to obtain a mixed solution after dissolution. Then take 0.05g of pyridine and 0.05g of tetraphenylphosphine bromide and add them to the above mixed solution to obtain a platinum nitrate precursor solution. The infusion pump 1 pumps the platinum nitrate precursor solution into the atomizer 3 at a flow rate of 0.2mL / min to form atomized droplets. At the same time, turn on the gas flowmeter to adjust the flow rate to 200mL / min, and the hydrogen from the gas compressor 6 enters the carrier container 4, mixes with the atomized droplets to obtain micron-level droplets, and drives the droplets into the pretreated carrier located on the sieve plate 8. Through the electrostatic force between the soluble salt of the metal active component in the droplet and the carrier, the metal salt precursor solution is uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried with the help of the heating function at the sieve plate 8. The catalyst 3-Pt / C is obtained, and the theoretical loading of metal platinum is 2wt%. The TEM electron microscope image of the catalyst is as follows Figure 5 As shown, the Pt nanoparticles are highly dispersed.

[0051] Weigh 2.5 g of the above 3-Pt / C catalyst and load it into a micro-packed bed reactor.

[0052] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 200 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 1 mL / min. After the reaction was completed, the conversion rate was 100% and the selectivity was 99.9%.

[0053] Example 4

[0054] At 0°C, 5 g of SiO2 particles of equal volume are immersed in a methanol solvent containing 0.05 g of furfural and 0.1 g of aniline, with the mass of methanol being 6.7 g. The mixture is allowed to stand at room temperature for 5 hours to obtain a mixture.

[0055] Then, the mixture was transferred to a 50 mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and dried in a vacuum drying oven at 65°C for 24 h to obtain the pretreated carrier. The pressure in the vacuum drying oven was 0.1 atmosphere.

[0056] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator 5 is turned on first to make the carrier particles move on the sieve plate 8, and the heating temperature is set to 80°C.

[0057] Take 0.27g of ruthenium trichloride and dissolve it in 5g of ethanol aqueous solution to obtain a mixed solution after dissolution, and then take 0.05g of bipyridine and add it to the above mixed solution to obtain a ruthenium trichloride precursor solution. The infusion pump 1 pumps the ruthenium trichloride precursor solution into the atomizer 3 at a flow rate of 0.2mL / min to obtain atomized droplets. At the same time, turn on the gas flowmeter to adjust the flow rate to 200mL / min, and allow nitrogen to enter the carrier container 4 through the gas compressor 6, mix with the atomized droplets to form micron-level droplets, and drive the droplets to the pretreated carrier located on the sieve plate 8. Through the electrostatic force between the soluble salt of the metal active component in the droplet and the carrier, the metal salt precursor solution is uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried with the help of the heating function at the sieve plate 8. The catalyst 4-Ru / SiO2 is obtained, and the theoretical loading of metal ruthenium is 2wt%. The TEM transmission electron microscope image of the catalyst is as follows Figure 4 As shown, the Ru nanoparticles are highly dispersed.

[0058] Weigh 2.5 g of the above 4-Ru / SiO2 catalyst and load it into a micro-packed bed reactor.

[0059] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 200 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 0.5 mL / min. After the reaction was completed, the conversion rate was 100% and the selectivity was 99.3%.

[0060] Example 5

[0061] At 0°C, 5 g of SiO2 particles of equal volume are immersed in a methanol solvent containing 0.1 g of furfural and 0.1 g of aniline, with the mass of methanol being 6.7 g. The mixture is allowed to stand at room temperature for 5 hours to obtain a mixture.

[0062] Then, the mixture was transferred to a 50 mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and dried in a vacuum drying oven at 65°C for 24 h to obtain the pretreated carrier. The pressure in the vacuum drying oven was 0.1 atmosphere.

[0063] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator 5 is turned on first to make the carrier particles move on the sieve plate 8, and the heating temperature is set to 80°C.

[0064] Take 0.248g palladium nitrate and dissolve it in 5g ethanol aqueous solution, and obtain a mixed solution after dissolving. Take 0.05g bipyridine again and add it to the above-mentioned mixed solution to obtain palladium nitrate precursor solution. Infusion pump 1 pumps palladium nitrate precursor solution into atomizer 3 at a flow rate of 0.2mL / min to obtain atomized droplets. Turn on the gas flow meter to adjust the flow rate to 200mL / min at the same time, and the air from the gas compressor 6 enters the carrier container 4, and is mixed with the atomized droplets to obtain micron-level droplets, and drives the droplets to arrive at the pretreated carrier on the sieve plate 8, and the electrostatic force between the soluble salt of the active metal component in the droplet and the carrier makes the metal salt precursor solution uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried by the heating function at the sieve plate 8. Obtain catalyst 5-Pd / SiO2, the theoretical loading of metal palladium is 2wt%.

[0065] Weigh 2.5 g of the above 5-Pd / SiO2 catalyst and load it into a micro-packed bed reactor.

[0066] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 100 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 1.0 mL / min. After the reaction was completed, the conversion rate was 100% and the selectivity was 99.9%.

[0067] Example 6

[0068] At 0°C, 5 g of Al2O3 particles were immersed in an equal volume of tetrahydrofuran solvent containing 0.05 g of furfural and 0.1 g of aniline, with a mass of 7 g of tetrahydrofuran. The mixture was allowed to stand at room temperature for 5 hours to obtain a mixture.

[0069] Then, the mixture was transferred to a 50 mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10 h; cooled to room temperature, washed with water three times, and then placed in a vacuum drying oven at 65°C for 24 h to obtain the pretreated carrier. The pressure in the vacuum drying oven was 0.1 atmosphere.

[0070] The pretreated carrier is placed on the sieve plate 8 inside the carrier container 4, the agitator is turned on first to make the carrier particles move on the sieve plate 8, and the heating temperature is set to 70°C.

[0071] Take 0.389g of rhodium acetylacetonate and dissolve it in 5g of water and ethanol mixed solution. After dissolving, take 0.07g of bipyridine and 0.07g of triphenylphosphine and add them to the above solution to obtain rhodium acetylacetonate precursor solution. Infusion pump 1 pumps the rhodium precursor solution into atomizer 3 at a flow rate of 0.2mL / min to obtain atomized droplets. At the same time, turn on the gas flow meter to adjust the nitrogen flow rate to 200mL / min, and the air from the gas compressor 6 enters the carrier container 4, mixes with the atomized droplets to obtain micron-level droplets, and drives the droplets to the pretreated carrier located on the sieve plate 8. Through the electrostatic force between the soluble salt of the active metal component in the droplet and the carrier, the metal salt precursor solution is uniformly adsorbed on the surface of the carrier shell layer, and then the catalyst is dried by the heating function at the sieve plate 8. Catalyst 6-Rh / Al2O3 is obtained, and the theoretical loading of metal rhodium is 2wt%.

[0072] Weigh 2.5g of the above 6-Rh / Al2O3 catalyst and load it into a micro-packed bed reactor. Before use, the catalyst is activated by hydrogenation treatment. The activation conditions are: temperature T = 300°C; pressure P is 1.0MPa, gas flow rate is 100mL / min, and reduction time is 2 hours. When the temperature in the reactor naturally drops to 80°C, increase the pressure to 1.0MPa and wait for the system to stabilize. A mixed solution of benzonitrile, ammonia methanol and methanol with a mass concentration of 10% benzonitrile is pumped into the reactor through a high-pressure pump, and the liquid flow rate is adjusted to 1.0mL / min. After the reaction is completed, the conversion rate is 100% and the selectivity is 99.2%.

[0073] Comparative Example 1

[0074] 0.172g of platinum nitrate was dissolved in 7.5mL of water at 0°C, and then the metal precursor was loaded onto 5g of activated carbon by equal volume impregnation. After standing at room temperature for 12h, the catalyst was placed in an oven at 80°C for 12h to obtain catalyst 7-Pt / Al2O3, and the theoretical loading amount of metal platinum was 2wt%.

[0075] Weigh 2.5 g of the above 7-Pt / C catalyst and load it into a micro-packed bed reactor.

[0076] The catalyst was activated by hydrogenation before use, and the activation conditions were: temperature T = 300 ° C; pressure P was 1.0 MPa, gas flow rate was 100 mL / min, and activation time was 2 hours. When the temperature in the reactor naturally dropped to 80 ° C, the pressure was increased to 1.0 MPa, and the system was waited for stability. A nitrobenzene-methanol mixed solution with a nitrobenzene mass concentration of 10% was pumped into the reactor through a high-pressure pump, and the liquid flow rate was adjusted to 1.0 mL / min. After the reaction was completed, the conversion rate was 66.1% and the selectivity was 92.2%.

[0077] Comparative Example 2

[0078] At 0°C, 5g of alumina particles were immersed in a tetrahydrofuran solvent containing 0.1g of furfural and 0.1g of aniline, with a mass of 7g of tetrahydrofuran, and allowed to stand at room temperature for 5h; then the mixture was transferred to a 50mL solvent thermal reactor under nitrogen protection and treated at 180°C for 10h; cooled to room temperature, washed with water 3 times, and then placed in a vacuum drying oven at 65°C for 24h, with a pressure of 0.1 atmosphere; the prepared carrier was placed in a petri dish of suitable size; 0.172g of platinum nitrate and 0.5g of bipyridine were dissolved in 7mL of water, and then the metal precursor was loaded on the alumina by equal volume impregnation, and the catalyst was placed in an oven at 80°C for 12h after standing for 12h. The catalyst 8-Pt / Al2O3 was obtained, and the theoretical loading amount of metal platinum was 2wt%.

[0079] Weigh 2.5g of the above 8-Pt / Al2O3 catalyst and load it into a micro-packed bed reactor. Before use, the catalyst is activated by hydrogenation treatment. The activation conditions are: temperature T = 300°C; pressure P is 1.0MPa, gas flow rate is 100mL / min, and activation time is 2 hours. When the temperature in the reactor naturally drops to 80°C, increase the pressure to 1.0MPa and wait for the system to stabilize. A nitrobenzyl alcohol mixed solution with a nitrobenzene mass concentration of 10% is pumped into the reactor through a high-pressure pump, and the liquid flow rate is adjusted to 1.0mL / min. After the reaction is completed, the conversion rate is 85.5% and the selectivity is 97.3%.

[0080] Comparative Example 3

[0081] 0.389 g of rhodium acetylacetonate was dissolved in 7 g of water at 0°C, and then the metal precursor was loaded onto 5 g of alumina by equal volume impregnation. After standing at room temperature for 12 h, the catalyst was placed in an oven at 80°C for 12 h. The catalyst 8-Rh / Al2O3 was obtained, and the theoretical loading amount of metal rhodium was 2 wt%.

[0082] Weigh 2.5g of the above 8-Rh / Al2O3 catalyst and load it into a micro-packed bed reactor. Before use, the catalyst is activated by hydrogenation treatment. The activation conditions are: temperature T = 300°C; pressure P is 1.0MPa, gas flow rate is 100mL / min, and activation time is 2 hours. When the temperature in the reactor naturally drops to 80°C, increase the pressure to 1.0MPa and wait for the system to stabilize. A mixed solution of benzonitrile, ammonia methanol and methanol with a mass concentration of 10% benzonitrile is pumped into the reactor through a high-pressure pump, and the liquid flow rate is adjusted to 1.0mL / min. After the reaction is completed, the conversion rate is 73.7% and the selectivity is 95.1%.

[0083] Table 1. Comparison of nitrobenzene hydrogenation activity between examples and comparative examples

[0084]

[0085] It can be seen from Table 1 that the activity and selectivity of the catalyst prepared by the present invention are superior to those of the catalyst prepared by the traditional impregnation method.

[0086] Table 2. Comparison of benzonitrile hydrogenation activity between examples and comparative examples

[0087]

[0088] It can be seen from Table 2 that the activity and selectivity of the catalyst prepared by the present invention are better than those of the catalyst prepared by the traditional impregnation method.

Claims

1. A method for preparing an eggshell-type catalyst, characterized in that: The preparation method comprises: (1) immersing an equal volume of a quantitative carrier particle in an organic solvent containing furfural and aniline at -20°C to 10°C, and standing at room temperature for 0.5 h to 10 h to obtain a mixture; (2) placing the mixture obtained in step (1) in a reaction kettle, and heat treating it at 100° C. to 200° C. for 3 h to 10 h, cooling it to room temperature, washing it with water several times, and then drying it in a vacuum drying oven for 1 h to 24 h to obtain a pretreated carrier, wherein the pressure in the vacuum drying oven is 0.05 to 0.3 atmospheres, and the drying temperature is 30° C. to 100° C.; (3) placing the pretreated carrier obtained in step (2) in a carrier container, stirring, and heating at 30° C. to 200° C.; (4) dissolving a quantitative amount of a soluble salt of a metal active component in an ethanol aqueous solution or a methanol aqueous solution to obtain a mixed solution; adding a ligand containing a N or P coordination element to the mixed solution to obtain a precursor solution, inputting the precursor solution into a carrier container and atomizing the precursor solution, wherein the droplets obtained after atomization are mixed with the gas input into the carrier container to form micron-sized droplets, wherein the soluble salt of the metal active component in the micron-sized droplets is electrostatically adsorbed on the surface of the pretreated carrier, and then rapidly dried to form an eggshell-type catalyst in which the metal active component is distributed on the surface of the carrier.

2. The method for preparing the eggshell-type catalyst according to claim 1, characterized in that: In step (1), the carrier particles are one of silicon dioxide, aluminum oxide, activated carbon, molecular sieve or magnesium dioxide.

3. The method for preparing the eggshell-type catalyst according to claim 1, characterized in that: In step (1), the mass ratio of furfural to aniline is 1:1-4, and the total mass of furfural and aniline accounts for 0.5%-5.0% of the mass of the carrier particles.

4. The method for preparing the eggshell-type catalyst according to claim 1, characterized in that: The organic solvent for dissolving furfural and aniline in step (1) is one or more of methanol, ethanol, tetrahydrofuran or DMF, and the mass of the organic solvent used is 120% to 160% of the mass of the carrier particles used.

5. The method for preparing the eggshell-type catalyst according to claim 1, characterized in that: In step (4), the soluble salt of the metal active component is one or more of chloroplatinic acid, platinum nitrate, tetraamine platinum dichloride, tetraamine platinum nitrate, chloroauric acid, palladium nitrate, palladium chloride, chloropalladic acid, palladium acetate, sodium chloropalladate, potassium chloropalladate, ruthenium trichloride, ruthenium acetylacetonate, ruthenium nitrate, rhodium trichloride or rhodium acetylacetonate; the ligand containing N or P coordination elements is one or more of pyridine, ammonia water, bipyridine, triphenylphosphine, tetraphenylphosphine bromide, dicyandiamide or melamine; the mass ratio of ethanol aqueous solution or methanol aqueous solution to the carrier particles used in step (1) is 1:1; the mass of N or P element in the ligand containing N or P coordination elements does not exceed 2% of the mass of the carrier particles in step (1).

6. The method for preparing the eggshell-type catalyst according to claim 1, characterized in that: In step (4), the precursor solution is input into the carrier container at a rate of 0.1 mL / min to 0.3 mL / min; the gas input into the carrier container is one or more of hydrogen, nitrogen, argon, helium or air, and the flow rate is 10 mL to 5 L / min.

7. An eggshell-type catalyst prepared by the method according to any one of claims 1 to 6, characterized in that: The metal active component is loaded on the surface of an eggshell-shaped carrier, wherein the metal active component is one or more of platinum, gold, palladium, ruthenium or rhodium, and the carrier is one of silicon dioxide, aluminum oxide, activated carbon, molecular sieve or magnesium dioxide, and polymers are blocked in the pores of the carrier; the mass fraction of the metal active component is 0.01% to 3.0%, and the rest is the carrier with polymers blocked in the pores.

8. A device for preparing an eggshell catalyst according to any one of claims 1 to 6, characterized in that: The device comprises a carrier container (4), a gas disperser (2) is arranged at the top inlet of the carrier container (4), and the gas disperser (2) is connected to a gas input pipeline with a gas compressor (6); a liquid input pipeline with an infusion pump (1) extends from the top of the carrier container (4) and an atomizer (3) is arranged at the bottom; a sieve plate (8) is arranged inside the carrier container (4), and sieve plate holes (7) are distributed on the sieve plate (8); a stirrer (5) is arranged above the sieve plate (8); and an exhaust port (9) is arranged at the bottom of the carrier container (4).

9. The device according to claim 8, characterized in that: The diameter of the sieve plate holes (7) ranges from 0.01 mm to 0.05 mm.

10. An eggshell catalyst prepared by the method according to any one of claims 1 to 6, which is used in a hydrogenation reaction after being reduced with hydrogen, methanol, hydrazine hydrate, sodium borohydride or potassium borohydride, and the applicable reactor is one of a fixed bed, a micro-packed bed and a trickle bed.

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