Method for the production of a nitrogen-doped hierarchical porous carbon supported nano-Pd catalyst and its products and uses

Abstract

A method for producing a nano-Pd catalyst supported on a nitrogen-doped hierarchical porous carbon, characterized in that it comprises: 1) Preparation of a nitrogen-doped hierarchical porous carbon, 2) Mixing the nitrogen-doped hierarchical porous carbon produced in step 1) with water and adjusting the pH of the mixed solution to alkaline. 3) Mixing the mixture solution prepared in step 2) with the aqueous solution of Pd metal precursors, adding reducing agent and obtaining the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon after reduction.

Description

TECHNICAL AREA

[0001] The present invention relates to the technical field of catalysts, in particular a process for producing a nano-Pd catalyst supported on a nitrogen-doped hierarchical porous carbon and its products and uses. BACKGROUND TECHNOLOGY

[0002] The selective hydrogenation reaction of unsaturated ketones is a key reaction in the production of fine chemicals such as vitamins, perfumes, and fragrances. The yield and cost of this reaction step determine the economic viability of new synthetic routes for vitamin E. The catalysts currently used in industrial production for the selective hydrogenation of carbon-carbon double bonds in unsaturated ketones are primarily supported palladium (Pd) catalysts, such as the commonly used palladium (Pd) / activated carbon (AC) catalysts. However, conventional Pd / AC catalysts suffer from numerous problems, including low activity, significant loss of active components, insufficient selectivity, and excessive hydrogen content. Therefore, the development of a more effective and stable catalyst for the selective hydrogenation of carbon-carbon double bonds is urgently needed.

[0003] Carbon material has a large specific surface area and is easy to control, making it an ideal catalyst support. However, the conventional activated carbon surface is inert and has weak interactions with the supported metal, readily leading to agglomeration and loss of the active metal. To improve the performance of the carbon material, Chinese patent publication CN 102513099A discloses a novel mesoporous carbon-supported metal catalyst consisting of metal particles and a mesoporous carbon support, where the carbon support is composed of a heteroatom-doped mesoporous carbon material.The technical solution modifies the local electronic structure of the carbon material through nitrogen doping, thereby promoting the dispersion of the precious metal nanoparticles and improving the activity, stability, and other properties of the catalyst through interaction between the nitrogen and the metal. However, the precious metal catalyst supported on nitrogen-doped carbon, produced using the conventional precious metal loading method, does not solve the problems of insufficient selectivity and an excess of hydrogen in the selective hydrogenation reaction of the carbon-carbon double bonds of unsaturated ketones.The reason is that the metal nanoparticles produced using the conventional method for loading the precious metal are spherical and have too many exposed edge and corner positions, which promotes the adsorption and hydrogenation of the polar carbon-oxygen double bonds in the unsaturated ketone and thus worsens the selectivity.

[0004] Therefore, a difficult task in the production of such catalysts is how to simply and controllably distribute the Pd nanoparticles evenly on the nitrogen-doped carbon with the fewest atoms at edges and corners, so that the selectivity of the catalyst is further increased.

[0005] Further methods for the production of catalysts comprising Pd nanoparticles on nitrogen-doped carbon supports are shown in CN 108 273 538 A and CN 106 975 505 B. INVENTIONAL CONTENT

[0006] In contrast to the problems described above in the prior art, the present invention discloses a method for producing a nano-Pd catalyst supported on a nitrogen-doped hierarchical porous carbon, wherein the surface and the hierarchical pore channels of the nitrogen-doped hierarchical porous carbon are loaded with metal-Pd nanoparticles having a regular polyhedral shape and a particle size of about 2-14 nm, the proportion of atoms of the metal-Pd nanoparticles with the specific morphology and particle size is lower at the edges and corners, and the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon exhibits excellent catalytic performance and, in particular, very high conversion rate, selectivity, and cycle stability in the selective hydrogenation reaction of unsaturated ketones.

[0007] The specific technical solutions are as follows: Method for the production of a nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst, comprising: 1) Preparation of a nitrogen-doped hierarchical porous carbon, 2) Mixing the nitrogen-doped hierarchical porous carbon produced in step 1) with water and adjusting the pH of the mixed solution to alkaline. 3) Mixing the solution prepared in step 2) with the aqueous solution of Pd metal precursor, adding reducing agent and obtaining the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon after reduction

[0008] In the present invention, nitrogen-doped hierarchical porous carbon is used as a support. Before the Pd metal precursor is added, the pH of the solution consisting of the nitrogen-doped hierarchical porous carbon and water is adjusted to alkaline. This allows the Pd metal precursor to initially react with alkaline conditions to form Pd hydroxide, enabling the regular formation of nuclei in the solution. Pd hydroxide nanoparticles with a regular shape and uniform size are then formed. These nanoparticles are supported within the hierarchical porous channels of the nitrogen-doped hierarchical porous carbon and bound by the nitrogen species contained therein. The size and morphology of the Pd hydroxide nanoparticles can be controlled by adjusting the type and concentration of the Pd metal precursor and the pH of the compound solution in step 2).Finally, it is converted into Pd metal nanoparticles by reduction with a reducing agent, whereby the type and concentration of the reducing agent can also influence the particle size of the Pd metal nanoparticles obtained by the conversion.

[0009] Nitrogen-doped hierarchical porous carbon is chosen as the support material so that the Pd hydroxide nanoparticles formed in the solution can distribute themselves uniformly within the pore channels of the hierarchical porous carbon through interaction with the nitrogen species. Furthermore, the Pd metal nanoparticles formed by the reduction of the Pd hydroxide nanoparticles can also be stabilized by nitrogen species, making them less prone to agglomeration and loss, thus ensuring the stability of the synthesized catalyst during use. Additionally, due to the relatively large particle size of the Pd nanoparticles, the use of nitrogen-doped hierarchical porous carbon can also prevent the Pd metal nanoparticles from blocking the pore channels and enhance the mass transfer effect.

[0010] In the reduction process, the conformal effect of Pd hydroxide nanoparticles is effectively utilized using a low-temperature liquid-phase reduction method. This avoids the damage to the morphology of the Pd hydroxide nanoparticles caused by high-temperature hydrogen reduction, thereby minimizing the number of edge and corner positions on the surface of the Pd metal nanoparticles. This conformal effect imparts excellent hydrogenation selectivity to the resulting catalyst.

[0011] Comparative studies have shown that, following the conventional impregnation process—namely, first mixing the support with the Pd metal precursor, adjusting the solution to alkaline, and finally adding the reducing agent—the metal Pd nanoparticles in the resulting supported catalyst are spherical or ellipsoidal. Furthermore, it has been found that the conversion rate and selectivity of the catalyst produced by the conventional process in the selective hydrogenation reaction of unsaturated ketones are much lower than those of the catalyst produced according to the present invention. In step 1)

[0012] The process for producing nitrogen-doped hierarchical porous carbon refers to the process in CN 106179440 A.

[0013] The resulting nitrogen-doped hierarchical porous carbon exhibits a hierarchical pore channel structure, and the nitrogen species it contains can serve to stabilize the metal-Pd nanoparticles. The mass fraction of nitrogen in the nitrogen-doped hierarchical porous carbon is 0.5–15%. In step 2):

[0014] The nitrogen-doped hierarchical porous carbon is insoluble in water, and the resulting solution forms a suspension upon mixing with water. Preferably, the mass-volume ratio of the nitrogen-doped hierarchical porous carbon to water is 1:20–200 g / ml.

[0015] In step 2), the pH of the mixed solution is adjusted to alkaline, preferably to 8-12, thereby regulating the particle size and morphology of the Pd hydroxide nanoparticles under the condition of Pd hydroxide formation, and ensuring that the shape and size of the Pd metal nanoparticles are conformable to the subsequent reduction steps. In step 3):

[0016] The Pd metal precursor is selected from soluble salts of Pd metal, specifically at least one of PdCl2, H2PdCl4, Pd(NO3)2, Pd(NH3)4(NO3)2.

[0017] In the present invention, the size and morphology of the Pd hydroxide nanoparticles serving as intermediates can be adjusted by controlling the type of Pd metal precursor, the concentration of the aqueous solution of Pd metal precursor, and the pH of the mixed solution. Preferably, the concentration of the aqueous solution of Pd metal precursor is 1-50 mg / ml, and the mass ratio of the nitrogen-doped hierarchical porous carbon to the Pd metal precursor is 3-600:1.

[0018] The particle size of the Pd hydroxide nanoparticles produced with the above-mentioned process parameters is 3-15nm, preferably 4-10nm.

[0019] The mixture of the combined solution and the aqueous solution of Pd metal precursor is mixed while stirring continuously. In step 3).

[0020] The reducing agent is at least one selected from hydrazine hydrate, formic acid, sodium borohydride and sodium formate.

[0021] The mass ratio of the reducing agent to the Pd metal precursor is 1-20:1.

[0022] The reducing agent is added as an aqueous solution and stirred continuously for 0.1–10 hours during the dropwise addition of the reducing agent. Preferably, the mass-volume ratio of the reducing agent to water is 1–20 mg / ml.

[0023] The reduction temperature is 0-80°C, the time is 1-360 minutes, and the preferred temperature is 0-30°C.

[0024] By changing the type and concentration of the reducing agent, the particle size of the Pd metal nanoparticles obtained after reduction can be adjusted.

[0025] The reduced product should also be filtered to obtain the nanoparticle catalyst supported on the nitrogen-doped hierarchical porous carbon.

[0026] Additionally, the nano-Pd catalyst obtained after filtration, supported on nitrogen-doped hierarchical carbon, should contain a certain amount of water to prevent spontaneous combustion of the catalyst in air. Preferably, the water content of the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon is 5-75 wt%.

[0027] The present invention also discloses a nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst produced according to the above-mentioned method, comprising a nitrogen-doped porous carbon material support with hierarchical pore channels and Pd metal nanoparticles supported on the support and in the hierarchical pore channels of the support;

[0028] The Pd-metal nanoparticles have a particle size of 2-14 nm, are regularly polyhedral, and are stabilized by nitrogen species on the surface of the nitrogen-doped porous carbon material. Preferably, the particle size of the Pd-metal nanoparticles is 4-10 nm.

[0029] The mass fraction of the Pd metal nanoparticles is 0.1-10% based on the total mass of the dehydrated dried catalyst.

[0030] The composition and morphology of the nitrogen-doped hierarchical porous carbon-supported nanoparticle catalyst are directly dependent on its manufacturing process conditions.

[0031] Furthermore, it is preferred that the manufacturing process for the nano-Pd catalyst supported on nitrogen-doped hierarchical carbon involves

[0032] in step 2): the pH value of the mixed solution is adjusted to 9-10,

[0033] in step 3): the Pd metal precursor is selected from PdCl2, Pd(NO3)2 or Pd(NH3)4(NO3)2, the concentration of the aqueous solution of Pd metal precursor is 5-20 mg / ml and the mass ratio of the nitrogen-doped hierarchical porous carbon to the Pd metal precursor is 50-200:1, the reducing agent is selected from an aqueous solution of hydrazine hydrate, formic acid or sodium borohydride with a concentration of 10-20mg / ml and the mass ratio of the reducing agent to the Pd metal precursor is 2-6:1.

[0034] It is even preferred that that the concentration of the aqueous solution of Pd metal precursor is 10mg / ml, the mass ratio of the nitrogen-doped hierarchical porous carbon to the Pd metal precursor is 100:1, the concentration of the reducing agent is 10-20mg / ml, and the mass ratio of the reducing agent to the Pd metal precursor is 2-4:1.

[0035] In the nitrogen-doped hierarchical porous carbon supported nano-Pd catalyst, produced under the above optimized process conditions, the Pd metal nanoparticles have a regular polyhedral shape and an average particle size of 4-8 nm, and the particle size is in accordance with the normal distribution.

[0036] It is even more preferred that the pH of the mixed solution is 10, and that the Pd metal precursor is selected from PdCl₂. In the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon, which is prepared under the further preferred conditions, the Pd metal nanoparticles have an average particle size of 8 nm, and the proportion of Pd metal nanoparticles with a particle size of less than 4 nm is very low to achieve better selectivity.

[0037] The present invention also discloses the use of the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon in the catalytic hydrogenation reaction, in particular in the selective hydrogenation reaction of unsaturated ketones.

[0038] In the above applications, the nano-Pd catalyst supported on nitrogen-doped hierarchical carbon is universally applicable. According to tests, the catalyst shows excellent catalytic performance when the following unsaturated ketone is used as a substrate, where the unsaturated ketone is specific for 6-methyl-5-hepten-2-one, 6-methyl-3,5-heptadien-2-one, 6,10-dimethyl-5-ene-2-undecanone, 6,10-dimethyl-5,9-diene-2-undecanone, 6,10-dimethyl-3,5-diene-2-undecanone, 6,10,14-trimethyl-5-ene-2-pentadecanone, 6,10,14-trimethyl-5,9,13-triene-2-pentadecanone, 6,10,14-trimethyl-3,5-diene-2-pentadecanone, cis 3,7-dimethyl-2,6-diene octanal, trans 3,7-Dimethyl-2,6-diene octanal.

[0039] Compared to the prior art, the present invention has the following advantages: The present invention discloses a manufacturing process for a nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon, wherein the nitrogen-doped hierarchical porous carbon is assumed to be the support and the catalyst is produced by the process steps of first adjusting the pH of a mixed solution of the nitrogen-doped hierarchical porous carbon and water and adding a Pd metal precursor, and by a low-temperature liquid-phase reduction process, wherein the Pd metal nanoparticles have a regular polyhedral shape.

[0040] In the manufacturing process of the present invention, the average particle size of the Pd metal nanoparticles in the produced catalyst is adjusted by adjusting the pH of the compound mixture in step 2), the type and concentration of the Pd metal precursor, and the type and concentration of the reducing agent in step 3). Furthermore, the catalyst produced by adjusting the appropriate pH of the compound mixture, the type and concentration of the Pd metal precursor, and the type and concentration of the reducing agent exhibits a very high conversion rate, selectivity, and cyclic stability in the selective hydrogenation reaction of unsaturated ketones. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows an X-ray diffraction pattern of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst produced in Example 1. Fig. Figure 2 shows a scanning electron microscope image of the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon produced in Example 1. Fig. Figure 3 shows a transmission electron micrograph of the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon produced in Example 1, with the enlarged image of the catalyst and the particle size distribution each provided in the small image. Fig. Figure 4 shows the comparative curves of the cycle application performance for the production of 6-methyl-2-heptadone(II) from the selective hydrogenation of 6-methyl-3,5-heptadien-2-one(VII) using the catalysts from Example 1, Comparative Example 1 and Comparative Example 2, respectively. Fig. Figure 5 shows a cycle application performance curve for the production of 6,10-dimethyl-2-undecanone(IV) from the selective hydrogenation of 6,10-dimethyl-3,5-diene-2-undecanone(IX) using the catalyst produced in Example 1. Fig. Figure 6 shows a cycle application performance curve for the production of 6,10,14-trimethyl-2-pentadecanone(VI) from the selective hydrogenation of 6,10,14-trimethyl-3,5-diene-2-pentadecanone(X) using the catalyst produced in Example 1. DETAILED DESCRIPTION

[0041] The technical solutions of the embodiments in the present invention are described more clearly and completely below. It is obvious that the described embodiments represent only a subset of the embodiments of the present invention and not all embodiments. All other embodiments that can be obtained by a person skilled in the art from the embodiments in the present invention without creative effort are within the scope of protection of the present invention. Example 1

[0042] 4 g of cellulose, 12 g of sodium bicarbonate, and 12 g of ammonium oxalate were weighed, mechanically mixed, transferred to a 30 ml crucible, and then calcined in a nitrogen oven. The calcination steps were: heating at 10°C / min to 800°C, calcining for 1 hour at 800°C, and then natural cooling to room temperature. The calcined product was milled, mixed with deionized water, allowed to stand for 24 hours, and then filtered. The precipitate was washed to neutral, and the nitrogen-doped hierarchical porous carbon material was obtained by drying and was ready for use.

[0043] One gram of nitrogen-doped hierarchical porous carbon material was weighed, added to 60 ml of deionized water, stirred at room temperature, and a 100 mg / ml aqueous solution of NaOH was slowly added dropwise to adjust the pH of the mixture to 10. Then, one ml of a 10 mg / ml aqueous solution of PdCl₂ was added dropwise, and the mixture was stirred for one hour at room temperature. While stirring, two ml of a 10 mg / ml aqueous solution of formic acid were added dropwise, and the mixture was stirred for another hour at room temperature. The mixture was then filtered and washed to neutral to obtain the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon.

[0044] The actual loading of Pd in ​​the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon, as prepared in this example, was determined using atomic emission spectrum analysis. The result is 0.59%, which is essentially in agreement with the theoretical loading of Pd.

[0045] The nitrogen-doped porous carbon composite produced in the present example was subjected to an X-ray diffraction test. The result is shown in Fig. 1 shown. In Fig. Figure 1 shows that the characteristic diffraction peaks of Pd metal can be observed at 40.1° and 46.7°. The nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon, prepared in the present example, was investigated by scanning electron microscopy. The result is shown in Figure 1. Fig. 2 shown. As in Fig. Figure 2 shows that rich pore channel structures can be observed. The nitrogen-doped hierarchical porous carbon composite produced in the present example was examined using transmission electron microscopy. The result is shown in Fig. 3 shown. As in Fig. Figure 3 shows that the Pd nanoparticles are evenly distributed in the nitrogen-doped porous carbon material, and the particle size shows a conformity with the normal distribution, with the average particle size being approximately 8nm and the proportion of Pd nanoparticles with a particle size of less than 4nm being very small. Example 2

[0046] One gram of nitrogen-doped hierarchical porous carbon material from Example 1 was weighed, added to 60 ml of deionized water, stirred at room temperature, and a 100 mg / ml aqueous solution of NaOH was slowly added dropwise to adjust the pH of the mixture to 9. Then, one ml of a 10 mg / ml aqueous solution of Pd(NO3)2 was added dropwise, and the mixture was stirred for 1 hour at room temperature. While stirring, two ml of a 15 mg / ml aqueous solution of hydrazine hydrate were added dropwise, and the mixture was stirred for another hour at room temperature. The mixture was then filtered and washed to neutral to obtain the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon.

[0047] In comparison to Example 1, the pH of the mixed solution, the type of precursor salt, and the type and concentration of the reducing agent were modified and altered during the fabrication process of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst in the present example. The particle size of the resulting Pd nanoparticles of the catalyst shows a typical distribution, with an average particle size of approximately 6 nm and a proportion of Pd nanoparticles with a particle size of less than 4 nm of approximately 10%, which is higher than in Example 1. Example 3

[0048] One gram of nitrogen-doped hierarchical porous carbon material from Example 1 was weighed, added to 60 ml of deionized water, stirred at room temperature, and a 100 mg / ml aqueous solution of NaOH was slowly added dropwise to adjust the pH of the mixed solution to 10. Then, one ml of a 10 mg / ml aqueous solution of Pd(NH3)4(NO3)2 was added dropwise, and the mixture was stirred for 1 hour at room temperature. While stirring, two ml of a 20 mg / ml aqueous solution of sodium borohydride were added dropwise, and the mixture was stirred for another hour at room temperature. The mixture was then filtered and washed to neutral to obtain the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon.

[0049] In comparison to Example 1, the pH of the mixed solution, the type of precursor salt, and the type and concentration of the reducing agent were modified and altered during the fabrication process of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst in the present example. The particle size of the resulting Pd nanoparticles of the catalyst shows a typical distribution, with an average particle size of approximately 5 nm and a proportion of Pd nanoparticles with a particle size of less than 4 nm of approximately 40%, which is higher than in Example 1. Comparative example 1

[0050] One gram of commercially available activated carbon was weighed, added to 60 ml of deionized water, stirred at room temperature, and then 1 ml of a 10 mg / mL PdCl₂ solution was added. After half an hour of stirring, 100 mg / mL aqueous solution of NaOH was slowly added dropwise to adjust the pH of the mixture to 10, and stirring continued for 1 hour at room temperature. While stirring, 2 ml of a 20 mg / mL aqueous solution of formic acid was added dropwise, and stirring continued for 1 hour at room temperature. The mixture was then filtered and washed to neutral to obtain the Pd catalyst supported on the activated carbon, which is described as the Pd / AC catalyst.

[0051] In comparison to example 1, the Pd / AC catalyst produced in the present comparative example is produced using a conventional low-temperature liquid-phase reduction process, namely the order of addition of the Pd salt precursor and the alkali hydroxide is exchanged; the Pd salt precursor is added first and then the pH of the solution is adjusted.

[0052] According to tests, it is found that the particle size of the Pd nanoparticles from the Pd / AC catalyst produced in the present comparison example is not uniform, the agglomeration phenomenon occurs, the average particle size is approximately 5nm, and the particles are spherical or ellipsoidal, with the proportion of Pd nanoparticles with a particle size of less than 4nm being ~35% and obviously higher than that in Example 1. Comparative example 2

[0053] One gram of nitrogen-doped hierarchical porous carbon material from Example 1 was weighed, added to 60 ml of deionized water, stirred at room temperature, and then 1 ml of a 10 mg / mL PdCl₂ solution was added. After half an hour of stirring, 100 mg / mL aqueous solution of NaOH was slowly added dropwise to adjust the pH of the mixed solution to 10, and stirring continued for 1 hour at room temperature. While stirring, 2 ml of a 10 mg / mL aqueous solution of formic acid was added dropwise, and stirring continued for 1 hour at room temperature. The mixture was then filtered and washed to neutral to obtain the Pd / CN catalyst supported on the nitrogen-doped hierarchical porous carbon.

[0054] The manufacturing process for the catalyst in Comparative Example 2 is consistent with that in Comparative Example 2, except that nitrogen-doped hierarchical porous carbon is used as the support. The nano-Pd particles of the Pd-CN catalyst have a uniform particle size, an average size of approximately 2 nm, and are spherical or ellipsoidal. Application example 1

[0055] Catalyzing the selective hydrogenation of 6-methyl-5-hepten-2-one(I), as follows: A 50ml high-pressure vessel was used. In it, 50mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6-methyl-5-hepten-2-one(I) 15mmol, ethanol 10mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0056] According to tests, the conversion rate of 6-methyl-5-hepten-2-one(I) is 100% and the selectivity of 6-methyl-2-heptanone (II) is 99.9%. Application example 2

[0057] Catalyzing the selective hydrogenation of 6-methyl-5-hepten-2-one(I), as follows: A 50ml high-pressure vessel was used. In it, 50mg of the nitrogen-doped hierarchical porous carbon nano-Pd catalyst prepared in Example 2, the substrate 6-methyl-5-hepten-2-one(I) 15mmol, ethanol 10mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0058] According to tests, the conversion rate of 6-methyl-5-hepten-2-one(I) is 100% and the selectivity of 6-methyl-2-heptanone (II) is 98.9%. Application example 3

[0059] Catalyzing the selective hydrogenation of 6-methyl-5-hepten-2-one(I), as follows: A 50ml high-pressure vessel was used. In it, 50mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 3, the substrate 6-methyl-5-hepten-2-one(I) 15mmol, ethanol 10mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0060] According to tests, the conversion rate of 6-methyl-5-hepten-2-one(I) is 100% and the selectivity of 6-methyl-2-heptanone (II) is 96.9%. Comparative application example 1~2

[0061] The same process conditions as in application example 1 were applied. The only difference is that the catalyst was replaced by the Pd / Ac and Pd / CN catalysts from comparison example 1 and comparison example 2, respectively, which were produced using the conventional low-temperature reduction process.

[0062] According to tests, the conversion rate and selectivity of the Pd / AC catalyst are 90% and 72% respectively, and the conversion rate and selectivity of the Pd / CN catalyst are 95% and 90% respectively.

[0063] It can be seen that in the selective hydrogenation of unsaturated ketones with the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon produced in Example 1 of the present invention, the activity of the catalyst is maintained and at the same time the selectivity is significantly improved. Application example 4

[0064] Catalyzing the selective hydrogenation of 6,10-dimethyl-5-ene-2-undecanone (III), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10-dimethyl-5-ene-2-undecanone (III) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0065] According to tests, the conversion rate of 6,10-Dimethyl-5-ene-2-undecanone (III) is 100% and the selectivity of 6,10-Dimethyl-2-undecanone (IV) is 99.9%. Application example 5

[0066] Catalyzing the selective hydrogenation of 6,10,14-trimethyl-5-ene-2-pentadecanone(V), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10,14-trimethyl-5-ene-2-pentadecanone(V) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0067] According to tests, the conversion rate of 6,10,14-trimethyl-5-ene-2-pentadecanone(V) is 100% and the selectivity of 6,10,14-trimethyl-2-pentadecanone(VI) is 99.9%. Application example 6

[0068] Catalyzing the selective hydrogenation of 6-methyl-3,5-heptadien-2-one(VII), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6-methyl-3,5-heptadien-2-one(VII) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0069] According to tests, the conversion rate of 6-methyl-3,5-heptadien-2-one(VII) is 100% and the selectivity of 6-methyl-2-heptanone (II) is 99.8%. Application example 7

[0070] Catalyzing the selective hydrogenation of 6,10-dimethyl-5,9-diene-2-undecanone(VIII), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10-dimethyl-5,9-diene-2-undecanone(VIII) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0071] According to tests, the conversion rate of 6,10-Dimethyl-5,9-diene-2-undecanone(VIII) is 100% and the selectivity of 6,10-Dimethyl-2-undecanone(IV) is 99.8%. Application example 8

[0072] Catalyzing the selective hydrogenation of 6,10-dimethyl-3,5-diene-2-undecanone(IX) , as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10-dimethyl-3,5-diene-2-undecanone(IX) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0073] According to tests, the conversion rate of 6,10-Dimethyl-3,5-diene-2-undecanone(IX) is 100% and the selectivity of 6,10-Dimethyl-2-undecanone(IV) is 99.9%. Application example 9

[0074] Catalyzing the selective hydrogenation of 6,10,14-trimethyl-3,5-diene-2-pentadecanone(X), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10,14-trimethyl-3,5-diene-2-pentadecanone(X) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0075] According to tests, the conversion rate of 6,10,14-trimethyl-3,5-diene-2-pentadecanone(X) is 100% and the selectivity of 6,10,14-trimethyl-2-pentadecanone(VI) is 99.9%. Application example 10

[0076] Catalyzing the selective hydrogenation of 6,10,14-trimethyl-5,9,13-triene-2-pentadecanone(XI), as follows: A 50ml high-pressure vessel was used. In it, 50 mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate 6,10,14-trimethyl-5,9,13-triene-2-pentadecanone(XI) 15 mmol, ethanol 10 mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0077] According to tests, the conversion rate of 6,10,14-trimethyl-5,9,13-trien-2-pentadecanone(XI) is 100% and the selectivity of 6,10,14-trimethyl-2-pentadecanone(VI) is 99.8%. Application example 11

[0078] Catalyzing the selective hydrogenation of cis-3,7-dimethyl-2,6-diene octanal (XII), as follows: A 50ml high-pressure vessel was used. In it, 50mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1, the substrate cis-3,7-dimethyl-2,6-diene octanal (XII) 15mmol, ethanol 10mmol, and hydrogen 2MPa were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours.

[0079] According to the test, the conversion rate of cis-3,7-dimethyl-2,6-diene octanal (XII) is 100% and the selectivity of cis-3,7-dimethyl octanal (XIII) is 99.6%. Application example 12

[0080] Catalyzing the selective hydrogenation of trans-3,7-dimethyl-2,6-diene octanal (XIV), as follows: A 50ml high-pressure vessel was used. 50mg of the nitrogen-doped hierarchical porous carbon-supported nano-Pd catalyst prepared in Example 1 was added, along with 15mmol of the substrate trans-3,7-dimethyl-2,6-diene octanal (XIV), 10mmol of ethanol, and 2MPa of hydrogen. The reaction temperature was 30°C and the reaction time lasted 4 hours.

[0081] According to tests, the conversion rate of trans-3,7-dimethyl-2,6-diene octanal (XIV) is 100% and the selectivity of 3,7-dimethyl octanal (XIII) is 99.8%. Application example 13

[0082] Comparison of utilization performance for catalyzing the selective hydrogenation reaction of 6-methyl-3,5-heptadien-2-one (VII), as follows: For the use of each catalyst, experiments were carried out in parallel in two vessels. A 50 ml high-pressure vessel was used. In each vessel, 50 mg of the nitrogen-doped hierarchical porous carbon nano-Pd catalyst from Example 1, the catalyst prepared in Comparative Example 1, or the catalyst prepared in Comparative Example 2, 15 mmol of 6-methyl-3,5-heptadien-2-one (VII), 10 ml of ethanol, and 2 MPa of hydrogen were added. The reaction temperature was 40°C, and the reaction time lasted 4 hours. After the reaction, the catalysts in both vessels were removed by centrifugation, washed three times with ethanol, and dried under vacuum at 40°C. The catalyst from one boiler was continued after the catalyst from the boiler for the parallel experiment on the selective hydrogenation reaction of 6-methyl-3,5-heptadien-2-one (VII).

[0083] The underlying chemical reactions are described below using reaction equations. The following reaction equations show the chemical reactions of the selective hydrogenation of monoketones with the nano-Pd catalyst according to the invention, supported on nitrogen-doped hierarchical porous carbon.

[0084] The following reaction equations show the chemical reactions of the selective hydrogenation of dienketones and trienketones with the nano-Pd catalyst according to the invention supported on nitrogen-doped hierarchical porous carbon.

[0085] The following reaction equations show the chemical reactions of the selective hydrogenation of dienketones and trienketones with the nano-Pd catalyst according to the invention supported on nitrogen-doped hierarchical porous carbon.

[0086] The usage results are in the Fig. Figure 4 shows that the nitrogen-doped hierarchical porous carbon nano-Pd catalyst from Example 1 is stable, and its activity and selectivity can be maintained after 100 uses. The activity and selectivity of the Pd / AC catalyst produced in Comparative Example 1 decreased significantly with increasing use, and the conversion rate and selectivity can only be maintained at approximately 50% and 60%, respectively, after 100 uses. The conversion rate and selectivity of the Pd / CN catalyst produced in Comparative Example 2 are maintained at approximately 90% and 95% of an initial value. Application example 14

[0087] Comparison of utilization performance for catalyzing the selective hydrogenation reaction of 6,10-dimethyl-3,5-diene-2-undecanone (IX), as follows: For the use of each catalyst, experiments were carried out in parallel in two vessels. A 50 ml high-pressure vessel was used. In each vessel, 50 mg of the nitrogen-doped hierarchical porous carbon nano-Pd catalyst from Example 1, the catalyst prepared in Comparative Example 1, or the catalyst prepared in Comparative Example 2, 15 mmol of 6,10-dimethyl-3,5-diene-2-undecanone (IX), 10 ml of ethanol, and 2 MPa of hydrogen were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours. After the reaction, the catalysts in both vessels were removed by centrifugation, washed three times with ethanol, and dried under vacuum at 40°C. The catalyst from one boiler after supplementation of the catalyst from the boiler for the parallel experiment was continued to the selective hydrogenation reaction of 6,10-Dimethyl-3,5-diene-2-undecanone (IX).

[0088] The usage results are in the Fig. 5 shown. It can be found that the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon of Example 1 is stable and that after 100 uses the activity can still be maintained and the selectivity only decreases slightly. Application example 15

[0089] Comparison of utilization performance for catalyzing the selective hydrogenation reaction of 6,10,14-trimethyl-3,5-diene-2-pentadecanone (X), as follows: For the use of each catalyst, experiments were carried out in parallel in two vessels. A 50 ml high-pressure vessel was used. In each vessel, 50 mg of the nitrogen-doped hierarchical porous carbon nano-Pd catalyst from Example 1, the catalyst prepared in Comparative Example 1, or the catalyst prepared in Comparative Example 2, 15 mmol of 6,10,14-trimethyl-3,5-diene-2-pentadecanone (X), 10 ml of ethanol, and 2 MPa of hydrogen were added. The reaction temperature was 30°C, and the reaction time lasted 4 hours. After the reaction, the catalysts in both vessels were removed by centrifugation, washed three times with ethanol, and dried under vacuum at 30°C. The catalyst from one boiler after supplementation of the catalyst from the boiler for the parallel experiment was continued to the selective hydrogenation reaction of 6,10,14-trimethyl-3,5-diene-2-pentadecanone (X).

[0090] The usage results are in the Fig.Figure 6 shows that the nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon from Example 1 is stable and that after 100 uses the activity can still be maintained and the selectivity only decreases slightly.

[0091] The various technical features of the embodiments described above can be combined in any number of ways. To keep the description concise, not all possible combinations of the various technical features in the embodiments described above are presented here. However, as long as the combination of these technical features does not conflict, it should be understood that the scope of this description is not to be interpreted in a restrictive sense.

[0092] The embodiments described above merely represent several embodiments of the present invention, which are described in detail, but are not to be interpreted as limiting the scope of the invention. It should be noted that, without departing from the concept of the present invention, numerous variations and modifications can be made by a person skilled in the art, all of which fall within the scope of the present invention. Accordingly, the scope of protection of the present invention should be defined by the accompanying claims.

Claims

[1] Method for producing a nano-Pd catalyst supported on a nitrogen-doped hierarchical porous carbon, characterized by , that it includes: 1) Preparation of a nitrogen-doped hierarchical porous carbon, 2) Mixing the nitrogen-doped hierarchical porous carbon produced in step 1) with water and adjusting the pH of the mixed solution to alkaline. 3) Mixing the mixture solution prepared in step 2) with the aqueous solution of Pd metal precursors, adding reducing agent and obtaining the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon after reduction. [2] Method according to claim 1, characterized by , that in step 2) the mass volume ratio of the nitrogen-doped hierarchical porous carbon to water is 1:20-200g / mL and the pH of the mixed solution is adjusted to 8-12. [3] Method according to claim 1, characterized by , that in step 3) the Pd metal precursor is selected from a soluble salt of metal Pd, the concentration of the aqueous solution of the Pd metal precursor is 1-50mg / mL and the mass ratio of the nitrogen-doped hierarchical porous carbon to the Pd metal precursor is 3-600:

1. [4] Method according to claim 1, characterized by , that in step 3) the reducing agent is at least one of hydrazine hydrate, formic acid, sodium borohydride and sodium formate and the mass ratio of the reducing agent to the Pd metal precursor is 1-20:

1. [5] Method according to claim 4, characterized by that the reducing agent is added as an aqueous solution of the reducing agent and the mass volume ratio of the reducing agent to water is 1-20mg / mL. [6] Method according to claim 1, characterized by, that in step 3) the temperature for reduction is 0-80°C and the time is 1-360 minutes. [7] Method according to claim 1, characterized by , that in step 3) the reduced product will be further treated by filtration to obtain the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon, and the water content in the nano-Pd catalyst supported on the nitrogen-doped hierarchical porous carbon is 5-75 wt.%. [8] Nano-Pd catalyst supported on nitrogen-doped hierarchical porous carbon, produced by the method according to any one of claims 1 to 7, comprising the nitrogen-doped carbon material support having hierarchical porous channels and the nano-Pd metal particles supported in the hierarchical porous channels by the support, characterized by, that the nano-Pd metal particles have a particle size of 2-14nm and regular polyhedral shape, and the mass fraction of the nano-Pd metal particles is 0.1-10% based on the total mass of the catalyst. [9] Use of the nitrogen-doped hierarchical carbon nano-Pd catalyst according to claim 8 in a catalytic hydrogenation reaction. [10] Use according to claim 9, characterized by that the catalytic hydrogenation reaction is the selective hydrogenation reaction for unsaturated ketones and the unsaturated ketone is at least one selected from 6-methyl-5-hepten-2-one, 6-methyl-3,5-heptadien-2-one, 6,10-dimethyl-5-ene-2-undecanone, 6,10-dimethyl-5,9-diene-2-undecanone, 6,10-dimethyl-3,5-diene-2-undecanone, 6,10,14-trimethyl-5-ene-2-pentadecanone, 6,10,14-trimethyl-5,9,13-triene-2-pentadecanone, 6,10,14-trimethyl-3,5-diene-2-pentadecanone, cis 3,7-dimethyl-2,6-diene octanal, trans 3,7-Dimethyl-2,6-diene octanal.

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