A ligand-modified pd / c catalyst, its preparation and application in selective hydrogenation of nitrogen-containing alkynes

Abstract

The application discloses a ligand modified Pd / C catalyst, a preparation method thereof and application of the catalyst in selective hydrogenation of nitrogen-containing alkyne, and the catalyst comprises a porous carbon carrier, palladium nanoparticles loaded on the carrier and organic ligands coordinated on the surface of the catalyst, the mass of the palladium nanoparticles is 0.5-2% of the mass of the porous carbon carrier, the organic ligands are selected from at least one of oxalic aniline, L-lysine, ethylenediaminetetraacetic acid and oleylamine, and the molar ratio of the organic ligands to palladium is 1-8:1. When the catalyst is applied to catalyzing semi-hydrogenation of 3-ethynylquinoline to prepare 3-vinylquinoline, the selectivity of the target product is as high as 97%, and the conversion rate of the reaction is 99%. In addition, under the same conditions, when thiophene is added into the system, the catalyst still has excellent sulfur poisoning resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a ligand-modified Pd / C catalyst, its preparation and application in selective hydrogenation of nitrogen-containing alkynes. BACKGROUND

[0002] Selective hydrogenation of alkynes is an important step in industrial production, and its semi-hydrogenation product olefin is widely used in the synthesis of fine chemicals, pesticides and pharmaceutical intermediates. However, due to the high adsorption energy of olefin on the continuous palladium surface, it is not conducive to its rapid desorption, which leads to the formation of undesirable over-hydrogenated products. Therefore, maintaining high selectivity of the target product is the key to industrial production.

[0003] Nitrogen is one of the most abundant elements on earth, and nitrogen-containing compounds are ubiquitous in nature. Nitrogen-containing alkynes / olefins are involved in many fields such as chemical and pharmaceutical fields, life science fields, etc. Nitrogen-containing olefins are usually obtained by semi-hydrogenation of the corresponding alkynes, but a difficult industrial problem is that the nitrogen atom has a lone pair of electrons and acts as a Lewis base, which can strongly coordinate with metal atoms (especially noble metals), isolate active sites and prevent reactant molecules from approaching the active center, leading to catalyst poisoning and deactivation. So far, due to the poisoning of heteroatoms to noble metal ions, the selective hydrogenation of nitrogen-containing alkynes has been rarely reported. Therefore, it is urgent to develop a catalyst with both selectivity and resistance to poisoning for the semi-hydrogenation of nitrogen-containing alkynes.

[0004] In heterogeneous catalysis, the traditional anti-poisoning strategy is to encapsulate metal nanoparticles in a structural shell, use metal heteroatoms (N / P / S, etc.) as catalysts or foreign atoms to dope metals. Frank's group synthesized a new type of heterogeneous Ru-S catalyst, which can reduce unstable groups such as aromatic hydrocarbons, halides and olefins under mild conditions, and more specifically, it shows wide tolerance to various sulfur-containing functional groups (sulfides, disulfides, thiophenes and sulfoxides) and medical-related (sulfonamides and sulfonyl chlorides) (J. Am. Chem. Soc. 2024, 146, 5864-5871). Zhang et al. used P-rich and C-rich polymers as precursors to encapsulate metal phosphide nanoparticles in a two-dimensional defect-rich graphite carbon shell, and adjusted the carbon layer thickness by changing the molar ratio of metal to phosphorus. The prepared catalyst has excellent selectivity in the semi-hydrogenation of phenylacetylene, and also shows high resistance to sulfur poisoning, in which the selective permeability of the carbon shell is the key to enhancing the stability of the catalyst (Chemical Engineering Journal 463 (2023) 142505). Although these methods effectively improve the anti-poisoning ability of the catalyst, there are still a series of shortcomings, such as high metal loading, leaching of active species in solution and inaccessibility of active sites, etc.

[0005] There is an urgent need to develop a simple preparation method, low metal loading and low cost of high efficiency anti-poisoning catalyst. Due to the good coordination ability of organic ligand and metal ion, it can be further anchored on the carrier due to its unique property. The application adopts a simple impregnation coordination method to prepare a high-efficiency Pd / C catalyst with anti-poisoning performance. SUMMARY

[0006] In view of the above technical problems existing in the prior art, the purpose of the present application is to provide a ligand modified Pd / C catalyst and its preparation and application in selective hydrogenation of nitrogen-containing alkynes. The Pd / C catalyst is synthesized by a simple impregnation coordination method. The Pd / C catalyst has good stability under air, solvent or high temperature conditions and can be reused under the same reaction conditions. When it is applied to the selective hydrogenation of nitrogen-containing alkynes, it shows excellent catalytic performance and sulfur poisoning resistance.

[0007] The technical scheme adopted by the present application is as follows:

[0008] A ligand modified Pd / C catalyst, comprising a porous carbon carrier, palladium nanoparticles loaded on the carrier and organic ligands coordinated on the surface of the catalyst, the mass of the palladium nanoparticles is 0.5-2% of the mass of the porous carbon carrier, the organic ligands are selected from at least one of oxanilide, L-lysine, ethylenediaminetetraacetic acid or oleylamine, and the molar ratio of the organic ligands to palladium is 1-8:1.

[0009] Further, the mass of the palladium nanoparticles is 0.8-1.2% of the mass of the porous carbon carrier, the organic ligands are selected from oxanilide, and the molar ratio of the organic ligands to palladium is 2-3:1.

[0010] Further, the preparation method of the porous carbon carrier comprises the following steps: mixing cellulose and ammonium bicarbonate in a mortar at a mass ratio of 1:0.8-1.2, then calcining at 700-900℃ under Ar atmosphere for 1-3h, cooling to room temperature, and then washing and drying the obtained black powder to obtain the porous carbon.

[0011] The preparation method of the ligand modified Pd / C catalyst comprises the following steps: adding organic ligands to anhydrous ethanol, stirring uniformly, then adding a palladium precursor solution, stirring overnight at room temperature, then adding a porous carbon carrier, the concentration of the dispersed porous carbon carrier in anhydrous ethanol is 5-30g / L, the mixed solution is transferred to a 70-90℃ oil bath heating environment for continuous stirring until the ethanol is completely evaporated, and the obtained black powder is reduced at 180-250℃ under hydrogen atmosphere for 1-3h to obtain the catalyst.

[0012] Further, the palladium precursor is Pd(NO3)2, PdCl2 or K2PdCl4, preferably Pd(NO3)2; the mass of Pd element in the palladium precursor is 0.5-2% of the mass of the porous carbon carrier, preferably 0.8-1.2%.

[0013] Further, in the preparation method of the ligand-modified Pd / C catalyst, the organic ligand is at least one selected from oxalic amide, L-lysine, ethylenediaminetetraacetic acid or oleylamine, preferably oxalic amide, and the molar ratio of the organic ligand to palladium is 1-8:1, preferably 2-3:1.

[0014] The application also provides the ligand-modified Pd / C catalyst, the preparation thereof and the use thereof in selective hydrogenation of nitrogen-containing alkynes, wherein the nitrogen-containing alkynes are mixed with a solvent, and then the reaction solution is subjected to selective hydrogenation under the action of the Pd / C catalyst in a hydrogen atmosphere to generate nitrogen-containing alkenes; the hydrogenation temperature is 0-100℃, the hydrogen pressure is 0.1-4 MPa, and the solvent is water, ethanol, dichloromethane, tetrahydrofuran or n-hexane.

[0015] Further, the mass of the catalyst is 1-10% of the mass of the nitrogen-containing alkynes, preferably 2-5%; the selective hydrogenation temperature is 25-40℃; the hydrogen pressure is 0.1-0.5 MPa; and the solvent is ethanol.

[0016] Thanks to the use of the above technical solutions, the application has the following advantages compared with the prior art:

[0017] 1. The oxalic amide is added in the application, and the palladium nanoparticles coordinated with the oxalic amide are obtained after the reduction of hydrogen after the simple impregnation coordination and the loading on the porous carbon. The preparation method of the catalyst is simple, time-saving, low in production cost and low in metal loading.

[0018] 2. Since the palladium nanoparticles are anchored on the carrier by the organic ligand, the sintering and agglomeration of the palladium nanoparticles under the high-temperature reduction atmosphere and the leaching of the palladium nanoparticles in the reaction solution are greatly inhibited, so that the palladium nanoparticles prepared by the application are uniform in size and good in dispersity. The Pd / C catalyst has good stability under air, solvent or high-temperature conditions and can be reused under the same reaction conditions.

[0019] 3、The ligand modified Pd / C catalyst in the application and its application in selective hydrogenation of nitrogen-containing alkyne are universal, which can be applied to self-made Pd / C and commercial Pd / C, and has good industrial prospect. The introduction of oxalic acid amide can change the electronic structure of palladium, improve the electronic density of palladium species, promote the activation and dissociation of H2, optimize the microenvironment of the reaction by constructing metal-ligand electronic interaction, promote the desorption of nitrogen-containing alkyne and weaken the enrichment of nitrogen species on the palladium surface, thereby improving the catalytic activity, selectivity and anti-poisoning performance of selective hydrogenation of nitrogen-containing alkyne. When the Pd / C catalyst in the application is used in the preparation of nitrogen-containing alkyne by selective hydrogenation of nitrogen-containing alkyne, the conversion rate of the reactant is 99%, and the selectivity of the product is as high as 97%, and even if the reaction time is prolonged, there is no obvious over-hydrogenation. At the same time, a certain amount of thiophene is added to the reaction system, and the ligand modified catalyst still maintains high activity, which reflects its more excellent anti-sulfur poisoning ability. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A transmission electron microscope image of the catalyst prepared in Example 1;

[0021] Figure 2 A high-resolution transmission electron microscope image of the catalyst prepared in Example 1; DETAILED DESCRIPTION

[0022] The application will be further described below in conjunction with specific examples, but the protection scope of the application is not limited thereto.

[0023] In the embodiment of the application, the cellulose used for preparing the porous carbon carrier has a particle size of 65 μm and is purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.

[0024] In the embodiment of the application, the preparation steps of the self-made porous carbon carrier are as follows: cellulose and ammonium bicarbonate are uniformly mixed in a mortar at a mass ratio of 1:1, and then calcined at 800 DEG C for 2 h under Ar atmosphere, and cooled to room temperature. The obtained black powder is washed with water overnight, dried, and the porous carbon carrier powder is obtained.

[0025] Example 1: self-made Pd / C catalyst modified based on oxalic acid amide ligand (molar ratio 1:2)

[0026] 9 mg of oxalic acid amide (0.0375 mmol) is placed in a 20 ml glass bottle, 12 ml of anhydrous ethanol is added, 1 ml of Pd(NO3)2 solution (the mass concentration of Pd is 2 mg / ml) is added after stirring uniformly, and then 200 mg of self-made porous carbon carrier powder is added after stirring overnight at room temperature, and then transferred to an 80 DEG C oil bath for continuous stirring until the ethanol is completely evaporated. The obtained black powder is reduced at 200 DEG C under hydrogen atmosphere for 2 h to obtain the catalyst.

[0027] The catalyst prepared in Example 1 was characterized by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), and the results are as follows: Figure 1 and Figure 2 As shown. From Figure 1 This demonstrates the successful loading of palladium nanoparticles onto porous carbon, resulting in relatively uniform particle size and good dispersibility. Statistical analysis of over 200 nanoparticles revealed an average particle size of 5.0 nm. Figure 2 The distinctive and clear palladium lattice stripes can be observed, with a lattice spacing of 0.229 nm, which is attributed to the Pd(111) plane.

[0028] The catalyst prepared in Example 1 was characterized by inductively coupled plasma mass spectrometry and then analyzed by EDS energy dispersive spectroscopy. The results showed that the Pd content in the catalyst of Example 1 was 0.9%.

[0029] Example 2: Commercial Pd / C catalyst based on oxaloylaniline ligand modification

[0030] 43 mg of oxaloyl aniline was placed in a 50 ml glass bottle, and 20-30 ml of anhydrous ethanol was added. After stirring evenly, 500 mg of commercial Pd / C catalyst (the Pd loading on the catalyst support was 10%, and the water content of the catalyst was 55%) was added. The mixture was stirred at 60 °C for 1 h, and then the temperature was increased and stirring continued until the ethanol was completely evaporated. The resulting black powder was reduced at 200 °C for 2 h under a hydrogen atmosphere to obtain the catalyst.

[0031] Example 3: Homemade Pd / C catalyst based on oxaloylaniline ligand (molar ratio 1:1)

[0032] Example 3 The catalyst preparation steps were repeated in Example 1, except that "the amount of oxaloyl aniline added was replaced with 4.5 mg", and the other conditions remained the same, and the catalyst was finally obtained.

[0033] Example 4: Homemade Pd / C catalyst based on oxaloylaniline ligand (molar ratio 1:4)

[0034] Example 4 The catalyst preparation steps were repeated in Example 1, except that the amount of oxaloyl aniline added was replaced with 18 mg, and the other conditions remained the same, and the catalyst was finally obtained.

[0035] Example 5: Homemade Pd / C catalyst based on oxaloylaniline ligand (molar ratio 1:8)

[0036] Example 5 The catalyst preparation steps were repeated in Example 1, except that the amount of oxaloyl aniline added was replaced with 36 mg, and the other conditions remained the same, and the catalyst was finally obtained.

[0037] Example 6 Self-made Pd / C catalyst modified with L-lysine ligand (molar ratio 1:2)

[0038] Example 5 Catalyst preparation step repeats Example 1, the only difference is that "0.0375 mmol of oxalic acid anilide is replaced by the same molar amount of L-lysine", the rest of the conditions remain the same, and finally the catalyst is obtained.

[0039] Example 7 Self-made Pd / C catalyst modified with ethylenediaminetetraacetic acid ligand (molar ratio 1:2)

[0040] Example 7 Catalyst preparation step repeats Example 1, the only difference is that "0.0375 mmol of oxalic acid anilide is replaced by the same molar amount of ethylenediaminetetraacetic acid", the rest of the conditions remain the same, and finally the catalyst is obtained.

[0041] Example 8 Self-made Pd / C catalyst modified with oleylamine ligand (molar ratio 1:2)

[0042] Example 8 Catalyst preparation step repeats Example 1, the only difference is that "0.0375 mmol of oxalic acid anilide is replaced by the same molar amount of oleylamine", the rest of the conditions remain the same, and finally the catalyst is obtained.

[0043] Example 9 3-Ethynylquinoline semi-hydrogenation catalyzed by Pd / C catalyst

[0044] 306 mg of 3-ethynylquinoline, 10 mg of catalyst and 5 mL of ethanol were added to a 50 mL stainless steel autoclave, the stainless steel autoclave was filled with hydrogen gas for three times (i.e. the air in the stainless steel autoclave was replaced by hydrogen, and the air in the stainless steel autoclave was evacuated), hydrogen was filled to 0.1 MPa and sealed, and the selective hydrogenation reaction was carried out in a 30°C water bath with magnetic stirring. After a period of time, the reaction was sampled and analyzed, and the reaction liquid was detected by gas chromatography to calculate the reaction results.

[0045] According to the above experimental method of catalyzing 3-ethynylquinoline semi-hydrogenation, the catalysts prepared in different examples were used for catalytic reaction, and the results were as follows:

[0046] 1) Using the catalyst of Example 1, the reaction results are as follows: when the reaction time is 25 min, the conversion rate of 3-ethynylquinoline is 79%, and the selectivity of 3-vinylquinoline is 99%. When the reaction time is extended to 32 min, the conversion rate of 3-ethynylquinoline is 99%, and the selectivity of 3-vinylquinoline is 97%. When the reaction time is further extended to 2 h, the selectivity of 3-vinylquinoline can still remain at 88%.

[0047] 2) Using the catalyst of Example 2, the reaction results are as follows: when the reaction time is 6 min, the conversion rate of 3-ethynylquinoline is 92%, and the selectivity of 3-vinylquinoline is 97%.

[0048] 3) Using the catalyst of Example 3, the reaction results were: the conversion of 3-ethynylquinoline was 50% and the selectivity of 3-vinylquinoline was 98% at a reaction time of 25 min.

[0049] 4) Using the catalyst of Example 4, the reaction results were: the conversion of 3-ethynylquinoline was 76% and the selectivity of 3-vinylquinoline was 99% at a reaction time of 25 min.

[0050] 5) Using the catalyst of Example 5, the reaction results were: the conversion of 3-ethynylquinoline was 62% and the selectivity of 3-vinylquinoline was 99% at a reaction time of 25 min.

[0051] 6) Using the catalyst of Example 6, the reaction results were: the conversion of 3-ethynylquinoline was 35% and the selectivity of 3-vinylquinoline was 99% at a reaction time of 25 min.

[0052] 7) Using the catalyst of Example 7, the reaction results were: the conversion of 3-ethynylquinoline was 48% and the selectivity of 3-vinylquinoline was 98% at a reaction time of 25 min.

[0053] 8) Using the catalyst of Example 8, the reaction results were: the conversion of 3-ethynylquinoline was 64% and the selectivity of 3-vinylquinoline was 96% at a reaction time of 25 min.

[0054] From the above experimental results, it can be seen that oxalic acid amide has a more obvious promoting effect on the catalytic performance in the semi-hydrogenation of nitrogen-containing acetylene than other organic ligands. When the molar ratio of palladium to oxalic acid amide is too low or too high, the catalytic performance is inhibited. When the molar ratio of palladium to oxalic acid amide is 1:2, the catalytic performance in the semi-hydrogenation of nitrogen-containing acetylene is the best.

[0055] Example 10: Pd / C catalyst prepared in Example 1 catalyzing the semi-hydrogenation of 3-ethynylquinoline in a sulfur-containing system

[0056] 306 mg of 3-ethynylquinoline, 10 μL of thiophene, 10 mg of the Pd / C catalyst prepared in Example 1 and 5 mL of ethanol were added to a 50 mL stainless steel autoclave. After the stainless steel autoclave was filled with hydrogen gas for three times, the hydrogen gas was filled to 0.1 MPa and sealed. The selective hydrogenation reaction was carried out under magnetic stirring at 30°C in a water bath. After 25 min, the reaction was stopped and the residual hydrogen gas in the stainless steel autoclave was carefully discharged. The reaction liquid was taken out. The Pd / C catalyst and the reaction liquid were separated by centrifugation. The reaction liquid was detected by gas chromatography. The conversion of 3-ethynylquinoline was 65% and the selectivity of 3-vinylquinoline was 99%.

[0057] Example 11 Semi-hydrogenation of 3-ethynylquinoline catalyzed by Pd / C catalyst prepared in Example 2 in sulfur-containing system

[0058] 306 mg of 3-ethynylquinoline, 100 μL of thiophene, 10 mg of Pd / C catalyst prepared in Example 2 and 5 mL of ethanol were added into a 50 mL stainless steel autoclave. After the stainless steel autoclave was charged with hydrogen for three times, it was sealed and heated in a 30 °C water bath with magnetic stirring. The selective hydrogenation reaction was carried out for 6 min. After the reaction was stopped, the residual hydrogen in the stainless steel autoclave was carefully discharged, and the reaction solution was taken out. The Pd / C catalyst and the reaction solution were separated by centrifugation, and the reaction solution was detected by gas chromatography. The conversion of 3-ethynylquinoline was calculated to be 78%, and the selectivity of 3-vinylquinoline was 97%.

[0059] It can be seen from the comparison of the experimental results of Example 9 Experiment 1) and Example 10-11 that the introduction of oxanilide can change the electronic structure of palladium, so that the catalyst has excellent sulfur poisoning resistance. The strategy of oxanilide modified palladium nanoparticles for resisting nitrogen (or sulfur) atom poisoning has universality and good industrial application prospect.

[0060] Example 12 Semi-hydrogenation of 3-ethynylquinoline catalyzed by the catalyst used in Example 9 Experiment 1)

[0061] The reaction of Example 9 Experiment 1) was stopped after 2 h, the residual hydrogen in the stainless steel autoclave was carefully discharged, and the reaction solution was taken out. The Pd / C catalyst and the reaction solution were separated by centrifugation, and the recovered Pd / C catalyst was used in the next batch of reaction. The reaction process was as follows:

[0062] 306 mg of 3-ethynylquinoline, 10 mg of recovered Pd / C catalyst and 5 mL of ethanol were added into a 50 mL stainless steel autoclave. After the stainless steel autoclave was charged with hydrogen for three times, it was sealed and heated in a 30 °C water bath with magnetic stirring. The selective hydrogenation reaction was carried out for 25 min. After the reaction was stopped, the residual hydrogen in the stainless steel autoclave was carefully discharged, and the reaction solution was taken out. The Pd / C catalyst and the reaction solution were separated by centrifugation, and the reaction solution was detected by gas chromatography. The conversion of 3-ethynylquinoline was calculated to be 75%, and the selectivity of 3-vinylquinoline was 99%.

[0063] It can be seen from the comparison of the experimental results of Example 12 and Example 9 Experiment 1) that the oxanilide modified Pd / C catalyst has good reusability, which indicates that it has excellent stability under the reaction conditions.

[0064] Comparative Example 1 Semi-hydrogenation of 3-ethynylquinoline catalyzed by self-made Pd / C catalyst without ligand modification

[0065] Catalyst preparation: 1 ml Pd(N03)2solution (2 mg / ml of Pd) was placed in a 20 ml glass bottle, 12 ml absolute ethanol was added, after stirring evenly 200 mg self-made porous carbon carrier was added, and then it was transferred to an 80 °C oil bath for continuous stirring until the ethanol was completely evaporated. The obtained black powder was reduced at 200 °C under hydrogen atmosphere for 2 h to obtain the catalyst.

[0066] The reaction of catalyzing the semi-hydrogenation of 3-ethynylquinoline was carried out by referring to Example 9, using the catalyst of Comparative Example 1. The reaction results were as follows: the conversion rate of 3-ethynylquinoline was 45% and the selectivity of 3-vinylquinoline was 98% when the reaction time was 25 min. When the reaction time was extended to 45 min, the conversion rate of 3-ethynylquinoline was 99% and the selectivity of 3-vinylquinoline was 94%. When the reaction time was further extended to 2 h, the selectivity of 3-vinylquinoline rapidly decreased to 53%.

[0067] The reaction of catalyzing the semi-hydrogenation of 3-ethynylquinoline in a sulfur-containing system was carried out by referring to Example 10, using the catalyst of Comparative Example 1. The reaction results were as follows: the conversion rate of 3-ethynylquinoline was 24% and the selectivity of 3-vinylquinoline was 98% when the reaction time was 25 min.

[0068] Comparative Example 2: Catalyzing the semi-hydrogenation of 3-ethynylquinoline based on a commercial Pd / C catalyst without ligand modification

[0069] Catalytic reaction process: 306 mg of 3-ethynylquinoline, 10 mg of the existing commercial Pd / C catalyst (55% water content) of Comparative Example 2 and 5 mL of ethanol were added to a 50 mL stainless steel autoclave. After hydrogen was filled in and discharged in the stainless steel autoclave for 3 times, hydrogen was filled to 0.1 MPa and sealed, and then selective hydrogenation reaction was carried out under magnetic stirring at 30 °C water bath heating. After the reaction was stopped, the residual hydrogen in the stainless steel autoclave was carefully discharged, and the reaction liquid was taken out. The Pd / C catalyst and the reaction liquid were separated by centrifugation, and the reaction liquid was detected by gas chromatography. The conversion rate of 3-ethynylquinoline was 53% and the selectivity of 3-vinylquinoline was 98% which were calculated by detection.

[0070] Catalytic reaction process under sulfur-containing conditions: 306 mg of 3-ethynylquinoline, 45 μl of thiophene, 10 mg of the existing commercial Pd / C catalyst of Comparative Example 2 (55% water content), and 5 mL of ethanol were added to a 50 mL stainless steel autoclave, which was then subjected to three hydrogen gas charging and discharging operations, and then was charged with hydrogen to 0.1 MPa and sealed. The selective hydrogenation reaction was carried out under magnetic stirring at 30°C in a water bath. After 180 min, the reaction was stopped, and the residual hydrogen in the autoclave was carefully discharged. The reaction solution was separated from the Pd / C catalyst by centrifugation, and the reaction solution was detected by gas chromatography. The conversion of 3-ethynylquinoline was 8%, and the selectivity of 3-vinylquinoline was 96%.

[0071] From the further comparison of the experimental results of Comparative Examples 1-2 and Examples 9-11, it can be concluded that the introduction of oxalic amide can improve the activity and selectivity of the catalyst in the semi-hydrogenation reaction of nitrogen-containing acetylenes, and even has good catalytic performance under sulfur-containing conditions, whether the Pd / C is self-made or commercial. Therefore, this strategy can be applied to industrial scale production.

[0072] Comparative Example 3: Semi-hydrogenation of 3-ethynylquinoline catalyzed by Pd / C catalyst based on conventional activated carbon

[0073] Catalyst preparation: 1 ml of Pd(NO3)2 solution (2 mg / ml of Pd) was placed in a 20 ml glass bottle, 12 ml of anhydrous ethanol was added, and after stirring uniformly, 200 mg of conventional activated carbon (400 mesh, purchased from Macklin) was added. The mixture was transferred to an 80°C oil bath for continued stirring until the ethanol was completely evaporated. The resulting black powder was reduced at 200°C under a hydrogen atmosphere for 2 h to obtain the catalyst.

[0074] The reaction of catalyzing the semi-hydrogenation of 3-ethynylquinoline was carried out by using the catalyst of Comparative Example 3 according to the reaction of Example 9. The results were as follows: the conversion of 3-ethynylquinoline was 11% and the selectivity of 3-vinylquinoline was 94% after 25 min.

[0075] The semi-hydrogenation of 3-ethynylquinoline in a sulfur-containing system was carried out by using the catalyst of Comparative Example 3 according to the reaction of Example 10. The results were as follows: the conversion of 3-ethynylquinoline was 4% and the selectivity of 3-vinylquinoline was 98% after 25 min.

[0076] Comparative Example 4: Semi-hydrogenation of 3-ethynylquinoline catalyzed by Pd / C catalyst based on oxalic amide ligand modification and loading on conventional activated carbon

[0077] Catalyst preparation: 9 mg of oxalic acid amide (0.0375 mmol) was placed in a 20 ml glass bottle, 12 ml of absolute ethanol was added, after stirring evenly, 1 ml of Pd(NO3)2 solution (mass concentration of Pd was 2 mg / ml) was added, after stirring overnight at room temperature, 200 mg of regular activated carbon (400 mesh, purchased from Maclin) was added, and then transferred to an 80°C oil bath for continuous stirring until the ethanol was completely evaporated, and then the obtained black powder was reduced at 200°C under hydrogen atmosphere for 2 h to obtain the catalyst.

[0078] The reaction of catalyzing the semi-hydrogenation of 3-ethynylquinoline was carried out by referring to Example 9, and using the catalyst of Comparative Example 4, and the reaction results were as follows: the conversion rate of 3-ethynylquinoline was 38% and the selectivity of 3-vinylquinoline was 97% after 25 min of reaction.

[0079] The reaction of catalyzing the semi-hydrogenation of 3-ethynylquinoline in a sulfur-containing system was carried out by referring to Example 10, and using the catalyst of Comparative Example 4, and the reaction results were as follows: the conversion rate of 3-ethynylquinoline was 29% and the selectivity of 3-vinylquinoline was 98% after 25 min of reaction.

[0080] It can be seen from the experimental results of Comparative Examples 3-4 that the catalyst prepared by using regular activated carbon as the carrier and using the same ligand modification method can also obtain similar conclusions, but the reaction effect is poorer than that of the self-made porous carbon carrier in the examples of the present application.

[0081] The content described in the specification is only a list of implementation forms of the inventive concept, and the protection scope of the present application should not be regarded as being limited to the specific forms stated in the examples.

Claims

1. A ligand-modified Pd / C catalyst characterized in that The catalyst comprises a porous carbon carrier, palladium nanoparticles supported on the carrier, and organic ligands coordinated on the surface of the catalyst, the mass of the palladium nanoparticles is 0.5-2% of the mass of the porous carbon carrier, and the organic ligands are selected from oxanilides, and the molar ratio of the organic ligands to palladium is 1-8:

1.

2. The ligand-modified Pd / C catalyst of claim 1, wherein The mass of the palladium nanoparticles is 0.8-1.2% of the mass of the porous carbon carrier, and the molar ratio of the organic ligands to palladium is 2-3:

1.

3. The ligand-modified Pd / C catalyst as described in claim 1, characterized in that... The preparation method of the porous carbon carrier comprises the following steps: uniformly mixing cellulose and ammonium bicarbonate in a mortar according to a mass ratio of 1:0.8-1.2, then calcining at 700-900 DEG C for 1-3 hours under an argon atmosphere, cooling to room temperature, and washing and drying the obtained black powder to obtain the porous carbon.

4. The method for preparing a ligand-modified Pd / C catalyst as described in claim 1, characterized in that... The preparation method comprises the following steps: adding the organic ligands to anhydrous ethanol, uniformly stirring, then adding a palladium precursor solution, stirring overnight at room temperature, then adding the porous carbon carrier, dispersing the porous carbon carrier in anhydrous ethanol at a concentration of 5-30 g / L, transferring the mixture to an oil bath heating environment at 70-90 DEG C, and continuing to stir until the anhydrous ethanol is completely evaporated, and reducing the obtained black powder at 180-250 DEG C under a hydrogen atmosphere for 1-3 hours to obtain the catalyst.

5. The method for preparing a ligand-modified Pd / C catalyst as described in claim 4, characterized in that... The palladium precursor is Pd(NO3)2, PdCl2 or K2PdCl4, and the mass of Pd in the palladium precursor is 0.5-2% of the mass of the porous carbon carrier.

6. A method of preparing a ligand-modified Pd / C catalyst according to claim 5, wherein The palladium precursor is Pd(NO3)2, and the mass of Pd in the palladium precursor is 0.8-1.2% of the mass of the porous carbon carrier.

7. The application of the ligand-modified Pd / C catalyst in catalyzing the selective hydrogenation of nitrogen-containing alkynes.

8. Use according to claim 7, wherein The nitrogen-containing alkyne is mixed with a solvent, and then the reaction solution is subjected to selective hydrogenation under the action of the ligand-modified Pd / C catalyst under a hydrogen atmosphere to generate a nitrogen-containing alkene, wherein the hydrogenation temperature is 0-100 DEG C, the hydrogen pressure is 0.1-4 MPa, and the solvent is water, ethanol, dichloromethane, tetrahydrofuran or n-hexane.

9. Use according to claim 8, wherein The mass of the catalyst is 1-10% of the mass of the nitrogen-containing alkyne, the selective hydrogenation temperature is 25-40 DEG C, the hydrogen pressure is 0.1-0.5 MPa, and the solvent is ethanol.

10. Use according to claim 9, wherein The mass of the catalyst is 2-5% of the mass of the nitrogen-containing alkyne.

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