A catalyst for the selective hydrogenation of quinoline and its preparation method

Abstract

The present invention discloses a catalyst for catalytic selective hydrogenation of quinoline. It also discloses a preparation method of a catalyst for catalytic selective hydrogenation of quinoline, which includes the following steps: S1, weighing nickel salt, copper salt, fluoride salt and alumina, putting them into deionized water to obtain a uniform mixed solution; S2, transferring the mixed solution to a hydrothermal reactor for hydrothermal reaction, filtering, washing and drying to obtain a massive blue-green solid; S3, grinding the massive blue-green solid into powder, first calcining in a nitrogen atmosphere and then reducing in a hydrogen atmosphere to obtain the catalyst. It also discloses an application of a catalyst for catalytic selective hydrogenation of quinoline, which is used for catalytic selective hydrogenation of quinoline and quinoline derivatives. The catalyst of the present invention has strong stability, a simple preparation process, relatively low cost of non-precious metals, and is easy to recycle, with a wide range of substrate applicability. It has good catalytic hydrogenation performance in the quinoline hydrogenation reaction and has important industrial value.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a catalyst for catalytic selective hydrogenation of quinoline and a preparation method thereof. Background Art

[0002] The products of quinoline hydrogenation have many uses in the synthesis of biomedicines and are also important raw materials for many important biomedicines. The demand for 1,2,3,4-tetrahydroquinoline has been gradually increasing. In recent years, heterogeneous catalysts based on Au, Pd, Pt, Ru, Ir, Rh, especially heterogeneous catalysts with noble metals as carriers, have attracted more and more attention. In the quinoline hydrogenation reaction, the N-heterocycle is prone to coordinate with metal nanoparticles, making it difficult to recycle the catalyst. Most importantly, noble metals are expensive and difficult to be applied in large-scale industries. Therefore, the development of non-noble metal catalysts has become an urgent task.

[0003] Tetrahydroquinoline (THQ) plays a key role in the synthesis of dyes and drugs and is also widely used as fine chemicals such as analytical reagents, corrosion inhibitors, and agrochemicals. There are various methods for the synthesis of 1,2,3,4-tetrahydroquinoline, such as catalytic cyclization, Beckmann rearrangement, and quinoline hydrogenation. Due to the convenience of quinoline hydrogenation and its high atom utilization rate, it is currently the most effective and promising method. The hydrogenation products of quinoline generally include three types: THQ, 5,6,7,8-tetrahydroquinoline (bz-THQ), and decahydroquinoline (DHQ). Therefore, the selective hydrogenation of the quinoline pyridine ring is still a great challenge.

[0004] In the reported quinoline hydrogenation reactions, the commonly used hydrogenation source is hydrogen. When hydrogen is used for hydrogenation, the most commonly used are highly active noble metal Pt-based, Ru-based, and non-noble metal Co-based, Ni-based, etc. There are also some other non-metal catalysts, such as nitrogen-doped carbon, and there are many choices for solvents. However, this catalyst system still has problems such as the long reaction time (48 h) required for hydrogenation under high pressure (5 Mpa H2) and high catalyst loading (20 mol%).

[0005] The preparation process of partial quinoline hydrogenation catalysts is complex and the operating conditions are harsh. For example, in the "One-Step High-Temperature-Synthesized Single-Atom Platinum Catalyst for Efficient Selective Hydrogenation" published by Qingyuan Bi, Xiaotao Yuan, etc. in Research Article in 2020, MoC and the active ingredient Pt atoms were synthesized at ultra-high temperature (over 4000 °C) using high-temperature arc power generation. The reaction temperature was 150 °C, the reaction time was 10 h, and the hydrogen pressure was 2 Mpa. The preparation conditions are harsh, the reaction conditions are relatively high, and due to the use of Pt metal as the active ingredient, the cost is also high.

[0006] Patent document CN202310542921.X discloses a copper-based bimetallic electrocatalytic hydrogenation of quinoline. Its reaction device uses an H-type electrolytic cell, which requires an alkaline solution as the anolyte, a Pt sheet as the anode, a copper-based bimetallic catalyst as the cathode, and the catholyte is an alkaline solution containing quinoline and 1,4-dioxane. The reaction conditions are complex, and the alkaline solution will cause maintenance costs due to the electrochemical corrosion of the device. Moreover, the preparation process is lengthy and not conducive to large-scale industrial use.

[0007] In order to overcome the above disadvantages, there is an urgent need to develop an efficient, stable, reusable, and low-loading non-noble metal catalytic system. Summary of the Invention

[0008] The purpose of the present invention is to provide a catalyst for catalytic selective hydrogenation of quinoline and its preparation method to solve the problems in the background technology that the preparation method of the current catalyst for selective hydrogenation of quinoline to prepare 1,2,3,4-tetrahydroquinoline has complex reaction conditions, a lengthy preparation process, and is not conducive to large-scale industrial use.

[0009] To achieve the above purpose, the present invention provides a catalyst for catalytic selective hydrogenation of quinoline. Using two-dimensional sheet-structured alumina as the carrier, nickel-copper bimetal is uniformly dispersed on the surface of the alumina carrier, and F is used as a doping element to improve the interaction between the carrier and the active component. The two-dimensional sheet-structured alumina is obtained by etching and modification with F element.

[0010] In a specific embodiment, the form of the active component is that copper atoms are embedded in nickel nanoparticles, and the mass of the embedded copper atoms is less than the mass of the nickel nanoparticles.

[0011] The present invention also provides a preparation method of a catalyst for catalytic selective hydrogenation of quinoline, including the following steps:

[0012] S1. Weigh nickel salt, copper salt, fluoride salt and aluminum oxide, put them into deionized water, and disperse them uniformly by stirring and ultrasonic treatment to obtain a uniform mixed solution; the aluminum oxide is ground and washed with ethanol before weighing;

[0013] S2, transfer the uniform mixed solution in S1 to a hydrothermal kettle, and then place the hydrothermal kettle in an oven at 100°C for hydrothermal reaction, and filter to obtain a solid after cooling, and then wash it with deionized water, and then dry it to obtain a blocky blue-green solid;

[0014] S3. Grind the blue-green solid block obtained in S2 into powder, then calcine it at a certain temperature in a nitrogen atmosphere for a period of time, and then reduce it at a certain temperature in a hydrogen atmosphere to finally obtain a catalyst.

[0015] In a specific embodiment, the nickel salt is one or more of nickel nitrate, nickel chloride, and nickel acetate; the copper salt is one or more of copper nitrate, copper chloride, and copper acetate; the molar ratio of nickel to copper is 10:0.5-3; the fluoride salt is one or more of ammonium fluoride, sodium fluoride, and potassium fluoride; the mass ratio of fluoride salt to aluminum oxide is 1:4-6.

[0016] In a specific embodiment, in step S1, in the sum of the weighed nickel salt, copper salt, fluoride salt and aluminum oxide, the mass fraction of nickel is 10wt%, the mass fraction of copper is 1wt%, and the mass fraction of fluorine is 20wt%.

[0017] In a specific embodiment, in step S2, the hydrothermal reaction time is 8 to 12 hours, the drying conditions are 80 to 120° C., and the drying time is 8 to 12 hours.

[0018] In a specific embodiment, in the step S3, the calcination conditions are: calcination temperature 300-500°C, calcination time 3-5h; in the step S3, the reduction conditions are: reduction temperature 300-500°C, reduction time 1-2h.

[0019] The present invention also provides an application of a catalyst for catalyzing the selective hydrogenation of quinoline. The catalyst is a catalyst prepared by the above-mentioned preparation method and is used for catalyzing the selective hydrogenation of quinoline and quinoline derivatives.

[0020] In a specific embodiment, the quinoline derivatives include 8-chloroquinoline, 8-fluoroquinoline, 8-methylquinoline, 8-bromoquinoline, 8-hydroxyquinoline;

[0021] The applications of the catalyst for catalytic selective hydrogenation of quinoline include: being used for catalytic selective hydrogenation of quinoline to prepare 1,2,3,4-tetrahydroquinoline; being used for catalytic selective hydrogenation of 8-chloroquinoline to prepare 8-chloro-1,2,3,4-tetrahydroquinoline; being used for catalytic selective hydrogenation of 8-fluoroquinoline to prepare 8-fluoro-1,2,3,4-tetrahydroquinoline; being used for catalytic selective hydrogenation of 8-methylquinoline to prepare 8-methyl-1,2,3,4-tetrahydroquinoline; being used for catalytic selective hydrogenation of 8-bromoquinoline to prepare 8-bromo-1,2,3,4-tetrahydroquinoline; being used for catalytic selective hydrogenation of 8-hydroxyquinoline to prepare 8-hydroxy-1,2,3,4-tetrahydroquinoline.

[0022] In a specific embodiment, the conditions for catalytic selective hydrogenation of quinoline are as follows: adding a catalyst, a solvent, and quinoline into a reaction kettle and introducing hydrogen at a certain pressure, the reaction temperature is 80 - 130 °C, the reaction time is 4 - 12 h, the H2 pressure is 0.5 - 3 Mpa, and the solvent is one or more of toluene, methanol, isopropanol, and acetonitrile.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In the present invention, through the hydrothermal method using the fluorination of ammonium fluoride, on the one hand, fluorine is used to etch the carrier to form a hollow mesoporous structure, which can better load nickel-copper bimetallic nanoparticles and improve the catalytic efficiency of the catalyst. On the other hand, fluorine is doped into the alumina carrier to enhance the interaction between the carrier and the nanoparticles and improve the adsorption capacity of nitrogen heterocyclic compounds such as quinoline on the catalyst surface. The fluorine-doped optimization of the catalyst performance in the present invention can achieve the selective hydrogenation of quinoline under mild conditions, and at the same time can better prevent the loss and poisoning of active components and improve the stability of the catalyst. The preparation method of the present invention has low cost and simple process, and has certain industrial value.

[0025] Compared with the existing quinoline hydrogenation catalysts, the catalyst of the present invention uses alumina as the carrier, nickel nitrate as the nickel source, copper nitrate as the copper source, and at the same time ammonium fluoride as the fluorine source to etch the carrier, etch the alumina sphere into a hollow mesoporous spherical shell, and at the same time distribute the active components in the shell. The obtained catalyst has strong stability, simple preparation process, better economic advantages of non-precious metals compared with precious metals, and is easy to recycle, and has a wide substrate application range. It has good catalytic hydrogenation performance in the quinoline hydrogenation reaction, the selectivity of the target product can reach 99%, and the yield is almost close to 100%, which has important industrial value.

[0026] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The present invention will be further described in detail below. Description of the Drawings

[0027] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 is the catalytic performance graph after the catalyst prepared by the present invention is recycled;

[0029] Figure 2 is the XRD graph of nickel-copper bimetallic catalysts with different Cu loadings prepared by the present invention;

[0030] Figure 3 is the XRD graph of the nickel-copper bimetallic catalyst supported on F-doped carrier before and after recycling prepared by the present invention;

[0031] Figure 4 is the BET nitrogen adsorption-desorption isotherm curve of the catalyst prepared by the present invention;

[0032] Figure 5 is the BET pore size distribution graph of the catalyst prepared by the present invention;

[0033] As Figure 4 and Figure 5 shown, for the N2 physical adsorption-desorption curves and pore size distribution curves of different F loadings of the Ni1Cu 0.1 / Al2O3-F catalyst, it can be seen from the figure that all the samples show type III isotherms in the adsorption isotherm, and the hysteresis loops are of type H3 and H4, indicating that all the catalyst structures have mesoporous structures. Further pore size analysis is carried out. As shown in the figure, for the pore size distribution graphs of different samples, it can be seen that the mesopores existing in the Ni1Cu 0.1 / Al2O3-F catalyst are mostly between 2 - 50 nm, indicating that F doping can reduce the pore size.

[0034] Figure 6 is the XPS full spectrum graph of the catalyst prepared by the present invention. From this, it can be seen that all the elemental compositions of the catalyst, whether it is Cu, Ni, F, or O, have clear signal peaks in the figure, indicating that Cu and Ni in the present invention are successfully loaded on the carrier.

[0035] Figures 7 - 9 All are the TEM transmission electron microscope graphs of the catalyst Ni1Cu 0.1 / Al2O3-F prepared by the present invention. From Figure 7 and Figure 8 it can be clearly seen that there are large black particles with clear edges, indicating a flaky structure, and there are few layers around the flaky structure, indicating that the etching of F elements causes the edges of alumina particles to become thinner and form a flaky structure. By Figure 9 measuring the lattice spacing, it can be determined that Ni1Cu0.1 The (200) crystal plane of Ni particles was exposed on the / Al2O3-F catalyst, and the lattice spacing was 0.17 nm.

[0036] Figure 10 It is the catalyst Ni1Cu prepared by the present invention 0.1 TEM transmission electron micrograph of / Al2O3. Through measurement in Figure (d), the Ni(200) particles of Ni1Cu 0.1 / Al2O3 were determined, and the lattice spacing was 0.18 nm.

[0037] Figure 11 It is the TEM line scan diagram of the catalyst prepared by the present invention. It can be seen from the figure that the change trends of the element contents of Cu, Ni, and F are consistent, which also shows that there is a certain connection among the three elements of Cu, Ni, and F, and they are all evenly distributed, which is consistent with the information revealed by the TEM transmission electron micrograph. Specific embodiments

[0038] The following will describe the embodiments of the present invention in detail. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] The present invention provides a catalyst for catalytic selective hydrogenation of quinoline. Using two-dimensional sheet-structured alumina as the carrier, nickel-copper bimetal is uniformly dispersed on the surface of the alumina carrier, and F is used as a doping element to improve the interaction between the carrier and the active component, and the two-dimensional sheet-structured alumina is obtained by etching and modification with F element.

[0040] The existence form of the active component is that copper atoms are embedded in nickel nanoparticles, and the mass of the embedded copper atoms is less than the mass of the nickel nanoparticles.

[0041] The present invention also provides a preparation method of a catalyst for catalytic selective hydrogenation of quinoline, which includes the following steps:

[0042] S1. Weigh nickel salt, copper salt, fluorine salt and alumina, put them into deionized water, and make them uniformly dispersed through stirring and ultrasonic treatment to obtain a uniform mixed solution; the weighed alumina was ground before weighing and washed with ethanol;

[0043] Perform ultrasonic treatment for 0.5 - 1.5 h; the alumina was ground with an agate mortar and washed with ethanol 1 - 2 times.

[0044] The nickel salt is one or more of nickel nitrate, nickel chloride, and nickel acetate, and preferably the nickel salt is nickel nitrate; the copper salt is one or more of copper nitrate, copper chloride, and copper acetate, and preferably the copper salt is copper nitrate; the molar ratio of nickel to copper is 10:0.5 - 3, preferably the molar ratio of nickel to copper is 10:1 - 3, and most preferably the molar ratio of nickel to copper is 10:1; the fluoride salt is one or more of ammonium fluoride, sodium fluoride, and potassium fluoride, and preferably the fluoride salt is ammonium fluoride; the mass ratio of the fluoride salt to alumina is 1:4 - 6.

[0045] In the step S1, in the sum of the weighed nickel salt, copper salt, fluoride salt, and alumina, the mass fraction of nickel is 10 wt%, the mass fraction of copper is 1 wt%, and the mass fraction of fluorine is 20 wt%.

[0046] S2. Transfer the homogeneous mixture in S1 to a hydrothermal autoclave, then place the hydrothermal autoclave in an oven at 100 °C for hydrothermal reaction for 8 - 12 h, then cool it to room temperature. After cooling, filter it to obtain a solid, wash it 1 - 2 times with deionized water, and then dry it to obtain a blocky blue-green solid.

[0047] In the step S2, the drying conditions are 80 - 120 °C and the drying time is 8 - 12 h.

[0048] Preferably, a Buchner funnel is used for suction filtration, and deionized water and ethanol are used alternately for washing.

[0049] S3. Place the blocky blue-green solid obtained in S2 in an agate mortar and grind it into a powder. The ground solid is placed in a ceramic boat and calcined at a high temperature in a muffle furnace. Then, it is first calcined in a nitrogen atmosphere at a certain temperature for a period of time, and then reduced in a hydrogen atmosphere at a certain temperature. Finally, a catalyst is obtained.

[0050] In the step S3, the calcination conditions are: the calcination temperature is 250 - 500 °C and the calcination time is 3 - 5 h; in the step S3, the reduction conditions are: the reduction temperature is 300 - 500 °C and the reduction time is 1 - 2 h.

[0051] The present invention also provides an application of a catalyst for catalytic selective hydrogenation of quinoline. The catalyst is the catalyst prepared by the preparation method as described above, and is used for catalytic selective hydrogenation of quinoline and quinoline derivatives to prepare 1,2,3,4-tetrahydroquinoline and its corresponding derivatives.

[0052] Quinoline derivatives include 8-chloroquinoline, 8-fluoroquinoline, 8-methylquinoline, 8-bromoquinoline, and 8-hydroxyquinoline. The applications of the catalyst for the selective hydrogenation of quinoline include: being used for catalyzing the selective hydrogenation of quinoline to prepare 1,2,3,4-tetrahydroquinoline; being used for catalyzing the selective hydrogenation of 8-chloroquinoline to prepare 8-chloro-1,2,3,4-tetrahydroquinoline; being used for catalyzing the selective hydrogenation of 8-fluoroquinoline to prepare 8-fluoro-1,2,3,4-tetrahydroquinoline; being used for catalyzing the selective hydrogenation of 8-methylquinoline to prepare 8-methyl-1,2,3,4-tetrahydroquinoline; being used for catalyzing the selective hydrogenation of 8-bromoquinoline to prepare 8-bromo-1,2,3,4-tetrahydroquinoline; being used for catalyzing the selective hydrogenation of 8-hydroxyquinoline to prepare 8-hydroxy-1,2,3,4-tetrahydroquinoline.

[0053] The conditions for the selective hydrogenation of quinoline catalyzed are: adding a catalyst, a solvent, and quinoline into a reaction kettle and introducing hydrogen at a certain pressure, the reaction temperature is 80 - 130 °C, preferably the reaction temperature is 90 - 120 °C, the reaction time is 4 - 12 h, preferably 6 h, the H2 pressure is 0.5 - 3 Mpa, preferably the H2 pressure is 2 Mpa, and the solvent is one or more of toluene, methanol, isopropanol, and acetonitrile, preferably the solvent is toluene or methanol.

[0054] Example 1

[0055] 1. Weigh 0.56 g of nickel nitrate hexahydrate, 0.05 g of copper nitrate trihydrate, 0.4 g of ammonium fluoride, and 1.0 g of the carrier, and disperse them completely in 15 mL of deionized water. After stirring, perform ultrasonic treatment for 0.5 h to completely dissolve the metal salts, where the nickel loading is 10%, the copper loading is 1%, and the fluorine loading is 20%. After ultrasonic treatment, transfer the liquid to a hydrothermal reaction kettle and carry out hydrothermal reaction in an oven at 100 °C for 8 h. After the reaction is completed, cool it to room temperature and then dry it overnight in an oven at 100 °C. Take it out the next day, cool it, and transfer it to a muffle furnace tube. First, under a nitrogen atmosphere, heat it up to 400 °C at a rate of 5 °C / min, calcine it at 400 °C for 3 h, then introduce hydrogen, and under a hydrogen atmosphere, reduce it at 400 °C for 1 h. After cooling, collect the black powder solid in a ceramic boat. Name it Ni1Cu 0.1 / Al2O3 - F400.

[0056] 2. Add 0.05 mmol of quinoline and 50 mg of Ni1Cu successively into a high-temperature magnetic stirring kettle 0.1 / Al2O3-F400 catalyst, 15 mL of methanol, set the reaction time to 6 h, the temperature to 100 °C, after gas washing, introduce 2 Mpa of hydrogen. The reaction liquid needs to be filtered before gas chromatography analysis. First, use a disposable syringe to extract 1 - 2 mL, then filter with an organic filter head. The filtered reaction liquid is measured by gas chromatography, and a hydrogen flame detector FID is used for detection. The peak area ratio is obtained from the gas chromatogram and calculated by the internal standard method. The internal standard substance is dodecane. The calculated quinoline conversion rate is 100%, and the selectivities and yields of 1,2,3,4-tetrahydroquinoline are 99% and 99% respectively. The reaction evaluation results are shown in Table 1.

[0057] Example 2

[0058] 1. Under a nitrogen atmosphere, heat to 450 °C at a rate of 5 °C / min and calcine at 450 °C. First, calcine in a nitrogen atmosphere for 3 h, and then reduce in a hydrogen atmosphere for 1 h. Other conditions are the same as those in the steps of Example 1. The catalyst obtained by calcination is named Ni1Cu 0.1 / Al2O3-F450.

[0059] 2. Add Ni1Cu 0.1 / Al2O3-F450 catalyst. Other conditions and steps are the same as those in Example 1. The quinoline conversion rate is 81.60%, and the selectivities and yields are 99% and 80.78% respectively. The reaction evaluation results are shown in Table 1.

[0060] Example 3

[0061] 1. Under a nitrogen atmosphere, heat to 350 °C at a rate of 5 °C / min and calcine at 350 °C. First, calcine in a nitrogen atmosphere for 3 h, and then reduce in a hydrogen atmosphere for 1 h. Other conditions are the same as those in the steps of Example 1. The catalyst obtained by calcination is named Ni1Cu 0.1 / Al2O3-F350.

[0062] 2. Add Ni1Cu 0.1 / Al2O3-F350 catalyst. Other conditions and steps are the same as those in Example 1. The quinoline conversion rate is 96.16%, and the selectivities and yields are 99% and 95.19% respectively. The reaction evaluation results are shown in Table 1.

[0063] Example 4

[0064] 1. Under a nitrogen atmosphere, heat to 300 °C at a rate of 5 °C / min and calcine at 300 °C. First, calcine in a nitrogen atmosphere for 3 h, and then reduce in a hydrogen atmosphere for 1 h. Other conditions are the same as those in the steps of Example 1. The catalyst obtained by calcination is named Ni1Cu 0.1 / Al2O3-F300.

[0065] 2. Add Ni1Cu 0.1 / Al2O3-F300 catalyst. Other conditions and steps are the same as in Example 1. The conversion rate of quinoline is 67.38%, and the selectivity and yield are 82.54% and 55.62% respectively. The reaction evaluation results are shown in Table 1.

[0066] Example 5

[0067] 1. Under a nitrogen atmosphere, heat to 500 °C at a rate of 5 °C / min and calcine at 500 °C. First, calcine in a nitrogen atmosphere for 3 h, and then reduce in a hydrogen atmosphere for 1 h. Other conditions are the same as the steps in Example 1. The catalyst obtained by calcination is named Ni1Cu 0.1 / Al2O3-F500.

[0068] 2. Add Ni1Cu 0.1 / Al2O3-F500 catalyst. Other conditions and steps are the same as in Example 1. The conversion rate of quinoline is 28.91%, and the selectivity and yield are 70.69% and 20.44% respectively. The reaction evaluation results are shown in Table 1.

[0069] Table 1

[0070] Example Catalyst Conversion rate % Selectivity % Yield % Example 1 <![CDATA[Ni1Cu 0.1 / Al2O3-F400]]> 100 99 99 Example 2 <![CDATA[Ni1Cu 0.1 / Al2O3-F350]]> 96.16 99 95.20 Example 3 <![CDATA[Ni1Cu 0.1 / Al2O3-F450]]> 81.60 99 80.78 Example 4 <![CDATA[Ni1Cu 0.1 / Al2O3-F300]]> 67.38 82.54 55.62 Example 5 <![CDATA[Ni1Cu 0.1 / Al2O3-F500]]> 28.91 70.69 20.44

[0071] From the comparison results of Examples 1 to 5, it can be known that among the calcination temperature conditions for catalyst preparation, 400 °C is the optimal preparation temperature. Increasing or decreasing the calcination temperature will have more or less negative impacts on the catalytic efficiency, and the conversion rate will decrease. When the calcination temperature is too high, as in Example 5, reaching 500 °C, the catalytic efficiency decreases significantly, and the yield decreases from 99% in Example 1 to 20.44%. It is speculated that this may be because too high a calcination temperature will cause the collapse of the mesoporous structure in the catalyst, resulting in a decrease in catalytic efficiency. However, when the calcination temperature is too low, as in Example 4, the catalytic efficiency fails to reach the high performance of Example 1. It is speculated that this may be because the calcination temperature and environment are too mild, and the active components are not evenly distributed on the carrier. It is concluded that the more preferred calcination temperature is 350 - 450 °C, 400 °C is the optimal calcination temperature, and the subsequent examples will all use 400 °C as the calcination temperature.

[0072] Example 6

[0073] 1. Change the amount of copper nitrate in step 1 of Example 1 to 0.03 g, and the molar ratio of nickel to copper is 10:0.5. Other steps are the same as in Example 1. Heat to 400 °C. First, calcine in a nitrogen atmosphere for 3 h, and then reduce in a hydrogen atmosphere for 1 h. The catalyst obtained by calcination is a black-green powdery catalyst, named Ni1Cu 0.05 / Al2O3-F.

[0074] 2. Add Ni1Cu 0.05 / Al2O3-F catalyst. Keep other conditions and steps the same as in Example 1. The conversion rate of quinoline is 89.42%, the selectivity and yield are 99% and 88.52% respectively. The reaction evaluation results are shown in Table 2.

[0075] Example 7

[0076] 1. Change the dosage of copper nitrate in step 1 of Example 1 to 0.1 g, and the molar ratio of nickel to copper is 10:2. Keep other steps the same as in Example 1. Heat up to 400 °C. First, calcine in a nitrogen atmosphere for 3 h, then reduce in a hydrogen atmosphere for 1 h. The calcined black powdery catalyst is named Ni1Cu 0.2 / Al2O3-F.

[0077] 2. Add Ni1Cu 0.2 / Al2O3-F catalyst. Keep other conditions and steps the same as in Example 1. The conversion rate of quinoline is 100%, the selectivity and yield are 99% and 99% respectively. The reaction evaluation results are shown in Table 2.

[0078] Control Example 1

[0079] 1. Change the dosage of copper nitrate trihydrate in Example 1 to 0 g, that is, do not add copper nitrate. Weigh 0.56 g of nickel nitrate hexahydrate, 0.4 g of ammonium fluoride, and 1.0 g of the carrier and disperse them fully in 15 mL of deionized water. Keep other steps the same as in Example 1. Heat up to 400 °C. First, calcine in a nitrogen atmosphere for 3 h, then reduce in a hydrogen atmosphere for 1 h. The calcined black powdery catalyst is named Ni1 / Al2O3-F400.

[0080] 2. Add Ni1 / Al2O3-F400 catalyst. Keep other conditions and steps the same as in Example 1. The conversion rate of quinoline is 60.94%, the selectivity and yield are 99% and 60.33% respectively. The reaction evaluation results are shown in Table 2.

[0081] Control Example 2

[0082] 1. In Example 1, change the dosage of ammonium fluoride to 0 g, that is, do not use ammonium fluoride for fluorination. Weigh 0.56 g of nickel nitrate hexahydrate, 0.05 g of copper nitrate trihydrate, and 1.0 g of the carrier and disperse them completely in 15 mL of deionized water. Keep other steps the same as in step 1 of Example 1. First, heat up to 400 °C at a rate of 5 °C / min in a nitrogen atmosphere, calcine at 400 °C for 3 h, then pass hydrogen, and reduce at 400 °C for 1 h in a hydrogen atmosphere. After cooling, collect the black powdery solid in the ceramic boat. Name it Ni1Cu 0.1 / Al2O3 - F0%. And so on, when the dosage of ammonium fluoride is 0.06 g, 0.1 g, 0.2 g, 0.3 g, they are respectively named Ni1Cu 0.1 / Al2O3 - F3%, Ni1Cu 0.1 / Al2O3 - F5%, Ni1Cu 0.1 / Al2O3 - F10%, Ni1Cu 0.1 / Al2O3 - F20%.

[0083] 2. Add Ni1Cu 0.1 / Al2O3 - F0% catalyst. Other conditions and steps are the same as those in Example 1. The conversion rate of quinoline is 11.93%, and the selectivity and yield are 99% and 11.81% respectively. The reaction evaluation results are shown in Table 2.

[0084] Table 2

[0085] Example Catalyst Conversion rate % Selectivity % Yield % Example 1 <![CDATA[Ni1Cu 0.1 / Al2O3-F400]]> 100 99 99 Example 6 <![CDATA[Ni1Cu 0.05 / Al2O3-F]]> 89.42 99 88.52 Example 7 <![CDATA[Ni1Cu 0.2 / Al2O3-F]]> 100 99 99 Control Example 1 <![CDATA[Ni1 / Al2O3-F400]]> 60.94 99 60.33 Control Example 2 <![CDATA[Ni1Cu 0.1 / Al2O3-F0%]]> 11.93 99 11.81

[0086] It can be seen from Example 1, Example 6, Example 7 and Comparative Example 1 that although the copper loading is small, it has an important impact on the catalytic performance. Especially from Comparative Example 1 and Example 1, it can be seen that when copper nitrate is not used, the catalytic effect of the nickel - copper bimetallic catalyst is nearly 60% higher than that of the single - nickel catalyst. When a trace amount of copper nitrate is added, as seen in Example 6, there is also an improvement of about 40%. When the dosage of copper nitrate further increases to 0.1 g, as seen in Example 7, there is no impact. It can be seen that excessive copper may not be successfully loaded onto the carrier. However, in order to reduce the emission of metal salts, the optimal dosage of copper nitrate is 0.05 g.

[0087] At the same time, it can be known from Example 1 and Comparative Example 2 about the important role of F in the catalyst preparation. In Comparative Example 2, ammonium fluoride was not added, that is, the carrier was not fluorinated with ammonium fluoride. Judging from the final results, the addition of ammonium fluoride has brought a qualitative leap in the catalytic performance of the catalyst, with the conversion rate increasing by nearly 50%. In subsequent examples, ammonium fluoride is uniformly added, and the dosage of ammonium fluoride is 0.4 g.

[0088] Example 8

[0089] 1. The same as step 1 of Example 1.

[0090] 2. Change 15 mL of methanol as the solvent to 15 mL of isopropanol. Other conditions are the same as those in step 2 of Example 1. The conversion rate of quinoline is 59.46%, and the selectivity and yield of 1,2,3,4 - tetrahydroquinoline are 79.52% and 47.28% respectively. The reaction evaluation results are shown in Table 3.

[0091] Example 9

[0092] 1. The same as step 1 of Example 1.

[0093] 2. Change 15 mL of isopropanol, the solvent in Example 8, to 15 mL of acetonitrile. Other conditions and steps are the same as in Example 8. After gas chromatography and calculation, the conversion rate of quinoline is 46.17%, and the selectivity and yield of the target product are 99% and 45.71% respectively. The reaction evaluation results are shown in Table 3.

[0094] Example 10

[0095] 1. The same as step 1 of Example 1.

[0096] 2. Change the solvent in Example 9 from acetonitrile to toluene, and the dosage is still 15 mL. Other steps and conditions are the same as in Example 1. Finally, the conversion rate of quinoline is 90.85%, and the selectivity and yield are 99% and 89.94% respectively. The reaction evaluation results are shown in Table 3.

[0097] Table 3

[0098] Example Solvent Conversion rate % Selectivity % Yield % Example 1 Methanol 100 99 99 Example 8 Isopropanol 59.46 79.52 47.28 Example 8 Acetonitrile 46.17 99 45.71 Example 10 Toluene 90.85 99 89.94

[0099] Table 3 shows the effects of different solvents on the catalytic performance in Example 1 and Examples 8 - 10. Further, the solvent is one or more of methanol, isopropanol, acetonitrile, water, and toluene.

[0100] Among them, the reaction conditions are: P(H2) = 2 MPa, T = 100 °C, t = 6 h, M(cat) = 50 mg, M(THQ) = 0.05 - 0.06 g, and the internal standard is dodecane. It can be seen from Table 3 that when methanol is the solvent, the performance of the catalyst can be best exerted, and toluene is second only to methanol.

[0101] Example 11

[0102] 1. The same as step 1 of Example 1.

[0103] 2. Change the substrate in Example 1 from quinoline to 8 - chloroquinoline, and the dosage is 0.06 g. Other steps and conditions are the same as in Example 1, but the reaction temperature is changed to 120 °C. Finally, the conversion rate of 8 - chloroquinoline is 100%, and the selectivity and yield of 8 - chloro - 1,2,3,4 - tetrahydroquinoline are 99% and 99% respectively. The reaction evaluation results are shown in Table 4.

[0104] Example 12

[0105] 1. The same as step 1 of Example 1.

[0106] 2. Change the substrate in Example 1 from quinoline to 8-fluoroquinoline, with a dosage of 0.06 g, and keep other steps and conditions the same as in Example 1. Finally, the conversion rate of 8-fluoroquinoline is 100%, and the selectivity and yield of 8-fluoro-1,2,3,4-tetrahydroquinoline are 99% and 99% respectively. The reaction evaluation results are shown in Table 4.

[0107] Example 13

[0108] 1. The same as step 1 in Example 1.

[0109] 2. Change the substrate in Example 1 from quinoline to 8-methylquinoline, with a dosage of 0.06 g, and keep other steps and conditions the same as in Example 1. Finally, the conversion rate of 8-methylquinoline is 100%, and the selectivity and yield of 8-methyl-1,2,3,4-tetrahydroquinoline are 99% and 99% respectively. The reaction evaluation results are shown in Table 4.

[0110] Example 14

[0111] 1. The same as step 1 in Example 1.

[0112] 2. Change the substrate in Example 1 from quinoline to 8-bromoquinoline, with a dosage of 0.06 g, and keep other steps and conditions the same as in Example 1. Finally, the conversion rate of 8-bromoquinoline is 100%, and the selectivity and yield of 8-bromo-1,2,3,4-tetrahydroquinoline are 99% and 99% respectively. The reaction evaluation results are shown in Table 4.

[0113] Example 15

[0114] 1. The same as step 1 in Example 1.

[0115] 2. Change the substrate in Example 1 from quinoline to 8-hydroxyquinoline, with a dosage of 0.06 g, and keep other steps and conditions the same as in Example 1. Finally, the conversion rate of 8-hydroxyquinoline is 45.17%, and the selectivity and yield of 8-hydroxy-1,2,3,4-tetrahydroquinoline are 99% and 44.72% respectively. The reaction evaluation results are shown in Table 4.

[0116] Table 4

[0117] Example Substrate Conversion rate % Selectivity % Yield % Example 1 Quinoline 100 99 99 Example 11 8 - Chloroquinoline 100 99 99 Example 12 8 - Fluoroquinoline 100 99 99 Example 13 8 - Methylquinoline 100 99 99 Example 14 8 - Bromoquinoline 100 99 99 Example 15 8 - Hydroxyquinoline 45.17 99 44.72

[0118] The catalysts used in the reactions are all Ni1Cu 0.1 / Al2O3-F400. Using quinoline with different substituents as substrates, the substrate scope of the selective hydrogenation of this catalyst was studied. The substituents were halogen elements (F, Cl, Br), methyl group, hydroxyl group, etc. It can be known from the expansion of various substrates in Table 4 that this catalyst also has good catalytic efficiency for other quinoline compounds. For some electron-donating groups, such as hydroxyl group, see Example 15. The catalyst of the present invention has a worse catalytic effect on quinoline compounds substituted by hydroxyl group than quinoline compounds substituted by some electron-withdrawing groups. See Examples 11 to 14. It can be seen that electron-withdrawing groups have different degrees of promotion effects on the hydrogenation reaction. It can be seen that the catalyst prepared by the present invention has wide applicability.

[0119] Example 16

[0120] 1. The same as step 1 of Example 1.

[0121] 2. The steps are the same as those of Example 1, and the catalyst is recovered after the reaction. The specific recovery method is as follows: transfer the reaction solution to a centrifuge tube, the rotation speed / centrifugal force = 8000, the centrifugation time is 2 min, pour the supernatant into the waste liquid bucket, take the precipitated solid, wash it with ethanol 2 to 3 times, and dry it in an oven at 100 °C for 8 - 12 h. The next day, add the recycled catalyst to the reaction kettle, and the other steps are the same as those of Example 1. The conversion rate and selectivity are calculated by internal standard in gas chromatography, and the conversion rate and selectivity are 100% and 99% respectively, which is recorded as cycle number 1. Repeat the above steps repeatedly to recycle the catalyst, and recycle it ten times in total. The catalytic analysis results are as Figure 1 shown.

[0122] From Figure 1 it can be seen that after ten cycles, both the conversion rate and the selectivity are at a very high level, indicating that the hollow mesoporous structure formed by the fluorination etching of the present invention has great stability, which can be proved in the XRD pattern. See Figure 3 that there is not much change in the crystal structure of the catalyst. The hollow mesoporous structure can prevent the loss of active components, so high conversion rate and high selectivity can still be achieved after multiple cycles, which can save huge costs in industry and also reflects the value of the present invention.

[0123] In the present invention, the room temperature is set at 25 °C ± 5 °C.

[0124] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A catalyst for selectively hydrogenating quinoline, characterized in that, Using alumina with a two-dimensional sheet structure as the carrier, nickel-copper bimetal is uniformly dispersed on the surface of the alumina carrier as the active component. F is used as a doping element to improve the interaction between the carrier and the active component, and the alumina with a two-dimensional sheet structure is obtained by etching and modification with F element.

2. The catalyst for catalytic selective hydrogenation of quinoline according to claim 1, wherein The active component exists in the form that copper atoms are embedded in nickel nanoparticles, and the mass of the embedded copper atoms is less than that of the nickel nanoparticles.

3. A preparation method of a catalyst for selective hydrogenation of quinoline, characterized in that, It includes the following steps: S1. Weigh nickel salt, copper salt, fluoride salt and alumina, put them into deionized water, and make them uniformly dispersed through stirring and ultrasonic treatment to obtain a uniform mixture; the weighed alumina was ground and washed with ethanol before weighing. S2. Transfer the uniform mixture in S1 to a hydrothermal reactor, place the hydrothermal reactor in an oven at 100 °C for hydrothermal reaction. After cooling, filter to obtain a solid, wash it with deionized water, and then dry it to obtain a massive blue-green solid. S3. Grind the massive blue-green solid obtained in S2 into a powder, then first calcine it in a nitrogen atmosphere at a certain temperature for a period of time, and then reduce it in a hydrogen atmosphere at a certain temperature. Finally, a catalyst is obtained.

4. The preparation method of the catalyst for catalytic selective hydrogenation of quinoline according to claim 3, characterized in that, The nickel salt is one or more of nickel nitrate, nickel chloride, nickel acetate; the copper salt is one or more of copper nitrate, copper chloride, copper acetate; the molar ratio of nickel to copper is 10:0.5 - 3; the fluoride salt is one or more of ammonium fluoride, sodium fluoride, potassium fluoride; the mass ratio of the fluoride salt to alumina is 1:4 - 6.

5. The preparation method of the catalyst for selectively hydrogenating quinoline according to claim 4, characterized in that, In step S1, in the total of the weighed nickel salt, copper salt, fluoride salt and alumina, the mass fraction of nickel is 10 wt%, the mass fraction of copper is 1 wt%, and the mass fraction of fluorine is 20 wt%.

6. The preparation method of the catalyst for selectively hydrogenating quinoline according to claim 3, characterized in that, In step S2, the hydrothermal reaction time is 8 - 12 h, the drying condition is 80 - 120 °C, and the drying time is 8 - 12 h.

7. The preparation method of the catalyst for selectively hydrogenating quinoline according to claim 3, characterized in that, In step S3, the calcination conditions are: the calcination temperature is 300 - 500 °C, and the calcination time is 3 - 5 h; in step S3, the reduction conditions are: the reduction temperature is 300 - 500 °C, and the reduction time is 1 - 2 h.

8. Use of a catalyst for selective hydrogenation of quinoline, characterized in that, The catalyst is the catalyst prepared by the preparation method described in any one of claims 3 - 7, and is used for catalytic selective hydrogenation of quinoline and quinoline derivatives.

9. Use of the catalyst for selective hydrogenation of quinoline according to claim 8, characterized in that, Quinoline derivatives include 8-chloroquinoline, 8-fluoroquinoline, 8-methylquinoline, 8-bromoquinoline, 8-hydroxyquinoline; The applications of the catalyst for catalytic selective hydrogenation of quinoline include: used for catalytic selective hydrogenation of quinoline to prepare 1,2,3,4-tetrahydroquinoline; used for catalytic selective hydrogenation of 8-chloroquinoline to prepare 8-chloro-1,2,3,4-tetrahydroquinoline; used for catalytic selective hydrogenation of 8-fluoroquinoline to prepare 8-fluoro-1,2,3,4-tetrahydroquinoline; used for catalytic selective hydrogenation of 8-methylquinoline to prepare 8-methyl-1,2,3,4-tetrahydroquinoline; used for catalytic selective hydrogenation of 8-bromoquinoline to prepare 8-bromo-1,2,3,4-tetrahydroquinoline; used for catalytic selective hydrogenation of 8-hydroxyquinoline to prepare 8-hydroxy-1,2,3,4-tetrahydroquinoline.

10. Use of the catalyst for the selective hydrogenation of quinoline according to claim 8, characterized in that, The conditions for catalytic selective hydrogenation of quinoline are as follows: Add a catalyst, a solvent, and quinoline into a reaction kettle, and introduce hydrogen at a certain pressure. The reaction temperature is 80 - 130 °C, the reaction time is 4 - 12 h, the H2 pressure is 0.5 - 3 Mpa, and the solvent is one or more of toluene, methanol, isopropanol, and acetonitrile.

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