Preparation method and application of reductive amination catalyst

Abstract

The invention discloses preparation and application of a reductive amination catalyst. The preparation method of the catalyst comprises the following steps: step 1, preparing an SrTiO3 carrier; step 2, loading a nickel source into the prepared SrTiO3 carrier to form a nickel-loaded SrTiO3 catalyst precursor; and step 3, roasting the SrTiO3 catalyst precursor to obtain the SrTiO3 loaded nickel catalyst. Large-scale production of the non-noble metal catalyst is realized by adopting a co-precipitation method and an impregnation method which are simple in process and environment-friendly under the condition of room temperature, the obtained material can be used for reductive amination reaction of acetophenone under the condition of taking water as a solvent and shows excellent catalytic performance, and after 50 times of application, the acetophenone conversion rate is gt; the selectivity of alpha-phenylethylamine is gt; the selectivity of the alpha-phenethyl alcohol is 1t; and 2%.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a method for preparing a reducing amination catalyst, and to a method for using the catalyst for the reducing amination of acetophenone to prepare α-phenylethylamine. Background Technology

[0002] As an important intermediate in the fine chemical industry, α-phenylethylamine is the basic raw material for preparing single-chiral α-phenylethylamine (a core pharmaceutical intermediate), and it is also used in the synthesis of dyes, fragrances, rubber vulcanization accelerators, and many other fields. Currently, α-phenylethylamine is produced through catalytic reduction of phenylacetonitrile, styrene amination, phenylacetaldehyde amination, and acetophenone amination. The first three methods suffer from drawbacks such as high toxicity of raw materials, poor stability, and cumbersome reaction steps; therefore, the acetophenone amination method is currently the main industrial method used.

[0003] In recent years, research on the conversion of acetophenone into α-phenylethylamine using noble metal catalysts has made some progress. However, the high price, scarcity of resources, and difficulty in large-scale industrial production of noble metal catalysts still restrict the widespread application of this method. Therefore, there is an urgent need to develop a non-noble metal catalyst to achieve the efficient, green, and environmentally friendly conversion of acetophenone into α-phenylethylamine.

[0004] However, in the reductive amination of acetophenone to α-phenylethylamine using existing non-precious metal catalysts, liquid ammonia is often used as the ammonia source, and organic solvents such as methanol and isopropanol are used as solvents. Considering that the reductive amination reaction itself generates water, the use of organic solvents will increase the cost of subsequent separation steps. Replacing the solvent with water can not only reduce the number of subsequent separation steps, but also replace the ammonia source from liquid ammonia to ammonia water, significantly reducing the overall process risk. However, commonly used catalysts such as transition metal alloys (Raney nickel, Raney cobalt) and Ni / Al2O3 catalysts exhibit low selectivity for α-phenylethylamine under water-based solvent conditions and are prone to metal loss and poisoning, thus affecting the catalyst's stability and recyclability.

[0005] Therefore, it is of great significance to develop a novel non-precious metal catalyst that can achieve the efficient and selective conversion of acetophenone to α-phenylethylamine in an aqueous system under long-term and stable conditions. Summary of the Invention

[0006] This invention provides a method for preparing a nickel catalyst supported on a SrTiO3 support, and uses this catalyst for the reductive amination of acetophenone to prepare α-phenylethylamine. This method uses non-precious metal nickel as the active component and SrTiO3 as the support, offering advantages such as low cost, simple preparation, high activity, good selectivity, and high stability. It can efficiently convert acetophenone to α-phenylethylamine, providing a new method for the reductive amination of acetophenone to prepare α-phenylethylamine.

[0007] In a first aspect, the present invention provides a method for preparing a reducing amination catalyst, the method comprising the following steps:

[0008] Step 1: Preparation of SrTiO3 support: SrTiO3 precursor is calcined to obtain SrTiO3 support;

[0009] Step 2: Load the nickel source onto the prepared SrTiO3 support to form a nickel-supported SrTiO3 catalyst precursor;

[0010] Step 3: Calcine the SrTiO3 catalyst precursor to obtain the SrTiO3 supported nickel catalyst (reduction amination catalyst).

[0011] Preferably, the preparation method of the SrTiO3 precursor includes the following steps:

[0012] Step 101: Adjust the pH of the titanium salt solution to 1.5-2, and then slowly add it dropwise into the strontium salt solution to obtain a homogeneous Sr-Ti mixed solution;

[0013] Step 102: Slowly add the precipitant solution dropwise into the Sr-Ti mixed solution to obtain the Sr-Ti mixed precipitate;

[0014] Step 103: The obtained precipitate is aged, then filtered, washed until neutral, and dried to obtain SrTiO3 precursor powder.

[0015] Preferably, in step 101, the strontium salt is a soluble salt of strontium, preferably one or more of strontium chloride, strontium acetate, and strontium nitrate;

[0016] Preferably, in step 101, the titanium salt is a soluble salt of titanium, preferably one or more of titanium tetrachloride, titanium oxyoxalate, titanium oxysulfate, and titanium oxynitrate.

[0017] Preferably, in step 101, the concentration of the titanium salt solution is 100–250 g / L;

[0018] Preferably, the concentration of the strontium salt solution in step 101 is 100–250 g / L;

[0019] Preferably, the pH of the titanium salt solution is adjusted using 5-10% dilute sulfuric acid;

[0020] Preferably, the molar ratio of Sr / Ti in the strontium salt and titanium salt mixed solution is 0.9 to 1.1;

[0021] Preferably, the precipitant in step 102 is a soluble alkaline compound, preferably one or more of ammonium oxalate, ammonia, and ammonium carbonate;

[0022] Preferably, the aging treatment in step 103 is performed by standing at room temperature for 2-8 hours;

[0023] Preferably, step 1, preparing the SrTiO3 support, specifically includes the following steps: calcining the prepared SrTiO3 precursor at high temperature, controlling the calcination temperature and time, to obtain the SrTiO3 support.

[0024] Preferably, in step 1, the SrTiO3 precursor is calcined at a temperature of 400–1000°C, more preferably 700–900°C. The calcination time is 2–10 hours, more preferably 5–8 hours.

[0025] In this invention, in step 2, the nickel source is a soluble salt of nickel, preferably one or more of nickel nitrate, nickel acetate, and nickel acetylacetone, and the loading method can be impregnation or deposition-precipitation, preferably deposition-precipitation.

[0026] The nickel content in the total mass of the catalyst is 5-30%, preferably 10-20%;

[0027] In this invention, the roasting temperature in step 3 is 200-600℃, preferably 300-500℃; the roasting time is 2-10 hours, preferably 4-6 hours.

[0028] Preferably, the calcination atmosphere in step 3 is a reducing atmosphere, preferably one or two of hydrogen, nitrogen, and argon. In a specific embodiment, hydrogen / nitrogen 1:9, hydrogen / argon 1:9, or hydrogen / helium 1:9 can be used.

[0029] In a second aspect, the present invention provides a reductive amination catalyst prepared by the above-described preparation method.

[0030] The third method of the present invention provides the application of the above-mentioned reducing amination catalyst in the method of preparing α-phenylethylamine by reducing amination of acetophenone.

[0031] Specifically, the method for preparing α-phenylethylamine by reductive amination of acetophenone includes the following steps: using acetophenone as a raw material, adding the aforementioned prepared SrTiO3 supported nickel catalyst, using ammonia water as an ammonia source, and carrying out a reductive amination reaction in a solvent to obtain the α-phenylethylamine.

[0032] Preferably, the reaction temperature in this method is 20–170°C, more preferably 90–140°C;

[0033] The mass ratio of acetophenone to catalyst is 1:0.01 to 1:0.5, preferably 1:0.01 to 1:0.1;

[0034] The pressure after ammonia source vaporization is 0.2–4 MPa, preferably 0.5–1.5 MPa;

[0035] The hydrogen pressure is 0.1–2 MPa, preferably 0.1–1.5 MPa;

[0036] The reductive amination reaction takes 2 to 16 hours, preferably 4 to 12 hours.

[0037] Preferably, the mass ratio of raw material to solvent in this method is 1:1 to 1:10, more preferably 1:1 to 1:5;

[0038] The solvent is selected from one or more of water, methanol, ethanol, propanol, isopropanol, n-butanol, tetrahydrofuran, methyltetrahydrofuran, diethyl ether, cyclopentyl methyl ether, and cyclohexyl methyl ether. Preferably, the solvent in this method is water.

[0039] Compared with the prior art, the present invention has the following significant advantages and beneficial effects:

[0040] 1. Using inexpensive and readily available non-precious metal nickel as the active component, the catalyst preparation method is simple and direct, without the need for complicated preparation processes, which helps to reduce production costs and improve preparation efficiency;

[0041] 2. There is a strong metal-support interaction between the prepared SrTiO3 support and the active nickel metal, the active component is tightly bound to the support, and the stability is strong;

[0042] 3. Water is used as a solvent in the reaction process, which reduces the number of subsequent separation steps. At the same time, ammonia water is used instead of liquid ammonia as the ammonia source, which reduces the risk of the reaction.

[0043] 4. The prepared SrTiO3 supported nickel catalyst has excellent catalytic activity and product selectivity, and can efficiently convert acetophenone selectively into high-value-added chemicals such as α-phenylethylamine, significantly improving the yield of the target product. Detailed Implementation

[0044] The present invention will be further described below with reference to embodiments and comparative examples, but the present invention is not limited to the following embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0045] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially.

[0046] Test method:

[0047] This application also provides a method for determining the conversion and yield during the synthesis of α-phenylethylamine, which can be:

[0048] GC analysis was performed on an Agilent 7820 using an HP-5 capillary column and an FID detector. The injector and detector temperatures were both 280°C. The column temperature was programmed: initial temperature 100°C, held for 0.5 minutes, then increased to 260°C at a rate of 15°C / min, and held for 5 minutes.

[0049] Example 1

[0050] A preparation process using SrTiO3-supported nickel as a catalyst includes the following steps:

[0051] Step 1: Preparation of SrTiO3 support material:

[0052] Step 101: Add 24.12g of Sr(NO3)2 to 200mL of deionized water and stir until completely dissolved;

[0053] Step 102: Add 17.85g TiOSO4 to 100mL of deionized water, add 10% dilute sulfuric acid dropwise, adjust the pH to 1.5-2.0, and stir until completely dissolved;

[0054] Step 103: Add the solution obtained in step 102 dropwise to the solution obtained in step 101 at a rate of 1 to 2 drops / second, and continue stirring to obtain a homogeneous mixture.

[0055] Step 104: Place the homogeneous mixture in a 25°C constant temperature water bath, and add 5wt% ammonia dropwise until pH=8 to obtain a mixed precipitate;

[0056] Step 105: Allow the obtained precipitate to stand for 3 hours for aging, filter, wash with deionized water until neutral, and dry to obtain SrTiO3 precursor powder;

[0057] Step 106: Calcine the SrTiO3 precursor powder at 800℃ for 6 hours to obtain the SrTiO3 support.

[0058] Step 2: Using the deposition-precipitation method, nickel nitrate is dissolved at room temperature, then added to the prepared SrTiO3 support and dispersed. Ammonia water is slowly added dropwise to precipitate the nickel source, forming an SrTiO3 catalyst precursor with a nickel loading of 15% of the total catalyst mass.

[0059] Step 3: The catalyst precursor was calcined at 400°C for 5 hours. The reducing atmosphere used for calcination was hydrogen / nitrogen at a ratio of 1:9 to obtain the SrTiO3 supported nickel catalyst.

[0060] Step 4: 120g of acetophenone was subjected to a reductive amination reaction in an aqueous medium under the action of 10g of the prepared catalyst to prepare α-phenylethylamine. The reaction temperature was 130℃, the partial pressure of ammonia in the system was 1.2MPa, the partial pressure of hydrogen was 0.5MPa, the reaction time was 8 hours, and the mass ratio of acetophenone / water in the system was 40% / 60%. The results of the first batch reaction were: acetophenone conversion rate 99.6%, selectivity: α-phenylethylamine 96.2%, α-phenylethanol 2.7%, and other components such as heavy components 1.1%. After 50 cycles, the acetophenone conversion rate was 99.3%, the selectivity was α-phenylethylamine 95.9%, α-phenylethanol 1.7%, and other components such as heavy components 2.4%.

[0061] Example 2

[0062] A preparation process using SrTiO3-supported nickel as a catalyst includes the following steps:

[0063] Step 1: Preparation of SrTiO3 support material:

[0064] Step 101: Add 20.61g of SrCl2 to 200mL of deionized water and stir until completely dissolved;

[0065] Step 102: Add 21.98g TiO(NO3)2 to 100mL of deionized water, add 10% dilute sulfuric acid dropwise, adjust the pH to 1.5-2.0, and stir until completely dissolved;

[0066] Step 103: Add the solution obtained in step 102 dropwise to the solution obtained in step 101 at a rate of 1 to 2 drops / second, and continue stirring to obtain a homogeneous mixture.

[0067] Step 104: Place the homogeneous mixture in a 25°C constant temperature water bath, and add 5wt% ammonium carbonate aqueous solution dropwise until pH=8 to obtain a mixed precipitate;

[0068] Step 105: Allow the obtained precipitate to stand for 6 hours for aging, filter, wash with deionized water until neutral, and dry to obtain SrTiO3 precursor powder;

[0069] Step 106: Calcine the SrTiO3 precursor powder at 900℃ for 8 hours to obtain the SrTiO3 support.

[0070] Step 2: Using the deposition-precipitation method, nickel nitrate is dissolved at room temperature, then added to the prepared SrTiO3 support and dispersed. Ammonia water is slowly added dropwise to precipitate the nickel source, forming an SrTiO3 catalyst precursor with a nickel loading of 10% of the total catalyst mass.

[0071] Step 3: The catalyst precursor was calcined at 500°C for 6 hours. The reducing atmosphere used for calcination was hydrogen / nitrogen at a ratio of 1:9 to obtain the SrTiO3 supported nickel catalyst.

[0072] Step 4: 120g of acetophenone was subjected to a reductive amination reaction in an aqueous medium under the action of 10g of the prepared catalyst to prepare α-phenylethylamine. The reaction temperature was 120℃, the partial pressure of ammonia in the system was 1.2MPa, the partial pressure of hydrogen was 0.6MPa, the reaction time was 8 hours, and the mass ratio of acetophenone / water in the system was 40% / 60%. The results of the first batch reaction were: acetophenone conversion rate 99.4%, selectivity: α-phenylethylamine 95.2%, α-phenylethanol 2.9%, and other components such as heavy components 1.9%. After 50 cycles, the acetophenone conversion rate was 99.1%, and the selectivity was: α-phenylethylamine 94.5%, α-phenylethanol 2.7%, and other components such as heavy components 2.8%.

[0073] Comparative Example 1

[0074] Take commercially available Raney nickel catalysts as an example.

[0075] Step 1: 120g of acetophenone was subjected to a reductive amination reaction in an aqueous medium using 10g of Raney nickel catalyst (W-2) to prepare α-phenylethylamine. The reaction temperature was 130℃, the partial pressure of ammonia in the system was 1.2MPa, the partial pressure of hydrogen was 0.5MPa, the reaction time was 8 hours, and the mass ratio of acetophenone / water in the system was 40% / 60%. The results of the first batch reaction were: acetophenone conversion rate 99.5%, and the product composition was α-phenylethylamine 94.7wt%, α-phenylethanol 4.6wt%, and other components such as heavy components 0.7wt%. After 50 cycles, the acetophenone conversion rate was 85.3%, and the selectivity was α-phenylethylamine 90.6%, α-phenylethanol 3.7%, and other components such as heavy components 5.7%.

[0076] Comparative Example 2

[0077] Take a commercially available supported nickel catalyst (Ni / Al2O3, with a Ni loading of 15%) as an example.

[0078] Step 1: 120g of acetophenone was subjected to a reductive amination reaction in an aqueous medium under the action of 10g of catalyst to prepare α-phenylethylamine. The reaction temperature was 130℃, the partial pressure of ammonia in the system was 1.2MPa, the partial pressure of hydrogen was 0.5MPa, the reaction time was 8 hours, and the mass ratio of acetophenone / water in the system was 40% / 60%. The results of the first batch of reaction were: acetophenone conversion rate of 99.7%, product composition of α-phenylethylamine 93.6%, α-phenylethanol 5.3%, and other components such as heavy components 1.1%. After 50 cycles, the acetophenone conversion rate was 83.3%, and the selectivity was α-phenylethylamine 88.5%, α-phenylethanol 3.7%, and other components such as heavy components 7.8%.

Claims

1. A method for preparing a reducing amination catalyst, characterized in that the step... include: Step 1: Preparation of SrTiO3 support: SrTiO3 precursor is calcined to obtain SrTiO3 support; Step 2: Load the nickel source onto the prepared SrTiO3 support to form a nickel-supported SrTiO3 catalyst precursor; Step 3: Calcine the SrTiO3 catalyst precursor to obtain the SrTiO3 supported nickel catalyst.

2. The preparation method according to claim 1, characterized in that, The preparation method of SrTiO3 precursor includes the following steps: Step 101: Adjust the pH of the titanium salt solution to 1.5-2, and then slowly add it dropwise into the strontium salt solution to obtain a homogeneous Sr-Ti mixed solution; Step 102: Slowly add the precipitant solution dropwise into the Sr-Ti mixed solution to obtain the Sr-Ti mixed precipitate; Step 103: The obtained precipitate is aged, then filtered, washed until neutral, and dried to obtain the SrTiO3 precursor.

3. The preparation method according to claim 2, characterized in that, The Sr / Ti molar ratio is 0.9 to 1.

1.

4. The preparation method according to claim 1 or 2, characterized in that, In step 1, the SrTiO3 precursor is calcined at a temperature of 400–1000℃, preferably 700–900℃, and the calcination time is 2–10 hours, preferably 5–8 hours.

5. The preparation method according to claim 1 or 2, characterized in that, The nickel content in the catalyst is 5-30% by mass, preferably 10-20%.

6. The preparation method according to claim 1 or 2, characterized in that, In step 3, the roasting temperature is 200–600℃, preferably 300–500℃; the roasting time is 2–10 hours. Preferably, the roasting atmosphere in step 3 is a reducing atmosphere, preferably one or two of hydrogen, nitrogen, and argon.

7. A method for preparing α-phenylethylamine by reductive amination of acetophenone, comprising the following steps: using acetophenone as a raw material, and in the presence of a SrTiO3 supported nickel catalyst prepared according to any one of claims 1-6, carrying out a reductive amination reaction in a solvent with ammonia water as the ammonia source.

8. The method according to claim 7, wherein, The reaction temperature is 20–170℃, preferably 90–140℃; The mass ratio of acetophenone to catalyst is 1:0.01 to 1:0.5, preferably 1:0.01 to 1:0.

1.

9. The method according to claim 7, wherein, The pressure after ammonia source vaporization is 0.2–4 MPa, preferably 0.5–1.5 MPa; The hydrogen pressure is 0.1–2 MPa, preferably 0.1–1.5 MPa.

10. The method according to claim 7, wherein, The mass ratio of raw materials to solvent is 1:1 to 1:10; Solvents include one or more of methanol, ethanol, propanol, isopropanol, n-butanol, tetrahydrofuran, methyltetrahydrofuran, diethyl ether, cyclopentyl methyl ether, and cyclohexyl methyl ether.