A ruthenium-based catalyst, a preparation method thereof, and an application thereof in catalytic reduction amination of carbonyl acids to prepare amino acids

Abstract

The present application discloses a ruthenium-based catalyst, a preparation method thereof, and an application thereof in catalytic reductive amination of carbonyl acids to prepare amino acids. The ruthenium-based catalyst comprises a carrier, and ruthenium metal and alkaline earth metal oxide loaded on the carrier; the carrier is an oxide. The method for catalytic reductive amination of carbonyl acids to prepare amino acids comprises: introducing hydrogen into a mixed solution containing a carbonyl acid, a catalyst, and ammonia water to carry out a reductive amination reaction to obtain an amino acid; the method has a high product yield, the catalyst is easy to separate, and the reaction conditions are mild. The use of the method and the catalyst has broad application prospects.

Description

Technical Field

[0001] The present application relates to a ruthenium-based catalyst, a preparation method thereof, and an application thereof in catalytic reductive amination of carbonyl acids to prepare amino acids, belonging to the technical field of chemical synthesis. Background Art

[0002] As the basic component of proteins, amino acids play a crucial role in life and are widely used in food and feed supplements, as raw materials for biodegradable plastics, pharmaceutical products, etc. Currently, amino acids are mainly produced by fermentation processes. The fermentation processes have long reaction times, generate a large amount of inorganic salts during production, have complex purification steps, and consume a large amount of energy. The traditional domestic synthesis method is the Strecker method, but it uses highly toxic cyanides and non-renewable aldehydes as substrates, which limits its development. A chemical route that converts renewable raw materials into amino acids in an environmentally friendly and energy-saving manner is highly desirable.

[0003] Carbonyl acid is an important organic chemical raw material with the properties of aldehydes and ketones and carboxylic acids. It can simultaneously undergo the reactions of aldehydes and ketones and acids, and sometimes cyclization or condensation reactions may also occur. It can be used as an intermediate for pharmaceuticals, dyes, plastics, and pesticides and has a wide range of applications in different fields. Carbonyl acid contains carbonyl and carboxylic acid bifunctional groups. During the reductive amination of the carbonyl group, the carboxylic acid will react with ammonia to form by-products, thereby reducing the selectivity of amino acids. Metal ruthenium has good applications in the hydrogenation field. Therefore, the carbonyl functional group of carbonyl acid can be utilized to reduce the carbonyl group by reductive amination to obtain an amino group, and then the product amino acid can be obtained. Summary of the Invention

[0004] The present invention aims to develop a highly efficient heterogeneous catalyst to reduce the carbonyl group in carbonyl acid by reductive amination to obtain an amino group and prepare amino acids.

[0005] The present application provides a method for preparing amino acids by reductive amination of carbonyl acids. This method has a high product yield and mild reaction conditions. This method uses hydrogen as the hydrogen source to reduce and aminate carbonyl acids to prepare amino acids. The catalyst used in this method, alkaline earth metals, is beneficial to the formation of amino groups, achieving high selectivity for amino acids and having broad application prospects.

[0006] In one aspect of the present application, a ruthenium-based catalyst is provided. The ruthenium-based catalyst includes a carrier and ruthenium metal and alkaline earth metal oxide supported on the carrier;

[0007] The carrier is an oxide.

[0008] Alkaline earth metal oxide is introduced into the catalyst, and through the electron transfer effect between the alkaline earth metal oxide and ruthenium metal, the hydrogenation activity of the catalyst is improved.

[0009] Optionally, the carrier is selected from at least one of TiO2, SiO2, Al2O3, ZrO2, ZnO, CeO2, Fe2O3;

[0010] The alkaline earth metal oxide is selected from at least one of MgO, CaO, SrO, BaO.

[0011] Optionally, in the ruthenium-based catalyst, the loading amount of metallic ruthenium is 0.2-10 wt%, wherein the mass of the catalyst is based on the mass of the carrier, and the mass of the metallic ruthenium is based on the mass of ruthenium element;

[0012] Optionally, in the ruthenium-based catalyst, the loading amount of metallic ruthenium is 1-8 wt%;

[0013] Optionally, the loading amount of metallic ruthenium in the ruthenium-based catalyst is 1-5 wt%.

[0014] Optionally, the upper limit of the loading amount of metallic ruthenium in the catalyst is selected from 1 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt%; the lower limit is selected from 0.2 wt%, 1 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%.

[0015] Optionally, in the ruthenium-based catalyst, the loading amount of the alkaline earth metal oxide is 10-30 wt%, wherein the mass of the catalyst is based on the mass of the carrier, and the mass of the alkaline earth metal oxide is based on its own mass.

[0016] Optionally, the upper limit of the loading amount of the alkaline earth metal in the catalyst is selected from 15 wt%, 18 wt%, 20 wt%, 25 wt%, 28 wt%, 30 wt%; the lower limit is selected from 10 wt%, 15 wt%, 18 wt%, 20 wt%, 25 wt%, 28 wt%.

[0017] In another aspect of the present application, a preparation method of the above ruthenium-based catalyst is provided, and the preparation method includes:

[0018] (1) Impregnating the oxide into a solution containing a metallic ruthenium precursor to obtain a catalyst precursor;

[0019] (2) Mixing the catalyst precursor with a solution containing an alkaline earth metal salt, adding ammonia water to form a mixed solution, and reducing to obtain the ruthenium-based catalyst.

[0020] Optionally, the metallic ruthenium precursor is a compound containing metallic ruthenium, and the compound containing metallic ruthenium is selected from at least one of ruthenium trichloride, ruthenium nitrate, ruthenium acetate, ruthenium carbonyl chloride;

[0021] The alkaline earth metal salt is selected from at least one of magnesium chloride, calcium chloride, strontium chloride, barium chloride.

[0022] Optionally, the solvent in the solution containing the ruthenium metal precursor is water, and the amount of water is the saturated water absorption of the carrier.

[0023] Optionally, the pH of the mixed solution is 10.0 - 11.0.

[0024] Optionally, the upper limit of the pH range is selected from 10.2, 10.4, 10.5, 10.6, 10.8, 11.0; the lower limit is selected from 10.0, 10.2, 10.4, 10.5, 10.6, 10.8.

[0025] Optionally, the reduction condition is reduction under a hydrogen atmosphere;

[0026] Optionally, the reduction temperature is 350 - 550 °C, and the reduction time is 1 - 6 h;

[0027] Optionally, the reduction temperature is 400 - 450 °C; the reduction time is 2 - 3 h.

[0028] Optionally, the upper limit of the reduction temperature is selected from 400 °C, 420 °C, 450 °C, 480 °C, 500 °C, 550 °C; the lower limit is selected from 350 °C, 400 °C, 420 °C, 450 °C, 480 °C, 500 °C.

[0029] Optionally, the upper limit of the reduction time is selected from 2 h, 3 h, 4 h, 5 h, 6 h; the lower limit is selected from 1 h, 2 h, 3 h, 4 h, 5 h.

[0030] As a specific embodiment, the preparation method of the ruthenium-based catalyst includes:

[0031] Impregnating the oxide into a solution containing a ruthenium metal precursor, stirring, standing, and drying to obtain the catalyst precursor; mixing and stirring the catalyst precursor and the alkaline earth metal salt solution at room temperature, adjusting the pH with ammonia water, continuing to stir for a period of time, then filtering, washing with deionized water, drying, and then reducing to obtain the catalyst.

[0032] Optionally, the specific conditions of the stirring include:

[0033] The stirring speed is 250 - 1200 rpm, preferably 400 - 800 rpm;

[0034] The stirring time is 0.5 - 12 h, preferably 0.5 - 6 h, and most preferably 0.5 - 2 h;

[0035] The standing time of the standing is 6 - 96 h, preferably 6 - 48 h, and most preferably 12 - 24 h.

[0036] Optionally, the upper limit of the stirring speed is selected from 400 rpm, 600 rpm, 700 rpm, 800 rpm, 1000 rpm, 1200 rpm; the lower limit is selected from 250 rpm, 400 rpm, 600 rpm, 700 rpm, 800 rpm, 1000 rpm.

[0037] Optionally, the upper limit of the stirring time is selected from 1 h, 2 h, 4 h, 6 h, 8 h, 12 h; the lower limit is selected from 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h.

[0038] Optionally, the upper limit of the standing time is selected from 12 h, 24 h, 36 h, 48 h, 72 h, 96 h; the lower limit is selected from 6 h, 12 h, 24 h, 36 h, 48 h, 72 h.

[0039] Optionally, the specific conditions for drying include:

[0040] The drying temperature is 100 - 180 °C, preferably 110 - 120 °C; the drying time is 5 - 15 h, preferably 10 - 12 h.

[0041] Optionally, the upper limit of the drying temperature is selected from 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 180 °C; the lower limit is selected from 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C.

[0042] Optionally, the upper limit of the drying time is selected from 7 h, 8 h, 9 h, 10 h, 12 h, 15 h; the lower limit is selected from 5 h, 7 h, 8 h, 9 h, 10 h, 12 h.

[0043] Optionally, the continuous stirring time is 0.5 - 5 h, preferably 0.5 - 2 h.

[0044] Optionally, the upper limit of the continuous stirring time is selected from 1 h, 2 h, 3 h, 4 h, 5 h; the lower limit is selected from 0.5 h, 1 h, 2 h, 3 h, 4 h.

[0045] Another aspect of the present application provides a method for catalytic reductive amination of carbonyl acid to prepare amino acid, including: introducing hydrogen into a mixed solution containing carbonyl acid, catalyst, and ammonia water for reductive amination reaction to obtain amino acid;

[0046] Wherein the catalyst is selected from the above ruthenium-based catalyst or the ruthenium-based catalyst obtained according to the above preparation method.

[0047] Optionally, the carbonyl acid compound is selected from at least one of the compounds containing hydroxyl and carboxyl shown in Formula I, Formula II, and Formula III:

[0048]

[0049] Among them, R1 is selected from a hydrogen, methyl, carboxymethyl or benzyl group, R2 is selected from a methyl group, and R3 is selected from a methyl group.

[0050] Optionally, the oxo acid compound is selected from at least one of glyoxylic acid, pyruvic acid, 3-oxobutyric acid, levulinic acid, oxaloacetic acid, phenylpyruvic acid;

[0051] Optionally, the molar amount of the catalyst is 0.1 to 15% of the molar amount of the oxo acid, wherein the molar amount of the catalyst is based on the molar amount of ruthenium element;

[0052] Optionally, the upper limits of the percentage of the molar amount of the catalyst relative to the molar amount of the aldehyde compound are selected from 0.8%, 1%, 2%, 5%, 10%, 15%; the lower limits are selected from 0.1%, 0.8%, 1%, 2%, 5%, 10%.

[0053] Optionally, the specific conditions of the reductive amination reaction include:

[0054] The hydrogen partial pressure is 0.1 to 4.0 MPa; the reaction temperature is 25 to 120 °C; the reaction time is 0.5 to 24 h.

[0055] Optionally, the specific conditions of the reductive amination reaction include:

[0056] The hydrogen source partial pressure is 0.5 - 2.0 MPa; the reaction temperature is 50 - 100 °C; the reaction time is 0.5 - 6 h.

[0057] Optionally, the upper limits of the hydrogen partial pressure are selected from 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa; the lower limits are selected from 0.1 MPa, 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, 3.0 MPa.

[0058] Optionally, the upper limits of the reaction temperature are selected from 50 °C, 70 °C, 80 °C, 90 °C, 100 °C, 120 °C; the lower limits are selected from 25 °C, 50 °C, 70 °C, 80 °C, 90 °C, 100 °C.

[0059] Optionally, the upper limits of the reaction time are selected from 1 h, 2 h, 3 h, 4 h, 6 h, 24 h; the lower limits are selected from 0.5 h, 1 h, 2 h, 3 h, 4 h, 6 h.

[0060] As a specific embodiment, the method for catalytic reductive amination of oxo acid to prepare amino acid includes: adding an oxo acid, a catalyst and ammonia water into a reaction kettle, mixing, heating to 25 - 120 °C, with a hydrogen partial pressure of 0.1 - 4.0 MPa and a reaction time of 0.5 - 24 h, and the oxo acid is reductively aminated to an amino acid.

[0061] As a specific embodiment, the present invention provides a method for preparing a ruthenium-based catalyst and its application in the highly selective preparation of amino acids from carbonyl acids. An oxide is impregnated into a solution containing a metal ruthenium precursor, and after stirring, standing, and drying, the catalyst precursor is obtained; the catalyst precursor and an alkaline earth metal salt solution are mixed and stirred at room temperature, the pH is adjusted by adding ammonia water, and after continuous stirring for a period of time, it is filtered, washed with deionized water, dried, and then reduced to obtain the catalyst. This method has a high product yield, the catalyst is easy to separate, and the reaction conditions are mild. The use of this method and the catalyst has broad application prospects.

[0062] The amino acid product prepared by this catalyst has a high yield, the catalyst preparation method is simple, it is easy to separate from the system, and it can still maintain a high catalytic activity after being recycled many times.

[0063] The beneficial effects that can be produced by this application include:

[0064] 1) The method for preparing amino acids by reductive amination of carbonyl acids provided by the present invention can achieve high selectivity for amino acids under mild conditions due to the action of alkaline earth metals in the catalyst.

[0065] 2) The catalyst system used in this method has good stability, high product yield and selectivity, low dosage, a simple preparation process, the catalyst is easy to separate from the system, and it is environmentally friendly.

[0066] 3) After the catalyst in this application is recycled five times, it can still maintain good stability, and the product yield remains above 90%. Specific embodiments

[0067] The following describes this application in detail with reference to examples, but this application is not limited to these examples.

[0068] Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels.

[0069] The calculation of the conversion rate and yield in the examples of this application is as follows:

[0070]

[0071]

[0072] Example 1

[0073] (1) 0.1 g of the carrier SiO2 and ruthenium trichloride (calculated as ruthenium element) accounting for 5 wt% of the carrier mass are added to water with a saturated water absorption amount of 0.1 g of the carrier. After stirring at 800 rpm for 2 h, it is left standing at room temperature for 24 h and dried at 120 °C for 10 h to obtain the catalyst precursor;

[0074] (2) Add magnesium chloride (calculated as magnesium element) with a mass of 15 wt% of the catalyst precursor and the support to water with a mass ratio to the support of 5. After stirring at 800 rpm for 2 h, add ammonia water (25 wt%) to adjust the pH to 10.2. After continuing to stir for 0.5 h, filter and wash with deionized water, dry at 120 °C for 10 h, and reduce in a hydrogen atmosphere at 450 °C for 3 h to obtain the Ru-MgO / SiO2 catalyst.

[0075] Application Example 1

[0076] Application of a catalyst of metal ruthenium supported on an oxide and an alkaline earth metal oxide in the reductive amination of oxo acids to prepare amino acids:

[0077] Add glyoxylic acid, the Ru-MgO / SiO2 catalyst prepared in Example 1, and ammonia water (25 wt%) to a 15 mL reaction kettle, close the kettle. Among them, the dosage of glyoxylic acid is 1 mmol, the molar amount of ruthenium in the catalyst is 0.8% of the molar amount of glyoxylic acid, and the dosage of ammonia water is 5 mL; displace the air in the kettle with hydrogen 5 times, fill in 2.0 MPa of hydrogen, heat up to 50 °C, and react at this temperature for 2 h. After the reaction is completed, naturally cool the reaction mixture to room temperature, and centrifuge to remove the catalyst. Rotavaporize the reaction solution to remove the solvent ammonia water, add the internal standard trioxane and deuterated water and mix evenly, take samples and conduct NMR analysis. The conversion rate of glyoxylic acid is 99%, and the yield of glycine is 99%.

[0078] Example 2

[0079] (1) Add 0.1 g of the support TiO2 and ruthenium nitrate (calculated as ruthenium element) with a mass of 1 wt% of the support to water with a saturated water absorption capacity of the support. After stirring at 400 rpm for 6 h, let stand at room temperature for 12 h, and dry at 110 °C for 12 h to obtain the catalyst precursor;

[0080] (2) Add the catalyst precursor and calcium chloride (calculated as calcium element) with a mass of 10 wt% of the support to water with a mass ratio to the support of 5. After stirring at 400 rpm for 6 h, add ammonia water (25 wt%) to adjust the pH to 10.5. After continuing to stir for 2 h, filter and wash with deionized water, dry at 110 °C for 12 h, and reduce in a hydrogen atmosphere at 400 °C for 2 h to obtain the Ru-CaO / TiO2 catalyst.

[0081] Application Example 2

[0082] Application of a catalyst of metal ruthenium supported on an oxide and an alkaline earth metal oxide in the reductive amination of oxo acids to prepare amino acids:

[0083] Pyruvic acid, the Ru-CaO / TiO₂ catalyst obtained in Example 2, and ammonia water (25 wt%) were added to a 15 mL reactor, and the reactor was closed. Among them, the amount of pyruvic acid used was 1 mmol, the molar amount of ruthenium in the catalyst was 1.0% of the molar amount of pyruvic acid, and the amount of ammonia water used was 5 mL; the air in the reactor was replaced with hydrogen 5 times, 0.5 MPa of hydrogen was charged, the temperature was raised to 100 °C, and the reaction was carried out at this temperature for 1 h. After the reaction was completed, it was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of pyruvic acid was 99%, and the yield of alanine was 97%.

[0084] Example 3

[0085] (1) 0.1 g of the carrier Al₂O₃ and ruthenium acetate (calculated as ruthenium element) accounting for 10 wt% of the carrier mass were added to the water with a saturated water absorption amount of 0.1 g of the carrier. After stirring at 250 rpm for 12 h, it was left standing at room temperature for 96 h and dried at 100 °C for 15 h to obtain a catalyst precursor;

[0086] (2) The catalyst precursor and strontium chloride (calculated as strontium element) accounting for 20 wt% of the carrier mass were added to the water with a mass ratio to the carrier of 5. After stirring at 250 rpm for 12 h, ammonia water (25 wt%) was added to adjust the pH to 10.8, and stirring was continued for 5 h. Then, it was filtered and washed with deionized water, dried at 100 °C for 15 h, and reduced in a hydrogen atmosphere at 350 °C for 6 h to obtain the Ru-SrO / Al₂O₃ catalyst.

[0087] Application Example 3

[0088] Application of a catalyst of metal ruthenium and alkaline earth metal oxide supported on an oxide in the reductive amination of carbonyl acid to prepare amino acids:

[0089] 3-Oxobutyric acid, the Ru-SrO / Al₂O₃ catalyst obtained in Example 3, and ammonia water (25 wt%) were added to a 15 mL reactor, and the reactor was closed. Among them, the amount of 3-oxobutyric acid used was 1 mmol, the molar amount of ruthenium in the catalyst was 0.1% of the molar amount of 3-oxobutyric acid, and the amount of ammonia water used was 5 mL; the air in the reactor was replaced with hydrogen 5 times, 4.0 MPa of hydrogen was charged, the temperature was raised to 80 °C, and the reaction was carried out at this temperature for 6 h. After the reaction was completed, it was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 3-oxobutyric acid was 99%, and the yield of 3-aminobutyric acid was 96%.

[0090] Example 4

[0091] (1) 0.1 g of the carrier ZrO₂ and ruthenium carbonyl chloride (calculated as ruthenium element) accounting for 6 wt% of the carrier mass were added to the water with a saturated water absorption amount of 0.1 g of the carrier. After stirring at 1200 rpm for 0.5 h, it was left standing at room temperature for 6 h and dried at 180 °C for 5 h to obtain a catalyst precursor;

[0092] (2) Add barium chloride (calculated as barium element) accounting for 25 wt% of the mass of the catalyst precursor and the support to water with a mass ratio to the support of 5. After stirring at 1200 rpm for 0.5 h, add ammonia water (25 wt%) to adjust the pH to 11.0. Continue stirring for 3 h, then filter and wash with deionized water, dry at 180 °C for 5 h, and reduce at 550 °C in a hydrogen atmosphere for 1 h to obtain the Ru-BaO / ZrO2 catalyst.

[0093] Application Example 4

[0094] Application of a catalyst of metal ruthenium and alkaline earth metal oxide supported on an oxide in the reductive amination of carbonyl acid to prepare amino acids:

[0095] Add levulinic acid, the Ru-BaO / ZrO2 catalyst obtained in Example 4, and ammonia water (25 wt%) to a 15 mL reaction kettle, close the kettle. Among them, the dosage of levulinic acid is 1 mmol, the molar amount of ruthenium in the catalyst is 15% of the molar amount of levulinic acid, and the dosage of ammonia water is 5 mL; displace the air in the kettle with hydrogen 5 times, fill with 0.1 MPa hydrogen, heat up to 120 °C, and react at this temperature for 0.5 h. After the reaction is completed, cool and sample for analysis according to the method described in Example 1. The conversion rate of levulinic acid is 99%, and the yield of 4-aminopentanoic acid is 96%.

[0096] Example 5

[0097] (1) Add 0.1 g of the support ZnO and ruthenium nitrate (calculated as ruthenium element) accounting for 0.2 wt% of the mass of the support to water with a mass equal to the saturated water absorption of 0.1 g of the support. After stirring at 1000 rpm for 4 h, let it stand at room temperature for 48 h, and dry at 150 °C for 8 h to obtain the catalyst precursor;

[0098] (2) Add the catalyst precursor and strontium chloride (calculated as strontium element) accounting for 30 wt% of the mass of the support to water with a mass ratio to the support of 5. After stirring at 1000 rpm for 4 h, add ammonia water (25 wt%) to adjust the pH to 10.0. Continue stirring for 1 h, then filter and wash with deionized water, dry at 150 °C for 8 h, and reduce at 500 °C in a hydrogen atmosphere for 5 h to obtain the Ru-SrO / ZnO catalyst.

[0099] Application Example 5

[0100] Application of a catalyst of metal ruthenium and alkaline earth metal oxide supported on an oxide in the reductive amination of carbonyl acid to prepare amino acids:

[0101] Oxaloacetic acid, the Ru-SrO / ZnO catalyst obtained in Example 5, and ammonia water (25 wt%) were added to a 15 mL autoclave, and the autoclave was closed. Among them, the amount of oxaloacetic acid used was 1 mmol, the molar amount of ruthenium in the catalyst was 10% of the molar amount of oxaloacetic acid, and the amount of ammonia water used was 5 mL; the air in the autoclave was replaced with hydrogen 5 times, 3.0 MPa hydrogen was charged, the temperature was raised to 25 °C, and the reaction was carried out at this temperature for 24 h. After the reaction was completed, it was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of oxaloacetic acid was 99%, and the yield of aspartic acid was 96%.

[0102] Example 6

[0103] (1) 0.1 g of the support CeO2 and ruthenium trichloride (calculated as ruthenium element) accounting for 8 wt% of the mass of the support were added to the water with a saturated water absorption amount of 0.1 g of the support. After stirring at 600 rpm for 1 h, it was left standing at room temperature for 36 h and dried at 130 °C for 9 h to obtain a catalyst precursor;

[0104] (2) The catalyst precursor and magnesium chloride (calculated as magnesium element) accounting for 28 wt% of the mass of the support were added to the water with a mass ratio to the support of 5. After stirring at 600 rpm for 1 h, ammonia water (25 wt%) was added to adjust the pH to 10.4, and stirring was continued for 4 h. Then, it was filtered and washed with deionized water and dried at 130 °C for 9 h. It was reduced at 420 °C for 4 h under a hydrogen atmosphere to obtain the Ru-MgO / CeO2 catalyst.

[0105] Application Example 6

[0106] Application of a catalyst of ruthenium supported on an oxide and an alkaline earth metal oxide in the reductive amination of carbonyl acids to prepare amino acids:

[0107] Phenylpyruvic acid, the Ru-MgO / CeO2 catalyst obtained in Example 6, and ammonia water (25 wt%) were added to a 15 mL autoclave, and the autoclave was closed. Among them, the amount of phenylpyruvic acid used was 1 mmol, the molar amount of ruthenium in the catalyst was 5% of the molar amount of phenylpyruvic acid, and the amount of ammonia water used was 5 mL; the air in the autoclave was replaced with hydrogen 5 times, 1.0 MPa hydrogen was charged, the temperature was raised to 90 °C, and the reaction was carried out at this temperature for 4 h. After the reaction was completed, it was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of phenylpyruvic acid was 99%, and the yield of phenylpyruvic acid was 95%.

[0108] Example 7

[0109] (1) 0.1 g of the support Fe2O3 and ruthenium trichloride (calculated as ruthenium element) accounting for 4 wt% of the mass of the support were added to the water with a saturated water absorption amount of 0.1 g of the support. After stirring at 700 rpm for 8 h, it was left standing at room temperature for 72 h and dried at 140 °C for 7 h to obtain a catalyst precursor;

[0110] (2) Add calcium chloride (calculated as calcium element) with a mass of 18 wt% of the catalyst precursor and the support to water with a mass ratio of 5 to the support. After stirring at 700 rpm for 8 h, add ammonia water (25 wt%) to adjust the pH to 10.6. After continuing to stir for 2 h, filter and wash with deionized water, dry at 140 °C for 7 h, and reduce at 480 °C in a hydrogen atmosphere for 3 h to obtain the Ru-CaO / Fe2O3 catalyst.

[0111] Application Example 7

[0112] Application of a catalyst of ruthenium supported on an oxide and an alkaline earth metal oxide in the reductive amination of oxo acids to prepare amino acids:

[0113] Add glyoxylic acid, the Ru-CaO / Fe2O3 catalyst obtained in Example 7, and ammonia water (25 wt%) to a 15 mL autoclave, close the autoclave. Among them, the dosage of glyoxylic acid is 1 mmol, the molar amount of ruthenium in the catalyst is 2% of the molar amount of glyoxylic acid, and the dosage of ammonia water is 5 mL; displace the air in the autoclave with hydrogen 5 times, fill with 1.5 MPa hydrogen, heat up to 70 °C, and react at this temperature for 3 h. After the reaction is completed, cool and sample for analysis according to the method described in Example 1. The conversion rate of glyoxylic acid is 99%, and the yield of glycine is 98%.

[0114] Example 8

[0115] Prepare the catalyst and reduce the catalyst according to the conditions of Example 1 and Application Example 1 and then use it in the reductive amination reaction of oxo acids. Different from Example 1 is that after the reaction is completed, the catalyst is centrifuged and separated, and the catalyst is continuously centrifuged and washed with water 5 times. The reductive amination reaction of oxo acids is cycled again, and the catalyst is used in this way for 5 times. The results are shown in Table 1.

[0116] Table 1. Recycling effect of ruthenium-based catalysts on the reductive amination of glyoxylic acid

[0117] Number of cycles Conversion rate of carbonyl acid (C%) Yield of amino acid (C%) 1 99 99 2 99 98 3 99 96 4 99 96 5 99 94

[0118] It can be seen from Table 1 that the prepared ruthenium-based catalyst can still maintain high catalytic activity after being recycled 5 times for the reductive amination of glyoxylic acid, and the yield of glycine remains above 94%. The catalysts provided in Examples 2-7 are recycled under the same conditions and can also maintain high catalytic activity. After being recycled 5 times, the yield of amino acids remains above 90%.

[0119] Comparative Example 1

[0120] The catalyst was prepared under the conditions of Example 1 and then reduced and used in the reductive amination reaction of oxo acid. Different from Example 1, after obtaining the catalyst precursor, it was directly reduced at 450 °C for 3 h under a hydrogen atmosphere to obtain the Ru / SiO2 catalyst. The conversion rate of glyoxylic acid was 99%, and the yield of glycine was 50%.

[0121] The preparation method of the present invention has mild conditions, a simple and easy operation process, the catalyst is easy to separate from the system, and can still maintain high catalytic activity after being recycled many times. The prepared ruthenium metal and alkaline earth metal oxides supported on an oxide carrier can highly selectively prepare amino acids in the reductive amination of oxo acids, and have broad application prospects.

[0122] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent embodiments and all fall within the scope of the technical solution.

Claims

1. A method for catalytic reductive amination of carbonyl acids to prepare amino acids, characterized in that, Comprising: Hydrogen is introduced into a mixed solution containing a carbonyl acid, a ruthenium-based catalyst, and ammonia water for reductive amination reaction to obtain an amino acid; The ruthenium-based catalyst comprises a carrier and ruthenium metal and alkaline earth metal oxide supported on the carrier; The carrier is an oxide; The carrier is selected from at least one of TiO2, SiO2, Al2O3, ZrO2, ZnO, CeO2, Fe2O3; The alkaline earth metal oxide is selected from at least one of MgO, CaO, SrO, BaO; In the ruthenium-based catalyst, the loading amount of ruthenium metal is 0.2 - 10 wt%, wherein the mass of the catalyst is based on the mass of the carrier, and the mass of the ruthenium metal is based on the mass of ruthenium element; The carbonyl acid compound is selected from at least one of the compounds shown in Formula I, Formula II, and Formula III: Formula Ⅰ; Formula II; Formula III; Wherein, R1 is selected from hydrogen, methyl, carboxymethyl or benzyl group, R2 is selected from methyl group, and R3 is selected from methyl group.

2. The method according to claim 1, characterized in that, In the ruthenium-based catalyst, the loading amount of ruthenium metal is 1 - 8 wt%.

3. The method according to claim 1, characterized in that, The loading amount of ruthenium metal in the ruthenium-based catalyst is 1 - 5 wt%.

4. The method according to claim 1, characterized in that, In the ruthenium-based catalyst, the loading amount of alkaline earth metal oxide is 10 - 30 wt%, wherein the mass of the catalyst is based on the mass of the carrier, and the mass of the alkaline earth metal oxide is based on its own mass.

5. The method according to claim 1, characterized in that, The preparation method of the ruthenium-based catalyst (1) The oxide is impregnated into a solution containing a ruthenium metal precursor to obtain a catalyst precursor; (2) The catalyst precursor and a solution containing an alkaline earth metal salt are mixed, ammonia water is added to form a mixed solution, and the ruthenium-based catalyst is obtained by reduction.

6. The method according to claim 5, characterized in that, The ruthenium metal precursor is a ruthenium metal-containing compound, and the ruthenium metal-containing compound is selected from at least one of ruthenium trichloride, ruthenium nitrate, ruthenium acetate, ruthenium carbonyl chloride; The alkaline earth metal salt is selected from at least one of magnesium chloride, calcium chloride, strontium chloride, barium chloride.

7. The method according to claim 5, characterized in that, The pH of the mixed solution is 10.0 - 11.

0.

8. The method according to claim 5, characterized in that, The condition of the reduction is reduction under a hydrogen atmosphere; The reduction temperature is 350 - 550 °C, and the reduction time is 1 - 6 h.

9. The method according to claim 8, characterized in that, The reduction temperature is 400 - 450 °C; the reduction time is 2 - 3 h.

10. The method according to claim 1, characterized in that, The carbonyl acid compound is selected from at least one of glyoxylic acid, pyruvic acid, 3-oxobutyric acid, levulinic acid, oxaloacetic acid, phenylpyruvic acid.

11. The method according to claim 1, characterized in that, The molar amount of the catalyst is 0.1 - 15% of the molar amount of the carbonyl acid, wherein the molar amount of the catalyst is based on the molar amount of ruthenium element.

12. According to the method described in claim 1, wherein, The specific conditions of the reductive amination reaction are: The hydrogen partial pressure is 0.1 - 4.0 MPa; The reaction temperature is 25 - 120 °C; The reaction time is 0.5 - 24 h.

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