A catalyst, a method for preparing the same, and use thereof in the production of 3-hydroxybutyric acid

Abstract

The application discloses a catalyst and a preparation method thereof and application of the catalyst in preparation of 3-hydroxybutyric acid, the catalyst comprising CuCr2O4 and a metal element; the metal element is selected from Ag and / or Pt; a mass ratio of the CuCr2O4 to the metal element is 100:1-3; and the catalyst is used in an oxidation reaction for preparing 3-hydroxybutyric acid. The catalyst provided by the application can be applied to the oxidation reaction for preparing 3-hydroxybutyric acid, and the conversion rate of 3-hydroxybutyraldehyde and the selectivity of generated 3-hydroxybutyric acid are improved, the reaction speed is fast, the yield is high, and the catalyst can be applied to large-scale production. The preparation method of the catalyst is stable, controllable and good in reproducibility.

Description

Technical Field

[0001] This application relates to a catalyst, its preparation method, and its application in the preparation of 3-hydroxybutyric acid, and belongs to the field of chemical engineering. Background Technology

[0002] 3-Hydroxybutyric acid (3-HHBEA) can be directly used to produce aliphatic polyester plastics and is an important monomer for the preparation of biodegradable plastics. It can also be copolymerized with other compounds to produce high-performance plastics. For example, alternating copolymerization with aromatic polyesters can produce copolyester products (CPE) with different properties and excellent performance. It can also undergo an amine exchange reaction with polyamide (nylon) to synthesize polyamide-ester copolymers (CPAE), which have advantages such as high melting point and high tensile strength. Furthermore, blending 3-HHBEA with general-purpose plastics (PE, PP, PS, PVC) can produce biodegradable plastics. Due to the addition of 3-HHBEA, these materials lose their mechanical properties and shape, and can be composted to obtain the same environmentally friendly advantages as biodegradable plastics.

[0003] Currently, there are multiple synthetic routes for producing 3-hydroxybutyric acid (3-HYB). The hydrolysis method is relatively simple and produces few byproducts, but it uses large amounts of cyanide, a highly toxic substance, posing a hazard to operators. Another method utilizes organometallic compounds, with the ester as the final product, which can be directly used as a raw material for plastics. Since α-bromoesters are not yet produced industrially, using acetaldehyde or acetic acid as raw materials for industrial production would increase the number of reaction steps, leading to more byproducts and the generation of Zn-containing contaminants. Furthermore, the Reformatsky reaction itself has a low yield, limiting its industrialization. The reduction method uses ethyl acetoacetate as a raw material, producing 3-HYB in a single step. However, due to the high price of ethyl acetoacetate, it is not economically advantageous compared to biochemical or fermentation methods. A method using lithium naphthylene catalysis is also possible. Although acetaldehyde and acetic acid are important and readily available chemical raw materials, the preparation of lithium naphthylene is complex, and its reactive and easily decomposed nature increases the difficulty of production. While the lithium naphthylene catalyst can be recovered, the recovery process is challenging. Because the raw materials contain hydroxyl groups, the oxidation method requires relatively low temperatures and pressures. 3-Hydroxybutyric acid (HHB) is not produced on a large industrial scale; it is prepared by acetaldehyde via an aldol condensation reaction. This method is the preferred approach for industrialization.

[0004] The catalyst prepared in this patent is used in the oxidation preparation of 3-hydroxybutyric acid. The catalyst has good activity, high conversion rate of 3-hydroxybutyraldehyde and selectivity of 3-hydroxybutyric acid, and good stability. Summary of the Invention

[0005] The catalyst prepared in this application is used in the oxidative preparation of 3-hydroxybutyric acid. The catalyst has good activity, high conversion rate of 3-hydroxybutyraldehyde and selectivity of 3-hydroxybutyric acid, and good stability.

[0006] According to one aspect of this application, a catalyst is provided, comprising CuCr2O4 and a metal element;

[0007] The metallic element is selected from Ag and / or Pt;

[0008] The mass ratio of CuCr2O4 to the metal element is 100:1 to 3; the mass ratio of CuCr2O4 to the metal element is selected from 100:1, 100:2, and 100:3.

[0009] The catalyst is used for the oxidation reaction to prepare 3-hydroxybutyric acid and improves the conversion rate of 3-hydroxybutyraldehyde and the selectivity of 3-hydroxybutyric acid.

[0010] According to another aspect of this application, a method for preparing the above-mentioned catalyst is provided, comprising the following steps:

[0011] 1) Mix raw materials containing copper source, chromium source and solvent I, sonicate and grind, dry I, and calcine I to obtain CuCr2O4;

[0012] 2) The raw materials containing the metal element source, CuCr2O4 and solvent II are mixed, and the mixture is dried and calcined by impregnation method to obtain the catalyst.

[0013] The copper source is selected from at least one of copper sulfate, copper chloride, or copper nitrate.

[0014] The chromium source is selected from chromium trioxide and / or chromium powder;

[0015] The molar ratio of the copper source to the chromium source is 0.9 to 2:2; the upper limit of the molar ratio of the copper source to the chromium source is selected from 2:2 and 1.9:2, and the lower limit is selected from 0.9:2 and 1:2.

[0016] The molar amount of the copper source is expressed in terms of the molar amount of cobalt.

[0017] The molar amount of the chromium source is expressed in terms of the molar amount of chromium element;

[0018] Solvent I is selected from at least one of methanol, ethanol, or acetone;

[0019] Furthermore, the solvent is ethanol.

[0020] The solid-liquid ratio of the total mass of the copper source and the chromium source to the volume of solvent I is 1:10 to 30 g / ml.

[0021] The upper limit of the solid-liquid ratio of the total mass of the copper source and the chromium source to the volume of the solvent I is selected from 1:10 g / ml and 1:20 g / ml, and the lower limit is selected from 1:30 g / ml and 1:20 g / ml.

[0022] The temperature of the drying process I is 80-110°C; the temperature of the drying process I is any value among 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, and 110°C, or a range between any two.

[0023] The drying time of the first step is 2 to 5 hours; the drying time of the first step is any value among 2 hours, 3 hours, 4 hours, and 5 hours, or any range between two of them.

[0024] The temperature of the roasting I is 600 to 1200°C; the temperature of the roasting I is any value or a range between any two of 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C.

[0025] The roasting time I is 4 to 8 hours; the roasting time I is any value among 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, or a range between any two.

[0026] The metal element source is selected from at least one of silver nitrate, silver carbonate, silver sulfate, or chloroplatinic acid;

[0027] Solvent II is selected from at least one of methanol, ethanol, or acetone;

[0028] The solid-liquid ratio of the metal element source, CuCr2O4, and solvent II is 1:10 to 30 g / ml.

[0029] The temperature of the second drying process is 80 to 110°C; the temperature of the second drying process is any value among 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, and 110°C, or a range between any two.

[0030] The drying time II is 2 to 5 hours; the drying time II is any value among 2 hours, 3 hours, 4 hours, and 5 hours, or any range between two of them.

[0031] The temperature of the second roasting is 500-600°C; the temperature of the second roasting is any value of 500°C, 550°C, and 600°C or any range between two of them.

[0032] The roasting time II is 4 to 8 hours; the roasting time II is any value among 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, or a range between any two.

[0033] According to another aspect of this application, a method for preparing 3-hydroxybutyric acid is provided, comprising the following steps:

[0034] In a fixed-bed reactor, a mixture containing oxygen and 3-hydroxybutyraldehyde is introduced and reacted to obtain a product containing 3-hydroxybutyric acid.

[0035] The fixed-bed reactor is filled with a catalyst;

[0036] The catalyst is selected from the catalysts described above or the catalysts prepared by the methods described above.

[0037] The oxygen flow rate is 0.1 to 0.5 L / min; the oxygen flow rate is any value among 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, and 0.5 L / min, or a range between any two.

[0038] The mass ratio of the catalyst to the 3-hydroxybutyraldehyde is 0.2 to 1:100; the mass ratio of the catalyst to the 3-hydroxybutyraldehyde is selected from 0.2:100, 0.5:100, 0.7:100, and 1:100.

[0039] The reaction temperature is 40–80°C; the reaction temperature is any value among 40°C, 50°C, 60°C, 70°C, and 80°C, or a range between any two.

[0040] The reaction time is 3 to 6 hours; the reaction time is any value among 3 hours, 4 hours, 5 hours, and 6 hours, or any range between two of them.

[0041] The 3-hydroxybutyraldehyde is an aqueous solution with a mass fraction of 20-50 wt%; the 3-hydroxybutyraldehyde is any value among 20 wt%, 30 wt%, 40 wt%, and 50 wt% or any range between two of them.

[0042] The beneficial effects that this application can produce include:

[0043] 1) The catalyst provided in this application can be applied to the reaction of oxidative preparation of 3-hydroxybutyric acid, and improves the conversion rate of 3-hydroxybutyraldehyde and the selectivity of the generated 3-hydroxybutyric acid.

[0044] 2) The preparation method of the catalyst provided in this application is stable, controllable and reproducible.

[0045] 3) The method for preparing 3-hydroxybutyric acid by oxidation provided in this application uses the catalyst provided in this application, which has a fast reaction rate and high yield, and can be applied to large-scale production. Attached Figure Description

[0046] Figure 1 Catalyst 1 # X-ray powder diffraction pattern of the active component CuCr2O4. Detailed Implementation

[0047] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0048] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased commercially.

[0049] The gas chromatograph used was an Agilent 7890B gas chromatograph.

[0050] Example 1

[0051] Preparation of catalysts

[0052] Taking sample 1 in Table 1 as an example, copper sulfate and chromium trioxide with a molar ratio of 2:2 were mixed in an ethanol solution (solid-liquid ratio of 1:20 g / ml), ultrasonicated, ground, and dried in an oven at 100℃ for 4 hours; then calcined in a high-temperature furnace at 1000℃ for 4 hours to obtain CuCr2O4 sample 1. # Silver nitrate, sample 1 # The mixture was prepared by mixing the catalysts in an ethanol solution at a mass ratio of 100:2 and drying them in an oven at 100°C for 4 hours. The resulting composite catalyst was then calcined at 500°C for 4 hours, and is designated as Catalyst 1. # .

[0053] Following the steps below, adjust the type and amount of each raw material and the reaction parameters to obtain a series of catalysts numbered 2 to 28, denoted as catalyst 2. # ~Catalyst 28 # As shown in Table 1 below:

[0054] Table 1

[0055]

[0056]

[0057] The explanations for each column in Table 1 above are as follows:

[0058] Copper sources: copper sulfate (Cu1), copper chloride (Cu2), copper nitrate (Cu3).

[0059] Chromium sources: Chromium trioxide (Cr1), chromium powder (Cr2).

[0060] Solvents: Methanol (solution 1), ethanol (solution 2), acetone (solution 3).

[0061] Silver sources: silver nitrate (Ag1), silver carbonate (Ag2), silver sulfate (Ag3).

[0062] Platinum source: Chloroplatinic acid (Pt)

[0063] Drying I: Drying during the preparation of CuCr2O4.

[0064] Drying II: Drying after mixing CuCr2O4 with the support.

[0065] Calcination I: Calcination during the preparation of CuCr2O4.

[0066] Calcination II: Calcination of CuCr2O4 mixed with support.

[0067] XRD characterization

[0068] Catalyst 1 was analyzed using a Miniflex 600 X-ray diffractometer with a Cu target. # The active component CuCr2O4 powder was diffracted to obtain catalyst 1. # The diffraction peaks of the active component CuCr2O4 conform to the characteristic peaks of CuCr2O4 (e.g. Figure 1 (As shown).

[0069] Example 2

[0070] The catalyst is used in the oxidation reaction to prepare 3-hydroxybutyric acid.

[0071] Catalysts 1 to 28 prepared in Example 1 # ~Catalyst 28 # In the oxidation preparation of 3-hydroxybutyric acid, the reaction temperature was 60℃, the reaction time was 5h, the O2 flow rate was 0.3L / min, the mass fraction of the 3-hydroxybutyraldehyde aqueous solution was 50%, and the mass ratio of catalyst to raw material was 1:100.

[0072] After the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 2. It can be seen that the prepared catalyst 1... # ~28 # Both reactions used for the oxidation preparation of 3-hydroxybutyric acid have high yields.

[0073] Table 2

[0074]

[0075]

[0076] Example 3

[0077] Catalyst 1 prepared in Table 1 #The oxidation reaction to prepare 3-hydroxybutyric acid was carried out. After the reaction parameters were varied and the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 3. It can be seen that the mass fraction of the 3-hydroxybutyraldehyde aqueous solution has a significant impact on the yield of the oxidation reaction to prepare 3-hydroxybutyric acid.

[0078] Table 3

[0079]

[0080]

[0081] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing 3-hydroxybutyric acid, comprising the following steps: In a fixed-bed reactor, a mixture containing oxygen and 3-hydroxybutyraldehyde is introduced and reacted to obtain a product containing 3-hydroxybutyric acid. The fixed-bed reactor is filled with a catalyst; The 3-hydroxybutyraldehyde is an aqueous solution with a mass fraction of 20~50wt%; The catalyst comprises CuCr2O4 and metal elements; The metallic element is selected from Ag and / or Pt; The mass ratio of CuCr2O4 to the metal element is 100:1~3; The mass ratio of the catalyst to the 3-hydroxybutyraldehyde is 0.5~1:

100.

2. A preparation method according to claim 1, characterized in that, Includes the following steps: 1) Mix raw materials containing copper source, chromium source and solvent I, dry I, and calcine I to obtain CuCr2O4; 2) Mix the raw materials containing the metal element source, CuCr2O4 and solvent II, dry II, and calcine II to obtain the catalyst.

3. The preparation method according to claim 2, characterized in that, The copper source is selected from at least one of copper sulfate, copper chloride, or copper nitrate. The chromium source is selected from chromium trioxide and / or chromium powder; The molar ratio of the copper source to the chromium source is 0.9~2:2; Wherein, the molar amount of the copper source is expressed in terms of the molar amount of copper element; The molar amount of the chromium source is expressed in terms of the molar amount of chromium element; Solvent I is selected from at least one of methanol, ethanol, or acetone; The solid-liquid ratio of the total mass of the copper source and the chromium source to the volume of the solvent I is 1:10~30 g / ml.

4. The preparation method according to claim 2, characterized in that, The temperature of the drying process I is 80~110℃; The drying time for step I is 2-5 hours; The temperature of the calcination I is 600~1200℃; The roasting time for the first stage is 4 to 8 hours.

5. The preparation method according to claim 2, characterized in that, The metal element source is selected from at least one of silver nitrate, silver carbonate, silver sulfate, or chloroplatinic acid; Solvent II is selected from at least one of methanol, ethanol, or acetone; The solid-liquid ratio of the metal element source, CuCr2O4, and solvent II is 1:10~30 g / ml.

6. The preparation method according to claim 2, characterized in that, The temperature of the drying II process is 80~110℃; The drying time for step II is 2-5 hours; The temperature of the second calcination is 500~600℃; The roasting time for the second stage is 4 to 8 hours.

7. The preparation method according to claim 1, characterized in that, The oxygen flow rate is 0.1~0.5 L / min.

8. The preparation method according to claim 1, characterized in that, The reaction temperature is 40~80℃; The reaction time is 3-6 hours.

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