A catalyst, its preparation method and use in the preparation of 3-hydroxybutyric acid

Abstract

The application discloses a catalyst and a preparation method and application thereof in preparation of 3-hydroxybutyric acid. The catalyst comprises TiO2 and Ti3C2, and is used in an oxidation reaction for preparing 3-hydroxybutyric acid. The application further discloses a preparation method of the catalyst, which comprises the following steps: preparing Ti3AlC2 by using a high-temperature calcination method, immersing the Ti3AlC2 in a hydrofluoric acid solution, washing for several times, and drying to obtain Ti3C2; mixing the Ti3C2 and sodium tetrafluoroborate in a hydrochloric acid solution, and performing a hydrothermal reaction; and washing and drying to obtain the catalyst. The application further discloses a method for preparing 3-hydroxybutyric acid by using the catalyst in an oxidation reaction.

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-HB) is the monomeric form of the natural polymer poly(R)-3-hydroxybutyrate (hereinafter referred to as PHB), existing naturally in its pure R configuration. As an important ketone body in the body, 3-hydroxybutyric acid is produced by the degradation of long-chain fatty acids in the liver, transported through the bloodstream to peripheral tissues, and plays a regulatory role in bodily functions. Existing literature reports its significant application value and prospects in the health supplement, food, and pharmaceutical industries, including: accelerating weight loss; stimulating the expression of various health-promoting genes; reducing the incidence of inflammatory complications; improving exercise performance and training efficiency; enhancing metabolic efficiency; providing optimal energy for the heart and reducing the incidence of cardiovascular disease; improving insulin sensitivity; preventing cancer and diseases related to glucose metabolism disorders; increasing cognitive ability, preventing Alzheimer's disease, and extending lifespan. It also finds applications in environmental protection materials and packaging materials, especially in single-use plastic products. Furthermore, it has unique applications in biofunctional materials. Therefore, the chemical synthesis research of 3-hydroxybutyric acid has significant environmental and economic implications.

[0003] Currently, the preparation of 3-hydroxybutyric acid using biochemical or fermentation methods is costly, has low yield, and is expensive. Hydrolysis produces few byproducts, but the cyanide is highly toxic and pollutes the environment. Acetaldehyde and acetic acid prepared under the catalysis of lithium naphthylene have readily available raw materials, few side reactions, and are easily scalable for continuous production. While lithium naphthylene is used in large quantities, it only acts as a catalyst and can be reused, thus holding potential for industrial production. Oxidation methods, due to the presence of hydroxyl groups in the raw materials, require relatively low temperatures and pressures. Large-scale industrial production of 3-hydroxybutyric acid is not yet possible; it is prepared from acetaldehyde via an aldol condensation reaction. Summary of the Invention

[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.

[0005] According to one aspect of this application, a catalyst is provided, said catalyst comprising TiO2 and Ti3C2;

[0006] The sheet-like TiO2 is embedded in the Ti3C2 layered structure.

[0007] 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.

[0008] According to another aspect of this application, a method for preparing the above-mentioned catalyst is provided, comprising the following steps:

[0009] a. Preparation of Ti3AlC2 by high-temperature calcination;

[0010] b. The Ti3AlC2 obtained in step a is immersed in a solution containing hydrofluoric acid to obtain Ti3C2;

[0011] c. The Ti3C2 obtained in b is mixed with sodium tetrafluoroborate and hydrochloric acid solution, and subjected to hydrothermal reaction to obtain the catalyst.

[0012] The high-temperature calcination method for preparing Ti3AlC2 includes the following steps:

[0013] The raw materials containing titanium source, aluminum source and carbon powder are mixed and calcined to obtain Ti3AlC2.

[0014] The titanium source is selected from titanium powder;

[0015] The aluminum source is selected from aluminum powder;

[0016] The molar ratio of the titanium source, aluminum source and carbon powder is 3:(0.9~1):2;

[0017] Optionally, the molar ratio of the titanium source, aluminum source and carbon powder is any value among 3:0.9:2, 3:0.95:2, 3:1:2 or any range between the two.

[0018] The calcination temperature is 1000–1400℃;

[0019] Optionally, the calcination temperature is any value among 1000℃, 1100℃, 1200℃, 1300℃, and 1400℃, or a range between any two.

[0020] The calcination time is 1 to 6 hours.

[0021] Optionally, the calcination time is any value among 1h, 2h, 3h, 4h, 5h, and 6h, or a range between any two.

[0022] The concentration of hydrofluoric acid in the solution containing hydrofluoric acid is 30-50 wt%.

[0023] Optionally, the concentration of hydrofluoric acid in the solution containing hydrofluoric acid is any value among 30wt%, 35wt%, 40wt%, 45wt%, and 50wt%, or a range between any two.

[0024] The solid-liquid ratio of the Ti3AlC2 obtained in step a to the hydrofluoric acid-containing solution is 1:(10-30)g / ml;

[0025] Optionally, the solid-liquid ratio of the Ti3AlC2 obtained in step a to the hydrofluoric acid-containing solution is any value among 1:10 g / ml, 1:15 g / ml, 1:20 g / ml, 1:25 g / ml, and 1:30 g / ml, or any range between two of them.

[0026] The impregnation temperature is 40–80°C;

[0027] Optionally, the impregnation temperature is any value among 40°C, 50°C, 60°C, 70°C, and 80°C, or a range between any two.

[0028] The soaking time is 28–112 hours;

[0029] Optionally, the immersion time is any value among 28h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, 110h, and 112h, or a range between any two.

[0030] The Ti3C2 was dried (I);

[0031] The temperature of the drying process I is 60–100°C;

[0032] Optionally, the temperature of the drying I is any value among 60°C, 70°C, 80°C, 90°C, and 100°C, or a range between any two.

[0033] The drying time is 12 to 36 hours.

[0034] Optionally, the drying time is any value among 12h, 18h, 24h, 30h, and 36h, or a range between any two.

[0035] The mass ratio of Ti3C2 obtained in b to sodium tetrafluoroborate is 1:(1-2);

[0036] Optionally, the mass ratio of Ti3C2 to sodium tetrafluoroborate obtained in step b is any value among 1:1, 1:1.5, and 1:2, or any range between the two.

[0037] The concentration of the hydrochloric acid is 1M to 3M;

[0038] Optionally, the concentration of the hydrochloric acid is any value among 1M, 2M, and 3M, or a range between any two.

[0039] The solid-liquid ratio of the solid Ti3C2 and sodium tetrafluoroborate to the liquid hydrochloric acid solution is 1:(40-70)g / ml;

[0040] Optionally, the solid-liquid ratio of the solid Ti3C2 and sodium tetrafluoroborate to the liquid hydrochloric acid solution is any value among 1:40 g / ml, 1:50 g / ml, 1:60 g / ml, and 1:70 g / ml, or any range between two of them.

[0041] The temperature of the hydrothermal reaction is 140–180°C;

[0042] Optionally, the temperature of the hydrothermal reaction is any value among 140°C, 150°C, 160°C, 170°C, and 180°C, or a range between any two.

[0043] The hydrothermal reaction time is 6–24 hours;

[0044] Optionally, the hydrothermal reaction time is any value among 6h, 12h, 18h, and 24h, or a range between any two.

[0045] The catalyst is dried (II);

[0046] The temperature of the drying II process is 60–100°C;

[0047] Optionally, the temperature of the drying II is any value among 60°C, 70°C, 80°C, 90°C, and 100°C, or a range between any two.

[0048] The drying time for step II is 12–36 hours.

[0049] Optionally, the drying time II is any value among 12h, 18h, 24h, 30h, and 36h, or a range between any two.

[0050] The Ti3C2 and the catalyst are washed before drying I or drying II;

[0051] The solvent used for washing is selected from water and / or ethanol.

[0052] The washing process is repeated multiple times.

[0053] According to one aspect of this application, a method for preparing 3-hydroxybutyric acid is provided.

[0054] Includes the following steps:

[0055] In a reactor, an aqueous solution containing oxygen and 3-hydroxybutyraldehyde is introduced into contact with a catalyst and reacted to obtain a product containing 3-hydroxybutyric acid.

[0056] The catalyst is selected from the catalysts described above or the catalysts prepared by the preparation method described above.

[0057] In the aqueous solution containing 3-hydroxybutyraldehyde, the mass fraction of 3-hydroxybutyraldehyde is 20-50 wt%.

[0058] Optionally, in the aqueous solution containing 3-hydroxybutyraldehyde, the mass fraction of 3-hydroxybutyraldehyde is any value among 20wt%, 30wt%, 40wt%, and 50wt%, or any range between two.

[0059] The oxygen flow rate is 0.1–0.5 L / min;

[0060] Optionally, 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.

[0061] The mass ratio of the catalyst to the 3-hydroxybutyraldehyde is (0.2-1):100;

[0062] Optionally, the mass ratio of the catalyst to the 3-hydroxybutyraldehyde is any value from 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, or any value between both.

[0063] The 3-hydroxybutyraldehyde is defined as the mass of 3-hydroxybutyraldehyde in the aqueous solution containing 3-hydroxybutyraldehyde.

[0064] The reaction temperature is 40–80°C;

[0065] Optionally, the temperature of the reaction is any value among 40°C, 50°C, 60°C, 70°C, and 80°C, or a range between any two.

[0066] The reaction time is 3 to 6 hours.

[0067] Optionally, the reaction time is any value among 3h, 4h, 5h, and 6h, or a range between any two.

[0068] The reactor is a fixed-bed reactor.

[0069] The beneficial effects that this application can produce include:

[0070] 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.

[0071] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.

[0072] 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

[0073] Figure 1 Catalyst 1 # X-ray powder diffraction pattern.

[0074] Figure 2 Catalyst 1 # Scanning electron microscope image. Detailed Implementation

[0075] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0076] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0077] The gas chromatograph used was an Agilent 7890B gas chromatograph.

[0078] Examples 1-28

[0079] Preparation of catalysts

[0080] Taking item 1 in Table 1 as an example, titanium powder, aluminum powder, and carbon powder in a molar ratio of 3:1:2 were ground to obtain a mixture. The mixture was calcined at 1400℃ for 2 hours to obtain Ti3AlC2. Ti3AlC2 was then soaked in a 40wt% hydrofluoric acid solution at 60℃ for 56 hours (the solid-liquid ratio of Ti3AlC2 to hydrofluoric acid solution was 1:20 g / ml). After washing several times with ethanol, it was dried in an oven at 70℃ for 24 hours to obtain Ti3C2. Ti3C2 in a mass ratio of 1:1.5 was mixed with sodium tetrafluoroborate in a 1M hydrochloric acid solution (the solid-liquid ratio was 1:50). The mixture was then subjected to a hydrothermal reaction at 160℃ for 24 hours. After washing several times with ethanol, it was dried in an oven at 70℃ for 24 hours to obtain Ti3C2 / TiO2, which was designated as catalyst 1. # .

[0081] 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:

[0082] Table 1

[0083]

[0084]

[0085] Table 2

[0086]

[0087]

[0088]

[0089] The columns in Tables 1 and 2 above are explained as follows:

[0090] Titanium source: Titanium powder (Ti1).

[0091] Aluminum source: Aluminum powder (Al1).

[0092] Toner (C1).

[0093] Solvents for the first wash: deionized water (solution 1), ethanol (solution 2), and a mixed solution of deionized water and ethanol (solution 3).

[0094] Solvents for the second wash: deionized water (solution 1), ethanol (solution 2), and a mixed solution of deionized water and ethanol (solution 3).

[0095] First drying: Drying during the preparation of Ti3AlC2.

[0096] Secondary drying: Drying of Ti3C2 / TiO2 preparation.

[0097] XRD characterization

[0098] Catalyst 1 was analyzed using a Miniflex 600 X-ray diffractometer with a Cu target. # Powder diffraction of Ti3C2 / TiO2 yielded catalyst 1. # The diffraction peaks of Ti3C2 / TiO2 conform to the characteristic peaks of Ti3C2 / TiO2 (e.g., Figure 1 (As shown).

[0099] SEM characterization

[0100] Scanning electron microscopy (SEM) (JSM-7800F) on catalyst 1 # Morphology of Ti3C2 / TiO2 (e.g.) Figure 2 As shown in the figure, after the hydrothermal reaction, the lamellar TiO2 structure is embedded into the Ti3C2 layered structure.

[0101] Example 29

[0102] The catalyst is used in the oxidation reaction to prepare 3-hydroxybutyric acid.

[0103] 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.

[0104] After the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 3.

[0105] Table 3

[0106]

[0107]

[0108] As can be seen from the table, the catalyst prepared in this patent is used for the oxidation reaction to prepare 3-hydroxybutyric acid, and the yield of 3-hydroxybutyric acid is not significantly different.

[0109] Example 30

[0110] 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 4.

[0111] Table 4

[0112]

[0113]

[0114] As can be seen from the table, the mass fraction (%) of 3-hydroxybutyraldehyde aqueous solution has a significant impact on the yield (%) of 3-hydroxybutyric acid in the oxidation reaction to prepare 3-hydroxybutyric acid.

[0115] 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, characterized in that, Includes the following steps: In a reactor, an aqueous solution containing oxygen and 3-hydroxybutyraldehyde is introduced into contact with a catalyst and reacted to obtain a product containing 3-hydroxybutyric acid. In the aqueous solution containing 3-hydroxybutyraldehyde, the mass fraction of 3-hydroxybutyraldehyde is 20-50 wt%. The oxygen flow rate is 0.2~0.5 L / min; The mass ratio of the catalyst to the 3-hydroxybutyraldehyde is (0.4~1):100; The 3-hydroxybutyraldehyde is defined as the mass of 3-hydroxybutyraldehyde in the aqueous solution containing 3-hydroxybutyraldehyde; The catalyst is characterized in that, The catalyst includes TiO2 and Ti3C2; TiO2 with a sheet-like structure is embedded in the Ti3C2 layered structure.

2. A method for preparing 3-hydroxybutyric acid according to claim 1, characterized in that, Includes the following steps: a. Preparation of Ti3AlC2 by high-temperature calcination; b. The Ti3AlC2 obtained in step a is immersed in a solution containing hydrofluoric acid to obtain Ti3C2; c. The Ti3C2 obtained in b is mixed with sodium tetrafluoroborate and hydrochloric acid solution, and subjected to hydrothermal reaction to obtain the catalyst.

3. The method according to claim 2, characterized in that, The high-temperature calcination method for preparing Ti3AlC2 includes the following steps: The raw materials containing titanium source, aluminum source and carbon powder are mixed and calcined to obtain Ti3AlC2.

4. The method according to claim 3, characterized in that, The titanium source is selected from titanium powder; The aluminum source is selected from aluminum powder; The molar ratio of the titanium source, aluminum source and carbon powder is 3:(0.9~1):2; The calcination temperature is 1000~1400℃; The calcination time is 1 to 6 hours.

5. The method according to claim 2, characterized in that, The concentration of hydrofluoric acid in the solution is 30-50 wt%. The solid-liquid ratio of the Ti3AlC2 obtained in step a to the hydrofluoric acid-containing solution is 1:(10~30)g / ml; The impregnation temperature is 40~80℃; The soaking time is 28~112 hours; The Ti3C2 was dried (I); The temperature of the drying process I is 60~100℃; The drying time for step I is 12-36 hours.

6. The method according to claim 2, characterized in that, The mass ratio of Ti3C2 obtained in b to sodium tetrafluoroborate is 1:(1~2). The concentration of the hydrochloric acid is 1M to 3M; The solid-liquid ratio of the solid mixture of Ti3C2 and sodium tetrafluoroborate to the hydrochloric acid solution is 1:(40~70) g / ml; The temperature of the hydrothermal reaction is 140~180℃; The hydrothermal reaction time is 6~24 hours; The catalyst is dried (II); The temperature of the drying II process is 60~100℃; The drying time for step II is 12 to 36 hours.

7. The method according to any one of claims 5 or 6, characterized in that, The Ti3C2 and the catalyst are washed before drying I or drying II; The solvent used for washing is selected from water and / or ethanol.

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

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