A catalyst for the preparation of octenal, its preparation method and application

Abstract

This application discloses a catalyst for the preparation of octenal, its preparation method, and its application. The catalyst comprises KTiNbO5 and hollow alumina; the content of KTiNbO5 is 4.7–9 wt%; and the content of hollow alumina is 91–95.3 wt%. The catalyst provided in this application can be applied to the butyraldehyde condensation reaction to prepare octenal, improving the conversion rate of butyraldehyde and the selectivity of the generated octenal. The reaction is fast, the yield is high, and it can be applied to large-scale production. The catalyst preparation method is stable, controllable, and reproducible.

Description

Technical Field

[0001] This application relates to a catalyst for the preparation of octenal, a method for its preparation, and its application, belonging to the field of chemical engineering. Background Technology

[0002] The aldol condensation of n-butyraldehyde is an important carbon chain growth step in the production of octanol. The process involves three steps: the aldol condensation of n-butyraldehyde to octenal (i.e., 2-ethyl-2-hexenal), and the hydrogenation of octenal to octanol. Currently, industrially, the aldol condensation of n-butyraldehyde is catalyzed by liquid NaOH. Although a high yield and selectivity of octenal can be obtained, the process is essentially still a catalytic reaction of n-butyraldehyde under alkaline conditions, and still has the following four disadvantages: (1) If the liquid alkali concentration is too low, the condensation reaction is not complete and the conversion rate is low; (2) If the liquid alkali concentration is too high, the aldol condensation reaction is more intense and it is easy to generate trimers or polymers, resulting in more by-products and low selectivity; (3) The discharge of alkaline wastewater is large, which pollutes the environment and incurs high treatment costs; (4) The cost is high. First, a large amount of NaOH is lost with the wastewater, resulting in high catalyst consumption; second, the aqueous phase contains a large amount of product after the reaction, which needs to be extracted by extraction and other processes, increasing the cost; third, the treatment of wastewater requires a large amount of acid, which increases the cost.

[0003] Solid base catalysts have become a focus of research due to their high activity, high selectivity, and ease of separation. Literature reports that solid base catalysts used for the aldol condensation of n-butyraldehyde are mainly metal oxides and supported organic solid bases, achieving activity and selectivity similar to liquid bases. However, their poor stability and difficulty in reusing hinder their industrial application. Solid acids have been reported in some aldol condensation reactions, demonstrating not only high catalytic activity but also good stability, showing broad prospects for industrial application. However, research reports on the application of solid acids in the self-condensation of n-butyraldehyde are limited. Summary of the Invention

[0004] This application constructs a solid acid-base bifunctional catalyst KTiNbO5-Al2O3, which is of great significance for developing a solid catalyst in the reaction of butyraldehyde-hydroxyaldehyde condensation to prepare octenal using a fixed-bed reactor. The catalyst has good activity, high butyraldehyde conversion rate and octenal selectivity, and good stability.

[0005] According to one aspect of this application, a catalyst for preparing octenal is provided, said catalyst comprising KTiNbO5 and hollow alumina;

[0006] The KTiNbO5 content in the catalyst is 4.7–9 wt%.

[0007] Optionally, the KTiNbO5 content in the catalyst is any value from 4.7wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or any range between two.

[0008] The content of hollow alumina is 91–95.3 wt%.

[0009] Optionally, the content of the hollow alumina is any value among 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, and 95.3wt%, or a range between any two.

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

[0011] (1) Preparation of KTiNbO5 by molten salt method;

[0012] (2) The KTiNbO5 obtained in (1) is mixed with hollow alumina and calcined to obtain the catalyst.

[0013] The process of preparing KTiNbO5 by the molten salt method includes the following steps:

[0014] The raw materials containing titanium source, niobium source, molten salt and solvent are mixed and calcined to obtain KTiNbO5.

[0015] The titanium source is selected from titanium dioxide and / or titanium powder;

[0016] The niobium source is selected from niobium pentoxide and / or niobium powder;

[0017] The molten salt is K2CO3;

[0018] The solvent is selected from at least one of methanol, ethanol, and acetone.

[0019] The molar ratio of the titanium source to the niobium source, calculated as the molar ratio of titanium in the titanium source to niobium in the niobium source, is 1:(0.9~1).

[0020] The molar ratio of the titanium source to the molten salt, calculated as the molar ratio of titanium in the titanium source to potassium in the molten salt, is 1:(0.9~1).

[0021] The solid-liquid ratio of the titanium source, niobium source, molten salt and solvent is 1:(2-3).

[0022] Optionally, the solid-liquid ratio of the titanium source, niobium source, molten salt and solvent is any value of 1:2, 1:3 or any range between the two.

[0023] The raw materials containing titanium source, niobium source, molten salt and solvent are mixed and then subjected to ultrasonication, grinding, drying and calcination.

[0024] The drying temperature is 80–110°C;

[0025] Optionally, the drying temperature is any value among 80°C, 90°C, 100°C, and 110°C, or a range between any two.

[0026] The drying time is 2 to 5 hours.

[0027] Optionally, the drying time is any value among 2h, 3h, 4h, and 5h, or a range between any two.

[0028] The roasting temperature is 600–1200℃;

[0029] Optionally, the calcination temperature is any value among 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, and 1200℃, or a range between any two.

[0030] The roasting time is 4 to 8 hours.

[0031] Optionally, the roasting time is any value among 4h, 5h, 6h, 7h, and 8h, or a range between any two.

[0032] After roasting, the food must be washed.

[0033] The hollow alumina is obtained through the following steps:

[0034] Weigh Al(NO3)3·9H2O, add anhydrous ethanol solution to prepare an aluminum nitrate ethanol solution. Add carbon spheres, sonicate, and let stand. Filter, dry, and sinter to obtain hollow alumina spheres.

[0035] The solid-liquid ratio of the carbon spheres, Al(NO3)39H2O and anhydrous ethanol is 1:(30-50):(200-300)g / ml;

[0036] Optionally, the upper limit of the solid-liquid ratio of the carbon spheres, Al(NO3)39H2O and anhydrous ethanol is 1:30:200g / ml or 1:40:250g / ml, and the lower limit is selected from 1:50:300g / ml or 1:40:250g / ml.

[0037] The duration of the ultrasound is 10–60 minutes;

[0038] Optionally, the ultrasound duration is any value among 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min, or a range between any two.

[0039] The settling time is 4 to 10 hours;

[0040] Optionally, the settling time is any value among 4h, 5h, 6h, 7h, 8h, 9h, and 10h, or a range between any two.

[0041] The drying temperature is 100℃~120℃;

[0042] Optionally, the drying temperature is any value among 100°C, 110°C, and 120°C, or a range between any two.

[0043] The drying time is 6–12 hours;

[0044] Optionally, the drying time is any value among 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two.

[0045] The sintering temperature is 500℃~600℃;

[0046] Optionally, the sintering temperature is any value among 500°C, 550°C, and 600°C, or a range between any two.

[0047] The sintering time is 4 to 8 hours.

[0048] Optionally, the sintering time is any value among 4h, 5h, 6h, 7h, and 8h, or a range between any two.

[0049] The mixing method of KTiNbO5 and hollow alumina is selected from either mechanical mixing or wet mixing.

[0050] The mass ratio of KTiNbO5 to hollow alumina is 1:(10-20);

[0051] Optionally, the mass ratio of KTiNbO5 to hollow alumina is any value among 1:10, 1:15, and 1:20, or any range between the two.

[0052] The calcination temperature is 500–600°C;

[0053] Optionally, the calcination temperature is any value among 500°C, 550°C, and 600°C, or a range between any two.

[0054] The calcination time is 4 to 8 hours.

[0055] Optionally, the calcination time is any value among 4h, 5h, 6h, 7h, and 8h, or a range between any two.

[0056] According to another aspect of this application, a method for preparing octenal is provided, comprising the following steps:

[0057] A material containing butyraldehyde is introduced into the reactor, where it comes into contact with the catalyst and reacts to obtain a material containing octenal.

[0058] The catalyst is selected from the catalysts described above or the catalysts prepared by the preparation method described above.

[0059] In the material, the space time of butyraldehyde is 0.1–10 g·min / ml.

[0060] Optionally, the space time of butyraldehyde in the material is any value or a range between any two of 0.1 g·min / ml, 0.5 g·min / ml, 1 g·min / ml, 2 g·min / ml, 3 g·min / ml, 4 g·min / ml, 5 g·min / ml, 6 g·min / ml, 7 g·min / ml, 8 g·min / ml, 9 g·min / ml, and 10 g·min / ml.

[0061] The reaction temperature is 100–200°C;

[0062] Optionally, the temperature of the reaction is any value or a range between 100°C, 120°C, 140°C, 160°C, 180°C, and 200°C.

[0063] The reaction time is 3 to 5 hours;

[0064] Optionally, the reaction time is any value among 3h, 4h, and 5h, or a range between any two.

[0065] The reaction is carried out at a pressure of 1–5 MPa.

[0066] Optionally, the pressure of the reaction is any value of 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, or a range between any two.

[0067] The reactor is a fixed-bed reactor.

[0068] The catalyst is packed into the 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 butyraldehyde condensation reaction to prepare octenal, and improves the conversion rate of butyraldehyde and the selectivity of the generated octenal.

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

[0072] 3) The method for preparing octenal by butyraldehyde condensation 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 of KTiNbO5. Detailed Implementation

[0074] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0075] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially. The gas chromatograph used was an Agilent 7890B gas chromatograph.

[0076] Examples 1-28

[0077] Preparation of catalysts

[0078] Taking item 1 in Table 1 as an example, titanium dioxide and niobium pentoxide with a titanium-niobium molar ratio of 1:1 were mixed with molten salt K2CO3 in an ethanol solution (the molar ratio of titanium in the titanium source to K in the molten salt was 1:1). After ultrasonication, the mixture was 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 KTiNbO5. Al(NO3)39H2O was weighed and anhydrous ethanol solution was added (the solid-liquid ratio of carbon spheres, Al(NO3)39H2O, and anhydrous ethanol was 1:40:250 g / ml) to prepare an aluminum nitrate ethanol solution. Carbon spheres were added, and the mixture was ultrasonicated for 30 minutes and then allowed to stand for 8 hours. After filtration, the mixture was dried at 100℃ for 10 hours and sintered at 550℃ for 4 hours to obtain hollow alumina. KTiNbO5 and hollow alumina were mixed at a mass ratio of 1:15 using a wet mixing method, and then calcined at 550℃ for 4 hours to obtain KTiNbO5-Al2O3, which was designated as catalyst 1. # .

[0079] 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:

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085]

[0086]

[0087]

[0088] The explanations for columns 1 and 2 above are as follows:

[0089] Titanium source: titanium dioxide (Ti1), titanium powder (Ti2).

[0090] Niobium source: Niobium pentoxide (Nb1), niobium powder (Nb2).

[0091] Lava: K2CO3 (K1).

[0092] Solvents: methanol (solution 1), ethanol (solution 2), acetone (solution 3).

[0093] Drying: Drying during the preparation of KTiNbO5.

[0094] Drying: Drying during the preparation of hollow alumina.

[0095] Calcination: Calcination during the preparation of KTiNbO5.

[0096] Sintering: Calcination during the preparation of hollow alumina.

[0097] Calcination: Calcination during the preparation of KTiNbO5-Al2O3 catalyst.

[0098] Mixing methods: mechanical mixing (method 1), wet mixing (method 2).

[0099] XRD characterization

[0100] Catalyst 1 was analyzed using a Miniflex 600 X-ray diffractometer with a Cu target. # Powder diffraction yielded catalyst 1. # The diffraction peaks of KTiNbO5 conform to the characteristic peaks of KTiNbO5 (e.g., Figure 1 (As shown).

[0101] Gas chromatography characterization

[0102] The composition of the butyraldehyde condensation reaction products was analyzed using an Agilent 7890B gas chromatograph (FID detector, HP-5 capillary column).

[0103] The conversion rate and selectivity calculation formulas in the embodiments of this application are as follows (with butyraldehyde conversion rate as the evaluation index):

[0104] Butyraldehyde conversion rate = (initial carbon number of butyraldehyde - carbon number of butyraldehyde in the product) * 100 / initial molar number of butyraldehyde

[0105] Octenal selectivity = (number of carbon atoms in octenal) * 100 / ∑(number of carbon atoms in octenal + number of carbon atoms in other products)

[0106] Example 29

[0107] The catalyst is used in the butyraldehyde condensation reaction to prepare octenal.

[0108] Catalysts 1 to 28 prepared in Example 1 # ~Catalyst 28 # The catalyst is used to prepare octenal by butyraldehyde condensation. The reaction is carried out at a temperature of 180°C, a reaction time of 4 hours, a reaction pressure of 2 MPa, and a raw material space time of 1 g·min / ml. The raw material is fed into a fixed-bed reactor carrying 3 g of the catalyst to produce octenal by condensation reaction.

[0109] After the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 3.

[0110] Table 3

[0111]

[0112]

[0113] As can be seen from the table, catalyst 1 produces the highest yield in this reaction.

[0114] Example 30

[0115] Catalyst 1 prepared in Table 1 # The reaction to prepare octenal by butyraldehyde condensation was carried out. After the reaction parameters were changed and the reaction stabilized, the reactants and products were analyzed by online gas chromatography. The reaction results are shown in Table 4.

[0116] Table 4

[0117]

[0118]

[0119] The table shows that temperature has a significant impact on the reaction.

[0120] 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 catalyst for the preparation of octenal, characterized in that, The catalyst comprises KTiNbO5 and hollow alumina; The KTiNbO5 content in the catalyst is 4.7~9 wt%. The content of the hollow alumina is 91~95.3 wt%; The method for preparing the catalyst includes the following steps: (1) Preparation of KTiNbO5 by molten salt method; (2) The KTiNbO5 obtained in (1) is mixed with hollow alumina and calcined to obtain the catalyst.

2. The catalyst according to claim 1, characterized in that, In step (1), the process of preparing KTiNbO5 by the molten salt method includes the following steps: The raw materials containing titanium source, niobium source, molten salt and solvent are mixed and calcined to obtain KTiNbO5.

3. The catalyst according to claim 2, characterized in that, The titanium source is selected from titanium dioxide and / or titanium powder; The niobium source is selected from niobium pentoxide and / or niobium powder; The molten salt is K2CO3; The solvent is selected from at least one of methanol, ethanol, and acetone.

4. The catalyst according to claim 3, characterized in that, The molar ratio of the titanium source to the niobium source, calculated as the molar ratio of titanium in the titanium source to niobium in the niobium source, is 1:(0.9~1). The molar ratio of the titanium source to the molten salt, calculated as the molar ratio of titanium in the titanium source to potassium in the molten salt, is 1:(0.9~1). The solid-liquid ratio of the sum of the titanium source, niobium source, and molten salt to the solvent is 1:(2~3).

5. The catalyst according to claim 2, characterized in that, The roasting temperature is 600~1200℃; The roasting time is 4 to 8 hours.

6. The catalyst according to claim 1, characterized in that, The mass ratio of KTiNbO5 to hollow alumina is 1:(10~20). The calcination temperature is 500~600℃; The calcination time is 4-8 hours.

7. A method for preparing octenal, characterized in that, Includes the following steps: A material containing butyraldehyde is introduced into the reactor, where it comes into contact with the catalyst and reacts to obtain a material containing octenal. The catalyst is selected from the catalysts described in any one of claims 1 to 6.

8. The method according to claim 7, characterized in that, In the material, the space time of butyraldehyde is 0.1 ~ 10 g·min / ml.

9. The method according to claim 7, characterized in that, The reaction temperature is 100~200℃; The reaction time is 3-5 hours; The reaction is carried out at a pressure of 1-5 MPa.

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