A manganese-based catalyst, its preparation method and use

Abstract

The application discloses a manganese-based catalyst and a preparation method and application thereof. The manganese-based catalyst is composed of MnO and Mn3N2. The application further discloses a preparation method of the catalyst, which comprises the following steps: preparing a MnO / Mn3N2 mixture by using an ammonia nitriding method, and obtaining the catalyst. The application further discloses a method for preparing 3-hydroxybutyraldehyde by using the catalyst to perform an acetaldehyde condensation reaction.

Description

Technical Field

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

[0002] Aldol condensation can proceed under both acidic and alkaline conditions. Homogeneous and heterogeneous aldol condensation have also been studied, especially gas-solid phase aldol condensation under solid catalysts, which has been applied to the condensation reactions of some aldehydes and ketones with good results. In the aldol condensation reaction of acetaldehyde under alkaline conditions, 3-hydroxybutyraldehyde is first formed. 3-hydroxybutyraldehyde readily loses one molecule of water upon heating to form butenal. To inhibit product dehydration, a low-temperature reaction is employed.

[0003] Acetaldehyde can undergo a liquid-phase aldol condensation reaction catalyzed by NaOH solution. The basic technical characteristics are: NaOH solution as a catalyst, liquid-phase reaction, the degree of condensation mainly controlled by the contact time between NaOH and acetaldehyde solutions, and the need to add acetic acid to neutralize the catalytic effect of NaOH and thus stop further condensation. It has been reported that the condensation reaction temperature is controlled at 40-50℃, the reaction pressure at 0.05 MPa, and the condensation rate at 60-65%.

[0004] Chinese invention patent (CN100450986C) discloses a method for preparing 1,3-butanediol, which first prepares 3-hydroxybutanal by adding a small amount of carboxylic acid to sodium hydroxide, and then hydrogenates it to prepare 1,3-butanediol. Chinese invention patent (CN1807381A) discloses a method for preparing butenal, which uses a weak base organic amine as a catalyst to condense acetaldehyde to generate 2-hydroxybutanal, and then dehydrates 2-hydroxybutanal under acidic conditions to form butenal. Chinese invention patents (CN105585448A), (CN110790634A), (CN206396080U), and (CN208883742U) disclose a two-step process for preparing 1,3-butanediol from acetaldehyde using acetaldehyde as a raw material, first condensing it under an alkaline catalyst to generate 3-hydroxybutanal, and then hydrogenating it. The aforementioned patents all use batch reactors and liquid alkalis (such as NaOH, KOH, LiOH, trimethylamine, and triethylamine) as catalysts. Due to the high viscosity of 3-hydroxybutyraldehyde, its easy dehydration after prolonged contact with the catalyst or at high temperatures makes further purification very difficult. The subsequent product refining process is cumbersome, increases production costs, and seriously affects the purity and price of the product. Summary of the Invention

[0005] The catalyst prepared in this patent is used in the reaction of acetaldehyde condensation to prepare 3-hydroxybutyraldehyde. The catalyst has good activity, high acetaldehyde conversion rate and high selectivity for 3-hydroxybutyraldehyde, and good stability.

[0006] According to one aspect of this application, a manganese-based catalyst is provided, wherein the manganese-based catalyst is composed of MnO and Mn3N2;

[0007] The Mn3N2 is loaded on the surface of the MnO.

[0008] The manganese-based catalyst is used in the condensation reaction of acetaldehyde to prepare 3-hydroxybutyraldehyde, and improves the conversion rate of acetaldehyde and the selectivity of 3-hydroxybutyraldehyde.

[0009] According to another aspect of this application, a method for preparing the above-mentioned manganese-based catalyst is provided, comprising the following steps:

[0010] The manganese-based catalyst was prepared by ammonia nitridation.

[0011] The specific steps of the ammonia nitridation method include:

[0012] Manganese dioxide was nitrided under an ammonia atmosphere.

[0013] The nitriding treatment temperature is 600–900°C;

[0014] Optionally, the nitriding temperature is any value among 600°C, 700°C, 800°C, and 900°C, or a range between any two.

[0015] The nitriding treatment time is 8 to 16 hours.

[0016] Optionally, the nitriding treatment time is any value among 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, and 16h, or a range between any two.

[0017] The nitriding treatment is carried out in a high-temperature calcining furnace.

[0018] According to another aspect of this application, a method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction is provided, characterized in that...

[0019] Includes the following steps:

[0020] An aqueous solution containing acetaldehyde was introduced into the reactor and reacted with the catalyst to obtain a product containing 3-hydroxybutyraldehyde.

[0021] The catalyst is selected from the manganese-based catalysts described above or the manganese-based catalysts prepared by the above preparation method.

[0022] The reactor is a fixed-bed reactor.

[0023] In the aqueous solution containing acetaldehyde, the mass ratio of acetaldehyde to water is 3:1 to 3:9.

[0024] Optionally, in the aqueous solution containing acetaldehyde, the mass ratio of acetaldehyde to water is any value or a range between any two of 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8, and 3:9.

[0025] The mass hourly space velocity (MSV) of the aqueous solution containing acetaldehyde is 0.1 h⁻¹. -1 ~1.5h -1 .

[0026] Optionally, the mass hourly space velocity (MSV) of the acetaldehyde-containing aqueous solution is 0.1 h⁻¹. -1 0.5h -1 1.0h -1 1.5h -1 Any value in the range or any value between the two.

[0027] The reaction temperature is 15–45°C;

[0028] Optionally, the temperature of the reaction is any value of 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, or 45°C, or a range between any two.

[0029] The reaction time is 2 to 3 hours.

[0030] Optionally, the reaction time is any value among 2h, 2.5h, and 3h, or a range between any two.

[0031] The beneficial effects that this application can produce include:

[0032] 1) The catalyst provided in this application can be applied to the acetaldehyde condensation reaction to prepare 3-hydroxybutyraldehyde, and improves the conversion rate of acetaldehyde and the selectivity of the generated 3-hydroxybutyraldehyde.

[0033] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.

[0034] 3) The method for preparing 3-hydroxybutyraldehyde by acetaldehyde 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

[0035] Figure 1 Catalyst 1 # 10 # 18 # 19 # and 27 # X-ray powder diffraction pattern. Detailed Implementation

[0036] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0037] 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.

[0038] Examples 1-28

[0039] Preparation of catalysts

[0040] Taking item 1 in Table 1 as an example, manganese dioxide was placed in a high-temperature calcining furnace and nitrided in an ammonia atmosphere at a nitriding temperature of 600℃ for 6 hours. The resulting MnO / Mn3N2 mixture was designated as catalyst 1. # .

[0041] 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:

[0042] Table 1

[0043]

[0044]

[0045] XRD characterization

[0046] Catalyst 1 was analyzed using a Miniflex 600 X-ray diffractometer with a Cu target. # Powder diffraction yielded catalyst 1. # 10 # 18 # 19 # and 27 # The diffraction peaks match the characteristic peaks of MnO / Mn3N2 (e.g. Figure 1 (As shown).

[0047] Gas chromatography characterization

[0048] The composition of the acetaldehyde condensation reaction products was analyzed using an Agilent 7890B gas chromatograph (FID detector, HP-5 capillary column).

[0049] The conversion rate and selectivity calculation formulas in the embodiments of this application are as follows (using acetaldehyde conversion rate as the evaluation index):

[0050] Acetaldehyde conversion rate = (initial carbon number of acetaldehyde - carbon number of acetaldehyde in the product) * 100 / initial molar number of acetaldehyde

[0051] 3-Hydroxybutyraldehyde selectivity = (number of carbon atoms in 3-hydroxybutyraldehyde) * 100 / ∑(number of carbon atoms in 3-hydroxybutyraldehyde + number of carbon atoms in other products)

[0052] Example 29

[0053] The catalyst is used in the reaction of acetaldehyde condensation to prepare 3-hydroxybutyraldehyde.

[0054] Catalysts 1 to 28 prepared in Example 1 # ~Catalyst 28 # This compound was used to prepare 3-hydroxybutyraldehyde by acetaldehyde condensation. The mass ratio of acetaldehyde to deionized water in the raw materials was 3:3. The reaction was carried out at a temperature of 35°C for 2 hours and a mass hourly space velocity (HHSV) of 0.5 h⁻¹. -1 The raw materials are fed into a fixed-bed reactor containing 3g of the catalyst, and a condensation reaction is carried out to produce 3-hydroxybutyraldehyde.

[0055] After the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 2.

[0056] Table 2

[0057]

[0058]

[0059] As can be seen from the table, the catalyst prepared in this patent is used in the reaction of acetaldehyde condensation to prepare 3-hydroxybutyraldehyde, and the difference between the acetaldehyde conversion rate and the selectivity of 3-hydroxybutyraldehyde is not significant.

[0060] Example 30

[0061] Catalyst 1 prepared in Table 1 # The reaction to prepare 3-hydroxybutyraldehyde by acetaldehyde 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 3.

[0062] Table 3

[0063]

[0064]

[0065] The table shows that the reaction temperature has a significant impact on the acetaldehyde conversion rate in the acetaldehyde condensation reaction to prepare 3-hydroxybutyraldehyde.

[0066] 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-hydroxybutyraldehyde by acetaldehyde condensation reaction, characterized in that, Includes the following steps: An aqueous solution containing acetaldehyde was introduced into the reactor and reacted with the catalyst to obtain a product containing 3-hydroxybutyraldehyde. The catalyst is a manganese-based catalyst, and the manganese-based catalyst components are MnO and Mn3N2; The Mn3N2 is loaded on the surface of the MnO; The reaction temperature is 25~45℃.

2. A method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction as described in claim 1, characterized in that, The preparation method of the manganese-based catalyst includes the following steps: The manganese-based catalyst was prepared by ammonia nitridation.

3. The method according to claim 2, characterized in that, The specific steps of the ammonia nitridation method include: Manganese dioxide was nitrided under an ammonia atmosphere.

4. The method according to claim 3, characterized in that, The nitriding treatment temperature is 600~900℃; The nitriding treatment time is 8~16 hours.

5. The method according to claim 3, characterized in that, The nitriding treatment is carried out in a high-temperature calcining furnace.

6. The method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction according to claim 1, characterized in that, The reactor is a fixed-bed reactor.

7. The method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction according to claim 1, characterized in that, In the aqueous solution containing acetaldehyde, the mass ratio of acetaldehyde to water is 3:1 to 3:

9.

8. The method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction according to claim 1, characterized in that, The mass hourly space velocity (MSV) of the aqueous solution containing acetaldehyde is 0.1 h⁻¹. -1 ~ 1.5 h -1 .

9. The method for preparing 3-hydroxybutyraldehyde by acetaldehyde condensation reaction according to claim 1, characterized in that, The reaction time is 2-3 hours.

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