Preparation method of composite catalyst, prepared catalyst and application

Abstract

The invention discloses a preparation method of a composite catalyst, the catalyst prepared by the preparation method and application of the catalyst. Comprising the following steps: (1) mixing a magnesium source, an aluminum source and a solvent, stirring, drying I and calcining I to obtain a precursor; and (2) dipping the precursor in a solution containing calcium salt, drying II, and calcining II to obtain the composite catalyst. The preparation method is stable, controllable and good in reproducibility. The method for preparing isophorone through acetone condensation provided by the invention adopts the catalyst provided by the invention, is high in reaction speed and high in yield, and can be applied to large-scale production.

Description

Technical Field

[0001] This application relates to a method for preparing a composite catalyst, the catalyst prepared therefrom, and its application, and belongs to the field of catalysts. Background Technology

[0002] Isophorones possess high boiling points and low hygroscopicity. They exhibit excellent solubility, dispersibility, and leveling properties, making them a good solvent for polymers, capable of dissolving nitrocellulose, acrylates, alkyd resins, polyesters, and epoxy resins. Due to their unsaturated ketone structure, the double bonds can further react to generate important products such as alcohols, acids, amines, esters, and isocyanates, finding wide applications in industries such as plastics, pesticides, pharmaceuticals, and coatings. With the increasingly evident global trend towards improved resource efficiency, rising environmental protection requirements, and the growing demand for low-VOC coatings, coupled with China's vigorous development of clean energy, the global market demand for isophorones and related products is steadily increasing. Their growth rate in the global market has already surpassed the growth rate of global GDP, and this momentum is expected to continue.

[0003] There are three methods for acetone condensation to prepare isophorone: (1) pressurized liquid-phase condensation in alkaline solution; (2) solid catalyst heterogeneous catalytic condensation; and (3) gas-phase condensation-liquid-phase condensation combined method. Since the liquid-phase method has many drawbacks, especially pollution problems, more and more researchers are turning their attention to developing environmentally friendly heterogeneous catalytic condensation methods.

[0004] The acetone gas-phase condensation method is an attractive industrial approach, with the key lying in the selection and preparation of solid catalysts. Early catalysts suffered from drawbacks such as low strength, short lifespan, poor reproducibility, high cost, and low production capacity. Later, magnesium-aluminum composites were often used. These catalysts are easy to prepare and can be used in a fixed-bed reactor, but they also suffer from high cost and difficult preparation. Summary of the Invention

[0005] The method for preparing CaO / MgO-MgAl2O4 catalyst in this application includes impregnation and high-temperature solid-phase synthesis. The synthesized catalyst has high crystallinity and good reaction stability in catalytic reactions. When applied to the acetone condensation to isophorone reaction, it exhibits good catalytic activity, high acetone conversion and isophorone selectivity, and good stability.

[0006] According to one aspect of this application, a method for preparing a composite catalyst is provided, characterized in that,

[0007] The method includes the following steps:

[0008] (1) First, the magnesium source and aluminum source were uniformly mixed by wet mixing method, and then MgO-MgAl2O4 was prepared by high temperature solid phase synthesis method.

[0009] (2) CaO was loaded onto MgO-MgAl2O4 by impregnation method to obtain the catalyst.

[0010] Optionally, the following steps are included:

[0011] (1) Mix the magnesium source, aluminum source and solvent, stir, dry I, calcine I, to obtain the precursor;

[0012] (2) The precursor is impregnated in a solution containing calcium salt, dried (II), and calcined (II) to obtain the composite catalyst.

[0013] The magnesium source is selected from at least one of magnesium nitrate, magnesium acetate, and magnesium hydroxide.

[0014] The aluminum source is selected from at least one of aluminum nitrate and aluminum oxide;

[0015] The solvent is selected from at least one of water and ethanol.

[0016] The molar ratio of the magnesium source to the aluminum source is 1:3 to 5, based on the molar amounts of magnesium and aluminum.

[0017] The upper limit of the molar ratio of the magnesium source to the aluminum source is selected from 1:3 and 1:4, and the lower limit is selected from 1:5 and 1:4;

[0018] The total mass of the magnesium source and aluminum source is in a solid-liquid ratio of 1:2 to 3 g / ml to the solvent.

[0019] The upper limit of the solid-liquid ratio of the total mass of the magnesium source and aluminum source to the solvent is selected from 1:2 g / ml and 1:2.5 g / ml, and the lower limit is selected from 1:3 g / ml and 1:2.5 g / ml.

[0020] The stirring temperature is 80–90°C;

[0021] Optionally, the upper limit of the stirring temperature is selected from 90°C and 85°C, and the lower limit is selected from 80°C and 85°C.

[0022] The stirring time is 5 to 10 hours;

[0023] Optionally, the upper limit of the stirring time is selected from 10 hours, 9 hours, and 8 hours, and the lower limit is selected from 5 hours, 6 hours, and 7 hours;

[0024] The stirring speed is 300-500 rpm;

[0025] Optionally, the upper limit of the stirring speed is selected from 500 rpm and 400 rpm, and the lower limit is selected from 300 rpm and 400 rpm;

[0026] The temperature of the drying process I is 100–120°C;

[0027] Optionally, the upper limit of the temperature of the drying I is selected from 120°C and 110°C, and the lower limit is selected from 100°C and 110°C;

[0028] The drying time for step I is 8 to 12 hours;

[0029] Optionally, the upper limit of the drying time I is selected from 12 hours and 10 hours, and the lower limit is selected from 8 hours and 10 hours;

[0030] The calcination temperature I is 600–1200°C;

[0031] Optionally, the upper limit of the calcination temperature I is selected from 1200℃, 1100℃, 1000℃, and 900℃, and the lower limit is selected from 600℃, 700℃, 800℃, and 900℃;

[0032] The calcination time is 12 to 24 hours.

[0033] Optionally, the upper limit of the calcination time I is selected from 24 hours, 22 hours, 20 hours, and 18 hours, and the lower limit is selected from 12 hours, 14 hours, and 16 hours.

[0034] The calcium salt is selected from calcium chloride and / or calcium nitrate;

[0035] The temperature of the drying II process is 80–130°C;

[0036] Optionally, the upper limit of the temperature of the drying II is selected from 130°C, 120°C, and 110°C, and the lower limit is selected from 80°C, 90°C, and 100°C;

[0037] The drying time for step II is 6 to 24 hours;

[0038] Optionally, the upper limit of the drying time II is selected from 24 hours, 22 hours, 20 hours, 18 hours, and 16 hours, and the lower limit is selected from 6 hours, 8 hours, 10 hours, 12 hours, and 14 hours.

[0039] The calcination temperature II is 450–650°C;

[0040] Optionally, the upper limit of the calcination temperature II is selected from 650°C, 600°C, and 550°C, and the lower limit is selected from 450°C, 500°C, and 550°C.

[0041] The calcination time II is 1 to 6 hours.

[0042] Optionally, the upper limit of the calcination time II is selected from 6 hours, 5 hours, and 4 hours, and the lower limit is selected from 1 hour, 2 hours, and 3 hours.

[0043] According to another aspect of this application, a composite catalyst prepared by the above-described preparation method is provided, characterized in that,

[0044] The composite catalyst is a CaO / MgO-MgAl2O4 catalyst.

[0045] The composite catalyst contains 2-5 wt% CaO, with the remainder being MgO-MgAl2O4.

[0046] According to another aspect of this application, a method for preparing isophorone by condensation of acetone is provided, comprising the following steps:

[0047] In a reactor, acetone is contacted with a catalyst and reacted to obtain isophorone;

[0048] The reactor is a fixed-bed reactor.

[0049] The catalyst is the composite catalyst described above.

[0050] The reaction temperature is 240–260°C;

[0051] Optionally, the upper limit of the reaction temperature is selected from 260°C and 250°C, and the lower limit is selected from 240°C and 250°C.

[0052] The reaction was carried out at atmospheric pressure.

[0053] The mass hourly space velocity of the acetone is 1–2 h⁻¹. -1 .

[0054] Optionally, the upper limit of the mass hourly space velocity of the acetone is selected from 2h. -1 1.5h -1 The lower limit is selected from 1h -1 1.5h -1 .

[0055] The beneficial effects that this application can produce include:

[0056] 1) The catalyst provided in this application can be applied to the reaction of acetone condensation to isophorone. The prepared CaO / MgO-MgAl2O4 catalyst has excellent catalytic activity and stability.

[0057] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.

[0058] 3) The method for the acetone condensation to isophorone 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. Detailed Implementation

[0059] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0060] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, but should be understood to include those approximations of such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0061] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0062] Unless otherwise specified, the raw materials used in the embodiments of this application were purchased commercially or prepared by known methods. Unless otherwise specified, the analytical methods used in the embodiments employed conventional instrument settings and conventional analytical methods.

[0063] Gas chromatography characterization

[0064] The composition of the products of the acetone condensation to isophorone reaction was analyzed using an Agilent 7890B gas chromatograph (FID detector, Pona column).

[0065] The acetone conversion rate and isophorone selectivity in the embodiments of this application are calculated as follows:

[0066] Acetone (AC) conversion rate: C AC =n0-n F *100% / n0

[0067] Isophorone selectivity: S IP =3n IP *100% / n0-n F .

[0068] n0: Molar amount of acetone fed into the feed

[0069] n IP Molar amount of isophorone

[0070] n F : Molar amount of unreacted acetone

[0071] Example 1: Preparation of Catalyst

[0072] Magnesium nitrate and aluminum nitrate (Mg:Al molar ratio 1:4) were mixed with deionized water solvent (solid-liquid ratio 1:2.5 g / ml), stirred at 300 rpm and 85°C for 8 hours, dried at 100°C for 12 hours, and calcined at 1100°C for 20 hours to obtain MgO-MgAl2O4 material. The synthesized MgO-MgAl2O4 was impregnated in a calcium nitrate solution with a CaO content of 4 wt%, dried at 120°C for 12 hours, and calcined at 550°C for 4 hours. This was designated as catalyst 1. # .

[0073] Example 17 Comparative Catalyst

[0074] This embodiment differs from Example 1 in that it does not include the CaO loading process; otherwise, it is the same as Example 1. Specifically, magnesium nitrate and aluminum nitrate with a Mg:Al molar ratio of 1:4 are mixed with deionized water solvent (solid-liquid ratio of 1:2.5 g / ml), stirred at 300 rpm and 85°C for 8 hours, dried at 100°C for 112 hours, and calcined at 1100°C for 120 hours to obtain MgO-MgAl2O4 material, denoted as Catalyst 17. # .

[0075] Following these steps, adjust the type, amount, and reaction parameters of each raw material to obtain sequence number 1. # ~17 # A series of catalysts, denoted as catalyst 1 # Catalyst 17 # As shown in Tables 1 and 2 below:

[0076] Table 1 Catalyst 1 # ~Catalyst 17 # Raw material selection and parameters

[0077]

[0078] The explanations for each column in Table 1 above are as follows:

[0079] Magnesium sources: magnesium nitrate (Mg1), magnesium acetate (Mg2), magnesium hydroxide (Mg3).

[0080] Aluminum source: aluminum nitrate (Al1), aluminum oxide (Al2).

[0081] Solvents: Deionized water (solution 1), ethanol (solution 2),

[0082] A mixed solution of ethanol and deionized water (the mass ratio of ethanol to deionized water is 1:1) (3).

[0083] Table 2 Catalyst 1 # Catalyst 17 #Raw material selection and parameters

[0084]

[0085]

[0086] The explanations for each column in Table 2 above are as follows:

[0087] Calcium sources: calcium chloride (Ca1), calcium nitrate (Ca2).

[0088] Example 2: Evaluation of the catalyst's reaction

[0089] The catalyst 1 obtained above # ~17 # It is applied to the acetone condensation to isophorone reaction, and the reaction conditions are shown in Table 3.

[0090] Catalyst 1, which has been tableted, pulverized, and sieved, # Up to 17 # The feedstock is loaded into a fixed-bed reactor, heated to the reaction temperature, and then pumped in.

[0091] The composition of the products was analyzed using an Agilent 7890B gas chromatograph (FID detector, Pona column), and the results are shown in Table 3.

[0092] Table 3 Catalyst 1 # ~16 # Catalyst and Comparative Example 17 # Reaction conditions and results of catalyst used in the acetone condensation to isophorone

[0093]

[0094]

[0095] 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 a composite catalyst, characterized in that, Includes the following steps: (1) Mix the magnesium source, aluminum source and solvent, stir, dry I, calcine I, to obtain the precursor; (2) The precursor is impregnated in a solution containing calcium salt, dried (II), and calcined (II) to obtain the composite catalyst.

2. The preparation method according to claim 1, characterized in that, The magnesium source is selected from at least one of magnesium nitrate, magnesium acetate, and magnesium hydroxide. The aluminum source is selected from at least one of aluminum nitrate and aluminum oxide; The solvent is selected from at least one of water and ethanol.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the magnesium source to the aluminum source is 1:3 to 5, based on the molar amounts of magnesium and aluminum. The total mass of the magnesium source and aluminum source is in a solid-liquid ratio of 1:2 to 3 g / ml to the solvent.

4. The preparation method according to claim 1, characterized in that, The stirring temperature is 80–90°C; The stirring time is 5 to 10 hours; The stirring speed is 300-500 rpm; The temperature of the drying process I is 100–120°C; The drying time for step I is 8 to 12 hours; The calcination temperature I is 600–1200°C; The calcination time is 12 to 24 hours.

5. The preparation method according to claim 1, characterized in that, The calcium salt is selected from calcium chloride and / or calcium nitrate.

6. The preparation method according to claim 1, characterized in that, The temperature of the drying II process is 80–130°C; The drying time for step II is 6 to 24 hours; The calcination temperature II is 450–650°C; The calcination time II is 1 to 6 hours.

7. A composite catalyst prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The composite catalyst is a CaO / MgO-MgAl2O4 catalyst.

8. The composite catalyst according to claim 7, characterized in that, The composite catalyst contains 2-5 wt% CaO, with the remainder being MgO-MgAl2O4.

9. A method for preparing isophorone by condensation of acetone, characterized in that, Includes the following steps: In a reactor, acetone is contacted with a catalyst and reacted to obtain isophorone; The catalyst is the composite catalyst according to any one of claims 7 or 8.

10. The method according to claim 9, characterized in that, The reaction temperature is 240–260°C; The reaction was carried out at atmospheric pressure. The mass hourly space velocity of the acetone is 1–2 h⁻¹. -1 .

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