A preparation method of a three-way catalyst, the catalyst prepared by the method and application thereof
By preparing a Zn1-xMgxO-Al2O3 ternary catalyst, the problems of equipment corrosion and difficult recovery of the catalyst in the process of acetone condensation to prepare isophorone were solved, achieving efficient acetone conversion and isophorone selectivity, which is suitable for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-12-06
- Publication Date
- 2026-06-09
AI Technical Summary
Existing catalysts for the preparation of isophorone by acetone condensation suffer from problems such as equipment corrosion, difficulty in catalyst recovery, and numerous side reactions. Furthermore, traditional heterogeneous catalysts are costly and difficult to prepare.
A Zn1-xMgxO-Al2O3 ternary catalyst was prepared by sol-gel method and mechanical mixing or wet kneading method. The basicity of the catalyst was modulated by Zn doping with MgO and applied to the acetone condensation reaction.
It improves acetone conversion and isophorone selectivity, and has good catalyst activity and stability, making it suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This application relates to a method for preparing a three-way catalyst, the catalyst prepared therefrom, and its application, and belongs to the field of catalysts. Background Technology
[0002] Isophorone is an important organic compound widely used in coatings, resins, oils, paints, inks, pesticides, and nitrocellulose. Its synthesis is typically achieved through the condensation reaction of acetone. Under alkaline conditions, three molecules of acetone first form an aldol condensation product, isopropylideneacetone, which is the product of two acetone molecules. Subsequently, the anion of the remaining acetone molecule undergoes a Michael addition reaction with isopropylideneacetone, and finally, isophorone is obtained through cyclization and dehydration.
[0003] In the condensation of acetone to isophorone, the catalyst plays a crucial role. Traditional catalysts such as NaOH and KOH, while effective, suffer from problems such as equipment corrosion, difficulty in catalyst recovery, and numerous side reactions. Therefore, the search for heterogeneous catalytic systems has become a research focus. For example, some studies have proposed using a mixture of Ba(OH)₂ and Mg(OH)₂ as a heterogeneous catalyst. This catalyst is not easily soluble in the reaction solution but can be suspended in it, flowing plate by plate in the reactive distillation column, thereby promoting the aldol condensation reaction of acetone. To improve the selectivity and yield of isophorone, researchers have developed novel catalysts. For instance, one catalyst consists of a magnesium-calcium-aluminum composite oxide and praseodymium sulfate. The magnesium-calcium-aluminum composite oxide is prepared by co-precipitation, then spray-impregnated with praseodymium sulfate solution, dried, and calcined to obtain the finished catalyst. This catalyst can significantly improve the yield of isophorone, but it still suffers from drawbacks such as high cost and difficult preparation. Summary of the Invention
[0004] Zn preparation in this application 1-x Mg x Methods using O-Al2O3 catalysts include sol-gel methods and mechanical mixing or wet kneading methods. By doping MgO with Zn to modulate its basicity, the modified composite catalyst was applied to the acetone condensation reaction to produce isophorone. This resulted in good catalyst activity, high acetone conversion and isophorone selectivity, and good stability.
[0005] According to one aspect of this application, a method for preparing a three-way catalyst is provided, wherein the three-way catalyst is Zn. 1-x Mg x O-Al2O3, where x is 0.9 to 0.95;
[0006] The method includes the following steps:
[0007] (1) Zn was first prepared using the sol-gel method. 1-xMg x O;
[0008] (2) Then, Zn is mixed mechanically or kneaded using a wet kneading method. 1-x Mg x The catalyst is obtained by mixing O and Al2O3.
[0009] Optionally, the following steps are included:
[0010] (1) Mix magnesium source, zinc source, urea, citric acid and solvent, stir to form sol, dry and cool to form dry gel, calcine I to obtain precursor;
[0011] (2) The precursor and Al2O3 are mixed by mechanical mixing or wet kneading and calcined to obtain the ternary catalyst.
[0012] The magnesium source is selected from at least one of magnesium nitrate, magnesium acetate, and magnesium chloride.
[0013] The zinc source is selected from at least one of zinc nitrate and zinc acetate;
[0014] The solvent is selected from water and / or ethanol.
[0015] The molar ratio of urea, citric acid, solvent to magnesium source and zinc source is 5-6:8-9:92-102:9;
[0016] Optionally, the molar ratio of the urea, citric acid, solvent to the magnesium source and zinc source is selected from 5:8:92:9 or 6:9:102:9;
[0017] The molar ratio of the magnesium source to the zinc source is 100:6 to 10, based on the molar amounts of magnesium and zinc.
[0018] Optionally, the upper limit of the molar ratio of the magnesium source and the zinc source is selected from 100:6, 100:7, and 100:8, and the lower limit is selected from 100:10, 100:9, and 100:8, based on the molar amounts of magnesium and zinc.
[0019] The stirring temperature is 80–90°C;
[0020] 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.
[0021] The stirring time is 5 to 10 hours;
[0022] 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;
[0023] The stirring speed is 300-500 rpm.
[0024] 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;
[0025] The drying temperature is 100–120°C;
[0026] Optionally, the upper limit of the drying temperature is selected from 120°C and 110°C, and the lower limit is selected from 100°C and 110°C;
[0027] The drying time is 8 to 12 hours;
[0028] Optionally, the upper limit of the drying time is selected from 12 hours and 10 hours, and the lower limit is selected from 8 hours and 10 hours;
[0029] The calcination temperature I is 450–650°C;
[0030] Optionally, the upper limit of the calcination temperature I is selected from 650℃, 600℃, and 550℃, and the lower limit is selected from 450℃, 500℃, and 550℃.
[0031] The calcination time is 2 to 5 hours.
[0032] Optionally, the upper limit of the calcination time I is selected from 5 hours and 4 hours, and the lower limit is selected from 2 hours and 3 hours;
[0033] The molar ratio of magnesium to aluminum in the magnesium source is 1:0.9 to 1.
[0034] The upper limit of the molar ratio of magnesium in the magnesium source to aluminum in Al2O3 is selected from 1:0.9, and the lower limit is selected from 1:1;
[0035] The calcination temperature II is 500–600°C;
[0036] Optionally, the upper limit of the calcination temperature II is selected from 600℃ and 550℃, and the lower limit is selected from 500℃ and 550℃;
[0037] The calcination time for the second stage is 2 to 6 hours.
[0038] 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 2 hours, 3 hours, and 4 hours.
[0039] According to another aspect of this application, a ternary catalyst prepared by the above-described preparation method is provided.
[0040] According to another aspect of this application, a method for preparing isophorone by condensation of acetone is provided, comprising the following steps:
[0041] Acetone is reacted with a catalyst to produce isophorone.
[0042] The catalyst is the aforementioned ternary catalyst.
[0043] The reaction temperature is 240–260°C;
[0044] 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;
[0045] The reaction was carried out at atmospheric pressure.
[0046] The mass hourly space velocity of the acetone is 1–2 h⁻¹. -1 .
[0047] 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 .
[0048] The beneficial effects that this application can produce include:
[0049] 1) The catalyst provided in this application can be used in the acetone condensation reaction to produce isophorone, and the Zn prepared is... 1-x Mg x O-Al2O3 catalysts exhibit excellent catalytic activity and stability.
[0050] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.
[0051] 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
[0052] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0053] 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.
[0054] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0055] 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.
[0056] Gas chromatography characterization
[0057] The composition of the products of the acetone condensation to isophorone reaction was analyzed using an Agilent 7890B gas chromatograph (FID detector, Pona column).
[0058] The acetone conversion rate and isophorone selectivity in the embodiments of this application are calculated as follows:
[0059] Acetone conversion rate: C AC =n0-n F *100% / n0
[0060] Isophorone selectivity: S IP =3n IP *100% / n0-n F .
[0061] n0: Molar amount of acetone fed into the feed
[0062] n IP Molar amount of isophorone
[0063] n F : Molar amount of unreacted acetone
[0064] Example 1: Preparation of Catalyst
[0065] A mixed solution of urea, citric acid, ethanol, and deionized water in a molar ratio of 5:8:92:9 was mixed with magnesium nitrate and zinc nitrate (Mg:Zn molar ratio of 100:8). The mixture was stirred at 400 rpm and 85°C for 6 hours, dried at 120°C for 10 hours, and calcined at 550°C for 3 hours to obtain Zn. 0.07 Mg 0.93 O material; Zn is prepared using a wet kneading method. 0.07 Mg 0.93 O and Al2O3 were mixed (Mg and Al molar ratio 1:1) and calcined at 550℃ for 4 hours, designated as catalyst 1. # .
[0066] Example 17 Comparative Catalyst
[0067] This embodiment, compared to Example 1, does not include the mixing process with Al2O3. A mixed solution of urea, citric acid, ethanol, and deionized water in a molar ratio of 5:8:92:9 is mixed with magnesium nitrate and zinc nitrate (Mg:Zn molar ratio of 100:8). The mixture is stirred at 400 rpm and 85°C for 6 hours, dried at 120°C for 110 hours, and calcined at 550°C for 13 hours to obtain Zn. 0.07 Mg 0.93 O material, designated as catalyst 17 # .
[0068] 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:
[0069] Table 1 Catalyst 1 # ~Catalyst 17 # Raw material selection and parameters
[0070]
[0071]
[0072] The explanations for each column in Table 1 above are as follows:
[0073] Magnesium sources: magnesium nitrate (Mg1), magnesium acetate (Mg2), magnesium chloride (Mg3).
[0074] Zinc sources: zinc nitrate (Zn1), zinc acetate (Zn2).
[0075] Solvents: Deionized water (solution 1), ethanol (solution 2),
[0076] A mixed solution of ethanol and deionized water (the mass ratio of ethanol to deionized water is 1:1) (3).
[0077] Table 2 Catalyst 1 # ~Catalyst 17 # Raw material selection and parameters
[0078]
[0079]
[0080] The explanations for each column in Table 2 above are as follows:
[0081] Mixing methods: mechanical mixing (mix 1), wet kneading (mix 2).
[0082] Example 2: Evaluation of the catalyst's reaction
[0083] 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.
[0084] 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.
[0085] 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.
[0086] Table 3 Example Catalyst 1 # ~16 # Comparative catalyst 17 # Reaction conditions and results for the acetone condensation to isophorone reaction
[0087]
[0088]
[0089] 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 three-way catalyst, characterized in that, The ternary catalyst is Zn. 1-x Mg x O-Al2O3, where x is 0.9 to 0.95; Includes the following steps: (1) Mix magnesium source, zinc source, urea, citric acid and solvent, stir to form sol, dry and cool to form dry gel, calcine I to obtain precursor; (2) The precursor and Al2O3 are mixed by mechanical mixing or wet kneading and calcined to obtain the ternary 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 chloride. The zinc source is selected from at least one of zinc nitrate and zinc acetate; The solvent is selected from water and / or ethanol.
3. The preparation method according to claim 1, characterized in that, The molar ratio of urea, citric acid, solvent to magnesium source and zinc source is 5-6:8-9:92-102:9; The molar ratio of the magnesium source to the zinc source is 100:6 to 10, based on the molar amounts of magnesium and zinc.
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.
5. The preparation method according to claim 1, characterized in that, The drying temperature is 100–120°C; The drying time is 8 to 12 hours; The calcination temperature I is 450–650°C; The calcination time is 2 to 5 hours.
6. The preparation method according to claim 1, characterized in that, The molar ratio of magnesium to aluminum in the magnesium source is 1:0.9 to 1.
7. The preparation method according to claim 1, characterized in that, The calcination temperature II is 500–600°C; The calcination time for the second stage is 2 to 6 hours.
8. A ternary catalyst prepared by the preparation method according to any one of claims 1 to 7.
9. A method for preparing isophorone by condensation of acetone, characterized in that, Includes the following steps: Acetone is reacted with a catalyst to produce isophorone. The catalyst is the ternary catalyst according to claim 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 .