A catalyst for preparing octenal by self-condensation of n-butyraldehyde, and its preparation method and application

Abstract

The present invention provides a catalyst for preparing octenal through the self-condensation of n-butyraldehyde, as well as a preparation method and application thereof, comprising a metal oxide and other additives, wherein the metal oxide includes MgO and CeO2. The reaction of preparing octenal through the self-condensation of n-butyraldehyde catalyzed by the catalyst is carried out in a fixed-bed reactor, and the conversion rate of n-butyraldehyde and the selectivity of octenal are both higher than 95%. The catalyst has good operational stability and can maintain good catalytic activity after long-term use. When catalyzing the synthesis of octenal, no alkaline wastewater is generated, and there is no need to separate the product and the catalyst. The process flow is simple, the cost is low, and it is environmentally friendly, which can meet the requirements for industrialization of preparing octenal through the self-condensation of n-butyraldehyde.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysis, and in particular relates to a catalyst for preparing octenal through self-condensation of n-butyraldehyde, and a preparation method and application thereof. Background Art

[0002] Octanol (2-ethylhexanol, 2-EH), commonly referred to as octanol refers to isooctyl alcohol, which is mainly used to manufacture dioctyl phthalate (DOP / DEHP) and dioctyl terephthalate (DOTP). It is also used in diesel additives, synthetic lubricants, antioxidants, solvents and defoaming agents. It can also be used in paper sizing, photography, latex and printing and dyeing. It is an important basic organic chemical raw material and chemical auxiliary raw material.

[0003] Currently, the industrial preparation of octanol mainly involves three steps: (1) using propylene and synthesis gas as raw materials to produce n-butyraldehyde through carbonylation reaction;

[0004] (2) n-Butyraldehyde undergoes self-condensation reaction under the catalysis of base to generate octenal (2-ethyl-2-hexenal):

[0005] 2CH3CH2CH2CHO→CH3CH2CH2CH=C(CH2CH3)CHO+H2O

[0006] (3) Octenal is hydrogenated to produce octanol:

[0007] CH3CH2CH2CH→C(CH2CH3)CHO+H2→CH3CH2CH2CH2CH(CH2CH3)CH2OH

[0008] Among them, liquid inorganic base (mainly dilute NaOH solution) is used as a catalyst for the industrial catalytic self-condensation of n-butyraldehyde. Although a high n-butyraldehyde conversion rate and octenal yield can be achieved, the production process has many disadvantages, such as severe equipment corrosion, non-reusable catalysts, large discharge of alkaline wastewater, high production costs, and serious environmental pollution. It is difficult to meet the current green chemical industry requirements.

[0009] To overcome the shortcomings of traditional liquid inorganic base catalysts, the development of new, environmentally friendly base catalysts is of great significance. Solid bases are solids that can accept protons or donate electron pairs. Alkali metal or alkaline earth metal oxide catalysts are common solid base catalysts. Compared with traditional liquid inorganic base catalysts, solid base catalysts offer many advantages, including high catalytic activity, high selectivity, easy separation, and reusability. However, solid base catalysts are often sensitive to air and moisture, have poor stability, and have other limitations, such as low strength and low specific surface area, which limit their application in industry. Summary of the Invention

[0010] In view of this, the present invention aims to propose a catalyst for preparing octenal by self-condensation of n-butyraldehyde, as well as its preparation method and application, so as to solve the problems that the catalyst cannot be reused in the process of preparing octenal by self-condensation of n-butyraldehyde, the discharge of alkaline wastewater is large, the production cost is high, and the environmental pollution is serious.

[0011] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0012] A catalyst for preparing octenal through self-condensation of n-butyraldehyde comprises metal oxides and other additives. The metal oxides include MgO and CeO2, and the other additives include fatty acid magnesium.

[0013] Furthermore, the molar ratio of MgO to CeO2 is 1:0.5-1.5.

[0014] Further, fatty acid magnesium includes C4-C20 saturated or unsaturated fatty acids and Mg 2+ The organic magnesium salt is preferably composed of one or more of magnesium butyrate, magnesium octanoate, magnesium myristate, magnesium stearate and magnesium oleate.

[0015] Furthermore, the mass ratio of the metal oxide to the other additives is 1:0.05-0.15.

[0016] Ce itself has weak alkalinity, but it has a fluorite structure and a high specific surface area, so it can be used as a strong promoter. When the Ca / Ce molar ratio is appropriate, Ca 2+ and Ce 4+ The substitution between them can form strong interactions and lattice changes, causing the MgO lattice to be distorted, generating strong basic sites, and also making the prepared MgO-CeO2 solid base catalyst exhibit excellent performance and stability.

[0017] Although fatty acid magnesium itself does not have a catalytic effect, adding an appropriate amount of fatty acid magnesium to the above-mentioned solid base catalyst can not only effectively overcome the shortcomings of the solid base catalyst such as rapid activity loss and poor stability, but also improve the conversion rate of n-butyraldehyde and the selectivity of the target product. The present application does not particularly limit the source of the fatty acid magnesium compound, which can be a commercially available product or prepared in a manner familiar to those skilled in the art.

[0018] A method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde comprises the following steps:

[0019] S1: adding magnesium salt and cerium salt to water and stirring to obtain a mixed solution;

[0020] S2: adding an excess amount of alkaline solution dropwise to the mixed solution in step S1 under stirring;

[0021] S3: The precipitate produced in step S2 is removed by filtration, washed thoroughly until neutral, and then dried to obtain a dried product;

[0022] S4: calcining the dried product in step S3 to obtain a calcined solid;

[0023] S5: uniformly mixing the calcined solid obtained in S4 with other additives, and forming the solid base catalyst.

[0024] Furthermore, the magnesium salt in step S1 is magnesium nitrate, and the cerium salt in step S1 is cerium nitrate.

[0025] Furthermore, the alkaline substance of the alkaline solution in step S2 includes one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, and potassium carbonate;

[0026] Preferably, the step S2 comprises uniformly adding an excess amount of alkaline solution to the mixed solution in S1, and aging the mixed solution for 6-24 hours after precipitation is complete.

[0027] Furthermore, the step S3 includes removing the precipitate in S2 by filtering, washing it with deionized water until it is neutral, and then drying it in an oven at 110° C. for 24 hours.

[0028] Furthermore, the step S4 includes calcining the dried product at 500-900° C. for 2-5 hours.

[0029] Furthermore, step S5 includes uniformly mixing the metal oxide obtained in S4 with an auxiliary agent, and forming the mixture by tableting or extrusion to obtain the solid base catalyst;

[0030] Preferably, the solid base catalyst obtained in step S5 has a size of 10-20 mesh;

[0031] Preferably, the mass ratio of the metal oxide to the other additives is 1:0.05-0.15.

[0032] The catalyst is used for preparing octenal by self-condensation of n-butyraldehyde.

[0033] Compared with the prior art, the catalyst for preparing octenal by self-condensation of n-butyraldehyde, the preparation method thereof, and the application thereof described in the present invention have the following advantages:

[0034] The present invention discloses a highly active and stable solid base catalyst that can be used to catalyze the self-condensation reaction of n-butyraldehyde to produce octenal. During the reaction, the conversion rate of the raw material n-butyraldehyde is high, and the selectivity of the product octenal is high. Furthermore, the solid base catalyst is non-corrosive and generates no alkaline wastewater. The solid base catalyst can be loaded into a fixed-bed reactor, and the reaction materials can be directly collected after leaving the reactor, eliminating the need to separate the reaction materials from the catalyst. This method has a simple process flow, low cost, and is environmentally friendly, meeting the requirements for industrialized production of octenal through n-butyraldehyde self-condensation. DETAILED DESCRIPTION

[0035] The technical solutions described in the present invention are described below in a clear and complete manner. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods described, unless otherwise specified, are all conventional methods.

[0036] Example 1

[0037] Preparation of solid base catalyst:

[0038] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:0.5, dissolved in deionized water, and mixed well to prepare a mixed solution;

[0039] S2: Slowly add 20% by mass of ammonia water to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age for 8 hours;

[0040] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0041] S4: The dried product was calcined at 850° C. in air atmosphere for 2.5 h to obtain the main component of the solid base catalyst.

[0042] S5: The main component obtained in S5 is mixed evenly with magnesium butyrate (the addition amount is 10% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a 10-20 mesh solid base catalyst.

[0043] Solid base catalyst evaluation:

[0044] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1 h -1The reaction temperature was 130°C and the reaction pressure was 0.7 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed by gas chromatography. The catalyst evaluation results are shown in Table 1.

[0045] Example 2

[0046] Preparation of solid base catalyst:

[0047] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:0.75, dissolved in deionized water, and mixed to obtain a mixed solution;

[0048] S2: Slowly add 20% by mass of sodium carbonate to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age for 10 hours;

[0049] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0050] S4: The dried product was calcined in air at 550° C. for 4.5 h to obtain the main component of the solid base catalyst.

[0051] S5: The main component obtained in S5 is mixed evenly with magnesium octoate (the addition amount is 10% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a solid base catalyst of 10-20 mesh.

[0052] Solid base catalyst evaluation:

[0053] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1.5 h -1 The reaction temperature was 120°C and the reaction pressure was 1.5 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed by gas chromatography. The catalyst evaluation results are shown in Table 1.

[0054] Example 3

[0055] Preparation of solid base catalyst:

[0056] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:1, dissolved in deionized water, and mixed well to prepare a mixed solution;

[0057] S2: Slowly add 20% by mass of sodium hydroxide to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age at room temperature for 12 hours;

[0058] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0059] S4: The dried product is calcined at 800° C. in air atmosphere for 3 h to obtain the main component of the solid base catalyst.

[0060] S5: The main component obtained in S5 is mixed evenly with magnesium oleate (the addition amount is 10% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a 10-20 mesh solid base catalyst.

[0061] Solid base catalyst evaluation:

[0062] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1.0 h -1 The reaction temperature was 110°C and the reaction pressure was 1.0 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed using a gas chromatograph. The catalyst evaluation results are shown in Table 1.

[0063] Example 4

[0064] Preparation of solid base catalyst:

[0065] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:1.25, dissolved in deionized water, and mixed to obtain a mixed solution;

[0066] S2: Slowly add 20% by mass of potassium hydroxide to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age for 16 hours;

[0067] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0068] S4: The dried product is calcined in air at 700° C. for 3.5 h to obtain the main component of the solid base catalyst.

[0069] S5: The main component obtained in S5 is mixed evenly with magnesium stearate (the addition amount is 10% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a solid base catalyst of 10-20 mesh.

[0070] Solid base catalyst evaluation:

[0071] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 0.6 h -1 The reaction temperature was 100°C and the reaction pressure was 0.9 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed using a gas chromatograph. The catalyst evaluation results are shown in Table 1.

[0072] Example 5

[0073] Preparation of solid base catalyst:

[0074] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:1.5, dissolved in deionized water, and mixed well to prepare a mixed solution;

[0075] S2: Slowly add 20% by mass of potassium carbonate to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is produced, and age for 14 hours;

[0076] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0077] S4: The dried product is calcined at 600° C. in air atmosphere for 4 h to obtain the main component of the solid base catalyst.

[0078] S5: The main component obtained in S5 is mixed evenly with magnesium myristate (the addition amount is 10% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a 10-20 mesh solid base catalyst.

[0079] Solid base catalyst evaluation:

[0080] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1.8 h -1 The reaction temperature was 140°C and the reaction pressure was 1.2 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed using a gas chromatograph. The catalyst evaluation results are shown in Table 1.

[0081] Example 6

[0082] Preparation of solid base catalyst:

[0083] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:1, dissolved in deionized water, and mixed well to prepare a mixed solution;

[0084] S2: Slowly add 20% by mass of sodium hydroxide to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age for 20 hours;

[0085] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0086] S4: The dried product is calcined at 800° C. in air atmosphere for 3 h to obtain the main component of the solid base catalyst.

[0087] S5: The main component obtained in S5 is mixed evenly with magnesium oleate (the addition amount is 5% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a solid base catalyst of 10-20 mesh.

[0088] Solid base catalyst evaluation:

[0089] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1.0 h -1 The reaction temperature was 110°C and the reaction pressure was 1.0 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed using a gas chromatograph. The catalyst evaluation results are shown in Table 1.

[0090] Example 7

[0091] Preparation of solid base catalyst:

[0092] S1: Magnesium nitrate and cerium nitrate were weighed in a molar ratio of 1:1, dissolved in deionized water, and mixed well to prepare a mixed solution;

[0093] S2: Slowly add 20% by mass of sodium hydroxide to the mixed solution prepared in S1 under mechanical stirring until no new precipitation is generated, and age for 22 hours;

[0094] S3: The precipitate in S2 is removed by filtration, washed thoroughly with deionized water, and then dried in an oven to remove moisture;

[0095] S4: The dried product is calcined at 800° C. in air atmosphere for 3 h to obtain the main component of the solid base catalyst.

[0096] S5: The main component obtained in S5 is mixed evenly with magnesium oleate (the addition amount is 15% of the mass of the main component), and the mixture is formed into tablets, crushed and sieved to obtain a solid base catalyst of 10-20 mesh.

[0097] Solid base catalyst evaluation:

[0098] The prepared catalyst was placed in a fixed bed reactor, and n-butyraldehyde was pumped into the fixed bed reactor through a feed pump at a space velocity of 1.0 h -1 The reaction temperature was 110°C and the reaction pressure was 1.0 MPa. Samples were taken periodically during the reaction and the composition of the product was analyzed using a gas chromatograph. The catalyst evaluation results are shown in Table 1.

[0099] Comparative Example 1

[0100] No fatty acid magnesium was added during the catalyst preparation process, and the other conditions were the same as in Example 3.

[0101] Comparative Example 2

[0102] No magnesium nitrate was added during the catalyst preparation process, and the other conditions were the same as in Example 3.

[0103] Comparative Example 3

[0104] No cerium nitrate was added during the catalyst preparation process, and the other conditions were the same as in Example 3.

[0105] Table 1 Catalyst evaluation results in various examples and comparative examples

[0106]

[0107]

[0108] From the above experimental results we can see that:

[0109] (1) By comparing Example 3 with Comparative Example 1, it can be seen that fatty acid magnesium was added during the preparation of the solid base catalyst in Example 3, while fatty acid magnesium was not added during the preparation of the solid base catalyst in Comparative Example 1. During long-term use, the long-term conversion rate and selectivity of the catalyst in Comparative Example 1 were significantly lower than those of the catalyst in Example 3.

[0110] (2) Comparison of Example 3 and Comparative Example 2 shows that the catalyst containing only CeO2 and fatty acid magnesium has almost no catalytic activity;

[0111] (3) By comparing Example 3 with Comparative Example 3, it can be seen that the solid base catalyst in Comparative Example 3 does not contain CeO2 components, and the initial and long-term conversion rates and selectivity of the catalyst in Comparative Example 3 are significantly lower than the conversion rates and selectivity of the catalyst in Example 3.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A catalyst for preparing octenal by self-condensation of n-butyraldehyde, characterized in that: Including metal oxides and other additives, metal oxides include MgO, CeO2, other additives are fatty acid magnesium, The molar ratio of MgO and CeO2 is 1:0.5-1.5; The mass ratio of metal oxide to other additives is 1:0.05-0.

15.

2. A catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 1, characterized in that: Fatty acid magnesium includes C4-C20 saturated or unsaturated fatty acids and Mg 2+ Composition of organic magnesium salts.

3. A catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 2, characterized in that: The fatty acid magnesium includes one or more of magnesium butyrate, magnesium octanoate, magnesium myristate, magnesium stearate, and magnesium oleate.

4. A method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to any one of claims 1 to 3, characterized in that: The steps include: S1: adding magnesium salt and cerium salt to water and stirring to obtain a mixed solution; S2: adding an excess amount of alkaline solution dropwise to the mixed solution in step S1 under stirring; S3: The precipitate produced in step S2 is removed by filtration, washed thoroughly until neutral, and then dried to obtain a dried product; S4: calcining the dried product in step S3 to obtain a calcined solid; S5: uniformly mixing the calcined solid obtained in S4 with other additives, and forming the solid base catalyst.

5. A method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 4, characterized in that: The magnesium salt in step S1 is magnesium nitrate, and the cerium salt in step S1 is cerium nitrate.

6. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 4, characterized in that: The alkaline substance of the alkaline solution in step S2 includes one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, and potassium carbonate.

7. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 6, wherein: The step S2 comprises uniformly adding an excess amount of alkaline solution to the mixed solution in S1, and aging the mixed solution for 6-24 hours after precipitation is complete.

8. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 4, characterized in that: The step S3 comprises filtering out the precipitate in step S2, washing it with water until it is neutral, and then drying it in an oven; The step S4 includes calcining the dried product at 500-900° C. for 2-5 hours.

9. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 4, characterized in that: Step S5 comprises uniformly mixing the metal oxide obtained in S4 with the auxiliary agent, and forming the mixture into tablets or strips by a method of extrusion to obtain the solid base catalyst.

10. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 9, characterized in that: The solid base catalyst obtained in step S5 has a size of 10-20 mesh.

11. The method for preparing a catalyst for preparing octenal by self-condensation of n-butyraldehyde according to claim 9, characterized in that: The mass ratio of metal oxide to other additives is 1:0.05-0.

15.

12. Use of the catalyst according to any one of claims 1 to 3, characterized in that: The catalyst is used for preparing octenal through self-condensation of n-butyraldehyde.

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