A method of aldol condensation reaction

Abstract

The present application relates to the technical field of alcohol aldehyde condensation reaction, and discloses an alcohol aldehyde condensation reaction method.The alcohol aldehyde condensation reaction method is carried out in an alcohol aldehyde condensation reaction device, the alcohol aldehyde condensation reaction device comprises a micro-channel alcohol aldehyde condensation reactor and an alcohol aldehyde condensation tube reactor which are connected in series; in the presence of an alkali catalyst, a reaction raw material n-butyl aldehyde is subjected to a first alcohol aldehyde condensation reaction in the micro-channel alcohol aldehyde condensation reactor to obtain a first alcohol aldehyde condensation reaction product; and the first alcohol aldehyde condensation reaction product is subjected to a second alcohol aldehyde condensation reaction in the alcohol aldehyde condensation tube reactor.The method uses a micro-channel alcohol aldehyde condensation reactor and an alcohol aldehyde condensation tube reactor to replace a full-mixing kettle reactor in the prior art to carry out alcohol aldehyde condensation reaction, so that the yield of a by-product heavy carbon alcohol can be significantly reduced, and the yield of a target product can be improved.

Description

Technical Field

[0001] This invention relates to the technical field of alcohol-aldehyde condensation reaction, and more specifically to a method for alcohol-aldehyde condensation reaction. Background Technology

[0002] Octyl alcohol is a colorless, flammable liquid with a characteristic odor. It is primarily used in the production of plasticizers, extractants, and stabilizers, and serves as an intermediate in the production of solvents and fragrances. Octyl alcohol itself is also used in fragrances, blending floral scents such as rose and lily, and as a flavoring agent in soaps.

[0003] The current mainstream production technology for octanol involves the low-pressure carbonylation synthesis of butyraldehyde using a rhodium catalyst, followed by the aldol condensation of butyraldehyde to obtain octenal, and then the hydrogenation purification of octenal to yield octanol. The aldol condensation reaction equation is as follows:

[0004]

[0005] CH3CH2CH2CHO + CH3CH2CH2CH=C(CH2CH3)CHO → Heavy alcohol (side reaction)

[0006] Butyraldehyde from the isomerization column reacts with sodium hydroxide solution in an aldol condensation reactor. The condensation and dehydration reactions take place in the liquid phase of the reactor, equipped with a stirrer, yielding a mixture of crude octenal and butyraldehyde. The reaction mixture enters an aldol condensation recycling column, where lighter components such as butyraldehyde are separated from octenal by distillation. The aqueous phase at the top of the column is steam-extracted from the organic matter and recycled back into the column. Octenal is collected from the bottom of the column, separated from the aqueous phase by a chromatography column, and then enters the hydrogenation reaction unit.

[0007] The process uses a fully mixed batch reactor, which produces 3% of heavy alcohols. However, because the reactor is equipped with a stirrer, a leak of reactants could occur during operation if the stirrer seal fails. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for aldol condensation reaction. This method uses a microchannel aldol condensation reactor and an aldol condensation tubular reactor in series to replace the existing fully mixed batch reactor for aldol condensation reaction, which can significantly reduce the yield of the by-product heavy alcohol and increase the yield of the target product.

[0009] To achieve the above objectives, the present invention provides a method for aldol condensation reaction, wherein the method is carried out in an aldol condensation reaction apparatus, the aldol condensation reaction apparatus comprising a microchannel aldol condensation reactor and an aldol condensation tubular reactor connected in series.

[0010] In the presence of an alkaline catalyst, the reactant n-butyraldehyde undergoes a first aldol condensation reaction in the microchannel aldol condensation reactor to obtain the first aldol condensation reaction product.

[0011] The product of the first aldol condensation reaction undergoes a second aldol condensation reaction in the aldol condensation tubular reactor.

[0012] Preferably, the conversion rate of n-butyraldehyde, the reactant in the first alcohol-aldol condensation reaction, is 65-75%.

[0013] Preferably, the diameter of the tube in the aldol condensation tubular reactor is 1 / 5 to 1 / 2 of the diameter of the reaction section of the microchannel aldol condensation reactor, and more preferably 1 / 4 to 1 / 2.

[0014] The method provided by this invention employs an optimized design combining a microchannel aldol condensation reactor and an aldol condensation tubular reactor, replacing the existing fully mixed reactor for aldol condensation. The microchannel aldol condensation reactor achieves uniform mixing of reactants, effectively improving the selectivity of the main reaction, butyraldehyde aldol condensation, while reducing the selectivity of the side reaction, butyraldehyde and octenal. This significantly reduces the yield of heavy alcohols, decreasing the content of heavy alcohols in the reaction products from 3% to approximately 2.5%, and increasing the yield of the target product, octenal.

[0015] The method provided by the present invention, in a preferred embodiment, uses a static mixer instead of a stirrer in the aldol condensation apparatus. This reduces the probability of reactant leakage and improves operational safety. Furthermore, it promotes uniform mixing of reactants and enhances the selectivity of the main reaction, the butyraldehyde aldol condensation reaction. Attached Figure Description

[0016] Figure 1 These are schematic diagrams of the aldol condensation reaction apparatus in Examples 1-9;

[0017] Figure 2 This is a schematic diagram of a comparative aldol condensation apparatus.

[0018] Explanation of reference numerals in the attached figures

[0019] Figure 1 middle,

[0020] 1- Microchannel aldol condensation reactor; 2- Aldol condensation tubular reactor;

[0021] 3-Microchannel reaction tube; 4-Dispenser.

[0022] Figure 2 middle,

[0023] 1-Alcohol-aldehyde condensation reactor body; 2-Alcohol-aldehyde condensation reactor stirrer. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, 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.

[0025] This invention provides a method for aldol condensation reaction, wherein the method is carried out in the following manner: Figure 1 The aldol condensation reaction is carried out in the apparatus shown, which includes a microchannel aldol condensation reactor 1 and an aldol condensation tubular reactor 2 connected in series.

[0026] In the presence of an alkaline catalyst, the reactant n-butyraldehyde undergoes a first aldol condensation reaction in the microchannel aldol condensation reactor 1 to obtain the first aldol condensation reaction product.

[0027] The product of the first aldol condensation reaction undergoes a second aldol condensation reaction in the aldol condensation tubular reactor 2.

[0028] The method provided by this invention employs an optimized design combining a microchannel aldol condensation reactor and an aldol condensation tubular reactor, replacing the existing fully mixed reactor for aldol condensation. The microchannel aldol condensation reactor achieves uniform mixing of reactants, effectively improving the selectivity of the main reaction, butyraldehyde aldol condensation, while reducing the selectivity of the side reaction, butyraldehyde and octenal. This significantly reduces the yield of heavy alcohols, decreasing the content of heavy alcohols in the reaction products from 3% to approximately 2.5%, and increasing the yield of the target product, octenal.

[0029] The method provided by this invention allows for a conversion rate of butyraldehyde of up to 70% after the reaction of n-butyraldehyde with an alkaline catalyst in a microchannel aldol condensation reactor. However, due to insufficient residence time, the conversion rate needs to be further improved. Therefore, by adding tubular reactors in series to increase the residence time of the reactants, the conversion rate of n-butyraldehyde can be further increased to 92%.

[0030] In this invention, preferably, the microchannel aldol condensation reactor 1 is a vertical reactor, more preferably a variable-diameter vertical reactor. Choosing a vertical reactor avoids the stratification of the first aldol condensation reaction products, thus improving the reaction performance of the main reaction.

[0031] In this invention, preferably, the microchannel aldol condensation reactor 1 includes a feed section, a buffer section, and a reaction section arranged sequentially from top to bottom.

[0032] In this invention, preferably, the reaction section is provided with a microchannel reaction tube 3 for mixing the reaction raw material n-butyraldehyde and the alkaline catalyst to carry out a first alcohol-aldehyde condensation reaction.

[0033] In this invention, it is understood that the reaction section refers to the area of ​​the microchannel reaction tube in the microchannel aldol condensation reactor.

[0034] In this invention, preferably, multiple microchannel reaction tubes 3 are provided, and the multiple microchannel reaction tubes 3 are arranged side by side inside the reaction section. By providing multiple microchannel reaction tubes, the first aldol condensation reaction can be carried out in this reaction section as much as possible, thereby improving the conversion rate of the reaction raw materials and reducing the occurrence of side reactions.

[0035] In this invention, preferably, the height-to-diameter ratio of the reaction section is 5:1-10:1, more preferably 8:1-10:1, where the height is the height of the microchannel reaction tube 3 in the reaction section, and the diameter is the diameter of the reaction section. This invention, by optimizing the structure of the microchannel aldol condensation reactor and controlling the height-to-diameter ratio of the reaction section within a specific range, has the advantage of reducing the selectivity of side reactions.

[0036] In this invention, it is understood that the diameter of the reaction section refers to the diameter of the region (cylinder) of the reaction section in the microchannel aldol condensation reactor.

[0037] In this invention, preferably, a static mixer is provided inside the microchannel reaction tube 3. The static mixer is used to mix the reaction raw material n-butyraldehyde and the alkaline catalyst to carry out the first alcohol-aldol condensation reaction. By using a static mixer instead of a stirrer in the alcohol-aldol condensation device, the probability of reactant leakage can be reduced, improving operational safety. On the other hand, it can promote uniform mixing of reactants and improve the selectivity of the main reaction, the butyraldehyde alcohol-aldol condensation reaction.

[0038] In this invention, preferably, each microchannel reaction tube 3 is provided with multiple static mixers.

[0039] In this invention, the specific type of static mixer is not particularly limited. It can be any static mixer conventionally defined in the art, such as at least one of ZW tube static mixer, SK type static mixer, FUNV SV type static mixer and SX type static mixer, preferably SK type static mixer.

[0040] In this invention, by first carrying out a first aldol condensation reaction in a microchannel aldol condensation reactor, the conversion rate of the reactant n-butyraldehyde can be improved, thereby increasing the yield of the target product. Preferably, the conversion rate of the reactant n-butyraldehyde in the first aldol condensation reaction is 65-75%, more preferably 68-72%.

[0041] In this invention, no particular type of base catalyst is specified; any base catalyst conventionally defined in the art for carbonyl synthesis reactions is applicable. Preferably, the base catalyst is selected from basic compounds, and sodium hydroxide is a preferred choice.

[0042] In this invention, the amounts of the alkaline catalyst and the reaction raw materials are not particularly limited. Preferably, the volume ratio of the reaction raw material n-butyraldehyde to the alkaline catalyst is 6-10:1, more preferably 9-10:1.

[0043] In this invention, preferably, the conditions for the first aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5 MPa, and a residence time of the reactant n-butyraldehyde and the alkaline catalyst in the reaction section of 5-10 s; preferably, the conditions for the first aldol condensation reaction include: a reaction temperature of 120-130℃, a reaction pressure of 0.4-0.45 MPa, and a residence time of the reactant n-butyraldehyde and the alkaline catalyst in the reaction section of 5-8 s. By using the apparatus of this invention in combination with the reaction conditions of this invention, it has the advantages of improving reaction selectivity and reducing the generation of the side reaction, heavy alcohols.

[0044] In this invention, it should be noted that the residence time of the reaction raw material n-butyraldehyde and the alkaline catalyst in the reaction section refers to the total residence time of the reaction raw material n-butyraldehyde and the alkaline catalyst in the microchannel reaction tube.

[0045] In this invention, preferably, the flow rates of the reactant n-butyraldehyde and the alkaline catalyst in the reaction section are above 2 m / s, and more preferably 2-3 m / s. By controlling the flow rates of the reactant n-butyraldehyde and the alkaline catalyst, the octenal produced in the reaction can be prevented from separating with water in the reaction tube, thus reducing the probability of side reactions.

[0046] In this invention, preferably, the method further includes: using a cooling medium to deheat the microchannel reaction tube 3. Within the reaction tube shell of the aldol condensation microchannel reactor, cooling water is used to deheat the microchannel reaction tube, preventing excessively high reaction temperatures inside the tube and thus avoiding negative impacts on reaction selectivity.

[0047] In this invention, the type of cooling medium is not particularly limited, and it can be any cooling medium conventionally defined in the art, such as water.

[0048] In this invention, preferably, the temperature of the cooling medium is 30-35°C.

[0049] In this invention, the specific type of aldol condensation tubular reactor 2 is not particularly limited; any loop reactor conventionally defined in the art is applicable to this invention. Preferably, the aldol condensation reactor 2 is a serpentine tubular reactor.

[0050] In this invention, the material of the aldol condensation tubular reactor is not particularly limited, and can be at least one of 304 stainless steel, 316L stainless steel and Hastelloy.

[0051] In this invention, preferably, the length-to-diameter ratio of the aldol condensation tubular reactor 2 is 25-30:1, wherein the length is the total length of the aldol condensation tubular reactor 2, and the diameter is the tube diameter of the aldol condensation tubular reactor 2.

[0052] In this invention, preferably, the diameter of the tubular reactor 2 for aldol condensation is 1 / 5 to 1 / 2 of the diameter of the reaction section of the microchannel aldol condensation reactor 1, and more preferably 1 / 4 to 1 / 2. The advantages of this preferred embodiment are that the throughput is matched to the microchannel aldol condensation reactor, the flow rate and pressure drop within the reactor are optimal, stratification of reactants within the reactor can be avoided, and equipment investment is optimized.

[0053] In this invention, preferably, the conditions for the second aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5 MPa, and a residence time of the first aldol condensation reaction product of 1-5 min; preferably, the conditions for the second aldol condensation reaction include: a reaction temperature of 120-130℃, a reaction pressure of 0.35-0.4 MPa, and a residence time of the first aldol condensation reaction product of 1-2 min. By using the apparatus of this invention in combination with the reaction conditions of this invention, it has the advantage of increasing the residence time of the aldol condensation reaction product and increasing the conversion rate of butyraldehyde.

[0054] In this invention, preferably, the top of the microchannel alcohol-aldehyde condensation reactor 1 is provided with a liquid phase inlet, which is used to transport the alkaline catalyst into the microchannel alcohol-aldehyde condensation reactor 1.

[0055] In this invention, preferably, the microchannel alcohol-aldehyde condensation reactor 1 is provided with a reaction raw material inlet at the top, which is located below the liquid phase inlet. The reaction raw material inlet is used to transport the reaction raw material n-butyraldehyde to the microchannel alcohol-aldehyde condensation reactor 1.

[0056] In this invention, preferably, the device further includes a distributor 4, which is disposed at the liquid phase inlet of the microchannel aldol condensation reactor 1 for distributing the alkaline catalyst.

[0057] In this invention, the type of distributor is not particularly limited, as long as it can achieve the distribution of materials, such as a perforated plate distributor or a perforated jet distributor.

[0058] In this invention, preferably, the method further includes returning the reaction product obtained from the second aldol condensation reaction to the downstream unit for reuse.

[0059] According to a specific embodiment of the present invention, the method is as follows: Figure 1 The aldol condensation reaction is carried out in the apparatus shown. The aldol condensation reaction apparatus includes a microchannel aldol condensation reactor 1 and an aldol condensation tubular reactor 2 connected in series. The microchannel aldol condensation reactor 1 includes a feed section, a buffer section and a reaction section arranged from top to bottom. The height-to-diameter ratio of the reaction section is 5:1-10:1. Multiple microchannel reaction tubes 3 are arranged in the reaction section. The microchannel reaction tubes 3 are arranged side by side inside the reaction section. Multiple static mixers are arranged inside each microchannel reaction tube 3.

[0060] The microchannel alcohol-aldehyde condensation reactor 1 is provided with a liquid phase inlet at its top. A distributor 4 is installed at the liquid phase inlet of the microchannel alcohol-aldehyde condensation reactor 1. The alkaline catalyst enters the microchannel alcohol-aldehyde condensation reactor 1 through the liquid phase inlet and is distributed by the distributor 4 before entering the microchannel alcohol-aldehyde condensation reactor 1. A reactant inlet is provided at the upper part of the microchannel alcohol-aldehyde condensation reactor 1, located below the liquid phase inlet. The reactant n-butyraldehyde enters the microchannel alcohol-aldehyde condensation reactor 1 through the reactant inlet. Inside, two streams of material sequentially enter the microchannel aldol condensation reactor 1 through the feed section, buffer section, and reaction section. The first aldol condensation reaction takes place in the microchannel reaction tube 3 of the reaction section. The conditions for the first aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5MPa, a residence time of the reactant n-butyraldehyde and the alkaline catalyst in the reaction section of 5-10s, and a flow rate of the reactant n-butyraldehyde and the alkaline catalyst in the reaction section of more than 2m / s, to obtain the first aldol condensation reaction product.

[0061] The heat generated during the first alcohol-aldehyde condensation reaction is removed by the cooling medium from the microchannel reaction tube 3 of the microchannel alcohol-aldehyde condensation reactor 1.

[0062] The first aldol condensation reaction product enters the aldol condensation tubular reactor 2 for a second aldol condensation reaction. The aldol condensation tubular reactor 2 is a serpentine tubular reactor with a length-to-diameter ratio of 25-30:1. The diameter of the aldol condensation tubular reactor 2 is 1 / 5-1 / 2 of the diameter of the microchannel aldol condensation reactor 1. The conditions for the second aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5MPa, and a residence time of the first aldol condensation reaction product of 1-5min.

[0063] The present invention will be described in detail below through embodiments.

[0064] Example 1

[0065] The method is as follows: Figure 1 The aldol condensation reaction is carried out in the apparatus shown. The aldol condensation reaction apparatus includes a microchannel aldol condensation reactor 1 and an aldol condensation tubular reactor 2 connected in series. The microchannel aldol condensation reactor 1 includes a feed section, a buffer section, and a reaction section arranged from top to bottom, with a height-to-diameter ratio of 8:1 for the reaction section. The aldol condensation tubular reactor 2 is a serpentine tubular reactor with a length-to-diameter ratio of 30:1. The microchannel aldol condensation reactor 1 has 3989 microchannel reaction tubes 3 arranged side by side inside, and each microchannel reaction tube 3 is equipped with 8 static mixers (model SK-10 / 20 in HG / T20570-95). The diameter of the aldol condensation tubular reactor 2 is 1 / 4 of the diameter of the reaction section of the microchannel aldol condensation reactor 1.

[0066] A distributor 4 (porous jet distributor) is provided at the liquid phase inlet of the microchannel alcohol-aldehyde condensation reactor 1. A liquid phase inlet is located at the top of the microchannel alcohol-aldehyde condensation reactor 1. Sodium hydroxide enters the microchannel alcohol-aldehyde condensation reactor 1 through the liquid phase inlet and is distributed by the distributor 4 before entering the microchannel alcohol-aldehyde condensation reactor 1. A reactant inlet is located at the upper part of the microchannel alcohol-aldehyde condensation reactor 1, below the liquid phase inlet. The reactant n-butyraldehyde enters the interior of the microchannel alcohol-aldehyde condensation reactor 1 through the reactant inlet. Butyraldehyde and sodium hydroxide, an alkaline catalyst, are sequentially fed through a feed section, a buffer section, and a reaction section. A first aldol condensation reaction is carried out in the microchannel reaction tube 3 of the reaction section. The volume ratio of the reactant n-butyraldehyde to the alkaline catalyst is 10:1. The conditions for the first aldol condensation reaction include: a reaction temperature of 120°C, a reaction pressure of 0.4 MPa, a residence time of 5 s for the reactants n-butyraldehyde and sodium hydroxide, and a flow rate of 2.5 m / s for the reactant n-butyraldehyde. The first aldol condensation reaction product is obtained, and the conversion rate of the reactant n-butyraldehyde is 70%.

[0067] The heat generated during the first alcohol-aldehyde condensation reaction is cooled by the cooling medium (cooling water, inlet temperature 33℃) on the shell of the microchannel reaction tube 3 in the microchannel alcohol-aldehyde condensation reactor 1, and the temperature of the reaction product is controlled at 120℃.

[0068] The first aldol condensation reaction product enters the aldol condensation tubular reactor 2 for a second aldol condensation reaction. The conditions for the second aldol condensation reaction include: a reaction temperature of 120°C, a reaction pressure of 0.35 MPa, and a residence time of 1 min for the first aldol condensation reaction product, to obtain the reaction product EPA.

[0069] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 92%, the yield of the target product was 85%, and the content of heavy alcohols in the reaction product was 2%.

[0070] Example 2

[0071] According to the method of Example 1, the aldol condensation reaction apparatus includes a microchannel aldol condensation reactor 1 and an aldol condensation tubular reactor 2 connected in series. The microchannel aldol condensation reactor 1 includes a feed section, a buffer section, and a reaction section arranged from top to bottom, with a height-to-diameter ratio of 10:1 for the reaction section. The aldol condensation tubular reactor 2 is a serpentine tubular reactor with a length-to-diameter ratio of 30:1. The microchannel aldol condensation reactor 1 has 3989 microchannel reaction tubes 3 arranged side by side inside, and each microchannel reaction tube 3 is equipped with 10 static mixers (model SK-10 / 20). The diameter of the tube in the aldol condensation tubular reactor 2 is 1 / 4 of the diameter of the reaction section in the microchannel aldol condensation reactor 1.

[0072] A distributor 4 (porous jet distributor) is provided at the liquid phase inlet of the microchannel alcohol-aldehyde condensation reactor 1. A liquid phase inlet is located at the top of the microchannel alcohol-aldehyde condensation reactor 1. Sodium hydroxide enters the microchannel alcohol-aldehyde condensation reactor 1 through the liquid phase inlet and is distributed by the distributor 4 before entering the microchannel alcohol-aldehyde condensation reactor 1. A reaction raw material inlet is located at the upper part of the microchannel alcohol-aldehyde condensation reactor 1, below the liquid phase inlet. The reaction raw material n-butyraldehyde enters the interior of the microchannel alcohol-aldehyde condensation reactor 1 through the reaction raw material inlet. The raw material n-butyraldehyde and the alkaline catalyst sodium hydroxide are sequentially fed through a feed section, a buffer section, and a reaction section. A first alcohol-aldol condensation reaction is carried out in the microchannel reaction tube 3 of the reaction section. The volume ratio of the raw material n-butyraldehyde to the alkaline catalyst is 10:1. The conditions for the first alcohol-aldol condensation reaction include: a reaction temperature of 120℃, a reaction pressure of 0.4MPa, a residence time of 8s for the raw material n-butyraldehyde and the sodium hydroxide, and a flow rate of 2.5m / s for the raw material n-butyraldehyde. The first alcohol-aldol condensation reaction product is obtained, and the conversion rate of the raw material n-butyraldehyde is 72%.

[0073] The heat generated during the first alcohol-aldehyde condensation reaction is cooled by the cooling medium (cooling water, inlet temperature 33℃) on the shell of the microchannel reaction tube 3 in the microchannel alcohol-aldehyde condensation reactor 1, and the temperature of the reaction product is controlled at 120℃.

[0074] The first aldol condensation reaction product enters the aldol condensation tubular reactor 2 for a second aldol condensation reaction. The conditions for the second aldol condensation reaction include: a reaction temperature of 120°C, a reaction pressure of 0.35 MPa, and a residence time of 1 min for the first aldol condensation reaction product, to obtain the reaction product EPA.

[0075] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 90%, the yield of the target product was 84%, and the content of heavy alcohols in the reaction product was 2.3%.

[0076] Example 3

[0077] The method is the same as in Example 1, except that the reaction pressure of the first aldol condensation reaction is 0.45 MPa.

[0078] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 88%, the yield of the target product was 82%, and the content of heavy alcohols in the reaction product was 2.3%.

[0079] Example 4

[0080] The method is the same as in Example 1, except that the reaction temperature of the first aldol condensation reaction is 130°C.

[0081] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 91%, the yield of the target product was 82%, and the content of heavy alcohols in the reaction product was 2.4%.

[0082] Example 5

[0083] The method is the same as in Example 1, except that the volume ratio of the reaction raw material n-butyraldehyde to the alkaline catalyst is 9:1.

[0084] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 86%, the yield of the target product was 79%, and the content of heavy alcohols in the reaction product was 2.5%.

[0085] Example 6

[0086] The method is the same as in Example 1, except that the operating pressure (reaction pressure of the second alcohol-aldol condensation reaction) of the aldol condensation tubular reactor 2 is 0.4 MPa.

[0087] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 90%, the yield of the target product was 83%, and the content of heavy alcohols in the reaction product was 2.2%.

[0088] Example 7

[0089] The method is the same as in Example 1, except that the length-to-diameter ratio of the first aldol condensation reaction product in the aldol condensation tubular reactor 2 is 25:1.

[0090] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 91%, the yield of the target product was 83%, and the content of heavy alcohols in the reaction product was 2.4%.

[0091] Example 8

[0092] The method is the same as in Example 1, except that the diameter of the tube in the aldol condensation tubular reactor 2 is half the diameter of the reaction section of the microchannel aldol condensation reactor 1.

[0093] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 90%, the yield of the target product was 82%, and the content of heavy alcohols in the reaction product was 2.5%.

[0094] Example 9

[0095] According to the method of Example 1, the aldol condensation reaction apparatus includes a microchannel aldol condensation reactor 1 and an aldol condensation tubular reactor 2 connected in series. The microchannel aldol condensation reactor 1 includes a feed section, a buffer section, and a reaction section arranged from top to bottom, with a height-to-diameter ratio of 6:1 for the reaction section. The aldol condensation tubular reactor 2 is a serpentine tubular reactor with a length-to-diameter ratio of 30:1. The microchannel aldol condensation reactor 1 is equipped with 3989 microchannel reaction tubes 3, and each microchannel reaction tube 3 is equipped with 6 static mixers (model SK-10 / 20). The diameter of the tube in the aldol condensation tubular reactor 2 is 1 / 4 of the diameter of the reaction section in the microchannel aldol condensation reactor 1.

[0096] A distributor 4 (porous jet distributor) is provided at the liquid phase inlet of the microchannel alcohol-aldehyde condensation reactor 1. A liquid phase inlet is located at the top of the microchannel alcohol-aldehyde condensation reactor 1. Sodium hydroxide enters the microchannel alcohol-aldehyde condensation reactor 1 through the liquid phase inlet and is distributed by the distributor 4 before entering the microchannel alcohol-aldehyde condensation reactor 1. A reactant inlet is located at the upper part of the microchannel alcohol-aldehyde condensation reactor 1, below the liquid phase inlet. The reactant n-butyraldehyde enters the interior of the microchannel alcohol-aldehyde condensation reactor 1 through the reactant inlet. The reactants n-butyraldehyde and sodium hydroxide are sequentially fed through a feed section, a buffer section, and a reaction section. A first alcohol-aldol condensation reaction is carried out in the microchannel reaction tube 3 of the reaction section. The volume ratio of n-butyraldehyde to the alkaline catalyst is 10:1. The conditions for the first alcohol-aldol condensation reaction include: a reaction temperature of 120°C, a reaction pressure of 0.4 MPa, a residence time of 4 s for n-butyraldehyde and sodium hydroxide, and a flow rate of 2.5 m / s for n-butyraldehyde. The first alcohol-aldol condensation reaction product is obtained, and the conversion rate of n-butyraldehyde is 65%.

[0097] The heat generated during the first alcohol-aldehyde condensation reaction is cooled by the cooling medium (cooling water, inlet temperature 33℃) on the shell of the microchannel reaction tube 3 in the microchannel alcohol-aldehyde condensation reactor 1, and the temperature of the reaction product is controlled at 120℃.

[0098] The first aldol condensation reaction product enters the aldol condensation tubular reactor 2 for a second aldol condensation reaction. The conditions for the second aldol condensation reaction include: a reaction temperature of 120°C, a reaction pressure of 0.35 MPa, and a residence time of 1 min for the first aldol condensation reaction product, to obtain the reaction product EPA.

[0099] Gas chromatography was used to analyze the components and found that the conversion rate of n-butyraldehyde was 89%, the yield of the target product was 84%, and the content of heavy alcohols in the reaction product was 2.8%.

[0100] Comparative Example

[0101] Using existing technologies such as Figure 2 The fully mixed reactor shown is used for aldol condensation reaction. The fully mixed reactor includes an aldol condensation reactor body 1 and an aldol condensation reactor stirrer 2 installed inside the aldol condensation reactor body 1. The volume ratio of the reaction raw material n-butyraldehyde to the alkaline catalyst sodium hydroxide is 10:1. The reaction is carried out at an operating temperature of 120°C and an operating pressure of 0.4 MPa for 2 min.

[0102] Using component analysis, the conversion rate of n-butyraldehyde was found to be 92%, the yield of the target product was 83%, and the content of heavy alcohols in the reaction product was 3%.

[0103] As can be seen from the examples and comparative examples, the present invention employs an optimized design combining a microchannel reactor and a tubular reactor. This design achieves uniform mixing of reactants within the microchannel reactor, effectively improving the selectivity of the main reaction, the butyraldehyde-aldol condensation reaction, while reducing the selectivity of the side reaction, the butyraldehyde-octenal reaction. This significantly reduces the yield of heavy alcohols and increases the yield of the reaction product, octenal. Furthermore, the absence of a stirrer reduces the probability of reactant leakage, improving industrial safety.

[0104] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for an aldol condensation reaction, wherein, The method is carried out in an aldol condensation reaction apparatus, which includes a microchannel aldol condensation reactor (1) and an aldol condensation tubular reactor (2) connected in series. In the presence of an alkaline catalyst, the reaction raw material n-butyraldehyde undergoes a first alcohol-aldol condensation reaction in the microchannel alcohol-aldol condensation reactor (1) to obtain the first alcohol-aldol condensation reaction product. The product of the first aldol condensation reaction undergoes a second aldol condensation reaction in the aldol condensation tubular reactor (2).

2. The reaction method according to claim 1, wherein, The microchannel aldol condensation reactor (1) is a vertical reactor; Preferably, the microchannel aldol condensation reactor (1) includes a feed section, a buffer section and a reaction section arranged from top to bottom; Preferably, a microchannel reaction tube (3) is provided in the reaction section for performing a first alcohol-aldehyde condensation reaction on the reaction raw material n-butyraldehyde and the alkaline catalyst; Preferably, multiple microchannel reaction tubes (3) are provided, and the multiple microchannel reaction tubes (3) are arranged side by side inside the reaction section; Preferably, the height-to-diameter ratio of the reaction section is 5:1-10:1, more preferably 8:1-10:1, where the height is the height of the microchannel reaction tube (3) in the reaction section, and the diameter is the diameter of the reaction section.

3. The reaction method according to claim 2, wherein, Preferably, a static mixer is provided inside the microchannel reaction tube (3), which is used to carry out the first alcohol-aldehyde condensation reaction after mixing the reaction raw material n-butyraldehyde and the base catalyst.

4. The reaction method according to claim 2 or 3, wherein, In the first alcohol-aldol condensation reaction, the conversion rate of the reaction raw material n-butyraldehyde is 65-75%, preferably 68-72%.

5. The reaction method according to any one of claims 1-4, wherein, The alkaline catalyst is selected from alkaline compounds, preferably sodium hydroxide; Preferably, the volume ratio of the reaction raw material n-butyraldehyde to the alkaline catalyst is 6-10:

1.

6. The reaction method according to any one of claims 2-5, wherein, The conditions for the first aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5MPa, and a residence time of the reaction raw material n-butyraldehyde and the alkaline catalyst in the reaction section of 5-10s; Preferably, the conditions for the first aldol condensation reaction include: a reaction temperature of 120-130℃, a reaction pressure of 0.4-0.45MPa, and a residence time of the reaction raw material n-butyraldehyde and the alkaline catalyst in the reaction section of 5-8s; Preferably, the flow rates of the reaction raw material n-butyraldehyde and the alkaline catalyst in the reaction section are above 2 m / s, and more preferably 2-3 m / s.

7. The method according to any one of claims 2-6, wherein, The method further includes: using a cooling medium to cool the microchannel reaction tube (3) to remove heat from the reaction; Preferably, the temperature of the cooling medium is 30-35°C.

8. The method according to any one of claims 2-7, wherein, The aldol condensation tubular reactor (2) is a serpentine tubular reactor; Preferably, the length-to-diameter ratio of the aldol condensation tubular reactor (2) is 25-30:1, wherein the length is the total length of the aldol condensation tubular reactor (2), and the diameter is the tube diameter of the aldol condensation tubular reactor (2). Preferably, the diameter of the tube of the aldol condensation tubular reactor (2) is 1 / 5 to 1 / 2 of the diameter of the reaction section of the microchannel aldol condensation reactor (1), and more preferably 1 / 4 to 1 / 2.

9. The method according to any one of claims 1-8, wherein, The conditions for the second aldol condensation reaction include: a reaction temperature of 110-140℃, a reaction pressure of 0.3-0.5MPa, and a residence time of the product of the first aldol condensation reaction of 1-5min. Preferably, the conditions for the second aldol condensation reaction include: a reaction temperature of 120-130°C, a reaction pressure of 0.35-0.4 MPa, and a residence time of the product of the first aldol condensation reaction of 1-2 min.

10. The method according to any one of claims 1-9, wherein, The device also includes a distributor (4), which is disposed at the liquid inlet of the microchannel aldol condensation reactor (1) for distributing the alkaline catalyst.

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