Preparation method of 3-hydroxypropionaldehyde

Abstract

The invention provides a preparation method of 3-hydroxy propionaldehyde. The preparation method comprises the following steps: step S1, providing a reactor, the reactor comprising M fixed bed reactors, each fixed bed reactor being internally provided with N catalytic units which are communicated with each other, M being greater than or equal to 1 and less than or equal to N, M and N being not equal to 1 at the same time, each fixed bed reactor being provided with a feed port and a discharge port, and each catalytic unit being provided with an acrolein solution inlet; and S2, respectively introducing an acrolein solution into the catalytic unit from the acrolein solution inlets, simultaneously introducing water into the feed port of the fixed bed reactor, so that the acrolein solution and the water are subjected to an addition reaction in the catalytic unit, and then discharging a product of the addition reaction through the discharge port of the fixed bed reactor, thereby obtaining the 3-hydroxypropionaldehyde. The preparation method provided by the invention solves the problems of low conversion frequency and easy hardening of the catalyst for the acrolein hydration reaction.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing 3-hydroxypropanal. Background Art

[0002] Polytrimethylene terephthalate fiber (PTT), as an important polyester material, is widely used in clothing, carpets, plastic accessories and engineering plastics. As a polymerization monomer for synthesizing PTT, there is a lot of room for improvement in the production process of 1,3-propylene glycol. There are various preparation processes for 1,3-propylene glycol, each with its own advantages and disadvantages. Common process methods include acrolein hydration hydrogenation, ethylene oxide carbonylation, and biological fermentation. Among them, the acrolein hydration hydrogenation method has unique advantages due to its relatively simple process, relatively mild conditions, few product by-products, and easy purification and separation.

[0003] The first step of the acrolein hydration hydrogenation method is the hydration of acrolein to prepare 3-hydroxypropionaldehyde. This reaction process is also the key step in the production of 1,3-propylene glycol by the acrolein hydration hydrogenation method. Fixed-bed catalytic processes are often used in industry. Acidic solid catalysts are filled in fixed beds, and acrolein is catalytically converted into 3-hydroxypropionaldehyde when it flows through the catalyst. In actual production, if the reaction is required to have high selectivity, a low reaction temperature must be maintained, but a low reaction temperature will lead to a low conversion rate; increasing the temperature can increase the conversion rate, but the selectivity will decrease. The traditional production method is to pump the acrolein aqueous solution raw material into the reactor at one time until it flows out of the reactor. In the early stage, the acrolein reaction concentration is high, the catalyst conversion frequency is low, the raw material is easy to self-polymerize, and many impurities are generated. The reaction is easy to cause catalyst caking and increase the bed pressure drop under long-term operation.

[0004] The disadvantages of the existing process include: first, the traditional process does not have fresh materials to supplement the entire reaction process, which easily leads to a high conversion frequency of the catalyst in the front stage and a low conversion frequency of the catalyst in the back stage; second, the heavy components produced during the acrolein hydration reaction belong to a series linear reaction. According to the principle of reaction kinetics, the high-concentration raw materials in the front stage and the large amount of 3-hydroxypropanal produced will have a longer residence time in the reactor, which will promote the production of subsequent heavy components such as 4-heterooxyheptanedial and other impurities; third, high-concentration acrolein self-polymerizes in the fixed bed, causing the catalyst particles to adhere to each other, and the polymer adheres to the surface of the catalyst particles, resulting in an increase in the catalyst particle size. The catalyst particles squeezed against each other will also promote agglomeration. At the same time, after the hydrogen ions on the acidic resin catalyst are replaced by a small amount of metal ions in the water, the volume will expand significantly, resulting in an increase in the volume of the catalyst particles, which in turn causes the catalyst to be squeezed and agglomerated.

[0005] The Chinese patent application with the patent application publication number CN113105315A discloses a method of using an organic solvent and pressurization to improve the solubility of acrolein, inhibit the gasification and polymerization of acrolein, thereby reducing the tendency of raw materials and products to polymerize, but it is obviously necessary to increase separation and equipment investment costs. The Chinese patent application with the patent application publication number CN117510320A discloses that by using a chelating resin to remove metal ions, the polymerization problem caused by metal ion enrichment is slowed down, thereby reducing side reactions and inhibiting catalyst caking, but the problem of impurities generated by the self-polymerization or polycondensation of acrolein and 3-hydroxypropanal is not considered. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for preparing 3-hydroxypropanal, so as to solve the problems of low conversion frequency and easy agglomeration of the catalyst used in the prior art for the hydration reaction of acrolein.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing 3-hydroxypropanal is provided, and the method comprises the following steps: step S1, providing a reactor, the reactor comprising M fixed bed reactors, each fixed bed reactor being provided with N catalytic units interconnected with each other, 1≤M, 1≤N, M and N are not 1 at the same time, each fixed bed reactor being provided with a feed port and a discharge port, and each catalytic unit having an acrolein solution inlet; step S2, introducing an acrolein solution into the catalytic unit from each acrolein solution inlet, and simultaneously introducing water into the feed port of the fixed bed reactor, so that the acrolein solution and water undergo an addition reaction in the catalytic unit, and then discharging the product of the addition reaction through the discharge port of the fixed bed reactor, thereby obtaining 3-hydroxypropanal.

[0008] Furthermore, the M fixed bed reactors are sequentially arranged in series. In step S2, water is introduced from the feed port of the first fixed bed reactor located upstream, and the product of the addition reaction is discharged through the discharge port of the last fixed bed reactor located downstream.

[0009] Furthermore, the M fixed bed reactors are arranged in parallel. In step S2, water is introduced from the feed port of each fixed bed reactor located upstream, and the product of the addition reaction is discharged through the discharge port of each fixed bed reactor located downstream.

[0010] Furthermore, the above-mentioned M≤6, N≤6; and / or, the catalytic unit includes a distributor, a catalyst layer and an expansion space arranged in sequence along the material flow direction; preferably, the fixed bed reactor is a vertical reactor, the feed inlet is arranged at the bottom of the fixed bed reactor, the discharge port is arranged at the top of the fixed bed reactor, and the catalytic unit is sequentially provided with a distributor, a catalyst layer and an expansion space from bottom to top; and / or, the filling coefficient of the catalyst layer is 0.5-0.9; and / or, the ratio of the volume of the expansion space to the volume of the catalyst layer is 10-40:100; and / or, the catalyst loaded in the catalyst layer is selected from any one or more of polystyrene aminoacetic acid resin, polystyrene propionic acid resin, polystyrene aminophosphoric acid resin, polystyrene sulfonic acid resin and polypropionic acid resin.

[0011] Furthermore, the length-to-diameter ratio of the fixed bed reactor is 2 to 35:1; and / or a filter is arranged on the top of the fixed bed reactor.

[0012] Furthermore, the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is 10-25:100; and / or the temperature of the water is 30-80°C; and / or the mass space velocity of the water is 0.2-1h -1 .

[0013] Furthermore, along the material flow direction, the mass flow rate of acrolein solution entering each catalytic unit decreases successively; preferably, the ratio of the maximum mass flow rate of acrolein solution flowing into each catalytic unit to the minimum mass flow rate of acrolein solution flowing into each catalytic unit is 5.7-60:1.

[0014] Furthermore, the temperature of the addition reaction is 30 to 80° C.; and / or the pressure of the addition reaction is 0.05 to 2 MPa.

[0015] Furthermore, the mass concentration of the acrolein solution is 75% to 99.9%.

[0016] Furthermore, the acrolein solution contains 500-5000 ppm of a polymerization inhibitor; and / or the polymerization inhibitor is selected from any one or more of hydroquinone, 2,6-di-tert-butyl-p-cresol and p-tert-butylcatechol.

[0017] By applying the technical solution of the present invention, the reactor of the present application includes at least two catalytic units. By respectively introducing acrolein solution into each catalytic unit, the concentration distribution of the acrolein solution in the reactor is helped to be more uniform, thereby helping to maintain the side reactions at a low level, reducing the rate of catalyst agglomeration, and maintaining a high conversion frequency of the rear-stage catalyst, thereby helping to improve the selectivity of the acrolein hydration reaction, extend the service life of the catalyst, improve the stability of the device operation and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 The schematic diagram of the structure of the reactor in Example 1 of the present application is shown.

[0020] The above drawings include the following reference numerals:

[0021] 1. Catalytic unit; 2. Filter; 11. Distributor; 12. Catalyst layer; 13. Expansion space. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] As analyzed in the background technology of the present application, the catalysts used in the prior art for the hydration reaction of acrolein have the problems of low conversion frequency and easy hardening. In order to solve the above problems, the present application provides a method for preparing 3-hydroxypropanal.

[0024] In a typical embodiment of the present application, a method for preparing 3-hydroxypropanal is provided, and the method comprises the following steps: step S1, providing a reactor, the reactor comprising M fixed bed reactors, each fixed bed reactor being provided with N interconnected catalytic units 1, 1≤M, 1≤N, M and N are not 1 at the same time, each fixed bed reactor being provided with a feed port and a discharge port, and each catalytic unit 1 having an acrolein solution inlet; step S2, introducing an acrolein solution into the catalytic unit 1 from each acrolein solution inlet, and simultaneously introducing water into the feed port of the fixed bed reactor, so that the acrolein solution and water undergo an addition reaction in the catalytic unit 1, and then discharging the product of the addition reaction through the discharge port of the fixed bed reactor, thereby obtaining 3-hydroxypropanal.

[0025] The reactor of the present application comprises at least two catalytic units 1, and the structural schematic diagram of the reactor is as follows: Figure 1 By introducing the acrolein solution into each catalytic unit 1 respectively, the concentration distribution of the acrolein solution in the reactor is helped to be more uniform, thereby helping to maintain the side reaction at a low level, reducing the rate of catalyst agglomeration, and maintaining a high conversion frequency of the rear-stage catalyst, thereby helping to improve the selectivity of the acrolein hydration reaction, extend the service life of the catalyst, improve the stability of the device operation, and reduce the production cost.

[0026] In order to further reduce the rate at which the catalyst becomes caking, in one embodiment of the present application, it is preferred that the above-mentioned M fixed bed reactors are arranged in series in sequence. In step S2, water is introduced from the feed port of the first fixed bed reactor located upstream, and the product of the addition reaction is discharged through the discharge port of the last fixed bed reactor located downstream.

[0027] An optional connection method between fixed bed reactors is provided. In one embodiment of the present application, the above-mentioned M fixed bed reactors are arranged in parallel. In step S2, water is introduced from the feed port of each fixed bed reactor located upstream, and the product of the addition reaction is discharged through the discharge port of each fixed bed reactor located downstream.

[0028] In one embodiment of the present application, M≤6, N≤6; and / or, the catalytic unit 1 includes a distributor 11, a catalyst layer 12 and an expansion space 13 arranged in sequence along the material flow direction; preferably, the fixed bed reactor is a vertical reactor, the feed inlet is arranged at the bottom of the fixed bed reactor, the discharge port is arranged at the top of the fixed bed reactor, and the catalytic unit 1 is provided with a distributor 11, a catalyst layer 12 and an expansion space 13 from bottom to top; and / or, the filling coefficient of the catalyst layer 12 is 0.5-0.9; and / or, the ratio of the volume of the expansion space 13 to the volume of the catalyst layer 12 is 10-40:100; and / or, the catalyst loaded in the catalyst layer 12 is selected from any one or more of polystyrene aminoacetic acid resin, polystyrene propionic acid resin, polystyrene aminophosphoric acid resin, polystyrene sulfonic acid resin and polypropionic acid resin.

[0029] Too many catalytic units 1 and fixed bed reactors are not conducive to the precise control of acrolein mass flow and the reduction of production costs. It is preferred to control the number of catalytic units 1 and fixed bed reactors within the above range, which is conducive to maintaining the catalyst at a higher conversion frequency, thereby helping to improve the selectivity of acrolein hydration reaction and extend the service life of the catalyst while improving the reliability of the device operation and controlling production costs. The distributor 11 is fixed to the inner wall of the fixed bed reactor, which helps to improve the support effect on the catalyst layer 12, thereby helping to reduce the squeezing effect of other materials on the catalyst layer 12; the presence of the expansion space 13 helps to weaken the expansion and squeezing effect caused by the polymer coating on the surface of the catalyst particles and the resin from the hydrogen type to the sodium type. It is preferred to control the filling coefficient of the catalyst layer 12 within the above range, which helps to make the catalyst fully contact with the acrolein solution and water, thereby helping to improve the catalytic efficiency of the catalyst. It is preferred to control the ratio of the volume of the expansion space 13 to the volume of the catalyst layer 12 within the above range, which helps to further reduce the impact of expansion and squeezing on the catalyst. It is preferred to control the type of catalyst within the above range, which helps to further improve the catalytic efficiency of the catalyst.

[0030] In one embodiment of the present application, the aspect ratio of the fixed bed reactor is 2 to 35:1; and / or a filter 2 is arranged on the top of the fixed bed reactor.

[0031] The aspect ratio of the fixed bed reactor is too high, which is not conducive to controlling the fixed bed reactor to maintain a low pressure drop, and is not conducive to the loading and unloading of the catalyst. The aspect ratio of the fixed bed reactor is too low, which is not conducive to the number of additional catalytic units and the uniformity of the radial temperature control. It is preferred to control the aspect ratio of the fixed bed reactor within the above range, which helps to control the fixed bed reactor to maintain a low pressure drop and a more uniform temperature distribution. It is preferred to set a filter 2 on the top of the fixed bed reactor to help intercept the floating catalyst and capture the generated polymer. In addition, the size of each fixed bed reactor can be the same or different.

[0032] In one embodiment of the present application, the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is 10-25:100; and / or the temperature of the water is 30-80°C; and / or the mass space velocity of the water is 0.2-1h -1 .

[0033] Preferably, the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is controlled within the above range, which helps to improve the reaction efficiency of the addition reaction, thereby helping to improve the conversion rate of the acrolein solution. Too high a water temperature is not conducive to reducing the content of by-products, and too low a water temperature is not conducive to increasing the speed of the addition reaction. Preferably, the water temperature is controlled within the above range, which helps to improve the conversion rate of the acrolein solution. Preferably, the mass space velocity of water is controlled within the above range, which helps to make water fully contact with the acrolein solution and the catalyst, thereby helping the reaction efficiency of the addition reaction.

[0034] In one embodiment of the present application, along the material flow direction, the mass flow rate of the acrolein solution entering each catalytic unit 1 decreases successively; preferably, the ratio of the maximum mass flow rate of the acrolein solution flowing into each catalytic unit 1 to the minimum mass flow rate of the acrolein solution flowing into each catalytic unit 1 is 5.7 to 60:1.

[0035] Preferably, the mass flow rate of the acrolein solution entering each catalytic unit 1 is reduced in sequence, which helps to further maintain the acrolein solution in the reactor at a certain concentration, thereby helping to further maintain the side reaction at a low level, reduce the rate of catalyst agglomeration, and maintain a high conversion frequency of the rear-stage catalyst. Preferably, the ratio of the maximum mass flow rate of the acrolein solution flowing into each catalytic unit 1 to the minimum mass flow rate of the acrolein solution flowing into each catalytic unit 1 is controlled within the above range, which helps to further maintain a high conversion frequency of the rear-stage catalyst.

[0036] In one embodiment of the present application, the temperature of the addition reaction is 30-80° C.; and / or the pressure of the addition reaction is 0.05-2 MPa.

[0037] If the temperature of the addition reaction is too high, it is not conducive to reducing the content of by-products, and if the temperature of the addition reaction is too low, it is not conducive to increasing the speed of the addition reaction. It is preferred to control the temperature of the addition reaction within the above range, which helps to improve the efficiency of the addition reaction. It is preferred to control the pressure of the addition reaction within the above range, which helps to further improve the efficiency of the addition reaction.

[0038] In order to further improve the conversion rate of acrolein, in one embodiment of the present application, the mass concentration of the acrolein solution is preferably 75% to 99.9%, and the mass concentrations of acrolein entering different catalytic units 1 may be the same or different.

[0039] In order to further reduce the probability of polymerization reaction occurring during the reaction process, in one embodiment of the present application, it is preferred that the acrolein solution contains 500 to 5000 ppm of a polymerization inhibitor; and / or the polymerization inhibitor is selected from any one or more of hydroquinone, 2,6-di-tert-butyl-p-cresol and p-tert-butylcatechol.

[0040] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0041] Example 1

[0042] Use Figure 1 The reactor is used for acrolein hydration reaction. Specifically, the reactor contains two fixed bed reactors connected in series, each reactor is provided with three catalytic units 1, water is introduced from the lower end feed port of the first fixed bed reactor, acrolein solution is introduced from the lower end of each distributor 11, and the material after the addition reaction of water and acrolein solution under the catalysis of the catalyst layer 12 passes through the expansion space 13 and the filter 2, and is discharged from the upper end discharge port of the last fixed bed reactor to obtain 3-hydroxypropanal, wherein the acrolein solution contains 2000ppm of hydroquinone, the aspect ratio of each fixed bed reactor is 20:1, the catalyst is polystyrene aminoacetic acid resin, the filling coefficient of the catalyst layer 12 is 0.7, the ratio of the volume of the expansion space 13 to the volume of the catalyst layer 12 is 35:100, and the mass space velocity of water is 0.25h -1 , the mass flow rate of water is a, the total mass flow rate of acrolein solution entering the reactor is b=0.18a, the mass concentration of acrolein solution is 96%, the mass flow rates of acrolein solution entering the first catalytic unit to the sixth catalytic unit are 0.4b, 0.2b, 0.15b, 0.1b, 0.08b and 0.07b respectively, the temperature of water is 45°C, the temperature of the addition reaction is 50°C, and the pressure of the addition reaction is 1MPa.

[0043] Example 2

[0044] The difference from Example 1 is that the number of fixed bed reactors is 2, each fixed bed reactor contains 2 catalytic units 1, and the mass flow rates of acrolein solution entering the first catalytic unit to the fourth catalytic unit are 0.6b, 0.2b, 0.15b and 0.05b respectively, and 3-hydroxypropionaldehyde is finally obtained.

[0045] Example 3

[0046] The difference from Example 1 is that the number of fixed bed reactors is 3, each fixed bed reactor contains one catalytic unit 1, the filling coefficient of the catalyst layer is 0.75, and the mass space velocity of water is 0.35h -1 The mass flow rates of acrolein solution entering the first catalytic unit to the third catalytic unit are 0.6b, 0.3b, and 0.1b, respectively, and 3-hydroxypropionaldehyde is finally obtained.

[0047] Example 4

[0048] The difference from Example 1 is that the number of fixed bed reactors is 3, each fixed bed reactor contains 2 catalytic units 1, the filling coefficient of the catalyst layer is 0.75, and the mass space velocity of water is 0.35h -1 The mass flow rates of acrolein solution entering the first catalytic unit to the sixth catalytic unit are 0.6b, 0.2b, 0.15b, 0.02b, 0.02b, and 0.01b, respectively, and 3-hydroxypropionaldehyde is finally obtained.

[0049] Example 5

[0050] The difference from Example 1 is that the number of fixed bed reactors is 3, each fixed bed reactor contains 4 catalytic units 1, the filling coefficient of the catalyst layer is 0.75, and the mass space velocity of water is 0.35h -1 The mass flow rates of acrolein solution entering the first catalytic unit to the twelfth catalytic unit are 0.5b, 0.1b, 0.1b, 0.05b, 0.05b, 0.04b, 0.04b, 0.03b, 0.03b, 0.02b, 0.02b, and 0.02b, respectively, and 3-hydroxypropionaldehyde is finally obtained.

[0051] Example 6

[0052] The difference from Example 1 is that the filling coefficient of the catalyst layer is 0.5, the ratio of the volume of the expansion space to the volume of the catalyst layer is 40:100, and 3-hydroxypropionaldehyde is finally obtained.

[0053] Example 7

[0054] The difference from Example 1 is that the filling coefficient of the catalyst layer is 0.9, the ratio of the volume of the expansion space to the volume of the catalyst layer is 10:100, and 3-hydroxypropionaldehyde is finally obtained.

[0055] Example 8

[0056] The difference from Example 1 is that the filling coefficient of the catalyst layer is 0.95, the ratio of the volume of the expansion space to the volume of the catalyst layer is 5:100, and 3-hydroxypropionaldehyde is finally obtained.

[0057] Example 9

[0058] The difference from Example 1 is that the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is 25:100, and 3-hydroxypropionaldehyde is finally obtained.

[0059] Example 10

[0060] The difference from Example 1 is that the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is 10:100, and 3-hydroxypropionaldehyde is finally obtained.

[0061] Embodiment 11

[0062] The difference from Example 1 is that the ratio of the total mass flow rate of the acrolein solution to the mass flow rate of water is 30:100, and 3-hydroxypropionaldehyde is finally obtained.

[0063] Example 12

[0064] The difference from Example 1 is that the water temperature is 80°C and the mass air velocity of water is 1h -1 , and finally 3-hydroxypropanal was obtained.

[0065] Embodiment 13

[0066] The difference from Example 1 is that the water temperature is 30°C and the mass air velocity of water is 0.2h -1 , and finally 3-hydroxypropanal was obtained.

[0067] Embodiment 14

[0068] The difference from Example 1 is that the water temperature is 85°C and the mass air velocity of water is 0.1h -1 , and finally 3-hydroxypropanal was obtained.

[0069] Embodiment 15

[0070] The difference from Example 1 is that the aspect ratio of the fixed bed reactor is 2:1, the temperature of the addition reaction is 30° C., the pressure of the addition reaction is 0.05 MPa, the mass concentration of the acrolein solution is 75%, the acrolein solution contains 500 ppm of 2,6-di-tert-butyl-p-cresol, and 3-hydroxypropanal is finally obtained.

[0071] Example 16

[0072] The difference from Example 1 is that the aspect ratio of the fixed bed reactor is 35:1, the temperature of the addition reaction is 80° C., the pressure of the addition reaction is 2 MPa, the mass concentration of the acrolein solution is 99.9%, the acrolein solution contains 5000 ppm of 2,6-di-tert-butyl-p-cresol, and 3-hydroxypropanal is finally obtained.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the number of fixed bed reactors is 1, each fixed bed reactor contains one catalytic unit 1, the filling coefficient of the catalyst layer is 1.0, and no catalyst expansion space volume is reserved, and 3-hydroxypropionaldehyde is finally obtained.

[0075] Under the conditions of Comparative Example 1, after 8000 hours of evaluation, the average selectivity of acrolein to 3-hydroxypropionaldehyde was 85.7%, the average content of heteroheptanedial was 3.8%, and the total pressure drop of the reactor was 0.2 MPa, which exceeded the upper limit of the resin catalyst operating pressure, and the evaluation was suspended.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that the number of fixed bed reactors is 1, each fixed bed reactor contains 1 catalytic unit 1, and 3-hydroxypropanal is finally obtained.

[0078] Under the conditions of the above example and comparative example 2, the reaction was carried out for 16000 hours. The results of the average selectivity of acrolein to prepare 3-hydroxypropanal, the average content of heteroheptanedial and the total pressure drop of the reactor are shown in Table 1.

[0079] Table 1

[0080]

[0081]

[0082] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0083] The reactor of the present application includes at least two catalytic units. By introducing acrolein solution into each catalytic unit respectively, the concentration distribution of the acrolein solution in the reactor is helped to be more uniform, thereby helping to maintain the side reactions at a low level, reducing the rate of catalyst agglomeration, and maintaining a high conversion frequency of the rear-stage catalyst, thereby helping to improve the selectivity of the acrolein hydration reaction, extend the service life of the catalyst, improve the stability of the device operation, and reduce production costs.

[0084] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing 3-hydroxypropanal, characterized in that: The preparation method comprises the following steps: Step S1, providing a reactor, wherein the reactor comprises M fixed bed reactors, each fixed bed reactor is provided with N interconnected catalytic units (1), 1≤M, 1≤N, M and N are not 1 at the same time, each fixed bed reactor is provided with a feed inlet and a discharge inlet, and each catalytic unit (1) has an inlet for an acrolein solution; Step S2, introducing the acrolein solution into the catalytic unit (1) from each of the acrolein solution inlets, and simultaneously introducing water into the feed port of the fixed bed reactor, so that the acrolein solution and the water undergo an addition reaction in the catalytic unit (1), and then discharging the product of the addition reaction through the discharge port of the fixed bed reactor, thereby obtaining the 3-hydroxypropanal.

2. The preparation method according to claim 1, characterized in that: The M fixed bed reactors are sequentially connected in series. In the step S2, the water is introduced from the feed port of the first fixed bed reactor located upstream, and the product of the addition reaction is discharged from the discharge port of the last fixed bed reactor located downstream.

3. The preparation method according to claim 1, characterized in that: The M fixed bed reactors are arranged in parallel. In the step S2, the water is introduced from the feed port of each fixed bed reactor located upstream, and the product of the addition reaction is discharged through the discharge port of each fixed bed reactor located downstream.

4. The preparation method according to any one of claims 1 to 3, characterized in that M≤6, N≤6; and / or, the catalytic unit (1) comprises a distributor (11), a catalyst layer (12) and an expansion space (13) arranged in sequence along the material flow direction; preferably, the fixed bed reactor is a vertical reactor, the feed inlet is arranged at the bottom of the fixed bed reactor, the discharge port is arranged at the top of the fixed bed reactor, and the catalytic unit (1) is provided with the distributor (11), the catalyst layer (12) and the expansion space (13) in sequence from bottom to top; and / or, the filling coefficient of the catalyst layer (12) is 0.5-0.9; and / or, the ratio of the volume of the expansion space (13) to the volume of the catalyst layer (12) is 10-40:100; and / or, the catalyst loaded in the catalyst layer (12) is selected from any one or more of polystyrylaminoacetic acid resin, polystyrylpropionic acid resin, polystyrylaminophosphoric acid resin, polystyrylsulfonic acid resin and polypropionic acid resin.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The length-to-diameter ratio of the fixed bed reactor is 2 to 35:1; and / or a filter (2) is arranged on the top of the fixed bed reactor.

6. The preparation method according to any one of claims 1 to 5, characterized in that The ratio of the total mass flow rate of the acrolein solution to the mass flow rate of the water is 10-25:100; and / or the temperature of the water is 30-80°C; and / or the mass space velocity of the water is 0.2-1h -1 .

7. The preparation method according to claim 2, characterized in that: Along the material flow direction, the mass flow rate of the acrolein solution entering each of the catalytic units (1) decreases successively; preferably, the ratio of the maximum mass flow rate of the acrolein solution flowing into each of the catalytic units (1) to the minimum mass flow rate of the acrolein solution flowing into each of the catalytic units (1) is 5.7 to 60:

1.

8. The preparation method according to any one of claims 1 to 7, characterized in that The temperature of the addition reaction is 30-80° C.; and / or the pressure of the addition reaction is 0.05-2 MPa.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The mass concentration of the acrolein solution is 75% to 99.9%.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The acrolein solution contains 500-5000 ppm of a polymerization inhibitor; and / or the polymerization inhibitor is selected from any one or more of hydroquinone, 2,6-di-tert-butyl-p-cresol and p-tert-butylcatechol.

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