Method for preparing beta-hydroxyaldehyde through hydration of alpha, beta-unsaturated aldehyde

Abstract

The invention provides a method for preparing beta-hydroxyaldehyde through hydration of alpha, beta-unsaturated aldehyde, and relates to the technical field of chemical synthesis. The method comprises the following steps: carrying out hydration reaction on an alpha, beta-unsaturated aldehyde aqueous solution under the action of a polymerization inhibitor and a modified HZSM-5 molecular sieve with a silica-alumina ratio of 30-60 to obtain beta-hydroxyaldehyde; the preparation process of the modified HZSM-5 molecular sieve comprises the following steps: S1, adjusting the pH value of a mixed material containing a silicon source and an aluminum source to 9.5-11, and then carrying out aging and hydrothermal crystallization to obtain a first catalyst precursor; s2, performing ammonium exchange on the first catalyst precursor to obtain a second catalyst precursor; s3, the second catalyst precursor and a silane modifier are subjected to a contact reaction, and the modified HZSM-5 molecular sieve is obtained. The method is high in raw material conversion rate and product selectivity, mild in reaction condition and wide in application range, and can be used for preparing beta-hydroxyaldehyde through a continuous olefine aldehyde hydration method.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and particularly relates to a method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. Background Art

[0002] β-hydroxy aldehyde is an important intermediate in organic chemical industry. For example, 3-hydroxy propionaldehyde (3-HPA) can be used to prepare 1,3-propanediol (1,3-PDO), and 1,3-PDO is an important monomer of the new polyester material poly(trimethylene terephthalate) (PTT). Therefore, β-hydroxy aldehyde compounds have great market potential.

[0003] At present, the main methods for preparing 3-hydroxy propionaldehyde are the enal hydration method, the ethylene oxide method and the biological method. Among them, the biological method has the disadvantages of small throughput and low production efficiency, and breakthroughs are still needed in strains and processes; the ethylene oxide carbonylation method has the disadvantages of high reaction pressure, great technical difficulty, complex catalytic system and harsh process, and it is still difficult to independently develop this process in the short term; while the enal hydration method has the advantages of mild process conditions and relatively simple catalytic system, and is more suitable for large-scale production.

[0004] In the process of preparing 3-hydroxypropionaldehyde by the hydroformylation of acrolein, the performance of the catalyst used is particularly important. For example, in Patent US2434110, proton acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid are used as catalysts. In Patents US5284979 and US5962745, buffer solutions composed of organic acids and bases formulated with carboxylic acids, phosphoric acid, and tertiary amine bases or aromatic heterocyclic compounds are used as catalysts. The conversion rate of acrolein is 40% - 60%, and the selectivity of 3-HPA is 70% - 85%. Such homogeneous catalysts are difficult to separate because they are dissolved in the aqueous phase, which greatly increases the difficulty of subsequent catalyst recovery. Patents CN108325560A, CN110386856A, CN112062663A, etc. use ionic liquid organic catalysts such as amino phosphoric acid, N-alkyl amino acids, and N-heterocyclic carboxylic acids, which can achieve a single-pass conversion rate of 80% for acrolein, and at the same time, the selectivity reaches 90% - 94%. However, the preparation of such ionic liquids is difficult, costly, and the process is complex, which is not suitable for large-scale applications. There are also technical solutions using chelating resin catalysts. For example, Patent US5015789 uses a chelating resin catalyst with amino phosphoric acid on the surface, Patent US5171898 uses a chelating resin catalyst with amino carboxylic acid functional groups on the surface, Patent CN1345713A uses a chelating resin catalyst with thiodiacetamide functional groups on the surface, and Patent CN1369471A uses a chelating resin catalyst containing carboxylic acid exchanged with rare earth metal ions; Patent CN100417443C uses a new type of chelating resin catalyst with amide group carboxylic acid groups on the surface. Such solid-phase catalysts are easy to separate from the reaction products, with a conversion rate greater than 70% and a selectivity of more than 80%, which is convenient for industrial applications. However, during the use of chelating resin catalysts, side reactions such as self-polymerization and polycondensation of acrolein and 3-HPA often occur, resulting in poor selectivity; secondly, polymer impurities accumulate on the surface of the catalyst, leading to a decrease in catalyst activity and a short service life.

[0005] In addition, not only does the performance of the catalyst affect the raw material conversion rate and product selectivity of the process, but how to reduce the occurrence of side reactions during the hydroformylation process of acrolein is also a problem that needs to be overcome. For example, the 3-hydroxypropionaldehyde product obtained by the hydration reaction is prone to dehydration to form by-products, or further undergoes condensation side reactions with the reaction raw materials, and the raw materials often undergo polymerization to form polymers, etc., further reducing the conversion rate and selectivity of the reaction. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the present invention discloses a method for preparing β-hydroxyaldehyde by the hydration of α,β-unsaturated aldehyde. This method can be used for the continuous preparation of β-hydroxyaldehyde, with a high raw material conversion rate, few side reactions, and high product selectivity for the overall process.

[0007] In order to achieve the above technical objectives, the present invention provides a method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. The aqueous solution of α,β-unsaturated aldehyde undergoes a hydration reaction to obtain β-hydroxy aldehyde under the action of an inhibitor and a modified HZSM-5 molecular sieve with a silica-alumina ratio of 30 to 60; wherein, the structure of the α,β-unsaturated aldehyde is: R in the said structure 1 and R 2 are each independently selected from H or an alkyl group having 1 to 5 carbon atoms;

[0008] The preparation process of the said modified HZSM-5 molecular sieve includes:

[0009] S1, adjusting the pH of the mixed material containing a silicon source and an aluminum source to 9.5 to 11, and then obtaining a first catalyst precursor through aging and hydrothermal crystallization;

[0010] S2, obtaining the second catalyst precursor by subjecting the first catalyst precursor to ammonium exchange;

[0011] S3, obtaining the said modified HZSM-5 molecular sieve by contacting the second catalyst precursor with a silane modifier for reaction.

[0012] The reaction process of preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde in the present invention is as follows:

[0013]

[0014] The above technical solution improves the technical effect of the method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde in the present invention through the synergistic optimization of multiple technical features. Specifically:

[0015] In the preparation of the modified HZSM-5 molecular sieve in the present invention, a suitable silica-alumina ratio is selected, so that the prepared catalyst can provide a suitable number of active sites for catalyzing the hydration reaction of α,β-unsaturated aldehyde. Further combined with providing a suitable hydrothermal crystallization pH value in S1, the structure and morphology of crystal growth can be regulated during hydrothermal crystallization, and a catalyst with a uniform distribution of active sites is obtained, which is beneficial to improving the raw material conversion rate and product selectivity, and also improves the structural stability and service life of the catalyst.

[0016] In addition, the catalyst is ion-exchanged from a sodium-type molecular sieve to a hydrogen-type molecular sieve through ammonium exchange, so that the catalyst can exhibit better catalytic performance in the acidic α,β-unsaturated aldehyde hydration reaction system of the present invention.

[0017] Common HZSM-5 molecular sieve catalysts have strong hydrophilicity. If they are applied to the catalytic enal hydration reaction system with a relatively large water content in the present invention, it will not be conducive to the uniform diffusion of oily unsaturated enals to the surface of the molecular sieve, resulting in low conversion and selectivity of the catalytic reaction. Based on a large amount of experimental data, the R & D team of the present invention found that by subjecting the HZSM-5 molecular sieve to silane modification, some surface regions of the original molecular sieve can be made lipophilic due to the modification, while other regions on its surface still retain hydrophilicity, thus obtaining an amphiphilic modified HZSM-5 molecular sieve catalyst, which can promote the dispersion of α,β-unsaturated aldehydes in the present invention on the catalyst surface and efficiently promote the progress of the hydration reaction.

[0018] It should be noted that no template agent needs to be added during the preparation process of the modified HZSM-5 molecular sieve of the present invention. This can not only reduce the process cost, reduce the operation steps and thus improve the production efficiency, but also reduce the discharge of organic substances and wastewater, improving the environmental friendliness of the method for preparing β-hydroxy aldehyde in the present invention.

[0019] By adding a polymerization inhibitor to the reaction system in the present invention, side reactions such as self-polymerization and polycondensation during the process are hindered, thereby further improving the reaction selectivity, prolonging the service life of the catalyst, and promoting the stable and continuous progress of the overall reaction.

[0020] The examples and comparative examples of the present invention illustrate the technical effects of the method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde in the present invention.

[0021] In a further example of the present invention, the silane modifier includes at least one of trimethylchlorosilane, triethylchlorosilane, tert-butyldimethylchlorosilane, and cyclohexyltrichlorosilane.

[0022] In a further example of the present invention, in step S3, the addition amount of the silane modifier can be selected as 20% - 60% of the mass of the second catalyst precursor. Exploring and optimizing the dosage of the silane modifier is beneficial to optimizing the acidic sites and pore distribution on the surface of the second catalyst precursor and improving the catalyst activity. In an optional example of the present invention, the addition amount of the silane modifier is 35% - 45% of the mass of the second catalyst precursor.

[0023] In a further example of the present invention, the temperature for the contact reaction between the second catalyst precursor and the silane modifier can be selected as 40 - 100°C. Under suitable temperature conditions, it is beneficial for the silane molecules of the modifier to fully react with the hydroxyl groups on the surface of the molecular sieve, thereby forming uniformly distributed silyl groups on the surface of the molecular sieve. In an optional example of the present invention, the temperature for the contact reaction between the second catalyst precursor and the silane modifier is preferably 60 - 80°C.

[0024] In a further example of the present invention, the contact reaction time between the second catalyst precursor and the silane modifier can be selected from 1 to 8 h, so that the second catalyst precursor and the silane modifier are fully contacted and modified; in an alternative example of the present invention, the contact reaction time between the second catalyst precursor and the silane modifier is preferably 2 to 5 h.

[0025] In a further example of the present invention, the contact reaction between the second catalyst precursor and the silane modifier can be carried out in a solvent, and the solvent includes at least one of toluene, cyclohexane, methylcyclohexane, benzene, xylene, tetrahydrofuran, and acetonitrile, preferably toluene.

[0026] A further example of the present invention also includes separating, washing, and drying the modified material to obtain a modified HZSM-5 molecular sieve. Further, the separation operation can be selected from filtration, centrifugation, suction filtration, or other methods that can achieve solid-liquid separation, and those skilled in the art can select according to needs, which does not limit the protection scope of the present invention. Further, the washing operation can be the solvent used in the modification reaction or other solvents, and those skilled in the art can select according to needs, which does not limit the protection scope of the present invention. Further, the drying operation can be carried out at a temperature range of 80 to 150 °C for 1 to 24 h, and those skilled in the art can select appropriate drying conditions according to needs, which does not limit the protection scope of the present invention.

[0027] In the above technical solution, the cations in the molecular sieve can be replaced by hydrogen ions through ammonium exchange to make it an H-type molecular sieve, thereby changing its acidity. Combining with the subsequent calcination operation, the pore structure and catalytic performance of the molecular sieve can be further optimized. In a further example of the present invention, the ammonium exchange includes contacting the first catalyst precursor with an ammonium salt aqueous solution, and the ammonium salt includes at least one of ammonium nitrate, ammonium sulfate, and ammonium chloride, preferably ammonium nitrate.

[0028] A further example of the present invention also includes a calcination operation on the first catalyst precursor after ammonium exchange; optionally, the temperature of the calcination operation is 500 to 600 °C. In an alternative example of the present invention, the calcination operation is carried out at 550 °C, and the calcination time is 4 to 8 h. In an alternative example of the present invention, the calcination operation time is 5 h; further optionally, it also includes solid-liquid separation of the material after ammonium exchange before the calcination operation; more preferably, it also includes a drying operation on the solid phase material obtained by solid-liquid separation. The temperature of the drying operation is 105 to 120 °C, preferably 110 °C, and the drying time is 3 to 8 h, preferably 5 h.

[0029] The concentration of the ammonium salt aqueous solution in the present invention is not limited and can be selected as 0.2 - 2 mol / l. The dosage of the ammonium salt aqueous solution in the present invention is not limited, and it is only necessary to make the first catalyst precursor contact with the ammonium salt solution for sufficient ammonium ion exchange. It can be understood that in the actual process, the first catalyst precursor can be optionally immersed entirely in the ammonium salt solution; in an optional example of the present invention, the ammonium salt solution can be recycled.

[0030] In a further example of the present invention, the temperature of the hydrothermal crystallization can be optionally 150 - 220 °C, preferably 170 - 190 °C; the pressure of the hydrothermal crystallization can be optionally 3 bar - 20 bar; the time of the hydrothermal crystallization can be optionally 20 - 36 h. Controlling the hydrothermal crystallization conditions is beneficial to regulating the crystal form, crystal size, and acid site distribution of the prepared catalyst, etc., and enhancing the thermal stability and chemical stability of the catalyst.

[0031] In a further example of the present invention, the pH value of the mixed material in step S1 is 10 - 11.

[0032] The specific operation of the aging operation in the present invention is not limited, and any method in the prior art that can allow the mixed material after adjusting the pH value to stand for a period of time under certain conditions to promote the further development and stabilization of its structure can be selected; in an optional example of the present invention, it can be optionally left standing at room temperature or at 20 - 50 °C for 10 - 20 h.

[0033] In a further example of the present invention, the particle size of the first catalyst precursor particles is 1.5 - 10 μm.

[0034] In a further example of the present invention, the silicon source includes sodium silicate, silica sol, and methyl orthosilicate. Preferably, the catalytic activity of the catalyst synthesized when sodium silicate is used as the silicon source is better.

[0035] In a further example of the present invention, the aluminum source includes aluminum sulfate, aluminum nitrate, aluminum chloride, and sodium metaaluminate. Preferably, the catalytic activity of the catalyst synthesized when aluminum sulfate is used as the aluminum source is better.

[0036] In a further example of the present invention, the contact angle of the modified HZSM-5 molecular sieve catalyst can be optionally 115 - 150°, further optionally 119° - 146°, and preferably 119.1° - 145.8°.

[0037] In a further example of the present invention, the α,β-unsaturated aldehyde includes at least one of acrolein, crotonaldehyde, 2-methylacrolein, 2-methyl-2-butenal, and 3-methyl-2-butenal, showing the wide applicability of the method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde in the present invention.

[0038] In a further example of the present invention, the mass concentration of the α,β-unsaturated aldehyde aqueous solution is 5% to 25%, so as to regulate the efficient progress of the reaction and help reduce the occurrence of side reactions such as self-polymerization and polycondensation of acrolein and products. In a preferred example of the present invention, the mass concentration of the α,β-unsaturated aldehyde aqueous solution is 10% to 20%.

[0039] In a further example of the present invention, the polymerization inhibitor includes one or several of hydroquinone, p-benzoquinone, polymerization inhibitor MQ (methyl hydroquinone), polymerization inhibitor PZ (phenothiazine), polymerization inhibitor ZJ701 (4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl), and polymerization inhibitor ZJ705 (tris(2,2,6,6-tetramethylpiperidin-4-yl) phosphite), preferably hydroquinone or polymerization inhibitor ZJ701. Examples of the present invention show the effects of using different polymerization inhibitors to catalyze the hydration of α,β-unsaturated aldehydes to prepare β-hydroxy aldehydes.

[0040] In a further example of the present invention, the addition amount of the polymerization inhibitor is 0.01% to 1.0% of the mass of the α,β-unsaturated aldehyde solution. By adding an appropriate amount of the polymerization inhibitor to the reaction materials, the effects of reducing the occurrence of side reactions, improving the product selectivity, and increasing the product yield can be achieved.

[0041] The present invention is not limited to the container for carrying out the hydration reaction of α,β-unsaturated aldehydes to prepare β-hydroxy aldehydes. Those skilled in the art can select a suitable reaction container, and the protection scope of the present invention is not limited thereby. In an alternative example of the present invention, the method for preparing β-hydroxy aldehydes by the hydration of α,β-unsaturated aldehydes of the present invention is carried out in a fixed-bed reactor. The modified HZSM-5 molecular sieve is loaded in the fixed-bed reactor, and a mixed feed stream containing the α,β-unsaturated aldehyde aqueous solution and the polymerization inhibitor is continuously input into the fixed-bed reactor for reaction; the feeding mode of the fixed bed can be selected as upflow-downflow or downflow-upflow, and further preferably downflow-upflow to increase the contact time between the materials and the catalyst, thereby effectively improving the reaction conversion rate; those skilled in the art can select according to needs, and the protection scope of the present invention is not limited thereby.

[0042] In a further example of the present invention, the temperature of the hydration reaction is 30 to 80 °C. A suitable reaction temperature is beneficial to improving the reaction efficiency and reducing the occurrence of side reactions; in an alternative example of the present invention, the temperature of the hydration reaction is preferably 50 to 70 °C.

[0043] In a further example of the present invention, the pressure of the hydration reaction is 0 to 1.5 MPa. The regulation of the reaction pressure is beneficial to regulating the reaction rate; in an alternative example of the present invention, the pressure of the hydration reaction is preferably 0 to 0.5 MPa.

[0044] In a further example of the present invention, the mass space velocity of the hydration reaction is 0.10 h -1~3.0 h -1 , by controlling the mass space velocity of the catalyst used in the reaction, it is beneficial to control the overall reaction process and promote the full reaction of raw materials, and it is beneficial to the continuous progress of the hydration reaction of α,β-unsaturated aldehyde; in an alternative example of the present invention, the mass space velocity of the hydration reaction is preferably 0.15 h -1 ~1.2 h -1 .

[0045] Compared with the prior art, the modified HZSM-5 molecular sieve used in the method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde in the present invention adopts a specific silicon-aluminum ratio in the preparation process and regulates the pH value of hydrothermal crystallization, and combines with silane modification to obtain an amphiphilic modified HZSM-5 molecular sieve with high catalytic activity and long service life. Combining with the use of inhibitors can reduce the occurrence of side reactions and improve the raw material conversion rate and product selectivity of the hydration reaction of α,β-unsaturated aldehyde; the reaction conditions of the present invention are mild and the applicable range is wide, and it can be used for the continuous preparation of β-hydroxyaldehyde by the olefin aldehyde hydration method. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0047] Figure 1 Shows the SEM comparison diagrams of the catalysts prepared by hydrothermal crystallization at different pH values;

[0048] Figure 2 Shows the gas chromatogram of the reaction material after Example 1;

[0049] Figure 3 Shows the long-term operation conversion rate and selectivity results of the method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde in Example 11. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0051] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0052] It should be noted that the reaction conversion rate and selectivity of the present invention are calculated by using the corrected gas chromatography peak area method. For example: conversion rate = (original unsaturated aldehyde - remaining unsaturated aldehyde) / original unsaturated aldehyde × 100%; selectivity = generated β-hydroxy aldehyde / converted unsaturated aldehyde × 100%.

[0053] Catalyst Preparation Example 1

[0054] A preparation method of an amphiphilic modified HZSM-5 molecular sieve, specifically, includes the following steps:

[0055] S1, Dissolve 60 g of sodium silicate in 350 g of deionized water, stir and heat to obtain a translucent solution; dissolve 3.4 g of aluminum sulfate in 20 g of deionized water, and slowly add the aluminum sulfate solution dropwise to the sodium silicate solution under vigorous stirring. After the addition is complete, add concentrated sulfuric acid to adjust the pH to about 10, continue stirring for 2 h, transfer to a beaker and age at room temperature; transfer the aged gel to a high-pressure reaction kettle, with an initial pressure of 5 bar, and crystallize at 180 °C for 25 h to obtain the first catalyst precursor;

[0056] S2, Filter the molecular sieve after hydrothermal crystallization, wash with deionized water, and dry the obtained solid at 110 °C for 6 h; displace the dried molecular sieve with 1 mol / L NH4NO3 solution three times at 90 °C; filter the displaced molecular sieve, dry at 110 °C for 5 h, and calcine at 550 °C for 5 h to obtain the second catalyst precursor.

[0057] S3, Add 10 g of the second catalyst precursor to 80 mL of toluene, and slowly add a 30 mL toluene solution containing 4 g of trimethylchlorosilane (TMCS) under stirring, raise the temperature to 60 °C and react for 2 h; after the reaction is completed, filter and wash three times with 30 mL of toluene, and dry the obtained molecular sieve at 110 °C for 5 h to obtain the trimethylchlorosilane-modified TMCS-HZSM-5 molecular sieve catalyst A-1, whose silicon-aluminum ratio is 49.

[0058] Catalyst Preparation Example 2

[0059] S1, Dissolve 30 g of silica sol in 350 g of deionized water, stir and heat to obtain a translucent solution; dissolve 2.67 g of aluminum chloride in 20 g of deionized water, and slowly add the aluminum chloride solution dropwise to the silica sol solution under vigorous stirring. After the addition is complete, add concentrated sulfuric acid to adjust the pH to about 10, continue stirring for 5 h, transfer to a beaker and age at room temperature; transfer the aged gel to a high-pressure reaction kettle, with an initial pressure of 8 bar, and crystallize at 170 °C for 36 h to obtain the first catalyst precursor;

[0060] S2. The molecular sieve after hydrothermal crystallization is filtered, washed with deionized water, and the obtained solid is dried at 120 °C for 5 h; the dried molecular sieve is replaced three times with 1 mol / L NH4Cl solution at 90 °C; after replacement, the molecular sieve is filtered, dried at 120 °C for 6 h, and calcined at 500 °C for 8 h to obtain the second catalyst precursor.

[0061] S3. 10 g of the second catalyst precursor is added to 80 mL of acetonitrile. Under stirring, a 30 mL acetonitrile solution containing 4 g of triethylchlorosilane (TESCL) is slowly added, and the temperature is raised to 70 °C for reaction for 5 h. After the reaction is completed, it is filtered and washed three times with 30 mL of acetonitrile. The obtained molecular sieve is dried at 110 °C for 5 h to obtain the triethylchlorosilane-modified TESCL-HZSM-5 molecular sieve catalyst B with a silica-alumina ratio of 50.

[0062] Catalyst Preparation Example 3

[0063] S1. 75 g of methyl orthosilicate is added to 350 g of deionized water; 3.6 g of aluminum nitrate is dissolved in 20 g of deionized water. Under vigorous stirring, the aluminum nitrate solution is slowly added dropwise to the methyl orthosilicate solution. After the addition is completed, concentrated sulfuric acid is added to adjust the pH to about 10, and stirring is continued for 3 h, then transferred to a beaker for aging at room temperature; the aged gel is transferred to a high-pressure reaction kettle with an initial pressure of 1.2 bar and crystallized at 190 °C for 22 h to obtain the first catalyst precursor;

[0064] S2. The molecular sieve after hydrothermal crystallization is filtered, washed with deionized water, and the obtained solid is dried at 105 °C for 8 h; the dried molecular sieve is replaced three times with 1 mol / L NH4NO3 solution at 90 °C; after replacement, the molecular sieve is filtered, dried at 110 °C for 6 h, and calcined at 600 °C for 4 h to obtain the second catalyst precursor.

[0065] S3. 10 g of the second catalyst precursor is added to 80 mL of xylene. Under stirring, a 30 mL xylene solution containing 4 g of tert-butyldimethylchlorosilane (TBSCL) is slowly added, and the temperature is raised to 80 °C for reaction for 3 h. After the reaction is completed, it is filtered and washed three times with 30 mL of xylene. The obtained molecular sieve is dried at 110 °C for 5 h to obtain the tert-butyldimethylchlorosilane-modified TBSCL-HZSM-5 molecular sieve catalyst C with a silica-alumina ratio of 58.

[0066] Catalyst Preparation Example 4

[0067] S1. Dissolve 50 g of sodium silicate in 350 g of deionized water, stir and heat to obtain a translucent solution; dissolve 1.64 g of sodium aluminate in 20 g of deionized water, and slowly add the sodium aluminate solution dropwise to the sodium silicate solution under vigorous stirring. After the addition is complete, adjust the pH to about 10 with concentrated sulfuric acid, continue stirring for 2 h, transfer to a beaker and age at room temperature; transfer the aged gel to a high-pressure reactor, with an initial pressure of 1.0 bar, and crystallize at 180 °C for 30 h to obtain the first catalyst precursor;

[0068] S2. Filter the molecular sieve after hydrothermal crystallization and wash it with deionized water. The obtained solid is dried at 120 °C for 5 h; the dried molecular sieve is replaced three times with 1 mol / L (NH4)2SO4 solution at 90 °C; after replacement, the molecular sieve is filtered, dried at 120 °C for 5 h, and calcined at 550 °C for 5 h to obtain the second catalyst precursor.

[0069] S3. Add 10 g of the second catalyst precursor to 80 mL of methylcyclohexane. Under stirring, slowly add a 30 mL methylcyclohexane solution containing 4 g of cyclohexyltrichlorosilane (CHTCS), and raise the temperature to 60 °C and react for 5 h. After the reaction is completed, filter and wash three times with 30 mL of methylcyclohexane. The obtained molecular sieve is dried at 120 °C for 5 h to obtain the cyclohexyltrichlorosilane-modified CHTCS-HZSM-5 molecular sieve catalyst D, with a silica-alumina ratio of 41.

[0070] The R & D team of the present invention conducted a hydrophobicity test on the catalyst. By measuring the contact angle between water and the catalyst surface, the hydrophilic and hydrophobic effects of the unmodified and modified HZSM-5 molecular sieve catalysts were compared. The results are shown in Table 1.

[0071] Table 1

[0072]

[0073] The reaction system of the method for preparing β-hydroxyaldehyde by the hydration of α,β-unsaturated aldehyde of the present invention is a reaction system containing a large amount of water. Therefore, how to promote the uniform diffusion of the oily unsaturated aldehyde (reaction raw material) to the catalyst surface is an important control factor for improving the raw material conversion rate. The contact angle of the unmodified HZSM-5 is 27.3°, showing extremely strong hydrophilicity (extremely strong lipophobicity). Using it in the reaction volume of the present invention will be unfavorable for the dispersion of the reaction raw material on the catalyst surface; while for the modified catalysts A - D, the contact angle is 119.1° - 145.8°, showing better lipophilicity and certain hydrophilicity. Using them in the reaction system of the present invention will be conducive to the dispersion of the oily unsaturated aldehyde on the molecular sieve surface. With the combined action of certain hydrophilicity and the large amount of water in the reaction system, it can effectively promote the contact reaction of water, organic matter and the molecular sieve catalyst, and improve the raw material conversion rate.

[0074] Combined with the experimental results in Table 1, optionally, the contact angle of the modified HZSM-5 molecular sieve catalyst is 115-150°; further optionally 119°-146°, preferably 119.1°-145.8°.

[0075] Catalyst Preparation Example 5

[0076] The process and parameter control of this catalyst preparation example are the same as those of Catalyst Preparation 1, except for S3: Add 10 g of the second catalyst precursor to 80 mL of toluene. Under stirring, slowly add a 30 mL toluene solution containing 2 g of trimethylchlorosilane (TMCS). Heat to 60 °C and react for 2 h. After the reaction is completed, filter and wash three times with 30 mL of toluene. The obtained molecular sieve is dried at 110 °C for 5 h to obtain a trimethylchlorosilane-modified molecular sieve catalyst A-2 with a silica-alumina ratio of 49.

[0077] Catalyst Preparation Example 6

[0078] The process and parameter control of this catalyst preparation example are the same as those of Catalyst Preparation 1, except for S3: Add 10 g of the second catalyst precursor to 80 mL of toluene. Under stirring, slowly add a 30 mL toluene solution containing 6 g of trimethylchlorosilane (TMCS). Heat to 60 °C and react for 2 h. After the reaction is completed, filter and wash three times with 30 mL of toluene. The obtained molecular sieve is dried at 110 °C for 5 h to obtain a trimethylchlorosilane-modified molecular sieve catalyst A-3 with a silica-alumina ratio of 49.

[0079] Catalyst Preparation Example 7

[0080] The process and parameter control of this catalyst preparation example are the same as those of Catalyst Preparation 1, except that in step S1, after slowly dropping the aluminum sulfate solution into the sodium silicate solution, adjust the pH to about 11 with concentrated sulfuric acid; then obtain the molecular sieve catalyst A-4 through steps S1-S3 with a silica-alumina ratio of 49.

[0081] Comparative Catalyst Preparation Example 1

[0082] A preparation method of a modified HZSM-5 molecular sieve. The preparation process and parameter control of this preparation method are the same as those of Catalyst Preparation Example 1, except that in step S1, dissolve 30 g of sodium silicate in 350 g of deionized water, stir and heat to obtain a semi-transparent solution; dissolve 3.4 g of aluminum sulfate in 20 g of deionized water, and slowly drop the aluminum sulfate solution into the sodium silicate solution under vigorous stirring; then obtain the molecular sieve catalyst A-5 through steps S1-S3 with a silica-alumina ratio of 25.

[0083] Comparative Catalyst Preparation Example 2

[0084] A preparation method of a modified HZSM-5 molecular sieve. This preparation method is the same as the preparation process and parameter control of Catalyst Preparation Example 1, except that: 90 g of sodium silicate is dissolved in 350 g of deionized water, and the solution is stirred and heated to obtain a translucent solution. 3.4 g of aluminum sulfate is dissolved in 20 g of deionized water, and the aluminum sulfate solution is slowly added dropwise to the sodium silicate solution under vigorous stirring; then, through steps S1 to S3, molecular sieve catalyst A-6 is obtained, and its silica-alumina ratio is 74.

[0085] Comparative Catalyst Preparation Example 3

[0086] A preparation method of a modified HZSM-5 molecular sieve. This preparation method is the same as the preparation process and parameter control of Catalyst Preparation Example 1, except that: after the aluminum sulfate solution is slowly added dropwise to the sodium silicate solution, concentrated sulfuric acid is used to adjust the pH to about 12; then, through steps S1 to S3, molecular sieve catalyst A-7 is obtained, and its silica-alumina ratio is 49.

[0087] Comparative Catalyst Preparation Example 4

[0088] A preparation method of an HZSM-5 molecular sieve. This preparation method is the same as the preparation process and parameter control of Catalyst Preparation Example 1, except that: after the aluminum sulfate solution is slowly added dropwise to the sodium silicate solution, concentrated sulfuric acid is used to adjust the pH to about 9; then, through step S1, a molecular sieve with regular morphology cannot be obtained.

[0089] Figure 1 The SEM images of the first catalyst precursor prepared by hydrothermal crystallization at different pH values are shown. In the figure, a detects the SEM image of the first catalyst precursor of Comparative Catalyst Preparation Example 4 (the pH of hydrothermal crystallization is 9), b shows the SEM image of the first catalyst precursor of Catalyst Preparation Example 1 (the pH of hydrothermal crystallization is 10), c shows the SEM image of the first catalyst precursor in Catalyst Preparation Example 7 (the pH of hydrothermal crystallization is 11), and d shows the SEM image of the first catalyst precursor of Comparative Catalyst Preparation Example 3 (the pH of hydrothermal crystallization is 12).

[0090] It can be confirmed that Figure 1 when hydrothermal crystallization is carried out at a pH value of 9, the first catalyst precursor obtained is basically amorphous; when the pH value of hydrothermal crystallization is 10, the first catalyst precursor obtained has good crystallinity, a relatively regular crystal form, and a particle size of about 5 μm; when hydrothermal crystallization is carried out at a pH of 11, the first catalyst precursor obtained has good crystallinity, and the particle size slightly increases to 10 μm; when the pH of hydrothermal crystallization is 12, the grain size of the first catalyst precursor obtained becomes larger, the particle size is about 30 μm, and its surface has obvious defects.

[0091] Examples

[0092] Example 1

[0093] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde, which is carried out in a fixed-bed reactor. Specifically, hydroquinone accounting for about 0.1% of the mass of the acrolein aqueous solution is added to the acrolein aqueous solution with a mass concentration of 10% to obtain a mixed feed stream. This mixed feed stream is pumped into a fixed-bed reactor filled with 8 g of molecular sieve catalyst A-1 for hydration reaction, and the feeding mode of the mixed feed stream is from bottom to top. The temperature of the hydration reaction is 50 °C, and the reaction space velocity is 1.2 h -1 , and the reaction pressure is 0.2 MPa. The reaction product is analyzed by gas chromatography (such as Figure 2 ), and the conversion rate of acrolein is 89.5%, and the selectivity of 3-hydroxypropanal is 96.2%.

[0094] Example 2

[0095] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde, which is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the catalyst used in this example is molecular sieve catalyst B. The conversion rate of acrolein in this example is 86.0%, and the selectivity of 3-hydroxypropanal is 94.5%.

[0096] Example 3

[0097] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde, which is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that in this example, hydroquinone accounting for 0.3% of the mass of the acrolein aqueous solution is added to the acrolein aqueous solution with a mass concentration of 15%, and the catalyst used is molecular sieve catalyst C. The conversion rate of acrolein in this example is 84.4%, and the selectivity of 3-hydroxypropanal is 93.6%.

[0098] Example 4

[0099] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde, which is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the catalyst used in this example is molecular sieve catalyst D. The conversion rate of acrolein in this example is 87.7%, and the selectivity of 3-hydroxypropanal is 95.2%.

[0100] Example 5

[0101] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde, which is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the catalyst used in this example is molecular sieve catalyst A-2. The conversion rate of acrolein in this example is 83.5%, and the selectivity of 3-hydroxypropanal is 95.8%.

[0102] Example 6

[0103] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. This method is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the catalyst used in this example is molecular sieve catalyst A-3. The conversion rate of acrolein in this example is 91.3%, and the selectivity of 3-hydroxy propionaldehyde is 96.8%.

[0104] Example 7

[0105] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. This method is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the temperature of the hydration reaction in this example is 65 °C. The conversion rate of acrolein in this example is 93.0%, and the selectivity of 3-hydroxy propionaldehyde is 94.7%.

[0106] Example 8

[0107] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. This method is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the mass concentration of the acrolein aqueous solution used in this example is 20%, and in addition, the dosage of the added polymerization inhibitor is 0.2% of the mass of the acrolein aqueous solution. The conversion rate of acrolein in this example is 82.2%, and the selectivity of 3-hydroxy propionaldehyde is 95.3%.

[0108] Example 9

[0109] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. This method is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the polymerization inhibitor used in this example is ZJ701. The conversion rate of acrolein in this example is 88.1%, and the selectivity of 3-hydroxy propionaldehyde is 96.4%.

[0110] Example 10

[0111] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. This method is carried out in a fixed-bed reactor. The specific process and parameter control are the same as those in Example 1, except that the catalyst used in this example is molecular sieve catalyst A-4. The conversion rate of acrolein in this example is 89.0%, and the selectivity of 3-hydroxy propionaldehyde is 95.1%.

[0112] Example 11

[0113] This example is based on Example 1 and evaluates the performance of the long-term operation of the reaction process. Specifically, on the basis of the method in Example 1, a long-term reaction evaluation was carried out for 1232 h, and the reaction results were analyzed by gas chromatography. The average conversion rate of acrolein was 89.4%, and the average selectivity of 3-hydroxypropionaldehyde was 96.3%; the specific operation results are as Figure 3 shown; it is confirmed that the catalyst used in the method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde of the present invention has high stability and long service life, the occurrence of side reactions is reduced in the overall process, and it has excellent economy and is suitable for large-scale industrial production.

[0114] Comparative Example

[0115] Comparative Example 1

[0116] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those in Example 1, except that the catalyst used in this comparative example is the second catalyst precursor in Catalyst Preparation Example 1. The conversion rate of acrolein in this comparative example was 66.7%, and the selectivity of 3-hydroxypropionaldehyde was 78.1%.

[0117] Comparative Example 2

[0118] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those in Example 1, except that 0.1% inhibitor was not added in this comparative example. The conversion rate of acrolein in this comparative example was 89.8%, and the selectivity of 3-hydroxypropionaldehyde was 88.7%.

[0119] Comparative Example 3

[0120] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those in Example 1, except that the catalyst used in this comparative example is a phosphoric acid solution (phosphoric acid concentration is 80%) of 6.7% of the mass of the acrolein aqueous solution, and the reaction form is a kettle reaction. The conversion rate of acrolein in this comparative example was 66.7%, and the selectivity of 3-hydroxypropionaldehyde was 78.1%.

[0121] Comparative Example 4

[0122] A method for preparing β-hydroxyaldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those in Example 1, except that the catalyst used in this comparative example is molecular sieve catalyst A-5. The conversion rate of acrolein in this example was 81.2%, and the selectivity of 3-hydroxypropionaldehyde was 80.4%.

[0123] Comparative Example 5

[0124] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those of Example 1, except that the catalyst used in this comparative example is molecular sieve catalyst A-6. The conversion rate of acrolein in this example is 51.9%, and the selectivity of 3-hydroxy propionaldehyde is 83.6%.

[0125] Comparative Example 6

[0126] A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde. The process and parameter control of this comparative example are the same as those of Example 1, except that the catalyst used in this comparative example is molecular sieve catalyst A-7. The conversion rate of acrolein in this example is 77.0%, and the selectivity of 3-hydroxy propionaldehyde is 79.2%.

[0127] Example 12

[0128] A method for preparing 3-hydroxy butyraldehyde (3-HBA) by hydrating crotonaldehyde. This method is carried out in a fixed-bed reactor. Specifically, 0.2% inhibitor ZJ701 is added to an aqueous solution of crotonaldehyde with a mass concentration of 15% to obtain a mixed feed stream; this mixed feed stream enters a fixed-bed reactor containing 8 g of molecular sieve catalyst A-1 through a pump for hydration reaction, and the feeding mode of the mixed feed stream is from top to bottom; the reaction temperature is 60 °C, and the reaction space velocity is 0.9 h -1 , and the reaction pressure is 0 MPa; the reaction results are analyzed by gas chromatography. The conversion rate of crotonaldehyde is 83.4%, and the selectivity of 3-hydroxy butyraldehyde is 90.3%.

[0129] Example 13

[0130] A method for preparing 3-hydroxy butyraldehyde by hydrating crotonaldehyde. The specific process and parameter control of this example are the same as those of Example 12, except that the catalyst used in this example is molecular sieve catalyst B; the reaction results are analyzed by gas chromatography. The conversion rate of crotonaldehyde is 81.5%, and the selectivity of 3-hydroxy butyraldehyde is 92.7%.

[0131] Example 14

[0132] A method for preparing 3-hydroxy butyraldehyde by hydrating crotonaldehyde. The specific process and parameter control of this example are the same as those of Example 12, except that the catalyst used in this example is molecular sieve catalyst C; the reaction results are analyzed by gas chromatography. The conversion rate of crotonaldehyde is 80.8%, and the selectivity of 3-hydroxy butyraldehyde is 91.1%.

[0133] Example 15

[0134] A method for preparing 3-hydroxybutyraldehyde by the hydration of crotonaldehyde. The specific process and parameter control of this example are the same as those of Example 12, except that the catalyst used in this example is molecular sieve catalyst D, and the inhibitor used is hydroquinone; the reaction results are analyzed by gas chromatography, the conversion rate of crotonaldehyde is 84.9%, and the selectivity of 3-hydroxybutyraldehyde is 89.5%.

[0135] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation manners, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple improvements can still be made, and all should be regarded as belonging to the scope of protection of the present invention.

Claims

1. A method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde, characterized in that, The aqueous solution of α,β-unsaturated aldehyde undergoes a hydration reaction under the action of an inhibitor and a modified HZSM-5 molecular sieve with a silica-alumina ratio of 30 to 60 to obtain β-hydroxy aldehyde; Among them, the structure of the α,β-unsaturated aldehyde is: R in the said structure 1 and R 2 are each independently selected from H or an alkyl group having 1 to 5 carbon atoms; The preparation process of the modified HZSM-5 molecular sieve includes: S1, adjusting the pH of the mixed material containing a silicon source and an aluminum source to 9.5 to 11, and then obtaining a first catalyst precursor through aging and hydrothermal crystallization; S2, performing ammonium exchange on the first catalyst precursor to obtain the second catalyst precursor; S3, obtaining the modified HZSM-5 molecular sieve after contacting and reacting the second catalyst precursor with a silane modifier.

2. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The silane modifier includes at least one of trimethylchlorosilane, triethylchlorosilane, tert-butyldimethylchlorosilane, and cyclohexyltrichlorosilane; Preferably, in step S3, the addition amount of the silane modifier is 20% to 60% of the mass of the second catalyst precursor, preferably 35% to 45%.

3. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The temperature for the contact reaction between the second catalyst precursor and the silane modifier is 40 to 100 °C, preferably 60 to 80 °C; And / or, the time for the contact reaction between the second catalyst precursor and the silane modifier is 1 to 8 h, preferably 2 to 5 h.

4. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The contact reaction between the second catalyst precursor and the silane modifier is carried out in a solvent, and the solvent includes at least one of toluene, cyclohexane, methylcyclohexane, benzene, xylene, tetrahydrofuran, and acetonitrile, preferably toluene.

5. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, wherein The ammonium exchange includes contacting the first catalyst precursor with an aqueous ammonium salt solution, and the ammonium salt includes at least one of ammonium nitrate, ammonium sulfate, and ammonium chloride, preferably ammonium nitrate.

6. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The temperature of the hydrothermal crystallization is 150 to 220 °C, preferably 170 to 190 °C; the pressure of the hydrothermal crystallization is 3 bar to 20 bar; the time of the hydrothermal crystallization is 20 to 36 h.

7. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The α,β-unsaturated aldehyde includes at least one of acrolein, crotonaldehyde, 2-methylacrolein, 2-methyl-2-butenal, and 3-methyl-2-butenal.

8. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The mass concentration of the aqueous solution of α,β-unsaturated aldehyde is 5% to 25%, preferably 10% to 20%.

9. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, wherein The inhibitor includes one or several of hydroquinone, p-benzoquinone, inhibitor MQ, inhibitor PZ, inhibitor ZJ701, and inhibitor ZJ705, preferably hydroquinone or inhibitor ZJ701; Preferably, the addition amount of the inhibitor is 0.01% - 1.0% of the mass of the α,β-unsaturated aldehyde solution.

10. The method for preparing β-hydroxy aldehyde by hydrating α,β-unsaturated aldehyde according to claim 1, characterized in that, The temperature of the hydration reaction is 30 to 80 °C, preferably 50 to 70 °C; And / or, the pressure of the hydration reaction is 0 to 1.5 MPa, preferably 0 to 0.5 MPa; And / or, the mass hourly space velocity of the hydration reaction is 0.10 h -1 ~3.0 h -1 , preferably 0.15 h -1 ~1.2 h -1 .

Images