Molecular sieve catalyst for acrolein hydration reaction as well as preparation and application of molecular sieve catalyst

Abstract

The invention discloses a method for preparing 3-hydroxypropionaldehyde by catalyzing acrolein hydration through a molecular sieve. The hierarchical pore structure SAPO-11 molecular sieve is prepared by adopting double template agents, and the method comprises the following steps: firstly, fully mixing phosphoric acid, an aluminum source and a template agent 1, and carrying out pre-crystallization to obtain precursor gel; and fully mixing the precursor gel, a silicon source and a template agent 2, crystallizing, washing, drying and roasting to obtain the SAPO-11 molecular sieve catalyst. The prepared catalyst shows high conversion rate and 3-hydroxypropionaldehyde selectivity in the acrolein hydration reaction, reaction conditions are mild, byproducts are few, stability is high, and the catalyst has good industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, and in particular to a method for preparing a stable and efficient molecular sieve catalyst for the hydration of acrolein to 3-hydroxypropionaldehyde and its application. Background Technology

[0002] 1,3-Propanediol (1,3-PDO) is an important chemical raw material, used as a solvent, antifreeze, protective agent, and pharmaceutical intermediate. Particularly in the polyester industry, polypropylene terephthalate (PTT), synthesized from 1,3-propanediol monomers, possesses more unique properties than polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), thus attracting widespread attention and research. Currently, the main methods for producing 1,3-propanediol include chemical methods such as acrolein hydration hydrogenation and ethylene oxide hydroformylation, as well as bio-fermentation methods. Among these, the acrolein hydration hydrogenation method was the first to achieve industrial-scale production due to its mature process, low technical difficulty, and low production cost.

[0003] The preparation of 1,3-propanediol via the acrolein hydration hydrogenation method involves two steps: first, acrolein undergoes a hydration reaction in the presence of an acidic catalyst to generate 3-hydroxypropanal; then, 3-hydroxypropanal undergoes a hydrogenation reaction in the presence of a metal catalyst to generate 1,3-propanediol. The hydrogenation reaction typically employs a two-stage hydrogenation method, achieving near 100% conversion of 3-hydroxypropanal and selectivity for 1,3-propanediol. Due to the reactivity of the aldehyde group and the presence of an enaldehyde-alkenyl conjugated structure in the acrolein molecule, both acrolein and 3-hydroxypropanal are prone to side reactions such as self-polymerization and condensation, leading to low selectivity for 3-hydroxypropanal and affecting catalyst lifetime. Therefore, the acrolein hydration process is crucial in the acrolein hydration hydrogenation process for 1,3-propanediol.

[0004] Commonly used catalysts for the acrolein hydration reaction include homogeneous catalysts such as inorganic and organic acid-base buffer solutions, as well as heterogeneous catalysts such as ion exchange resins and zeolite molecular sieves. Among them, heterogeneous catalysts have good prospects for industrial application due to their low separation energy consumption and cost. In particular, zeolite molecular sieve catalysts have attracted increasing attention due to their high selectivity in the acrolein hydration reaction. Patent CN 115626869 A uses an acid-modified molecular sieve as a catalyst and employs a mixed solvent of organic solvent and water to increase the concentration of the reactant acrolein, thereby effectively improving the conversion rate of acrolein (≥50%) and the selectivity of 3-hydroxypropionaldehyde (≥87%). Patent CN 117884172A describes the preparation of a V-Mo-X-SAPO-34 catalyst by introducing metal ions such as vanadium, molybdenum, and zirconium into SAPO-34 molecular sieve. The acrolein hydration reaction is carried out using a four-stage series reactor. The addition of metal ions improves the conversion rate of acrolein and the selectivity and yield of 3-hydroxypropionaldehyde. The reaction conditions are mild, the process is simple, and there are few by-products, making it suitable for large-scale continuous industrial production. Summary of the Invention

[0005] In view of this, the present invention aims to propose a new method for preparing molecular sieve catalysts and a reaction system for preparing 3-hydroxypropanal by hydration of acrolein, so as to overcome the problems of low conversion rate of acrolein and yield of 3-hydroxypropanal, high separation cost and serious loss in the hydration reaction, and provide technical support for the industrial production of 1,3-propanediol.

[0006] To achieve the above objectives, the present invention provides a method for preparing a molecular sieve catalyst for the acrolein hydration reaction, comprising the following steps:

[0007] S1. Mix phosphoric acid, aluminum source, template agent 1 and water, stir thoroughly, and transfer to a crystallization kettle for pre-crystallization to obtain precursor gel;

[0008] S2. Mix the precursor gel, silicon source, template agent 2 and water, stir thoroughly, and transfer to a crystallization kettle for crystallization.

[0009] S3. After crystallization, the sample is washed, dried, and calcined to obtain SAPO-11 molecular sieve catalyst.

[0010] Furthermore, in step S1, the aluminum source includes one or more of boehmite, aluminum isopropoxide, sodium aluminate, and aluminum nitrate.

[0011] In step S1, template agent 1 includes one or more of di-n-propylamine (DPA), triethylamine, tetrapropylammonium hydroxide (TPAOH), and tetrapropylammonium bromide.

[0012] In step S1, the molar ratio of aluminum source (calculated as Al2O3) to water is 1:(10-100);

[0013] Preferably, in step S1, the molar ratio of aluminum source (calculated as Al2O3) to water is 1:(20-60).

[0014] In step S1, stirring is carried out under water bath conditions, with a stirring temperature of 30-50℃ and a stirring time of 1-24h;

[0015] Preferably, the stirring temperature is 30-40℃ and the stirring time is 10-24h.

[0016] In step S1, pre-crystallization is carried out in a stainless steel hydrothermal crystallization kettle, and the pre-crystallization conditions are: constant temperature crystallization at 90-150℃ for 5-12 hours.

[0017] Preferably, the pre-crystallization conditions are: constant temperature crystallization at 120-150℃ for 5-10 hours.

[0018] Furthermore, in step S2, the silicon source includes one or more of tetraethyl orthosilicate, acidic silica sol, fumed silica, and sodium metasilicate.

[0019] In step S2, template agent 2 includes one or more of cetyltrimethylammonium bromide (CTAB), P123, and F127.

[0020] In step S2, the molar ratio of silicon source (calculated as SiO2) to water is 1:(50-200);

[0021] Preferably, in step S2, the molar ratio of silicon source (calculated as SiO2) to water is 1:(100-150).

[0022] In step S2, the molar ratio of aluminum source (calculated as Al2O3), phosphoric acid (calculated as P2O5), silicon source (calculated as SiO2), template agent 1 and template agent 2 is 1:(0.1-2):(0.1-3):(0.05-2):(0.001-2);

[0023] Preferably, the molar ratio is 1:(0.5-1):(0.3-2):(0.1-2):(0.001-1).

[0024] In step S2, stirring is carried out under water bath conditions, with a stirring temperature of 30-50℃ and a stirring time of 0.5-12h.

[0025] Preferably, the stirring temperature is 30-40℃ and the stirring time is 1-12h.

[0026] In step S2, crystallization is carried out in a stainless steel hydrothermal crystallization kettle under the following conditions: constant temperature crystallization at 170-200℃ for 24-84 hours.

[0027] Preferably, the crystallization conditions are: constant temperature crystallization at 180-200℃ for 24-72 hours.

[0028] Further, in step S3, the drying is carried out in a forced-air drying oven under the following conditions: constant temperature drying at 100-150℃ for 8-24 hours, and the calcination is carried out in a muffle furnace under the following conditions: constant temperature calcination at 500-700℃ for 4-8 hours.

[0029] Preferably, the drying conditions are: constant temperature drying at 100-120℃ for 10-12 hours, and the calcination conditions are: constant temperature calcination at 550-650℃ for 6-8 hours.

[0030] In a reaction system for the preparation of 3-hydroxypropionalal by the hydration of acrolein using molecular sieve catalysis, SAPO-11 catalyst is applied to the acrolein hydration reaction, and the hydration reaction is carried out in a continuous fixed-bed reactor.

[0031] Furthermore, the reaction raw material is an aqueous solution of acrolein with a mass concentration of 10-20%, and the content of polymerization inhibitor in the reaction raw material is 100-1000 ppm. The polymerization inhibitor includes one or more of hydroquinone, tert-butylcatechol, p-hydroxyanisole, and 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical.

[0032] Preferably, the reaction raw material is an aqueous solution of acrolein with a mass concentration of 10-15%, and the content of polymerization inhibitor in the reaction raw material is 500-1000 ppm.

[0033] Furthermore, the hydration reaction temperature is 30-80℃, the atmosphere is inert, the reaction pressure is 0-2MPa, and the mass hourly space velocity (WHSV) of the reactants is 0.1-10h. -1 ;

[0034] Preferably, the hydration reaction temperature is 40-60℃, the reaction pressure is 0-1MPa, and the mass hourly space velocity of the reactants is 0.5-1h. -1 .

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. This invention uses a dual template agent to prepare a hierarchical porous SAPO-11 molecular sieve. The prepared SAPO-11 molecular sieve has high porosity and large specific surface area, which can provide more active centers. The surface acidity of the molecular sieve is mainly weak acid and medium-strong acid, which is suitable for acrolein hydration reaction.

[0037] 2. The hierarchical porous SAPO-11 molecular sieve prepared by this invention effectively improves the conversion rate of acrolein and the selectivity of 3-hydroxypropionaldehyde in the acrolein hydration reaction.

[0038] 3. The hierarchical porous SAPO-11 molecular sieve prepared by this invention exhibits high catalytic stability in the acrolein hydration reaction and has good prospects for industrial application.

[0039] The catalyst prepared in this invention exhibits high conversion rate and 3-hydroxypropanal selectivity in the acrolein hydration reaction, with mild reaction conditions, few byproducts, and high stability, showing good prospects for industrial application. Detailed Implementation

[0040] The present invention will be further described below with reference to experimental subjects, but the scope of protection of the present invention is not limited thereto.

[0041] Example 1

[0042] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0043] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0044] 1.09 g of hexadecyltrimethylammonium bromide and 0.58 g of P123 were added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring was continued for 1 h. Finally, the precursor gel was added, and stirring was continued for 4 h to obtain a mixture with a molar composition of 1.0 Al2O3:0.74 P2O5:0.3 SiO2:0.93 DPA:0.03 CTAB:0.001 P123:41.0 H2O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0045] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0046] Example 2

[0047] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0048] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0049] 1.09 g of hexadecyltrimethylammonium bromide and 0.11 g of F127 were added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring was continued for 1 h. Finally, the precursor gel was added, and stirring was continued for 4 h to obtain a mixture with a molar composition of 1.0 Al2O3:0.74 P2O5:0.3 SiO2:0.93 DPA:0.03 CTAB:0.001 F127:41.0 H2O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0050] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0051] Example 3

[0052] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0053] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0054] 1.09 g of hexadecyltrimethylammonium bromide was added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring was continued for 1 h. Finally, the precursor gel was added, and stirring was continued for 4 h to obtain a mixture with a molar composition of 1.0 Al₂O₃:0.74 P₂O₅:0.3 SiO₂:0.93 DPA:0.03 CTAB:41.0 H₂O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0055] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0056] Example 4

[0057] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0058] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0059] 0.58 g of P123 was added to 30.00 g of deionized water and stirred in a 40°C water bath for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring continued for 1 h. Finally, the precursor gel was added, and stirring continued for 4 h to obtain a mixture with a molar composition of 1.0 Al2O3:0.74 P2O5:0.3 SiO2:0.93 DPA:0.001 P123:41.0 H2O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185°C for 24 h to obtain a solid product.

[0060] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0061] Example 5

[0062] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0063] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0064] 0.11 g of F127 was added to 30.00 g of deionized water and stirred in a 40°C water bath for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring continued for 1 h. Finally, the precursor gel was added, and stirring continued for 4 h to obtain a mixture with a molar composition of 1.0 Al2O3:0.74 P2O5:0.3 SiO2:0.93 DPA:0.001 F127:41.0 H2O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185°C for 24 h to obtain a solid product.

[0065] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0066] Example 6

[0067] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0068] 17.06 g of phosphoric acid and 75.65 g of tetrapropylammonium hydroxide (25% aqueous solution) were mixed and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0069] 1.09 g of hexadecyltrimethylammonium bromide was added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring continued for 1 h. Finally, the precursor gel was added, and stirring continued for 4 h to obtain a mixture with a molar composition of 1.0 Al₂O₃:0.74 P₂O₅:0.3 SiO₂:0.93 TPAOH:0.03 CTAB:41.0 H₂O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0070] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0071] Example 7

[0072] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0073] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 20.42 g of aluminum isopropoxide was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0074] 1.09 g of hexadecyltrimethylammonium bromide was added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.25 g of tetraethyl orthosilicate was added at a rate of 2 s / drop, and stirring was continued for 1 h. Finally, the precursor gel was added, and stirring was continued for 4 h to obtain a mixture with a molar composition of 1.0 Al₂O₃:0.74 P₂O₅:0.3 SiO₂:0.93 DPA:0.03 CTAB:41.0 H₂O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0075] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0076] Example 8

[0077] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0078] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0079] 1.09 g of hexadecyltrimethylammonium bromide was added to 30.00 g of deionized water and stirred in a water bath at 40 °C for 1 h. Then, 6.01 g of acidic silica sol was added at a rate of 2 s / drop, and stirring continued for 1 h. Finally, the precursor gel was added, and stirring continued for 4 h to obtain a mixture with a molar composition of 1.0 Al₂O₃:0.74 P₂O₅:0.3 SiO₂:0.93 DPA:0.03 CTAB:41.0 H₂O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0080] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0081] Example 9

[0082] SAPO-11 molecular sieves were prepared by hydrothermal synthesis.

[0083] 17.06 g of phosphoric acid and 9.41 g of di-n-propylamine were added to 40.00 g of deionized water and stirred in a water bath at 40 °C for 0.5 h. Then, 13.97 g of boehmite was added, and stirring was continued for 24 h to obtain a homogeneous gel. The gel was transferred to a stainless steel hydrothermal crystallization vessel with a polytetrafluoroethylene liner and pre-crystallized at 150 °C for 6 h to obtain a precursor gel.

[0084] 6.25 g of tetraethyl orthosilicate was added to 30.00 g of deionized water at a rate of 2 drops / s, and stirred in a water bath at 40 °C for 1 h. Then, the precursor gel was added, and stirring was continued for 4 h to obtain a mixture with a molar composition of 1.0 Al₂O₃:0.74 P₂O₅:0.3 SiO₂:0.93 DPA:41.0 H₂O. The mixture was transferred to a stainless steel hydrothermal crystallization autoclave lined with polytetrafluoroethylene and crystallized at 185 °C for 24 h to obtain a solid product.

[0085] After the solid product was washed by deionized water filtration until the pH of the filtrate was 7, it was dried at 110℃ for 12 h and calcined at 600℃ for 6 h to remove the template agent, thus obtaining SAPO-11 molecular sieve.

[0086] Example 10

[0087] SAPO-11 catalyst was prepared according to Example 1 for the acrolein hydration reaction:

[0088] 0.2 g of catalyst was placed in a continuous fixed-bed reactor with an inner diameter of 10 mm. The reaction was carried out at atmospheric pressure and 50 °C. The reactant was a 12.0% (w / w) acrolein aqueous solution containing 1000 ppm hydroquinone as a polymerization inhibitor. The catalyst was pumped into the reactor using a high-pressure liquid pump at a liquid hourly space velocity (LISH) of 0.5 h⁻¹. -1 The reaction results are shown in Table 1.

[0089] Example 11

[0090] The difference from Example 10 is that the SAPO-11 catalyst prepared according to Example 2 was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0091] Example 12

[0092] The difference from Example 10 is that the SAPO-11 catalyst prepared according to Example 3 was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0093] Example 13

[0094] The difference from Example 10 is that the SAPO-11 catalyst prepared according to Example 4 was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0095] Example 14

[0096] The difference from Example 10 is that the SAPO-11 catalyst prepared according to Example 5 was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0097] Example 15

[0098] The difference from Example 10 is that the SAPO-11 catalyst prepared according to Example 9 was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0099] Comparative Example 1

[0100] The difference from Example 10 is that a commercially available ZSM-5 catalyst was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0101] Comparative Example 2

[0102] The difference from Example 10 is that a commercially available β-catalyst was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0103] Comparative Example 3

[0104] The difference from Example 10 is that a commercially available HY catalyst was used for the acrolein hydration reaction. The reaction results are shown in Table 1.

[0105] Table 1 Results of molecular sieve-catalyzed acrolein hydration reaction

[0106]

[0107]

[0108] Example 16

[0109] The SAPO-11 catalyst prepared according to Example 1 was used for stability tests of acrolein hydration reaction.

[0110] 0.2 g of catalyst was placed in a continuous fixed-bed reactor with an inner diameter of 10 mm. The reaction was carried out at atmospheric pressure, and the reaction temperature was gradually increased from 40 °C to 60 °C. The reactant was a 12.0% (w / w) acrolein aqueous solution containing 1000 ppm of the polymerization inhibitor hydroquinone. The catalyst was pumped into the reactor using a high-pressure liquid pump at a liquid hourly space velocity (LISH) of 0.5 h⁻¹. -1 Within 2000 hours, the conversion rate of acrolein and the selectivity of 3-hydroxypropionaldehyde remained stable at 84% and 90%, respectively.

[0111] Based on the above embodiments, this invention provides a method for preparing SAPO-11 molecular sieves. The prepared hierarchical porous SAPO-11 molecular sieves exhibit high conversion and selectivity, as well as stable catalytic activity in the acrolein hydration reaction. The application of the catalyst of this invention is not limited to the usage described in this embodiment.

[0112] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a molecular sieve catalyst for the acrolein hydration reaction, characterized in that, Includes the following steps: S1. Mix phosphoric acid, aluminum source, template agent 1 and water, stir thoroughly, and transfer to a crystallization kettle for pre-crystallization to obtain precursor gel; S2. Mix the precursor gel, silicon source, template agent 2 and water, stir thoroughly, and transfer to a crystallization kettle for crystallization. S3. After crystallization, the sample is washed, dried, and calcined to obtain SAPO-11 molecular sieve catalyst.

2. The preparation method according to claim 1, characterized in that, In step S1, the aluminum source includes one or more of boehmite, aluminum isopropoxide, sodium aluminate, and aluminum nitrate. In step S1, template agent 1 includes one or more of di-n-propylamine, triethylamine, tetrapropylammonium hydroxide, and tetrapropylammonium bromide.

3. The preparation method according to claim 1, characterized in that, In step S2, the silicon source includes one or more of tetraethyl orthosilicate, acidic silica sol, fumed silica, and sodium metasilicate. In step S2, template agent 2 includes one or more of cetyltrimethylammonium bromide, P123, and F127.

4. The preparation method according to claim 1, characterized in that, In step S2, the molar ratio of aluminum source (calculated as Al2O3), phosphoric acid (calculated as P2O5), silicon source (calculated as SiO2), template agent 1 and template agent 2 is 1:(0.1-2):(0.1-3):(0.05-2):(0.001-2); Preferably, the molar ratio is 1:(0.5-1):(0.3-2):(0.1-2):(0.001-1).

5. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of aluminum source (calculated as Al2O3) to water is 1:(10-100); In step S2, the molar ratio of silicon source (calculated as SiO2) to water is 1:(50-200); Preferably, in step S1, the molar ratio of aluminum source (calculated as Al2O3) to water is 1:(20-60); In step S2, the molar ratio of silicon source (calculated as SiO2) to water is 1:(100-150).

6. The preparation method according to claim 1, characterized in that, In step S1, the pre-crystallization conditions are: isothermal crystallization at 90-150℃ for 5-12 hours; In step S2, the crystallization conditions are: constant temperature crystallization at 170-200℃ for 24-84 hours; Preferably, in step S1, the pre-crystallization conditions are: constant temperature crystallization at 120-150℃ for 5-10 hours; In step S2, the crystallization conditions are: constant temperature crystallization at 180-200℃ for 24-72 hours.

7. A molecular sieve catalyst prepared by any one of the preparation methods according to claims 1-6.

8. The application of the molecular sieve catalyst according to claim 6 in a reaction system for the catalytic hydration of acrolein to prepare 3-hydroxypropionaldehyde.

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