A method for preparing 1,3-dihydroxypropane

Abstract

The invention discloses a method for preparing 1,3-dihydroxypropane, including: an aqueous solution of acrolein is subjected to a hydration reaction under the action of a hydration catalyst, and after obtaining a mixed solution of 3-hydroxypropanal, acrolein is removed by vacuum distillation; the solution after aldehyde removal enters a microinterface reactor and is mixed with hydrogen to form a gas-liquid microemulsion, and then enters a hydrogenation reactor for hydrogenation reaction; the product after separation of the hydrogenation reaction is obtained to obtain a crude product of 1,3-dihydroxypropane, and 1,3-dihydroxypropane is obtained by distillation. The microinterface reactor of the present invention can break hydrogen into micron-sized bubbles, which are mixed with a 3-hydroxypropanal solution to form a gas-liquid micro-chemical, thereby increasing the interfacial area and mass transfer rate, thereby increasing the rate of the hydrogenation reaction, and reducing the material consumption and energy consumption of the reaction; and a hydration and hydrogenation catalyst with high catalytic performance is used at the same time to increase the yield of 1,3-dihydroxypropane. The yield and purity of 1,3-dihydroxypropane produced by the method are high, and can be used for the production of polytrimethylene terephthalate, and is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical fields of organic synthesis, catalyst preparation and chemical application, and in particular to a method for preparing 1,3-dihydroxypropane. Background Art

[0002] Polytrimethylene terephthalate (PTT) fiber has become a research hotspot in the market because it has the anti-fouling property of polyester, the softness of nylon, the fluffiness of acrylic, the elongation of spandex, and the advantages of wrinkle resistance, antistatic property, UV resistance, and easy dyeing. From the perspective of market size, the market size of my country's PTT fiber industry increased from 558 million yuan to 2.881 billion yuan from 2012 to 2019, and the market size increased nearly 6 times in seven years, and maintained a high growth rate. However, compared with foreign countries, the development of the PTT fiber industry is still relatively slow. The main reason is that the production technology of the raw material 1,3-dihydroxypropane (1,3-PDO) is limited, and the production capacity is insufficient, resulting in excessively high costs of 1,3-PDO, which has caused the price of PTT to remain high, limiting its application.

[0003] At present, the production technologies of 1,3-PDO mainly include biological method and chemical method. Although the biological method has the characteristics of mild conditions, simple operation, energy saving, low equipment investment, and environmental friendliness, it is not easy to separate and is not conducive to large-scale production. The chemical method mainly includes ethylene oxide method and acrolein hydration hydrogenation method. In recent years, with the overcapacity of propylene production in China, oxidizing propylene to acrolein and then using acrolein hydration hydrogenation method is more in line with my country's national conditions.

[0004] The production process of acrolein hydration hydrogenation mainly includes a feeding section, a hydration section, a vacuum distillation section, a hydrogenation section and a product distillation section. In the feeding section, acrolein is sprayed into the reactor at a certain space velocity, and then enters the hydration reactor, where it reacts under the action of a hydration reaction catalyst to obtain a mixed solution of 3-hydroxypropanal. Acrolein in the 3-hydroxypropanal mixed solution is removed by vacuum distillation. The 3-hydroxypropanal solution after the removal of acrolein enters the hydrogenation reactor, where it undergoes a hydrogenation reaction under the action of a hydrogenation catalyst to prepare a 1,3-dihydroxypropane mixed solution, which is then distilled to obtain 1,3-dihydroxypropane.

[0005] At present, the hydrogenation process of acrolein hydration hydrogenation method mostly adopts a two-stage hydrogenation method, with the first stage hydrogenation reaction temperature of 35-70°C and pressure of 3-10Mpa, and the second stage hydrogenation reaction temperature of 90-130°C and hydrogenation pressure of 3-10Mpa. The two-stage hydrogenation method generally uses stirring or bubbling methods, which can only produce centimeter or large millimeter scale turbulent vortices in the hydrogenation reactor, resulting in uneven mixing of hydrogen and 3-hydroxypropanal, low mass transfer efficiency, and thus slow hydrogenation reaction rate and low yield of 1,3-dihydroxypropane.

[0006] In order to further promote the full progress of the hydrogenation reaction, the yield of 1,3-dihydroxypropane is usually increased by increasing the pressure, increasing the hydrogen-to-oil ratio and other measures during the hydrogenation process, which greatly increases the material and energy consumption in the reaction process and the risks in equipment operation.

[0007] In addition, the yield of 3-hydroxypropanal in the acrolein hydration hydrogenation process also has a great influence on the yield of the final product 1,3-PDO. In the acrolein hydration hydrogenation process, selecting a catalyst that can both improve the acrolein conversion rate and improve the selectivity of 3-hydroxypropanal is also the focus of the process research.

[0008] At present, ion resins are mostly used as hydration catalysts in industry. The invention patent with authorization announcement number CN 110204422B discloses a method for preparing 1,3-PDO from acrolein. The method uses acidic cationic resins or chelated ion exchange resins modified by alkali metals / alkaline earth metals as hydration catalysts. However, ion exchange resins have problems such as easy shedding of active groups, short catalyst life and inability to regenerate.

[0009] In recent years, some new hydration catalysts have been reported successively. The invention patent with the authorization announcement number CN 112062663B discloses a method for preparing 3-hydroxypropionaldehyde (3-HPA) by hydrating acrolein. The method uses N-heterocyclic carboxylic acid ionic liquid as a homogeneous hydration catalyst, but the ionic liquid is expensive and the waste liquid is difficult to treat, which is not conducive to large-scale industrial production. Therefore, finding a hydration catalyst with high conversion rate, high selectivity, high stability, long life and regeneration has become one of the keys to preparing 3-HPA from acrolein.

[0010] The 3-hydroxypropionaldehyde generated after the hydration of acrolein is chemically active and unstable. It is easy to self-polymerize and easily undergo polymerization reaction with acrolein. The degree of polymerization increases with the increase of reaction temperature. Therefore, through process improvement and finding a hydrogenation catalyst with high conversion rate, high selectivity, high stability and long life at low temperature, the 3-hydroxypropionaldehyde in the hydration product and the polymerized 3-hydroxypropionaldehyde are depolymerized by the hydrogenation catalyst and fully reacted with hydrogen to generate 1,3-dihydroxypropane, which is also one of the keys to improve the yield of 1,3-dihydroxypropane.

[0011] In view of the above-mentioned deficiencies of the existing technology, it is crucial to find a new acrolein hydration hydrogenation production process to increase the gas-liquid two-phase mass transfer area, reduce material consumption and energy consumption in the reaction process, and cooperate with a high catalytic performance hydration catalyst and hydrogenation catalyst to increase the yield of 1,3-dihydroxypropane. Summary of the invention

[0012] In order to overcome the shortcomings of the prior art, the present invention provides a method for preparing 1,3-dihydroxypropane. The method provides a micro-interface reaction device in front of a hydrogenation reactor to break hydrogen into micron-sized bubbles to form a uniform gas-liquid emulsion with a 3-hydroxypropanal solution, thereby greatly increasing the interfacial area and mass transfer rate, thereby increasing the rate of the hydrogenation reaction, and at the same time, using a hydration catalyst and a hydrogenation catalyst with high catalytic performance to increase the yield of 1,3-dihydroxypropane.

[0013] A method for preparing 1,3-dihydroxypropane comprises the following steps:

[0014] (1) adding a polymerization inhibitor to an aqueous solution of acrolein, mixing the mixture thoroughly, and then introducing the mixture into a hydration reactor to carry out a hydration reaction under the action of a hydration reaction catalyst to obtain a mixed solution of 3-hydroxypropanal, and then removing the acrolein by distillation under reduced pressure;

[0015] (2) The 3-hydroxypropanal solution after the removal of acrolein enters the microinterface reactor and is mixed with hydrogen, and then enters the hydrogenation reactor to undergo a hydrogenation reaction under the action of a hydrogenation catalyst.

[0016] The microinterface reactor includes an interface mixer and an interface disruptor, wherein the interface mixer mixes hydrogen and 3-HPA solution, and the interface disruptor breaks hydrogen into microbubbles, which are mixed with 3-hydroxypropanal solution to form a uniform gas-liquid emulsion;

[0017] (3) The mixed liquid obtained after the hydrogenation reaction enters a gas-liquid separation tank through a quenching device to obtain crude 1,3-dihydroxypropane, and is distilled to obtain 1,3-dihydroxypropane.

[0018] The present invention uses a micro-interface reaction device to break hydrogen into micron-sized bubbles and form a uniform gas-liquid emulsion with 3-hydroxypropanal solution, and efficiently adjusts the geometric size of the gas-liquid-solid interface from the millimeter-centimeter level to the micron level, greatly improving the interfacial area and mass transfer rate, thereby increasing the rate of the hydrogenation reaction. The improvement of hydrogen mass transfer solves the balance between "hydrogen demand" and "hydrogen supply", realizes "sufficient" hydrogen supply in the hydrogenation reaction process of the system, and enables the hydrogenation reaction to obtain a high 1,3-dihydroxypropane yield under low pressure and low hydrogen-to-oil ratio conditions, greatly reducing the material and energy consumption in the reaction process and the risk in equipment operation.

[0019] Preferably, in step (1), the concentration of the acrolein aqueous solution is 5-40wt%; the inhibitor is one or more of hydroquinone, 4-methoxyphenol, phenothiazine, p-benzoquinone, 2,6-dinitro-p-cresol, 4-tert-butylcatechol, piperidinol oxide or tetramethylpiperidinium nitroxide free radical phosphite triester, and the concentration of the inhibitor is 100-3000ppm.

[0020] More preferably, in step (1), the concentration of the acrolein aqueous solution is 8-25 wt %.

[0021] Preferably, in step (1), the hydration reactor is a U-shaped hydration reactor, the feed port is higher than the discharge port, the interior is filled with a hydration reaction catalyst, and the length-to-diameter ratio of the hydration reaction catalyst is 1-20: 1. A reactor with this structure can ensure that the acrolein aqueous solution has sufficient residence time in the reactor, thereby making the reaction more complete.

[0022] Preferably, in step (1), the hydration reaction catalyst is one or more of HY, MOR, NaY, USY, β, ZSM-5 or MAM-2 molecular sieves modified with metal salts, and the metal salt is one or more of W, Mo, Sn, Ti, Zr, Ni, Fe or Cu salts.

[0023] The metal salt-modified molecular sieve hydration catalyst used in the present invention has high reaction activity, is stable, can be repeatedly regenerated, and the activity of the catalyst after regeneration remains substantially unchanged, thus reducing the treatment process of solid waste and waste liquid, and is more suitable for large-scale industrial production.

[0024] The metal salt-modified hydration reaction catalyst of the present invention is used to catalyze the acrolein hydration reaction, and a higher 3-hydroxypropanal yield can be obtained. Compared with unmodified molecular sieves, the metal salt-modified catalyst used in the present invention can significantly improve the 3-hydroxypropanal selectivity, and compared with commonly used resin catalysts, the hydration catalyst of the present invention can significantly improve the conversion rate of acrolein.

[0025] Preferably, in step (1), the metal content in the hydration reaction catalyst is 3-20 wt%.

[0026] More preferably, in step (1), the hydration reaction catalyst is a MOR molecular sieve modified with a metal W or Mo salt, and the metal content in the MOR molecular sieve catalyst modified with a metal W or Mo salt is 8-20%. The use of a MOR molecular sieve catalyst modified with a metal W or Mo salt can obtain a higher acrolein conversion rate and a higher 3-hydroxypropanal selectivity, and the final yield of 3-hydroxypropanal is higher.

[0027] Preferably, in step (1), the catalyst bed temperature of the U-shaped hydration reactor is 35-70°C, and the acrolein aqueous solution and the inhibitor are fully mixed for 0.1-2.5h. -1 The air velocity enters the U-shaped hydration reactor through spraying, flows through the hydration reaction catalyst for catalytic reaction and then flows out.

[0028] Preferably, in step (1), the temperature for removing acrolein by reduced pressure distillation is 25-50°C, the vacuum degree is 0.1-0.4 kPa, the acrolein removal time is 10-60 min, the acrolein removed by reduced pressure distillation is condensed into a storage tank, and the concentration of 3-HPA in the mixed solution after removing acrolein is 5-40wt%.

[0029] The micro-interface reactor is of external type and is arranged in front of the hydrogenation reactor. Compared with the internal type, the hydrogenation device using the external micro-interface reactor has a simple structure, is easy to maintain, and has a low cost.

[0030] Preferably, in step (2), the number of the microinterface reactors is one or more. When the number is greater than one, they are connected to the system in parallel, in series or in a mixed connection.

[0031] The series connection of microinterface reactors can make the gas-liquid emulsion mix more uniformly, which is suitable for high-concentration and high-viscosity materials, while the parallel connection can increase the material processing capacity and is more suitable for high-space-velocity reactions. The mixed connection enables the material to quickly form a uniform gas-liquid emulsion at a higher space velocity, thereby achieving efficient hydrogenation.

[0032] Preferably, in step (2), the diameter of the microbubbles is 1-1000 μm. The present invention breaks hydrogen into micron-sized bubbles through a microinterface reactor, greatly increasing the interfacial area and mass transfer rate, thereby increasing the rate of the hydrogenation reaction.

[0033] Preferably, in step (2), the hydrogenation reaction catalyst is a Raney-based catalyst such as Raney nickel or Raney copper or a supported catalyst, and the metal in the supported catalyst is one or more of Ni, Pt, Pd, Ru, Ir, Au, Fe, Co, Mo, Cu or Zn.

[0034] Preferably, the metal content of the Raney series catalyst in the hydrogenation reaction catalyst is 40-90wt%, and the metal content of the supported catalyst is 0.1-50wt%.

[0035] Preferably, in step (2), the hydrogenation reaction is a one-stage or two-stage hydrogenation, and the hydrogenation reactor is a fixed bed hydrogenation reactor.

[0036] Preferably, when the hydrogenation reaction is a one-stage hydrogenation, the temperature of the hydrogenation reaction is 35-70°C, the pressure is 1-4MPa, the hydrogen-to-oil ratio (molar ratio of H2 to 3-hydroxypropanal) is 2-10:1, and the mass space velocity of the gas-liquid emulsion is 1.0-8.0h -1 .

[0037] More preferably, the hydrogenation reaction pressure of the one-stage hydrogenation is 1.5-3 MPa, and the hydrogen-to-oil ratio is 3-7:1.

[0038] Preferably, when the hydrogenation reaction is a two-stage hydrogenation reaction, the temperature of the first stage hydrogenation reaction is 35-70°C, the temperature of the second stage hydrogenation reaction is 90-130°C, the pressure is 1-4MPa, the hydrogen-to-oil ratio is 2-10:1, and the mass space velocity is 1.0-8.0h -1 The mass ratio of the first stage hydrogenation reaction catalyst to the second stage hydrogenation reaction catalyst is 0.5-5:1.

[0039] More preferably, the hydrogenation reaction pressure of the two-stage hydrogenation is 1.5-3 MPa, and the hydrogen-to-oil ratio is 3-7:1.

[0040] In step (3), the aldehyde content in the 1,3-dihydroxypropane after distillation is less than 50 ppm, which can be used to produce polytrimethylene terephthalate (PTT), and is suitable for large-scale industrial production.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. Compared with resin and ionic liquid catalysts, the metal salt-modified molecular sieve hydration catalyst provided by the present invention has high reaction activity, stable catalyst, and can be repeatedly regenerated. The activity of the catalyst after regeneration remains basically unchanged, which reduces the treatment process of solid waste and waste liquid and is more suitable for large-scale industrial production.

[0043] 2. The present invention introduces a micro-interface reaction device in front of the hydrogenation reactor device, through which hydrogen is broken into micron-sized bubbles and 3-hydroxypropanal solution to form a uniform gas-liquid emulsion, and the geometric size of the gas-liquid-solid interface is efficiently regulated from the millimeter-centimeter level to the micron level, greatly improving the interfacial area and mass transfer rate, thereby improving the rate of the hydrogenation reaction. The improvement of hydrogen mass transfer solves the balance between "hydrogen demand" and "hydrogen supply", and realizes "sufficient" hydrogen supply in the hydrogenation reaction process of the system. There is no need to improve the mass transfer of hydrogen by increasing the hydrogen pressure and the hydrogen-to-oil ratio, so that the reaction can obtain a high 1,3-dihydroxypropane yield under low pressure and low hydrogen-to-oil ratio conditions, greatly reducing material consumption and energy consumption as well as the risks in equipment operation.

[0044] 3. The present invention increases the yield of 1,3-dihydroxypropane by arranging a microinterface reaction device before the hydrogenation reactor and simultaneously using a hydration catalyst and a hydrogenation catalyst with high catalytic performance. The aldehyde content in 1,3-dihydroxypropane after distillation is less than 50ppm, which can be used to produce polytrimethylene terephthalate (PTT) and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 The activity of the catalyst was evaluated in the hydration reaction of molybdenum-modified molecular sieve for 500 hours and its regeneration experiment.

[0047] Figure 2 is a schematic diagram of the acrolein hydration hydrogenation reaction system in Example 19,

[0048] In the figure: 1. acrolein storage tank; 2. desalted water storage tank; 3. feed pump; 4. acrolein aqueous solution storage tank; 5. heat exchanger; 6. reflux aldehydes; 7. hydration reaction tower; 8. 3-HPA collection tank; 9. vacuum dealdehyde distillation tower; 10. 3-HPA crude product storage tank; 11. micro-interface reactor; 12. first-stage hydrogenation reactor; 13. second-stage hydrogenation reactor; 14. high-pressure gas-liquid separator; 15. gas compressor; 16. light component removal tower; 17: dehydration tower; 18: refining tower; 19: light component collection tank; 20: water collection tank; 21: refined 1,3-PDO storage tank; 22: heavy component collection tank. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is described below through specific embodiments. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination steps or the insertion of other method steps before these explicitly mentioned steps; it should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0050] 1. Preparation and application of hydration catalyst

[0051] 100g of commercially available Y molecular sieve was taken for water absorption test; 200g of commercially available Y molecular sieve was weighed, and the precursor solution of the active component metal salt sodium tungstate was prepared according to the water absorption of the molecular sieve and the metal loading of the catalyst, and then the metal salt solution was poured into the molecular sieve in an equal volume impregnation manner and mixed evenly with a kneader, taken out for aging for 12h, and dried at 110°C for 12h; the dried powder was poured into a kneader, 50g of binder aluminum sol was added, and after stirring evenly, it was put into an extruder for extrusion, dried at 120°C for 12h, broken into 3-6mm particles, and placed in a muffle furnace for calcination at 500°C for 4h to obtain a metal tungsten modified Y molecular sieve, and the mass percentage of metal tungsten in the modified Y molecular sieve was 5wt%. The catalysts used in Examples 2-13 in Table 1 were prepared respectively by the same method as that for preparing the metal tungsten modified Y molecular sieve, and the metal content in the prepared catalysts is shown in Table 1.

[0052] Examples 1-13

[0053] The present invention applies the above-prepared catalyst to the reaction of preparing 3-hydroxypropionaldehyde by hydration of acrolein, so as to examine the catalytic performance of the prepared hydration catalyst. The catalytic performance of the hydration catalyst is evaluated by the conversion rate of acrolein and the selectivity of 3-hydroxypropionaldehyde in the hydration reaction.

[0054] The calculation formula of acrolein conversion rate is:

[0055]

[0056] The calculation formula for the selectivity of 3-hydroxypropanal is:

[0057]

[0058] The catalysts used in Examples 1-13 are shown in Table 1. The specific steps of preparing 3-hydroxypropanal by hydrating acrolein in Example 1-13 are as follows: 1000 ppm of 4-methoxyphenol was added to a 15 wt% acrolein solution, mixed evenly, and stirred for 1.5 h using a feed pump. -1 The acrolein solution is preheated in a preheater and then enters the upper part of the U-shaped hydration reactor. The acrolein solution flows through the W, Mo, Sn, Ti, Fe-modified Y, MOR, β, ZSM-5, MAM-2, and USY molecular sieves in a spraying manner for hydration reaction. The results of the hydration reaction are shown in Table 1.

[0059] Table 1 Application of metal-modified molecular sieve catalysts, unmodified molecular sieve catalysts and resin catalysts in hydration reactions

[0060]

[0061] Comparative Examples 1-5

[0062] The difference between Comparative Example 1-5 and Example 1-13 is that the hydration catalyst used in Comparative Example 1-5 is an unmodified molecular sieve catalyst (see Table 1).

[0063] Comparative Example 6

[0064] The difference between Comparative Example 6 and Examples 1-13 is that the hydration catalyst used in Comparative Example 6 is a resin (see Table 1).

[0065] As can be seen from Table 1, the molecular sieve catalyst modified by metal salt has little change in acrolein conversion rate relative to the unmodified molecular sieve catalyst, but significantly improves the selectivity of 3-hydroxypropanal, while relative to the resin catalyst, the conversion rate of acrolein is significantly improved, and the selectivity of 3-hydroxypropanal does not change much. Comparing the catalytic performance of the molecular sieve catalyst modified by metal salt in Examples 1-13, when WO3 / MOR and Mo2O3 / MOR are used to catalyze the acrolein hydration reaction, the conversion rate and selectivity of acrolein are both high.

[0066] In order to investigate the performance of the catalyst prepared in the example, the Mo2O3 / MOR molecular sieve in Example 7 was selected for hydration reaction for 500 h and a catalyst regeneration experiment was performed to evaluate its catalytic activity. The specific steps are as follows: 800 ppm of p-benzoquinone was added to a 10 wt% acrolein solution, mixed evenly, and then fed with a feed pump for 1.4 h. -1 The air velocity of 1000 g / min was preheated in a preheater and then sprayed into the upper part of the U-shaped hydration reactor. The U-shaped hydration reactor was filled with the Mo2O3 / MOR catalyst in Example 7. The reaction temperature was 48°C and the reaction conditions were kept stable for 500 h. After 500 h, the catalyst was regenerated and the regenerated catalyst was subjected to hydration reaction under the same experimental conditions. The experimental results before and after regeneration are shown in FIG. Figure 1 shown.

[0067] 2. Application of microinterface reactor in hydrogenation of 3-hydroxypropanal to 1,3-dihydroxypropane

[0068] Examples 14-18

[0069] A 15 wt% acrolein solution is passed through a 40°C preheater into a hydration reactor for hydration reaction. The catalyst filled in the hydration reactor is the Mo2O3 / MOR catalyst in Example 7. The mixture after the hydration reaction is subjected to reduced pressure distillation to remove acrolein. The 3-HPA solution and hydrogen with concentrations of 8 wt%, 10 wt%, 12 wt%, 15 wt%, and 18 wt% after the aldehyde removal are respectively passed into the microinterface reactor from their respective channels. The microinterface reactor mixes the hydrogen and the 3-HPA solution, breaks the hydrogen into microbubbles, and mixes them with the 3-hydroxypropanal solution to form a uniform gas-liquid emulsion. The mass space velocity of the 3-HPA solution is 4.0 h-1 , the hydrogen-to-oil ratio is 4:1, and the uniformly mixed gas-liquid emulsion enters a fixed-bed reactor equipped with a nickel-based catalyst, and the hydrogenation reaction is carried out at 50°C and 3MPa. The mass yield of 1,3-PDO is calculated as follows:

[0070]

[0071] The mass yields of 1,3-PDO obtained in Examples 14-18 are shown in Table 2.

[0072] Table 2 Application of microinterface reaction system in fixed bed primary hydrogenation reaction

[0073]

[0074] Comparative Examples 7-12

[0075] Comparative Example 7

[0076] This embodiment and embodiment 16 use the same hydration raw material, no micro-interface reaction system, and other conditions are the same.

[0077] Comparative Example 8

[0078] This embodiment and embodiment 16 use the same hydrated raw material, the hydrogenation pressure is 7 MPa, there is no micro-interface reaction system, and the other conditions are the same.

[0079] Comparative Example 9

[0080] This example and Example 16 use the same hydrated raw material, the hydrogenation pressure is 7 MPa, and the mass space velocity is 2.0 h -1 , no microinterface reaction system, and other conditions are the same.

[0081] Comparative Example 10

[0082] This embodiment and embodiment 16 use the same hydrated raw material, the hydrogenation pressure is 7 MPa, the hydrogen-to-oil ratio is 9:1, there is no micro-interface reaction system, and the other conditions are the same.

[0083] Comparative Example 11

[0084] This example and Example 16 use the same hydrated raw material, the hydrogenation pressure is 7 MPa, the hydrogen-to-oil ratio is 9:1, and the mass space velocity is 2.0 h -1 , no microinterface reaction system, and other conditions are the same.

[0085] Comparative Example 12

[0086] This example and Example 18 use the same hydrated raw material, the hydrogenation pressure is 7 MPa, the hydrogen-to-oil ratio is 9:1, and the mass space velocity is 2.0 h -1, no microinterface reaction system, and other conditions are the same.

[0087] As shown in the table, Examples 14-18 introduced a microinterface reaction device, and the hydrogenation reaction was carried out at 3 MPa, a hydrogen-to-oil ratio of 4:1, and a mass space velocity of 4.0 h -1 , a higher 1,3-PDO yield can be obtained when the mass concentration of 3-hydroxypropanal is between 8-18wt%. It can be seen from Example 16 and Comparative Examples 7-11 that for the same raw materials, when a micro-interface reaction device is not introduced, the yield of 1,3-PDO needs to be increased by increasing the pressure, increasing the hydrogen-to-oil ratio, and reducing the space velocity. Comparing the results of Example 18 and Comparative Example 12, it can be seen that when the mass concentration of 3-hydroxypropanal is high, when there is no micro-interface reaction device in the hydrogenation reaction, even by increasing the pressure, increasing the hydrogen-to-oil ratio, and reducing the space velocity, a high 1,3-dihydroxypropane yield cannot be obtained.

[0088] Embodiment 19

[0089] The acrolein hydration hydrogenation reaction system used in this embodiment is as follows Figure 2 As shown, it includes a feed zone, a hydration reaction zone, a dealdehyde zone, a hydrogenation reaction zone, a gas-liquid separation zone and a refining zone. In the feed zone, acrolein is mixed with desalted water to obtain an acrolein aqueous solution; the acrolein aqueous solution enters a hydration reaction tower, and a hydration reaction is carried out under the action of a hydration catalyst to prepare 3-HPA; the mixed solution obtained after the hydration reaction is subjected to reduced pressure distillation for dealdehyde treatment, and the removed acrolein is refluxed into the acrolein aqueous solution storage tank for another hydration reaction, and the crude 3-HPA after the removal of acrolein enters a micro-interface reactor, and the micro-interface reactor breaks hydrogen into microbubbles to form a uniform gas-liquid emulsion with 3-hydroxypropanal; the gas-liquid emulsion formed by hydrogen and 3-hydroxypropanal enters a two-stage hydrogenation reaction device, and a hydrogenation reaction is carried out under the action of a hydrogenation catalyst, and the mixed solution obtained after hydrogenation enters a high-pressure gas-liquid separator for gas-liquid separation to obtain a 1,3-PDO crude product, which is refined to obtain a 1,3-PDO pure product.

[0090] The specific steps of preparing 1,3-PDO in this embodiment are as follows: a 20 wt% acrolein solution is introduced into a hydration reactor through a 40°C preheater for hydration reaction, the catalyst filled in the hydration reactor is the WO3 / MOR catalyst in Example 6, the mixture after the hydration reaction is subjected to reduced pressure distillation to remove acrolein, a 3-HPA solution with a concentration of 12 wt% after the aldehyde removal and hydrogen are introduced into a microinterface reactor from respective channels, the microinterface reactor mixes hydrogen and 3-HPA solution, breaks hydrogen into microbubbles, and mixes with 3-hydroxypropanal solution to form a uniform gas-liquid emulsion, and the mass space velocity of the 3-HPA solution is 5.0 h -1, the hydrogen-to-oil ratio was 4:1, the pressure was 3 MPa, and the evenly mixed gas-liquid emulsion entered a fixed bed reactor equipped with a nickel-based catalyst, a first-stage hydrogenation reaction was carried out at 60°C, and a second-stage hydrogenation reaction was carried out at 120°C. The mass ratio of the first-stage hydrogenation reaction catalyst to the second-stage hydrogenation reaction catalyst was 4:1. The mass yield of 1,3-PDO obtained in Example 19 is shown in Table 3.

[0091] Embodiment 20

[0092] The 3-hydroxypropanal concentration in this embodiment is 18 wt %, and the other conditions are the same as those in Example 19.

[0093] Comparative Examples 13-17

[0094] Comparative Example 13

[0095] This embodiment and embodiment 19 use the same hydration raw material, no micro-interface reaction system, and other conditions are the same.

[0096] Comparative Example 14

[0097] This example and Example 19 use the same hydration raw material, the reaction pressure is 7 MPa, there is no micro-interface reaction system, and the other conditions are the same.

[0098] Comparative Example 15

[0099] This embodiment and embodiment 19 use the same hydration raw material, the hydrogen-to-oil ratio is 9:1, there is no micro-interface reaction system, and the other conditions are the same.

[0100] Comparative Example 16

[0101] This example and Example 19 use the same hydration raw material, and the mass space velocity is 2.0h -1 , no microinterface reaction system, and other conditions are the same.

[0102] Comparative Example 17

[0103] This example uses the same hydrated raw material as Example 19, with a reaction pressure of 7 MPa, a hydrogen-to-oil ratio of 9:1, and a mass space velocity of 2.0 h -1 , no microinterface reaction system, and other conditions are the same.

[0104] Table 3 Application of microinterface reaction device in fixed bed two-stage hydrogenation reaction

[0105]

[0106] As shown in Table 3, the mass yield of 1,3-PDO is significantly improved after two-stage hydrogenation, which indicates that the two-stage hydrogenation has a better effect and the mass yield of the prepared 1,3-PDO is higher. Compared with the system without the microinterface reactor, the addition of the microinterface reactor increases the yield of 1,3-dihydroxypropane and significantly reduces the reaction pressure and hydrogen-to-oil ratio, which greatly improves the safety factor in industrial operation and reduces material and energy consumption.

Claims

1. A method for preparing 1,3-dihydroxypropane, characterized in that: The following steps are involved: (1) adding a polymerization inhibitor to an aqueous solution of acrolein, mixing the mixture thoroughly, and then introducing the mixture into a hydration reactor to carry out a hydration reaction under the action of a hydration reaction catalyst to obtain a mixed solution of 3-hydroxypropanal, and then removing the acrolein by distillation under reduced pressure. The hydration reactor is a U-shaped hydration reactor, the feed port is higher than the discharge port, the interior is filled with a hydration reaction catalyst, and the length-to-diameter ratio of the hydration reaction catalyst is 1-20:

1. The hydration reaction catalyst is a MOR molecular sieve modified by a metal W or Mo salt, and the metal content in the MOR molecular sieve catalyst modified by a metal W or Mo salt is 8-20wt%; (2) The 3-hydroxypropanal solution after the removal of acrolein enters the microinterface reactor and is mixed with hydrogen, and then enters the hydrogenation reactor to undergo a hydrogenation reaction under the action of a hydrogenation catalyst. The microinterface reactor includes an interface mixer and an interface disruptor, wherein the interface mixer mixes hydrogen and 3-HPA solution, and the interface disruptor breaks hydrogen into microbubbles, which are mixed with 3-hydroxypropanal solution to form a uniform gas-liquid emulsion; (3) The mixed liquid obtained after the hydrogenation reaction enters a gas-liquid separation tank through a quenching device to obtain crude 1,3-dihydroxypropane, and is distilled to obtain 1,3-dihydroxypropane.

2. The method according to claim 1, characterized in that: The number of the microinterface reactors is one or more. When the number is greater than one, they are connected to the system in parallel, in series or in a mixed connection. The diameter of the microbubbles is 1-1000 μm.

3. The method according to claim 1, characterized in that The concentration of the acrolein aqueous solution is 5-40wt%; the inhibitor is one or more of hydroquinone, 4-methoxyphenol, phenothiazine, p-benzoquinone, 2,6-dinitro-p-cresol, 4-tert-butylcatechol, piperidinol oxide or tetramethylpiperidinium nitroxide free radical phosphite triester, and the concentration of the inhibitor is 100-3000ppm.

4. The method according to claim 1, characterized in that: The catalyst bed temperature of the U-shaped hydration reactor is 35-70°C, and the acrolein aqueous solution and the inhibitor are fully mixed and heated for 0.1-2.5h. -1 The air velocity enters the U-shaped hydration reactor through spraying, flows through the hydration reaction catalyst for catalytic reaction and then flows out.

5. The method according to claim 1, characterized in that: The temperature of removing acrolein by vacuum distillation is 25-50°C, the vacuum degree is 0.1-0.4kPa, the acrolein removal time is 10-60min, the acrolein removed by vacuum distillation enters the storage tank after condensation, and the concentration of 3-HPA in the mixed solution after removing acrolein is 5-40wt%.

6. The method according to claim 1, characterized in that: The hydrogenation reaction catalyst is a Raney catalyst or a supported catalyst, the metal in the supported catalyst is one or more of Ni, Pt, Pd, Ru, Ir, Au, Fe, Co, Mo, Cu or Zn; the metal content in the Raney catalyst is 40-90wt%, and the metal content in the supported catalyst is 0.1-50wt%.

7. The method according to claim 1, characterized in that: The hydrogenation reaction is a one-stage or two-stage hydrogenation. When the hydrogenation reaction is a one-stage hydrogenation, the temperature of the hydrogenation reaction is 35-70°C, the pressure is 1-4MPa, the hydrogen-to-oil ratio is 2-10:1, and the mass space velocity of the gas-liquid emulsion is 1.0-8.0h -1 ; When the hydrogenation reaction is a two-stage hydrogenation reaction, the temperature of the first stage hydrogenation reaction is 35-70°C, the temperature of the second stage hydrogenation reaction is 90-130°C, the pressure is 1-4MPa, the hydrogen-to-oil ratio is 2-10:1, and the mass space velocity is 1.0-8.0h -1 The mass ratio of the first stage hydrogenation reaction catalyst to the second stage hydrogenation reaction catalyst is 0.5-5:1.

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