Metal modified resin catalyst, preparation and application of metal modified resin catalyst in hydration of acrylic acid

Abstract

The invention relates to a metal-modified ion exchange resin catalyst and application thereof in catalyzing hydration of acrylic acid to prepare 3-hydracrylic acid. A preparation method of the catalyst comprises the following steps: (1) metal ion exchange and (2) low-temperature reduction. According to the present invention, the appropriate content of the metal is introduced into the catalyst, such that the intermediate of the acrylic acid polymerization reaction can be adsorbed, and the active component for catalyzing the hydration reaction is protected so as to improve the selectivity and the reaction stability of the 3-hydracrylic acid; the preparation conditions of the catalyst are mild, and the process is stable and controllable. The prepared catalyst has the advantages of high activity, strong polymerization resistance, good stability and the like.

Description

Technical Field

[0001] The invention relates to a catalytic method for preparing 3-hydroxypropionic acid by hydrating acrylic acid, in particular to a catalytic hydration method of acrylic acid and water on a metal-modified ion exchange resin. Background Art

[0002] 3-Hydroxypropionic acid is a widely used chemical raw material. It can be used as an intermediate in fine chemicals and is also a key monomer for the synthesis of poly 3-hydroxypropionic acid (P3HP). In recent years, with the implementation of the plastic reduction order, polyhydroxyalkanoates (PHAs) have attracted more and more attention from the international community. Polyhydroxyalkanoates (PHAs) have become a research hotspot in recent years due to their superior biodegradability. Among them, poly 3-hydroxypropionic acid (P3HP) exhibits excellent properties in hardness, tensile strength, ductility and biocompatibility, and has potential application value.

[0003] At present, the synthesis method reported for 3-hydroxypropionic acid is mainly biological. However, the biological fermentation process takes a long time, has low yield, and the separation and purification process is complicated, making it difficult to produce on a large scale. The chemical synthesis of 3-hydroxypropionic acid includes β-propiolactone hydrolysis, β-hydroxypropionitrile acidification, 3-hydroxypropionaldehyde oxidation, vinyl acetate carbonylation, propylene alcohol oxidation, and acrylic acid hydration. Among them, the reaction conditions of acrylic acid hydration are relatively mild, and the operating conditions are easy to control. There are few reports on the preparation of 3-hydroxypropionic acid by acrylic acid hydration. Patent CN102746141A reports a method for preparing 3-hydroxypropionic acid by hydration of acrylic acid catalyzed by inorganic acid, molecular sieve and resin, and reacts at 60-280°C in a kettle reactor for 1-24h to obtain 3-hydroxypropionic acid. Patent CN110981718B uses acid-modified β-type molecular sieve as a catalyst, which can reduce the reaction temperature and by-product selectivity of acrylic acid hydration and improve the yield of 3-hydroxypropionic acid. Patent CN113461512A reports a method for preparing 3-hydroxypropionic acid by hydrating acrylic acid catalyzed by saturated organic acid. The currently reported technologies generally have problems such as low efficiency and side reactions. During the acrylic acid hydration reaction, the main side reaction is the self-polymerization of acrylic acid under high temperature and strong acid conditions.

[0004] The present invention develops a metal-modified ion exchange resin catalyst and an application method thereof in catalyzing the hydration of acrylic acid to produce 3-hydroxypropionic acid. Introducing a suitable amount of metal into the ion exchange resin catalyst can adsorb the intermediate of the acrylic acid polymerization reaction and protect the active components used to catalyze the hydration reaction, thereby improving the selectivity and reaction stability of 3-hydroxypropionic acid. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a high-efficiency catalyst for preparing 3-hydroxypropionic acid by continuous hydration of acrylic acid, which can improve the hydration reaction efficiency, inhibit side reactions and improve product selectivity.

[0006] The technical solution is:

[0007] The method for preparing a catalyst for preparing 3-hydroxypropionic acid by hydrating acrylic acid of the present invention comprises the following steps:

[0008] (1) Metal ion exchange: adding an ion exchange resin to an aqueous solution of a metal chloride, stirring and refluxing at a certain temperature, cooling to room temperature, washing with deionized water and ethanol in sequence, and drying to obtain a metal ion exchange resin;

[0009] (2) Low-temperature reduction: Add the metal ion exchange resin to the reducing agent solution, stir to react, wash with deionized water and ethanol in turn, and vacuum dry to obtain a catalyst for preparing 3-hydroxypropionic acid by hydration of acrylic acid.

[0010] Preferably, in step (1), the metal salt is NiCl2·6H2O, and the concentration is 0.05-0.5 mol / L; the solid-liquid ratio of the resin to the metal salt solution is 1:10-1:20; the reaction temperature is 50-90°C, and the reflux time is 4-8h; after cooling to room temperature, washing with deionized water until no chloride ions remain, and then washing with anhydrous ethanol; vacuum drying at 50-100°C for 6-12h to obtain a metal ion exchange resin.

[0011] Preferably, in step (2), the reducing agent is a sodium borohydride aqueous solution with a concentration of 0.2-2.0 mol / L; the solid-liquid ratio is 1:10-1:20; the reaction time is 1-4 h; after the reaction is completed, washing with deionized water and anhydrous ethanol in sequence; and drying at 80-120° C. for 6-12 h to obtain a metal-modified exchange resin with a metal content of 0.1-1 wt%.

[0012] A solid superacid catalyst for preparing 3-hydroxypropionic acid by hydrating acrylic acid is used in the reaction of preparing 3-hydroxypropionic acid by hydrating acrylic acid.

[0013] Preferably, a fixed bed reactor is used, the raw material is an aqueous solution of acrylic acid, the mass concentration is 25-50%; the inhibitor is p-methoxyphenol, the mass ratio of the inhibitor to acrylic acid is 0.05-0.2%; the reaction temperature is 120-180°C; the reaction pressure is 0.5-1.5MPa; based on the mass of the raw material, the mass space velocity is 0.75-2h -1 .

[0014] The invention introduces a suitable amount of metal into the catalyst, which can adsorb the intermediate of acrylic acid polymerization reaction and protect the active component used for catalytic hydration reaction, thereby improving the selectivity and reaction stability of 3-hydroxypropionic acid. The preparation conditions of the catalyst are mild, and the process is stable and controllable. The prepared catalyst has the advantages of high activity, strong anti-polymerization ability, good stability and the like.

[0015] Beneficial technical effects

[0016] 1. The present invention prepares an acrylic acid hydration catalyst by ion exchange and low-temperature reduction, introduces a suitable amount of metal, can adsorb the intermediate of acrylic acid polymerization reaction, protect the active components used to catalyze the hydration reaction, thereby improving the selectivity and reaction stability of 3-hydroxypropionic acid.

[0017] 2. The catalyst preparation process is simple, controllable and easy to operate, and has broad application prospects. DETAILED DESCRIPTION

[0018] In order to further explain the present invention in detail, several specific implementation cases are given below, but the present invention is not limited to these embodiments.

[0019] Example 1

[0020] (1) Metal ion exchange: 1.19 g NiCl2·6H2O was weighed and dissolved in 50 mL deionized water, and 5.0 g ion exchange resin Amberlyst-15 was added. After stirring and refluxing at 80°C for 4 h, the mixture was cooled to room temperature and washed with deionized water until no chloride ions remained. The mixture was then washed with anhydrous ethanol and dried at 120°C for 12 h to obtain Ni 2+ exchanged resin precursor;

[0021] (2) Low-temperature reduction: 1.89 g of sodium borohydride was dissolved in 50 mL of deionized water, and the precursor prepared in step (1) was added. After reacting for 2 h, the mixture was washed with deionized water and anhydrous ethanol in turn, and dried under vacuum at 60° C. for 12 h to obtain a metal-modified exchange resin, which was designated as catalyst 1.

[0022] (3) Catalyst evaluation: The catalyst was evaluated in a fixed bed tubular reactor. The raw material was a 50% aqueous solution, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 180°C, the reaction pressure was 1.0 MPa, and the mass space velocity was 1.0 h -1 The composition and content of the product were analyzed by high performance liquid chromatography, and the conversion rate of acrylic acid and the selectivity of 3-hydroxypropionic acid were calculated.

[0023] Comparative Example 1

[0024] Comparative Example 1 is compared with Example 1. The process and conditions are the same as those of Example 1, except that the catalyst is an unmodified ion exchange resin, which is recorded as Catalyst 2. The catalyst evaluation conditions are the same as those of Example 1.

[0025] Example 2: Different ion exchange conditions

[0026] Compared with Example 1, Example 2 has the same process and conditions as Example 1, except that in step (1), 1.18 g of NiCl2·6H2O is weighed and dissolved in 100 mL of deionized water, and stirred and refluxed at 50° C. for 8 h, which is recorded as Catalyst 3. The catalyst evaluation conditions are the same as those in Example 1.

[0027] Example 3: Different ion exchange conditions

[0028] Compared with Example 1, Example 3 has the same process and conditions as Example 1, except that in step (1), 8.91 g of NiCl2·6H2O is weighed and dissolved in 75 mL of deionized water, and stirred and refluxed at 90° C. for 2 h, which is recorded as Catalyst 4. The catalyst evaluation conditions are the same as those in Example 1.

[0029] Example 4: Different low temperature reduction conditions

[0030] Compared with Example 1, Example 4 has the same process and conditions as Example 1, except that in step (2), 2.5 g of hydrazine hydrate is weighed and dissolved in 50 mL of deionized water, which is recorded as Catalyst 5. The catalyst evaluation conditions are the same as those in Example 1.

[0031] Example 5: Different low temperature reduction conditions

[0032] Compared with Example 1, Example 5 has the same process and conditions as Example 1, except that in step (2), 0.5 g of hydrazine hydrate is weighed and dissolved in 50 mL of deionized water, and the reduction treatment is carried out for 4 h, which is recorded as Catalyst 6. The catalyst evaluation conditions are the same as those in Example 1.

[0033] Example 6: Different low temperature reduction conditions

[0034] Compared with Example 1, Example 6 has the same process and conditions as Example 1, except that in step (2), 1.54 g of ammonia borane is weighed and dissolved in 50 mL of deionized water, which is recorded as Catalyst 7. The catalyst evaluation conditions are the same as those in Example 1.

[0035] Example 7: Different low temperature reduction conditions

[0036] Compared with Example 1, Example 7 has the same process and conditions as Example 1, except that in step (2), 0.31 g of ammonia borane is weighed and dissolved in 50 mL of deionized water and reduced for 1 hour, which is recorded as Catalyst 8. The catalyst evaluation conditions are the same as those in Example 1.

[0037] Example 8: Different types of exchange metals

[0038] Compared with Example 1, Example 8 has the same process and conditions as Example 1, except that in step (1), 0.85 g of CuCl2·2H2O is weighed and dissolved in 50 mL of deionized water, and in step (2), 0.38 g of sodium borohydride is weighed and dissolved in 50 mL of deionized water, which are recorded as Catalyst 9. The catalyst evaluation conditions are the same as those in Example 1.

[0039] Example 9: Different types of exchange metals

[0040] Compared with Example 1, Example 9 has the same process and conditions as Example 1, except that in step (1), 1.35 g of FeCl3·6H2O is weighed and dissolved in 50 mL of deionized water, and the reduction time in step (2) is 4 h, which is recorded as Catalyst 10. The catalyst evaluation conditions are the same as those in Example 1.

[0041] Example 10: Different types of exchange metals

[0042] Compared with Example 1, the process and conditions of Example 10 are the same as those of Example 1, except that in step (1), 1.19 g of CoCl2·6H2O is weighed and dissolved in 50 mL of deionized water, and in step (2), 3.78 g of sodium borohydride is weighed and dissolved in 50 mL of deionized water, which are recorded as Catalyst 11. The catalyst evaluation conditions are the same as those of Example 1.

[0043] The following table lists the reaction evaluation results of the catalyst prepared by the method of the present invention:

[0044] Example Acrylic acid conversion rate / % Dimer selectivity / % 3-Hydroxypropionic acid selectivity / % Example 1 81.1 7.8 84.2 Comparative Example 1 61.6 15.2 67.8 Example 2 70.5 12.8 71.6 Example 3 80.1 8.3 82.8 Example 4 80.3 8.1 82.6 Example 5 76.1 9.3 72.9 Example 6 79.8 8.6 80.3 Example 7 75.1 9.4 71.3 Example 8 80.9 8.0 83.9 Example 9 77.5 10.1 81.8 Example 10 77.8 9.9 82.3

[0045] From Example 1 and Comparative Example 1, it can be seen that the metal-modified ion exchange resin is beneficial to improving the conversion rate of acrylic acid and the selectivity of 3-hydroxypropionic acid, and inhibiting the formation of acrylic acid dimers; from Examples 1-7, it can be seen that the modification conditions of 1 are optimal; from Examples 1, 8-10, it can be seen that Ni has the best effect, and Cu, Co and Fe decrease in turn.

Claims

1. A metal-modified ion exchange resin catalyst, comprising a metal auxiliary agent and an ion exchange resin, wherein the content of the metal auxiliary agent is 0.05-5wt%, preferably 0.1-1wt%; and the rest is the ion exchange resin.

2. The catalyst according to claim 1, characterized in that: The ion exchange resin used is a macroporous strongly acidic ion exchange resin, and the model is one or more of D001, HND58 and Amberlyst-15.

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that: The preparation of the catalyst comprises the following steps: (1) Metal ion exchange: adding an ion exchange resin to an aqueous solution of a metal chloride, stirring and refluxing the solution, cooling the solution to room temperature, washing the solution with deionized water and ethanol in turn, and drying the solution to obtain a metal ion exchange resin; (2) Low-temperature reduction: Add the metal ion exchange resin to the reducing agent solution, stir to react, wash with deionized water and ethanol in turn, and dry to obtain a catalyst for preparing 3-hydroxypropionic acid by hydration of acrylic acid.

4. The method according to claim 3, characterized in that: In step (1), the metal chloride is one or more of NiCl2·6H2O, CuCl2·2H2O, FeCl3·6H2O or CoCl2·6H2O, preferably NiCl2·6H2O; the metal chloride concentration is 0.01-1 mol / L, preferably 0.05-0.5 mol / L; The solid-liquid ratio of the ion exchange resin to the aqueous solution of the metal chloride is 1:5-1:50 (g:mL), preferably 1:10-1:20; the reaction temperature is 50-90°C, the reflux time is 2-10h, preferably 4-8h; after cooling to room temperature, washing with deionized water until no chloride ions remain, and then washing with anhydrous ethanol; drying at 80-120°C for 6-12h to obtain a metal ion exchange resin.

5. The method according to claim 3, characterized in that: In step (2), the reducing agent is an aqueous solution of one or more of sodium borohydride, hydrazine hydrate or ammonia borane, preferably sodium borohydride; the reducing agent concentration is 0.05-5 mol / L, preferably 0.2-2.0 mol / L; The solid-liquid ratio of the ion exchange resin to the aqueous solution of the metal chloride is 1:5-1:50 (g:mL), preferably 1:10-1:20; the reaction time is 0.5-8h, preferably 1-4h; after the reaction is completed, washing with deionized water and anhydrous ethanol in sequence; vacuum drying at 50-100°C for 6-12h to obtain a metal-modified exchange resin, wherein the metal content is 0.05-5wt%, preferably 0.1-1wt%.

6. Use of the catalyst according to claim 1 or 2 or the catalyst prepared by the preparation method according to any one of claims 3 to 5 in catalyzing the hydration of acrylic acid to prepare 3-hydroxypropionic acid.

7. The use according to claim 6, characterized in that: A fixed bed reactor is used, the raw material is an aqueous solution of acrylic acid, the mass concentration is 15-75%, preferably 25-50%; the inhibitor is one or more of hydroquinone, p-methoxyphenol and phenothiazine, the mass ratio of the inhibitor to acrylic acid is 0.01-1%, preferably 0.05-0.2%; the reaction temperature is 100-200°C, preferably 120-180°C; the reaction pressure is 0.1-2MPa, preferably 0.5-1.5MPa; based on the mass of the raw material, the mass space velocity is 0.5-5h -1 , preferably 0.75-2h -1 .