Preparation and application of acrylic acid hydration catalyst

Abstract

The invention relates to a solid superacid catalyst for hydrating acrylic acid. A preparation method of the solid superacid catalyst comprises the following steps: (1) preparing a carrier; (2) loading active components; and (3) partially reducing. According to the invention, valence-state-adjustable cerium oxide is taken as a carrier, and after superacid is loaded, adsorption of active groups of reactants can be promoted through empty holes generated after partial reduction, so that the reaction activity is improved. The method has the advantages of easily available raw materials, mild reaction conditions, high product selectivity and the like.

Description

Technical Field

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

[0002] In recent years, the problem of "white pollution" has become increasingly serious, and a series of environmental problems caused by the long degradation cycle of traditional plastics have increasingly attracted widespread 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. 3-Hydroxypropionic acid, as a key monomer for the synthesis of P3HP, is a widely used chemical raw material.

[0003] At present, there are many reports on the biological synthesis of 3-hydroxypropionic acid, but the biological fermentation process is long, the yield is low, 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, allyl alcohol oxidation, and acrylic acid hydration. Among them, the acrylic acid hydration method has relatively mild reaction conditions and easy-to-control operating conditions.

[0004] 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 hydrating 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 reports that acid-modified β-type molecular sieves can reduce the reaction temperature and by-product selectivity of acrylic acid hydration and increase 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, and the catalyst is easy to separate and recover. In the acrylic acid hydration reaction process, the main side reactions are the self-polymerization of acrylic acid under high temperature and strong acidic conditions and the etherification of 3-hydroxypropionic acid. The currently reported technologies generally have problems such as low efficiency and side reactions, and lack of efficient catalytic systems.

[0005] The present invention develops a new method for preparing a catalyst for preparing 3-hydroxypropionic acid by hydrating acrylic acid. The catalyst uses cerium oxide with adjustable valence as a carrier, and is partially reduced after being loaded with sulfuric acid. The generated defect sites promote the adsorption of active groups, thereby improving the reaction activity. Summary of the invention

[0006] 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.

[0007] The technical solution is:

[0008] The method for preparing a catalyst for preparing 3-hydroxypropionic acid by hydrating acrylic acid of the present invention comprises the following steps:

[0009] (1) Preparation of carrier: The raw salt is prepared into an aqueous solution, the pH value of the solution is adjusted and stirred continuously to form a gel, and the carrier is obtained after washing, drying and calcining;

[0010] (2) Active component loading: adding the carrier into a sulfuric acid aqueous solution, and obtaining a catalyst precursor after impregnation, filtration, drying, and calcination;

[0011] (3) Partial reduction: In a reducing atmosphere, the catalyst precursor is partially reduced to obtain a catalyst for preparing 3-hydroxypropionic acid by hydration of acrylic acid. This step is a key step of the present invention, and its function is to obtain an appropriate amount of oxygen vacancies through partial reduction, which is beneficial to the adsorption of active groups in the reactant molecules, thereby improving the efficiency of the main reaction and inhibiting side reactions.

[0012] Preferably, in step (1), the raw salt is Ce(NO3)3·6H2O; the pH adjuster is ammonia water, and the pH value is 10-11; stirring for 10-12 hours, washing with deionized water to neutrality; drying at 110-130°C for 6-12 hours, and calcining at 450-550°C for 4-6 hours to obtain a carrier.

[0013] Preferably, in step (2), the active component is sulfate, and the active component content is 10-40wt%; the carrier content is 60-90wt%; the concentration of the sulfuric acid solution used is 0.5-2mol / L; after immersion at room temperature for 4-6h, the solid product is filtered to obtain a solid product, which is dried at 110-130°C for 6-12h and calcined at 450-550°C for 4-6h to obtain a catalyst precursor.

[0014] Preferably, the reducing atmosphere in step (3) is hydrogen or a mixture of hydrogen and nitrogen (or argon or helium), the volume proportion of hydrogen in the mixture is 20-60%; the reduction temperature is 300-400°C; and the reduction time is 2-4h.

[0015] 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.

[0016] Preferably, 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, and 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 .

[0017] The present invention uses valence-adjustable cerium oxide as a carrier, and after loading a superacid, the vacant sites generated after partial reduction can promote the adsorption of active groups of reactants, thereby improving the reaction activity. The present invention has the advantages of easy availability of raw materials, mild reaction conditions, high product selectivity, etc.

[0018] Beneficial technical effects

[0019] 1. The present invention prepares an acrylic acid hydration catalyst by carrier preparation, active component loading and partial reduction, with simple steps, mild conditions and controllable process. The prepared catalyst has both a strong acid center and a hole site, which is conducive to the adsorption of active groups and improves the reaction activity;

[0020] 2. The catalyst has the advantages of low reaction temperature, high selectivity, good stability, etc. The reaction process is simple, controllable and easy to operate, and has broad application prospects. DETAILED DESCRIPTION

[0021] 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.

[0022] Example 1

[0023] (1) Preparation of carrier: Weigh 5.0 g of Ce(NO3)3·6H2O, dissolve it in 100 mL of deionized water, add 3.4 mol / L of ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120°C for 12 h, and calcine at 500°C for 4 h to obtain a carrier. XRD results show that the synthesized carrier is CeO2;

[0024] (2) Active component impregnation: Weigh 2.0 g of the support prepared in step (1), add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, and then filter to obtain a solid product, dry at 120° C. for 12 h, and calcine at 500° C. for 4 h to obtain a catalyst precursor;

[0025] (3) Partial reduction: The catalyst precursor prepared in step (2) was placed in a quartz tube furnace and reduced at 400°C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 1.

[0026] (4) Catalyst evaluation: The catalyst was evaluated in a fixed bed tubular reactor. The raw material was an aqueous solution of acrylic acid with a mass concentration of 50%, 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 ; Product analysis: 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.

[0027] Comparative Example 1

[0028] Comparative Example 1 is different from Example 1 in that the partial reduction process of step (3) is omitted, and the remaining processes and conditions are exactly the same as those of Example 1; the obtained catalyst is recorded as Catalyst 2. Catalyst evaluation: The catalyst was evaluated in a fixed bed tubular reactor, the raw material was an acrylic acid aqueous solution with a mass concentration of 50%, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 100°C, the reaction pressure was 0.1 MPa, and the mass space velocity was 5.0 h -1 The product analysis conditions are exactly the same as those in Example 1.

[0029] Example 2: Carrier Synthesis Precursor Salt Type - Ce(SO4)2·4H2O

[0030] Weigh 5.0gCe(SO4)2·4H2O, dissolve in 100mL deionized water, add 3.4mol / L ammonia water to adjust the pH to 10.0, stir for 16h to form a gel, wash with deionized water until neutral, dry at 130℃ for 6h, calcine at 650℃ for 2h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0031] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 130 ° C for 6 h, and calcine at 650 ° C for 2 h to obtain a catalyst precursor;

[0032] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 3.

[0033] The catalyst evaluation conditions and process were the same as in Example 1.

[0034] Example 3: Carrier Synthesis Precursor Salt Type - CeCl3·7H2O

[0035] Weigh 5.0 g CeCl3·7H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 12.0, stir for 1 h to form a gel, wash with deionized water until neutral, dry at 110 ° C for 12 h, and calcine at 400 ° C for 8 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0036] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 110 ° C for 12 h, and calcine at 400 ° C for 8 h to obtain a catalyst precursor;

[0037] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 4.

[0038] The catalyst evaluation conditions and process were the same as in Example 1.

[0039] Example 4: Increased sulfuric acid concentration

[0040] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0041] Weigh 2.0 g of the carrier, add 2 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0042] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 5.

[0043] The catalyst evaluation conditions and process were the same as in Example 1.

[0044] Example 5: Sulfuric acid concentration reduction

[0045] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0046] Weigh 2.0 g of the carrier, add 0.5 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0047] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 6.

[0048] The catalyst evaluation conditions and process were the same as in Example 1.

[0049] Example 6: Extended immersion time

[0050] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0051] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 10 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0052] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 7.

[0053] The catalyst evaluation conditions and process were the same as in Example 1.

[0054] Example 7: Shortened immersion time

[0055] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0056] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 1 h, filter to obtain a solid product, dry at 120° C. for 12 h, and calcine at 500° C. for 4 h to obtain a catalyst precursor;

[0057] The catalyst precursor was placed in a quartz tube furnace and reduced at 400 °C for 3 h in a H2 atmosphere (flow rate 50 mL / min) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 8.

[0058] The catalyst evaluation conditions and process were the same as in Example 1.

[0059] Example 8: Reduction conditions, reduction atmosphere, reduction temperature, reduction time

[0060] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0061] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0062] The catalyst precursor was placed in a quartz tube furnace and reduced at 350°C for 6 h in a H2 / N2 (flow rate 50 mL / min) mixed atmosphere (H2 volume ratio 10%) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 9.

[0063] The catalyst evaluation conditions and process were the same as in Example 1.

[0064] Example 9: Reduction conditions, reduction atmosphere, reduction temperature, reduction time

[0065] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0066] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0067] The catalyst precursor was placed in a quartz tube furnace and reduced at 300°C for 6 h in a H2 / N2 (flow rate 50 mL / min) mixed atmosphere (H2 volume ratio 50%) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce 4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 10.

[0068] The catalyst evaluation conditions and process were the same as in Example 1.

[0069] Example 10: Reduction conditions, reduction atmosphere, reduction temperature, reduction time

[0070] Weigh 5.0 g Ce(NO3)3·6H2O, dissolve it in 100 mL deionized water, add 3.4 mol / L ammonia water to adjust the pH to 11.0, stir for 8 h to form a gel, wash with deionized water until neutral, dry at 120 °C for 12 h, and calcine at 500 °C for 4 h to obtain a carrier (XRD results show that the synthesized carrier is CeO2);

[0071] Weigh 2.0 g of the carrier, add 1 mol / L sulfuric acid at a solid-liquid ratio of 1:5, stir for 2 h, filter to obtain a solid product, dry at 120 ° C for 12 h, and calcine at 500 ° C for 4 h to obtain a catalyst precursor;

[0072] The catalyst precursor was placed in a quartz tube furnace and reduced at 400°C for 2 h in a H2 / N2 (flow rate 50 mL / min) mixed atmosphere (H2 volume ratio 90%) to obtain a partially reduced cerium oxide-supported sulfuric acid catalyst. The X-ray photoelectron spectroscopy results showed that the Ce element was Ce4+ and Ce 3+ Coexisting on the catalyst surface, Ce 3+ The relative content is 26%, recorded as catalyst 11.

[0073] The catalyst evaluation conditions and process were the same as in Example 1.

[0074] Example 11: Reaction conditions, raw materials, temperature, pressure, space velocity

[0075] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 15 wt% acrylic acid 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 ; Product analysis is the same as in Example 1.

[0076] Example 12: Reaction conditions, raw materials, temperature, pressure, space velocity

[0077] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 75 wt% acrylic acid 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 ; Product analysis is the same as in Example 1.

[0078] Example 13: Reaction conditions, raw materials, temperature, pressure, space velocity

[0079] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor phenothiazine was 0.01%, the reaction temperature was 180°C, the reaction pressure was 1.0 MPa, and the mass space velocity was 1.0 h -1 ; Product analysis is the same as in Example 1.

[0080] Example 14: Reaction conditions, raw materials, temperature, pressure, space velocity

[0081] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor p-methoxyphenol was 1%, the reaction temperature was 180°C, the reaction pressure was 1.0 MPa, and the mass space velocity was 1.0 h -1 ; Product analysis is the same as in Example 1.

[0082] Example 15: Reaction conditions, raw materials, temperature, pressure, space velocity

[0083] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 100°C, the reaction pressure was 1.0 MPa, and the mass space velocity was 1.0 h-1 ; Product analysis is the same as in Example 1.

[0084] Example 16: Reaction conditions, raw materials, temperature, pressure, space velocity

[0085] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 200°C, the reaction pressure was 1.0 MPa, and the mass space velocity was 1.0 h -1 ; Product analysis is the same as in Example 1.

[0086] Example 17: Reaction conditions, raw materials, temperature, pressure, space velocity

[0087] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 180°C, the reaction pressure was 0.1 MPa, and the mass space velocity was 1.0 h -1 ; Product analysis is the same as in Example 1.

[0088] Example 18: Reaction conditions, raw materials, temperature, pressure, space velocity

[0089] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid aqueous solution, the mass concentration of the inhibitor hydroquinone was 0.1%, the reaction temperature was 180°C, the reaction pressure was 2.0 MPa, and the mass space velocity was 1.0 h -1 ; Product analysis is the same as in Example 1.

[0090] Example 19: Reaction conditions, raw materials, temperature, pressure, space velocity

[0091] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid 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 0.5 h -1 ; Product analysis is the same as in Example 1.

[0092] Example 20: Reaction conditions, raw materials, temperature, pressure, space velocity

[0093] Catalyst 1 was used in a fixed bed tubular reactor. The raw material was 50 wt% acrylic acid 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 5 h -1 ; Product analysis is the same as in Example 1.

[0094] Table 1 below lists the reaction evaluation results of the catalyst prepared by the method of the present invention

[0095]

[0096] From Example 1 and Comparative Example 1, it can be seen that partial reduction is beneficial to improving the conversion rate of acrylic acid and the selectivity of 3-hydroxypropionic acid; from Examples 1, 2 and 3, it can be seen that the reaction activity of the catalyst synthesized using Ce(NO3)3·6H2O as raw material is slightly higher than that of Ce(SO4)2·4H2O or CeCl3·7H2O; from Examples 1, 4-7, it can be seen that with the increase of sulfuric acid concentration and the extension of immersion time, the reaction activity gradually increases, and the activity does not change much when it continues to increase; from Examples 1, 8-10, it can be seen that the reducing atmosphere, reduction temperature and reduction time have a great influence on the activity of the catalyst, and suitable reaction conditions are required; from Examples 1 and 11, 12, 19, 20, it can be seen that the lower the concentration of the reactant raw materials and the smaller the weight hourly space velocity, the higher the reaction activity; from Examples 1, 13, 14, it can be seen that the inhibitor has little effect on the conversion rate of acrylic acid, while the selectivity of 3-hydroxypropionic acid is slightly different; from Examples 1, 15-18, it can be seen that under appropriate conditions, the higher the reaction temperature and the greater the pressure, the higher the reaction activity, and the reaction efficiency does not change much when the temperature and pressure are further increased.

Claims

1. A solid superacid catalyst, comprising an active component and a carrier, wherein the active component is sulfate ion and the carrier is a partially reduced rare earth Ce oxide; the active component content is 5-50wt%, preferably 10-40wt%; the preparation of the catalyst comprises the following steps: (1) Preparation of carrier: The raw salt is prepared into an aqueous solution, the pH value of the solution is adjusted and stirred to form a gel, and the carrier is obtained after washing, drying and calcining; (2) Active component loading: adding the carrier into a sulfuric acid aqueous solution, and obtaining a catalyst precursor after impregnation, filtration, drying, and calcination; (3) Partial reduction: In a reducing atmosphere, the catalyst precursor is partially reduced to obtain a catalyst for preparing 3-hydroxypropionic acid by hydration of acrylic acid.

2. The method according to claim 1, characterized in that: In step (1), the raw salt is one or more of Ce(NO3)3·6H2O, Ce(SO4)2·4H2O or CeCl3·7H2O; the pH adjuster is ammonia water, and the pH value is 9-12, preferably 10-11; stirring for 8-16h (preferably 10-12h), washing with deionized water to neutrality; drying at 110-130℃ for 6-12h, and calcining at 400-650℃ (preferably 450-550℃) for 2-8h (preferably 4-6h) to obtain a carrier.

3. The method according to claim 1, characterized in that: In step (2), the concentration of the sulfuric acid solution used is 0.5-2 mol / L; after impregnation at room temperature for 1-10 h (preferably 4-6 h), the solid product is filtered to obtain a solid product, which is dried at 110-130° C. for 6-12 h and calcined at 400-650° C. (preferably 450-550° C.) for 2-8 h (preferably 4-6 h) to obtain a catalyst precursor.

4. The method according to claim 1, characterized in that: The reducing atmosphere in step (3) is hydrogen, or a mixture of hydrogen and an inert atmosphere gas (the inert atmosphere gas is one or more of nitrogen, argon or helium), the volume proportion of hydrogen in the mixture is 10-90% (preferably 20-60%); the reduction temperature is 250-450° C., preferably 300-400° C.; the reduction time is 1-8h, preferably 2-4h; and a partially reduced rare earth oxide-supported superacid catalyst is obtained.

5. The method according to claim 1 or 2, characterized in that: The ratio of raw material salt to water used in preparing the aqueous solution is 1.0-10 g:100 mL.

6. A solid superacid catalyst obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the solid superacid catalyst according to claim 6 in a process for catalyzing the hydration of acrylic acid to prepare 3-hydroxypropionic acid.

8. The use according to claim 7, 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 .

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