A method for synthesizing 3-hydroxypropionic acid

Abstract

The present application relates to a kind of synthesis 3-hydroxypropionic acid method, specifically to a kind of preparation 3-hydroxypropionic acid from formaldehyde and acetic acid method.The process first in the catalyst with condensation function, formaldehyde and acetic acid condensation reaction generates acrylic acid and water mixture;Then the acrylic acid and water mixture generated in situ on hydration catalyst, hydration reaction occurs to generate 3-hydroxypropionic acid.

Description

Technical Field

[0001] This invention relates to a method for the catalytic synthesis of 3-hydroxypropionic acid, specifically a method for preparing 3-hydroxypropionic acid from formaldehyde and acetic acid. Background Technology

[0002] 3-Hydroxypropionic acid is an isomer of lactic acid (2-hydroxypropionic acid). Due to the different positions of the hydroxyl groups, it is more chemically reactive. Through oxidation, dehydration, esterification, and other reactions, it can be used to synthesize a variety of important chemical substances, such as malonic acid, acrylic acid, 3-hydroxypropionic acid esters, and the polymer poly(3-hydroxypropionic acid). It can also be used as an additive and preservative in food or feed.

[0003] Large-scale production of 3-hydroxypropionic acid has not yet been reported. Its synthesis methods mainly include bio-fermentation and chemical synthesis. While bio-fermentation is environmentally friendly, it suffers from low production efficiency, cumbersome product separation, and small production scale, failing to meet the demands of the polymer market. Chemical synthesis methods for producing 3-hydroxypropionic acid mainly include: β-hydroxypropionitrile acidification, 1,3-propanediol / propenol / 3-hydroxypropanal oxidation, vinyl acetate carbonylation, and acrylic acid hydration.

[0004] β-Hydroxypropionitrile acidification method: Ethylene reacts with Cl2 to form vinyl chloride, which then undergoes addition with water and substitution with sodium cyanide to form β-hydroxypropionitrile; β-hydroxypropionitrile then reacts with water to form 3-hydroxypropionic acid. This route uses highly toxic sodium cyanide, therefore it is only suitable for small-scale laboratory synthesis and separation, and not for large-scale industrial production.

[0005] 1,3-Propanediol / Allyl alcohol / 3-Hydroxypropanal oxidation method: Supported noble metal catalysts are widely used in the catalytic oxidation of alcohols and aldehydes to prepare carboxylic acids. The production of 3-hydroxypropionic acid using 1,3-propanediol as a raw material has high raw material costs, and large-scale production technology for 1,3-propanediol is monopolized by foreign companies; domestic technology is under continuous development and research. Degussa reports that using 3-hydroxypropanal as a raw material (3-hydroxypropanal is usually obtained by the hydration of acrolein, which is an intermediate in the oxidation of propylene to acrylic acid) offers milder reaction conditions compared to 1,3-propanediol, but the oxidation process is difficult to control; even small changes can lead to over-oxidation and the formation of malonic acid.

[0006] Vinyl acetate carbonylation method: Vinyl acetate and other vinyl unsaturated compounds undergo carbonylation with CO and H₂O in the presence of Pd complexes to generate hydroxypropionate (a mixture of 3-hydroxy and 2-hydroxy acids), which is then hydrolyzed by alkaline catalysis to produce a mixture of 3-hydroxypropionic acid and lactic acid. In this route, the raw material vinyl acetate is toxic, the carbonylation reaction conditions are harsh, the catalyst cost is high, and the products 3-hydroxypropionic acid and lactic acid have similar properties, making separation difficult.

[0007] Acrylic acid hydration method: Wanhua Chemical (CN2019112225946.7) reported a method for preparing 3-hydroxypropionic acid by catalyzing the hydration of acrylic acid using β-molecular sieve catalysts modified with acids such as maleic acid and citric acid. The preparation of 3-hydroxypropionic acid from acrylic acid via hydration requires less sophisticated equipment.

[0008] Although biosynthesis is the primary method reported for the preparation of 3-hydroxypropionic acid, fermentation processes are not yet mature and the preparation time is relatively long. Chemical synthesis, on the other hand, is gradually attracting attention due to its advantages such as relatively simple separation and purification, low cost, and mild conditions. Summary of the Invention

[0009] The problem this invention aims to solve is to provide a method for synthesizing 3-hydroxypropionic acid from inexpensive and readily available formaldehyde and acetic acid. 3-hydroxypropionic acid is prepared via condensation-hydration using a suitable catalytic system and process.

[0010] The technical solution is as follows:

[0011] Formaldehyde or its aqueous mixture with acetic acid is vaporized and diluted with an inert gas or not, and then undergoes a condensation reaction in a first-stage reactor on a catalyst with condensation function to produce a mixture of acrylic acid and water. The mixture of acrylic acid and water is obtained by separation from the reaction mixture. Then, the mixture of acrylic acid and water, or by partially separating water or by adding water to adjust the molar ratio of acrylic acid to water, is vaporized and diluted with an inert gas or not, and then undergoes a hydration reaction in a second-stage reactor on a catalyst with hydration function to produce 3-hydroxypropionic acid.

[0012] Provide one solution:

[0013] In the mixture following the first reactor stage, acrylic acid and water may be partially separated or not separated at all.

[0014] Provide one solution:

[0015] The formaldehyde or its aqueous mixture includes: trioxymethylene, paraoxymethylene, and a 30-99 wt% formaldehyde aqueous mixture;

[0016] The molar ratio of formaldehyde to acetic acid in the formaldehyde or its aqueous mixture is 5:1 to 1:5.

[0017] The inert atmosphere includes: N2, Ar, and He;

[0018] The inert gas accounts for 10-80% of the total gas volume;

[0019] The catalyst with condensation function is one or more of the following: tantalum oxyphosphate, niobium oxyphosphate, niobium isomorphically substituted tantalum oxyphosphate, tantalum isomorphically substituted niobium oxyphosphate, and their supported catalysts.

[0020] The loading of the active component in the supported catalyst is 5-50 wt%.

[0021] The support for the supported catalyst includes one or a mixture of two or more of SiO2, Al2O3, TiO2, and ZrO2 in any proportion;

[0022] The condensation reaction temperature is 250-450℃;

[0023] The condensation reaction pressure is 0.5-30 atm;

[0024] The mass hourly space velocity (HSV) of formaldehyde and acetic acid on the catalyst is 0.2-4 h⁻¹. -1 ;

[0025] The molar ratio of acrylic acid to water in the mixture of acrylic acid and water is 1:1 to 1:6.

[0026] The catalyst with hydration function is: SO4 2- / HfO2、SO4 2- / ZrO2、SO4 2- / TiO2、SO4 2- / ZrO2-HfO2、SO4 2- / Fe2O3、SO4 2- / SnO2、SO4 2- / CeO2、SO4 2- One or more of / γ-Al2O3;

[0027] The hydration reaction temperature is 120-350℃;

[0028] The hydration reaction pressure is 0.5-30 atm.

[0029] The mass hourly space velocity (HWHV) of acrylic acid on the catalyst is 0.2-4 h⁻¹. -1 .

[0030] Provide one solution:

[0031] The catalyst with the condensation function is prepared by dissolving potassium niobate or potassium tantalate to form a homogeneous solution, then adding a mixed acid solution of nitric acid and phosphoric acid with a molar ratio of 1:1 until more than 95% of Nb and tantalum metal ions are precipitated in the solution. The precipitated suspension is then filtered and washed until the filtrate is neutral. The precipitate is dried and then fully calcined in air or an inert atmosphere to 500-800°C to obtain niobium oxyphosphate or tantalum oxyphosphate.

[0032] Using a mixed solution of potassium niobate and potassium tantalate, niobium isomorphously substituted tantalum oxyphosphate or tantalum isomorphically substituted niobium oxyphosphate can be prepared by the above method.

[0033] The preparation method of the supported catalyst is as follows: after dissolving potassium niobate or potassium tantalate to form a homogeneous solution, a specific mass of support is added according to the loading amount, and then the process is continued to obtain the supported condensation catalyst.

[0034] Provide one solution:

[0035] The preparation method of the hydration-functional catalyst is as follows: one or more of the corresponding soluble metal salts of Ti, Zr, Hf, Fe, Sn, Ce, and Al are dissolved in water or ethanol; ammonia, urea, NaOH, or KOH are added as precipitants, the amount of which is sufficient to precipitate more than 90% of the metal ions in the metal salt solution; simultaneously, (NH4)2SO4, Na2SO4, or K2SO4 solution is added, the amount of SO4 in the solution is... 2- The ion concentration is 0.5-4.0 mol / L; the resulting precipitate suspension is aged at 30-80℃ for 6-24 h, then filtered, washed to remove impurity ions, and then dried and fully calcined in air or nitrogen atmosphere at 400-800℃.

[0036] Beneficial technical effects

[0037] This invention achieves the synthesis of high-value-added 3-hydroxypropionic acid by organically combining innovative catalyst design with reaction process, using inexpensive, readily available, and simple raw materials such as formaldehyde and acetic acid.

[0038] Figure 1 Brief reaction process flow diagram. Detailed Implementation

[0039] To provide a more detailed description of the present invention, several specific implementation examples are given below, but the present invention is not limited to these embodiments.

[0040] according to Figure 1 The reaction process can be briefly described as follows: The vaporized formaldehyde-acetic acid mixture undergoes a condensation reaction on a catalyst with condensation function in the first reactor. The reacted material is separated to obtain a mixture of acrylic acid and water, which is then introduced into a hydration reactor at a controlled temperature. Water is partially separated to ensure the appropriate molar ratio of acrylic acid to water. Finally, in the second reactor, the mixture of acrylic acid and water undergoes a hydration reaction on a catalyst with hydration function to generate 3-hydroxypropionic acid, which is then separated to obtain 3-hydroxypropionic acid.

[0041] Example 1

[0042] Potassium niobate was dissolved in water to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise to the solution. The Nb ion concentration was monitored until more than 95% of the Nb ions in the solution were precipitated. The precipitate suspension was then filtered, and the solid was washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 500°C until the mass loss was stable, thus obtaining niobium oxyphosphate.

[0043] Zirconium nitrate was dissolved in water (10 g / L), and a 26 wt% ammonia solution was gradually added while monitoring the Zr ion concentration until more than 90% of the Zr ions were precipitated. Simultaneously, (NH4)2SO4 was added to ensure the SO42- concentration in the solution was within acceptable limits. 2- The ion concentration was 0.5 mol / L; the resulting precipitate was aged at 30℃ for 6 hours, then filtered, washed to remove impurity ions, and then fully calcined in air at 400℃ until the mass loss stabilized, thus obtaining SO4. 2- / ZrO2.

[0044] A mixture of paraformaldehyde and acetic acid, formed by a molar ratio of 1 / 5, is vaporized and then undergoes a condensation reaction in the first-stage reactor on a condensation catalyst, niobium oxyphosphate, at 250°C and 0.5 atm. The feed rate is controlled to ensure that the mass hourly space velocity (WHSV) of formaldehyde and acetic acid on the catalyst is 0.2 h⁻¹. -1 The mixture of acrylic acid and water is obtained by separating it from the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:6. After gasification, it is then reacted in a second-stage reactor at 120°C and 0.5 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on ZrO2 to generate 3-hydroxypropionic acid. The mass hourly space velocity (H₂O₅) of acrylic acid on the catalyst is maintained at 0.2 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0045] Example 2

[0046] Potassium tantalate was dissolved in water to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise. The concentration of Ta ions was monitored until more than 95% of the Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 800°C until the mass loss was stable, thus obtaining tantalum oxyphosphate.

[0047] Hafnium nitrate was dissolved in water (10 g / L), and urea was gradually added while monitoring the Hf ion concentration until more than 90% of the Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure the SO₄²⁻ concentration in the solution was high. 2-The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / HfO2.

[0048] A mixture of paraformaldehyde and acetic acid in a 1 / 1 molar ratio is vaporized and diluted with N2 (N2 comprising 10% of the total gas volume). In the first-stage reactor, a condensation reaction occurs on a condensation catalyst, tantalum oxyphosphate, at 300°C and 1 atm. The feed rate is controlled to ensure a mass hourly space velocity (MSV) of 1 h⁻¹ for both formaldehyde and acetic acid on the catalyst. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:3. After gasification, and dilution with N2 (N2 accounting for 10% of the total gas volume), it is reacted in a second-stage reactor at 180°C and 10 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on HfO2 to generate 3-hydroxypropionic acid. The mass hourly space velocity (MHSV) of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0049] Example 3

[0050] Potassium niobate and potassium tantalate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise to the solution. The concentrations of Nb and Ta ions were monitored until more than 95% of Nb and Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 600°C until the mass loss was stable, thus obtaining niobium isomorphously substituted tantalum oxyphosphate.

[0051] Dissolve ferric nitrate in water (200 g / L), gradually add NaOH, and monitor the Fe ion concentration until more than 90% of the Fe ions are precipitated. Simultaneously add K₂SO₄ to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 4 mol / L; the resulting precipitate was aged at 60℃ for 24 h, then filtered, washed to remove impurity ions, and then fully calcined in air at 800℃ until the mass loss stabilized, thus obtaining SO4. 2- / Fe2O3.

[0052] A mixture of 30 wt% formaldehyde aqueous solution and acetic acid in a molar ratio of 5 / 1 was vaporized and diluted with N2 (N2 comprising 50% of the total gas volume). In the first-stage reactor, a condensation reaction was carried out on a niobium isomorphously substituted tantalum oxyphosphate catalyst at 350 °C and 10 atm. The feed rate was controlled to ensure that the mass hourly space velocity (H₂O) of formaldehyde and acetic acid on the catalyst was 2 h⁻¹. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization, and diluted with N2 (N2 accounting for 50% of the total gas volume), it is reacted in a second-stage reactor at 250°C and 20 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on Fe2O3 to generate 3-hydroxypropionic acid. The mass space velocity (MSV) of acrylic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0053] Example 4

[0054] Potassium tantalate was dissolved in water to form a homogeneous saturated aqueous solution. The amount of Al2O3 support added was calculated based on the tantalum oxyphosphate yield obtained in Example 2, ensuring the tantalum oxyphosphate loading was maintained at 5 wt%. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise, and the Ta ion concentration was monitored until more than 95% of the Ta ions in the solution precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. After drying, the precipitate was calcined in air at 800°C until the mass loss stabilized, yielding 5 wt% tantalum oxyphosphate / Al2O3.

[0055] Similarly, supported tantalum oxyphosphate catalysts with different supports (including SiO2, TiO2, ZrO2) and different loading amounts (5-50 wt%) can be prepared.

[0056] Dissolve cerium nitrate in water (300 g / L), gradually add KOH, and monitor the Ce ion concentration until more than 90% of the Ce ions are precipitated. Simultaneously add K₂SO₄ to ensure the SO₄²⁻ concentration in the solution is high. 2- The ion concentration was 4 mol / L; the resulting precipitate was aged at 60℃ for 24 h, then filtered, washed to remove impurity ions, and then fully calcined in air at 800℃ until the mass loss stabilized, thus obtaining SO4. 2- / CeO2.

[0057] Similarly, hydrated catalysts with different supports (including SnO2, Al2O3, TiO2, and ZrO2) can be prepared using tin chloride, aluminum nitrate, and titanium chloride.

[0058] A mixture of 50 wt% formaldehyde aqueous solution and acetic acid at a molar ratio of 1 / 2, after being vaporized and diluted with Ar (Ar accounting for 80% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 450 °C and 30 atm on a condensation catalyst of 5 wt% tantalum oxyphosphate / Al₂O₃. The mass hourly space velocity (WHSV) of formaldehyde and acetic acid on the catalyst is maintained at 4 h⁻¹ by controlling the feed rate. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization, and diluted with N2 (N2 accounting for 50% of the total gas volume), it is reacted in a second-stage reactor at 350°C and 30 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on CeO2 to generate 3-hydroxypropionic acid. The mass space velocity (MSV) of acrylic acid on the catalyst is maintained at 4 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0059] Example 5

[0060] Potassium tantalate and potassium niobate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Simultaneously, the amount of ZrO2 support added was calculated based on the theoretical yield of tantalomorphically substituted niobium oxyphosphate, maintaining the loading of tantalomorphically substituted niobium oxyphosphate at 50 wt%. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise, monitoring the concentrations of Ta and Nb ions until more than 95% of Ta and Nb ions precipitated in the solution. The precipitate suspension was then filtered and washed until the filtrate was neutral. After drying, the precipitate was calcined in air at 600°C until the mass loss stabilized, yielding tantalomorphically substituted niobium oxyphosphate / ZrO2.

[0061] Zirconium nitrate and hafnium nitrate were dissolved in water at a molar ratio of 1 / 1 (total concentration of metal nitrates: 10 g / L). 26 wt% ammonia solution was gradually added, monitoring the concentrations of Zr and Hf ions, until over 90% of the Zr and Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / ZrO2-HfO2.

[0062] A mixture of 99 wt% formaldehyde aqueous solution and acetic acid at a molar ratio of 1 / 2, after being vaporized and diluted with N2 (N2 accounting for 50% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 350 °C and 5 atm on a condensation catalyst of tantalum isomorphously substituted niobium oxyphosphate / ZrO2. The mass space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 The mixture of acrylic acid and water is obtained by separating it from the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:3. After gasification, it is then reacted in a second-stage reactor at 200°C and 15 atm with SO4 catalyst having hydration function. 2- A hydration reaction occurs on ZrO2-HfO2 to generate 3-hydroxypropionic acid. The mass space velocity of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0063] Example 6

[0064] Potassium tantalate and potassium niobate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Simultaneously, the amount of ZrO2 support added was calculated based on the theoretical yield of tantalomorphically substituted niobium oxyphosphate, maintaining the loading of tantalomorphically substituted niobium oxyphosphate at 50 wt%. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise, monitoring the concentrations of Ta and Nb ions until more than 95% of Ta and Nb ions precipitated in the solution. The precipitate suspension was then filtered and washed until the filtrate was neutral. After drying, the precipitate was calcined in air at 600°C until the mass loss stabilized, yielding tantalomorphically substituted niobium oxyphosphate / ZrO2.

[0065] Zirconium nitrate and hafnium nitrate were dissolved in water at a molar ratio of 1 / 1 (total concentration of metal nitrates: 10 g / L). 26 wt% ammonia solution was gradually added, monitoring the concentrations of Zr and Hf ions, until over 90% of the Zr and Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / ZrO2-HfO2.

[0066] A mixture of 99 wt% formaldehyde aqueous solution and acetic acid at a molar ratio of 1 / 4, after being vaporized and diluted with N2 (N2 comprising 50% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 350 °C and 5 atm on a condensation catalyst of tantalum isomorphously substituted niobium oxyphosphate / ZrO2. The mass space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 The mixture of acrylic acid and water is obtained by separating it from the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:5. After gasification, it is then reacted in a second-stage reactor at 200°C and 15 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on ZrO2-HfO2 to generate 3-hydroxypropionic acid. The mass space velocity of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0067] Example 7

[0068] Potassium tantalate and potassium niobate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Simultaneously, the amount of ZrO2 support added was calculated based on the theoretical yield of tantalomorphically substituted niobium oxyphosphate, maintaining the loading of tantalomorphically substituted niobium oxyphosphate at 50 wt%. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise, monitoring the concentrations of Ta and Nb ions until more than 95% of Ta and Nb ions precipitated in the solution. The precipitate suspension was then filtered and washed until the filtrate was neutral. After drying, the precipitate was calcined in air at 600°C until the mass loss stabilized, yielding tantalomorphically substituted niobium oxyphosphate / ZrO2.

[0069] Zirconium nitrate and hafnium nitrate were dissolved in water at a molar ratio of 1 / 1 (total concentration of metal nitrates: 10 g / L). 26 wt% ammonia solution was gradually added, monitoring the concentrations of Zr and Hf ions, until over 90% of the Zr and Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / ZrO2-HfO2.

[0070] A mixture of 99 wt% formaldehyde aqueous solution and acetic acid at a molar ratio of 1 / 5, after being vaporized and diluted with N2 (N2 accounting for 50% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 350 °C and 5 atm on a condensation catalyst of tantalum isomorphously substituted niobium oxyphosphate / ZrO2. The mass space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 The mixture of acrylic acid and water is obtained by separating it from the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:6. After gasification, it is then reacted in a second-stage reactor at 200°C and 15 atm with SO4 catalyst having hydration function. 2- A hydration reaction occurs on ZrO2-HfO2 to generate 3-hydroxypropionic acid. The mass space velocity of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0071] Example 8

[0072] Potassium tantalate was dissolved in water to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise. The concentration of Ta ions was monitored until more than 95% of the Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 800°C until the mass loss was stable, thus obtaining tantalum oxyphosphate.

[0073] Hafnium nitrate was dissolved in water (10 g / L), and urea was gradually added while monitoring the Hf ion concentration until more than 90% of the Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure the SO₄²⁻ concentration in the solution was high. 2- The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / HfO2.

[0074] A mixture of paraformaldehyde and acetic acid in a 1 / 1 molar ratio, after being vaporized and diluted with N2 (N2 comprising 10% of the total gas volume), undergoes a condensation reaction in the first-stage reactor over a condensation catalyst, tantalum oxyphosphate, at 250°C and 1 atm. The mass hourly space velocity (WHSV) of formaldehyde and acetic acid over the catalyst is controlled to ensure a WHSV of 1 h⁻¹. -1The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:3. After gasification and dilution with N2 (N2 accounting for 10% of the total gas volume), it is reacted in a second-stage reactor at 180°C and 0.5 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on HfO2 to generate 3-hydroxypropionic acid. The mass hourly space velocity (MHSV) of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0075] Example 9

[0076] Potassium tantalate was dissolved in water to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise. The concentration of Ta ions was monitored until more than 95% of the Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 800°C until the mass loss was stable, thus obtaining tantalum oxyphosphate.

[0077] Hafnium nitrate was dissolved in water (10 g / L), and urea was gradually added while monitoring the Hf ion concentration until more than 90% of the Hf ions were precipitated. Simultaneously, Na₂SO₄ was added to ensure the SO₄²⁻ concentration in the solution was high. 2- The ion concentration was 2 mol / L; the resulting precipitate was aged at 80℃ for 12 h, then filtered, washed to remove impurity ions, and then fully calcined at 600℃ in a nitrogen atmosphere until the mass loss stabilized, thus obtaining SO4. 2- / HfO2.

[0078] A mixture of paraformaldehyde and acetic acid in a 1 / 1 molar ratio, after being vaporized and diluted with N2 (N2 comprising 10% of the total gas volume), undergoes a condensation reaction in the first-stage reactor over a condensation catalyst, tantalum oxyphosphate, at 450°C and 1 atm. The mass hourly space velocity (WHSV) of formaldehyde and acetic acid over the catalyst is controlled to ensure a WHSV of 1 h⁻¹. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:3. After gasification and dilution with N2 (N2 accounting for 10% of the total gas volume), it is reacted in a second-stage reactor at 180°C and 30 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on HfO2 to generate 3-hydroxypropionic acid. The mass hourly space velocity (MHSV) of acrylic acid on the catalyst is maintained at 1 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0079] Example 10

[0080] Potassium niobate and potassium tantalate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise to the solution. The concentrations of Nb and Ta ions were monitored until more than 95% of Nb and Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 500°C until the mass loss was stable, thus obtaining niobium isomorphously substituted tantalum oxyphosphate.

[0081] Dissolve ferric nitrate in water (200 g / L), gradually add NaOH, and monitor the Fe ion concentration until more than 90% of the Fe ions are precipitated. Simultaneously add K₂SO₄ to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 4 mol / L; the resulting precipitate was aged at 30℃ for 24 h, then filtered, washed to remove impurity ions, and then fully calcined in air at 800℃ until the mass loss stabilized, thus obtaining SO4. 2- / Fe2O3.

[0082] A mixture of 30 wt% formaldehyde aqueous solution and acetic acid in a molar ratio of 5 / 1 was vaporized and diluted with N2 (N2 comprising 50% of the total gas volume). In the first-stage reactor, a condensation reaction was carried out on a niobium isomorphously substituted tantalum oxyphosphate catalyst at 350 °C and 10 atm. The feed rate was controlled to ensure that the mass hourly space velocity (H₂O) of formaldehyde and acetic acid on the catalyst was 2 h⁻¹. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization, and diluted with N2 (N2 accounting for 50% of the total gas volume), it is reacted in a second-stage reactor at 250°C and 20 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on Fe2O3 to generate 3-hydroxypropionic acid. The mass space velocity (MSV) of acrylic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0083] Example 11

[0084] Potassium niobate and potassium tantalate were dissolved in water at a metal molar ratio of 1 / 9 to form a homogeneous saturated aqueous solution. Then, a mixed solution of 68 wt% nitric acid and 85 wt% phosphoric acid with a molar ratio of 1:1 was added dropwise to the solution. The concentrations of Nb and Ta ions were monitored until more than 95% of Nb and Ta ions in the solution were precipitated. The precipitate suspension was then filtered and washed until the filtrate was neutral. The precipitate was dried and then calcined in air at 800°C until the mass loss was stable, thus obtaining niobium isomorphously substituted tantalum oxyphosphate.

[0085] Dissolve ferric nitrate in water (200 g / L), gradually add NaOH, and monitor the Fe ion concentration until more than 90% of the Fe ions are precipitated. Simultaneously add K₂SO₄ to ensure sufficient SO₄²⁻ concentration in the solution. 2- The ion concentration was 4 mol / L; the resulting precipitate was aged at 80℃ for 24 h, then filtered, washed to remove impurity ions, and then fully calcined in air at 800℃ until the mass loss stabilized, thus obtaining SO4. 2- / Fe2O3.

[0086] A mixture of 30 wt% formaldehyde aqueous solution and acetic acid in a molar ratio of 5 / 1 was vaporized and diluted with N2 (N2 comprising 50% of the total gas volume). In the first-stage reactor, a condensation reaction was carried out on a niobium isomorphously substituted tantalum oxyphosphate catalyst at 350 °C and 10 atm. The feed rate was controlled to ensure that the mass hourly space velocity (H₂O) of formaldehyde and acetic acid on the catalyst was 2 h⁻¹. -1 The mixture of acrylic acid and water is obtained by separating the reaction mixture, or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization, and diluted with N2 (N2 accounting for 50% of the total gas volume), it is reacted in a second-stage reactor at 250°C and 20 atm with a hydration catalyst, SO4. 2- A hydration reaction occurs on Fe2O3 to generate 3-hydroxypropionic acid. The mass space velocity (MSV) of acrylic acid on the catalyst is maintained at 2 h⁻¹ by controlling the feed rate. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0087] Comparative Example 1

[0088] A mixture of 50 wt% formaldehyde aqueous solution and acetic acid (molar ratio 1 / 2), after being vaporized and diluted with Ar (Ar accounting for 80% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 450 °C and 30 atm on a condensation catalyst of 5 wt% V₂O₅ / Al₂O₃. The mass hourly space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 4 h⁻¹ by controlling the feed rate. -1Acrylic acid and water were obtained by separating the reaction mixture from the reaction mixture, or by partially separating water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization, the mixture was diluted with N2 (N2 accounting for 50% of the total gas volume) and then subjected to a hydration reaction on HMCM-48 at 350°C and 30 atm to produce 3-hydroxypropionic acid. The feed rate was controlled to ensure that the mass hourly space velocity (MSV) of acrylic acid on the catalyst was 4 h⁻¹. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0089] Comparative Example 2

[0090] A mixture of 50 wt% formaldehyde aqueous solution and acetic acid (molar ratio 1 / 2), after being vaporized and diluted with Ar (Ar accounting for 80% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 450 °C and 30 atm on a condensation catalyst of 5 wt% P₂O₅ / Al₂O₃. The mass hourly space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 4 h⁻¹ by controlling the feed rate. -1 A mixture of acrylic acid and water was obtained from the reaction mixture, either by separating the water or by partially separating the water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After vaporization and dilution with N2 (N2 accounting for 50% of the total gas volume), the mixture underwent a hydration reaction on HZSM-5 at 350°C and 30 atm to produce 3-hydroxypropionic acid. The feed rate was controlled to ensure that the mass hourly space velocity (MSV) of acrylic acid on the catalyst was 4 h⁻¹. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0091] Comparative Example 3

[0092] A mixture of 50 wt% formaldehyde aqueous solution and acetic acid at a molar ratio of 1 / 2, after being vaporized and diluted with Ar (Ar accounting for 80% of the total gas volume), undergoes a condensation reaction in the first-stage reactor at 450 °C and 30 atm on a condensation catalyst of 5 wt% V₂O₅-5 wt% P₂O₅ / Al₂O₃. The mass space velocity (MSV) of formaldehyde and acetic acid on the catalyst is maintained at 4 h⁻¹ by controlling the feed rate. -1 Acrylic acid and water were obtained by separating the reaction mixture from the reaction mixture, or by partially separating water or by adding water to adjust the molar ratio of acrylic acid to water to 1:1. After gasification and dilution with N2 (N2 accounting for 50% of the total gas volume), the mixture underwent a hydration reaction on SAPO-34 at 350°C and 30 atm to produce 3-hydroxypropionic acid. The feed rate was controlled to ensure that the mass hourly space velocity (MHSV) of acrylic acid on the catalyst was 4 h⁻¹. -1 Conversion and selectivity were calculated using chromatographic analysis. See Table 1.

[0093] Table 1 Reaction Evaluation Results

[0094]

[0095] From Examples 5-7, it can be seen that: in the first reactor, the lower the molar ratio of formaldehyde to acetic acid, the more favorable the conversion is, and the selectivity can be maintained at a similar level; in the second reactor, the lower the molar ratio of acrylic acid to water, the more favorable the conversion is, and the selectivity can be maintained at a similar level.

[0096] From Examples 2, 8, and 9, it can be seen that: in the first reactor, the lower the reaction temperature, the lower the conversion rate, while the selectivity remains the same; the higher the reaction temperature, the higher the conversion rate, but the lower the selectivity. In the second reactor, the lower the reaction pressure, the lower the conversion rate, while the selectivity remains the same; the higher the reaction pressure, the higher both the conversion rate and the selectivity.

[0097] Examples 3, 10, and 11 show that: calcination during the preparation of condensation catalysts requires a moderate calcination temperature; and aging during the preparation of hydration catalysts requires a moderately suitable temperature.

[0098] From Example 4 and Comparative Examples 1, 2, and 3, it can be seen that: V2O5 / Al2O3, P2O5 / Al2O 3、 V2O5-P2O5 / Al2O3 was used as a condensation catalyst, while HMCM-48, HZSM-5, and SAPO-34 were used as hydration catalysts, but their activity was poor under the stated reaction conditions.

Claims

1. A method for synthesizing 3-hydroxypropionic acid, characterized in that: Formaldehyde or its aqueous mixture with acetic acid is vaporized and then diluted with an inert atmosphere or without dilution. In the first stage reactor, a condensation reaction occurs on a catalyst with condensation function to produce a mixture of acrylic acid and water. The mixture of acrylic acid and water is obtained by separating the reaction mixture from the reaction mixture. Then, the mixture of acrylic acid and water, either by partially separating water or by adding water to adjust the molar ratio of acrylic acid to water, is vaporized and then diluted with an inert gas or without dilution. In the second stage reactor, a hydration reaction occurs on a catalyst with hydration function to produce 3-hydroxypropionic acid. The catalyst with condensation function is one or more of tantalum oxyphosphate, niobium oxyphosphate, and their supported catalysts; the supported catalyst has one or more of tantalum oxyphosphate and niobium oxyphosphate as the active component. The catalyst with hydration function is: SO4 2- / HfO2、SO4 2- / ZrO2、SO4 2- / TiO2、SO4 2- / ZrO2-HfO2、SO4 2- / Fe2O3、SO4 2- / SnO2、SO4 2- / CeO2、SO4 2- One or more of γ-Al2O3; The formaldehyde or its aqueous mixture thereof is one or more of the following: trioxymethylene, paraoxymethylene, and a 30-99 wt% aqueous mixture of formaldehyde; The molar ratio of formaldehyde to acetic acid in the formaldehyde or its aqueous mixture is 5:1 to 1:

5. The catalyst with condensation function is one or more of tantalum oxyphosphate, niobium oxyphosphate, and their supported catalysts. The supported catalyst uses one or two of tantalum oxyphosphate and niobium oxyphosphate as active components, and the loading of the active component in the supported catalyst is 5-50 wt%. The support for the supported catalyst is one of SiO2, Al2O3, TiO2, and ZrO2, or a mixture of two or more of them in any proportion; The condensation reaction temperature is 250-450 ℃; The condensation reaction pressure is 0.5-30 atm; The mass hourly space velocity (HSV) of formaldehyde and acetic acid on the catalyst is 0.2-4 h⁻¹. -1 .

2. The method according to claim 1, characterized in that: In the mixture following the first reactor stage, acrylic acid and water may be partially separated or not separated at all.

3. The method according to claim 1, characterized in that: The inert atmosphere includes one or more of N2, Ar, and He; The inert gas accounts for 10-80% of the total gas volume.

4. The method according to claim 1, 2, or 3, characterized in that: The molar ratio of acrylic acid to water in the mixture of acrylic acid and water is 1:1 to 1:

6. The catalyst with hydration function is: SO4 2- / HfO2、SO4 2- / ZrO2、SO4 2- / TiO2、SO4 2- / ZrO2-HfO2、SO4 2- / Fe2O3、SO4 2- / SnO2、SO4 2- / CeO2、SO4 2- One or more of / γ-Al2O3; The hydration reaction temperature is 120-350 ℃; The hydration reaction pressure is 0.5-30 atm; The mass space velocity of acrylic acid on the catalyst is: 0.2-4 h -1 .

5. The method according to claim 1, characterized in that: SO4 in catalysts with hydration function 2- The mass content depends on the SO4 content on its loading carrier. 2- It depends on the saturation adsorption capacity of the ions.

6. The method according to claim 1, characterized in that: A. The preparation method of the catalyst with condensation function is as follows: dissolve potassium niobate or potassium tantalate to form a homogeneous solution, then add a mixed acid solution of nitric acid and phosphoric acid with a molar ratio of 1:1 dropwise until more than 95% of Nb and tantalum metal ions are precipitated in the solution. Then filter and wash the above precipitate suspension until the filtrate is neutral, dry the precipitate, and calcine it fully in air and / or an inert atmosphere to 500-800℃ to obtain niobium oxyphosphate or tantalum oxyphosphate; the inert atmosphere is one or more of N2, Ar, and He. Alternatively, method C, the preparation method of the supported catalyst is as follows: after dissolving potassium niobate and / or potassium tantalate to form a homogeneous solution, the required mass of support is added according to the loading amount, and then the supported condensation catalyst is prepared by following the same process and conditions as method A above.

7. The method according to claim 1, 5, or 6, characterized in that: The preparation method of the hydration catalyst is as follows: one or more of the corresponding soluble metal salts selected from Ti, Zr, Hf, Fe, Sn, Ce, and Al are dissolved in water and / or ethanol. One or more precipitants selected from 28wt% ammonia, urea, NaOH, or KOH are added, with the amount of precipitant sufficient to precipitate more than 90% of the metal ions in the metal salt solution. Simultaneously, one or more of (NH4)2SO4, Na2SO4, or K2SO4 are added to reduce the SO42- content in the solution. 2- The ion concentration is 0.5-4.0 mol / L; the resulting precipitate suspension is aged at 30-80℃ for 6-24 h, then filtered, washed to remove impurity ions, and then dried and fully calcined in air and / or nitrogen atmosphere at 400-800℃.

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