A method for preparing hydroxyacetone by liquid-phase catalytic oxidation of 1,2-propanediol.

Abstract

This invention belongs to the field of catalysis technology, and specifically relates to a method for the liquid-phase catalytic oxidation of 1,2-propanediol to prepare hydroxyacetone. The catalyst is an M-Zr-UiO-66 catalyst, where the metal M is selected from Fe, Cr, Cu, and Co, and the ligand is terephthalic acid. The catalyst preparation and catalytic reaction process of this invention are simple, the catalyst is reusable, and it is environmentally friendly. Using the catalyst and corresponding catalytic conditions of this invention, a good yield of hydroxyacetone can be obtained under relatively mild conditions. The main product is hydroxyacetone, and the byproduct is acetone. The selectivity of the main product can reach over 80%, and the conversion rate of 1,2-propanediol can reach over 14%.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, and specifically relates to a method for preparing hydroxyacetone by liquid-phase catalytic oxidation of 1,2-propanediol. Background Technology

[0002] 1,2-Propanediol, as a renewable biomass derivative, is facing problems of inefficient utilization and long-term overcapacity due to industrial development demands. Its highly reactive hydroxyl functional group can be directly used to synthesize high-value chemicals such as hydroxyacetone (HA, also known as acetyl alcohol), glyoxal, lactic acid, and pyruvic acid. Hydroxyacetone, as an intermediate product in the oxidation process of 1,2-propanediol, has a higher price than some of the over-oxidation and decomposition products such as pyruvaldehyde, pyruvic acid, formic acid, and acetic acid. Furthermore, hydroxyacetone has wide applications in the pharmaceutical, food, textile, cosmetic, and polymer industries. Traditional hydroxyacetone production processes mostly employ non-catalytic oxidation methods, which not only have low selectivity for hydroxyacetone but also require complex purification steps.

[0003] Recent research has focused on the selective oxidation of propylene glycol using environmentally friendly oxidants and easily recyclable catalysts in liquid-phase oxidation. Wang Huijie et al. (authorized publication number: CN110813364B) proposed using Pd-based bimetallic nanoparticles as a catalyst and air as the oxidant for the catalytic oxidation of 1,2-propanediol in alkaline solution; however, the main product was pyruvic acid, with low hydroxyacetone content. Based on literature reports, most catalysts for the selective oxidation of 1,2-propanediol are currently noble metal catalysts such as Pd and Au, which are not only costly but also prone to aggregation and deactivation over long reaction times, limiting their large-scale application. Therefore, developing more economical, green, and efficient catalysts and processes for the selective oxidation of 1,2-propanediol is of significant practical importance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing hydroxyacetone from 1,2-propanediol as a raw material, which solves the problems of complex production processes and low selectivity of hydroxyacetone by using a non-precious metal catalyst.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing hydroxyacetone by liquid-phase catalytic oxidation of 1,2-propanediol, using an M-Zr-UiO-66 bimetallic organic framework catalyst, wherein the metal M is selected from Fe, Cr, Cu, and Co, and the ligand is terephthalic acid.

[0007] 1,2-Propanediol, a catalyst, and an oxidant are added to an organic solvent, and the mixture is reacted at 20-75°C for 1-4 hours to obtain the product hydroxyacetone.

[0008] The preferred reaction temperature is 45℃.

[0009] The mass ratio of 1,2-propanediol to catalyst is 1:0.03-0.1.

[0010] The oxidant is calculated as 30 wt% hydrogen peroxide, and the mass ratio of 1,2-propanediol to the oxidant is 1:1-5.

[0011] The organic solvent is acetonitrile, acetone, acetic acid, or N,N-dimethylformamide, and the mass ratio of 1,2-propanediol to the organic solvent is 1:5-20. Acetonitrile is the most preferred organic solvent.

[0012] Preferably, the Zr / M molar ratio in the catalyst is 2-10:1, and more preferably 5:1.

[0013] The catalyst zirconium source is zirconium nitrate or zirconium chloride, and the salt of the second metal M can be selected from one of ferric nitrate, ferric chloride, chromium nitrate, chromium chloride, copper nitrate, copper chloride, cobalt nitrate, and cobalt chloride. Cr is preferred as the second metal M.

[0014] Specifically, a method for preparing hydroxyacetone by liquid-phase catalytic oxidation of 1,2-propanediol employs a Cr-Zr-UiO-66 bimetallic organic framework catalyst, with terephthalic acid as the ligand and a Zr / Cr molar ratio of 5:1. 1,2-propanediol, the catalyst, and the oxidant are added to the organic solvent acetonitrile, and the reaction is carried out at 45°C for 1-4 hours to obtain the product hydroxyacetone.

[0015] Bimetallic organic framework catalysts can be prepared by, but are not limited to, the following method: adding the salts corresponding to bimetallic Zr and M and terephthalic acid to an organic solvent, followed by a hydrothermal reaction, and then purifying and drying to obtain the bimetallic organic framework catalyst.

[0016] During catalyst preparation, the molar ratio of Zr and M bimetals to terephthalic acid is 1:0.8-1.3.

[0017] This invention selects the M-Zr-UiO-66 bimetallic organic framework catalyst for the catalytic oxidation of 1,2-propanediol, achieving a good yield of hydroxyacetone under relatively mild conditions. The main product is hydroxyacetone, and the byproduct is acetone. The main product selectivity can reach over 80%, and the 1,2-propanediol conversion rate reaches over 14%. The catalyst preparation process is simple, low-cost, reusable, and environmentally friendly. Attached Figure Description

[0018] Figure 1 The XRD characterization results are for the organic framework catalyst prepared in Example 1 of this invention and the Cr-Zr bimetallic organic framework catalysts with different proportions.

[0019] Among them: (a) 0.12Cr-Zr-UiO-66 after use; (b) 0.3Cr-Zr-UiO-66; (c) 0.12Cr-Zr-UiO-66; (d) 0.06Cr-Zr-UiO-66; (e) UiO-66 Detailed Implementation

[0020] The technical solution of the present invention is illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0021] Example 1

[0022] (1) Synthesis of metal-organic frameworks

[0023] At room temperature, 0.35 g of zirconium chloride and 0.25 g of terephthalic acid were added to 45 mL of DMF to obtain a mixed solution. After stirring for at least 30 min, the solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene and reacted at 120 °C for 24 h. After the reaction was completed, the sample was washed and centrifuged multiple times with DMF and anhydrous methanol, dried overnight in a 60 °C oven, and then dried in a vacuum drying oven at 85 °C for at least 6 h to obtain the metal-organic framework UiO-66.

[0024] (2) Synthesis of Cr-Zr organic framework catalysts with different bimetallic ratios

[0025] At room temperature, 0.06 g, 0.12 g, 0.3 g of chromium nitrate, 0.35 g of zirconium chloride, and 0.25 g of terephthalic acid were added to 45 ml of DMF solvent. After stirring for 30 min, the green mixed solution was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 120 °C for 24 h. After the reaction, the sample was washed and centrifuged multiple times with DMF and anhydrous methanol, dried overnight in a 60 °C oven, and then dried in a vacuum drying oven at 85 °C for at least 6 h to obtain catalysts with different bimetallic ratios, labeled as 0.06Cr-Zr-UiO-66, 0.12Cr-Zr-UiO-66, and 0.3Cr-Zr-UiO-66, respectively.

[0026] (3) Used in the catalytic oxidation of 1,2-propylene glycol

[0027] First, 1.4 g of 1,2-propylene glycol solution, 20 mL of acetonitrile, and 0.1 g of catalyst were added to a three-necked flask to form a mixed solution. A magnetic stir bar was added and the rotation speed was adjusted to 300 rpm. When the temperature of the reactants rose to 45 °C, 2 mL of H₂O₂ (30% by mass) was added using a peristaltic pump to initiate the catalytic reaction for 2 hours. The reaction products were filtered, diluted to a final volume, and analyzed by gas chromatography. The results are shown in Table 1.

[0028] Table 1 Comparison of catalyst activities with different Zr / Cr ratios

[0029] Catalyst name 1,2-Propanediol conversion Hydroxyacetone selectivity Hydroxyacetone yield Catalyst-free 17.92％ 38.89％ 6.96％ UIO-66 9％ 81％ 7.3％ 0.06Cr-Zr-UIO-66 8.58％ 51.39％ 9.5％ 0.12Cr-Zr-UIO-66 14.62％ 87.75％ 12.83％ 0.3Cr-Zr-UIO-66 15.53％ 67.37％ 6.56％

[0030] Example 2

[0031] The catalytic reaction conditions for 1,2-propanediol were the same as in Example 1, but the solvent composition was changed to DMF, acetonitrile + acetic acid, and DMF + acetic acid. The catalyst used was 0.12Cr-Zr-UiO-66 from Example 1. The activity evaluation results are shown in Table 2.

[0032] Table 2 Effect of different solvents on catalytic activity

[0033] solvent Propylene glycol conversion rate Hydroxyacetone selectivity Hydroxyacetone yield Acetonitrile 14.62％ 87.75％ 12.83％ DMF 9.52％ 54.86％ 5.22％ Acetonitrile + Acetic acid (3:1) 13.06％ 51.21％ 4.6％ DMF + Acetic Acid (3:1) 7.65％ 35.3％ 3.92％

[0034] The results showed that the conversion rate of 1,2-propanediol and the selectivity for hydroxyacetone were both the highest when acetonitrile was used as the solvent.

[0035] Example 3

[0036] The catalytic reaction conditions for 1,2-propanediol were the same as in Example 1, but the reaction temperatures were 40℃, 45℃, 50℃, and 55℃, respectively, and the catalyst used was the 0.12Cr-Zr-UiO-66 from Example 1. The effects of different oxidation temperatures on the final feed conversion rate and the selectivity of the reaction products are shown in Table 3. The results show that the selectivity for hydroxyacetone first increases and then decreases with increasing oxidation temperature, reaching its maximum at 45℃.

[0037] Table 3 Effect of different reaction temperatures on catalytic activity

[0038] Reaction temperature (°C) Propylene glycol conversion rate Hydroxyacetone selectivity Hydroxyacetone yield 40 8.63％ 66.44％ 7.63％ 45 14.62％ 87.75％ 12.83％ 50 14.98％ 84.33％ 12.63％ 55 13.48％ 63.09％ 8.50％

[0039] Example 4

[0040] 0.12 g of ferric nitrate, 0.35 g of zirconium chloride, and 0.25 g of terephthalic acid were added to 45 ml of DMF solvent. After stirring for 30 min, the green mixed solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene and reacted at 120 °C for 24 h. After the reaction was completed, the sample was washed and centrifuged multiple times with DMF and anhydrous methanol, dried overnight in a 60 °C oven, and then dried in a vacuum drying oven at 85 °C for at least 6 h. The obtained catalyst was named Fe-Zr-UiO-66.

[0041] The 1,2-propanediol catalytic reaction conditions were the same as in Example 1. The catalyst activity evaluation results are shown in Table 4.

[0042] Example 5

[0043] Ferric nitrate was replaced with cobalt nitrate, and the rest was the same as in Example 4. The resulting catalyst was named Co-Zr-UiO-66, and the catalyst activity evaluation results are shown in Table 4.

[0044] Table 4 Catalytic performance of Zr-UiO-66 modified with different metals

[0045] catalyst Propylene glycol conversion rate Hydroxyacetone selectivity Hydroxyacetone yield Fe-Zr-UiO-66 9.56％ 45.25％ 4.32％ Co-Zr-UiO-66 12.24％ 65.35％ 7.99％

Claims

1. A process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone, characterized in that, The M-Zr-UiO-66 bimetallic organic framework catalyst is used, the metal M is Cr, and the ligand is terephthalic acid; the molar ratio of Zr / M in the catalyst is 2-10:1, and the molar ratio of Zr and M bimetallic to terephthalic acid is 1:0.8-1.

3.

2. The process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 1, characterized in that, 1,2-propanediol, a catalyst, and an oxidant are added in an organic solvent, and the reaction is carried out at 20-75 DEG C for 1-4 h to obtain the product hydroxyacetone.

3. The process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 2, characterized in that, The reaction temperature is 45 DEG C.

4. The process for liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 2, characterized in that, The mass ratio of 1,2-propanediol to the catalyst is 1:0.03-0.

1.

5. The process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 2, characterized in that, The mass ratio of 1,2-propanediol to the oxidant is 1:1-5, calculated based on 30 wt% hydrogen peroxide.

6. The process for liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 2, characterized in that, The organic solvent is acetonitrile, acetone, acetic acid, or N,N-dimethylformamide, and the feeding mass ratio of 1,2-propanediol to the organic solvent is 1:5-20.

7. The process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to any one of claims 1 to 6, characterized in that, The molar ratio of Zr / M in the catalyst is 5:

1.

8. The process for the liquid phase catalytic oxidation of 1,2-propanediol to hydroxyacetone according to claim 7, characterized in that, The zirconium source of the catalyst is zirconium nitrate or zirconium chloride, and the salt of the second metal M is selected from chromium nitrate and chromium chloride.

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