Preparation method of terephthalic acid

Abstract

The invention discloses a preparation method of terephthalic acid. Comprising the following steps: placing a solvent solution containing 2, 4-hexadienoic acid in a closed reactor, introducing ethylene to reach a specific pressure, carrying out a cycloaddition reaction to obtain an intermediate product, contacting the intermediate product with a catalyst, and carrying out a dehydrogenation reaction to obtain a product containing terephthalic acid. The method has the advantages of simple steps, easily available raw materials, high product purity and easiness in large-scale preparation, provides advanced technical support for industrial production of bio-based terephthalic acid, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of terephthalic acid and belongs to the field of chemistry and chemical industry. BACKGROUND

[0002] Terephthalic acid is an important industrial chemical with high added value, is one of the most widely used and largest amount of binary acids, and is a main synthetic raw material of polyethylene terephthalate. At present, terephthalic acid is mainly produced by the Amoco method in the industry. In the Co / Mn / Br homogeneous catalyst system, p-xylene is oxidized under the harsh reaction conditions of about 200 DEG C, about 2-3 MPa and a solvent of acetic acid. The main problems of the process are low efficiency, corrosive solvent and difficulty in separating the product from the catalyst. The raw material of the process is p-xylene, which is derived from the refining process of petroleum and is non-renewable.

[0003] 2,4-hexadienedioic acid, commonly known as muconic acid, is a new bio-based raw material and is mainly obtained by fermentation of saccharides. In 1994, scientists used Escherichia coli as a starting strain, and then used 1,2 dioxygenase, protocatechuate decarboxylase and 3-dehydroshikimate dehydratase for catalysis to synthesize muconic acid with glucose as a carbon source. Later, other researchers continuously improved and finally cultivated a yeast strain 24 times stronger than the starting strain, and the produced muconic acid reached 141 mg / L. SUMMARY

[0004] The terephthalic acid is obtained by the two-step reaction of cycloaddition and dehydrogenation with 2,4-hexadienedioic acid derived from biomass as a raw material, and has high conversion rate and selectivity, good stability and green environmental protection.

[0005] According to the above-mentioned idea of synthesizing terephthalic acid with biomass energy as a raw material, the application provides a method for obtaining terephthalic acid by mixing 2,4-hexadienedioic acid and ethylene and then performing cycloaddition and dehydrogenation reaction. The conversion rate of the method can reach 85%, and the selectivity can reach more than 90%.

[0006] According to an aspect of the application, a preparation method of terephthalic acid is provided, comprising the following steps:

[0007] A solvent solution containing 2,4-hexadienedioic acid is placed in a closed reactor, ethylene is introduced, a cycloaddition reaction occurs, an intermediate product is obtained, the intermediate product is contacted with a catalyst, a dehydrogenation reaction occurs, and a product containing terephthalic acid is obtained;

[0008] The 2,4-hexadienedioic acid is derived from biomass;

[0009] The 2,4-hexadienedioic acid is produced by a yeast strain or produced by a dehydrating and deoxidizing reaction method from galactaric acid derived from fruit peel.

[0010] The whole process is as follows:

[0011]

[0012] The solvent is selected from at least one of water, methanol, ethanol, isopropanol, n-butanol, acetone, dichloromethane, acetonitrile, n-hexane, toluene, tetrahydrofuran, 1,4-dioxane;

[0013] The concentration of 2,4-hexadienedioic acid in the solvent solution containing 2,4-hexadienedioic acid is 0.2-10M;

[0014] Optionally, the concentration of 2,4-hexadienedioic acid is 2-6M.

[0015] The pressure reached by passing in ethylene is 0.5-10Mpa;

[0016] Optionally, the pressure reached by passing in ethylene is 2-5Mpa.

[0017] The temperature of the cycloaddition reaction is 100-400℃;

[0018] Optionally, the temperature of the cycloaddition reaction is 160-260℃.

[0019] The time of the cycloaddition reaction is 2-36h;

[0020] Optionally, the time of the cycloaddition reaction is 6-24h.

[0021] The catalyst is composed of a carrier and a metal active component supported on the carrier;

[0022] The carrier is selected from at least one of C, Al2O3, SiO2, TiO2, MgO, CeO2, ZSM-5;

[0023] The metal active component is selected from at least one of Ni element, Pt element, Pd element, Rh element, Ir element;

[0024] In the catalyst, the loading amount of the metal active component is 0.5-10wt%.

[0025] The ratio of the use amount of the intermediate product to the catalyst is 1ml:0.01g-excess.

[0026] The temperature of the dehydrogenation reaction is 100-400℃;

[0027] Optionally, the temperature of the dehydrogenation reaction is 160-260℃.

[0028] The time of the dehydrogenation reaction is 2-36h;

[0029] Optionally, the dehydrogenation reaction time is 6-24 h.

[0030] The beneficial effects that can be produced by the present application include:

[0031] 1. Compared with the traditional method of synthesizing terephthalic acid, the raw material of the present application is green and renewable, the waste liquid is less, the corrosion is small, and the environment is more friendly.

[0032] 2. Compared with traditional fossil energy-based raw materials, the reaction raw material is derived from biomass, which conforms to the concept of sustainable development and the concept of double carbon. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Liquid chromatogram of the bio-based terephthalic acid obtained in Example 1. DETAILED DESCRIPTION

[0034] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples.

[0035] Unless otherwise specified, the raw materials and catalysts in the examples of the present application are purchased through commercial channels.

[0036] Example 1:

[0037] Galactaric acid derived from fruit peel is subjected to a dehydration and deoxidation reaction in the presence of a catalyst and a reducing agent to obtain muconic acid. 5 g of muconic acid prepared by the above reaction is added to a high-pressure reaction kettle containing 100 mL of acetonitrile, replaced with nitrogen for 3 times, and then filled with ethylene to 2 MPa. The oil bath is heated to 220°C, and the reaction is carried out for 18 h. After the reaction is completed, the conversion rate of muconic acid and the selectivity of 2-cyclohexene-1,4-dicarboxylic acid are analyzed by liquid chromatography. The conversion rate is 95%, and the selectivity of 2-cyclohexene-1,4-dicarboxylic acid is 90%.

[0038] Commercial Pt / C catalyst is added to the above high-pressure reaction kettle containing material A containing 2-cyclohexene-1,4-dicarboxylic acid, replaced with nitrogen for 3 times, and heated to 220°C in an oil bath. The reaction is carried out for 12 h. After the reaction is completed, the conversion rate of 2-cyclohexene-1,4-dicarboxylic acid and the selectivity of terephthalic acid are analyzed by liquid chromatography, as shown in Figure 1 The conversion rate is 90%, and the selectivity of terephthalic acid is 92%.

[0039] Example 2:

[0040] Into the above autoclave containing material A of 2-cyclohexene-1, 4-dicarboxylic acid, 5 g of muconic acid was added, and then the autoclave was purged with nitrogen for 3 times and charged with ethylene to 2 MPa. The autoclave was heated to 220°C in an oil bath and reacted for 18 h. After the reaction, the conversion of muconic acid and the selectivity of 2-cyclohexene-1, 4-dicarboxylic acid were analyzed by liquid chromatography. The conversion was 98% and the selectivity of 2-cyclohexene-1, 4-dicarboxylic acid was 92%.

[0041] Into the above autoclave containing material A of 2-cyclohexene-1, 4-dicarboxylic acid, a commercial Rh / Al2O3 catalyst was added, and then the autoclave was purged with nitrogen for 3 times and heated to 220°C in an oil bath and reacted for 12 h. After the reaction, the conversion of 2-cyclohexene-1, 4-dicarboxylic acid and the selectivity of terephthalic acid were analyzed by liquid chromatography. The conversion was 92% and the selectivity of terephthalic acid was 95%.

[0042] Example 3:

[0043] Into the above autoclave containing material A of 2-cyclohexene-1, 4-dicarboxylic acid, 8 g of muconic acid was added, and then the autoclave was purged with nitrogen for 3 times and charged with ethylene to 4 MPa. The autoclave was heated to 220°C in an oil bath and reacted for 18 h. After the reaction, the conversion of muconic acid and the selectivity of 2-cyclohexene-1, 4-dicarboxylic acid were analyzed by liquid chromatography. The conversion was 97% and the selectivity of 2-cyclohexene-1, 4-dicarboxylic acid was 92%.

[0044] Into the above autoclave containing material A of 2-cyclohexene-1, 4-dicarboxylic acid, a commercial Rh / Al2O3 catalyst was added, and then the autoclave was purged with nitrogen for 3 times and heated to 240°C in an oil bath and reacted for 12 h. After the reaction, the conversion of 2-cyclohexene-1, 4-dicarboxylic acid and the selectivity of terephthalic acid were analyzed by liquid chromatography. The conversion was 91% and the selectivity of terephthalic acid was 89%.

[0045] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the above describes the preferred embodiments of the present application, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. A method for preparing terephthalic acid, characterized in that, Includes the following steps: A solvent solution containing 2,4-hexadienediaic acid is placed in a closed reactor, and ethylene is introduced to induce a cycloaddition reaction, yielding an intermediate product. The intermediate product is then contacted with a catalyst to induce a dehydrogenation reaction, yielding a product containing terephthalic acid.

2. The preparation method according to claim 1, characterized in that, The solvent is selected from at least one of water, methanol, ethanol, isopropanol, n-butanol, acetone, dichloromethane, acetonitrile, n-hexane, toluene, tetrahydrofuran, and 1,4-dioxane; In the solvent solution containing 2,4-hexadienediaic acid, the concentration of 2,4-hexadienediaic acid is 0.2–10 M; Preferably, the concentration of the 2,4-hexadienediaic acid is 2–6 M.

3. The preparation method according to claim 1, characterized in that, The pressure reached when ethylene is introduced is 0.5–10 MPa; Preferably, the pressure reached when ethylene is introduced is 2-5 MPa.

4. The preparation method according to claim 1, characterized in that, The cycloaddition reaction is performed at a temperature of 100–400 °C. Preferably, the cycloaddition reaction is carried out at a temperature of 160–260°C.

5. The preparation method according to claim 1, characterized in that, The cycloaddition reaction takes 2–36 hours; Preferably, the cycloaddition reaction takes 6 to 24 hours.

6. The preparation method according to claim 1, characterized in that, The catalyst is composed of a support and a metal active component supported on the support; The support is selected from at least one of C, Al2O3, SiO2, TiO2, MgO, CeO2, and ZSM-5; The active metal component is selected from at least one of Ni, Pt, Pd, Rh, and Ir elements; In the catalyst, the loading of the metal active component is 0.5 to 10 wt%.

7. The preparation method according to claim 1, characterized in that, The ratio of the intermediate product to the catalyst is 1 ml: 0.01 g to excess.

8. The preparation method according to claim 1, characterized in that, The temperature of the dehydrogenation reaction is 100–400°C; Preferably, the temperature of the dehydrogenation reaction is 160–260°C.

9. The preparation method according to claim 1, characterized in that, The dehydrogenation reaction takes 2–36 hours; Preferably, the dehydrogenation reaction takes 6 to 24 hours.

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