A catalyst for the oxidation of ethylene glycol to glycolic acid and a method for its preparation

Abstract

The application provides a catalyst for preparing glycolic acid by oxidizing ethylene glycol, wherein mesoporous molecular sieve MCM-41 modified by metal Mn is used as a carrier, metal Pt is used as an active component, and metal Sn and metal Bi are used as adjuvants; wherein the content of the metal Pt is 1.0%-1.5% and the total content of the metal Sn, the metal Bi and the metal Mn is 1.5%-4.0% based on 100% of the mass of the catalyst. The catalyst for preparing glycolic acid by oxidizing ethylene glycol provided by the application promotes the improvement of ethylene glycol conversion rate and selectivity by adopting the combination of Pt and Mn, Sn and Bi elements, improves the oxidation rate and shortens the oxidation time.

Description

Technical Field

[0001] This invention relates to the field of ethylene glycol oxidation technology, and particularly to a catalyst for the oxidation of ethylene glycol to prepare glycolic acid and its preparation method. Background Technology

[0002] Glycolic acid is an important fine chemical raw material with wide applications in organic synthesis, medicine, food industry, and cosmetics. However, there are currently no companies producing glycolic acid monomers on a large scale. The main synthetic methods for glycolic acid include formaldehyde carbonylation, hydrolysis of chloroacetic acid or oxalic acid, and electrolytic reduction of oxalic acid. However, these methods suffer from drawbacks such as demanding production conditions, high catalyst costs, and large amounts of byproducts. Therefore, there is a need to develop new glycolic acid synthesis routes with mild reaction conditions, green reaction processes, and practical applications.

[0003] With breakthroughs in key catalysts for the hydrogenation of dimethyl oxalate (DMO) in China, the production process of coal-to-ethylene glycol has become increasingly mature. A large amount of ethylene glycol production capacity has not been effectively released. Directly oxidizing the excess, inexpensive ethylene glycol at low temperatures to produce high-value-added glycolic acid provides a green and efficient production process for glycolic acid.

[0004] The oxidation of ethylene glycol to glycolic acid occurs in a series coupling process on the catalyst surface, involving the activation of OH, CH, C=O, and CC bonds. Ethylene glycol is a symmetrical molecule with two identical primary hydroxyl groups. During oxidation, the activation of the OH and CH bonds on a single primary hydroxyl group and the oxidation of the aldehyde group (-CHO) occur first. Further activation of the CH bond yields glycolic acid. During the reaction, the catalyst readily leads to side reactions such as the deep oxidation of the other primary hydroxyl group in the glycolic acid product (generating oxalic acid) and the breaking of the CC bond (generating formic acid and CO2). Therefore, the core of the ethylene glycol oxidation to glycolic acid reaction is the preparation of a catalyst to address the selectivity issue of glycolic acid. Current research has demonstrated that noble single-metal catalysts and transition metal catalysts exhibit good catalytic performance under alkaline conditions. However, the introduction of alkali degrades catalyst stability, leading to low catalyst utilization efficiency, easy deactivation, high cost, and potential environmental pollution and increased separation costs, thus limiting its further industrialization.

[0005] For example, Chinese patent document CN114534723A discloses a catalyst and its preparation method for the selective oxidation of ethylene glycol to glycolic acid. This catalyst uses activated carbon as a support, palladium as the main catalytic component, and bismuth and cerium dioxide as co-catalysts. The content of palladium is 0.1%–1.5% of the support weight, and the total content of bismuth and cerium dioxide, based on cerium content, is 0.25%–1.5% of the support weight. The Pd-Bi-CeO2 / C catalyst provided in this document, under the bimetallic co-catalytic effect of bismuth and cerium dioxide, achieves highly efficient and selective catalytic catalysis of the synthesis of glycolic acid from ethylene glycol with low Pd loading. However, in this scheme, the interaction between the active palladium and the support is relatively weak, and the active palladium easily aggregates during the reaction, resulting in a decrease in catalyst activity.

[0006] Chinese patent document CN112961046B discloses a method for synthesizing glycolic acid from waste biomass without alkali, comprising the following steps: 1) hydrolyzing and hydrogenating the waste biomass to obtain a polyol; 2) adding a metal catalyst to the extracted polyol and mixing it evenly, wherein the molar ratio of the metal catalyst to the polyol is 1:50-200; 3) pouring the polyol with the added metal catalyst into a high-pressure reactor and introducing oxygen at a pressure of 0.5-8 MPa, reacting at a temperature of 20-180℃ for 1-50 h to obtain crude glycolic acid; 4) subjecting the obtained crude glycolic acid to vacuum distillation to obtain high-purity glycolic acid; wherein the active metal accounts for 0.5-1% of the catalyst mass; the metal catalyst is prepared by loading an active metal onto a catalyst support, wherein the catalyst support is one of NaY, C, CeO2, MCM-41, ZSM-5, or MgO; and the active metal is one or more of Pt, Au, Pd, Ni, Co, or Fe. However, when this method uses a large amount of active metals (Pt, Au, Pd, Ni, Co, Fe), they are prone to agglomeration during the reaction, thus affecting the catalytic activity of the catalyst. Summary of the Invention

[0007] Based on the existing problems or areas for improvement in catalysts for the selective oxidation of ethylene glycol to glycolic acid, this invention provides a catalyst for the oxidation of ethylene glycol to glycolic acid. This catalyst enables highly active and selective oxidation of ethylene glycol to glycolic acid under mild and green alkali-free conditions. By using a Mn-modified molecular sieve as a support, Pt as the active component, and Mn, Sn, and Bi as co-active components, the co-active and active components work synergistically. Mn, Sn, Bi, and Pt form alloys, reducing active metal agglomeration and significantly improving the dispersion of Pt in the catalyst. Furthermore, the synergistic catalytic effect of Sn, Bi, Mn, and Pt enhances the catalytic performance of the catalyst.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A catalyst for the oxidation of ethylene glycol to prepare glycolic acid uses Mn-modified mesoporous molecular sieve MCM-41 as a support, Pt as the active component, and Sn and Bi as auxiliary agents.

[0010] Specifically, based on the mass of the catalyst (100%), the content of metal Pt is 1.0%-1.5%, and the total content of metal Sn, metal Bi, and metal Mn is 1.5%-4.0%.

[0011] Optionally, in the support of the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the molar ratio of metal Mn to element Si is 1:(25-360).

[0012] Optionally, in the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the mass ratio (based on elemental metals) of the metal Mn, the metal Sn and the metal Bi is (0.2-3.5):(0.2-1.5):(0.2-1.0).

[0013] Optionally, in the catalyst for the oxidation of ethylene glycol to glycolic acid provided by the present invention, the specific surface area of ​​the support (metal Mn-modified mesoporous molecular sieve MCM-41) is 500-900 m². 2 / g, pore volume 0.5-0.9cm³ 3 / g; preferably, the specific surface area is 570-600 m² / g. 2 / g, pore volume 0.5-0.7cm 3 / g.

[0014] Optionally, in the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the catalyst is a supported catalyst (metal Pt, metal Sn and metal Bi supported on a molecular sieve MCM-41 modified with metal Mn).

[0015] The present invention also provides a method for preparing the above-mentioned catalyst for the oxidation of ethylene glycol to glycolic acid, comprising the following steps:

[0016] A metal Mn-modified mesoporous molecular sieve MCM-41 was impregnated with an equal volume of impregnation solution containing Pt salt, Sn salt and Bi salt. After aging, drying, calcining and reduction, the catalyst for the oxidation of ethylene glycol to prepare glycolic acid was obtained.

[0017] Optionally, in the preparation method of the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the aging temperature is 20-40℃ and the time is 2-4h.

[0018] The drying temperature is 100-120℃, and the time is 2-4 hours;

[0019] The roasting temperature is 400-600℃ and the time is 4-6 hours.

[0020] Optionally, in the preparation method of the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the reducing atmosphere is a mixture of H2 and Ar, the volume content of H2 in the mixture is 5%-30%, the reducing temperature is 300-450℃, and the time is 3-6h.

[0021] Optionally, in the preparation method of the catalyst for the oxidation of ethylene glycol to prepare glycolic acid provided by the present invention, the Pt salt is selected from at least one of chloroplatinic acid (H2PtC16·6H2O), tetraammineplatinum, and platinum nitrate.

[0022] The Sn salt is selected from at least one of stannous chloride, stannous nitrate, and stannous sulfate.

[0023] The Bi salt is selected from at least one of bismuth nitrate, bismuth sulfate, and bismuth chloride.

[0024] Optionally, in the preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided by the present invention, the impregnation solution containing Pt salt, Sn salt and Bi salt recommended by the present invention is prepared by the following method:

[0025] Dissolve the platinum salt completely in deionized water to obtain a platinum salt solution;

[0026] Sn salt and Bi salt were dissolved in deionized water to obtain a mixed solution;

[0027] The platinum salt solution is mixed with the mixed solution to obtain the impregnation solution containing Pt salt, Sn salt and Bi salt.

[0028] Optionally, in the preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided by the present invention, metal Mn is used to form a metal Mn-modified mesoporous molecular sieve MCM-41 by in-situ doping. The preparation method of the metal Mn-modified mesoporous molecular sieve MCM-41 recommended by the present invention includes the following steps:

[0029] (1) Dissolve the template agent (such as hexadecyltrimethylammonium bromide (CTAB)) in deionized water to obtain a template agent solution; if necessary, heat and stir to completely dissolve the template agent in deionized water;

[0030] (2) While stirring, adjust the pH of the template agent solution to about 11 with ammonia water, then add the manganese salt solution and mix well;

[0031] (3) Tetraethyl orthosilicate (TEOS) is slowly added dropwise to the solution in step (2) while maintaining the temperature at 10-50℃. After the addition is complete, the mixture is stirred at this temperature for 0.2-0.5h to form a latex solution. The solution is then transferred to a crystallization vessel and crystallized at 100-120℃ for 40-55h. The solid obtained after separation is washed with deionized water until pH≈7. The solid is then dried at 80-150℃ for 2-4h to obtain a white powder sample. The sample is then placed in a muffle furnace and calcined at 400-600℃ for 4-6h to obtain a metal Mn modified mesoporous molecular sieve MCM-41 (denoted as MCM-41-Mn).

[0032] The manganese salt solution is obtained by dissolving manganese salt in deionized water, wherein the manganese salt is selected from at least one of manganese nitrate, manganese sulfate, and manganese chloride.

[0033] Compared with the prior art, the advantages of the present invention are as follows:

[0034] The catalyst for the oxidation of ethylene glycol to glycolic acid provided by this invention uses Mn-modified mesoporous molecular sieve MCM-41, which has a high specific surface area and high pore volume, as a support. Pt, Sn, and Bi are loaded on the Mn-modified MCM-41 molecular sieve. The Pt, Mn, Sn, and Bi metals can be uniformly distributed on the pore walls. Pt forms an alloy with the metals Mn, Sn, and Bi, which reduces the agglomeration of Pt on the MCM-41 molecular sieve and increases the metal dispersion of Pt. The active sites of Pt in the catalyst are hardly lost, which improves the stability of the catalyst. At the same time, the combination of Pt with Mn, Sn, and Bi elements promotes the improvement of ethylene glycol conversion and selectivity, increases the oxidation rate, and shortens the oxidation time. Detailed Implementation

[0035] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0036] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0037] Example 1

[0038] This embodiment provides a catalyst for the oxidation of ethylene glycol to prepare glycolic acid, and its preparation method includes the following steps:

[0039] Carrier preparation:

[0040] Step (1): Dissolve 2.7g of cetyltrimethylammonium bromide (CTAB) in 125mL of deionized water, place it in a water bath, and heat it under magnetic stirring to completely dissolve the template agent CTAB, thus obtaining the template agent solution;

[0041] Step (2): Add ammonia to the template agent solution under magnetic stirring to make the pH of the solution around 11 (cover with plastic wrap to prevent ammonia from evaporating);

[0042] Step (3): Under magnetic stirring, add 0.322g of 50wt% Mn(NO3)2 solution to the solution in step (2);

[0043] Step (4): Take 14 ml of tetraethyl orthosilicate (TEOS) (calculated as SiO2, mass fraction of 28.4%) and slowly add it dropwise to the solution in step (3). Maintain the temperature at 35℃ and stir for 0.5 h. Transfer the resulting latex solution to a crystallization vessel and crystallize at 110℃ for 52 h. After crystallization is completed, filter the solid and wash it with deionized water until pH≈7. Dry it at 100℃ for 4 h. Place the resulting white powder sample in a muffle furnace and calcine at 550℃ for 6 h to obtain MCM-41-Mn molecular sieve. The Mn / Si molar ratio in the MCM-41-Mn molecular sieve is 1:70.

[0044] Catalyst preparation:

[0045] Step (a): Take 5.0 mL of chloroplatinic acid solution (Pt concentration of 0.03 g / mL), which is a platinum solution;

[0046] Step (b): Take 2.5 ml of a solution containing Sn(NO3)4 and Bi(NO3)3, where the Sn concentration is 0.02 g / ml and the Bi concentration is 0.01 g / ml, and mix it with a platinum solution to form an impregnation solution;

[0047] Step (c): The impregnation solution is added dropwise to 10g of the above MCM-41-Mn molecular sieve support and shaken continuously until complete impregnation is achieved to achieve equal volume impregnation. The paste-like solid obtained by complete impregnation is aged at 20°C for 2h, and then dried at 100°C for 4h. After crushing, it is placed in a muffle furnace and calcined at 450°C for 6h to obtain the catalyst precursor. The catalyst precursor is placed in a tube furnace in a mixed gas atmosphere of H2 and Ar (H2 volume content is 10%) and reduced at 350°C for 6h to obtain the Pt-MnSnBi / MCM-41 catalyst.

[0048] Examples 2-6

[0049] The preparation methods of the catalysts for the oxidation of ethylene glycol to glycolic acid provided in Examples 2-6 are similar to those in Example 1, with the only difference being some parameters. The specific parameters are shown in the table below.

[0050] Table 1

[0051]

[0052]

[0053] Comparative Example 1

[0054] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, except that: 1) step (3) is omitted in the preparation process of the support in this comparative example, and the final product is a fully silica MCM-41 molecular sieve without Mn; 2) Sn(NO3)4 is not added in step (b) of the catalyst preparation in this comparative example.

[0055] The specific preparation steps for this comparative example are as follows:

[0056] Carrier preparation

[0057] Step (1): Dissolve 2.7g of cetyltrimethylammonium bromide (CTAB) in 125mL of deionized water, place it in a water bath, and heat it under magnetic stirring to completely dissolve the template agent CTAB, thus obtaining the template agent solution;

[0058] Step (2): Add ammonia to the template agent solution under magnetic stirring, so that the pH of the solution is around 11 (cover with plastic wrap to prevent ammonia from evaporating);

[0059] Step (3): Take 12.65g of tetraethyl orthosilicate (TEOS) (calculated as SiO2, mass fraction of 28.4%) and slowly add it dropwise to the solution in step (2). Maintain the temperature at 35℃ and stir for 0.5h. Transfer the resulting latex solution to a crystallization vessel and crystallize at 110℃ for 52h. After crystallization is complete, filter the solid and wash it with deionized water until pH≈7. Dry it at 100℃ for 4h. Place the resulting white powder sample in a muffle furnace and calcine at 550℃ for 6h to obtain MCM-41 molecular sieve.

[0060] Catalyst preparation

[0061] Step (a): Take 5.0 mL of chloroplatinic acid solution (Pt concentration of 0.03 g / mL), which is a platinum solution;

[0062] Step (b): Take 2.5 ml of Bi(NO3)3 solution with a Bi concentration of 0.01 g / ml and mix it with platinum solution to form an impregnation solution;

[0063] Step (c): The impregnation solution is added dropwise to 10g of the above MCM-41 molecular sieve support and shaken continuously until complete impregnation is achieved to achieve equal volume impregnation. The paste-like solid obtained after complete impregnation is aged at 20°C for 2h, then dried at 100°C for 4h, crushed and placed in a muffle furnace for calcination at 450°C for 6h. Then, it is placed in a tube furnace in a mixed gas atmosphere of H2 and Ar (H2 volume content is 10%) for reduction at 350°C for 6h to obtain the catalyst.

[0064] Comparative Example 2

[0065] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, except that: 1) Sn(NO3)4 is not added in step (b) of the preparation of the catalyst in this comparative example.

[0066] The specific preparation steps for this comparative example are as follows:

[0067] Carrier preparation: Same as in Example 1.

[0068] Catalyst preparation

[0069] Step (a): Take 5.0 mL of chloroplatinic acid solution (Pt concentration of 0.03 g / mL), which is a platinum solution;

[0070] Step (b): Take 2.5 ml of Bi(NO3)3 solution with a Bi concentration of 0.02 g / ml and mix it with platinum solution to form an impregnation solution;

[0071] Step (c): The impregnation solution is added dropwise to 10g of the above MCM-41-Mn molecular sieve support and shaken continuously until complete impregnation is achieved to achieve equal volume impregnation. The paste-like solid obtained after complete impregnation is aged at 20°C for 2h, then dried at 100°C for 4h, crushed and placed in a muffle furnace for calcination at 450°C for 6h. Then, it is placed in a tube furnace in a mixed gas atmosphere of H2 and Ar (H2 volume content is 10%) for reduction at 350°C for 6h to obtain the catalyst.

[0072] Comparative Example 3

[0073] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, except that: 1) step (3) is omitted in the preparation process of the support in this comparative example, and the final product is a fully silica MCM-41 molecular sieve without Mn; 2) in step (b) of the catalyst preparation in this comparative example, 2.5 ml of deionized water is used instead of the solution containing Sn(NO3)4 and Bi(NO3)3.

[0074] The specific preparation steps for this comparative example are as follows:

[0075] Carrier preparation: Same as Comparative Example 1.

[0076] Catalyst preparation:

[0077] Step (a): Take 5.0 mL of chloroplatinic acid solution (Pt concentration of 0.03 g / mL), which is a platinum solution;

[0078] Step (b): Mix 2.5 ml of deionized water with the platinum solution to form an impregnation solution;

[0079] Step (c): The impregnation solution is added dropwise to 10g of the above MCM-41 molecular sieve support and shaken continuously until complete impregnation is achieved to achieve equal volume impregnation. The paste-like solid obtained after complete impregnation is aged at 20°C for 2h, then dried at 100°C for 4h, crushed and placed in a muffle furnace for calcination at 450°C for 6h. Then, it is placed in a tube furnace in a mixed gas atmosphere of H2 and Ar (H2 volume content is 10%) for reduction at 350°C for 6h to obtain the catalyst.

[0080] Comparative Example 4

[0081] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, the only difference is that the Pt concentration in step (a) of the catalyst preparation in this comparative example is 0.016 g / mL.

[0082] Comparative Example 5

[0083] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, except that: 1) in step (b) of the preparation of the catalyst in this comparative example, 2.5 ml of deionized water is used instead of the solution containing Sn(NO3)4 and Bi(NO3)3.

[0084] Comparative Example 6

[0085] The preparation method of the catalyst for the oxidation of ethylene glycol to glycolic acid provided in this comparative example is similar to that in Example 1, the only difference is that: in step (3) of the support preparation, the weight of 50wt% Mn(NO3)2 is 1.127g, and the Mn / Si molar ratio in the MCM-41-Mn molecular sieve is 1:20; in step (b) of the catalyst preparation, the Sn(NO3)4 and Bi(NO3)3 in 2.5ml solution contain Sn and Bi concentrations of 0.07g / ml and 0.05g / ml, respectively.

[0086] Experimental Example 1

[0087] The supports and catalysts prepared in each embodiment and comparative example were tested according to the following methods, and the specific results are shown in the table below.

[0088] Specific surface area of ​​a carrier tested using the BET method;

[0089] Pore ​​volume: The BJH method was used to test the pore volume of the carrier.

[0090] Metal content: Pt, Sn, Bi and Mn on the catalyst were determined by inductively coupled plasma atomic emission spectrometry (ICP).

[0091] Table 2

[0092]

[0093] Experimental Example 2

[0094] The dispersion of Pt in the catalysts prepared in the above embodiments and comparative examples was tested according to the following methods, and the specific results are shown in the table below.

[0095] Metal dispersion was characterized using a ChemBET3000 fully automated temperature-programmed chemisorption analyzer from Quanta Computer Corporation (USA). This instrument is equipped with a fully automated quantitative loop injector and an automatic gas inlet valve for pulsed chemisorption determination of metal dispersion. The specific detection method is as follows:

[0096] After reducing the sample to be tested at 450℃ in a hydrogen atmosphere for 3 hours, it was purged to 50℃ in an argon atmosphere, and then subjected to pulsed chemisorption using hydrogen. Based on the selective chemisorption of hydrogen on the Pt surface and the clear stoichiometric relationship between the adsorption and the hydrogen content, the Pt dispersion on the catalyst was calculated from the adsorption amount. The specific Pt dispersion (R) can be expressed as the ratio of the number of adsorbed hydrogen atoms to the number of metallic Pt atoms on the catalyst, as follows:

[0097] R = N H / N Pt x100%

[0098] Where R is the metal dispersion; N H N represents the number of adsorbed hydrogen atoms. Pt This represents the total number of Pt atoms.

[0099] Table 3. Dispersion of Pt on the catalyst

[0100]

[0101]

[0102] The data in the table above show that adding Mn, Sn and Bi to the catalyst can effectively improve the metal dispersion of Pt in the catalyst, thereby reducing the aggregation of Pt in the catalyst.

[0103] Experimental Example 3

[0104] The catalysts prepared in the above embodiments and comparative examples were used to verify the effectiveness of ethylene glycol oxidation to glycolic acid according to the following methods. The specific test results are shown in the table below, and the specific test methods are as follows:

[0105] 25 mL of a 0.3 mol / L ethylene glycol solution (water as solvent) was added to a 50 mL micro high-pressure reactor (Beijing Century Senlang SLM50) equipped with a stirrer. The catalyst to ethylene glycol ratio was 1 g:10 mol. The reaction pressure of the oxidant oxygen in the reactor was 1.0 MPa, the reaction temperature was 60 °C, and the rotation speed was 1000 r / min. After the reaction was completed and cooled, the reaction solution was subjected to high-performance liquid chromatography (HPLC) (detector: RID-20A; mobile phase: 0.05 mol / L sulfuric acid aqueous solution; flow rate: 0.17 mL / min; time: 25 min; temperature: 40 °C; column: Rezex™ ROA-Organic Acid H). + (8%), model number 00G-0138-E0) was analyzed.

[0106] Table 4 Results of oxidation reaction

[0107]

[0108]

[0109] As can be seen from the data in the table above, using Pt as the main active metal, Mn-modified molecular sieve as the support, Sn and Bi as auxiliary agents, and limiting the content of each metal, can improve the conversion rate and selectivity of ethylene glycol oxidation to glycolic acid, while reducing the reaction time of the entire oxidation reaction. However, after extending the reaction time using the catalyst prepared in the comparative example, the selectivity and conversion rate of glycolic acid still cannot reach the same level as those in the example.

[0110] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A catalyst for the oxidation of ethylene glycol to prepare glycolic acid, characterized in that, The mesoporous molecular sieve MCM-41 modified with metal Mn was used as a support, with metal Pt as the active component and metal Sn and metal Bi as auxiliary agents. Specifically, based on the mass of the catalyst (100%), the content of metal Pt is 1.0%-1.5%, and the total content of metal Sn, metal Bi, and metal Mn is 1.5%-4.0%. In the carrier, the molar ratio of the metal Mn to the element Si is 1:(25-360); The mass ratio of the metal Mn, the metal Sn, and the metal Bi is (0.2-3.5):(0.2-1.5):(0.2-1.0); The method for preparing the catalyst for the oxidation of ethylene glycol to glycolic acid includes the following steps: A metal Mn-modified mesoporous molecular sieve MCM-41 was impregnated with an equal volume of impregnation solution containing Pt salt, Sn salt and Bi salt. After aging, drying, calcining and reduction, the catalyst for the oxidation of ethylene glycol to prepare glycolic acid was obtained.

2. The catalyst according to claim 1, characterized in that, The specific surface area of ​​the carrier is 500-900 m². 2 / g, pore volume 0.5-0.9cm³ 3 / g.

3. The catalyst according to claim 1, characterized in that, The aging time is 2-4 hours; The roasting temperature is 400~600℃ and the time is 4-6 h.

4. The catalyst according to claim 1, characterized in that, The reduction atmosphere is a mixture of H2 and Ar, with the volume content of H2 in the mixture being 5% to 30%, and the reduction temperature being 300 to 450°C for 3 to 6 hours.

5. The catalyst according to claim 1, characterized in that, Metallic Mn was used to form a metallic Mn-modified mesoporous molecular sieve, MCM-41.

6. The catalyst according to claim 1, characterized in that, The Pt salt is selected from at least one of H2PtC16·6H2O, tetraammineplatinum and platinum nitrate; The Sn salt is selected from at least one of stannous chloride, stannous nitrate, and stannous sulfate; The Bi salt is selected from at least one of bismuth nitrate, bismuth sulfate, and bismuth chloride.

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