Oxidation catalyst, preparation method and application thereof, and method for preparing glycollic acid by oxidizing ethylene glycol

Abstract

The invention relates to the field of catalysts, in particular to an oxidation catalyst, a preparation method and application of the oxidation catalyst and a method for preparing glycollic acid through ethylene glycol oxidation, a carrier of the oxidation catalyst is Sb2O5, and an active component of the oxidation catalyst is platinum oxide; wherein the content of platinum oxide in the oxidation catalyst is 0.1-5 wt%. According to the oxidation catalyst, the alkaline deposition agent is used for regulating and controlling the generation form and structure of the active component and the action between the active component and the carrier, so that the catalytic oxidation performance of the oxidation catalyst is remarkably improved, and glycollic acid can be prepared by catalyzing ethylene glycol under the condition of no additional alkali.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to an oxidation catalyst, a preparation method and application thereof, and a method for preparing glycolic acid by oxidizing ethylene glycol. Background Art

[0002] As one of the main downstream products of coal chemical industry, ethylene glycol can be used in energy, plastics and chemical industry. With the rapid development of my country's green industry and coal chemical industry, the output of ethylene glycol has increased rapidly, which has led to overcapacity. How to efficiently and greenly convert it into value-added fine chemicals has attracted much attention. Glycolic acid is a very important chemical that plays an important role in organic chemicals, leather processing, packaging materials, adhesives and other fields, and has broad market prospects.

[0003] Glycolic acid can be obtained by partial oxidation of ethylene glycol. In industry, the methods for producing glycolic acid from ethylene glycol mainly include biocatalytic oxidation, electrochemical catalytic oxidation and chemical oxidation. The reaction process of biocatalytic oxidation is relatively simple, but the production of glycolic acid is greatly affected by the strain and reaction conditions, and there is a lot of glyoxylic acid in the product, making it difficult to separate. The chemical catalysis of ethylene glycol to produce glycolic acid has the advantages of adjustable reaction, high production efficiency and mild reaction, and is considered to be a sustainable and green method.

[0004] Considering the two hydroxyl functional groups in the ethylene glycol molecule, one of which -CH2OH is oxidized to -CHO to generate glycolaldehyde, glycolaldehyde is extremely unstable and will be further oxidized, and -CHO in glycolaldehyde is oxidized to -COOH and then converted into glycolic acid, while -CH2OH in glycolaldehyde is oxidized to produce glyoxal, and glyoxal will be further oxidized to generate glyoxylic acid, while -CH2OH in glycolic acid will also be further oxidized to -CHO to generate glyoxylic acid and oxalic acid. Therefore, in the reaction of partial oxidation of ethylene glycol to produce glycolic acid, it is particularly important to select a suitable catalyst and preparation method. Literature (Catalysis Science & Technology, 2017, 7 (11): 2371-2371.) reports a CNF-loaded copper or nickel catalyst, which reacts for 15 hours at 150°C-180°C, and an external base must be added at the same time. The ethylene glycol conversion rate is as high as 82%, and the generation of glycolic acid is related to the base. The document (Chemical Engineering Science, 2023, 268, 118394) reported an activated carbon catalyst. When hydrogen peroxide was added to the NaOH system, ethylene glycol was converted into glycolic acid, and the highest selectivity of glycolic acid could reach 53.2%. The applicant disclosed a catalyst for producing glycolic acid in the invention patent (CN 116809063). First, oxygen vacancies were constructed by pretreating the carrier, and a high-performance PdO catalyst was prepared by impregnation. After reacting at 220°C for 5 hours, the glycolic acid yield could reach 82%. Given that the current selective oxidation of ethylene glycol to produce glycolic acid requires the addition of a strong base, the production process is relatively complicated, and the conversion efficiency still needs to be further improved.

[0005] At present, it is extremely important to study simple, green and effective catalysts suitable for the catalytic oxidation of ethylene glycol and their preparation methods to provide strong guarantees for its expansion of large-scale production. Summary of the invention

[0006] The purpose of the present invention is to provide an oxidation catalyst and its preparation method and application, and a method for producing glycolic acid by oxidation of ethylene glycol, in view of the problems that the current selective oxidation reaction of ethylene glycol to produce glycolic acid requires the additional addition of a strong base, the production process is relatively complicated, and the conversion efficiency still needs to be further improved. The oxidation catalyst uses an alkaline precipitant to regulate the generation form and structure of the active component and the interaction between it and the carrier, thereby significantly improving its catalytic oxidation performance, and can catalyze the production of glycolic acid by ethylene glycol without the addition of an external base.

[0007] In order to achieve the above-mentioned object, in the first aspect, the present invention provides an oxidation catalyst, characterized in that the carrier of the oxidation catalyst is Sb2O5, and the active component is platinum oxide; wherein,

[0008] The platinum oxide content in the oxidation catalyst is 0.1-5 wt%.

[0009] Preferably, the platinum oxide in the oxidation catalyst is provided by one or two or more of platinum halide, platinum chlorate, platinum acetate, platinum sulfate, platinum nitrate and platinum ammine complex.

[0010] In a second aspect, the present invention provides a method for preparing an oxidation catalyst, which comprises: mixing Sb2O5 and a platinum salt in the presence of a liquid medium, adding an alkaline reagent, depositing, precipitating, washing, drying, and calcining.

[0011] Preferably, the platinum salt is selected from one or two or more of platinum halides, platinum chlorates, platinum acetates, platinum sulfates, platinum nitrates and platinum ammine complexes.

[0012] Preferably, the liquid medium is water.

[0013] More preferably, the alkaline agent is selected from one or two or more of urea, ammonia water, sodium carbonate and potassium carbonate.

[0014] Preferably, the molar ratio of Sb2O5 to platinum salt is 1:0.15-10.

[0015] Preferably, the mass concentration of the alkaline agent is 0.1-1.0 g / mL.

[0016] Preferably, the deposition conditions include: a temperature of 40-100° C., a stirring rate of 300-1000 rpm, and a time of 6-10 h.

[0017] Preferably, the precipitation conditions include: temperature of 15-30°C and time of 12-24h.

[0018] More preferably, the washing conditions include: washing the precipitated product with a detergent until it becomes neutral.

[0019] Further preferably, the drying conditions include: temperature of 100-120° C. and time of 12-24 h.

[0020] Preferably, the calcination conditions include: temperature of 350-750° C. and time of 2-6 h.

[0021] In a third aspect, the present invention provides an oxidation catalyst prepared by the preparation method described in the second aspect.

[0022] In a fourth aspect, the present invention provides a use of the oxidation catalyst described in the first aspect or the third aspect in catalyzing the oxidation of ethylene glycol to produce glycolic acid.

[0023] In a fifth aspect, the present invention provides a method for producing glycolic acid by oxidation of ethylene glycol, the method comprising: placing an oxidation catalyst and ethylene glycol in a high-pressure reactor, respectively, charging with oxygen, and performing a catalytic oxidation reaction, wherein:

[0024] The oxidation catalyst is the oxidation catalyst described in the first aspect or the third aspect.

[0025] Preferably, the weight ratio of the oxidation catalyst to ethylene glycol is 1:1-10.

[0026] More preferably, the mass concentration of the ethylene glycol is 8-12 g / mL.

[0027] Further preferably, the pressure of the oxygen is 0.1-1.0 MPa.

[0028] More preferably, the conditions of the catalytic oxidation reaction include: temperature of 180-240° C. and time of 1-5 h.

[0029] In the above technical scheme, the oxidation catalyst of the present invention uses Sb2O5 as a carrier and platinum oxide as an active component. By using an alkaline precipitant to regulate the generation morphology, structure and interaction of the active component with the carrier, the catalyst performance is significantly improved.

[0030] On the other hand, the present invention adopts a deposition precipitation method to prepare the oxidation catalyst. The oxidation catalyst exists in the form of oxides and only requires moderate calcination treatment, which simplifies the preparation process, shortens the catalyst preparation cycle, and the preparation process is simple, green and environmentally friendly.

[0031] At the same time, in the catalyst reaction system for selective oxidation of ethylene glycol to produce ethanolic acid used in the present invention, no additional alkaline reagent needs to be added, which significantly reduces the degree of environmental pollution. The system has excellent catalytic performance for producing ethanolic acid from ethylene glycol, the ethylene glycol conversion rate can reach 97.3%, and the ethanolic acid yield can reach 92%, which has broad application prospects.

[0032] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 is a scanning electron microscope image of the oxidation catalyst of the present invention. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0036] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0037] In a first aspect, the present invention provides an oxidation catalyst, characterized in that the carrier of the oxidation catalyst is Sb2O5, and the active component is platinum oxide; wherein,

[0038] The platinum oxide content in the oxidation catalyst is 0.1-5 wt%.

[0039] The oxidation catalyst of the present invention uses Sb2O5 as a carrier and platinum oxide as an active component. The generation form and structure of the active component and its interaction with the carrier are regulated by using an alkaline deposition agent, thereby significantly improving the catalyst performance.

[0040] In a preferred embodiment of the present invention, in order to better disperse and enrich the platinum oxide on the carrier surface, the platinum oxide in the oxidation catalyst is provided by one or two or more of platinum halide, platinum chlorate, platinum acetate, platinum sulfate, platinum nitrate and platinum ammine complex.

[0041] In a second aspect, the present invention provides a method for preparing an oxidation catalyst, which comprises: mixing Sb2O5 and a platinum salt in the presence of a liquid medium, adding an alkaline reagent, depositing, precipitating, washing, drying, and calcining.

[0042] The present invention adopts a deposition precipitation method to prepare the oxidation catalyst. The oxidation catalyst exists in the form of oxides and only needs to be moderately calcined, which simplifies the preparation process, shortens the catalyst preparation cycle, and the preparation process is simple, green and environmentally friendly.

[0043] In a preferred embodiment of the present invention, in order to better disperse and enrich the platinum oxide on the carrier surface, the platinum salt is selected from one or two or more of platinum halides, platinum chlorates, platinum acetates, platinum sulfates, platinum nitrates and platinum ammine complexes.

[0044] In a preferred embodiment of the present invention, in order to better reflect the environmental protection, economy and universality of the preparation method of the oxidation catalyst of the present invention, the liquid medium is water.

[0045] In a preferred embodiment of the present invention, in order to better enhance the generation of the platinum oxide precursor and the interaction between the platinum oxide precursor and the carrier, the alkaline agent is selected from one or two or more of urea, ammonia water, sodium carbonate and potassium carbonate.

[0046] In a preferred embodiment of the present invention, in order to promote the dispersion and deposition of platinum oxide on the surface of the carrier, the molar ratio of Sb2O5 to platinum salt is 1:0.15-10.

[0047] In a preferred embodiment of the present invention, in order to regulate the precipitation and deposition of the platinum salt in an aqueous environment and the interaction between the platinum salt and the carrier, the mass concentration of the alkaline agent is 0.1-1.0 g / mL.

[0048] In a preferred embodiment of the present invention, in order to facilitate the formation of platinum hydroxide, the deposition conditions include: a temperature of 40-100° C., a stirring rate of 300-1000 rpm, and a time of 6-10 h.

[0049] In a preferred embodiment of the present invention, in order to facilitate the formation and complete precipitation of platinum hydroxide, the precipitation conditions include: temperature of 15-30° C. and time of 12-24 h.

[0050] In a preferred embodiment of the present invention, in order to avoid the influence of the alkalinity of the carrier surface on the catalyst formation during the catalyst preparation process, the washing conditions include: washing the precipitated product with a detergent until it is neutral.

[0051] In a preferred embodiment of the present invention, in order to facilitate the formation and drying of platinum hydroxide, the drying conditions include: a temperature of 100-120° C. and a drying time of 12-24 hours.

[0052] In a preferred embodiment of the present invention, in order to facilitate the formation and distribution of platinum oxide crystal nuclei, the calcination conditions include: a temperature of 350-750° C. and a time of 2-6 hours.

[0053] In a third aspect, the present invention provides an oxidation catalyst prepared by the preparation method described in the second aspect.

[0054] In a fourth aspect, the present invention provides a use of the oxidation catalyst described in the first aspect or the third aspect in catalyzing the oxidation of ethylene glycol to produce glycolic acid.

[0055] In a fifth aspect, the present invention provides a method for producing glycolic acid by oxidizing ethylene glycol, the method comprising: placing an oxidation catalyst and ethylene glycol into a high-pressure reactor respectively, filling with oxygen, and performing a catalytic oxidation reaction, wherein the oxidation catalyst is the oxidation catalyst described in the first aspect or the third aspect.

[0056] In the catalyst reaction system for preparing glycolic acid by selective oxidation of ethylene glycol used in the present invention, no additional alkaline reagent needs to be added, which significantly reduces the degree of environmental pollution. The catalyst has excellent catalytic performance for preparing glycolic acid by ethylene glycol, the ethylene glycol conversion rate can reach 97.3%, and the glycolic acid yield can reach 92%, and the catalyst has broad application prospects.

[0057] In a preferred embodiment of the present invention, in order to enhance the catalytic conversion of the active centers of the catalyst on the reactant ethylene glycol molecules, the weight ratio of the oxidation catalyst to ethylene glycol is 1:1-10.

[0058] In a preferred embodiment of the present invention, the mass concentration of ethylene glycol is 8-12 g / mL.

[0059] In a preferred embodiment of the present invention, in order to regulate the effect of reaction pressure on the contact between reactant molecules and catalyst active centers, the pressure of the oxygen is 0.1-1.0 MPa.

[0060] In a preferred embodiment of the present invention, in order to regulate the occurrence of the oxidation reaction and avoid deep degradation of the product, the conditions of the catalytic oxidation reaction include: a temperature of 180-240° C. and a time of 1-5 h.

[0061] In a preferred embodiment of the present invention, room temperature refers to a temperature of 15-30°C.

[0062] The present invention will be described in detail below by way of examples. In the following examples, the drugs and medicaments are all conventional commercial products.

[0063] Example 1

[0064] (1) Weigh 10 g of commercial Sb2O5 powder and 0.14 g of chloroplatinic acid and mix with 30 ml of water, stir thoroughly for 1.0 h, then add an appropriate amount of 2 g of urea (the mass ratio of urea to carrier is 1:5), and heat the suspension to 80°C. After stirring thoroughly for 6 h, age at room temperature for 12 h, wash with deionized water until neutral, dry at 110°C for 24 h, and then place in a muffle furnace and roast at 650°C for 3 h and cool to obtain a Pt-based catalyst with a platinum oxide content of 0.75%, which is recorded as Cat 1.

[0065] Example 2

[0066] The implementation steps and conditions are the same as those of Example 1, except that 0.14 g of chloroplatinic acid is replaced with 0.096 g of nitric acid to prepare the corresponding oxidation catalyst, which is recorded as Cat 2.

[0067] Example 3

[0068] The implementation steps and conditions are the same as those of Example 1, except that the mass of chloroplatinic acid is replaced with 0.093 g to obtain the corresponding oxidation catalyst, which is recorded as Cat 3.

[0069] Example 4

[0070] The implementation steps and conditions are the same as those of Example 1, except that the calcination temperature is changed from 650° C. to 450° C. to obtain the corresponding oxidation catalyst, which is designated as Cat 4.

[0071] Example 5

[0072] The implementation steps and conditions are the same as those of Example 1, except that chloroplatinic acid is replaced with the corresponding sodium chloroplatinate to prepare the corresponding oxidation catalyst, which is recorded as Cat 5.

[0073] Example 6

[0074] The implementation steps and conditions are the same as those of Example 1, except that urea is replaced with ammonia water to prepare the corresponding oxidation catalyst, which is recorded as Cat 6.

[0075] Example 7

[0076] The implementation steps and conditions are the same as those in Example 1, except that the aging time is adjusted from 12 h to 24 h, and the corresponding oxidation catalyst is obtained, which is recorded as Cat 7.

[0077] Comparative Example 1

[0078] The implementation steps and conditions are the same as those of Example 1, except that the preparation method of the oxidation catalyst is changed to an impregnation method, and urea is not added to obtain the corresponding oxidation catalyst, which is recorded as Cat A.

[0079] Comparative Example 2

[0080] The implementation steps and conditions are the same as those in Example 1, except that the antimony oxide carrier is replaced with MCM-41 molecular sieve to prepare the corresponding oxidation catalyst, which is denoted as CatB.

[0081] Comparative Example 3

[0082] The implementation steps and conditions are the same as those in Example 1, except that the antimony oxide carrier is replaced with aluminum oxide to prepare the corresponding oxidation catalyst, which is recorded as Cat C.

[0083] Test Example 1

[0084] The oxidation catalyst prepared in Example 1 was tested by scanning electron microscope. The results are as follows: Figure 1 shown.

[0085] Depend on Figure 1 It can be seen that the platinum oxide particles of the oxidation catalyst of the present invention are clearly dispersed uniformly on the support.

[0086] Application Example 1

[0087] 30 ml of 10 mg / ml ethylene glycol solution was placed in a high-pressure reactor, and 0.2 g of the oxidation catalyst Cat 1 prepared in Example 1 was added thereto. Oxygen was then introduced into the reactor to make the gas pressure 0.5 MPa of oxygen. The reaction temperature was controlled at 220° C. The mixture was heated and stirred for 5 h. The mixture was cooled to room temperature and the filtrate was collected. The product was detected by high performance liquid chromatography (HPLC) on the reaction solution.

[0088] The above catalyst Cat 1 was replaced by Cat 2-7 and Cat AC respectively, and the other steps were the same.

[0089] The catalytic performance is shown in Table 1.

[0090] Table 1 Performance of ethylene glycol to glycolic acid on different catalysts

[0091]

[0092]

[0093] It can be seen from the above and Table 1 that the oxidation catalysts prepared in Examples 1-7 of the present invention have an ethylene glycol conversion rate of up to 97.3% and a ethylene glycol acid yield of up to 92% in the reaction of catalyzing ethylene glycol to produce glycolic acid.

[0094] At the same time, in the reaction of catalyzing ethylene glycol to produce glycolic acid, although the ethylene glycol conversion rate of the oxidation catalyst prepared by the impregnation method in Comparative Example 1 was 98.1%, the yield of glycolic acid was only 50%. In the reaction of catalyzing ethylene glycol to produce glycolic acid, the yield of glycolic acid was as low as 58.4% in the oxidation catalyst prepared by the deposition precipitation method of the present invention, indicating that the oxidation catalyst prepared by the preparation method of the present invention has significantly better catalytic performance than the oxidation catalyst prepared by the impregnation method in Comparative Example 1.

[0095] In addition, in the reaction of preparing glycolic acid from ethylene glycol using the oxidation catalyst prepared without antimony oxide as a carrier in Comparative Example 2, the yield of glycolic acid was only 37.4%, which was much lower than the yield of glycolic acid in the reaction of preparing glycolic acid from ethylene glycol using the oxidation catalyst prepared by the method of the present invention. In Comparative Example 3, the yield of glycolic acid in the reaction of preparing glycolic acid from ethylene glycol using the oxidation catalyst prepared by replacing the antimony oxide carrier with aluminum oxide was only 12.6%, indicating that the oxidation catalyst of the present invention has a more excellent catalytic performance.

[0096] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0097] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0098] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An oxidation catalyst, characterized in that The carrier of the oxidation catalyst is Sb2O5, and the active component is platinum oxide; wherein, The platinum oxide content in the oxidation catalyst is 0.1-5 wt%.

2. The oxidation catalyst according to claim 1, characterized in that The platinum oxide in the oxidation catalyst is provided by one or two or more of platinum halide, platinum chlorate, platinum acetate, platinum sulfate, platinum nitrate and platinum ammonia complex.

3. A method for preparing an oxidation catalyst, characterized in that: The preparation method comprises: In the presence of a liquid medium, Sb2O5 and a platinum salt are mixed, an alkaline agent is added, and the mixture is deposited, precipitated, washed, dried, and calcined.

4. The preparation method according to claim 3, characterized in that: The platinum salt is selected from one or two or more of platinum halides, platinum chlorates, platinum acetates, platinum sulfates, platinum nitrates and platinum ammonia complexes; Preferably, the liquid medium is water; More preferably, the alkaline agent is selected from one or two or more of urea, ammonia water, sodium carbonate and potassium carbonate.

5. The preparation method according to claim 3 or 4, characterized in that: The molar ratio of Sb2O5 to platinum salt is 1:0.15-10; Preferably, the mass concentration of the alkaline agent is 0.1-1.0 g / mL.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The deposition conditions include: temperature of 40-100°C, stirring rate of 300-1000rpm, and time of 6-10h; Preferably, the precipitation conditions include: temperature of 15-30°C and time of 12-24h; More preferably, the washing conditions include: washing the precipitated product with a detergent until it becomes neutral; Further preferably, the drying conditions include: temperature of 100-120° C. and time of 12-24 h.

7. The preparation method according to any one of claims 3 to 6, characterized in that: The calcination conditions include: a temperature of 350-750° C. and a time of 2-6 hours.

8. An oxidation catalyst prepared according to the preparation method according to any one of claims 3 to 7.

9. Use of the oxidation catalyst according to claim 1-2 or claim 8 in catalyzing the oxidation of ethylene glycol to produce glycolic acid.

10. A method for preparing glycolic acid by oxidation of ethylene glycol, characterized in that: The method comprises: The oxidation catalyst and ethylene glycol are placed in a high-pressure reactor, and oxygen is introduced to perform a catalytic oxidation reaction, wherein: The oxidation catalyst is the oxidation catalyst described in claim 1-2 or claim 8; Preferably, the weight ratio of the oxidation catalyst to ethylene glycol is 1:1-10; More preferably, the mass concentration of ethylene glycol is 8-12 g / mL; Further preferably, the pressure of the oxygen is 0.1-1.0 MPa; More preferably, the conditions of the catalytic oxidation reaction include: temperature of 180-240° C. and time of 1-5 h.

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