Oxidation catalyst and its preparation method and application

Abstract

The present invention discloses an oxidation catalyst, a preparation method thereof and an application thereof. The oxidation catalyst comprises a carrier and an active component supported on the carrier; the carrier is Sb6O 13 , and the active component is PdO. The oxidation catalyst has more oxygen vacancies, exhibits excellent catalytic oxidation performance, and can catalyze the selective preparation of glycolic acid from ethylene glycol. At the same time, the preparation method of the oxidation catalyst is simple and convenient, green and environmentally friendly, and can realize the efficient conversion of ethylene glycol to glycolic acid without adding an external base, reducing the degree of environmental pollution and having broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to an oxidation catalyst and a preparation method and application thereof. Background Art

[0002] Glycolic acid is an important organic compound. Because it contains a carboxyl group and a hydroxyl group in its molecule, it can be widely used as a raw material for organic synthesis. It has broad applications in chemical cleaning agents and pharmaceutical fields. In addition, glycolic acid can also be used as a monomer for the synthesis of polyglycolic acid, which is a synthetic polymer material with good biodegradability and biocompatibility, and is of great significance to environmental protection. As one of the important products of coal chemical industry, ethylene glycol can be partially oxidized to glycolic acid. In industry, the methods for preparing glycolic acid from ethylene glycol mainly include biocatalytic oxidation, electrochemical catalytic oxidation and chemical oxidation. The reaction conditions of biocatalytic oxidation are relatively mild, but it requires cell culture and has a long reaction cycle, which is not conducive to industrial production. Electrocatalytic oxidation reacts rapidly, but has high energy consumption and poor catalyst stability. This has led to a lot of attention in the research on the preparation of glycolic acid by chemical oxidation. The literature (Catalysis Science & Technology, 2017, 7 (11): 2371-2371.) synthesized Cu / CNF and Ni / CNF catalysts, which can catalyze the oxidation of ethylene glycol to glycolic acid under alkaline conditions, and the yield of glycolic acid is related to the alkali content. After reacting at 150°C-180°C for 15 hours, the ethylene glycol conversion rate reached 82%, and the glycolic acid selectivity reached up to 96%. The literature (Industrial & Engineering Chemistry Research, 2019, 58 (40): 18561-18568.) reported a Pt-Fe / CeO 2 Bimetallic catalysts can achieve the conversion of ethylene glycol to glycolic acid in a NaOH system. The yield of glycolic acid can reach 62% after reacting at 70°C for 4 hours. However, it is worth noting that most of the current reports on the catalytic oxidation of ethylene glycol to glycolic acid are limited to strong alkaline conditions such as NaOH and KOH, which can easily cause environmental pollution and serious equipment corrosion, thus limiting its industrial application.

[0003] Therefore, it is very meaningful and promising to develop a catalyst that can catalyze the oxidation of ethylene glycol to glycolic acid without using a strong base. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the current catalytic oxidation of ethylene glycol to produce glycolic acid is mostly limited to being carried out under strong alkaline conditions such as NaOH and KOH, which is easy to cause environmental pollution and serious equipment corrosion, thereby providing an oxidation catalyst and a preparation method and application thereof. The oxidation catalyst can catalyze ethylene glycol to selectively produce glycolic acid. At the same time, the preparation method of the oxidation catalyst is simple and convenient, green and environmentally friendly, and can achieve efficient conversion of ethylene glycol to glycolic acid without the addition of an alkali, thereby reducing the degree of environmental pollution and having broad application prospects.

[0005] In order to achieve the above object, the present invention provides an oxidation catalyst, which includes a carrier and an active component supported on the carrier;

[0006] The carrier is Sb 6 O 13 , the active component is PdO.

[0007] The present invention also provides a method for preparing an oxidation catalyst, the method comprising:

[0008] 1) Sb 2 O 5 Carrying out a calcination treatment to obtain an oxidation catalyst carrier;

[0009] 2) Mixing palladium salt with water, and then adding the oxidation catalyst support obtained in step 1), followed by stirring, impregnation, drying and calcining.

[0010] The present invention further provides an oxidation catalyst prepared by the above preparation method.

[0011] The present invention further provides an application of the above oxidation catalyst in preparing glycolic acid from ethylene glycol.

[0012] The present invention also provides a method for preparing glycolic acid from ethylene glycol, the method comprising: mixing ethylene glycol and oxygen for reaction in the presence of an oxidation catalyst;

[0013] Wherein, the oxidation catalyst is the above-mentioned oxidation catalyst.

[0014] In the above technical solution, the oxidation catalyst carrier of the present invention is Sb 6 O 13 The active component is PdO, wherein the content of PdO is 0.1-5wt%, and it has a large number of oxygen vacancies, showing excellent catalytic oxidation performance. When the PdO content increases moderately, the active centers increase, and the performance increases, and it can catalyze the oxidation of ethylene glycol to selectively produce glycolic acid.

[0015] At the same time, the oxidation catalyst is prepared by the classic impregnation method with simple reaction conditions and steps. It only needs to be calcined at 250-450°C and does not require a reduction step. The operation is easy and environmentally friendly.

[0016] Furthermore, the oxidation catalyst prepared by the present invention has excellent catalytic oxidation performance. Without the addition of additional alkaline reagents, it shows excellent catalytic oxidation performance for ethylene glycol, can selectively catalytically oxidize ethylene glycol to glycolic acid, significantly reduces the degree of environmental pollution, and has broad application prospects.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 is a SEM image of the oxidation catalyst Cat 1 prepared in Example 1;

[0020] Figure 2 is the SEM image of the calcined oxidation catalyst support. DETAILED DESCRIPTION

[0021] 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.

[0022] 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.

[0023] The present invention provides an oxidation catalyst, which comprises a carrier and an active component loaded on the carrier; the carrier is Sb 6 O 13 , the active component is PdO.

[0024] The oxidation catalyst of the present invention has excellent catalytic oxidation performance for ethylene glycol, and can efficiently and selectively catalytically oxidize ethylene glycol to generate glycolic acid without the addition of a strong base.

[0025] According to a preferred embodiment of the present invention, in order to make the oxidation catalyst have better catalytic oxidation performance of ethylene glycol, the content of PdO in the oxidation catalyst is 0.1-5wt%.

[0026] The present invention also provides a method for preparing an oxidation catalyst, the method comprising:

[0027] 1) Sb 2 O 5 Carry out calcination to obtain an oxidation catalyst carrier for standby use;

[0028] 2) Mixing palladium salt with water, and then adding the oxidation catalyst support obtained in step 1), followed by stirring, impregnation, drying and calcining.

[0029] The preparation method provided by the present invention is prepared by an impregnation method, which only requires a calcination process and does not require a reduction step. The prepared oxidation catalyst exists in the form of an oxide, which greatly reduces the production cost, is easy to operate, and is green and environmentally friendly.

[0030] In the method of the present invention, the Sb 2 O 5 The crystal phase structure is improved, the oxygen species in the carrier crystal is improved, and its oxidation ability to the reaction materials is improved. In a preferred embodiment, in step 1), the calcination conditions include: a temperature of 250-450°C and a time of 2-6 hours.

[0031] According to a preferred embodiment of the present invention, in order to further improve the catalytic performance of the oxidation catalyst, in step 2), the palladium salt is selected from one or more of palladium nitrate, palladium halide and palladium acetate.

[0032] According to a preferred embodiment of the present invention, in order to further improve the catalytic performance of the oxidation catalyst, in step 2), the weight ratio of the palladium salt to the oxidation catalyst carrier is 0.03-0.06:10, wherein the palladium salt is calculated as palladium ions.

[0033] According to a preferred embodiment of the present invention, in order to further improve the catalytic performance of the oxidation catalyst, in step 2), the solid-liquid ratio of water to the oxidation catalyst carrier is 15-25 mL:10 g.

[0034] According to a preferred embodiment of the present invention, in order to further improve the catalytic performance of the oxidation catalyst, in step 2), the stirring conditions include: a rotation speed of 300-1000 r / min and a time of 3-6 h.

[0035] In the method of the present invention, the catalyst obtained by the impregnation method effectively regulates the interaction between the Pd salt and the carrier, increases the reaction active center, and can achieve the conversion of ethylene glycol to glycolic acid by selective oxidation without the addition of a strong base. In a preferred embodiment, in step 2), the impregnation conditions include: a temperature of 15-30°C and a time of 6-12h.

[0036] According to a preferred embodiment of the present invention, in step 2), the drying conditions may be conventional conditions in the art, for example, the drying conditions include: a temperature of 100-120° C. and a time of 20-30 h.

[0037] According to a preferred embodiment of the present invention, in order to make the prepared oxidation catalyst have better catalytic oxidation performance, in step 2), the calcination conditions include: temperature of 250-450° C. and time of 2-6 h.

[0038] The present invention further provides an oxidation catalyst prepared by the above preparation method.

[0039] The present invention further provides an application of the above oxidation catalyst in preparing glycolic acid from ethylene glycol.

[0040] The present invention also provides a method for preparing glycolic acid from ethylene glycol, which comprises mixing ethylene glycol and oxygen for reaction in the presence of an oxidation catalyst;

[0041] Wherein, the oxidation catalyst is the above-mentioned oxidation catalyst.

[0042] In the catalyst reaction system used in the present invention, ethylene glycol can be catalytically oxidized to glycolic acid without the need to add additional alkaline reagents, which significantly reduces the degree of environmental pollution, is more environmentally friendly, and saves costs.

[0043] According to a preferred embodiment of the present invention, in order to convert more ethylene glycol into glycolic acid, the pressure of the oxygen is 0.1-1.0 MPa.

[0044] According to a preferred embodiment of the present invention, in order to enable the oxidation catalyst to better exert its catalytic oxidation performance and improve the reaction rate and yield, the weight ratio of the ethylene glycol to the oxidation catalyst is 0.3-4:2.

[0045] According to a preferred embodiment of the present invention, in order to convert more ethylene glycol into glycolic acid, the reaction conditions include: temperature of 180-240° C. and reaction time of 1-5 h.

[0046] 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.

[0047] Example 1

[0048] (1) Weigh 15g Sb 2 O 5 The powder was placed in a muffle furnace and calcined at 350°C for 2 h to obtain the oxidation catalyst carrier Sb 6 O 13 ;

[0049] (2) Weigh 0.07 g of palladium nitrate and dissolve it in 20 ml of deionized water. Then, place 10 g of the heat-treated support in step (1) into the palladium nitrate solution, stir thoroughly for 3 h, soak for 6 h, dry at 110° C. for 24 h, and then place in a muffle furnace and calcine at 350° C. for 2 h and cool to obtain an oxidation catalyst with a PdO content of 0.6 wt%, which is recorded as Cat 1.

[0050] Example 2

[0051] The method described in Example 1 was followed, except that 0.07 g of palladium nitrate in step (2) was replaced with 0.09 g of palladium chloride to obtain an oxidation catalyst having a PdO content of 0.6 wt %, which was recorded as Cat 2.

[0052] Example 3

[0053] The method described in Example 1 was followed, except that 0.07 g of palladium nitrate in step (2) was replaced with 0.05 g of palladium chloride to obtain an oxidation catalyst having a PdO content of 0.34 wt %, which was recorded as Cat 3.

[0054] Example 4

[0055] The method described in Example 1 was followed, except that the calcination temperature in step (2) was changed from 350° C. to 300° C., to obtain an oxidation catalyst having a PdO content of 0.6 wt %, which was designated as Cat 4.

[0056] Comparative Example 1

[0057] The method described in Example 1 was followed, except that Sb in step (1) 2 O 5 The powder was not calcined to obtain the corresponding Sb 2 O 5 The oxidation catalyst with a carrier is denoted as Cat A.

[0058] Comparative Example 2

[0059] The method described in Example 1 was followed, except that the Sb in step (1) was replaced by 2 O 5 Powder replaced with Sb 2O 3 , to obtain non-Sb 6 O 13 The oxidation catalyst used as the carrier is denoted as Cat B.

[0060] Test Example 1

[0061] The oxidation catalyst Cat 1 prepared in Example 1 and the calcined oxidation catalyst support were characterized by scanning electron microscopy. Figure 1-2 shown.

[0062] Depend on Figure 1-2 It can be seen that the calcined oxidation catalyst carrier exhibits a distinct spherical shape. After loading PdO, the spherical nanoparticle morphology does not change, which is one of the important factors to ensure the formation of the oxidation catalyst.

[0063] Application Example 1

[0064] 30 ml of 10 mg / ml ethylene glycol solution was placed in a high-pressure reactor, and 0.2 g of oxidation catalyst Cat 1 was added thereto. 0.7 MPa of oxygen was flushed into the reactor. The reaction temperature was controlled at 220°C, and the mixture was heated and stirred for 5 h. The mixture was cooled to room temperature, the filtrate was collected, and the reaction solution was detected by high performance liquid chromatography (HPLC).

[0065] The above oxidation catalyst Cat 1 is replaced by Cat 2-4 and Cat AB respectively, and the other steps are the same.

[0066] The catalytic performance of ethylene glycol reaction is shown in Table 1.

[0067] Table 1 Performance of ethylene glycol to glycolic acid on different oxidation catalysts

[0068] Oxidation Catalyst Ethylene glycol conversion rate (%) Glycolic acid yield (%) Cat 1 97.1 82.5 Cat 2 97.3 80.8 Cat 3 83.2 73.4 Cat 4 93.4 81.7 Cat A 76.1 58.1 Cat B 94.3 60.8

[0069] It can be seen from the above and Table 1 that the oxidation catalysts prepared in Examples 1-4 of the present invention and the oxidation catalysts prepared in Comparative Examples 1-2, under the same conditions, the oxidation catalysts prepared in the embodiments of the present invention, without the addition of additional base, have a conversion rate of ethylene glycol as high as 97.3% in the reaction of catalyzing the catalytic oxidation of ethylene glycol to glycolic acid, and a yield of glycolic acid as high as 82.5%.

[0070] Meanwhile, in Comparative Example 1, Sb 2 O 5 The yield of glycolic acid of the oxidized catalyst obtained by calcination was 58.1%. 2 O 5 The yield of glycolic acid of the oxidized catalyst obtained by calcination was 82.5%, and the yield of glycolic acid of the oxidized catalyst obtained by calcination was 82.5%. 2 O 3The ethanol acid yield of the obtained oxidation catalyst was 60.8%. 2 O 5 Calcination to generate Sb 6 O 13 The oxidation catalyst prepared as a carrier has better catalytic performance.

[0071] Application Example 2

[0072] The method described in Application Example 1 was used, except that only the oxidation catalyst Cat 1 was tested, and the ethylene glycol concentration was changed from 10 mg / mL to 40 mg / mL to obtain a corresponding reaction solution, which was tested by high performance liquid chromatography (HPLC). The catalytic ethylene glycol reaction performance is shown in Table 2.

[0073] Application Example 3

[0074] The method described in Application Example 1 was used, except that only the oxidation catalyst Cat 1 was tested, and the ethylene glycol concentration was changed from 10 mg / mL to 1 mg / mL to obtain a corresponding reaction solution, which was tested by high performance liquid chromatography (HPLC). The catalytic ethylene glycol reaction performance is shown in Table 2.

[0075] Application Example 4

[0076] The method described in Application Example 1 was used, except that only the oxidation catalyst Cat 1 was tested, and the oxygen pressure was changed from 0.7 MPa to 1.0 MPa to obtain a corresponding reaction solution, which was tested by high performance liquid chromatography (HPLC). The catalytic performance of the ethylene glycol reaction is shown in Table 2.

[0077] Application Example 5

[0078] The method described in Application Example 1 was followed, except that only the oxidation catalyst Cat 1 was tested, and the reaction temperature was increased to 240°C to obtain a corresponding reaction solution, which was tested using a high performance liquid chromatography (HPLC). The catalytic performance of the ethylene glycol reaction is shown in Table 2.

[0079] Table 2 Catalytic performance of ethylene glycol reaction of the oxidation catalyst prepared in Example 1 under different reaction conditions

[0080] Ethylene glycol conversion rate (%) Glycolic acid yield (%) Application Example 2 59.7 55.2 Application Example 3 98 66.8 Application Example 4 96.1 76.6 Application Example 5 91.7 52.9

[0081] It can be seen from the data in Table 2 that the oxidation catalyst provided by the present invention has stable performance and can still maintain a relatively high ethylene glycol conversion rate and glycolic acid yield under changing reaction conditions such as ethylene glycol concentration, oxygen pressure and reaction temperature.

[0082] 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.

[0083] 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.

[0084] 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. A method for preparing glycolic acid from ethylene glycol, It is characterized in that The method comprises: mixing ethylene glycol and oxygen for reaction in the presence of an oxidation catalyst; Wherein, the oxidation catalyst comprises a carrier and an active component supported on the carrier; The carrier is Sb 6 O 13 , the active component is PdO; The content of PdO in the oxidation catalyst is 0.1-5wt%.

2. The method according to claim 1, It is characterized in that The preparation method of the oxidation catalyst comprises: 1) Sb 2 O 5 The oxidation catalyst carrier Sb 6 O 13 ; 2) The palladium salt is mixed with water and then added to the oxidation catalyst support obtained in step 1), followed by stirring, impregnation, drying and calcination.

3. The method according to claim 2, It is characterized in that In step 1), the calcination conditions include: temperature of 250-450° C. and time of 2-6 hours.

4. The method according to claim 2 or 3, It is characterized in that In step 2), the palladium salt is selected from one or more of palladium nitrate, palladium halide and palladium acetate.

5. The method according to claim 2, It is characterized in that In step 2), the weight ratio of the palladium salt to the oxidation catalyst carrier is 0.03-0.06:10, wherein the palladium salt is calculated as palladium ions.

6. The method according to claim 2, It is characterized in that In step 2), the solid-liquid ratio of water to the oxidation catalyst carrier is 15-25 mL:10 g.

7. The method according to claim 2, It is characterized in that In step 2), the stirring conditions include: a rotation speed of 300-1000 r / min and a time of 3-6 hours.

8. The method according to claim 2, It is characterized in that In step 2), the immersion conditions include: temperature of 15-30° C. and time of 6-12 hours.

9. The method according to claim 2, It is characterized in that In step 2), the calcination conditions include: temperature of 250-450° C. and time of 2-6 hours.

10. The method according to claim 1, It is characterized in that The pressure of the oxygen is 0.1-1.0Mpa.

11. The method according to claim 1, It is characterized in that The weight ratio of the ethylene glycol to the oxidation catalyst is 0.3-4:

2.

12. The method according to claim 1, It is characterized in that The reaction conditions include: temperature of 180-240° C. and time of 1-5 h.

Images