Preparation method and application of catalyst for preparing pyruvate by oxidative dehydrogenation of lactate

Abstract

The present invention relates to a method for preparing a catalyst for preparing pyruvate by oxidative dehydrogenation of lactate and its application. MoO x . The MoO x . The catalyst preparation method is simple and does not need to be loaded on other carriers, avoiding the problem of easy dissolution of active components of conventional supported catalysts. At the same time, the catalytic surface contains abundant oxygen defects, which can effectively catalyze the oxidative dehydrogenation of lactate to prepare pyruvate. Taking methyl lactate as an example, at 150°C, the conversion rate of methyl lactate can reach 98.2%, and the selectivity of methyl pyruvate can reach more than 90.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical catalytic materials, and particularly relates to a preparation method and application of a catalyst for preparing pyruvate by oxidative dehydrogenation of lactate. Background Art

[0002] Pyruvic acid and its esters are important chemical intermediates and are widely used in food additives, plastics, amino acids, and pharmaceuticals, attracting widespread attention. In industry, pyruvic acid is mainly prepared by dehydration and decarboxylation of tartaric acid, but a large amount of KHSO4 is required as a dehydrating agent in this process, which not only reduces production costs but also seriously pollutes the environment. Therefore, it is necessary to find a green and efficient production route for pyruvic esters.

[0003] Lactic acid and its esters are an important biomass platform compound that can be prepared by biomass fermentation. The structure of lactate ester is similar to that of pyruvate ester, so the preparation of pyruvate ester by oxidative dehydrogenation of lactate ester has higher atomic efficiency and good application prospects. At present, there have been many reports on the preparation of pyruvate ester by oxidative dehydrogenation of lactate ester, but there are multiple side reactions in this process, resulting in low selectivity of pyruvate ester. Therefore, the key to this reaction is to develop and design efficient multiphase catalysts. Currently, a variety of vanadium-based or titanium-based catalysts have been widely used to catalyze the reaction of lactate ester to pyruvate ester, such as V x O y / SBA-15 as a catalyst, the yield of ethyl pyruvate can reach 95% (Catalysis Science & Technology, 2023, 13, 5582-5591); using modified TS-1 molecular sieve as a catalyst, the yield of ethyl pyruvate can reach 95% (CN107930687A). However, there are few reports on the use of molybdenum-based catalysts in the liquid phase catalytic reaction of lactate to prepare pyruvate.

[0004] The present invention uses an organic vanadium salt as a precursor and prepares a highly efficient MoO2 catalyst for catalyzing the conversion of lactate to pyruvate through a simple high-temperature calcination (inert atmosphere) process. x Catalyst. The conversion rate of methyl lactate can reach 98.2%, and the selectivity of methyl pyruvate can reach more than 90.5%. Summary of the invention

[0005] The present invention provides a MoO2-catalyzed oxidative dehydrogenation method for preparing pyruvate x The catalyst does not need to be loaded on a carrier, thus avoiding the loss of active components. x The abundant oxygen defects in the catalyst improve the oxidizability of the catalyst, thereby improving the performance of the catalyst.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A MoO x The preparation method is carried out according to the following steps:

[0008] Put the molybdenum salt in a tube furnace, introduce gas, set a certain calcination temperature and calcine to obtain MoO x powder.

[0009] As a further limitation of the present invention, the molybdenum salt of the present invention is specifically molybdenum acetylacetonate, ammonium molybdate, and the like.

[0010] As a further limitation of the present invention, the gas of the present invention is nitrogen, argon, air or helium.

[0011] As a further limitation of the present invention, the calcination temperature of the present invention is 200-600° C., preferably 300° C., and the calcination time is 2-5 hours.

[0012] The MoO x The catalyst is used in the oxidative dehydrogenation reaction of lactate to prepare pyruvate according to the following method.

[0013] (1) Lactate, MoO x The catalyst and organic solvent are added to an intermittent high-pressure reactor, and the gas is replaced with oxygen and then filled with oxygen at an initial pressure of 0.2 to 1.8 MPa;

[0014] (2) Under stirring, the reaction temperature is set at 120° C. to 160° C. and the reaction time is 1 to 6 h. After the reaction is completed, the reactor is quickly cooled to room temperature and the product is analyzed by gas chromatography.

[0015] As a further limitation of the present invention, the MoO x The mass ratio of the catalyst to the lactic acid ester is 0.01-0.3; the mass ratio of ethyl lactate to the solvent is 0.01-0.2.

[0016] As a further limitation of the present invention, the organic solvent of the present invention is one of acetonitrile, acetone, diethyl succinate and DMF.

[0017] As a further limitation of the present invention, the reaction temperature of step (2) of the present invention is 150° C. and the reaction time is 6 hours.

[0018] As a further limitation of the present invention, the applicable applications are: methyl lactate is oxidized to obtain methyl pyruvate; ethyl lactate is oxidized to obtain ethyl pyruvate; and butyl lactate is oxidized to obtain butyl pyruvate.

[0019] The MoO provided by the present invention xThe preparation method of the catalyst has the following advantages compared with the traditional catalyst:

[0020] Under mild reaction conditions, MoO x The catalyst has good catalytic performance for the oxidative dehydrogenation of lactic esters. For example, a 98.2% conversion rate of methyl lactate can be achieved by reacting at 150°C for 6 hours, and the maximum selectivity for methyl pyruvate can reach more than 90.5%. At the same time, this method also has the advantages of simple catalyst preparation, cheap and easy-to-obtain raw materials, high atomic utilization, and wide substrate applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It's MoO x -XRD pattern of 300 catalyst;

[0022] Figure 2 For MoO x XPS pattern of -300 catalyst.

[0023] Figure 3 It's MoO x TEM image of -300 catalyst. DETAILED DESCRIPTION

[0024] The present invention will be further described with reference to the following examples, but it should be understood that these examples are only for illustration and should not be construed as limiting the implementation of the present invention. It should be noted that the substances used in the following examples are all conventional commercially available products.

[0025] In the present invention, MoO is synthesized by high temperature calcination under an inert atmosphere. x Catalysts can obtain different MoO x -T (T is the calcination temperature) catalyst.

[0026] Example 1-2

[0027] The effects of different molybdenum salt precursors on the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate are as follows:

[0028] MoO x Preparation of -300 catalyst:

[0029] MoO x -300 catalyst preparation scheme: Weigh molybdenum acetylacetonate or ammonium molybdate and put it into a tube furnace, introduce nitrogen, and heat the temperature from room temperature to 300℃ at 5.0℃ / min and maintain for 3h. The obtained black powder is denoted as MoO x -300. Figure 2 a It can be seen that MoO x There are no other impurities in the Figure 2 b Description MoO x There is also Mo 6+ and Mo 5+ .

[0030] 2mmol ethyl lactate, 50mg MoO x -300 catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150℃, and the reaction was stirred for 6h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0031] Table 1 Effect of molybdenum salt precursor type on ethyl lactate conversion and ethyl pyruvate selectivity

[0032]

[0033]

[0034] It can be seen from Table 1 that the catalysts synthesized with different molybdenum salt precursors have good catalytic effects on the catalytic oxidation of ethyl lactate to prepare ethyl pyruvate. x -300 catalyst precursor, the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate were the highest. Therefore, molybdenum acetylacetonate was used as MoO x precursor.

[0035] Embodiment 3-6

[0036] MoO synthesized at different calcination temperatures x The effect of catalyst on ethyl lactate conversion and ethyl pyruvate selectivity, the specific steps are as follows:

[0037] The catalysts of Examples 3-6 were prepared in the same manner as in Example 1, except that the calcination temperature was changed to 200°C to 600°C.

[0038] 2mmol ethyl lactate, 50mg MoO x -T catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150℃, and the reaction was stirred for 6h. After the reaction, the product was analyzed by gas chromatography for quantitative analysis.

[0039] Table 2 MoO x Effect of Calcination Temperature on Conversion of Ethyl Lactate and Selectivity of Ethyl Pyruvate

[0040] Example Calcination temperature Conversion rate (%) Selectivity (%) 3 200 78.9 85.3 1 300 92.1 90.3 4 400 87.4 91.5 5 500 80.1 93.4 6 600 74.5 92.6

[0041] Table 2 shows that MoO calcined at different calcination temperatures x-T catalyst has a great influence on the catalytic oxidation of ethyl lactate to prepare ethyl pyruvate. When the calcination temperature is 300℃, the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate are the highest.

[0042] Examples 7-10

[0043] MoO synthesized under different calcination atmospheres x The effect of catalyst on ethyl lactate conversion and ethyl pyruvate selectivity, the specific steps are as follows:

[0044] The catalyst preparation was the same as in Example 1, except that the nitrogen gas was replaced by air, argon or helium.

[0045] 2mmol ethyl lactate, 50mg MoO x -300 catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150℃, and the reaction was stirred for 6h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0046] Table 3 MoO x Effect of Calcination Atmosphere on Conversion of Ethyl Lactate and Selectivity of Ethyl Pyruvate

[0047] Example Roasting atmosphere Conversion rate (%) Selectivity (%) 1 <![CDATA[N2]]> 92.1 90.3 7 Air 45.7 85.9 8 Ar 91.9 89.8 9 He 92.3 90.5 10 <![CDATA[10%H2 / Ar]]> 54.9 72.5

[0048] Table 3 shows that MoO calcined under inert atmosphere x -300 catalyst has good catalytic performance for the oxidative dehydrogenation of ethyl lactate to prepare ethyl pyruvate, the conversion rate of ethyl lactate can reach more than 90%, and the selectivity of ethyl pyruvate is about 90%; while the catalyst prepared by air roasting has a conversion rate of ethyl lactate of only 45.7% and a selectivity of ethyl pyruvate of 85.9%; after roasting with 10% H2 / Ar mixed gas, the conversion rate of ethyl lactate is 54.9% and the selectivity of ethyl pyruvate is 72.5%.

[0049] Examples 11-13

[0050] The catalyst preparation was the same as in Example 1, and the effects of different reaction temperatures on the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate were studied. The specific steps were as follows:

[0051] 2mmol ethyl lactate, 50mg MoO x -300 catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 120-160℃, and the reaction was stirred for 6h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0052] Table 4 Effect of reaction temperature on ethyl lactate conversion and ethyl pyruvate selectivity

[0053] Example Reaction temperature (℃) Conversion rate (%) Selectivity (%) 11 120 41.3 92.3 12 140 78.7 91.5 1 150 92.1 90.3 13 160 93.4 88.7

[0054] Examples 14-17

[0055] The catalyst preparation was the same as in Example 1, and the effects of different reaction times on the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate were studied. The specific steps were as follows:

[0056] 2mmol ethyl lactate, 50mg MoO x -300 catalyst, 0.2MPaO2, and 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150°C, and after reacting for 1 to 6 hours, quantitative analysis was performed using gas chromatography.

[0057] Table 5 Effect of reaction time on ethyl lactate conversion and ethyl pyruvate selectivity

[0058]

[0059]

[0060] Examples 18-19

[0061] The catalyst preparation was the same as in Example 1, and the effects of different catalyst amounts on the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate were studied. The specific steps were as follows:

[0062] 2mmol ethyl lactate, 10-50mg MoO x -300 catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150℃, and the reaction was stirred for 6h. After the reaction, the product was quantitatively analyzed by gas chromatography.

[0063] Table 6 Effect of catalyst amount on ethyl lactate conversion and ethyl pyruvate selectivity

[0064] Example Catalyst amount (mg) Conversion rate (%) Selectivity (%) 18 10 42.7 90.8 19 30 75.2 89.9 1 50 92.1 90.3

[0065] Examples 20-22

[0066] The catalyst preparation was the same as in Example 1, and the effects of different solvents on the conversion rate of ethyl lactate and the selectivity of ethyl pyruvate were studied. The specific steps were as follows:

[0067] 2mmol ethyl lactate, 50mg MoO x -300 catalyst, 0.2MPaO2, 15mL solvent were placed in a 50mL intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 150℃, and the reaction was stirred for 6h. After the reaction, the product was analyzed quantitatively by gas chromatography.

[0068] Table 7 Effect of solvent on ethyl lactate conversion and ethyl pyruvate selectivity

[0069] Example Solvents Conversion rate (%) Selectivity (%) 20 acetone 88.2 89.5 21 Diethyl succinate 93.5 90.7 22 DMF 90.8 91.1

[0070] Embodiment 23-25

[0071] The catalyst preparation was the same as in Example 1, and the universality of the catalyst system on different substrates was studied. The specific steps were as follows:

[0072] 2mmol substrate, 50mgMoO x -300 catalyst, 0.2MPaO2, 15mL acetonitrile were placed in a 50ml intermittent high-pressure reactor, the reaction device was installed, the temperature was raised to 120℃, and the reaction was stirred for 2h. After the reaction, the product was analyzed quantitatively by gas chromatography.

[0073] Table 8 Effect of the universality of the catalyst system on different substrates

[0074] Example Substrate product Conversion rate (%) Selectivity (%) 23 Methyl lactate Methyl pyruvate 98.2 90.5 1 Ethyl lactate Ethyl pyruvate 92.1 90.3 24 Propyl lactate Propyl pyruvate 88.7 89.2 25 Butyl lactate Butyl pyruvate 80.6 88.9

[0075] Comparative Example 1

[0076] Commercial MoO2 is used as the catalyst, and the specific steps are as follows:

[0077] 2mmol ethyl lactate, 50mg catalyst, 0.2MPaO2, 15mL acetonitrile are placed in a 50mL intermittent autoclave, the reaction unit is installed, the temperature is raised to 150°C, the stirring reaction is performed for 6h, and the product analysis after the reaction is completed adopts gas chromatography for quantitative analysis. In the present embodiment, the conversion rate of ethyl lactate is 57.8%, and the selectivity of ethyl pyruvate is 67.3%.

[0078] Comparative Example 2

[0079] Commercial MoO3 is used as a catalyst, and the specific steps are as follows:

[0080] 2mmol ethyl lactate, 50mg catalyst, 0.2MPaO2, 15mL acetonitrile are placed in a 50mL intermittent autoclave, the reaction unit is installed, the temperature is raised to 150°C, the stirring reaction is performed for 6h, and the product analysis after the reaction is completed adopts gas chromatography for quantitative analysis. In the present embodiment, the conversion rate of ethyl lactate is 22.3%, and the selectivity of ethyl pyruvate is 82.5%.

[0081] Comparative Example 3

[0082] Supported 10% MoO xThe preparation process of the SBA-15 catalyst is as follows: a certain amount of molybdenum acetylacetonate is dissolved in 50 mL of acetonitrile, then 1 g of SBA-15 is added, and the mixture is stirred in an oil bath at 80 ° C until it is dried. Finally, the mixture is placed in a tubular furnace, nitrogen is introduced, and the temperature is raised from room temperature to 300 ° C at a rate of 5.0 ° C / min and maintained for 3 h to obtain 10% MoO x / SBA-15 catalyst.

[0083] 2mmol ethyl lactate, 50mg catalyst, 0.2MPaO2, 15mL acetonitrile are placed in a 50mL intermittent autoclave, the reaction unit is installed, the temperature is raised to 150°C, the stirring reaction is performed for 6h, and the product analysis after the reaction is completed adopts gas chromatography for quantitative analysis. In the present embodiment, the conversion rate of ethyl lactate is 49.9%, and the selectivity of ethyl pyruvate is 64.4%.

[0084] As can be seen from Tables 4-7, reaction conditions such as reaction temperature, time, catalyst dosage and solvent have a great influence on the reaction, but the selectivity of ethyl pyruvate is about 90%. Table 8 shows that the catalyst also has a good catalytic effect on other substrates (such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, etc.). The results of the examples and comparative examples show that the catalyst synthesized by this method is better than commercial molybdenum dioxide, molybdenum trioxide and supported MoO x The catalytic performance is good.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A MoO x The use of the catalyst in the oxidative dehydrogenation reaction of lactic acid ester is characterized in that: (1) Lactate, MoO x The catalyst and organic solvent are added to the reactor, and the gas is replaced with oxygen and then filled with oxygen at an initial pressure of 0.2-1.8 MPa; (2) Under stirring, set the reaction temperature to 120 ℃~160 ℃ and the reaction time to 1~6 h. After the reaction is completed, quickly cool the reactor to room temperature and collect the pyruvate product; Among them, MoO x The catalyst preparation method is as follows: a molybdenum salt is placed in a tube furnace and calcined under a gas atmosphere to obtain MoO x ; The gas atmosphere is a mixture of one or more of nitrogen, argon or helium; the molybdenum salt is molybdenum acetylacetonate or ammonium molybdate; the calcination temperature is 300~500 o C.

2. MoO according to claim 1 x The application of the catalyst in the oxidative dehydrogenation reaction of lactic acid ester is characterized by: The calcination time is 2~5h.

3. MoO according to claim 1 x The application of the catalyst in the oxidative dehydrogenation reaction of lactic acid ester is characterized by: The lactic acid ester is one of methyl lactate, ethyl lactate, propyl lactate and butyl lactate.

4. MoO according to claim 1 x The application of the catalyst in the oxidative dehydrogenation reaction of lactic acid ester is characterized by: MoO x The mass ratio of the catalyst to the lactic acid ester is 0.01-0.

3.

5. MoO according to claim 1 x The application of the catalyst in the oxidative dehydrogenation reaction of lactic acid ester is characterized by: The organic solvent is one of acetonitrile, acetone, diethyl succinate and DMF.

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