A preparation method of vinylene carbonate

Abstract

The present invention discloses a preparation method of vinylene carbonate. The preparation method includes: using ethylene carbonate as a raw material, under the irradiation of ultraviolet light with a wavelength of 157 - 365 nm and in the presence of a photocatalyst, using oxygen as an oxygen source to carry out an oxidation reaction to generate vinylene carbonate. This method can not only avoid some adverse consequences brought by the use of chlorine in the prior art, but also prepare vinylene carbonate in one step with a high yield, and the operation is relatively simple, green and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of synthesis technology, in particular to additives for lithium-ion battery electrolytes such as vinylene carbonate, and specifically to a preparation method of vinylene carbonate. Background Art

[0002] Vinylene Carbonate (VC for short) is a colorless transparent liquid, which is an organic synthesis intermediate and an additive for lithium-ion battery electrolytes. It can extend the cycle life of lithium-ion batteries and improve the charge and discharge performance of lithium batteries. It can also be used as a surface coating component or as a monomer for preparing polyvinylenecarbonate, and has broad market prospects. The chemical structural formula of vinylene carbonate is:

[0003]

[0004] Currently, the industrial production of vinylene carbonate uses ethylene carbonate (EC) as a raw material, which undergoes a chlorination reaction with chlorine to generate chloroethylene carbonate (CEC), and then dehydrochlorination is carried out with an inorganic base such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, or an organic base such as N,N-dimethylaniline, pyridine, N-methylmorpholine, triethylamine, etc. to produce vinylene carbonate. The main disadvantages of this process method are relatively long reaction time, low reaction yield, many by-products, obvious three wastes, and chlorine raw materials being dangerous goods, etc. Summary of the Invention

[0005] The object of the present invention is to overcome one or more deficiencies in the prior art, and provide an improved method for preparing vinylene carbonate. This method can not only avoid some adverse consequences brought by the use of chlorine in the prior art, but also prepare vinylene carbonate in one step with a high yield, and the operation is relatively simple.

[0006] Based on a large amount of research and experiments, the inventors of the present invention unexpectedly found that by using relatively green oxygen as an oxygen source, in the presence of a photocatalyst under the irradiation of ultraviolet light with a specific wavelength, vinylene carbonate can be prepared in one step, and an unexpectedly high yield is also obtained; further, the inventors analyzed that it should be that oxygen forms oxygen ions (O 2- ), peroxide ions (O2( 2- )) or superoxide ions (O2( - )) and other strongly oxidizing ions under the high-energy radiation of ultraviolet light, and these strongly oxidizing ions are used to oxidize the raw material ethylene carbonate under high-energy radiation to obtain vinylene carbonate with a high yield.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A preparation method of vinylene carbonate, the preparation method comprising:

[0009] Using ethylene carbonate as a raw material, under ultraviolet light irradiation with a wavelength of 157 - 365 nm and in the presence of a photocatalyst, using oxygen as an oxygen source, an oxidation reaction occurs to generate vinylene carbonate.

[0010] According to some preferred aspects of the present invention, controlling the wavelength of the ultraviolet light to be 157 - 165 nm, under the irradiation of ultraviolet light at this wavelength, a relatively higher yield can be obtained.

[0011] According to some preferred aspects of the present invention, controlling the oxidation reaction to be carried out at 55 - 95 °C.

[0012] Furthermore, controlling the oxidation reaction to be carried out at 60 - 95 °C.

[0013] Still further, controlling the oxidation reaction to be carried out at 70 - 90 °C.

[0014] In some embodiments of the present invention, controlling the oxidation reaction to be carried out at 85 - 90 °C.

[0015] According to the present invention, the oxygen source is pure oxygen gas (purity greater than 99%), a mixed gas composed of an inert gas and oxygen, or dry air. In some embodiments of the present invention, the inert gas can be nitrogen, argon, etc.

[0016] According to some preferred and specific aspects of the present invention, when the oxygen source is pure oxygen gas, the flow rate of the pure oxygen gas relative to the addition amount of ethylene carbonate is 0.2 - 1 L / (min·500 g), and further is 0.3 - 0.6 L / (min·500 g).

[0017] According to some preferred aspects of the present invention, the photocatalyst is nano - titanium dioxide, its particle size is 1 - 40 nm, further is 5 - 30 nm, and still further is 10 - 20 nm.

[0018] Furthermore, the molar ratio of the nano - titanium dioxide to the ethylene carbonate in the feed is 0.01 - 0.1∶1, and further is 0.015 - 0.05∶1.

[0019] In some preferred embodiments of the present invention, the embodiment of preparing the vinylene carbonate includes:

[0020] Adding ethylene carbonate and a photocatalyst into a photocatalytic reactor, heating to a preset temperature, turning on an ultraviolet lamp for ultraviolet light irradiation, and introducing an oxygen source into the photocatalytic reactor for reaction to generate vinylene carbonate.

[0021] Further, the power of the ultraviolet lamp is adjusted so that the wavelength of the ultraviolet light falls within a set wavelength range. According to the present invention, the greater the power of the ultraviolet lamp, the smaller the wavelength, and the smaller the power, the larger the wavelength. During actual operation, an ultraviolet lamp with adjustable power can be selected, and its power can be adjusted to control the wavelength. Alternatively, several ultraviolet lamps can be selected, with each ultraviolet lamp corresponding to a wavelength.

[0022] In some preferred embodiments, the preset temperature is 55 - 95°C, further 60 - 95°C, and still further 70 - 90°C. For example, it can be 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc.

[0023] In some preferred embodiments of the present invention, the reaction time of the oxidation reaction is controlled to be 4 - 12 hours. Compared with the existing preparation process, the preparation time is greatly shortened, and the production efficiency can be significantly improved.

[0024] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0025] The present invention can obtain vinylene carbonate by one-step oxidation method, which has the advantages of low cost, simple process operation, mild reaction conditions, less catalyst usage, and less three wastes on the basis of obtaining an ideal yield. Detailed implementation manners

[0026] The main concept of the present invention is to use relatively green and environmentally friendly and easily available oxygen as the oxygen source, and under the irradiation of ultraviolet light with a specific wavelength and in the presence of a photocatalyst, convert oxygen into some ionic states with higher oxidation ability (oxygen ions (O 2- ), peroxide ions (O2( 2- )) or superoxide ions (O2( - )) etc.). These ions efficiently oxidize ethylene carbonate under high-energy radiation to generate vinylene carbonate, which not only makes the preparation process relatively green and environmentally friendly, but also does not have difficult-to-treat or highly polluting three wastes, has low requirements for equipment, simple process operation, relatively mild reaction conditions, and less catalyst usage, making the overall process cost relatively low and facilitating industrial large-scale production.

[0027] Based on this, the present invention provides a method for preparing vinylene carbonate, which includes: using ethylene carbonate as a raw material, under the irradiation of ultraviolet light with a wavelength of 157 - 365 nm and in the presence of a photocatalyst, using oxygen as the oxygen source to carry out an oxidation reaction to generate vinylene carbonate.

[0028] In the present invention, not any wavelength of ultraviolet light can play a role, nor can any wavelength of ultraviolet light achieve an ideal effect; if the wavelength is too large or too small, it may affect the generation of strongly oxidizing ions and may even have a reverse effect on the oxidation of ethylene carbonate, and ultimately an ideal yield cannot be obtained. Through a large number of experimental studies, it is found that when the wavelength of ultraviolet light is in the range of 157 - 365 nm, a relatively ideal yield can basically be obtained. According to the present invention, the greater the power of the ultraviolet lamp, the smaller the wavelength, and the smaller the power, the larger the wavelength. During actual operation, an ultraviolet lamp with adjustable power can be selected, and the wavelength can be controlled by adjusting its power. Alternatively, several ultraviolet lamps can be selected, with each ultraviolet lamp corresponding to a wavelength. If the wavelength is controlled within the range of 157 - 165 nm, a relatively better yield can be obtained.

[0029] In the present invention, the oxidation reaction can be controlled to proceed at a relatively safe and easily achievable temperature, such as 55 - 95 °C, and a relatively ideal yield can be obtained; further, in the reaction system of ultraviolet light irradiation using oxygen as the oxygen source in the present invention, when the temperature is controlled within the range of 60 - 95 °C, the yield can be relatively good. When the temperature is close to about 90 °C, for example, fluctuating within about ±5 °C, controlling the wavelength within the range of 157 - 165 nm can be more conducive to the progress of the oxidation reaction and obtain a significantly excellent high yield.

[0030] The above - mentioned scheme will be further described below in conjunction with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited by the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0031] Unless otherwise specified in the following embodiments, all raw materials are obtained through commercial purchase or prepared by conventional methods in the art.

[0032] The ultraviolet lamps used in Examples 1 - 12 are the 4kW adjustable high - pressure mercury lamps for UV photocatalysis from Zhuozhou Prest Electric Equipment Co., Ltd., and the ultraviolet lamp used in Comparative Example 1 is the AF3 parallel light reactor from Shanghai Shanshi Technology Co., Ltd.

[0033] Nano - titanium dioxide is purchased from the anatase nano - titanium dioxide of Xuancheng Jingrui New Materials Co., Ltd., with a particle size of about 15 nm.

[0034] Ethylene carbonate is purchased commercially, with a purity of about 98%.

[0035] Example 1

[0036] This example provides a preparation method of vinylene carbonate, and the preparation method includes:

[0037] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0038] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 157 and 165 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate of 0.3 L / min) for the oxidation reaction;

[0039] (3) Stop after reacting for 8 hours, and use gas chromatography to detect that the content of vinylene carbonate in the reaction solution is 92.79%.

[0040] Comparative Example 1

[0041] Basically the same as Example 1, the only difference is that: adjust the power so that the wavelength range of the ultraviolet light source is > 365 nm. After the reaction stops, use gas chromatography to detect that the content of vinylene carbonate in the reaction solution is 62.39%.

[0042] Example 2

[0043] This example provides a method for preparing vinylene carbonate, and the preparation method includes:

[0044] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0045] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 157 and 165 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate of 0.4 L / min) for the oxidation reaction;

[0046] (3) Stop after reacting for 8 hours, and use gas chromatography to detect that the content of vinylene carbonate in the reaction solution is 93.82%.

[0047] Example 3

[0048] This example provides a method for preparing vinylene carbonate, and the preparation method includes:

[0049] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0050] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 157 and 165 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate of 0.5 L / min) for the oxidation reaction;

[0051] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 93.88%.

[0052] Example 4

[0053] This example provides a method for preparing vinylene carbonate, which includes:

[0054] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 60 °C and start stirring;

[0055] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 157 and 165 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.3 L / min) for oxidation reaction;

[0056] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 87.89%.

[0057] Example 5

[0058] This example provides a method for preparing vinylene carbonate, which includes:

[0059] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 60 °C and start stirring;

[0060] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 157 and 165 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.4 L / min) for oxidation reaction;

[0061] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 89.14%.

[0062] Example 6

[0063] This example provides a method for preparing vinylene carbonate, which includes:

[0064] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0065] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 165 and 254 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.3 L / min) for oxidation reaction;

[0066] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 84.05%.

[0067] Example 7

[0068] This example provides a method for preparing vinylene carbonate, which includes:

[0069] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0070] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 165 and 254 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.4 L / min) for oxidation reaction;

[0071] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 85.97%.

[0072] Example 8

[0073] This example provides a method for preparing vinylene carbonate, which includes:

[0074] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 60 °C and start stirring;

[0075] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 165 and 254 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.3 L / min) for oxidation reaction;

[0076] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 81.14%.

[0077] Example 9

[0078] This example provides a method for preparing vinylene carbonate, which includes:

[0079] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into the ultraviolet photocatalytic reactor, turn on the heating to 60 °C and start stirring;

[0080] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength range of the ultraviolet light source is between 165 and 254 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.4 L / min) for oxidation reaction;

[0081] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 82.28%.

[0082] Example 10

[0083] This example provides a method for preparing vinylene carbonate, which includes:

[0084] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0085] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength of the ultraviolet light source is between 254 and 365 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.3 L / min) for oxidation reaction;

[0086] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 80.34%.

[0087] Example 11

[0088] This example provides a method for preparing vinylene carbonate, which includes:

[0089] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 60 °C and start stirring;

[0090] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength of the ultraviolet light source is between 254 and 365 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.3 L / min) for oxidation reaction;

[0091] (3) After 8 hours of reaction, it was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 77.49%.

[0092] Example 12

[0093] This example provides a method for preparing vinylene carbonate, which includes:

[0094] (1) Add 500 g of ethylene carbonate (purity about 98%) and 6.82 g of nano-titanium dioxide into an ultraviolet photocatalytic reactor, turn on the heating to 90 °C and start stirring;

[0095] (2) Turn on the ultraviolet lamp, adjust the power so that the wavelength of the ultraviolet light source is between 254 and 365 nm, and then introduce pure oxygen gas (purity greater than 99.9%, flow rate 0.5 L / min) for oxidation reaction;

[0096] (3) After 8 hours of reaction, the reaction was stopped, and the content of vinylene carbonate in the reaction solution was detected by gas chromatography to be 81.24%.

[0097] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

[0098] In the ranges disclosed herein, the endpoints and any values are not limited to the exact 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, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A method for preparing vinylene carbonate, characterized in that, The preparation method includes: Using ethylene carbonate as a raw material, under ultraviolet light irradiation with a wavelength of 157 - 365 nm and in the presence of a photocatalyst, and using oxygen as an oxygen source, an oxidation reaction occurs to produce vinylene carbonate; Controlling the oxidation reaction to proceed at 55 - 95 °C, and the photocatalyst is nano-titanium dioxide.

2. The preparation method of vinylene carbonate according to claim 1, characterized in that, Controlling the wavelength of the ultraviolet light to be 157 - 165 nm.

3. The method for preparing vinylene carbonate according to claim 1 or 2, characterized in that, Controlling the oxidation reaction to proceed at 60 - 95 °C.

4. The method for preparing vinylene carbonate according to claim 3, wherein Controlling the oxidation reaction to proceed at 70 - 90 °C.

5. The method for preparing vinylene carbonate according to claim 1 or 2, characterized in that, The oxygen source is pure oxygen gas, a mixed gas composed of an inert gas and oxygen, or dry air.

6. The method for preparing vinylene carbonate according to claim 5, wherein When the oxygen source is pure oxygen gas, the flow rate of the pure oxygen gas relative to the addition amount of ethylene carbonate is 0.2 - 1 L / (min·500 g).

7. The method for preparing vinylene carbonate according to claim 6, characterized in that, When the oxygen source is pure oxygen gas, the flow rate of the pure oxygen gas relative to the addition amount of ethylene carbonate is 0.3 - 0.6 L / (min·500 g).

8. The method for preparing vinylene carbonate according to claim 1 or 2, characterized in that, The particle size of the nano-titanium dioxide is 1 - 40 nm.

9. The preparation method of vinylene carbonate according to claim 8, wherein, The particle size of the nano-titanium dioxide is 5 - 30 nm.

10. The method for preparing vinylene carbonate according to claim 9, characterized in that, The particle size of the nano-titanium dioxide is 10 - 20 nm.

11. The preparation method of vinylene carbonate according to claim 1, wherein The feeding molar ratio of the nano-titanium dioxide to the ethylene carbonate is 0.01 - 0.1∶1.

12. The method for preparing vinylene carbonate according to claim 11, characterized in that, The feeding molar ratio of the nano-titanium dioxide to the ethylene carbonate is 0.015 - 0.05∶1.

13. The method for preparing vinylene carbonate according to claim 1 or 2, characterized in that, The implementation method for preparing this vinylene carbonate includes: Adding ethylene carbonate and a photocatalyst into a photocatalytic reactor, heating to a preset temperature, turning on an ultraviolet lamp for ultraviolet light irradiation, and introducing an oxygen source into the photocatalytic reactor to react and produce vinylene carbonate.

14. The method for preparing vinylene carbonate according to claim 13, wherein Adjusting the power of the ultraviolet lamp so that the wavelength of the ultraviolet light is within a set wavelength range.

15. The method for preparing vinylene carbonate according to claim 1 or 2, characterized in that, Controlling the reaction time of the oxidation reaction to be 4 - 12 hours.

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