A modified ZnO nanosieve and a preparation method thereof and a modified synthetic ester insulating oil and a preparation method thereof

Abstract

The present invention belongs to the technical field of insulating oil additives, and provides a modified ZnO nanosieve and a preparation method thereof, and a modified synthetic ester insulating oil and a preparation method thereof. The preparation of the modified ZnO nanosieve provided by the present invention comprises the following steps: S1, zinc salt, urea, sodium carbonate and water are mixed and then subjected to hydrothermal reaction to obtain a reaction product; S2, the reaction product is sequentially subjected to centrifugation, washing and drying treatment to obtain a ZnO nanoprecursor; S3, the ZnO nanoprecursor is subjected to calcination treatment to obtain a ZnO nanosieve; S4, ZnO nanosieve, oleic acid and ethanol are mixed to obtain a mixture, and the mixture is sequentially subjected to centrifugation, washing and drying treatment to obtain a modified ZnO nanosieve. The modified ZnO nanosieve has a higher specific surface area, and using it to modify the synthetic ester insulating oil can improve the insulating performance of the synthetic ester insulating oil.

Description

Technical Field

[0001] The invention relates to the technical field of insulating oil additives, and in particular to a modified ZnO nanosieve and a preparation method thereof, and a modified synthetic ester insulating oil and a preparation method thereof. Background Art

[0002] At present, environmentally friendly synthetic ester insulating oil with renewable and degradable characteristics has become one of the preferred insulating oils for oil-immersed transformers. In order to make transformer oil meet the needs of low-carbon environmental protection while further enhancing the electrical strength, the most commonly used method is to modify natural ester insulating oil. Modifying natural ester insulating oil by adding nanomaterials is one of the methods to improve the breakdown strength of oil. Since different nanomaterials have differences in volume effect, surface effect, polarization phenomenon and other characteristics, their effects in insulating oil are also different. When nanoparticles are polarized under the action of an electric field, they will form traps that capture electrons and slow down the development speed of streamers. Nanomaterials with high specific surface areas usually have more significant surface effects and better effects on improving the breakdown voltage of insulating oil.

[0003] At present, the modification method using nanomaterials is mostly seen in mineral insulating oils, while the main components, physical and chemical properties, and dielectric properties of synthetic ester insulating oils are different from those of mineral oils. The performance of nanomaterials in synthetic ester oils must be different, and its mechanism of action needs to be studied. In addition, it is difficult to further increase the specific surface area by simply changing the type of nanomaterials. The morphology of nanoparticles needs to be changed to obtain a higher specific surface area, thereby achieving a better breakdown voltage improvement effect.

[0004] Therefore, how to provide a nanomaterial with a high specific surface area for the modification of synthetic ester insulating oil has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In view of this, the present invention provides a modified ZnO nanosieve and a preparation method thereof and a modified synthetic ester insulating oil and a preparation method thereof, which aims to solve the technical problems of small specific surface area and poor surface effect of existing nanomaterials.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for preparing a modified ZnO nanosieve, comprising the following steps:

[0008] S1, mixing zinc salt, urea, sodium carbonate and water and performing a hydrothermal reaction to obtain a reaction product;

[0009] S2, the reaction product is sequentially centrifuged, washed and dried to obtain a ZnO nano precursor;

[0010] S3, calcining the ZnO nano precursor to obtain a ZnO nanosieve;

[0011] S4. The ZnO nanosieve, oleic acid and ethanol are mixed to obtain a mixture, and the mixture is sequentially centrifuged, washed and dried to obtain a modified ZnO nanosieve.

[0012] Furthermore, in step S1, the zinc salt is zinc nitrate hexahydrate or zinc acetate dihydrate; the mass volume ratio of the zinc salt, urea, sodium carbonate and water is 1-2 g: 0.1-1 g: 0.1-1 g: 40-80 mL;

[0013] The temperature of the hydrothermal reaction is 140-160° C., and the time of the hydrothermal reaction is 18-36 hours.

[0014] Furthermore, in step S3, the calcination temperature is 800-900° C., the calcination time is 3-4 hours, and the calcination atmosphere is argon or nitrogen.

[0015] Furthermore, in step S4, the mass volume ratio of ZnO nanosieve, oleic acid and ethanol is 1-2 g: 1-5 mL: 70-100 mL;

[0016] The mixing temperature is 40-60° C., and the mixing time is 20-30 hours.

[0017] The invention provides a modified ZnO nanosieve prepared by the preparation method.

[0018] The present invention provides a method for preparing modified synthetic ester insulating oil by using the modified ZnO nanosieve, comprising the following steps:

[0019] The modified ZnO nanosieve and the synthetic ester insulating oil are mixed to obtain a mixture, and the mixture is dried to obtain the modified synthetic ester insulating oil;

[0020] The modified ZnO nanosieve accounts for 0.01-0.1 vol% of the modified synthetic ester insulating oil.

[0021] Furthermore, the synthetic ester insulating oil is TMP triester or PETP tetraester.

[0022] Furthermore, the TMP triester is synthesized by esterification reaction of medium-chain fatty acids and trimethylolpropane;

[0023] The PETP tetraester is synthesized by esterification reaction of medium-chain fatty acid and pentaerythritol.

[0024] Furthermore, the mixing is performed under ultrasound, the mixing temperature is 20 to 50° C., and the mixing time is 0.5 to 3 hours.

[0025] The invention provides modified synthetic ester insulating oil prepared by the preparation method.

[0026] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] Compared with nanoparticles of traditional structures, the modified ZnO nanosieve prepared by the present invention has a larger specific surface area, a more significant surface effect, and a higher efficiency in capturing free electrons generated by ionization in oil under the action of an electric field.

[0028] The modified synthetic ester insulating oil prepared by the present invention has higher breakdown voltage and volume resistivity, indicating that its insulating performance is very excellent. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a modified ZnO nanosieve, comprising the following steps:

[0030] S1, mixing zinc salt, urea, sodium carbonate and water and performing a hydrothermal reaction to obtain a reaction product;

[0031] S2, the reaction product is sequentially centrifuged, washed and dried to obtain a ZnO nano precursor;

[0032] S3, calcining the ZnO nano precursor to obtain a ZnO nanosieve;

[0033] S4. The ZnO nanosieve, oleic acid and ethanol are mixed to obtain a mixture, and the mixture is sequentially centrifuged, washed and dried to obtain a modified ZnO nanosieve.

[0034] In the present invention, in step S1, the zinc salt is zinc nitrate hexahydrate or zinc acetate dihydrate, preferably zinc nitrate hexahydrate; the mass volume ratio of the zinc salt, urea, sodium carbonate and water is 1-2g:0.1-1g:0.1-1g:40-80mL, preferably 1g:0.2-0.8g:0.2-0.8g:50-70mL, more preferably 1g:0.4-0.6g:0.4-0.6g:60-65mL; ​​the temperature of the hydrothermal reaction is 140-160°C, preferably 145-156°C, more preferably 150-155°C; the time of the hydrothermal reaction is 18-36h, preferably 20-35h, more preferably 25-30h.

[0035] In the present invention, in step S2, the centrifugation time is 10 to 30 minutes, preferably 12 to 25 minutes, and more preferably 15 to 20 minutes; when washing, first wash with water, then wash with anhydrous ethanol, and repeat 3 to 5 times, preferably 4 times; the drying temperature is 50 to 70°C, preferably 54 to 66°C, and more preferably 55 to 60°C; the drying time is 20 to 30 hours, preferably 22 to 28 hours, and more preferably 24 to 26 hours.

[0036] In the present invention, in step S3, the calcination temperature is 800-900°C, preferably 820-880°C, and more preferably 840-860°C; the calcination time is 3-4h, preferably 3.5h; the calcination atmosphere is argon or nitrogen, preferably nitrogen.

[0037] In the present invention, in step S4, the mass volume ratio of ZnO nanosieve, oleic acid and ethanol is 1-2g:1-5mL:70-100mL, preferably 1g:2-4mL:80-90mL, and more preferably 1g:3mL:85mL; the mixing temperature is 40-60°C, preferably 43-56°C, and more preferably 46-52°C; the mixing time is 20-30h, preferably 22-28h, and more preferably 24-26h.

[0038] In the present invention, in step S4, the centrifugation time is 10 to 30 minutes, preferably 12 to 25 minutes, and more preferably 15 to 20 minutes; when washing, first wash with water, then wash with anhydrous ethanol, and repeat 3 to 5 times, preferably 4 times; the drying temperature is 50 to 70°C, preferably 54 to 66°C, and more preferably 55 to 60°C; the drying time is 20 to 30 hours, preferably 22 to 28 hours, and more preferably 24 to 26 hours.

[0039] The invention provides a modified ZnO nanosieve prepared by the preparation method.

[0040] The present invention provides a method for preparing modified synthetic ester insulating oil by using the modified ZnO nanosieve, comprising the following steps:

[0041] The modified ZnO nanosieve and the synthetic ester insulating oil are mixed to obtain a mixture, and the mixture is dried to obtain the modified synthetic ester insulating oil.

[0042] In the present invention, the modified ZnO nanosieve accounts for 0.01 to 0.1 vol%, preferably 0.02 to 0.08 vol%, and more preferably 0.04 to 0.06 vol% of the modified synthetic ester insulating oil.

[0043] In the present invention, the synthetic ester insulating oil is TMP triester or PETP tetraester, preferably TMP triester.

[0044] In the present invention, the TMP triester is synthesized by esterification reaction between medium-chain fatty acids and trimethylolpropane; and the PETP tetraester is synthesized by esterification reaction between medium-chain fatty acids and pentaerythritol.

[0045] In the present invention, the mixing is carried out under ultrasound, the mixing temperature is 20-50°C, preferably 25-45°C, more preferably 30-40°C; the mixing time is 0.5-3h, preferably 1-2.5h, more preferably 1.5-2h.

[0046] In the present invention, the temperature of the drying treatment is 80 to 100°C, preferably 85 to 96°C, and more preferably 88 to 92°C.

[0047] The invention provides modified synthetic ester insulating oil prepared by the preparation method.

[0048] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] Take 1g of Zn(NO 3 ) 2 6H 2 O, 0.5g of Na 2 CO 3 and 0.3 g of CO(NH 2 ) 2 The solid particles were mixed in 40 mL of deionized water and stirred for 20 min to ensure that the solid was completely dissolved; the mixed solution was transferred to a reactor and sealed, and reacted in a constant temperature environment of 150°C for 24 h by heating in an oil bath; the reaction product was centrifuged in a centrifuge for 20 min; then the precipitate was washed with water first, and then washed with anhydrous ethanol, and repeated 3 times; after washing, it was placed in a vacuum drying oven and dried at 60°C for 24 h to obtain a ZnO nanosieve precursor; the ZnO nanosieve precursor was calcined at 850°C in an argon atmosphere using a tubular furnace to remove impurity ions in the precursor, and the calcination time was 200 min. After cooling, the calcined product was taken out to obtain a ZnO nanosieve.

[0051] Take 1g ZnO nanosieve and 2mL oleic acid and add them to 80mL ethanol solution and mix them evenly. Use an ultrasonic oscillator to ultrasonically oscillate the mixed solution at 50℃ for 24h; use a centrifuge to centrifuge the oscillated mixture for 10min; then wash it with water first, then wash the solid obtained by centrifugation with anhydrous ethanol, and repeat 3 times. Place the solid in a vacuum drying oven and dry it for 24h at 60℃. After drying, the modified ZnO nanosieve is obtained.

[0052] Example 2

[0053] Take 1g of C 4 H 6 O 4 Zn·2H 2 O, 0.6g of Na 2 CO 3 and 0.4 g of CO(NH 2 ) 2 The solid particles were mixed in 40 mL of deionized water and stirred for 20 min to ensure that the solid was completely dissolved; the mixed solution was transferred to a reactor and sealed, and reacted in a constant temperature environment of 160°C for 20 h by heating in an oil bath; the reaction product was centrifuged in a centrifuge for 20 min; then the precipitate was washed with water first, and then washed with anhydrous ethanol, and repeated 4 times; after washing, it was placed in a vacuum drying oven and dried at 60°C for 24 h to obtain a ZnO nanosieve precursor; the ZnO nanosieve precursor was calcined at 900°C in an argon atmosphere using a tubular furnace to remove impurity ions in the precursor, and the calcination time was 180 min. After cooling, the calcined product was taken out to obtain a ZnO nanosieve.

[0054] Take 1g ZnO nanosieve and 3mL oleic acid and add them to 90mL ethanol solution and mix them evenly. Use an ultrasonic oscillator to ultrasonically oscillate the mixed solution at 50℃ for 25h; use a centrifuge to centrifuge the oscillated mixture for 15min; then wash it with water first, then wash the solid obtained by centrifugation with anhydrous ethanol, and repeat 4 times. Place the solid in a vacuum drying oven and dry it for 24h at 60℃. After drying, the modified ZnO nanosieve is obtained.

[0055] Example 3

[0056] The modified ZnO nanosieve obtained in Example 1 was added to the TMP triester insulating oil, and the oil sample was ultrasonically dispersed using an ultrasonic oscillator and oscillated for 1 hour until a clear fluid was formed. The clarified fluid after ultrasonic dispersion was dried at 90° C. for 48 hours under a vacuum environment using a vacuum drying oven to obtain a modified TMP triester insulating oil, wherein the modified ZnO nanosieve accounted for 0.03 vol% of the modified TMP triester insulating oil.

[0057] Example 4

[0058] The preparation steps of the modified TMP triester insulating oil are the same as those of Example 3, except that the modified ZnO nanosieve is prepared according to Example 2.

[0059] Example 5

[0060] The preparation steps of the modified TMP triester insulating oil are the same as those of Example 3, except that the modified ZnO nanosieve accounts for 0.06 vol% of the modified TMP triester insulating oil.

[0061] Example 6

[0062] The modified ZnO nanosieve obtained in Example 1 was added to the PETP tetraester insulating oil, and the oil sample was ultrasonically dispersed using an ultrasonic oscillator and oscillated for 1 hour until a clear fluid was formed. The clarified fluid after ultrasonic dispersion was dried at 90° C. for 48 hours under a vacuum environment using a vacuum drying oven to obtain a modified PETP tetraester insulating oil, wherein the modified ZnO nanosieve accounted for 0.03 vol% of the modified PETP tetraester insulating oil.

[0063] Example 7

[0064] The preparation steps of the modified PETP tetraester insulating oil are the same as those of Example 6, except that the modified ZnO nanosieve is prepared according to Example 2.

[0065] Example 8

[0066] The preparation steps of the modified PETP tetraester insulating oil are the same as those of Example 6, except that the modified ZnO nanosieve accounts for 0.06 vol% of the modified PETP tetraester insulating oil.

[0067] Comparative Example 1

[0068] Take 1g of ordinary ZnO nanoparticles and 2mL of oleic acid and add them to 80mL of ethanol solution and mix them evenly. Use an ultrasonic oscillator to ultrasonically oscillate the mixed solution at 50℃ for 24h; use a centrifuge to centrifuge the oscillated mixture for 10min; then wash it with water first, then wash the solid obtained by centrifugation with anhydrous ethanol, and repeat 3 times. Place the solid in a vacuum drying oven and dry it for 24h at 60℃. After drying, the modified ZnO nanoparticles are obtained.

[0069] The obtained modified ZnO nanoparticles were added to TMP triester insulating oil, and the oil sample was ultrasonically dispersed using an ultrasonic oscillator, and oscillated for 1 hour until a clear fluid was formed. The clarified fluid after ultrasonic dispersion was dried at 90°C for 48 hours under a vacuum environment using a vacuum drying oven to obtain a modified TMP triester insulating oil, wherein the modified ZnO nanoparticles accounted for 0.03 vol% of the modified TMP triester insulating oil.

[0070] Comparative Example 2

[0071] The preparation steps of the modified TMP triester insulating oil are the same as those of Comparative Example 1, except that the modified ZnO nanoparticles account for 0.06 vol% of the modified TMP triester insulating oil.

[0072] Comparative Example 3

[0073] The present comparative example prepares modified PETP tetraester insulating oil, and the PETP tetraester insulating oil is used to replace the TMP triester insulating oil in comparative example 1, and the remaining steps are the same as those in comparative example 1.

[0074] Comparative Example 4

[0075] The preparation steps of the modified PETP tetraester insulating oil are the same as those of Comparative Example 3, except that the modified ZnO nanoparticles account for 0.06 vol% of the modified PETP tetraester insulating oil.

[0076] Comparative Example 5

[0077] The modified ZnO nanosieve obtained in Example 1 was added to Karamay #25 mineral insulating oil, and the oil sample was ultrasonically dispersed using an ultrasonic oscillator and oscillated for 1 hour until a clear fluid was formed. The clarified fluid after ultrasonic dispersion was dried at 90°C for 48 hours under a vacuum environment using a vacuum drying oven to obtain a modified mineral insulating oil, wherein the modified ZnO nanosieve accounted for 0.06 vol% of the modified mineral insulating oil.

[0078] Comparative Example 6

[0079] The preparation steps of the modified TMP triester insulating oil are the same as those of Example 3, except that the modified ZnO nanosieve accounts for 0.12 vol% of the modified TMP triester insulating oil.

[0080] Comparative Example 7

[0081] The preparation steps of the modified PETP tetraester insulating oil are the same as those of Example 6, except that the modified ZnO nanosieve accounts for 0.12 vol% of the modified PETP tetraester insulating oil.

[0082] Performance Testing

[0083] The power frequency breakdown voltage, dielectric loss factor at 90°C, relative dielectric constant and volume resistivity of TMP triester insulating oil, PETP tetraester insulating oil, Karamay #25 mineral insulating oil, products of Examples 3 to 8 and Comparative Examples 1 to 7 were measured using an insulating oil dielectric strength tester and a dielectric loss tester, respectively. The test results are shown in Table 1.

[0084] Table 1 Performance test results of insulating oil

[0085]

[0086]

[0087] It can be seen from Table 1 that, under the same concentration, the modified ZnO nanosieve prepared by the present invention has a more significant effect on improving the breakdown voltage and volume resistivity of the synthetic ester insulating oil than ordinary nano ZnO particles, indicating that the modified ZnO nanosieve prepared by the present invention can greatly improve the insulation performance of the synthetic ester insulating oil.

[0088] When the concentration of modified ZnO nanosieve is 0.12 vol%, the breakdown voltage of the two modified synthetic ester insulating oils is increased at a low level and the dielectric loss is large, indicating that it is not advisable to add too many nanosieve particles to avoid agglomeration. In addition, the effect of modified ZnO nanosieve in mineral oil is not as obvious as in synthetic ester. This is because mineral oil and synthetic ester have great differences in structure, resulting in different polarization phenomena of modified ZnO nanosieve in the two oils, and different numbers of captured electrons, so the effects are different, indicating that modified ZnO nanosieve is more suitable for synthetic ester insulating oil.

[0089] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0090] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a modified ZnO nanosieve, characterized in that: The following steps are involved: S1, mixing zinc salt, urea, sodium carbonate and water and performing a hydrothermal reaction to obtain a reaction product; S2, the reaction product is sequentially centrifuged, washed and dried to obtain a ZnO nano precursor; S3, calcining the ZnO nano precursor to obtain a ZnO nanosieve; S4, mixing the ZnO nanosieve, oleic acid and ethanol to obtain a mixture, and sequentially centrifuging, washing and drying the mixture to obtain a modified ZnO nanosieve; The temperature of the hydrothermal reaction is 140-160° C., and the time of the hydrothermal reaction is 18-36 hours; In the step S3, the calcination temperature is 800-900° C., the calcination time is 3-4 hours, and the calcination atmosphere is argon or nitrogen.

2. The preparation method according to claim 1, characterized in that: In the step S1, the zinc salt is zinc nitrate hexahydrate or zinc acetate dihydrate; the mass volume ratio of the zinc salt, urea, sodium carbonate and water is 1-2g:0.1-1g:0.1-1g:40-80mL.

3. The preparation method according to claim 1, characterized in that: In step S4, the mass volume ratio of ZnO nanosieve, oleic acid and ethanol is 1-2 g: 1-5 mL: 70-100 mL; The mixing temperature is 40-60° C., and the mixing time is 20-30 hours.

4. The modified ZnO nanosieve prepared by the preparation method according to any one of claims 1 to 3.

5. A method for preparing modified synthetic ester insulating oil using the modified ZnO nanosieve according to claim 4, characterized in that: The following steps are involved: The modified ZnO nanosieve and the synthetic ester insulating oil are mixed to obtain a mixture, and the mixture is dried to obtain the modified synthetic ester insulating oil; The modified ZnO nanosieve accounts for 0.01-0.1 vol% of the modified synthetic ester insulating oil.

6. The preparation method according to claim 5, characterized in that: The synthetic ester insulating oil is TMP triester or PETP tetraester.

7. The preparation method according to claim 6, characterized in that: The TMP triester is synthesized by esterification reaction of medium-chain fatty acid and trimethylolpropane; The PETP tetraester is synthesized by esterification reaction of medium-chain fatty acid and pentaerythritol.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The mixing is carried out under ultrasound, the mixing temperature is 20-50° C., and the mixing time is 0.5-3 h.

9. The modified synthetic ester insulating oil prepared by the preparation method according to any one of claims 5 to 8.

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