Modification process of waste transformer oil for cutting fluid
By combining molecular sieve-platinum catalyst and phosphotungstic acid catalyst, the dehydrogenation isomerization and epoxidation esterification of waste transformer oil were achieved, solving the problems of insufficient lubrication performance and volatility of waste oil in cutting fluid. High-viscosity polyol esters were prepared as base oils, improving resource utilization efficiency.
Patent Information
- Application Number
- CN202511608821.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-02-06
AI Technical Summary
In existing technologies, waste transformer oil has problems with insufficient lubrication performance and volatility when used as a base oil for metal cutting fluids, and it is difficult to degrade effectively, which affects its environmentally friendly utilization.
Dehydroisomerization was carried out using a molecular sieve-platinum catalyst, combined with the epoxidation reaction of formic acid and hydrogen peroxide, followed by ring-opening esterification catalyzed by phosphotungstic acid to prepare a high-viscosity polyol ester, which can be used as the base oil for cutting fluid.
The lubrication performance and degradability of waste transformer oil were improved, the evaporation loss rate was reduced, and the efficient resource utilization of waste oil was achieved. The prepared polyol ester has good lubricity and thermal stability as a base oil.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of waste transformer oil, in particular to a modification process of waste transformer oil for cutting fluid. BACKGROUND
[0002] Transformer oil is an essential lubricant in machinery, which will become waste transformer oil due to performance degradation after long-term use. Therefore, transformer oil must be replaced when it deteriorates to a certain extent after being used for a certain period of time. The amount of waste transformer oil is increasing in China. Currently, these waste oils are treated in the following ways: some are collected, purified and sent to oil refineries to be processed into target products through physical and chemical changes, and some are burned as fuel. In the existing recycling methods, waste transformer oil is also used as base oil, such as cutting fluid and lubricating oil. Currently, waste transformer oil can be used as base oil for metal cutting fluid to achieve resource utilization, but the lubricating performance of waste transformer oil used as base oil for metal cutting fluid is insufficient, and there is a certain problem of volatilization.
[0003] In the prior art, CN115851359A discloses an environmentally friendly metal cutting fluid and a preparation method and application thereof. The components thereof are as follows: waste transformer oil 20%-60%, organic amine 1%-20%, extreme pressure lubricant 0%-40%, ionic liquid 10%-40%, corrosion inhibitor 1%-10%, emulsifier 8%-30%, defoaming agent 0.5%-5%, bactericide 1%-20%, and the balance is water. The metal cutting fluid is prepared by using waste transformer oil as raw material. In the recycling process of waste transformer oil, no complex chemical treatment, physical distillation, dehydration and deacidification treatment methods are required. The recycling process does not produce new pollutants such as acid sludge and oily wastewater, and the process is simple and environmentally friendly. Although the utilization of waste transformer oil is realized, the untreated waste transformer oil has a certain problem of volatilization in use, and the base oil is difficult to degrade, which is not conducive to the environmental utilization of the cutting fluid.
[0004] Therefore, there is a need for a modification process of waste transformer oil for cutting fluid. SUMMARY
[0005] The present application claims a modification process of waste transformer oil for cutting fluid, and the technical scheme adopted is as follows:
[0006] A modification process of waste transformer oil for cutting fluid, and the specific preparation method is as follows:
[0007] Step one: dehydrogenation isomerization: filter the waste transformer oil to remove impurities to obtain filtrate A, add molecular sieve-platinum catalyst to the filtrate A, and react at 160-190℃ for 3-4h to obtain filtrate B;
[0008] Step two epoxidation: add formic acid to the filtrate B, drop hydrogen peroxide solution, control the drop speed, react at 45-55℃ for 4-6h, get reaction product C;
[0009] Step three ring-opening esterification: separate the reaction product C, remove the water layer, add water to the oil layer, mix well, add tungsten phosphoric acid, react at 100-115℃ for 0.5-1h; after the reaction is completed, continue to add carboxylic acid for esterification, after the reaction is completed, separate the layers, separate the upper organic layer, and purify to obtain the transparent oily liquid product.
[0010] Further, in step one, the amount of catalyst added is 5-10% of the mass of filtrate A in step one; the molecular sieve is ZSM-5 molecular sieve, and the loading of platinum is 4-20%;
[0011] Further, in step two, the mass ratio of formic acid to hydrogen peroxide is 3:1; the mass of formic acid is 30%-50% of the mass of filtrate A in step one;
[0012] Further, in step three, the amount of tungsten phosphoric acid added is 0.5-1.5% of the mass of filtrate A in step one;
[0013] Further, in step three, the carboxylic acid is a C2-C8 monobasic or dibasic carboxylic acid; the molar ratio of carboxylic acid to formic acid is 1-2.5:1; after adding the carboxylic acid, continue to heat to 120-135℃ and maintain the reaction for 4-8h.
[0014] The specific reaction principle is as follows:
[0015] There are a large amount of alkanes in waste transformer oil, and platinum catalyst can achieve the dehydrogenation of alkanes, while the catalytic action of molecular sieve ZSM can isomerize olefins into branched olefins, the epoxidation of olefins is achieved by peroxide, and the catalytic action of tungsten phosphoric acid promotes ring-opening and esterification, and then branched esters are prepared, which have good viscosity and lubrication performance.
[0016]
[0017] Technical effects
[0018] The present application utilizes waste transformer oil to realize dehydrogenation isomerization through a molecular sieve platinum catalyst, wherein noble metal realizes dehydrogenation, and molecular sieve ZSM plays the role of isomerization, and then branched olefins are effectively reduced from the waste transformer oil, and high-viscosity polyol esters are obtained through epoxidation and ring-opening esterification reaction, which not only effectively recycles and utilizes the waste transformer oil, but also synthesizes polyol esters that can be used as base oil, has a lower evaporation loss rate and better lubricity. In the present application, formic acid hydrogen peroxide is used for epoxidation, which is simple to operate, and the subsequent ring-opening esterification can realize one-pot synthesis, thereby improving the utilization efficiency of materials; the present application uses phosphotungstic acid as a ring-opening catalyst and an esterification catalyst, which can effectively promote the ring-opening esterification reaction, and at the same time, the present application uses dehydrogenation isomerization, which can obtain higher recycling effect than traditional recycling and processing technology, and finally obtains high-viscosity alcohol esters, which are not easy to volatilize, can be degraded, and can be used as base oil for cutting fluid. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 The infrared spectrum of the high-viscosity polyol ester obtained in Example 1 shows obvious ester group characteristic absorption peaks; Figure 2 The thermogravimetric analysis curve of the obtained base oil shows that it has excellent thermal stability and low volatility. Figure 1 The strong absorption peaks at 1740 cm -1 confirm the formation of ester carbonyl C=O bond, and the double peaks at 1170 cm - and 1230 cm -1 indicate the existence of ester C-O-C structure. Figure 2 The base oil shows almost no weight loss below 300℃, which is much better than traditional mineral oil. DETAILED DESCRIPTION
[0020] The present application will be further described below in combination with specific examples.
[0021] Example 1
[0022] Take 160 g of waste transformer oil, filter to obtain 150 g of filtered oil, then add 9 g of molecular sieve ZSM-5-platinum catalyst (platinum loading is 10%), heat to 180℃ in a reaction kettle for 4 h, then filter, add 60 g (1.3 mol) of formic acid to the filtrate, add 100 g of 20% mass fraction of hydrogen peroxide, slowly drop for 0.5 h, react at 50℃ for 4 h, after the reaction is completed, stand and separate, remove the lower aqueous solution, then add 50 ml of water, mix uniformly, add 2 g of phosphotungstic acid, heat to 110℃ and react for 0.5 h, continue to add 250 g (1.92 mol) of n-heptanoic acid, heat to 120℃ and react for 6 h, after the reaction is completed, stand, then extract and reduce pressure distillation to obtain transparent oil liquid product synthesis ester 360 g.
[0023] In order to verify the properties of the resulting product, infrared spectroscopy and thermogravimetric analysis tests were carried out, Figure 1 a strong absorption peak at 1740 cm -1 confirms the formation of the ester carbonyl C=0 bond, while the doublet at 1170 cm -1 and 1230 cm -1 indicates the presence of the ester C-O-C structure, which is a clear ester group characteristic absorption peak, indicating that the polyol ester has been successfully synthesized by the method. The thermogravimetric analysis results shown in Figure 2 show that the base oil has almost no weight loss below 300°C, which is much better than traditional mineral oil, and the base oil exhibits good thermal stability.
[0024] Example 2
[0025] Take 160 g of waste transformer oil and filter to obtain 150 g of filtered oil. Then add 13 g of molecular sieve ZSM-5-platinum catalyst (platinum loading of 6%) and heat to 190°C in a reaction kettle for 3 h. Then filter, add 81 g (1.76 mol) of formic acid to the filtrate, add 100 g of 27% mass fraction of hydrogen peroxide, slowly drop for 0.5 h, and react at 45°C for 6 h. After the reaction is completed, stand and separate the layers, remove the lower aqueous solution, then add 50 ml of water, mix uniformly, add 1 g of phosphotungstic acid, heat to 115°C and react for 0.8 h. Continue to add 300 g (3.4 mol) of n-butyric acid, heat to 130°C and react for 5 h. After the reaction is completed, stand, then extract and reduce pressure distillation to obtain transparent oily liquid product synthetic ester 382 g.
[0026] Example 3
[0027] Take 160 g of waste transformer oil and filter to obtain 150 g of filtered oil. Then add 15 g of molecular sieve ZSM-5-platinum catalyst (platinum loading of 16%) and heat to 160°C in a reaction kettle for 4 h. Then filter, add 90 g (1.96 mol) of formic acid to the filtrate, add 100 g of 30% mass fraction of hydrogen peroxide, slowly drop for 0.5 h, and react at 55°C for 5 h. After the reaction is completed, stand and separate the layers, remove the lower aqueous solution, then add 50 ml of water, mix uniformly, add 2.2 g of phosphotungstic acid, heat to 100°C and react for 1 h. Continue to add 320 g (2.2 mol) of n-octanoic acid, heat to 135°C and react for 4 h. After the reaction is completed, stand, then extract and reduce pressure distillation to obtain transparent oily liquid product synthetic ester 394 g.
[0028] Comparative Example 1
[0029] Take waste transformer oil 160 g filter to get 150 g filter oil, then add 9 g molecular sieve ZSM-5-platinum catalyst (platinum loading is 10%), heated to 180℃ in the reaction kettle for 4h, then filter, add formic acid 60 g (1.3 mol) to the filtrate, add 100 g mass fraction 25% hydrogen peroxide, slowly drop 0.5h, react at 50℃ for 4h, after the reaction is completed, stand and separate, remove the lower aqueous solution, then add 50 ml water, mix evenly, then add 2 g phosphotungstic acid, heat to 110℃ for 0.5h, continue to add n-heptanoic acid 250 g (1.92 mol), heat to 120℃ for 6h, after the reaction is completed, stand, then extract and reduce pressure distillation to get transparent oily liquid product synthetic ester 307 g.
[0030] Comparative example 2
[0031] Take waste transformer oil 160 g filter to get 150 g filter oil, then add 9 g molecular sieve ZSM-5-platinum catalyst (platinum loading is 10%), heated to 180℃ in the reaction kettle for 4h, then filter, add formic acid 60 g (1.3 mol) to the filtrate, add 100 g mass fraction 25% hydrogen peroxide, slowly drop 0.5h, react at 50℃ for 4h, after the reaction is completed, stand and separate, remove the lower aqueous solution, then add 50 ml water, mix evenly, then add 2 g phosphotungstic acid, heat to 110℃ for 0.5h, continue to add n-heptanoic acid 250 g (1.92 mol), heat to 120℃ for 6h, after the reaction is completed, stand, then extract and reduce pressure distillation to get transparent oily liquid product synthetic ester 307 g.
[0032] Verification example
[0033] In order to verify the performance of the synthetic ester of the present application, its acidity, kinematic viscosity, pour point are tested, the test method is GB / T7304-2014 "determination of acid value of petroleum products (potentiometric titration)", GB / T3535-2006 "determination of pour point of petroleum products", according to GB / T1995-1998 "calculation method of viscosity index of petroleum products" and the kinematic viscosity value of oil at 40℃ and 100℃, the viscosity index (VI) of high viscosity lubricating oil ester base oil is calculated. The test results are shown in table 1.
[0034] Table 1 test results of products obtained by examples and comparative examples
[0035]
[0036] From the test results, it can be seen that the ester synthesized in Examples 1-3 of the present application has high viscosity, good viscosity-temperature property and low pour point, and can be used as base oil of lubricating oil. By using waste transformer oil, through dehydrogenation isomerization, epoxidation, ring-opening esterification, high viscosity alcohol ester is finally obtained, which not only effectively recycles and utilizes waste transformer oil, but also synthesizes polyol ester that can be used as base oil, has lower evaporation loss rate and better lubricity, and has good effect as cutting fluid. In the present application, formic acid and hydrogen peroxide are used for epoxidation, which is simple to operate, and the subsequent ring-opening esterification can be realized by one-pot synthesis, thereby improving the utilization efficiency of materials; in the present application, phosphotungstic acid is used as a ring-opening catalyst and an esterification catalyst, which can effectively promote the ring-opening esterification reaction, and at the same time, the catalyst can be recycled by dehydrogenation isomerization, thereby achieving higher recycling effect than traditional recycling and processing technology.
[0037] At the same time, it can be seen that the mass ratio of formic acid to hydrogen peroxide in Comparative Example 1-2 is less than and greater than 3:1, respectively, the obtained product has less mass and poor performance, and the reason is that the mass ratio of formic acid to hydrogen peroxide is not appropriate, resulting in poor double bond oxidation and ring-opening effect, less branched chains connected subsequently, low viscosity and easy evaporation.
Claims
1. A modification process for waste transformer oil used as cutting fluid, characterized in that, The process includes the following steps: Step 1: Dehydroisomerization: Filter the waste transformer oil to remove impurities and obtain filtrate A. Add molecular sieve-platinum catalyst to filtrate A and react at 160-190℃ for 3-4 hours. Filter to obtain filtrate B. Step 2: Epoxidation: Add formic acid to filtrate B, add hydrogen peroxide solution dropwise, control the dropping rate, and react at 45-55℃ for 4-6 hours to obtain reaction product C; Step 3: Ring-opening esterification: Let the reaction product C stand to separate into layers, remove the water layer, add water to the oil layer and mix thoroughly, then add phosphotungstic acid and react at 100-115℃ for 0.5-1h. After the reaction is complete, continue to add carboxylic acid to react. After the reaction is complete, let stand to separate into layers, separate the upper organic layer, and purify to obtain a transparent oily liquid product.
2. The modification process for waste transformer oil for cutting fluid as described in claim 1, characterized in that, In step one, the amount of catalyst added is 5-10% of the mass of filtrate A in step one; the molecular sieve is ZSM molecular sieve, and the platinum loading is 4-20%.
3. The modification process for waste transformer oil for cutting fluid as described in claim 1, characterized in that, In step two, the mass ratio of formic acid to hydrogen peroxide is 3:1; the mass of formic acid is 30%-50% of the mass of filtrate A in step one.
4. The modification process for waste transformer oil for cutting fluid as described in claim 1, characterized in that, In step three, the amount of phosphotungstic acid added is 0.5-1.5% of the mass of filtrate A in step one.
5. The modification process for waste transformer oil for cutting fluid as described in claim 1, characterized in that, In step three, the carboxylic acid is a C2-C8 monocarboxylic acid or a dicarboxylic acid; the molar ratio of the carboxylic acid to formic acid is 1-2.5:1; after adding the carboxylic acid, continue heating to 120-135℃ and maintain the reaction for 4-8 hours.