Method for preparing ionic liquid-supercritical modified lubricating base oil

Abstract

The invention discloses a method for preparing ionic liquid-supercritical modified lubricating base oil, which is characterized in that waste transformer oil is utilized, dehydrogenation is realized through a molecular sieve platinum catalyst, the modified transformer oil is effectively reduced to obtain olefin or branched olefin, and the catalyst and a reaction product can be separated only by filtering; meanwhile, the ionic liquid is used as a catalyst, chain extension of the waste transformer oil is achieved, meanwhile, the ionic liquid has good fluidity in supercritical fluid, a strong acid site can be kept, generation of a polyalkyl side chain compound can be promoted, and polyalkyl naphthalene can be obtained without a high temperature. The polyalkyl naphthalene has better viscosity and lubricating property, is not easy to volatilize, can provide proper viscosity and lubricating property for processing liquid, is more suitable for being used as base oil than waste transformer oil, and can be used as base oil of cutting fluid.

Description

Technical Field

[0001] This invention relates to the field of waste transformer oil, and more specifically to a method for producing an ionic liquid-supercritical modified lubricating base oil. Background Technology

[0002] The amount of waste transformer oil in my country is increasing daily. Currently, some of this waste oil is collected, purified, and sent to refineries as raw materials for further physical and chemical processing to produce target products. Another portion is burned as fuel. Existing recycling methods also include using waste transformer oil as a base oil, such as in cutting fluids and lubricating oils. While waste transformer oil can be used as a base oil in metal cutting fluids to achieve resource utilization, its lubricating properties are insufficient, and it also presents some volatility issues.

[0003] In the prior art, CN115851358B discloses an environmentally friendly water-based cutting fluid for stainless steel, its preparation method, and its application. The fluid comprises 20%–60% mixed oil ester, 1%–20% organic amine, 0%–40% water-based extreme pressure lubricant for stainless steel, 10%–40% ionic liquid, 1%–10% corrosion inhibitor, 8%–30% emulsifier, 1%–20% bactericide, and the balance being deionized water. The mixed oil ester is a mixture of waste transformer oil and white oil in a ratio of 3–1:1–5. The advantage of this invention is that it uses waste transformer oil and white oil as raw materials to formulate the environmentally friendly stainless steel cutting fluid. In the process of reusing waste transformer oil, apart from appropriate filtration of the heavily polluted waste transformer oil, no complex chemical treatment, physical distillation, dehydration, or deacidification treatment is required. Although it achieves the utilization of waste transformer oil, the performance of untreated waste transformer oil is still inferior to other similar base oils. The low-carbon components have certain volatilization problems during use, and the base oil is difficult to degrade, which is not conducive to the environmentally friendly utilization of cutting fluid. In addition, the formulation of cutting fluid requires the addition of other components besides base oil, such as ionic liquids to improve the performance of cutting fluid.

[0004] Ionic liquids can effectively improve the performance of base oils, reduce friction and wear on machinery during machining fluid use, and therefore, modifying base oils with ionic liquids and applying them to cutting fluid formulations can be considered to improve cutting fluid performance. Most existing waste transformer oil processing methods involve multiple steps and are time-consuming.

[0005] Therefore, a method for modifying lubricating base oils with ionic liquids and supercritical fluids is needed to solve the above problems. Summary of the Invention

[0006] This invention claims protection for a method for producing an ionic liquid-supercritical modified lubricating base oil, the technical solution of which is as follows:

[0007] A method for preparing an ionic liquid-supercritical modified lubricating base oil, the specific preparation method being as follows:

[0008] Step 1 Dehydrogenation: Filter the waste transformer oil to remove impurities and obtain filtrate. Add molecular sieve-platinum catalyst to the filtrate and react at 160-190℃ for 3-4 hours. Filter to obtain solution A.

[0009] Step 2: Alkylation: Using n-decane as a solvent, triethylamine hydrochloride and anhydrous aluminum chloride are added to synthesize an ionic liquid. Then, naphthalene is added to the prepared ionic liquid and placed together in a reaction vessel. Solution A is added, and after the addition is complete, the reaction is continued at 50-60℃ for 0.5-1 h. The temperature is then lowered, and supercritical carbon dioxide is introduced for 0.5-1 h. After the reaction is complete, the mixture is allowed to stand.

[0010] After the reaction is complete, the supernatant is decanted, an equal volume of distilled water is added, the mixture is stirred thoroughly, and the supernatant is separated. The obtained supernatant is then subjected to vacuum distillation to remove the solvent.

[0011] Furthermore, in step one, the amount of catalyst added is 0.5-2% of the mass of the waste transformer oil in step one; the platinum loading is 4-20%.

[0012] Furthermore, in step two, the reaction temperature of the ionic liquid is 50-60℃; the molar ratio of triethylamine hydrochloride to anhydrous aluminum chloride is 1:2-2.5; and the mass ratio of waste transformer oil to naphthalene is 5-7:1.

[0013] Furthermore, in step two, the cooling temperature is 31°C, the critical pressure of carbon dioxide is 7.39 MPa, and the mass ratio of naphthalene to triethylamine hydrochloride is 7-8:1.

[0014] Furthermore, in step one, the molecular sieve in question is a Y-type molecular sieve.

[0015] Furthermore, in step one, the molecular sieve can also be ZSM-5 molecular sieve, used for the isomerization reaction of waste transformer oil.

[0016] The specific reaction principle is as follows:

[0017]

[0018] Waste transformer oil contains a large amount of alkanes. Platinum catalysts can dehydrogenate alkanes into olefins, and ZSM molecular sieves can be used to isomerize olefins into branched olefins. Ionic liquids can be used as catalysts for alkylation reactions to achieve carbon enrichment and cyclization of olefins. Supercritical carbon dioxide has good solubility and can promote the activation of ionic liquids. This is because ionic liquids basically lose their fluidity after the reaction and have low reactivity. Supercritical fluids have good solubility, which allows ionic liquids to maintain good catalytic activity at low temperatures and can promote the catalytic effect of ionic liquids, thereby continuously providing acidic sites to promote the continuous conversion of monoalkyl to dialkyl or polyalkyl, thus improving the conversion rate of the reaction, especially the conversion rate of polyalkyl naphthalene. Polyalkyl naphthalene has good viscosity and lubrication properties, is not easily volatile, and is more suitable for use as a base oil.

[0019] Technical effect

[0020] This invention utilizes waste transformer oil and dehydrogenation via a platinum molecular sieve catalyst to effectively reduce the altered transformer oil to obtain olefins or branched olefins. The catalyst and reaction products can be separated simply by filtration. Simultaneously, this application utilizes an ionic liquid as a catalyst to extend the chain in the waste transformer oil. This ionic liquid exhibits good fluidity in supercritical fluids, effectively solving the problem of poor fluidity after a certain reaction time, and maintains strong acidic sites, promoting the formation of polyalkyl side-chain compounds. Polyalkyl naphthalenes can be obtained without high temperatures. Polyalkyl naphthalenes possess good viscosity and lubricating properties, are not easily volatile, and provide suitable viscosity and lubricity for processing fluids, making them more suitable as base oils than waste transformer oil. They can also be used as base oils for cutting fluids. Attached Figure Description

[0021] Figure 1 The image shows the 1H NMR spectrum of naphthalene. Figure 2 The image shows the 1H NMR spectrum of the polyalkylnaphthalene product obtained in Example 1. Figure 2 and Figure 1 In contrast, a new peak appeared near the chemical shift of 7 PPM, indicating that a new carbon chain was attached to the naphthalene ring after the reaction. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] The raw material used was No. 25 waste transformer oil that conformed to GB2536-1990. This waste transformer oil was scrapped because its dielectric loss factor and breakdown voltage performance exceeded the standards.

[0024] Example 1

[0025] Take 125g of filtered waste transformer oil, then add 1.3g of Y-type molecular sieve-platinum catalyst (15% loading), heat to 170℃ in a reactor and react for 4h, then filter to obtain solution A; add 3g of triethylamine hydrochloride and 6g of anhydrous aluminum chloride to 12g of n-decane and dissolve at 60℃ to obtain ionic liquid for later use; add 22g of naphthalene to the ionic liquid and place it in the reactor, then add solution A dropwise using a plunger pump, and continue the reaction at 60℃ for 1h after completion; then cool to 31℃, connect to a supercritical carbon dioxide device, introduce supercritical carbon dioxide at a pressure of 7.39MPa, maintain for 1h, let stand after the reaction, decant the supernatant, add an equal volume of distilled water, stir thoroughly, separate the liquid, and perform vacuum distillation on the obtained supernatant to obtain 139g of modified base oil.

[0026] The product obtained in Example 1 was subjected to 1H NMR spectroscopy, and the result was compared with the 1H NMR spectrum of naphthalene. The results showed that the 1H NMR spectrum of the product obtained in Example 1 exhibited a new peak near a chemical shift of 7 PPM, indicating that a new carbon chain was attached to naphthalene, and the structure was similar to... Figure 1 The significant differences indicate that Example 1 successfully obtained a modified base oil of polyalkylnaphthalene.

[0027] Example 2

[0028] Take 125g of filtered waste transformer oil, then add 2.5g of ZSM molecular sieve-platinum catalyst (6% loading), heat to 190℃ in a reactor and react for 3h, then filter to obtain solution A; add 3.5g of triethylamine hydrochloride and 8g of anhydrous aluminum chloride to 18g of n-decane and dissolve at 52℃ to obtain ionic liquid for later use; add 25g of naphthalene to the ionic liquid and place it in the reactor, then add solution A dropwise using a plunger pump, and continue the reaction at 52℃ for 1h after completion; then cool to 31℃, connect to a supercritical carbon dioxide device, introduce supercritical carbon dioxide, maintain for 1h, let stand after the reaction, decant the supernatant after the reaction, add an equal volume of distilled water, stir thoroughly, separate the liquid, and perform vacuum distillation on the obtained supernatant to obtain 140g of modified base oil.

[0029] Comparative Example 1

[0030] Take 125g of filtered waste transformer oil, then add 1.3g of Y-type molecular sieve-platinum catalyst (15% loading), heat to 170℃ in a reactor and react for 4h, then filter to obtain solution A; add 3g of triethylamine hydrochloride and 6g of anhydrous aluminum chloride to 12g of n-decane and dissolve at 60℃ to obtain ionic liquid for later use; add 22g of naphthalene to the ionic liquid and place it in the reactor, then add solution A dropwise using a plunger pump, and continue the reaction at 60℃ for 1h after completion; then cool to 31℃, decant the supernatant, add an equal volume of distilled water, stir thoroughly, separate the liquid, and perform vacuum distillation on the obtained supernatant to obtain 137g of modified base oil.

[0031] Comparative Example 2

[0032] This comparative example uses unprocessed and unmodified waste transformer oil directly.

[0033] To verify the performance of the modified base oil of the present invention, the oils obtained in Examples 1-2 and Comparative Examples 1-2 were used to prepare cutting fluids according to the description in Example 1 of patent CN115851359A. The performance of the cutting fluids was then tested. The invention title of this patent is "An Environmentally Friendly Metal Cutting Fluid and Its Preparation Method and Application." The test results are listed in Table 1.

[0034] Table 1 Comparison of Cutting Fluid Performance

[0035]

[0036] The test results show that both the examples and the comparative examples have good corrosion resistance, rust prevention, and lubrication. The coefficient of friction and wear scar diameter of Examples 1-2 are smaller than those of Comparative Example 2, indicating that the lubrication performance of the modified waste transformer oil is better than that of the unmodified oil. The modified base oils obtained using different catalysts have different properties. Example 2, using ZSM molecular sieves, can obtain isomerized olefins, which have better lubrication effects than the straight-chain olefins obtained in Example 1. The lubrication performance of Comparative Example 1 is lower than that of Example 1. This is because the supercritical fluid in Example 1 promotes the catalytic effect of the ionic liquid, effectively promoting the formation of multi-side-chain products. Multi-branched products have better viscosity and lubrication performance, which can better reduce machine wear.

Claims

1. A method of ionic liquid-supercritical modified lubricating base oil characterized by, The recycling process comprises the following steps: Step one dehydrogenation: the waste pressure oil is filtered to remove impurities to obtain a filtrate, a molecular sieve-platinum catalyst is added to the filtrate, and the reaction is carried out at 160-190℃ for 3-4h, then filtered to obtain solution A; Step two alkylation: using n-decane as a solvent, adding triethylamine hydrochloride and anhydrous aluminum chloride to synthesize ionic liquid; then, naphthalene is added to the prepared ionic liquid and placed in a reaction kettle, and solution A is added, and after the dropwise addition is completed, the reaction is continued at a reaction temperature of 50-60℃ for 0.5-1h, then the temperature is lowered, supercritical carbon dioxide is introduced for 0.5-1h, and after the reaction is completed, it is left to stand; After the reaction is completed, the upper liquid is decanted, an equal volume of distilled water is added, stirred and separated, and the obtained upper liquid is subjected to vacuum distillation to remove the solvent; The addition amount of the catalyst is 0.5-2% of the mass of the waste pressure oil in step one; In step two, the molar ratio of triethylamine hydrochloride to anhydrous aluminum chloride is 1:2-2.5, the mass ratio of waste pressure oil to naphthalene is 5-7:1, and the mass ratio of naphthalene to triethylamine hydrochloride is 7-8:

1.

2. A method of producing an ionic liquid-supercritical modified lubricating base oil according to claim 1, characterized by, In step one, the loading amount of platinum is 4-20%.

3. The method for producing an ionic liquid-supercritical modified lubricating base oil as described in claim 1, characterized in that, In step two, the reaction temperature of the ionic liquid is 50-60℃.

4. The method for producing an ionic liquid-supercritical modified lubricating base oil as described in claim 1, characterized in that, In step two, the temperature after cooling is 31℃, and the critical pressure of carbon dioxide is 7.39MPa.

5. The method for producing an ionic liquid-supercritical modified lubricating base oil as described in claim 1, characterized in that, In step one, the molecular sieve is a Y-type molecular sieve.

6. The method for producing an ionic liquid-supercritical modified lubricating base oil as described in claim 1, characterized in that, In step one, the molecular sieve can also be a ZSM-5 molecular sieve, which is used for isomerization reaction of waste pressure oil.

Images