Magnetic adsorbent for refining ester base oil as well as preparation method and application method of magnetic adsorbent

Abstract

The invention discloses a magnetic adsorbent for refining ester base oil and preparation and application methods thereof, the adsorbent comprises a magnetic material formed by compounding basic lanthanum carbonate and magnetic particles, the magnetic material is spherical, the sphere diameter is 150-600 nm, and the magnetic material can be rapidly separated from oil liquid under the action of an external magnetic field. The magnetic basic lanthanum carbonate adsorbent disclosed by the invention has high adsorption capacity and selectivity on acidic substances and various polar impurities in ester base oil; the oil-water separator has strong magnetism and can be quickly and thoroughly separated from oil under the action of an external magnetic field; and the preparation process is simple and easy for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lubricating oil refining, and particularly relates to a magnetic adsorbent for ester base oil refining and a preparation and application method thereof, and especially relates to a composite adsorbent taking basic lanthanum carbonate as an active ingredient and having high adsorption performance and magnetic separation characteristics. BACKGROUND

[0002] Ester base oil is widely used in high-end industrial gear oil, aviation hydraulic oil and electrical insulation oil and other fields due to its excellent viscosity-temperature performance, high and low temperature stability, good lubricity and biodegradability. However, during its synthesis or storage, acid impurities (such as free organic acids) and various polar small molecules (such as alcohols, aldehydes, ketones and trace amounts of water) are often left or generated. These impurities can cause the acid value of the oil to increase, causing equipment corrosion and accelerating oil oxidation; at the same time, they can significantly increase the medium loss factor (tan δ) of the oil, seriously damaging its insulation performance.

[0003] At present, adsorption method is commonly used in industry to refine ester base oil. Common adsorbents include activated clay, silica gel, activated alumina and the like. However, these traditional adsorbents have obvious defects: firstly, the adsorption selectivity of acid and polar impurities is limited, and the adsorption capacity is insufficient, resulting in large dosage and unsatisfactory refining effect; secondly, after adsorption, solid-liquid separation needs to be realized through complex filtration or high-speed centrifugation process, which is high in energy consumption and time-consuming under the background of high viscosity of ester oil, and is easy to affect the cleanliness and dielectric performance of the oil due to the residual of adsorbent powder.

[0004] In recent years, magnetic adsorbents have attracted attention because they can realize rapid and low-energy solid-liquid separation with the help of an external magnetic field. However, existing magnetic adsorbent materials (such as surface-modified Fe3O4 nanoparticles or magnetic carbon materials) often lack effective adsorption sites for specific impurities in ester oil, and have limited effect on reducing acid value and medium loss factor.

[0005] Therefore, there is an urgent technical need and important application value to develop a new type of adsorbent that has high adsorption activity (can efficiently remove acid and polar impurities) and excellent magnetic responsiveness (convenient for rapid separation), in order to improve the efficiency and economy of ester base oil refining process and meet the stringent requirements of high-end application fields. SUMMARY

[0006] The primary purpose of the present application is to overcome the deficiencies of the prior art and provide a new type of magnetic basic lanthanum carbonate adsorbent. The adsorbent needs to meet the following requirements: 1) high adsorption capacity and selectivity for acid substances and various polar impurities in ester base oil; 2) strong magnetism itself, which can realize rapid and complete separation from oil under the action of an external magnetic field; 3) simple preparation process, easy to scale up.

[0007] Another object of the present application is to provide a preparation method of the above-mentioned magnetic lanthanum hydroxycarbonate adsorbent.

[0008] Still another object of the present application is to provide a method for refining ester base oil by using the above-mentioned adsorbent, so as to realize a high-efficiency, low-energy-consumption and low-residue refining process.

[0009] To achieve the above-mentioned objects, the present application adopts the following technical solutions: 1. A magnetic lanthanum hydroxycarbonate adsorbent for refining ester base oil The adsorbent is a core-shell or inlaid structure composite material formed by chemical co-precipitation and hydrothermal process of lanthanum hydroxycarbonate (LaCO3OH) and nano-magnetic particles (such as Fe3O4). Its microscopic morphology presents as uniform spherical particles with a diameter ranging from 150 nm to 600 nm. The surface of the material is rich in hydroxyl (-OH) and carbonate (CO3 2- ) functional groups, which is mildly alkaline, can effectively neutralize acidic substances and adsorb small polar molecules through polar action. At the same time, the embedded nano-magnetic particles endow it with superparamagnetic or ferromagnetic properties, so that it can respond to an external magnetic field.

[0010] 2. A preparation method of the magnetic lanthanum hydroxycarbonate adsorbent The preparation method comprises the following steps: (1) Mixing ingredients: lanthanum salt (preferably lanthanum chloride hexahydrate or lanthanum nitrate hexahydrate), urea, citric acid monohydrate and nano-magnetic powder (particle size 30-50 nm) are added to deionized water in a certain mass ratio, and are fully stirred or ultrasonically dispersed to form a uniform suspension. Then, high-purity (≥99.5%) ethylene glycol and a 0.1 mol / L aqueous solution of cetyltrimethylammonium bromide (CTAB) are added to the suspension. The preferred mass ratio of lanthanum salt, urea, citric acid monohydrate and magnetic powder is 1: (1~1.67) : (0.33~1) : 1; the preferred volume ratio of ethylene glycol to CTAB aqueous solution is 1:10.

[0011] (2) Hydrothermal reaction: the mixed solution obtained in step (1) is transferred to a polytetrafluoroethylene-lined high-pressure reaction kettle, sealed and placed in a dry box for hydrothermal reaction. The reaction temperature is preferably 180°C, and the reaction time is preferably 12 hours. During this process, urea decomposes to release carbonate and ammonia, which combine with lanthanum ions and grow and deposit around the magnetic powder under the synergistic action of CTAB template and ethylene glycol, forming a composite structure of lanthanum hydroxycarbonate.

[0012] (3) Post-processing: After the reaction is completed, the reaction vessel is allowed to cool naturally to room temperature. The product suspension is then centrifuged (preferably at a speed of 2000-4000 rpm) to collect the solid precipitate. The precipitate is repeatedly washed with deionized water to remove impurity ions. Finally, the washed solid is dried in an oven at 50-60℃ for 2-4 hours to obtain the magnetic basic lanthanum carbonate adsorbent powder.

[0013] 3. A method for refining ester base oils using the adsorbent. The refining method includes the following steps: (1) Adsorption process: The magnetic basic lanthanum carbonate adsorbent is added to the ester base oil to be refined at a certain dosage (e.g., 0.5-1.5 g / L oil). Adsorption is carried out at a constant temperature (preferably 40-80℃, more preferably 60℃) and a certain stirring rate (preferably 800-1200 rpm) to ensure sufficient contact between the adsorbent and the oil. The adsorption time is preferably 20-60 minutes, more preferably 30-40 minutes, to reach adsorption equilibrium.

[0014] (2) Separation process: After adsorption is complete, stop stirring. Apply a strong magnetic field (such as using a permanent magnet or electromagnet) to the outside or bottom of the container (such as a beaker or reaction vessel). The magnetic adsorbent rapidly aggregates and settles under the action of the magnetic field, and can usually achieve clear separation from the oil within 2-10 minutes. Remove the supernatant to obtain the refined ester base oil.

[0015] The beneficial effects of this invention are as follows: 1. Excellent adsorption performance: The basic lanthanum carbonate component in the adsorbent provides abundant basic and polar adsorption sites, which can efficiently remove acidic impurities and various polar small molecules (such as alcohols, aldehydes, ketones and water) from oil products through the synergistic effect of chemical neutralization and physical adsorption, thereby simultaneously and significantly reducing the acid value and media loss factor (tanδ) of ester base oils.

[0016] 2. Highly efficient and convenient separation process: Due to the composite of nano-magnetic particles, this adsorbent exhibits excellent magnetic responsiveness. After purification, no complex filtration or high-speed centrifugation is required. Simply applying a common external magnetic field can achieve rapid and thorough separation of the adsorbent from the high-viscosity oil within minutes, greatly reducing separation energy consumption and time costs, and avoiding the risks of contamination from filter media or adsorbent powder residue.

[0017] 3. Good material stability: The composite material prepared by the hydrothermal method is firmly bonded, and the basic lanthanum carbonate is coated or loaded on the surface of the magnetic powder, which is not easy to fall off during use, ensuring the stability of adsorption performance and the potential for recycling.

[0018] 4. Simple and controllable preparation process: The preparation method adopts a one-step hydrothermal method, the raw materials are readily available, the reaction conditions are mild, no complicated equipment is required, the process flow is short, and it is easy to achieve mass production. Attached Figure Description

[0019] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a scanning electron microscope (SEM) image of the magnetic basic lanthanum carbonate adsorbent prepared in Example 1 of the present invention, showing its spherical morphology and size distribution.

[0020] Figure 2 The X-ray diffraction (XRD) pattern of the magnetic basic lanthanum carbonate adsorbent prepared in Example 1 of this invention confirms that both basic lanthanum carbonate (LaCO3OH) and magnetic Fe3O4 crystalline phases coexist in the material.

[0021] Figure 3 (a) and (b) are the curves showing the changes in acid value and media loss factor of trimethylolpropane oleate over time during the purification process using the adsorbent of the present invention.

[0022] Figure 4 (a) and (b) are curves showing the changes in acid value and media loss factor over time during the purification process of a synthetic ester using the adsorbent of the present invention.

[0023] Figure 5 The curves show the change in lanthanum ion content in the oil phase over time during the separation of two ester base oils under an external magnetic field, directly reflecting the separation speed and thoroughness of the magnetic adsorbent. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0025] Example 1: Preparation of magnetic basic lanthanum carbonate adsorbent (1) Accurately weigh 300 mg of lanthanum chloride hexahydrate (LaCl3·6H2O), 450 mg of urea, 300 mg of citric acid monohydrate and 300 mg of Fe3O4 magnetic powder with an average particle size of about 40 nm; add all the above solids into a beaker containing 50 mL of deionized water and stir magnetically for 30 minutes at room temperature to obtain a uniform suspension; (2) While stirring continuously, add 1 mL of 99.7% pure ethylene glycol and 10 mL of pre-prepared 0.1 mol / L CTAB aqueous solution dropwise to the above suspension; (3) Transfer all the mixture obtained in step (2) into a 75 mL capacity polytetrafluoroethylene-lined high-pressure reactor and seal it tightly; (4) Place the reactor in a forced-air drying oven, heat it to 180°C and maintain it at this temperature for 12 hours to carry out the hydrothermal reaction; (5) After the reaction is complete, allow it to cool naturally to room temperature; open the reaction vessel, transfer all the products in the vessel to centrifuge tubes, centrifuge at 3000 rpm for 5 minutes, and discard the supernatant; (6) Redisperse the precipitate with about 30 mL of deionized water and centrifuge and wash again; repeat this washing process 3 times. (7) The final precipitate was transferred to a petri dish and dried in an oven at 55°C for 2 hours. After drying, it was ground to obtain a powdered product, which is the magnetic basic lanthanum carbonate adsorbent.

[0026] Product characterization: SEM observation ( Figure 1 XRD analysis showed that the particles were spherical with a diameter of 150-600 nm, and the surface was composed of even smaller particles. Figure 2 The presence of characteristic diffraction peaks belonging to both LaCO3OH and Fe3O4 in the spectrum confirms the successful synthesis of the target composite material.

[0027] Example 2: Evaluation of the effect of adsorbent on the refining of ester base oils This embodiment examines the refining effect of the magnetic basic lanthanum carbonate adsorbent prepared in Example 1 on two typical ester base oils (trimethylolpropane oleate and an industrial synthetic ester).

[0028] (1) Initial property determination of oil samples: 10 mL and 40 mL of trimethylolpropane oleate and synthetic ester were weighed respectively, and the acid value was determined using a fully automatic potentiometric titrator (Titrando 905). The dielectric loss factor (tanδ) was determined using an oil dielectric loss tester (DX6100). Test conditions: voltage 500 kV, temperature 90℃. The initial acid value and dielectric loss factor of the two ester base oils are shown in Table 1. Table 1 Initial acid number and media loss factor of ester base oils Ester base oil Initial acid value Medium loss factor Trimethylolpropane oleyl ester 1.87 mgKOH / g 4.163% Synthetic ester 0.37 mgKOH / g 3.582% (2) Static adsorption experiment: 1000 mL of the two ester oils were measured and placed in two 2 L glass beakers respectively; 500 mg (i.e. 0.5 g / L) of the magnetic basic lanthanum carbonate adsorbent prepared in Example 1 was added to each beaker; (3) Place the beaker in a 60°C constant temperature water bath, add a magnetic stir bar, and start stirring at 1000 rpm. Keep stirring at a constant speed to start the adsorption reaction. (4) When the reaction proceeds for 5 min, 10 min, 20 min, 30 min, 40 min, 50 min and 60 min, take samples from the reaction solution in the beaker, filter them and determine the acid value and the medium loss factor.

[0029] In Example 2, the changes in acid value and dielectric loss factor during the reaction of trimethylolpropane oleate and the synthetic ester after the addition of magnetic basic lanthanum carbonate adsorbent are shown in the curves below. Figure 3 and Figure 4 As shown. From Figure 3 and Figure 4 It can be seen that the magnetic basic lanthanum carbonate adsorbent can effectively reduce the acid value and media loss factor of trimethylolpropane oleate and synthetic esters, and the adsorption reaches saturation within 20~40 minutes.

[0030] Example 3: Separation effect of magnetic basic lanthanum carbonate adsorbent (1) Measure 1000 mL of trimethylolpropane oleate and synthetic ester into beakers respectively; (2) Add 500 mg of the magnetic basic lanthanum carbonate adsorbent prepared in Example 1 to a beaker, add a magnetic stir bar, and stir at a constant temperature water bath magnetic stirrer at 60°C for 30 min at a stirring speed of 1000 rpm. (3) Place a strong magnet at the bottom of the beaker and take samples from the upper part of the beaker at 2 min, 4 min, 6 min, 8 min and 10 min. Use inductively coupled plasma mass spectrometry (ICP-MS) to determine the content of lanthanum in the oil sample to judge the separation effect of the magnetic basic lanthanum carbonate adsorbent.

[0031] The changing trends of lanthanum ion content in two ester base oils during the magnetic separation of lanthanum carbonate adsorbent using a magnetic separator are as follows: Figure 5 As shown in the figure, the lanthanum ion content in the oil completely settled within 4-6 minutes after the magnet was placed, proving the excellent separation performance of the magnetic basic lanthanum carbonate adsorbent under an external magnetic field.

[0032] The above embodiments fully demonstrate that the magnetic basic lanthanum carbonate adsorbent and its preparation and application method provided by the present invention can effectively solve the technical problem of simultaneously achieving adsorption efficiency and separation efficiency in the refining process of ester base oils. This adsorbent has a simple preparation process, superior adsorption performance, and rapid and thorough magnetic separation, showing promising prospects for industrial application.

[0033] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A magnetic basic lanthanum carbonate adsorbent for refining ester base oils, characterized in that, The adsorbent comprises a magnetic material formed by combining basic lanthanum carbonate and magnetic particles. The adsorbent has a spherical morphology with a diameter of 150–600 nm, and the magnetic material can be rapidly separated from the oil under the action of an external magnetic field.

2. The magnetic basic lanthanum carbonate adsorbent according to claim 1, characterized in that, The magnetic particles have a particle size of 30–50 nm.

3. A method for preparing the magnetic basic lanthanum carbonate adsorbent according to claim 1 or 2, characterized in that, Includes the following steps: (1) Lanthanum salt, urea, citric acid monohydrate and magnetic powder are mixed evenly in deionized water to obtain a suspension; then ethylene glycol and CTAB aqueous solution are added to the suspension. (2) Transfer the mixture obtained in step (1) to a high-pressure reactor and keep it at a set temperature in a drying oven for reaction; (3) The product obtained after the reaction in step (2) is centrifuged to separate the solid. After washing and drying, the magnetic basic lanthanum carbonate adsorbent is obtained.

4. The preparation method according to claim 3, characterized in that, In step (1), the lanthanum salt is selected from either lanthanum chloride hexahydrate or lanthanum nitrate hexahydrate.

5. The preparation method according to claim 3, characterized in that, In step (1), the mass ratio of the lanthanum salt, urea, citric acid monohydrate and magnetic powder is 1: (1~1.67): (0.33~1):

1.

6. The preparation method according to claim 3, characterized in that, In step (1), the purity of the ethylene glycol is ≥99.5%, the concentration of the CTAB aqueous solution is 0.1 mol / L, and the volume ratio of the added ethylene glycol to the CTAB aqueous solution is 1:

10.

7. The preparation method according to claim 3, characterized in that, In step (2), the temperature of the heat preservation reaction is 180°C and the reaction time is 12 hours.

8. The preparation method according to claim 3, characterized in that, In step (3), the centrifugation speed is 2000-4000 rpm.

9. A method for refining ester base oils, characterized in that, Includes the following steps: The magnetic basic lanthanum carbonate adsorbent as described in claim 1 or 2, or the magnetic basic lanthanum carbonate adsorbent prepared by the method according to any one of claims 3 to 8, is added to the ester base oil to be refined, and the adsorption reaction is carried out under stirring. After the reaction is complete, the magnetic basic lanthanum carbonate adsorbent is separated from the oil by an external magnetic field to obtain the refined ester base oil.

10. The method for refining ester base oils according to claim 9, characterized in that, The adsorption reaction was carried out at a temperature of 40-80℃, a stirring rate of 1000 rpm, and a reaction time of 20-40 minutes.

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