Process for the purification and regeneration of used lubricating oils

Abstract

The present application belongs to the technical field of waste mineral oil recycling and regeneration, and particularly relates to a refining and regeneration method of waste lubricating oil; aiming at the problems of complex composition, containing various additives, metal debris, degradation products and the like of the current waste lubricating oil; the present application adopts molecular recognition-plasma-supercritical coupling technology, first carries out magnetic separation and vibration membrane filtration on the waste lubricating oil, then selectively adsorbs and removes various heavy metal ions through the molecularly imprinted polymer microspheres prepared by using the chemically modified dithizone as a functional monomer; utilizes low-temperature plasma treatment to deeply remove chlorine, silicon and phosphorus elements, and carries out supercritical CO2 treatment to realize preliminary separation of these impurities and base oil molecules, and through the catalyst MoP / TiO2-SiO2-OTS, catalytic cracking and alkylation reactions are realized to degrade the impurities into hydrocarbon fragments, and deep purification and recycling are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste mineral oil recycling and regeneration, and particularly relates to a refining and regeneration method of waste lubricating oil. BACKGROUND

[0002] With the development of industry and transportation, the amount of waste lubricating oil is huge and continues to grow. Waste lubricating oil is one of the hazardous wastes, which contains heavy metals, chlorine, sulfides and oxidation degradation products, etc., making it environmentally hazardous. During use, lubricating oil will mix with dust, water, worn metal particles and generate sludge, paint film, asphaltene and other oxides. Especially, modern high-performance lubricating oil adds a variety of functional additives, which will decompose or react with impurities during use to produce harmful substances with corrosion. In addition, the friction of mechanical equipment such as engines will cause heavy metal particles to enter the lubricating oil, such as lead, zinc, iron, etc., and long-term use may also produce persistent pollutants such as polychlorinated biphenyls. If these pollution components are not properly treated and directly discharged, they will cause serious harm to the environment and human health.

[0003] In view of the above reasons, the recycling and regeneration of waste lubricating oil is of great significance. On the one hand, it can eliminate its environmental hazards, and on the other hand, the base oil obtained by regeneration can replace part of the crude oil resources. Traditionally, the regeneration methods of waste lubricating oil include acid clay method, vacuum distillation, solvent refining, hydrogenation refining and adsorption processes. However, these methods have certain limitations and deficiencies when dealing with complex waste oil. The acid washing clay method can remove impurities and improve color, but concentrated sulfuric acid will form a large amount of acid sludge with impurities in the oil, which is a hazardous waste, difficult to handle and dispose of, and will cause secondary pollution; the vacuum distillation method relies on high temperature to fractionate base oil fractions from waste oil, but the oil's gum and asphaltene are easy to polymerize and deposit at high temperature, forming coke and hot spots, which will cause equipment coking and plugging, affecting continuous operation and reducing the yield of base oil; the solvent extraction method uses organic solvents to selectively remove impurities, but the residual solvent in the oil after extraction will affect the quality of the regenerated oil; the hydrogenation refining method can deeply remove sulfur, nitrogen and oxides, but requires high temperature and high pressure and noble metal catalyst equipment, with high investment and operating costs; the adsorption refining method needs to consume a large amount of adsorbent, and has limited removal of heavy metals and gum, and the saturated adsorbent also has environmental pressure for regeneration or disposal.

[0004] In recent years, in order to overcome the above shortcomings, researchers have begun to focus on the application of flocculation and sedimentation in waste oil pretreatment. The flocculation-sedimentation process adds a flocculating agent to the waste oil, which makes the gum, asphaltene and suspended particles aggregate into large particles and separate by sedimentation. This method can effectively reduce the solid impurity content in the oil, reduce the load of the subsequent refining process, and the energy consumption is low, however, the traditional inorganic salt flocculant may introduce secondary pollution, residual metal ions or produce a large amount of metal hydroxide sludge.

[0005] In view of the above, it is very important to develop an efficient, environmentally friendly, economic and deep purification of complex waste lubricating oil refining and regeneration technology, the purpose of the present application is to provide a waste lubricating oil refining and regeneration method. SUMMARY

[0006] The present application provides a waste lubricating oil refining and regeneration method, aiming at overcoming the shortcomings of the prior art, providing a waste lubricating oil refining and regeneration method with simple process flow, good treatment effect and environmental friendliness. The method realizes the synergistic removal of metal ions, colloid, asphaltene and solid particles by using an innovative composite pretreatment agent, significantly improves the regeneration efficiency and oil quality.

[0007] The specific technical scheme is as follows:

[0008] A waste lubricating oil refining and regeneration method, as follows:

[0009] S1: Preparation of molecularly imprinted polymer (MIP).

[0010] S11: Dissolve dithizone and glycidyl methacrylate in anhydrous tetrahydrofuran, then add catalyst 4-dimethylaminopyridine, keep the concentration of reaction solution at 0.02mol / L, stir under nitrogen protection, after reaction, cool to room temperature, pour the reaction solution into n-hexane with a temperature of 2℃ for precipitation, filter, wash, vacuum dry, and get modified dithizone functional monomer.

[0011] S12: Dissolve the modified dithizone functional monomer prepared in S11 and mixed template ions in acetonitrile, avoid light and magnetic stirring for 2h, then add crosslinking agent divinylbenzene and initiator azobisisobutyronitrile, stir at 200rpm for 30min, then introduce nitrogen to remove oxygen in the solution, stir and react, after reaction, naturally cool to room temperature, centrifuge, elute, wash, vacuum dry, and get MIP microspheres.

[0012] S2: Preparation of catalyst.

[0013] S21: Dissolve polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in anhydrous ethanol, add concentrated hydrochloric acid as catalyst; stir and add tetra-n-butyl titanate, tetraethyl orthosilicate in turn, then add polymethyl methacrylate microspheres, ultrasonic dispersion for 30min, stir for 24h, seal and age, get wet gel, finally heat and calcine, naturally cool, grind and sieve, get TiO2-SiO2 composite carrier particles.

[0014] S22: Dissolve ammonium molybdate and ammonium dihydrogen phosphate in deionized water to form a solution, then immerse the TiO2-SiO2 composite carrier particles prepared in S21 in the solution, stand for 12 h to ensure uniform impregnation, dry, and reduce phosphorize in a mixed gas of H2 and N2 with a volume ratio of 1:9 in a stepwise temperature increase, cool to room temperature in an H2 atmosphere, to obtain a MoP / TiO2-SiO2 catalyst precursor.

[0015] S23: Soak the MoP / TiO2-SiO2 catalyst precursor prepared in S22 in a toluene solution of octadecyltrichlorosilane (OTS) with a volume fraction of 5%, condense and reflux, cool to room temperature, wash, and vacuum dry to obtain the catalyst MoP / TiO2-SiO2-OTS.

[0016] S3: Waste lubricating oil treatment and regeneration.

[0017] S31: Heat the waste lubricating oil sample to 60℃ to reduce the viscosity, then pass through a high-gradient magnetic separator with a magnetic field strength of 0.8T, and then pass through a vibrating membrane filter to obtain pretreated waste lubricating oil.

[0018] S32: Add the MIP microspheres prepared in S12 to the pretreated waste lubricating oil in S31, stir to perform an adsorption reaction, stop stirring after the adsorption reaction is completed, and perform solid-liquid separation to collect the filtrate.

[0019] S33: Perform low-temperature plasma treatment on the filtrate collected in S32, then stand for 4 h for precipitation to obtain supernatant.

[0020] S34: Mix the supernatant prepared in S33 with ethanol, then load the activated catalyst MoP / TiO2-SiO2-OTS prepared in S23 into a supercritical fluid extraction device for supercritical treatment, separate, and obtain refined oil.

[0021] Further, the reaction solution of S11, wherein the molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine is 1:(1.1-1.5):(0.08-0.15).

[0022] The stirring of S11, with the following parameters: rotation speed 300-500 rpm, temperature 60±2℃, and time 24 h.

[0023] The washing of S11, with 3℃ n-hexane washing 3 times.

[0024] The vacuum drying parameters of S11: vacuum degree -0.095 MPa, temperature 45℃.

[0025] Further, the mixed template ions of S12 are composed of 0.25 mmol of lead nitrate, copper nitrate, zinc nitrate, and cadmium nitrate.

[0026] The modified dithizone functional monomer in S12 is mixed with mixed template ions at a molar ratio of 4:1; the modified dithizone functional monomer is mixed with divinylbenzene at a molar ratio of 1:4 to 1:6; and the mass ratio of the azobisisobutyronitrile to the total mass of the modified dithizone functional monomer is 1 to 2%.

[0027] The stirring reaction in S12 is performed at a rotation speed of 200 rpm, a temperature of 65℃, and for a time period of 12 h.

[0028] The centrifugation in S12 is performed at a rotation speed of 5000 rpm for a time period of 10 min.

[0029] The elution in S12 is performed using a mixed solution of methanol and glacial acetic acid at a volume ratio of 9:1 for 48 h.

[0030] The washing in S12 is performed using pure methanol until the washing liquid is neutral and has no acetic acid smell.

[0031] The vacuum drying in S12 is performed at a vacuum degree of -0.085 MPa and a temperature of 50℃.

[0032] Further, the molar ratio of the titanium tetra-n-butyl ester to the tetraethyl orthosilicate in S21 is 1:2, and the molar ratio of the titanium tetra-n-butyl ester to the tetraethyl orthosilicate to the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:0.008 to 1:0.012.

[0033] The mass of the polymethyl methacrylate microspheres in S21 accounts for 20 to 30% of the mass of the silica.

[0034] The sealed aging in S21 is performed at a temperature of 40℃ for a time period of 48 h.

[0035] The temperature rising calcination in S21 is performed at a first stage of temperature rising to 350℃ at a rate of 1℃ / min and for a time period of 4 h, a second stage of temperature rising to 500℃ at a rate of 2℃ / min and for a time period of 4 h.

[0036] Further, the molar ratio of the ammonium molybdate to the ammonium dihydrogen phosphate in S22 is 1:1.

[0037] The drying in S22 is performed at a temperature of 110℃ for a time period of 12 h.

[0038] The stepwise temperature rising in S22 is performed at a first stage of temperature rising to 200℃ at a rate of 4 to 6℃ / min and for a time period of 1 h, a second stage of temperature rising to 350℃ at a rate of 1℃ / min and for a time period of 2 h, and a third stage of temperature rising to 600℃ at a rate of 1 to 3℃ / min and for a time period of 2 h.

[0039] Further, the condensation reflux in S23 is set as follows: temperature 110℃, time length 6h.

[0040] The washing in S23 is set as follows: anhydrous toluene is used for washing 3 times, and anhydrous ethanol is used for washing 3 times.

[0041] The vacuum drying in S23 is set as follows: vacuum degree -0.085MPa, temperature 80℃, time length 6h.

[0042] Further, the vibrating membrane filtration in S31 is set as follows: temperature 60℃, pressure 0.3MPa, vibrating frequency 50Hz.

[0043] Further, the stirring in S32 is set as follows: rotating speed 250-300rpm, temperature 50℃, time length 1h.

[0044] Further, the low-temperature plasma treatment in S33 is set as follows: power 280-320W, time length 10-20min.

[0045] Further, the mixing in S34 is set as follows: the volume ratio of the supernatant to ethanol is 9:1.

[0046] The activation in S34 is set as follows: H2 atmosphere, temperature 300℃, time length 2h.

[0047] The supercritical treatment in S34 is set as follows: temperature 300-350℃, pressure 20-30MPa, time length 1-2h.

[0048] The separation in S34 is set as follows: first-stage separation temperature 100℃, pressure 8MPa, second-stage separation temperature 40℃, pressure 5MPa.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] 1. The present application can efficiently and selectively adsorb the metal ions by preparing the molecular imprinting polymer, which has high specific recognition and binding sites for the main heavy metal pollutants in the waste lubricating oil, thereby improving the removal efficiency.

[0051] 2. The present application can effectively remove the ferromagnetic wear particles by high-gradient magnetic separation, remove the small mechanical impurities by vibrating membrane filtration, efficiently degrade the residual organic pollutants, oxidation products and colloid in the oil by low-temperature plasma treatment, and realize deep decolorization, deodorization and removal of trace polar substances under mild conditions by supercritical fluid extraction under the action of high-efficiency catalyst.

[0052] 3.The application effectively cracks macromolecular impurities, saturated olefins and removes heteroatoms by preparing the MoP / TiO2-SiO2-OTS catalyst, avoids the use of a large amount of strong acid and active clay in the traditional acid-clay process, and reduces secondary pollution to the environment and the cost of subsequent hazardous waste treatment. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is a waste lubricating oil refining and regeneration process flow chart.

[0054] Figure 2 It is a comparison chart of metal removal rate, oxidation product removal rate, carbon deposition and gum content data of the oil products finally prepared in Examples 1-4 and Comparative Examples 1-3.

[0055] Figure 3 It is an FTIR chart of the oil products finally prepared in Examples 1 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0056] The following examples further explain and illustrate the technical solutions of the application. It is particularly pointed out that each specific embodiment is a specific embodiment and explanation of the technical solution, and should not be regarded as a limitation on the protection scope of the application. Those skilled in the art still have the right to modify the technical solutions of these examples, to make equivalent replacements to some or all of the technical features, and these modifications or replacements do not change the essence of the corresponding technical solution, and do not make the essence of the corresponding technical solution deviate from the scope of the technical solution described in the application.

[0057] The application proposes a waste lubricating oil refining and regeneration method, as shown in the accompanying Figure 1 The application proposes a waste lubricating oil refining and regeneration method, as shown in the accompanying

[0058] 1.Preparation of MIP adsorbent

[0059] 1.1Preparation of functional monomer

[0060] Dithizone and glycidyl methacrylate are dissolved in anhydrous tetrahydrofuran, then a catalyst 4-dimethylaminopyridine is added, the concentration of the reaction solution is maintained at 0.02 mol / L, the reaction is stirred under nitrogen protection at a temperature of 60±2℃, after the reaction is completed, it is cooled to room temperature, the reaction solution is poured into n-hexane with a temperature of 2℃ for precipitation, filtration, washing and vacuum drying to obtain the modified dithizone functional monomer. Dithizone is selected because it can react with up to 20 kinds of metal ions, and can coordinate with Pb 2+ , Cu 2+ , Zn 2+ , Cd 2+The four hydrogen furan in anhydrous state has strong complexing ability. The water will consume glycidyl methacrylate, resulting in its hydrolysis into byproducts, which seriously reduces the yield. The reaction liquid concentration is maintained at 0.02 mol / L because too high concentration may cause viscosity increase or side reactions, and too low concentration reduces the reaction efficiency. The inert gas protection is to prevent oxygen from entering to avoid the pre-polymerization of the methacryloyl group in the glycidyl methacrylate to generate dimers or polymers, thereby ensuring the purity of the functional monomer and the subsequent polymerization activity. The stirring at 60±2℃ is because this temperature is near the reflux temperature of anhydrous tetrahydrofuran, which can provide sufficient reaction kinetic energy to accelerate the ring-opening reaction, while avoiding excessive temperature to cause side reactions. The use of n-hexane washing can effectively remove the 4-dimethylamino pyridine salt, unreacted glycidyl methacrylate and other impurities adsorbed on the surface of the product.

[0061] This step is the ring-opening addition reaction of the epoxy group of glycidyl methacrylate with the active amino group on the dithizone molecule, thereby introducing the methacryloyl group onto the dithizone molecule.

[0062] 1.2 MIP microsphere preparation

[0063] The modified dithizone functional monomer and mixed template ions are dissolved in acetonitrile, magnetically stirred in the dark for 2h, then the crosslinking agent divinylbenzene and the initiator azobisisobutyronitrile are added, stirred at 200rpm for 30min, then nitrogen is introduced to remove oxygen in the solution, the reaction is stirred, after the reaction is completed, it is naturally cooled to room temperature, centrifuged, eluted, washed, vacuum dried to obtain MIP microspheres, wherein the vacuum drying parameters are set as follows: vacuum degree-0.085MPa, temperature 45℃. The types and proportions of the mixed templates are adjusted according to the actual heavy metal components and contents in the waste lubricating oil, and the present application uses lead nitrate, copper nitrate, zinc nitrate and cadmium nitrate each 0.25mmol. The crosslinking agent divinylbenzene provides a rigid structure to maintain the stability of the imprinted cavity. Elution must completely elute the template, otherwise it will seriously affect the adsorption performance and selectivity. Acetic acid can effectively destroy the coordination bond. The vacuum drying temperature is 45℃ in order to prevent the carbon-carbon double bond in the modified dithizone functional monomer from undergoing thermal polymerization at too high a temperature, thereby ensuring its high reactivity in the subsequent MIP polymerization.

[0064] 2. Catalyst preparation

[0065] 2.1 Preparation of TiO2-SiO2 composite carrier

[0066] Polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is dissolved in absolute ethanol, concentrated hydrochloric acid is added as catalyst; stirring and adding tetra-n-butyl titanate, tetraethyl orthosilicate in turn, then adding polymethyl methacrylate microspheres, ultrasonic dispersion for 30 min, stirring for 24 h, aging in a sealed state, obtaining wet gel, finally temperature calcination, natural cooling, grinding and sieving, obtaining TiO2-SiO2 composite carrier particles. Polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is a kind of surfactant, its hydrophilic-hydrophobic segment will self-assemble into micelles in solution, and these micelles act as templates to guide the inorganic polymerization around them to form ordered mesoporous in the process of gelation. Polymethyl methacrylate microspheres provide macropores, TiO2 provides Lewis acid sites, which helps to break the carbon-carbon single bond; SiO2 provides high specific surface area and thermal stability, and the combination of the two can produce a synergistic effect. The first stage of temperature calcination slowly and completely oxidizes and decomposes polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polymethyl methacrylate microspheres, avoiding the collapse of the carrier structure caused by sudden temperature rise; the second stage of inorganic skeleton further condenses and crystallizes to obtain sufficient mechanical strength while eliminating surface unstable groups.

[0067] This step is to solve the diffusion limitation problem of macromolecules such as gum and asphalt, and to provide abundant active site anchoring sites.

[0068] 2.2 Loading of molybdenum phosphide active phase

[0069] Ammonium molybdate and ammonium dihydrogen phosphate are dissolved in deionized water to form a solution, and then the TiO2-SiO2 composite carrier particles prepared above are immersed in the solution, and left to stand for 12 h to ensure uniform impregnation, dried, and reduced and phosphatized in a mixed gas of H2 and N2 with a volume ratio of 1:9 in a stepwise temperature increase, cooled to room temperature in a H2 atmosphere, obtaining MoP / TiO2-SiO2 catalyst precursor. Drying is to remove solvent water, so that metal salts are precipitated in the form of crystals on the inner wall of the pores. The main purpose of the second stage of stepwise temperature increase is to remove crystal water and decompose ammonium salt to generate metal oxide, and the third stage of PH3 is generated by the decomposition of phosphate. Under this condition, MoO3 is reduced and phosphatized, generating highly dispersed MoP particles in situ, and firmly embedding them in the carrier pores.

[0070] The purpose of this step is to fix the highly active catalytic center in a highly dispersed form on the surface of the carrier.

[0071] 2.3 Surface hydrophobic modification

[0072] The MoP / TiO2-SiO2 catalyst precursor was immersed in a toluene solution of octadecyltrichlorosilane (OTS) with a volume fraction of 5%, condensed and refluxed, cooled to room temperature, washed, and vacuum dried to obtain the catalyst MoP / TiO2-SiO2-OTS. The toluene solution of octadecyltrichlorosilane is used to graft long-chain alkyl groups onto the surface of the catalyst, making it hydrophobic from hydrophilic. The principle is that the -Cl group at one end of the octadecyltrichlorosilane molecule reacts with the abundant -OH on the surface of the carrier to form a firm Si-O-Si covalent bond, and the long-chain alkyl group at the other end of the OTS molecule extends outward. Washing and drying are to remove physically adsorbed OTS molecules to obtain a pure modified catalyst.

[0073] The purpose of this step is to fundamentally change the physical and chemical properties of the catalyst surface to make it perfectly compatible with the supercritical CO2 medium.

[0074] 3. Waste lubricating oil treatment and regeneration

[0075] 3.1 Pretreatment

[0076] The waste lubricating oil sample was heated to 60°C to reduce the viscosity, increase the molecular diffusion rate, and thus improve the adsorption efficiency, while avoiding further oxidation of the oil or volatilization of the light components due to excessive temperature. Then it was passed through a high-gradient magnetic separator with a magnetic field strength of 0.8T, and then through a vibrating membrane filter to obtain the pretreated waste lubricating oil.

[0077] 3.2 Adsorption removal

[0078] The pretreated waste lubricating oil described above was added with the MIP microspheres prepared above, and stirring was performed for adsorption reaction. After the adsorption reaction was completed, stirring was stopped, and solid-liquid separation was performed to collect the filtrate. Stirring ensures that the MIP adsorbent particles remain uniformly suspended in the oil and fully contact the oil, avoiding sedimentation.

[0079] 3.3 Low-temperature plasma treatment

[0080] The filtrate described above was subjected to low-temperature plasma treatment, and then allowed to stand for 4h for precipitation to obtain the supernatant. High-energy electrons and active radicals directly attack and break the C-Cl, Si-O-C, P-O chemical bonds of impurity molecules such as chlorinated hydrocarbons, siloxanes, and organophosphorus compounds in the oil, oxidizing and decomposing them into small molecular products such as CO2, H2O, and HCl, thereby deeply removing chlorine, silicon, and phosphorus elements.

[0081] 3.4 Supercritical CO2 fluid extraction-catalysis

[0082] The prepared supernatant is mixed with ethanol, and then mixed with the prepared catalyst MoP / TiO2-SiO2-OTS after activation, and then loaded into a supercritical fluid extraction device for supercritical treatment and separation to obtain refined oil. The supercritical CO2 has the properties of permeability and solubility, and can preferentially extract and enrich the residual polar macromolecular substances such as gum, asphaltene, and modified oxides and condensates by plasma in the oil into the supercritical CO2 fluid phase, thereby realizing the preliminary separation of these impurities from the base oil molecules. The macromolecular impurities extracted into the supercritical CO2 phase are in full contact with the surface of the catalyst MoP / TiO2-SiO2-OTS as the fluid moves, and catalytic cracking and alkylation reactions occur. Complex gum and asphaltene macromolecules are degraded into smaller molecular weight and less polar hydrocarbon fragments. These newly generated small molecular products have a reduced solubility in supercritical CO2 due to their reduced polarity, and are quickly desorbed and redissolved back into the base oil phase. This process not only removes impurities, but also converts waste into useful components, improving the yield and quality of the base oil.

[0083] Example 1

[0084] A method for refining and regenerating waste lubricating oil, as follows:

[0085] Table 1: Main raw materials

[0086]

[0087] S1: Preparation of MIP adsorbent.

[0088] S11: Dissolve dithizone and glycidyl methacrylate in anhydrous tetrahydrofuran, then add catalyst 4-dimethylaminopyridine, keep the concentration of the reaction solution at 0.02 mol / L, stir the reaction under nitrogen protection, after the reaction is completed, cool to room temperature, pour the reaction solution into n-hexane at a temperature of 2℃ for precipitation, filter, wash, and vacuum dry to obtain modified dithizone functional monomer. The molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine is 1:1.2:0.1, the stirring parameters are set as follows: rotation speed 400 rpm, temperature 60℃, and time 24h, the washing is performed with 3℃ n-hexane for 3 times, and the vacuum drying parameters are set as follows: vacuum degree -0.095 MPa, and temperature 45℃.

[0089] S12: The modified dithizone functional monomer prepared in S11 is dissolved in acetonitrile with mixed template ions, and magnetically stirred in the dark for 2 h. Then, the crosslinking agent divinylbenzene and the initiator azobisisobutyronitrile are added, and stirred at 200 rpm for 30 min. Nitrogen is then introduced to remove oxygen in the solution. After the reaction, the solution is naturally cooled to room temperature, centrifuged, eluted, washed, and vacuum dried to obtain MIP microspheres. The mixed template ions are lead nitrate, copper nitrate, zinc nitrate, and cadmium nitrate, each at 0.25 mmol. The molar ratio of the modified dithizone functional monomer to the mixed template ions is 4:1. The molar ratio of the modified dithizone functional monomer to divinylbenzene is 1:5, and the mass of azobisisobutyronitrile accounts for 1.5% of the total mass of the modified dithizone functional monomer. The stirring reaction parameters are set as follows: rotation speed 200 rpm, temperature 65°C, and time 12 h. The centrifugation parameters are set as follows: rotation speed 5000 rpm and time 10 min. The elution is performed using a mixed solution of methanol and glacial acetic acid with a volume ratio of 9:1 for 48 h. The washing is performed using pure methanol until the eluate is neutral and has no acetic acid smell. The vacuum drying parameters are set as follows: vacuum degree -0.085 MPa and temperature 50°C.

[0090] S2: Catalyst preparation.

[0091] S21: The polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is dissolved in anhydrous ethanol, and concentrated hydrochloric acid is added as a catalyst. The titanium tetrabutoxide and tetraethyl orthosilicate are then added in sequence, followed by the addition of polymethyl methacrylate microspheres. The mixture is ultrasonically dispersed for 30 min, stirred for 24 h, and then sealed for aging. Finally, the wet gel is calcined by increasing the temperature, naturally cooled, ground, and sieved to obtain TiO2-SiO2 composite carrier particles. The molar ratio of titanium tetrabutoxide to tetraethyl orthosilicate is 1:2, and the molar ratio of titanium tetrabutoxide, tetraethyl orthosilicate, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:0.01. The mass of the polymethyl methacrylate microspheres accounts for 25% of the mass of the silica. The sealing aging parameters are set as follows: temperature 40°C and time 48 h. The temperature calcination parameters are set as follows: the first stage is to increase the temperature to 350°C at a rate of 1°C / min, and the second stage is to increase the temperature to 500°C at a rate of 2°C / min, with a holding time of 4 h in each stage.

[0092] S22: Dissolve ammonium molybdate and ammonium dihydrogen phosphate in deionized water to prepare a solution, then immerse the TiO2-SiO2 composite carrier particles prepared in S21 in the solution, stand for 12 h to ensure uniform impregnation, dry, and reduce phosphorize in a mixed gas of H2 and N2 with a volume ratio of 1:9 in a stepwise temperature increase, cool to room temperature in an H2 atmosphere, to obtain a MoP / TiO2-SiO2 catalyst precursor. Among them, the molar ratio of ammonium molybdate and ammonium dihydrogen phosphate is 1:1; the drying parameter setting is: temperature 110℃, time 12h; the stepwise temperature increase parameter setting is: the first stage is heated to 200℃ at a rate of 5℃ / min, the holding time is 1h, the second stage is heated to 350℃ at a rate of 1℃ / min, the holding time is 2h, the third stage is heated to 600℃ at a rate of 2℃ / min, the holding time is 2h.

[0093] S23: Soak the MoP / TiO2-SiO2 catalyst precursor prepared in S22 in a toluene solution of octadecyltrichlorosilane (OTS) with a volume fraction of 5%, condense and reflux, cool to room temperature, wash, and vacuum dry to obtain the catalyst MoP / TiO2-SiO2-OTS. Among them, the condensation and reflux parameter setting is: temperature 110℃, time 6h; the washing uses anhydrous toluene to wash 3 times, and then uses anhydrous ethanol to wash 3 times; the vacuum drying parameter setting is: vacuum degree -0.085MPa, temperature 80℃, time 6h.

[0094] S3: Waste lubricating oil treatment and regeneration.

[0095] S31: Heat the waste lubricating oil sample to 60℃ to reduce the viscosity, then pass through a high gradient magnetic separator with a magnetic field strength of 0.8T, and then pass through a vibrating membrane filter to obtain pretreated waste lubricating oil. Among them, the vibrating membrane filter parameter setting is: temperature 60℃, pressure 0.3MPa, vibration frequency 50Hz.

[0096] S32: Add the MIP microspheres prepared in S12 to the pretreated waste lubricating oil in S31, stir to perform an adsorption reaction, after the adsorption reaction is completed, stop stirring, separate the solid and liquid, and collect the filtrate. Among them, the stirring parameter setting is: speed 275rpm, temperature 50℃, time 1h.

[0097] S33: Perform low temperature plasma treatment on the filtrate collected in S32, then stand for 4h for precipitation to obtain the supernatant. The low temperature plasma parameter setting is: power 300W, time 15min.

[0098] S34: The supernatant prepared in S33 is mixed with ethanol, and then loaded into a supercritical fluid extraction device with the catalyst MoP / TiO2-SiO2-OTS prepared in S23 after activation for supercritical treatment, separation, to obtain refined oil. The volume ratio of the supernatant to ethanol is 9:1; the activation parameter setting: H2 atmosphere, temperature 300°C, time 2h; the supercritical treatment parameter setting: temperature 325°C, pressure 25MPa, time 1.5h; the separation parameter setting: first-stage separation temperature 100°C, pressure 8MPa, second-stage separation temperature 40°C, pressure 5MPa.

[0099] Example 2

[0100] Referring to the composition and preparation process of Example 1, the difference is that:

[0101] In S11 of the preparation process, the molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine is 1:1.1:0.08, and the other components are the same.

[0102] In S11 of the preparation process, the stirring parameter setting is: rotation speed 300rpm, temperature 58°C, and the other steps are the same.

[0103] In S12 of the preparation process, the molar ratio of modified dithizone functional monomer to divinylbenzene is 1:4, and the mass fraction of azobisisobutyronitrile in the total mass of modified dithizone functional monomer is 1%, and the other components are the same.

[0104] In S21 of the preparation process, the molar ratio of tetra-n-butyl titanate, tetraethyl orthosilicate, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:0.008, and the mass fraction of polymethyl methacrylate microspheres in the mass of silica is 20%, and the other components are the same.

[0105] In S22 of the preparation process, the stepwise heating parameter setting is: first-stage heating rate 4°C / min, third-stage heating rate 1°C / min, and the other steps are the same.

[0106] In S32 of the preparation process, the stirring parameter setting is: rotation speed 250rpm, and the other steps are the same.

[0107] In S33 of the preparation process, the low-temperature plasma parameter setting is: power 280W, time 10min, and the other steps are the same.

[0108] In S34 of the preparation process, the supercritical treatment parameter setting is: temperature 300°C, pressure 20MPa, time 1h, and the other steps are the same.

[0109] Example 3

[0110] Referring to the composition and preparation process of Example 1, the difference is that:

[0111] The molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine in S11 of the preparation process is 1:1.5:0.15, and the other components are the same.

[0112] The stirring parameter setting in S11 of the preparation process is: rotation speed 500 rpm, temperature 62°C, and the other steps are the same.

[0113] The molar ratio of modified dithizone functional monomer to divinylbenzene in S12 of the preparation process is 1:6, and the mass of azobisisobutyronitrile accounts for 2% of the total mass of the modified dithizone functional monomer, and the other components are the same.

[0114] The molar ratio of titanium tetrabutoxide, tetraethyl orthosilicate, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in S21 of the preparation process is 1:0.012, and the mass of polymethyl methacrylate microspheres accounts for 30% of the mass of silica, and the other components are the same.

[0115] The stepwise heating parameter setting in S22 of the preparation process is: the first stage heating rate is 6°C / min, and the third stage heating rate is 3°C / min, and the other steps are the same.

[0116] The stirring parameter setting in S32 of the preparation process is: rotation speed 300 rpm, and the other steps are the same.

[0117] The low-temperature plasma parameter setting in S33 of the preparation process is: power 320W, time 20min, and the other steps are the same.

[0118] The supercritical treatment parameter setting in S34 of the preparation process is: temperature 350°C, pressure 30MPa, time 2h, and the other steps are the same.

[0119] Example 4

[0120] Referring to the composition and preparation process of Example 1, the difference is:

[0121] The molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine in S11 of the preparation process is 1:1.4:0.09, and the other components are the same.

[0122] The stirring parameter setting in S11 of the preparation process is: rotation speed 350 rpm, temperature 59°C, and the other steps are the same.

[0123] The molar ratio of modified dithizone functional monomer to divinylbenzene in S12 of the preparation process is 1:5.5, and the mass of azobisisobutyronitrile accounts for 1.3% of the total mass of the modified dithizone functional monomer, and the other components are the same.

[0124] The molar ratio of tetra-n-butyl titanate, tetraethyl orthosilicate and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in S21 of the preparation process was 1:0.011, the mass of polymethyl methacrylate microspheres accounted for 28% of the mass of silica, and the other components were the same.

[0125] In S22 of the preparation process, the stepwise heating parameter setting was as follows: the first stage heating rate was 4℃ / min, the third stage heating rate was 1℃ / min, and the other steps were the same.

[0126] In S32 of the preparation process, the stirring parameter setting was as follows: the rotation speed was 260 rpm, and the other steps were the same.

[0127] In S33 of the preparation process, the low-temperature plasma parameter setting was as follows: the power was 290 W, the time length was 13 min, and the other steps were the same.

[0128] In S34 of the preparation process, the supercritical treatment parameter setting was as follows: the temperature was 340℃, the pressure was 28 MPa, the time length was 1.8 h, and the other steps were the same.

[0129] Comparative Example 1

[0130] Referring to the composition and preparation process of Example 1, the difference is that:

[0131] In S3 of the preparation process, the MIP microsphere adsorption treatment was cancelled, and the other steps were the same.

[0132] Comparative Example 2

[0133] Referring to the composition and preparation process of Example 1, the difference is that:

[0134] In S3 of the preparation process, the low-temperature plasma treatment was cancelled, and the MIP adsorption was directly followed by supercritical treatment, and the other steps were the same.

[0135] Comparative Example 3

[0136] Referring to the composition and preparation process of Example 1, the difference is that:

[0137] In S3 of the preparation process, the catalyst MoP / TiO2-SiO2-OTS treatment was deleted, and the supercritical CO2 treatment was deleted and only N-methyl pyrrolidone was used for solvent extraction, and the other steps were the same.

[0138] In summary, Examples 1-4 and Comparative Examples 1-3, the initial waste lubricating oil and the final prepared oil sample were taken, and the metal removal rate test was carried out, and the standard GB / T 10476-2023 "Determination of multiple elements in lubricating oil and base oil by inductively coupled plasma emission spectrometry" was referred to.

[0139] Combining Examples 1-4 and Comparative Examples 1-3, samples were taken from the initial waste lubricating oil and the final prepared oil, and the removal rate of oxidation products was tested. The results were determined by Fourier transform infrared spectroscopy, referring to the standard ASTM D7414 "Standard Test Method for Monitoring the Oxidation State of Petroleum and Hydrocarbon-Based Lubricants in Use by Trend Analysis of Fourier Transform Infrared Spectroscopy (FT-IR)". Figure 3 The FTIR plots for Example 1 and Comparative Examples 1-3 are provided by... Figure 3 It can be seen that the range is 1700-1750cm. -1 It mainly consists of oxidation products represented by carbonyl groups; at 3000 cm⁻¹ -1 Nearby, the main products are water, alcohols, etc., represented by hydroxyl groups; at 1300–1500 cm⁻¹ -1 It mainly consists of hydrocarbon compounds represented by CH.

[0140] Based on Examples 1-4 and Comparative Examples 1-3, samples of the final prepared oil were taken and tested for carbon deposit and gum content. Thermogravimetric analysis was performed, referring to the standard ASTM D6375-24 "Standard Test Method for Determination of Evaporation Loss of Lubricating Oils by Thermogravimetric Analyzer (TGA) Noack Method".

[0141] The specific test results are shown in Table 2. Figure 2 As shown:

[0142] Table 2 Comparison of core performance between Examples 1-4 and Comparative Examples 1-3:

[0143]

[0144] The comparison results above show that Example 1 has the best overall performance. MIP adsorption accurately removes heavy metals, low-temperature plasma efficiently degrades oxidation products and colloids, and supercritical catalytic treatment achieves deep decolorization, deodorization, and oil stabilization. This indicates that Example 1 successfully solves the current problems of complex waste lubricating oil composition, containing various additives, metal fragments, and degradation products. The overall performance of Examples 2 to 4 is slightly lower than that of Example 1, but still maintains a high level. This shows that excellent extraction results were achieved even with a wide range of parameter variations. In Comparative Example 1, the removal of MIP adsorption resulted in a significant decrease in metal removal rate. At the same time, the removal of oxidation products and carbon deposits was also affected. In Comparative Example 2, the removal of low-temperature plasma treatment resulted in poor removal of oxidation products and colloids. In Comparative Example 3, solvent extraction was used instead of a catalyst, resulting in incomplete metal removal, ineffective oxidation treatment, high carbon deposit content, and dark oil color.

[0145] In summary, through the above examples and comparative examples, it can be clearly seen that the waste lubricating oil refining and regeneration method provided by the present application is significantly better than the traditional scheme in metal removal, oxidation removal, carbon deposition and gum content, which is due to the adoption of MIP adsorption, low-temperature plasma treatment and supercritical catalytic treatment, thereby realizing the refining and regeneration of waste lubricating oil.

Claims

1. A method for refining and regenerating waste lubricating oil, characterized in that: the method comprises adsorbing heavy metal ions by using a molecular imprinting polymer, and further comprises low-temperature plasma treatment, high-energy electron and active radical bombardment and breakage of chemical bonds of impurity molecules in the oil product to oxidize and decompose the impurity molecules into small molecular products, thereby deeply removing chlorine, silicon and phosphorus elements, and further comprises supercritical CO2 treatment and catalyst degradation, the permeability and solubility of CO2 are used to efficiently extract and enrich polar macromolecular substances remaining in the oil product into a supercritical CO2 fluid phase, thereby realizing preliminary separation of the impurities from base oil molecules; the molecular imprinting polymer is prepared by using lead, copper, zinc and cadmium ions as mixed templates, and by using a modified dithizone functional monomer and a crosslinking agent, the modified dithizone functional monomer is prepared by ring-opening addition reaction of dithizone and glycidyl methacrylate; the catalyst is MoP / TiO2-SiO2-OTS, in which molybdenum phosphide modified by octadecyltrichlorosilane is loaded on a TiO2-SiO2 composite carrier, the TiO2-SiO2 composite carrier is prepared by using a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer as a mesoporous template agent and adding polymethyl methacrylate microspheres as a macropore pore-forming agent, and the impurities are degraded into hydrocarbon fragments through catalytic cracking and alkylation, thereby desorbing and redissolving the impurities into the base oil phase; the method specifically comprises: heating waste lubricating oil samples to 60 DEG C to reduce the viscosity, then passing through a high-gradient magnetic separator with a magnetic field strength of 0.8T, and then passing through a vibrating membrane filter to obtain pretreated waste lubricating oil; adding molecular imprinting polymer microspheres to the pretreated waste lubricating oil, stirring to perform an adsorption reaction, stopping stirring after the adsorption reaction is completed, and then performing solid-liquid separation to collect a filtrate; performing low-temperature plasma treatment on the filtrate, and then standing for 4 hours to perform precipitation to obtain supernatant; mixing the supernatant with ethanol, and then loading the mixture and an activated catalyst MoP / TiO2-SiO2-OTS into a supercritical fluid extraction device to perform supercritical treatment and separation, thereby obtaining refined oil. the preparation of the molecular imprinting polymer and the catalyst comprises the following steps:

2. The method for refining and regenerating used lubricating oil according to claim 1, characterized by, S1: preparing the molecular imprinting polymer; S11: dissolving dithizone and glycidyl methacrylate in anhydrous tetrahydrofuran, then adding a catalyst 4-dimethylaminopyridine, keeping the concentration of the reaction solution at 0.02 mol / L, stirring under nitrogen protection, cooling to room temperature after the reaction is completed, pouring the reaction solution into n-hexane with a temperature of 2 DEG C for precipitation, filtering, washing and vacuum drying, and obtaining a modified dithizone functional monomer; ​ S12: The modified dithizone functional monomer prepared in S11 is dissolved in acetonitrile with mixed template ions, and stirred magnetically in the dark for 2 hours. Then, the crosslinking agent divinylbenzene and the initiator azobisisobutyronitrile are added, and stirred at 200 rpm for 30 minutes. Then, nitrogen is introduced to remove oxygen in the solution. The solution is stirred and reacted. After the reaction is completed, it is naturally cooled to room temperature, centrifuged, eluted, washed, and vacuum dried to obtain molecularly imprinted polymer microspheres; S2: Catalyst preparation; S21: The polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is dissolved in anhydrous ethanol, and concentrated hydrochloric acid is added as a catalyst. Stirring is performed, and then titanium tetrabutoxide and tetraethyl orthosilicate are added in sequence. Then, the polymethyl methacrylate microspheres are added, ultrasonic dispersion is performed for 30 minutes, stirring is performed for 24 hours, and the wet gel is obtained after aging in a sealed state. Finally, the temperature is increased for calcination, and the TiO2-SiO2 composite carrier particles are obtained after natural cooling, grinding, and sieving; S22: Ammonium molybdate and ammonium dihydrogen phosphate are dissolved in deionized water to form a solution. Then, the TiO2-SiO2 composite carrier particles prepared in S21 are immersed in the solution, and are allowed to stand for 12 hours to ensure uniform impregnation. After drying, the MoP / TiO2-SiO2 catalyst precursor is obtained by stepwise reduction and phosphatization in a mixed gas of H2 and N2 with a volume ratio of 1:9, and is cooled to room temperature in an H2 atmosphere.

3. The method for refining and regenerating waste lubricating oil according to claim 2, characterized in that: In the reaction solution of S11, the molar ratio of dithizone, glycidyl methacrylate, and 4-dimethylaminopyridine is 1: (1.1-1.5): (0.08-0.15); In the stirring of S11, the parameters are set as follows: rotation speed 300-500 rpm, temperature 60±2°C, and time 24 hours; In the washing of S11, n-hexane at 3°C is used for washing 3 times; In the vacuum drying of S11, the parameters are set as follows: vacuum degree -0.095 MPa, and temperature 45°C.

4. The method for refining and regenerating waste lubricating oil according to claim 2, characterized in that: The mixed template ions in S12 are composed of 0.25 mmol of lead nitrate, copper nitrate, zinc nitrate, and cadmium nitrate; In S12, the molar ratio of the modified dithizone functional monomer to the mixed template ions is 4:1, the molar ratio of the modified dithizone functional monomer to divinylbenzene is 1:4-1:6, and the mass ratio of azobisisobutyronitrile to the total mass of the modified dithizone functional monomer is 1-2%; In the stirring reaction of S12, the parameters are set as follows: rotation speed 200 rpm, temperature 65°C, and time 12 hours; In the centrifugation of S12, the parameters are set as follows: rotation speed 5000 rpm, and time 10 minutes; In the elution of S12, a mixed solution of methanol and glacial acetic acid with a volume ratio of 9:1 is used for elution for 48 hours. ​ The washing described in S12 involves washing with pure methanol until the washing solution is neutral and has no acetic acid odor. The vacuum drying described in S12 has the following parameter settings: vacuum degree -0.085MPa, temperature 50℃.

5. The method for refining and regenerating waste lubricating oil according to claim 2, characterized in that: The molar ratio of tetrabutyl titanate to tetraethyl orthosilicate described in S21 is 1:2, and the molar ratio of tetrabutyl titanate to tetraethyl orthosilicate: polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:0.008 to 1:0.

012. The polymethyl methacrylate microspheres described in S21 account for 20-30% of the mass of silica. The sealing aging process described in S21 has the following parameter settings: temperature 40℃, duration 48h. The heating and roasting process described in S21 has the following parameter settings: in the first stage, the temperature is increased to 350℃ at a rate of 1℃ / min and held for 4 hours; in the second stage, the temperature is increased to 500℃ at a rate of 2℃ / min and held for 4 hours.

6. The method for refining and regenerating waste lubricating oil according to claim 2, characterized in that: The ammonium molybdate and ammonium dihydrogen phosphate described in S22 have a molar ratio of 1:1; The drying process described in S22 has the following parameters: temperature 110℃, duration 12h. The stepped heating parameters set in S22 are as follows: the first stage is heated to 200℃, the heating rate is 4-6℃ / min, and the holding time is 1h; the second stage is heated to 350℃, the heating rate is 1℃ / min, and the holding time is 2h; the third stage is heated to 600℃, the heating rate is 1-3℃ / min, and the holding time is 2h.

7. The method for refining and regenerating waste lubricating oil according to claim 2, characterized in that: The condensation reflux described in S23 has the following parameter settings: temperature 110℃, duration 6h; The washing process described in S23 involves first washing three times with anhydrous toluene, and then washing three times with anhydrous ethanol. The vacuum drying described in S23 has the following parameters: vacuum degree -0.085MPa, temperature 80℃, and duration 6h.

8. The method for refining and regenerating waste lubricating oil according to claim 1, characterized in that: The parameters for the vibrating membrane filter are: temperature 60℃, pressure 0.3MPa, and vibration frequency 50Hz. The stirring parameters are set as follows: rotation speed 250-300 rpm, temperature 50℃, and duration 1 hour. The parameters for the low-temperature plasma treatment are: power 280-320W, duration 10-20min. The mixture is wherein the volume ratio of the supernatant to ethanol is 9:1; The activation parameters are set as follows: H2 atmosphere, temperature 300℃, duration 2h; The supercritical treatment parameters are set as follows: temperature 300-350℃, pressure 20-30MPa, and duration 1-2h. The separation is performed after the supercritical treatment, with the following parameter settings: first-stage separation temperature 100℃, pressure 8MPa, second-stage separation temperature 40℃, pressure 5MPa.

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