Lubricating oil recycling method based on combination of membrane separation and ultrafiltration

Abstract

The invention relates to the technical field of comprehensive utilization of waste mineral oil, in particular to a lubricating oil recycling method based on combination of membrane separation and ultrafiltration. The invention discloses a lubricating oil recycling method based on combination of membrane separation and ultrafiltration, which comprises the following steps: firstly, preheating waste lubricating oil, then adding an adsorbent, stirring, standing and filtering to obtain primarily purified oil, the adsorbent being composed of multiple components such as silanized basalt fiber and the like; secondly, the preliminarily purified oil is separated through a microfiltration membrane and an ultrafiltration membrane, a refined base oil precursor is obtained, the microfiltration membrane contains basalt fibers and the like, and the ultrafiltration membrane is of a metal organic framework-ionic liquid type; then, a hydro-upgrading agent is added into the refined base oil precursor for hydrogenation, hydrogenated base oil is obtained, and the hydro-upgrading agent is a cerium-doped nickel molybdenum phosphorus / zirconium-based metal organic framework; and finally, preheating the hydrogenated base oil, adding an anti-wear agent, performing high-speed shearing, adding an antioxidant, stirring, distilling, and filtering to obtain the lubricating oil, thereby realizing efficient regeneration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of waste mineral oil, and particularly relates to a lubricating oil recycling method based on membrane separation and ultrafiltration. BACKGROUND

[0002] During the use of waste lubricating oil, various impurities such as carbon black, colloidal particles, metal scraps, sulfur, nitrogen and aromatic hydrocarbons are mixed into the waste lubricating oil, and aldehydes, ketones, asphaltene and other substances are also generated due to oxidation and other reactions, which leads to performance degradation. Most of the components in the waste lubricating oil have recycling value, and the recycling treatment of the waste lubricating oil can not only save resources but also reduce environmental pollution, and thus has important significance.

[0003] Traditional waste lubricating oil regeneration processes have many limitations. For example, strong acids and strong bases and other substances may be used in the treatment process, which is easy to cause environmental pollution; the energy consumption is high, and the operation is complex; it is difficult to completely remove various impurities, the quality of the regenerated oil is unstable, and it is difficult to balance the key performances such as wear resistance and oxidation resistance, which cannot meet the use requirements of high-end equipment.

[0004] Membrane separation technology has potential in the field of waste lubricating oil regeneration due to its high efficiency, energy saving and no pollution, and can effectively separate part of the impurities. However, single membrane separation technology may face problems such as oil adhesion and membrane pollution in the treatment process, and it is difficult to completely separate impurities of different sizes, and the purification effect is limited.

[0005] A membrane treatment integrated process for purifying and regenerating waste lubricating oil is disclosed in Chinese Patent No. CN103289807A. In the process, the waste lubricating oil is subjected to natural sedimentation to remove impurities, and then subjected to extraction separation with a polar organic solvent to obtain a mixed liquid, oil residue and water. The mixed liquid is separated into oil and solvent in a separation tower, and the solvent is recovered and reused. The separated waste lubricating oil is heated to reduce viscosity, and then subjected to coarse filtration with a metal filter, fine filtration with a metal membrane to remove impurities, clay adsorption to remove pollutants, plate and frame filtration to remove clay, and finally addition of additives to prepare a regenerated lubricating oil product. The patent relies on clay adsorption, and only physically adsorbs impurities through the porous structure, which may result in a large loss of oil and weak adsorption of complex impurities. Only a single-stage filtration with a metal membrane may not be sufficient to trap small polar impurities, and the risk of membrane contamination is high. There is no hydrogenation modification step, and only conventional performance additives are added, and the regenerated base oil may not be sufficient in chemical stability and use performance.

[0006] A method and system for continuous production of base oil from waste mineral oil containing chlorine and silicon are disclosed in Chinese Patent Publication No. CN119591660A. First, the waste mineral oil is subjected to thermal settling to preliminarily remove solid particles, sludge, moisture and other impurities. Then, the waste mineral oil enters a flash evaporation device to separate light component oil and heavy component oil. The heavy component oil is first reacted with a heavy oil dechlorination agent to remove chlorine, and then with a metal removal agent to remove metal impurities. After vacuum distillation, fraction oil, light fraction and residue oil are obtained. The light component oil is subjected to oil-water separation and then added to the light fraction to complete dechlorination with a light oil dechlorination agent. The dechlorinated light oil is mixed with the residue oil and filtered through a ceramic nanofiltration membrane or a silicon carbide tubular membrane. The obtained clear liquid and fraction oil are subjected to adsorption desiliconization in an adsorption desiliconization tank. Finally, after three-stage hydrogenation reaction and rectification, solvent oil, industrial white oil and base oil are obtained. This patent mainly relies on thermal settling, dechlorination agent, metal removal agent and chelating resin adsorption desiliconization, and has good treatment effect on specific impurities such as chlorine, silicon and metal. However, it lacks multi-component collaborative design for the adsorption of complex impurities such as gum, asphaltene and acidic substances in waste oil. Single ceramic nanofiltration membrane or silicon carbide tubular membrane filtration is used to remove large particle impurities, but the precision of intercepting small polar impurities is limited, and the anti-clogging relies on a backwashing system. After hydrogenation and rectification, the products such as base oil are obtained directly, and the anti-wear and anti-oxidation properties of the products are not specially optimized, and the lubricating performance of the products may be insufficient in high load and high temperature environments.

[0007] In summary, the combination of membrane separation and ultrafiltration, combined with adsorption, hydro-upgrading, and the addition of composite additives, forms a synergistic treatment system, which is an important direction for the deep regeneration of waste lubricating oil. This combined method can take advantage of each process, achieve gradient removal of different impurities, improve the purity and performance of the regenerated oil, reduce pollution and energy consumption, and meet the requirements of green environmental protection and resource efficient utilization. SUMMARY

[0008] To solve the above problems, the purpose of the present application is to provide a lubricating oil recycling method based on the combination of membrane separation and ultrafiltration, which specifically comprises the following steps: S001, preheat the waste lubricating oil, add an adsorbent, and perform adsorption and filtration treatment to obtain preliminary purified oil; S002, pass the preliminary purified oil into a microfiltration membrane and an ultrafiltration membrane for separation treatment to obtain refined base oil precursor; S003, add a hydro-upgrading agent to the refined base oil precursor for hydrogenation treatment to obtain hydrogenated base oil; S004, preheat the hydrogenated base oil, slowly add an anti-wear agent, perform high-speed shearing treatment, slowly add an antioxidant, perform stirring and vacuum distillation treatment, cool to room temperature, and then filter to obtain lubricating oil.

[0009] The waste lubricating oil in step S001 is preheated to 60-80 ℃, the adsorbent is added at 2% of the oil mass, the adsorption treatment is first stirred at 300 rpm for 30 min, and then static treatment is performed for 2 h, and the filtration treatment is performed by plate and frame filtration.

[0010] The conditions for microfiltration membrane separation treatment in step S002 are 1.0 MPa pressure, 70 ℃, cross-flow rate of 3.5 m / s, and backwashing cycle of 6 h, and the conditions for ultrafiltration membrane separation treatment are 0.6 MPa pressure and 100 ℃.

[0011] The addition amount of the hydro-upgrading agent in step S003 is 1.5% of the mass of the refined base oil precursor, and the hydroprocessing conditions are 14.5 MPa pressure, 355 ℃, 10 L / h hydrogen flow rate, and 2 h.

[0012] The preheating treatment conditions in step S004 are 65 ℃, 200 rpm for 10 min, the addition amount of the anti-wear agent is 2% of the hydrogenated base oil, the high-speed shearing treatment conditions are 1000 rpm and 15 min, the stirring treatment conditions are 300 rpm and 30 min, and the vacuum distillation treatment conditions are 120 ℃, -0.09 MPa, and 2 h.

[0013] The adsorbent is composed of basalt fibers with silanized surfaces, silica networks derived from tetraethyl orthosilicate, modified copolymers of acrylamide-maleic anhydride-N-isopropyl acrylamide, sodium allyl sulfonate, and trimethylsiloxy groups derived from hexamethyldisilazane, with mass ratios of 5:85:9:0.3:0.1, respectively. The specific preparation method includes the following steps: S101, immerse the basalt fibers in a hydrochloric acid solution, shake, wash, and dry, immerse in a γ-aminopropyltriethoxysilane solution, reflux, wash, and dry to obtain pretreated basalt fibers; S102, perform deoxygenation treatment on the acrylamide-maleic anhydride copolymer and N-isopropyl acrylamide added in an ethanol solution, add potassium persulfate initiator, perform polymerization treatment, and after cooling, perform dialysis and freeze-drying to obtain the modified copolymer; S103, mix the modified copolymer in an ethanol solution, slowly add sodium allyl sulfonate, stir, add the pretreated basalt fibers for dispersion treatment, and adjust the pH; S104, add the catalyst dropwise and stir, add formamide for gelation treatment, add hexamethyldisilazane solution for oleophobic treatment, wash, dry, and stabilize to obtain the adsorbent.

[0014] The concentration of the hydrochloric acid solution in step S101 is 1 M, the conditions of the shaking treatment are 60 °C, 150 rpm, and 2 h, the conditions of the drying treatment are 110 °C and 2 h, the solution of γ-aminopropyltriethoxysilane is a 2% γ-aminopropyltriethoxysilane ethanol solution with a pH of 4.5-5.5, the conditions of the reflux treatment are 70 °C and 4 h, then the sample is cooled to room temperature, washed with anhydrous ethanol for 3 times, and the conditions of the drying treatment are 60 °C, -0.09 MPa, and 1 h.

[0015] The molar ratio of acrylamide-maleic anhydride copolymer to N-isopropyl acrylamide in step S102 is 10:1, the ethanol solution is a 70% aqueous ethanol solution with a pH of 8.0-9.0, the conditions of the deoxidation treatment are 65 °C, nitrogen, and 30 min, the concentration of the potassium persulfate initiator is 0.5%, and the conditions of the polymerization treatment are 65 °C, nitrogen, and 3 h, then the sample is cooled to room temperature, transferred to a dialysis bag with a molecular weight cut-off of 8000-14000, dialyzed in ultrapure water for 72 h, and the conditions of the freeze-drying treatment are -50 °C and 24 h.

[0016] The mass ratio of the modified copolymer, sodium allyl sulfonate, and the pretreated basalt fiber in step S103 is 9:0.3:5, the ethanol solution is an 80% aqueous ethanol solution with a pH of 8.5-9.5, the conditions of the mixing treatment are 40 °C and 300 rpm until dissolution, the conditions of the stirring treatment are 60 °C, 300 rpm, and 30 min, the conditions of the dispersion treatment are 0-2 °C, 500 W, and 30 min, and the pH is 9-10.

[0017] The catalyst in step S104 is composed of tetraethyl orthosilicate-ethanol solution and polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, the mass ratio of tetraethyl orthosilicate, polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, and formamide is 1:0.1:0.5, the molar ratio of tetraethyl orthosilicate to ethanol is 1:4, the conditions of the stirring treatment are 25 °C, 300 rpm, and 20 min, the conditions of the gelation treatment are first standing at 40 °C for 24 h and then immersing in anhydrous ethanol for aging for 24 h, the mass ratio of hexamethyldisilazane to the pretreated basalt fiber is 1:50, the solution of hexamethyldisilazane is 3.4 mg / mL, the conditions of the oleophobic treatment are 80 °C and 6 h, the sample is washed with anhydrous ethanol for 5 times after cooling, and the conditions of the drying treatment are first immersing in tert-butyl alcohol for 24 h, then pre-freezing for 6 h at -40 °C, drying at -50 °C and 10 Pa for 24 h, the conditions of the stabilization treatment are placing in a supercritical device at 40 °C, 10 MPa, and 2 h, then immersing in an ethanol-acetic acid solution with a volume ratio of 9:1, microwave irradiation at 60 °C and 300 W for 10 min, and then drying at 40 °C for 30 min.

[0018] The microfiltration membrane is a ceramic microfiltration membrane containing basalt fibers, cerium oxide and a surface grafted sodium dodecyl benzene sulfonate hydrophobic segment, and the specific preparation method comprises the following steps: S201, the pretreated basalt fibers, cerium oxide and alumina are added into anhydrous ethanol and a dispersant, homogenate, molding, sintering treatment, and the sintered membrane is obtained; S202, the sintered membrane is immersed in a modification solution for modification treatment, and the microfiltration membrane is obtained.

[0019] The pretreated basalt fibers in step S201 are first soaked in 5% dilute hydrochloric acid for 30 min, then washed with ultrapure water until neutral, and then dried at 120 DEG C. The mass ratio of the pretreated basalt fibers, cerium oxide and alumina is 3:1:96, anhydrous ethanol is added at a solid-liquid mass volume ratio of 1:3, the dispersant is 0.5% polyacrylic acid, the homogenate treatment is by 300 rpm ball milling for 24 h, the molding treatment is first dried at 60 DEG C for 24 h, then dried at 80 DEG C for 12 h, the sintering treatment is heated to 600 DEG C at a rate of 5 DEG C / min for 1 h, then heated to 1200 DEG C at a rate of 3 DEG C / min for 2 h, and then cooled to room temperature.

[0020] The modification solution in step S202 is 5% sodium dodecyl benzene sulfonate ethanol solution, and the modification treatment is first reacted at 80 DEG C for 4 h, then washed with anhydrous ethanol for 3 times, and then dried at 80 DEG C.

[0021] The ultrafiltration membrane is a metal organic framework-ionic liquid ultrafiltration membrane, and the specific preparation method comprises the following steps: S301, the chromium-based MIL-101 is immersed in lithium-based ionic liquid for loading and vacuum drying treatment, and the filler is obtained; S302, the filler is added into N-methyl pyrrolidone for ultrasonic treatment, and polyether sulfone is added for dispersion treatment, and the casting solution is obtained; S303, the casting solution is subjected to film scraping and solidification treatment, and the ultrafiltration membrane is obtained.

[0022] The loading treatment in step S301 is carried out at 60 DEG C, 300 rpm for 24 h, and the vacuum drying treatment is carried out at -0.09 MPa, 120 DEG C for 24 h.

[0023] The ultrasonic treatment in step S302 is carried out at 500 W for 30 min, and the dispersion treatment is first carried out at 60 DEG C, 300 rpm for 12 h, and then static for 6 h, and the mass ratio of the filler, N-methyl pyrrolidone and polyether sulfone is 12:73:15.

[0024] The blade coating treatment in step S303 is to coat the casting solution on the polyester non-woven fabric substrate to form a liquid film, and the curing treatment is to first immerse in 30% N-methyl pyrrolidone aqueous solution at 25 DEG C, then immerse in ultrapure water at 60 DEG C for 48 h, and finally air dry at room temperature for 24 h.

[0025] The hydrogenation modification agent is cerium-doped nickel molybdenum phosphorus / zirconium-based metal organic framework, and the specific preparation method comprises the following steps: S401, the zirconium-based UiO-66 metal organic framework is immersed in an active component solution for adsorption treatment; S402, cerium is added for stirring treatment, a complexing agent is added for aging, drying, calcination and reduction treatment, and a cerium-doped nickel molybdenum phosphorus / zirconium-based metal organic framework is obtained, which is denoted as a hydrogenation modification agent.

[0026] The active component solution in step S401 is composed of nickel sulfate, ammonium heptamolybdate and ammonium hydrogen phosphate, and the molar ratio is 1:0.8:0.5, and the carrier loading is 15%, and the adsorption treatment conditions are 60 DEG C, 300 rpm and 4 h.

[0027] In step S402, the amount of cerium oxide is 0.2% of the mass of the carrier, the stirring treatment conditions are 60 DEG C and 300 rpm for 2 h, the complexing agent is 0.5 M citric acid with a volume of 10% of the total solution, the aging treatment conditions are 80 DEG C for 12 h, the drying treatment conditions are 120 DEG C, -0.09 MPa and 8 h, the calcination treatment conditions are 400 DEG C under nitrogen for 3 h, and the reduction treatment conditions are 350 DEG C under a mixed protective gas for 4 h, and the mixed protective gas is a mixed gas of 70% nitrogen and 30% hydrogen.

[0028] The anti-wear agent is composed of zinc dialkyldithiophosphate, titanium dioxide coated antimony-doped tin oxide and polyisobutylene succinimide, the mass ratio of zinc dialkyldithiophosphate to titanium dioxide coated antimony-doped tin oxide is 5:1, and the addition amount of polyisobutylene succinimide is 0.5% of the hydrogenated base oil, the zinc dialkyldithiophosphate and the titanium dioxide coated antimony-doped tin oxide are added into the polyisobutylene succinimide, and then stirring is carried out at -20 DEG C and 500 rpm for 30 min, and the anti-wear agent is obtained.

[0029] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and diphenylamine, and the addition amounts of 2,6-di-tert-butyl-p-cresol and diphenylamine are 0.2% and 0.1% of the hydrogenated base oil respectively, the 2,6-di-tert-butyl-p-cresol and the diphenylamine are mixed, stirring is carried out at 60 DEG C and 200 rpm for 20 min, and the antioxidant is obtained.

[0030] Compared with the prior art, the present application has the following beneficial effects: 1.The adsorbent of the present application realizes high-efficiency selective adsorption through the synergistic effect of multiple components. The basalt fiber with silanized surface provides a rigid skeleton, the modification of gamma-aminopropyl triethoxysilane introduces amino groups that can adsorb polar impurities through hydrogen bonds; the silica network derived from tetraethyl orthosilicate forms a porous structure, providing a large number of adsorption sites; the acrylamide-maleic anhydride-N-isopropyl acrylamide modified copolymer contains polar groups that can selectively adsorb polar impurities, and the sulfonic acid groups introduced by sodium allyl sulfonate enhance hydrophilicity, further strengthening the adsorption of polar impurities; the oil-repellent treatment of hexamethyldisilazane can reduce the adsorption of lubricating oil components and reduce oil loss. The adsorbent can efficiently remove harmful impurities such as condensed n-pentane insoluble matter, condensed toluene insoluble matter, and acidic substances from waste lubricating oil, and can maintain stable adsorption performance after multiple cycles, with good durability; 2.The present application realizes deep purification through gradient membrane material design and combined process. The basalt fiber reinforced ceramic membrane as the base can improve the impact strength, the doping of cerium oxide can decompose part of the organic impurities, the surface grafting of sodium dodecyl benzene sulfonate hydrophobic segment can reduce the adhesion of oil on the membrane surface and reduce pollution; the metal organic framework of the ultrafiltration membrane provides high porosity, and the lithium-based ionic liquid enhances the selective retention of polar small molecule impurities. Microfiltration pretreatment removes large particles to reduce the load of ultrafiltration membrane, and ultrafiltration deeply retains small molecule impurities, realizing gradient separation of coarse and fine purification, effectively improving the purity of the oil, and making the refined base oil precursor pure and transparent. At the same time, the microfiltration membrane has strong anti-clogging ability, and the reverse flushing interval is prolonged; the ultrafiltration membrane can maintain stable filtration performance for a long time, and has a long service life. The temperature setting is connected with the waste oil preheating process, which can avoid energy waste caused by repeated heating and meet the green environmental protection concept; 3.The hydrogenation modification agent of the present application improves the performance through the synergistic effect of carrier, active component, and dopant. The zirconium-based UiO-66 metal organic framework as the carrier has high specific surface area and uniform pore size, which can uniformly disperse the active component; the active components nickel, molybdenum, and phosphorus respectively act as hydrogenation active center, desulfurization active center, and component to promote the dispersion of active component, which can remove sulfur, nitrogen, and aromatic hydrocarbons; the dopant cerium can enhance the reducibility of nickel through electron transfer effect, improve the hydrogenation activity, and can adsorb hydrogen molecules and dissociate into active hydrogen atoms. The hydrogenation modification agent can effectively remove impurities such as sulfur, nitrogen, and aromatic hydrocarbons in lubricating oil, improve the hydrogenation modification depth; can improve the performance of base oil, increase the viscosity index to enhance the viscosity temperature stability, and reduce the pour point to improve the low temperature fluidity; and has good stability, slow activity decay after long-term continuous use, can reduce the frequency of catalyst replacement, and reduce the cost; 4. The present application solves the problem of difficult to balance anti-wear and anti-oxidation by the synergistic effect of composite anti-wear-anti-oxidation additives. The polyisobutylene succinimide, zinc dialkyldithiophosphate and titanium dioxide coated with antimony-doped tin oxide in the anti-wear agent synergistically form a dual anti-wear mechanism of chemical film and physical filling, in which the zinc dialkyldithiophosphate forms a chemical adsorption film to improve the anti-wear property, the titanium dioxide coated with antimony-doped tin oxide nanoparticles fill the friction surface to realize physical strengthening, and the polyisobutylene succinimide can disperse the nanoparticles to avoid their agglomeration. The 2,6-di-tert-butyl-p-cresol and diphenylamine in the anti-oxidant are compounded and then improve the anti-oxidation efficiency through synergistic effect, the 2,6-di-tert-butyl-p-cresol captures free radicals to inhibit the oxidation chain reaction, and the diphenylamine decomposes peroxide to terminate oxidation. High-speed shearing is used to ensure uniform dispersion of the anti-wear agent, and vacuum distillation is used to remove low-boiling impurities to avoid additive failure, so that the regenerated waste lubricating oil has good anti-wear ability and oxidation resistance, even in high temperature environment for a long time, it can still maintain stable performance, the viscosity change is small, and it can provide reliable lubrication for equipment; 5. The present application realizes efficient regeneration through whole-process process parameter matching and functional complementation. The adsorption pretreatment is matched with the operating temperature of the microfiltration membrane, which can avoid the viscosity rise caused by oil fraction cooling and reduce the membrane separation energy consumption; the membrane separation removes colloidal / macro-molecular impurities, which can reduce the load of the hydrogenation modifier and avoid the impurities covering the active sites; the hydrogenation modified base oil provides a stable matrix for the additives to ensure that the anti-wear agent and the anti-oxidant can fully play their roles; the filtration / washing process is used in each step to avoid secondary pollution of impurities. This process can effectively improve the conversion rate of waste lubricating oil, and the use of recyclable adsorbent and high-efficiency membrane separation system avoids the use of high-pollution treatment methods such as strong acid and strong base, reduces the generation of pollutants from the source, reduces the impact on the ecological environment, and meets the green process concept. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with specific embodiments.

[0032] Example 1: A lubricating oil treated by the adsorbent of the present application, specifically comprising the following steps: 1. Preparation of the adsorbent of the present application: 10 g of basalt fiber was immersed in 500 mL of hydrochloric acid solution, shaken at 60 ℃ and 150 rpm for 2 h, washed with ultrapure water until neutral, dried at 110 ℃ for 2 h, immersed in 500 mL of 2% γ-aminopropyltriethoxysilane ethanol solution with pH 5, refluxed at 70 ℃ for 4 h, cooled to room temperature, washed with anhydrous ethanol for 3 times, and dried at 60 ℃ and -0.09 MPa for 1 h to obtain the pretreated basalt fiber. Mix 17.8 g acrylamide-maleic anhydride copolymer and 1.13 g N-isopropyl acrylamide into 200 mL 70% ethanol aqueous solution with pH of 8.5, 65 ℃, nitrogen treatment for 30 min, add 0.1 g potassium persulfate initiator, 65 ℃, nitrogen polymerization treatment for 3 h, cool to room temperature, transfer to dialysis bag, dialysis in ultrapure water for 72 h, dry at-50 ℃ for 24 h, to obtain the modified copolymer; Mix 15.2 g modified copolymer into 250 mL 80% ethanol aqueous solution with pH of 9.0, 40 ℃, 300 rpm until dissolved, slowly add 0.51 g sodium allyl sulfonate, 60 ℃, 300 rpm stirring for 30 min, slowly add 8.5 g pretreated basalt fiber, 0~2 ℃, 500 W ultrasonic dispersion for 30 min, adjust pH to 9.5; Mix 2.5 g tetraethyl orthosilicate, 2.2 g anhydrous ethanol and 0.25 g polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer to obtain the catalyst; Drop the catalyst, 25 ℃, 300 rpm stirring for 20 min, add 1.25 g formamide, first gel by standing at 40 ℃ for 24 h, then immerse in anhydrous ethanol for aging for 24 h, add 50 mL of 3.4 mg / mL hexamethyldisilazane ethanol solution, 80 ℃ oleophobic treatment for 6 h, after cooling, wash with anhydrous ethanol for 5 times, immerse in t-butyl alcohol for 24 h, pre-freeze at-40 ℃ for 6 h, dry at-50 ℃, 10 Pa for 24 h, 40 ℃, 10 MPa supercritical treatment for 2 h, immerse in ethanol-acetic acid solution with a volume ratio of 9:1, 60 ℃, 300 W microwave irradiation for 10 min, 40 ℃ drying for 30 min, to obtain the adsorbent of the application.

[0033] 2. A method for treating lubricating oil: Preheat 500 g waste lubricating oil to 70 ℃, add 10 g adsorbent of the application, 300 rpm stirring for 30 min, stand for 2 h, filter by plate and frame filter, to obtain the preliminary purified oil, recorded as test sample 1.

[0034] Example 2: A lubricating oil treated by the combined treatment of the microfiltration membrane and ultrafiltration membrane of the application, specifically comprising the following steps: 1. Preparation of the microfiltration membrane of the application: Soak the basalt fiber in 5% dilute hydrochloric acid for 30 min, rinse to neutral with ultrapure water, and dry at 120 ℃; Sintered membrane was obtained by adding 3 g of pretreated basalt fiber, 1 g of cerium oxide and 96 g of aluminum oxide into 300 mL of anhydrous ethanol and 0.5 g of 0.5% polyacrylic acid dispersant, ball milling homogenate for 24 h at 300 rpm, drying at 60 ℃ for 24 h, then drying at 80 ℃ for 12 h, forming, heating to 600 ℃ at 5 ℃ / min, treating for 1 h, then increasing to 1200 ℃ at 3 ℃ / min, treating for 2 h, and then cooling to room temperature. The sintered membrane was immersed in a 5% sodium dodecylbenzenesulfonate ethanol solution modification solution, first reacted at 80 ℃ for 4 h, then washed with anhydrous ethanol for 3 times, and then dried at 80 ℃, to obtain a microfiltration membrane.

[0035] 2. Preparation of the ultrafiltration membrane of the application: The 12 g of chromium-based MIL-101 was immersed in a lithium-based ionic liquid, and was treated by loading at 60 ℃ and 300 rpm for 24 h, and then dried at -0.09 MPa and 120 ℃ for 24 h, to obtain the filler. S302, 12 g of the filler was added to 73 g of N-methylpyrrolidone, and was ultrasonicated at 500 W for 30 min, 15 g of polyethersulfone was added, and was dispersed at 60 ℃ and 300 rpm for 12 h, and then was left to stand for 6 h, to obtain the casting solution. S303, the casting solution was scraped and coated on a polyester non-woven fabric substrate to form a liquid film, was immersed in a 30% N-methylpyrrolidone aqueous solution at 25 ℃, was immersed in ultrapure water at 60 ℃ for 48 h, and was left to dry at room temperature for 24 h, to obtain the ultrafiltration membrane.

[0036] 3. A treatment method of lubricating oil: The test sample 1 was passed into the microfiltration membrane at a pressure of 1.0 MPa, 70 ℃, and a cross-flow rate of 3.5 m / s, and then was passed into the ultrafiltration membrane at a pressure of 0.6 MPa and 100 ℃ after a backwashing period of 6 h, to obtain a refined base oil precursor, which was recorded as test sample 2.

[0037] Example 3: A lubricating oil treated by the hydrogen modification agent of the application, specifically comprising the following steps: 1. Preparation of the hydrogen modification agent of the application: 0.43 g of nickel sulfate, 2.41 g of ammonium heptamolybdate and 0.18 g of ammonium hydrogen phosphate were added into 100 mL of ultrapure water, to obtain an active component solution. 20 g of zirconium-based UiO-66 metal organic framework was immersed in the active component solution, and was adsorbed at 60 ℃ and 300 rpm for 4 h. Add 0.04 g of cerium oxide, 60°C, 300 rpm stirring for 2 h, add 10 mL of 0.5 M citric acid complexing agent, 80°C for 12 h, 120°C, -0.09 MPa drying for 8 h, 400°C under nitrogen for 3 h, 350°C under a mixture of 70% nitrogen and 30% hydrogen protective gas for 4 h, to obtain cerium-doped nickel-molybdenum-phosphorus / zirconium-based metal-organic framework, denoted as hydro-upgrading agent.

[0038] 2. The method for treating lubricating oil comprises the following steps: The 200 g of test product 2 is added with 3 g of hydro-upgrading agent, and hydrogenated at a pressure of 14.5 MPa, 355°C, and a hydrogen flow rate of 10 L / h for 2 h to obtain the hydrogenated base oil, denoted as test product 3.

[0039] Example 4: A lubricating oil treated with the anti-wear agent and antioxidant of the present application, specifically comprising the following steps: 1. Preparation of the anti-wear agent of the present application: 5 g of polyisobutylene succinimide, 12.5 g of zinc dialkyldithiophosphate, and 2.5 g of titanium dioxide coated with antimony-doped tin oxide are added to a 50 mL beaker, and stirred at -20°C and 500 rpm for 30 min to obtain the anti-wear agent.

[0040] 2. Preparation of the antioxidant of the present application: 2 g of 2,6-di-tert-butyl-p-cresol is mixed with 1 g of diphenylamine, and stirred at 60°C and 200 rpm for 20 min to obtain the antioxidant.

[0041] 3. The method for treating lubricating oil comprises the following steps: The test product 3 is preheated to 65°C, maintained at 200 rpm for 10 min, slowly added with the anti-wear agent, and treated with high-speed shearing at 1000 rpm for 15 min, slowly added with the antioxidant, stirred at 300 rpm for 30 min, distilled at 120°C and -0.09 MPa for 2 h, and filtered after cooling to room temperature to obtain the lubricating oil, denoted as test product 4.

[0042] Comparative Example 1 A lubricating oil treated with activated carbon, specifically comprising the following steps: The difference from Example 1 is that 800-mesh activated carbon is used instead of the adsorbent of the present application, and the remaining steps are performed according to the method for treating lubricating oil in Example 1 to obtain Comparative Product 1.

[0043] Comparative Example 2 A lubricating oil treated with diatomite, specifically comprising the following steps: The difference from Example 1 is that 500-mesh diatomite is used instead of the adsorbent of the application, and the rest of the steps are performed according to the treatment method of the lubricating oil in Example 1, to obtain a control sample 2.

[0044] Comparative Example 3 A lubricating oil treated by a single ceramic microfiltration membrane and a single organic ultrafiltration membrane, specifically comprising the following steps: The difference from Example 2 is that a single ceramic microfiltration membrane with a pore size of 0.2 μm is used instead of the microfiltration membrane of the application, and a single organic ultrafiltration membrane with a molecular weight cut-off of 1000 Da is used instead of the ultrafiltration membrane of the application, and the rest of the steps are performed according to the treatment method of the lubricating oil in Example 2, to obtain a control sample 3.

[0045] Comparative Example 4 A lubricating oil treated by a nickel-molybdenum-phosphorus catalyst / alumina hydrogenation catalyst, specifically comprising the following steps: The difference from Example 3 is that a nickel-molybdenum-phosphorus catalyst / alumina hydrogenation catalyst is used instead of the hydrogenation modifier of the application, and the rest of the steps are performed according to the treatment method of the lubricating oil in Example 3, to obtain a control sample 4.

[0046] Comparative Example 5 A lubricating oil treated by adding a single anti-wear agent and a single antioxidant, specifically comprising the following steps: The difference from Example 4 is that zinc dialkyldithiophosphate is used instead of the anti-wear agent of the application, and 2,6-di-tert-butyl-p-cresol is used instead of the antioxidant of the application, and the rest of the steps are performed according to the treatment method of the lubricating oil in Example 4, to obtain a control sample 5.

[0047] Experimental Example 1 This experimental example tests the high-efficiency selective adsorption performance of the test sample of Example 1 and the control samples of Comparative Examples 1-2, specifically comprising the following steps: 1. Comparative experiment of adsorption efficiency: Determination of coagulated n-pentane insoluble matter: Add 50 mL of n-butyl diethanolamine and 50 mL of isopropyl alcohol to 1 L of n-pentane solvent to mix, to obtain a n-pentane-coagulant solution; Put a clean centrifuge tube into a 105 ℃±3 ℃ oven to dry for 30 min, cool in a desiccator, and weigh the centrifuge tube, with the weight recorded as m0; Put 10.0 g of the waste lubricating oil in Example 1, Test Sample 1, Control Sample 1, Control Sample 2 into the centrifuge tube respectively, add n-pentane-coagulant solution to the 100 mL mark, plug the stopper, shake and mix, centrifuge at 1500 r / min for 20 min, pour the supernatant, and make the remaining liquid less than 3 mL; add 10 mL of n-pentane, stir and disperse the precipitate, add n-pentane to the 50 mL mark, shake and mix, centrifuge at 1500 r / min for 20 min, pour out the supernatant, and complete one washing, and repeat to complete one washing; Put the centrifuge tube into a 105 ℃±3 ℃ oven and dry for 30 min, cool in a desiccator, and weigh, and record the weight as m1, 3 parallels for each sample.

[0048] According to the ratio of the difference between m1 and m0 to the sample weight, the mass fraction of n-pentane insoluble after coagulation is calculated.

[0049] Determination of toluene insoluble after coagulation: Mix 50 mL of toluene and 50 mL of 95% ethanol to obtain a toluene-ethanol solution; Put a clean centrifuge tube into a 105 ℃±3 ℃ oven and dry for 30 min, cool in a desiccator, and weigh the centrifuge tube, and record the weight as m2; Put 10.0 g of the waste lubricating oil in Example 1, Test Sample 1, Control Sample 1, Control Sample 2 into the centrifuge tube respectively, add n-pentane-coagulant solution to the 100 mL mark, plug the stopper, shake and mix, centrifuge at 1500 r / min for 20 min, pour the supernatant, and make the remaining liquid less than 3 mL; add 10 mL of n-pentane, stir and disperse the precipitate, add n-pentane to the 50 mL mark, shake and mix, centrifuge at 1500 r / min for 20 min, pour out the supernatant, and complete one washing, and repeat to complete one washing; Add 10 mL of toluene-ethanol solution, stir and disperse the precipitate, add toluene-ethanol solution to the 50 mL mark, shake and mix, centrifuge at 1500 r / min for 20 min, pour the supernatant, add 10 mL of toluene, stir and disperse the precipitate, add toluene to the 50 mL mark, shake and mix, centrifuge at 1500 r / min for 20 min, pour the supernatant. Put the centrifuge tube into a 105 ℃±3 ℃ oven and dry for 1 h, cool in a desiccator, and weigh, and record the weight as m3, 3 parallels for each sample.

[0050] According to the ratio of the difference between m3 and m1 to the sample weight, the mass fraction of toluene insoluble after coagulation is calculated, and the results are shown in Table 1.

[0051] The mass fraction of insoluble gum after coagulation was calculated according to the difference between the mass fraction of n-pentane insoluble after coagulation and the mass fraction of toluene insoluble after coagulation, and the results are shown in Table 1.

[0052] Determination of the content of acidic substances: 100 mL of toluene and 100 mL of isopropanol were mixed to obtain a toluene-isopropanol mixed solvent; 10 g of the waste lubricating oil in Example 1, Test Sample 1, Control Sample 1 and Control Sample 2 were respectively placed in a 250 mL beaker, 125 mL of the toluene-isopropanol mixed solvent was added, and the samples were completely dissolved by stirring. Each sample was repeated 3 times. The beaker was placed on an electromagnetic stirrer, a glass electrode and a calomel electrode were inserted, and a potentiometric titrator was connected. The titration was performed with a 0.1 mol / L potassium hydroxide isopropanol standard solution, the potential change during titration was recorded, the titration end point was determined, and the volume of the consumed potassium hydroxide isopropanol standard solution was read.

[0053] The content of acidic substances was calculated by the ratio of the product of the volume of the consumed potassium hydroxide isopropanol standard solution, the concentration of the potassium hydroxide isopropanol standard solution and the molar mass of potassium hydroxide to the mass of the sample, and the results are shown in Table 1.

[0054] The impurity content was calculated by the total value of the mass fraction of toluene insoluble after coagulation, the mass fraction of insoluble gum after coagulation and the content of acidic substances, taking the waste lubricating oil in Example 1 as the initial. The impurity removal rate was calculated according to the ratio of the difference between the initial impurity content and the impurity content after treatment to the initial impurity content, and the results are shown in Table 1.

[0055] 2. Stability cycle experiment: The adsorbents obtained from the comparison experiment of adsorption efficiency were collected, washed with anhydrous ethanol for 3 times, and then dried at 60°C. The dried adsorbents were used again for adsorption of waste lubricating oil, and the adsorption experiment was repeated 5 times.

[0056] The impurity removal rate in the 5th time was measured according to the comparison experiment of adsorption efficiency. The decay rate was calculated according to the ratio of the difference between the first removal rate and the impurity removal rate in the 5th time to the first removal rate, and the results are shown in Table 1.

[0057] Table 1 Results of the comparison experiment of adsorption efficiency

[0058] As can be seen from Table 1, the mass fraction of the toluene insoluble after coagulation of Example 1 is 0.12%, and the mass fraction of insoluble gum is 0.18%, which is much lower than those of Comparative Examples 1 and 2, indicating that the adsorbent of the present application has stronger adsorption capacity for the two types of substances, and can effectively reduce the content of such impurities in the lubricating oil. The content of acidic substances in Example 1 is only 0.1%, while that in Comparative Example 1 is 1.4% and that in Comparative Example 2 is 1.7%, which shows that the adsorbent of the present application has good removal effect on acidic substances and can optimize the acid value of the lubricating oil. The impurity removal rate of Example 1 is as high as 97.3%, which is much lower than that of Comparative Examples 1 and 2, indicating that the adsorbent of the present application can more efficiently remove impurities in the lubricating oil and improve the purity of the oil product. The attenuation rate of Example 1 is 6.9%, which is much lower than that of Comparative Examples 1 and 2, indicating that the adsorbent of the present application has good stability, and the adsorption performance decreases little after multiple cycles, and has good durability.

[0059] In summary, when the adsorbent of the present application is used to treat lubricating oil, it is significantly superior to activated carbon and diatomite in reducing the content of various insoluble substances and acidic substances after coagulation, improving the impurity removal rate, and maintaining the stability of the adsorbent, and can effectively optimize the quality of the lubricating oil product, and has good application potential.

[0060] Experimental Example 2 In this experimental example, gradient membrane separation test of the microfiltration membrane and the ultrafiltration membrane of the present application was carried out on the test sample of Example 2 and the control sample of Comparative Example 3, which specifically included the following steps: 1. Determination of impurity content: 100 mL G4 glass sand core funnel was dried in an oven at 105±2 ℃ until constant weight, weighed, and the weight was recorded as m4, 3 parallels for each sample; 100 g of test sample 2 and control sample 3 were respectively placed in a 250 mL beaker, 60 mL of toluene was added, heated to 80 ℃ in a water bath and stirred until completely dissolved, transferred to a G4 glass sand core funnel, filtered under reduced pressure while hot, washed with 80 ℃ toluene for 5 times, and the G4 glass sand core funnel containing impurities was placed in a 105±2 ℃ oven for drying for 50 min, cooled to room temperature, and weighed, the weight was recorded as m5, 3 parallels for each sample.

[0061] According to the ratio of the difference between m5 and m4 to the mass of the sample, the mechanical impurity content was calculated, and the results are shown in Table 2.

[0062] 2. Determination of light transmittance: The test sample 2 and the control sample 3 were respectively loaded into a cuvette, and the light transmittance of the sample was determined by a UV-visible spectrophotometer at a wavelength of 600 nm, 3 parallels for each sample, with test sample 1 as a reference, and the light transmittance of the sample was recorded, and the results are shown in Table 2.

[0063] Table 2 Determination results of impurity content and light transmittance

[0064] As can be seen from Table 2, Example 2 adopts the microfiltration membrane and ultrafiltration membrane of the present application for combined treatment of lubricating oil, and Comparative Example 3 adopts single ceramic microfiltration membrane and single organic ultrafiltration membrane for treatment. In terms of mechanical impurity content, Example 2 is far lower than Comparative Example 3, indicating that the combined membrane of the present application can more efficiently intercept mechanical impurities and improve the cleanliness of the oil product; in terms of light transmittance, Example 2 is significantly higher than Comparative Example 3, reflecting that after treatment by the combined membrane of the present application, there are fewer impurities affecting light transmittance in the lubricating oil, and the oil product has better light transmittance, further demonstrating that the microfiltration membrane and ultrafiltration membrane used in combination in the present application are superior to conventional single membrane combination in optimizing the quality of lubricating oil, and exhibit the advantages of gradient membrane separation.

[0065] Experimental Example 3 In this experimental example, the performance of the hydrogenation modification agent of Example 3 and the control product of Comparative Example 4 was tested, which included the following steps: 1. Hydrogenation efficiency comparison experiment: Sulfur content determination: 0.2 g of the test product 2, the test product 3 and the control product 4 were weighed in a porcelain boat, which was covered with fine sand. The porcelain boat was placed in the high temperature zone of a tubular furnace porcelain tube, and the stopper was quickly inserted. The air flow was connected to the flow meter at 500 mL / min, and the tubular furnace was burned at a temperature of 900-950 ℃ for 35 min. The receiver was removed, the glass bend was washed with distilled water, the bromocresol green-methyl red mixed indicator was added, and the 0.02 mol / L sodium hydroxide standard solution was titrated until the solution changed from purple red to dark green. The volume of the consumed sodium hydroxide standard solution was recorded, and each sample was tested in triplicate.

[0066] The sulfur content was calculated according to the ratio of the product of the concentration of the sodium hydroxide standard solution, the volume of the consumed sodium hydroxide standard solution and the molar mass of sulfur to the mass of the sample. The sulfur content of the test product 2 was taken as the sulfur content before hydrogenation.

[0067] Nitrogen content determination: 10 mg of 8-hydroxyquinoline was added to a 100 mL volumetric flask, which was diluted to the calibration line with xylene to obtain a nitrogen standard stock solution; 10 mL, 1 mL, 0.1 mL, 0.01 mL, 0.005 mL of the nitrogen standard stock solution were taken into 100 mL volumetric flasks, respectively, which were diluted to the calibration line with xylene to obtain a nitrogen standard working solution; 1 g of the test product 2, the test product 3 and the control product 4 were dissolved in 5 g of xylene, respectively, to obtain the sample to be tested; Inject 5 μL of the sample and nitrogen standard working solution into the boat of the chemiluminescence instrument, crack oxygen 360±36 mL / min, inlet oxygen 60±6 mL / min, carrier gas 155±15 mL / min, boat injection speed 150±10 mm / min, detect chemiluminescence response value, 3 parallel for each sample, with dimethylbenzene as blank; Draw the standard curve with the concentration of the nitrogen standard working solution as the abscissa and the response value as the ordinate. Calculate the concentration of the sample according to the response value, and then calculate the nitrogen content according to the dilution multiple and sample quality. Take the nitrogen content of sample 2 as the nitrogen content before hydrogenation.

[0068] Aromatic hydrocarbon content determination: Fill activated silica gel into the adsorption column to half the height of the separation section, add a 3-5 mm thick dyed silica gel layer, and continue to fill silica gel to 75 mm of the loading section, and compact for 4 min under 100 Hz vibration; Inject 0.75 mL of sample 2, sample 3, and control 4 into the silica gel 30 mm below the loading section, and then add isopropyl alcohol to the spherical joint after complete adsorption; Connect the gas supply system, and maintain at 14 kPa for 2.5 min, then at 34 kPa for 2.5 min, and finally adjust to 28-69 kPa. When the red alcohol-aromatic hydrocarbon interface enters the analysis section 350 mm, mark the upper end of the aromatic hydrocarbon region under ultraviolet light 365 nm, which is the upper end of the first red-brown ring. After the hydrocarbons descend 50 mm, mark the second time in reverse. Place the adsorption column horizontally, measure the length of the aromatic hydrocarbon region marked twice, measure the upper end of the first red-brown ring to the front of the clear liquid sample, and record the total length of the hydrocarbon region. 3 parallel for each sample.

[0069] Calculate the aromatic hydrocarbon content by the ratio of the aromatic hydrocarbon length to the total length of the hydrocarbon region. Take the aromatic hydrocarbon content of sample 2 as the aromatic hydrocarbon content before hydrogenation.

[0070] Calculate the impurity content after hydrogenation by the sum of sulfur content, nitrogen content, and aromatic hydrocarbon content. Calculate the impurity removal rate after hydrogenation according to the ratio of the difference between the impurity content before hydrogenation and the impurity content after hydrogenation to the impurity content before hydrogenation. The results are shown in Table 3.

[0071] 2. Base oil performance test: Viscosity index determination: Inject 10 mL of sample 3 and control 4 into the test tube, respectively, and place it in a 40 ℃ water bath for 30 min. Measure the kinematic viscosity of the sample at 40 ℃ using a kinematic viscosity tester. 3 parallel for each sample; Respectively, 10 mL of test product 3, control product 4 were added into test tubes, and were placed in 100℃ water bath for 30 min, the kinematic viscosity of 100℃ sample was determined by kinematic viscosity tester, 3 parallel samples for each sample; According to the kinematic viscosity of 40℃ sample, the kinematic viscosity of 100℃ sample, viscosity index was calculated by GB / T 1995-1998 Petroleum Products Viscosity Index Calculation Method Method B, the results were shown in Table 3.

[0072] Pour point determination: Respectively, 10 mL of test product 3, control product 4 were added into test tubes, and were placed in 100℃ water bath for 30 min, the kinematic viscosity of 100℃ sample was determined by kinematic viscosity tester, 3 parallel samples for each sample; The test tube containing sample was placed in the cold bath sleeve, the liquid level of the test tube was flush with the cold bath liquid level, and the cooling rate was about 3℃ / min, the test tube was taken out from the sleeve every 3℃, and was inclined at 45° for 5 s, 3 parallel samples for each sample; The lowest temperature at which the sample could flow was recorded as the pour point, and the results were shown in Table 3.

[0073] 3. Hydrogenation modifier stability experiment The hydrogenation modifier used after the first example 3, comparative example 4 experiment was collected, washed with anhydrous ethanol 3 times, dried at 60℃ for 2 h, and was used for example 3, comparative example 4 experiment again, respectively, the hydrogenation modifier was used for 2 times, the test product and control product after the 100th use were collected, and the impurity removal rate of the hydrogenation modifier after the 100th use was determined according to the method in the hydrogenation efficiency comparison experiment, 3 parallel samples for each sample.

[0074] According to the ratio of the difference between the impurity removal rate after the first hydrogenation and the impurity removal rate after the 100th hydrogenation to the impurity removal rate after the first hydrogenation, the activity attenuation rate was calculated, and the results were shown in Table 3.

[0075] Table 3 Comparison experiment results of adsorption efficiency

[0076] As can be seen from Table 3, the hydrogenation improver of the present application is used in Example 3, and the impurity removal rate after hydrogenation is as high as 97.2%; the nickel-molybdenum-phosphorus catalyst / alumina hydrogenation catalyst is used in Comparative Example 4, and the removal rate is only 53.2%. It is shown that the hydrogenation improver of the present application has a significantly better effect on the hydrogenation removal of impurities such as sulfur, nitrogen and aromatic hydrocarbons in lubricating oil, can greatly reduce the content of impurities after hydrogenation, and improve the hydrogenation modification depth of oil products. The viscosity index of Example 3 is 140.8±1.3, which is higher than that of Comparative Example 4, indicating that the smaller the change of lubricating oil viscosity with temperature, the better the temperature stability of the lubricating oil after being treated by the hydrogenation improver of the present application, which is beneficial to the use in a wide temperature range. The pour point of Example 3 is-25.3±0.6℃, which is lower than that of Comparative Example 4, indicating that the lubricating oil has good low-temperature fluidity, and the hydrogenation improver of the present application can effectively improve the low-temperature performance of the lubricating oil, which has obvious advantages in cold environment and other scenarios. The activity attenuation rate of Example 3 is 3.6%, which is lower than that of Comparative Example 4, indicating that the hydrogenation activity of the hydrogenation improver of the present application decreases by a small margin after 100 cycles, and the stability and durability are far superior to those of the conventional nickel-molybdenum-phosphorus / alumina hydrogenation catalyst, which can reduce the cost of frequent catalyst replacement and is suitable for industrial continuous production application.

[0077] In summary, the hydrogenation improver of the present application has obvious advantages in improving the hydrogenation efficiency of lubricating oil, optimizing the performance of base oil and ensuring its stability, and can effectively help upgrade the lubricating oil hydrogenation modification process and improve product quality and production economy.

[0078] Experimental Example 4 In this experimental example, the synergistic system effect of the anti-wear-antioxidant composite additives of the test products of Examples 3-4 and the control product of Comparative Example 5 is verified, which specifically includes the following steps: 1. Anti-wear performance test: The test is performed by a four-ball extreme pressure tester. Three steel balls are placed in the recess of the oil box and fixed by a compression ring. The test products 3, 4 and the control product 5 are poured into the oil box to submerge the steel balls and reach the joint between the compression ring and the screw cap. The balls are loaded into the chuck and fixed on the main shaft. The main shaft rotates at a speed of 1450±50 r / min, the load is 392 N, and the test time is 10 s. The test phenomenon is recorded to see whether there is jamming, noise or smoking.

[0079] The steel balls are taken out and washed with petroleum ether. The diameter of each steel ball wear scar is measured, and the results are shown in Table 4.

[0080] 2. Anti-oxidation performance test: 5 mL of the test products 3, 4 and the control product 5 are taken respectively and injected into clean glass sample cups. One polished copper sheet is placed in each sample cup, and each sample has 3 parallels. Put 50 mL ultrapure water into the oxygen bomb, fix the sample cup on the sample holder in the oxygen bomb, cover the oxygen bomb tightly, fill oxygen to 690 kPa, close the air inlet valve, stand for 5 min, put the oxygen bomb into a 150 ℃ constant temperature water bath, rotate the oxygen bomb at a speed of 100±5 r / min, when the pressure drop rate reaches 0.2 MPa / min, record the time at this time, which is the oxidation induction period, and the results are shown in Table 4.

[0081] 3. High temperature stability test: Respectively, 100 mL of test sample 3, test sample 4 and control sample 5 were placed in a clean beaker, the beaker was covered with a breathable plastic wrap, and the beaker was placed in a 150 ℃ oven for aging for 100 h, thereby obtaining an aged sample; Respectively, 100 mL of test sample 3, test sample 4, control sample 5 and aged sample were immediately loaded into a viscometer, the viscometer was fixed in a 40 ℃ constant temperature water bath, and the constant temperature was maintained for 15 min. Adjust the viscometer vertically, record the flow time of the sample after being released, and 3 parallel samples for each sample; The kinematic viscosity was calculated by the product of the viscosity constant and the flow time. According to the ratio of the difference between the kinematic viscosity after aging and the kinematic viscosity before aging to the kinematic viscosity before aging, the viscosity change rate was calculated, and the results are shown in Table 4.

[0082] Table 4 Effect verification results of anti-wear-antioxidant composite additive synergistic system

[0083] As can be seen from Table 4, Example 3 has a short jam, obvious noise and slight smoking; Example 4 has no abnormality; and Comparative Example 5 has a short jam and slight noise. It shows that the anti-wear agent and the antioxidant in Example 4 synergize to make the anti-wear performance of the lubricating oil better, and the composite additive of the present application can improve the anti-wear process stability. The steel ball wear scar diameter of Example 4 is 0.3±0.1, which is smaller than that of Example 3 and Comparative Example 5, indicating that the anti-wear effect is good, the anti-wear agent and the antioxidant of the present application synergize, can effectively reduce the wear of the steel ball, and the anti-wear performance is more outstanding. The oxidation induction period of Example 4 is 380.7±4.5 min, which is much longer than that of Example 3 and Comparative Example 5, indicating that the lubricating oil has strong oxidation resistance, the anti-wear agent and the antioxidant of the present application synergize, significantly improve the oxidation stability of the lubricating oil, and delay the oxidation deterioration. The viscosity change rate of Example 4 is 4.7±0.6%, which is lower than that of Example 3 and Comparative Example 5, indicating that the viscosity of the lubricating oil after high temperature aging is stable, the composite additive of the present application synergizes, enhances the high temperature stability of the lubricating oil, reduces the abnormal change of viscosity caused by high temperature, and is beneficial to maintaining good lubricating performance under high temperature working conditions.

[0084] In summary, the anti-wear agent and the antioxidant are used to treat the lubricating oil, and the lubricating oil has the advantages of anti-wear, anti-oxidation and high-temperature stability.

[0085] The above description is only used to illustrate the technical solutions of the present application but not limit the present application, and any equivalent modification and change of the technical solutions of the present application made by those skilled in the art should still belong to the scope of the present application as long as the modification and change do not deviate from the overall concept of the present application.

Claims

1. A method for recycling lubricating oil based on the combination of membrane separation and ultrafiltration, characterized in that: The lubricating oil recycling method based on the combination of membrane separation and ultrafiltration specifically comprises the following steps: S001, preheating the waste lubricating oil, adding adsorbent, adsorption and filtering to obtain preliminary purified oil; S002, passing the preliminarily purified oil through a microfiltration membrane and an ultrafiltration membrane for separation treatment to obtain a refined base oil precursor; S003, adding a hydrogenation modifier to the refined base oil precursor for hydrogenation treatment to obtain a hydrogenated base oil; S004, preheating the hydrogenated base oil, slowly adding an anti-wear agent, performing high-speed shearing treatment, slowly adding an antioxidant, stirring, and performing reduced pressure distillation treatment. After cooling to room temperature, filtering is performed to obtain lubricating oil.

2. The lubricating oil recycling method based on membrane separation and ultrafiltration according to claim 1, characterized in that: In step S001, the adsorbent is added at 2% by mass of the oil. The adsorption treatment is first carried out by stirring at 300 rpm for 30 minutes and then standing for 2 hours. The filtration treatment is carried out by plate and frame filtration. In step S003, the amount of the added hydrogenation modifier is 1.5% by mass of the refined base oil precursor. In step S004, the amount of the added anti-wear agent is 2% of the hydrogenated base oil.

3. The lubricating oil recycling method based on membrane separation and ultrafiltration according to claim 1, characterized in that: The adsorbent is composed of basalt fiber with a silanized surface, a silica network derived from ethyl orthosilicate, a modified copolymer of acrylamide-maleic anhydride-N-isopropylacrylamide, sodium allyl sulfonate, and trimethylsiloxy derived from hexamethyldisilazane, with the mass ratios being 5:85:9:0.3:0.1 respectively.

4. The lubricating oil recycling method based on the combination of membrane separation and ultrafiltration according to claim 1, characterized in that: The microfiltration membrane is a ceramic microfiltration membrane containing basalt fiber, cerium oxide, and surface-grafted sodium dodecylbenzenesulfonate hydrophobic chain segments; the ultrafiltration membrane is a metal organic framework-ionic liquid ultrafiltration membrane; and the hydrogenation modifier is a cerium-doped nickel molybdenum phosphorus / zirconium-based metal organic framework.

5. The lubricating oil recycling method based on membrane separation and ultrafiltration according to claim 1, characterized in that: The anti-wear agent is composed of zinc dialkyl dithiophosphate, titanium dioxide-coated antimony-doped tin oxide, and polyisobutylene succinimide. The mass ratio of zinc dialkyl dithiophosphate to titanium dioxide-coated antimony-doped tin oxide is 5:1, and the added amount of polyisobutylene succinimide is 0.5% of the hydrogenated base oil.

6. The lubricating oil recycling method based on membrane separation and ultrafiltration according to claim 1, characterized in that: The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and diphenylamine, and the added amounts thereof are 0.2% and 0.1% of the hydrogenated base oil respectively.

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