Preparation method for refining base oil from waste lubricating oil

Abstract

The invention discloses a preparation method for refining base oil from waste lubricating oil, which comprises the following steps: 1) placing the waste lubricating oil in an oil-water separator to settle for 12-48 hours, and collecting separated oil; (2) carrying out reduced pressure distillation on the separated oil obtained in the step (1) in a wiped-film evaporator to obtain distillate oil; (3) mixing the distillate oil obtained in the step (2) with a mesoporous adsorption carrier under ultrasonic waves, the addition amount of the mesoporous adsorption carrier being 3-10% of the mass of the distillate oil; 4) settling, filtering and collecting an oil phase; 5) thin film evaporation; and 6) carrying out short-path distillation. The method has the advantages that not only can degraded components in the waste lubricating oil be effectively removed, but also the yield of the base oil can be effectively increased.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating oil, and in particular to a method for preparing base oil by refining waste lubricating oil. Background Art

[0002] Lubricating oil is mainly composed of 80% to 90% base oil and 10% to 20% additives. After 150SN of use, the performance of lubricating oil will deteriorate due to physical, chemical or human factors, and impurities will be generated. It can no longer be used and becomes waste lubricating oil. Waste lubricating oil belongs to the HW08 waste mineral oil and mineral oil-containing waste category in my country's "National List of Hazardous Wastes". It contains a variety of toxic and harmful substances, such as heavy metals, benzene series, polycyclic aromatic hydrocarbons, etc. Direct disposal will cause water and soil pollution. On the other hand, waste lubricating oil has a high recycling value and can be regenerated into base oil and other products through appropriate recycling technology. The recycling of waste lubricating oil can directly save petroleum resources.

[0003] At present, the traditional acid-distillation-bleaching clay process is used to regenerate waste lubricating oil. Although the process is simple and the equipment requirements are low, it requires a large amount of bleaching clay, has a low regeneration rate, and also produces serious "three wastes" problems, causing serious secondary pollution. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing base oil from waste lubricating oil, which can not only effectively remove the degraded components in the waste lubricating oil, but also effectively improve the yield of the base oil.

[0005] The present invention is achieved through the following technical solutions: On the one hand, a method for preparing base oil by refining waste lubricating oil is provided, comprising the following steps:

[0006] 1) Place the waste lubricating oil in an oil-water separator and let it settle for 12-48 hours, then collect the separated oil;

[0007] 2) subjecting the separated oil obtained in step 1) to vacuum distillation in a wiped film evaporator to obtain a distillate oil;

[0008] 3) mixing the distillate oil obtained in step 2) with a mesoporous adsorption carrier under ultrasound, wherein the amount of the mesoporous adsorption carrier added accounts for 3-10% of the mass of the distillate oil;

[0009] 4) Settling, filtering and collecting the oil phase;

[0010] 5) Thin film evaporation;

[0011] 6) Short-path distillation to obtain.

[0012] Through the above technical scheme, the waste lubricating oil is subjected to fine pretreatment, vacuum distillation, ultrasonic mixed adsorption, thin film evaporation and short-range distillation, etc., combined with optimized ultrasonic conditions, mesoporous adsorption carrier and its preparation process, to achieve efficient regeneration of waste lubricating oil and improve the base oil yield and quality.

[0013] Furthermore, in step 3), the mesoporous adsorption carrier is made of diatomaceous earth and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as templates, through a template method and a sol-gel method; wherein the mass ratio of the diatomaceous earth to chitosan oligosaccharide is 1:3-6.

[0014] Through the above technical solution, the introduction of mesoporous adsorption carriers in the waste lubricating oil refining process simplifies the subsequent processing steps, such as reducing the number and difficulty of filtration and distillation, and improving the efficiency and stability of the overall process. In addition, diatomaceous earth itself has a porous structure and can provide a good adsorption basis. The addition of chitosan oligosaccharides further enriches the pore structure of the carrier, especially the mesoporous structure formed by the sol-gel process. These mesopores have a large specific surface area and a suitable pore size distribution, which is conducive to the effective adsorption of impurities, colloids and other unfavorable components in the waste lubricating oil, thereby improving the purity and quality of the base oil.

[0015] As a natural polysaccharide, chitosan oligosaccharide has good biocompatibility and stability. When combined with diatomaceous earth, it can enhance the overall structural stability of the mesoporous adsorption carrier, so that it can still maintain good adsorption performance under harsh conditions such as high temperature, acid and alkali, and extend its service life.

[0016] The diatomite and chitosan oligosaccharide are mixed in the above mass ratio, which can effectively control the pore size distribution of the mesoporous adsorption carrier. Therefore, the porous structure of the diatomite and the chelating ability of the chitosan oligosaccharide work together to achieve efficient adsorption of impurities.

[0017] Furthermore, the preparation process of the mesoporous adsorption carrier includes the following steps:

[0018] Step 1: Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide as raw materials, remove impurities and adjust the particle size to 200 mesh after pretreatment;

[0019] Step 2: Mesoporous structure construction;

[0020] a. Preparation of template solution: Dissolve CTAB and TPABr in an appropriate amount of aqueous solution according to CTAB:TPABr=1:0.3-0.5, stir evenly until completely dissolved, and obtain a template solution;

[0021] b. Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed according to the above ratio, a template solution is added, the pH value is adjusted, and the mixture is stirred to form a sol, which is then gelled to obtain a wet gel;

[0022] c. Aging and drying: The wet gel was aged at room temperature for 24 hours and dried to obtain a dry gel;

[0023] d. Template removal and activation: The dry gel is placed at 500-600°C for heat treatment to remove the template agents CTAB and TPABr, and after forming a mesoporous structure, it is activated and an inert gas is introduced to obtain an activated material;

[0024] Step 3: Grind and sieve the activated material to obtain a granular mesoporous adsorption carrier.

[0025] Through the above technical scheme and the above preparation method, the obtained granular mesoporous adsorption carrier has excellent mesoporous structure and adsorption capacity, and can also increase the specific surface area of ​​the granular mesoporous adsorption carrier, thereby increasing the contact area between the carrier and the lubricating oil, and improving the adsorption efficiency and capacity.

[0026] In addition, in step b, the preparation process of diatomite powder and chitosan oligosaccharide solution is as follows: the process of obtaining diatomite powder is as follows: taking high-quality diatomite raw material, crushing it to 200 meshes to increase its specific surface area and adsorption capacity. Subsequently, high-temperature flash modification is carried out in a flash kiln, the flash time is 5-20 seconds, and the flash temperature is 400-800°C to remove part of the organic matter and activate the surface of the diatomite to increase its adsorption active sites.

[0027] The process of obtaining the chitosan oligosaccharide solution is as follows: dissolving the chitosan oligosaccharide in an appropriate amount of deionized water to form a chitosan oligosaccharide solution of a certain concentration. In order to enhance the chelating ability of the chitosan oligosaccharide, an appropriate amount of acetic acid can be added as a solvent to adjust the pH value of the solution to an appropriate range.

[0028] Furthermore, the specific surface area of ​​the mesoporous adsorption carrier is 172-210m 2 / g, the pore volume is 0.2-0.7ml / g, and the average pore diameter is 5-10nm.

[0029] Furthermore, the filtration is ceramic membrane filtration, and the ceramic membrane filtration adopts a multi-channel ceramic membrane, and the number of channels is controlled at 10-12.

[0030] Furthermore, the ceramic membrane is made of glass membrane with a pore size of 0.20 μm; the flow rate is controlled at 5-10 m / s, the pressure is controlled at 0.1-0.2 MPa, and the filtrate temperature is controlled at 40-50°C.

[0031] Furthermore, in step 5), the steam pressure of the thin film evaporation is 30-35 psig, and the temperature is ≥190°C.

[0032] Further, in step 6), the short-path distillation is a three-stage molecular short-path distillation; the distances between the hot and cold plates of the three-stage molecular short-path distillation are 15-20 mm, 25-30 mm and 35-40 mm respectively; the hot plate temperature is 190-300°C, the cold plate temperature is 30-100°C, and the vacuum degree is 30-50Pa.

[0033] Furthermore, the feed flow rate of the short-path distillation is 90-100 mL / h, the system pressure is 60-70 Pa, and the temperature of the molecular short-path distillation is controlled above 200°C.

[0034] Preferably, the waste lubricating oil is industrial waste lubricating oil or vehicle waste lubricating oil.

[0035] Beneficial Effects

[0036] The present invention effectively removes impurities in the fraction oil through vacuum distillation and ultrasonic treatment, thereby improving the purity of the oil; ceramic membrane filtration and thin film evaporation further remove impurities and moisture in the oil, and molecular distillation further purifies it through short-range distillation; that is, through vacuum distillation, ultrasonic treatment, ceramic membrane filtration, thin film evaporation and molecular distillation and other multi-step treatments, efficient purification of waste lubricating oil is achieved. In particular, the high specific surface area and pore volume of the mesoporous adsorption carrier can effectively adsorb tiny impurities in the oil, effectively improving the quality of the oil.

[0037] The invention has a high yield, indicating that the treatment process is effective and has little loss; the obtained base oil meets the quality requirements of a type of lubricating oil in "QSY44-2009 Universal Lubricating Oil Base Oil" and has excellent physical and chemical properties. Using waste lubricating oil as a raw material reduces resource waste and environmental pollution, and at the same time, the energy consumption in the treatment process is low. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The experimental methods without specific conditions in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise specified, all percentages, ratios, proportions or parts are by weight.

[0040] Unless otherwise specified, the reagents and raw materials used in the examples and comparative examples of the present invention can be obtained through commercial channels.

[0041] The ceramic membrane (multi-channel ceramic membrane) was purchased from Sanda Membrane Technology (Xiamen) Co., Ltd. The number of channels was controlled at 10-12. The membrane material was glass membrane with a pore size of 0.2 μm.

[0042] Example 1

[0043] Weigh 100kg of industrial waste lubricating oil, place the waste lubricating oil in an oil-water separator, let it settle for 24 hours, and collect the separated oil; send the separated oil to a scraped film evaporator for vacuum distillation, and control the steam pressure at 30psig to obtain distillate oil. Under ultrasonic conditions, the ultrasonic power is 200W, the ultrasonic frequency is 20kHz, and the ultrasonic time is 25min, and the distillate oil is mixed with the mesoporous adsorption carrier; after ultrasonic mixing, let it settle for 48 hours, and filter it with a ceramic membrane with a pore size of 0.20μm, a channel number of 10-12, a flow rate of 8m / s, a pressure of 0.2MPa, and a filtrate temperature of 50℃, and collect the oil phase. The filtered oil phase is sent to a thin film evaporator, the steam pressure is controlled at 35psig, the temperature is 190°C, to remove residual moisture and light components; the resulting waste lubricating oil is then passed into a molecular distiller for three-stage molecular short-range distillation, the distances between the hot and cold plates are 20mm, 30mm and 40mm respectively; the hot plate temperature is 300°C, the cold plate temperature is 100°C, and the vacuum degree is 50Pa; the feed flow rate is 90mL / h, the system pressure is 60Pa, and the temperature of the molecular short-range distillation is controlled at above 200°C to obtain a base oil; and the light lubricating oil base oil and heavy lubricating oil base oil contained in the base oil meet the quality requirements of a class of lubricating oil in "QSY44-2009 General Lubricating Oil Base Oil", specifically meeting the requirements in the main properties specification table of lubricating oil base oil in the following table:

[0044] category Category I Category II Three categories Saturated hydrocarbon content, v% <90 ≥90 ≥90 Viscosity Index 80-120 80-120 ≥120 Sulfur content, w% ＞0.3 ＜0.3 ＜0.3

[0045] On the basis of the above scheme, the addition amount of the mesoporous adsorption carrier accounts for 10% of the mass of the distillate oil; the mesoporous adsorption carrier is prepared by the template method and the sol-gel method using diatomite and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as template agents, and the mass ratio of diatomite to chitosan oligosaccharide is 1:6.

[0046] The preparation process of the above-mentioned mesoporous adsorption carrier is as follows:

[0047] Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide, remove impurities and adjust the particle size to 200 mesh.

[0048] Preparation of template solution: dissolve CTAB and TPABr in an appropriate amount of aqueous solution at a ratio of CTAB:TPABr=1:0.3 and stir evenly.

[0049] Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed, template solution is added, pH value is adjusted, and stirred evenly to form a sol, which is then gelled to obtain a wet gel.

[0050] Aging and drying: The wet gel was aged at room temperature for 24 h and then dried to obtain a dry gel.

[0051] Template removal and activation: The dry gel is placed at 600°C for heat treatment to remove the template and form a mesoporous structure. After activation, an inert gas is introduced to obtain an activated material.

[0052] Grinding and sieving: Grinding and sieving the activated material to obtain a granular mesoporous adsorption carrier;

[0053] Finally, the obtained granular mesoporous adsorption carrier has a specific surface area of ​​210m2 / g, a pore volume of 0.4ml / g, and an average pore diameter of 6nm.

[0054] Example 2

[0055] Weigh 100kg of industrial waste lubricating oil, place the waste lubricating oil in an oil-water separator, let it settle for 12 hours, and collect the separated oil; send the separated oil to a scraped film evaporator for vacuum distillation, and control the steam pressure at 30psig to obtain distillate oil. Under ultrasonic conditions, the ultrasonic power is 150W, the ultrasonic frequency is 20kHz, and the ultrasonic time is 30min, and the distillate oil is mixed with the mesoporous adsorption carrier; after ultrasonic mixing, let it settle for 48 hours, and filter it with a ceramic membrane with a pore size of 0.30μm, a channel number of 10-12, a flow rate of 6m / s, a pressure of 0.2MPa, and a filtrate temperature of 50℃, and collect the oil phase. The filtered oil phase is sent to a thin film evaporator, the steam pressure is controlled at 35psig, the temperature is ≥190℃, and the residual moisture and light components are further removed; the waste lubricating oil obtained is then passed into a molecular distiller for three-stage molecular short-range distillation, the distance between the hot and cold plates is 15mm, 25mm and 35mm respectively; the hot plate temperature is 260℃, the cold plate temperature is 100℃, and the vacuum degree is 45Pa; the feed flow rate is 95mL / h, the system pressure is 70Pa, and the temperature of the molecular short-range distillation is controlled at above 200℃ to obtain the base oil. And the light lubricating oil base oil and heavy lubricating oil base oil contained in the base oil meet the quality requirements of a class of lubricating oil in "QSY44-2009 General Lubricating Oil Base Oil", and specifically meet the requirements in the main properties specification table of lubricating oil base oil in the following table:

[0056]

[0057]

[0058] On the basis of the above scheme, the addition amount of the mesoporous adsorption carrier accounts for 9% of the mass of the distillate oil; the mesoporous adsorption carrier is prepared by the template method and the sol-gel method using diatomite and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as template agents, and the mass ratio of diatomite to chitosan oligosaccharide is 1:5.

[0059] The preparation process of the above-mentioned mesoporous adsorption carrier is as follows:

[0060] Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide, remove impurities and adjust the particle size to 200 mesh.

[0061] Preparation of template solution: dissolve CTAB and TPABr in an appropriate amount of aqueous solution at a ratio of CTAB:TPABr=1:0.5 and stir evenly.

[0062] Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed, template solution is added, pH value is adjusted, and stirred evenly to form a sol, which is then gelled to obtain a wet gel.

[0063] Aging and drying: The wet gel was aged at room temperature for 24 h and then dried to obtain a dry gel.

[0064] Template removal and activation: The dry gel is placed at 500°C for heat treatment to remove the template and form a mesoporous structure. After activation, an inert gas is introduced to obtain an activated material.

[0065] Grinding and screening: Grind and screen the activated material to obtain a granular mesoporous adsorption carrier with a specific surface area of ​​185m2 / g, a pore volume of 0.2ml / g, and an average pore diameter of 10nm.

[0066] Example 3

[0067] Weigh 100kg of industrial waste lubricating oil, place the waste lubricating oil in an oil-water separator, settle for 20 hours, and collect the separated oil; send the separated oil to a scraped film evaporator for vacuum distillation, and control the steam pressure at 30psig to obtain distillate oil. Under ultrasonic conditions, the ultrasonic power is 180W, the ultrasonic frequency is 20kHz, and the ultrasonic time is 30min, and the distillate oil is mixed with the mesoporous adsorption carrier; after ultrasonic mixing, let it stand for 48 hours, and filter it with a ceramic membrane with a pore size of 0.20μm, a channel number of 10-12, a flow rate of 10m / s, a pressure of 0.2MPa, and a filtrate temperature of 50℃, and collect the oil phase. The filtered oil phase is sent to a thin film evaporator, the steam pressure is controlled at 35psig, the temperature is ≥190℃, and the residual moisture and light components are further removed; the waste lubricating oil obtained is then passed into a molecular distiller for three-stage molecular short-range distillation, the distance between the hot and cold plates is 18mm, 28mm and 38mm respectively; the hot plate temperature is 300℃, the cold plate temperature is 100℃, and the vacuum degree is 50Pa; the feed flow rate is 100mL / h, the system pressure is 70Pa, and the temperature of the molecular short-range distillation is controlled at above 200℃ to obtain the base oil. In addition, the light lubricating oil base oil and heavy lubricating oil base oil contained in the base oil meet the quality requirements of a class of lubricating oil in "QSY44-2009 General Lubricating Oil Base Oil", and specifically meet the requirements in the main properties specification table of lubricating oil base oil in the following table:

[0068] category Category I Category II Three categories Saturated hydrocarbon content, v% <90 ≥90 ≥90 Viscosity Index 80-120 80-120 ≥120 Sulfur content, w% ＞0.3 ＜0.3 ＜0.3

[0069] On the basis of the above scheme, the addition amount of the mesoporous adsorption carrier accounts for 8% of the mass of the distillate oil; the mesoporous adsorption carrier is prepared by the template method and the sol-gel method using diatomite and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as template agents, wherein the mass ratio of diatomite to chitosan oligosaccharide is 1:4.

[0070] The preparation process of the above-mentioned mesoporous adsorption carrier is as follows:

[0071] Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide, remove impurities and adjust the particle size to 200 mesh.

[0072] Preparation of template solution: dissolve CTAB and TPABr in an appropriate amount of aqueous solution at a ratio of CTAB:TPABr=1:0.5 and stir evenly.

[0073] Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed, template solution is added, pH value is adjusted, and stirred evenly to form a sol, which is then gelled to obtain a wet gel.

[0074] Aging and drying: The wet gel was aged at room temperature for 24 h and then dried to obtain a dry gel.

[0075] Template removal and activation: The dry gel is placed at 580°C for heat treatment to remove the template and form a mesoporous structure. After activation, an inert gas is introduced to obtain an activated material.

[0076] Grinding and screening: Grind and screen the activated material to obtain a granular mesoporous adsorption carrier with a specific surface area of ​​200m2 / g, a pore volume of 0.7ml / g and an average pore diameter of 7nm.

[0077] Example 4

[0078] Weigh 100kg of industrial waste lubricating oil, place the waste lubricating oil in an oil-water separator, settle for 18 hours, and collect the separated oil; send the separated oil to a scraped film evaporator for vacuum distillation, and control the steam pressure at 30psig to obtain distillate oil. Under ultrasonic conditions, the ultrasonic power is 300W, the ultrasonic frequency is 20kHz, and the ultrasonic time is 28min, and the distillate oil is mixed with the mesoporous adsorption carrier; after ultrasonic mixing is uniform, it is allowed to settle for 48 hours, and filtered using a ceramic membrane with a pore size of 0.20μm, a channel number of 10-12, a flow rate of 5-10m / s, a pressure of 0.2MPa, and a filtrate temperature of 45°C, and the oil phase is collected. The filtered oil phase is sent to a thin film evaporator, the steam pressure is controlled at 35psig, the temperature is ≥190℃, and the residual moisture and light components are further removed; the waste lubricating oil obtained is then passed into a molecular distiller for three-stage molecular short-range distillation, the distance between the hot and cold plates is 20mm, 30mm and 40mm respectively; the hot plate temperature is 280℃, the cold plate temperature is 100℃, and the vacuum degree is 50Pa; the feed flow rate is 100mL / h, the system pressure is 70Pa, and the temperature of the molecular short-range distillation is controlled at above 200℃ to obtain the base oil. And the light lubricating oil base oil and heavy lubricating oil base oil contained in the base oil meet the quality requirements of a class of lubricating oil in "QSY44-2009 General Lubricating Oil Base Oil", and specifically meet the requirements in the main properties specification table of lubricating oil base oil in the following table:

[0079] category Category I Category II Three categories Saturated hydrocarbon content, v% <90 ≥90 ≥90 Viscosity Index 80-120 80-120 ≥120 Sulfur content, w% ＞0.3 ＜0.3 ＜0.3

[0080] On the basis of the above scheme, the addition amount of the mesoporous adsorption carrier accounts for 10% of the mass of the distillate oil; the mesoporous adsorption carrier is prepared by the template method and the sol-gel method using diatomite and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as template agents, and the mass ratio of diatomite to chitosan oligosaccharide is 1:5.

[0081] The preparation process of the above-mentioned mesoporous adsorption carrier is as follows:

[0082] Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide, remove impurities and adjust the particle size to 200 mesh.

[0083] Preparation of template solution: dissolve CTAB and TPABr in an appropriate amount of aqueous solution at a ratio of CTAB:TPABr=1:0.3 and stir evenly.

[0084] Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed, template solution is added, pH value is adjusted, and stirred evenly to form a sol, which is then gelled to obtain a wet gel.

[0085] Aging and drying: The wet gel was aged at room temperature for 24 h and then dried to obtain a dry gel.

[0086] Template removal and activation: The dry gel is placed at 600°C for heat treatment to remove the template and form a mesoporous structure. After activation, an inert gas is introduced to obtain an activated material.

[0087] Grinding and screening: Grind and screen the activated material to obtain a granular mesoporous adsorption carrier with a specific surface area of ​​200m2 / g, a pore volume of 0.7ml / g, and an average pore diameter of 5nm.

[0088] Comparative Example 1

[0089] Different from Example 1, no mesoporous adsorption carrier is added to mix with the distillate oil, and the obtained base oil does not meet the quality requirements of Class I lubricating oil in "QSY44-2009 Universal Lubricating Oil Base Oil".

[0090] Comparative Example 2

[0091] Different from Example 2, the base oil obtained was not treated under ultrasonic conditions, and the quality requirements of a class of lubricating oils in "QSY44-2009 Universal Lubricating Oil Base Oil" were met, specifically meeting the requirements in the main properties specification table of lubricating oil base oils in the following table:

[0092] category Category I Category II Three categories Saturated hydrocarbon content, v% <90 ≥90 ≥90 Viscosity Index 80-120 80-120 ≥120 Sulfur content, w% ＞0.3 ＜0.3 ＜0.3

[0093] Comparative Example 3

[0094] Different from Example 3, the thin film evaporation treatment was not performed, and the obtained base oil met the quality requirements of a class of lubricating oil in "QSY44-2009 Universal Lubricating Oil Base Oil", specifically meeting the requirements in the main properties specification table of lubricating oil base oil in the following table:

[0095] category Category I Category II Three categories Saturated hydrocarbon content, v% <90 ≥90 ≥90 Viscosity Index 80-120 80-120 ≥120 Sulfur content, w% ＞0.3 ＜0.3 ＜0.3

[0096] Comparative Example 4

[0097] Different from Example 4, the tertiary molecular short-range distillation treatment was not performed, and the obtained base oil met the quality requirements of Class I lubricating oil in "QSY44-2009 Universal Lubricating Oil Base Oil", and specifically met the requirements in the main property specification table of lubricating oil base oil in the following table:

[0098]

[0099]

[0100] Effect Example

[0101] The above-mentioned Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to performance tests, and the performance characteristics of the base oil are shown in the following table:

[0102]

[0103]

[0104] In summary, through vacuum distillation and ultrasonic treatment, impurities in the distillate oil are effectively removed, and the purity of the oil is improved; ceramic membrane filtration and thin film evaporation further remove impurities and moisture in the oil, and molecular distillation is further purified by short-range distillation; that is, through multi-step treatments such as vacuum distillation, ultrasonic treatment, ceramic membrane filtration, thin film evaporation and molecular distillation, efficient purification of waste lubricating oil is achieved. In particular, the high specific surface area and pore volume of the mesoporous adsorption carrier can effectively adsorb tiny impurities in the oil and effectively improve the quality of the oil. According to the analysis of the above table, the yields in Examples 1-4 are generally high, indicating that the treatment process is effective and the loss is small; the obtained base oil meets the quality requirements of a class of lubricating oils in "QSY44-2009 General Lubricating Oil Base Oil" and has excellent physical and chemical properties. Using waste lubricating oil as a raw material reduces resource waste and environmental pollution, and at the same time, the energy consumption during the treatment process is low.

[0105] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing base oil by refining waste lubricating oil, characterized in that: The following steps are involved: 1) Place the waste lubricating oil in an oil-water separator and let it settle for 12-48 hours, then collect the separated oil; 2) subjecting the separated oil obtained in step 1) to vacuum distillation in a wiped film evaporator to obtain a distillate oil; 3) mixing the distillate oil obtained in step 2) with a mesoporous adsorption carrier under ultrasound, wherein the amount of the mesoporous adsorption carrier added accounts for 3-10% of the mass of the distillate oil; 4) sedimentation, filtration, and collection of the oil phase; 5) Thin film evaporation; 6) Short-path distillation to obtain.

2. The preparation method according to claim 1, characterized in that: In step 3), the mesoporous adsorption carrier is made of diatomite and chitosan oligosaccharide as raw materials, CTAB and tetrapropylammonium bromide (TPABr) as templates, through template method and sol-gel method; wherein the mass ratio of diatomite to chitosan oligosaccharide is 1:3-6.

3. The preparation method according to claim 2, characterized in that: The preparation process of the mesoporous adsorption carrier comprises the following steps: Step 1: Raw material pretreatment: Select high-purity diatomaceous earth and chitosan oligosaccharide as raw materials, remove impurities and adjust the particle size to 200 mesh after pretreatment; Step 2: Mesoporous structure construction; a. Preparation of template solution: Dissolve CTAB and TPABr in an appropriate amount of aqueous solution according to CTAB:TPABr=1:0.3-0.5, stir evenly until completely dissolved, and obtain a template solution; b. Sol-gel process: diatomaceous earth powder and chitosan oligosaccharide solution are mixed according to the above ratio, a template solution is added, the pH value is adjusted, and the mixture is stirred to form a sol, which is then gelled to obtain a wet gel; c. Aging and drying: The wet gel was aged at room temperature for 24 hours and dried to obtain a dry gel; d. Template removal and activation: The dry gel is placed at 500-600°C for heat treatment to remove the template agents CTAB and TPABr, and after forming a mesoporous structure, it is activated and an inert gas is introduced to obtain an activated material; Step 3: Grind and sieve the activated material to obtain a granular mesoporous adsorption carrier.

4. The preparation method according to any one of claims 1 to 3, characterized in that The specific surface area of ​​the mesoporous adsorption carrier is 172-210m 2 / g, the pore volume is 0.2-0.7ml / g, and the average pore diameter is 5-10nm.

5. The preparation method according to claim 1, characterized in that: In step 4), the filtration is ceramic membrane filtration, and the ceramic membrane filtration uses a multi-channel ceramic membrane, and the number of channels is controlled at 10-12.

6. The preparation method according to claim 5, characterized in that: The ceramic membrane is made of glass membrane with a pore size of 0.20 μm; the flow rate is controlled at 5-10 m / s, the pressure is controlled at 0.1-0.2 MPa, and the filtrate temperature is controlled at 40-50°C.

7. The preparation method according to claim 1, characterized in that: In step 5), the steam pressure of the thin film evaporation is 30-35 psig and the temperature is ≥190°C.

8. The preparation method according to claim 1, characterized in that: In step 6), the short-path distillation is a three-stage molecular short-path distillation; the distances between the hot and cold plates of the three-stage molecular short-path distillation are 15-20 mm, 25-30 mm and 35-40 mm respectively; the hot plate temperature is 190-300°C, the cold plate temperature is 30-100°C, and the vacuum degree is 30-50Pa.

9. The preparation method according to claim 8, characterized in that: The feed flow rate of the short-path distillation is 90-100 mL / h, the system pressure is 60-70 Pa, and the temperature of the short-path distillation is controlled at above 200°C.

10. The preparation method according to any one of claims 1-3 and 5-9, characterized in that: The waste lubricating oil is industrial waste lubricating oil or vehicle waste lubricating oil.

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