CN112403271B - Method for preparing diesel oil antiwear agent by removing saturated fatty acid through membrane separation - Google Patents
Method for preparing diesel oil antiwear agent by removing saturated fatty acid through membrane separation Download PDFInfo
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- CN112403271B CN112403271B CN202011173185.8A CN202011173185A CN112403271B CN 112403271 B CN112403271 B CN 112403271B CN 202011173185 A CN202011173185 A CN 202011173185A CN 112403271 B CN112403271 B CN 112403271B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/147—Microfiltration
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/10—Liquid carbonaceous fuels containing additives
- C10L1/14—Organic compounds
- C10L1/18—Organic compounds containing oxygen
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L10/00—Use of additives to fuels or fires for particular purposes
- C10L10/08—Use of additives to fuels or fires for particular purposes for improving lubricity; for reducing wear
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- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
- C11C1/00—Preparation of fatty acids from fats, fatty oils, or waxes; Refining the fatty acids
- C11C1/08—Refining
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Abstract
The invention discloses a method for preparing a diesel antiwear agent by removing saturated fatty acid through membrane separation, which comprises the following steps: cooling and crystallizing raw industrial unsaturated fatty acid, and then continuously separating the cooled and crystallized industrial unsaturated fatty acid by adopting a microfiltration membrane tubular device with the aperture of 0.1-1.0 micron under the condition that the pressure difference between two sides of the microfiltration membrane is 0.1-0.6 MPa to obtain the diesel antiwear agent product with lower saturated fatty acid content than the conventional diesel antiwear agent product filtered by adopting filter cloth under the same cooling and crystallization conditions. The diesel antiwear agent prepared by the method has lower saturated fatty acid content, the cloud point of the diesel antiwear agent is low to be close to the condensation point, and the low-sulfur diesel antiwear agent has better low-temperature performance.
Description
Technical Field
The invention belongs to the field of refining of diesel additives, and particularly relates to a method for preparing a diesel antiwear agent by removing saturated fatty acid through membrane separation.
Background
The fatty acid type diesel antiwear agent is produced by using unsaturated fatty acid comprising industrial linoleic acid, linolenic acid, oleic acid, tall oil acid and their mixture as main material, cooling to crystallize, filtering to separate most saturated fatty acid to obtain filtrate, and blending the filtrate to obtain the diesel antiwear agent product. The industrial unsaturated fatty acid product contains a certain amount of saturated fatty acid, the content of the saturated fatty acid in the diesel antiwear agent prepared by separating the obtained filtrate and then blending is a main technical index influencing the use performance of the diesel antiwear agent, and the saturated fatty acid has higher crystallization temperature and is easy to precipitate solid crystals at low temperature, so the saturated fatty acid is removed as much as possible in the production process of the diesel antiwear agent. The higher the content of saturated fatty acid, the higher the cloud point and the condensation point of the diesel anti-wear agent product, and the easier the turbidity and the solidification are. When the low value of the natural environment temperature of many regions is below-10 ℃, the diesel antiwear agent produced by the traditional method is used for producing diesel, saturated fatty acid is easy to precipitate in the low-temperature environment to cause turbidity or solidification, although the pour point of the pour point depressant can be reduced by adding the pour point depressant, and the low-temperature flowing property is improved, the pour point depressant has little influence on the low-temperature precipitation of the saturated fatty acid. The precipitated saturated fatty acid crystals can increase the viscosity of the diesel oil, increase the risk of blocking an oil pump filter screen of the engine, even cause the diesel oil to lose fluidity at low temperature, and cause the engine to work abnormally. Therefore, in the production of the diesel antiwear agent, saturated fatty acid which is easy to separate out and crystallize at low temperature is removed as far as possible, so that the diesel antiwear agent has a lower condensation point and a lower cloud point.
In order to remove saturated fatty acid, the traditional method is to carry out low-temperature cooling crystallization on industrial-grade unsaturated fatty acid, then use fiber fabrics such as filter cloth and the like as filter media, permeate liquid unsaturated fatty acid through the filter cloth by depending on a certain pressure difference, and intercept saturated fatty acid precipitated by crystallization to achieve the purpose of separation. The filtration and separation modes of the filter are natural filtration, negative pressure vacuum filtration, mechanical pressure filtration, centrifugal filtration and the like which rely on gravity, and traditional fiber fabrics such as filter cloth and the like are adopted as filter media. The filter pores of the fiber fabric filter media such as filter cloth are generally large and have different pore sizes, so that the filter media are easy to deform or even break under the existence of pressure difference to generate filter leakage, and particularly, the traditional separation mode needs a process of bridging particles to form a filter layer just before filtration, and during the process, the crystal particles with smaller sizes penetrate through the filter media to enter the filtrate and cause turbidity of the initial filtrate. The separation process requires a period of time to form a stable filtration layer to nearly completely trap solid crystals and gradually make the filtrate nearly transparent, and if the stable structure of the filtration layer is broken due to pressure change or other reasons during the filtration separation process, a process of re-establishing the stable filtration layer is required. For the reasons, the traditional separation method causes the content of saturated fatty acid in the filtrate obtained in the process of separating and removing saturated fatty acid and the diesel anti-wear agent produced by the filtrate, so that the cloud point of the filtrate or the diesel anti-wear agent produced by the filtrate is higher than the condensation point by more than 5 ℃, wherein a large amount of easily separated saturated fatty acid is a main risk factor for blocking an oil pump filter screen. Because of the property limit of industrial grade unsaturated fatty acid, the diesel antiwear agent product with unsaturated fatty acid as the main chemical component is produced by a conventional separation method using traditional filter cloth and other fiber fabrics as filter media, and the cloud point and the condensation point of the diesel antiwear agent product are close to the limit of the method.
The preparation methods of the diesel oil antiwear agents disclosed in Chinese patent application numbers 201710424183.3 and 201610935614.8 both use higher fatty acid as a raw material to prepare the diesel oil antiwear agent by freezing crystallization and adopting traditional separation methods such as filtration or centrifugation. No application report of microfiltration membrane separation technology in fatty acid separation and diesel antiwear agent preparation is available.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for preparing a diesel antiwear agent by removing saturated fatty acid through membrane separation, wherein the problem of more thorough separation of saturated fatty acid can be solved, and the diesel antiwear agent prepared by separating filtrate under the same cooling and crystallization conditions and blending the filtrate has lower saturated fatty acid content and cloud point which is as low as the condensation point.
In the preparation process of separating saturated fatty acid and diesel antiwear agent, through extensive experimental research, it is found that in the general low-temperature crystallization process, the crystal grain size of saturated fatty acid is mostly above 0.5 micrometer, and the crystal grain with slightly larger size can be obtained by very slow cooling speed and extremely long crystallization curing time. The microfiltration membrane separation technology with constant pore diameter can solve the problem of more thorough separation of saturated fatty acid. The invention solves the technical problems through the following technical scheme.
The invention provides a method for preparing a diesel antiwear agent by removing saturated fatty acid through membrane separation, which comprises the following steps: cooling and crystallizing industrial-grade unsaturated fatty acid, and then continuously separating the cooled and crystallized industrial-grade unsaturated fatty acid by adopting a microfiltration membrane tubular device with the pore diameter of 0.1-1.0 micron under the condition that the pressure difference between two sides of a microfiltration membrane is 0.1-0.6 MPa to obtain a diesel antiwear agent product with lower saturated fatty acid content than that of a conventional diesel antiwear agent product filtered by adopting filter cloth under the same cooling and crystallizing condition.
According to the technical scheme, the cooling crystallization temperature is preferably-10 to-7 ℃, and the cooling time is preferably 6 to 10 hours.
Preferably, the aperture of the microfiltration membrane tubular device is 0.4-0.6 micron.
Further, it is preferable that the pressure difference between both sides of the microfiltration membrane is 0.3 to 0.4MPa.
When the microfiltration membrane tubular device is used for separating the crystallized materials, the materials flow through the surface of the membrane under the pushing of pressure, liquid phase smaller than the membrane holes permeates the membrane body to become filtered liquid, and solid crystal particles larger than the membrane holes are intercepted and discharged, so that the solid-liquid continuous separation is realized. The internal pressure type or external pressure type can be adopted, and the cross flow mode is adopted, so that the deposition on the surface of the membrane is reduced, and the flux of the membrane is improved. The working process of the microfiltration equipment is dynamic, and the separation process is completed in a flowing state. The solid crystal particles are only deposited on the surface of the membrane in a limited way, the microfiltration rate is attenuated to a certain degree and tends to be balanced, and the working performance of microfiltration equipment is recovered through cleaning and regeneration. The microfiltration membrane separation needs a certain pressure as power, and the pressure difference between two sides of the membrane is 0.1-0.6 MPa, preferably 0.3-0.4 MPa. When the pressure difference is too small, the power of the liquid passing through the membrane is reduced, and the time consumed by separation is prolonged; when the pressure is too high, the crystalline particles are easily crushed and aggregated to reduce the flux of the filter membrane or increase the regeneration frequency of the membrane.
The pore size of the microfiltration membrane is 0.1 to 1.0 micron, preferably 0.4 to 0.6 micron. The smaller pore diameter is beneficial to improving the separation ratio of saturated fatty acid, is beneficial to the fact that the product filtrate contains lower saturated fatty acid and produces a diesel antiwear agent with lower cloud point, but the resistance of a liquid phase passing through a microfiltration membrane is increased or the time required for separation is prolonged along with the reduction of the pore diameter, so that the energy consumption is increased; too large a pore size is the opposite.
The microfiltration membrane is not limited in material, needs to be organic phase resistant and can bear corresponding operating pressure. For example, polyvinylidene fluoride, polytetrafluoroethylene, polyOrganic microfiltration membranes of urethane, zrO, etc 2 Or Al 2 O 3 And the like.
Compared with the prior art, the method has the beneficial effects that: compared with the product prepared by the traditional separation method, the diesel antiwear agent obtained by the method has lower saturated fatty acid content, cloud point of the diesel antiwear agent is as low as the condensation point, and low-sulfur diesel oil has better low-temperature performance.
Detailed Description
Example 1
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0 percent) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then the cooled crystallization feed liquid is conveyed to a microfiltration membrane tubular separation device with the aperture of 0.5 micron through a pipeline at the bottom of a reaction kettle under the operating environment of-8 ℃, the cooled crystallization feed liquid is continuously separated by keeping the pressure difference of 0.3MPa, and the diesel oil antiwear agent prepared by the obtained separation liquid has the saturated fatty acid content of 0.6 percent, the cloud point of-16 ℃ and the condensation point of-17 ℃.
Example 2
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0%) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then the cooled crystallization feed liquid is conveyed to a microfiltration membrane tubular separation device with the aperture of 0.5 micron through a pipeline at the bottom of the reaction kettle under the operating environment of-8 ℃, the cooled crystallization feed liquid is continuously separated by keeping the pressure difference of 0.1MPa, the weight percentage content of the saturated fatty acid of the diesel antiwear agent prepared by mixing the obtained separation liquid is 0.6%, the cloud point is-16 ℃, and the condensation point is-17 ℃.
Example 3
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0%) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then the cooled crystallization feed liquid is conveyed to a microfiltration membrane tubular separation device with the aperture of 0.1 micron through a pipeline at the bottom of the reaction kettle under the operating environment of-8 ℃, the cooled feed liquid is continuously separated by keeping the pressure difference of 0.6MPa, the weight percentage content of the saturated fatty acid of the diesel antiwear agent prepared by mixing the obtained separation liquid is 0.5%, the cloud point is-16 ℃, and the condensation point is-17 ℃.
Example 4
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0%) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then the cooled crystallization feed liquid is conveyed to a microfiltration membrane tubular separation device with the aperture of 1.0 micron through a pipeline at the bottom of the reaction kettle under the operating environment of-8 ℃, the cooled feed liquid is continuously separated by keeping the pressure difference of 0.1MPa, the weight percentage content of the saturated fatty acid of the diesel oil antiwear agent prepared by mixing the obtained separation liquid is 0.8%, the cloud point is-15 ℃, and the condensation point is-17 ℃.
Comparative example 1
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0%) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then, common terylene filter cloth is adopted as a filter medium to carry out filter pressing separation on cooling crystallization feed liquid under the pressure difference of 0.3MPa under the operating environment of-8 ℃, and the mass percentage content of the saturated fatty acid of the diesel antiwear agent prepared by blending the obtained filtrate is 2.2%, the cloud point is-9 ℃, and the condensation point is-14 ℃.
Comparative example 2
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0%) is put into a 5L crystallization kettle with jacket cooling to be stirred and cooled to-8 ℃ and kept for 8 hours, then, high-density thickened terylene filter cloth is adopted as a filter medium to carry out filter pressing separation on cooling crystallization feed liquid under the pressure difference of 0.3MPa under the operation environment of-8 ℃, and the diesel oil antiwear agent prepared by blending the obtained filtrate has the content of the saturated fatty acid of 1.8% in percentage by mass, the cloud point of-10 ℃ and the condensation point of-15 ℃.
Comparative example 3
3600 g of industrial grade linoleic acid (the content of saturated fatty acid is 5.0 percent) is put into a 5L crystallization kettle with jacket cooling, stirred and cooled to-8 ℃ and kept for 8 hours, then high-density thickened terylene filter cloth is adopted as a filter medium under the operating environment of-8 ℃ to carry out vacuum filtration separation on the cooled crystallization feed liquid under the vacuum degree of-0.09 MPa, and the weight percent content of the saturated fatty acid of the diesel antiwear agent prepared by blending the obtained filtrate is 1.9 percent, the cloud point is-10 ℃, and the condensation point is-15 ℃.
Measuring the content of saturated fatty acid by gas chromatography; cloud point was determined according to the method specified in ASTM D2500; the freezing point was measured according to the method specified in GB 510.
Claims (5)
1. A method for preparing a diesel antiwear agent by removing saturated fatty acid through membrane separation is characterized in that raw material industrial unsaturated fatty acid is cooled and crystallized, and then a microfiltration membrane tubular device with the pore diameter of 0.1-1.0 micron is adopted to continuously separate the cooled and crystallized industrial unsaturated fatty acid under the condition that the pressure difference between two sides of a microfiltration membrane is 0.1-0.6 MPa, so that a diesel antiwear agent product with lower saturated fatty acid content than that of a conventional diesel antiwear agent product filtered by filter cloth under the same cooling and crystallization conditions is obtained.
2. The method according to claim 1, wherein the cooling crystallization temperature is-10 to-7 ℃ and the cooling time is 6 to 10 hours.
3. The method as claimed in claim 1, wherein the pore size of the microfiltration membrane tube device is 0.4 to 0.6 μm.
4. The method of claim 1, wherein the pressure differential across the microfiltration membrane is between 0.3 and 0.4MPa.
5. The method as claimed in claim 1, wherein the microfiltration membrane is made of polyvinylidene fluoride, polytetrafluoroethylene, polyurethane organic microfiltration membrane, or ZrO 2 Or Al 2 O 3 A ceramic microfiltration membrane.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US3755389A (en) * | 1970-12-24 | 1973-08-28 | Procter & Gamble | Method of separating fatty acids |
| CN103074158A (en) * | 2013-01-29 | 2013-05-01 | 北京普仁生物工程技术有限公司 | Separation method of unsaturated fatty acid |
| CN104130809A (en) * | 2014-08-19 | 2014-11-05 | 安庆市中创生物工程有限公司 | Diesel oil anti-wear agent and preparation method thereof |
| CN104962589B (en) * | 2015-08-05 | 2019-02-26 | 嘉必优生物技术（武汉）股份有限公司 | A kind of microbial oil and preparation method rich in phosphatide type polyunsaturated fatty acid |
| CN106350217B (en) * | 2016-11-01 | 2019-05-28 | 中海油天津化工研究设计院有限公司 | A kind of preparation method of low cloud point fatty acid type diesel antiwear additive |
| CN107057852B (en) * | 2017-06-27 | 2021-01-05 | 管天球 | Preparation method of unsaturated fatty acid tea oil |
| CN110079389B (en) * | 2019-04-25 | 2022-08-30 | 安徽牧洋油脂有限公司 | Deep processing method of animal fat |
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