阅读说明：本技术 基于膜分离-酯交换法的合成酯基础油生产方法 (Synthetic ester base oil production method based on membrane separation-ester exchange method ) 是由 时晨 朱兵 付鑫 袁鹏 曹昕 于 2021-08-30 设计创作，主要内容包括：本发明涉及基于膜分离-酯交换法的合成酯基础油生产方法,原料酸、原料醇在催化剂的作用下酯化反应,反应生成的醇/水混合蒸气经分离膜脱水后,返回酯化反应体系继续反应,在体系酸值达到规定要求后蒸除过量原料醇,获得酯化反应产物；将第一步酯化反应的产品和多元醇混合后在催化剂的作用下进行酯交换反应,完成反应后精制产物获取合成酯基础油成品。本发明的方法以C4～9混合一元脂肪酸和乙醇为原料,通过酯化-膜分离组合装置催化酯化合成混合脂肪酸乙酯；所得混合酸乙酯脱除乙醇后直接进行酯交换反应,最终的合成酯基础油产品酯化率高、游离酸含量低、色泽好,且使得控制生产环节能耗低、三废产出少二者难以兼顾的问题得到了解决。(The invention relates to a synthetic ester base oil production method based on a membrane separation-ester exchange method, which comprises the steps of carrying out esterification reaction on raw material acid and raw material alcohol under the action of a catalyst, dehydrating alcohol/water mixed steam generated in the reaction through a separation membrane, returning the dehydrated alcohol/water mixed steam to an esterification reaction system for continuous reaction, and evaporating excessive raw material alcohol after the acid value of the system meets the specified requirement to obtain an esterification reaction product; and mixing the product of the first step of esterification reaction with polyhydric alcohol, and then carrying out ester exchange reaction under the action of a catalyst, and refining the product after the reaction is finished to obtain the synthetic ester base oil finished product. According to the method, C4-9 mixed monobasic fatty acid and ethanol are used as raw materials, and the raw materials are catalyzed and esterified by an esterification-membrane separation combined device to synthesize mixed fatty acid ethyl ester; after ethanol in the obtained mixed ethyl acetate is removed, ester exchange reaction is directly carried out, and the final synthetic ester base oil product has high esterification rate, low free acid content and good color and luster, and the problems of low energy consumption in the production link control and less three-waste output which are difficult to be considered are solved.)

1. A synthetic ester base oil production method based on a membrane separation-ester exchange method is characterized by comprising the following steps:

raw material acid and raw material alcohol are subjected to esterification reaction under the action of a catalyst, alcohol/water mixed steam generated in the reaction is dehydrated through a separation membrane and then returns to an esterification reaction system for continuous reaction, and excessive raw material alcohol is evaporated after the acid value of the system reaches the specified requirement, so that an esterification reaction product is obtained;

mixing the product of the first step of esterification reaction with polyhydric alcohol, then carrying out ester exchange reaction under the action of a catalyst, and refining the product after the reaction is finished to obtain a synthetic ester base oil finished product;

wherein the raw material acid is at least two of monobasic fatty acids with carbon chain lengths of 4-9; the raw material alcohol is ethanol.

2. The method of claim 1, wherein the polyol is one or more of neopentyl glycol, trimethylolpropane, pentaerythritol.

3. The method of claim 1, wherein the esterification and transesterification reactions are carried out under the protection of an inert gas.

4. The method of claim 1, wherein the catalyst used in the esterification reaction is one or more of titanate, solid super acid, inorganic acid or acid salt thereof; the dosage of the catalyst is 0.005-0.05% of the total mass of the raw material acid and the raw material alcohol.

5. The method according to claim 1, wherein the molar ratio of acid to alcohol of the raw acid to the raw alcohol is 1: 1.2.

6. the process of claim 1, wherein the temperature of the esterification reaction ranges from 80 ℃ to 150 ℃; preferably 90 ℃ to 120 ℃.

7. The method according to claim 1, wherein the catalyst used in the transesterification reaction is one or more of tin compounds, sodium alkoxide, calcium oxide or hydroxide, and aluminum oxide.

8. The process of claim 1, wherein the temperature of the transesterification reaction is in the range of 100 ℃ to 160 ℃; preferably 120 ℃ to 140 ℃.

9. The method of claim 1, wherein after the transesterification reaction is completed, ethanol is removed from the reaction system; and adsorbing the product by an adsorbent, vacuum degassing and precisely filtering to obtain a finished product of the synthetic ester base oil.

10. The method according to claim 9, wherein the adsorption temperature is 50 to 100 ℃.

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a synthetic ester base oil production method based on a membrane separation-ester exchange method.

Background

The synthetic ester base oil is used as an important component of lubricating oil, and the performance index of the synthetic ester base oil has important influence on the performance of a final oil product. Because the lubricating oil is mostly used for various sealed precise instruments, the hydroxyl value and the acid value of the lubricating oil determine the stability of the lubricating oil in the application process. For high-grade synthetic ester base oil products, the degree of esterification (product hydroxyl value) and the free acid content (product acid value) are important evaluation indexes.

In the prior art, various synthetic processes for synthesizing ester base oil products exist, such as a method for catalytically synthesizing neopentyl polyol fatty acid ester and a catalyst in CN105061202A and a preparation process for neopentyl polyol octadecanoate in CN102030638A, which are all used for preparing neopentyl polyol fatty acid ester by carrying out ester exchange reaction on fatty acid methyl ester and neopentyl polyol under the action of the catalyst. The method mainly discusses the ester exchange reaction conditions, the use of a catalyst and a post-refining purification process, and does not refer to the source and quality standard of raw material methyl fatty acid ester. CN109294745A A fatty acid methyl ester vegetable oil preparation method, adopting vegetable oil or waste kitchen grease to carry out ester exchange reaction with methanol to prepare fatty acid methyl ester biodiesel; CN108329207A is a device and a method for producing fatty acid methyl ester by using a catalytic distillation technology.

In general industrial production, in order to reduce the hydroxyl value of a product and improve the esterification rate of polyhydric alcohol, a raw material acid excess process is generally adopted, and in the later refining process, in order to reduce the acid value of the product to a specified range, long-time high-temperature deacidification and alkali liquor neutralization are required, so that the application of the product is influenced by deepening the color and luster of the product, the production energy consumption and the three-waste output are increased, and the clean production of a lubricating oil product is not facilitated.

Disclosure of Invention

The invention aims to provide a method for producing synthetic ester base oil based on a membrane separation-ester exchange method.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a synthetic ester base oil production method based on a membrane separation-ester exchange method comprises the following steps:

raw material acid and raw material alcohol are subjected to esterification reaction under the action of a catalyst, alcohol/water mixed steam generated in the reaction is dehydrated through a separation membrane and then returns to an esterification reaction system for continuous reaction, and excessive raw material alcohol is evaporated after the acid value of the system reaches the specified requirement, so that an esterification reaction product is obtained;

mixing the product of the first step of esterification reaction with polyhydric alcohol, then carrying out ester exchange reaction under the action of a catalyst, and refining the product after the reaction is finished to obtain a synthetic ester base oil finished product;

wherein the raw material acid is at least two of monobasic fatty acids with carbon chain lengths of 4-9; the raw material alcohol is ethanol.

As a further improvement of the invention, the polyalcohol is one or more of neopentyl glycol, trimethylolpropane and pentaerythritol.

As a further improvement of the invention, the esterification reaction and the ester exchange reaction are carried out under the protection of inert gas; the inert gas may be nitrogen.

As a further improvement of the invention, the catalyst used in the esterification reaction is one or more of titanate, solid super acid, inorganic acid or acid salt thereof. Preferably, the amount of catalyst added is 0.005-0.05% of the total mass of the starting materials.

As a further improvement of the invention, the molar ratio of the acid to the alcohol of the raw material alcohol is 1: 1.2.

As a further improvement of the invention, the starting alcohol (ethanol) has a water content of less than 0.5%.

As a further improvement of the invention, the temperature range of the esterification reaction is 80-150 ℃; preferably 90 ℃ to 120 ℃.

As a further improvement of the invention, the alcohol/water mixed vapor generated in the reaction is dehydrated by a separation membrane to ensure that the water content of the ethanol is not higher than 0.5 percent and then the ethanol returns to the esterification reaction system.

As a further improvement of the invention, the catalyst used in the ester exchange reaction is one or more of tin compounds, sodium alkoxide, calcium oxide or hydroxide and aluminum oxide.

As a further improvement of the invention, the temperature range of the ester exchange reaction is 100-160 ℃; preferably 120 ℃ to 140 ℃.

As a further improvement of the invention, after the ester exchange reaction is finished, ethanol in the reaction system is removed; and adsorbing the product by an adsorbent, vacuum degassing and precisely filtering to obtain a finished product of the synthetic ester base oil.

As a further improvement of the invention, after the ester exchange reaction is finished, the temperature is reduced to the specified temperature, and then the ethanol in the reaction system is removed in vacuum; further, the temperature of vacuum ethanol removal is 80-100 ℃, and the vacuum degree is-0.09 to-0.10 MPa.

As a further improvement of the invention, the composite adsorbent is adopted for adsorption; the composite adsorbent is one or more of activated carbon, activated clay, alkaline bleaching soil and alumina.

As a further improvement of the invention, the adsorption temperature is 50-100 ℃.

As a further improvement of the invention, the vacuum degassing temperature is 80-130 ℃, and the vacuum degree is-0.09 to-0.10 MPa.

According to the method, C4-9 mixed monobasic fatty acid and ethanol are used as raw materials, and the mixed fatty acid ethyl ester with high esterification degree is synthesized by catalytic esterification through an esterification-membrane separation combined device; after the ethanol in the mixed acid ethyl ester is removed, other post-treatment is not needed, the mixed acid ethyl ester is directly subjected to ester exchange reaction with one or more of neopentyl glycol/trimethylolpropane/pentaerythritol, a crude product is refined to remove impurities, and the final synthetic ester base oil product is high in esterification rate, low in free acid content and good in color and luster, and the problems that the energy consumption is low in the production link control, the three-waste output is less and the two are difficult to take into consideration are solved.

Drawings

FIG. 1 is a process flow diagram of the process of the present invention.

FIG. 2 is a schematic diagram of the esterification process of the experimental apparatus of the present invention, in which:

1-first esterification reaction kettle (synthesizing mixed fatty acid ethyl ester), 2-membrane separation device, 3-second esterification reaction kettle (ester exchange), 4-refining reaction kettle, 5-finished product receiving device, 6-1-pump I, 6-2-pump II, 6-3-pump III, 6-4-pump IV, and 7-separated water receiving device.

Detailed Description

In order to better illustrate the invention, we will cite the following examples, but the invention is not limited to the following examples.

The apparatus used in the example is shown in fig. 2, a first esterification reaction vessel 1, a second esterification reaction vessel 3, a refining reaction vessel 4, and a finished product receiving apparatus 5 are connected in sequence according to the procedure, and a pump i 6-1, a pump ii 6-2, and a pump iii 6-3 are used as material pumps to pump the product into the next reaction vessel/finished product receiving apparatus. The upper part of the first esterification reaction kettle 1 is connected with a membrane separation device 2, alcohol/water mixed vapor escaping from the reaction is dehydrated and then circularly sent into the first esterification reaction kettle 1 through a pump IV 6-4, and water separated by the membrane separation device is stored in a separated water receiving device 7.

And (3) carrying out a first-step esterification reaction in the first esterification reaction kettle 1, evaporating excessive raw material alcohol after the reaction is finished, and conveying the product to the second esterification reaction kettle 3 through a pump I6-1 to carry out a second-step esterification reaction to prepare crude synthetic ester base oil.

The crude synthetic ester base oil is sent into a refining reaction kettle 4 through a pump II 6-2, an adsorbent is added for precise adsorption, then vacuum pressure reduction degassing and precise filtration are carried out, and a product is sent into a finished product receiving device 6 through a pump III 6-3.

Example 1

Referring to fig. 1, the technological process for preparing the synthetic ester base oil i by taking trimethylolpropane, n-pentanoic acid, 2-ethylhexanoic acid, isononanoic acid and ethanol as raw materials is as follows:

carrying out esterification reaction of n-pentanoic acid, 2-ethylhexanoic acid, isononanoic acid and ethanol in a first esterification reaction kettle 1, adding 20kg of n-pentanoic acid, 10kg of 2-ethylhexanoic acid, 40kg of isononanoic acid, 28.62kg of ethanol and a proper amount of catalyst into the first esterification reaction kettle 1, wherein the dosage of the catalyst is 0.01 percent of the dosage of the system raw materials, and heating to 100 plus materials under the protection of nitrogen for 110 ℃ heat preservation stirring reaction. Separating ethanol and water from ethanol-water solution evaporated in the reaction process by a membrane separation device 2, controlling the water content in the ethanol to be less than 0.5%, introducing the ethanol in the membrane separation device 2 into a first esterification reaction kettle 1 for continuous esterification reaction until the acid value of the system is less than 0.5mgKOH/g, and evaporating excess ethanol to obtain mixed fatty acid ethyl ester I.

Performing transesterification reaction of mixed fatty acid ethyl ester I and trimethylolpropane in a second esterification reaction kettle 3, adding 23.15kg of trimethylolpropane, a proper amount of catalyst and mixed fatty acid ethyl ester I obtained by one-step esterification reaction into the second esterification reaction kettle 3, wherein the dosage of the catalyst is 0.01 percent of the dosage of system raw materials, heating to 130-140 ℃ under the protection of nitrogen, keeping the temperature, stirring, reacting until the content of polyol ester is more than 98 percent, cooling to 90 ℃, removing ethanol under the condition that the vacuum degree is-0.09 to-0.10 MPa until no solvent is evaporated, and obtaining crude synthetic ester base oil I.

Refining the crude product in a refining reaction kettle 4, adding the crude product synthetic ester base oil I obtained in the two-step reaction, a specified amount of active carbon and bleaching soil into the refining kettle, heating to 70-80 ℃, performing adsorption refining for 1h, then performing vacuum degassing at 120-130 ℃ under the vacuum degree of-0.09 to-0.10 MPa, and finally performing precise filter pressing to obtain the finished product synthetic ester base oil I.

The acid value of the synthetic ester base oil I product is 0.03 mgKOH/g, the hydroxyl value is 2.7 mgKOH/g, and the yield is 89.55 percent. The viscosity of the obtained product at 40 ℃ is 70-300 cSt.

Example 2

Referring to fig. 1, the process flow for preparing the synthetic ester base oil ii by taking pentaerythritol, n-pentanoic acid, heptanoic acid, isononanoic acid and ethanol as raw materials is as follows:

carrying out esterification reaction of n-valeric acid, heptanoic acid, isononanoic acid and ethanol in a first esterification reaction kettle 1, adding 20kg of n-valeric acid, 20kg of heptanoic acid, 40kg of isononanoic acid, 33.28kg of ethanol and a proper amount of catalyst into the first esterification reaction kettle 1, wherein the amount of the catalyst is 0.01 percent of the amount of the system raw materials, heating to 110 ℃ and 120 ℃ under the protection of nitrogen, and carrying out heat preservation and stirring reaction. Separating ethanol and water from ethanol-water solution evaporated in the reaction process by a membrane separation device 2, controlling the water content in the ethanol to be less than 0.5%, introducing the ethanol in the membrane separation device 2 into a first esterification reaction kettle 1 for continuous esterification reaction until the acid value of the system is less than 0.5mgKOH/g, and evaporating excess ethanol to obtain mixed fatty acid ethyl ester II.

Performing transesterification reaction of mixed fatty acid ethyl ester II and pentaerythritol in a second esterification reaction kettle 3, adding 20.49kg of pentaerythritol, a proper amount of catalyst and mixed fatty acid ethyl ester obtained by one-step esterification reaction into the second esterification reaction kettle 3, wherein the dosage of the catalyst is 0.01 percent of the dosage of the system raw materials, heating to 140 ℃ and 150 ℃ under the protection of nitrogen, performing heat preservation and stirring reaction, monitoring the reaction process by adopting HPLC (high performance liquid chromatography), cooling to 90 ℃, and removing ethanol under the condition that the vacuum degree is-0.09 to-0.10 MPa until no solvent is evaporated to obtain crude synthetic ester base oil II.

Refining the crude product in a refining reaction kettle 4, adding the crude product synthetic ester base oil II obtained in the two-step reaction, a specified amount of active carbon and diatomite into the refining kettle, heating to 70-80 ℃, performing adsorption refining for 1h, then performing vacuum degassing at 80-100 ℃ under the vacuum degree of-0.09 to-0.10 MPa, and finally performing precise filter pressing to obtain the finished product synthetic ester base oil II.

The acid value of the synthetic ester base oil I product is 0.05mgKOH/g, the hydroxyl value is 3.7 mgKOH/g, and the yield is 87.47%. The viscosity of the obtained product at 40 ℃ is 70-300 cSt.

Example 3

Referring to fig. 1, a process flow for preparing synthetic ester base oil iii using neopentyl glycol, butyric acid, isooctanoic acid, isononanoic acid and ethanol as raw materials is as follows:

esterification reaction of C8-C10 acid, isooctanoic acid, isononanoic acid and ethanol is carried out in a first esterification reaction kettle 1, 10.3kg of butyric acid, 10kg of isooctanoic acid, 40kg of isononanoic acid, 24.96kg of ethanol and a proper amount of catalyst are added into the first esterification reaction kettle 1, the dosage of the catalyst is 0.01 percent of the dosage of the system raw materials, and the temperature is raised to 100 ℃ and 110 ℃ for heat preservation stirring reaction under the protection of nitrogen. Separating ethanol and water from ethanol-water solution evaporated in the reaction process by a membrane separation device 2, controlling the water content in the ethanol to be less than 0.5%, introducing the ethanol in the membrane separation device 2 into a first esterification reaction kettle 1 for continuous esterification reaction until the acid value of the system is less than 0.5mgKOH/g, and evaporating excess ethanol to obtain mixed fatty acid ethyl ester III.

And (2) carrying out transesterification reaction of mixed fatty acid ethyl ester III and neopentyl glycol in a second esterification reaction kettle 3, adding 23.51kg of neopentyl glycol, a proper amount of catalyst and mixed fatty acid ethyl ester obtained by one-step esterification reaction into the second esterification reaction kettle 3, wherein the dosage of the catalyst is 0.01 percent of the dosage of the system raw material, heating to 130-fold under the protection of nitrogen, keeping the temperature and stirring at 140 ℃, reacting until the content of polyol ester is more than 98 percent, cooling to 90 ℃, and removing ethanol under the condition that the vacuum degree is-0.09 to-0.10 MPa until no solvent is evaporated to obtain crude synthetic ester base oil III.

Refining the crude product in a refining reaction kettle 4, adding the crude product synthetic ester base oil III obtained in the two-step reaction and a specified amount of activated carbon and alumina into the refining kettle, heating to 60-80 ℃, performing adsorption refining for 1h, then performing vacuum degassing at 100-120 ℃ under the vacuum degree of-0.09 to-0.10 MPa, and finally performing precise filter pressing to obtain the finished product synthetic ester base oil III.

The acid value of the synthetic ester base oil I product is 0.07 mgKOH/g, the hydroxyl value is 2.4 mgKOH/g, and the yield is 89.72 percent. The viscosity of the resulting product is 20-150cSt at 40 ℃.

Example 4

Referring to fig. 1, the process flow for preparing the synthetic ester base oil ii by taking pentaerythritol, n-pentanoic acid, heptanoic acid, isononanoic acid and ethanol as raw materials is as follows:

carrying out esterification reaction of n-valeric acid, heptanoic acid, isononanoic acid and ethanol in a first esterification reaction kettle 1, adding 20kg of n-valeric acid, 20kg of heptanoic acid, 40kg of isononanoic acid, 33.28kg of ethanol and a proper amount of catalyst into the first esterification reaction kettle 1, wherein the dosage of the catalyst is 0.01 percent of the dosage of the system raw materials, heating to 90-110 ℃ under the protection of nitrogen, and carrying out heat preservation and stirring reaction. Separating ethanol and water from ethanol-water solution evaporated in the reaction process by a membrane separation device 2, controlling the water content in the ethanol to be less than 0.5%, introducing the ethanol in the membrane separation device 2 into a first esterification reaction kettle 1 for continuous esterification reaction until the acid value of the system is less than 0.5mgKOH/g, and evaporating excess ethanol to obtain mixed fatty acid ethyl ester II.

Performing transesterification reaction of mixed fatty acid ethyl ester II and pentaerythritol in a second esterification reaction kettle 3, adding 20.49kg of pentaerythritol, a proper amount of catalyst and mixed fatty acid ethyl ester obtained by one-step esterification reaction into the second esterification reaction kettle 3, wherein the dosage of the catalyst is 0.01 percent of the dosage of the system raw materials, heating to 120 plus materials under the protection of nitrogen, keeping the temperature and stirring for reaction, monitoring the reaction process by adopting HPLC (high performance liquid chromatography), cooling to 90 ℃, and removing ethanol under the condition that the vacuum degree is-0.09 to-0.10 MPa until no solvent is evaporated to obtain crude synthetic ester base oil II.

Refining the crude product in a refining reaction kettle 4, adding the crude product synthetic ester base oil II obtained in the two-step reaction, a specified amount of active carbon and diatomite into the refining kettle, heating to 70-80 ℃, performing adsorption refining for 1h, then performing vacuum degassing at 80-100 ℃ under the vacuum degree of-0.09 to-0.10 MPa, and finally performing precise filter pressing to obtain the finished product synthetic ester base oil II.

The acid value of the synthetic ester base oil I product is 0.05mgKOH/g, the hydroxyl value is 1.8mgKOH/g, and the yield is 87.63 percent. The viscosity of the resulting product is from 30 to 180 cSt at 40 ℃.