阅读说明：本技术 一种分步反应制备合成酯基础油的方法 (Method for preparing synthetic ester base oil through step-by-step reaction ) 是由 时晨 朱兵 孟思凡 李伟 袁鹏 曹昕 于 2020-12-30 设计创作，主要内容包括：本发明涉及一种分步反应制备合成酯基础油的方法,第一步通过多元醇与混和一元酸在醇过量的情况下酯化反应合成多元醇不饱和酯,第二步再以滴加的方式将多元醇不饱和酯投入至含有混合一元酸的反应釜中在局部酸过量的情况下进行酯化反应,反应后期用少量催化剂与剩余不饱和酯混合后滴加进行催化酯化,酯化完成后经精制后处理,过滤得到酸值低、色度好的冷冻机油产品,同时产品收率处于较高水平,对合成高品质的合成酯类润滑油基础油具有重要意义。(The invention relates to a method for preparing synthetic ester base oil by stepwise reaction, which comprises the steps of firstly synthesizing unsaturated polyol ester by esterification reaction of polyol and mixed monoacid under the condition of excessive alcohol, secondly, adding the unsaturated polyol ester into a reaction kettle containing the mixed monoacid in a dropwise manner to perform esterification reaction under the condition of excessive local acid, mixing a small amount of catalyst with the rest unsaturated ester at the later stage of the reaction, dropwise adding the mixture to perform catalytic esterification, refining and post-treating the mixture after the esterification is finished, filtering the mixture to obtain a refrigerating machine oil product with low acid value and good chromaticity, and simultaneously ensuring the product yield to be at a higher level, thereby having important significance for synthesizing high-quality synthetic ester lubricating oil base oil.)

1. A method for preparing synthetic ester base oil through step-by-step reaction is characterized by comprising the following steps:

(1) adding polyalcohol and mixed monobasic fatty acid into a first esterification reaction kettle to perform a first-step esterification reaction;

(2) adding the product of the first esterification reaction into a second esterification reaction kettle containing mixed monobasic fatty acid by adopting a dropwise adding method, and carrying out the second esterification reaction under the condition of excessive local acid;

(3) after the acid value of the reaction system is reduced to a specified range, mixing the product of the residual first-step esterification reaction with a catalyst, and continuously dropwise adding the mixture into the reaction system of the second-step esterification reaction to obtain crude synthetic ester base oil;

(4) and refining the crude synthetic ester base oil to obtain the finished synthetic ester base oil.

2. The method according to claim 1, wherein the mixed mono-fatty acid is composed of two or more of mono-fatty acids having a carbon chain length of 4 to 9.

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

4. The method of claim 1, wherein the first and second esterification reactions are carried out under an inert gas blanket.

5. The method according to claim 1, wherein in the first esterification reaction, the molar ratio of the polyol to the mixed monobasic fatty acid is 2: 1-3: 2.

6. The method according to claim 1, wherein the molar ratio of the raw material polyol to the mixed monobasic fatty acid total alkyd is 1: 1-1: 1.05 in the first and second esterification reactions.

7. The method according to claim 1, wherein the reaction temperature of the first esterification reaction is 160 to 240 ℃, preferably 180 to 220 ℃.

8. The process according to claim 1, wherein the reaction temperature of the second esterification reaction is 150 to 200 ℃, preferably 160 to 180 ℃.

9. The method of claim 1, wherein the catalyst is one or more of a solid super acid, a titanate, and an inorganic acid salt.

10. The method of claim 1, wherein the crude synthetic ester base oil is decolorized with an adsorbent, degassed under reduced pressure, and precision filtered to obtain a finished synthetic ester base oil.

Technical Field

The invention relates to a method for synthesizing high-purity refrigerating machine oil by reacting polyalcohol with mixed monoacid to obtain polyalcohol unsaturated ester, adding the polyalcohol unsaturated ester serving as a raw material into a reaction kettle containing the mixed monoacid in a dropwise manner, and carrying out esterification and refining post-treatment under the action of a catalyst.

The invention synthesizes the high-purity refrigerating machine oil through two-step esterification and refining post-treatment by controlling the molar ratio of the alcohol acid in the whole system. The first step is to esterify and synthesize unsaturated polyol ester with mixed monoacid under the condition of excessive alcohol, the second step is to take the unsaturated polyol ester as raw material and drop the raw material into a reaction kettle containing the mixed monoacid, a small amount of catalyst can be mixed and dropped with 10% unsaturated ester at the later stage of esterification, catalytic esterification is carried out under the condition of excessive local acid, the forward reaction is promoted, and the reaction rate is accelerated. After the esterification is finished, the high-quality synthetic ester base oil is obtained by refining and filtering.

Background

The polyol fatty acid ester refrigerator oil is one kind of high grade synthetic ester lubricating base oil. The lubricating oil can be used as special lubricating oil for refrigerating type compression devices and applied to lubrication, sealing and cooling of various refrigerators. The usual esterification processes to achieve high esterification levels and high reaction rates depend on extending the reaction time, raising the reaction temperature, increasing the acid excess ratio, using special catalysts, etc. But correspondingly increases the equipment loss, the impurity residue and the excessive acid cause the post-treatment refining process to be complex, and the three wastes are increased.

In the prior art, various polyol fatty acid ester preparation processes exist, for example, CN103710155A is a method for preparing biodiesel through high-temperature esterification of high-acid-value grease, high-acid-value grease and a catalyst are added into an esterification reactor, methanol is dripped into the esterification reactor by a dripping device for esterification, and a biodiesel product which is simple in process and easy to industrialize is obtained through post-distillation treatment. CN106187756A A D-methyl lactate esterification process, the process promotes the reaction to be carried out forward by adding methanol dropwise to bring water, the reaction temperature is low, and the purity of the finished product is high. CN109053441A A pentaerythritol oleic acid mixed ester with large bearing capacity and a synthetic method thereof, according to the following steps: pentaerythritol: the molar ratio of the succinic acid monoester is 3: 1: 1.1-1.2, synthesizing; CN108863785A A low pour point pentaerythritol oleate mixed ester and its synthesis method, adopting oleic acid, pentaerythritol, methyl maleate to synthesize; CN108707074A A method for preparing trimethylolpropane oleate with low acid value, which is synthesized by oleic acid, trimethylolpropane and micromolecular anhydride. The reaction processes all use catalysts and water-carrying agents, and simultaneously, the two-step synthesis method uses small molecular acid ester for carrying out hydroxyl end capping, and the procedures of washing and removing the water-carrying agents are added, so that the technical process is complex, and three wastes are increased. The method for synthesizing CN1381437 pentaerythritol oleate synthesizes the lubricant base oil with good high temperature resistance, good lubricating property, excellent viscosity-temperature property and good low-temperature fluidity by using excessive acid; CN108569964A A method for preparing neopentyl glycol ester, which adopts non-acid catalyst to esterify, and removes benzoic acid, isooctanoic acid and water-carrying agent at the later stage.

The above prior art processes rely on prolonged reaction time, increased reaction temperature, increased acid excess ratio, use of special catalysts, etc. to achieve high esterification and high reaction rates. But correspondingly increases the equipment loss, the impurity residue and the excessive acid cause the post-treatment refining process to be complex, and the three wastes are increased.

Disclosure of Invention

The invention aims to provide a method for preparing high-purity synthetic ester base oil through stepwise reaction, which synthesizes refrigerating machine oil through two steps of esterification and refining after controlling the same molar ratio of alcohol acid in the whole system.

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

a method for preparing synthetic ester base oil through step-by-step reaction is characterized by comprising the following steps:

(1) adding polyalcohol and mixed monobasic fatty acid into a first esterification reaction kettle to perform a first-step esterification reaction;

(2) adding the product of the first esterification reaction into a second esterification reaction kettle containing mixed monobasic fatty acid by adopting a dropwise adding method, and carrying out the second esterification reaction under the condition of excessive local acid;

(3) after the acid value of the reaction system is reduced to a specified range, mixing the product of the residual first-step esterification reaction with a catalyst, and continuously dropwise adding the mixture into the reaction system of the second-step esterification reaction to obtain crude synthetic ester base oil;

(4) and refining the crude synthetic ester base oil to obtain the finished synthetic ester base oil.

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

As a further improvement of the invention, the mixed monobasic fatty acid is composed of two or more of monobasic fatty acids with carbon chain length of 4-9, including but not limited to butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid and isomeric acids thereof. Preferably, the raw materials in the first esterification reaction and the second esterification reaction are mixed with the same monobasic fatty acid component and the mixture ratio.

As a further improvement of the invention, the first esterification reaction and the second esterification reaction are carried out under the protection of inert gas.

As a further improvement of the method, in the first step of esterification reaction, the molar ratio of the polyol to the mixed monobasic fatty acid is 2: 1-3: 2.

As a further improvement of the method, the molar ratio of the raw material mixed monobasic fatty acid to the raw material polyol total alkyd related to the first esterification reaction and the second esterification reaction is 1: 1-1: 1.05.

As a further improvement of the method, the reaction temperature of the first esterification reaction is 160-240 ℃, and the preferable reaction temperature is 180-220 ℃.

As a further improvement of the method, the reaction temperature of the second esterification reaction is 150-200 ℃, and the preferable reaction temperature is 160-180 ℃.

As a further improvement of the invention, the catalyst is one or more of solid super acid, titanate and inorganic acid salt.

As a further improvement of the invention, the crude synthetic ester base oil is decolored by adopting an adsorbent, degassed under reduced pressure and filtered precisely to obtain the finished synthetic ester base oil.

As a further improvement of the invention, the adsorbent is one or more of activated clay, diatomite, alkaline bleaching earth, alumina and activated carbon.

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

as a further improvement of the invention, in the decompression degassing process, the temperature is 80-130 ℃, and the vacuum degree is-0.090-0.100 MPa.

The method comprises the steps of reacting step by step, synthesizing unsaturated polyol ester by esterification reaction of polyol and mixed monoacid under the condition of excessive alcohol, and adding the unsaturated polyol ester into a reaction kettle containing the mixed monoacid in a dropwise manner to perform esterification reaction under the condition of excessive local acid, so that the consumption of a catalyst can be reduced and excessive fatty acid can be reduced on the premise of ensuring the performance index of the product; in the later stage of the reaction, a small amount of catalyst can be used for mixing with the rest unsaturated ester and then dropwise adding the mixture for catalytic esterification, so that the reaction is promoted to be carried out in the forward direction, and the reaction rate is increased. After esterification, the product is refined and then filtered to obtain the refrigerator oil product with low acid value and good chromaticity, and meanwhile, the product yield is at a higher level, so that the method has important significance for synthesizing high-quality synthetic ester lubricating oil base oil.

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 (first stage esterification), 2-condensing equipment I, 3-second esterification reaction kettle (catalytic esterification), 4-refining reaction kettle, 5-1-pump I, 5-2-pump II, 5-3-pump III, 5-4-pump IV, 6-finished product receiving device, 7-condensing equipment II, 8-esterified 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 6 are connected in sequence according to the procedure, and a pump i 5-1, a pump ii 5-2, and a pump iii 5-3 are used as material pumps to pump the product into the next reaction vessel/finished product receiving apparatus. The first esterification reaction kettle 1 and the second esterification reaction kettle 3 are respectively connected with a condensing device I2 and a condensing device II 7, mixed steam of fatty acid and water escaping from the reaction is cooled and split, an oil phase returns to the first esterification reaction kettle 1 and the second esterification reaction kettle 3 respectively to continue to participate in the reaction, and a water phase is sent to an esterification water receiving device 8 through a pump IV 5-4.

And (3) carrying out a first-step esterification reaction in the first esterification reaction kettle 1, delivering the product after the reaction to a liquid dropping device at a feed inlet of the second esterification reaction kettle 3 through a pump I5-1, and introducing the product into the second esterification reaction kettle 3 in a dropping mode to carry out a second-step esterification reaction. Initially carrying out esterification reaction under the condition of excessive local acid, uniformly mixing the residual esterification product in the first esterification reaction kettle 1 and a small amount of catalyst after the central control acid value is less than a specified range, and then dropwise adding the mixture into the second esterification reaction kettle 3 to prepare the crude synthetic ester base oil.

The crude synthetic ester base oil is sent into a refining reaction kettle 4 through a pump II 5-2, an adsorbent is added for 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 5-3.

Example 1

Referring to fig. 1, the process flow for preparing the synthetic ester base oil i by using pentaerythritol, isooctanoic acid and isononanoic acid as raw materials is as follows:

carrying out esterification reaction of pentaerythritol, isooctanoic acid and isononanoic acid in a first esterification reaction kettle 1, adding 13.6kg of pentaerythritol, 14.4kg of isooctanoic acid and 15.8kg of isononanoic acid into the esterification reaction kettle, slowly heating to 220-230 ℃ under the protection of nitrogen, stirring for reaction until the acid value of the system is less than 0.01mgKOH/g, and cooling to obtain polyhydric alcohol unsaturated ester I;

carrying out esterification reaction of polyol unsaturated ester I, isooctanoic acid and isononanoic acid in a second esterification reaction kettle 3, adding 14.4kg of isooctanoic acid and 15.8kg of isononanoic acid into the reaction kettle, slowly raising the temperature to 180 ℃ under the protection of nitrogen, adding the esterification product in a first esterification reaction kettle 1 in a dropwise manner, carrying out esterification reaction under the condition of excessive local acid, controlling the acid value to be less than 16mgKOH/g, uniformly mixing the rest esterification product in the first esterification reaction kettle 1 and a small amount of catalyst (0.5 thousandth titanate) and continuously adding the mixture into the reaction kettle in a dropwise manner to carry out catalytic esterification reaction until the acid value of the system is less than 0.01mgKOH/g, and cooling to obtain crude synthetic ester base oil I;

refining the crude synthetic ester base oil I in a refining reaction kettle 4, adding a specified amount of composite adsorbent into the reaction kettle, heating to 70-80 ℃, refining and adsorbing for 2 hours, slowly heating to 100 ℃, degassing for 1 hour under the vacuum degree of-0.090-0.100 Mpa, and precisely filtering to obtain the synthetic ester base oil I.

The acid value of the pentaerythritol isooctanoate isononanoate product is 0.01mgKOH/g, the hydroxyl value is 4.7 mgKOH/g, and the yield is 85.55%. The viscosity of the obtained product at 40 deg.C is 50-300mm²/s。

Example 2

Referring to fig. 1, the process flow for preparing the synthetic ester base oil ii by using neopentyl glycol, n-pentanoic acid and nonanoic acid as raw materials is as follows:

carrying out esterification reaction of neopentyl glycol, n-pentanoic acid and nonanoic acid in a first esterification reaction kettle 1, adding 28.45kg of neopentyl glycol, 15kg of n-pentanoic acid and 20kg of nonanoic acid into the esterification reaction kettle, slowly heating to 210 ℃ and 220 ℃ under the protection of nitrogen, stirring for reaction until the acid value of the system is less than 0.01mgKOH/g, and cooling to obtain polyol unsaturated ester II;

carrying out esterification reaction of polyol unsaturated ester II, n-valeric acid and pelargonic acid in a second esterification reaction kettle 3, adding 15kg of n-valeric acid and 20kg of pelargonic acid into the reaction kettle, slowly raising the temperature to 170 ℃ under the protection of nitrogen, adding the esterification product in the first esterification reaction kettle 1 in a dropwise manner, carrying out esterification reaction under the condition of excessive local acid, controlling the acid value to be less than 18mgKOH/g, uniformly mixing the rest esterification product in the first esterification reaction kettle 1 with a small amount of catalyst (0.5 thousandth of super-strong solid acid), continuously adding the mixture into the reaction kettle in a dropwise manner to carry out catalytic esterification reaction until the acid value of the system is less than 0.05mgKOH/g, and cooling to obtain crude synthetic ester base oil II;

refining the crude synthetic ester base oil II in a refining reaction kettle 4, adding a specified amount of composite adsorbent into the reaction kettle, heating to 60-70 ℃, refining and adsorbing for 1.5-2 hours, slowly heating to 90 ℃, degassing under the vacuum degree of-0.090-0.100 Mpa for 1 hour under reduced pressure, and precisely filtering to obtain the synthetic ester base oil II.

The neopentyl glycol n-pentanoic pelargonic acid ester product has an acid value of 0.05mgKOH/g, a hydroxyl value of 5.7 mgKOH/g and a yield of 87.55%. The viscosity of the obtained product at 40 deg.C is 40-300mm²/s。

Example 3

Referring to fig. 1, the process flow for preparing the synthetic ester base oil iii by taking pentaerythritol, heptanoic acid and hexanoic acid as raw materials is as follows:

carrying out esterification reaction of pentaerythritol, heptanoic acid and hexanoic acid in a first esterification reaction kettle 1, adding 14.05kg of pentaerythritol, 10kg of heptanoic acid and 13.6kg of hexanoic acid into the esterification reaction kettle, slowly heating to 220-230 ℃ under the protection of nitrogen, stirring for reaction until the acid value of the system is less than 0.01mgKOH/g, and cooling to obtain polyhydric alcohol unsaturated ester III;

carrying out esterification reaction of polyol unsaturated ester III, heptanoic acid and n-hexanoic acid in a second esterification reaction kettle 3, adding 10kg of heptanoic acid and 13.6kg of n-hexanoic acid into the reaction kettle, slowly raising the temperature to 190 ℃ under the protection of nitrogen, adding an esterification product in a first esterification reaction kettle 1 in a dropwise manner, carrying out esterification reaction under the condition of excessive local acid, controlling the acid value to be less than 17mgKOH/g, uniformly mixing the esterification product in the rest first esterification reaction kettle 1 and a small amount of catalyst (0.5 per thousand titanate), continuously adding the mixture into the reaction kettle in a dropwise manner to carry out catalytic esterification reaction until the acid value of the system is less than 0.1mgKOH/g, and cooling to obtain crude synthetic ester base oil III;

refining the crude synthetic ester base oil III in a refining reaction kettle 4, adding a specified amount of composite adsorbent into the reaction kettle, heating to 70-80 ℃, refining and adsorbing for 2 hours, slowly heating to 100 ℃, degassing under the vacuum degree of-0.090-0.100 Mpa for 1 hour under reduced pressure, and precisely filtering to obtain the synthetic ester base oil III.

The acid value of the pentaerythritol isoheptanoic acid n-hexanoate product is 0.1mgKOH/g, the hydroxyl value is 3.7 mgKOH/g, and the yield is 86.75%. The viscosity of the obtained product at 40 deg.C is 50-300mm²/s。

Example 4

Referring to fig. 1, the process flow for preparing the synthetic ester base oil iv by using dipentaerythritol, heptanoic acid and nonanoic acid as raw materials is as follows:

carrying out esterification reaction of pentaerythritol, heptanoic acid and nonanoic acid in a first esterification reaction kettle 1, adding 25.4kg of dipentaerythritol, 23.4kg of heptanoic acid and 34.8kg of nonanoic acid into the esterification reaction kettle, slowly heating to 180-190 ℃ under the protection of nitrogen, stirring for reaction until the acid value of the system is less than 0.01mgKOH/g, and cooling to obtain polyhydric alcohol unsaturated ester IV;

carrying out esterification reaction of polyol unsaturated ester IV, heptanoic acid and nonanoic acid in a second esterification reaction kettle 3, adding 15.6kg of heptanoic acid and 17.4kg of nonanoic acid into the reaction kettle, slowly raising the temperature to 160 ℃ under the protection of nitrogen, adding the esterification product in the first esterification reaction kettle 1 in a dropwise manner, carrying out esterification reaction under the condition of excessive local acid, controlling the acid value to be less than 14mgKOH/g, uniformly mixing the rest esterification product in the first esterification reaction kettle 1 and a small amount of catalyst (0.5 per thousand titanate), continuously adding the mixture into the reaction kettle in a dropwise manner to carry out catalytic esterification reaction until the acid value of the system is less than 0.1mgKOH/g, and cooling to obtain crude synthetic ester base oil IV;

refining the crude synthetic ester base oil IV in a refining reaction kettle 4, adding a specified amount of composite adsorbent into the reaction kettle, heating to 70-80 ℃, refining and adsorbing for 2 hours, slowly heating to 100 ℃, degassing for 1 hour under the vacuum degree of-0.090-0.100 Mpa, and performing precise filtration to obtain the synthetic ester base oil IV.

The dipentaerythritol heptanoic acid pelargonic acid ester product has an acid value of 0.1mgKOH/g, a hydroxyl value of 2.5mgKOH/g and a yield of 88.59%. The obtained product has viscosity of 80-350mm at 40 deg.C²/s。

Example 5

Referring to fig. 1, the process flow for preparing the synthetic ester base oil v from pentaerythritol, neopentyl glycol, butyric acid and n-hexanoic acid as raw materials is as follows:

carrying out esterification reaction of pentaerythritol, neopentyl glycol, butyric acid and n-hexanoic acid in a first esterification reaction kettle 1, adding 13.6kg of dipentaerythritol, 10.4kg of neopentyl glycol, 13.2kg of butyric acid and 17.4kg of n-hexanoic acid into the esterification reaction kettle, slowly heating to 190-210 ℃ under the protection of nitrogen, stirring for reaction until the acid value of a system is less than 0.01mgKOH/g, and cooling to obtain polyhydric alcohol unsaturated ester V;

carrying out esterification reaction of unsaturated polyol ester V, butyric acid and n-hexanoic acid in a second esterification reaction kettle 3, adding 13.2kg of butyric acid and 17.4kg of n-hexanoic acid into the reaction kettle, slowly raising the temperature to 200 ℃ under the protection of nitrogen, adding an esterification product in a first esterification reaction kettle 1 in a dropwise manner, carrying out esterification reaction under the condition of excessive local acid, controlling the acid value to be less than 19mgKOH/g, uniformly mixing the esterification product in the rest first esterification reaction kettle 1 and a small amount of catalyst (0.5 per thousand titanate), continuously adding the mixture into the reaction kettle in a dropwise manner to carry out catalytic esterification reaction until the acid value of the system is less than 0.1mgKOH/g, and cooling to obtain crude synthetic ester base oil V;

refining the crude synthetic ester base oil V in a refining reaction kettle 4, adding a specified amount of composite adsorbent into the reaction kettle, heating to 70-80 ℃, refining and adsorbing for 2 hours, slowly heating to 100 ℃, degassing for 1 hour under the vacuum degree of-0.090-0.100 Mpa, and precisely filtering to obtain the synthetic ester base oil V.

The acid value of the synthesized ester base oil V product is 0.1mgKOH/g, the hydroxyl value is 6.1mgKOH/g, and the yield is 86.23%. The obtained product has viscosity of 20-60mm at 40 deg.C²/s。