Preparation method of polyol ester
阅读说明：本技术 一种多元醇酯的制备方法 (Preparation method of polyol ester ) 是由 王俊明 李团乐 张建荣 陈馥婧 周旭光 于 2019-09-27 设计创作，主要内容包括：本发明涉及一种多元醇酯的制备方法,包括以下步骤：以C4～C20直链或支链一元脂肪酸和多元醇为原料,以固体超强酸为催化剂,将原料与催化剂一次性投入反应器后,反应完成得多元醇酯粗品；将多元醇酯粗品进行减压蒸馏,待减压蒸馏至多元醇酯粗品酸值≤1mgKOH/g时,停止减压蒸馏,过滤除去固体催化剂后,对多元醇酯粗品进行分子蒸馏处理。本发明的多元醇酯的制备方法简便、“三废”排放少,生产成本较低、产品品质高,适合于工业化生产。本发明方法制备的多元醇酯适用于航空润滑油、冷冻机油、压缩机油、高温链条油、难燃液压油、难燃变压器油的基础油。(The invention relates to a preparation method of polyol ester, which comprises the following steps: taking C4-C20 straight chain or branched chain monobasic fatty acid and polyhydric alcohol as raw materials, taking solid superacid as a catalyst, putting the raw materials and the catalyst into a reactor at one time, and then completing the reaction to obtain a polyhydric alcohol ester crude product; and (3) carrying out reduced pressure distillation on the crude product of the polyol ester, stopping the reduced pressure distillation when the reduced pressure distillation is carried out until the acid value of the crude product of the polyol ester is less than or equal to 1mgKOH/g, filtering to remove the solid catalyst, and carrying out molecular distillation treatment on the crude product of the polyol ester. The preparation method of the polyol ester is simple, has less discharge of three wastes, lower production cost and high product quality, and is suitable for industrial production. The polyol ester prepared by the method is suitable for base oil of aviation lubricating oil, refrigerating machine oil, compressor oil, high-temperature chain oil, flame-retardant hydraulic oil and flame-retardant transformer oil.)
1. A method for preparing polyol ester, characterized by comprising the steps of:
(1) taking C4-C20 straight chain or branched chain monobasic fatty acid and polyhydric alcohol as raw materials, taking solid superacid as a catalyst, putting the raw materials and the catalyst into a reactor at one time, and then heating for reaction; stopping the reaction when the hydroxyl value of the reaction system is detected to be less than or equal to 3mgKOH/g, and obtaining a crude product of the polyol ester;
(2) carrying out reduced pressure distillation on the crude product of the polyol ester; stopping reduced pressure distillation when the acid value of the crude product of the polyol ester is detected to be less than or equal to 1 mgKOH/g; filtering to remove the solid super acidic catalyst;
(3) and (3) carrying out molecular distillation treatment on the polyol ester crude product subjected to reduced pressure distillation in the step (2).
2. The method for producing a polyol ester according to claim 1, wherein in the step (1),
the C4-C20 straight chain or branched chain monobasic fatty acid is one or a mixture of more than two of n-butyric acid, isobutyric acid, n-valeric acid, 2-methylbutyric acid, 3-methylbutyric acid, trimethylacetic acid, n-hexanoic acid, 2-methylvaleric acid, 2-ethylbutyric acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, 2-methylheptanoic acid, n-nonanoic acid, isononanoic acid, n-decanoic acid, neodecanoic acid, 10-undecylenic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid and oleic acid;
the polyalcohol is one or two of neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol;
the C4-C20 linear chain or branched chain monobasic fatty acid and the polyalcohol are fed according to the molar ratio of carboxyl to hydroxyl of 1.6: 1-1.1: 1.
3. The method for preparing polyol ester according to claim 1, wherein in the step (1), the solid super acidic catalyst is selected from SO4 2-/MxOyOne or two of type solid super acid and composite type solid super acid;
the addition amount of the solid super acid catalyst is 0.1-0.5 wt% of the total mass of the C4-C20 straight chain or branched chain monobasic fatty acid and the polyalcohol.
4. The method for producing a polyol ester according to claim 1, wherein the reaction conditions in the step (1) are: slowly heating to 180-250 ℃, and continuously reacting for 6-12 h.
5. The method for producing a polyol ester according to claim 1, wherein the conditions of the reduced pressure distillation in the step (2) are: distilling under reduced pressure at 120-250 ℃ and 0.01-15 kPa for 6-12 h.
6. The method according to claim 1, wherein in the step (2), the distillate of the vacuum distillation is recovered and reused as a fatty acid raw material.
7. The method for producing a polyol ester according to claim 1, wherein said molecular distillation treatment in said step (3) comprises a primary molecular distillation deacidification treatment which comprises: and adjusting the evaporation temperature to 140-250 ℃ and the vacuum degree to 1-50 Pa, and keeping the weight percentage of the light phase distillate to 5% -15% of the total distillate to obtain a first-stage light phase distillate and a first-stage heavy phase distillate.
8. The preparation method of the polyol ester according to claim 7, wherein the first-stage light phase distillate is enriched and then is subjected to molecular distillation treatment, the evaporation temperature is adjusted to 120-200 ℃, the vacuum degree is adjusted to 1-50 Pa, the light phase distillate is kept to account for 5-10% of the total distillate by mass, and the obtained light phase distillate is the monobasic fatty acid and is recycled; the heavy phase distillate is a polyol ester product.
9. The method for preparing polyol ester according to claim 7, wherein the molecular distillation treatment in the step (3) further comprises subjecting the primary heavy phase distillate to a secondary molecular distillation decolorization treatment comprising: adjusting the evaporation temperature to 180-290 ℃ and the vacuum degree to 0.01-10 Pa, and keeping the light phase distillate to be 85% -95% of the total distillate by mass percent to obtain a secondary light phase distillate, namely a polyol ester product, and a secondary heavy phase distillate;
and (3) continuing to perform molecular distillation treatment on the secondary heavy-phase distillate after enrichment, adjusting the evaporation temperature to 180-280 ℃ and the vacuum degree to 0.01-10 Pa, keeping the light-phase distillate accounting for 60-90% of the total distillate by mass percent, wherein the obtained light-phase distillate is a polyol ester product, and the obtained heavy-phase distillate is pigment-containing impurities.
10. The method for producing a polyol ester according to any one of claims 7 to 9, wherein the obtained polyol ester product is subjected to the test of: if the product is qualified, the product is the final product, and if the product is unqualified, the molecular distillation treatment is continued; the qualified conditions of the product detection of the polyol ester are as follows: the acid value is less than or equal to 0.01mgKOH/g, the hydroxyl value is less than or equal to 3mgKOH/g, the content of each metal element is less than 1ppm, the water content is less than or equal to 100pm, and the chroma is less than 0.5.
Technical Field
The invention relates to a preparation method of polyol ester, in particular to a preparation method of green and environment-friendly high-quality polyol ester.
Background
According to the classification of the American Petroleum Institute (API), synthetic esters represented by diesters, polyol esters, and complex esters belong to group V base oils, and have been widely used in aviation lubricants, refrigeration oils, compressor oils, high-temperature chain oils, flame-retardant hydraulic oils, and automotive oils and various other industrial lubricants because of their excellent lubricity, viscosity-temperature properties, thermal oxidation stability, low volatility, additive sensitivity, biodegradability, low toxicity, and renewable raw materials. The polyol ester has strong controllability of molecular structure, can obtain polyol esters with different viscosity grades, excellent comprehensive performance and meeting the lubricating requirements of different working conditions by reasonably selecting the carbon chain length and the isomerization degree of fatty acid, and is the most important product in the current synthetic ester and the most widely applied product.
At present, inorganic acids such as concentrated sulfuric acid and the like or organic acids such as p-toluenesulfonic acid, methanesulfonic acid and the like are mostly adopted as catalysts in the traditional preparation method of polyol ester, and then products are refined by means of catalyst removal, reduced pressure distillation deacidification, alkali washing, water washing, dehydration, adsorption decoloration and the like. The traditional preparation method has the defects of serious equipment corrosion, complex product post-treatment, difficult catalyst removal, more waste water, waste residue and waste catalyst discharge and lower product quality. Especially, the alkaline washing and water washing process in the traditional production process is easy to cause polyol ester loss and generate a large amount of oily wastewater, the adsorption and decoloration process is also easy to generate more adsorbent waste residues, the discharge amount of three wastes is large, the environment is greatly influenced, and the ecological civilization construction and green chemical concept advocated by the society at present cannot be met. More importantly, the polyol ester produced by the traditional method has low quality, and generally has the defects of high acid value, deep color, large moisture and the like, and particularly, the high acid value and the large moisture can have negative effects on the hydrolytic stability, the oxidation stability and the like of the polyol ester. Because the presence of acid and trace amounts of water results in slow hydrolysis of the polyol ester, causing an increase in its acid value. Therefore, the polyol ester prepared by the traditional method is difficult to meet the requirement of modern industrial equipment on high-quality polyol ester base oil, and the situation that the overall productivity of the polyol ester is sufficient in the domestic market at the present stage, but the high-quality polyol ester depends on imported products is caused.
Since polyol esters are of no importance for replacement in the field of lubricating oils, the research on the production process of polyol esters has not been reduced in recent years. Chinese patent application CN101475467 discloses a new process for synthesizing polyol ester by catalyzing fatty acid lower ester and neopentyl polyol to perform ester exchange reaction by using immobilized lipase in the presence of an organic solvent, wherein the adopted fatty acid lower ester is an alcoholysis product of natural animal and vegetable oil and methanol or ethanol, the raw material source is rich, the cost is low, the ester exchange yield is high, but key performance indexes such as acid value, hydroxyl value and the like of the product are not mentioned, and the lipase is easy to be poisoned and inactivated and has great difficulty in industrialization. Similarly, chinese patent application CN1995364 discloses a method for microwave-assisted enzymatic synthesis of polyol esters, which is green and efficient, but has the problem of difficult industrialization. Chinese patent application CN101456813 discloses a method for synthesizing polyol ester by using functionalized ionic liquid as a catalyst, which has relatively mild conditions, high esterification rate, stable catalyst and recycling, but the method only reflects the esterification rate and does not disclose key technical indexes relating to the performance of polyol ester. Chinese patent application CN101367726 discloses a method for preparing pentaerythritol tetra-erucic acid ester by using rare earth solid-phase heteropoly acid as a catalyst, and the obtained product has high viscosity index and 100% biodegradation, but does not mention key technical indexes such as acid value and the like. Chinese patent application CN101928216 provides a preparation method of polyol ester for lubricating oil, which comprises esterification reaction of polyol and excessive fatty acid, reduced pressure distillation deacidification, further removing residual fatty acid by excessive acid capture agent containing epoxy bond, removing unreacted acid capture agent, alkali washing, water washing, vacuum dehydration, adsorption decoloration. The obtained polyol ester has an acid value lower than 0.02mgKOH/g and high quality, but has a long integral refining process which is basically similar to the traditional process, and the difference is that residual acid is removed only after deacidification is carried out by using an acid catching agent, so that emulsification in an alkaline washing stage is reduced. The Chinese patent application CN103833549 discloses a method for preparing polyol ester by taking titanium source solid acid as a catalyst, which avoids the problems of equipment corrosion, complex product post-treatment, difficult catalyst separation, easy environmental pollution and the like existing in the use of liquid acid catalysts such as sulfuric acid and the like, and has high catalytic efficiency and short reaction period. The Chinese patent application CN104926654 discloses a preparation process of neopentyl polyol 2-ethylhexanoate, the catalyst is p-toluenesulfonic acid, and the preparation process is the same as that of the traditional process. As the acid value is lower than 1.5mgKOH/g, the requirement can be met, and only the alkali washing and water washing link is saved, the preparation of the polyol ester is completed by adsorption and decoloration after reduced pressure distillation and deacidification, but the obtained polyol ester has lower quality and limited application. Chinese patent application CN104619680 discloses a method for preparing polyol ester by using polyol and C3-C20 straight chain or branched chain monobasic fatty acid as raw materials and using Lewis acid containing titanium, zirconium, hafnium or tin as a catalyst, which is characterized in that an adsorbent which is similar to silica gel, diatomite, alumina hydrate, clay, carbonate or active carbon and the like accounting for 0.5-1.5 percent of the total weight of reactants is added into a reaction system at the beginning of the reaction, and the residue of catalyst metal elements in the polyol ester can be obviously reduced by adsorption treatment of acidic active carbon after the reaction is finished. Chinese patent application CN103003227 discloses a decolorization treatment method for polyol ester, which is characterized in that crude ester is treated with peroxide or ozone with strong oxidizing property or metal hydride with strong reducing property, and then treated with steam, dried and filtered to obtain light-colored polyol ester with Hazen color value lower than 20, but with slightly higher acid value (0.06mgKOH/g) and larger water content (0.03%). Similarly, chinese patent application CN102030636 discloses a method for lightening the color of polyol esters without using an adsorbent, i.e. crude esters are treated with aqueous hydrogen peroxide and then treated with steam to obtain light-colored polyol esters with Hazen color values below 100, but also has the problem of large acid value and large water content. Chinese patent application CN 105658613 also discloses a method for post-treating polyol ester, which comprises reacting polyol with C3-C20 straight chain or branched chain monobasic fatty acid in the presence of Lewis acid catalyst and adsorbent, distilling under reduced pressure for deacidification, adding water accounting for 1-4% of the crude ester mass into the crude ester at 60-90 ℃ under specific pressure for treatment to remove Lewis acid catalyst, further treating with hydrogen peroxide to reduce color, and immediately performing steam treatment. It can be seen that the preparation method of polyol ester developed in recent years mostly focuses on two links of catalyst system development and post-treatment process. The main reason is that the catalyst system is related to the completeness of the esterification reaction, and further influences key technical indexes of polyol ester such as hydroxyl value, and the like, and the post-treatment process influences key technical indexes of polyol ester such as acid value, moisture, color, residual metal content and the like. If the polyol ester contains the free fatty acid which cannot be removed completely, the hydrolytic stability of the polyol ester is negatively influenced; the acid value of the water-soluble organic acid is easy to increase due to large water content; the incomplete esterification results in higher hydroxyl value and thus affects the oxidation stability. However, it can be found that in the above known prior art, the disclosures are rarely related to these several key technical indicators of polyol esters. On one hand, the method is difficult to realize the levels of the polyol ester with the acid value less than or equal to 0.01mgKOH/g, the hydroxyl value less than or equal to 3mgKOH/g, the content of metal elements lower than 1ppm, the water content less than or equal to 100pm and the chroma less than 0.5. And the other is convenient, even if the method can reach the required key technical indexes, the product loss and the three-waste discharge amount caused by repeated refining are huge, so that the product cost is high and the competitive advantage is avoided. Moreover, the preparation method still uses traditional processes such as adsorbent adsorption, alkali washing and washing, and the like, and is hard to say that the improvement of the green and environment-friendly process is realized. Therefore, these prior arts still need further improvement in the preparation method and the control of the final product quality.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of green and environment-friendly high-quality polyol ester.
The technical problem to be solved by the invention is realized by the following technical scheme.
The invention provides a preparation method of polyol ester, which comprises the following steps:
(1) taking C4-C20 straight chain or branched chain monobasic fatty acid and polyhydric alcohol as raw materials, taking solid superacid as a catalyst, putting the raw materials and the catalyst into a reactor at one time, and then heating for reaction; stopping the reaction when the hydroxyl value of the reaction system is detected to be less than or equal to 3mgKOH/g, and obtaining a crude product of the polyol ester;
(2) carrying out reduced pressure distillation on the crude product of the polyol ester; stopping reduced pressure distillation when the acid value of the crude product of the polyol ester is detected to be less than or equal to 1 mgKOH/g; filtering to remove the solid super acidic catalyst;
(3) and (3) carrying out molecular distillation treatment on the polyol ester crude product subjected to reduced pressure distillation in the step (2).
In an embodiment of the present invention, in the step (1), the C4-C20 linear or branched fatty acid may be one or a mixture of two or more selected from n-butyric acid, isobutyric acid, n-valeric acid, 2-methylbutyric acid, 3-methylbutyric acid, trimethylacetic acid, n-hexanoic acid, 2-methylpentanoic acid, 2-ethylbutyric acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, 2-methylheptanoic acid, n-nonanoic acid, isononanoic acid, n-decanoic acid, neodecanoic acid, 10-undecylenic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, and oleic acid.
In an embodiment of the present invention, in the step (1), the polyol may be one or two selected from the group consisting of neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol.
In an embodiment of the present invention, in the raw material of step (1), the C4-C20 linear or branched chain monovalent fatty acid and the polyol are fed in a molar ratio of carboxyl group to hydroxyl group of 1.6: 1-1.1: 1, preferably 1.45: 1-1.15: 1.
In an embodiment of the present invention, in the step (1), the solid super acidic catalyst may be selected from SO4 2-/MxOyOne or two of type solid super acid and composite type solid super acid. The solid superacid may be, for example OrSolid super acid. The composite type solid super acid may be, for example Or Solid super acid.
In an embodiment of the present invention, in the step (1), the solid super acid catalyst is added in an amount of 0.1 to 0.5 wt% based on the total mass of the C4 to C20 linear or branched chain mono fatty acid and the polyol.
In an embodiment of the present invention, the conditions of the reaction in step (1) are: slowly heating to 180-250 ℃, and continuously reacting for 6-12 h.
In an embodiment of the present invention, the conditions of the reduced pressure distillation in step (2) are: distilling under reduced pressure at 120-250 ℃ and 0.01-15 kPa for 6-12 h. Thus, the crude ester can be made to have an acid value of 1mgKOH/g or less, and preferably, the crude ester can be made to have an acid value of 0.5mgKOH/g or less by distillation under reduced pressure, so that most of the unreacted raw material fatty acid can be removed.
In the embodiment of the present invention, in the step (2), the distillate of the vacuum distillation may be recovered and utilized as a fatty acid raw material.
In an embodiment of the present invention, the molecular distillation treatment in step (3) includes a primary molecular distillation deacidification treatment which includes: and adjusting the evaporation temperature to 140-250 ℃ and the vacuum degree to 1-50 Pa, and keeping the weight percentage of the light phase distillate to 5% -15% of the total distillate to obtain a first-stage light phase distillate and a first-stage heavy phase distillate. The treatment step removes residual fatty acid in the crude ester after deacidification by reduced pressure distillation in the form of a first-stage light-phase distillate, and collects polyol ester in the form of a first-stage heavy-phase distillate.
In the embodiment of the invention, preferably, the first-stage light-phase distillate is enriched and then can be subjected to molecular distillation treatment, the evaporation temperature is adjusted to 120-200 ℃, the vacuum degree is adjusted to 1-50 Pa, the light-phase distillate is kept to account for 5% -10% of the total distillate by mass, and the obtained light-phase distillate is monobasic fatty acid and is recycled; the heavy phase distillate is a polyol ester product.
In an embodiment of the present invention, the molecular distillation treatment in step (3) may further include subjecting the primary heavy phase distillate to a secondary molecular distillation decolorization treatment including: and adjusting the evaporation temperature to be 180-290 ℃ and the vacuum degree to be 0.01-10 Pa, and keeping the light phase distillate to account for 85% -95% of the total distillate by mass percent to obtain a second-stage light phase distillate, namely a polyol ester product, and a second-stage heavy phase distillate. This treatment step collects the polyol ester product as a secondary light phase distillate and removes the pigment as a secondary heavy phase distillate.
In the embodiment of the invention, preferably, the second-stage heavy-phase distillate is enriched and then subjected to molecular distillation treatment, the evaporation temperature is adjusted to 180-280 ℃, the vacuum degree is adjusted to 0.01-10 Pa, the light-phase distillate accounts for 60% -90% of the total distillate by mass, the obtained light-phase distillate is a polyol ester product, and the obtained heavy-phase distillate is a pigment-containing impurity.
In an embodiment of the invention, the resulting polyol ester product is tested: if the product is qualified, the product is the final product, and if the product is unqualified, the molecular distillation treatment is continued; the qualified conditions of the product detection of the polyol ester are as follows: the acid value is less than or equal to 0.01mgKOH/g, the hydroxyl value is less than or equal to 3mgKOH/g, the content of each metal element is less than 1ppm, the water content is less than or equal to 100pm, and the chroma is less than 0.5.
The preparation method of the polyol ester can also properly adjust the molecular distillation treatment sequence and finally obtain the high-quality polyol ester. If the crude ester is subjected to molecular distillation and first-stage deacidification treatment, then various physical and chemical property analysis and detection are carried out, if incomplete deacidification is detected, the deacidification treatment can be continuously carried out until the acid value is less than or equal to 0.01mgKOH/g, then the decoloration treatment is carried out until the index requirements that the acid value is less than or equal to 0.01mgKOH/g, the hydroxyl value is less than or equal to 3mgKOH/g, the content of each metal element is less than or equal to 1ppm, the water content is less than or equal to 100pm and the chroma is less than 0.5 are met, and then the.
The preparation method of the polyol ester can economically and quickly obtain the high-quality polyol ester, and the preparation method of the invention abandons the processes of alkali washing, adsorbent decoloring, vacuum dehydration and the like of the traditional preparation method, obviously reduces the discharge of waste water and waste residue in the production process of the polyol ester, greatly reduces the loss of the polyol ester in the refining link, and reduces the discharge of chemical wastes by enriching and then treating and recycling the impurities removed in each link, thereby having the obvious characteristic of environmental protection.
Compared with the prior art, the invention has the following beneficial effects:
(1) the preparation method of the polyol ester adopts the solid super acidic catalyst, has high catalytic efficiency, is easy to remove, and has no influence on the color of the product, while the traditional organic acid or inorganic acid catalyst is difficult to remove, is easy to cause the product to have dark color, and generates more acidic catalyst wastes which are difficult to treat.
(2) The preparation method adopts a molecular distillation treatment means in the polyol ester refining link, is a physical process, has mild conditions and simple and convenient operation, does not introduce new impurities and generate too many three wastes, can effectively avoid the discharge problems of adsorbent waste residues generated by adsorption decoloration and a large amount of oily wastewater generated by alkaline washing and water washing in the traditional process, and can recover fatty acid and polyol ester products by enriching impurity phase fractions collected in the treatment process and then performing molecular distillation treatment, thereby hardly causing the loss of the polyol ester, only generating a small amount of waste, greatly reducing the discharge of chemical waste and remarkably reducing the environmental pollution in the production process.
(3) The polyol ester product obtained by the preparation method has an acid value of less than or equal to 0.01mgKOH/g, a hydroxyl value of less than or equal to 3mgKOH/g, metal element contents of less than or equal to 1ppm, water content of less than or equal to 100pm and chroma of less than 0.5, can be used as base oil of aviation lubricating oil, refrigerating machine oil, compressor oil, high-temperature chain oil, flame-retardant hydraulic oil and flame-retardant transformer oil, and has a good market prospect. The preparation method has the advantages of simple process, low cost, short production period, continuous production and suitability for industrial production.
Detailed Description
Example 1
To a 5L reactor equipped with a mechanical stirrer, a thermometer, a nitrogen gas-guide tube and a water-dividing distillation receiver tube were added 817g of pentaerythritol (98%), 987g of n-pentanoic acid, 1168g of n-heptanoic acid, 1420g of isononanoic acid, and,4.40g of solid super acidic catalyst is added with nitrogen, stirred and slowly heated for reaction, and the reaction temperature is controlled to be not higher than 230 ℃. By-product water is timely separated from the water-dividing distillation receiving pipe, and no by-product is produced after 9 hours of reactionWater is generated, the hydroxyl value of the detection system is 2.09mgKOH/g, and reduced pressure distillation is started after the temperature is reduced to 80 ℃. And (3) carrying out reduced pressure distillation on the crude product of the polyol ester for 6h at 220 ℃ under the vacuum degree of 10kPa, detecting that the acid value is 0.52mgKOH/g, and stopping the reduced pressure distillation. And (3) cooling, filtering to remove the solid catalyst, and introducing the crude product of the polyol ester into molecular distillation equipment for primary deacidification treatment. Setting the evaporation temperature to be 185 ℃ and the vacuum degree to be 5Pa, adjusting other molecular distillation parameters, keeping the light phase distillate to be about 10 percent of the total distillate by mass, and continuously distilling. The obtained light phase distillate is recovered and enriched, and the heavy phase distillate directly enters second-stage molecular distillation equipment for decolorization treatment. Setting the evaporation temperature to 210 ℃ and the vacuum degree to 0.1Pa, adjusting other molecular distillation parameters, keeping the light phase distillate accounting for 90 percent of the total distillate by mass, and continuously distilling until all products are treated. The heavy phase distillate is recovered and enriched, the light phase distillate is the polyol ester product, and the analysis and detection are carried out on the heavy phase distillate and the light phase distillate, and the analysis results are shown in table 1, example 1-1. Since the acid number did not meet the index requirements, the first molecular distillation deacidification treatment step was repeated and the analytical results of the polyol ester product obtained are shown in table 1, examples 1-2. The whole preparation process basically does not generate other 'three wastes' except acid wastewater and a small amount of waste solid acid catalyst which are byproducts generated in the reaction stage, and distillates generated in each link can be enriched and then subjected to molecular distillation treatment for recycling.
Example 2
509g of dipentaerythritol (90%), 425g of n-heptanoic acid, 306g of n-octanoic acid, 2409g of isononanoic acid, 208g of n-heptanoic acid, 208g of pentaerythritol, and water were charged into a 5L reactor equipped with a mechanical stirrer, a thermometer, a nitrogen gas line, and a water-dividing distillation receiver tube,19.29g of solid super acidic catalyst, introducing nitrogen, stirring, slowly raising the temperature for reaction, and controlling the reaction temperature to be not higher than 240 ℃. And (3) timely separating by-product water from the water-splitting distillation receiving pipe, reacting for 11 hours without by-product water, detecting the hydroxyl value of the system to be 2.87mgKOH/g, cooling to 80 ℃, and then starting reduced pressure distillation. Vacuum drying the crude product at 240 deg.C under 10kPaAfter 7 hours of distillation under reduced pressure, the acid value was determined to be 0.53mgKOH/g, and the distillation under reduced pressure was stopped. And (3) cooling, filtering to remove the solid catalyst, and introducing the crude product of the polyol ester into molecular distillation equipment for primary deacidification treatment. Setting the evaporation temperature at 230 ℃ and the vacuum degree at 1Pa, adjusting other molecular distillation parameters, keeping the light-phase distillate accounting for about 8 percent of the total distillate by mass, and continuously distilling. The obtained light phase distillate is recovered and enriched, and the heavy phase distillate directly enters second-stage molecular distillation equipment for decolorization treatment. Setting evaporation temperature 281 ℃ and vacuum degree 0.07Pa, adjusting other molecular distillation parameters, keeping the weight percentage of light phase distillate to about 91% of the total distillate, and continuously distilling until all products are treated. The heavy phase distillate is recovered and enriched, the light phase distillate is the polyol ester product, the analysis and detection are carried out on the product, and the analysis result is shown in Table 1
Example 2. The whole preparation process basically does not generate other 'three wastes' except acid wastewater and a small amount of waste solid acid catalyst which are byproducts generated in the reaction stage, and distillates generated in each link can be enriched and then subjected to molecular distillation treatment for recycling.
Example 3
470g of trimethylolpropane (99%), 2491g of oleic acid, 597g of isostearic acid, 266g of isononanoic acid, 266g of n-butyl alcohol, n,11.47g of composite solid super acidic catalyst is added with nitrogen, stirred and slowly heated for reaction, the reaction temperature is controlled to be not higher than 250 ℃, and by-product water is timely separated from the water-splitting distillation receiving pipe. After the reaction is carried out for 6 hours, no by-product water is generated, the hydroxyl value of a detection system is 2.05mgKOH/g, and reduced pressure distillation is started after the temperature is reduced to 80 ℃. After distilling the above system at 240 ℃ under a vacuum of 10kPa for 8 hours, the acid value was detected to be 0.48mgKOH/g, and the distillation under reduced pressure was stopped. And (3) cooling, filtering to remove the solid catalyst, and introducing the crude product of the polyol ester into molecular distillation equipment for primary deacidification treatment. Setting the evaporation temperature at 190 deg.C and vacuum degree at 2Pa, and adjusting the restSub-distillation parameters, keeping the weight percentage of the light phase distillate to about 11 percent of the total distillate mass, and continuously distilling. The obtained light phase distillate is recovered and enriched, and the heavy phase distillate directly enters the second-stage molecular distillation for decolorization treatment. Setting and adjusting the evaporation temperature of 253 ℃ and the vacuum degree of 0.06Pa, adjusting other molecular distillation parameters, keeping the light phase distillate to be about 90 percent of the total distillate by mass percent, and continuously distilling until all products are treated. The heavy phase distillate is recovered and enriched, the light phase distillate is the polyol ester product, and the analysis and detection are carried out on the heavy phase distillate and the light phase distillate, and the analysis results are shown in table 1, example 3-1. Since the acid number did not meet the index requirements, the first molecular distillation deacidification treatment step was repeated and the analytical results of the polyol ester product obtained are shown in table 1, examples 3-2. The whole preparation process basically does not generate other 'three wastes' except acid wastewater and a small amount of waste solid acid catalyst which are byproducts generated in the reaction stage, and distillates generated in each link can be enriched and then subjected to molecular distillation treatment for recycling.
Example 4
In a 5000mL reaction vessel equipped with a mechanical stirrer, a thermometer, a nitrogen gas-guide tube and a water-dividing distillation receiver tube, 258g of neopentyl glycol (99%), 204g of trimethylolpropane (99%), 558g of oleic acid, 2959g of isostearic acid, and,15.91g of solid super acidic catalyst, introducing nitrogen, starting stirring to slowly raise the temperature for reaction, controlling the reaction temperature to be not higher than 250 ℃, timely separating by-product water from the water-splitting distillation receiving pipe, generating no by-product water after 9 hours of reaction, detecting the hydroxyl value of the system to be 1.95mgKOH/g, and starting reduced pressure distillation after cooling to 80 ℃. After the above system was distilled under reduced pressure at 240 ℃ under a vacuum degree of 3kPa for 8 hours, the acid value was detected to be 0.74mgKOH/g, and the distillation under reduced pressure was stopped. And (3) cooling, filtering to remove the solid catalyst, and introducing the crude product of the polyol ester into molecular distillation equipment for primary deacidification treatment. Setting the evaporation temperature of 197 ℃ and the vacuum degree of 2Pa, adjusting other molecular distillation parameters, keeping the light phase distillate accounting for about 12 percent of the total distillate by mass, and continuously distilling. Recovering the rich fraction from the light phase distillateAnd (4) directly feeding the heavy phase distillate into a second-stage molecular distillation for decolorization treatment. Setting and adjusting the evaporation temperature to 246 ℃ and the vacuum degree to 0.06Pa, adjusting other molecular distillation parameters, keeping the light phase distillate to be about 90 percent of the total distillate by mass percent, and continuously distilling until all products are treated. The heavy phase distillate is recovered and enriched, the light phase distillate is the polyol ester product, and the analysis and detection are carried out on the heavy phase distillate and the light phase distillate, and the analysis results are shown in table 1, example 4-1. Since the acid number did not meet the index requirements, the first molecular distillation deacidification treatment step was repeated and the analytical results of the polyol ester product obtained are shown in table 1, examples 4-2. The whole preparation process basically does not generate other 'three wastes' except the acidic wastewater as a byproduct and a small amount of waste solid acid catalyst, and distillates generated in each link can be enriched and then subjected to molecular distillation treatment for recycling.
Example 5
And (3) treating the light-phase distillate enriched in the deacidification treatment by molecular distillation in the example 1 at the evaporation temperature of 145 ℃ and the vacuum degree of 1Pa, adjusting other molecular distillation parameters, keeping the light-phase distillate accounting for about 7 percent of the total distillate by mass, and continuously distilling. The obtained light phase distillate is a fatty acid raw material and can be recycled for preparing polyol ester of the same type, and the heavy phase distillate is a polyol ester product, and the analysis and detection are carried out on the product, wherein the analysis result is shown in table 1, example 5-1. Since the acid value did not meet the index requirements, the molecular distillation deacidification treatment steps were repeated and the analytical results of the polyol ester products obtained are shown in table 1, examples 5-2.
Example 6
And (3) treating the heavy-phase distillate enriched in the molecular distillation decoloring treatment in the example 1 at the evaporation temperature of 200 ℃ and the vacuum degree of 0.1Pa, adjusting other molecular distillation parameters, keeping the light-phase distillate accounting for about 80 percent of the total distillate by mass, and continuously distilling. The obtained heavy phase distillate is pigment-containing impurities, the light phase distillate is a polyol ester product, and the analysis and detection are carried out on the heavy phase distillate and the light phase distillate, and the analysis results are shown in table 1, example 6.
TABLE 1 example polyol ester preparation analytical data
As can be seen from the analysis data in Table 1, the preparation method of the invention can prepare high-quality polyol ester in an environment-friendly, economic and convenient way, and achieve the technical indexes that the acid value is less than or equal to 0.01mgKOH/g, the hydroxyl value is less than or equal to 3mgKOH/g, the content of each metal element is less than 1ppm, the water content is less than or equal to 100ppm, and the chroma is less than 0.5.
Therefore, the preparation method of the polyol ester is simple, has less discharge of three wastes, lower production cost and high product quality, and is suitable for industrial production.
The high-quality polyol ester prepared by the method is suitable for the fields of aviation lubricating oil, refrigerating machine oil, compressor oil, high-temperature chain oil, flame-retardant hydraulic oil, base oil of flame-retardant transformer oil and the like.