阅读说明：本技术 一种处理中低温煤焦油的天然高效脱酚低共熔萃取剂 (Natural efficient dephenolization eutectic extractant for treating medium and low temperature coal tar ) 是由 欧阳曙光 汪叶洋 刘祖源 江敏 张从风 于 2021-08-13 设计创作，主要内容包括：本发明公开了一种从煤焦油或者煤直接液化油中提取酚类化合物的可回收高效率高选择性不含卤离子的非季铵盐型纯天然低共熔溶剂,其由L-脯氨酸、D-海藻糖、超纯水合成。所述萃取剂的使用方法是：常温下,将中低温煤焦油沸点为180℃-240℃之间的馏分切割得到高酚含量的粗油。加入本发明的低共熔溶剂进行萃取,得到萃取相(萃取剂)和萃余相(萃取后的煤焦油),萃取相采用异丙醚处理后,得到再生的萃取剂,循环使用。本发明有效解决了现有萃取剂需要大量有机酸碱洗脱而且萃取工艺复杂、脱酚效率偏低,萃取剂回收难、溶剂质量损失高,萃取剂含有的卤离子、易吸湿不易保存的季铵盐类溶剂。本发明使用的天然低共荣溶剂其组成均为天然组分,药品廉价易得,合成简单。操作过程简便,降低生产设备采购费用,溶剂不含卤离子,有利于金属设备的长期运行。降低了生产设备维护费用。(The invention discloses a non-quaternary ammonium salt type pure natural eutectic solvent capable of recovering high-efficiency high-selectivity halide-free ions, which is used for extracting phenolic compounds from coal tar or direct coal liquefaction oil and is synthesized by L-proline, D-trehalose and ultrapure water. The use method of the extracting agent comprises the following steps: and cutting the fraction with the boiling point of 180-240 ℃ of the medium-low temperature coal tar at normal temperature to obtain the crude oil with high phenol content. The eutectic solvent is added for extraction to obtain an extract phase (extractant) and a raffinate phase (extracted coal tar), and the extract phase is treated by isopropyl ether to obtain a regenerated extractant for recycling. The invention effectively solves the problems that the prior extracting agent needs a large amount of organic acid and alkali for elution, the extracting process is complex, the dephenolization efficiency is low, the extracting agent is difficult to recover, the quality loss of the solvent is high, and the extracting agent contains halide ions, is easy to absorb moisture and is difficult to store. The components of the natural low-cosmetology solvent used in the invention are all natural components, and the medicine is cheap and easy to obtain and is simple to synthesize. The operation process is simple, the purchase cost of production equipment is reduced, and the solvent does not contain halide ions, thereby being beneficial to the long-term operation of metal equipment. The maintenance cost of production equipment is reduced.)

1. A natural high-efficiency dephenolizing extractant for treating medium-low temperature coal tar or direct coal liquefaction oil is characterized in that the extractant consists of L-proline, D-trehalose and water; wherein the molar ratio of the D-trehalose to the L-proline is 1:2-6, and the adding mass of the ultrapure water is 20-30% of the total mass of the proline and the trehalose.

2. The natural efficient dephenolizing extractant for treating medium and low temperature coal tar or direct coal liquefaction oil according to claim 1, which is characterized in that L-proline, D-trehalose and ultrapure water are respectively mixed according to corresponding proportion or quality, stirred for 45 minutes to 60 minutes at 75 ℃ to 85 ℃ to form uniform transparent light yellow liquid, and kept in original form after standing for more than 48 hours at room temperature.

3. The natural efficient dephenolizing extractant for treating medium and low temperature coal tar or coal direct liquefaction oil according to claim 1, characterized in that the preferable condition is coal tar simulated oil, wherein the simulated oil comprises 20% of n-hexadecane, 30% of toluene and 50% of m-cresol by mass fraction.

4. The natural efficient dephenolizing extractant for treating medium and low temperature coal tar or coal direct liquefaction oil according to claim 2 and claim 3, wherein the molar ratio of D-trehalose to L-proline is preferably 1:3-5, and the mass fraction of ultrapure water is preferably 20% -25%.

5. The natural efficient dephenolizing extractant for treating medium and low temperature coal tar or direct coal liquefaction oil according to claim 1, characterized in that the prepared natural eutectic solvent is suitable for separating phenols in 180-240 ℃ distillate oil in high-content phenol simulation oil, direct coal liquefaction oil or medium and low temperature coal tar.

Technical Field

The invention belongs to the technical field of coal chemical processing, and particularly relates to an environment-friendly and efficient eutectic solvent as an extracting agent for separating phenolic compounds from coal tar or direct coal liquefaction oil.

Background

The phenolic compounds are mainly derived from coal direct liquefaction oil, coal tar, petroleum and biomass pyrolysis oil. The phenol compound accounts for about 10-30% of the total mass fraction of the coal tar, if the phenol compound is not separated out, the hydrogen consumption in the preparation process of the light oil is increased, the catalyst in the later processing of the coal tar is poisoned by water generated by the hydrogenation of the phenol compound, and the phenol compound is an organic chemical raw material with important commercial value and can be used for preparing dyes, medicaments, resins, sterilization disinfectants and the like. Because the traditional acid-base washing method has low efficiency of solvent extraction dephenolization, and excessive acid and alkali are needed to damage the environment.

Some conventional organic solvents have been proposed, although avoiding the use of acid-base solvents, such as: the ionic liquid adopted in the last decade has improved extraction efficiency, but is easy to hydrolyze, difficult to recover and expensive. However, the quaternary ammonium salt is easy to absorb moisture and deteriorate, and halogen elements such as chloride ions, bromide ions and the like carried by the quaternary ammonium salt corrode metal equipment. Its biological low toxicity to the environment has not been fully demonstrated. Some of the dephenolized multi-stage counter-current extraction processes that have been put into use are generally inefficient and the multi-stage extraction process increases the entrainment of neutral oil.

The multi-stage alcohol solvent countercurrent extraction adopted in the patent CN108706825A, the extraction complexation dephenolization adopted in the patent CN1683475A and the dephenolization of the patent CN1450006A distillation method have complex processes, low extraction efficiency and large solvent loss.

The method comprises the steps of mixing an aqueous solution of organic amine and an acidification liquid for extraction and dephenolization adopted in patent CN109825322B, a double-solvent extraction method used in patent CN110003939A, and a dephenolization solvent formed by combining an extraction agent, a co-extraction agent and an antioxidant adopted in patent CN 112811500A; they use a large amount of organic solvent, and have low dephenolization efficiency, and the entrainment of aromatic neutral oil is not effectively solved.

Based on the natural eutectic solvent, the natural eutectic solvent does not contain halogen, natural biodegradable components of amino acid and saccharide used in experiments have high dephenolization selectivity and dephenolization efficiency, has small carrying amount of neutral oil, is easy to biodegrade and harmless to the environment, can be recycled for many times, and aims to overcome the defects in the traditional dephenolization solvent.

Disclosure of Invention

The invention provides a natural efficient dephenolizing extractant for treating medium and low temperature coal tar or direct coal liquefaction oil, aiming at simplifying the process of extracting dephenolizing by the existing extractant, improving the dephenolizing efficiency of the existing extractant, increasing the extraction selectivity and reducing the problem of entrainment of neutral oil.

In order to achieve the above object, the present invention is implemented by the following technical solutions.

The extractant consists of L-proline, anhydrous D-trehalose and ultrapure water; wherein the molar ratio of the L-proline to the D-trehalose is 2-6:1, and the weight of the ultrapure water accounts for 20-30% of the natural eutectic solvent.

Most preferably, when the molar ratio of the L-proline to the D-trehalose is 3-5:1, the optimal addition mass of the ultrapure water is 25% of the natural eutectic solvent.

The natural extractant is applied to the separation of phenolic compounds in the interval of middle-low temperature coal tar or direct coal liquefaction oil rich in phenol boiling fraction.

The extractant can be prepared according to the following steps: respectively adding L-proline and D-trehalose into ultrapure water, stirring and mixing uniformly for 1 hour at 75-85 ℃ to form a yellowish uniform transparent liquid, and then cooling and standing at room temperature to obtain the natural eutectic solvent.

The use steps of the extractant are as follows:

pretreating low-temperature coal tar in step (1)

The medium-low temperature coal tar is placed in a distillation column to cut the components between 180 ℃ and 240 ℃ to obtain the phenol-rich oil.

Step (2) extraction separation

Adding the extractant and the phenol oil treated in the step (1) into oil according to the ratio of the mass (g/g) of the extractant to the volume (ml/ml) of the phenol oil of 1: 1-5, stirring vigorously at normal temperature for 15-60 min, standing for 20-50 min to obtain an upper extraction phase and a lower extraction raffinate phase, discharging the lower extraction raffinate phase, and detecting and analyzing the content of total phenol in the extraction raffinate phase.

Step (3) regeneration of the extractant

Adding isopropyl ether with the mass being 2-8 times that of the extract phase obtained in the step (2) as a back extractant. And (3) back-extracting the phenolic compounds in the natural eutectic solvent by using isopropyl ether, separating the lower eutectic solvent obtained by layering again, and carrying out reduced pressure distillation or atmospheric distillation at 70-80 ℃ for 30-80 min to remove a small amount of isopropyl ether. The recovered natural eutectic solvent is used as an extracting agent for the next step for recycling.

Preferably, the high temperature point of the phenol-rich distillate oil is reduced to 220-230 ℃ in the step (1), and the entrainment of the high-boiling-point component polycyclic aromatic hydrocarbon and the derivative neutral oil thereof is remarkably reduced.

Preferably, the mixture obtained in the step (2) is stirred for 20-30 min and then is kept stand for 30-40 min

Preferably, the molar ratio of the eutectic solvent L-proline to the D-trehalose is 3-4: 1, and most preferably, the weight of ultrapure water is 25% of the weight of the eutectic solvent.

Preferably, the volume ratio of the mass of the extracting agent to the volume of the oil is 1g: 1-3 ml.

Preferably, the mass of the isopropyl ether in the step (3) is 5-6 times of that of the eutectic solvent, and the time of the reduced pressure distillation or the atmospheric pressure distillation is 50-60 min at the temperature of 75 ℃.

Compared with the prior extraction dephenolization technology, the method has the following advantages:

(1) according to the invention, hydrogen bonds are provided by utilizing L-proline and D-trehalose under the coordination of solvent water to form a eutectic solvent, after the distillate oil rich in phenol oil is added, the extraction balance time is only 10-30 min generally, no evaporation loss exists in the extraction agent circulation process, and the loss in the transfer process is lower than 0.1% in the solvent circulation recycling process.

(2) The extracting agent adopts single-stage extraction, the extraction efficiency is high, when high-content phenol simulation oil consisting of 50% of m-cresol, 20% of n-16 alkane and 30% of toluene in mass fraction is adopted, the total phenol removal rate is recycled for 5 times when the mass g of the extracting agent and the volume ml of the oil are 1:2, and the dephenolization effect is kept above 97%;

(3) the regenerated eutectic solvent can be recycled, so that the secondary pollution of the solvent is avoided, and the use cost and the treatment cost of the extracting agent are reduced;

(4) each medicine for synthesizing the extractant is cheap and easy to obtain, and the eutectic solvent does not contain halogen and quaternary ammonium salt which is easy to absorb water and deteriorate. When the water content is not more than 30%, the extractant can still maintain higher dephenolization efficiency.

(5) The eutectic solvent components are amino acid and saccharide, and are easy to biodegrade and will not produce biological toxicity to the use environment.

Drawings

FIG. 1 is a graph of the fit of different phenol contents to nitrotoluene as an internal standard.

FIG. 2 is an infrared chart of L-proline and D-trehalose and 25% ultrapure water obtained in an optimum ratio.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples, but the embodiments of the present invention are not limited thereto, i.e. the present disclosure is not intended to limit the scope of the invention, and any person or entity who can combine the features of the present invention with the present invention to obtain the same or similar products as the present invention by using the present invention or other features of the prior art, is within the scope of the present invention.

(1) Preparation of extractant

[ example 1 ]

The eutectic solvent 1 is a transparent uniform liquid formed by vigorously stirring L-proline and D-trehalose with the molar ratio of 3:1 and the content of ultrapure water accounting for 25% of the mass of the L-proline and the D-trehalose at the temperature of 80 ℃.

[ example 2 ]

The eutectic solvent 2 is a uniform transparent liquid formed by vigorously stirring L-proline and D-trehalose with the molar ratio of 4:1 and the content of ultrapure water accounting for 25% of the mass of the L-proline and the D-trehalose at the temperature of 80 ℃.

[ example 3 ]

The eutectic solvent 3 is prepared by uniformly stirring choline chloride and D-trehalose at a molar ratio of 4:1 at 80 ℃ to form a uniform liquid.

(2) Use of an extractant

1) Preparation of coal tar simulation oil

The real oil component is relatively complex, and in order to explore the performance of the comparative extractant, simulated oil with the mass fractions of 20% of n-hexadecane, 30% of toluene and 50% of m-cresol is prepared to replace medium-low temperature coal tar and is rich in distillate oil.

The phenol content was determined by the following method:

preparing a series of metacresol solutions with different concentrations, wherein o-nitrotoluene is used as an internal standard substance, and ethanol is used as a solvent.

A standard curve showing the ratio of cresol content to area is obtained in a gas chromatography column of the type Pekinelmer type Clarus 590, see FIG. 1. The sample introduction condition is 80 ℃, 1-280 ℃ for 1min, the heating rate is 15 ℃/min, the split ratio 150/1 is selected for 1 mu L sample introduction, and nitrogen gas blowing is 1.5 ml/min.

2) Extraction separation

And (2) respectively stirring the prepared solvent 1, solvent 2, solvent 3 and simulated oil at the mass and volume ratio of 1g:2ml at room temperature for 30min, standing for 30min to obtain an upper extract phase and a lower raffinate phase, transferring the upper extract phase out of a certain volume, and detecting and analyzing the residual m-cresol area of the extract phase and the area of the internal standard substance. The dephenolation efficiency of the different eutectic solvents was calculated according to internal standard by recording the volume of the first and last oil and is shown in table 1. The initial simulated oil phenol content was 0.44996mg/ml, and the infrared characterization of solvent 2 is shown in FIG. 2.

Dephenolization removal rate = 100%

TABLE 1 dephenolation efficiency of the extract phase for different extractants

As can be seen from table 1, the dephenolation efficiency of the eutectic solvent agent 2 is superior to that of the solvent 1 and the solvent 3. The dephenolizing efficiency of the eutectic solvent 3 containing choline is lower than that of the extractant 2 under the same molar ratio, which shows that the solvent 2 has the best effect. Solvent 3 gave a lower final volume than solvent 2, indicating that solvent 3 had more neutral oil entrained than solvent 2.

3) Solvent regeneration

Adding isopropyl ether with the mass 4 times of that of the eutectic solvent into the solvent raffinate phase obtained in the step (2), stirring vigorously for 20min, standing for 30min to obtain an upper-layer extractant and a lower-layer eutectic solvent phase, and separating the upper-layer extractant and the lower-layer eutectic solvent phase to complete extractant regeneration.

4) The extractant can be recycled

And (3) continuously extracting the medium-temperature and low-temperature coal tar simulation oil by using the regenerated extractant according to the step 2), and analyzing the content of the m-cresol in the medium-temperature and low-temperature coal tar simulation oil, wherein the content of the m-cresol is shown in a table 2.

TABLE 2 dephenolization efficiency after continuous regeneration of extractant 1

As described above, the natural efficient eutectic solvent for treating medium-low temperature coal tar or direct coal liquefaction oil provided by the invention has the advantages of short reaction equilibrium time, high dephenolization efficiency, good stability of dephenolization efficiency of cyclic regeneration, cheap and easily-obtained raw materials, simple and convenient operation and separation process, natural components of all the components, no hygroscopic quaternary ammonium salt and halogen, easy biodegradation and no harm to the environment.

The above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art who knows the technical field of the present invention and who has already clarified the present invention shall be within the scope of the present invention according to the technical scheme of the present invention and the idea of the present invention and the replacement or construction of the same kind of characteristic techniques.