CN106986751A - A kind of method that crude phenols are extracted from carbolic oil - Google Patents

Abstract

The invention adopts the means of combining azeotropic distillation and extractive distillation to extract phenolic compounds in phenolic oil to obtain crude phenolic products and neutral oil. The used entrainer and extractant are all regenerated to realize recycling. The crude phenol product obtained by the method of the invention has the advantages of good quality, simple technological process, short process flow, less equipment investment, low production cost, high solvent boiling point and less loss, and no consumption of acidic and alkaline substances.

Description

A method for extracting crude phenol from phenol oil

technical field

The invention belongs to the technical field of separation of phenol oil dephenolization, and specifically relates to a method for extracting crude phenol from phenol oil fractions (referred to as phenol oil) of various high, medium and low temperature coal tars and coal direct liquefied oils.

Background technique

Crude phenol is a mixture of a series of phenolic substances, and it is one of the main components of coal tar, a by-product of coal coke. Phenolic substances will increase the oxygen content in coal tar due to their hydroxyl groups, which will not only cause additional hydrogen consumption during the hydrogenation process of coal tar, but also generate water that will adversely affect the catalyst. In addition, high-purity phenolic substances are widely used in agriculture, medicine, dyes and other fields. At present, the development of domestic coal chemical industry has brought a large amount of coal tar, which is rich in a large amount of phenolic oil and phenolic compounds. If the phenolic substances can be separated, it can save resources and have high added value. Can produce good economic benefits. At present, the industrial dephenolization technology is mainly the alkali elution phenol method. This method is simple to operate and has high efficiency. However, this process consumes a large amount of strong acid and strong alkali. The production cost is high, the equipment is seriously corroded, and a large amount of difficult to handle Phenol-containing wastewater, these shortcomings severely limit the industrial application of alkali elution phenol method.

In addition to the alkali elution phenol method, the methods for dephenolization of industrial phenol oil include extractive distillation and double solvent extraction. Extractive distillation is to continuously add high-boiling solvents such as glycerol triacetate, sulfolane, diethylene glycol, etc. to the upper part of the rectification tower, extract phenolic compounds into the solvent, and come out of the tower together with the solvent, while the neutral oil and Pyridines are evaporated from the top of the tower because they are insoluble in solvents. For example, Chinese patent application CN201410162519.X discloses a method for extracting phenolic compounds in direct coal liquefied oil by means of extractive distillation. Practice has proved that the effect of simple extraction and rectification is not satisfactory, especially for some neutral oils with high boiling points and pyridine substances. It is difficult to obtain crude phenol products that meet the national standards. The solvent extraction method is to add some solvents with high solubility to phenols and low solubility to neutral oils in the phenol oil system, so as to separate the phenols from the phenol oil. Generally, the solvent is overheated. Water, saline solution and alcohol solution, etc. For example, Yue Hui used a dual-solvent extraction method to separate phenolic compounds in phenolic oil, and also used a similar principle (Yue Hui, Qin Feifei, Cao Qianming, etc. Separation of phenolic compounds in phenolic oil by dual-solvent extraction[J]. Modern Chemical Industry. 2016, 36(12):106-109). This method has a better removal and extraction effect on neutral oils, but because phenolic substances are weakly acidic and pyridines are weakly alkaline, pyridines will also be entrained in the process of solvent extraction of phenolic substances. This poses a difficult problem for further separation of pyridine. In addition, two solvents are required in dual-solvent extraction, which is a complicated process and a long process.

Contents of the invention

The purpose of the present invention is to provide a method that does not use acid and alkali, does not produce waste water, has a short flow process, low energy consumption, good quality crude phenol products, recyclable entrainer and extractant, can efficiently extract phenol, and can meet the requirements of A method for extracting crude phenol from phenol oil with increasingly stringent environmental protection requirements. The solvent adopted in the method can significantly improve the relative volatility of the phenolic compound and the oil, and is easy to recover.

The technical scheme of the present invention is a method for extracting phenolic compounds from phenol oil by combining azeotropic distillation and extractive distillation, said method comprising the following steps:

A. Add raw material phenol oil in the middle of the first tower, add extractant in the upper part, add entrainer in the lower part of the tower, carry out azeotropic rectification and extractive rectification at the same time, and obtain neutral oil and pyridine substances at the top of the tower A mixture of water and water, the mixture is cooled and separated into phases, the upper layer is a mixture of neutral oil and pyridine, the lower layer is water, part of the water is returned to the tower as reflux, and the other part of the water goes to the third tower for cooling Solvent vapor; the mixture of solvent and phenolic compound is obtained at the bottom of the tower, and enters the second tower after coming out of the tower kettle;

B. Carry out rectification operation in the second tower, steam the phenolic compound from the top of the tower to obtain the crude phenol product, and the polymer produced in the solvent and heating process comes out from the tower kettle and enters the third tower;

C. Solvent recovery is carried out in the third tower, the solvent is steamed from the top of the tower, and the heat in the solvent vapor is used to heat the entrainer water coming out of the top of the first tower to make it into water vapor, and then return to the first tower The lower part of a tower is used as an entrainer, the solvent itself is cooled into a liquid, and returns to the upper part of the first tower as an extractant, and the asphalt-like polymer is released from the bottom of the tower.

The extractant used in the extractive distillation includes one or more of diethylene glycol, triethylene glycol, triacetin and sulfolane. The entrainer used in the azeotropic distillation is water.

In step A, the extraction agent is added to the upper part of the first rectification tower at a position 1 to 10 plates away from the top of the tower, and the entrainer steam is added to the lower part of the tower at a position 1 to 10 plates away from the bottom of the tower. The top of the tower obtains a mixture of neutral oil, pyridine and water substantially free of phenolic compounds, the mixture is cooled and layered, the neutral oil (containing pyridines) is separated from water, and the separated water is separated from the third The overhead distillate (that is, the extraction agent obtained by regeneration) of the first tower is exchanged for heat, and after being turned into steam, it returns to the lower part of the first tower for recycling as an entrainer; the tower still obtains a mixture of phenolic compounds and solvents , the mixture enters the second column for further distillation.

Further, when carrying out extractive rectification and azeotropic rectification in the first tower, the reflux ratio is 0.5～3.0, the consumption of extractant is 1～4 times of phenol oil quality, the used water consumption of azeotropic rectification is 0.2 to 1 times the mass of phenol oil, and the top pressure is 5 to 30kPa.

The advantages of the present invention are:

1, the present invention adopts the method that azeotropic rectification and extractive rectification combine, wherein entrainer water adds from the bottom of rectification tower, can form low The boiling point azeotrope makes it easy for such impurities to evaporate from the top of the tower during the rectification process; the selected extractant is added from the upper part of the rectification tower, which can dissolve various phenolic compounds well, and the neutral Oils and pyridines have poor solubility, so phenolic compounds can be brought into the bottom of the tower well, and finally come out of the tower kettle together with the solvent, and enter the next tower to recover crude phenol. Azeotropic distillation and extractive distillation perfectly combine and work together, which can effectively reduce the content of neutral oil and pyridine in crude phenol products, and significantly improve the quality and yield of crude phenol products.

2. The present invention effectively utilizes the steam waste heat of the solvent (i.e. the extractant) in the regeneration process of the extractant to heat the entrainer water, so that it is vaporized into water vapor, and then the water vapor is returned to the lower part of the first tower for co-entrainment. boiling agent used. Compared with the existing extractive distillation process, it does not significantly increase the heating energy consumption of the distillation process, but it increases the function of azeotropic distillation and better separation effect, and significantly reduces the neutrality in crude phenol The content of oil and pyridine improves the product quality and yield.

3. The present invention does not use acid and alkali solutions, and both the entrainer and the extractant can be recycled.

4. By adopting the method of the present invention to separate phenolic compounds and neutral oil, the obtained crude phenol product has good quality, simple process, short process flow, less equipment investment, low cost, and no need to use low-boiling solvents.

Description of drawings

Figure 1: Schematic flow chart of the present invention for extracting phenolic compounds from phenolic oil.

In the figure: T1 extraction and azeotropic rectification tower, T2 rectification tower, T3 rectification tower, E1 phase separation tank; R1 first reboiler, R2 second reboiler, R3 third reboiler, C1 first Condenser, C2 second condenser, C3 third condenser; 1-extractant; 2-water; 3-neutral oil; 4-solvent containing phenol; 5-crude phenol; 6-solvent containing polymer; 7 - Pitch-like polymers; 8-phenol oil raw material;

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Example 1

The number of trays in tower one is 40, the extractant feed is located at the 5th plate from the top of the tower, the phenol oil feed is located at the second 11 plates in the middle of the tower, and the entrainer feed is located at the bottom of the tower from the bottom of the tower. At 5 plates, the operating pressure at the top of the tower is 30kPa, and the reflux ratio is 0.5. In the middle of tower one, the raw material phenol oil (50% of phenolic substances, 45% of neutral oil, and 5% of pyridines) is passed into the middle of tower one. , are all mass percentages), the selected extractant of the test is diethylene glycol, the feed flow rate is 1000kg/h, the feed flow rate of the entrainer water vapor is 200kg/h, and the output of the tower reactor is separated by tower two (Number of plates: 40, reflux ratio: 2), the pyridines contained in the obtained crude phenol were 0.1%, and the neutral oil was 0.5%. The entrainer and extractant are regenerated and reused through tower three.

Example 2

Adopt the device identical with embodiment 1, the operating pressure of tower one is 20kPa, and the reflux ratio is 1, feeds raw material phenol oil (same as above) with the speed of 1000kg/h in tower one middle part, and the selected extraction agent of test is triacetic acid Glycerides, feed flow rate is 4000kg/h, the feed flow rate of entrainer water vapor is 1000kg/h, and this column still discharges through tower two separation (same as above), and contained pyridines in the crude phenol of gained is 0.4 %, neutral oil is 0.3%. The entrainer and extractant are regenerated and reused through tower three.

Example 3

The same experimental device as in Example 1 was used. The operating pressure of tower one is 5kPa, and the reflux ratio is 3, feeds raw material phenol oil (same as above) with the rate of 1000kg/h in the middle part of tower one, and the extraction agent selected in the test is sulfolane, and feed flow rate is 2500kg/h, total The feeding flow rate of the boiling agent water vapor is 600kg/h, and the output from the tower tank is separated through the second tower (same as above), and the pyridines contained in the crude phenol of the gained are 0.4%, and the neutral oil is 0.6%. The entrainer and extractant are regenerated and reused through tower three.

Example 4

The same experimental device as in Example 1 was used. The operating pressure of tower one is 15kPa, and the reflux ratio is 2, feeds raw material phenol oil (same as above) with the rate of 1000kg/h in the middle part of tower one, and the extraction agent selected in the test is triethylene glycol, and feed flow rate is 1500kg/h , the feed flow rate of entrainer water vapor is 800kg/h, and this column kettle discharge is separated through tower two (same as above), and contained pyridines is 0.2% in the crude phenol of gained, and neutral oil is 0.5%. The entrainer and extractant are regenerated and reused through tower three.

The above embodiments have described the technical solutions of the present invention in detail. Obviously, the invention is not limited to the described embodiments. Based on the embodiments of the present invention, those skilled in the art can make various changes accordingly, but any changes that are equivalent or similar to the present invention fall within the protection scope of the present invention.

Claims (4)

1. a kind of method that phenolic compound is extracted from carbolic oil, it is characterised in that this method is using azeotropic distillation and extraction essence Evaporate the means being combined and phenolic compound is extracted from carbolic oil；It the described method comprises the following steps：

A. raw material carbolic oil is added at the middle part of first tower, top adds extractant, adds entrainer in the bottom of tower, enters simultaneously Row azeotropic distillation and extracting rectifying, the mixture of neutral oil, pyridines material and water is obtained in tower top, after mixture cooling It is layered through split-phase groove, upper strata is the mixture of neutral oil and pyridines material, and lower floor is water, a part of water makees phegma and returns to tower Interior, another part water removes the 3rd tower cooler solvent vapo(u)r；Bottom of towe obtains the mixture of solvent and phenolic compound, goes out from tower reactor Enter second tower after coming；

B. distillation operation is carried out in second tower, phenolic compound is steamed from tower top and obtains crude phenols product, solvent and heating During the polymer that produces out enter from tower reactor in the 3rd tower；

C. solvent recovery is carried out in the 3rd tower, solvent is steamed from tower top, the heat in solvent vapo(u)r is used to heat first The entrainer water that column overhead comes out, makes it become water vapour, then goes back to first tower bottom to make entrainer, and solvent is cooled into itself Liquid, returns to first tower top and makees extractant, the polymer of pitch shape is released from tower reactor.

2. method according to claim 1, it is characterised in that the extractant used in the extracting rectifying is diethylene glycol (DEG), three second Entrainer used is water in one or more in acid glyceride, sulfolane or triethylene glycol, the azeotropic distillation.

3. method according to claim 1, it is characterised in that in step A in first rectifying column positioned at the top of tower from Extractant is added at tower top 1-10 block plates, the bottom of tower is from addition entrainer water vapour at bottom of towe 1-10 block plates.

4. method according to claim 1, it is characterised in that the reflux ratio of first tower is 0.5-3.0, extractant Consumption is 1-4 times of carbolic oil quality, and the consumption of the water vapour used in azeotropic distillation is 0.2-1 times of carbolic oil quality, tower top pressure For 5~30kPa.