CN111848359B - Method for separating phenolic substances in medium and low temperature coal tar - Google Patents
Method for separating phenolic substances in medium and low temperature coal tar Download PDFInfo
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Abstract
The invention belongs to the technical field of separation and purification in the chemical industry, and particularly relates to a method for separating phenols in medium and low temperature coal tar, wherein two extraction separation processes are adopted to separate the phenols with the purity of more than 99%, and the specific steps are as follows: and mixing and settling the medium-low temperature coal tar and the mixed extracting agent to obtain a phenol-rich component, feeding the phenol-rich component into an extraction tower, feeding the heavy component at the bottom of the tower into a recovery tower 2, feeding the component at the top of the recovery tower 2 into a recovery tower 3, and feeding the component at the bottom of the recovery tower 3 into a phenolic substance. The separation process has the advantages of simple operation conditions, low cost of the extracting agent, stable property, low equipment investment and energy consumption, high phenol recovery rate, recycling of the extracting agent and no generation of three wastes.
Description
Technical Field
The invention belongs to the technical field of separation and purification in the chemical industry, and particularly relates to a method for separating phenols in medium and low temperature coal tar.
Background
At present, medium-low temperature coal tar contains a large amount of phenolic substances, phenols and non-phenols are mostly separated by auxiliary methods such as alkali washing, acid washing and neutralization, the operation procedures are more and complicated, the product recovery rate is low, the amount of wastewater in the process is large, the subsequent sewage treatment cost is high, and the method is not beneficial to environmental protection.
Medium and low temperature coal tar is currently used for producing gasoline, the medium and low temperature coal tar contains more phenol products, the added value of phenols is higher, the boiling points of phenols and non-phenols are mutually crossed, the phenols and the non-phenols cannot be separated by common rectification, and the phenols and the non-phenols are mostly separated by auxiliary methods such as alkali washing, acid washing neutralization and the like, so that the operation procedures are more and complicated, the product recovery rate is low, and the amount of wastewater in the process is large.
Disclosure of Invention
For the technical problems existing at present, the invention provides a method for separating phenolic substances from medium and low temperature coal tar, which adopts two extraction and separation processes, has the advantages of simple operation conditions, lower price of an extracting agent, more stable properties, lower equipment investment and energy consumption, high recovery rate of phenols, reuse of the extracting agent and no generation of three wastes.
The technical scheme of the invention is as follows:
a method for separating phenolic substances from medium and low temperature coal tar, wherein the medium and low temperature coal tar is separated into the phenolic substances with the purity of more than 99% by adopting two extraction separation processes, and the specific steps are as follows:
(1) the medium-low temperature coal tar is uniformly mixed with the mixed extracting agent A, B according to a certain proportion, and the mixture is settled and layered, wherein the upper layer is a non-phenolic substance 1, and the lower layer is a phenolic-rich solvent;
(2) the separated phenol-rich solvent enters an extraction tower from the upper end of the tower, and an extractant C enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the components at the top of the extraction tower enter a recovery tower 1, the components at the top of the recovery tower 1 are an extracting agent C and are recycled, and the components at the bottom of the extraction tower are a non-phenolic substance 2;
(4) the components at the bottom of the extraction tower enter a recovery tower 2, the components at the bottom of the recovery tower 1 are an extracting agent A and are recycled, and the components at the top of the tower enter a recovery tower 3;
(5) the tower top component of the recovery tower 3 is a non-phenol substance 3, after the non-phenol substance 3 is stood for layering, the upper layer is a non-phenol substance 4, and the lower layer is an extracting agent B for recycling; the tower bottom component of the recovery tower 3 is phenolic substances;
(6) the non-phenolic substances 1, 2 and 4 are used as oil blending components to blend the diesel oil;
the medium and low temperature coal tar contains 60-70% of phenolic substances and the balance of non-phenolic substances.
Preferably, the extractant a is: one of glycerol, ethylene glycol and diethylene glycol, and the extractant B is: water, triethylamine and organic acid solution.
Further preferably, extractant C is: n-hexane, isohexane, cyclohexane and acetonitrile.
Preferably, the mass ratio of the extracting agents A and B in the mixed extracting agent A, B is 2:1-10:1, and the mass ratio of the mixed extracting agent A, B to the medium-low temperature coal tar is 1:1-20: 1.
Further preferably, the mass ratio of the extracting agents A and B in the mixed extracting agent A, B is 1:1-5: 1; the mass ratio of the mixed extracting agent A, B to the medium-low temperature coal tar is 5:1-15: 1.
Preferably, the mass ratio of the extracting agent C to the medium-low temperature coal tar is 1:1-20: 1.
Further preferably, the mass ratio of the extracting agent C to the medium-low temperature coal tar is changed to 1:1-5: 1.
Preferably, the temperature at the top of the recovery tower 1 is 67-72 ℃, the pressure at the top of the recovery tower is 101.3-120Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 169-179 ℃.
Preferably, the temperature at the top of the recovery column 2 is 118-121 ℃, the pressure at the top of the recovery column is 15-35Kpa (absolute pressure), and the temperature at the bottom of the recovery column is 230-240 ℃.
Preferably, the temperature at the top of the recovery column 3 is 87 to 89 ℃, the pressure at the top of the column is 15 to 35Kpa (absolute pressure), and the temperature at the bottom of the column is 155-162 ℃.
Preferably, the extraction tower is a packed extraction tower, the recovery tower 1, the recovery tower 2 and the recovery tower 3 are packed recovery towers, and other types of extraction towers or recovery towers can be selected according to actual needs.
In the medium-low temperature coal tar, the non-phenolic substances contained in the medium-low temperature coal tar are other components such as 1, 3, 5-trimethylbenzene, o-xylene, n-dodecane, indane, 1-methylnaphthalene, pyridine, naphthalene, indene, methyl ethylbenzene, tetramethylbenzene and the like.
The invention provides a method for separating phenolic substances from medium and low temperature coal tar, which comprises the steps of uniformly mixing the medium and low temperature coal tar with a mixed extracting agent A, B, settling and layering, wherein the upper layer is a non-phenolic substance 1, the lower layer is a phenol-rich solvent, the phenol-rich solvent enters an extraction tower from the upper end of the tower, the extracting agent enters the extraction tower from the lower end of the tower, a light component at the top of the tower enters a recovery tower 1, a component at the top of the recovery tower 1 is an extracting agent C, recycling is carried out, and a component at the bottom of the recovery tower 1 is a non-phenolic substance 2; the tower bottom component of the extraction tower enters a recovery tower 2, the tower bottom component of the recovery tower 2 is an extracting agent A and is recycled, the tower top component of the recovery tower 2 enters a recovery tower 3, the tower top component of the recovery tower 3 is subjected to standing and layering, the upper layer is a non-phenolic substance 4, the lower layer is an extracting agent B and is recycled, the tower bottom component of the recovery tower 3 is a phenolic substance, and the purity is higher than 99%; in the invention, the non-phenolic substances 1, 2 and 4 can be used as oil blending components to blend the diesel oil. The extractant of the invention can be recycled, thus reducing cost, reducing resource waste and avoiding environmental pollution.
The invention adopts the mixed extractant and two extraction separation processes, the effect of separating phenolic substances from non-phenolic substances is optimal, which can not be realized by a single extractant and a single extraction separation; the boiling points of phenolic substances and non-phenolic substances are crossed, and the phenolic substances and the non-phenolic substances cannot be separated by ordinary rectification, but the high-purity phenolic substances can be separated by extracting twice and then passing through a recovery tower by the method; the method has the advantages of fewer and simple processes, high product recycling rate, more than 99% of the purity of the recycled phenolic substances, and capability of recycling the extracting agent in the process, thereby reducing the waste of resources.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principles of the invention and these modifications should also be considered as within the scope of the invention.
In the embodiment, the medium-low temperature coal tar contains 60-70% of phenolic substances and the balance of non-phenolic substances.
Example 1
A method for separating phenols in medium and low temperature coal tar is provided, wherein the medium and low temperature coal tar adopts two extraction separation processes to separate phenols with purity of more than 99%, and the specific steps are as follows:
(1) the medium-low temperature coal tar is uniformly mixed with the mixed extracting agent A, B according to a certain proportion, and the mixture is settled and layered, wherein the upper layer is a non-phenolic substance 1, and the lower layer is a phenolic-rich solvent;
(2) the separated phenol-rich solvent enters an extraction tower from the upper end of the tower, and an extractant C enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the components at the top of the extraction tower enter a recovery tower 1, the components at the top of the recovery tower 1 are an extracting agent C and are recycled, and the components at the bottom of the extraction tower are non-phenolic substances 2;
(4) the components at the bottom of the extraction tower enter a recovery tower 2, the components at the bottom of the recovery tower 1 are an extracting agent A and are recycled, and the components at the top of the tower enter a recovery tower 3;
(5) the tower top component of the recovery tower 3 is a non-phenol substance 3, after the non-phenol substance 3 is stood for layering, the upper layer is a non-phenol substance 4, and the lower layer is an extracting agent B for recycling; the tower bottom component of the recovery tower 3 is phenolic substances;
(6) the non-phenolic substances 1, 2 and 4 are used as oil blending components to blend the diesel oil;
the mass ratio of the extracting agent A to the extracting agent B in the mixed extracting agent A, B is 5: 1; the mass ratio of the medium-low temperature coal tar to the mixed extractant is 5: 12; the proportion of the extractant C to the medium-low temperature coal tar is 1: 1;
the temperature at the top of the recovery tower 1 is 69.4 ℃, the pressure at the top of the recovery tower is 110Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 172.5 ℃; the temperature at the top of the recovery tower 2 is 119.7 ℃, the pressure at the top of the recovery tower is 20Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 232.5 ℃; the temperature at the top of the recovery column 3 was 88.6 ℃ and the pressure at the top was 20Kpa (absolute) and the temperature at the bottom was 157.4 ℃.
The sum of the phenolic substances of the separated products is 99.32 percent.
Example 2
A method for separating phenols from medium and low temperature coal tar adopts two extraction and separation processes to separate phenols with purity of more than 99%, and comprises the following specific steps:
(1) the medium-low temperature coal tar is uniformly mixed with the mixed extracting agent A, B according to a certain proportion, and the mixture is settled and layered, wherein the upper layer is a non-phenolic substance 1, and the lower layer is a phenolic-rich solvent;
(2) the separated phenol-rich solvent enters an extraction tower from the upper end of the tower, and an extracting agent C enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the components at the top of the extraction tower enter a recovery tower 1, an extractant C is arranged at the top of the recovery tower 1 and is recycled, and a non-phenolic substance 2 is arranged at the bottom of the recovery tower;
(4) the components at the bottom of the extraction tower enter a recovery tower 2, the components at the bottom of the recovery tower 1 are an extracting agent A and are recycled, and the components at the top of the tower enter a recovery tower 3;
(5) the tower top component of the recovery tower 3 is a non-phenol substance 3, after the non-phenol substance 3 is stood for layering, the upper layer is a non-phenol substance 4, and the lower layer is an extracting agent B for recycling; the tower bottom component of the recovery tower 3 is phenolic substances;
(6) the non-phenolic substances 1, 2 and 4 are used as oil blending components to blend the diesel oil;
the mass ratio of the extracting agent A to the extracting agent B in the mixed extracting agent A, B is 10: 3; the mass ratio of the medium-low temperature coal tar to the mixed extractant is 5: 13; the proportion of the extractant C to the medium-low temperature coal tar is 1:1
The temperature at the top of the recovery tower 1 is 68.4 ℃, the pressure at the top of the recovery tower is 120Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 171.3 ℃; the top temperature of the recovery tower 2 is 120.2 ℃, the top pressure is 20Kpa (absolute pressure), and the bottom temperature is 235.3 ℃; the top temperature of the recovery tower 3 is 88.3 ℃, the top pressure is 20Kpa (absolute pressure), and the bottom temperature is 159.6 ℃;
the sum of the phenolic substances of the separated products is 99.51%.
Example 3
A method for separating phenolic substances from medium and low temperature coal tar, wherein the medium and low temperature coal tar is separated into the phenolic substances with the purity of more than 99% by adopting two extraction separation processes, and the specific steps are as follows:
(1) the medium-low temperature coal tar is uniformly mixed with the mixed extracting agent A, B according to a certain proportion, and the mixture is settled and layered, wherein the upper layer is a non-phenolic substance 1, and the lower layer is a phenolic-rich solvent;
(2) the separated phenol-rich solvent enters an extraction tower from the upper end of the tower, and an extractant C enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the components at the top of the extraction tower enter a recovery tower 1, an extractant C is arranged at the top of the recovery tower 1 and is recycled, and a non-phenolic substance 2 is arranged at the bottom of the recovery tower;
(4) the tower bottom component of the extraction tower enters a recovery tower 2, the tower bottom component of the recovery tower 1 is an extracting agent A and is recycled, and the tower top component enters a recovery tower 3;
(5) the tower top component of the recovery tower 3 is a non-phenol substance 3, after the non-phenol substance 3 is stood for layering, the upper layer is a non-phenol substance 4, and the lower layer is an extracting agent B for recycling; the tower bottom component of the recovery tower 3 is phenolic substances;
(6) the non-phenolic substances 1, 2 and 4 are used as oil blending components to blend the diesel oil;
the mass ratio of the extracting agent A to the extracting agent B in the mixed extracting agent A, B is 5: 2; the mass ratio of the medium-low temperature coal tar to the mixed extractant is 5: 14; the ratio of the extracting agent C to the medium-low temperature coal tar is 1:1
The temperature at the top of the recovery tower 1 is 68.1 ℃, the pressure at the top of the recovery tower is 110Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 171.7 ℃; the temperature at the top of the recovery tower 2 is 120.5 ℃, the pressure at the top of the recovery tower is 20Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 235.6 ℃; the temperature at the top of the recovery tower 3 is 87.9 ℃, the pressure at the top of the recovery tower is 20Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 158.4 ℃;
the sum of the phenolic substances of the separated products is 99.67 percent.
Comparative example 1
A method for separating phenols in medium and low temperature coal tar comprises the following specific steps:
(1) medium-low temperature coal tar enters an extraction tower from the upper end of the tower, and an extracting agent enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the light component at the top of the extraction tower is a non-phenol component, and the heavy component at the bottom of the extraction tower is a phenol-rich solvent;
(4) the phenol-rich solvent 1 enters a recovery tower, the tower bottom component of the recovery tower is an extracting agent, and the tower top phenolic substances;
the extractant is glycerol;
the mass ratio of the extracting agent to the medium-low temperature coal tar is 8: 1;
the temperature at the top of the recovery tower is 121.1 ℃, the pressure at the top of the recovery tower is 20Kpa (absolute pressure), and the temperature at the bottom of the recovery tower is 237.7 ℃;
the sum of the phenolic substances of the separated products is 91.42 percent.
The content of phenols obtained by the method for separating the phenols from the medium and low temperature coal tar is more than 99.32 percent; however, by the separation method of comparative example 1, the obtained phenolic content was only 91.42%. The invention adopts the mixed extractant and two extraction separation processes, can effectively separate phenolic substances and non-phenolic substances, has simple operation condition, lower price of the selected extractant, more stable property, lower equipment investment and energy consumption, high recovery rate of phenols, reusability of the extractant and no generation of three wastes.
Claims (4)
1. A method for separating phenolic substances in medium and low temperature coal tar is characterized in that a two-step extraction separation process is adopted to separate the phenolic substances with the purity of more than 99 percent, and the specific steps are as follows:
(1) the medium-low temperature coal tar is uniformly mixed with the mixed extracting agent A, B according to a certain proportion, and the mixture is settled and layered, wherein the upper layer is a non-phenolic substance 1, and the lower layer is a phenolic-rich solvent;
(2) the separated phenol-rich solvent enters an extraction tower from the upper end of the tower, and an extractant C enters the extraction tower from the lower end of the tower and is subjected to countercurrent extraction;
(3) the components at the top of the extraction tower enter a recovery tower 1, the components at the top of the recovery tower 1 are an extracting agent C and are recycled, and the components at the bottom of the extraction tower are non-phenolic substances 2;
(4) the tower bottom component of the extraction tower enters a recovery tower 2, the tower bottom component of the recovery tower 2 is an extracting agent A and is recycled, and the tower top component enters a recovery tower 3;
(5) the tower top component of the recovery tower 3 is a non-phenol substance 3, after the non-phenol substance 3 is stood for layering, the upper layer is a non-phenol substance 4, and the lower layer is an extracting agent B for recycling; the tower bottom component of the recovery tower is phenolic substances;
(6) the non-phenolic substances 1, 2 and 4 are used as oil blending components to blend the diesel oil;
the medium-low temperature coal tar contains 60-70% of phenolic substances and the balance of non-phenolic substances;
the extractant A is as follows: one of glycerol, ethylene glycol and diethylene glycol, and the extractant B is: one of water, triethylamine and organic acid solution;
the extractant C is as follows: one of n-hexane, isohexane, cyclohexane and acetonitrile;
the temperature of the top of the recovery tower 1 is 67-72 ℃, the pressure of the top of the recovery tower is 101.3-120Kpa, and the temperature of the bottom of the recovery tower is 169-179 ℃;
the tower top temperature of the recovery tower 2 is 121 ℃ plus 118 ℃, the tower top pressure is 15-35Kpa, and the tower bottom temperature is 230 ℃ plus 240 ℃;
the top temperature of the recovery tower 3 is 87-89 ℃, the top pressure is 15-35Kpa, and the bottom temperature is 155-162 ℃.
2. The method for separating phenolic substances from medium and low temperature coal tar according to claim 1, wherein the mass ratio of the extracting agent A to the extracting agent B in the mixed extracting agent A, B is 2:1-10:1, and the mass ratio of the mixed extracting agent A, B to the medium and low temperature coal tar is 1:1-20: 1.
3. The method for separating phenolic substances from medium and low temperature coal tar according to claim 1, wherein the mass ratio of the extracting agent C to the medium and low temperature coal tar is 1:1-20: 1.
4. The method for separating phenolic substances from medium and low temperature coal tar according to claim 3, wherein the mass ratio of the extracting agent C to the medium and low temperature coal tar is 1: 1-5:1.
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