CN113087585B - Method for producing paraxylene and ethylbenzene from mixed C8 aromatic hydrocarbons - Google Patents
Method for producing paraxylene and ethylbenzene from mixed C8 aromatic hydrocarbons Download PDFInfo
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Abstract
The invention belongs to the technical field of aromatic hydrocarbon production, and relates to a method for producing paraxylene and ethylbenzene by using mixed C8 aromatic hydrocarbon. The method comprises the following steps: carrying out first liquid-phase adsorption separation on the mixed C8 aromatic hydrocarbon to obtain a first extract rich in paraxylene and a first raffinate rich in ethylbenzene; rectifying the first extract to obtain a paraxylene product and a first extract residual solution; rectifying the first raffinate to obtain a mixture containing ethylbenzene, o-xylene and m-xylene and a first raffinate residual solution; performing second liquid phase adsorption separation on the mixture to obtain a second extract rich in ethylbenzene and a second raffinate poor in ethylbenzene; rectifying the second extract to obtain an ethylbenzene product and a second extract residual solution; and rectifying the second raffinate to obtain a mixture rich in o-xylene and m-xylene and a second raffinate residual solution. The method reduces the energy consumption for separating the paraxylene and the ethylbenzene from the C8 aromatic hydrocarbon.
Description
Technical Field
The invention belongs to the technical field of aromatic hydrocarbon production, and particularly relates to a method for producing paraxylene and ethylbenzene by using mixed C8 aromatic hydrocarbons.
Background
The paraxylene and the ethylbenzene are important basic organic chemical raw materials and have wide market application prospect. Ethylbenzene is used primarily for the production of styrene.
The use of adsorptive separation processes to produce high purity para-xylene is well known to those skilled in the art. There are two types of processes for producing high purity ethylbenzene, one being the reaction to produce ethylbenzene. The other is ethylbenzene obtained by a separation process in C8 aromatics.
As a method for producing ethylbenzene by the reaction, patent document CN108698952a discloses a method for producing ethylbenzene. The method comprises the following steps: (a1) Providing benzene and an alkylating agent comprising at least 40wt% ethylene to an alkylation reaction zone; (b1) Adding at least one C3+ olefin to the alkylation reaction zone in an amount of at least 200ppm by weight based on the ethylene supplied to the alkylation reaction zone; and (C1) contacting benzene, ethylene and C3+ olefins with an alkylation catalyst in an alkylation reaction zone under alkylation conditions effective to alkylate at least a portion of the benzene and produce an alkylation effluent comprising ethylbenzene, polyethylbenzenes, and at least one mono-C3 + alkylbenzene; (d1) Separating the alkylation effluent into at least a first product fraction comprising ethylbenzene and a second fraction comprising polyethylbenzenes and the at least one mono-C3 + alkylbenzene; and (e 1) contacting at least a portion of the second fraction with benzene in the presence of a transalkylation catalyst under transalkylation conditions effective to convert at least a portion of the polyethylbenzene to ethylbenzene and produce a transalkylation effluent. The process employs benzene and ethylene and C3+ olefins via an alkylation reaction to produce a first product fraction comprising ethylbenzene and a second fraction comprising polyethylbenzene, the second fraction being passed over a transalkylation catalyst with the benzene to produce ethylbenzene. Patent document CN106518604a discloses a synthesis method of ethylbenzene. The method comprises the steps of contacting dilute ethane with benzene over a catalyst to produce ethylbenzene; the catalyst comprises the following components in percentage by weight: a) 75-95% of ZSM-5 molecular sieve; b) 5 to 25 percent of at least one auxiliary agent selected from nickel, cobalt, iron or palladium. The reaction products generated by the synthesis method all contain byproducts, for example, the product does not pass through the subsequent flow Cheng Dichun, and the purity of the ethylbenzene is difficult to reach 95%.
For the process of obtaining ethylbenzene by separation, patent document CN103373890a discloses a process for separating ethylbenzene from C 8 Adsorption in aromatic hydrocarbonsA process for separating para-xylene and ethylbenzene comprising subjecting C to 8 The aromatic hydrocarbons are separated by liquid phase adsorption to obtain extract oil containing paraxylene and raffinate oil containing ethylbenzene, m-xylene and o-xylene; and (3) performing gas phase pressure swing adsorption separation on raffinate oil obtained by liquid phase adsorption separation to obtain pressure swing adsorption raffinate and desorption liquid, and separating non-aromatic hydrocarbons in the desorption liquid to obtain ethylbenzene. Patent document CN101045671a discloses a method for adsorption-crystallization separation of p-xylene and ethylbenzene from C8 aromatic hydrocarbons, which comprises the steps of adsorbing and separating the C8 aromatic hydrocarbons into a first stream containing ethylbenzene and p-xylene and a second stream containing m-xylene and o-xylene, then crystallizing and separating the p-xylene in the first stream, and adsorbing and separating mother liquor after crystallization and separation to separate the ethylbenzene from the mother liquor. The components need to be vaporized by adopting gas phase pressure swing adsorption, and a large amount of energy is needed; the use of adsorption in combination with crystallization likewise requires a high expenditure of energy in crystallization.
Disclosure of Invention
The invention aims to provide a method for producing paraxylene and ethylbenzene from mixed C8 aromatic hydrocarbons, which reduces the energy consumption and the operation cost for separating the paraxylene and the ethylbenzene from the mixed C8 aromatic hydrocarbons.
In order to achieve the above object, the present invention provides a method for producing paraxylene and ethylbenzene from mixed C8 aromatic hydrocarbons, the method comprising the steps of:
carrying out first liquid phase adsorption separation on mixed C8 aromatic hydrocarbon (mixed C8A) to obtain a first extract rich in paraxylene and a first raffinate rich in ethylbenzene;
performing first rectification on the first extract to obtain a paraxylene product and a first extract residual solution;
performing second rectification on the first raffinate to obtain a mixture containing ethylbenzene, ortho-xylene and meta-xylene and a first raffinate residual solution;
performing second liquid phase adsorption separation on the mixture containing ethylbenzene, ortho-xylene and meta-xylene to obtain a second extract rich in ethylbenzene and a second raffinate poor in ethylbenzene;
performing third rectification on the second extract to obtain an ethylbenzene product and a second extract residual solution;
and performing fourth rectification on the second raffinate to obtain a mixture rich in ortho-xylene and meta-xylene and a second raffinate residual solution.
As will be understood by those skilled in the art, the first extract raffinate is a first extract rich in paraxylene, and is subjected to a first rectification to obtain a residue product after the paraxylene product is rectified; the first raffinate residual liquid is a residual product obtained by performing second rectification on the first raffinate rich in ethylbenzene to rectify a mixture containing ethylbenzene, ortho-xylene and meta-xylene; the residual liquid of the second extract liquid is a residual product obtained after the second extract liquid rich in ethylbenzene is subjected to third rectification to rectify an ethylbenzene product; and performing fourth rectification on the second raffinate to obtain a residual product rich in the mixture of the o-xylene and the m-xylene.
In one embodiment of the invention, the first liquid phase adsorptive separation and the second liquid phase adsorptive separation are both carried out in a simulated moving bed separation unit. The first liquid phase adsorptive separation is carried out in a first simulated moving bed separation unit. The number of beds of the first simulated moving bed separation unit can be 8-24. The second liquid phase adsorption separation is carried out in a second simulated moving bed separation unit. The number of beds of the second simulated moving bed separation device can be 8-32. The process of the simulated moving bed separation device has 4 basic inlet and outlet materials: raw materials, desorbent, extract and raffinate; 1-7 paths of flushing can be arranged, so that the high purity of the product is ensured, and the effective adsorption pore volume of the adsorbent is utilized to the maximum extent. Take four flushes as an example: the desorbent flushing is positioned between the desorbent and the extract, the material composition of the desorbent flushing is the same as that of the desorbent, and the desorbent flushing and the extract enter an adsorption bed layer at an interval of one bed layer; the extract is washed once and is positioned between the extract and the raw material, a bed layer is separated from the raw material, the composition of the used materials is the same as that of the extract, and the materials enter an adsorption bed layer; the extract liquid is washed for the second time and is positioned between the extract liquid and the raw material, two bed layers are separated from the extract liquid, the composition of the used materials is the same as that of the extract liquid, and the materials enter an adsorption bed layer; the feed flushing is located between the raw material and the raffinate, and is separated from the raffinate by two beds, the material composition of which is the same as that of the raw material, and the feed flushing enters the adsorption beds. For the second simulated moving bed separation device, one path of desorbent flushing, or one path of extract flushing, or one path of raw material flushing, or two paths of extract flushing and one path of desorbent flushing can be added.
Those skilled in the art can realize liquid phase adsorptive separation of paraxylene in mixed C8 aromatics by setting the adsorptive separation parameters of the first simulated moving bed separation unit, and those skilled in the art can also realize adsorptive separation of ethylbenzene in the first raffinate by setting the adsorptive separation parameters of the second simulated moving bed separation unit.
In one embodiment of the present invention, the adsorption temperature of the first liquid phase adsorption separation is 150 to 200 ℃, the adsorption pressure is 0.8 to 1.5MPaG, the desorption temperature is 150 to 200 ℃, and the desorption pressure is 0.8 to 1.5MPaG. The adsorption separation efficiency of the adsorption separation parameter on the paraxylene in the C8 aromatic hydrocarbon is higher.
In one embodiment of the present invention, the adsorption temperature of the second liquid phase adsorption separation is 140-200 ℃, the adsorption pressure is 0.8-1.7MPaG, the desorption temperature is 140-200 ℃, and the desorption pressure is 0.8-1.7MPaG. The adsorption separation efficiency of ethylbenzene in the first raffinate is higher by adopting the adsorption separation parameters.
The separation of paraxylene and ethylbenzene from mixed C8A can be realized by those skilled in the art according to the difference of adsorption strength of the adsorbent used for liquid phase adsorption separation on paraxylene and ethylbenzene and other C8A. Specifically, the first adsorbent used for the first liquid-phase adsorptive separation includes an X-type zeolite and/or a Y-type zeolite; the second adsorbent used for the second liquid phase adsorption separation comprises at least one of titanium silicalite molecular sieve, X-type zeolite and Y-type zeolite.
In the present invention, the first desorbent used in the first liquid phase adsorptive separation comprises para-diethylbenzene, toluene, naphthalene, para-difluorobenzene or an alkyl indene; preferably p-diethylbenzene or toluene; the first desorbent used in the first liquid phase adsorptive separation may be derived from two sources, one being an additional addition and the other being a product formed by the process of the present invention, with part or all of the first extract retentate and/or part or all of the first raffinate retentate being used as the first desorbent for the first liquid phase adsorptive separation.
In the present invention, the second desorbent used in the second liquid phase adsorptive separation includes toluene, p-diethylbenzene, m-diethylbenzene, o-diethylbenzene, toluene, naphthalene, p-difluorobenzene, or alkyl indane; preferably p-diethylbenzene, toluene or alkyl indane; the second desorbent used in the second liquid phase adsorptive separation may be derived from two sources, one being an additional addition and the other being a product formed by the process of the present invention, and part or all of the second extract retentate and/or part or all of the second raffinate retentate may be used as the second desorbent used in the second liquid phase adsorptive separation.
When the mixed C8 aromatic hydrocarbon is subjected to first liquid phase adsorption separation, the volume ratio of the first desorbent to the mixed C8 aromatic hydrocarbon is 0.5-5:1; more preferably, the volume ratio of the first desorbent to the mixed C8 aromatic hydrocarbon is from 0.9 to 1.5.
When the mixture containing ethylbenzene, ortho-xylene and meta-xylene is subjected to second liquid phase adsorption separation, the volume ratio of the second desorbent to the mixture containing ethylbenzene, ortho-xylene and meta-xylene is 0.5-5:1; more preferably, the volume ratio of the second desorbent to the mixture comprising ethylbenzene, ortho-xylene and meta-xylene is from 2 to 4:1.
In the present invention, the first rectification, the second rectification, the third rectification and the fourth rectification are each independently accomplished by one or more rectification columns. In general, the first rectification, the second rectification, the third rectification and the fourth rectification can be completed by one rectification tower.
In the invention, the extract liquid and the raffinate liquid obtained after the two liquid phases are adsorbed and separated are respectively rectified to obtain high-purity products. The first extract liquid rich in p-xylene is subjected to first rectification, the temperature at the top of the first rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG. The first extract rich in paraxylene is subjected to first rectification to obtain a paraxylene product and a first extract raffinate, the mass concentration of paraxylene in the paraxylene product is greater than or equal to 99.7%, and part or all of the first extract raffinate can be used as a first desorbent for first liquid-phase adsorption separation.
And performing second rectification on the first raffinate, wherein the temperature at the top of the second rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG. And carrying out second rectification on the first raffinate to obtain a mixture containing ethylbenzene, ortho-xylene and meta-xylene and a first raffinate, wherein part or all of the first raffinate can be used as a first desorbent. And carrying out second liquid phase adsorption separation on the mixture containing the ethylbenzene, the ortho-xylene and the meta-xylene to obtain a second extract rich in the ethylbenzene and a second raffinate poor in the ethylbenzene.
And performing third rectification on the second extract rich in the ethylbenzene, wherein the temperature at the top of the third rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG. And performing third rectification on the second extract rich in ethylbenzene to obtain an ethylbenzene product and a second extract residual solution, wherein the mass concentration of ethylbenzene in the ethylbenzene product is 95-99.9%, and part or all of the second extract residual solution can be used as a second desorbent for second liquid phase adsorption separation.
And performing fourth rectification on the second raffinate, wherein the temperature at the top of the fourth rectification tower can be 106-228 ℃, the pressure can be 0.01-0.6MPaG, so as to obtain a mixture rich in ortho-xylene and meta-xylene and a second raffinate residual liquid, and part or all of the second raffinate residual liquid can be used as a second desorbent.
In order to increase utilization of the feedstock, more of the C8 aromatics are converted to para-xylene, the process further comprising: mixing the mixture rich in ortho-xylene and meta-xylene with hydrogen to form an isomerization feed;
introducing the isomerization feed into an isomerization reactor, and carrying out isomerization reaction under the action of an isomerization catalyst to obtain an isomerization reaction product; and optionally, mixing the isomerization reaction product as a raw material with mixed C8 aromatic hydrocarbon, and then carrying out the first liquid phase adsorption separation.
Specifically, the molar ratio of the hydrogen to the mixture rich in ortho-xylene and meta-xylene is 0.5 to 3:1, preferably 0.8 to 1:1.
Specifically, the reaction temperature of the isomerization reaction is 360-380 ℃, and the reaction pressure is 0.5-1.2MPaG.
Specifically, the isomerization catalyst comprises: at least one of MOR type molecular sieve, ZSM-5 type molecular sieve, EU-1 type molecular sieve, mgAPSO-31 type molecular sieve and NU-87 type molecular sieve.
Specifically, the liquid hourly space velocity of the isomerization feed is 4-10h -1 。
The method for producing paraxylene and ethylbenzene by mixed C8 aromatic hydrocarbons comprises the steps of firstly carrying out liquid phase adsorption separation on the C8 aromatic hydrocarbons to obtain a first extract rich in paraxylene and a first raffinate rich in ethylbenzene; respectively rectifying the mixture to obtain a paraxylene product, a first extract raffinate, a mixture containing ethylbenzene, o-xylene and m-xylene, and a first raffinate; performing liquid phase adsorption separation on a mixture containing ethylbenzene, ortho-xylene and meta-xylene to obtain a second extract rich in ethylbenzene and a second raffinate poor in ethylbenzene; and respectively rectifying the ethylbenzene product and the second extract raffinate to obtain an ethylbenzene product, a second extract raffinate, a mixture rich in o-xylene and m-xylene and a second raffinate. Therefore, the method can separate the paraxylene, the ethylbenzene and the mixture rich in the ortho-xylene and the meta-xylene from the mixed C8 aromatic hydrocarbon through liquid phase adsorption separation and rectification, and reduces the energy consumption for separating the paraxylene, the ethylbenzene and the mixture rich in the ortho-xylene and the meta-xylene from the mixed C8 aromatic hydrocarbon.
The method combines the production of the ethylbenzene and the production process of the paraxylene by utilizing the characteristic that raffinate rich in the ethylbenzene can be obtained in the production process of the paraxylene, adopts the mixed C8 aromatic hydrocarbon to jointly produce the paraxylene and the ethylbenzene, can fully utilize ethylbenzene resources in the mixed xylene, and reduces the cost of raw materials; the mixture only containing m-xylene and o-xylene in the second raffinate returns to isomerization, the concentration of ethylbenzene in the isomerization feed is reduced, and the scale of an isomerization device is greatly reduced; meanwhile, the separation is carried out in the liquid phase, so that the production flow is simplified, and the purposes of saving the device investment and reducing the device energy consumption are achieved.
In the process of carrying out isomerization reaction on the mixture rich in o-xylene and m-xylene by the method for producing p-xylene and ethylbenzene by mixing C8 aromatic hydrocarbon, the temperature at the end of the reaction is greatly reduced under the condition of unchanged pressure and airspeed, the hydrogen-oil ratio is reduced, and the energy consumption of a device is saved; the isomerization activity of the p-xylene/xylene is improved, the loss of the xylene is greatly reduced, the reaction efficiency is effectively improved, and the material consumption of a device is reduced.
The method for producing p-xylene and ethylbenzene by using mixed C8 aromatic hydrocarbons can utilize ethylbenzene, m-xylene and o-xylene in the mixed C8 aromatic hydrocarbons to the maximum extent. On one hand, the complicated process for preparing the ethylbenzene from the benzene and the ethylene is removed, and on the other hand, the energy consumption for producing the ethylbenzene is reduced by adopting a liquid phase separation technology. In addition, the method optimizes the isomerization reaction conditions and saves the investment and energy consumption of the isomerization part.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
FIG. 1 shows a flow diagram of a process for producing para-xylene and ethylbenzene from mixed C8 aromatics as provided by the present invention.
FIG. 2 shows a flow diagram of another process for producing para-xylene and ethylbenzene from mixed C8 aromatics provided by the present invention.
The reference numerals in the drawings denote:
1. a first simulated moving bed separation unit;
2. a first rectification device;
4. a second rectification device;
7. a second simulated moving bed separation unit;
9. a third rectifying device;
11. a fourth rectifying unit;
13. an isomerization reactor;
x, mixed C8 aromatics;
3a, a first extract;
3b, first raffinate;
5a, a p-xylene product;
5b, first extract residual liquid;
6a, a mixture comprising ethylbenzene, ortho-xylene and meta-xylene;
6b, first raffinate residual liquid;
8a, a second extract;
8b, second raffinate;
10a, ethylbenzene production;
10b, second extract residual liquid;
12a, a mixture enriched in ortho-xylene and meta-xylene;
12b, second raffinate retentate.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
The invention provides a method for producing paraxylene and ethylbenzene by mixed C8 aromatic hydrocarbons. Referring to FIG. 1, FIG. 1 shows a flow diagram of a process for producing para-xylene and ethylbenzene from mixed C8 aromatics according to the present invention. As shown in FIG. 1, the method for producing paraxylene and ethylbenzene from mixed C8 aromatics comprises the following steps:
and carrying out first liquid phase adsorption separation on the mixed C8 aromatic hydrocarbon X to obtain a first extract liquid 3a rich in paraxylene and a first raffinate liquid 3b rich in ethylbenzene.
And carrying out first rectification on the first extract 3a to obtain a paraxylene product 5a and a first extract residual solution 5b.
The second rectification of the first raffinate 3b is carried out, obtaining a mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene and a first raffinate 6b.
A mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene is subjected to a second liquid phase adsorptive separation to obtain a second extract 8a rich in ethylbenzene and a second raffinate 8b depleted in ethylbenzene.
And performing third rectification on the second extract 8a to obtain an ethylbenzene product 10a and a second extract raffinate 10b.
The second raffinate 8b is subjected to a fourth rectification to produce an ortho-xylene and meta-xylene enriched mixture 12a and a second raffinate heel 12b.
The working principle of the method for producing paraxylene and ethylbenzene by C8 aromatic hydrocarbon provided by the invention is as follows:
with reference to fig. 1, first, performing liquid phase adsorption separation on the mixed C8 aromatic hydrocarbon X to obtain a first extract 3a rich in paraxylene and a first raffinate 3b rich in ethylbenzene; respectively rectifying the mixture to obtain a p-xylene product 5a, a first extract raffinate 5b, a mixture 6a containing ethylbenzene, o-xylene and m-xylene, and a first raffinate 6b; carrying out liquid phase adsorption separation on a mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene to obtain a second extract 8a rich in ethylbenzene and a second raffinate 8b poor in ethylbenzene; the ethylbenzene product 10a and the second raffinate 10b, as well as the mixture rich in ortho-xylene and meta-xylene 12a and the second raffinate 12b, are obtained by rectification respectively. Therefore, the method can separate the paraxylene, the ethylbenzene and the mixture rich in the ortho-xylene and the meta-xylene from the mixed C8 aromatic hydrocarbon through liquid phase adsorption separation and rectification, and reduces the energy consumption for separating the paraxylene, the ethylbenzene and the mixture rich in the ortho-xylene and the meta-xylene from the mixed C8 aromatic hydrocarbon.
In a preferred embodiment of the present invention, the first liquid phase adsorptive separation and the second liquid phase adsorptive separation are both carried out in a simulated moving bed separation unit. Referring to fig. 1, the first liquid-phase adsorptive separation is carried out in a first simulated moving bed separation apparatus 1; the second liquid-phase adsorptive separation is carried out in a second simulated moving bed separation apparatus 7.
Specifically, in the first simulated moving bed separation device 1, the adsorption temperature of the first liquid phase adsorption separation is 150 to 200 ℃, the adsorption pressure is 0.8 to 1.5MPaG, the desorption temperature is 150 to 200 ℃, and the desorption pressure is 0.8 to 1.5MPaG.
Specifically, in the second simulated moving bed separation device 7, the adsorption temperature of the second liquid phase adsorption separation is 140-200 ℃, the adsorption pressure is 0.8-1.7MPaG, the desorption temperature is 140-200 ℃, and the desorption pressure is 0.8-1.7MPaG.
Specifically, the first adsorbent used for the first liquid-phase adsorptive separation includes an X-type zeolite and/or a Y-type zeolite; the second adsorbent used for the second liquid phase adsorption separation comprises at least one of titanium silicalite molecular sieve, X-type zeolite and Y-type zeolite.
Specifically, the first desorbent used in the first liquid phase adsorptive separation comprises para-diethylbenzene, toluene, naphthalene, para-difluorobenzene, or an alkyl indene, etc.; preferably p-diethylbenzene or toluene.
Specifically, the second desorbent used in the second liquid phase adsorptive separation includes toluene, p-diethylbenzene, m-diethylbenzene, o-diethylbenzene, toluene, naphthalene, p-difluorobenzene, alkyl indane, or the like; preferably p-diethylbenzene, toluene or alkyl indane.
In the present invention, referring to fig. 2, a portion or all of the first extract retentate 5b and/or a portion or all of the first raffinate retentate 6b is used as the first desorbent for the first liquid phase adsorptive separation.
In the present invention, referring to fig. 2, a portion or all of the second extract retentate 10b and/or a portion or all of the second raffinate retentate 12b is used as the second desorbent for the second liquid phase adsorptive separation.
More specifically, the volume ratio of the first desorbent to the C8 aromatic hydrocarbon is from 0.5 to 5:1; preferably, the volume ratio of the first desorbent to the C8 aromatic hydrocarbon is from 0.9 to 1.5.
More specifically, the volume ratio of the second desorbent to the mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene is from 0.5 to 5:1; preferably, the volume ratio of the second desorbent to the mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene is from 2 to 4:1.
In the present invention, the first rectification, the second rectification, the third rectification and the fourth rectification are each independently accomplished by one or more rectification columns.
Referring to fig. 2, in the present invention, the first rectification of the first extract 3a may be performed in the first rectification device 2. The first rectification apparatus may comprise one or more than two rectification columns, typically two rectification columns. Performing first rectification on a first extract 3a rich in p-xylene by using a first rectification device 2, wherein the temperature at the top of the first rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG; to obtain a paraxylene product 5a and a first extract raffinate retentate 5b.
Referring to fig. 2, in the present invention, the second rectification of the first raffinate 3b may be performed in a second rectification apparatus 4. The second rectification apparatus may comprise one or more than two rectification columns, typically one rectification column. Performing second rectification on the first raffinate 3b by using a second rectification device 4, wherein the temperature at the top of the second rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG; a mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene and a first raffinate 6b are obtained.
Referring to fig. 2, in the present invention, the third rectification of the second extract 8a may be performed in a third rectification device 9. The third rectification apparatus may comprise one or more than two rectification columns, typically two rectification columns. Performing third rectification on the second extract liquid 8a rich in ethylbenzene by using a third rectification device 9, wherein the temperature at the top of the third rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG; yielding ethylbenzene product 10a and second draw raffinate 10b.
Referring to FIG. 2, in the present invention, the fourth rectification of the second raffinate 8b may be performed in a fourth rectification apparatus 11. The fourth rectification apparatus may comprise one or more than two rectification columns, typically one rectification column in series. And performing fourth rectification on the second raffinate 8b by using a fourth rectification device 11, wherein the temperature at the top of the fourth rectification tower can be 106-228 ℃, and the pressure can be 0.01-0.6MPaG, so as to obtain a mixture 12a rich in o-xylene and m-xylene and a second raffinate residual solution 12b.
In the invention, the mass concentration of the paraxylene in the paraxylene product obtained by the first rectification is more than 99.7%.
In the invention, the mass concentration of ethylbenzene in the ethylbenzene product obtained by the third rectification is 95-99.9%.
With continued reference to fig. 2, the method further comprises: mixing the ortho-xylene and meta-xylene enriched mixture 12a with hydrogen to form an isomerized feed; the isomerization feed is introduced into an isomerization reactor 13, and an isomerization reaction is carried out under the action of an isomerization catalyst to obtain an isomerization reaction product. Further, the isomerization reaction product is used as a raw material to be mixed with mixed C8 aromatic hydrocarbon, and then the first liquid phase adsorption separation is carried out.
More specifically, the molar ratio of the hydrogen to the ortho-xylene and meta-xylene enriched mixture 12a is from 0.5 to 3:1, preferably from 0.8 to 1:1, more preferably 1:1.
More specifically, the isomerization reaction is carried out at a reaction temperature of 360 to 380 ℃ and a reaction pressure of 0.5 to 1.2MPaG.
More specifically, the isomerization catalyst comprises: at least one of MOR type molecular sieve, ZSM-5 type molecular sieve, EU-1 type molecular sieve, mgAPSO-31 type molecular sieve and NU-87 type molecular sieve.
More specifically, the liquid hourly space velocity of the isomerization feed is 4 to 10h -1 。
Example 1
This example provides a process for producing para-xylene and ethylbenzene from mixed C8 aromatics. Referring to fig. 2, the method includes the following steps:
the mixed C8 aromatic hydrocarbon X is used as a raw material, the first simulated moving bed separation device 1 is used for carrying out first liquid phase adsorption separation on the mixed C8 aromatic hydrocarbon X, the adsorption temperature is 156 ℃, the adsorption pressure is 0.75MPaG, and a first extract liquid 3a rich in paraxylene and a first raffinate liquid 3b rich in ethylbenzene are separated.
And (3) performing first rectification on the first extract 3a by using a first rectification device 2, wherein the temperature at the top of the first rectification tower is 190, the pressure is 0.25PaG, a paraxylene product 5a is obtained, the mass concentration of paraxylene is more than or equal to 99.7% and less than 100%, and a first extract residual liquid 5b is recycled to the first simulated moving bed separation device 1 as a first desorbent for recycling.
And performing second rectification on the first raffinate 3b by using a second rectification device 4, wherein the temperature of the second rectification can be 200 ℃, and the pressure can be 0.35MPaG, so as to obtain a mixture 6a containing ethylbenzene, o-xylene and m-xylene and a first raffinate residual liquid 6b, and the first raffinate residual liquid 6b serving as a first desorbent is recycled to the first simulated moving bed separation device 1 for recycling.
And (3) carrying out second liquid-phase adsorption separation on the mixture 6a containing ethylbenzene, ortho-xylene and meta-xylene by using a second simulated moving bed separation device 7, wherein the adsorption pressure is 0.85MPaG, the adsorption temperature is 162 ℃, and a second extract liquid 8a rich in ethylbenzene and a second raffinate liquid 8b lean in ethylbenzene are obtained.
And performing third rectification on the second extract 8a by using a third rectification device 9, wherein the temperature at the top of the third rectification tower is 185, the pressure is 0.25PaG, an ethylbenzene product 10a and a second extract residual solution 10b are obtained, the mass concentration of ethylbenzene in the ethylbenzene product 10a is 99%, and the second extract residual solution 10b serving as a second desorbent is recycled to the second simulated moving bed separation device 7 for reuse.
And performing fourth rectification on the second raffinate 8b by using a fourth rectification device 11, wherein the temperature at the top of the fourth rectification tower is 192 ℃, the pressure is 0.35PaG, so as to obtain a mixture 12a rich in o-xylene and m-xylene and a second raffinate residual liquid 12b, and the second raffinate residual liquid 12b serving as a second desorbent is recycled to the second simulated moving bed separation device 7 for reuse.
Mixing the ortho-xylene and meta-xylene enriched mixture 12a with hydrogen in a molar ratio (hydrogen to oil) of 1:1 to form an isomerization feed; the isomerization feed is introduced into an isomerization reactor 13, an isomerization reaction is carried out under the action of a ZSM-5 type molecular sieve, the reaction temperature is 365 ℃, the reaction pressure is 0.5MPaG, an isomerization reaction product is obtained, and the isomerization reaction product is used as a raw material to be mixed with mixed C8 aromatic hydrocarbon and returned to the first simulated moving bed separation device 1. The composition of the feed/discharge in this example is shown in Table 1 in the state of material balance.
Table 1 example 1 composition of feed and discharge
| Composition of | Feed kg/h | Discharge kg/h |
| Ethylbenzene production | 18022 | 17392 |
| Para-xylene | 122679 | 504697 |
| Meta-xylene | 283022 | - |
| Ortho-xylene | 114277 | - |
| Others | 1396 | 17307 |
| Total up to | 539396 | 539396 |
The results of comparing the isomerization reaction conditions of the prior art ethylbenzene containing feed with the enriched ortho-xylene and meta-xylene mixture of this example are shown in Table 2.
TABLE 2 comparison of isomerization reaction conditions for a prior isomerization feed containing ethylbenzene and a mixture rich in ortho-xylene and meta-xylene
As can be seen from the examples, the method for producing p-xylene and ethylbenzene from mixed C8 aromatics according to the present invention can maximize the utilization of ethylbenzene, m-xylene and o-xylene in the mixed C8 aromatics. On one hand, the complex flow of preparing ethylbenzene from benzene and ethylene is avoided, and on the other hand, the energy consumption is saved by adopting a liquid phase separation technology. In addition, the method optimizes the isomerization reaction condition, saves the investment and reduces the energy consumption.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (12)
1. A process for producing para-xylene and ethylbenzene from mixed C8 aromatics, comprising the steps of:
carrying out first liquid phase adsorption separation on the mixed C8 aromatic hydrocarbon to obtain a first extract rich in paraxylene and a first raffinate rich in ethylbenzene;
performing first rectification on the first extract to obtain a paraxylene product and a first extract residual solution;
performing second rectification on the first raffinate to obtain a mixture containing ethylbenzene, o-xylene and m-xylene and a first raffinate residual solution;
performing second liquid phase adsorption separation on the mixture containing ethylbenzene, ortho-xylene and meta-xylene to obtain a second extract rich in ethylbenzene and a second raffinate poor in ethylbenzene;
performing third rectification on the second extract to obtain an ethylbenzene product and a second extract residual solution;
performing fourth rectification on the second raffinate to obtain a mixture rich in o-xylene and m-xylene and a second raffinate residual solution; mixing the mixture rich in ortho-xylene and meta-xylene with hydrogen to form an isomerization feed; introducing the isomerization feed into an isomerization reactor, and carrying out isomerization reaction under the action of an isomerization catalyst to obtain an isomerization reaction product; optionally, the isomerization reaction product is used as a raw material to be mixed with mixed C8 aromatic hydrocarbon and then the first liquid phase adsorption separation is carried out;
the first liquid phase adsorption separation and the second liquid phase adsorption separation are both carried out in a simulated moving bed separation device;
the second adsorbent used for the second liquid phase adsorption separation comprises at least one of a titanium silicalite molecular sieve, X-type zeolite and Y-type zeolite;
part or all of the second extract raffinate and/or part or all of the second raffinate are/is used as a second desorbent for the second liquid-phase adsorptive separation;
the second desorbent used in the second liquid phase adsorptive separation comprises toluene, p-diethylbenzene, m-diethylbenzene, o-diethylbenzene, naphthalene, p-difluorobenzene or alkyl indane.
2. The process according to claim 1, characterized in that the isomerization reaction is carried out at a reaction temperature of 360-380 ℃ and a reaction pressure of 0.5-1.2MPaG;
the isomerization catalyst comprises: at least one of MOR type molecular sieve, ZSM-5 type molecular sieve, EU-1 type molecular sieve, mgAPSO-31 type molecular sieve and NU-87 type molecular sieve; the liquid hourly space velocity of the isomerization feed is 4-10h -1 。
3. The process of claim 1, wherein the first liquid phase adsorptive separation has an adsorption temperature of 150 to 200 ℃ and an adsorption pressure of 0.8 to 1.5MPaG; the desorption temperature is 150-200 ℃, and the desorption pressure is 0.8-1.5MPaG;
the adsorption temperature of the second liquid phase adsorption separation is 140-200 ℃, and the adsorption pressure is 0.8-1.7MPaG; the desorption temperature is 140-200 ℃, and the desorption pressure is 0.8-1.7MPaG.
4. The method of claim 1, wherein the first adsorbent used for the first liquid phase adsorptive separation comprises an X-type zeolite and/or a Y-type zeolite.
5. The process of claim 1, wherein part or all of the first draw raffinate retentate and/or part or all of the first raffinate retentate acts as the first desorbent for the first liquid-phase adsorptive separation.
6. The process of claim 1, wherein the first desorbent used in the first liquid phase adsorptive separation comprises p-diethylbenzene, toluene, naphthalene, p-difluorobenzene, or an alkyl indane.
7. The method of claim 6, wherein the volume ratio of the first desorbent to the mixed C8 aromatic hydrocarbon is from 0.5 to 5:1.
8. The process of claim 7, wherein the volume ratio of the first desorbent to the mixed C8 aromatic hydrocarbon is from 0.9 to 1.5.
9. The process of claim 1, wherein the volume ratio of the second desorbent to the mixture comprising ethylbenzene, ortho-xylene, and meta-xylene is from 0.5 to 5:1.
10. The process of claim 9, wherein the volume ratio of the second desorbent to the mixture comprising ethylbenzene, ortho-xylene, and meta-xylene is from 2 to 4:1.
11. The method according to claim 1, characterized in that the first, second, third and fourth rectification are each independently accomplished by one or more rectification columns.
12. The method according to claim 1, wherein the mass concentration of paraxylene in the paraxylene product obtained by the first rectification is 99.7% or more;
the mass concentration of ethylbenzene in the ethylbenzene product obtained by the third rectification is 95-99.9%.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4313015A (en) * | 1980-02-07 | 1982-01-26 | Uop Inc. | Separation process |
| CN1552515A (en) * | 2003-05-30 | 2004-12-08 | 中国石油化工股份有限公司 | Paraxylene adsorbent and preparing method thereof |
| CN101125793A (en) * | 2007-09-21 | 2008-02-20 | 苏州久泰集团公司 | Process of preparing high-purity petroleum m-xylene |
| CN103373891A (en) * | 2012-04-26 | 2013-10-30 | 中国石油化工股份有限公司 | Method for producing p-xylene and ethylbenzene from C8 aromatic hydrocarbons by adsorption separation |
| CN104974002A (en) * | 2014-04-11 | 2015-10-14 | 中国石油化工股份有限公司 | Method of producing p-xylene through separation of C8 mixed aromatics |
-
2020
- 2020-01-08 CN CN202010019079.8A patent/CN113087585B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4313015A (en) * | 1980-02-07 | 1982-01-26 | Uop Inc. | Separation process |
| CN1552515A (en) * | 2003-05-30 | 2004-12-08 | 中国石油化工股份有限公司 | Paraxylene adsorbent and preparing method thereof |
| CN101125793A (en) * | 2007-09-21 | 2008-02-20 | 苏州久泰集团公司 | Process of preparing high-purity petroleum m-xylene |
| CN103373891A (en) * | 2012-04-26 | 2013-10-30 | 中国石油化工股份有限公司 | Method for producing p-xylene and ethylbenzene from C8 aromatic hydrocarbons by adsorption separation |
| CN104974002A (en) * | 2014-04-11 | 2015-10-14 | 中国石油化工股份有限公司 | Method of producing p-xylene through separation of C8 mixed aromatics |
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