Separation method of carbon octa-aromatic hydrocarbon isomer mixture

文档序号：1320376 发布日期：2020-07-14 浏览：38次中文

阅读说明：本技术 一种碳八芳烃同分异构体混合物的分离方法 (Separation method of carbon octa-aromatic hydrocarbon isomer mixture ) 是由邢华斌崔希利于 2020-04-02 设计创作，主要内容包括：本发明公开了一种碳八芳烃同分异构体混合物的分离方法,以孔径在<Image he="69" wi="200" file="DDA0002436526260000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的阴离子柱撑微孔材料为吸附剂,将碳八芳烃同分异构体混合物与吸附剂接触,实现碳八芳烃同分异构体混合物的选择性吸附分离；所述阴离子柱撑微孔材料为由金属离子M、无机阴离子A和有机配体L通过配位键形成的多孔材料,通式为[MAL2]n,其中n>4且为整数；所述金属离子M为Fe2+、Co2+、Ni2+或Cu2+；所述无机阴离子A为SiF62-、NbOF52-、TaF72-、ZrF62-、TiF62-、GeF62-、SO3CF3-或NbF6-；所述有机配体L选自如下结构：<Image he="263" wi="700" file="DDA0002436526260000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention discloses a separation method of a carbon octa-arene isomer mixture, which adopts the pore diameter The anion pillared microporous material is an adsorbent, the mixture of the carbon octaarene isomers is contacted with the adsorbent to realize the selective adsorption separation of the mixture of the carbon octaarene isomers, the anion pillared microporous material is a porous material formed by a metal ion M, an inorganic anion A and an organic ligand L through a coordination bond, and the general formula is [ MA L ] 2 ] n Wherein n is>4 and is an integer; the metal ion M is Fe 2+ 、Co 2+ 、Ni 2+ Or Cu 2+ (ii) a The inorganic anion A is SiF 6 2‑ 、NbOF 5 2‑ 、TaF 7 2‑ 、ZrF 6 2‑ 、TiF 6 2‑ 、GeF 6 2‑ 、SO 3 CF 3 ‑ Or NbF 6 ‑ The organic ligand L is selected from the following structures:)

1. A separation method of a C-eight aromatic hydrocarbon isomer mixture is characterized in that an anionic pillared microporous material is used as an adsorbent, and the C-eight aromatic hydrocarbon isomer mixture is contacted with the adsorbent to realize selective adsorption separation of the C-eight aromatic hydrocarbon isomer mixture;

the anion pillared microporous material is a porous material formed by metal ions M, inorganic anions A and organic ligands L through coordination bonds, and the general formula is [ MA L ]₂]_nWherein n is>4 and is an integer;

the metal ion M is Fe²⁺、Co²⁺、Ni²⁺Or Cu²⁺；

The inorganic anion A is SiF₆ ^2-、NbOF₅ ^2-、TaF₇ ^2-、ZrF₆ ^2-、TiF₆ ^2-、GeF₆ ^2-、SO₃CF₃ ^-Or NbF₆ ^-；

The organic ligand L is selected from the following structures:

2. the separation method according to claim 1, wherein the pore size of the anionic pillared microporous material is

3. The separation method according to claim 1, wherein the metal ion M is Ni²⁺Or Cu²⁺The inorganic anion A is NbOF₅ ^2-、SiF₆ ^2-Or TiF₆ ^2-And the organic ligand L is 4, 4' -bipyridine.

4. The separation process according to any one of claims 1 to 3, wherein the mixture of the isomers of the C-octaaromatic hydrocarbon is in a gaseous and/or liquid state, and the components comprise at least two of p-xylene, m-xylene, o-xylene and ethylbenzene.

5. The separation method according to claim 1, wherein the adsorbent is contacted with the mixture of the isomers of the C-octaaromatic hydrocarbon by any one of fixed bed adsorption and simulated moving bed adsorption.

6. The separation method according to claim 5, wherein the adsorption temperature is 20 to 250 ℃ and the adsorption pressure is 0.1 to 5 bar.

7. The separation method according to claim 5 or 6, wherein the contacting means is fixed bed adsorption, comprising in particular the steps of:

(1) introducing the carbon octaarene isomeride mixture into a fixed bed adsorption column, adsorbing the strongly adsorbed carbon octants on an adsorbent, and penetrating the specific carbon octants which are not adsorbed or have low adsorption quantity to obtain the specific carbon octants;

(2) after the penetration and adsorption of the specific carbon eight component are finished, desorbing the strongly adsorbed carbon eight component from the adsorbent in a way of pressure reduction desorption, temperature rise desorption, desorbent desorption or inert gas purging to obtain the strongly adsorbed carbon eight component.

8. The separation process according to claim 7, wherein the desorption temperature is 20 to 250 ℃.

9. The separation process of claim 7, wherein the specific carbon octant is para-xylene and has a mass percent purity greater than 99.9%.

10. The application of the anion pillared microporous material in selective adsorption separation of a C-eight aromatic hydrocarbon isomer mixture is characterized in that the anionThe pillared interlayer material is a porous material formed by metal ions M, inorganic anions A and organic ligands L through coordination bonds, and the general formula is [ MA L ]₂]_nWherein n is>4 and is an integer;

the metal ion M is Fe²⁺、Co²⁺、Ni²⁺Or Cu²⁺；

The inorganic anion A is SiF₆ ^2-、NbOF₅ ^2-、TaF₇ ^2-、ZrF₆ ^2-、TiF₆ ^2-、GeF₆ ^2-、SO₃CF₃ ^-Or NbF₆ ^-；

The organic ligand L is selected from the following structures:

Technical Field

The invention relates to the technical field of chemical engineering, in particular to a method for separating a carbon octaarene isomer mixture.

Background

Para-xylene (PX) is a basic organic chemical raw material, mainly used for synthesizing terephthalic acid (PTA), and PTA is a raw material for producing polyesters, especially polyethylene terephthalate (PET). With the global surge in polyester demand, the demand for PX is growing rapidly. In recent years, in 2017, the consumption of PX reaches 2385 ten thousand tons all the year around, the consumption is increased by 11.67%, the import accounts for 60%, and the consumption mainly comes from Japan and Korea.

The mixed carbon-eight aromatic hydrocarbon mainly comes from reactions such as steam cracking, catalytic reforming, toluene disproportionation and the like, and mainly comprises xylene isomers (PX, m-xylene (MX), o-xylene (OX)) and Ethylbenzene (EB). The separation of mixed carbon and octa-aromatics is the main process for the preparation of PX. Due to the physical and chemical properties of the components of the carbon-eight aromatic hydrocarbon mixture and similarity of the components, the density of each component is close to that of each component, the boiling point difference is small, for example, the boiling point difference between PX (138.35 ℃) and MX (139.0 ℃) is only 0.35 ℃, and the components are difficult to separate by using a traditional rectification method. At present, methods for separating PX mainly include Simulated Moving Bed (SMB) separation, crystallization, chemical complex extraction, adsorption-crystallization integrated separation, and the like. Among them, the simulated moving bed separation technique is the main method for separating PX, and was first reported in patent US 2985589A. Subsequently, patents such as US3040777A, US3214247A, and US3422848A disclose equipment and control systems in simulated moving bed adsorptive separation processes. The simulated moving bed process mainly comprises a Parex and MXSorbex process of UOP, wherein an adsorbent is a molecular sieve, PX can be separated and purified through the working procedures of adsorption, elution, eluent rectification and the like, and toluene is adopted as an eluent in the Parex process. Among them, US3686342A, US3707550A, US3997620A, US5159131A and the like disclose that the adsorbent used for adsorption separation of paraxylene is a barium-type or barium-potassium-type X or Y faujasite molecular sieve.

The simulated moving bed technology is an efficient separation technology, but has the problems of large equipment investment, easy loss, small treatment capacity and the like. In addition, the problems of low separation selectivity, small capacity and large desorption energy consumption of the adsorbent result in extremely high PX separation energy consumption and solvent consumption. Therefore, research and development of novel high-selectivity adsorbents and high-efficiency PX separation and purification technologies are needed as soon as possible.

In recent years, research finds that Metal-organic frameworks (MOFs) with specific pore structures and functional sites can selectively adsorb and separate C8 arene mixtures, patent US8704031B2 reports Al-MI L-53 and Zn-MOF-5 adsorbents which selectively and preferentially adsorb PX, and a simulated moving bed process is adopted to separate xylene mixtures by taking p-diethylbenzene, toluene and the like as eluent, patent US20180215684A1 reports MI L-125-NH 2, MI L-140B and MOF-48 adsorbents which selectively and preferentially adsorb PX, patent US20170189890A1 reports C8 arene mixtures separated by cyclodextrin MOF (CD-MOF) adsorbents, but with the development of xylene synthesis technology through disproportionation of toluene, the yield of mixed products is as high as 80% -95%, the adsorbents which preferentially adsorb MX need to undergo multiple adsorption-desorption cycles to obtain higher purity PX products, and the process is high in energy consumption, the adsorbents which have poor energy consumption and the adsorbents are capable of obtaining high purity MX, and the adsorbents which have low capacity of selectively adsorbing MX, and the adsorbents which have the problems of reducing the capacity of adsorbing MX, such as high purity of PX, PX-84, and the adsorbent separation of the adsorbents which have been reported in the prior art.

Disclosure of Invention

Aiming at the defects in the field, the invention provides a separation method of a C-eight aromatic hydrocarbon isomer mixture, which takes an anionic pillared microporous material as an adsorbent and can realize selective and efficient adsorption separation of the C-eight aromatic hydrocarbon isomer mixture.

A separation method of a C-eight aromatic hydrocarbon isomer mixture takes an anion pillared microporous material as an adsorbent, and the C-eight aromatic hydrocarbon isomer mixture is contacted with the adsorbent to realize selective adsorption separation of the C-eight aromatic hydrocarbon isomer mixture;

the anion pillared microporous material is prepared from metal ions M and inorganicThe anion A and the organic ligand L form a porous material through coordination bonds, and the general formula is [ MA L ]₂]_nWherein n is>4；

The metal ion M is Fe²⁺、Co²⁺、Ni²⁺Or Cu²⁺；

The inorganic anion A is SiF₆ ^2-、NbOF₅ ^2-、TaF₇ ^2-、ZrF₆ ^2-、TiF₆ ^2-、GeF₆ ^2-、SO₃CF₃ ^-Or NbF₆ ^-；

The organic ligand L is selected from the following structures:

the anion pillared microporous material used by the invention is a porous crystal material prepared from metal ions, inorganic anions and organic ligands, has high specific surface area and high porosity, and the pore structure and the inorganic anion functional site of the anion pillared microporous material can realize the response to different xylene isomer molecules, further carry out structure modulation and identify the difference of the carbon-octaarene in shape, thereby obtaining very high separation selectivity, for example, the anion pillared microporous material with the academic name ZU-61 (the metal ions are Ni)²⁺The inorganic anion being NbOF₅ ^2-The organic ligand is 4, 4' -bipyridine) has the adsorption capacity of the meta-xylene up to 3.4mmol/g, and the separation selectivity of the meta-xylene/para-xylene is up to 2.9, thus showing good application prospect in the separation of carbon eight carbon hydrocarbons.

The anion pillared microporous material prepared from the organic ligand, the metal ions and the inorganic anions has the following structure:

the pore diameter of the anion pillared microporous material is

The anion pillared microporous material can be prepared by adopting the prior art, such as a solid phase grinding method, an interface slow diffusion method, a solvothermal method, a room temperature coprecipitation method and the like.

Preferably, the metal ion M is Ni²⁺Or Cu²⁺The inorganic anion A is NbOF₅ ^2-、SiF₆ ^2-Or TiF₆ ^2-And the organic ligand L is 4, 4' -bipyridine.

Preferably, the carbon eight aromatic hydrocarbon isomer mixture is in a gas state and/or a liquid state, and the components comprise at least two of paraxylene, metaxylene, orthoxylene and ethylbenzene.

The anion pillared microporous material hasThe pore channel structure with the size contains inorganic anions which are highly orderly arranged, and the high-efficiency separation of the mixture of o-xylene, m-xylene, p-xylene and ethylbenzene can be realized.

More preferably, the organic ligand L in the anion pillared microporous material is 4,4 '-bipyridine, and the pore diameter of the material formed by the 4, 4' -bipyridine, the metal ion M and the inorganic anion A is as followsThe adsorption strength sequence of the carbon eight aromatic hydrocarbon isomer mixture is as follows: o-xylene, m-xylene, ethylbenzene, p-xylene. The PX adsorption is weaker, so that the separation and purification of the PX are realized, and the paraxylene with the purity of more than 99 percent is obtained.

The separation method is suitable for separating the carbon octaarene isomer mixture with different contents and compositions, the mass percentage concentration of p-xylene, m-xylene, o-xylene and ethylbenzene in the mixture can be between 1 and 99 percent, the carbon octaarene isomer mixture can be a mixture of two or more of the aromatic hydrocarbons, and the mixture state can be gaseous or liquid. The anion pillared microporous material has good stability, and the mixture of the isomers of the carbon octaarene can contain other impurity components, such as one or more of water, methane, nitrogen, carbon dioxide, hydrogen, benzene, C7, C9 and the like.

In the separation method of the invention, the anion pillared microporous material is not limited in shape and can be amorphous particles or spherical and cylindrical particles after molding.

In the separation method, the contact mode of the adsorbent and the carbon octaarene isomer mixture can be any one of fixed bed adsorption and simulated moving bed adsorption. The mixture of the isomers of the C-octa-aromatic hydrocarbon can be in a liquid form or a gas form, wherein the adsorption operation can be temperature swing adsorption or pressure swing adsorption.

The adsorption temperature is preferably 20 to 250 ℃, and more preferably 40 to 160 ℃.

The adsorption pressure is preferably 0.1 to 5bar, and more preferably 0.2 to 2 bar.

Preferably, the contact mode is fixed bed adsorption, and the method specifically comprises the following steps:

The desorption temperature is preferably 20 to 250 ℃, and more preferably 50 to 150 ℃.

The highest purity of the p-xylene, the m-xylene, the o-xylene and the ethylbenzene obtained by the separation method is more than 99 percent and can reach 99.999 percent.

Preferably, the specific carbon eight component is paraxylene, and the mass percent purity is more than 99.9%.

The invention also provides application of the anion pillared microporous material in selective adsorption separation of a carbon-eight aromatic hydrocarbon isomer mixture. Preferably, the carbon eight aromatic hydrocarbon isomer mixture is in a gas state and/or a liquid state, and the components comprise at least two of paraxylene, metaxylene, orthoxylene and ethylbenzene.

Compared with the prior art, the invention has the main advantages that:

(1) the invention provides a method for preparing a porous material with an apertureCompared with the traditional adsorbent, the anion pillared microporous material has the advantages of adjustable pore structure, large pore volume, adjustable action force with adsorbate molecules and the like, and the special pore structure can realize shape-selective high-efficiency separation of the carbon octaarene, for example, the invention discovers that the separation selectivity of the anion pillared microporous material with the academic name of ZU-61 on m-xylene/p-xylene is as high as 2.9, and the selective separation of each component of the carbon octaarene isomerides with different sizes and shapes is realized;

(2) the anion pillared microporous material has higher porosity and high-density functional sites and has higher adsorption capacity on the carbon octaarene isomer, for example, the invention finds that the anion pillared microporous material with the academic name of ZU-61 has the adsorption capacity on m-xylene up to 3.4mmol/g, and the consumption of an adsorbent is saved.

(3) The adsorption strength of the anionic pillared microporous material to the carbon-octaarene mixture is sequentially as follows: o-xylene, m-xylene, ethylbenzene, p-xylene. For weak PX adsorption, high-purity paraxylene (the purity is higher than 99.9 percent and the mass percent) can be obtained by a one-step single-column method, which is superior to a simulated moving bed process based on a conventional molecular sieve.

(4) The method can obtain high-purity p-xylene, m-xylene, o-xylene and ethylbenzene products according to industrial requirements, and the highest purity can reach 99.999 percent (mass percentage);

(5) the anion pillared microporous material has the advantages of simple synthesis method, easy amplification preparation, low cost and the like. In addition, the adsorbent is easy to regenerate, can be repeatedly used, has low energy consumption and low cost, and is suitable for industrialization.

Drawings

FIG. 1 is a graph showing adsorption isotherms of p-xylene, m-xylene, o-xylene, and ethylbenzene at 333K for the anion pillared microporous material obtained in example 1;

FIG. 2 is a graph of penetration data obtained in example 2;

FIG. 3 is an adsorption isotherm diagram of p-xylene, m-xylene, o-xylene, and ethylbenzene for 333K of the anion pillared microporous material obtained in example 4;

FIG. 4 is a graph of penetration data obtained in example 5;

FIG. 5 is a graph of penetration data obtained in example 6;

FIG. 6 is a graph of penetration data obtained in example 7;

FIG. 7 is a graph of the regeneration data for adsorbent ZU-61 from the breakthrough experiment obtained in example 8;

FIG. 8 is a graph of the cyclic breakthrough data obtained in example 9;

FIG. 9 is a crystal structure diagram of the anion-pillared microporous material obtained in example 4 after adsorbing paraxylene.

Detailed Description

The invention is further described with reference to the following drawings and specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are conducted under conditions not specified, usually according to conventional conditions, or according to conditions recommended by the manufacturer.

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Separation method of carbon octa-aromatic hydrocarbon isomer mixture

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