Alkylbenzene-containing desorbent and its use in the adsorption and separation of meta-aromatic hydrocarbons

Abstract

The present invention relates to an alkylbenzene-containing desorbent and its use in the adsorption and separation of meta-aromatic hydrocarbons. The desorbent contains, or consists of, 20 to 100% by weight of an alkylbenzene compound of the general formula (I) and 0 to 80% by weight of a C5 to C14 saturated aliphatic hydrocarbon, where R1, R2, and R3 are independently selected from C1 to C4 chain alkyl groups, and R4, R5, and R6 are independently selected from hydrogen, C1 to C4 saturated hydrocarbyl, C1 to C4 alkoxy, and halogen. The desorbent is available from a wide range of sources, has an adsorption selectivity that corresponds well to the target product, and is beneficial for improving the yield and purity of the product. 【Chemical 1】 JPEG2025522041000014.jpg46169

Description

Detailed Description of the Invention

[0001] 〔Technical Field〕 This application relates to the separation and purification of meta-aromatic hydrocarbons, particularly to desorbents containing alkylbenzenes and their use in the adsorption separation of meta-aromatic hydrocarbons.

[0002] 〔Background Art〕 m-Xylene (MX) is an important basic organic chemical raw material and is widely used in many fields such as synthetic resins, pesticides, pharmaceuticals, paints, and dyes. High-purity m-xylene is usually obtained by separating mixed C8 aromatic hydrocarbons containing ethylbenzene, p-xylene, m-xylene, and o-xylene. Since the boiling points of the four C8 aromatic isomers are similar, it is difficult to separate them by using conventional distillation processes. Therefore, processes for separating m-xylene mainly include sulfonation hydrolysis, complexation separation, extractive distillation, and adsorption separation. Here, the adsorption separation method has the advantages of being environmentally friendly, pollution-free, non-corrosive, low equipment cost, high product purity and yield, and long adsorbent life. The adsorption separation method is the main development direction of m-xylene separation technology.

[0003] CN101745364A discloses an adsorbent for adsorbing and separating m-xylene and its preparation method. The adsorbent includes a Y zeolite exchanged with a Group IA metal ion and a copper or silver ion, and a binder, and toluene is used as the desorbent, with a fast mass transfer rate and a small usage amount.

[0004] CN101772478A discloses a method for separating m-xylene with a purity of at least 99% by weight by using simulated moving bed separation adsorption. The number of moving bed layers may be configured to be 12, 13, or 15, and the desorbent is toluene or a mixture of toluene and tetralin.

[0005] CN1939883A discloses a method for separating m - xylene by using a forging site type zeolite adsorbent. The method uses tetralin and its alkylated derivatives as desorbents, thereby reducing the cost of recovering and reusing the desorbent.

[0006] CN1379007A discloses a method for co - producing p - xylene and m - xylene, including two - stage separation. The method uses two separation steps. The two separation steps respectively use barium - exchanged X zeolite and potassium - exchanged Y zeolite as adsorbent components, p - diethylbenzene or p - difluorobenzene (the first separation step), and toluene, indane, or p - toluene as adsorbents to produce qualified paraxylene and metaxylene.

[0007] US5900523A discloses that using sodium - exchanged Y zeolite as the active component of the adsorbent and indane as the desorbent can enable the recovery of m - xylene in a single extraction raffinate without the need for an expensive fractionation process to remove o - xylene.

[0008] However, when toluene is used as the desorbent, its mass fraction in the extract and raffinate is 80% - 90%. The heat load required for its separation is high and the energy consumption is large. Toluene is a limited source with a low content and is difficult to obtain. When aromatic hydrocarbons (such as indane or tetralin) and their derivatives, which have a large difference in adsorption selectivity with the target product, are used as desorbents for separation, the consumption of materials and energy is large, the operating cost is high, and the yield of the target product is low.

[0009] Therefore, it is necessary to find a desorbent that has a boiling point significantly different from that of the target product, a wide range of feed sources, low cost, can improve the separation effect of the target product, and as a result, effectively reduce the production cost and improve the economic benefits of the device.

[0010] 〔Summary of the Invention〕 The object of the present application is an alkylbenzene-containing desorbent and its use in the adsorption separation of one or more meta-aromatic hydrocarbons, wherein the desorbent can effectively achieve the desorption of the target product from the adsorbent, and its boiling point is significantly different from that of the target product, thereby facilitating the separation of the target product by distillation for subsequent recycling and reuse. The present application provides a desorbent and its use.

[0011] In order to achieve the above object, in one aspect, the present application is for the use of a liquid material containing 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5-C14 saturated aliphatic hydrocarbon as a desorbent for the adsorption separation of one or more meta-aromatic hydrocarbons,

[0012]

Chemical formula

[0013] R1, R2, and R3 may be the same or different and are independently selected from C 1-4 alkyl groups, R4, R5, and R6 may be the same or different and are independently selected from hydrogen, C 1-4 saturated hydrocarbon groups, C 1-4 alkoxy groups, and halogens, and provides the use.

[0014] In another aspect, the present application is a method for separating one or more meta-aromatic hydrocarbons from a mixed aromatic hydrocarbon feedstock containing the one or more meta-aromatic hydrocarbons and their isomers, 1) Contacting the mixed aromatic hydrocarbon feedstock with an adsorbent to adsorb the one or more meta - aromatic hydrocarbons, and obtaining an adsorbent on which the one or more meta - aromatic hydrocarbons are adsorbed and a raffinate containing components that were not adsorbed; 2) Contacting the adsorbent on which the one or more meta - aromatic hydrocarbons were adsorbed, obtained in step 1), with a desorbent to desorb the one or more meta - aromatic hydrocarbons, and obtaining an extract containing the one or more meta - aromatic hydrocarbons and the desorbent; 3) Subjecting the extract obtained in step 2) to rectification separation to obtain the one or more meta - aromatic hydrocarbons and the desorbent; comprising Based on the total amount of the desorbent, the desorbent comprises, or consists of, 20 - 100% by weight of the alkylbenzene compound of the above general formula (I) and 0 - 80% by weight of a C5 - C14 saturated aliphatic hydrocarbon, and provides a method.

[0015] In a third aspect, the present application provides a kit of an adsorption - desorption agent comprising a solid adsorbent and a liquid desorbent, wherein the solid adsorbent contains at least 90% by weight of Y - type molecular sieve as an active ingredient, and the Y - type molecular sieve has a molar ratio of silicon oxide to aluminum oxide of 4.0 - 6.0, and the liquid desorbent contains, or consists of, 20 - 100% by weight of an alkylbenzene compound having the above general formula (I) and 0 - 80% by weight of a C5 - C14 saturated aliphatic hydrocarbon, and provides a kit.

[0016] The alkylbenzene-containing desorbent of the present application has a wide range of sources. Compared with toluene desorbent, the alkylbenzene-containing desorbent has an adsorption selectivity similar to that of one or more meta-aromatic hydrocarbons, and can effectively improve the yield of the target meta-aromatic product. The boiling point of the alkylbenzene-containing desorbent is extremely different from that of the target product, and is useful for subsequent separation from the target product by distillation for recycling and reuse. For example, when the desorbent is used for the separation of m-xylene, its boiling point is significantly higher than the boiling point of C8 aromatic hydrocarbons (for example, it can exceed 30 °C), which is useful for its recycling and reuse after recovery from the bottom of the column by distillation treatment. Currently, in an apparatus using a desorbent having a low boiling point such as toluene, it significantly reduces the energy consumption required for distillation of a large amount of desorbent having a low boiling point to the top of the column for recovery, and effectively saves production costs. Utilizing the desorbent of the present application to separate one or more meta-aromatic hydrocarbons from the mixed aromatic hydrocarbon feedstock by adsorption-desorption separation has strong adaptability to the feedstock, and can accurately control the process parameters throughout the separation operation process, and efficiently obtain meta-aromatic products with high purity and yield. The utilization is environmentally friendly and can significantly improve the economic benefits of the comprehensive utilization of C9+ heavy aromatics.

[0017] Other features and advantages of the present application will be described in detail in the following sections of specific embodiments.

[0018] 〔Brief Description of the Drawings〕 The drawings are used to provide a further understanding of the present application and constitute a part of this specification. Together with the following specific embodiments, the drawings are used to explain the present application, but do not constitute a limitation to the present application. In the drawings, FIG. 1 is an X-ray diffraction spectrum of the molecular sieve of Adsorbent Preparation Example 1; FIG. 2 is a pulse spectrum diagram of Example 1; FIG. 3 is a pulse spectrum diagram of Example 6; FIG. 4 is a pulse spectrum diagram of Example 9; Figure 5 is the pulse spectrum diagram of Example 10; Figure 6 is the pulse spectrum diagram of Comparative Example 1; Figure 7 is the pulse spectrum diagram of Comparative Example 2; Figure 8 is the pulse spectrum diagram of Comparative Example 3; and, Figure 9 is the schematic diagram of the simulated moving bed adsorption separation of the present application.

[0019] [Detailed Description of the Invention] Specific embodiments of the present application are described in detail below in conjunction with the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0020] The word "exemplary" exclusively used herein means "serving as an example, embodiment, or illustration". It should not be construed that any embodiment described as "exemplary" herein is necessarily preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0021] It should be understood that any specific numerical value (including the endpoints of the numerical range) disclosed herein is not limited to the exact value of that numerical value, but also encompasses values close to the exact value, such as all possible values within ±5% of the exact value. In addition, for the disclosed numerical range, the values of the endpoints of the range, the values of the endpoints and the specific points within the range, and the values of each specific point can be arbitrarily combined to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed herein.

[0022] Unless otherwise indicated, the terms used in this specification have the same meaning as commonly understood by those skilled in the art. If a term is defined in this specification and its definition differs from the meaning commonly understood in the art, the definition in this specification shall prevail.

[0023] In this application, the term "meta-aromatic hydrocarbon" for one or more refers to one or more "meta-substituted aromatic hydrocarbons" and refers to an aromatic compound having only two substituents on the aromatic ring. One of the substituents is in the meta-position relative to the other substituent. According to this application, the substituents on the meta-aromatic hydrocarbon do not contain Group VIA heteroatoms and Group VIIA heteroatoms, and for example, may include, but are not limited to, hydrocarbon groups, amine groups, etc., preferably hydrocarbon groups. More preferably, the meta-aromatic hydrocarbon is a meta-alkyl aromatic hydrocarbon, that is, a meta-aromatic hydrocarbon in which both substituents are alkyl groups. Particularly preferably, the meta-aromatic hydrocarbon is a C8-C12 meta-aromatic hydrocarbon, more preferably a C8-C12 meta-alkyl aromatic hydrocarbon such as m-xylene or 2,7-dimethylnaphthalene.

[0024] In this application, the term "saturated aliphatic hydrocarbon" has the meaning commonly understood in the art, including paraffin and cycloparaffin.

[0025] In this application, the term "paraffin" has the meaning commonly understood in the art, including linear paraffin (also called linear alkane) and isoparaffin (also called branched-chain alkane).

[0026] In this application, the term "saturated hydrocarbon group" has the meaning commonly understood in the art, including chain alkyl groups and cycloalkyl groups.

[0027] In this application, the term "alkyl group" has the meaning generally understood in the art, including straight-chain alkyl groups and branched-chain alkyl groups.

[0028] In this application, the term "C8" refers to having 8 carbon atoms, and the term "C8 aromatic hydrocarbon" refers to an aromatic hydrocarbon having 8 carbon atoms.

[0029] In this application, the term "C9" refers to having 9 carbon atoms, and the term "C9+ aromatic hydrocarbon" refers to an aromatic hydrocarbon having more than 9 carbon atoms, which is also referred to herein as "heavy aromatic hydrocarbon".

[0030] In this application, unless otherwise indicated, all pressures given are gauge pressures.

[0031] In this application, except as specifically described, any matter or article not mentioned is directly applicable, without any modification, to what is known in the art. Further, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solution or idea formed thereby shall be regarded as part of the original disclosure or original record of this application, and shall not be regarded as new content not disclosed or not expected herein, unless those skilled in the art consider such combination to be clearly unreasonable.

[0032] All patents and non-patent documents cited herein, including but not limited to textbooks and magazine articles, are hereby incorporated by reference in their entirety.

[0033] In the adsorption system, the metal ions in the molecular sieve crystal of the active component of the adsorbent are located above the aromatic ring of the meta-aromatic hydrocarbon and are biased towards the side having the substituent of the aromatic ring. Therefore, the region of the aromatic ring having a stronger positive electrostatic potential is biased towards the side of the aromatic ring, and the positive extreme value is located on one side of the aromatic ring. The two substituents of the meta-aromatic hydrocarbon are located on one side, and the formed angle is about 120 degrees. The negative electrostatic potential of the aromatic ring is distributed on one side of the aromatic ring, with good dispersibility, and the negative extreme value site is not located relatively centrally. Therefore, the region on one side of the aromatic ring is the position where the electrostatic attraction between the adsorbent and the adsorbate is the strongest. The adsorbent can preferentially adsorb the meta-aromatic hydrocarbon compared to other impurities. When other impurities are removed from this system, the target component needs to be desorbed from the adsorbent in order to produce a high-purity component for processing and utilization. Whether it is possible to perform efficient, high cycle rate, and high-purity desorption at this time mainly depends on the characteristics of the desorbent that needs to have a certain interaction with the adsorbent and needs to interact with the adsorbent to a certain extent. This interaction force should not be too strong or too weak. If the interaction force is too strong, the target component will be rapidly desorbed and cannot be separated from other impurities. As a result, it cannot be effectively separated from other impurities, and the purity of the product cannot be guaranteed. If the interaction force is too weak, the desorption process is very slow, the consumption is very large, the timeliness and economy are too poor, it is difficult for the target component to be desorbed, it occupies the effective pore volume of the adsorbent, and affects the volume to be processed next. At the same time, the negative electrostatic potential distribution area of the desorbent must coincide with the positive electrostatic potential distribution area of the metal ions, and the interaction area of the target component must coincide with the interaction area of the impurity molecules. Only when the interaction between the desorbent and the adsorbent and the target component is appropriate can the target component be replaced from the adsorbent, and the adsorption and desorption processes can be rapidly and efficiently repeated to produce a high-purity product.Therefore, finding a desorbent having a suitable negative electrostatic potential distribution region and a suitable interaction between the adsorbent and the adsorbed substance can improve the adsorption separation effect. In addition, in the adsorbent-desorbent system, there are intermolecular interactions between the target product and other impurity components and the desorbent molecules, such as dispersion force, induction force, and mutual repulsive force. The intermolecular interaction affects the diffusion coefficient of each component molecule inside and between the adsorbent crystals, thereby affecting the preferential adsorption selectivity of each component in this adsorption-desorption system. Therefore, different feedstock compositions and different adsorption-desorption systems produce different adsorption effects.

[0034] As described above, in the first aspect, the present application provides the use of one or more meta-aromatic hydrocarbons in a liquid material, which comprises or consists of 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5-C14 saturated aliphatic hydrocarbon, as a desorbent for the adsorption separation of one or more meta-aromatic hydrocarbons.

[0035]

Chemical formula

[0036] According to the present application, in the general formula (I), R1, R2, and R3 may be the same or different and are independently selected from C alkyl groups including various isomers such as methyl, ethyl, propyl, and butyl. 1-4 selected independently from preferably, at least one of R1, R2, and R3 is methyl. more preferably, at least two of them are methyl. even more preferably, all of them are methyl.

[0037] According to the present application, in the general formula (I), R4, R5, and R6 may be the same or different and are independently selected from hydrogen, C 1-4 saturated hydrocarbon group, C 1-4 alkoxy group, and halogen, said C1-4 Saturated hydrocarbon groups include methyl, ethyl, propyl, butyl, isopropyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, and their various isomers, preferably including methyl, but not limited thereto, The C 1-4 Alkoxy groups include methoxy, ethoxy, propoxy, butoxy, cyclopropyloxy, cyclobutyloxy, and their various isomers, but are not limited thereto, The halogen includes fluorine, chlorine, and bromine, but is not limited thereto, Preferably, at least one of R4, R5, and R6 is hydrogen or a C 1-4 saturated hydrocarbon group. For example, R4 or R6 is a C 1-4 saturated hydrocarbon group, More preferably, at least two of them are independently hydrogen or a C 1-4 saturated hydrocarbon group. For example, both R4 and R6 are C 1-4 saturated hydrocarbon groups, Even more preferably, all three are independently hydrogen or a C 1-4 saturated hydrocarbon group, Particularly preferably, all three are hydrogen.

[0038] In a preferred embodiment, in formula (I), at least one of R1, R2, and R3 is methyl, and R4, R5, and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group.

[0039] In a more preferred embodiment, in formula (I), at least two of R1, R2, and R3 are methyl, and R4, R5, and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group, and at least one of them is hydrogen.

[0040] In a more preferred embodiment, in formula (I), at least two of R1, R2, and R3 are methyl, R5 and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group, and at least two of them are hydrogen, preferably all three are hydrogen.

[0041] According to the present application, the liquid material as the desorbent may be a C9+ heavy aromatic hydrocarbon having a specific structure, a C9+ heavy aromatic hydrocarbon derivative, or a mixture thereof with an alkane. Preferably, the C9+ heavy aromatic hydrocarbon is selected from one or more of 1,2,3-trisubstituted C9+ alkylbenzene or its derivative, 1,2,3,4-tetrasubstituted C9+ alkylbenzene or its derivative, 1,2,3,4,5-pentasubstituted C9+ alkylbenzene or its derivative. In a particularly preferred embodiment, the alkylbenzene compound of formula (I) is selected from 1,2,3-trimethylbenzene (also referred to herein as tritoluene), 1,2,3,4-tetramethylbenzene (also referred to herein as tetratoluene), 1,2,3,4,5-pentamethylbenzene (also referred to herein as pentatoluene), and 3-ethyl-o-xylene, more preferably 1,2,3-trimethylbenzene or 1,2,3,4-tetramethylbenzene.

[0042] In recent years, with the gradual approval of the operation of large-scale integrated naphtha reforming, ethylene, and combined units of aromatics in Japan, the production of heavy aromatics has also been increasing. Here, the mass fraction of C9+ heavy aromatics in the catalytic reforming reaction product can usually reach 20% - 50%. Since the content of heteroatom components and olefins is low and the stability is good, C9+ heavy aromatics are high-quality raw materials for further processing and utilization. The mass fraction of trimethylbenzene in the reformed C9+ heavy aromatics is 15% - 30%, and the mass fraction of tetramethylbenzene is 3% - 8%. Currently, pseudocumene and mesitylene in this part of trimethylbenzene and tetramethylbenzene are separated by a mature industrial production process and used to produce partial anhydrides and trimesic acid. On the other hand, the utilization of tritoluene and tetratoluene is relatively insufficient, and most of them are sold as high-boiling aromatic solvent oils with low added value. This application utilizes C9+ heavy aromatic hydrocarbons, such as 1,2,3-trimethylbenzene, as desorbents for separating one or more meta-aromatic hydrocarbons. This not only achieves the high-value utilization of C9+ heavy aromatic hydrocarbon resources but also helps to reduce the energy and material consumption of the meta-aromatic hydrocarbon adsorption separation device. This not only brings great economic benefits to production enterprises but also helps enterprises save energy and reduce consumption.

[0043] In a preferred embodiment, the adsorption separation includes a step of separating a meta-aromatic hydrocarbon from a mixed aromatic hydrocarbon feedstock containing the meta-aromatic hydrocarbon and at least one isomer thereof by adsorption and desorption.

[0044] In a more preferred embodiment, the meta-aromatic hydrocarbon is a C8 - C12 meta-aromatic hydrocarbon, more preferably a C8 - C12 meta-alkyl aromatic hydrocarbon, such as m-xylene or 2,7-dimethylnaphthalene.

[0045] In yet another more preferred embodiment, The meta-aromatic hydrocarbon is m-xylene, The mixed aromatic hydrocarbon feedstock is m-xylene and at least one other C8 aromatic hydrocarbon selected from p-xylene, o-xylene, and ethylbenzene, and is a mixed C8 aromatic hydrocarbon feedstock containing the same. More preferably, the mixed C8 aromatic hydrocarbon feedstock contains 5 to 95% by weight of m-xylene. Particularly preferably, the mixed aromatic hydrocarbon feedstock contains 5 to 94% by weight of m-xylene and 6 to 95% by weight of p-xylene, more preferably 5 to 90% by weight of m-xylene and 10 to 95% by weight of p-xylene. For example, the content of xylene in the mixed aromatic hydrocarbon feedstock may be 10 to 90% by weight, 20 to 80% by weight, 30 to 70% by weight, or 40 to 60% by weight. The content of p-xylene in the mixed aromatic hydrocarbon feedstock may be 6 to 50% by weight, 7 to 40% by weight, 8 to 30% by weight, or 10 to 25% by weight.

[0046] In a particularly preferred embodiment, the meta-aromatic hydrocarbon is m-xylene, and the mixed aromatic hydrocarbon feedstock contains 20 to 60% by weight of m-xylene, 10 to 30% by weight of p-xylene, 10 to 30% by weight of o-xylene, and 5 to 20% by weight of ethylbenzene, for example, 40 to 55% by weight of m-xylene, 15 to 25% by weight of p-xylene, 15 to 25% by weight of o-xylene, and 5 to 15% by weight of ethylbenzene.

[0047] In some further preferred embodiments, the meta-aromatic hydrocarbon is 2,7-dimethylnaphthalene, and the mixed aromatic hydrocarbon feedstock is a mixed C12 aromatic hydrocarbon feedstock containing 2,7-dimethylnaphthalene (meta-position) and at least one other C12 aromatic hydrocarbon selected from 1,6-dimethylnaphthalene (non-para, non-ortho position), 2,6-dimethylnaphthalene (para-position), and 1,8-dimethylnaphthalene (ortho position), 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 1,7-dimethylnaphthalene, 2,3-dimethylnaphthalene. More preferably, the mixed C12 aromatic hydrocarbon feedstock contains 5 to 95% by weight of 2,7-dimethylnaphthalene.

[0048] In a preferred embodiment, the adsorbent used in the adsorption separation contains at least 90% by weight of Y-type molecular sieve as an active ingredient, and the Y-type molecular sieve has a molar ratio of silicon oxide to aluminum oxide of 4.0 to 6.0, preferably 4.3 to 5.7. Other characteristics of the adsorbent are as described in the second aspect of the present application below.

[0049] In a preferred embodiment, based on the total amount of the liquid material, the liquid material contains 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, and 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight of an alkane selected from C5 to C14 straight-chain alkanes, preferably selected from C6 to C10 straight-chain alkanes, more preferably selected from C6 to C8 straight-chain alkanes. The inventors of the present application have found that including a certain amount of C5 to C14 straight-chain alkanes in the liquid material as a desorbent helps to moderate the strong desorption performance of the aromatic desorbent, helps to reduce the half-width of the separation peak, thereby improving the separation degree between the target component and other components, and ultimately reducing the total amount of the desorbent, material consumption, and energy consumption.

[0050] In a particularly preferred embodiment, the meta-aromatic hydrocarbon is m-xylene, the mixed aromatic hydrocarbon feedstock comprises 20 to 60% by weight of m-xylene, 10 to 30% by weight of p-xylene, 10 to 30% by weight of o-xylene, and 5 to 20% by weight of ethylbenzene, the alkylbenzene compound of formula (I) is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, based on the total amount of the liquid material, the liquid material comprises 30 to 70% by weight of the alkylbenzene compound and 30 to 70% by weight of an alkane selected from C5-C14 straight-chain alkanes, the charge-balancing cation of the adsorbent is Na + , Sr 2+ , Ba 2+ , and Ag + selected from, and the adsorbent contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight, of adsorbed water.

[0051] In a second aspect, the present application is a method for separating one or more meta-aromatic hydrocarbons from a mixed aromatic hydrocarbon feedstock containing the one or more meta-aromatic hydrocarbons and their isomers, 1) contacting the mixed aromatic hydrocarbon feedstock with an adsorbent to adsorb one or more meta-aromatic hydrocarbons, thereby obtaining an adsorbent having adsorbed thereon the one or more meta-aromatic hydrocarbons and a raffinate containing unadsorbed components; 2) contacting the adsorbent having adsorbed thereon the one or more meta-aromatic hydrocarbons obtained in step 1) with a desorbent, thereby desorbing the one or more meta-aromatic hydrocarbons to obtain an extract containing the one or more meta-aromatic hydrocarbons and the desorbent; 3) subjecting the extract obtained in step 2) to rectification separation to obtain the one or more meta-aromatic hydrocarbons and the desorbent; comprising Based on the total amount of the desorbent, the desorbent contains, or consists of, 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5-C14 saturated aliphatic hydrocarbon:

[0052]

Chemical formula

[0053] wherein R1, R2, R3, R4, R5, and R6 are as defined above, a method is provided.

[0054] In a preferred embodiment, in formula (I), at least one of R1, R2, and R3 is methyl, and R4, R5, and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group.

[0055] In a more preferred embodiment, in formula (I), at least two of R1, R2, and R3 are methyl, and R4, R5, and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group, and at least one of them is hydrogen.

[0056] In a further more preferred embodiment, in formula (I), at least two of R1, R2, and R3 are methyl, and R5 and R6 are independently hydrogen or a C 1-4 saturated hydrocarbon group, at least two of them are hydrogen, preferably all three are hydrogen.

[0057] In a particularly preferred embodiment, the alkylbenzene compound of formula (I) is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, preferably 1,2,3-trimethylbenzene or 1,2,3,4-tetramethylbenzene.

[0058] In a preferred embodiment, the meta-aromatic hydrocarbon is a C8-C12 meta-aromatic hydrocarbon, preferably a C8-C12 meta-alkyl aromatic hydrocarbon, such as m-xylene or 2,7-dimethylnaphthalene.

[0059] In a further preferred embodiment, the meta-aromatic hydrocarbon is m-xylene, and the mixed aromatic hydrocarbon feedstock is m-xylene and at least one other C8 aromatic hydrocarbon selected from p-xylene, o-xylene, and ethylbenzene, and is a mixed C8 aromatic hydrocarbon feedstock. More preferably, the mixed C8 aromatic hydrocarbon feedstock contains 5-95% by weight of m-xylene. Particularly preferably, the mixed aromatic hydrocarbon feedstock contains 5-94% by weight of m-xylene and 6-95% by weight of p-xylene, more preferably 5-90% by weight of m-xylene and 10-95% by weight of p-xylene. For example, the content of xylene in the mixed aromatic hydrocarbon feedstock may be 10-90% by weight, 20-80% by weight, 30-70% by weight, or 40-60% by weight. The content of p-xylene in the mixed aromatic hydrocarbon feedstock may be 6-50% by weight, 7-40% by weight, 8-30% by weight, or 10-25% by weight.

[0060] In some further preferred embodiments, the meta-aromatic hydrocarbon is 2,7-dimethylnaphthalene, and the mixed aromatic hydrocarbon feedstock is a mixed C12 aromatic hydrocarbon feedstock comprising 2,7-dimethylnaphthalene (meta-position) and at least one other C12 aromatic hydrocarbon selected from 1,6-dimethylnaphthalene (non-para, non-ortho position), 2,6-dimethylnaphthalene (para-position), and 1,8-dimethylnaphthalene (ortho position). More preferably, the mixed C12 aromatic hydrocarbon feedstock comprises 5 to 95% by weight of 2,7-dimethylnaphthalene.

[0061] This application has no strict restrictions on the source of the mixed aromatic hydrocarbon feedstock. In one exemplary embodiment, the mixed aromatic hydrocarbon feedstock, particularly the mixed C8 aromatic hydrocarbon feedstock, may be derived from a catalytic reforming unit, a disproportionation and transalkylation unit, a toluene shape-selective disproportionation unit, an isomerization unit, and / or a p-xylene adsorption separation unit.

[0062] In a preferred embodiment, based on the total amount of the desorbent, the desorbent comprises 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, and 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight of an alkane selected from C5 to C14 straight-chain alkanes, preferably selected from C6 to C10 straight-chain alkanes, more preferably selected from C6 to C8 straight-chain alkanes, and comprises or consists of.

[0063] In a preferred embodiment, the adsorbent used in step 1) contains at least 90% by weight of Y-type molecular sieve as an active ingredient, and the molar ratio of silicon oxide to aluminum oxide of the Y-type molecular sieve is 4.0 to 6.0, preferably 4.3 to 5.7. More preferably, the crystal size of the Y-type molecular sieve is 0.5 to 2.0 μm, preferably 0.8 to 1.2 μm. In an exemplary embodiment, the toluene adsorption capacity of the completed beads of the adsorbent is 155 to 220 mg / g, the bulk density based on calcination is 0.645 to 0.867 g / mL, and the crushing rate at 130 N is 0.3 to 5.0% by weight.

[0064] In a more preferred embodiment, the adsorbent contains 0.05 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.05 to 0.8% by weight, and even more preferably 0.1 to 0.5% by weight of adsorbed water. The inventors of the present application have found that water molecules in the adsorbent have the effect of regulating the adsorption capacity and adsorption performance. When the water content in the adsorbent is different, the preferential selectivity of the adsorbent for the target component is different. Due to the polarization of water molecules, the polarization intensity of cations outside the crystal lattice of the molecular sieve of the adsorbent is affected by water molecules, and the interaction between the adsorbent and the adsorbate, especially the electrostatic interaction between the adsorbent and the target component, changes, so the selectivity of the adsorbent and the mass transfer efficiency of the adsorbate in the adsorption system change. In addition, when the mass fraction of water molecules is high, a large number of water molecules occupy a part of the effective pore volume in the crystal lattice of the molecular sieve of the adsorbent, and as a result, the adsorption capacity of the target component decreases. When the water content exceeds a certain range, the crystal structure of the molecular sieve of the adsorbent undergoes irreversible hydrothermal destruction, leading to a significant decrease in the adsorption capacity and adsorption selectivity. Therefore, an appropriate water content in the adsorbent helps the adsorbent to stably exhibit optimal adsorption performance for a long time.

[0065] This application does not have strict requirements for the preparation method of the adsorbent. In an exemplary embodiment, the adsorbent is prepared by the rolling ball mixing method, and the composition of the raw materials is 90-99 wt% of Y-type molecular sieve, 0.5-9 wt% of binder, and 0.5-1 wt% of forming aid. Preferably, the binder is kaolin, bentonite, and / or attapulgite, and the forming aid is lignin, sesbania powder, dried starch, carboxymethyl cellulose, and / or activated carbon. After the preparation of the adsorbent, the composition of the adsorbent is 91-99.5 wt% of Y-type molecular sieve and 0.5-9 wt% of binder.

[0066] In a more preferred embodiment, the adsorbent further contains one or more of Group IA metal ions, Group IIA metal ions, and Group IB metal ions, such as one kind or two kinds, as charge-balancing cations. The Group IA metal ion is preferably Li + , and Na + selected from, The Group IIA metal ion is preferably Mg 2+ , Sr 2+ , and Ba 2+ selected from, The Group IB metal ion is preferably Ag + . Preferably, the total amount of the Group IA metal, Group IIA metal, and Group IB metal in the adsorbent is calculated as metal oxide based on the total weight of the adsorbent and is 10-45%.

[0067] In a particularly preferred embodiment, the adsorbent contains at least 90 wt% of NaY-type molecular sieve as the active ingredient, and the adsorbent is preferably treated by metal ion exchange, that is, the Na + ions in the molecular sieve are exchanged with other metal ions, and as a result, the degree of metal ion exchange is 78.0-99.9%. Particularly preferably, the molar concentration of the metal salt in the ion exchange process is 0.05-0.65 mol / L, preferably 0.15-0.50 mol / L.

[0068] All the features of the adsorbent disclosed in the second aspect of the present application are also applicable to the adsorbents described in the first and third aspects of the present application, and thus will not be described in detail in the first and third aspects of the present application.

[0069] In a particularly preferred embodiment, the meta-aromatic hydrocarbon is m-xylene, the mixed aromatic hydrocarbon feedstock contains 20 to 60% by weight of m-xylene, 10 to 30% by weight of p-xylene, 10 to 30% by weight of o-xylene, and 5 to 20% by weight of ethylbenzene, the alkylbenzene compound of formula (I) is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, based on the total amount of the desorbent, the desorbent contains 30 to 70% by weight of the alkylbenzene compound and 30 to 70% by weight of an alkane selected from C5-C14 linear alkanes, the charge-balancing cation of the adsorbent is Na + , Sr 2+ , Ba 2+ , and Ag + selected from, and the adsorbent contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight, of adsorbed water.

[0070] In a preferred embodiment, the operating conditions of the adsorption in step 1) and the desorption in step 2) are a temperature of 100 to 190°C, preferably 110 to 180°C, more preferably 120 to 160°C, and / or a pressure of 0.6 to 1.6 MPa, preferably 0.8 to 1.0 MPa, each independently included.

[0071] According to the present application, a method for separating one or more meta-aromatic hydrocarbons may be implemented by, but not limited to, using a simulated moving bed. Generally, the simulated moving bed may include one or more adsorption towers, each tower includes a plurality of bed layers filled with an adsorbent, each bed layer has an inlet pipeline and an outlet pipeline for its own material, the material in the adsorption tower flows from the top to the bottom, the material between the towers is transported by a circulation pump, and the material flows through the adsorption bed layers of different adsorption towers to form a closed cycle with end-to-end connection. The material flowing into and out of the adsorption bed layer includes at least a feedstock (F), a desorbent (D), an extract (E), and a raffinate (R). The material flowing into and out of the simulated moving bed divides the adsorption bed layer therein into a desorption zone, a purification zone, an adsorption zone, and an isolation zone, the adsorption bed layer between the desorbent injection and the extract discharge is the desorption zone, the adsorption bed layer between the extract discharge and the feedstock injection is the purification zone, the adsorption bed layer between the feedstock injection and the raffinate discharge is the adsorption zone, and the temperature of the adsorption bed layer is the adsorption temperature, the adsorption bed layer between the raffinate discharge and the desorbent injection is the isolation zone. During the operation of the simulated moving bed, the position of each material flow flowing into and out of the adsorption bed layer of the adsorption tower changes periodically. A multi-way rotary valve or a program-controlled switching valve group may be used to control the inflow and outflow of each material flow in different adsorption bed layers. At a certain moment, each material flow is connected to a specific bed layer, and at regular intervals, that is, in one step time, the inflow and outflow positions of each material flow move down by one adsorption bed layer. The time required for the inflow position of the material flow into the adsorption bed layer (or the discharge position of the material flow from the adsorption bed) to return to the starting position through all the adsorption bed layers is one cycle period.

[0072] In a preferred embodiment, steps 1) and 2) are carried out by using a simulated moving bed, the simulated moving bed comprises a plurality of adsorption bed layers filled with an adsorbent, each bed layer is provided with an inlet pipeline and an outlet pipeline for the corresponding material, the material flowing into and out of the simulated moving bed divides the adsorption bed into a desorption zone, a purification zone, an adsorption zone, and an isolation zone. Preferably, the ratio of the number of bed layers in the adsorption zone, the purification zone, the desorption zone, and the isolation zone in the simulated moving bed is 25±10%:38±15%:25±5%:12±4%.

[0073] In a more preferred embodiment, the mass flow ratio of the desorbent flowing into the simulated moving bed to the mixed aromatic hydrocarbon feedstock is 0.01 to 6.0, preferably 0.01 to 5.5, more preferably 0.01 to 5.0.

[0074] In a more preferred embodiment, the flow rate of the mixed aromatic hydrocarbon feedstock flowing into the simulated moving bed per unit mass of the adsorbent is in the range of 0.1 to 8 kg / (h·kg adsorbent), preferably 0.15 to 8 kg / (h·kg adsorbent), more preferably 0.17 to 8 kg / (h·kg adsorbent).

[0075] In a more preferred embodiment, the step time of the simulated moving bed is 60 to 160 seconds, preferably 70 to 120 seconds.

[0076] In a more preferred embodiment, one cycle period of the simulated moving bed is 12 to 70 minutes, preferably 20 to 40 minutes.

[0077] In the method of the present application, by selecting a suitable desorbent and corresponding operating conditions, when the separation in steps 1) and 2) is carried out by using a simulated moving bed, the separation effect including purity and yield can be improved, the feedstock processing capacity is increased, and the material consumption and energy consumption including not only the energy consumption for recycling and reuse but also the pipeline flow rate and circulation flow rate of each material flow are reduced.

[0078] According to the present application, the extract obtained in step 2) contains one or more meta-aromatic hydrocarbons and a part of the desorbent, and the difference in boiling points between the two components can be used to separate and recover the two components by distillation in step 3). For example, when one or more meta-aromatic hydrocarbons are m-xylene, in step 3), the desorbent in the extract can be recovered at the bottom of the column by a distillation column, and the top stream passes through the subsequent product column to obtain a high-purity m-xylene product. In addition, when a simulated moving bed is used, the main components of the raffinate obtained in step 1) are the desorbent and other components in the feedstock except m-xylene. The desorbent in the raffinate can be recovered at the bottom of the column by a distillation column, and the raffinate oil obtained at the top of the column can be subjected to corresponding subsequent processing and separation, or used as an isomerization feedstock for an aromatic unit.

[0079] In a third aspect, the present application is a kit of an adsorption and desorption agent including a solid adsorbent and a liquid desorbent, wherein the solid adsorbent contains at least 90% by weight of Y-type molecular sieve as an active ingredient, and the Y-type molecular sieve has a silicon oxide / aluminum oxide molar ratio of 4.0 to 6.0, preferably 4.3 to 5.7, the liquid desorbent contains, or consists of, 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5-C14 saturated aliphatic hydrocarbon,

[0080]

Chemical formula

[0081] Provide a kit, wherein R1, R2, R3, R4, R5, and R6 are as defined above.

[0082] In a certain preferred embodiment, in formula (I), At least one of R1, R2, and R3 is methyl, R4, R5, and R6 are independently hydrogen or a C 1-4 Saturated hydrocarbon group.

[0083] In a more preferred embodiment, in formula (I), At least two of R1, R2, and R3 are methyl, R4, R5, and R6 are independently hydrogen or a C 1-4 Saturated hydrocarbon group, and at least one of them is hydrogen.

[0084] In a more preferred embodiment, in formula (I), At least two of R1, R2, and R3 are methyl, R5 and R6 are independently hydrogen or a C 1-4 Saturated hydrocarbon group, at least two of them are hydrogen, and preferably all three are hydrogen.

[0085] In a more preferred embodiment, the alkylbenzene compound of formula (I) is selected from 1,2,3 - trimethylbenzene, 1,2,3,4 - tetramethylbenzene, 1,2,3,4,5 - pentamethylbenzene, and 3 - ethyl - o - xylene, and preferably 1,2,3 - trimethylbenzene or 1,2,3,4 - tetramethylbenzene.

[0086] In a preferred embodiment, based on the total amount of the liquid desorbent, the desorbent 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, and 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight of an alkane selected from C5 - C14 straight-chain alkanes, preferably selected from C6 - C10 straight-chain alkanes, more preferably selected from C6 - C8 straight-chain alkanes, and comprising, or consisting of.

[0087] In a preferred embodiment, the solid adsorbent contains 0.05 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.05 to 0.8% by weight, even more preferably 0.1 to 0.5% by weight of adsorbed water.

[0088] In a particularly preferred embodiment, based on the total amount of the liquid desorbent, the liquid desorbent comprises 30 to 70% by weight of the alkylbenzene compound and 30 to 70% by weight of an alkane selected from C5 - C14 straight-chain alkanes, The charge-balancing cations of the solid adsorbent are Na + , Sr 2+ , Ba 2+ and Ag + selected from, and the adsorbent contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight of adsorbed water.

[0089] Other features of the adsorbent used in the third aspect of the present application are as described in the second aspect of the present application and are not repeated here.

[0090] In a certain preferred embodiment, the present application provides the following technical solutions.

[0091] 1. A method for separating high-purity m-xylene by adsorption using a heavy desorbent, comprising a step of introducing a C8 aromatic hydrocarbon mixed feedstock into an adsorbent, wherein the m-xylene in the feedstock is adsorbed by the adsorbent, The unadsorbed components are discharged as raffinate, The heavy desorbent is introduced into the adsorbent to desorb the adsorbed m-xylene to obtain an extract, The extract containing the desorbent and the raffinate are subjected to distillation separation to obtain m-xylene and other C8 aromatic hydrocarbon components at the top of the distillation column, respectively. The method includes the step of recovering the desorbent at the bottom of the distillation column.

[0092] 2. The heavy desorbent is one or more selected from 1,2,3-trisubstituted C9+ alkylbenzenes or their derivatives, 1,2,3,4-tetrasubstituted C9+ alkylbenzenes or their derivatives, 1,2,3,4,5-pentasubstituted C9+ alkylbenzenes or their derivatives. The method according to item 1, characterized in that.

[0093] 3. The heavy desorbent is an alkane, and one or more selected from 1,2,3-trisubstituted C9+ alkylbenzenes or their derivatives, 1,2,3,4-tetrasubstituted C9+ alkylbenzenes or their derivatives, 1,2,3,4,5-pentasubstituted C9+ alkylbenzenes or their derivatives, and is a mixture of The alkane is preferably a C5-C8 linear alkane, and its content is not more than 80% by weight. The method according to item 1, characterized in that.

[0094] 4. The 1,2,3-trisubstituted C9+ alkylbenzene is 1,2,3-trimethylbenzene and 3-ethyl-o-xylene, The 1,2,3,4-tetrasubstituted C9+ alkylbenzene is 1,2,3,4-tetramethylbenzene, The 1,2,3,4,5-pentasubstituted C9+ alkylbenzene is 1,2,3,4,5-pentamethylbenzene. The method according to item 2 or 3, characterized in that.

[0095] 5. The active ingredient of the adsorbent is Y-type molecular sieve, and the molar ratio of silicon oxide to aluminum oxide thereof is 4.0 to 6.0, preferably 4.3 to 5.7. The method according to any one of Items 1 to 4, characterized in that.

[0096] 6. The crystal size of the Y-type molecular sieve is 0.5 to 2.0 μm, preferably 0.8 to 1.2 μm. The method according to Item 5, characterized in that.

[0097] 7. The adsorbent contains adsorbed water of 2% by weight or less, preferably 1% by weight or less, more preferably 0.8% by weight or less. The method according to any one of Items 1 to 4, characterized in that.

[0098] 8. The active ingredient of the adsorbent is Y-type molecular sieve, The charge-balancing cations of the adsorbent are one or two metal ions of Group IA, Group IIA, and Group IB, preferably, the metal ions within Group IA are one or two of Li + , and Na + , the metal ions within Group IIA are one or two of Mg 2+ , Sr 2+ , and Ba 2+ , and the metal ion within Group IB is Ag + . The method according to Items 1 to 4, characterized in that.

[0099] 9. The adsorbent whose active ingredient is NaY-type molecular sieve is subjected to metal ion exchange, The molar concentration of the metal salt during the ion exchange process is 0.05 to 0.65 mol / L, preferably 0.15 to 0.50 mol / L. The method according to Items 1 to 4, characterized in that.

[0100] 10. The adsorption temperature is 100 to 190 °C, preferably 110 to 180 °C, more preferably 120 to 160 °C. The method according to any one of items 1 to 9, characterized in that.

[0101] 11. The adsorption pressure is 0.6 to 1.6 MPa, preferably 0.8 to 1.0 MPa. The method according to any one of items 1 to 10, characterized in that.

[0102] 12. The feedstock is derived from a catalytic reforming unit, a disproportionation and transalkylation unit, a toluene shape-selective disproportionation unit, an isomerization unit, and / or a p-xylene adsorption separation unit. The method according to any one of items 1 to 11, characterized in that.

[0103] 13. The composition of the rolling ball mixture used in the preparation process of the adsorbent is 90 to 99 wt% of Y-type molecular sieve, 0.5 to 9 wt% of binder, and 0.5 to 1 wt% of forming aid. The composition of the adsorbent is 91.0 to 99.5 wt% of Y-type molecular sieve, and 0.5 to 9 wt% of binder. The method according to any one of items 1 to 12, characterized in that.

[0104] 14. The binder is kaolin, bentonite, and / or attapulgite. The method according to item 13, characterized in that.

[0105] 15. The forming aid is lignin, sesbania powder, dried starch, carboxymethyl cellulose, and / or activated carbon. The method according to item 13, characterized in that.

[0106] 16. The adsorption separation employs a simulated moving bed process. The method according to any one of items 1 to 15, characterized in that.

[0107] 17. The simulated moving bed includes a plurality of adsorption bed layers filled with an adsorbent, each bed layer has an inlet pipeline and an outlet pipeline for its own material, the material flowing into and out of the simulated moving bed divides the adsorption bed layer therein into a desorption zone, a purification zone, an adsorption zone, and an isolation zone, the adsorption bed layer between the desorbent injection and the extract discharge is the desorption zone, the adsorption bed layer between the extract discharge and the feedstock injection is the purification zone, the adsorption bed layer between the feedstock injection and the raffinate discharge is the adsorption zone, the adsorption bed layer between the raffinate discharge and the desorbent injection is the isolation zone, The method according to item 16, characterized in that.

[0108] 18. The ratio of the number of bed layers in the adsorption zone, purification zone, desorption zone, and isolation zone in the simulated moving bed is 25 ± 10%: 38 ± 15%: 25 ± 5%: 12 ± 4%, The method according to item 16, characterized in that.

[0109] 19. The mass flow rate ratio of the desorbent to the feedstock flowing into the simulated moving bed is 6.0 or less, preferably 5.5 or less, more preferably 5.0 or less, The method according to item 16, characterized in that.

[0110] 20. The flow rate of the feedstock flowing into the simulated moving bed per unit mass of the adsorbent is 0.1 / (h·kg adsorbent) or more, preferably 0.15 kg / (h·kg adsorbent) or more, more preferably 0.17 kg / (h·kg adsorbent) or more, The method according to item 16, characterized in that.

[0111] 21. The cycle period of the simulated moving bed is 12 to 70 minutes, preferably 20 to 40 minutes. The method according to item 16, characterized in that.

[0112] 22. A desorbent composition comprising an alkylbenzene selected from the following and one or more alkanes selected from C5 - C8 linear alkanes, wherein the alkylbenzene is one or more selected from 1,2,3 - trisubstituted C9+ alkylbenzene or its derivatives, 1,2,3,4 - tetrasubstituted C9+ alkylbenzene or its derivatives, 1,2,3,4,5 - pentasubstituted C9+ alkylbenzene or its derivatives, and the content of the alkane is 80% by weight or less based on the weight of the desorbent composition.

[0113] 23. The 1,2,3 - trisubstituted C9+ alkylbenzene is 1,2,3 - trimethylbenzene and 3 - ethyl - o - xylene, the 1,2,3,4 - tetrasubstituted C9+ alkylbenzene is 1,2,3,4 - tetramethylbenzene, and the 1,2,3,4,5 - pentasubstituted C9+ alkylbenzene is 1,2,3,4,5 - pentamethylbenzene. The composition according to item 22, characterized in that.

[0114] 24. Use of an alkylbenzene selected from the following as a desorbent for the adsorption separation of high - purity m - xylene, wherein the alkylbenzene is one or more selected from 1,2,3 - trisubstituted C9+ alkylbenzene or its derivatives, 1,2,3,4 - tetrasubstituted C9+ alkylbenzene or its derivatives, 1,2,3,4,5 - pentasubstituted C9+ alkylbenzene or its derivatives, and the content of the alkane is not more than 80% by weight based on the weight of the desorbent composition.

[0115] 25. The alkylbenzene is combined with one or more alkanes selected from C5 - C8 straight-chain alkanes as the desorbent, and the content of the alkane is not more than 80% by weight based on the weight of the desorbent, Use according to item 22.

[0116] 26. The 1,2,3-trisubstituted C9+ alkylbenzene is 1,2,3-trimethylbenzene and 3-ethyl-o-xylene, the 1,2,3,4-tetrasubstituted C9+ alkylbenzene is 1,2,3,4-tetramethylbenzene, and the 1,2,3,4,5-pentasubstituted C9+ alkylbenzene is 1,2,3,4,5-pentamethylbenzene, Use according to item 24 or 25, characterized in that.

[0117] 〔Examples〕 The present invention will be further described in detail by the following examples, but the present application is not limited thereto.

[0118] <Test method> (Evaluation of adsorbent performance) The adsorption capacity of the adsorbent was determined by a toluene gas-phase adsorption experiment. As a specific operation method, at 35°C, nitrogen carrying toluene (toluene partial pressure is 0.05 MPa) was brought into contact with a certain mass of adsorbent until toluene reached adsorption equilibrium. The adsorption capacity of the tested adsorbent was calculated by the following formula based on the mass difference of the adsorbent before and after toluene adsorption.

[0119]

Number

[0120] C is the adsorption capacity (mg / g), m1 is the mass (g) of the adsorbent before toluene adsorption, and m2 is the mass (g) of the adsorbent after toluene adsorption.

[0121] The bulk density of the adsorbent based on calcination was determined by the following method. 50 mL of the adsorbent was added into a 100 mL graduated cylinder, and it was vibrated on a tap density meter (manufactured by Liaoning Institute of Instrumentation Co., Ltd.) for 5 minutes. Then, 50 mL of the adsorbent was added thereto and vibrated for 5 minutes. The ratio of the mass to the volume of the adsorbent in the graduated cylinder is the bulk density of the adsorbent. A certain mass of the adsorbent was taken, calcined at 600 °C for 2 hours, placed in a desiccator, and cooled to room temperature. The ratio of the mass of the adsorbent after calcination to the mass of the adsorbent before calcination is the calcination basis, and the product of the calcination basis and the bulk density of the adsorbent is the bulk density based on calcination.

[0122] The compression strength of the adsorbent is represented by the crushing rate of the adsorbent beads under a certain pressure. The lower the crushing rate, the higher the compression strength. As a method for measuring the compression strength of the adsorbent, measurement was carried out using a DL-II type particle strength tester (manufactured by Dalian Institute of Chemical Industry Research and Design). After passing the adsorbent beads through a 300-micron sieve, about 1.5 mL of the adsorbent was filled into a stainless steel cylinder. When the measurement was carried out, a pin having an interference fit with the stainless steel cylinder was attached. After pressurizing once under a preset pressure, the adsorbent was allowed to flow out, then passed through a 300-micron sieve, and weighed. The mass reduction of the adsorbent before and after the pressurization test is the crushing rate of the adsorbent under the set pressure.

[0123] After the ion exchange test, the mass fraction of the metal oxide in the adsorbent was determined by a fluorescent X-ray analyzer. Based on this, the molar fraction of the metal ions was calculated, and the metal ion exchange degree of the adsorbent was further calculated by the following formula, thereby determining the metal ion exchange degree of the adsorbent.

[0124]

Equation

[0125] η is the degree of ion exchange, m1 is the mass fraction of Na2O in the adsorbent after ion exchange, m2 is the mass fraction of the target metal (exchanged metal) oxide in the adsorbent after ion exchange, M1 is the molar mass of Na2O, and M2 is the molar mass of the target metal oxide.

[0126] (Performance Evaluation of Adsorption-Desorption System) In the following examples and comparative examples, a dynamic pulse experimental apparatus was used to evaluate the performance of the adsorption-desorption system used, including the adsorption selectivity of the adsorbent and the adsorption and desorption rates of the target product. The apparatus was composed of a supply system, an adsorption column, a heating furnace, a pressure control valve, etc. The adsorption column was a stainless steel tube with a diameter of Ф6×940 mm. The lower inlet of the adsorption column was connected to the supply and nitrogen systems, and the upper outlet was connected to a pressure control valve that was then connected to a drain collector.

[0127] For specific adsorbents and adsorbates, pulse tests were carried out under the same process conditions, and different separation effects may be generated by changing the type or composition of the desorbent. This is because the desorbent, adsorbate, and target components interact synergistically, promote each other, and limit each other. Changing the desorbent changes the selectivity difference between the target component and the impurities in the adsorbate, and also changes the selective adsorption of the adsorbent for the target component. Therefore, when pulse tests are carried out using different desorbents, the peak times, peak shapes, intervals, and extreme value positions of the target component and impurities may be different, and the degree of separation may also be different. Specific parameters are represented as significantly different separation coefficients and separation degrees.

[0128] As a method for measuring the adsorption selectivity of the adsorption-desorption system, adsorbent particles with a particle size of 500 - 1000 μm were filled into the adsorption column, shaken and compacted, nitrogen was introduced at room temperature to exhaust the air remaining in the system, and then the desorbent was introduced to remove the gas in the system. The pressure and temperature of the system were raised to the set values, the introduction of the desorbent was stopped, and 5 - 10 mL of the pulse feedstock solution was added over 1.0 h -1It was introduced at a volumetric space velocity. Here, the feedstock solution contained a non-adsorbed tracer. Next, the desorbent was introduced at the same volumetric space velocity, and three drops of the desorption liquid sample were taken every 2 mL and analyzed by gas chromatography. With the volume of the desorbent used for desorption on the horizontal axis and the concentration of each component of the pulsed feedstock solution on the vertical axis, the desorption curves of each component of the pulsed feedstock solution were plotted. Here, the non-adsorbed tracer could be used to obtain the dead volume of the adsorption system. Taking the midpoint of the half-width of the tracer peak as the zero point, the net retention volume from the midpoint of the half-width of each component peak to the zero point was measured. The net retention volume of any component was proportional to the distribution coefficient at adsorption equilibrium and reflected the interaction between each component and the adsorbent. The ratio of the net retention volumes of two components was the separation factor β. For example, the ratio of the net retention volume of m-xylene to the net retention volume of ethylbenzene was the ratio of the adsorption performance of the adsorbent in the adsorption-desorption system for the two compounds, the separation factor of m-xylene relative to ethylbenzene, and was denoted as β (MX / EB) was recorded. The larger the value of β, the greater the difference in the adsorption capacity of the adsorbent in the adsorption-desorption system for the two components of MX and ethylbenzene (EB), that is, MX was more easily adsorbed and EB was less easily adsorbed, so the two components were easily separated.

[0129] The half-width of the pulse peak envelope provides information about the mass transfer rate of the fluid between the particles of the adsorbent, between the particles of the molecular sieve, and within the molecular sieve crystals. The narrower the half-width of the component, the smaller the half-width value, which means that the adsorption and desorption rates of the component by the adsorbent in the adsorption-desorption system are faster and the mass transfer of the component in the adsorbent is faster. The increase in the adsorption and desorption rates means an improvement in the efficiency of the adsorbent, which helps to reduce the filling amount of the adsorbent and the investment. The increase in the adsorption and desorption rates also means a reduction in the amount of desorbent used for desorption, which helps to reduce energy consumption.

[0130] Resolution is usually one of the indices for evaluating the separation efficiency of an adsorption and desorption system, especially for evaluating the influence of different adsorbents or desorbents on adsorption separation under the same operating parameters. R MX / EB The resolution, as the ratio of the difference between the net retention volumes of m-xylene and ethylbenzene recorded as MX / EB to the average half-width of the pulse peaks of the two components, that is, like the resolution between the two components, is equal to the ratio of the difference between the net retention volumes of the two pulse peaks to the average half-width of the two pulse peaks. According to the definition and calculation method of resolution, the resolution of the strongly adsorbed component with respect to the weakly adsorbed component is proportional to the difference in the net retention volume between the two components and inversely proportional to the average half-width of the peak. Therefore, the resolution R comprehensively considers the difference in adsorption strength and the influence of the mass transfer rate on adsorption separation. R MX / EB The larger the value of R, the larger the difference in the net retention volume between the MX and EB components, or the smaller the average half-width of the peak, the larger the difference in adsorption selectivity, or the faster the adsorption and desorption rates. Compared with the EB component, MX is more easily adsorbed by the adsorbent in the adsorption and desorption system, or its adsorption and desorption rates in the adsorption and desorption system are faster, and the comprehensive separation effect is high.

[0131] In the following examples and comparative examples, unless otherwise specified, all the reagents and raw materials used are commercially available and of chemically pure grade.

[0132] <Adsorbent Preparation Example 1> NaY-type molecular sieve having a silicon oxide / aluminum oxide molar ratio of 5.0 and a crystal particle size of 0.8 μm was uniformly mixed with kaolin mineral and sesbania powder in a mass ratio of 95:4:1, rounded into beads for molding, dried, and then calcined at 540 °C for 8 hours. The calcined beads were washed with deionized water at a liquid-solid ratio of 10 and dried at 100 °C for 4 hours to obtain Adsorbent A.

[0133] The mass ratio of the molecular sieve to the kaolin mineral in the adsorbent beads is 96:4, and its X-ray diffraction (XRD) spectrum is shown in Figure 1. By analysis, the toluene adsorption capacity of adsorbent A is 213 mg / g, the bulk density based on firing is 0.651 g / mL, the crushing rate at 130 N is 0.9% by weight, and the mass fraction of the charge-balancing cation calculated as a metal oxide is 12.8%.

[0134] <Adsorbent Preparation Example 2> NaY-type molecular sieve having a molar ratio of silicon oxide / aluminum oxide of 4.3 and a crystal particle size of 0.9 μm was uniformly mixed with kaolin mineral and sesbania powder at a mass ratio of 95:4:1, rounded into beads for molding, dried, and then fired at 540 °C for 8 hours. The fired beads were washed with deionized water at a liquid-solid ratio of 10 and dried at 100 °C for 4 hours to obtain adsorbent B.

[0135] The mass ratio of the molecular sieve to the kaolin mineral in the adsorbent beads was 96:4. By analysis, the toluene adsorption capacity of adsorbent B is 212 mg / g, the bulk density based on firing is 0.652 g / mL, the crushing rate at 130 N is 1.0% by weight, and the mass fraction of the charge-balancing cation calculated as a metal oxide is 13.6%.

[0136] <Adsorbent Preparation Example 3> NaY-type molecular sieve having a molar ratio of silicon oxide / aluminum oxide of 5.0 and a crystal particle size of 1.1 μm was uniformly mixed with kaolin mineral and sesbania powder at a mass ratio of 92:7:1, rounded into beads for molding, dried, and then fired at 540 °C for 6 hours. The fired beads were subjected to column ion exchange at a temperature of 85 °C for 8 hours using a 0.25 mol / L silver nitrate solution. The liquid-solid ratio of the solution to the adsorbent was 45, and the space velocity was 5 h -1 -1. The ion exchange degree calculated by the above formula was 89.5%. After the exchange, the beads were dried at 100 °C for 3 hours to obtain adsorbent C.

[0137] The mass ratio of the molecular sieve to the kaolin mineral in the adsorbent beads was 93:7. By analysis, the toluene adsorption capacity of adsorbent C was 183 mg / g, the bulk density based on calcination was 0.823 g / mL, the crushing rate at 130 N was 2.5 wt%, and the mass fraction of the charge-balancing cation calculated as a metal oxide was 37.6%.

[0138] <Adsorbent Preparation Example 4> NaY-type molecular sieve having a molar ratio of silicon oxide / aluminum oxide of 5.0 and a crystal particle size of 1.0 μm was uniformly mixed with kaolin mineral and sesbania powder at a mass ratio of 94:5.5:0.5, rounded into beads for molding, dried, and then calcined at 550 °C for 9 hours. The calcined beads were subjected to column ion exchange at a temperature of 90 °C for 8 hours using a 0.40 mol / L strontium chloride hexahydrate solution. The liquid-solid ratio of the solution to the adsorbent was 40, and the space velocity was 5 h -1 The degree of ion exchange calculated by the above formula was 99.5%. After the exchange, the beads were dried at 100 °C for 4 hours to obtain adsorbent D.

[0139] The mass ratio of the molecular sieve to the kaolin mineral in the adsorbent beads was 94.5:5.5. By analysis, the toluene adsorption capacity of adsorbent D was 185 mg / g, the bulk density based on calcination was 0.785 g / mL, the crushing rate at 130 N was 3.0 wt%, and the mass fraction of the charge-balancing cation calculated as a metal oxide was 36.9%.

[0140] <Adsorbent Preparation Example 5> NaY-type molecular sieve having a molar ratio of silicon oxide / aluminum oxide of 5.0 and a crystal particle size of 0.8 μm was uniformly mixed with kaolin mineral and sesbania powder at a mass ratio of 95:4:1, rounded into beads for molding, dried, and then calcined at 550 °C for 9 hours. The calcined beads were subjected to column ion exchange at a temperature of 90 °C for 8 hours using a 0.20 mol / L barium chloride solution. The liquid-solid ratio of the solution to the adsorbent was 40, and the space velocity was 5 h -1It was. The ion exchange degree calculated by the above formula was 99.8%. After the exchange, the beads were dried at 100 °C for 4 hours to obtain adsorbent E.

[0141] The mass ratio of molecular sieve to kaolin mineral in the adsorbent beads was 95.5:4.5. The toluene adsorption capacity of adsorbent E was analyzed to be 179 mg / g, the bulk density based on calcination was 0.845 g / mL, the crushing rate at 130 N was 3.0% by weight, and the mass fraction of charge-balancing cations calculated as metal oxides was 39.8%.

[0142] <Example 1> An appropriate amount of adsorbent A was taken and programmed to be heated to 180 °C in a muffle furnace, and then subjected to fluid dehydration for 2 hours. The mass fraction of water adsorbed on adsorbent A was determined to be 1.84%. 26 mL of the adsorbent was taken and a liquid pulse experiment was carried out to determine its adsorption selectivity, resolution, and the adsorption and desorption rates of m-xylene. The pressure of the liquid pulse experiment was 0.8 MPa, the temperature was 145 °C, and the desorbent used in the experiment was 30% by weight of 1,2,3-trimethylbenzene and 70% by weight of n-heptane. The composition of the pulse feedstock liquid was 5% by weight of p-xylene, m-xylene, o-xylene, ethylbenzene, n-nonane, and 75% by weight of the desorbent, and n-nonane was the tracer.

[0143] The separation factors and resolutions (β MX / EB and R MX / EB , β MX / PX and R MX / PX , β MX / OX and R MX / OX ) between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1, and the pulse spectrum is shown in Figure 2.

[0144] <Example 2> The adsorbent A was programmed to be heated up to 220 °C in a muffle furnace and then subjected to fluidized dehydration for 2 hours. Except for this, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1. As a result of measuring the mass fraction of water adsorbed on the adsorbent A, it was 1.03%.

[0145] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0146] <Example 3> Except that the desorbent used in the experiment was 50 wt% 1,2,3-trimethylbenzene and 50 wt% n-heptane, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1.

[0147] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0148] <Example 4> Except that the desorbent used in the experiment was 80 wt% 1,2,3-trimethylbenzene and 20 wt% n-heptane, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1.

[0149] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0150] <Example 5> Except that the desorbent used in the experiment was 1,2,3-trimethylbenzene, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 2.

[0151] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0152] <Example 6> Except that adsorbent A was programmed to be heated to 230°C in a muffle furnace and then subjected to fluidized dehydration for 2 hours, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1. As a result of determining the mass fraction of water adsorbed on adsorbent A, it was 0.82%.

[0153] The results of separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1, and the pulse spectrum is shown in Figure 3.

[0154] <Example 7> Except that adsorbent A was programmed to be heated to 250°C in a muffle furnace and then subjected to fluidized dehydration for 2 hours, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1. As a result of measuring the mass fraction of water adsorbed on adsorbent A, it was 0.55%.

[0155] The results of separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0156] <Example 8> Except that adsorbent A was programmed to be heated to 280°C in a muffle furnace and then subjected to fluidized dehydration for 2 hours, m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1. As a result of determining the mass fraction of water adsorbed on adsorbent A, it was 0.10%.

[0157] The results of separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0158] <Example 9> Adsorbent A was programmed to be heated to 260 °C in a muffle furnace and then subjected to flowing dehydration for 2 hours, and m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1. As a result of determining the mass fraction of water adsorbed on Adsorbent A, it was 0.26%.

[0159] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1, and the pulse spectrum is shown in Fig. 4.

[0160] <Example 10> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the temperature of the liquid-phase pulse experiment was 130 °C.

[0161] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1, and the pulse spectrum is shown in Fig. 5.

[0162] <Example 11> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1, except that the adsorbent was Adsorbent B.

[0163] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0164] <Example 12> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1, except that the adsorbent was Adsorbent C.

[0165] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene are shown in Table 1.

[0166] <Example 13> The m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1, except that the adsorbent was adsorbent D.

[0167] Table 1 shows the results of separation coefficients and degrees of separation between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0168] <Example 14> The m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 20% tetratoluene and 80% n-octane.

[0169] Table 1 shows the results of separation coefficients and degrees of separation between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0170] <Example 15> The m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 50% pentatoluene and 50% n-decane.

[0171] Table 1 shows the results of separation coefficients and degrees of separation between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0172] <Example 16> The m-xylene in the mixed C8 aromatic hydrocarbons was separated by the method of Example 9, except that the desorbent was 50% 3-ethyl-o-xylene and 50% n-undecane was present.

[0173] Table 1 shows the results of separation coefficients and degrees of separation between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0174] <Example 17> The adsorbent was E, and the composition of the pulse-fed raw material liquid was 5 wt% 2,7-dimethylnaphthalene, 5 wt% 1,6-dimethylnaphthalene, 5 wt% 2,6-dimethylnaphthalene, 5 wt% 1,8-dimethylnaphthalene, 5 wt% n-nonane, and 75 wt% desorbent. Except that n-nonane was a tracer, the separation of metadimethylnaphthalene in the mixed C12 aromatic hydrocarbons was carried out according to the method of Example 1.

[0175] The results of the separation coefficients and separation degrees between 2,7-dimethylnaphthalene and 1,6-dimethylnaphthalene, between 2,6-dimethylnaphthalene, and between 1,8-dimethylnaphthalene are shown in Table 1.

[0176] <Example 18> Except that when the adsorbent was subjected to an ion exchange experiment, the concentration of the exchange liquid was 0.15 mol / L and the exchange degree of the obtained adsorbent E was 78.5%, the separation of metadimethylnaphthalene in the mixed C12 aromatic hydrocarbons was carried out according to the method of Example 17.

[0177] The results of the separation coefficients and separation degrees between 2,7-dimethylnaphthalene and 1,6-dimethylnaphthalene, between 2,6-dimethylnaphthalene, and between 1,8-dimethylnaphthalene are shown in Table 1.

[0178] <Example 19> The composition of the pulse-fed raw material liquid was 10 wt% m-xylene, 10 wt% ethylbenzene, 10 wt% n-nonane, and 70 wt% desorbent. Except that n-nonane was a tracer, the separation of m-xylene in the mixed C8 aromatic hydrocarbons was carried out according to the method of Example 9.

[0179] The results of the separation coefficients and separation degrees between m-xylene and ethylbenzene are shown in Table 1.

[0180] <Comparative Example 1> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 30 wt% toluene and 70 wt% n-heptane.

[0181] Table 1 shows the results of separation factors and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene, and the pulse spectrum is shown in FIG. 6.

[0182] <Comparative Example 2> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 30 wt% tetralin and 70 wt% n-heptane.

[0183] Table 1 shows the results of separation factors and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene, and the pulse spectrum is shown in FIG. 7.

[0184] <Comparative Example 3> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 30 wt% 1,2,4-trimethylbenzene and 70 wt% n-heptane.

[0185] Table 1 shows the results of separation factors and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene, and the pulse spectrum is shown in FIG. 8.

[0186] <Comparative Example 4> m-Xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 1, except that adsorbent A was programmed to be heated to 600 °C in a muffle furnace and dehydrated for 24 hours. As a result of determining the mass fraction of water adsorbed on adsorbent A, it was 0.005%.

[0187] Table 1 shows the results of separation factors and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0188] <Comparative Example 5> m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the adsorption temperature was 95°C.

[0189] Table 1 shows the results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0190] <Comparative Example 6> m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 9, except that the desorbent was 10% by weight of 1,2,3-trimethylbenzene and 90% by weight of n-heptane.

[0191] Table 1 shows the results of the separation coefficients and separation degrees between m-xylene and ethylbenzene, between p-xylene, and between o-xylene.

[0192]

Table 1

[0193] In Examples 1 to 13 of this application, when 1,2,3-trimethylbenzene or a mixture thereof with an alkane was used as a desorbent for the adsorption separation of MX, it can be seen from the test results in Table 1 that the separation effect was improved compared with toluene as a desorbent (Example 1 vs. Comparative Example 1). Components other than MX, ethylbenzene (EB), p-xylene (PX), and o-xylene (OX), could be separated simultaneously with MX. The net retention volumes corresponding to the pulse peaks of the three components were relatively similar, and the separation factors and resolution degrees of the three components from MX were slightly different. This indicates that the interaction forces between the three impurities and the adsorbent were similar and significantly different from the interaction forces between the target component and the adsorbent. Therefore, by designing the process parameters, the three impurities can be removed in the same time period and the same process section. On the other hand, when toluene was used as a desorbent, the three impurities could not be removed in the same time period and the same process section. If they were forcibly removed simultaneously, the control range of the process parameters would become very small, and the accuracy requirements for the process equipment would increase. Therefore, when toluene was used as a desorbent, the efficiency of the entire separation process was lower, the material consumption was greater, and the energy consumption for recycling was also higher. In addition, in this adsorption separation system, the components that are difficult to separate from MX are PX and OX, and the component that is easy to separate is EB. Therefore, whether a high-purity MX product can be obtained depends on the complete removal of the most difficult-to-separate impurities PX and OX. That is, it is necessary to compare the separation factors and resolution degrees between these two components and MX rather than focusing on the removal of the easily separable impurities. Compared with the case where toluene was used as a desorbent, the net retention volumes corresponding to the pulse peaks of PX and OX were significantly reduced. This indicates that in the presence of the 1,2,3-trimethylbenzene desorbent, the adsorption capacity of the adsorbent for PX and OX was significantly weakened, and the separation of PX and OX from MX was easier than when toluene was used as a desorbent.The separation factor and resolution are larger, the separation effect is better, the speed of the entire separation process is faster, the amount of material used is less, and the energy consumption for recycling is less.

[0194] The test results of Examples 14 to 18 show that the present application can also be applied to the separation of other meta-aromatic hydrocarbons such as metadimethylnaphthalene, and other alkylbenzene compounds conforming to the general formula (I) such as tetratoluene, pentatoluene, and 3-ethyl-o-xylene can also be used in the present application.

[0195] <Example 20> With 2116 g of adsorbent filling and a water content of 0.26%, Adsorbent A was used. A simulated moving bed adsorption separation device was used to separate m-xylene in the mixed C8 aromatic hydrocarbons. Here, the mixed C8 aromatic hydrocarbon feedstock contained 1.5 wt% non-aromatic, 0.5 wt% benzene, 0.9 wt% toluene, 48.1 wt% m-xylene, 20.2 wt% p-xylene, 18.9 wt% o-xylene, 9.8 wt% ethylbenzene, and 0.1 wt% C9+ aromatic.

[0196] The simulated moving bed device was composed of 24 columns connected in series. The cavity inside the column for accommodating the adsorbent had a height of 200 mm and a diameter of 40 mm. The 24th column was connected to the 1st column via a pump for circulating the fluid inside the column. Materials could be introduced or discharged at the connection positions of each column. There were 7 columns between the raffinate outlet, which was the adsorption zone, and the feedstock inlet. There were 9 columns between the feedstock inlet, which was the purification zone, and the extract outlet. There were 5 columns between the extract outlet, which was the desorption zone, and the desorbent inlet. There were 3 columns between the desorbent inlet, which was the isolation zone, and the raffinate outlet. The positions of the inlets and outlets of each material flow are shown in Figure 9. The positions of the inlets and outlets of the materials were changed according to the step time. The inlets and outlets were moved forward by one column every step time. The inlets and outlets were moved from the positions of the solid-line arrows in the figure to the positions of the dotted-line arrows. In the next step time, it moved forward in the set direction. Until the inlets and outlets returned to the starting positions, which was one cycle, the positions of the inlets and outlets were sequentially changed in the same manner. One step time was 80 seconds, and one cycle was 32 minutes. After the simulated moving bed was stably operated, mixed samples of the extract and mixed samples of the raffinate were taken for one layout of the cycle, and their compositions were analyzed. According to the analysis results, the calculation method for the purity and yield of m-xylene is

[0197] [Number]

[0198] where X is the mass fraction of each component in the extract,

[0199] [Number]

[0200] where X m-キシレン、抽出物 is the mass fraction of m-xylene in the extract, Q 抽出物 is the mass flow rate of the extract, Xm-キシレン , ラフィネート is the mass fraction of m-xylene in the raffinate, and Q ラフィネート is the mass flow rate of the raffinate.

[0201] The temperature of the adsorption bed layer was controlled at 145 °C, and the operating pressure was 0.90 MPa. The desorbent was 93% by weight of 1,2,3-trimethylbenzene (purchased from Xilong Chemical Reagent Company, CAS: 526-73-8). The supply raw material supply rate was 0.36 kg / h, the desorbent injection rate was 1.79 kg / h, the extract rate was 0.84 kg / h, the raffinate rate was 1.31 kg / h, and the local flow rate in the purification zone was 2.85 kg / h. The mass flow ratio of the desorbent to the C8 aromatic hydrocarbon feedstock flowing into the simulated moving bed was 4.97, and the C8 aromatic hydrocarbon feedstock rate per unit mass of the adsorbent was 0.17 kg / (h·kg adsorbent). The number of adsorption bed layers in the simulated moving bed adsorption separation device was 24, and the number of bed layers in the adsorption zone, purification zone, desorption zone, and isolation zone were 7, 9, 5, and 3, respectively. The step time was 80 seconds, and one cycle period was 32 minutes. After adsorption separation, the yield of m-xylene was 96.25% by weight, and the purity was 99.65% by weight. The desorbent accounted for 81.11% by weight in the extract and 84.23% by weight in the raffinate. Based on the composition of the extract and the raffinate, the theoretical number of trays, top condensation load, and bottom heating load of the distillation column were calculated by using the RadFrac module of AspenPlus software. With an industrial adsorption separation device having an annual production capacity of 200,000 tons of m-xylene, the desorbent 1,2,3-trimethylbenzene was recovered at the top of the extract column in the extract and at the bottom of the raffinate column, respectively. The simulation calculation results showed that the extract flow rate was 124 t / h, the raffinate flow rate was 202 t / h, the mass fraction of the recovered desorbent after separation reached 99.995%, the mass fraction of the desorbent in the m-xylene product at the top or other C8 aromatic hydrocarbons was 0.01%, and the heat loads of the bottoms of the extract distillation column and the raffinate distillation column were 11.8 Gcal / h and 18.2 Gcal / h, respectively.

[0202] <Comparative Example 7> Except that the desorbent was 99 wt% toluene (purchased from Inokai Technology Co., Ltd., CAS: 108-88-3), m-xylene in the mixed C8 aromatic hydrocarbons was separated according to the method of Example 20. Under the same operating conditions, the local flow rate of the purification zone was 2.90 kg / h, the yield of m-xylene was 95.55 wt%, and the purity was 99.50 wt%. The desorbent toluene was recovered at the top of the extractive distillation column and at the top of the raffinate distillation column, respectively. The simulation calculation results showed that the heat loads of the extractive distillation column and the raffinate distillation column were 27.6 Gcal / h and 35.8 Gcal / h, respectively.

[0203] By comparing the separation purity and yield results of Example 20 and Comparative Example 7, it can be seen that when 1,2,3-trimethylbenzene is used as the desorbent, the separation of components (PX and OX) that are more difficult to separate from the target component MX is easier than when toluene is used as the desorbent, which is beneficial for the purification of MX in the purification zone of the simulated moving bed. At the same time, the required local flow rate of the purification zone is reduced by about 10% to a certain extent, that is, a reduction in material consumption, saving the cost of purchasing materials and the cost of recycling. The purity and yield of the final target component MX also increase accordingly, the purity increases by 0.1 percentage point, and the yield increases by 0.75 percentage point, resulting in an improvement in the MX separation efficiency in industrial equipment, an increase in the amount of processed feedstock, and a reduction in operating costs. The boiling point of 1,2,3-trimethylbenzene is higher than that of the target component MX. When 1,2,3-trimethylbenzene is used as the desorbent, 1,2,3-trimethylbenzene is recovered at the bottom of the extractive and raffinate distillation columns for continuous recycling. Therefore, compared with the case where toluene is used as the desorbent and recovered at the top of the column, the required bottom heat load is significantly reduced, the heat load of the extractive distillation column is reduced by 57%, the heat load of the raffinate distillation column is reduced by 49%, and the energy consumption of the device is significantly reduced.

[0204] The preferred embodiments of the present application have been described in detail above. However, the present application is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present application, various simple modifications may be made to the technical solutions of the present application, and all of these simple modifications fall within the protection scope of the present application.

[0205] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. To avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0206] In addition, various embodiments of the present application may be arbitrarily combined, and as long as they do not conflict with the concept of the present application, they should also be regarded as the content invented in the present application.

Brief Description of the Drawings

[0207]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Claims

1. A liquid material comprising or consisting of 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5 to C14 saturated aliphatic hydrocarbon, is used as a desorbent for the adsorption and separation of one or more meta-aromatic hydrocarbons. 【Chemistry 1】 R １ And, R ２ And, R ３ This means that C may be the same or different. １－４ Selected independently of the alkyl chain, Preferably, R １ And, R ２ And, R ３ And, at least one of them is methyl, More preferably, at least two of them are methyl, More preferably, all of them are methyl, R ４ and R ５ and R ６ may be the same or different, and are independently selected from hydrogen, C １－４ saturated hydrocarbon group, C １－４ alkoxy group, and halogen Preferably, R ４ And, R ５ And, R ６ And at least one of them is hydrogen, or C １－４ It is a saturated hydrocarbon group, for example, R ４ , or R ６ C １－４ It is a saturated hydrocarbon group, More preferably, at least two of them independently contain hydrogen or C １－４ It is a saturated hydrocarbon group, for example, R ４ And, R ６ In all cases, C １－４ It is a saturated hydrocarbon group, More preferably, these three are independently hydrogen or C １－４ It is a saturated hydrocarbon group, Particularly preferably, all three are hydrogen. Said C １－４ The saturated hydrocarbon group is preferably a methyl group.

2. The adsorption separation includes the steps of separating one or more meta-aromatic hydrocarbons from a mixed aromatic hydrocarbon supply material containing one or more meta-aromatic hydrocarbons and at least one isomer thereof by adsorption and desorption. The one or more meta-aromatic hydrocarbons are preferably one or more C8-C12 meta-aromatic hydrocarbons, more preferably C8-C12 metaalkyl aromatic hydrocarbons, such as m-xylene or 2,7-dimethylnaphthalene. More preferably, the mixed aromatic hydrocarbon feedstock is m-xylene and, At least one other C8 aromatic hydrocarbon selected from p-xylene, o-xylene, and ethylbenzene, It is a mixed C8 aromatic hydrocarbon supply material containing, More preferably, the mixed C8 aromatic hydrocarbon supply material contains 5 to 95% by weight of m-xylene, according to claim 1.

3. The aforementioned meta-aromatic hydrocarbon is m-xylene, The mixed aromatic hydrocarbon feedstock comprises 5 to 94% by weight of m-xylene and 6 to 95% by weight of p-xylene. Preferably, the use according to claim 2 comprises 5 to 90% by weight of m-xylene and 10 to 95% by weight of p-xylene.

4. The adsorbent used in the adsorption separation contains at least 90% by weight of a Y-type molecular sieve as an active ingredient, and the Y-type molecular sieve has a silicon oxide / aluminum oxide molar ratio of 4.0 to 6.0, preferably 4.3 to 5.

7. More preferably, the adsorbent contains one or more of the Group IA metal ions, Group IIA metal ions, and Group IB metal ions, for example, one or two, as charge-balanced cations. The aforementioned Group IA metal ion is preferably Li ＋ , and Na ＋ Selected from, The aforementioned Group IIA metal ion is preferably Mg ２＋ , Sr ２＋ , and Ba ２＋ Selected from, The aforementioned Group IB metal ion is preferably Ag ＋ And, Preferably, the total amount of Group IA metals, Group IIA metals, and Group IB metals in the adsorbent is calculated as metal oxides and is 10 to 45%, preferably 10 to 40%, based on the total weight of the adsorbent. More preferably, the adsorbent contains 0.05 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.05 to 0.8% by weight, and even more preferably 0.1 to 0.5% by weight of adsorbed water. Particularly preferred is the use according to claim 2, wherein the adsorbent contains at least 90% by weight of NaY-type molecular sieve as an active ingredient, and is preferably treated by metal ion exchange to have a metal ion exchange degree of 78.0 to 99.9%.

5. Based on the total amount of the liquid material, the liquid material is, 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight, of an alkane selected from C5 to C14 linear alkanes, preferably selected from C6 to C10 linear alkanes, The use according to claim 2, which includes or consists of

6. In equation (I), R １ And, R ２ And, R ３ At least two of them are methyl, R ４ And, R ５ And, R ６ This is independent of hydrogen, or C １－４ It is a saturated hydrocarbon group, and at least one of them is hydrogen. Preferably, R ４ And, R ５ And, R ６ At least two of these are hydrogen, and the C １－４ The saturated hydrocarbon group is methyl, The use according to claim 2, more preferably, the alkylbenzene compound is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, and preferably 1,2,3-trimethylbenzene or 1,2,3,4-tetramethylbenzene.

7. The aforementioned meta-aromatic hydrocarbon is m-xylene, The mixed aromatic hydrocarbon feedstock comprises 20 to 60% by weight of m-xylene, 10 to 30% by weight of p-xylene, 10 to 30% by weight of o-xylene, and 5 to 20% by weight of ethylbenzene. The alkylbenzene compound is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene. Based on the total amount of the liquid material, the liquid material comprises 30 to 70% by weight of the alkylbenzene compound and 30 to 70% by weight of an alkane selected from C5 to C14 linear alkanes. The charge-balanced cation of the adsorbent is Na ＋ , Sr ２＋ Ba ２＋ , and Ag ＋ The use according to claim 4, wherein the adsorbent is selected from and contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight, of adsorbed water.

8. A method for separating one or more meta-aromatic hydrocarbons from a mixed aromatic hydrocarbon feedstock containing the one or more meta-aromatic hydrocarbons and their isomers, 1) A step of bringing the mixed aromatic hydrocarbon supply material into contact with an adsorbent to adsorb one or more meta-aromatic hydrocarbons, thereby obtaining a raffinate containing the adsorbent on which the one or more meta-aromatic hydrocarbons have been adsorbed and the components that were not adsorbed; 2) A step of bringing the adsorbent obtained in step 1) on which the one or more meta-aromatic hydrocarbons have been adsorbed into contact with a desorbing agent to desorb the one or more meta-aromatic hydrocarbons, thereby obtaining an extract containing the one or more meta-aromatic hydrocarbons and the desorbing agent; 3) A step of subjecting the extract obtained in step 2) to rectification separation to obtain one or more meta-aromatic hydrocarbons and the desorbing agent; Includes, Based on the total amount of the desorbent, the desorbent comprises or consists of 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of one or more C5-C14 saturated aliphatic hydrocarbons. 【Chemistry 2】 R １ And, R ２ And, R ３ This means that C may be the same or different. １－４ Selected independently of the alkyl chain, Preferably, R １ And, R ２ And, R ３ And, at least one of them is methyl, More preferably, at least two of them are methyl, More preferably, all of them are methyl, R ４ And, R ５ And, R ６ These may be the same or different, and include hydrogen and C. １－４ Saturated hydrocarbon group, C １－４ Selected independently from alkoxy groups and halogens, Preferably, R ４ And, R ５ And, R ６ And at least one of them is hydrogen, or C １－４ It is a saturated hydrocarbon group, for example, R ４ , or R ６ C １－４ It is a saturated hydrocarbon group, More preferably, at least two of them independently contain hydrogen or C １－４ It is a saturated hydrocarbon group, for example, R ４ And, R ６ In all cases, C １－４ It is a saturated hydrocarbon group, More preferably, these three are independently hydrogen or C １－４ It is a saturated hydrocarbon group, Particularly preferably, all three are hydrogen. The method wherein the alkyl group is preferably methyl.

9. The meta-aromatic hydrocarbon is a C8-C12 meta-aromatic hydrocarbon, preferably a C8-C12 metaalkyl aromatic hydrocarbon, such as m-xylene or 2,7-dimethylnaphthalene. Preferably, the mixed aromatic hydrocarbon feedstock is m-xylene and, At least one other C8 aromatic selected from p-xylene, o-xylene, and ethylbenzene, It is a mixed C8 aromatic hydrocarbon supply material containing, More preferably, the method according to claim 8, wherein the mixed C8 aromatic hydrocarbon supply material contains 5 to 95% by weight of m-xylene.

10. The aforementioned meta-aromatic hydrocarbon is m-xylene, The aforementioned mixed aromatic hydrocarbon supply material comprises 5 to 94% by weight of m-xylene and 6 to 95% by weight of p-xylene, Preferably, the method according to claim 9, comprising 5 to 90% by weight of m-xylene and 10 to 95% by weight of p-xylene.

11. Based on the total amount of the desorbent, the desorbent is 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight, of an alkane selected from C5 to C14 linear alkanes, preferably selected from C6 to C10 linear alkanes, The method according to claim 8, comprising or comprising

12. In equation (I), R １ And, R ２ And, R ３ At least two of them are methyl, R ４ And, R ５ And, R ６ This is independent of hydrogen, or C １－４ It is a saturated hydrocarbon group, and at least one of them is hydrogen. Preferably, R ４ And, R ５ And, R ６ At least two of these are hydrogen, and the C １－４ The saturated hydrocarbon group is methyl, The method according to claim 8, more preferably, the alkylbenzene compound is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, and preferably 1,2,3-trimethylbenzene or 1,2,3,4-tetramethylbenzene.

13. The adsorbent used in step 1) contains at least 90% by weight of a Y-type molecular sieve as an active ingredient, and the Y-type molecular sieve has a silicon dioxide / aluminum oxide molar ratio of 4.0 to 6.0, preferably 4.3 to 5.

7. Preferably, the adsorbent contains one or more of the Group IA metal ions, Group IIA metal ions, and Group IB metal ions, for example, one or two, as charge-balanced cations. The aforementioned Group IA metal ion is preferably Li ＋ , and Na ＋ Selected from, The aforementioned Group IIA metal ion is preferably Mg ２＋ , Sr ２＋ , and Ba ２＋ Selected from, The aforementioned Group IB metal ion is preferably Ag ＋ And, Preferably, the total amount of Group IA metals, Group IIA metals, and Group IB metals in the adsorbent is calculated as metal oxides and is 10 to 45% based on the total amount of the adsorbent. More preferably, the crystal size of the Y-type molecular sieve is 0.5 to 2.0 μm, preferably 0.8 to 1.2 μm. The method according to claim 8, more preferably, the adsorbent contains at least 90% by weight of a NaY-type molecular sieve as an active ingredient, and is preferably treated by metal ion exchange to obtain a metal ion exchange degree of 78.0 to 99.9%.

14. The method according to claim 13, wherein the adsorbent contains 0.05 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.05 to 0.8% by weight, and even more preferably 0.1 to 0.5% by weight of adsorbed water.

15. The aforementioned meta-aromatic hydrocarbon is m-xylene, The mixed aromatic hydrocarbon feedstock comprises 20 to 60% by weight of m-xylene, 10 to 30% by weight of p-xylene, 10 to 30% by weight of o-xylene, and 5 to 20% by weight of ethylbenzene. The alkylbenzene compound is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene. Based on the total amount of the liquid material, the liquid material comprises 30 to 70% by weight of the alkylbenzene compound and 30 to 70% by weight of an alkane selected from C5 to C14 linear alkanes. The charge-balancing cation of the adsorbent is Na ＋ , Sr ２＋ , Ba ２＋ , and Ag ＋ selected from, and the adsorbent contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight of adsorbed water, the method according to claim 13.

16. The operating conditions for the adsorption in step 1) and the desorption in step 2) are: A temperature of 100 to 190°C, preferably 110 to 180°C, more preferably 120 to 160°C. and / or, A pressure of 0.6 to 1.6 MPa, preferably 0.8 to 1.0 MPa. The method according to claim 8, comprising each of independently.

17. Steps 1) and 2) are performed by using a simulated moving floor. The aforementioned pseudo-movable floor comprises multiple adsorbent floor layers filled with an adsorbent, Each floor layer is equipped with an inlet conduit and an outlet conduit for the corresponding material. The material flowing into the simulated moving bed and flowing out of the simulated moving bed divides the adsorption bed layer within it into a desorption zone, a purification zone, an adsorption zone, and an isolation zone. The adsorption bed layer between the desorbent injection position and the extract discharge position is the desorption zone. The adsorption bed layer between the extract discharge position and the raw material injection position is the purification zone. The adsorption bed layer between the raw material injection position and the raffinate discharge position is the adsorption zone. The adsorption bed layer between the raffinate discharge position and the desorbent injection position is the isolation zone. Preferably, the ratio of the number of floor layers in the adsorption zone, purification zone, desorption zone, and isolation zone within the pseudo-mobile bed is 25±10%:38±15%:25±5%:12±4%. More preferably, the mass flow rate ratio of the desorbent to the supply material flowing into the pseudo-moving bed is 0.01 to 6.0, preferably 0.01 to 5.5, and more preferably 0.01 to 5.

0. More preferably, the flow rate of the supply material flowing into the pseudo-moving bed relative to the unit mass of the adsorbent is in the range of 0.1 to 8 kg / (h·kg adsorbent), preferably 0.15 to 8 kg / (h·kg adsorbent), and more preferably 0.17 to 8 kg / (h·kg adsorbent). The method according to claim 8, wherein the cycle period of the pseudo-moving bed is particularly preferably 12 to 70 minutes, preferably 20 to 40 minutes.

18. A kit of adsorption / desorption agents comprising a solid adsorbent and a liquid desorbent, The solid adsorbent contains at least 90% by weight of a Y-type molecular sieve as an active ingredient, and the Y-type molecular sieve has a silicon oxide / aluminum oxide molar ratio of 4.0 to 6.0, preferably 4.3 to 5.

7. The liquid deconjugate comprises, or consists of, 20 to 100% by weight of an alkylbenzene compound of the following general formula (I) and 0 to 80% by weight of a C5-C14 saturated aliphatic hydrocarbon. 【Transformation 3】 R １ And, R ２ And, R ３ This means that C may be the same or different. １－４ Selected independently of the alkyl chain, Preferably, R １ and R ２ and R ３ and at least one of them is methyl, More preferably, at least two of them are methyl, More preferably, all of them are methyl, R ４ And, R ５ And, R ６ These may be the same or different, and include hydrogen and C. １－４ Saturated hydrocarbon group, C １－４ Selected independently from alkoxy groups and halogens, Preferably, R ４ And, R ５ And, R ６ And at least one of them is hydrogen, or C １－４ It is a saturated hydrocarbon group, for example, R ４ , or R ６ C １－４ It is a saturated hydrocarbon group, More preferably, at least two of them independently contain hydrogen or C １－４ It is a saturated hydrocarbon group, for example, R ４ And, R ６ In all cases, C １－４ It is a saturated hydrocarbon group, More preferably, these three are independently hydrogen or C １－４ It is a saturated hydrocarbon group, Particularly preferably, all three are hydrogen. The aforementioned alkyl group is preferably methyl, in the kit.

19. Based on the total amount of the liquid desorbent, the desorbent is 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 30 to 50% by weight of the alkylbenzene compound, 5 to 70% by weight, preferably 20 to 70% by weight, more preferably 50 to 70% by weight, of an alkane selected from C5 to C14 linear alkanes, preferably selected from C6 to C10 linear alkanes, The kit according to claim 18, comprising or consisting of

20. In equation (I), R １ And, R ２ And, R ３ At least two of them are methyl, R ４ And, R ５ And, R ６ This is independent of hydrogen, or C １－４ It is a saturated hydrocarbon group, and at least one of them is hydrogen. Preferably, R ４ And, R ５ And, R ６ At least two of these are hydrogen, and the C １－４ The saturated hydrocarbon group is methyl, The kit according to claim 18, more preferably, the alkylbenzene compound is selected from 1,2,3-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,4,5-pentamethylbenzene, and 3-ethyl-o-xylene, and preferably 1,2,3-trimethylbenzene or 1,2,3,4-tetramethylbenzene.

21. The adsorbent contains one or more of the following metal ions: Group IA, Group IIA, and Group IB, preferably one or two, as charge-balanced cations. The aforementioned Group IA metal ion is preferably Li ＋ , and Na ＋ Selected from, The aforementioned Group IIA metal ion is preferably Mg ２＋ , Sr ２＋ , and Ba ２＋ Selected from, The aforementioned Group IB metal ion is preferably Ag ＋ And, Preferably, the total amount of Group IA metals, Group IIA metals, and Group IB metals in the adsorbent is calculated as metal oxides and is 10 to 45% based on the total amount of the adsorbent. Preferably, the crystal size of the Y-type molecular sieve in the solid adsorbent is 0.5 to 2.0 μm, preferably 0.8 to 1.2 μm. More preferably, the adsorbent contains 0.05 to 2% by weight, preferably 0.05 to 1% by weight, more preferably 0.05 to 0.8% by weight, and even more preferably 0.1 to 0.5% by weight of adsorbed water. The kit according to claim 18, more preferably, the adsorbent contains at least 90% by weight of a NaY-type molecular sieve as an active ingredient, and is preferably treated by metal ion exchange to achieve a metal ion exchange degree of 78.0 to 99.9%.

22. Based on the total amount of the liquid desorbent, the liquid desorbent comprises 30 to 50% by weight of the alkylbenzene compound and 50 to 70% by weight of an alkane selected from C5 to C14 linear alkanes. The charge-balanced cation of the solid adsorbent is Na ＋ , Sr ２＋ Ba ２＋ , and Ag ＋ The kit according to claim 21, wherein the adsorbent is selected from and contains 0.05 to 0.8% by weight, preferably 0.1 to 0.5% by weight, of adsorbed water.

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