Near-boiling-point mixture separation system and method based on coupling of porous adsorption material and membrane contactor

Abstract

The invention provides a near-boiling-point mixture separation system and method based on coupling of a porous adsorption material and a membrane contactor. The system comprises a near-boiling-point mixture storage tank, a first target product storage tank, a second target product storage tank, the membrane contactor, a poor porous adsorption material slurry storage tank, a rich porous adsorption material slurry storage tank and a desorption tower. The membrane contactor comprises a plurality of hollow fiber membrane modules and is provided with a slurry inlet, a slurry outlet, a raw material inlet and a separated product outlet; the near-boiling-point mixture storage tank is communicated with the raw material inlet, the poor-porous adsorption material slurry storage tank is communicated with the slurry inlet, the slurry outlet is communicated with an inlet of the desorption tower through the rich-porous adsorption material slurry storage tank, and a desorption product outlet and a liquid phase outlet of the desorption tower are respectively communicated with the second target product storage tank and the poor-porous adsorption material slurry storage tank; and the separated product outlet is communicated with the first target product storage tank. The system and the method have the advantages of high separation efficiency, low energy consumption, continuous operation and the like.

Description

Technical Field

[0001] The present invention relates to a separation system and method for near-boiling-point mixtures based on the coupling of porous adsorbents and membrane contactors, belonging to the technical field of chemical separation. Background Art

[0002] In many chemical industrial fields such as petrochemical industry, fine chemical separation, and new energy materials, the efficient separation of near-boiling-point mixtures with a boiling point difference less than 5°C (such as C4-C6 alkane isomers, xylene isomers, etc.) has become a common technical problem in the industry.

[0003] Rectification, as an important separation technology, realizes the separation of mixtures by multiple partial vaporizations and partial condensations, utilizing the differences in the volatilities of each component. However, for systems with a relative volatility α≈1.0 - 1.5 (such as n-hexane / methylcyclopentane), multi-stage rectification towers in series operation are required, and the number of theoretical plates exceeds 100, resulting in high equipment investment costs and extremely high energy consumption.

[0004] Membrane separation technology, as an efficient separation means, realizes the separation of mixtures through the selective transport of a selective permeable membrane, utilizing the differences in molecular size, polarity, or diffusion coefficient, etc. among each component. Although existing polymer membranes (such as polyimide gas separation membranes) can achieve phase-free separation, their separation factors are generally lower than 1.5 (such as for the p-xylene / o-xylene system), and the problem of flux decay caused by membrane fouling is prominent (the flux drops by more than 40% after operating for 120 h).

[0005] Porous materials have shown unique properties in the fields of adsorption and separation. However, molecular sieve adsorbents (such as 5A molecular sieve, etc.) can achieve selective adsorption through pore size sieving, but fixed-bed adsorption devices have problems such as low adsorbent regeneration efficiency (frequent bed layer switching is required), slow dynamic mass transfer rate (contact time > 30 min), and easy pipeline blockage. More seriously, the adsorption selectivity coefficients of traditional adsorbents for near-boiling-point mixture components are difficult to meet the requirements of industrial-scale separation.

[0006] It is worth noting that metal-organic framework materials (MOFs) show potential in the field of molecular recognition due to their adjustable pore size and surface chemical properties. CN113680172A discloses a capture agent for hydrocarbon gases and a separation method for near-boiling-point gases. However, in industrial applications, it is difficult to achieve continuous adsorption-regeneration operation, and frequent start-stop accelerates the mechanical wear of key components such as valves and pumps, increasing the maintenance cost. At the same time, this capture agent and method are only applicable to the separation of gas mixtures and cannot be directly applied to the separation of liquid near-boiling-point mixtures.

[0007] In view of the above problems, there is an urgent need to develop a separation system and method for near-boiling point mixtures based on the coupling of porous adsorption materials and membrane contactors, which integrates high separation efficiency, low energy consumption, and continuous operation. Summary of the Invention

[0008] In order to solve the above-mentioned disadvantages and deficiencies, the purpose of the present invention is to provide a separation system and method for near-boiling point mixtures based on the coupling of porous adsorption materials and membrane contactors. The system and method provided by the present invention can at least solve the problems existing in the existing separation technologies for near-boiling point mixtures, such as low efficiency, high energy consumption, complex equipment, and high cost, and have many advantages such as high separation efficiency, low energy consumption, and continuous operation.

[0009] To achieve the above object, on the one hand, the present invention provides a separation system for near-boiling point mixtures based on the coupling of porous adsorption materials and membrane contactors, wherein the system includes:

[0010] A near-boiling point mixture storage tank, a first target product storage tank, a second target product storage tank, a membrane contactor, a lean porous adsorption material slurry storage tank, a rich porous adsorption material slurry storage tank, and a desorption tower;

[0011] The membrane contactor includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell body and an upper end cover and a lower end cover respectively provided at the upper and lower ends of the shell body. The plurality of hollow fiber membrane modules are arranged in the shell body in a manner parallel to the central axis of the shell body, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover; the upper end cover and the lower end cover are respectively provided with a first opening and a second opening, and the lower and upper parts of the outer side wall of the shell body are respectively provided with a third opening and a fourth opening;

[0012] The near-boiling point mixture storage tank is communicated with the third opening through a pipeline, the lean porous adsorption material slurry storage tank is communicated with the first opening through a pipeline, the second opening is communicated with the inlet of the desorption tower through a pipeline via the rich porous adsorption material slurry storage tank, the desorption product outlet and the liquid phase outlet of the desorption tower are communicated with the second target product storage tank and the lean porous adsorption material slurry storage tank respectively through pipelines, and the fourth opening is communicated with the first target product storage tank through a pipeline;

[0013] Or the near-boiling point mixture storage tank is communicated with the second opening through a pipeline, the lean porous adsorption material slurry storage tank is communicated with the fourth opening through a pipeline, the third opening is communicated with the inlet of the desorption tower through a pipeline via the rich porous adsorption material slurry storage tank, the desorption product outlet and the liquid phase outlet of the desorption tower are communicated with the second target product storage tank and the lean porous adsorption material slurry storage tank respectively through pipelines, and the first opening is communicated with the first target product storage tank through a pipeline.

[0014] In the system of the present invention described above, when the near-boiling-point mixture storage tank is connected to the third opening through a pipeline, the lean porous adsorbent slurry storage tank is connected to the first opening through a pipeline, the second opening is connected to the inlet of the desorption tower through a pipeline via the rich porous adsorbent slurry storage tank, the desorption product outlet and the liquid phase outlet of the desorption tower are connected to the second target product storage tank and the lean porous adsorbent slurry storage tank respectively through pipelines, and the fourth opening is connected to the first target product storage tank through a pipeline, the third opening (raw material inlet) and the fourth opening (separation product outlet) are both connected to the space outside the fibers inside the shell, while the first opening (slurry inlet) and the second opening (slurry outlet) are both connected to the inside of the hollow fiber membrane module, that is, the space inside the fibers; correspondingly, in the first case, the near-boiling-point mixture and the lean porous adsorbent slurry enter the space outside the fibers and the space inside the fibers of the membrane contactor respectively according to the principle that the near-boiling-point mixture enters from the bottom, the target product exits from the top, and the slurry enters from the top and exits from the bottom.

[0015] When the near-boiling-point mixture storage tank is connected to the second opening through a pipeline, the lean porous adsorbent slurry storage tank is connected to the fourth opening through a pipeline, the third opening is connected to the inlet of the desorption tower through a pipeline via the rich porous adsorbent slurry storage tank, the desorption product outlet and the liquid phase outlet of the desorption tower are connected to the second target product storage tank and the lean porous adsorbent slurry storage tank respectively through pipelines, and the first opening is connected to the first target product storage tank through a pipeline,

[0016] the second opening (raw material inlet) and the first opening (separation product outlet) are both connected to the inside of the hollow fiber membrane module, that is, the space inside the fibers, and the fourth opening (slurry inlet) and the third opening (slurry outlet) are both connected to the space outside the fibers inside the shell; correspondingly, in the second case, the near-boiling-point mixture and the lean porous adsorbent slurry also enter the space inside the fibers and the space outside the fibers of the membrane contactor respectively according to the principle that the near-boiling-point mixture enters from the bottom, the target product exits from the top, and the slurry enters from the top and exits from the bottom.

[0017] The system of the present invention described above is preferably arranged according to the first case, that is, preferably, the near-boiling-point mixture storage tank is connected to the third opening through a pipeline, the lean porous adsorbent slurry storage tank is connected to the first opening through a pipeline, the second opening is connected to the inlet of the desorption tower through a pipeline via the rich porous adsorbent slurry storage tank, the desorption product outlet and the liquid phase outlet of the desorption tower are connected to the second target product storage tank and the lean porous adsorbent slurry storage tank respectively through pipelines, and the fourth opening is connected to the first target product storage tank through a pipeline. At this time, the near-boiling-point mixture and the lean porous adsorbent slurry enter the space outside the fibers and the space inside the fibers of the membrane contactor respectively according to the principle that the near-boiling-point mixture enters from the bottom, the target product exits from the top, and the slurry enters from the top and exits from the bottom.

[0018] Under normal circumstances, the viscosity of the lean porous adsorbent slurry must be greater than that of the near-boiling mixture. Therefore, it is more conducive to the flow of the slurry and more energy-efficient to make the near-boiling mixture enter from the bottom, the target product exit from the top, and the slurry enter from the top and exit from the bottom.

[0019] As a specific embodiment of the system described above of the present invention, wherein the near-boiling mixture storage tank is connected to the third opening or the second opening through a pipeline via a first feed pump or a pressure reducing valve and a flow controller in sequence, and at this time, both the third opening or the second opening are used as raw material inlets.

[0020] As a specific embodiment of the system described above of the present invention, wherein the fourth opening or the first opening is connected to the first target product storage tank through a pipeline via a first back pressure valve and a first flow meter in sequence, and at this time, both the fourth opening or the first opening are used as separation product outlets.

[0021] As a specific embodiment of the system described above of the present invention, wherein the second opening or the third opening is connected to the inlet of the rich porous adsorbent slurry storage tank through a pipeline via a second back pressure valve, the outlet of the rich porous adsorbent slurry storage tank is connected to the inlet of the desorption tower through a pipeline via a second feed pump, the desorption product outlet of the desorption tower is connected to the second target product storage tank through a pipeline via a third back pressure valve, a second flow meter and a water ring vacuum pump in sequence, the liquid phase outlet of the desorption tower is connected to the inlet of the lean porous adsorbent slurry storage tank through a pipeline via a transfer pump, and the outlet of the lean porous adsorbent slurry storage tank is connected to the first opening or the fourth opening through a pipeline via a third feed pump. At this time, both the second opening or the third opening are used as slurry outlets, and both the first opening or the fourth opening are used as slurry inlets.

[0022] As a specific embodiment of the system described above of the present invention, wherein the materials of the multiple hollow fiber membrane modules include one or a combination of several of polypropylene (PP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), etc.

[0023] As a specific embodiment of the system described above of the present invention, wherein the inner diameters of the multiple hollow fiber membrane modules are 0.1 - 5 mm, the wall thicknesses are 0.01 - 2 mm, the porosities are 40 - 80%, and the pore size distributions are 0.01 - 5 μm.

[0024] Theoretically, the present invention does not make specific requirements on the number of the hollow fiber membrane modules, and can be reasonably selected and adjusted as needed. For example, the number of the hollow fiber membrane modules can be about several tens to 100. As the membrane contactor is scaled up, the number of the hollow fiber membrane modules also increases, and can be up to about 1000, or even as high as about 10000.

[0025] As a specific embodiment of the above-described system of the present invention, a stirring device is provided inside the desorption tower. This stirring device can be an existing conventional stirring device and can be reasonably selected as needed. For example, in some specific embodiments of the present invention, this stirring device can be a stirring paddle or the like.

[0026] On the other hand, the present invention also provides a method for separating a near-boiling-point mixture based on the coupling of a porous adsorbent material and a membrane contactor, which is realized by using the above-described system for separating a near-boiling-point mixture based on the coupling of a porous adsorbent material and a membrane contactor. Wherein, the method includes:

[0027] Step (1): Feed the near-boiling-point mixture into the outer space or inner space of the fibers inside the shell, and feed the porous adsorbent material slurry into the inner space or outer space of the fibers inside the shell. Under the pressure difference between the near-boiling-point mixture side and the porous adsorbent material slurry side, a part of the target components in the near-boiling-point mixture pass through the wall of the hollow fiber membrane module into the inner space or outer space of the fibers and are selectively adsorbed by the porous adsorbent material, obtaining a rich porous adsorbent material slurry, while another part of the target components in the near-boiling-point mixture are discharged from the outer space or inner space of the fibers;

[0028] Step (2): Feed the rich porous adsorbent material slurry into the desorption tower and heat it to desorb the target components in the rich porous adsorbent material slurry and discharge and collect them from the desorption product outlet. After desorption is completed, collect and recycle the obtained lean porous adsorbent material slurry.

[0029] As a specific embodiment of the above-described method of the present invention, the near-boiling-point mixture includes a near-boiling-point mixture with a relative volatility α between 1.0 and 1.5.

[0030] As a specific embodiment of the above-described method of the present invention, the near-boiling-point mixture contains at least two target components.

[0031] As a specific embodiment of the above-described method of the present invention, the near-boiling-point mixture is C4-C6 alkane isomers or the like.

[0032] As a specific embodiment of the above-described method of the present invention, the near-boiling-point mixture includes any one group of n-hexane and methylcyclopentane, n-hexane and 2-methylpentane, n-hexane and 3-methylpentane, n-pentane and isopentane, and n-butane and isobutane, etc.

[0033] As a specific embodiment of the above-described method of the present invention, the near-boiling-point mixture is in a gaseous or liquid phase, that is, the system and method of the present invention can feed the near-boiling-point mixture in a gaseous state or in a liquid state.

[0034] As a specific embodiment of the method described above in the present invention, the porous adsorbent material slurry is a solid-liquid suspension slurry, which is formed by uniformly dispersing a porous adsorbent material in a solvent, and comprises a porous adsorbent material and a solvent, and the volume ratio of the porous adsorbent material to the solvent is from 1:20 to 1:1.

[0035] As a specific embodiment of the method described above in the present invention, the porous adsorbent material includes one or a combination of several of metal-organic framework materials, covalent organic framework materials, molecular sieves, etc.

[0036] As a specific embodiment of the method described above in the present invention, the porous adsorbent material includes one or a combination of several of ZIF-8, CALF-20, UIO-66, etc.

[0037] As a specific embodiment of the method described above in the present invention, the solvent includes one or a combination of several of water, alcohol solvents, ketone solvents, hydrocarbon solvents, etc.

[0038] As a specific embodiment of the method described above in the present invention, the solvent includes one or a combination of several of water, ethylene glycol, isocetane, N,N-dimethylformamide (DMF), 1,3-dimethylpropyleneurea (DMPU), N-methylpyrrolidone (NMP), etc.

[0039] In the method described above in the present invention, the near-boiling-point mixture side and the porous adsorbent material slurry side respectively refer to the regions where the near-boiling-point mixture and the porous adsorbent material slurry enter. For example, when the near-boiling-point mixture is made to enter the outer space of the fiber and the porous adsorbent material slurry enters the inner space of the fiber, the outer space of the fiber and the inner space of the fiber are respectively the near-boiling-point mixture side and the porous adsorbent material slurry side. It should be noted that an appropriate pressure difference should be maintained between the near-boiling-point mixture side and the porous adsorbent material slurry side. If the pressure on the near-boiling-point mixture side is too high, a large amount of near-boiling-point mixture raw materials will enter the porous adsorbent material slurry, resulting in a deteriorated separation effect. If the pressure on the porous adsorbent material slurry side is too high, the fiber bundle will be damaged.

[0040] As a specific embodiment of the method described above of the present invention, the pressure on the near-boiling-point mixture side is controlled to be not lower than the pressure on the porous adsorbent material slurry side, and the pressure difference between the near-boiling-point mixture side and the porous adsorbent material slurry side is 0 - 10 kPa. During specific implementation, the pressure difference between the first back-pressure valve and the second back-pressure valve is controlled to be 0 - 10 kPa by controlling the pressures set by the two valves. Under such a small pressure difference condition, the near-boiling-point mixture can pass through the wall of the hollow fiber membrane module and come into contact with the porous adsorbent material slurry for adsorption, while also controlling to prevent a large amount of the near-boiling-point mixture from passing through the wall of the hollow fiber membrane module, so as to improve the separation effect. Because: if the pressure difference is large, many components that cannot be adsorbed by the porous adsorbent material slurry will be squeezed into the porous adsorbent material slurry. Whether the near-boiling-point mixture is a gas mixture or a liquid mixture, it will cause a decrease in its separation effect, and the degree of decrease in the separation effect of the liquid mixture will be significantly higher than that of the gas mixture.

[0041] As a specific embodiment of the method described above of the present invention, the residence time of the near-boiling-point mixture in the membrane contactor is 1 - 20 min, and the residence time of the porous adsorbent material slurry in the membrane contactor is 3 - 60 min.

[0042] As a specific embodiment of the method described above of the present invention, the desorption carried out in the desorption tower adopts intermittent operation.

[0043] In the present invention, the outer space of the fiber refers to the space between the hollow fiber membrane modules in the membrane contactor housing and the space between the inner wall of the housing and the hollow fiber membrane module, which can be regarded as a whole as the "shell side", and the inner space of the fiber refers to the inside of the hollow fiber membrane module, which can be regarded as the "tube side".

[0044] Compared with the prior art, the beneficial technical effects that can be achieved by the near-boiling-point mixture separation system and method based on the coupling of a porous adsorbent material and a membrane contactor provided by the present invention include:

[0045] In the present invention, the porous adsorbent material slurry adsorption method is coupled with a membrane contactor, that is, a hollow fiber membrane contactor, containing multiple hollow fiber membrane modules to separate the near-boiling-point mixture, giving full play to the advantages of the porous adsorbent material slurry adsorption method such as large separation factor, short equilibrium time, and fast desorption speed. At the same time, by using the hollow fiber membrane contactor, the hollow fiber membrane modules in the hollow fiber membrane contactor increase the contact area and mass transfer efficiency, overcoming the limitation of the traditional porous adsorbent material slurry adsorption method that continuous operation cannot be achieved in a gas penetration device, thus realizing an efficient and stable separation process.

[0046] In addition, by using a hollow fiber membrane contactor, the present invention effectively solves the technical bottleneck faced by the traditional slurry adsorption method of porous adsorbents in separating liquid-phase near-boiling point mixtures. Separating near-boiling point mixtures using the system and method provided by the present invention not only improves the separation efficiency (the separation factor can be as high as over 1400) and the purity of the obtained products, but also significantly reduces energy consumption and enables continuous operation, and is suitable for the efficient separation of near-boiling point mixtures with a relative volatility between 1.0 - 1.5. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 FIG. is a schematic structural diagram of a near-boiling point mixture separation system based on the coupling of a porous adsorbent and a membrane contactor provided in Embodiment 1 of the present invention.

[0049] Figure 2 FIG. is a schematic structural diagram of a near-boiling point mixture separation system based on the coupling of a porous adsorbent and a membrane contactor provided in Embodiment 2 of the present invention.

[0050] Figure 3 FIG. is a schematic structural diagram of a near-boiling point mixture separation system based on the coupling of a porous adsorbent and a membrane contactor provided in Embodiment 3 of the present invention.

[0051] Figure 4 FIG. is a schematic diagram showing the mass transfer of a mixture of n-hexane and methylcyclopentane and a slurry of a porous adsorbent through a multi-stage cross-flow contact channel in Example 1-1 of the present invention.

[0052] Figure 5 FIG. is an X-ray diffraction pattern of fresh ZIF-8 powder used in Example 1-1 of the present invention and ZIF-8 powder recovered from the ZIF-8 / NMP slurry after 10 adsorption-desorption cycle experiments.

[0053] Figure 6 FIG. is a schematic process flow diagram of the separation of pentane hydrocarbons in Comparative Example 1.

[0054] Main reference numeral descriptions:

[0055] Figures 1 - 3 Among them:

[0056] 1. Membrane contactor, 100. Near-boiling point mixture storage tank, 200. First target product storage tank, 300. Second target product storage tank, 400. Desorption tower;

[0057] 11. Inner space of fiber, 12. Outer space of fiber, 21. Slurry inlet, 22. Slurry outlet, 23. Lean porous adsorbent slurry storage tank, 24. Third feed pump, 25. Second back pressure valve, 26. Rich porous adsorbent slurry storage tank, 31. Raw material inlet, 310. First feed pump, 311. Liquid-phase product inlet, 32. Separation product outlet, 34. Pressure reducing valve, 35. Flow controller, 36. First back pressure valve, 37. First flowmeter, 38. Gas-phase product inlet, 39. Raw material outlet, 41. Second feed pump, 42. Desorption tower inlet, 43. Desorption product outlet, 44. Third back pressure valve, 45. Second flowmeter, 46. Water ring vacuum pump, 47. Desorption product inlet, 48. Liquid-phase outlet, 49. Transfer pump, 230. Feeding port.

[0058] Figure 6 Among them:

[0059] 50. Carbon dioxide removal tower 4, 51. Isopentane tower, 52. n-Pentane tower, 53. Cyclopentane tower. Specific embodiments

[0060] It should be noted that the term "including" and any of its variations in the description, claims and above-mentioned drawings of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0061] The "ranges" disclosed in the present invention are given in the form of lower and upper limits. There can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges defined in this way are combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it is understood that ranges of 60 - 110 and 80 - 120 are also expected. In addition, if the minimum range values listed are 1 and 2, and the maximum range values listed are 3, 4 and 5, then the following ranges are all expected: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4 and 2 - 5.

[0062] In the present invention, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed in the present invention, and "0 - 5" is just an abbreviated representation of these numerical combinations.

[0063] In the present invention, unless otherwise specified, all the embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0064] In the present invention, unless otherwise specified, all the technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0065] In the present invention, unless otherwise specified, all the steps mentioned herein can be carried out sequentially or randomly, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0066] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the attached tables, drawings and embodiments. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0067] Example 1

[0068] This example provides a separation system for near-boiling point mixtures based on the coupling of a porous adsorption material and a membrane contactor. As shown in the schematic structural diagram Figure 1 shown, it can be seen from Figure 1 that the system includes:

[0069] A near-boiling point mixture storage tank 100, a first target product storage tank 200, a second target product storage tank 300, a membrane contactor 1, a lean porous adsorption material slurry storage tank 23, a rich porous adsorption material slurry storage tank 26, and a desorption tower 400; in this example, the near-boiling point mixture storage tank 100 is a liquid-phase near-boiling point mixture container; and a stirring device is provided in the desorption tower 400;

[0070] The membrane contactor 1 includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell, an upper end cover and a lower end cover respectively arranged at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are arranged in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover. The upper end cover and the lower end cover are respectively provided with a slurry inlet 21 and a slurry outlet 22, and the lower and upper parts of the outer side wall of the shell are respectively provided with a raw material inlet 31 and a separation product outlet 32. That is, both the raw material inlet 31 and the separation product outlet 32 are communicated with the space 12 outside the fibers in the shell, while the slurry inlet 21 and the slurry outlet 22 are both communicated with the inside of the hollow fiber membrane module, that is, the space 11 inside the fibers.

[0071] The raw material outlet 39 of the liquid near-boiling-point mixture container is communicated with the raw material inlet 31 through a pipeline successively via a first feed pump 310 and a flow controller 35. The separation product outlet 32 is communicated with the liquid-phase product inlet 311 of the first target product storage tank 200 through a pipeline successively via a first back-pressure valve 36 and a first flowmeter 37. The slurry outlet 22 is communicated with the inlet of the rich porous adsorbent material slurry storage tank 26 through a pipeline via a second back-pressure valve 25. The outlet of the rich porous adsorbent material slurry storage tank 26 is communicated with the desorption tower inlet 42 of the desorption tower 400 through a pipeline via a second feed pump 41. The desorption product outlet 43 of the desorption tower 400 is communicated with the desorption product inlet 47 of the second target product storage tank 300 through a pipeline successively via a third back-pressure valve 44, a second flowmeter 45 and a water-ring vacuum pump 46. The liquid-phase outlet 48 of the desorption tower 400 is communicated with the feeding port 230 of the lean porous adsorbent material slurry storage tank 23 through a pipeline via a transfer pump 49. The discharge port of the lean porous adsorbent material slurry storage tank 23 is communicated with the slurry inlet 21 through a pipeline via a third feed pump 24.

[0072] Example 2

[0073] This example provides a near-boiling-point mixture separation system based on the coupling of a porous adsorbent material and a membrane contactor. The schematic structural diagram is as Figure 2 shown. It can be seen from Figure 2 that the system includes:

[0074] A near-boiling-point mixture storage tank 100, a first target product storage tank 200, a second target product storage tank 300, a membrane contactor 1, a lean porous adsorbent material slurry storage tank 23, a rich porous adsorbent material slurry storage tank 26 and a desorption tower 400. In this example, the near-boiling-point mixture storage tank 100 is a gas cylinder; and a stirring device is arranged in the desorption tower 400.

[0075] The membrane contactor 1 includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell body, an upper end cover and a lower end cover respectively arranged at the upper and lower ends of the shell body. The plurality of hollow fiber membrane modules are arranged in the shell body in a manner parallel to the central axis of the shell body, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover. The upper end cover and the lower end cover are respectively provided with a slurry inlet 21 and a slurry outlet 22, and the lower and upper parts of the outer side wall of the shell body are respectively provided with a raw material inlet 31 and a separation product outlet 32. That is, both the raw material inlet 31 and the separation product outlet 32 are communicated with the fiber outer space 12 in the shell body, while the slurry inlet 21 and the slurry outlet 22 are both communicated with the inside of the hollow fiber membrane module, that is, the fiber inner space 11.

[0076] The raw material outlet 39 of the gas cylinder is communicated with the raw material inlet 31 through a pipeline successively via a pressure reducing valve 34 and a flow controller 35. The separation product outlet 32 is communicated with the gas phase product inlet 38 of the first target product storage tank 200 through a pipeline successively via a first back pressure valve 36 and a first flow meter 37. The slurry outlet 22 is communicated with the inlet of the rich porous adsorbent material slurry storage tank 26 through a pipeline via a second back pressure valve 25. The outlet of the rich porous adsorbent material slurry storage tank 26 is communicated with the desorption tower inlet 42 of the desorption tower 400 through a pipeline via a second feed pump 41. The desorption product outlet 43 of the desorption tower 400 is communicated with the desorption product inlet 47 of the second target product storage tank 300 through a pipeline successively via a third back pressure valve 44, a second flow meter 45 and a water ring vacuum pump 46. The liquid phase outlet 48 of the desorption tower 400 is communicated with the feeding port 230 of the poor porous adsorbent material slurry storage tank 23 through a pipeline via a transfer pump 49. The discharge port of the poor porous adsorbent material slurry storage tank 23 is communicated with the slurry inlet 21 through a pipeline via a third feed pump 24.

[0077] Example 3

[0078] This example provides a near-boiling point mixture separation system based on the coupling of a porous adsorbent material and a membrane contactor. The schematic structural diagram is as Figure 3 shown. It can be seen from Figure 3 that the system includes:

[0079] a near-boiling point mixture storage tank 100, a first target product storage tank 200, a second target product storage tank 300, a membrane contactor 1, a poor porous adsorbent material slurry storage tank 23, a rich porous adsorbent material slurry storage tank 26 and a desorption tower 400. In this example, the near-boiling point mixture storage tank 100 is a gas cylinder. And a stirring device is arranged in the desorption tower 400.

[0080] The membrane contactor 1 includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell, an upper end cover and a lower end cover respectively arranged at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are arranged in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover; the lower end cover and the upper end cover are respectively provided with a raw material inlet 31 and a separation product outlet 32, and the upper and lower parts of the outer side wall of the shell are respectively provided with a slurry inlet 21 and a slurry outlet 22, that is, the raw material inlet 31 and the separation product outlet 32 are both communicated with the inside of the hollow fiber membrane module, that is, the fiber inner space 11, while the slurry inlet 21 and the slurry outlet 22 are both communicated with the fiber outer space 12 inside the shell;

[0081] The raw material outlet 39 of the gas cylinder is communicated with the raw material inlet 31 through a pipeline successively via a pressure reducing valve 34 and a flow controller 35; the separation product outlet 32 is communicated with the gas phase product inlet 38 of the first target product storage tank 200 through a pipeline successively via a first back pressure valve 36 and a first flowmeter 37; the slurry outlet 22 is communicated with the inlet of the rich porous adsorbent slurry storage tank 26 through a pipeline via a second back pressure valve 25. The outlet of the rich porous adsorbent slurry storage tank 26 is communicated with the desorption tower inlet 42 of the desorption tower 400 through a pipeline via a second feed pump 41. The desorption product outlet 43 of the desorption tower 400 is communicated with the desorption product inlet 47 of the second target product storage tank 300 through a pipeline successively via a third back pressure valve 44, a second flowmeter 45 and a water ring vacuum pump 46. The liquid phase outlet 48 of the desorption tower 400 is communicated with the feeding port 230 of the lean porous adsorbent slurry storage tank 23 through a pipeline via a transport pump 49. The discharge port of the lean porous adsorbent slurry storage tank 23 is communicated with the slurry inlet 21 through a pipeline via a third feed pump 24.

[0082] Example 1-1

[0083] This example provides a method for separating near-boiling point mixtures based on the coupling of a porous adsorbent and a membrane contactor, which is realized by using the near-boiling point mixture separation system based on the coupling of a porous adsorbent and a membrane contactor provided in Example 1. In the membrane contactor used in the system, the inner diameter of the housing is 5 cm, the wall thickness is 1 cm, the length is 0.35 m, and 1000 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PP, the length is 35 cm, the inner diameter is 0.6 mm, the wall thickness is 0.2 mm, the porosity is 45%, and the pore size distribution is 0.2 μm;

[0084] Among them, the method includes the following steps:

[0085] Step (a): At a temperature of 25 °C, turn on the first feed pump 310 and set the flow rate of the flow controller 35 to 82.47 mL / min; allow the n-hexane and methylcyclopentane mixture with a mass ratio of 15:85 contained in the liquid near-boiling point mixture container to enter the outer space 12 of the fibers of the membrane contactor 1 through the raw material inlet 31;

[0086] At the same time, turn on the lean porous adsorbent slurry storage tank 23, start the third feed pump 24 and control its flow rate to 9.90 mL / min, so that the slurry contained in the lean porous adsorbent slurry storage tank 23 (which contains ZIF-8, N-methylpyrrolidone and water with a mass ratio of 3:5:2) is input into the inner space 11 of the fibers of the membrane contactor 1 through the slurry inlet 21;

[0087] Adjust the pressure of the first back pressure valve 36 to 200 kPa, adjust the pressure of the second back pressure valve 25 to 200 kPa, and the slurry and the mixture flow reversely in the membrane contactor 1 through the hollow fiber membrane module in the membrane contactor 1. During this process, part of the mixture passes through the wall of the hollow fiber membrane module and enters the hollow fiber membrane module, and the target component in the mixture, that is, n-hexane, is selectively adsorbed by the porous adsorbent material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorbent slurry, while methylcyclopentane in the mixture is discharged from the separation product outlet and enters the first target product storage tank 200 through the liquid phase product inlet 311; among them, the schematic diagram of the mass transfer of the n-hexane and methylcyclopentane mixture and the porous adsorbent slurry through the multi-stage cross-flow contact channel is as Figure 4 shown; in this embodiment, the residence time of the near-boiling point mixture in the membrane contactor is 5 min, and the residence time of the porous adsorbent slurry in the membrane contactor is 10 min;

[0088] Step (b): The rich porous adsorbent slurry enters the desorption tower 400 from the rich porous adsorbent slurry storage tank 26 through the second feed pump 41 via the desorption tower inlet 42. Turn on the heating and heat to 95 °C, and at the same time start the water ring vacuum pump 46. Adjust the pressure of the third back pressure valve to 10 kPa, so that the n-hexane in the rich porous adsorbent slurry is desorbed and discharged from the desorption product outlet 43 into the second target product storage tank 300. The desorption can be completed in 40 min. The lean slurry after desorption is transported by the transport pump 49 from the liquid phase outlet 48 of the desorption tower 400 to the lean porous adsorbent slurry storage tank 23.

[0089] Finally, in this embodiment, methylcyclopentane with a purity of 95.22% is obtained from the separation product outlet 32, and n-hexane with a purity of 97.15% is obtained from the desorption product outlet 43. The raw material and product compositions are analyzed by a HP7890B type chromatograph using the headspace sampling method. The separation factor is as high as 1209.

[0090] Meanwhile, after 10 cycles of repeated absorption and regeneration, the separation performance of the slurry did not show any decline. Subsequently, the reused slurry was dried to recover the ZIF-8 material, and the fresh and recovered ZIF-8 materials were characterized structurally. The obtained X-ray diffraction pattern is as shown in Figure 5 . Figure 5 The characterization results shown in

[0091] Example 1-2

[0092] This example provides a method for separating near-boiling point mixtures based on the coupling of a porous adsorbent material and a membrane contactor, which is realized by using the near-boiling point mixture separation system based on the coupling of a porous adsorbent material and a membrane contactor provided in Example 1. The inner diameter of the outer shell of the membrane contactor used in the system is 5 cm, the wall thickness is 1 cm, the length is 0.35 m, and 1000 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PP, the length is 35 cm, the inner diameter is 0.6 mm, the wall thickness is 0.2 mm, the porosity is 45%, and the pore size distribution is 0.2 μm;

[0093] Among them, the method includes the following steps:

[0094] Step (a): At a temperature of 25 °C, turn on the first feed pump 310 and set the flow rate of the flow controller 35 to 82.47 mL / min; make the n-hexane and methylcyclopentane mixture with a mass ratio of 15:85 contained in the liquid-phase near-boiling point mixture container enter the outer space 12 of the fibers of the membrane contactor 1 through the raw material inlet 31;

[0095] Meanwhile, turn on the lean porous adsorbent slurry storage tank 23, start the third feed pump 24 and control its flow rate to 9.90 mL / min, so that the slurry contained in the lean porous adsorbent slurry storage tank 23 (which contains ZIF-8, N-methylpyrrolidone and water with a mass ratio of 3:5:2) enters the inner space 11 of the fibers of the membrane contactor 1 through the slurry inlet 21;

[0096] Adjust the pressure of the first back-pressure valve 36 to 200 kPa, and adjust the pressure of the second back-pressure valve 25 to 180 kPa. The slurry and the mixture flow reversely in the membrane contactor 1 through the hollow fiber membrane module in the membrane contactor 1. During this process, part of the mixture passes through the wall of the hollow fiber membrane module and enters the hollow fiber membrane module, and the target component in the mixture, that is, n-hexane, is selectively adsorbed by the porous adsorbent material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a slurry rich in porous adsorbent material. The methylcyclopentane in the mixture is discharged from the separation product outlet and enters the first target product storage tank 200 through the liquid-phase product inlet 311; among them, the schematic diagram of mass transfer of the n-hexane and methylcyclopentane mixture and the slurry rich in porous adsorbent material through the multi-stage cross-flow contact channel is as Figure 4 shown; in this embodiment, the residence time of the near-boiling-point mixture in the membrane contactor is 5 min, and the residence time of the slurry rich in porous adsorbent material in the membrane contactor is 10 min;

[0097] Step (b): The slurry rich in porous adsorbent material enters the desorption tower 400 from the slurry rich in porous adsorbent material storage tank 26 through the second feed pump 41 via the desorption tower inlet 42. Turn on the heating and heat it to 95 °C, and at the same time start the water-ring vacuum pump 46. Adjust the pressure of the third back-pressure valve to 10 kPa, so that the n-hexane in the slurry rich in porous adsorbent material is desorbed and discharged from the desorption product outlet 43 into the second target product storage tank 300. The desorption can be completed in 40 min. The desorbed lean slurry is transported by the transport pump 49 through the liquid-phase outlet 48 of the desorption tower 400 to the lean slurry storage tank 23 of porous adsorbent material.

[0098] Finally, in this embodiment, methylcyclopentane with a purity of 94.41% is obtained from the separation product outlet 32, and n-hexane with a purity of only 54.22% is obtained from the desorption product outlet 43. The compositions of the raw materials and products are analyzed by a HP7890B chromatograph using the headspace sampling method. The separation factor is only 20.

[0099] Comparing the experimental results of Comparative Example 1-1 and Example 1-2, it can be seen that compared with Example 1-1, due to the larger pressure difference between the near-boiling-point mixture side and the slurry side of the porous adsorbent material in Example 1-2, many components that cannot be adsorbed by the slurry of porous adsorbent material are squeezed into the slurry of porous adsorbent material, resulting in a significant reduction in the separation effect of the near-boiling-point mixture.

[0100] Example 1-3

[0101] This embodiment provides a method for separating near-boiling mixtures based on the coupling of porous adsorption materials and membrane contactors, which is realized by using the near-boiling mixture separation system based on the coupling of porous adsorption materials and membrane contactors provided in Embodiment 1. The inner diameter of the outer shell of the membrane contactor used in the system is 8 cm, the wall thickness is 1 cm, the length is 0.35 m, and 1000 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PVDF, the length is 35 cm, the inner diameter is 0.9 mm, the wall thickness is 0.3 mm, the porosity is 40%, and the pore size distribution is 0.1 μm;

[0102] Among them, the method includes the following steps:

[0103] Step (a): Under the temperature condition of 20 °C, turn on the first feed pump 310 and set the flow rate of the flow controller 35 to 114.06 mL / min; make the n-pentane and isopentane mixture with a mass ratio of 1:1 contained in the liquid-phase near-boiling mixture container enter the outer space 12 of the fibers of the membrane contactor 1 through the raw material inlet 31;

[0104] At the same time, turn on the lean porous adsorption material slurry storage tank 23, start the third feed pump 24 and control its flow rate to 14.83 mL / min, so that the slurry contained in the lean porous adsorption material slurry storage tank 23 (which contains ZIF-8, 1,3-dimethylpropyleneurea and water with a mass ratio of 3:6:1) is input into the inner space 11 of the fibers of the membrane contactor 1 through the slurry inlet 21;

[0105] Adjust the pressure of the first back pressure valve 36 to 150 kPa, adjust the pressure of the second back pressure valve 25 to 145 kPa, and the slurry and the mixture flow reversely in the membrane contactor 1 through the hollow fiber membrane module in the membrane contactor 1. During this process, part of the mixture passes through the wall of the hollow fiber membrane module and enters the hollow fiber membrane module, and the target component in the mixture, that is, n-pentane, is selectively adsorbed by the porous adsorption material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorption material slurry, while the isopentane in the mixture is discharged from the separation product outlet and enters the first target product storage tank 200 through the liquid-phase product inlet 311; In this embodiment, the residence time of the near-boiling mixture in the membrane contactor is 10 min, and the residence time of the porous adsorption material slurry in the membrane contactor is 15 min;

[0106] Step (b): The slurry of the porous adsorbent material enters the desorption column 400 from the storage tank 26 of the slurry of the porous adsorbent material through the second feed pump 41 via the desorption column inlet 42. Start heating and heat to 75 °C, and at the same time start the water ring vacuum pump 46. Adjust the pressure of the third backpressure valve to 10 kPa to desorb n-hexane in the slurry of the porous adsorbent material and discharge it from the desorption product outlet 43 into the second target product storage tank 300. Desorption can be completed in 30 minutes. The desorbed lean slurry is transported by the transport pump 49 through the liquid phase outlet 48 of the desorption column 400 to the storage tank 23 of the lean slurry of the porous adsorbent material.

[0107] Finally, in this example, isopentane with a purity of 98.72% was obtained from the separation product outlet 32, and n-pentane with a purity of 91.86% was obtained from the desorption product outlet 43. The compositions of the raw materials and products were analyzed by a HP7890B chromatograph using the headspace sampling method. The separation factor was as high as 868.

[0108] At the same time, after more than ten times of repeated absorption and regeneration, the separation performance of the slurry did not show any decline. Subsequently, the repeatedly used slurry was dried and the ZIF-8 material therein was recovered, and then the recovered ZIF-8 material was subjected to structural characterization. The X-ray diffraction characterization results showed that the characteristic structure of the recovered ZIF-8 was basically the same as that of the fresh ZIF-8, indicating that the structure of the ZIF-8 material remained intact after multiple repeated uses.

[0109] Example 2-1

[0110] This example provides a method for separating near-boiling point mixtures based on the coupling of a porous adsorbent material and a membrane contactor, which is realized by using the system for separating near-boiling point mixtures based on the coupling of a porous adsorbent material and a membrane contactor provided in Example 2. The inner diameter of the outer shell of the membrane contactor used in the system is 8 cm, the wall thickness is 1 cm, the length is 0.5 m, and 1000 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PVDF, the length is 50 cm, the inner diameter is 1 mm, the wall thickness is 0.3 mm, the porosity is 40%, and the pore size distribution is 0.1 μm;

[0111] Among them, the method includes the following steps:

[0112] Step (a): Open the gas cylinder, adjust the pressure of the pressure reducing valve 34 to 200 KPa and adjust the flow rate of the flow meter 35 to 131.94 mL / min; then pass the n-butane and isobutane gas mixture with a mass ratio of 4:6 contained in the gas cylinder into the outer space 12 of the fibers of the membrane contactor 1 through the raw material inlet 31; at the same time, open the lean porous adsorbent slurry storage tank 23, start the third feed pump 24 and control its flow rate to 27.49 mL / min, so that the slurry contained in the lean porous adsorbent slurry storage tank 23 (which contains ZIF-8, 1,3-dimethylpropyleneurea and water with a mass ratio of 3:5:2) is input into the inner space 11 of the fibers of the membrane contactor 1 through the slurry inlet 21;

[0113] Adjust the pressure of the first back pressure valve 36 to 200 kPa, adjust the pressure of the second back pressure valve 25 to 200 kPa, and the slurry and the mixture flow reversely in the membrane contactor 1 through the hollow fiber membrane module in the membrane contactor 1. During this process, part of the mixture passes through the wall of the hollow fiber membrane module and enters the hollow fiber membrane module, and the target component in the mixture, that is, n-butane, is selectively adsorbed by the porous adsorbent material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorbent slurry, while the isobutane in the mixture is discharged from the separation product outlet and enters the first target product storage tank 200 through the gas phase product inlet 38; in this embodiment, the residence time of the near-boiling point mixture in the membrane contactor is 5 min, and the residence time of the porous adsorbent slurry in the membrane contactor is 10 min;

[0114] Step (b): The rich porous adsorbent slurry enters the desorption tower 400 from the rich porous adsorbent slurry storage tank 26 through the second feed pump 41 via the desorption tower inlet 42. Turn on the heating and heat it to 55 °C. At the same time, start the water ring vacuum pump 46 and adjust the pressure of the third back pressure valve to 10 kPa, so that the n-butane in the rich porous adsorbent slurry is desorbed and discharged from the desorption product outlet 43 into the second target product storage tank 300. Desorption can be completed in 30 min, and the lean slurry after desorption is transported to the lean porous adsorbent slurry storage tank 23 by the transport pump 49 through the liquid phase outlet 48 of the desorption tower 400.

[0115] Finally, in this embodiment, isobutane with a purity of 91.36% is obtained from the separation product outlet 32, and n-butane with a purity of 99.26% is obtained from the desorption product outlet 43. The compositions of the raw materials and products are analyzed by a HP7890B type chromatograph using the headspace sampling method. The separation factor is as high as 1418.

[0116] Meanwhile, after more than ten times of repeated absorption and regeneration, the separation performance of the slurry did not show any decline. Subsequently, the repeatedly used slurry was dried to recover the ZIF-8 material therein, and then the recovered ZIF-8 material was subjected to structural characterization. The X-ray diffraction characterization results showed that the characteristic structure of the recovered ZIF-8 was basically the same as that of the fresh ZIF-8, indicating that the structure of the ZIF-8 material remained intact after multiple repeated uses.

[0117] Example 2-2

[0118] This example provides a method for separating near-boiling point mixtures based on the coupling of a porous adsorbent material and a membrane contactor, and the difference from Example 2-1 is only that:

[0119] The gas mixture contained in the gas cylinder is a gas mixture of butyne, 1-butene, n-butane, isobutene, and isobutane with a molar ratio of 19.6:18.4:14.8:20.1:27.1.

[0120] Finally, in this example, a gas mixture of butyne, 1-butene, n-butane, isobutene, and isobutane with a molar ratio of 1.5:1.4:5.3:31.4:60.4 was obtained from the separation product outlet 32, and a gas mixture of butyne, 1-butene, n-butane, isobutene, and isobutane with a molar ratio of 36.3:32.9:24.2:6.3:0.3 was obtained from the desorption product outlet 43. The compositions of the raw materials and products were analyzed by a HP7890B type chromatograph using the headspace sampling method. It is not difficult to see that the gas at the separation product outlet 32 is mainly isobutene and isobutane, accounting for 91.8%. The gas at the desorption product outlet 43 is mainly butyne, 1-butene, and n-butane, accounting for 93.4%. The separation factor of (butyne + 1-butene + n-butane) / (isobutene + isobutane) achieved by the method provided in this example can reach 158.

[0121] It can be seen from Example 2-2 that the separation system and method for near-boiling point mixtures based on the coupling of a porous adsorbent material and a membrane contactor provided by the present invention can also achieve the separation of near-boiling point mixtures containing two or more target components.

[0122] Example 3-1

[0123] This embodiment provides a method for separating near-boiling mixtures based on the coupling of porous adsorption materials and membrane contactors, which is realized by using the near-boiling mixture separation system based on the coupling of porous adsorption materials and membrane contactors provided in Embodiment 3. The inner diameter of the outer shell of the membrane contactor used in the system is 8 cm, the wall thickness is 1 cm, the length is 0.5 m, and 1000 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PVDF, the length is 50 cm, the inner diameter is 1 mm, the wall thickness is 0.3 mm, the porosity is 40%, and the pore size distribution is 0.1 μm.

[0124] Wherein, the method includes the following steps:

[0125] Step (a): Open the gas cylinder, adjust the pressure of the pressure reducing valve 34 to 200 KPa and adjust the flow rate of the flow controller 35 to 54.98 mL / min; then pass the n-butane and isobutane gas mixture with a mass ratio of 4:6 contained in the gas cylinder through the raw material inlet 31 into the inner space 11 of the fibers of the membrane contactor 1; at the same time, open the lean porous adsorption material slurry storage tank 23, start the third feed pump 24 and control its flow rate to 65.97 mL / min, so that the slurry contained in the lean porous adsorption material slurry storage tank 23 (which contains ZIF-8, 1,3-dimethylpropyleneurea and water with a mass ratio of 3:5:2) is input into the outer space 12 of the fibers of the membrane contactor 1 through the slurry inlet 21.

[0126] Adjust the pressure of the first back pressure valve 36 to 200 kPa, adjust the pressure of the second back pressure valve 25 to 200 kPa, and the slurry and the mixture flow reversely in the membrane contactor 1 through the hollow fiber membrane module in the membrane contactor 1. During this process, part of the mixture passes through the wall of the hollow fiber membrane module into the outer space 12 of the fibers, and the target component in the mixture, that is, n-butane, is selectively adsorbed by the porous adsorption material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorption material slurry, while the isobutane in the mixture is discharged from the separation product outlet and enters the first target product storage tank 200 through the gas phase product inlet 38; in this embodiment, the residence time of the near-boiling mixture in the membrane contactor is 5 min, and the residence time of the porous adsorption material slurry in the membrane contactor is 10 min.

[0127] Step (b): The slurry of the porous adsorbent material enters the desorption tower 400 from the slurry storage tank 26 of the porous adsorbent material through the second feed pump 41 via the desorption tower inlet 42. Start heating and heat it to 55 °C, and at the same time start the water ring vacuum pump 46. Adjust the pressure of the third back-pressure valve to 10 kPa to desorb n-butane in the slurry of the porous adsorbent material and discharge it from the desorption product outlet 43 into the second target product storage tank 300. Desorption can be completed in 30 minutes. The lean slurry after desorption is transported by the transport pump 49 through the liquid phase outlet 48 of the desorption tower 400 to the lean slurry storage tank 23 of the porous adsorbent material.

[0128] Finally, in this embodiment, isobutane with a purity of 92.40% is obtained from the separation product outlet 32, and n-butane with a purity of 98.26% is obtained from the desorption product outlet 43. The compositions of the raw materials and products are analyzed by a HP7890B chromatograph using the headspace sampling method. The separation factor is as high as 687. Comparing the experimental results of Comparative Example 2-1 and Example 3-1, it can be seen that on the premise that other conditions are the same, the separation effect when the near-boiling-point mixture flows through the inner space 11 of the fiber and the slurry flows through the outer space 12 of the fiber in Example 3-1 is slightly worse than that when the near-boiling-point mixture flows through the outer space 12 of the fiber and the slurry flows through the inner space 11 of the fiber in Example 2-1.

[0129] At the same time, the separation performance of the slurry does not show any decline after more than ten times of repeated absorption and regeneration. Subsequently, the repeatedly used slurry is dried and the ZIF-8 material therein is recovered, and then the recovered ZIF-8 material is subjected to structural characterization. The X-ray diffraction characterization results show that: the characteristic structure of the recovered ZIF-8 is basically the same as that of the fresh ZIF-8, indicating that the structure of the ZIF-8 material remains intact after multiple repeated uses.

[0130] Comparative Example 1

[0131] The paper published by Zhang Z et al. (AIChE J., 2020, 66(7): 16236-16243.) lists the production process of a C5 fractionation unit with a production capacity of 100 thousand tons / year. In this C5 alkane distillation separation process, four distillation towers as shown in Figure 6 are set, namely the de-C4 tower 50, the isopentane tower 51, the n-pentane tower 52 and the cyclopentane tower 53, corresponding to different separation components respectively. Although there are many components involved in this process, the separation process in the isopentane tower can be regarded as mainly the separation process of n-pentane and isopentane. The process operating conditions and the number of theoretical plates of the fractionating tower are shown in Table 1 below.

[0132] Table 1

[0133] Isopentane tower n-Pentane tower Number of theoretical trays 80 65 Top pressure / MPa 0.25 0.25 Top temperature / °C 69.6 78.1 Bottom temperature / °C 89.0 104.4 Reflux ratio 17.21 7.25 <![CDATA[Reflux flow rate / kg·h -1 > 72585 72585 Packing 350Y 350Y Fractionating tower diameter / m 3.2 2.0

[0134] As can be seen from Table 1, in the separation process of isopentane fraction, the required theoretical number of plates is 80, and the reflux ratio is as high as 17.21. This reflects that the separation of n-pentane and isopentane is difficult, and it is a huge economic consumption in terms of energy consumption and equipment cost.

[0135] Comparative Example 2

[0136] The separation of butane isomers using a separation membrane made of MFI zeolite is a technology that has been studied extensively, and it can significantly reduce separation energy consumption and pollutant emissions. Currently, there are many papers published on the use of MFI membranes to separate butane isomers. The results show that under the test conditions of 20-100°C, the selectivity of n-butane / isobutane is between 4 and 70, which is significantly lower than the experimental results in the embodiments of the present invention.

[0137] The separation results of the prior art using MFI zeolite molecular sieve membrane to separate n-butane and isobutane are shown in Table 2 below.

[0138] Table 2

[0139]

[0140] In addition, Woo et al. (Micropor. Mesopor. Mat., 2008, 110(2-3): 330-338) prepared an MFI-based mixed matrix membrane to improve the n-butane permeability of the membrane, but the highest n-butane / isobutane separation factor obtained using the MFI-based mixed matrix membrane was only 6.64.

[0141] Comparative Example 3

[0142] This comparative example uses the small-scale experimental device described in paragraphs

[0023] and

[0024] of the specification of CN102389686A and the experimental method described in the specification of CN119113696A to conduct the experiment. During the experiment, at a temperature of 25°C, 10 g of a slurry of ZIF-8, 1,3-dimethylpropyleneurea and water with a composition of 3:6:1 (mass ratio) was added, and n-pentane and isopentane with a mass ratio of 1:1 were introduced to separate the two.

[0143] Finally, isopentane with a purity of 93.31% was obtained in this comparative example, and n-hexane with a purity of 88.52% was obtained in the desorbed gas. The separation factor was only 107.55. The method provided in this comparative example uses a combination of a porous adsorption material and an existing conventional experimental device, rather than a combination of a porous adsorption material and a non-membrane contactor, to separate near-boiling mixtures. Compared with the embodiments of the present invention, the method provided in Comparative Example 3 not only has a significantly reduced separation factor, but also can only separate the near-boiling mixture by heating it to the gaseous state. At the same time, the method provided in Comparative Example 3 is difficult to carry out large-scale production.

[0144] As described above, the above are only specific embodiments of the present invention, and the scope of the invention cannot be limited by them. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the present invention, should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined and used between technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A separation system for near-boiling mixtures based on the coupling of porous adsorption materials and membrane contactors, wherein, The system includes: a near-boiling-point mixture storage tank, a first target product storage tank, a second target product storage tank, a membrane contactor, a lean porous adsorbent slurry storage tank, a rich porous adsorbent slurry storage tank, and a desorption tower; The membrane contactor includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell and an upper end cover and a lower end cover respectively arranged at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are arranged in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover. The upper end cover and the lower end cover are respectively provided with a first opening and a second opening, and the lower and upper parts of the outer side wall of the shell are respectively provided with a third opening and a fourth opening; The near-boiling-point mixture storage tank is communicated with the third opening through a pipeline. The lean porous adsorbent slurry storage tank is communicated with the first opening through a pipeline. The second opening is communicated with the inlet of the desorption tower through a pipeline via the rich porous adsorbent slurry storage tank. The desorption product outlet and the liquid phase outlet of the desorption tower are respectively communicated with the second target product storage tank and the lean porous adsorbent slurry storage tank through pipelines. The fourth opening is communicated with the first target product storage tank through a pipeline; Or the near-boiling-point mixture storage tank is communicated with the second opening through a pipeline. The lean porous adsorbent slurry storage tank is communicated with the fourth opening through a pipeline. The third opening is communicated with the inlet of the desorption tower through a pipeline via the rich porous adsorbent slurry storage tank. The desorption product outlet and the liquid phase outlet of the desorption tower are respectively communicated with the second target product storage tank and the lean porous adsorbent slurry storage tank through pipelines. The first opening is communicated with the first target product storage tank through a pipeline.

2. The system according to claim 1, wherein The near-boiling-point mixture storage tank is communicated with the third opening or the second opening through a pipeline in sequence via a first feed pump or a pressure reducing valve and a flow controller.

3. The system according to claim 1 or 2, wherein, The fourth opening or the first opening is communicated with the first target product storage tank through a pipeline in sequence via a first back pressure valve and a first flowmeter.

4. The system according to claim 1 or 2, wherein, The second opening or the third opening is communicated with the inlet of the rich porous adsorbent slurry storage tank through a pipeline via a second back pressure valve. The outlet of the rich porous adsorbent slurry storage tank is communicated with the inlet of the desorption tower through a pipeline via a second feed pump. The desorption product outlet of the desorption tower is communicated with the second target product storage tank through a pipeline in sequence via a third back pressure valve, a second flowmeter, and a water ring vacuum pump. The liquid phase outlet of the desorption tower is communicated with the inlet of the lean porous adsorbent slurry storage tank through a pipeline via a transfer pump. The outlet of the lean porous adsorbent slurry storage tank is communicated with the first opening or the fourth opening through a pipeline via a third feed pump.

5. The system according to claim 1, wherein, The material of the plurality of hollow fiber membrane modules includes one or a combination of several of polypropylene, polyvinylidene fluoride, and polyacrylonitrile.

6. The system according to claim 1 or 5, wherein The inner diameter of the plurality of hollow fiber membrane modules is 0.1-5 mm, the wall thickness is 0.01-2 mm, the porosity is 40-80%, and the pore size distribution is 0.01-5 μm.

7. A method for separating near-boiling mixtures based on the coupling of porous adsorbent materials and membrane contactors, which is realized by using the near-boiling mixture separation system based on the coupling of porous adsorbent materials and membrane contactors according to any one of claims 1-6, wherein, The method includes: Step (1): Feed the near-boiling-point mixture into the outer space or the inner space of the fibers inside the shell, and feed the porous adsorbent slurry into the inner space or the outer space of the fibers inside the shell. Under the pressure difference between the near-boiling-point mixture side and the porous adsorbent slurry side, a part of the target components in the near-boiling-point mixture pass through the wall of the hollow fiber membrane module into the inner space or the outer space of the fibers and are selectively adsorbed by the porous adsorbent to obtain a rich porous adsorbent slurry, while another part of the target components in the near-boiling-point mixture are discharged from the outer space or the inner space of the fibers. Step (2): Feed the rich porous adsorbent slurry into a desorption tower and heat it to desorb the target components in the rich porous adsorbent slurry and discharge and collect them from the desorption product outlet. After desorption is completed, collect and recycle the resulting lean porous adsorbent slurry.

8. The method according to claim 7, wherein The near-boiling-point mixture includes a near-boiling-point mixture with a relative volatility α between 1.0 and 1.

5. Preferably, the near-boiling-point mixture contains at least two target components. More preferably, the near-boiling-point mixture is a C4-C6 alkane isomer. Further preferably, the near-boiling-point mixture includes any one of n-hexane and methylcyclopentane, n-hexane and 2-methylpentane, n-hexane and 3-methylpentane, n-pentane and isopentane, and n-butane and isobutane. Also preferably, the near-boiling-point mixture is in a gaseous phase or a liquid phase.

9. The method according to claim 7 or 8, wherein The porous adsorbent slurry is a solid-liquid suspension slurry, which contains a porous adsorbent and a solvent, and the volume ratio of the porous adsorbent to the solvent is 1:20 to 1:

1. Preferably, the porous adsorbent includes one or a combination of metal-organic framework materials, covalent organic framework materials, and molecular sieves. More preferably, the porous adsorbent includes one or a combination of ZIF-8, CALF-20, and UIO-66. Also preferably, the solvent includes one or a combination of water, alcohol solvents, ketone solvents, and hydrocarbon solvents. Even more preferably, the solvent includes one or a combination of water, ethylene glycol, isocetane, N,N-dimethylformamide, 1,3-dimethylpropyleneurea, and N-methylpyrrolidone.

10. The method according to claim 7 or 8, wherein, Control the pressure on the near-boiling-point mixture side to be not lower than the pressure on the porous adsorbent slurry side, and the pressure difference between the near-boiling-point mixture side and the porous adsorbent slurry side is 0-10 kPa. Preferably, the residence time of the near-boiling-point mixture in the membrane contactor is 1-20 min, and the residence time of the porous adsorbent slurry in the membrane contactor is 3-60 min.

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