A method for adsorption separation of low-carbon olefin / alkane mixture and its application

Abstract

The present invention relates to an adsorption separation method for a low-carbon olefin / alkane mixture and its application. The specific method comprises: firstly, two adsorbers are arranged in series, and a mixed gas containing ethylene, propylene and an alkane mixture is introduced to adsorb propylene and ethylene; then, the two adsorbers are arranged in parallel, and a desorbent is introduced to obtain a single-component product of propylene or ethylene respectively, and the adsorbent material is regenerated at the same time; wherein the adsorbent material comprises at least one of CaA, AgA, NiA or NiY molecular sieves; and the desorbent comprises one of carbon dioxide or nitrogen. Compared with the prior art, the present invention can separate and obtain single-component products of propylene and ethylene with high purity; at the same time, the present invention realizes effective desorption of olefins by effectively reducing the adsorption energy between the adsorbent material and the olefin compound, thereby avoiding the problems of easy polymerization of olefins and rapid coking and deactivation of the adsorbent during the temperature rise desorption process, and also avoiding the problems of high energy consumption caused by vacuum desorption and low processing efficiency caused by repeated filling and releasing of pressure.

Description

Technical Field

[0001] The invention belongs to the technical field of gas separation, and relates to an adsorption separation method for a low-carbon olefin / alkane mixture and application thereof. Background Art

[0002] As the basic raw material for many industrial products, olefins play a very important role in the petrochemical field and are widely used in the production of lubricants, surfactants, oilfield recovery additives and plasticizers. In the petrochemical industry, olefins are mainly obtained by steam cracking of alkanes, and a portion of uncracked alkanes will inevitably be mixed in the production process. Therefore, in order to ensure the quality of downstream products, other impurities must be removed as much as possible to achieve olefin levels of polymerization grade purity. However, olefins and alkanes usually have similar relative volatility and molecular size, making olefin / alkane separation extremely challenging.

[0003] At present, the separation of low-carbon olefin / alkane systems in industry mainly relies on the mature high-pressure and low-temperature distillation process. The olefin / alkane mixture is separated by repeated distillation-concentration cycles in a distillation tower with more than 100 plates. However, distillation is the most energy-consuming separation process in the chemical industry. For the separation of olefin / alkane systems, the energy consumed by distillation is several times or even dozens of times that of other non-thermal separation technologies. Taking ethylene as an example, the non-thermal separation technology can save 0.3 to 1.5 GJ of energy per ton of ethylene through high-pressure and low-temperature distillation. In order to improve the energy efficiency and economic benefits of olefin / alkane separation, the development of new low-energy separation technologies has become an urgent problem to be solved.

[0004] Adsorption separation is recognized as a highly promising technology for separation of olefin / alkane mixtures due to its advantages of simple process, high separation efficiency and low operating cost. The development of high-performance adsorption materials is the key and research hotspot to achieve efficient adsorption separation technology. Currently, a variety of adsorbents have been used for the separation of olefin / alkane systems, such as metal organic framework materials (MOFs), molecular sieves, carbon molecular sieves (CMS), etc.

[0005] The document "M2(m-dobdc)(M=Mn,Fe,Co,Ni)metal-organic frameworks as highly selective,high-capacity adsorbents for olefin / paraffin separations" (Journal of the American Chemical Society, 2017, Vol. 139, No. 43, pp. 15363-15370) reports the separation performance of adsorbents Mn2(m-dobdc), Fe2(m-dobdc), Co2(m-dobdc) and Ni2(m-dobdc) for C2H4 / C2H6 system and C3H6 / C3H8 system respectively.

[0006] The document "Light olefins / paraffins separation with 13X zeolite binderless beads" (Separation and Purification Technology, 2014, Vol. 133, pp. 452-475) reports the evaluation of the separation performance of binderless X-type zeolite for C2H4 / C2H6 system and C3H6 / C3H8 system by VPSA process.

[0007] Although many studies have reported that different adsorbent materials can be used to achieve the adsorption separation of alkanes and olefins in olefin / alkane mixtures, the crude olefin products obtained industrially usually have complex components, including not only olefin / alkane mixtures with the same carbon number, but also their homologues, making the separation of olefins and alkanes, and the separation of olefin components with different carbon numbers difficult.

[0008] The document "Adsorption Separation of 1,1,1,2-Tetrafluoroethane / 1,1-Difluoro-2-Chloroethylene by Ion-Modified Y Molecular Sieve" (Chemical Industry and Engineering Journal, 2014, Vol. 65, No. 10, pp. 3946-3952) reported that a mixture of 1,1,1,2-tetrafluoroethane / 1,1-difluoro-2-chloroethylene was separated by modified Y molecular sieves, and the adsorbent material was regenerated by thermal desorption. The regeneration efficiency was poor. This was mainly because the thermal desorption method would cause olefins to polymerize on the adsorbent material, and the generated polymers covered the adsorption sites of the adsorbent material, making it difficult to desorb effectively.

[0009] The document "Study on Dynamic Adsorption and Desorption Characteristics of Ethylene and Propylene in Dry Gas on Activated Carbon" (Journal of Chemical Engineering of Universities, 2013, Vol. 27, No. 4, pp. 547-554) reported that propylene and propane in dry gas were adsorbed and removed by activated carbon, and the activated carbon was regenerated by hydrogen purge, with a regeneration efficiency of about 91%. The document did not propose an effective solution for the separation of propylene, propane and desorbent (hydrogen).

[0010] Although studies have reported desorption and regeneration of olefin adsorbent materials by heating or desorbent purging, it is inevitable to encounter problems such as olefin polymerization caused by temperature desorption, accelerated deactivation of the adsorbent by coking, and difficulty in effectively separating the desorbent from the olefin. Summary of the invention

[0011] Based on the fact that olefins and alkanes have similar relative volatility and molecular size, which causes separation difficulties, the purpose of the present invention is to provide an adsorption separation process and application of a low-carbon olefin / alkane mixture. The process uses two adsorbers connected in series, respectively loaded with adsorbent materials with high selective adsorption functions for propylene and ethylene, and utilizes the difference in adsorption capacity of different adsorbent materials for specific components to separate propylene and ethylene from the low-carbon olefin / alkane system in turn. Not only can it effectively solve the problem of difficulty in efficient separation of olefins and alkanes due to their similar relative volatility and molecular size, but it can also achieve the separation and recovery of high-purity olefin single components.

[0012] At the same time, in view of the problem that olefin compounds adsorbed on traditional adsorbent materials are difficult to desorb, the present invention also provides a convenient and efficient desorption method that can be operated at room temperature and does not require vacuum operation. The effective desorption of olefins is achieved by sweeping the bed layer with a desorbent, avoiding the problem of easy polymerization of olefins and rapid deactivation of adsorbents due to coking during the temperature rise desorption process. It also avoids the high energy consumption caused by vacuum desorption and the low processing efficiency caused by repeated filling and release of pressure. The present invention can be used for the adsorption separation and purification of olefin / alkane mixtures in different scenarios, and can also be used for the separation and purification of olefin mixtures containing different carbon numbers (such as ethylene, propylene, butadiene, etc.). By selecting suitable adsorbent materials and higher adsorption and desorption operating temperatures, effective separation and recovery of single-component olefins in liquid hydrocarbon mixtures can also be achieved.

[0013] In addition, the chemical absorption method can be used to further separate olefins and carbon dioxide in the desorbent, thereby obtaining a high-purity single-component olefin product. Finally, the absorbent can be regenerated to desorb carbon dioxide, thereby achieving the purpose of carbon dioxide recycling.

[0014] The purpose of the present invention can be achieved by the following technical solutions:

[0015] The first aspect of the present invention provides an adsorption separation process for a low-carbon olefin / alkane mixture:

[0016] A method for adsorption separation of a low-carbon olefin / alkane mixture comprises: passing a mixed gas containing ethylene and / or propylene into an adsorber filled with an adsorption material to adsorb propylene and / or ethylene; after the adsorption is completed, passing a desorbent to obtain a propylene product or an ethylene product, and simultaneously completing the regeneration of the adsorption material.

[0017] An adsorption separation method for a mixture of low-carbon olefins / alkanes is based on an adsorption device, which comprises: two adsorbers capable of switching between series and parallel connection, an adsorption air inlet pipe connected to the preceding adsorber in the series state, and a desorbent feed pipe connected to the two adsorbers in the parallel state; adsorbent material is filled in the adsorber;

[0018] The adsorption separation process of the low-carbon olefin / alkane mixture can not only achieve efficient separation of alkanes and olefins, but also simultaneously realize the separation and recovery of high-purity olefin single components.

[0019] In some preferred embodiments, the total olefin content in the low-carbon olefin / alkane mixture is about 5 to 95%, preferably 10 to 50%, and more preferably 10 to 30% (by mass fraction).

[0020] In some preferred embodiments, the low-carbon olefin / alkane mixture is a hydrocarbon mixture containing ethylene, propylene and at least one low-carbon alkane, such as refinery dry gas.

[0021] In some preferred embodiments, the low carbon alkane includes any one of C1-C8 alkanes or a mixture thereof, preferably C1-C6 alkanes, more preferably C1-C5 alkanes. Preferably, it includes C1-C3 alkanes or a mixture thereof; for example, it can be a hydrocarbon mixture containing ethylene, propylene, methane, ethane, and propane.

[0022] The adsorption separation method comprises the following steps:

[0023] S1: Two adsorbers are connected in series, purged with inert gas, and then a mixed gas containing ethylene and propylene is introduced through the adsorption inlet pipe to adsorb propylene and ethylene;

[0024] In some preferred embodiments, in a series connection state, the front adsorber is filled with an adsorbent material having a highly selective adsorption function for propylene, and the rear adsorber is filled with an adsorbent material having a highly selective adsorption function for ethylene;

[0025] The bed volume of the adsorber is determined according to the composition of the low-carbon olefin / alkane mixture and the adsorption characteristics of the adsorbent material (such as penetration adsorption capacity, diffusion rate, etc.). Preferably, in the adsorber, the loading amount of the adsorbent material is 1 / 5-1, preferably 1 / 3-1, and more preferably 1 / 3-2 / 3 of the adsorber volume.

[0026] When the mixed gas passes through the first adsorber bed, the specific adsorbent material loaded in the bed selectively adsorbs propylene in the flow; when the material after the propylene component is removed passes through the second adsorber bed, the specific adsorbent material loaded in the bed (different from the adsorbent material loaded in the first adsorber) selectively adsorbs ethylene in the flow. Thus, the propylene and ethylene in the material can be adsorbed and removed in turn through the two adsorbers, so that a product containing a high concentration of alkane components is obtained at the outlet of the adsorption device;

[0027] S2: After the adsorption is completed, the operation is switched to desorption. Two adsorbers are connected in parallel to the desorbent feed pipe, and the desorbent is introduced. High-purity single-component products of propylene and ethylene can be collected at the outlets of the two adsorbers respectively, and the desorption regeneration of the adsorbent material can be achieved at the same time;

[0028] In the adsorption separation method of the light olefin / alkane mixture of the present invention, two adsorbers for selectively adsorbing propylene and ethylene in the adsorption separation device are operated in series during the adsorption process, and in parallel during desorption and regeneration. This method can not only achieve efficient separation of alkanes and olefins, but also realize the separation and recovery of high-purity olefin single components.

[0029] In some preferred embodiments, during the adsorption process, the adsorption temperature is 0-100° C., preferably 15-80° C., more preferably 15-35° C. The adsorption pressure is 1-10 bar, preferably 1-5 bar;

[0030] Mixed gas air speed is 1-20min -1 , preferably 1-10min -1 , preferably 2-10min -1 .

[0031] In some preferred embodiments, the adsorber includes one of a fixed bed adsorber, a fluidized bed adsorber, or a simulated moving bed adsorber, or a combination thereof, and more preferably, one of a fixed bed adsorber or a simulated moving bed adsorber, or a combination thereof.

[0032] The second aspect of the present invention provides an adsorbent material having a highly selective adsorption function for olefins loaded as described in the first aspect of the present invention.

[0033] In some preferred embodiments, in the series state, a propylene adsorption material is loaded in the front adsorber, and the propylene adsorption material includes a composite material of one or more structures of molecular sieve, metal organic framework material, covalent organic framework material, metal oxide or activated carbon; more preferably, it is a composite material of one or more structures of molecular sieve, metal organic framework material, activated carbon. The average pore size is 0.1-2.0nm, preferably 0.3-2.0nm, and more preferably 0.3-1.5nm. The adsorption energy for propylene is about 20-200kJ / mol, preferably 50-200kJ / mol, and more preferably 50-150kJ / mol, and the adsorption energy for alkanes is lower than that for propylene, and the difference in adsorption energy is >20kJ / mol.

[0034] The rear adsorber is filled with an ethylene adsorption material, which includes a composite material of one or more structures of molecular sieve, metal organic framework material, covalent organic framework material, metal oxide or activated carbon. More preferably, it is a composite material of one or more structures of molecular sieve, metal organic framework material, activated carbon. The average pore size is 0.2-2.0nm, preferably 0.2-1.0nm, and more preferably 0.2-0.6nm. The adsorption energy for ethylene is about 20-200kJ / mol, preferably 50-200kJ / mol, and more preferably 50-150kJ / mol. And it has a lower adsorption energy for alkanes than for ethylene, and the difference in adsorption energy is >20kJ / mol.

[0035] Further preferably, the adsorption material includes at least one of CaA molecular sieve, AgA molecular sieve, NiA molecular sieve or NiY molecular sieve.

[0036] The third aspect of the present invention provides a convenient and efficient desorption method that can be performed at room temperature and does not require vacuum operation. The effective desorption of olefins is achieved by effectively reducing the adsorption energy between the adsorbent material and the olefin compound, thereby avoiding the problems of easy polymerization of olefins and rapid coking and deactivation of the adsorbent during the temperature increase desorption process. At the same time, it also avoids the high energy consumption caused by vacuum desorption and the low processing efficiency caused by repeated filling and releasing of pressure.

[0037] In some preferred embodiments, the desorbent should be able to effectively reduce the adsorption energy between the adsorbent material and the olefin compound to achieve effective desorption of the olefin, and can be one or more of nitrogen, helium, argon, hydrogen, carbon dioxide, carbon monoxide, etc., preferably, carbon dioxide or a mixed gas containing a certain concentration of carbon dioxide.

[0038] In some preferred embodiments, when the desorbent is carbon dioxide or a mixed gas containing carbon dioxide, a chemical absorption method can be used to separate and recover the desorbent to obtain a high-purity single-component olefin product.

[0039] In some preferred embodiments, during the desorption process, the desorption temperature is 15-300°C, preferably 25-150°C, and more preferably 25-60°C; the desorption pressure is 1-10 bar, preferably 1-5 bar, and more preferably 1-2 bar; the desorption time is 1-10 h, preferably 1-5 h, and more preferably 2-4 h; the desorbent space velocity is 0.5-10 min -1 , preferably 1-10min -1 , preferably 1-5min -1 .

[0040] According to a preferred embodiment of the present invention, the adsorption performance of the regenerated adsorbent can reach 50-100% of that of the fresh adsorbent, preferably 75-100%, and more preferably 90-100%.

[0041] According to a preferred embodiment of the present invention, the principle of desorption and regeneration of the adsorbent material is that the addition of the desorbent can effectively reduce the adsorption energy between the adsorbent material and the olefin compound, thereby achieving effective desorption of the olefin, that is, completing the desorption and regeneration of the adsorbent material.

[0042] According to a preferred embodiment of the present invention, the mixture of olefins and desorbents in the desorbed gas can be easily and effectively separated by adsorption, chemical absorption, membrane separation and other processes to recover the olefin components and realize the recycling of the desorbent, preferably by chemical absorption.

[0043] In a fourth aspect of the present invention, an application of a method for adsorption separation of a mixture of low-carbon olefins / alkanes is provided. Those skilled in the art can design corresponding adsorption devices and load specific adsorption materials to meet the needs of other fields according to the requirements of the fields of chemistry, chemical engineering, energy, environmental protection, biology, medicine, electronics, and mechanics;

[0044] The method can be used for the adsorption separation and purification of olefin / alkane mixtures in different scenarios, and can also be used for the separation and purification of olefin mixtures with different carbon numbers (can be selected from any one of C2-C8 olefins or a mixture thereof, preferably C2-C6 olefins, more preferably C2-C4 olefins. Such as ethylene, propylene, butadiene, etc.). By selecting suitable adsorption materials and higher adsorption and desorption operating temperatures, effective separation and recovery of single-component olefins in liquid hydrocarbon mixtures can also be achieved.

[0045] According to a preferred embodiment of the present invention, by selecting suitable adsorption materials and higher adsorption and desorption operating temperatures, effective separation and recovery of single-component olefins in a liquid hydrocarbon mixture can also be achieved.

[0046] Compared with the prior art, the present invention has the following characteristics:

[0047] As described in the background technology section of the present invention, the prior art does disclose the use of different adsorbent materials to achieve the adsorption separation of alkanes and olefins in olefin / alkane mixtures. However, none of them has been able to achieve the separation and recovery of single components of olefins with different carbon numbers in complex hydrocarbon mixtures under actual working conditions, nor has an effective solution been proposed for this problem. Secondly, the prior art reports the desorption and regeneration of olefin adsorbent materials by heating or desorbent purging, which inevitably encounters problems such as olefin polymerization caused by temperature increase desorption, accelerated deactivation of the adsorbent due to coking, and difficulty in effectively separating the desorbent from the olefin.

[0048] However, in view of the above-mentioned difficulties, the present invention discloses an adsorption separation process for a mixture of low-carbon olefins / alkanes. By means of two adsorbers connected in series, adsorbent materials having a highly selective adsorption function for propylene and ethylene are respectively loaded, so that propylene and ethylene can be separated from the low-carbon olefin / alkanes system in turn, respectively, not only achieving efficient separation of alkanes and olefins, but also realizing separation and recovery of high-purity single-component olefins at the same time. In addition, the present invention also provides a convenient and efficient desorption method that can be operated at room temperature and does not require vacuum operation. The effective desorption of olefins is achieved by effectively reducing the adsorption energy between the adsorbent material and the olefin compound, avoiding the problem of easy polymerization of olefins and rapid coking and deactivation of the adsorbent during the temperature rise desorption process, and also avoiding the high energy consumption caused by vacuum desorption and the low processing efficiency caused by repeated filling and release of pressure. Finally, the olefins in the desorbed gas are further separated from the carbon dioxide desorbent by chemical absorption, thereby obtaining a high-purity single-component olefin product, and also achieving the purpose of recycling carbon dioxide. By using the adsorption separation process of a low-carbon olefin / alkane mixture provided by the present invention, the adsorption separation and purification of olefin / alkane mixtures in different scenarios can be achieved, and it can also be used for the separation and purification of olefin mixtures containing different carbon numbers (such as ethylene, propylene, butadiene, etc.). By selecting suitable adsorption materials and higher adsorption and desorption operating temperatures, the effective separation and recovery of single-component olefins in liquid hydrocarbon mixtures can also be achieved.

[0049] It should be understood that according to the ideas and methods proposed in the present invention, those skilled in the art can easily design other processes for sequentially separating single components of olefins with different carbon numbers by changing the number, size and adsorbent material of the adsorbers based on a typical series-connected adsorber device. The creativity of the present invention mainly lies in the first proposal of a process for sequentially adsorbing and separating single components of propylene and ethylene from a mixture of low-carbon olefins / alkanes.

[0050] In summary, according to the adsorption separation process and application of a low-carbon olefin / alkane mixture provided by the present invention, by changing the number, size and loaded adsorption material of the adsorber, other adsorption processes can be designed to meet the needs of other fields. The design concept of the present invention is clear, the process flow is simple, and the source of adsorption materials is wide, which greatly broadens the application of the designed process in adsorption, separation, catalysis, energy storage, drug delivery, electronic devices and the like.

[0051] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic structural diagram of an adsorption device in the present invention.

[0053] Figure 2 This is the olefin adsorption breakthrough curve of Example 1.

[0054] Figure 3 This is the olefin adsorption breakthrough curve of Example 2.

[0055] Figure 4 is the olefin adsorption breakthrough curve of Example 3. a and b are the olefin adsorption breakthrough curves of the first adsorber and the second adsorber, respectively.

[0056] Figure 5 is the olefin adsorption breakthrough curve of Example 4. a and b are the olefin adsorption breakthrough curves of the first adsorber and the second adsorber, respectively.

[0057] Figure 6 This is the olefin adsorption breakthrough curve of Example 5.

[0058] Figure 7 This is the olefin adsorption breakthrough curve of Example 6.

[0059] Figure 8 This is the olefin adsorption breakthrough curve of Example 7.

[0060] Fig. 9 This is the adsorbent regeneration efficiency diagram of Example 8.

[0061] Fig.10 This is the adsorbent regeneration efficiency diagram of Example 9.

[0062] Fig.11 This is a diagram of the hydrocarbon composition in the desorbed gas of Example 10.

[0063] Fig.12 This is a graph of the adsorbent regeneration efficiency of Example 10.

[0064] Fig.13 This is a graph of the adsorbent regeneration efficiency of Example 11.

[0065] Description of the markings in the figure:

[0066] 1-first adsorber, 2-second adsorber, 3-raw gas tank, 4-desorbent tank. DETAILED DESCRIPTION

[0067] Through extensive and in-depth research, the inventors unexpectedly discovered for the first time an adsorption separation process and application of a low-carbon olefin / alkane mixture. Compared with other adsorption separation processes, the adsorber series device designed by the present invention can successively separate propylene and ethylene from the low-carbon olefin / alkane system, not only achieving efficient separation of alkanes and olefins, but also realizing the separation and recovery of high-purity olefin single components. Through this method, other processes for successively separating single components of olefins with different carbon numbers can be designed, which greatly broadens the application of adsorption separation in other aspects. In addition, the present invention also provides a convenient and efficient desorption method that can be operated at room temperature and does not require vacuum, and effectively desorbs olefins by effectively reducing the adsorption energy between the adsorbent material and the olefin compound, thereby avoiding the problem of easy polymerization of olefins and rapid coking and deactivation of adsorbents during the temperature rise desorption process, and also avoiding the high energy consumption caused by vacuum desorption and the low processing efficiency caused by repeated filling and release of pressure. The present invention is completed on this basis. The present invention can be used for the adsorption separation and purification of olefin / alkane mixtures in different scenarios, and can also be used for the separation and purification of olefin mixtures containing different carbon numbers (such as ethylene, propylene, butadiene, etc.). By selecting appropriate adsorption materials and higher adsorption and desorption operating temperatures, effective separation and recovery of single-component olefins in liquid hydrocarbon mixtures can also be achieved.

[0068] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for the unrecorded specific conditions in the following examples are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and weight parts.

[0069] Unless otherwise specified, the experimental materials and reagents used in the following examples can be obtained from commercial channels.

[0070] In the following examples, the NaY molecular sieve powder, NaA molecular sieve powder and CaA molecular sieve powder used were purchased from Tianjin Nanhua Catalyst Co., Ltd.

[0071] An adsorption device specifically includes the following features:

[0072] (1) Connection method: Press Figure 1 Connect according to the connection method in the device structure diagram.

[0073] (2) Structural features of the adsorber: It is a metal component with a cylindrical body that can be heated and insulated by electric heating. It is filled with adsorbent material and can pass raw gas / desorbent. The inner diameter is 1.5 cm and the height is 80 cm. The gas flow direction in the connecting pipeline can be controlled by a valve.

[0074] The composition of the olefin / alkane mixed gas is: C2H4: 4.80%, C2H6: 48.65%, C3H6: 13.52%, C3H8: 33.03% (by mass fraction).

[0075] The schematic diagram of the adsorption device used is shown in Figure 1 As shown, it includes a raw gas tank 3 for storing olefin / alkane mixed gas, a desorbent tank 4 for storing desorbent, and a first adsorber 1 and a second adsorber 2. Among them, the first adsorber 1 and the second adsorber 2 are fixed bed adsorbers. The top and bottom of the first adsorber 1 and the second adsorber 2 are respectively provided with a feeding pipe and a feeding pipe. The raw gas tank 3 is connected to the main adsorption pipe, and is then connected to the top feeding pipe of the first adsorber 1 and the top feeding pipe of the second adsorber 2 through the first adsorption branch pipe and the second adsorption branch pipe respectively. A series branch connected to the top feeding pipe of the second adsorber 2 is provided on the bottom feeding pipe of the first adsorber 1, and a series branch valve is provided on the series branch. By opening the series branch valve and closing the branch valve on the second adsorption branch, the series adsorption operation of the raw gas by the first adsorber 1 and the second adsorber 2 can be realized. Feed pipe valves are also provided on the bottom feeding pipes of the first adsorber 1 and the second adsorber 2, respectively, to cooperate with the series branch to form a series adsorption pipeline.

[0076] The desorbent tank 4 is connected to the main desorption pipe, and is further connected to the bottom feed pipes of the first adsorber 1 and the second adsorber 2 through the first desorption branch pipe and the second desorption branch pipe, respectively, so that the desorbent is introduced into the beds of the first adsorber 1 and the second adsorber 2 in parallel for parallel desorption operation.

[0077] Embodiment 1:

[0078] NaY molecular sieve powder was mixed with 0.5M NiCl2 solution at a mass ratio of 1:10, stirred at 80°C for 5h, and NiY molecular sieve was obtained after suction filtration, washing and drying.

[0079] 5 g of NiY molecular sieve was weighed and calcined in a muffle furnace at 450°C under air atmosphere for 4 h. It was quickly taken out and placed in a desiccator for cooling, and then quickly added to a homemade quartz fixed bed adsorption column, maintaining the column temperature at 30°C.

[0080] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The adsorption breakthrough curves of NiY molecular sieve for ethylene and propylene were obtained by using a gas chromatograph equipped with a FID detector. Figure 2 As shown in the figure, the penetration adsorption capacity of NiY sample for ethylene and propylene are 6.2 mg / g and 104.8 mg / g respectively (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0081] Embodiment 2:

[0082] NaA molecular sieve powder was mixed with 0.1M AgNO3 solution at a mass ratio of 1:10, stirred at 80°C for 2h, and AgA molecular sieve was obtained after suction filtration, washing and drying.

[0083] Weigh 5 g of AgA sample and calcine it in a muffle furnace at 450°C in air atmosphere for 4 h. Then take it out quickly and cool it in a desiccator. Then quickly add it to the homemade quartz fixed bed adsorption column and maintain the column temperature at 30°C.

[0084] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The adsorption breakthrough curves of ethylene and propylene by AgA molecular sieve were obtained by gas chromatograph equipped with FID detector. Figure 3 As shown in the figure, the penetration adsorption capacity of AgA sample for ethylene and propylene are 11.2 mg / g and 23.7 mg / g respectively (taking Ct / C0=0.05 as the adsorption penetration point).

[0085] Embodiment 3:

[0086] Weigh 5 g of the NiY molecular sieve prepared in Example 1 and 5 g of the AgA molecular sieve prepared in Example 2, respectively, and calcine them in a muffle furnace at 450° C. in an air atmosphere for 4 h. Take them out quickly and place them in a dryer for cooling. Then, fill them into the first adsorber 1 and the second adsorber 2 respectively. Connect the two adsorption columns in series (such as Figure 1 The column temperature was maintained at 30°C using a thermostatic water bath.

[0087] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min. The outlet gas of the fixed bed adsorption column 1 and 2 was sampled every 2 minutes using an aluminum foil sampling bag. The gas chromatograph equipped with an FID detector was used for analysis to obtain the adsorption breakthrough curves of the two adsorption column beds, as shown in Figure 2. Figure 4 -a,b as shown.

[0088] The penetration adsorption capacity of the NiY sample in the first adsorber 1 for ethylene and propylene are 6.1 mg / g and 105.1 mg / g respectively; the penetration adsorption capacity of the AgA sample in the second adsorber 2 for ethylene and propylene are 36.9 mg / g and 23.9 mg / g respectively (Ct / C0=0.05 is taken as the adsorption penetration point).

[0089] Embodiment 4:

[0090] Weigh 25 g of each of the NiY molecular sieve prepared in Example 1 and the AgA molecular sieve prepared in Example 2, and fill them into the pilot test device (such as Figure 1 ) in the first adsorber 1 and the second adsorber 2, the pipelines were switched to a parallel state, nitrogen was introduced, and the NiY molecular sieve and the AgA molecular sieve were activated at 450°C for 4 hours under a nitrogen atmosphere. After the activation was completed, the nitrogen atmosphere was maintained and the bed temperature was cooled to 30°C.

[0091] At the beginning of the adsorption experiment, the nitrogen was turned off, the pipeline was switched to a series state, and the olefin / alkane mixture was introduced into the fixed bed adsorber bed at a gas flow rate of 110 mL / min. The two bed outlets were sampled using an aluminum foil sampling bag every 10 minutes. The gas chromatograph equipped with an FID detector was used for analysis to obtain the adsorption breakthrough curves of the two fixed bed adsorption columns, as shown in Figure 1. Figure 5 -a,b as shown.

[0092] The penetration adsorption capacity of NiY molecular sieve for ethylene and propylene in the first adsorber 1 is 0 and 112.9 mg / g respectively; the penetration adsorption capacity of AgA molecular sieve for ethylene and propylene in the second adsorber 2 is 37.8 mg / g and 14.7 mg / g respectively (Ct / C0=0.05 is taken as the adsorption penetration point).

[0093] Embodiment 5:

[0094] Weigh 5 g of CaA sample and calcine it in a muffle furnace at 450 °C in air atmosphere for 4 h. Take it out quickly and place it in a desiccator to cool it. Then quickly add it to the homemade quartz fixed bed adsorption column, and use a constant temperature water bath to maintain the column temperature at 30 °C.

[0095] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The adsorption breakthrough curves of CaA molecular sieve for ethylene and propylene were obtained by using a gas chromatograph equipped with an FID detector. Figure 6 As shown, the penetration adsorption capacity of CaA molecular sieve for ethylene and propylene are 11.3 mg / g and 54.1 mg / g respectively (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0096] Embodiment 6:

[0097] The CaA molecular sieve powder was mixed with 0.05M NiCl2 solution at a mass ratio of 1:10, stirred at 80°C for 2h, and the NiA molecular sieve was obtained after suction filtration, washing and drying.

[0098] 5 g of NiA sample was weighed and calcined in a muffle furnace at 450 °C in air atmosphere for 4 h. It was quickly taken out and placed in a desiccator for cooling, then quickly added to a homemade quartz fixed bed adsorption column, and a constant temperature water bath was used to maintain the column temperature at 30 °C.

[0099] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The adsorption breakthrough curves of NiA molecular sieve for ethylene and propylene were obtained by using a gas chromatograph equipped with a FID detector. Figure 7 As shown in the figure, the penetration adsorption capacity of AgA sample for ethylene and propylene are 10.3 mg / g and 44.3 mg / g respectively (taking Ct / C0=0.05 as the adsorption penetration point).

[0100] Embodiment 7:

[0101] The CaA molecular sieve powder was mixed with 0.1M AgNO3 solution at a mass ratio of 1:10, stirred at 80°C for 2h, and then filtered, washed and dried to obtain the AgA molecular sieve.

[0102] Weigh 5 g of AgA sample and calcine it in a muffle furnace at 450°C in air atmosphere for 4 h. Then take it out quickly and cool it in a desiccator. Then add it quickly to a homemade quartz fixed bed adsorption column and use a constant temperature water bath to maintain the column temperature at 30°C.

[0103] At the beginning of the adsorption experiment, the olefin / alkane mixed gas was controlled by a flow meter to pass into the adsorption column at 84 mL / min, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The adsorption breakthrough curves of ethylene and propylene by AgA molecular sieve were obtained by gas chromatograph equipped with FID detector. Figure 8 As shown in the figure, the penetration adsorption capacity of AgA sample for ethylene and propylene are 12.4 mg / g and 34.9 mg / g respectively (taking Ct / C0=0.05 as the adsorption penetration point).

[0104] Embodiment 8:

[0105] The adsorption experiment was carried out according to the method of Example 6. The adsorption was stopped at 100 min of adsorption time. The two adsorption columns were connected in parallel and the process was switched to desorption. The desorbent CO2 was continuously introduced into the two fixed bed adsorption columns at 50 mL / min for desorption. Desorbed samples 1 and 2 were collected at the outlets of adsorbers 1 and 2, respectively. After gas chromatography analysis with an FID detector, the propylene content of desorbed sample 1 (without considering the desorbent) and the ethylene content of desorbed sample 2 (without considering the desorbent) were both greater than 95%.

[0106] After 30 minutes of desorption, the two adsorption columns were connected in series and the adsorption experiment was carried out according to the same adsorption steps as above. The olefin / alkane mixed gas was passed into the adsorption column at a rate of 84 mL / min using a flow meter. The gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The total penetration adsorption capacity of the regenerated NiA molecular sieve for olefins was obtained by gas chromatography and compared with that of the fresh adsorbent. This process was repeated three times. Fig. 9 After the NiA molecular sieve was regenerated three times, the total breakthrough adsorption capacity for olefins was still higher than 95% of that of the fresh adsorbent (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0107] Embodiment 9:

[0108] An adsorption experiment was carried out according to the method of Example 7. The adsorption was stopped when the adsorption time was 100 min. The two adsorption columns were connected in parallel and the process was switched to desorption. The desorbent N2 was continuously introduced into the two fixed bed adsorption columns at 50 mL / min for desorption for 30 min. Subsequently, an adsorption experiment was carried out according to the same adsorption steps as above. A flow meter was used to control the olefin / alkane mixed gas to pass into the adsorption column at 84 mL / min. An aluminum foil sampling bag was used to sample the gas at the outlet of the adsorption column every 2 min. A gas chromatograph was used for analysis to obtain the total penetration adsorption capacity of the regenerated AgA molecular sieve for olefins, and compared with the fresh adsorbent. This process was repeated three times. Fig.10 As shown, after AgA molecular sieve is regenerated three times, the total breakthrough adsorption capacity for olefins is about 50% of that of the fresh adsorbent (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0109] Embodiment 10:

[0110] After the experiment was carried out according to the experimental steps in Example 5, the desorbent CO2 was continuously introduced into the fixed bed adsorption column at 50 mL / min using a flow meter for 30 min. For the first 8 min of the desorption process, the desorbent was sampled every 2 min using an aluminum foil sampling bag and analyzed using a gas chromatograph. The hydrocarbon composition of the desorbent was as follows: Fig.11 shown.

[0111] Then, the same method as in Example 5 was used to control the olefin / alkane mixed gas to pass into the adsorption column at 84 mL / min using a flow meter, and the gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The total breakthrough adsorption capacity of the regenerated CaA molecular sieve for olefins was obtained by gas chromatography and compared with that of the fresh adsorbent. This process was repeated three times. Fig.12 After the CaA sample was regenerated three times, the total breakthrough adsorption capacity for olefins was still higher than 85% of the fresh adsorbent (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0112] Embodiment 11:

[0113] After the experiment was carried out according to the experimental steps in Example 7, the adsorber bed was vacuum desorbed for 30 minutes using a vacuum pump. Then, the same method as in Example 7 was used, and a flow meter was used to control the olefin / alkane mixed gas to pass into the adsorption column at 84 mL / min. The gas at the outlet of the adsorption column was sampled every 2 minutes using an aluminum foil sampling bag. The total penetration adsorption capacity of the regenerated AgA molecular sieve for olefins was obtained by analysis using a gas chromatograph and compared with that of the fresh adsorbent. This process was repeated three times. Fig.13 As shown, after AgA molecular sieve is regenerated three times, the total breakthrough adsorption capacity for olefins is about 30% of that of the fresh adsorbent (taking Ct / C0=0.05 as the adsorption breakthrough point).

[0114] The present invention obtains an adsorption separation process and application of a low-carbon olefin / alkane mixture by designing an adsorber series device (and loading adsorbent materials with high selective adsorption function for propylene and ethylene respectively). Compared with other olefin / alkane mixture adsorption separation processes, the present invention is oriented to complex hydrocarbon mixtures under actual working conditions, not only achieving efficient separation of alkanes and olefins, but also realizing separation and recovery of high-purity olefin single components. In addition, the present invention also provides a convenient and efficient desorption method that can be operated at room temperature and does not require vacuum, which can achieve efficient desorption and regeneration of olefin adsorption materials, avoid the problems of easy polymerization of olefins and rapid coking and deactivation of adsorbents during the temperature increase desorption process, and also avoid the problems of high energy consumption caused by vacuum desorption and low processing efficiency caused by repeated filling and release of pressure. According to the process design method proposed by the present invention, by changing the number, size and type of adsorbent loaded in the adsorber, it is easy to design other processes for sequentially separating single components of olefins with different carbon numbers, which greatly broadens the application of adsorption separation in other aspects.

[0115] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for the adsorption separation of a mixture of light olefins / alkanes, characterized in that: The method is based on an adsorption device, which includes: two adsorbers capable of switching between series and parallel connection, an adsorption air inlet pipe connected to the preceding adsorber in the series state, and a desorbent feed pipe connected to the two adsorbers in the parallel state; adsorbent material is filled in the adsorber; The adsorption separation method comprises the following steps: S1: two adsorbers are arranged in series, and an olefin / alkane mixed gas containing ethylene and propylene is introduced through an adsorption inlet pipe, propylene and ethylene components in the mixed gas are adsorbed, and a mixture of alkane components without olefins flows out and is collected as a product; wherein the front adsorber is filled with a propylene adsorption material, which is a NiY molecular sieve; and the rear adsorber is filled with an ethylene adsorption material, which includes at least one of a CaA molecular sieve, an AgA molecular sieve or a NiA molecular sieve; S2: Two adsorbers are connected in parallel to the desorbent feed pipe, and the desorbent is introduced to obtain propylene product or ethylene product respectively, and the adsorbent material is regenerated at the same time; the desorbent is carbon dioxide, and during the desorption process, the desorption temperature is 25-60°C, the desorption pressure is 1-2 bar, the desorption time is 2-4 h, and the desorbent space velocity is 1-5 min -1 ; The desorbent is separated and recovered from the absorbent by a chemical absorption method for recycling.

2. The method for adsorption separation of a light olefin / alkane mixture according to claim 1, characterized in that: The adsorber includes one or more combinations of a fixed bed adsorber, a fluidized bed adsorber or a simulated moving bed adsorber.

3. The method for adsorption separation of a light olefin / alkane mixture according to claim 1, characterized in that: The mixed gas also includes low-carbon alkanes, and the low-carbon alkanes include at least one of methane, ethane, and propane.

4. The method for adsorption separation of a light olefin / alkane mixture according to claim 1, characterized in that: In the adsorber, the amount of adsorbent material filled is 1 / 5-1 of the adsorber volume; During the adsorption process, the adsorption temperature is 0-100°C, the adsorption pressure is 1-10 bar, and the mixed gas space velocity is 1-20 min -1 .

5. The method for adsorption separation of a light olefin / alkane mixture according to claim 1, characterized in that: In step S1, before the mixed gas is introduced, an inert gas is used for purging.

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