Modified A-type molecular sieve and application thereof in ethylene separation

Abstract

The invention relates to the field of adsorption separation, and discloses a modified A-type molecular sieve and application thereof in separation of ethylene, and a method for separating ethylene comprises the following steps: contacting a mixed gas containing ethane and ethylene with a separation adsorbent under an adsorption condition for selective adsorption, and then desorbing ethylene from the separation adsorbent under a desorption condition. The separation adsorbent provided by the invention has the characteristics of high adsorption capacity, high selectivity and high stability, the preparation method is simple, the yield of the modified A type molecular sieve is high, meanwhile, the ethylene separation method can be carried out at low temperature and low pressure, the operation method is simple, the industrial operation cost is low, and the separation adsorbent has a relatively strong industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of adsorption separation, specifically to a modified type A molecular sieve and its application in the separation of ethylene, and more specifically to a method for separating ethylene, a modified type A molecular sieve and its preparation method, and a separation adsorbent and its preparation method. Background Technology

[0002] Ethylene is a crucial basic chemical raw material and a vital bridge between oil and chemical industries, with its production, apparent consumption, and demand increasing year by year. In many ethylene production processes, after gas separation, ethylene and ethane coexist. Because ethylene and ethane have similar physicochemical properties, separation is challenging. Currently, industrial processes typically employ cryogenic distillation, which requires high pressure (0.7-2.8 MPa), extremely low temperature (-160℃), and high tray count (>100) and reflux ratio (2.5-4) in distillation columns. This results in high energy consumption, large investment, and complex operation. Therefore, there is an urgent need to develop efficient, energy-saving, and environmentally friendly methods for ethylene concentration.

[0003] CN108456553A relates to a dry gas separation system and method based on argon cycle refrigeration. It can be used to separate dry gas to obtain polymer-grade ethylene and to improve methane recovery rate when used for purge gas separation. However, the high operating pressure and energy consumption of conventional cryogenic methods restrict the widespread application of this method.

[0004] CN114602337A relates to a mixed matrix gas separation membrane, its preparation method, and its application in ethane-ethylene separation, belonging to the field of membrane separation technology. CN101548147A relates to a distillation method that can separate light hydrocarbon streams of ethylene, ethane, and C3+ hydrocarbons into ethylene streams, ethane streams, and C3+ hydrocarbon streams.

[0005] CN113577981A utilizes biochar to prepare oxygen-containing microporous activated carbon, enabling the simple one-step adsorption separation of ethylene and ethylene mixtures. Given that the cations residing in the molecular sieve channels, used to balance the negative charge of the molecular sieve framework, can form π-complexing forces with the unsaturated bonds of ethylene, and that these π-complexing forces are stronger than van der Waals forces but weaker than chemical forces, molecular sieve adsorbents exhibit superior adsorption and regeneration performance in applications such as deep desulfurization of fuel oil, separation of olefins and alkanes, and adsorption of harmful substances. However, current methods for separating ethylene and ethylene using molecular sieves or porous materials at room temperature and pressure suffer from drawbacks such as low adsorption capacity, low selectivity, and poor stability, hindering further development for industrial applications. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low adsorption capacity, low selectivity and poor stability in the prior art, and to provide a method for separating ethylene, a modified type A molecular sieve and its preparation method, and a separation adsorbent and its preparation method.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for separating ethylene, the method comprising: contacting a mixed gas containing ethane and ethylene with a separation adsorbent under adsorption conditions for selective adsorption, and then desorbing ethylene from the separation adsorbent under desorption conditions, wherein the separation adsorbent comprises a modified type A molecular sieve and a binder, the modified type A molecular sieve being a type A molecular sieve doped with a loaded metal element and a modified metal element, wherein the loaded metal element is selected from at least one of group 10 and 11 metal elements, and the modified metal element is selected from at least one of Sn, Bi, and Te; wherein, based on the total weight of the modified type A molecular sieve, the content of the type A molecular sieve is 75-98.3 wt%, the content of the loaded metal element is 0.7-15 wt%, and the content of the modified metal element is 1-10.6 wt%.

[0008] A second aspect of the present invention provides a modified type A molecular sieve, wherein the modified type A molecular sieve is the modified type A molecular sieve defined in the above-described method or the modified type A molecular sieve prepared in the above-described method.

[0009] A third aspect of the present invention provides a method for preparing a modified type A molecular sieve, wherein the method is the method for preparing a modified type A molecular sieve as defined above.

[0010] A fourth aspect of the present invention provides a separation adsorbent, which is a separation adsorbent defined in the above-described method or a separation adsorbent prepared by the above-described method.

[0011] The fifth aspect of the present invention provides a method for preparing a separation adsorbent, wherein the method is the method for preparing a separation adsorbent as defined above.

[0012] Through the above technical solution, the present invention has achieved at least the following beneficial effects:

[0013] (1) The separation adsorbent provided by the present invention has the characteristics of high adsorption capacity, high selectivity, high stability and high sulfur resistance.

[0014] (2) The preparation method of the separation adsorbent provided by the present invention is simple, and the modified type A molecular sieve prepared by the preparation method of the modified type A molecular sieve provided by the present invention has a high yield.

[0015] (3) The method for separating ethylene provided by the present invention can be carried out at low temperature and low pressure, the operation method is simple, the industrial operating cost is low, and it has strong industrial application prospects. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of this invention provides a method for separating ethylene, the method comprising: contacting a mixed gas containing ethane and ethylene with a separation adsorbent under adsorption conditions for selective adsorption, and then desorbing ethylene from the separation adsorbent under desorption conditions, wherein the separation adsorbent comprises a modified type A molecular sieve and a binder, the modified type A molecular sieve being a type A molecular sieve doped with a loaded metal element and a modified metal element (i.e., the modified type A molecular sieve refers to a product obtained by simultaneously modifying type A with a loaded metal element and a modified metal element, preferably a modified type A molecular sieve prepared according to the following method), wherein the loaded metal element is selected from at least one of group 10 and 11 metal elements, and the modified metal element is selected from at least one of Sn, Bi, and Te; wherein, based on the total weight of the modified type A molecular sieve, the content of the type A molecular sieve is 75-98.3 wt%, the content of the loaded metal element is 0.7-15 wt%, and the content of the modified metal element is 1-10.6 wt%.

[0018] In a preferred embodiment of the present invention, the modified metal elements are Bi and Sn in combination, resulting in a separation adsorbent with higher selectivity and stability, and better sulfur resistance. Specifically, based on the total weight of the modified type A molecular sieve, the content of the Bi element is 0.2-1.5 wt% (for example, it can be any two values ​​from 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, and values ​​within that range), and the content of the Sn element is 0.5-2 wt% (for example, it can be any two values ​​from 0.5 wt%, 0.7 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, and values ​​within that range).

[0019] In this invention, preferably, the content of the modified type A molecular sieve is 90-97 wt% and the content of the binder is 3-10 wt% based on the total dry weight of the separating adsorbent.

[0020] In this invention, preferably, the separating adsorbent is a spherical particle with an average particle size of 0.3-0.6 mm.

[0021] In this invention, the binder is a commonly used binder in the art for preparing modified molecular sieves into mixed powders. Preferably, the binder is selected from at least one of kaolin, bentonite, montmorillonite, diatomite, palygorskite, and halloysite.

[0022] In this invention, preferably, the type A molecular sieve is selected from at least one of 3A, 4A, and 5A molecular sieves, more preferably 4A and / or 5A molecular sieves.

[0023] In a preferred embodiment of the present invention, the average grain size of the type A molecular sieve is ≤1μm, preferably ≤0.9μm, more preferably 0.7-0.85μm; and the relative crystallinity is ≥80%, preferably ≥90%.

[0024] In this invention, preferably, the loaded metal element is selected from at least one of Cu, Pd, Ag, Pt and Ni.

[0025] In a preferred embodiment of the present invention, the loaded metal elements are a combination of Pt and Ni, resulting in a separation adsorbent with higher selectivity and stability, and better sulfur resistance. Specifically, based on the total weight of the modified type A molecular sieve, the content of Pt is 1-3 wt% (e.g., it can be any two values ​​from 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.3 wt%, 2.5 wt%, 2.7 wt%, 3 wt%, or any value within that range), and the content of Ni is 0.1-1.5 wt% (e.g., it can be any two values ​​from 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.3 wt%, 1.5 wt%, or any value within that range).

[0026] In this invention, preferably, based on the total weight of the modified type A molecular sieve, the content of the type A molecular sieve is 80-97.5 wt% (for example, it can be any two values ​​from 80 wt%, 82 wt%, 85 wt%, 88 wt%, 90 wt%, 93 wt%, 95 wt%, 97.5 wt%, or any value within that range), the content of the loaded metal is 1-12 wt% (for example, it can be any two values ​​from 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, or any value within that range), and the content of the modified metal is 1.3-5 wt% (for example, it can be any two values ​​from 1.3 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%).

[0027] In this invention, there are no particular limitations on the adsorption and desorption conditions, as long as the adsorbent can be properly adsorbed and desorbed. Preferably, the adsorption conditions include: an adsorption temperature of 10-40℃, more preferably 20-30℃; and an adsorption pressure of 0.5-1 MPa, more preferably 0.6-0.8 MPa. Preferably, the desorption conditions include: a desorption temperature of 80-200℃, more preferably 80-120℃; and a desorption pressure of 0.001-0.1 MPa, more preferably 0.005-0.08 MPa.

[0028] In this invention, preferably, the mass hourly space velocity (MSV) of the mixed gas containing ethane and ethylene is 0.3-3 h⁻¹. -1 More preferably 2-3h -1 .

[0029] In this invention, preferably, the method for separating ethylene further includes: activating the separating adsorbent in the presence of a protective gas before the separating adsorbent comes into contact with the mixed gas containing ethane and ethylene.

[0030] In this invention, preferably, the activation conditions include: an activation temperature of 150-450℃, more preferably 200-400℃; and an activation time of 30-180 min, more preferably 60-150 min.

[0031] In this invention, the protective gas can be a gas commonly used in the art to provide an inert atmosphere. Preferably, the protective gas is selected from at least one of nitrogen, argon, or helium. Activation in the aforementioned protective gas can further improve the separation effect.

[0032] In a preferred embodiment of the present invention, the supported metal element and the modified metal element may exist in the form of oxides, sulfides or salts, and more preferably, the supported metal element and the modified metal element exist in the form of oxides or chlorides.

[0033] In this invention, because the separation adsorbent of this invention has a strong tolerance to sulfides, it can treat mixed gases containing sulfides. That is, the mixed gas containing ethane and ethylene may also contain 0-100 ppm of sulfides, wherein the sulfides include, but are not limited to, at least one of H2S, SO2, and COS (carbonyl sulfide).

[0034] In a preferred embodiment of the present invention, the selective adsorption can be carried out in a fixed bed or a moving bed.

[0035] In a preferred embodiment of the present invention, when a mixed gas containing ethylene and ethane is contacted with a bed of separation adsorbent for selective adsorption, the ethylene content in the tail gas after passing through the bed of separation adsorbent is determined using an Agilent 7890A gas chromatograph. Selective adsorption is stopped when an ethylene signal can be detected in the tail gas.

[0036] In this invention, the preparation method of the modified type A molecular sieve includes: mixing a solution containing loaded metal ions and modified metal ions with a type A molecular sieve for ion exchange, wherein the weight ratio of the loaded metal ions to the type A molecular sieve is 5-200:100, and the weight ratio of the modified metal ions to the type A molecular sieve is 50-160:100; the metal element in the loaded metal ions is selected from at least one of group 10 and 11 metal elements, and the metal element in the modified metal ions is selected from at least one of Sn, Bi, and Te.

[0037] In this invention, preferably, the metal element in the loaded metal ion is selected from at least one of Cu, Pd, Ag, and Pt.

[0038] In this invention, preferably, the mass ratio of the loaded metal ions to the type A molecular sieve is 6-135:100; the mass ratio of the modified metal ions to the type A molecular sieve is 55-145:100.

[0039] In this invention, preferably, the solvent in the solution containing loaded metal ions and modified metal ions can be a solvent commonly used in the art for dissolving loaded metal ions and modified metal ions, such as water; the amount of solvent is not particularly required, as long as it is sufficient to prepare modified type A molecular sieves, for example, the mass ratio of water to type A molecular sieves is 10-40:1, more preferably 15-35:1.

[0040] In this invention, preferably, the ion exchange conditions include: an ion exchange temperature of 50-90℃ and an ion exchange time of 30-120 min; more preferably, the ion exchange temperature is 60-90℃ and the ion exchange time is 40-100 min. The ion exchange can be completed in one step or in steps. Specifically, when a solution containing loaded metal ions and a solution containing modified metal ions are mixed stepwise with a type A molecular sieve for ion exchange, the ion exchange time is the single-cycle exchange time; when solutions containing loaded metal ions and modified metal ions are mixed with a type A molecular sieve for ion exchange, the ion exchange time is the total exchange time.

[0041] In a preferred embodiment of the present invention, the method for preparing modified type A molecular sieve may further include stepwise mixing of a solution containing metal ions and a solution containing modified metal ions with the type A molecular sieve for ion exchange. One stepwise preparation method may involve mixing loaded metal ions with the type A molecular sieve for ion exchange to obtain sample A, and then mixing modified metal ions with sample A for ion exchange to obtain the modified type A molecular sieve. Another stepwise preparation method involves mixing modified metal ions with the type A molecular sieve for ion exchange to obtain sample B, and then mixing loaded metal ions with sample B for ion exchange to obtain the modified type A molecular sieve.

[0042] In a preferred embodiment of the present invention, the preparation method of the modified type A molecular sieve further includes: solid-liquid separation (e.g., filtration) of the modified type A molecular sieve obtained after ion exchange, washing, drying, and calcining. The washing can be performed using deionized water to wash the modified type A molecular sieve obtained after ion exchange until neutral. The drying temperature can be 100-110℃ (e.g., any two values ​​from 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, or values ​​within that range); the drying time can be 0.5-10h, preferably 1-6h (e.g., any two values ​​from 1h, 2h, 3h, 4h, 5h, 6h, or values ​​within that range); the calcination temperature can be 200-420℃, preferably 250-400℃ (e.g., 1-200-1 ... For example, it can be any two values ​​formed by 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, and 400℃, or the values ​​within that range; the roasting time can be 1-10h, preferably 2-8h (for example, it can be any two values ​​formed by 2h, 3h, 4h, 5h, 6h, 7h, and 8h, or the values ​​within that range).

[0043] In a preferred embodiment of the present invention, the loaded metal ions and modified metal ions may exist in the form of oxides, sulfides or salts, and more preferably, the loaded metal ions and modified metal ions exist in the form of oxides or chlorides.

[0044] In this invention, the loading of metal components in the modified type A molecular sieve is obtained by X-ray fluorescence spectroscopy, for example, by using a ZSX100EX X-ray fluorescence spectrometer from Rigaku Corporation of Japan, with a tube voltage of 40kV and a tube current of 250mA. Elemental analysis is performed by utilizing the relationship that the intensity of the fluorescence rays of each element is proportional to its concentration.

[0045] In this invention, the method for preparing the separation adsorbent includes: mixing the modified type A molecular sieve prepared by the above method with a binder.

[0046] In this invention, based on the total dry weight of the separating adsorbent, the content of the modified type A molecular sieve is 90-97 wt%, and the content of the binder is 3-10 wt%.

[0047] In a preferred embodiment of the present invention, deionized water can be added to the separating adsorbent to form small spheres as needed. For example, the spheres can have a particle size of 0.3-0.6 mm, and the content of deionized water can be 0-15 wt% based on the total weight of the separating adsorbent.

[0048] According to a preferred embodiment of the present invention, the method for separating ethylene comprises: (1) preparing a modified type A molecular sieve as described above, and mixing the obtained modified type A molecular sieve with a binder to form a separation adsorbent; (2) selectively adsorbing a mixed gas containing ethane and ethylene with the separation adsorbent obtained in step (1) under adsorption conditions, and then desorbing ethylene from the separation adsorbent under desorption conditions. In this preferred embodiment, the conditions of each step, etc., can be performed as described above.

[0049] A second aspect of the present invention provides a modified type A molecular sieve, wherein the modified type A molecular sieve is the modified type A molecular sieve defined in the above-described method or the modified type A molecular sieve prepared in the above-described method.

[0050] A third aspect of the present invention provides a method for preparing a modified type A molecular sieve, wherein the method is the method for preparing a modified type A molecular sieve as defined above.

[0051] In this invention, the preparation method of the modified type A molecular sieve is the same as the preparation method of the modified type A molecular sieve described above, and will not be repeated here.

[0052] A fourth aspect of the present invention provides a separation adsorbent, which is a separation adsorbent defined in the above-described method or a separation adsorbent prepared by the above-described method.

[0053] The fifth aspect of the present invention provides a method for preparing a separation adsorbent, wherein the method is the method for preparing a separation adsorbent as defined above.

[0054] In this invention, the preparation method of the separation adsorbent is the same as that of the separation adsorbent described above, and will not be repeated here.

[0055] The present invention will be described in detail below through examples. Unless otherwise specified, all conditions in the following examples and comparative examples were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products. The average crystallite size of the 4A molecular sieve is 2.5 μm, and its relative crystallinity is 87%; the average crystallite size of the 5A molecular sieve is 2.5 μm, and its relative crystallinity is 86%.

[0056] In the following examples and comparative examples, the volume ratio of ethylene to ethane after desorption was determined using an Agilent 7890A gas chromatograph. The volume ratio of ethylene to ethane was determined by measuring the ratio of the peak areas of ethylene and ethane after desorption from the separation adsorbent.

[0057] The ethylene adsorption capacity of the separation adsorbent can be determined by a Hiden Isochema Intelligent Gravimetric Adsorption Analyzer (IGA) at a test temperature of 30°C and a test pressure of 0-100 kPa.

[0058] The ethylene selectivity of the separation adsorbent can be calculated using the IAST-DSLF model.

[0059] The volume growth rate of ethylene adsorbed in a single instance = (volume percentage of ethylene adsorbed in a single instance - 50) / 50.

[0060] The ethylene adsorption reduction rate after 30 cycles = (percentage of ethylene volume adsorbed in a single cycle - percentage of ethylene volume after 30 cycles) / percentage of ethylene volume adsorbed in a single cycle.

[0061] Intake A consists of ethylene and ethane in a volume ratio of 1:1.

[0062] Intake B consists of intake A and sulfur-containing gas at a concentration not exceeding 100 ppm. The specific ppm concentration and composition of the sulfur-containing gas have been specified in the examples.

[0063] The loading of metal components in the modified type A molecular sieve was determined using a Rigaku ZSX100EX X-ray fluorescence spectrometer (40 kV, 250 mA). Elemental analysis was performed based on the proportionality between the intensity of fluorescence rays and the concentration of each element. Table 2 shows the loaded metal elements and the loading amounts of modified metal elements in the modified type A molecular sieves of the examples and comparative examples. The content of type A molecular sieve in the modified type A molecular sieve = 1 - percentage content of loaded metal elements determined by fluorescence spectroscopy - percentage content of modified metal elements determined by fluorescence spectroscopy.

[0064] Example 1

[0065] (1) Preparation of modified type A molecular sieves

[0066] 4 g of 5A molecular sieve was weighed and mixed with 0.99 g of Cu(NO3)2·6H2O and 60 g of deionized water. Ion exchange was performed at 60 °C for 90 min, followed by filtration and washing with deionized water until neutral. The mixture was then dried at 100 °C for 1 h and calcined at 250 °C for 8 h. The calcined sample was then mixed with 5 g of SnCl2 and 50 g of deionized water, and ion exchange was performed at 90 °C for 30 min. The mixture was then filtered and washed with deionized water until neutral. After drying at 100 °C for 1 h, it was calcined at 320 °C for 5 h to obtain the modified type A molecular sieve.

[0067] (2) Preparation of separation adsorbent

[0068] The modified type A molecular sieve and kaolin were mixed evenly at a mass ratio of 92:8 to form a mixed powder. The powder was placed in a sugar coating pan and 12wt% deionized water was sprayed in while rolling. Based on the weight of the mixed powder, it was then rolled into small balls with a particle size of 0.3-0.6mm.

[0069] (3) Purification of ethylene

[0070] The above-mentioned separation adsorbent was activated at 400℃ under a nitrogen atmosphere for 120 min, and then the inlet gas A was introduced at a temperature of 25℃ and a pressure of 0.75 MPa for 2.5 h. -1 Selective adsorption was achieved by contacting the ethylene-ethane separation adsorbent bed with the adsorbent at a mass hourly space velocity (MHSV). The contact method was a moving bed. Selective adsorption was stopped when ethylene was detectable by gas chromatography in the tail gas after passing through the ethylene-ethane separation adsorbent bed. The temperature was then raised to 80°C and the pressure reduced to 0.001 MPa to desorb ethylene (and a small amount of ethane) from the adsorbent. The ethylene / ethane volume ratio of the desorbed ethylene and ethane was determined using a 7890A gas chromatograph, and the results are shown in Table 1.

[0071] Example 2

[0072] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 1, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 30 ppm H2S). The results are shown in Table 1.

[0073] Example 3

[0074] (1) Preparation of modified type A molecular sieves

[0075] Weigh 4g of 4A molecular sieve, mix it with 5g of SnCl2 and 50g of deionized water, and perform ion exchange at 90℃ for 30min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 250℃ for 8h. Next, take the calcined sample, mix it with 2g of AgNO3 and 50g of deionized water, and perform ion exchange at 90℃ for 30min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 320℃ for 5h to obtain the modified type A molecular sieve.

[0076] (2) Preparation of separation adsorbent

[0077] The separation adsorbent was prepared according to the method in Example 1.

[0078] (3) Purification of ethylene

[0079] The above-mentioned separation adsorbent was activated at 300℃ under a nitrogen atmosphere for 150 min, and then the inlet gas A was introduced at 30℃ and 0.75 MPa for 2 h. -1 Selective adsorption was achieved by contacting the ethylene-ethane separation adsorbent bed with the adsorbent at a mass hourly space velocity (MHSV). The contact method was a moving bed. Selective adsorption was stopped when ethylene was detectable by gas chromatography in the tail gas after passing through the ethylene-ethane separation adsorbent bed. The temperature was then raised to 80°C and the pressure reduced to 0.001 MPa to desorb ethylene (and a small amount of ethane) from the adsorbent. The ethylene / ethane volume ratio of the desorbed ethylene and ethane was determined using a 7890A gas chromatograph. The results are shown in Table 1.

[0080] Example 4

[0081] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 3, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 50 ppm H2S). The results are shown in Table 1.

[0082] Example 5

[0083] (1) Preparation of modified type A molecular sieves

[0084] Weigh 4g of 4A molecular sieve, mix it with 5g of Pd(NO3)2 and 50g of deionized water, and perform ion exchange at 90℃ for 30min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 250℃ for 8h. Next, take the calcined sample, mix it with 5g of Bi(NO3)3·5H2O and 50g of deionized water, and perform ion exchange at 90℃ for 30min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 320℃ for 5h to obtain the modified type A molecular sieve.

[0085] (2) Preparation of separation adsorbent

[0086] The separation adsorbent was prepared according to the method in Example 1.

[0087] (3) Purification of ethylene

[0088] The above-mentioned separation adsorbent was activated at 450℃ under a nitrogen atmosphere for 60 min, and then the inlet gas A was subjected to a 3-hour cycle at a temperature of 10℃ and a pressure of 1 MPa. -1 Selective adsorption was achieved by contacting the ethylene-ethane separation adsorbent bed with the adsorbent at a mass hourly space velocity (MHSV). The contact method was a moving bed. Selective adsorption was stopped when ethylene was detectable by gas chromatography in the tail gas after passing through the ethylene-ethane separation adsorbent bed. The temperature was then raised to 80°C and the pressure reduced to 0.001 MPa to desorb ethylene (and a small amount of ethane) from the adsorbent. The ethylene / ethane volume ratio of the desorbed ethylene and ethane was determined using a 7890A gas chromatograph. The results are shown in Table 1.

[0089] Example 6

[0090] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 5, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 70 ppm COS). The results are shown in Table 1.

[0091] Example 7

[0092] The separation adsorbent and ethylene were prepared according to the method in Example 3, with the following difference:

[0093] (1) Preparation of modified type A molecular sieves

[0094] 4g of 4A molecular sieve was weighed and mixed with 5g of Pt(NO3)2 and 60g of deionized water. Ion exchange was performed at 60℃ for 90min. Then, the mixture was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 250℃ for 8h. The calcined sample was then mixed with 6g of (NH4)2TeO4 and 60g of deionized water. Ion exchange was performed at 90℃ for 30min. Then, the mixture was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 320℃ for 5h to obtain modified type A molecular sieve.

[0095] Example 8

[0096] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 7, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 90 ppm SO2). The results are shown in Table 1.

[0097] Example 9

[0098] The separation adsorbent and ethylene were prepared according to the method in Example 1, with the following difference:

[0099] (1) Preparation of modified type A molecular sieves

[0100] 4g of dried 5A molecular sieve was weighed and mixed with 5g of Pt(NO3)2 and 60g of deionized water. Ion exchange was performed at 60℃ for 90min. Then, the mixture was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 250℃ for 8h. Then, the mixture was mixed with 5g of NiCl2·6H2O and 60g of deionized water. Ion exchange was performed at 60℃ for 90min. Then, the mixture was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 320℃ for 5h. Then, the mixture was mixed with 5g of SnCl2 and 50g of deionized water. Ion exchange was performed at 90℃ for 30min. Then, the mixture was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 320℃ for 5h to obtain modified type A molecular sieve. The modified type A molecular sieve was mixed with 5g of Bi(NO3)3·5H2O and 50g of deionized water, and ion exchange was carried out at 90℃ for 30min. Then, it was filtered and washed with deionized water until neutral. After drying at 100℃ for 1h, it was calcined at 320℃ for 5h to obtain the modified type A molecular sieve.

[0101] Example 10

[0102] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 9, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 100 ppm COS). The results are shown in Table 1.

[0103] Example 11

[0104] The separation adsorbent and ethylene were prepared according to the method in Example 1, with the following difference:

[0105] (1) Preparation of modified type A molecular sieves

[0106] Weigh 4g of 5A molecular sieve, mix it with 0.99g of Cu(NO3)2·6H2O, 5g of SnCl2 and 60g of deionized water, and perform ion exchange at 60℃ for 90min. Then filter it and wash it with deionized water until neutral. Dry it at 100℃ for 1h and calcine it at 250℃ for 8h to obtain modified type A molecular sieve.

[0107] Example 12

[0108] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Example 11, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 120 ppm H2S). The results are shown in Table 1.

[0109] Comparative Example 1

[0110] The separation adsorbent and ethylene were prepared according to the method in Example 5, with the following difference:

[0111] (1) Preparation of modified type A molecular sieves

[0112] Weigh 4g of 5A molecular sieve, mix it with 0.99g of Cu(NO3)2·6H2O and 60g of deionized water, perform ion exchange at 60℃ for 90min, then filter and wash with deionized water until neutral, dry at 100℃ for 1h, and calcine at 250℃ for 8h to obtain modified type A molecular sieve.

[0113] Comparative Example 2

[0114] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Comparative Example 1, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 30 ppm COS). The results are shown in Table 1.

[0115] Comparative Example 3

[0116] The separation adsorbent and ethylene were prepared according to the method in Example 1, with the following difference:

[0117] (1) Preparation of modified type A molecular sieves

[0118] 4 g of 5A molecular sieve was weighed and mixed with 0.99 g of Cu(NO3)2·6H2O and 60 g of deionized water. Ion exchange was performed at 60 °C for 90 min, followed by filtration and washing with deionized water until neutral. The mixture was then dried at 100 °C for 1 h and calcined at 250 °C for 8 h. The calcined sample was then mixed with 5 g of Pb(NO3)2 and 60 g of deionized water, and ion exchange was performed at 60 °C for 90 min. The mixture was then filtered and washed with deionized water until neutral. The mixture was dried at 100 °C for 1 h and calcined at 320 °C for 5 h to obtain the modified type A molecular sieve.

[0119] Comparative Example 4

[0120] (1) Preparation of modified type A molecular sieves

[0121] Modified type A molecular sieves were prepared according to the method in Comparative Example 3.

[0122] (2) Preparation of separation adsorbent

[0123] The separation adsorbent was prepared according to the method of Comparative Example 1.

[0124] (3) Purification of ethylene

[0125] Ethylene was purified according to the method of Comparative Example 2.

[0126] Comparative Example 5

[0127] The separation adsorbent and ethylene were prepared according to the method in Example 5, with the following difference:

[0128] (1) Preparation of modified type A molecular sieves

[0129] Weigh 4g of 5A molecular sieve, mix it with 1.4g of SbCl3 and 60g of deionized water, and perform ion exchange at 60℃ for 90min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 250℃ for 8h. Next, mix the calcined molecular sieve with 0.99g of Cu(NO3)2·6H2O and 60g of deionized water, and perform ion exchange at 60℃ for 90min. Then, filter the mixture and wash it with deionized water until neutral. Dry the mixture at 100℃ for 1h, and then calcine it at 320℃ for 5h to obtain the modified type A molecular sieve.

[0130] Comparative Example 6

[0131] (1) Preparation of modified type A molecular sieves

[0132] Modified type A molecular sieves were prepared according to the method in Comparative Example 5.

[0133] (2) Preparation of separation adsorbent

[0134] The separation adsorbent was prepared according to the method of Comparative Example 1.

[0135] (3) Purification of ethylene

[0136] Ethylene was purified according to the method of Comparative Example 2.

[0137] Comparative Example 7

[0138] (1) Preparation of modified type A molecular sieves

[0139] Add 3.95 g NaOH, 1.52 g boehmite, and 7.54 g tetraethyl orthosilicate to 38.5 mL of deionized water, stir to obtain a mixed gel, transfer to an autoclave, age at 40 °C for 24 h, after aging to 60 °C for 10 h, filter the obtained hydrothermal reaction product, wash with deionized water until neutral, and dry at 100 °C to obtain 4A molecular sieve; take the obtained 4A molecular sieve and 2.49 g of... Water, CaCl2, and 40g of deionized water were mixed and subjected to ion exchange at 70℃ for 95min. The mixture was then filtered and washed with deionized water until neutral, and dried at 100℃. The dried sample was then mixed with 0.99g of Zn(NO3)2·6H2O and 60g of deionized water and subjected to ion exchange at 60℃ for 90min. The mixture was then filtered and washed with deionized water until neutral, and dried at 100℃ to obtain modified type A molecular sieve.

[0140] (2) Preparation of separation adsorbent

[0141] The modified type A molecular sieve and kaolin were mixed evenly at a mass ratio of 96:4 to form a mixed powder. The powder was placed in a sugar coating pan and 12wt% deionized water was sprayed in while rolling. Based on the weight of the mixed powder, it was then rolled into small balls with a particle size of 0.3-0.6mm.

[0142] (3) Purification of ethylene

[0143] The above-mentioned separation adsorbent was activated at 400℃ under a nitrogen atmosphere for 120 min, and then the inlet gas A was introduced at a temperature of 25℃ and a pressure of 0.75 MPa for 2.5 h. -1 Selective adsorption was achieved by contacting the ethylene-ethane separation adsorbent bed with the adsorbent at a mass hourly space velocity (MHSV). The contact method was a moving bed. Selective adsorption was stopped when ethylene was detectable by gas chromatography in the tail gas after passing through the ethylene-ethane separation adsorbent bed. The temperature was then raised to 80°C and the pressure reduced to 0.001 MPa to desorb ethylene (and a small amount of ethane) from the adsorbent. The ethylene / ethane volume ratio of the desorbed ethylene and ethane was determined using a 7890A gas chromatograph. The results are shown in Table 1.

[0144] Comparative Example 8

[0145] Modified type A molecular sieves and separation adsorbents were prepared according to the method in Comparative Example 7, except that in step (3) during the ethylene purification process, inlet gas A was replaced with inlet gas B (ethylene and ethane in a volume ratio of 1:1 and 30 ppm COS). The results are shown in Table 1.

[0146] Table 1

[0147]

[0148] The “saturated adsorption capacity of ethylene” in Table 1 refers to the saturated adsorption capacity of the adsorbents prepared in the examples and comparative examples when adsorbing ethylene.

[0149] Table 2

[0150]

[0151]

[0152] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating ethylene, characterized in that, The method includes: selectively adsorbing a mixed gas containing ethane and ethylene with a separation adsorbent under adsorption conditions, and then desorbing ethylene from the separation adsorbent under desorption conditions. The separation adsorbent comprises a modified type A molecular sieve and a binder. The modified type A molecular sieve is a type A molecular sieve doped with a loaded metal element and a modified metal element. The loaded metal element is selected from at least one element from Groups 10 and 11, and the modified metal element is selected from at least one element from Sn, Bi, and Te. Based on the total weight of the modified type A molecular sieve, the content of the type A molecular sieve is 75-98.3 wt%, the content of the loaded metal element is 0.7-15 wt%, and the content of the modified metal element is 1-10.6 wt%.

2. The method according to claim 1, characterized in that, Based on the total dry weight of the separating adsorbent, the content of the modified type A molecular sieve is 90-97 wt%, and the content of the binder is 3-10 wt%. And / or, the separating adsorbent is a spherical particle with an average particle size of 0.3-0.6 mm.

3. The method according to claim 1, characterized in that, The binder is selected from at least one of kaolin, bentonite, montmorillonite, diatomite, rettoite, and halloysite; Preferably, the type A molecular sieve is selected from at least one of 3A, 4A, and 5A molecular sieves, more preferably 4A and / or 5A molecular sieves; Preferably, the loaded metal element is selected from at least one of Cu, Pd, Ag, Pt, and Ni; Preferably, based on the total weight of the modified type A molecular sieve, the content of the type A molecular sieve is 80-97.5 wt%, the content of the supported metal element is 1-12 wt%, and the content of the modified metal element is 1.3-5 wt%.

4. The method according to claim 1, characterized in that, The adsorption conditions include: an adsorption temperature of 10-40℃, preferably 20-30℃; and an adsorption pressure of 0.5-1MPa, preferably 0.6-0.8MPa. Preferably, the desorption conditions include: a desorption temperature of 80-200℃, more preferably 80-120℃; and a desorption pressure of 0.001-0.1MPa, more preferably 0.005-0.08MPa. Preferably, the mass hourly space velocity (MSV) of the ethane and ethylene mixture is 0.3-3 h⁻¹. -1 More preferably 2-3h -1 .

5. The method according to claim 1 or 4, characterized in that, The method for separating ethylene further includes: activating the separation adsorbent in the presence of a protective gas before the separation adsorbent comes into contact with the mixed gas containing ethane and ethylene; Preferably, the activation conditions include: an activation temperature of 150-450℃, more preferably 200-400℃; and an activation time of 30-180 min, more preferably 60-150 min. Preferably, the protective gas is selected from at least one of nitrogen, argon, or helium.

6. The method according to any one of claims 1-3, characterized in that, The method for preparing the modified type A molecular sieve includes: mixing a solution containing loaded metal ions and modified metal ions with a type A molecular sieve for ion exchange, wherein the weight ratio of the loaded metal ions to the type A molecular sieve is 5-200:100, and the weight ratio of the modified metal ions to the type A molecular sieve is 50-160:100; the metal element in the loaded metal ions is selected from at least one of group 10 and 11 metal elements, and the metal element in the modified metal ions is selected from at least one of Sn, Bi, and Te.

7. The method according to claim 6, characterized in that, The mass ratio of the loaded metal ions to the type A molecular sieve is 6-135:100; Preferably, the mass ratio of the modified metal ions to the type A molecular sieve is 55-145:

100.

8. The method according to claim 6, characterized in that, The conditions for ion exchange include: an ion exchange temperature of 50-90℃ and an ion exchange time of 30-120 min; more preferably, an ion exchange temperature of 60-90℃ and an ion exchange time of 40-100 min.

9. The method according to any one of claims 1-3, characterized in that, The method for preparing the separation adsorbent includes: mixing the modified type A molecular sieve with a binder to form a mold.

10. A modified type A molecular sieve, characterized in that, The modified type A molecular sieve is the modified type A molecular sieve as defined in the method of claim 1 or 3, or the modified type A molecular sieve prepared in the method of any one of claims 6-8.

11. A method for preparing modified type A molecular sieves, characterized in that, The method described is the preparation method of modified type A molecular sieve as defined in any one of claims 6-8.

12. A separation adsorbent, characterized in that, The separating adsorbent is the separating adsorbent defined in the method of any one of claims 1-5 or the separating adsorbent prepared in the method of claim 9.

13. A method for preparing a separation adsorbent, characterized in that, The method described is the preparation method of the separation adsorbent as defined in claim 9.

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