Preparation method of metal modified A type molecular sieve

Abstract

The invention relates to a preparation method of a metal modified A-type molecular sieve. The method comprises the step of carrying out ion exchange on the A-type molecular sieve and a metal salt component at the apparent pressure of 0.2-1.0 MPa and the temperature of 50-95 DEG C. The method is simple, low in cost and high in operability. The metal-modified A-type molecular sieve obtained by the method has improved ethylene adsorption capacity and improved ethylene adsorption selectivity, so that ethylene can be better separated from mixed gas of ethylene and ethane, and the method is simple, low in cost and high in operability and has a relatively strong industrial application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing a molecular sieve, and more specifically to a method for preparing a metal-modified type A molecular sieve for the separation of ethylene and ethane. Background Technology

[0002] Ethylene is a crucial raw material in modern petrochemicals, and its production volume and technology can be used to measure the development level of the petrochemical industry. The main ethylene production processes include steam cracking, olefin production as a byproduct of oil refining, methanol-to-olefins (MTO), and ethane dehydrogenation. In these processes, due to the similar physicochemical properties of ethylene and ethane molecules, separating ethylene and ethane to obtain high-purity ethylene is very challenging. Currently, cryogenic separation is used industrially to separate ethylene and ethane, but this method requires harsh operating conditions and consumes a lot of energy. Adsorption separation, on the other hand, is characterized by low energy consumption, low cost, and simple operation, and can obtain high-purity ethylene, making it a highly efficient and low-energy-consumption method for separating ethylene and ethane. In adsorption separation, the adsorption material used is crucial for achieving good separation results between ethylene and ethane. Therefore, strategies are needed to obtain adsorption materials that improve the separation performance of ethylene and ethane. Summary of the Invention

[0003] The purpose of this application is to provide a simple, low-cost, and highly operable method for preparing metal-modified type A molecular sieves. The metal-modified type A molecular sieves obtained by this method have improved ethylene adsorption capacity and improved ethylene adsorption selectivity, thereby enabling the effective separation of ethylene from a mixture of ethylene and ethane gases.

[0004] To achieve the above objectives, this application provides a method for preparing a metal-modified type A molecular sieve, the method comprising ion exchange of a type A molecular sieve and a metal salt component at an apparent pressure of 0.2-1.0 MPa and a temperature of 50-95 °C.

[0005] The preparation method provided in this application obtains metal-modified type A molecular sieves through ion exchange under the synergistic effect of specific apparent pressure and temperature. Compared with the prior art, this method is simple, low-cost, and highly operable, and has strong prospects for industrial application. This method can obtain metal-modified type A molecular sieves with improved ethylene adsorption capacity and improved ethylene adsorption selectivity, thereby enabling better separation of ethylene from a mixture of ethylene and ethane gases.

[0006] In any embodiment of this application, the apparent pressure is obtained by hydrothermal pressurization or ventilated pressurization, preferably by ventilated pressurization.

[0007] In any embodiment of this application, the apparent pressure is 0.3-0.9 MPa, preferably 0.4-0.8 MPa, more preferably 0.5-0.7 MPa, and most preferably 0.55-0.65 MPa.

[0008] In any embodiment of this application, the apparent pressure is obtained by venting and pressurizing, and the gas used in venting and pressurizing is an inert gas.

[0009] In any embodiment of this application, the temperature is 60-90°C, preferably 80-90°C.

[0010] In any embodiment of this application, the metal salt component is a chloride, nitrate, sulfate, or acetate of a metal, and the metal is selected from Ag. + Mg 2+ Ca 2+ 、Sr 2+ Cu 2+ Zn 2+ Mn 2+ Ni 2+ Co 2+ Cd 2+ Fe 2+ Fe 3+ and Cr 3+ One or more of the above, preferably selected from Ag + Ca 2+ 、Sr 2+ Zn 2+ Mn 2+ Co 2+ and Fe 2+ One or more of the above, more preferably selected from Ag + Ca 2+ Zn 2+ Mn 2+ and Co 2+ One or more of the following. Most preferably, the metal in the metal salt component is Ca. 2+ Ag + Zn 2+ Or a combination thereof.

[0011] In any embodiment of this application, the weight ratio of the type A molecular sieve to the metal salt component is 1:0.4-0.8, preferably 1:0.40-0.65.

[0012] In a preferred embodiment of this application, the apparent pressure is 0.55-0.65 MPa and is achieved by venting and pressurizing, and the temperature is 80-90°C.

[0013] In any embodiment of this application, the method further includes filtering, washing, and drying the molecular sieve obtained after ion exchange. Attached Figure Description

[0014] Figure 1 The adsorption curves of pure gases ethylene and ethane for the metal-modified type A molecular sieve obtained according to the method of Example 3 of this application are shown.

[0015] Figure 2 The adsorption curves of pure gases ethylene and ethane for the metal-modified type A molecular sieve obtained according to the method of Example 9 of this application are shown.

[0016] Figure 3 The adsorption curves of metal-modified type A molecular sieves obtained according to the method of Comparative Example 2 (ion exchange only at an apparent pressure of 0.6 MPa) for pure gases of ethylene and ethane at 25 °C and 0-100 kPa are shown.

[0017] Figure 4 The adsorption curves of pure ethylene and ethane gases for the metal-modified type A molecular sieve obtained according to the method of Comparative Example 3 (ion exchange only at a reaction temperature of 90 °C) are shown at 25 °C and 0-100 kPa. Detailed Implementation

[0018] The following describes in detail the embodiments of the preparation method of the metal-modified type A molecular sieve of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0019] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0023] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0024] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0025] This application provides a method for preparing a metal-modified type A molecular sieve, the method comprising ion exchange of a type A molecular sieve and a metal salt component at an apparent pressure of 0.2-1.0 MPa and a temperature of 50-95 °C.

[0026] Although the mechanism is not yet clear, the inventors of this application unexpectedly discovered that molecular sieve materials possess, on the one hand, regular and uniform channels and flexibly adjustable pore sizes; on the other hand, their channels contain exchangeable cations (such as sodium ions). By exchanging the cations in the molecular sieve with other cations (i.e., cations different from those originally present in the molecular sieve), the type and quantity of cations in the molecular sieve can be changed, thereby modulating the pore size of the molecular sieve and its interaction with adsorbates (such as ethylene and ethane). This allows for the selective adsorption of specific adsorbates (such as ethylene) using the separation principles and thermodynamics of molecular sieves, ultimately achieving good separation between different adsorbates. Clearly, the type and quantity of other cations that exchange with the cations in the molecular sieve (such as sodium ions) have a significant impact on the final desired adsorption separation (such as the separation of ethylene and ethane). Therefore, it is necessary to increase the degree of ion exchange (such as reducing the sodium ion content in the molecular sieve) to obtain molecular sieves with improved adsorption separation performance. In conventional ion exchange processes, methods such as increasing the solution concentration and extending the exchange time are typically used to ensure sufficient exchange between cations in the molecular sieve and other cations. However, some metal ions used for exchange exist as hydrated metal ions. Hydrated metal ions have a large radius, making it difficult for them to enter the sodalite cages of the molecular sieve. Consequently, they cannot exchange with the cations (such as sodium ions) within them and instead deposit on the outer surface of the molecular sieve, resulting in limited cation exchange and restricting the improvement of the molecular sieve's adsorption and separation performance. Furthermore, higher solution concentrations and longer exchange times lead to reduced raw material utilization, lower ion exchange efficiency, longer production cycles, and increased energy consumption.

[0027] The inventors of this application further discovered that by conducting ion exchange between type A molecular sieves and metal salt components under the synergistic effect of specific apparent pressure and temperature, it is possible to promote the migration of more metal ions into the channels of type A molecular sieves and exchange them with the sodium ions originally present in the molecular sieve (instead of simply depositing metal ions on the outer surface of the molecular sieve). This results in more sodium ions in the sodalite cages being replaced by metal ions (i.e., the sodium ion content in the molecular sieve is reduced), thereby improving the degree of ion exchange (i.e., the sodium ion content in the molecular sieve is reduced). At the same time, the metal ions in the channels of type A molecular sieves form more ethylene adsorption active sites, thereby improving the adsorption and separation performance of the molecular sieve. Therefore, the metal-modified type A molecular sieve obtained by the method of this application has improved ethylene adsorption capacity and ethylene adsorption selectivity, and can better separate ethylene from the mixture of ethylene and ethane, achieving good separation from ethane. Furthermore, this application, by performing ion exchange under a specific combination of apparent pressure and temperature, can significantly shorten the time required to reach the desired degree of ion exchange, improve ion exchange efficiency, and greatly shorten the production cycle. At the same time, this method is simple, low-cost, and highly operable, and can effectively improve production efficiency in industrial production.

[0028] According to this application, if the apparent pressure and / or temperature during ion exchange is too low, the degree of ion exchange is low, resulting in fewer active sites for ethylene adsorption and thus the molecular sieve has a low ethylene adsorption capacity and ethylene adsorption selectivity. If the apparent pressure and / or temperature during ion exchange is too high, it will damage the crystal structure of the molecular sieve, greatly reducing the ethylene adsorption capacity and ethylene adsorption selectivity of the modified molecular sieve, and will also greatly increase production energy consumption and production costs.

[0029] In some embodiments, the ion exchange is performed at an apparent pressure of 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa, 0.8 MPa, 0.85 MPa, 0.9 MPa, 0.95 MPa, or 1.0 MPa.

[0030] In some embodiments, the ion exchange is carried out at a temperature of 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.

[0031] In some embodiments, the ion exchange is carried out at an apparent pressure of 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa, 0.8 MPa, 0.85 MPa, 0.9 MPa, 0.95 MPa, or 1.0 MPa, while simultaneously at a temperature of 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.

[0032] In some embodiments, the apparent pressure is obtained by hydrothermal pressurization or aeration pressurization, preferably by aeration pressurization. That is, the ion exchange is carried out at an apparent pressure of 0.2-1.0 MPa by hydrothermal pressurization or aeration pressurization, preferably by aeration pressurization.

[0033] In the context of this application, the gas-pressurization method refers to maintaining the ion exchange process at a certain apparent pressure by introducing gas from the outside. The hydrothermal pressurization method refers to maintaining the ion exchange process at a certain apparent pressure by introducing water vapor from the outside. In the context of this application, the apparent pressure refers to the pressure value displayed on an external pressure detection device (e.g., a pressure gauge) directly connected to the apparatus used for ion exchange. The apparent pressure can be obtained, for example, by loading the raw materials into the reaction apparatus and sealing it, then opening the inlet valve on the reaction apparatus to allow nitrogen gas to enter the reaction apparatus through the inlet, monitoring the pressure inside the reaction apparatus using a pressure gauge connected to the reaction apparatus, and stopping the gas supply when the pressure reaches the required value.

[0034] In some embodiments, the apparent pressure is 0.3-0.9 MPa, preferably 0.4-0.8 MPa, more preferably 0.5-0.7 MPa, and most preferably 0.55-0.65 MPa.

[0035] In some embodiments, when ion exchange is performed using a pressurized ventilation method, the gas used for pressurization is an inert gas, such as nitrogen or argon.

[0036] In some embodiments, the temperature is 60-90°C, preferably 80-90°C.

[0037] In some embodiments, the ion exchange time is 30-120 min, preferably 60-90 min.

[0038] In some embodiments, the metal salt component is a chloride, nitrate, sulfate, or acetate of a metal, preferably a chloride or nitrate, and the metal is selected from Ag. + Mg 2+ Ca 2+ 、Sr 2+ Cu 2+ Zn 2+ Mn 2+ Ni 2+ Co 2+ Cd 2+ Fe 2+ Fe 3+ and Cr 3+ One or more of the above, preferably selected from Ag + Ca 2+ 、Sr 2+ Zn 2+ Mn 2+ Co 2+ and Fe 2+ One or more of the above, more preferably selected from Ag + Ca 2+ Zn 2+ Mn 2+ and Co 2+ One or more of them.

[0039] In some embodiments, the metal in the metal salt component is Ca. 2+ Ag + Zn 2+ Or a combination thereof. In some preferred embodiments, the metal in the metal salt component is Ca. 2+ and Ag + Combinations or Ca 2+ and Zn 2+ The combination of .

[0040] In some embodiments, the weight ratio of the type A molecular sieve to the metal salt component is 1:0.4-0.8, preferably 1:0.40-0.65.

[0041] In some embodiments, the concentration of the metal salt component is 0.04-0.08 g / ml, preferably 0.040-0.065 g / ml.

[0042] In some embodiments, the apparent pressure is 0.55-0.65 MPa and is achieved by pressurization via air purging, and the temperature is 80-90°C. This improves the degree of ion exchange, forming more ethylene adsorption active sites in the type A molecular sieve, thereby increasing the ethylene adsorption capacity and selectivity of the modified molecular sieve, ultimately enabling the extraction of more ethylene gas from the ethylene and ethane mixture.

[0043] In some embodiments, type A molecular sieves are combined with Ca as a metal salt component. 2+ Salts and containing Ag + The salt undergoes ion exchange at an apparent pressure of 0.55-0.65 MPa via a pressurized aeration method and a temperature of 80-90°C. In some preferred embodiments, the weight of the type A molecular sieve is related to the Ca content as a metal salt component. 2+ Salts and containing Ag + The weight ratio of salt is 1:0.40-0.46, preferably 1:0.42-0.45.

[0044] In some embodiments, type A molecular sieves are combined with Ca as a metal salt component. 2+ Salts and containing Zn 2+ The salt undergoes ion exchange at an apparent pressure of 0.55-0.65 MPa via a pressurized aeration method and a temperature of 80-90°C. In some preferred embodiments, the weight of the type A molecular sieve is related to the Ca content as a metal salt component. 2+ Salts and containing Zn 2+ The weight ratio of salt is 1:0.60-0.65, preferably 1:0.62-0.64.

[0045] In some embodiments, the method further includes filtering, washing, and drying the molecular sieve obtained after ion exchange. The filtration, washing, and drying are performed using apparatus and solution systems commonly used in the art for filtering, washing, and drying molecular sieves.

[0046] In this application, unless otherwise specified, all ion exchanges are carried out in an aqueous system.

[0047] In this application, the adsorption curves of pure ethylene and pure ethane on metal-modified type A molecular sieves were measured using a Hiden Isochema Intelligent Gravimetric Adsorption (IGA) instrument at a test temperature of 30°C and a test pressure of 0-100 kPa. The ethylene adsorption capacity was obtained, and then, based on the adsorption curves of ethylene and ethane, the ethylene adsorption selectivity in a 1:1 volume ratio mixture of ethylene and ethane was determined using the IAST-DSLF method. This evaluation method is also described, for example, in *Adsorption Separation Technology and Engineering*, Chen Jian et al., Science Press, July 2022, First Edition, Chapter 1, "Fundamentals of Gas Adsorption Separation," pp. 7-8 and 31-33.

[0048] In one preferred embodiment, the metal-modified type A molecular sieve exhibits an ethylene adsorption capacity of up to 3.29 mmol / g and an ethylene adsorption selectivity of up to 15.68 in a 1:1 volume ratio of ethylene to ethane mixture. In another preferred embodiment, the metal-modified type A molecular sieve exhibits an ethylene adsorption capacity of up to 3.56 mmol / g and an ethylene adsorption selectivity of up to 35.64 in a 1:1 volume ratio of ethylene to ethane mixture.

[0049] In this application, the definitions within the broadest scope and the preferred definitions can be combined to form new technical solutions, which are also considered to be disclosed in this specification.

[0050] The present application is illustrated by way of examples below, but should not be construed as limiting the scope of the present application.

[0051] Example

[0052] I. Raw materials and reaction apparatus

[0053] Type A molecular sieves were purchased from the catalyst factory of Nankai University.

[0054] All reagents used for ion exchange modification were chemically pure and purchased from Alfa Aesar, USA.

[0055] Ethylene (purity >99.99%) and ethane (99.95%) were purchased from Beijing Huanyu Jinghui Jingcheng Gas Technology Co., Ltd.

[0056] The reaction apparatus was purchased from Shanghai Laibei Scientific Instruments Co., Ltd.

[0057] II. Testing of Ethylene Adsorption Capacity and Ethylene Adsorption Selectivity

[0058] First, a metal-modified type A molecular sieve was loaded into a Hiden Isochema Intelligent Gravimetric Adsorption (IGA) system, and pure ethylene gas was introduced. The adsorption curve of ethylene on the metal-modified type A molecular sieve was measured under the conditions of 30°C and 0-100 kPa, and the ethylene adsorption capacity was obtained. Then, the metal-modified type A molecular sieve was reloaded into the IGA system, and pure ethane gas was introduced. The adsorption curve of ethane on the metal-modified type A molecular sieve was measured under the conditions of 30°C and 0-100 kPa. Finally, based on the adsorption curves of ethylene and ethane, the ethylene adsorption selectivity in a 1:1 volume ratio mixture of ethylene and ethane was obtained using the IAST-DSLF method.

[0059] Example 1

[0060] 4g of 4A molecular sieve, 0.8g of anhydrous CaCl2, and 1.751g of Zn(NO3)2·6H2O as metal salt components were mixed evenly with 40g of deionized water, loaded into a reaction apparatus, and sealed. Then, the inlet valve on the reaction apparatus was opened to allow nitrogen gas to enter the reaction apparatus through the inlet. When the pressure inside the reaction apparatus reached 0.3MPa, the gas supply was stopped. The reaction apparatus was then heated to 95℃, and ion exchange was carried out for 60min at an apparent pressure of 0.3MPa and a reaction temperature of 95℃. The obtained product was then filtered, washed with deionized water until neutral, and dried at a constant temperature of 70℃ to obtain metal-modified type A molecular sieve.

[0061] Example 2

[0062] The method for preparing metal-modified type A molecular sieves is the same as in Example 1, except that ion exchange is carried out at an apparent pressure of 0.5 MPa and a reaction temperature of 80 °C.

[0063] Example 3

[0064] The method for preparing metal-modified type A molecular sieves is the same as in Example 1, except that ion exchange is carried out at an apparent pressure of 0.6 MPa and a reaction temperature of 90 °C.

[0065] Example 4

[0066] The method for preparing metal-modified type A molecular sieves is the same as in Example 1, except that ion exchange is carried out at an apparent pressure of 0.7 MPa and a reaction temperature of 70 °C.

[0067] Example 5

[0068] The method for preparing metal-modified type A molecular sieves is the same as in Example 1, except that ion exchange is carried out at an apparent pressure of 0.9 MPa and a reaction temperature of 60 °C.

[0069] Example 6

[0070] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 0.8g of anhydrous CaCl2 and 1g of AgNO3 are added as metal salt components.

[0071] Example 7

[0072] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 0.8 g of anhydrous CaCl2 and 1.165 g of MnCl2·4H2O are added as metal salt components.

[0073] Example 8

[0074] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 0.8 g of anhydrous CaCl2 and 1.713 g of Co(NO3)2·6H2O are added as metal salt components.

[0075] Example 9

[0076] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 1.143 g of anhydrous SrCl2 and 1.17 g of FeCl2·4H2O are added as metal salt components.

[0077] Example 10

[0078] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 0.8 g of anhydrous CaCl2 and 2.356 g of Cr(NO3)3·9H2O are added as metal salt components.

[0079] Example 11

[0080] The method for preparing metal-modified type A molecular sieves is the same as in Example 3, except that 2g of anhydrous CaCl2 is added as a metal salt component.

[0081] Comparative Example 1

[0082] The method for preparing metal-modified type A molecular sieves is the same as in Example 9, except that ion exchange is carried out only at room temperature (25°C).

[0083] Comparative Example 2

[0084] The method for preparing metal-modified type A molecular sieves is the same as in Example 9, except that ion exchange is performed only at an apparent pressure of 0.6 MPa (room temperature, 25 °C).

[0085] Comparative Example 3

[0086] The method for preparing metal-modified type A molecular sieves is the same as in Example 9, except that ion exchange is carried out only at a reaction temperature of 90°C (without external pressure).

[0087] The metal-modified type A molecular sieves obtained by the methods of Examples 1-11 and Comparative Examples 1-3 were tested according to the above "II. Test of ethylene adsorption capacity and ethylene adsorption selectivity", and the specific results are shown in Table 1 below.

[0088] Table 1. Ethylene adsorption capacity and ethylene adsorption selectivity of metal-modified type A molecular sieves obtained by the methods of Examples 1-11 and Comparative Examples 1-3.

[0089]

[0090] Figure 1 The adsorption curves of metal-modified type A molecular sieves obtained by the method in Example 3 for pure ethylene and ethane gases at 25°C and 0-100 kPa are shown. Figure 2 The adsorption curves of the metal-modified type A molecular sieve obtained by the method in Example 9 for pure ethylene and ethane gases at 25°C and 0-100 kPa are shown. Figure 3 The adsorption curves of metal-modified type A molecular sieves obtained by the method of Comparative Example 2 for pure ethylene and ethane gases at 25℃ and 0-100kPa are shown. Figure 4 The adsorption curves of metal-modified type A molecular sieves obtained by the method of Comparative Example 3 for pure ethylene and ethane gases at 25℃ and 0-100kPa are shown.

[0091] By comparison Figures 1 to 4As can be seen from the data in Table 1, the method of this application, through ion exchange between the type A molecular sieve and the metal salt component under specific apparent pressure and temperature, promotes the migration of more metal ions into the pores of the type A molecular sieve, where they exchange with sodium ions in the sodalite cage. The high degree of ion exchange results in the formation of more ethylene adsorption active sites within the molecular sieve, thus significantly improving the adsorption and separation performance of the molecular sieve obtained by this method—exhibiting improved ethylene adsorption capacity and ethylene adsorption selectivity. For example, regarding ethylene adsorption selectivity, compared to molecular sieves obtained by ion exchange only at room temperature (Comparative Example 1, with an ethylene adsorption selectivity of 5.86), or only under a certain apparent pressure (Comparative Example 2), or only under a certain temperature (Comparative Example 3, with an ethylene adsorption selectivity of 8.12), while all other aspects are the same as the method of this application, the metal-modified type A molecular sieve obtained by the method of this application (Example 9, with an ethylene adsorption selectivity of 11.95)—under specific apparent pressure and temperature—shows improved ethylene adsorption selectivity by 104%, 78%, and 47%, respectively.

[0092] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a metal-modified type A molecular sieve, characterized in that, The method includes: ion exchange of type A molecular sieve and metal salt components at an apparent pressure of 0.2-1.0 MPa and a temperature of 50-95 °C.

2. The method according to claim 1, characterized in that, The apparent pressure is obtained by hydrothermal pressurization or ventilated pressurization, preferably by ventilated pressurization.

3. The method according to claim 1, characterized in that, The apparent pressure is 0.3-0.9 MPa, preferably 0.4-0.8 MPa, more preferably 0.5-0.7 MPa, and most preferably 0.55-0.65 MPa.

4. The method according to claim 1, characterized in that, The apparent pressure is obtained by venting and pressurizing, and the gas used in venting and pressurizing is an inert gas.

5. The method according to any one of claims 1 to 4, characterized in that, The temperature is 60-90℃, preferably 80-90℃.

6. The method according to any one of claims 1 to 4, characterized in that, The metal salt component is a chloride, nitrate, sulfate, or acetate of a metal, and the metal is selected from Ag. + Mg 2+ Ca 2+ 、Sr 2+ Cu 2+ Zn 2+ Mn 2+ Ni 2+ Co 2+ Cd 2 + Fe 2+ Fe 3+ and Cr 3+ One or more of the above, preferably selected from Ag + Ca 2+ 、Sr 2+ Zn 2+ Mn 2+ Co 2+ and Fe 2+ One or more of the above, more preferably selected from Ag + Ca 2+ Zn 2+ Mn 2+ and Co 2+ One or more of them.

7. The method according to claim 6, characterized in that, The metal in the metal salt component is Ca. 2+ Ag + Zn 2+ Or a combination thereof.

8. The method according to any one of claims 1 to 4, characterized in that, The weight ratio of type A molecular sieve to metal salt component is 1:0.40-0.80, preferably 1:0.40-0.

65.

9. The method according to claim 1, characterized in that, The apparent pressure is 0.55-0.65 MPa and is achieved by pressurizing through ventilation, and the temperature is 80-90℃.

10. The method according to any one of claims 1 to 4, characterized in that, It also includes filtration, washing, and drying of the molecular sieves obtained after ion exchange.

11. A metal-modified type A molecular sieve obtained by the preparation method of any one of claims 1 to 10.

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