Aluminum- and magnesium-loaded acidic molecular sieves, methods for their preparation and use

Abstract

The application discloses an acidic molecular sieve loaded with aluminum and magnesium, a preparation method and application thereof. The provided acidic molecular sieve loaded with aluminum and magnesium comprises an acidic molecular sieve and aluminum oxide and magnesium oxide loaded in the channel and / or surface of the acidic molecular sieve, wherein the mass ratio of aluminum in the aluminum oxide to the acidic molecular sieve is 1:(10-20), and the mass ratio of magnesium in the magnesium oxide to the acidic molecular sieve is 1:(40-60). The provided acidic molecular sieve loaded with aluminum and magnesium is modified by the bimetallic aluminum oxide and magnesium oxide. The co-modification of aluminum and magnesium can produce a synergistic effect, provide a more optimized acid-base site combination, improve the CO2 desorption rate in an amine solution, improve the stability of a catalyst, prolong the service life of the catalyst, reduce the regeneration energy consumption of the CO2-rich amine solution, and can be applied to a complex amine regeneration / CO2 desorption process.

Description

Technical Field

[0001] This application belongs to the field of catalyst processing technology, and relates to acidic molecular sieves supported on aluminum and magnesium, their preparation methods and applications. Background Technology

[0002] The amine solution absorption method, represented by monoethanolamine (MEA) and multi-component complex amine systems, is currently the most mature CO2 capture technology for industrial application. This capture process involves two reversible reactions: absorption and desorption. First, fresh amine solution selectively absorbs CO2 from the flue gas in the absorption tower, transforming the fresh amine solution into a rich amine solution. Subsequently, the rich amine solution enters the desorption tower, where it undergoes thermal desorption by heating, converting the rich amine solution into a lean amine solution, which then enters the absorption tower again for the next CO2 absorption cycle. However, traditional desorption processes rely on a high-temperature environment of 110-120℃, resulting in system energy consumption accounting for 60%-70% of the total capture cost, severely restricting the techno-economic viability and large-scale promotion.

[0003] Introducing solid acid catalysts into organic amine absorption systems is one feasible method to reduce regeneration energy consumption. Among them, zeolite molecular sieves, as a type of solid acid catalyst, exhibit good catalytic activity in catalyzing CO2 desorption and promoting proton transfer, which can significantly improve the CO2 desorption rate, reduce regeneration time, and lower CO2 desorption temperature, thereby reducing the regeneration heat load of CO2 desorption. However, existing molecular sieve catalysts have a short service life and a low CO2 desorption rate. Summary of the Invention

[0004] Therefore, it is necessary to provide an acidic molecular sieve loaded with aluminum and magnesium with a long service life and a high CO2 desorption rate, as well as its preparation method and application.

[0005] In some embodiments, an acidic molecular sieve loaded with aluminum and magnesium is provided, comprising an acidic molecular sieve and aluminum oxide and magnesium oxide loaded in and / or on the surface of the acidic molecular sieve pores, wherein the mass ratio of aluminum in the aluminum oxide to the acidic molecular sieve is 1:(10~20), and the mass ratio of magnesium in the magnesium oxide to the acidic molecular sieve is 1:(40~60).

[0006] In some embodiments, the acidic molecular sieve supported on aluminum and magnesium satisfies one or more of the following conditions:

[0007] (1) Specific surface area is 320 m² 2 / g~380m 2 / g;

[0008] (2) The pore size is 0.5 nm to 0.55 nm;

[0009] (3) The pore volume is 0.16 cm 3 / g~0.20cm3 / g;

[0010] (4) The acidic molecular sieve comprises one or more of HZSM-5, MCM-41 and SBA-15;

[0011] (5) The acidic molecular sieve contains silicon and aluminum, and the molar ratio of silicon to aluminum in the acidic molecular sieve is (50-100):1.

[0012] In some embodiments, a method for preparing the aforementioned aluminum and magnesium-loaded acidic molecular sieve is provided, comprising the following steps:

[0013] The acidic molecular sieve is pretreated under an oxygen-containing atmosphere and high temperature, and then cooled in a first inert atmosphere to prepare the pretreated acidic molecular sieve.

[0014] The pretreated acidic molecular sieve is immersed in an aqueous solution containing soluble aluminum and magnesium salts, ultrasonically dispersed, aged, dried, and calcined under a second inert atmosphere to prepare the aluminum and magnesium-loaded acidic molecular sieve.

[0015] In some embodiments, the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium includes pretreatment conditions that satisfy one or both of the following conditions:

[0016] (1) Keep warm at 500℃~600℃ for 5h~7h;

[0017] (2) The heating rate for pretreatment is 3℃ / min to 5℃ / min.

[0018] In some embodiments, the provided method for preparing the aluminum and magnesium-loaded acidic molecular sieve satisfies one or more of the following conditions:

[0019] (1) The oxygen-containing atmosphere includes one or both of air and oxygen;

[0020] (2) The flow rate of the oxygen-containing atmosphere is 40 mL / min to 60 mL / min;

[0021] (3) The first inert atmosphere and the second inert atmosphere each independently include one or more of nitrogen and argon;

[0022] (4) The flow rates of the first inert atmosphere and the second inert atmosphere are each 50 mL / min to 80 mL / min independently.

[0023] In some embodiments, the method for preparing the provided aluminum and magnesium-loaded acidic molecular sieve includes drying by one or both of forced-air drying and spray drying.

[0024] Optionally, the drying process includes: drying at 50℃~60℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h; drying at 80℃~90℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h; and drying at 100℃~110℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h.

[0025] Optionally, the spray drying conditions include an inlet temperature of 150°C to 250°C and an outlet temperature of 80°C to 110°C.

[0026] In some embodiments, the provided method for preparing the aluminum and magnesium-loaded acidic molecular sieve satisfies one or more of the following conditions:

[0027] (1) The conditions for ultrasonic dispersion include: temperature of 40℃~50℃, power of 300W~400W, and time of 30min~60min;

[0028] (2) The aging conditions include: temperature of 5℃~30℃ and time of 10h~20h;

[0029] (3) The calcination conditions include: holding at 500℃~600℃ for 4h~5h;

[0030] (4) The heating rate for calcination is 1℃ / min to 2℃ / min.

[0031] In some embodiments, the provided method for preparing the aluminum and magnesium-loaded acidic molecular sieve satisfies one or more of the following conditions:

[0032] (1) The mass ratio of aluminum in the soluble aluminum salt to the acidic molecular sieve is 1:(10~20); the mass ratio of magnesium in the magnesium salt to the acidic molecular sieve is 1:(40~60).

[0033] (2) The soluble aluminum salt includes one or more of aluminum nitrate and aluminum chloride;

[0034] (3) The magnesium salt includes one or more of magnesium nitrate and magnesium acetate.

[0035] In some embodiments, the application of the aluminum- and magnesium-loaded acidic molecular sieves described above, or the aluminum- and magnesium-loaded acidic molecular sieves prepared by the described preparation method, in the catalytic desorption of carbon dioxide is provided.

[0036] In some embodiments, the acidic molecular sieve loaded with aluminum and magnesium is contacted with a CO2-rich amine solution to desorb CO2.

[0037] The provided acidic molecular sieve, supported on aluminum and magnesium, is modified by alumina and magnesium oxide bimetallic modification. The introduction of alumina increases the aluminum content on the support surface, significantly enhancing the acid density of the molecular sieve and increasing the number and strength of Brønsted acid sites. Brønsted acids are proton-donating acids, and the increase in the number and strength of these sites positively promotes acid-catalyzed reactions. The introduction of magnesium oxide improves stability and enhances the hydrothermal stability of the catalyst. Aluminum and... magnesium Co-modification may produce synergistic effects, providing a more optimized combination of acid-base sites, increasing the CO2 desorption rate in amine solutions, improving catalyst stability, extending catalyst lifespan, reducing energy consumption for regeneration of CO2-rich amine solutions, and making it suitable for complex amine regeneration / CO2 desorption processes. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments and examples of this application, and to more completely understand this application and its beneficial effects, the accompanying drawings used in the description of the embodiments or examples will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. Those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0039] Figure 1 This is a schematic diagram of a CO2 desorption evaluation device, in which 1-oil bath, 2-electric meter, 3-carbon dioxide gas mass flow meter, 4-thermometer, 5-sampling port, and 6-dryer. Detailed Implementation

[0040] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0041] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0044] The terms "and / or," "or / and," and "and / or" as used in this application encompass any one of two or more related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and "a combination of A and B."

[0045] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0046] The terms “combinations thereof,” “any combination thereof,” and “any combination thereof” as used in this application include all suitable combinations of any two or more of the listed items.

[0047] In this application, the term "suitable" as used in "suitable combination", "suitable method", "any suitable method", etc., refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0048] In this application, terms such as "preferred," "better," "more suitable," and "ideal" are merely used to describe implementation methods or embodiments that achieve better results, and should be understood not to limit the scope of protection of this application.

[0049] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0050] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0051] In this invention, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0052] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0053] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0054] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0055] In this application, % (w / w) and wt% both represent weight percentage, % (v / v) refers to volume percentage, and % (w / v) refers to mass-volume percentage.

[0056] In this application, "room temperature" generally refers to 5℃~30℃, and more preferably 25±5℃.

[0057] Current catalysts are prone to dealuminization of the molecular sieve framework under high temperature, especially in water vapor environments, which leads to the destruction of the pore structure and a decrease in specific surface area. During high-temperature reactions or regeneration, the supported active metal atoms or small particles detach from the support surface, resulting in permanent loss of active components.

[0058] In some embodiments, an acidic molecular sieve loaded with aluminum and magnesium is provided, comprising an acidic molecular sieve and aluminum oxide and magnesium oxide loaded in and / or on the surface of the acidic molecular sieve pores, wherein the mass ratio of aluminum in the aluminum oxide to the acidic molecular sieve is 1:(10~20), and the mass ratio of magnesium in the magnesium oxide to the acidic molecular sieve is 1:(40~60).

[0059] Understandably, the mass ratio of magnesium in magnesium oxide to the acidic molecular sieve can be 1:40, 1:45, 1:50, 1:55, 1:60, etc., or it can be any range of two of the aforementioned ratios.

[0060] In some embodiments, the specific surface area of ​​the aluminum and magnesium-loaded acidic molecular sieve is 320 m². 2 / g~380m 2 / g, for example, the specific surface area of ​​acidic molecular sieves supported on aluminum and magnesium can be 320 m². 2 / g、330m 2 / g、340m 2 / g, 350m 2 / g、360m 2 / g、370m 2 / g、380m 2 / g, etc., can also be a range consisting of any two of the aforementioned values.

[0061] In some embodiments, the pore size of the acidic molecular sieve loaded with aluminum and magnesium is 0.5 nm to 0.55 nm. For example, the pore size of the acidic molecular sieve loaded with aluminum and magnesium can be 0.5 nm, 0.51 nm, 0.52 nm, 0.53 nm, 0.54 nm, 0.55 nm, etc., or it can be a range composed of any two of the aforementioned values.

[0062] In some embodiments, the pore volume of the aluminum and magnesium-loaded acidic molecular sieve is 0.16 cm³. 3 / g~0.20cm 3 / g, for example, the pore volume of acidic molecular sieves supported on aluminum and magnesium can be 0.16 cm³. 3 / g, 0.17cm 3 / g, 0.18cm 3 / g, 0.19cm 3 / g, 0.20cm 3 / g, etc., can also be a range consisting of any two of the aforementioned values.

[0063] In some embodiments, the acidic molecular sieve loaded with aluminum and magnesium comprises one or more of HZSM-5, MCM-41, and SBA-15.

[0064] In some embodiments, the acidic molecular sieve loaded with aluminum and magnesium contains silicon and aluminum elements, and the molar ratio of silicon to aluminum in the acidic molecular sieve is (50~100):1. For example, the molar ratio of silicon to aluminum in the acidic molecular sieve can be 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc., or it can be a range of any two of the aforementioned ratios.

[0065] In some embodiments, a method for preparing the aforementioned aluminum and magnesium-loaded acidic molecular sieve is provided, comprising the following steps:

[0066] The acidic molecular sieve is pretreated under an oxygen-containing atmosphere and high temperature, and then cooled in a first inert atmosphere to prepare the pretreated acidic molecular sieve.

[0067] The pretreated acidic molecular sieve is immersed in an aqueous solution containing soluble aluminum and magnesium salts, ultrasonically dispersed, aged, dried, and calcined under a second inert atmosphere to prepare the aluminum and magnesium-loaded acidic molecular sieve.

[0068] In some embodiments, the pretreatment conditions in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium include: holding at 500℃~600℃ for 5h~7h, for example, the pretreatment temperature can be 500℃, 550℃, 600℃, etc., or it can be a range of any two of the aforementioned values; the holding time can be 5h, 6h, 7h, etc., or it can be a range of any two of the aforementioned ratios.

[0069] In some embodiments, the pretreatment conditions in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium include a heating rate of 3°C / min to 5°C / min.

[0070] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the oxygen-containing atmosphere includes one or both of air and oxygen.

[0071] In some embodiments, in the method for preparing the acidic molecular sieve loaded with aluminum and magnesium, the flow rate of the oxygen-containing atmosphere is 40 mL / min to 60 mL / min.

[0072] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the first inert atmosphere and the second inert atmosphere each independently include one or more of nitrogen and argon.

[0073] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the flow rates of the first inert atmosphere and the second inert atmosphere are each independently 50 mL / min to 80 mL / min.

[0074] In some embodiments, the drying method provided for preparing the aluminum and magnesium-loaded acidic molecular sieve includes one or both of blower drying and spray drying.

[0075] In some embodiments, the drying process includes: drying at 50°C to 60°C at an air flow rate of 50 mL / min to 60 mL / min for 4 to 5 hours; drying at 80°C to 90°C at an air flow rate of 50 mL / min to 60 mL / min for 4 to 5 hours; and drying at 100°C to 110°C at an air flow rate of 50 mL / min to 60 mL / min for 4 to 5 hours.

[0076] In some embodiments, the spray drying conditions include an inlet temperature of 150°C to 250°C and an outlet temperature of 80°C to 110°C.

[0077] In some embodiments, the ultrasonic dispersion conditions in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium include: a temperature of 40°C to 50°C, a power of 300W to 400W, and a time of 30min to 60min.

[0078] In some embodiments, the aging conditions in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium include: a temperature of 5°C to 30°C and a time of 10h to 20h.

[0079] In some embodiments, the calcination conditions in the provided method for preparing the aluminum and magnesium-loaded acidic molecular sieve include: holding at 500℃~600℃ for 4h~5h, for example, the calcination temperature can be 500℃, 550℃, 600℃, etc., or any combination of the aforementioned two values; the holding time can be 4h, 4.5h, 5h, etc., or any combination of the aforementioned two values.

[0080] In some embodiments, the calcination heating rate in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium is 1°C / min to 2°C / min.

[0081] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the mass ratio of aluminum in the soluble aluminum salt to the acidic molecular sieve is 1:(10~20); the mass ratio of magnesium in the magnesium salt to the acidic molecular sieve is 1:(40~60). For example, the mass ratio of magnesium in the magnesium salt to the acidic molecular sieve can be 1:40, 1:45, 1:50, 1:55, 1:60, etc., or it can be a range consisting of any two of the aforementioned ratios.

[0082] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the soluble aluminum salt includes one or more of aluminum nitrate and aluminum chloride;

[0083] In some embodiments, in the provided method for preparing acidic molecular sieves loaded with aluminum and magnesium, the magnesium salt includes one or more of magnesium nitrate and magnesium acetate.

[0084] In some embodiments, the application of the aluminum- and magnesium-loaded acidic molecular sieves described above, or the aluminum- and magnesium-loaded acidic molecular sieves prepared by the described preparation method, in the catalytic desorption of carbon dioxide is provided.

[0085] In some embodiments, the acidic molecular sieve loaded with aluminum and magnesium is contacted with a CO2-rich amine solution to desorb CO2.

[0086] Enhanced support pretreatment thoroughly removes template agents and adsorbed water, exposing a clean, intact pore structure and surface hydroxyl groups. This provides uniform active sites for subsequent metal loading, significantly improving metal dispersion and catalyst stability. Inert atmosphere cooling prevents reabsorption of water.

[0087] By employing the impregnation method, the active component precursor is introduced into the molecular sieve pores or uniformly dispersed on the surface to the greatest extent possible, which greatly reduces the risk of large particles clogging the pores caused by the precipitation method.

[0088] During the calcination process, the temperature is increased at a rate of 1℃ / min to 2℃ / min, within the range of 250-400℃ where nitrates undergo vigorous decomposition.

[0089] It achieves efficient and rapid desorption at relatively low temperatures, thereby significantly reducing the energy consumption of the carbon capture system regeneration process.

[0090] The provided preparation method combines ultrasonic dispersion, step drying, and programmed temperature-controlled calcination. The optimized preparation process ensures high dispersibility and stability of the active components and extends the catalyst lifetime.

[0091] The following are specific embodiments. They are intended to provide further detailed explanation of this application to help those skilled in the art and researchers to better understand it. The technical conditions and other details do not constitute any limitation on this application. Any modifications made within the scope of the claims of this application are protected by the claims of this application.

[0092] Unless otherwise stated, all raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0093] The reagents used in the examples were sourced as follows: HZSM-5 was purchased from Zeolyst International (USA), and MCM-41 and SBA-15 were purchased from Aladdin (China).

[0094] Example 1

[0095] This embodiment provides an acidic molecular sieve supported on aluminum and magnesium, prepared by the following method:

[0096] (1) Carrier pretreatment

[0097] For example, acidic molecular sieve HZSM-5 powder with a Si / Al molar ratio of 50 is placed in a tube furnace, and dry air is introduced at a flow rate of 50 mL / min. The temperature is increased to 550 °C at a rate of 3 °C / min and held at 550 °C for 6 hours. After the holding period, high-purity N2 is switched on (flow rate of 50 mL / min), and the mixture is allowed to cool naturally to room temperature (<50 °C). It is then immediately transferred to a desiccator and sealed for storage for later use.

[0098] (2) Solution preparation

[0099] Dissolve the soluble aluminum salt Al(NO3)3 in deionized water to prepare a 0.5 mol / L solution, then add 0.1 mol / L Mg(NO3)2 to dissolve it together with the aluminum salt.

[0100] (3) Carrier impregnation and ultrasound

[0101] Impregnation process: Using the equal volume impregnation method, acidic molecular sieve powder is added to the solution obtained in step (2) so that the mass ratio of Mg to acidic molecular sieve in magnesium salt is 1:50 and the mass ratio of Al to acidic molecular sieve in aluminum salt is 1:15. Stir for 30 min.

[0102] Then, sonicate at 40℃ (300W) for 30-60 minutes to form a homogeneous suspension. After sonication, allow to stand at room temperature (25℃) for 12 hours to age.

[0103] (4) Drying

[0104] The sample was dried using a stepwise temperature increase drying oven as follows: at 60℃, with a drying air flow of 50 mL / min, for 4 hours; at 80℃, with a drying air flow of 50 mL / min, for 4 hours; at 100℃, with a drying air flow of 50 mL / min, for 4 hours. The dried sample should be a loose powder without any hard lumps.

[0105] (5) Calcination

[0106] The dried powder was placed in a tube furnace, and high-purity N2 was introduced at a flow rate of 80 mL / min (ensuring positive pressure inside the furnace tube to prevent air from entering). The temperature was increased to 500°C at a rate of 2°C / min. After reaching 500°C, the temperature was maintained for 4 hours.

[0107] After the heat treatment is complete, keep N2 circulating and allow the furnace to cool naturally to below 100°C. Turn off the N2 and immediately transfer the sample to a desiccator to cool to room temperature. Seal and store the sample in a desiccator or a sample vial filled with inert gas.

[0108] Example 2

[0109] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium. The preparation method is similar to that in Example 1, except that in step (3), the mass ratio of Mg in the magnesium salt to the acidic molecular sieve is 1:50, and the mass ratio of Al in the aluminum salt to the acidic molecular sieve is 1:10.

[0110] Example 3

[0111] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium. The preparation method is similar to that in Example 1, except that in step (3), the mass ratio of Mg in the magnesium salt to the acidic molecular sieve is 1:50, and the mass ratio of Al in the aluminum salt to the acidic molecular sieve is 1:20.

[0112] Example 4

[0113] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium. The preparation method is similar to that in Example 1, except that in step (3), the mass ratio of Mg in the magnesium salt to the acidic molecular sieve is 1:40, and the mass ratio of Al in the aluminum salt to the acidic molecular sieve is 1:10.

[0114] Example 5

[0115] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium. The preparation method is similar to that in Example 1, except that in step (3), the mass ratio of Mg in the magnesium salt to the acidic molecular sieve is 1:60, and the mass ratio of Al in the aluminum salt to the acidic molecular sieve is 1:10.

[0116] Example 6

[0117] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium, prepared by a method similar to that in Example 1, except that the acidic molecular sieve is MCM-41 with a Si / Al molar ratio of 50.

[0118] Example 7

[0119] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium, prepared by a method similar to that in Example 1, except that the acidic molecular sieve is SBA-15 with a Si / Al molar ratio of 50.

[0120] Example 8

[0121] This embodiment provides an acidic molecular sieve loaded with aluminum and magnesium. The preparation method is similar to that in Example 1, except that in step (4), the impregnated slurry is directly pumped into a spray drying tower and dried into microspheres instantly with hot air at an inlet temperature of 250°C and an outlet temperature of 110°C.

[0122] Comparative Example 1

[0123] This comparative example provides a bifunctional catalyst of magnesium-aluminum composite oxide / HZSM-5, which is composed of magnesium-aluminum composite oxide and HZSM-5 molecular sieve. The mass ratio of magnesium-aluminum composite oxide to HZSM-5 molecular sieve is 1:1, and the molar ratio of magnesium to aluminum in magnesium-aluminum composite oxide is 1:1.

[0124] A method for preparing a magnesium-aluminum composite oxide / HZSM-5 bifunctional catalyst includes the following steps:

[0125] (1) Preparation of magnesium-aluminum composite oxides:

[0126] (11) Co-precipitation: Dissolve 4.45g magnesium nitrate and 6.39g aluminum nitrate in water and make up to 200mL in a volumetric flask to prepare an active component solution with a total magnesium and aluminum concentration of 0.3mol / L. Take 200mL of 29% ammonia solution as the precipitant. Under stirring conditions at 50℃, add 200mL of active component solution and precipitant dropwise to 200mL of deionized water. During the dropwise addition, control the pH of the system to 8.5-9.5. After the dropwise addition is completed, keep the temperature and continue aging for 8h.

[0127] (12) Preparation of magnesium-aluminum composite oxide: centrifuge, wash the solid obtained by centrifugation until neutral, dry at 100℃ for 10h, calcine at 400℃ for 10h in muffle furnace at a heating rate of 2℃ / min, grind to obtain magnesium-aluminum composite oxide for later use.

[0128] (2) Preparation of HZSM-5 molecular sieve:

[0129] (21) Alkali treatment: Take 30g of silica-alumina ratio of 38 and specific surface area of ​​350m².2 / g of ZSM-5 molecular sieve was added to 150mL of 0.1mol / L NaOH solution and alkali-treated at 60℃ for 5h. During the alkali treatment, the mixture was stirred and refluxed. After filtration and washing until neutral, the mixture was dried at 100℃ for 12h.

[0130] (22) Ammonium exchange: 25g of alkali-treated ZSM-5 molecular sieve was added to 250mL of 1mol / L ammonium nitrate solution and heated at 65℃ for 6h. During the treatment, the mixture was stirred and refluxed. After filtration and washing until neutral, the mixture was dried at 100℃ for 12h. The operation was repeated once.

[0131] (23) The temperature was raised to 400℃ in a muffle furnace at a heating rate of 2℃ / min and calcined for 10h. The mixture was then ground to obtain HZSM-5 molecular sieve for later use.

[0132] (3) Physical mixing: Take 10g each of magnesium aluminum composite oxide and HZSM-5 molecular sieve, mix them in an agate mortar for 20 minutes, and then press them into tablets and sieve them through a 40-60 mesh sieve.

[0133] Comparative Example 2

[0134] This comparative example provides an aluminum-loaded acidic molecular sieve, which is prepared in a similar manner to Example 2, except that Mg(NO3)2 is not added in step (2), and the mass ratio of Al in the aluminum salt to the acidic molecular sieve is 1:60 in step (3).

[0135] Comparative Example 3

[0136] This comparative example provides an acidic molecular sieve loaded with magnesium. The preparation method is similar to that of Example 2, except that Al(NO3)3 is not added in step (2), and the mass ratio of Mg in the magnesium salt to the acidic molecular sieve is 1:60 in step (3).

[0137] Comparative Example 4

[0138] This comparative example provides an acidic molecular sieve loaded with nickel. The preparation method is similar to that of Example 2, except that in step (2), nickel sulfate is dissolved in water to prepare a 0.5 mol / L nickel salt solution, and in step (3), the mass ratio of nickel to acidic molecular sieve is 1:60.

[0139] Performance testing

[0140] Nitrogen adsorption-desorption tests were conducted using a physical adsorption apparatus at liquid nitrogen temperature (-196℃). Prior to the test, the samples were degassed under vacuum at 300℃ for 6 hours. Specific surface area was calculated using the BET method, and pore volume and pore size were analyzed using the BJH method to determine the desorption branch data.

[0141] The Al loading and Mg loading were detected using the following method:

[0142] A quantitative amount of catalyst sample was weighed and completely digested using microwave digestion to dissolve all Al and Mg. The sample was then cooled and diluted to a final volume to prepare the test solution. A series of Al and Mg standard solutions were prepared, and the element concentrations in the solutions were determined using the external standard method with characteristic spectral lines selected by ICP-OES inductively coupled plasma atomic emission spectrometry. Finally, the actual mass loading of Al and Mg in the catalyst was calculated.

[0143] Adopting such Figure 1 The apparatus shown is used for evaluating CO2 desorption. It mainly includes a three-necked flask, a constant-temperature oil bath, a reflux condenser, and a soap film flow meter. One neck of the three-necked flask is equipped with a reflux condenser to prevent the amine solution from evaporating during heating; the other two necks are used to mount thermometers to monitor the desorption temperature of the solution and for sampling. A CO2-rich amine solution (e.g., 5 mol / L MEA, with a CO2 loading of approximately 0.5 mol / mol) is mixed with a catalyst and heated to 96°C for desorption. The amount of CO2 released per unit time is recorded using a carbon dioxide gas mass flow meter, and the desorption rate is calculated.

[0144] A cyclic desorption-absorption experiment was employed. After each desorption cycle, the lean amine solution was replenished to the initial volume, CO2 was reabsorbed until saturation, and then the next desorption cycle was performed. The number of cycles at which the desorption rate decreased to 80% of the initial value was recorded as the catalyst lifetime. Simultaneously, the catalyst specific surface area retention rate was measured after 10 cycles to evaluate hydrothermal stability.

[0145] The results are shown in Table 1 below.

[0146] Table 1

[0147]

[0148] As shown in Table 1, the provided aluminum and magnesium-loaded acidic molecular sieves exhibit stable structure, long service life, and high CO2 desorption rate, which can reduce the energy consumption of CO2-rich amine solution regeneration and can be applied to complex amine regeneration / CO2 desorption processes.

[0149] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An acidic molecular sieve supported on aluminum and magnesium, characterized in that, The mixture comprises an acidic molecular sieve and alumina and magnesium oxide loaded within and / or on the surface of the acidic molecular sieve pores, wherein the mass ratio of aluminum in the alumina to the acidic molecular sieve is 1:(10~20), and the mass ratio of magnesium in the magnesium oxide to the acidic molecular sieve is 1:(40~60).

2. The acidic molecular sieve supported on aluminum and magnesium according to claim 1, characterized in that, The acidic molecular sieve loaded with aluminum and magnesium satisfies one or more of the following conditions: (1) Specific surface area is 320 m² 2 / g~380m 2 / g; (2) The pore size is 0.5 nm to 0.55 nm; (3) The pore volume is 0.16 cm 3 / g~0.20cm 3 / g; (4) The acidic molecular sieve comprises one or more of HZSM-5, MCM-41 and SBA-15; (5) The acidic molecular sieve contains silicon and aluminum, and the molar ratio of silicon to aluminum in the acidic molecular sieve is (50~100):

1.

3. The method for preparing the acidic molecular sieve supported on aluminum and magnesium as described in claim 1 or 2, characterized in that, Includes the following steps: The acidic molecular sieve is pretreated under an oxygen-containing atmosphere and high temperature, and then cooled in a first inert atmosphere to prepare the pretreated acidic molecular sieve. The pretreated acidic molecular sieve is immersed in an aqueous solution containing soluble aluminum and magnesium salts, ultrasonically dispersed, aged, dried, and calcined under a second inert atmosphere to prepare the aluminum and magnesium-loaded acidic molecular sieve.

4. The method for preparing the acidic molecular sieve supported on aluminum and magnesium according to claim 3, characterized in that, The preprocessing conditions must meet one or both of the following conditions: (1) Keep warm at 500℃~600℃ for 5h~7h; (2) The heating rate for pretreatment is 3℃ / min to 5℃ / min.

5. The method for preparing the acidic molecular sieve supported on aluminum and magnesium according to claim 3, characterized in that, One or more of the following conditions must be met: (1) The oxygen-containing atmosphere includes one or both of air and oxygen; (2) The flow rate of the oxygen-containing atmosphere is 40 mL / min to 60 mL / min; (3) The first inert atmosphere and the second inert atmosphere each independently include one or more of nitrogen and argon; (4) The flow rates of the first inert atmosphere and the second inert atmosphere are each 50 mL / min to 80 mL / min independently.

6. The method for preparing the acidic molecular sieve supported on aluminum and magnesium according to any one of claims 3 to 5, characterized in that, Drying methods include one or both of the following: blower drying and spray drying; Optionally, the drying process includes: drying at 50℃~60℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h; drying at 80℃~90℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h; and drying at 100℃~110℃ with an air flow rate of 50mL / min~60mL / min for 4h~5h. Optionally, the spray drying conditions include an inlet temperature of 150°C to 250°C and an outlet temperature of 80°C to 110°C.

7. The method for preparing the acidic molecular sieve supported on aluminum and magnesium according to any one of claims 3 to 5, characterized in that, One or more of the following conditions must be met: (1) The conditions for ultrasonic dispersion include: temperature of 40℃~50℃, power of 300W~400W, and time of 30min~60min; (2) The aging conditions include: temperature of 5℃~30℃ and time of 10h~20h; (3) The calcination conditions include: holding at 500℃~600℃ for 4h~5h; (4) The heating rate for calcination is 1℃ / min to 2℃ / min.

8. The method for preparing the acidic molecular sieve supported on aluminum and magnesium according to any one of claims 3 to 5, characterized in that, One or more of the following conditions must be met: (1) The mass ratio of aluminum in the soluble aluminum salt to the acidic molecular sieve is 1:(10~20); the mass ratio of magnesium in the magnesium salt to the acidic molecular sieve is 1:(40~60). (2) The soluble aluminum salt includes one or more of aluminum nitrate and aluminum chloride; (3) The magnesium salt includes one or more of magnesium nitrate and magnesium acetate.

9. The application of the aluminum- and magnesium-loaded acidic molecular sieve according to claim 1 or 2, or the aluminum- and magnesium-loaded acidic molecular sieve prepared by the preparation method according to any one of claims 3 to 8, in the catalytic desorption of carbon dioxide.

10. The application according to claim 9, characterized in that, The acidic molecular sieve loaded with aluminum and magnesium is contacted with a CO2-rich amine solution to desorb CO2.

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