Preparation method of H-type aluminosilicate zeolite

Abstract

The invention belongs to the technical field of catalyst materials, and particularly relates to a preparation method of H-type aluminosilicate zeolite. The preparation method comprises the following steps: carrying out ion exchange on aluminosilicate zeolite containing metal cations by using an organic acid aqueous solution as an exchange medium to obtain the H-type aluminosilicate zeolite. As a green generation process, the method has the advantages of low energy consumption, no waste gas, no pollution waste water and the like while saving process steps and raw material cost. The problems of high energy consumption and ammonia nitrogen wastewater / irritant waste gas treatment in the traditional ammonium exchange process and the problems of inorganic acid radical wastewater treatment and equipment corrosion in the strong acid exchange process are avoided. The method is also suitable for aluminosilicate zeolite including ZSM-5, Beta, Y and the like, and has relatively high environmental protection advantages and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials technology, specifically relating to a method for preparing H-type aluminosilicate zeolite. Background Technology

[0002] H-SSZ-13, as a functional carrier containing protic acids, has attracted much attention in recent years and has been widely used in automotive exhaust aftertreatment (NH3-SCR), coal chemical industry (MTO), and gas separation (CO2 separation membrane). In the field of automotive exhaust aftertreatment, Cu-SSZ-13 molecular sieve material has become the first choice for denitrification catalysts for China VI emission standard vehicles due to its excellent SCR performance. In the preparation of SSZ-13, an alkali metal (Alk) needs to be added to stabilize the charge of the molecular sieve framework. Therefore, the crystallization product after molecular sieve production is Alk-SSZ-13. To obtain H-SSZ-13, an "ion exchange" process is required.

[0003] The most commonly used ion exchange scheme is "ammonium exchange," which utilizes the NH4+ in the ammonium salt solution. + The method involves replacing alkali metal ions from Alk-SSZ-13. However, this method generates a large amount of ammonia nitrogen wastewater and requires an additional roasting step to convert NH3-SSZ-13 to H-SSZ-13, thus reducing economic efficiency. Developing low-pollution, low-cost ion exchange processes is a very important direction.

[0004] This application is submitted in order to address the above issues. Summary of the Invention

[0005] To address the problems of long process routes, high energy consumption and costs, and large wastewater discharge in existing Alk-SSZ-13 processes, this application provides a green ion exchange process that features low energy consumption, a short process route, and the ability to obtain additional economically valuable byproducts after simple wastewater treatment. This process can effectively replace traditional ammonium exchange processes.

[0006] This application relates to an ion exchange method for preparing H-SSZ-13 from AlK (alkali metal)-SSZ-13. Specifically, the ion exchange method uses an organic acid solution as the exchange medium, and performs ion exchange on AlK-SSZ-13 under low water consumption conditions to directly obtain H-SSZ-13; furthermore, the organic acid waste liquid can be treated harmlessly to obtain economically valuable additional by-products. As a green production process, this application saves on process steps and raw material costs, while also offering advantages such as low energy consumption, no waste gas, and no polluting wastewater. This application avoids the high energy consumption and ammonia nitrogen wastewater / irritating waste gas treatment problems of traditional "ammonia exchange processes," as well as the inorganic acid wastewater treatment and equipment corrosion problems of strong acid exchange processes. This application is not only applicable to the preparation of H-SSZ-13 from AlK (alkali metal)-SSZ-13, but also applicable to aluminosilicate zeolites including ZSM-5, Beta, and Y, exhibiting significant environmental advantages and economic benefits.

[0007] The technical solution of this application is as follows:

[0008] This application provides a method for preparing H-type aluminosilicate zeolite, the preparation comprising: using an aqueous organic acid solution as an exchange medium to perform ion exchange on aluminosilicate zeolite containing metal cations to obtain H-type aluminosilicate zeolite.

[0009] Preferably, the organic acid is selected from one or more of oxalic acid, formic acid, acetic acid, and citric acid.

[0010] Preferably, the ion exchange includes the following steps:

[0011] (1) A mixture is prepared by mixing an aluminosilicate containing a metal cation, an organic acid, and water, such that the concentration of the organic acid in the mixture is 40-240 g / L, and the content of the aluminosilicate zeolite containing the metal cation is 20-35 wt%.

[0012] (2) Ion exchange: control the exchange temperature to 20~60℃, control the total exchange time to 0.5~4h, control the number of exchanges to 1~5 times, and the resulting solid is H-type aluminosilicate zeolite.

[0013] More preferably, the total exchange time is 1-2.5 hours.

[0014] More preferably, the content of the aluminosilicate zeolite containing metal cations is 20-25 wt%.

[0015] More preferably, the concentration of organic acid in the mixture is 40~120 g / L.

[0016] More preferably, the number of exchanges is 1 to 3.

[0017] Preferably, the preparation method further includes:

[0018] (3) Washing and waste liquid treatment: The mixture in step (3) is filtered by pressure, and the filtered product is washed to obtain H-type aluminosilicate zeolite.

[0019] Preferably, the aluminosilicate zeolite containing metal cations is one or more of AlK-SSZ-13 aluminosilicate zeolite, ZSM-5 aluminosilicate zeolite, Beta aluminosilicate zeolite, and Y-type aluminosilicate zeolite.

[0020] Preferably, step (1) includes:

[0021] (11) Preparation of exchange medium: Prepare an aqueous solution of organic acid with a concentration of 40~240g / L;

[0022] (12) Solid-liquid mixing: Add aluminosilicate zeolite containing metal cations into the exchange liquid, and make the solid content 20~35wt%.

[0023] Preferably, step (1) includes:

[0024] First, a slurry containing metal cations is prepared by pulping aluminosilicates to a solid content of 20-35 wt%. Then, an organic acid is added to the slurry to make the organic acid concentration 40-240 g / L.

[0025] Preferably, the wastewater containing organic acid radicals obtained in step (2) is added to quicklime and then distilled or crystallized to obtain organic acid calcium salt byproducts.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention proposes for the first time a method for obtaining H-type aluminosilicate zeolite zeolite by ion exchange of metal cations using acid exchange. Specifically, this application uses an organic acid solution as the exchange medium to perform ion exchange on aluminosilicate zeolite zeolite (e.g., AlK-SSZ-13) containing metal cations under certain solid content, temperature, and exchange time conditions, directly obtaining H-type aluminosilicate zeolite zeolite (e.g., H-SSZ-13). This application eliminates the roasting process in traditional ammonium exchange processes (e.g., the roasting process for converting NH3-SSZ-13 to H-SSZ-13).

[0028] 2. Furthermore, this application does not use strong acids for acid exchange, thus avoiding water pollution caused by nitrate and sulfate ions during the strong acid exchange process, and has significant economic and environmental advantages. Moreover, this method is also applicable to other aluminosilicate zeolites, and has a broad application market.

[0029] 3. The ion exchange method for preparing H-SSZ-13 of this invention has fewer process steps (reducing drying and calcination compared to traditional processes). The final product, besides H-SSZ-13, consists only of a small amount of wastewater containing organic acid radicals, which can be easily treated to render it harmless. This allows for the direct discharge of wastewater while simultaneously obtaining additional economically beneficial byproducts. For example, quicklime can be added to the wastewater containing organic acid radicals, followed by distillation or crystallization to obtain calcium salts of organic acids as byproducts.

[0030] 4. The H-SSZ-13 prepared by the method of this application can completely retain the skeletal aluminum, achieving a final effect similar to that of the ammonium exchange process. It can be used directly or after appropriate loading treatment in catalysis, adsorption and separation fields such as methanol to olefins (MTO), automobile exhaust denitrification (Cu-SSZ-13), and CO2 separation (SSZ-13 membrane).

[0031] 5. This exchange method can exchange the total amount of alkali metal ions in AlK-SSZ-13 zeolite molecular sieve to 0.1~0.0 wt%. Therefore, the method of this application can simply and effectively remove alkali metals from AlK-SSZ-13.

[0032] 6. This application also found that the acid exchange process can also remove the "unstable framework aluminum" on the surface to improve the overall hydrothermal stability of the supported catalyst (zeolite-supported metal ions).

[0033] 7. This application also discovers that by employing an acid exchange process, the "acid density overload region (aluminum enrichment region)" can be complexed and removed in a "one-step" manner by adjusting the exchange conditions. This results in a relatively mild active site for the catalyst, making it more suitable for long-term use in coal chemical / petrochemical industries. Furthermore, the formation of an internal hierarchical porous structure due to dealumination is beneficial for improving the diffusion of "coke precursors" during the reaction process, delaying coke deposition and deactivation. Ultimately, this achieves a dual improvement in "selectivity" and "catalytic lifetime" in the catalytic reaction. Attached Figure Description

[0034] Figure 1 The XRD diffraction patterns are those of H-SSZ-13 prepared according to Example 2 of the present invention and samples prepared by conventional ammonium exchange roasting according to Comparative Example 1.

[0035] Figure 2 This is a comparison chart of the NH3-SCR performance of H-SSZ-13 prepared by organic acid exchange in Example 4 and ammonium carbonate exchange in Comparative Example 1 after Cu loading and hydrothermal aging.

[0036] Figure 3 The results are NH3-TPD comparisons of H-SSZ-13 prepared by organic acid exchange in Example 6 and by carbomonium exchange in Comparative Example 2 according to the present invention. Detailed Implementation

[0037] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in manuals, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials required in the following embodiments and comparative examples are all commercially available.

[0038] This application provides an ion exchange method for preparing H-SSZ-13, which uses an organic acid solution as the exchange medium to perform ion exchange on AlK-SSZ-13 to directly obtain H-SSZ-13; and the organic acid waste liquid can be treated to obtain additional by-products.

[0039] The method of the present invention is also applicable to aluminosilicate zeolites including ZSM-5, Beta, and Y-type, specifically: using an organic acid solution as an exchange medium to perform ion exchange on ZSM-5, Beta, and Y-type aluminosilicate zeolites to obtain H-ZSM-5 aluminosilicate zeolite, H-Beta aluminosilicate zeolite, and HY-type aluminosilicate zeolite.

[0040] Taking AlK-SSZ-13 as an example, the method of the present invention includes the following steps:

[0041] (1) Preparation of exchange medium: Prepare an organic acid solution with a concentration of 40~240g / L;

[0042] (2) Solid-liquid mixing: AlK-SSZ-13 is added to the exchange solution with a solid content of 20~35wt%;

[0043] (3) Ion exchange: control the exchange temperature to room temperature to 60℃, control the exchange time to 0.5 to 4h, and control the number of exchanges to 1 to 5 times;

[0044] (4) Washing and waste liquid treatment: The filter product in step (3) is subjected to one filter washing / pulping washing to directly obtain H-SSZ-13.

[0045] Collect all the wastewater from steps (3) and (4), which contains organic acid radicals. Then add an appropriate amount of quicklime to the wastewater containing organic acid radicals and adjust the pH until it reaches the discharge standard; at the same time, use the remaining energy of the overall production process to "distill / crystallize" to obtain additional byproducts such as calcium oxalate, calcium formate, and calcium acetate.

[0046] Step (1) The types of organic acids include, but are not limited to, one or more of oxalic acid, formic acid, acetic acid, citric acid, etc., whose acid radicals can form economically valuable salt solutions / precipitates with calcium ions or other alkali metal ions.

[0047] Steps (2) and (1) can be replaced by: first, pulping AlK-SSZ-13 to prepare a slurry with a solid content of 20~35wt%, and then adding the amount of organic acid required in step (1) into the system.

[0048] In step (3), as the exchange temperature increases, the exchange time is shortened accordingly, and the number of exchanges is reduced accordingly.

[0049] If the washing steps are reduced after each exchange, the number of exchanges needs to be increased.

[0050] The following provides further details about the scheme of this application. The wastewater referred to below refers to the wastewater obtained in steps (3) and (4). Exchange time refers to the total exchange time.

[0051] Example 1

[0052] (1) Prepare an oxalic acid aqueous solution with a concentration of 40 g / L as the exchange medium;

[0053] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0054] (3) The exchange temperature is 60℃, the exchange time is 2.5h, the number of exchanges is 3, and after each exchange, the same mass of deionized water as the molecular sieve dry basis is used for filtration and washing once.

[0055] (4) The mixture obtained in step (3) is subjected to pressure filtration, and the pressure filtration product is washed once to obtain H-SSZ-13. Quicklime is added to the wastewater containing only acetate and a small amount of sodium ions to obtain calcium oxalate solution as a byproduct.

[0056] Example 2

[0057] (1) Prepare a 50 g / L formic acid aqueous solution as the exchange medium;

[0058] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 25 wt%;

[0059] (3) The exchange temperature is 55℃, the exchange time is 2h, the number of exchanges is 3, and after each exchange, the molecular sieve dry basis is filtered and washed once with deionized water of the same mass.

[0060] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is slurryed and washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing only formate and a small amount of sodium ions to obtain calcium formate solution byproduct.

[0061] Example 3

[0062] (1) Prepare an aqueous solution of acetic acid with a concentration of 60 g / L as the exchange medium;

[0063] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0064] (3) The exchange temperature is 50℃, the exchange time is 2h, the number of exchanges is 2, and after each exchange, the molecular sieve dry basis is filtered and washed once with deionized water of the same mass.

[0065] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing only acetate and a small amount of sodium ions to obtain calcium acetate solution.

[0066] Example 4

[0067] (1) Prepare a citric acid aqueous solution with a concentration of 70 g / L as the exchange medium;

[0068] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0069] (3) The exchange temperature is 50℃, the exchange time is 1.5h, the number of exchanges is 2, and after each exchange, the same mass of deionized water as the molecular sieve dry basis is used for filtration and washing.

[0070] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is slurryed and washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing only citrate and a small amount of sodium ions to obtain calcium citrate precipitate by-product.

[0071] Example 5

[0072] (1) Prepare an 80 g / L citric acid aqueous solution as the exchange medium;

[0073] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0074] (3) The exchange temperature is 45℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0075] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is slurryed and washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing only citrate and a small amount of sodium ions to obtain calcium citrate precipitate by-product.

[0076] Example 6

[0077] (1) Prepare a mixed aqueous solution of formic acid and citric acid with a concentration of 90 g / L (molar ratio of formic acid to citric acid is 3:1).

[0078] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0079] (3) The exchange temperature is 40℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0080] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing organic acid radicals and a small amount of sodium ions to obtain calcium citrate precipitant calcium formate solution by-product.

[0081] Example 7

[0082] (1) Prepare a mixed aqueous solution of acetic acid and citric acid with a concentration of 100 g / L (the molar ratio of acetic acid to citric acid is 1:1).

[0083] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0084] (3) The exchange temperature is 40℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0085] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing organic acid radicals and a small amount of sodium ions to obtain calcium acetate solution and calcium citrate precipitate by-product.

[0086] Example 8

[0087] (1) Prepare a mixed aqueous solution of oxalic acid and formic acid with a concentration of 110 g / L (molar ratio of oxalic acid to formic acid is 3:1).

[0088] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0089] (3) The exchange temperature is 40℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0090] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once to obtain H-SSZ-13; quicklime is added to the wastewater containing organic acid radicals and a small amount of sodium ions to obtain a mixed solution of oxalic acid and calcium formate as a byproduct.

[0091] Example 9

[0092] (1) Prepare an aqueous solution of acetic acid with a concentration of 120 g / L;

[0093] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0094] (3) The exchange temperature is 30℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0095] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once by filtration / pulping to obtain H-SSZ-13; quicklime is added to the wastewater containing acetate and a small amount of sodium ions to obtain calcium acetate solution byproduct.

[0096] Example 10

[0097] (1) Prepare an aqueous solution of acetic acid with a concentration of 120 g / L;

[0098] (2) Add AlK-SSZ-13 to the exchange solution, with a solid content of 20 wt%;

[0099] (3) Control the exchange temperature to room temperature of 20℃, control the exchange time to 1h, and the number of exchanges to 1 time. After each exchange, filter and wash once with the same mass of deionized water as the molecular sieve dry basis.

[0100] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once to obtain H-SSZ-13; sodium carbonate or sodium bicarbonate is added to the wastewater containing acetate and a small amount of sodium ions to obtain sodium acetate solution byproduct.

[0101] Example 11

[0102] (1) Prepare an aqueous solution of acetic acid with a concentration of 120 g / L;

[0103] (2) Add AlK-ZSM-5 to the exchange solution, with a solid content of 20 wt%;

[0104] (3) Control the exchange temperature to room temperature of 20℃, control the exchange time to 1h, and the number of exchanges to 1 time. After each exchange, filter and wash once with the same mass of deionized water as the molecular sieve dry basis.

[0105] The mixture obtained in step (3) is subjected to pressure filtration, and the pressure filtration product is washed once to obtain H-ZSM-5; sodium carbonate or sodium bicarbonate is added to the wastewater containing acetate and a small amount of sodium ions to obtain sodium acetate solution byproduct.

[0106] Example 12

[0107] (1) Prepare a mixed aqueous solution of acetic acid and formic acid with a concentration of 110 g / L (the molar ratio of acetic acid to formic acid is 3:1).

[0108] (2) Add AlK-Y to the exchange solution with a solid content of 20 wt%;

[0109] (3) The exchange temperature is 40℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0110] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once by filtration / pulping to obtain HY; quicklime is added to the wastewater containing organic acid radicals and a small amount of sodium ions to obtain a mixed solution of acetic acid and calcium formate as a byproduct.

[0111] Example 13

[0112] (1) Prepare a mixed aqueous solution of formic acid and citric acid with a concentration of 90 g / L (molar ratio of formic acid to citric acid 3:1).

[0113] (2) Add AlK-Beta to the exchange solution with a solid content of 20 wt%;

[0114] (3) The exchange temperature is 40℃, the exchange time is 1h, the number of exchanges is 2, and after each exchange, the molecular sieve is washed once with the same mass of deionized water as dry molecular sieve.

[0115] (4) The mixture obtained in step (3) is filtered by pressure, and the filtered product is washed once by filtration / pulping to obtain H-Beta; quicklime is added to the wastewater containing organic acid radicals and a small amount of sodium ions to obtain calcium citrate precipitant calcium formate solution by-product.

[0116] Comparative Example 1

[0117] Using a traditional ammonium exchange process, AlK-SSZ-13 was mixed with a 150 g / L ammonium bicarbonate solution at a solid content of 30 wt% to prepare a homogeneous slurry, which was then subjected to ion exchange at 40 °C for 1 h. After one round of filtration and washing, the filter cake was slurried and supplemented with ammonium bicarbonate (to a concentration of 150 g / L) for a second exchange, which lasted for 1 h. After two rounds of exchange, the slurry was pressure filtered and washed with twice the amount of deionized water (dry basis of molecular sieve). The dried NH3-SSZ-13 was then calcined at 500 °C for 4 h to obtain H-SSZ-13.

[0118] In Comparative Example 1, it was found that if washing was performed multiple times, a large amount of ammonia nitrogen wastewater would be generated; if washing was insufficient, a large amount of ammonia gas with an irritating odor would be generated in the subsequent drying section.

[0119] Comparative Example 2

[0120] A strong acid exchange process was adopted to prepare a homogeneous slurry by mixing AlK-SSZ-13 with a 75 g / L nitric acid solution with a solid content of 30 wt%, and then performing ion exchange at 40 °C for 1 h. After one round of filtration and washing, the filter cake was slurried and supplemented with nitric acid (to a nitric acid content of 75 g / L) for a second exchange, which lasted for 1 h. After two rounds of exchange, the slurry was pressure filtered and washed with twice the amount of deionized water based on the dry molecular sieve.

[0121] In Comparative Example 2, it was found that repeated washing resulted in a large amount of ammonia nitrogen wastewater; insufficient washing resulted in a large amount of pungent NO2- odor being generated in the subsequent roasting stage. x The gas poses a risk of corrosion to the equipment.

[0122] Figure 1 The XRD diffraction patterns are those of H-SSZ-13 prepared according to Example 2 of the present invention and samples prepared by conventional ammonium exchange roasting according to Comparative Example 1. Figure 1 Note: By controlling the exchange conditions, alkali metals can be removed while maintaining the crystallinity of SSZ-13, achieving an effect similar to that of traditional ammonium exchange.

[0123] Figure 2 This is a comparison chart of the NH3-SCR performance of H-SSZ-13 prepared by organic acid exchange in Example 4 and ammonium carbonate exchange in Comparative Example 1 after Cu loading and hydrothermal aging. Figure 2 Note: Cu-SSZ-13 with the same copper content was prepared by equal-volume impregnation, followed by standing, drying, and calcination at 550℃ for 4 hours. Two aged samples were obtained by aging treatment (800℃, 10% moisture for 16 hours) on Cu-SSZ-13 prepared by two exchange methods and loaded with copper. The samples were then tested under simulated automobile exhaust conditions (space velocity = 100,000 h⁻¹). -1 (Based on a coating of 150g / L) NO: 500ppm; NH3: 500ppm; O2: 10; H2O: 3.0%) NH3-SCR performance was tested.

[0124] Figure 3 The results are NH3-TPD comparisons of H-SSZ-13 prepared by organic acid exchange in Example 6 and by carbomonium exchange in Comparative Example 2 according to the present invention. Figure 3 Note: By controlling the exchange conditions, it is possible to achieve the removal of alkali metals while maintaining the aluminum skeleton of SSZ-13.

[0125] The ion exchange method described in this invention can remove alkali metal ions and free up ion exchange sites (B acid sites) in the molecular sieve. Figure 3The presence of a distinct NH3 desorption peak at 350℃ indicates that the strong Brønsted acid sites inherent in the molecular sieve are exposed after alkali metal removal following ion exchange.

[0126] The chemical composition of the raw materials and post-exchange products in several embodiments and comparative examples was measured using an elemental analyzer, and the proportions of silicon, aluminum, and alkali metals were tested by ICP elemental analysis. The above analysis reveals the extent of damage to the zeolite molecular sieve itself caused by ion exchange, as well as its ability to remove alkali metal ions. The measured elemental composition data are shown in Table 1.

[0127] Table 1

[0128]

[0129] As shown in Table 1, compared with Comparative Examples 1 and 2, the ion exchange method of this invention has a similar ability to remove alkali metals as traditional ammonium exchange. By adjusting the exchange conditions, such as in Example 1, partial removal of aluminum-rich regions can be achieved. Combined with processes such as roasting and wastewater treatment, it can be seen that this method has significant economic advantages. The reason why partial removal of aluminum-rich regions can be achieved in Example 1 may be due to the effect of oxalic acid.

[0130] Application Example 1

[0131] The products obtained from the exchanges in Examples 1 and 2 were used as catalysts in the methanol-to-olefins (MTO) reaction. In a fixed-bed reactor, the catalyst was activated at 500°C under a nitrogen atmosphere for 1 hour, and then the temperature was lowered to 400°C. Saturated methanol vapor at 40°C was passed through the catalyst (0.2 g) at a nitrogen flow rate of 10 ml / min for 2 hours. -1 The methanol-to-olefins (MTO) reaction was tested under space velocity conditions, and the measured reaction data are shown in Table 2.

[0132] Table 2

[0133]

[0134] As shown in Table 2, compared to Example 5, the Sample 1, after partial aluminum removal via ion exchange, exhibited significantly better overall selectivity (nearly 3%) for high-value-added products (ethylene and propylene) in the MTO reaction through acid site optimization. Furthermore, the hierarchical porous structure obtained through ion exchange removal etching nearly doubled the catalytic lifetime. This approach, by simultaneously optimizing the active sites of solid acid catalysis during the ion exchange stage, saves process costs and yields more efficient and stable petrochemical and coal chemical catalysts.

Claims

1. A method for preparing H-type aluminosilicate zeolite, characterized in that, The preparation method includes: using an aqueous organic acid solution as an exchange medium to perform ion exchange on aluminosilicate zeolite containing metal cations to obtain H-type aluminosilicate zeolite.

2. The method for preparing H-type aluminosilicate zeolite according to claim 1, characterized in that, The organic acid is selected from one or more of oxalic acid, formic acid, acetic acid, and citric acid.

3. The method for preparing H-type aluminosilicate zeolite according to claim 2, characterized in that, The ion exchange includes the following steps: (1) Mix metal cationic aluminosilicate, organic acid and water to make the organic acid concentration 40~240g / L, and the metal cationic aluminosilicate content 20~35wt%; (2) Ion exchange: control the exchange temperature to 20~60℃, control the total exchange time to 0.5~4h, control the number of exchanges to 1~5 times, and the resulting solid is H-type aluminosilicate zeolite.

4. The method for preparing H-type aluminosilicate zeolite according to claim 3, characterized in that, The preparation method further includes: (3) Washing and waste liquid treatment: The mixture in step (3) is filtered by pressure, and the filtered product is washed to obtain H-type aluminosilicate zeolite.

5. The method for preparing H-type aluminosilicate zeolite according to claim 3, characterized in that, The metal cation aluminosilicate zeolite is one or more of AlK-SSZ-13 aluminosilicate zeolite, ZSM-5 aluminosilicate zeolite, Beta aluminosilicate zeolite, and Y-type aluminosilicate zeolite.

6. The method for preparing H-type aluminosilicate zeolite according to claim 3, characterized in that, Step (1) includes: (1) Preparation of exchange medium: Prepare an aqueous solution of organic acid with a concentration of 40~240g / L; (2) Solid-liquid mixing: Add metal cation aluminosilicate zeolite into the exchange liquid, and make the solid content 20~35wt.

7. The method for preparing H-type aluminosilicate zeolite according to claim 3, characterized in that, Step (1) includes: First, the metal cationic aluminosilicate is pulped to prepare a slurry with a solid content of 20~35wt%. Then, organic acid is added to the slurry to make the organic acid concentration 40~240g / L.

8. The method for preparing H-type aluminosilicate zeolite according to claim 3, characterized in that, The wastewater containing organic acid radicals obtained in step (2) is added to quicklime and then distilled or crystallized to obtain organic acid calcium salt byproducts.

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