A heteroatom mor-type zeolite, its preparation method and use in selective adsorption of nitrogen oxides

Abstract

The application provides a kind of heteroatom MOR type zeolite and its preparation method and application in selective adsorption of nitrogen oxide, it is related to nitrogen oxide treatment and zeolite synthesis technical field.The MOR type zeolite, water and soluble metal salt are mixed to carry out ion exchange, and the heteroatom MOR type zeolite is obtained;The metal element in the soluble metal salt includes one or more of group IIA metal element and transition metal element.The MOR type zeolite of the application is ion exchanged by specific metal salt, and the MOR type zeolite is doped with heteroatom metal, the pore characteristics of MOR type zeolite is improved, and the prepared heteroatom MOR type zeolite has excellent selective adsorption capacity of nitrogen oxide (NO x ) and can selectively adsorb NO x from flue gas (including NO x , CO2 and O2) efficiently.

Description

Technical Field

[0001] This invention relates to the fields of nitrogen oxide control and zeolite synthesis technology, and particularly to a heteroatom MOR-type zeolite, its preparation method, and its application in the selective adsorption of nitrogen oxides. Background Technology

[0002] Nitrogen oxides (NO) x NOx is a significant source of air pollution, causing numerous environmental problems and harming health, including photochemical smog, acid rain, and ozone layer depletion. In recent years, the issue of NOx has become increasingly prominent. x Emission restrictions are becoming increasingly stringent, thus requiring the search for effective methods to remove NO from flue gas. x The method for reducing NO has become a widely studied research topic. Among these, selective catalytic reduction (SCR) technology is widely used, but it is not suitable for low concentrations of NO. x However, the removal of NO2 is problematic due to issues such as ammonia leakage and catalyst poisoning / deactivation. In contrast, adsorption methods are simple, efficient, and highly suitable for removing low concentrations of NO2. x The removal of [something] has a promising application prospect.

[0003] Adsorption separation based on solid inorganic porous adsorbents is a novel gas adsorption separation technology with the following advantages: high product purity; generally operates at room temperature and low pressure; bed regeneration does not require heating, resulting in high product purity; simple equipment, easy operation and maintenance; continuous cyclic operation, fully automated. Therefore, this new technology has attracted attention from industries worldwide since its emergence. The core of this technology lies in the development of solid porous adsorbents.

[0004] Zeolite is an inorganic porous aluminosilicate widely used in petrochemicals, ion exchange, adsorption, and separation. The framework of zeolite consists of co-located TO₄ (T = Si or Al) tetrahedra, forming periodic and highly stable 1D to 3D channels. It possesses a unique porous structure with pore sizes typically <2 nm, covering most industrially important small molecule sizes. Currently, the framework element types for T have been further expanded to include P, Fe, B, Ga, Ti, Ge, etc., and 255 zeolite structures have been recognized by the International Zeolite Association – Structure Committee.

[0005] MOR-type zeolite, also known as mordenite, possesses excellent heat resistance, acid resistance, and moisture resistance. Industrially, it is widely used as an adsorbent for separating gas or liquid mixtures and as a catalyst in reactions such as hydrocarbon cracking, hydrocracking, dimethylamine synthesis, alkane isomerization, and alkylation of polycyclic aromatic compounds. It can also be used as a desiccant and adsorbent. Although there are reports on the adsorption and separation of gas molecules using zeolite, there are currently no reports on the separation of NO using MOR-type zeolite. x Case study. Summary of the Invention

[0006] In view of this, the present invention aims to provide a heteroatom MOR-type zeolite, its preparation method, and its application in the selective adsorption of nitrogen oxides. The heteroatom MOR-type zeolite prepared by the present invention can efficiently and selectively adsorb nitrogen oxides (NOx). x ).

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing heteroatom MOR-type zeolites, comprising the following steps:

[0009] The heteroatom MOR-type zeolite is obtained by ion exchange of a mixture of MOR-type zeolite, water, and a soluble metal salt; the metal element in the soluble metal salt includes one or more of Group IIA metal elements and transition metal elements.

[0010] Preferably, the Group IIA metal element includes magnesium and / or strontium; the transition metal element includes one or more of zinc, nickel, manganese, iron, cobalt and copper.

[0011] Preferably, the soluble metal salt includes one or more of chlorides, nitrates, and sulfates.

[0012] Preferably, the mass ratio of the MOR-type zeolite to water is 1:10 to 1:1000, and the concentration of soluble metal ions in the resulting mixture is 0.1 to 2 mol / L.

[0013] Preferably, the ion exchange temperature is 80–100°C and the time is 0.5–3 h.

[0014] Preferably, the preparation method of the MOR-type zeolite includes the following steps:

[0015] An alkali source, an aluminum source, a silicon source, and water are mixed to obtain a mother liquor; the alkali source is an alkali metal hydroxide and / or an alkali metal oxide, and the alkali source, aluminum source, silicon source, and water are respectively calculated as alkali metal oxide, Al2O3, SiO2, and H2O. The molar ratio of alkali metal oxide, Al2O3, SiO2, and H2O in the mother liquor is (3-10):1:(15-60):(350-1000).

[0016] The mother liquor was subjected to hydrothermal crystallization to obtain MOR-type zeolite; the hydrothermal crystallization temperature was 150-200℃ and the time was 24-72h.

[0017] The present invention provides heteroatom MOR-type zeolite prepared by the preparation method described above, wherein the heteroatoms in the heteroatom MOR-type zeolite include one or more of Group IIA metal elements and transition metal elements.

[0018] Preferably, the amount of heteroatom doped in the heteroatom MOR-type zeolite is 0.1–2 wt%.

[0019] This invention provides the application of the heteroatom MOR-type zeolite described above in the selective adsorption of nitrogen oxides.

[0020] Preferably, the nitrogen oxides are derived from a mixture of gases including CO2 and O2.

[0021] This invention provides a method for preparing heteroatom MOR-type zeolite, comprising the following steps: mixing MOR-type zeolite, water, and a soluble metal salt for ion exchange to obtain the heteroatom MOR-type zeolite; the metal element in the soluble metal salt includes one or more of Group IIA metals and transition metals. This invention uses specific metal salts for ion exchange to dope MOR-type zeolite with heteroatoms, thereby improving the pore characteristics of the MOR-type zeolite by altering the pore size and allowing some ions to enter the MOR-type zeolite framework or side pockets, thus changing the zeolite structure and making it more effective at capturing nitrogen oxides (NOx). x On the other hand, altering the equilibrium cations in MOR-type zeolites makes them more compatible with NO. x The heteroatom MOR-type zeolite prepared by this invention exhibits excellent selective adsorption of nitrogen oxides (NOx). x The ability to process flue gas (including NO) x Highly selective adsorption of NO in CO2 and O2 x . Attached Figure Description

[0022] Figure 1 The images show the XRD patterns of the heteroatom MOR-type zeolites prepared in Examples 1-8. Figure 1 The curves a to h correspond to Examples 1 to 8 respectively;

[0023] Figure 2 The heteroatom MOR-type zeolite prepared in Example 1 for NO x Dynamic penetration curve;

[0024] Figure 3 The heteroatom MOR-type zeolite prepared in Example 2 for NO x Dynamic penetration curve;

[0025] Figure 4 The heteroatom MOR-type zeolite prepared in Example 3 for NOx Dynamic penetration curve;

[0026] Figure 5 The heteroatom MOR-type zeolite prepared in Example 4 for NO x Dynamic penetration curve;

[0027] Figure 6 The heteroatom MOR-type zeolite prepared in Example 5 for NO x Dynamic penetration curve;

[0028] Figure 7 The heteroatom MOR-type zeolite prepared in Example 6 for NO x Dynamic penetration curve;

[0029] Figure 8 The heteroatom MOR-type zeolite prepared in Example 7 for NO x Dynamic penetration curve;

[0030] Figure 9 The heteroatom MOR-type zeolite prepared in Example 8 for NO x Dynamic penetration curve;

[0031] Figure 10 MOR-type zeolite prepared for Comparative Example 1 for NO x Dynamic penetration curve;

[0032] Figure 11 For comparative example 2, commercial Y-type zeolite was used for ion exchange of NO. x Dynamic penetration curve;

[0033] Figure 12 To compare the effect of commercial ZSM-5 zeolite on NO in Example 3 x Dynamic penetration curve. Detailed Implementation

[0034] This invention provides a method for preparing heteroatom MOR-type zeolites, comprising the following steps:

[0035] The heteroatom MOR-type zeolite is obtained by ion exchange of a mixture of MOR-type zeolite, water, and a soluble metal salt; the metal element in the soluble metal salt includes one or more of Group IIA metal elements and transition metal elements.

[0036] MOR-type molecular sieves were first synthesized by Barre et al. in 1952. The idealized MOR framework (space group: Cmcm) is constructed using mor(t-tes) as secondary structural units (CBUs). Each mor(t-tes) is connected in space by 4-membered rings, creating a two-dimensional (2D) channel system with 12-ring and 8-ring pore openings. In addition, the MOR molecular sieve has parallel 12-membered ring (MR) one-dimensional channels along the c-axis, with a pore size of [missing information]. arrive MOR molecular sieves have important applications in catalysis, such as methanol-to-olefins (MTO), dimethyl ether carbonylation, and adsorption. Although there are reports on the adsorption and separation of gas molecules using zeolites, there are currently no reports on the use of MOR to separate NO. x This is mainly because the known pore structure and charge properties of zeolites do not fully satisfy NO. x Conditions for deep separation. This invention improves the pore characteristics of MOR-type zeolites by heteroatom metal doping through ion exchange, making them suitable for NO... x Selective adsorption separation. This will be explained in detail below:

[0037] In this invention, the preparation method of the MOR-type zeolite preferably includes the following steps:

[0038] An alkali source, an aluminum source, a silicon source, and water are mixed to obtain a mother liquor; the alkali source is an alkali metal hydroxide and / or an alkali metal oxide, and the alkali source, aluminum source, silicon source, and water are respectively calculated as alkali metal oxide, Al2O3, SiO2, and H2O. The molar ratio of alkali metal oxide, Al2O3, SiO2, and H2O in the mother liquor is (3-10):1:(15-60):(350-1000).

[0039] The mother liquor was subjected to hydrothermal crystallization to obtain MOR-type zeolite.

[0040] In this invention, the alkali metal hydroxide preferably includes sodium hydroxide and / or potassium hydroxide, and the alkali metal oxide is preferably sodium oxide; the aluminum source preferably includes one or more of sodium aluminate, aluminum hydroxide, and boehmite; the silicon source preferably includes one or more of silica, silica sol, and tetraethyl orthosilicate. In this invention, the preferred method for mixing the alkali source, aluminum source, silicon source, and water is as follows: the alkali source is added to water for a first mixing to obtain a first solution; the aluminum source is added to the first solution for a second mixing to obtain a second solution; the remaining water is added to the second solution for a third mixing to obtain a third solution; the third solution is cooled to room temperature, and then the silicon source is added to it for a fourth mixing to obtain a mother liquor. In this invention, the first, second, third, and fourth mixing are preferably carried out under stirring conditions. This invention does not have particular requirements for the stirring speed and time, as long as the components are mixed evenly. In this invention, the molar ratio of alkali metal oxides, Al2O3, SiO2 and H2O in the mother liquor is (3-10):1:(15-60):(350-1000), preferably (6-10):1:(15-30):(780-1000).

[0041] In this invention, the hydrothermal crystallization temperature is preferably 150–200°C, more preferably 150–180°C, and the time is preferably 24–72 h, more preferably 24–36 h. Preferably, the mother liquor is transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization. After hydrothermal crystallization, the obtained crystallization product is preferably filtered, washed, and dried sequentially to obtain MOR-type zeolite; the pH value of the washed product is preferably 7–10, the drying temperature is preferably 80°C, and the drying time is preferably 24 h. In this invention, the yield of the MOR-type zeolite, calculated as Al₂O₃, is higher than 95%.

[0042] In this invention, the metal element in the soluble metal salt includes one or more of Group IIA metal elements and transition metal elements; the Group IIA metal elements preferably include magnesium and / or strontium; the transition metal elements preferably include one or more of zinc, nickel, manganese, iron, cobalt, and copper; the soluble metal salt preferably includes one or more of chlorides, nitrates, and sulfates. In embodiments of this invention, the soluble metal salt is specifically one or more of nickel nitrate, strontium chloride, magnesium nitrate, manganese nitrate, ferric sulfate, cobalt nitrate, copper nitrate, and zinc nitrate.

[0043] In this invention, the preferred method for mixing the MOR-type zeolite, water, and soluble metal salt is as follows: dispersing the MOR-type zeolite in water to obtain a zeolite dispersion; and dissolving the soluble metal salt in the zeolite dispersion. In this invention, the mass ratio of the MOR-type zeolite to water is preferably 1:10 to 1:1000, more preferably 1:100, and the water is preferably deionized water; the metal ion concentration of the soluble metal salt in the resulting mixture is preferably 0.1 to 2 mol / L, more preferably 1 mol / L. In this invention, the ion exchange temperature is preferably 80 to 100°C, more preferably 80 to 90°C, and the time is preferably 0.5 to 3 hours, more preferably 1 to 2 hours; the metal ions in the soluble metal salt, as heteroatoms, enter the MOR-type zeolite through ion exchange. After the ion exchange is completed, this invention preferably cools the resulting reaction solution to room temperature and then sequentially filters, washes, and dries it to obtain the heteroatom-containing MOR-type zeolite.

[0044] This invention provides heteroatom MOR-type zeolite prepared by the preparation method described above. The heteroatoms in the heteroatom MOR-type zeolite include one or more Group IIA metal elements and transition metal elements. The preferred doping amount of the heteroatoms in the heteroatom MOR-type zeolite is 0.1–2 wt%. This invention improves the pore characteristics of MOR-type zeolite by altering the pore size and allowing some ions to enter the MOR-type zeolite framework or side pockets, thus changing the zeolite structure and making it more effective at capturing NO. x On the other hand, altering the equilibrium cations in MOR-type zeolites makes them more compatible with NO. x In this embodiment of the invention, the heteroatom MOR-type zeolite is referred to as X-MOR-type zeolite, where X represents a heteroatom, i.e., the metal element corresponding to ion exchange.

[0045] This invention provides the application of the heteroatom MOR-type zeolite described above in the selective adsorption of nitrogen oxides. x There are no special requirements; any nitrogen oxide well-known to those skilled in the art can be used. In this invention, the nitrogen oxide is preferably derived from a mixture of gases including CO2 and O2. The heteroatom MOR-type zeolite prepared by this invention exhibits excellent selective adsorption of nitrogen oxides (NO). x The ability to process flue gas (including NO) x Highly selective adsorption of NO in CO2 and O2 x .

[0046] The following examples illustrate the heteroatom MOR-type zeolite, its preparation method, and its application in the selective adsorption of nitrogen oxides provided by this invention. However, these examples should not be construed as limiting the scope of protection of this invention.

[0047] Example 1

[0048] The preparation steps of heteroatom MOR type zeolites are as follows:

[0049] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0050] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 150°C for 24 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0051] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Strontium chloride was dissolved in the zeolite dispersion to adjust the strontium ion concentration to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain strontium-doped Sr-MOR-type zeolite.

[0052] The obtained strontium-doped Sr-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown in curve a, the product is consistent with the standard spectrum of MOR type zeolite.

[0053] The ability of strontium-doped Sr-MOR zeolite to dynamically capture NOx in a mixture of NOx, CO2, and O2 was tested under the following conditions:

[0054] The gas concentration (volume percentage) is 200 ppm NO. x The test conditions were: 14% O2, 4.5% CO2, with nitrogen as the equilibrium gas. The mass of the strontium-doped Sr-MOR zeolite was 2.25 g. The gas flow rate was 250 mL / min, and the test temperature was room temperature (298 K). The test results are shown below. Figure 2 (Dynamic breakthrough curve), the adsorption amount obtained by integral calculation is shown in Table 1.

[0055] Example 2

[0056] The preparation steps of heteroatom MOR type zeolites are as follows:

[0057] Add 31g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 838g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 49.1g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 10Na2O:Al2O3:15SiO2:1000H2O.

[0058] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 200°C for 72 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0059] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Nickel nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain nickel-doped Ni-MOR-type zeolite.

[0060] The obtained nickel-doped Ni-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown in curve b, the product is consistent with the standard spectrum of MOR type zeolite.

[0061] Testing of nickel-doped Ni-MOR type zeolites in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 3 The adsorption amount obtained by integral calculation is shown in Table 1.

[0062] Example 3

[0063] The preparation steps of heteroatom MOR type zeolites are as follows:

[0064] Add 13.2g of potassium hydroxide to 40g of water and stir until dissolved to form solution 1; add 19.85g of boehmite to solution 1 and stir until dissolved to form solution 2; add 267g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 49.1g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 3K2O:Al2O3:15SiO2:350H2O.

[0065] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 180°C for 72 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0066] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Manganese nitrate was dissolved in the zeolite dispersion, and the metal ion concentration was adjusted to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain manganese-doped Mn-MOR-type zeolite.

[0067] The obtained manganese-doped Mn-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown in the c-curve, the product's spectrum is consistent with the MOR-type zeolite standard spectrum.

[0068] Testing manganese-doped Mn-MOR type zeolites in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 4 The adsorption amount obtained by integral calculation is shown in Table 1.

[0069] Example 4

[0070] The preparation steps of heteroatom MOR type zeolites are as follows:

[0071] Add 44g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 19.85g of boehmite to solution 1 and stir until dissolved to form solution 2; add 267g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 49.1g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 10Na2O:Al2O3:15SiO2:350H2O.

[0072] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 180°C for 72 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0073] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Ferric sulfate was dissolved in the zeolite dispersion, and the metal ion concentration was adjusted to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain iron-doped Fe-MOR-type zeolite.

[0074] The obtained iron-doped Fe-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown in the d-curve, the product is consistent with the standard spectrum of MOR-type zeolite.

[0075] Testing iron-doped Fe-MOR type zeolites in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 5 The adsorption amount obtained by integral calculation is shown in Table 1.

[0076] Example 5

[0077] The preparation steps of heteroatom MOR type zeolites are as follows:

[0078] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0079] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 150°C for 24 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0080] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Magnesium nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain magnesium-doped Mg-MOR-type zeolite.

[0081] The obtained magnesium-doped Mg-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown by the e-curve, the product's spectrum is consistent with the MOR-type zeolite standard spectrum.

[0082] Testing magnesium-doped Mg-MOR type zeolites in NO x The ability to dynamically capture NOx in a mixture of CO2 and O2 gases was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 6 The adsorption amount obtained by integral calculation is shown in Table 1.

[0083] Example 6

[0084] The preparation steps of heteroatom MOR type zeolites are as follows:

[0085] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0086] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 150°C for 24 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0087] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion; cobalt nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L; the resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange; after cooling, it was filtered, washed and dried to obtain cobalt-doped Co-MOR-type zeolite.

[0088] The obtained cobalt-doped Co-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown by curve f, the product is consistent with the standard spectrum of MOR type zeolite.

[0089] Testing of cobalt nitrate-doped Co-MOR type zeolites in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 7 The adsorption amount obtained by integral calculation is shown in Table 1.

[0090] Example 7

[0091] The preparation steps of heteroatom MOR type zeolites are as follows:

[0092] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3. After the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0093] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 150°C for 24 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0094] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Copper nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain copper-doped Cu-MOR-type zeolite.

[0095] The obtained copper-doped Cu-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown in curve g, the product is consistent with the standard spectrum of MOR type zeolite.

[0096] Testing of copper nitrate-doped Cu-MOR type zeolite in NO x Dynamic capture of NO in CO2, O2 and mixed gases x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 8 The adsorption amount obtained by integral calculation is shown in Table 1.

[0097] Example 8

[0098] The preparation steps of heteroatom MOR type zeolites are as follows:

[0099] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0100] The mother liquor was transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal crystallization at a temperature of 150°C for 24 hours. The crystallized product was collected by filtration, washing and drying. The pH of the washed product was less than 10. The drying temperature was 80°C and the drying time was 24 hours to obtain the primary product, namely MOR-type zeolite.

[0101] The above-mentioned MOR-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion; zinc nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L; the resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange; after cooling, zinc-doped Zn-MOR-type zeolite was obtained by filtration, washing and drying.

[0102] The obtained zinc-doped Zn-MOR type zeolite product was subjected to XRD testing, and the test results are as follows: Figure 1 As shown by curve h, the product is consistent with the standard spectrum of MOR type zeolite.

[0103] Testing cobalt nitrate-doped Zn-MOR type zeolites in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 9 The adsorption amount obtained by integral calculation is shown in Table 1.

[0104] Comparative Example 1

[0105] The preparation steps of MOR-type zeolite (non-heteroatom doped) are as follows:

[0106] Add 19g of sodium hydroxide to 40g of water and stir until dissolved to form solution 1; add 14.3g of aluminum hydroxide to solution 1 and stir until dissolved to form solution 2; add 645g of water to solution 2 to form solution 3; after the above solutions have cooled to room temperature, add 98.2g of silica to solution 3 and stir until dissolved to form mother liquor. The ratio (molar ratio) of the mother liquor is 6Na2O:Al2O3:30SiO2:780H2O.

[0107] Testing MOR-type zeolite in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 10 The adsorption amount obtained by integral calculation is shown in Table 1.

[0108] Comparative Example 2

[0109] Commercial Y-type zeolite was dispersed in deionized water at a solid-liquid mass ratio of 1:100 to obtain a zeolite dispersion. Cobalt nitrate was dissolved in the zeolite dispersion to adjust the metal ion concentration to 1 mol / L. The resulting mixture was heated to 80°C and kept at that temperature for 2 hours for ion exchange. After cooling, it was filtered, washed, and dried to obtain cobalt-doped Co-Y-type zeolite.

[0110] Testing Co-Y type zeolite in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 11 The adsorption amount obtained by integral calculation is shown in Table 1.

[0111] Comparative Example 3

[0112] Testing commercial ZSM-5 zeolite in NO x Dynamic capture of NO in a mixture of CO2 and O2 x The capability was tested under the same conditions as in Example 1, and the test results are shown in [reference needed]. Figure 12 The adsorption amount obtained by integral calculation is shown in Table 1.

[0113] Table 1. Dynamic NOx adsorption capacity of zeolites obtained in Examples 1-8 and Comparative Examples 1-3

[0114]

[0115]

[0116] As can be seen from the above embodiments, the heteroatom MOR-type zeolite prepared by ion exchange through heteroatom metal doping of MOR-type zeolite exhibits excellent selective adsorption of nitrogen oxides (NOx). x The ability to process flue gas (including NO) x Highly selective adsorption of NO in CO2 and O2 x .

[0117] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of a heteroatom MOR-type zeolite in selective adsorption of nitrogen oxides, wherein the heteroatom in the heteroatom MOR-type zeolite is magnesium, and a method for preparing the heteroatom MOR-type zeolite, comprising the following steps: mixing a MOR-type zeolite, water and a soluble metal salt to perform ion exchange, to obtain the heteroatom MOR-type zeolite; the metal element in the soluble metal salt is magnesium; the method for preparing the MOR-type zeolite comprises the following steps: mixing an alkali source, an aluminum source, a silicon source and water to obtain a mother liquor; the alkali source is an alkali metal hydroxide and / or an alkali metal oxide, and the alkali source, the aluminum source, the silicon source and water are respectively calculated as alkali metal oxide, Al2O3, SiO2 and H2O, and the molar ratio of alkali metal oxide, Al2O3, SiO2 and H2O in the mother liquor is (3-10):1:(15-60):(350-1000); hydrothermally crystallizing the mother liquor to obtain a MOR-type zeolite; the temperature of the hydrothermal crystallization is 150-200℃, and the time is 24-72h.

2. Use according to claim 1, characterized in that, The soluble metal salt includes one or more of chloride, nitrate and sulfate.

3. Use according to claim 1, characterized in that, The mass ratio of the MOR-type zeolite to water is 1:10-1:1000, and the metal ion concentration of the soluble metal salt in the obtained mixed solution is 0.1-2mol / L.

4. Use according to claim 1, characterized in that, The temperature of the ion exchange is 80-100℃, and the time is 0.5-3h.

5. The use according to claim 1, characterized in that, The doping amount of the heteroatom in the heteroatom MOR-type zeolite is 0.1-2wt%.

6. Use according to claim 1, characterized in that, The nitrogen oxides are from a mixed gas including CO2 and O2.

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