CN109422276B - Transition metal doped molecular sieve and preparation method and application thereof - Google Patents

Transition metal doped molecular sieve and preparation method and application thereof Download PDF

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CN109422276B
CN109422276B CN201710761879.5A CN201710761879A CN109422276B CN 109422276 B CN109422276 B CN 109422276B CN 201710761879 A CN201710761879 A CN 201710761879A CN 109422276 B CN109422276 B CN 109422276B
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CN109422276A (en
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王树东
柯权力
孙天军
顾一鸣
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Dalian Institute of Chemical Physics of CAS
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Abstract

The invention provides a transition metal doped molecular sieve, and preparation and application thereof, wherein the molecular sieve has RHO molecular sieve configuration and comprises a chemical composition X with the following molar ratio 2 O 3 ：aYO 2 ：bZO：cM δ O, where Y is some tetravalent element; x is a certain trivalent element; z is a transition metal element; m is a monovalent or polyvalent cation. The molecular sieve is synthesized by adopting initial gel prepared by crown ether, sodium, cesium, water, a silicon source, an aluminum source or a boron source and transition metal through a hydrothermal method. The molecular sieve framework of the invention is doped with partial transition metal elements which can be in CO 2 ‑CH 4 Preferential mass adsorption of CO in separations 2 In CH 4 ‑N 2 Preferential mass adsorption of CH in separation 4 In the presence of CO 2 ‑N 2 Preferential mass adsorption of CO in separations 2 . When the molecular sieve is applied to a tail gas treatment process, the reduction activity of the molecular sieve on nitrogen oxides at low temperature can reach more than 90%.

Description

Transition metal doped molecular sieve and preparation method and application thereof
Technical Field
The invention belongs to the field of gas separation adsorbents, and particularly relates to a transition metal doped molecular sieve, and a preparation method and application thereof.
Background
Global warming has become the most environmental concern at present. CO 2 2 Is a main product of fossil energy combustion and also one of the main sources of greenhouse effect. Statistically, in the past decades, CO has been produced due to the massive combustion of fossil energy 2 The amount of emissions increased at an annual rate of 80%. CH (CH) 4 Is a unit equivalent greenhouse effect ratio CO 2 The more severe greenhouse gas, which causes about 30% environmental stress, while natural gas is also considered as a promising clean energy source for replacing coal and oil, CH 4 Which needs to be recovered as the main component of natural gas. In many cases, the gas mixture often contains a large amount of N 2 And due to molecular size and polarity, CH 4 -N 2 Is also considered to be one of the most difficult systems to separate, and thus N 2 Shadow of (2)The response should also be taken into account in the separation process. For containing CO 2 The traditional industrialized separation method is to adopt amine solution to separate CO in gas 2 Absorption is carried out and then thermal desorption regeneration is carried out on the amine solution. The method can capture a large amount of CO in the raw material gas such as flue gas 2 However, the high energy consumption of the amine solution regeneration process is the biggest problem. The Pressure Swing Adsorption (PSA) technology can perform gas molecule desorption in a temperature-changing or pressure-reducing mode, and can effectively solve the problem of high energy consumption of the traditional method. Among the adsorbents developed at present, molecular sieves, metal organic framework Materials (MOFs) and carbon materials are the most promising adsorbents.
MOFs are three-dimensional networks formed by the crosslinking of metal nodes and organic ligands, and typically have uniform pore sizes ranging from 0.3nm to 2nm (Nature, 2003,423, 705). MOFs can selectively screen CO from gas mixtures when they have pore sizes similar to the molecular size 2 And the like (Angew. Chem. Int. Ed.,2016,55, 10268-10272). However, in many cases, the separated system often contains certain water vapor, for example, flue gas contains 5% -10% of water vapor, and this part of water vapor easily destroys the structure of the MOFs, which affects the separation performance, and if water is removed in advance, the equipment investment is increased.
The carbon molecular sieve is a carbon-based novel adsorbent with certain characteristics of both activated carbon and molecular sieve, and the pore structure of the carbon molecular sieve is mainly microporous, and the pore diameter is distributed between 0.3nm and 1 nm. Carbon molecular sieves have relatively good hydrophobic properties, but are resistant to CO 2 The adsorption capacity of (a) will also be correspondingly lower (ind. Eng. Chem. Res.2008,47, 8048). At the same time, the carbon material tends to be more complex in source and less dense in volume, resulting in greater loading in the adsorbent bed and increased production costs.
The zeolite molecular sieve is in CO 2 The most widely used adsorbent in the trapping process has a basic structure of a ring structure in which regular tetrahedrons centered on Si atoms or Al atoms are connected via oxygen bridges. The largest amount of zeolitic molecular sieves currently used in this process are the 5A molecular sieves and the 13X molecular sieves. Its advantage is high effect on CO 2 Has large adsorption capacity at normal temperature and normal pressureThe adsorption capacity can reach 5mmol/g, but the adsorption capacity to CO is high because partial alkali metal cations are introduced into the framework 2 Tends to be higher, resulting in higher energy consumption for molecular sieve regeneration (ind. Eng. Chem. Res.2006,45,3248, j.am. Chem. Soc.,2005,127, 17998). The RHO molecular sieve is a small-pore molecular sieve which is formed by connecting truncated octahedron or alpha cage through double eight-membered rings, belongs to a body-centered cubic crystal system, and has a main channel composed of eight-membered rings and a channel size
Figure BDA0001393298740000021
I.e. with eight-membered ring orifices, larger cage bins. The pore size of the porous material is just positioned in CO 2
Figure BDA0001393298740000022
N 2
Figure BDA0001393298740000023
And CH 4
Figure BDA0001393298740000024
Therefore, the method is very suitable for the adsorption separation of the gas. The patent US3904738 first reported a method for the synthesis of a small pore RHO molecular sieve with a unique crystal structure and adsorption characteristics, with an SAR value between 5 and 7. Patent CN102439123A adopts the above method to synthesize an RHO molecular sieve and applies it to separation and purification of natural gas. The RHO molecular sieve has the advantages of low SAR value, easy change of a framework structure, temperature, water vapor and CO 2 Sensitivity and the like, and difficult industrial application. In addition, na ions and Cs ions are still introduced into the framework of the RHO molecular sieve, so that the adsorption heat is still higher. In CH 4 -N 2 The above molecular sieve selectively adsorbs N 2 And the adsorption capacity of both is low, because N is contained in raw material gas such as flue gas 2 In a large amount, using the zeolite to selectively adsorb N 2 The problems of raw material gas compression and serious energy consumption in the desorption process of the adsorbent can be brought.
The method can effectively solve the problems by improving the silicon-aluminum ratio of the molecular sieve and reducing alkali metal cationsThe problem of higher energy consumption for desorption and regeneration of the molecular sieve adsorbent is well verified on the SSZ-13 molecular sieve (Langmuir, 2013,29, 832-839). Generally, the introduction of a macromolecular organic templating agent increases the silica to alumina ratio of the molecular sieve (j. Chem. Soc.,1961, 971-982). This is due to the fact that the larger volume of the macromolecular organic species compared to the inorganic ion, the lower overall charge density of the organic-inorganic hybrid species formed, and thus the lower number of negative skeletal charges, i.e., the required Al atoms (one AlO within the molecular sieve) 2 The unit introduces a negative charge). Chatelain et al synthesized a high silica-alumina ratio homogeneous RHO molecular sieve with an SAR value of 9 for the first time using crown ether as an organic template (Microporous mat, 1995,4, 231-238). Wright et al synthesized an RHO molecular sieve with SAR value of 9 using the same method and applied to CO in flue gas 2 Removal, but the RHO molecular sieve was found to neutralize CO 2 The sites of action are predominantly alkali metal cations and the heat of adsorption remains large, leading to difficulties in regeneration (j.am. Chem. Soc.,2012,134,17628-17642, chem. Mater.,2014,26, 2052-2061). Patent CN105452168A synthesizes a RHO molecular sieve with SAR value more than 9.5 by adjusting the composition of hydrogel and applies the RHO molecular sieve to the purification of exhaust gas such as automobile exhaust gas, but the reaction activity of the RHO molecular sieve is still not high below 200 ℃, which shows that Cu in the catalyst 2+ The dispersion mode needs further improvement. Therefore, there is an urgent need for CO with higher Si/Al ratio and lower heat of adsorption 2 -CH 4 -N 2 Selective separation adsorbent, and a nitrogen oxide selective reduction catalyst with higher low-temperature reaction activity.
Disclosure of Invention
The invention aims to provide an RHO molecular sieve for gas separation and tail gas treatment and a preparation method thereof, in particular to a transition metal doped and modified RHO molecular sieve adsorbent capable of efficiently adsorbing CO 2 -CH 4 CO in the System 2 ，CO 2 -N 2 CO in the System 2 And CH 4 -N 2 CH in the system 4 . In addition, the transition metal doped RHO molecular sieve with high silica-alumina ratio synthesized by the synthesis method can effectively remove the waste gas containing nitrogen oxide at low temperature, and is very suitable for being used as tailThe gas treatment aspect is especially a selective reduction catalyst for nitrogen oxide containing exhaust gases.
In order to achieve the purpose, the invention adopts crown ether as a template agent of a hydrothermal system, successfully synthesizes the RHO molecular sieve with high silicon-aluminum ratio and certain transition metal doping amount by optimizing the components of initial gel synthesized by the molecular sieve, doping partial transition metal elements and selecting proper synthesis conditions, and the RHO molecular sieve is used for preferentially adsorbing CO 2 And CH 4 Is very suitable for CO 2 -CH 4 -N 2 The gas system is separated from the adsorbent. In addition, the selective reduction activity of the Cu-doped modified RHO molecular sieve on waste gas containing nitrogen oxide can reach more than 90 percent at low temperature (200 ℃) through further ion exchange, and the Cu-doped modified RHO molecular sieve is very suitable for being used as a selective reduction catalyst of oxynitride.
The invention relates to a transition metal doped molecular sieve, which has RHO molecular sieve configuration identified by International molecular Sieve Institute (IZA), and is determined by nuclear magnetic resonance spectroscopy and inductively coupled plasma spectroscopy, wherein the molar ratio of the chemical components of the molecular sieve is X 2 O 3 ：aYO 2 ：bZO：cM δ O，
Wherein X is a trivalent element; y is a tetravalent element; z is a divalent transition metal element; m is a monovalent or polyvalent cation; a is more than or equal to 10 and less than or equal to 20, b is more than or equal to 0.05 and less than or equal to 0.4, c is more than or equal to 1 and less than or equal to 3, and delta is more than or equal to 0.67 and less than or equal to 2.
And the molecular sieve has characteristic peaks at least in the following 4 interplanar spacings (d) when measured by X-ray diffraction; the first crystal plane spacing d =10.6 ± 0.3, the second crystal plane spacing d =6.1 ± 0.2, and the third crystal plane spacing
d =5.3 ± 0.2, and the fourth interplanar spacing d =4.7 ± 0.2.
The ratio of the oxide of the tetravalent element Y to the oxide of the trivalent element X in the chemical composition of the RHO molecular sieve is preferably 13 to 20.
The ratio of the oxide of the divalent element Z to the oxide of the trivalent element X in the chemical composition of the RHO molecular sieve is preferably not less than 0.1 and not more than 0.4.
The ratio of the oxide of the monovalent or polyvalent element M to the oxide of the trivalent element X in the chemical composition of the RHO molecular sieve is preferably 1. Ltoreq. C.ltoreq.2.
The value of the coordination valence of the monovalent or polyvalent element M and oxygen in the chemical composition of the RHO molecular sieve is preferably 1. Ltoreq. Delta. Ltoreq.2.
Y in the chemical composition is a tetravalent element, including but not limited to one or more of Si, ge and Sn, and is preferably Si;
x in the chemical composition is a trivalent element, including but not limited to one or more of B, al and Ga, preferably Al and B, and most preferably Al;
z in the chemical composition is a divalent transition metal element, including but not limited to one or more of Mg, mn, zn, fe, ni, cr, co and Cu;
m in the chemical composition is a monovalent or polyvalent cation, including but not limited to valence ions of elements such as H, li, na, cs, K, ag, mg, mn, zn, fe, ni, cu, cr, co and the like, and NH 4 + One or more kinds of ions.
Simultaneously relates to a preparation method of the transition metal doped molecular sieve, which comprises the following steps:
carrying out hydrothermal synthesis reaction on raw materials at least containing polybasic crown ether, cesium hydroxide, sodium hydroxide, nitrate, acetate or oxalate of transition metal, a trivalent element compound and a tetravalent element compound to obtain a precursor of the molecular sieve; and removing organic matters in the precursor of the molecular sieve, and introducing univalent or multivalent cations M to prepare the molecular sieve.
The method comprises the following specific steps:
(a) Sequentially adding poly crown ether, sodium hydroxide, cesium hydroxide and deionized water according to the molar ratio of (1.0-2.0) to (0.5-1.5) to (1) (12-30) in a reaction kettle, heating and stirring to fully dissolve and uniformly mix, taking supernatant, and adding the mixture according to the ratio X 2 O 3 ：YO 2 : ZO =1:20-25: adding raw material compounds containing divalent transition metal element Z, trivalent element X and tetravalent element Y in the molecular sieve composition according to the mole ratio of 0.1-0.2, stirring and aging to obtain initial gel, transferring into a reaction kettle, and allowing reaction to proceedAfter hydrothermal synthesis reaction, obtaining a precursor of the molecular sieve of claim 1;
(b) Filtering, washing and drying the molecular sieve precursor after the reaction in the step (a), and then heating and activating to remove organic matters in the molecular sieve precursor to obtain a roasted matrix;
(c) Contacting the calcined substrate obtained in step (b) with a mixture comprising monovalent or polyvalent cations M n+ The solution (2) is mixed according to the mass ratio of 1 (2-10), and the mass concentration of the solution is usually selected to be 10-80%. Ion exchange is carried out on the roasted matrix and the cation solution for 1 to 10 times at the temperature of between 50 and 100 ℃, and the ion exchange time is 1h each time; the ion exchange solution may contain one or two or more of the monovalent or polyvalent cations described in claim 2;
(d) Calcining the ion-exchanged molecular sieve obtained in the step (c) in air at 550 ℃, cooling after calcining, taking out and placing in a drying dish for storage;
(e) If necessary, steps (c) and (d) can be repeated several times to achieve the optimum monovalent or polyvalent cation M n+ The loading, and the type of ion exchanged during the repetition of step (c), may be different.
The polybasic crown ether template adopted by the RHO molecular sieve in the step (a) is a mixture of 18-crown-6 and other crown ethers, wherein the other crown ethers comprise but are not limited to one or a mixture of more of 12-crown-4, 15-crown-5, 18-crown-6 or 24-crown-8. The mass proportion of 18-crown-6 in the crown ether mixture is usually controlled to 50 to 100%, preferably 80 to 95%.
The RHO molecular sieve in the step (a) has a chemical composition in which Y is a tetravalent element, including but not limited to one or more of Si, ge, sn, ti and the like, preferably Si, ti, and more preferably Si.
The raw material containing tetravalent element Y in step (a) includes, but is not limited to, one or a mixture of two or more of oxides, chlorides, sulfides or metal salts of elements such as Si, ge, sn, ti, etc., preferably one or a mixture of several of oxides, silicates and silicates containing tetravalent Si element, and more preferably one or a mixture of several of silica sol, silica gel, active silica and orthosilicates containing tetravalent Si element.
X In the chemical composition of the RHO molecular sieve In the step (a) is a certain trivalent element, including but not limited to one or more of B, al, ga, fe, in and the like, preferably Al and B, and more preferably Al.
The raw material containing the trivalent element X In step (a) includes, but is not limited to, one or a mixture of two or more of oxides, hydroxides, chlorides and metal salts of elements such as B, al, ga, fe, in, preferably one or a mixture of several of simple substances, oxides, hydroxides, chlorides and metal salts of trivalent B and Al elements, more preferably one or a mixture of several of aluminum foil, aluminum salt, activated alumina, activated aluminum hydroxide, aluminum alkoxide, pseudo boehmite, pseudoboehmite or meta-aluminate containing trivalent Al elements.
Z in the chemical composition of the RHO molecular sieve in the step (a) is a certain divalent element, including but not limited to one or more than two transition metal elements of Mg, mn, zn, fe, ni, cr, co, cu and the like, preferably Fe and Cu transition metal elements, and more preferably Cu elements.
The raw material containing the divalent transition metal element Z in the step (a) includes, but is not limited to, one or a mixture of two or more of simple substances, oxides, hydroxides, chlorides and metal salts of transition metal elements such as Mg, mn, zn, fe, ni, cr, co, cu, preferably one or a mixture of several of simple substances, oxides, hydroxides, chlorides and metal salts of divalent Fe and Cu, more preferably one or a mixture of several of copper powder, copper oxide, copper hydroxide, copper chloride, copper nitrate, copper sulfate, copper acetate and copper complex ions containing divalent Cu.
M in the chemical composition of the RHO molecular sieve described in step (d) is a cation, including but not limited to monovalent cations, divalent cations, trivalent cations, and preferably monovalent cations. The source of monovalent cations comprises H + 、Li + 、Na + 、K + 、Cs + 、Ag + Or NH 4 + One or more of oxide, sulfide, hydroxide, chloride, nitrate, sulfate, acetate and oxalate in the ions or a mixture of any more of the oxides, the sulfide, the hydroxide, the chloride, the nitrate, the sulfate, the acetate and the oxalate; the divalent cation source comprises Mg 2+ 、Zn 2+ 、Fe 2+ 、Ni 2+ 、Cu 2+ 、Sr 2+ 、Ca 2+ 、Ba 2+ One or a mixture of any more of oxide, sulfide, hydroxide, chloride, nitrate, sulfate, acetate and oxalate of plasma; said source of trivalent cations comprises Fe 3+ 、Cr 3+ 、Co 3+ One or a mixture of any more of oxides, sulfides, hydroxides, chlorides, nitrates, sulfates, acetates and oxalates in the plasma.
The synthesis method is static heating or rotary heating, preferably rotary heating.
The reaction temperature of the hydrothermal synthesis is 90-300 ℃, preferably 120-250 ℃, and more preferably 140-180 ℃; the reaction time is 48 to 720 hours or more, preferably 72 to 240 hours, more preferably 120 to 144 hours.
The preparation process of the initial gel in step (a) of the present invention is influenced by the dissolution sequence and dissolution conditions. Usually, the polycrown ether is dissolved in water and then mixed with an inorganic base, the water/templating agent molar ratio being selected in the range of 6 to 30, preferably 10 to 20. The mixture was dissolved to some extent at room temperature. The mixing temperature is usually controlled to 50 to 200 deg.C, preferably 60 to 100 deg.C, and more preferably 70 to 90 deg.C. After the aqueous solution of the crown ether and the inorganic base is obtained, taking supernatant liquid and any raw materials of the divalent transition metal element Z, the tetravalent element Y and the trivalent element X in the molecular sieve synthesis raw materials, adding the supernatant liquid and the raw materials into a reaction kettle together, and stirring and aging the mixture to obtain initial gel. The aging time is selected from 12 to 80 hours, preferably 24 to 60 hours; the ageing temperature is selected from 0 to 100 ℃ and preferably from 10 to 60 ℃.
Alternatively, the dissolving sequence of the initial gel is that the polybasic crown ether is dissolved in 1/3 of water, then the inorganic base is added and mixed, the mixing temperature is preferably more than 50 ℃ and less than 100 ℃, the aqueous solution of the crown ether and the inorganic base is obtained, and then the supernatant is taken for standby. Dissolving the trivalent element X and the divalent transition metal element Z in the molecular sieve synthetic raw materials by using the remaining 2/3 of water, adding the obtained supernatant, stirring for 30min, adding the tetravalent element Y in the molecular sieve synthetic raw materials, stirring and aging to obtain initial gel, wherein the aging time is preferably 24-60h, and the aging temperature is preferably 10-60 ℃.
In the hydrothermal synthesis process in the step (a), the initial gel is moved into a pressure-resistant container together with a reaction kettle, and heated by hot air for reaction in a rotary reaction furnace after being screwed down. The synthesis method can select standing heating or rotary heating, and preferably rotary heating. The reaction temperature of the hydrothermal synthesis is 90-300 ℃, preferably 120-250 ℃, and more preferably 140-180 ℃; the reaction time is 48-720 h; preferably 72 to 240 hours, more preferably 96 to 144 hours.
In the filtering, washing and drying process in the step (b), the temperature of the drying process is selected to be 60-200 ℃, preferably 80-100 ℃. The drying time is 12-36h, preferably 12-24h. The dried molecular sieve has adsorption and catalysis performances only by heating and roasting to remove the template agent in the molecular sieve, and the roasting temperature is selected from 400-600 ℃, preferably 500-600 ℃. The calcination time is selected from 0.5 to 24 hours, preferably 1 to 24 hours, more preferably 3 to 6 hours.
The calcined substrate obtained in step (c) is reacted with a catalyst containing monovalent or polyvalent cations M n+ The solution of (a) was as follows 1: (2-10), preferably 1: (5-10), more preferably 1: (8-10) mass ratio; monovalent or polyvalent cations M n+ The mass concentration of the solution is usually 10-80%, preferably 20-50%; the ion exchange times are selected from 1-10 times, preferably 4-6 times; the ion exchange temperature is 50-100 deg.C, preferably 60-90 deg.C, and each ion exchange time is 1h.
The calcination temperature of the ion-exchanged molecular sieve obtained in the step (d) is selected to be 400-800 ℃, and preferably 450-600 ℃; the calcination time is selected from 3 to 12 hours, preferably 5 to 9 hours. The RHO molecular sieve in actual use is in a raw powder state or a molding state after granulation.
The molecular sieve has a RHO molecular sieve configuration identified by International molecular Sieve Association (IZA). The characteristics thereof were confirmed by X-ray diffraction measurement. However, in the actual measurement, the environment of measurement, the direction of crystal growth, the elemental composition in the crystal, the adsorbed substance, and the defects of the crystal are different, and therefore, the position and the peak intensity of each peak actually measured are different from those of each peak specified by IZA.
The light source for X-ray diffraction measurement is not limited to Cu Ka, but Co Ka, mo Ka, ag Ka can also be used as the light source for phase analysis. The starting material morphology tested may be powder, emulsion or solid particles.
The molecular sieve is synthesized by adopting a macromolecular organic template agent, so that a molecular sieve precursor synthesized after the hydrothermal reaction needs to be heated and roasted to remove the macromolecular template agent.
The RHO molecular sieve can be applied to CO-containing 2 And CH 4 CO in the mixed gas 2 And CH 4 Separation of (4). Compared with a silicon-aluminum RHO molecular sieve, the catalyst can preferentially adsorb CO in a large amount 2 。
Alternatively, the RHO molecular sieves can be applied to CO-containing 2 And N 2 CO in the mixed gas 2 And N 2 Can preferentially adsorb CO in large quantities compared with a silicoaluminophosphate RHO molecular sieve 2 。
Alternatively, the RHO molecular sieves may be applied to CH-containing molecules 4 And N 2 Mixed gas of CH 4 And N 2 Compared with a silicoaluminophosphate RHO molecular sieve, the catalyst can preferentially adsorb CH in a large amount 4 。
The RHO molecular sieve adsorption separation gas can be operated at 273-323K, preferably 288-308K.
The RHO molecular sieve can be applied to selective reduction of nitrogen oxides in mixed gas containing nitrogen oxides. Compared with a silicon-aluminum RHO molecular sieve, the selective reduction activity of the silicon-aluminum RHO molecular sieve on the waste gas containing nitrogen oxides at low temperature (200 ℃) can reach more than 90 percent.
The process of selective reduction of nitrogen oxide by RHO molecular sieve can be carried out at the airspeed of 20000h -1 Above, preferably 100000h -1 The following operations are carried out in the following manner,the temperature is usually 100 ℃ or higher, preferably 150 ℃ or higher, usually 700 ℃ or lower, preferably 550 ℃ or lower.
The invention has the advantages that:
(1) The transition metal doped RHO molecular sieve in the invention modulates CO by the pore channel structure 2 -CH 4 -N 2 The system carries out selective adsorption separation, and can avoid the cation pair CO in the framework structure of the traditional low-silica-alumina ratio zeolite molecular sieve 2 The strong adsorption of the molecular sieve reduces the adsorption heat of the molecular sieve, thereby reducing the energy consumption of molecular sieve regeneration.
(2) Compared with a silicon-aluminum RHO molecular sieve, the transition metal doped RHO molecular sieve has the advantages that the change of a pore path structure of the transition metal is not large, but the CO adsorption heat of the molecular sieve can be improved while the CO adsorption of the molecular sieve can be improved by doping part of the transition metal in a framework structure of the molecular sieve 2 And CH 4 Thereby increasing the adsorption separation factor of the molecular sieve.
(3) The transition metal doped RHO molecular sieve can introduce Cu element in the synthesis process, and can obtain the high-silicon RHO molecular sieve with high Cu element dispersion through further Cu ion exchange, and the selective reduction activity of the RHO molecular sieve on waste gas containing nitrogen oxide can reach more than 90% at low temperature (200 ℃).
Drawings
FIG. 1 is a diagram showing the XRD test results of Na, cs-CuRHO-1 in example 1,
FIG. 2 is the adsorption isotherm of H-CuRHO-1 for carbon dioxide, methane and nitrogen at 288K in example 1,
FIG. 3 is the adsorption isotherm of H-CuRHO-1 for carbon dioxide, methane and nitrogen at 298K in example 1,
FIG. 4 is the adsorption isotherm of H-CuRHO-1 for carbon dioxide, methane and nitrogen at 308K in example 1,
FIG. 5 is a diagram showing the XRD test results of Na, cs-MgRHO-1 in example 2,
FIG. 6 is the adsorption isotherm of H-MgRHO-1 at 288K for carbon dioxide, methane and nitrogen in example 2,
FIG. 7 is the adsorption isotherm of H-MgRHO-1 at 298K for carbon dioxide, methane and nitrogen in example 2,
FIG. 8 is the adsorption isotherm of H-MgRHO-1 at 308K for carbon dioxide, methane and nitrogen in example 2,
FIG. 9 is a diagram showing the XRD test results of Na, cs-ZnRHO-1 in example 3,
FIG. 10 is the adsorption isotherm of H-ZnRHO-1 for carbon dioxide, methane and nitrogen at 288K in example 3,
FIG. 11 is the adsorption isotherm of H-ZnRHO-1 for carbon dioxide, methane and nitrogen at 298K in example 3,
FIG. 12 is the adsorption isotherm of H-ZnRHO-1 for carbon dioxide, methane and nitrogen at 308K in example 3,
FIG. 13 is a graphic representation of XRD test results for Na, cs-MnRHO-1 of example 4,
FIG. 14 is the adsorption isotherm of H-MnRHO-1 at 288K for carbon dioxide, methane and nitrogen in example 4,
FIG. 15 is the adsorption isotherm of H-MnRHO-1 at 298K for carbon dioxide, methane and nitrogen in example 4,
FIG. 16 is the adsorption isotherm of H-MnRHO-1 at 308K for carbon dioxide, methane and nitrogen in example 4,
FIG. 17 is a diagram showing the XRD test results of Na, cs-FeRHO-1 in example 5,
FIG. 18 is the adsorption isotherm of H-FeRHO-1 for carbon dioxide, methane and nitrogen at 288K in example 5,
FIG. 19 is the adsorption isotherm of H-FeRHO-1 at 298K for carbon dioxide, methane and nitrogen in example 5,
FIG. 20 is the adsorption isotherm of H-FeRHO-1 at 308K for carbon dioxide, methane and nitrogen in example 5,
FIG. 21 is a graph showing the XRD test results of Na, cs-CoRHO-1 in example 6,
FIG. 22 is the adsorption isotherm of H-CoRHO-1 for carbon dioxide, methane and nitrogen at 288K in example 6,
FIG. 23 is the adsorption isotherm of H-CoRHO-1 for carbon dioxide, methane, and nitrogen at 298K in example 6,
FIG. 24 is the adsorption isotherm of H-CoRHO-1 for carbon dioxide, methane, and nitrogen at 308K in example 6,
FIG. 25 is a diagram showing XRD test results of Na, cs-BRHO-1 in example 7,
FIG. 26 is the adsorption isotherm of H-BRHO-1 for carbon dioxide, methane and nitrogen at 288K in example 7,
FIG. 27 is the adsorption isotherm of H-BRHO-1 at 298K for carbon dioxide, methane and nitrogen in example 7,
FIG. 28 is the adsorption isotherm of H-BRHO-1 for carbon dioxide, methane and nitrogen at 308K in example 7,
FIG. 29 is a graphical representation of the selective reduction catalytic activity of the Cu-exchanged-CuRHO-1 molecular sieve of example 8 on nitrogen oxides before and after hydrothermal aging.
FIG. 30 is a graph showing the results of XRD measurement of Na, cs-RHO-1 in comparative example 1,
FIG. 31 is the adsorption isotherm of H-RHO-1 for carbon dioxide, methane and nitrogen at 288K in comparative example 1,
FIG. 32 is an adsorption isotherm of H-RHO-1 for carbon dioxide, methane, and nitrogen at 298K in comparative example 1,
FIG. 33 is the adsorption isotherm of H-RHO-1 at 308K for carbon dioxide, methane and nitrogen in comparative example 1,
FIG. 34 is a graphical representation of the selective reduction activity of Cu-RHO-1 molecular sieve of comparative example 2 on nitrogen oxides before and after hydrothermal aging.
Detailed Description
The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[ Instrument characterization ]
< X-ray diffraction measurement >
The X-ray diffraction measuring instrument is Panalytical X' Pert PRO, a detection light source Cu Kalpha, the tube voltage is 40kV, the tube current is 40mA, the detection angle range is 5-50 degrees, and the detection time is 10min. The phase structure of the synthesized molecular sieve is determined by X-ray diffraction, ground sample powder is added into a square hole on a glass plate, then the glass plate is inserted into the axial position of an angle measuring instrument, and a probe rotates at the speed of 2 theta/min under the irradiation of a Cu Kalpha light source. The light source is not limited to Cu K α, and Co K α, mo K α, and Ag K α can be used as a light source for phase analysis. The starting material morphology tested may be powder, emulsion or solid particles.
< inductively coupled plasma Spectroscopy >
Inductively coupled plasma spectroscopy (ICP) was performed using a PerkinElmer Optima8x00. The method determines the contents of tetravalent element Y, trivalent element X, divalent element Z and monovalent element or polyvalent cation M in the synthesized molecular sieve by inductively coupled plasma spectroscopy. The concentration gradient absorption curve is made after the standard sample is diluted. The sample is dissolved by hydrofluoric acid and then diluted by water, and then the concentration of each element in the sample is determined by the absorption peak intensity.
< measurement of cell parameters >
The pore parameters are measured by Quantachrome Autosorb-iQ2. The specific surface area and the pore channel parameters of the zeolite molecular sieve are calculated by an Ar adsorption isotherm under 87K. Taking 50mg of a sample, putting the sample into a sample tube, and then putting the sample into 87K solution Ar, wherein the adsorption pressure is 0-760mmHg. All samples were activated at 350 ℃ for more than 6h before adsorption.
< measurement of gas adsorption >
The gas adsorption assay employs Quantachrome Autosorb-iQ2. The present invention tests gas adsorption selectivity by gas adsorption assay. CO 2 2 -CH 4 -N 2 And (3) measuring the adsorption isotherm at 288-308K, putting 1000mg of a sample into a sample tube, and then putting the sample into a 288-308K thermostatic water bath, wherein the adsorption pressure is 0-1bar. All samples were activated at 350 ℃ for more than 6h before adsorption. The adsorption heat of the zeolite molecular sieve to different gases is calculated by the adsorption isotherm data at different temperatures through a Clay-Claus equation.
< evaluation of catalyst Activity >
The prepared zeolite molecular sieve is pressed and molded, and then crushed and sieved to obtain 16-20 mesh particles. The fixed bed was packed with 1ml of the whole zeolite molecular sieve. While heating the zeolite reaction layer, a gas mixture (NO: 500ppm 3 :500ppm,5％O 2 ,10％H 2 O, the balance being N 2 ) At 100000h -1 Space velocity is through the zeolite layer. The nitrogen oxide removal activity (catalytic activity before hydrothermal aging test) of the zeolite sample was evaluated using the value of% NO purification rate ((% inlet NO concentration-outlet NO concentration)/inlet NO concentration) = 100) when the outlet NO concentration was constant at temperatures such as 150 ℃, 175 ℃,200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃.
Further, the zeolite molecular sieve was exposed to an air atmosphere containing 10% by volume of water vapor at 800 ℃ for 10 hours (3000 hours) -1 Space velocity), the removal activity of nitrogen oxides (catalytic activity after hydrothermal aging test) was evaluated in the same manner as described above.
Example 1
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of 4.4g 15-crown ether-5 (the mass percentage of crown ether)>98 percent) is added into 20g of water to be dissolved, and then 2.9g of NaOH (the mass percent of NaOH) is added in turn>96%), 8.0g CsOH (50% >, csOH mass% >>99%) and heating and dissolving for 3h at 80 ℃ to obtain the mixed solution of crown ether and alkali. 0.23g of activated alumina (Al) was taken 2 O 3 99.9 percent of mass percent, 0.1g of Cu (CH) 3 COO) 2 ·H 2 O(Cu(CH 3 COO) 2 ·H 2 O mass percentage content>98%) was dissolved in 6.6g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixture of the crown ether and the base was taken and added to the reaction vessel, and then 8.45g of Ludox AS-40 (SiO) was added to the mixture while stirring 2 40% by mass) and aging at room temperature for 24h to obtain the initial gel. The gel mixture is transferred into a pressure-resistant container and sealed, and is statically crystallized for 144h at the reaction temperature of 140 ℃ and the autogenous pressure. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystals at 100 ℃ for 12h to obtain powdery products Na, cs-CuRHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-CuRHO-1 is shown in a table 1, and a schematic diagram of XRD test results is shown in a figure 1, so that the synthesized molecular sieve has the RHO molecular sieve configuration determined by IZA.
The obtained sample is Na, cs-CuRHO-1Calcining the mixture for 6 hours in a muffle furnace at 600 ℃ to obtain powdery products Na, cs-CuRHO-2. Contacting 5g of the obtained Na, cs-CuRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 -CurHO-1. NH to be obtained subsequently 4 -calcining the powder of the molecular sieve of CuRHO-1 in air: heating to 450 deg.C at 5 deg.C/min, maintaining at 450 deg.C for 10min, further heating to 600 deg.C at 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-CuRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-CuRHO-1 is H ≤6.03 Si 42.48 Al 5.02 Cu 0.50 O 96 The SAR value of the zeolite molecular sieve is 16.9, and the Cu weight percent is 1.1 percent.
The above H-CuRHO-1 is used for CO 2 /CH 4 /N 2 And (5) adsorption separation. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 of Quantachrome. The adsorbed gas is CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the adsorption temperature of the gas by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 2-4 for adsorption isotherms of (a). At 298K under normal pressure, H-CuRHO-1 is to CO 2 、CH 4 And N 2 The amounts of adsorption of (A) were 3.28mmol,0.52mmol and 0.19mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha is alpha (CO2/CH4) ＝47,α (CO2/N2) ＝155,α (CH4/N2) =3.3; H-CuRHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 30.9kJ/mol,20.0kJ/mol, and 21.9kJ/mol, respectively.
TABLE 1 characteristic interplanar spacings of Na, cs-CuRHO-1
Interplanar spacing (d)
1 10.506
2 6.078
3 5.268
4 4.713
5 4.308
6 3.987
7 3.515
8 3.336
Example 2
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of, 2.2g of 15-crown ether-5 (the weight percentage of crown ether)>98%) was dissolved in 14g of water, and then 2.6g of NaOH (NaOH mass hundred) was addedIn parts by weight>96%), 8.0g CsOH (50%; aquous, csOH mass%>99%) and heating and dissolving at 80 deg.C for 3 hr to obtain crown ether and alkali mixture. 0.56g of NaAlO is taken 2 (Al 2 O 3 41 percent of mass percent), 0.14g of Mg (NO) 3 ) 2 ·6H 2 O(Mg(NO 3 ) 2 ·6H 2 O mass percentage content>98%) was dissolved in 6.6g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixture of the crown ether and the alkali was added to the reaction vessel, and 8.45g of Ludox AS-40 (SiO) was added to the mixture while stirring 2 40% by mass) and aging at room temperature for 24h to obtain the initial gel. Transferring the gel mixture into a pressure-resistant container, sealing, and dynamically crystallizing at 150 deg.C under autogenous pressure for 135h. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystal at 100 ℃ for 12h to obtain a powdery product Na, cs-MgRHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-MgRHO-1 is shown in a table 2, and a schematic diagram of XRD test results is shown in a figure 5, which shows that the synthesized molecular sieve has the RHO molecular sieve configuration determined by IZA.
And calcining the obtained sample Na, cs-MgRHO-1 in a muffle furnace at 550 ℃ for 6 hours to obtain a powdery product Na, cs-MgRHO-2. Contacting 5g of the obtained Na, cs-MgRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 -MgRHO-1. NH to be obtained subsequently 4 -calcination of the MgRHO-1 molecular sieve powder in air: heating to 450 deg.C at a rate of 5 deg.C/min, maintaining at 450 deg.C for 10min, heating to 600 deg.C at a rate of 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-MgRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-MgRHO-1 is H ≤7.05 Si 41.39 Al 6.17 Mg 0.44 O 96 The SAR value of the zeolite molecular sieve is 13.4, wherein the Mg wt% is 0.37%.
The above H-MgRHO-1 is used for CO 2 /CH 4 /N 2 And (5) adsorbing and separating. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 from Quantachrome. The adsorbed gas is CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the temperature of gas adsorption by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 6-8 for adsorption isotherms of (a). 298K at normal pressure, H-MgRHO-1 to CO 2 、CH 4 And N 2 The amounts of adsorption of (A) were 4.48mmol,0.76mmol and 0.27mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha is alpha (CO2/CH4) ＝36,α (CO2/N2) ＝126,α (CH4/N2) =3.5; H-MgRHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 31.4kJ/mol,23.1kJ/mol, and 20.7kJ/mol, respectively.
TABLE 2 characteristic interplanar spacings of Na, cs-MgRHO-1
Interplanar spacing (d)
1 10.505
2 6.078
3 5.265
4 4.714
5 4.306
6 3.990
7 3.517
8 3.337
Example 3
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of 2.6g of 15-crown-5 (the mass percentage of crown ether is)>98 percent) is added into 20g of water to be dissolved, and then 2.9g of NaOH (the mass percent of NaOH) is added in turn>96%), 7.0g CsOH (50% >, csOH mass%>99%) and heating and dissolving at 80 deg.C for 3 hr to obtain crown ether and alkali mixture. 0.56g of NaAlO is taken 2 (Al 2 O 3 41 percent of mass percent) and 0.1g of Zn (CH) 3 COO) 2 (Zn(CH 3 COO) 2 Mass percentage of>99.5%) was dissolved in 6.6g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixed solution of the crown ether and the alkali was taken and added to the reaction vessel, and then 3.4g of active Silica (SiO) was added to the mixture while stirring 2 99.9% by mass), and aging at room temperature for 24h to obtain an initial gel. Transferring the gel mixture into a pressure-resistant container, sealing, and dynamically crystallizing at 160 ℃ under autogenous pressure for 120h. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystal at 100 ℃ for 12h to obtain powdery products Na, cs-ZnRHO-1. XRD of the obtained productThe phase analysis shows that the interplanar spacing of characteristic peaks in Na, cs-ZnRHO-1 is shown in Table 3, the schematic diagram of XRD test results is shown in FIG. 9, and the synthesized molecular sieve has the RHO molecular sieve configuration identified by IZA.
And calcining the obtained sample Na, cs-ZnRHO-1 in a muffle furnace at 550 ℃ for 6 hours to obtain a powdery product Na, cs-ZnRHO-2. Contacting 5g of the obtained Na, cs-ZnRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 -ZnRHO-1. NH to be obtained subsequently 4 -calcining ZnRHO-1 molecular sieve powder in air: heating to 450 ℃ at the speed of 5 ℃/min, maintaining at 450 ℃ for 10min, then continuing to heat to 600 ℃ at the speed of 2 ℃/min, then maintaining at 600 ℃ for 5H, and then cooling to 100 ℃ to obtain H-ZnRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-ZnRHO-1 is H ≤6.83 Si 41.99 Al 5.19 Zn 0.82 O 96 The SAR value of the zeolite molecular sieve is 16.2, and the Zn wt% is 1.8%.
The above H-ZnRHO-1 is used for CO 2 /CH 4 /N 2 And (5) adsorption separation. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 of Quantachrome. The adsorbed gas is CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the temperature of gas adsorption by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 10-12 for adsorption isotherms of (a). At 298K under normal pressure, H-ZnRHO-1 is to CO 2 、CH 4 And N 2 Was 3.95mmol,0.61mmol and 0.19mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha (alpha) ("alpha") (CO2/CH4) ＝35,α (CO2/N2) ＝119,α (CH4/N2) =3.4; H-ZnRHO-1 to CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 31.1kJ/mol,21.3kJ/mol and 22.4kJ/mol, respectively.
TABLE 3 characteristic interplanar spacings of Na, cs-ZnRHO-1
Interplanar spacing (d)
1 10.522
2 6.081
3 5.271
4 4.714
5 4.304
6 3.986
7 3.516
8 3.337
Example 4
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of the total weight of the components, 3.0g of 15-crown ether-5 (the mass percentage of the crown ether)>98 percent) is added into 20g of water for dissolution, and then 2.0g of NaOH (the mass percentage of NaOH is added in turn>96%), 8.0g CsOH (50% >, csOH mass% >>99%) and heating and dissolving at 80 deg.C for 3 hr to obtain crown ether and alkali mixture. 0.56g of NaAlO is taken 2 (Al 2 O 3 41% by mass, 0.12g Mn (CH) 3 COO) 2 (Mn(CH 3 COO) 2 Mass percentage of>99.0%) was dissolved in 6.6g of water and transferred to a reaction vessel, 9.0g of the supernatant of the mixed solution of the crown ether and the alkali was added to the reaction vessel, and then 8.6g of tetramethyl orthosilicate (99.0% by mass) was added to the mixture while stirring, and aged at room temperature for 24 hours to obtain an initial gel. Transferring the gel mixture into a pressure-resistant container, sealing, and statically crystallizing at the reaction temperature of 180 ℃ under the autogenous pressure for 96 hours. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystal at 100 ℃ for 12h to obtain a powdery product Na, cs-MnRHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-MnRHO-1 is shown in a table 4, a schematic diagram of XRD test results is shown in a figure 13, and the synthesized molecular sieve has the RHO molecular sieve configuration determined by IZA.
And calcining the obtained sample Na, cs-MnRHO-1 in a muffle furnace at 550 ℃ for 6 hours to obtain a powdery product Na, cs-MnRHO-2. Contacting 5g of the obtained Na, cs-MnRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, 1h each time, filtering and drying between each contact to obtain NH 4 -MnRHO-1. NH to be obtained subsequently 4 -calcining MnRHO-1 molecular sieve powder in air: heating to 450 deg.C at a rate of 5 deg.C/min, maintaining at 450 deg.C for 10min, further heating to 600 deg.C at a rate of 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-MnRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-MnRHO-1 is H ≤6 .61Si 41.65 Al 6.10 Mn 0.26 O 96 The zeolite molecular sieve had an SAR value of 13.7 and an Mn wt% of 0.49.
The above H-MnRHO-1 is used for CO 2 /CH 4 /N 2 And (5) adsorption separation. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 from Quantachrome. The adsorbed gas being CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the temperature of gas adsorption by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 14-16 for adsorption isotherms of (a). At 298K, under normal pressure, H-MnRHO-1 is added to CO 2 、CH 4 And N 2 The amounts of adsorption of (A) were 3.89mmol,0.65mmol and 0.23mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha (alpha) ("alpha") (CO2/CH4) ＝37,α (CO2/N2) ＝133,α (CH4/N2) =3.6; H-MnRHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 30.2kJ/mol,20.1kJ/mol, and 20.0kJ/mol, respectively.
TABLE 4 characteristic interplanar spacings of Na, cs-MnRHO-1
Figure BDA0001393298740000211
Figure BDA0001393298740000221
Example 5
28.3g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of 15-crown ether-5, 5.6g (the mass percentage of crown ether)>98%) of the above-mentioned raw materials were dissolved in 28g of water, and then 2.9g of NaOH (NaOH in mass percent) was added thereto>96％)，8.0g CsOH (50%; aquous; mass% CsOH)>99%) and heating and dissolving for 3h at 80 ℃ to obtain the mixed solution of crown ether and alkali. 0.35g of activated aluminum hydroxide (Al) was taken 2 O 3 66% by mass), 0.1g Fe (COO) 2 ·2H 2 O(Fe(COO) 2 ·2H 2 O mass percentage content>99.0%) was dissolved in 6.6g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixed solution of the crown ether and the alkali was added to the reaction vessel, and 8.45g of Ludox AS-40 (SiO) was added to the mixture while stirring 2 40% by mass) and aging at room temperature for 24h to obtain the initial gel. The gel mixture is transferred into a pressure-resistant container and sealed, and dynamic crystallization is carried out for 144h at the reaction temperature of 140 ℃ and the autogenous pressure. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystals at 100 ℃ for 12h to obtain powdery products Na, cs-FeRHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-FeRHO-1 is shown in Table 5, the schematic diagram of the XRD test result is shown in figure 17, and the synthesized molecular sieve has the RHO molecular sieve configuration identified by IZA.
And calcining the obtained sample Na, cs-FeRHO-1 in a muffle furnace at 450 ℃ for 4 hours to obtain a powdery product Na, cs-FeRHO-2. Contacting 5g of the obtained Na, cs-FeRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 -MnRHO-1. NH to be obtained subsequently 4 -calcination of the FeRHO-1 molecular sieve powder in air: heating to 450 deg.C at 5 deg.C/min, maintaining at 450 deg.C for 10min, heating to 600 deg.C at 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-FeRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-FeRHO-1 is H ≤7.19 Si 41.32 Al 6.15 Fe 0.52 O 96 The SAR value of the zeolite molecular sieve is 13.4, and the Fe wt% is 1.01%.
Use of the above H-FeRHO-1 for CO 2 /CH 4 /N 2 And (5) adsorbing and separating. Adsorption isotherm of the sampleThe measurement was carried out on an Autosorb-iQ2 from Quantachrome. The adsorbed gas is CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the adsorption temperature of the gas by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 18-20 for adsorption isotherms of (a). 298K at normal pressure, H-FeRHO-1 to CO 2 、CH 4 And N 2 The amounts of adsorption of (A) were 4.28mmol,0.71mmol and 0.23mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha is alpha (CO2/CH4) ＝38,α (CO2/N2) ＝122,α (CH4/N2) =3.2; H-FeRHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 30.9kJ/mol,19.3kJ/mol, and 20.4kJ/mol, respectively.
TABLE 5 characteristic interplanar spacings of Na, cs-FeRHO-1
Figure BDA0001393298740000231
Figure BDA0001393298740000241
Example 6
14.5g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent of the total weight of the components, 3.0g of 15-crown ether-5 (the weight percentage of the crown ether)>98 percent) is added into 11g of water to be dissolved, and then 2.9g of NaOH (the mass percent of NaOH) is added in turn>96%), 8.0g CsOH (50% >, csOH mass% >>99%) and heating and dissolving at 80 deg.C for 3 hr to obtain crown ether and alkali mixture. 0.93g of aluminum isopropoxide (Al) was taken 2 O 3 25% by mass), 0.15g Co (NO) 3 ) 2 ·6H 2 O(Co(NO 3 ) 2 ·6H 2 O mass percentage content>98.5%) was dissolved in 6.6g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixture of the crown ether and the base was taken and added to the reaction vessel, and then 8.45g of Ludox AS-40 (SiO) was added to the mixture while stirring 2 40% by mass) and aging at room temperature for 24h to obtain the initial gel. Transferring the gel mixture into a pressure-resistant container, sealing, and dynamically crystallizing at 180 deg.C under autogenous pressure for 96h. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. The obtained crystals were dried at 100 ℃ for 12 hours to obtain a powdery product Na, cs-CoRHO-1. The obtained product is analyzed by XRD as phase, the interplanar spacing of the characteristic peak in Na, cs-CoRHO-1 is shown in Table 6, the schematic diagram of XRD test result is shown in figure 21, which shows that the synthesized molecular sieve has RHO molecular sieve configuration determined by IZA.
And calcining the obtained sample Na, cs-CoRHO-1 in a muffle furnace at 500 ℃ for 6 hours to obtain powdery products Na, cs-CoRHO-2. Contacting 5g of the obtained Na, cs-CoRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 -CoRHO-1. NH to be obtained subsequently 4 -calcination of the powder of the molecular sieve CoRHO-1 in air: heating to 450 ℃ at the speed of 5 ℃/min, maintaining at 450 ℃ for 10min, then continuing to heat to 600 ℃ at the speed of 2 ℃/min, then maintaining at 600 ℃ for 5H, and then cooling to 100 ℃ to obtain H-CoRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-CoRHO-1 is H ≤6.86 Si 41.74 Al 5.68 Co 0.59 O 96 The SAR value of the zeolite molecular sieve is 14.7, and the Co wt% is 1.20%.
Use of the above H-CoRHO-1 for CO 2 /CH 4 /N 2 And (5) adsorption separation. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 of Quantachrome. The adsorbed gas being CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). To avoid the effect of physically adsorbed water in the molecular sieve on the adsorption results, the samples were tested in Autosorb-iQ2 is subjected to dehydration treatment, and heated to 100 deg.C at 3 deg.C/min under extremely low vacuum (below 0.005 mmHg), maintained at 100 deg.C for 30min, and then further heated to 350 deg.C at 3 deg.C/min, and maintained at 350 deg.C for 6h. Controlling the adsorption temperature of the gas by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 22-24 for adsorption isotherms of (a). At 298K, under normal pressure, H-CoRHO-1 is added to CO 2 、CH 4 And N 2 Were adsorbed in amounts of 3.95mmol,0.65mmol and 0.24mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha is alpha (CO2/CH4) ＝38,α (CO2/N2) ＝122,α (CH4/N2) =3.2; H-CoRHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 30.2kJ/mol,20.7kJ/mol, and 22.1kJ/mol, respectively.
TABLE 6 characteristic interplanar spacings of Na, cs-FeRHO-1
Figure BDA0001393298740000251
Figure BDA0001393298740000261
Example 7
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98 percent) is added into 20g of water to be dissolved, and then 2.6g of NaOH (the mass percent of NaOH) is added in turn>96%), 7.0g CsOH (50% >, csOH mass%>99%) and heating and dissolving for 3h at 80 ℃ to obtain the mixed solution of crown ether and alkali. 0.47g of NaAlO was taken 2 (Al 2 O 3 41 percent of mass percent) of NaBO 0.26g 2 ·4H 2 O(NaBO 2 ·4H 2 O mass percentage content>99%) was dissolved in 6.4g of water, transferred to a reaction vessel, 9.0g of the supernatant of the mixture of the crown ether and the alkali was taken and added to the reaction vessel, and then 12g of tetraethyl orthosilicate (SiO) was added to the mixture while stirring 2 Mass percentage of>28.4%) at room temperatureAfter aging for 24h, an initial gel was obtained. The gel mixture is transferred into a pressure-resistant container and sealed, and dynamic crystallization is carried out for 144h at the reaction temperature of 140 ℃ and the autogenous pressure. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystals at 100 ℃ for 12h to obtain powdery products Na, cs-BRHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-BRHO-1 is shown in a table 7, and a schematic diagram of XRD test results is shown in a figure 25, which shows that the synthesized molecular sieve has the RHO molecular sieve configuration identified by IZA.
And calcining the obtained samples Na and Cs-BRHO-1 in a muffle furnace at 400 ℃ for 3h to obtain powdery products Na and Cs-BRHO-2. Contacting 5g of the obtained Na, cs-BRHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, 1h each time, filtering and drying between each contact to obtain NH 4 -BRHO-1. NH to be obtained subsequently 4 -calcining BRHO-1 molecular sieve powder in air: heating to 450 deg.C at a rate of 5 deg.C/min, maintaining at 450 deg.C for 10min, heating to 600 deg.C at a rate of 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-BRHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-BRHO-1 is H ≤5.83 Si 42.17 Al 5.07 B 0.76 O 96 The SAR value of the zeolite molecular sieve is 16.6, and the B wt% is 0.29%.
The above H-BRHO-1 is used for CO 2 /CH 4 /N 2 And (5) adsorbing and separating. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 of Quantachrome. The adsorbed gas being CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. Controlling the temperature of gas adsorption by constant temperature water bath (precision 0.01 ℃), wherein the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 26-28 for adsorption isotherms of (a). 298K at normal pressure, H-BRHO-1 to CO 2 、CH 4 And N 2 The amounts of adsorption of (A) were 4.07mmol,0.67mmol and 0.22mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha (alpha) ("alpha") (CO2/CH4) ＝32,α (CO2/N2) ＝109,α (CH4/N2) =3.4; H-BRHO-1 to CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 30.5kJ/mol,21.1kJ/mol,21.5kJ/mol, respectively.
TABLE 7 characteristic interplanar spacings of Na, cs-BRHO-1
Interplanar spacing (d)
1 10.356
2 6.026
3 5.228
4 4.680
5 4.275
6 3.960
7 3.496
8 3.317
Example 8
1g of Cu (CH) 3 COO) 2 ·H 2 O(Cu(CH 3 COO) 2 ·H 2 O mass percentage content>98%) was dissolved in 15g of water to obtain a copper (II) acetate solution. NH in example 1 4 Molecular sieve of-CuRHO-1 zeolite was dispersed in the above copper (II) acetate solution and ion-exchanged at 60 ℃ for 2 hours. The zeolite molecular sieve was recovered by filtration and washed three times with deionized water. The above ion exchange and washing process was then repeated 2 times. The obtained zeolite molecular sieve was dried at 100 ℃ for 12 hours and then calcined in air at 550 ℃ for 1 hour, thereby obtaining a Cu ion-exchanged zeolite molecular sieve Cu-exchanged-CuRHO-1. The sample is subjected to element composition analysis by ICP, and the analysis result shows that the Cu content in the zeolite molecular sieve is 3.6%. The BET specific surface area of the zeolite molecular sieve Cu-exchanged-CuRHO-1 was determined to be 909m 2 (ii) in terms of/g. The zeolite molecular sieve was exposed to an air atmosphere containing 10% by volume of water vapor at 800 ℃ for 10 hours (3000 hours) -1 Space velocity), the BET specific surface area was measured and reduced to 836m 2 (iv) g. The selective reduction catalytic activity of the zeolite molecular sieve Cu-exchanged-CuRHO-1 on nitrogen oxides before and after hydrothermal aging is researched, and an activity curve is shown in figure 29.
Comparative example 1
21.2g of 18-crown ether-6 (the mass percentage of crown ether)>98%) of the above-mentioned raw materials were dissolved in 14g of water, and then 2.9g of NaOH (NaOH in mass percent) was added thereto>96%), 8.0g CsOH (50%; aquous, csOH mass%>99%) and heating and dissolving for 3h at 80 ℃ to obtain the mixed solution of crown ether and alkali. 0.56g of NaAlO is taken 2 (Al 2 O 3 41 percent of mass content) is dissolved in 6.6g of water and then transferred to a reaction kettle, and 9.0g of mixed solution of the crown ether and the alkali is takenThe supernatant was added to a reaction vessel, and then 8.45g of Ludox AS-40 (SiO) was added to the above mixture while stirring 2 40% by mass) and aging at room temperature for 24h to obtain the initial gel. The gel mixture is transferred into a pressure-resistant container and sealed, and dynamic crystallization is carried out for 144h at the reaction temperature of 140 ℃ and the autogenous pressure. And after the hydrothermal reaction is finished, cooling, filtering and washing the reaction liquid to obtain a crystallized product. Drying the obtained crystals at 100 ℃ for 12h to obtain powdery products Na, cs-RHO-1. The obtained product is subjected to phase analysis by XRD, the interplanar spacing of the characteristic peak in Na, cs-RHO-1 is shown in a table 8, a schematic diagram of XRD test results is shown in a figure 30, and the synthesized molecular sieve has the RHO molecular sieve configuration identified by IZA.
And calcining the obtained sample Na, cs-RHO-1 in a muffle furnace at 550 ℃ for 6 hours to obtain a powdery product Na, cs-RHO-2. Contacting 5g of the obtained Na, cs-RHO-2 with 6mol/L ammonium chloride solution (5 ml/g molecular sieve) at 80 ℃ for 4 times, each time for 1h, filtering and drying between each contact to obtain NH 4 RHO-1. NH to be obtained subsequently 4 -calcination of the RHO-1 molecular sieve powder in air: heating to 450 deg.C at a rate of 5 deg.C/min, maintaining at 450 deg.C for 10min, heating to 600 deg.C at a rate of 2 deg.C/min, maintaining at 600 deg.C for 5H, and cooling to 100 deg.C to obtain H-RHO-1. The dried sample was taken out and stored in a drying dish. ICP is adopted to carry out element composition analysis on the samples, and the analysis result shows that the chemical element composition of H-RHO-1 is H ≤5.2 Si 42.8 Al 5.2 O 96 The SAR value of the zeolite molecular sieve is 17.2.
Use of the above H-RHO-1 for CO 2 /CH 4 /N 2 And (5) adsorbing and separating. The adsorption isotherm of the sample was measured on an Autosorb-iQ2 of Quantachrome. The adsorbed gas being CO 2 (99.99％)、CH 4 (99.99％)、N 2 (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption result, the sample is dehydrated in the Autosorb-iQ2, heated to 100 ℃ at the rate of 3 ℃/min under the extremely low vacuum degree (below 0.005 mmHg), maintained at 100 ℃ for 30min, then continuously heated to 350 ℃ at the rate of 3 ℃/min, and maintained at 350 ℃ for 6h. With constant temperature water bath (essence)The temperature is 0.01 ℃) to control the temperature of gas adsorption, the adsorption temperature is 288-308K 2 、CH 4 And N 2 See fig. 31-33 for adsorption isotherms of (a). At 298K under normal pressure, H-RHO-1 is to CO 2 、CH 4 And N 2 Was 3.45mmol,0.57mmol and 0.19mmol, respectively, from which CO was calculated 2 /CH 4 、CO 2 /N 2 And CH 4 the/N2 adsorption selectivity is respectively as follows: alpha is alpha (CO2/CH4) ＝27,α (CO2/N2) ＝100,α (CH4/N2) =3.7; H-RHO-1 vs. CO 2 、CH 4 And N 2 The heat of adsorption of (a) was 29.4kJ/mol,24.0kJ/mol, and 24.5kJ/mol, respectively.
TABLE 8 characteristic interplanar spacings of Na, cs-RHO-1
Interplanar spacing (d)
1 10.532
2 6.084
3 5.270
4 4.716
5 4.305
6 3.986
7 3.517
8 3.337
Comparative example 2
1g of Cu (CH) 3 COO) 2 ·H 2 O(Cu(CH 3 COO) 2 ·H 2 O mass percentage content>98%) was dissolved in 15g of water to obtain a copper (II) acetate solution. NH in comparative example 1 4 -RHO-1 zeolite molecular sieve was dispersed in the above copper (II) acetate solution and ion-exchanged at 60 ℃ for 2 hours. The zeolite molecular sieve was recovered by filtration and washed three times with deionized water. The above ion exchange and washing process was then repeated 2 times. The obtained zeolite molecular sieve was dried at 100 ℃ for 12 hours and then calcined in air at 550 ℃ for 1 hour, thereby obtaining a Cu ion-exchanged zeolite molecular sieve Cu-RHO-1. The sample is subjected to element composition analysis by ICP, and the analysis result shows that the Cu content in the zeolite molecular sieve is 3.5%. The BET specific surface area of the zeolite molecular sieve Cu-RHO-1 was measured to be 803m 2 (iv) g. The zeolite molecular sieve was exposed to an air atmosphere containing 10% by volume of water vapor at 800 ℃ for 10 hours (3000 hours) -1 Space velocity), the BET specific surface area was measured and reduced to 705m 2 (iv) g. The selective reduction catalytic activity of the zeolite molecular sieve Cu-RHO-1 on nitrogen oxides before and after hydrothermal aging is researched, and an activity curve is shown in figure 34.

Claims (7)

1. A preparation method of a transition metal doped molecular sieve is characterized by comprising the following steps: the molecular sieve has RHO molecular sieve configuration, and comprises the following chemical composition X in a molar ratio determined by nuclear magnetic resonance spectroscopy and inductively coupled plasma spectroscopy 2 O 3 ：aYO 2 ：bZO：cM δ O，
X is a trivalent element; y isA tetravalent element; z is a divalent transition metal element; m is univalent or multivalent cation, a is more than or equal to 10 and less than or equal to 20, b is more than or equal to 0.05 and less than or equal to 0.4, c is more than or equal to 1 and less than or equal to 3, delta is more than or equal to 0.67 and less than or equal to 2, the trivalent element is aluminum, the tetravalent element is silicon, the divalent transition metal elements are Mg, mn, zn, fe, co and Cu, and the univalent or multivalent cation is H + 、Cu 2+ ；
And the molecular sieve has characteristic peaks at least in the following 4 interplanar spacings (d) when measured by X-ray diffraction; the first interplanar spacing d =10.6 ± 0.3, the second interplanar spacing d =6.1 ± 0.2, the third interplanar spacing d =5.3 ± 0.2, the fourth interplanar spacing d =4.7 ± 0.2;
the preparation method comprises the following steps:
carrying out hydrothermal synthesis reaction on raw materials at least containing polybasic crown ether, cesium hydroxide, sodium hydroxide, nitrate, acetate or oxalate of transition metal, and a trivalent element compound and a tetravalent element compound to obtain a precursor of the molecular sieve; removing organic matters in the precursor of the molecular sieve, and introducing univalent or multivalent element cations M to prepare the molecular sieve;
the method comprises the following specific steps:
(a) Sequentially adding polybasic crown ether, sodium hydroxide, cesium hydroxide and deionized water into a reaction kettle according to the molar ratio of (1.0-2.0) to (0.5-1.5) to (12-30), heating and stirring to fully dissolve and uniformly mix, taking supernatant, and adding the supernatant according to X 2 O 3 ： YO 2 : ZO =1:20-25: adding raw material compounds containing a divalent transition metal element Z, a trivalent element X and a tetravalent element Y in the molecular sieve composition into the molecular sieve composition according to the oxide molar ratio of 0.1-0.2, stirring and aging to obtain initial gel, transferring the initial gel into a reaction kettle, and carrying out hydrothermal synthesis reaction to obtain a precursor of the molecular sieve;
(b) Filtering, washing and drying the molecular sieve precursor after the reaction in the step (a) is finished, and then heating and activating to remove organic matters in the molecular sieve precursor to obtain a roasting matrix;
(c) Mixing the roasted matrix obtained in the step (b) with a cation solution according to the mass ratio of 1 (2-10), wherein the mass concentration of the solution is selected to be 10-80%; ion exchange is carried out on the roasted matrix and the cation solution for 1 to 10 times at the temperature of between 50 and 100 ℃, and the ion exchange time is 1h each time; the cation solution is ammonium chloride or copper acetate;
(d) Roasting the ion-exchanged molecular sieve obtained in the step (c) in air at 400-600 ℃ for 3-6h, cooling after roasting is finished, taking out and placing in a drying dish for storage;
(e) If necessary, steps (c) and (d) can be repeated several times to achieve the optimal monovalent or multivalent cation loading, and the elements are different in the repeated implementation of step (c).
2. The method of claim 1, wherein the transition metal-doped molecular sieve is prepared by: the polybasic crown ether is a mixture of 18-crown-6 and other crown ethers, and the other crown ethers comprise one or a mixture of more of 12-crown-4, 15-crown-5, 18-crown-6 or 24-crown-8; the mass ratio of the 18-crown ether-6 in the crown ether mixture is 50 to 100 percent.
3. The method of claim 1, wherein the transition metal-doped molecular sieve is prepared by: the synthesis method is static heating or rotary heating.
4. The method of claim 1, wherein the transition metal-doped molecular sieve is prepared by: the reaction temperature of the hydrothermal synthesis is 90-300 ℃, and the reaction time is 48-720 h.
5. The method of claim 1, wherein the transition metal-doped molecular sieve is prepared by: the synthesis method comprises rotary heating; the reaction temperature of the hydrothermal synthesis is 120-250 ℃, and the reaction time is 72-240h.
6. Use of a transition metal doped molecular sieve according to claim 1, wherein: the molecular sieve is applied to the separation of carbon dioxide and methane in a mixed gas containing carbon dioxide and methane, the separation of carbon dioxide and nitrogen in a mixed gas containing carbon dioxide and nitrogen and the separation of methane and nitrogen in a mixed gas containing methane and nitrogen.
7. Use of a transition metal doped molecular sieve according to claim 1, wherein: the molecular sieve is used as a molecular sieve catalyst for tail gas treatment, and the selective reduction activity of the molecular sieve on waste gas containing nitrogen oxides at 200 ℃ can reach more than 90%.
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