阅读说明：本技术 一种原位水热合成Fe-SSZ-13分子筛的方法 (Method for in-situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve ) 是由 刘春红 郑渭建 胡晨晖 卓佐西 杜凯敏 祁志福 陈亮 林贻超 于 2020-06-12 设计创作，主要内容包括：本发明涉及一种原位水热合成Fe-SSZ-13分子筛的方法,包括：步骤1、制备Fe的络合物：将二价Fe金属盐加入到有机胺中进行络合反应2～6h,形成Fe的络合物；步骤2、制备反应混合物；步骤3、在结晶条件下在180～220℃下加热步骤2.2所得陈化后的反应混合物12～72h直至形成Fe-SSZ-13粗产物。本发明的有益效果是：本发明为一步法制备Fe-SSZ-13,相比于传统通过二步法离子交换制备Fe-SSZ-13的方法,制备工序简单；由于不会产生大量的废水,成本也更低,更加简单高效；所得Fe-SSZ-13分子筛催化剂经过酸洗处理后具有优异的水热稳定性、耐酸碱性；Fe-SSZ-13分子筛可应用于选择性催化还原(NH<Sub>3</Sub>-SCR)发动机、化工厂等尾气中的氮氧化物。(The invention relates to a method for in-situ hydrothermal synthesis of a Fe-SSZ-13 molecular sieve, which comprises the following steps: step 1, preparation of a complex of Fe: adding divalent Fe metal salt into organic amine to perform a complex reaction for 2-6 h to form a Fe complex; step 2, preparing a reaction mixture; and 3, heating the aged reaction mixture obtained in the step 2.2 at 180-220 ℃ for 12-72 h under the crystallization condition until a crude product of Fe-SSZ-13 is formed. The invention has the beneficial effects that: the invention is a one-step method for preparing Fe-SSZ-13, compared with the traditional method for preparing Fe-SSZ-13 by ion exchange through a two-step method, the preparation process is simple; because a large amount of waste water is not generated, the cost is lower, and the method is simpler and more efficient; the obtained Fe-SSZ-13 molecular sieve catalyst has excellent hydrothermal stability and acid and alkali resistance after acid washing treatment; Fe-SSZ-13 molecular sieve can be appliedIn selective catalytic reduction (NH) 3 SCR) of nitrogen oxides in exhaust gases of engines, chemical plants, etc.)

1. The method for in-situ hydrothermal synthesis of the Fe-SSZ-13 molecular sieve is characterized by comprising the following steps:

step 1, preparation of a complex of Fe: adding divalent Fe metal salt into organic amine to perform a complex reaction for 2-6 h to form a Fe complex;

step 2, preparing a reaction mixture:

step 2.1, adding an inorganic base and a trivalent aluminum source into the Fe complex, adding N, N, N-trimethyl-1-amantadine after completely dissolving, uniformly stirring, and finally dropwise adding a tetravalent silicon source to obtain a reaction mixture;

step 2.2, aging the mixture obtained in the step 2.1 for a certain time under the condition of stirring;

step 3, heating the aged reaction mixture obtained in the step 2.2 at 180-220 ℃ for 12-72 h under the crystallization condition until a crude product of Fe-SSZ-13 is formed;

step 4, placing the Fe-SSZ-13 crude product prepared in the step 3 in a specific atmosphere, and roasting at 500-700 ℃ for 6-12 h to remove a template agent, so as to obtain a Fe-SSZ-13 molecular sieve; the temperature rise rate of the roasting is 1-5 ℃/min.

2. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: in the step 1, the divalent Fe metal salt is ferrous nitrate and hydrate thereof, ferrous acetate and hydrate thereof, ferrous sulfate and hydrate thereof or ferrous chloride and hydrate thereof; the organic amine is triethylene diamine or tetraethylenepentamine.

3. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: in the step 1, the time for carrying out the complex reaction of the divalent Fe metal salt and the organic amine is 2 hours.

4. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: the trivalent aluminum source in the step 2.1 is at least one of aluminum hydroxide, aluminum oxide, aluminum isopropoxide and sodium metaaluminate; the inorganic base is sodium hydroxide.

5. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: the aging time in the step 2.2 is 5-20 h.

6. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: the temperature of the reaction mixture after heating and aging in the step 3 is 200 ℃, and the heating time is 72 h.

7. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: in the step 4, the roasting temperature is 550 ℃, the roasting time is 6h, and the heating rate of roasting is 5 ℃/min.

8. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: the specific atmosphere in step 4 is air.

9. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: the molar ratio of the trivalent aluminum source to the tetravalent silicon source in the step 2.1 is 0.01-0.10; the molar ratio of the hydroxyl ions to the tetravalent silicon source is 0.2-0.6; the molar ratio of the organic base to the tetravalent silicon source is 0.05-0.2; the molar ratio of the N, N, N-trimethyl-1-amantadine cation to the tetravalent silicon source is 0.08-0.2.

10. The method for in situ hydrothermal synthesis of Fe-SSZ-13 molecular sieve according to claim 1, characterized in that: and 2.1, both the complex of Fe and the N, N, N-trimethyl-1-amantadine are used as template agents, and the Fe complex is simultaneously used as an Fe source for synthesizing the Fe-SSZ-13 molecular sieve.

Technical Field

The invention relates to a preparation method for synthesizing a Fe-SSZ-13 molecular sieve in situ by one step. The Fe-SSZ-13 molecular sieve can be applied to selective catalytic reduction (NH)₃SCR) of nitrogen oxides in exhaust gases of engines, chemical plants, etc.

Background

The molecular sieve material is a crystalline porous material with regular pore channels and a high specific surface, the framework structure mainly comprises aggregates of silicon-aluminum oxide which are connected through oxygen bridges to form a regular pore structure and a cavity system, and the pore size is mainly 0.3-2.0 nm. Molecular sieve materials have wide industrial application in the fields of ion exchange, adsorption separation, catalysis and the like due to unique physical and chemical properties, and become indispensable important materials in the chemical field. For convenience of research and exchange, The International Zeolite Association (IZA) classifies molecular sieves according to their framework topologies, such as CHA, MFI, FAU, VFI, and The like. For example, the current hot spot molecular sieve material SSZ-13 has the CHA topology, which is formed by AlO₄And SiO₄The tetrahedron are connected end to end through oxygen atoms and are orderly arranged into an ellipsoidal cage (0.73nm × 1.2.2 nm) with an eight-membered ring structure and a three-dimensional cross pore channel structure, the pore channel size is 0.37nm × 0.42.42 nm SSZ-13 has the characteristics of ordered pore channel, good hydrothermal stability, more surface proton acid centers, exchangeable cations and the like, and the SSZ-13 molecular sieve after divalent Fe ions or divalent Cu ions are exchanged is an excellent Selective Catalytic Reduction (SCR) catalyst, and NO is not contained in the catalyst_xThe removal rate can reach 80-90%. The current research result shows that the work of the Cu-SSZ-13 molecular sieve catalystThe temperature window is generally 200-400 ℃, and the working temperature window of the Fe-SSZ-13 molecular sieve catalyst is generally 300-550 ℃. Compared with the Cu-SSZ-13 molecular sieve, the Fe-SSZ-13 molecular sieve has better SCR performance at high temperature.

The synthesis method of SSZ-13 is disclosed in the US patent document US 4544538 of 1982 for the first time, and the method needs to use expensive N, N, N-trimethyl-1-amantadine cation template agent, thus increasing the synthesis cost of the SSZ-13 molecular sieve and greatly limiting the popularization and application of the SSZ-13 molecular sieve. And the preparation of the SSZ-13 molecular sieve with the SCR activity also needs ion exchange, thereby further increasing the working procedure and the cost.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for synthesizing a Fe-SSZ-13 molecular sieve by in-situ hydrothermal synthesis.

The method for in-situ hydrothermal synthesis of the Fe-SSZ-13 molecular sieve comprises the following steps:

step 1, preparation of a complex of Fe: adding divalent Fe metal salt into organic amine to perform a complex reaction for 2-6 h to form a Fe complex;

step 2, preparing a reaction mixture:

step 2.1, adding an inorganic base and a trivalent aluminum source into the Fe complex, adding N, N, N-trimethyl-1-amantadine after completely dissolving, uniformly stirring, and finally dropwise adding a tetravalent silicon source to obtain a reaction mixture;

step 2.2, aging the mixture obtained in the step 2.1 for a certain time under the condition of stirring;

step 3, heating the aged reaction mixture obtained in the step 2.2 at 180-220 ℃ for 12-72 h under the crystallization condition until a crude product of Fe-SSZ-13 is formed;

step 4, placing the Fe-SSZ-13 crude product prepared in the step 3 in a specific atmosphere, and roasting at 500-700 ℃ for 6-12 h to remove a template agent, so as to obtain a Fe-SSZ-13 molecular sieve; the temperature rise rate of the roasting is 1-5 ℃/min.

Preferably, in the step 1, the divalent Fe metal salt is ferrous nitrate and its hydrate, ferrous acetate and its hydrate, ferrous sulfate and its hydrate or ferrous chloride and its hydrate (ferrous sulfate and its hydrate have better performance); the organic amine is triethylene diamine or tetraethylene pentamine (the performance of the tetraethylene pentamine is better).

Preferably, the time for the complexing reaction of the divalent Fe metal salt and the organic amine in the step 1 is 2 hours.

Preferably, the trivalent aluminum source in the step 2.1 is at least one of aluminum hydroxide, aluminum oxide, aluminum isopropoxide and sodium metaaluminate; preferably aluminum isopropoxide and sodium metaaluminate, more preferably sodium metaaluminate; the inorganic base is sodium hydroxide.

Preferably, the aging time in the step 2.2 is 5-20 h.

Preferably, the temperature of the reaction mixture after heat aging in the step 3 is 200 ℃, and the heating time is 72 h.

Preferably, in the step 4, the roasting temperature is 550 ℃, the roasting time is 6 hours, and the heating rate of the roasting is 5 ℃/m in.

Preferably, the specific atmosphere in step 4 is air.

Preferably, the molar ratio of the trivalent aluminum source to the tetravalent silicon source in the step 2.1 is in a range of 0.01 to 0.10; the molar ratio of the hydroxyl ions to the tetravalent silicon source is 0.2-0.6; the molar ratio of the organic base to the tetravalent silicon source is 0.05-0.2; the molar ratio of the N, N, N-trimethyl-1-amantadine cation to the tetravalent silicon source is 0.08-0.2.

Preferably, the Fe complex and the N, N, N-trimethyl-1-amantadine in the step 2.1 both serve as template agents, and the Fe complex simultaneously serves as an Fe source for synthesizing the Fe-SSZ-13 molecular sieve.

The invention has the beneficial effects that: the invention is a one-step method for preparing Fe-SSZ-13, compared with the traditional method for preparing Fe-SSZ-13 by ion exchange through a two-step method, the preparation process is simple; because a large amount of waste water is not generated, the cost is lower, and the method is simpler and more efficient; the obtained Fe-SSZ-13 molecular sieve catalyst has excellent hydrothermal stability and acid and alkali resistance after acid washing treatment; f e-SSZ-13 molecular sieve can be applied to selective catalytic reduction (NH)₃SCR) of nitrogen oxides in exhaust gases of engines, chemical plants, etcA compound (I) is provided.

Drawings

FIG. 1 is a powder XRD pattern of Fe-SSZ-13 molecular sieves prepared in examples 1 to 3 of the present invention;

FIG. 2 is an SEM picture of a Fe-SSZ-13 molecular sieve prepared in example 1 of the present invention;

FIG. 3 is a diagram showing the denitration performance test results of the Fe-SSZ-13 molecular sieve prepared in example 1 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for a person skilled in the art, several modifications can be made to the invention without departing from the principle of the invention, and these modifications and modifications also fall within the protection scope of the claims of the present invention.