阅读说明：本技术 去除氮氧化物的分子筛催化剂制备方法 (Preparation method of molecular sieve catalyst for removing nitrogen oxides ) 是由 施文杰 金炜阳 王刚 周钧 陈加伟 胡嘉宁 岳军 贾莉伟 于 2019-06-25 设计创作，主要内容包括：本发明涉及一种去除氮氧化物的分子筛催化剂制备方法,它包括以下步骤：配制氢型分子筛浆液；向氢型分子筛浆液中加入氢型分子筛重量0.2%~1%的硅溶胶并搅拌均匀,得到混合浆液；向前步骤的混合浆液中加入金属盐并搅拌均匀,其中,金属盐的加入量为其中的金属元素重量占氢型分子筛重量的0.7%~4.5%；将前步骤的混合浆液放入微波马弗炉中升温至200~350℃并恒温煅烧0.5~1.5h,即得到分子筛催化剂。本发明的方法步骤简单、制备时间短、过程可控、操作性强且不会产生废水。通过本发明得到的产品活性组分可控、金属分散度较高。(the invention relates to a preparation method of a molecular sieve catalyst for removing nitrogen oxides, which comprises the following steps of preparing hydrogen type molecular sieve slurry, adding silica sol accounting for 0.2 to ~ 1 percent of the weight of a hydrogen type molecular sieve into the hydrogen type molecular sieve slurry, uniformly stirring to obtain mixed slurry, adding metal salt into the mixed slurry obtained in the previous step, uniformly stirring, wherein the adding amount of the metal salt is that the weight of metal elements accounts for 0.7 to ~ 4.5.5 percent of the weight of the hydrogen type molecular sieve, placing the mixed slurry obtained in the previous step into a microwave muffle furnace, heating to 200 ~ 350 ℃, and calcining at constant temperature for 0.5 to 0.5 ~ 1.5.5 hours to obtain the molecular sieve catalyst.)

1. A method for preparing molecular sieve catalyst for removing nitrogen oxides is characterized by comprising the following steps

a. Preparing hydrogen type molecular sieve slurry;

b. Adding cured substances in silica sol accounting for 0.2 percent to ~ 1 percent of the weight of the hydrogen molecular sieve into the hydrogen molecular sieve slurry, and uniformly stirring to obtain mixed slurry, wherein the cured substance content of the silica sol is 15 percent to ~ 40 percent;

c. adding metal salt into the mixed slurry obtained in the step b and uniformly stirring, wherein the adding amount of the metal salt is ~ 4.5.5% of the weight of metal elements in the mixed slurry accounting for 0.7% of the weight of the hydrogen type molecular sieve;

d. And c, putting the mixed slurry obtained in the step c into a microwave muffle furnace, heating to 200 ~ 350 ℃, and calcining at constant temperature for 0.5 ~ 1.5.5 h to obtain the molecular sieve catalyst.

2. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 1, which is characterized in that: the metal in the metal salt is one or more of Cu, Fe, Co, Ni, Ce, Ag and Mn.

3. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the copper salt in the metal salt is one or two of copper nitrate, copper acetate, copper chloride and copper sulfate.

4. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the iron salt in the metal salt is one or two of ferric nitrate, ferric chloride and ferric sulfate.

5. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the cobalt salt in the metal salt is one or two of cobalt chloride and cobalt sulfate.

6. the method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the nickel salt in the metal salt is one or two of nickel nitrate and nickel acetate.

7. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the cerium salt in the metal salt is one or two of cerium nitrate and cerium acetate.

8. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the silver salt in the metal salt is silver nitrate.

9. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 2, which comprises: the manganese salt in the metal salt is one or two of manganese nitrate and manganese acetate.

10. The method for preparing a molecular sieve catalyst for removing nitrogen oxides according to claim 1, which is characterized in that: the hydrogen-type molecular sieve material is one or more of BEA, CHA, MFI, LTA, AEI, AFX and FAU.

Technical Field

the invention relates to a preparation method of a molecular sieve catalyst for removing nitrogen oxides, belonging to the technical field of catalyst preparation.

Background

With the development of technology, transition metal-loaded molecular sieve catalysts are emerging as a new generation of leading-edge material for removing NOx in NH ₃ -SCR due to their high activity, selectivity and good stability.

the traditional method for introducing metals into molecular sieves is mainly an ion exchange method, namely, under hydrothermal stirring, adding the molecular sieves and metal salts into an aqueous solution, carrying out solid-liquid separation, washing and drying after exchange for several hours, and repeating the steps for many times in order to obtain the metals with high load capacity. The method has the advantages of uncontrollable metal loading, low dispersion uniformity of metal in the molecular sieve, complex working procedures, long process time and large amount of waste water generation.

Compared with the traditional method, the microwave heating promotes the exchange reaction and improves the exchange degree. The process of ion exchange reaction is generally affected by diffusion process, ions generally exist in the form of hydrated ions in solution, and the larger the radius of the hydrated ions, the slower the migration speed. The water molecules rotate at a high speed under the action of microwaves and are converted into translational energy of the molecules through intermolecular interaction, so that necessary energy is provided for the hydrated ions to overcome dehydration barriers; in addition, under the induction of the central ions, dipoles of bonded water molecules in the hydrated ions are enhanced, and the absorption of microwaves is correspondingly enhanced, so that stronger rotation and vibration are generated, the original ordered arrangement is instantaneously destroyed, the hydrated ions are partially dehydrated, and then the hydrated ions quickly and smoothly enter the pore channels of the zeolite molecular sieve. The naked ion not only accelerates the exchange speed, but also promotes the exchange to occur in the deeper part of the pore channel, so that the total exchange degree is improved.

disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method of a molecular sieve catalyst for removing nitrogen oxides, which is simple in method, short in preparation time, controllable in process, strong in operability and free of wastewater.

According to the technical scheme provided by the invention, the preparation method of the molecular sieve catalyst for removing the nitrogen oxides comprises the following steps

a. Preparing hydrogen type molecular sieve slurry;

b. Adding cured substances in silica sol accounting for 0.2 percent to ~ 1 percent of the weight of the hydrogen molecular sieve into the hydrogen molecular sieve slurry, and uniformly stirring to obtain mixed slurry, wherein the cured substance content of the silica sol is 15 percent to ~ 40 percent;

c. Adding metal salt into the mixed slurry obtained in the step b and uniformly stirring, wherein the adding amount of the metal salt is ~ 4.5.5% of the weight of metal elements in the mixed slurry accounting for 0.7% of the weight of the hydrogen type molecular sieve;

d. And c, placing the mixed slurry obtained in the step c into a microwave muffle furnace, heating to 200 ~ 350 ℃, and calcining at constant temperature for 0.5 ~ 1.5.5 h to obtain the molecular sieve catalyst, wherein the frequency of the microwave is 300MHz ~ 300 GHz.

The metal in the metal salt is one or more of Cu, Fe, Co, Ni, Ce, Ag and Mn.

The copper salt in the metal salt is one or two of copper nitrate, copper acetate, copper chloride and copper sulfate.

the iron salt in the metal salt is one or two of ferric nitrate, ferric chloride and ferric sulfate.

The cobalt salt in the metal salt is one or two of cobalt chloride and cobalt sulfate.

The nickel salt in the metal salt is one or two of nickel nitrate and nickel acetate.

The cerium salt in the metal salt is one or two of cerium nitrate and cerium acetate.

the silver salt in the metal salt is silver nitrate.

the manganese salt in the metal salt is one or two of manganese nitrate and manganese acetate.

the hydrogen-type molecular sieve material is one or more of BEA, CHA, MFI, LTA, AEI, AFX and FAU.

The cured product content of the silica sol was 15% ~ 40%.

The method has the advantages of simple steps, short preparation time, controllable process, strong operability and no generation of wastewater. The product obtained by the method has controllable active components and higher metal dispersion degree.

Drawings

FIG. 1 is a graph comparing NOx conversion efficiency under steady state conditions after aging for example 2 and comparative example 1.

FIG. 2 is a graph comparing NO conversion efficiency under transient conditions after aging for example 5 and comparative example 2.

Detailed Description

The present invention will be further described with reference to the following specific examples.