阅读说明：本技术 一种耐高温高活性Cu基SCR催化剂及其制备方法 (High-temperature-resistant high-activity Cu-based SCR catalyst and preparation method thereof ) 是由 朱增赞 汪银环 赵磊 冯峰 孙敏 任衍伦 徐欢 陈令伍 郭晓会 王菊 于 2019-07-17 设计创作，主要内容包括：本发明提供一种耐高温高活性Cu基SCR催化剂及其制备方法,包括制备高分散纳米Cu溶液；制备Cu-分子筛原位浸渍液；使用原位浸渍法制备Cu基SCR催化剂。本方法通过离子半径与铜离子相差30％以内的金属盐对Cu分子筛SCR掺杂,通过优化配制工艺、配比,形成固溶体系,不仅解决了Cu(Ⅱ)离子迁移问题,抑制副产物N<Sub>2</Sub>O生成,提高N<Sub>2</Sub>的选择性,而且增强了催化剂酸性位强度,提高催化剂的NH3存储能力,拓宽了催化剂的催化活性窗口,满足国VI排放标准要求。与现有技术相比,本发明制备方法简单,生产成本低,重复性强,容易实现过程控制,能很好地满足实际应用要求。(The invention provides a high-temperature-resistant high-activity Cu-based SCR catalyst and a preparation method thereof, which comprises the steps of preparing a high-dispersion nano Cu solution; preparing Cu-molecular sieve in-situ impregnation liquid; the Cu-based SCR catalyst was prepared using an in situ impregnation method. The method forms a solid solution system by doping the Cu molecular sieve SCR through metal salt with the difference of the ionic radius and the copper ion being within 30 percent and optimizing the preparation process and the proportion, thereby not only solving the problem of Cu (II) ion migration, but also inhibiting the byproduct N 2 O production, increase N 2 The selectivity of the catalyst is enhanced, the acid site strength of the catalyst is enhanced, the NH3 storage capacity of the catalyst is improved, the catalytic activity window of the catalyst is widened, and the national VI emission standard requirement is met. Compared with the prior art, the preparation method is simple, low in production cost, strong in repeatability, easy to realize process control and capable of well meeting the requirementAnd (5) the practical application requirement.)

1. A preparation method of a high-temperature-resistant high-activity Cu-based SCR catalyst is characterized by comprising the following steps: comprises the following steps

S1: preparing a high-dispersion nano Cu solution;

s2: preparing Cu-molecular sieve in-situ impregnation liquid;

s3: the Cu-based SCR catalyst was prepared using an in situ impregnation method.

2. The method for preparing the Cu-based SCR catalyst with high temperature resistance and high activity according to claim 1, wherein the step S1 comprises:

s101: adding a nano Cu source into deionized water, preparing a 0.5-10% solution, and stirring for 10-60 min;

s102: adding the copper source dispersant according to the molar ratio of the copper source dispersant to Cu of 0.1-9, and stirring for 10-60 min;

s103: adding a metal salt M solution according to the molar ratio of the metal M to the Cu of 0.1-2, and stirring for 10-60 min;

s104: adjusting the pH value to 3-6, and stirring for 30-60 minutes.

3. The method for preparing the Cu-based SCR catalyst with high temperature resistance and high activity according to claim 2, wherein the step S2 comprises:

s201: weighing molecular sieve powder according to the mass ratio of Cu to the molecular sieve of 0.01-0.06, adding the molecular sieve powder into the high-dispersion nano Cu solution at the speed of 5-10g/min, keeping the uniform stirring state, and stirring for 60-120min until the molecular sieve is completely dispersed;

s202: adding the nonionic surfactant according to the molar ratio of the nonionic surfactant to Cu of 0.0001-0.1, and stirring for 60-120 min;

s203: introducing the prepared slurry into a sand mill, sanding for 5-50min, and grinding to obtain a particle size D902-16 μm;

s204: adjusting the pH value of the solution to 3-6 and the solid content to 32-44%, and continuing stirring for 10-60 min.

4. The method for preparing the high temperature resistant and high activity Cu-based SCR catalyst according to claim 3, wherein the step S3 comprises:

s301: adding the thickening agent according to the mass ratio of the thickening agent to the molecular sieve of 0.005-0.1, adjusting the viscosity to 500-2500cp, and continuing stirring for 10-60 min;

s302: coating the catalyst, wherein the coating amount is 60-250 g/L;

s303: rapidly drying at 80-200 deg.C for 20-60min, heating to 400-650 deg.C at a temperature rising rate of 1-10 deg.C/min, and calcining for 1-6 h.

5. The method for preparing the high-temperature-resistant high-activity Cu-based SCR catalyst as recited in claim 4, wherein the nano Cu source is nano Cu particles, and the precursor of the nano Cu source is one or more of copper nitrate, copper acetate, copper sulfate and copper chloride.

6. The preparation method of the high-temperature-resistant high-activity Cu-based SCR catalyst as recited in claim 5, wherein the copper source dispersant is one or more of saccharides, alcohols or esters.

7. The method for preparing the high-temperature-resistant high-activity Cu-based SCR catalyst as recited in claim 6, wherein M is one or more of Y, Ti, Zr, Hf, Co, Cr, Nb and Ni.

8. The method for preparing the high-temperature-resistant high-activity Cu-based SCR catalyst as recited in claim 7, wherein the non-ionic surfactant is one or more of acetylene glycol, alkyl glucoside, isopropanol, fatty glyceride, fatty sorbitan fatty acid, and polysorbate.

9. The method for preparing the high-temperature-resistant high-activity Cu-based SCR catalyst as recited in claim 8, wherein the thickener is one or more of CMC, HPMC, HEC, xanthan gum, silica sol and alumina sol.

10. A high-temperature-resistant high-activity Cu-based SCR catalyst, which is prepared by the preparation method of any one of claims 1 to 9;

in the Cu-based SCR catalyst, the mass fraction of Cu is 0.1-2.0%, the mass fraction of metal M is 0.01-4.0%, the mass fraction of a molecular sieve is 15-45%, and the balance is a cordierite ceramic carrier.

Technical Field

The invention belongs to the field of catalysts and preparation methods thereof, and particularly relates to a high-temperature-resistant high-activity Cu-based SCR catalyst and a preparation method thereof.

Background

NH3 selective catalytic reduction is one of the most effective diesel vehicle tail gas NOx purification technologies recognized at present, and efficient, stable and environment-friendly NH is developed₃SCR catalysts are a common target for the current automobile exhaust aftertreatment enterprises and various large research institutes. Cu-based molecular sieve catalyst due to its broader NH₃SCR window of reactivity and excellent N₂Selectivity, is of great concern.

The existing Cu molecular sieve SCR catalyst technology for purifying NOx of diesel vehicles has many problems, the catalytic activity of the catalyst is mainly expressed in a low-medium temperature region, and the catalytic activity of a high-temperature region needs to be improved. The method of supporting Cu is generally an impregnation method. The impregnation method is simple, the steps are easy to operate, the process control is easy to realize, the repeatability is strong, the production period is short, and the method is more suitable for production amplification. However, Cu (II) ions exchanged with the molecular sieve framework of the Cu molecular sieve SCR catalyst prepared by the impregnation method are easy to migrate out of the pore channels and are oxidized into CuO on the surface of the catalyst, and the CuO promotes the generation of N2O and NO2, thereby reducing the N-to-N ratio₂Selectivity of (2). Therefore, the key point that the technology can be widely applied is to improve the high-temperature catalytic activity of the Cu molecular sieve SCR catalyst and inhibit Cu ion migration.

Disclosure of Invention

In order to solve the problem that Cu (II) ions exchanged with a molecular sieve framework are easy to migrate out of a pore channel and oxidized into CuO on the surface of a catalyst in the Cu molecular sieve SCR catalyst in the prior art, the CuO can promote the generation of N2O and NO2, thereby reducing the generation of nitrogen and nitrogen in the Cu molecular sieve SCR catalystTo N₂The invention provides a high-temperature-resistant high-activity Cu-based SCR catalyst and a preparation method thereof. The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of such embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

The invention adopts the following technical scheme:

in some optional embodiments, a preparation method of the high-temperature-resistant high-activity Cu-based SCR catalyst comprises the following steps

S1: preparing a high-dispersion nano Cu solution;

s2: preparing Cu-molecular sieve in-situ impregnation liquid;

s3: the Cu-based SCR catalyst was prepared using an in situ impregnation method.

Wherein, the step S1 includes:

s101: adding a nano Cu source into deionized water, preparing a 0.5-10% solution, and stirring for 10-60 min;

s102: adding the copper source dispersant according to the molar ratio of the copper source dispersant to Cu of 0.1-9, and stirring for 10-60 min;

s103: adding a metal salt M solution according to the molar ratio of the metal M to the Cu of 0.1-2, and stirring for 10-60 min;

s104: adjusting the pH value to 3-6, and stirring for 30-60 minutes.

Wherein, the step S2 includes:

s201: weighing molecular sieve powder according to the mass ratio of Cu to the molecular sieve of 0.01-0.06, adding the molecular sieve powder into the high-dispersion nano Cu solution at the speed of 5-10g/min, keeping the uniform stirring state, and stirring for 60-120min until the molecular sieve is completely dispersed;

s202: adding the nonionic surfactant according to the molar ratio of the nonionic surfactant to Cu of 0.0001-0.1, and stirring for 60-120 min;

s203: introducing the prepared slurry into a sand mill, sanding for 5-50min, and grinding to obtain a particle size D902-16 μm;

s204: adjusting the pH value of the solution to 3-6 and the solid content to 32-44%, and continuing stirring for 10-60 min.

Wherein, the step S3 includes:

s301: adding the thickening agent according to the mass ratio of the thickening agent to the molecular sieve of 0.005-0.1, adjusting the viscosity to 500-2500cp, and continuing stirring for 10-60 min.

S302: coating the catalyst, wherein the coating amount is 60-250 g/L;

s303: rapidly drying at 80-200 deg.C for 20-60min, heating to 400-650 deg.C at a temperature rising rate of 1-10 deg.C/min, and calcining for 1-6 h.

Wherein the nano Cu source is nano Cu particles, and the precursor of the nano Cu source is one or more of copper nitrate, copper acetate, copper sulfate and copper chloride.

Wherein the copper source dispersant is one or more of saccharides, alcohols or esters.

Wherein, M is one or more of Y, Ti, Zr, Hf, Co, Cr, Nb and Ni.

Wherein the nonionic surfactant is one or more of alkynediol, alkyl glucoside, isopropanol, fatty glyceride, fatty sorbitan and polysorbate.

Wherein the thickener is one or more of CMC, HPMC, HEC, xanthan gum, silica sol and aluminum sol.

A high temperature resistant high activity Cu-based SCR catalyst is prepared by the preparation method;

in the Cu-based SCR catalyst, the mass fraction of Cu is 0.1-2.0%, the mass fraction of metal M is 0.01-4.0%, the mass fraction of a molecular sieve is 15-45%, and the balance is a cordierite ceramic carrier.

The invention has the following beneficial effects: the method forms a solid solution system by doping the Cu molecular sieve SCR through metal salt with the difference of the ionic radius and the copper ion being within 30 percent and optimizing the preparation process and the proportion, thereby not only solving the problem of Cu (II) ion migration, but also inhibiting the byproduct N₂O production, increase N₂The selectivity of the catalyst is enhanced, the acid site strength of the catalyst is enhanced, the NH3 storage capacity of the catalyst is improved, and the catalyst is widenedThe catalytic activity window of the catalyst meets the requirements of national VI emission standards. Compared with the prior art, the preparation method is simple, low in production cost, strong in repeatability, easy to realize process control and capable of well meeting the requirements of practical application.

For the purposes of the foregoing and related ends, the one or more embodiments include the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and are indicative of but a few of the various ways in which the principles of the various embodiments may be employed. Other benefits and novel features will become apparent from the following detailed description when considered in conjunction with the drawings and the disclosed embodiments are intended to include all such aspects and their equivalents.

Drawings

FIG. 1 is a graph comparing the catalytic performance of Cu/Zr/SSZ-13, a molecular sieve catalyst prepared in example 1, and Cu/SSZ-13, a catalyst without metal doping in comparative example 1, having the same copper content.

FIG. 2 shows the N content of Cu/Zr/SSZ-13, a molecular sieve catalyst prepared in example 1, and Cu/SSZ-13, a catalyst obtained in comparative example 1 without metal doping and having the same copper content, in the SCR reaction process₂Graph comparing the amount of O produced.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in or substituted for those of others. The scope of embodiments of the invention encompasses the full ambit of the claims, as well as all available equivalents of the claims.

In some illustrative embodiments, a method for preparing a high temperature resistant and high activity Cu-based SCR catalyst comprises the following steps

S1: preparing a high-dispersion nano Cu solution;

s101: adding a nano Cu source into deionized water, preparing a 0.5-10% solution, and stirring for 10-60 min; the nano Cu source is nano Cu particles, and the precursor of the nano Cu source is one or more of copper nitrate, copper acetate, copper sulfate and copper chloride.

S102: adding the copper source dispersant according to the molar ratio of the copper source dispersant to Cu of 0.1-9, and stirring for 10-60 min; the copper source dispersant is one or more of saccharides, alcohols or esters. The saccharide is sucrose, maltose, fructose, dextran, etc. The alcohol is polyvinyl alcohol, polyethylene glycol, glycerol, etc. The esters are ethyl acetate, butyl acetate, etc.

S103: adding a metal salt M solution according to the molar ratio of the metal M to the Cu of 0.1-2, and stirring for 10-60 min; and M is one or more of Y, Ti, Zr, Hf, Co, Cr, Nb and Ni.

S104: adjusting the pH value to 3-6, and stirring for 30-60 minutes.

S2: preparing Cu-molecular sieve in-situ impregnation liquid;

s201: weighing molecular sieve powder according to the mass ratio of Cu to the molecular sieve of 0.01-0.06, adding the molecular sieve powder into the high-dispersion nano Cu solution at the speed of 5-10g/min, keeping the uniform stirring state, and stirring for 60-120min until the molecular sieve is completely dispersed; the molecular sieve comprises a silicon-aluminum molecular sieve SSZ-13, SSZ-39, a silicon-aluminum molecular sieve BETA, a silicon-aluminum molecular sieve ZSM-5 and a silicon-aluminum-phosphorus molecular sieve SAPO-34.

S202: adding the nonionic surfactant according to the molar ratio of the nonionic surfactant to Cu of 0.0001-0.1, and stirring for 60-120 min; the nonionic surfactant is one or more selected from alkyne diol, alkyl glucoside, isopropanol, fatty glyceride, fatty sorbitan and polysorbate.

S203: introducing the prepared slurry into a sand mill, sanding for 5-50min, and grinding to obtain a particle size D902-16 μm;

s204: adjusting the pH value of the solution to 3-6 and the solid content to 32-44%, and continuing stirring for 10-60 min.

S3: preparing a Cu-based SCR catalyst by using an in-situ impregnation method;

s301: adding the thickening agent according to the mass ratio of the thickening agent to the molecular sieve of 0.005-0.1, adjusting the viscosity to 500-2500cp, and continuing stirring for 10-60 min. The thickener is one or more of CMC, HPMC, HEC, xanthan gum, silica sol and alumina sol.

S302: coating the catalyst, wherein the coating amount is 60-250 g/L; the coating method comprises the following steps: dip coating, dip-and-pull coating, quantitative coating, negative pressure extraction coating, high pressure spray coating, and the like.

S303: rapidly drying at 80-200 deg.C for 20-60min, heating to 400-650 deg.C at a temperature rising rate of 1-10 deg.C/min, and calcining for 1-6 h.

A high temperature resistant high activity Cu-based SCR catalyst is prepared by the preparation method;

in the Cu-based SCR catalyst, the mass fraction of Cu is 0.1-2.0%, the mass fraction of metal M is 0.01-4.0%, the mass fraction of a molecular sieve is 15-45%, and the balance is a cordierite ceramic carrier. The method is suitable for purifying nitrogen oxides in automobile exhaust, and is also suitable for denitration of waste gas of a thermal power plant and denitration of ship exhaust.

Comparative example 1:

preparation of highly dispersed Nano Cu solution

a. Weighing 15.0g of nano Cu solution, adding into 600.0g of deionized water, and stirring for 20 min.

b. 30.0g of sucrose was added and stirred for 30 min.

c. Adjusting the pH value of the solution to 3.0, and stirring for 30 min.

Preparing in-situ impregnating solution of Cu-molecular sieve

a. Weighing 500g of SSZ-13 molecular sieve powder, slowly adding the powder into the high-dispersion nano Cu solution at the speed of 10g/min, keeping the uniform stirring state, and stirring for 90min until the molecular sieve is completely dispersed.

b. 0.8g of acetylenic diol was added and stirred for 60 min.

c. And (3) introducing the prepared slurry into a sand mill, sanding for 40min, and grinding to obtain the particle size D9013.5 mu m.

d. The pH value of the solution is adjusted to 5.8, the solid content is 38%, and the stirring is continued for 30 min.

Preparing a Cu-based SCR catalyst by using an in-situ impregnation method;

a. adding 2.5g CMC, adjusting viscosity to 700cp, and continuing stirring for 60 min.

b. The catalyst is coated by adopting a dipping and pulling method, and the coating amount is controlled at 150 g/L.

c, quickly drying at 120 ℃ for 40min, heating to 550 ℃ at the heating rate of 5 ℃/min, and roasting for 2 h.