CN116139861A - Catalyst applicable to storage reduction of nitrogen oxides of gas turbine as well as preparation and application thereof - Google Patents

Abstract

The invention discloses a catalyst suitable for nitrogen oxide storage reduction of a gas turbine, a preparation method and application thereof. In the catalyst, ag-M/CeO ₂ Is a core, the surface of which is coated with amorphous TiO ₂ A layer; ag-M/CeO ₂ Representing CeO ₂ Surface loading Ag, ag ₂ Oxides of O and of the acidic auxiliaries M; the acid assistant M is at least one of W, sb, mo, nb. The preparation method comprises the following steps: ceO is added with ₂ Dispersing the silver nitrate and the precursor of the acid auxiliary agent M in deionized water, uniformly mixing, drying and roasting to obtain Ag-M/CeO ₂ The method comprises the steps of carrying out a first treatment on the surface of the Dissolving tetrabutyl titanate in ethanol to obtain solution A, mixing nitric acid with deionized water and ethanol to obtain solution B, and adding solution A into solution B under stirring to obtain TiO ₂ Sol; ag-M/CeO ₂ Added to TiO ₂ In the sol, stirring continuously, aging and roasting to obtain Ag-M/CeO suitable for the storage reduction of nitrogen oxides of gas turbines ₂ @TiO ₂ A catalyst.

Description

Catalyst suitable for storage and reduction of nitrogen oxides in gas turbines and its preparation and application

technical field

The invention relates to the technical field of nitrogen oxide reduction in gas turbines, in particular to a catalyst suitable for storage and reduction of nitrogen oxides in gas turbines and its preparation method and application.

Background technique

Due to the optimization and adjustment of China's energy structure, the scale of gas-fired power plants continues to expand, and the problem of nitrogen oxide (NO _x ) emissions is becoming increasingly serious.

The difference in power demand between day and night and the instability of new energy power generation require frequent peak shaving of the power grid, and gas turbines (hereinafter referred to as "gas turbines") have the characteristics of rapid start and stop, so they undertake the task of peak shaving of the power grid. However, the frequent start and stop of the gas turbine is likely to cause excessive NO _x emissions and "yellow smoke" (high NO ₂ /NO _x ) of the exhaust gas. Compared with NO, NO ₂ is more toxic and can cause diseases such as bronchitis and even lung cancer in humans and animals, as well as serious disasters such as photochemical smog and acid rain. Therefore, how to solve the problem of yellow smoke at the start-up stage of the gas turbine has become the focus of NO _x control in gas-fired power plants in China.

The denitrification catalyst is the key to the terminal treatment of gas flue gas NO _x . Selective Catalytic Reduction (SCR) technology is currently the most widely used stationary source denitrification technology. The representative catalyst is V ₂ O ₅ /TiO ₂ -based catalyst, which has good denitrification performance at medium and high temperatures (300-420°C). However, it has poor adaptability to the flue gas environment with low temperature and high NO ₂ /NO _x during the start-up stage of the gas turbine, and its ability to remove nitrogen oxides is insufficient.

For the removal of nitrogen oxides at low temperature, adsorption storage technology is a more suitable choice. Passive NO _x Adsorber (PNA) technology represented by Pd/ZSM-5 is mainly used in the cold start stage of motor vehicles, and has a good low-temperature NO _x adsorption effect, but it usually needs to be combined with post-treatment. _NOx can be removed. The nitrogen oxide storage reduction (NO _x Storage-Reduction, NSR) technology represented by Pt-Ba/Al realizes the storage and reduction of nitrogen oxides by using the fuel-lean stage switching of the motor vehicle engine, but it also has the cost of precious metals. High and small _NOx storage capacity, etc., are not suitable for the application of large flue gas volume in gas-fired power plants.

Cerium oxide (CeO ₂ ) has been extensively studied and applied in the field of SCR denitrification as a main catalyst or co-catalyst due to its excellent oxygen storage and release properties. At the same time, the abundant oxygen vacancies on the surface of _CeO2 have a strong chemical adsorption effect on _NOx . Therefore, based on CeO ₂ , aiming at the characteristics of frequent startup and shutdown of gas turbines, a cerium-based denitrification catalyst with low-temperature NO ₂ adsorption and medium-high temperature NO _x catalytic reduction has been developed, which is of great significance for realizing full-time NO _x emission control of gas-fired power plants. very important practical significance.

The patent specification with the publication number CN 108993471 A discloses a supported nanometer cerium oxide particle catalyst which can be used for catalytic purification of _NOx , with titanium dioxide carrier as the main component, Ag as the co-catalyst, and the mass fraction of cerium oxide is only 0.5% to 15%. %, the catalyst structure is a simple loading on the surface of titanium dioxide, and this patented technology does not involve the adsorption storage and reduction process of _NO2 .

Contents of the invention

The invention provides a catalyst suitable for the storage and reduction of nitrogen oxides in gas turbines, which is a low-cost cerium-based catalyst with good activity and stability, and can be used for gas turbine start-up and low load (Start Up and Low Loading, SULL ) storage and reduction of NO _x during the operation phase, and also has good SCR denitrification activity during the high load (High Loading, HL) operation phase of the gas turbine, which can effectively solve the problem of "yellow smoke" in the exhaust gas caused by the frequent start and stop of the gas turbine in the current gas-fired power plant .

A catalyst suitable for storage and reduction of nitrogen oxides in gas turbines. In the catalyst, Ag-M/CeO is the _nucleus , and its surface is covered with an amorphous _TiO layer;

The Ag-M/CeO ₂ represents the oxide of Ag, Ag ₂ O and acid additive M on the surface of CeO ₂ ;

The acidic additive M is at least one of W, Sb, Mo, and Nb, preferably W.

In the SULL stage of the gas turbine, the flue gas temperature is low, the water content is high, and the NO _x in the flue gas is mainly NO ₂ . The adaptability of the traditional vanadium-tungsten-titanium catalyst is poor. The abundant oxygen vacancies and certain basicity on the surface of CeO ₂ make it have excellent low-temperature NO ₂ adsorption performance, but the weak surface acidity also makes it impossible to effectively complete the SCR denitration reaction. Therefore, based on _CeO2 , the present invention improves its surface acidity and redox performance by adding acid additives M, Ag, and _Ag2O , respectively, and improves _NH3 adsorption and activation capabilities, thereby greatly improving its SCR performance. At the same time, the strong interaction between CeO ₂ and the acidic additive M promotes the formation of more oxygen vacancies, and Ag and Ag ₂ O can induce the bulk oxygen vacancies of CeO ₂ to migrate to the surface. ₂ Adsorption properties. Finally, it is wrapped with amorphous TiO ₂ , which not only avoids the agglomeration of CeO ₂ , but also increases the acid sites, further improving the denitrification performance of the catalyst. In addition, the inventors have also found that if it is not the Ag-M/ _CeO2 core and _TiO2 shell structure of the present invention, but the relatively common titanium dioxide supported cerium oxide, Ag, acidic additive M and other simple supported catalysts, The low-temperature storage effect and denitrification performance of the nitrogen oxides of the present invention, especially NO ₂ , cannot be obtained.

In the gas turbine SULL stage, the catalyst of the present invention can efficiently adsorb NO ₂ ; in the gas turbine HL stage, the surface of the catalyst can undergo SCR reaction by spraying NH ₃ in situ, and the NO ₂ adsorbed and stored on the catalyst surface will be reduced to N ₂ is desorbed to complete the denitrification and at the same time realize the regeneration of NO ₂ adsorption sites on the catalyst surface.

Preferably, the catalyst is mainly composed of CeO ₂ , wherein the mass ratio of CeO ₂ and TiO ₂ is preferably 100:5 to 20, more preferably 100:10, and the catalyst can show a higher NO ₂ under optimal conditions. adsorption capacity and better SCR catalytic performance.

Too high loading of Ag, Ag ₂ O and acidic additive M will reduce the adsorption of CeO ₂ on NO ₂ , while too low loading will make little effect on improving SCR performance. Preferably, in the Ag-M/CeO ₂ , the mass ratio of the sum of the mass of Ag and Ag ₂ O to the oxide of the acidic additive M and CeO ₂ is 0.02 to 0.2 (more preferably 0.1):0.5 ~2 (more preferably 1): 100; wherein the sum of the mass of Ag and Ag ₂ O is based on the mass of Ag and Ag ₂ O converted to Ag ₂ O, and the mass of the oxide of the acidic additive M is expressed in terms of WO _3. In terms of Sb ₂ O ₃ , MoO ₃ , and Nb ₂ O ₅ .

The catalyst of the present invention, on the one hand, CeO ₂ serves as the main NO ₂ low-temperature adsorption and storage site, can efficiently store NO ₂ in the form of nitrate/nitrite species in the SULL stage, and on the other hand, its excellent storage The oxygen evolution performance also plays an important role in the SCR function in the HL stage; the acidic additive M and the externally coated TiO ₂ provide a large number of surface acidic sites for the catalyst, which is beneficial to the adsorption of the reducing agent NH ₃ in the denitrification process, thereby Significantly improved the SCR performance of CeO ₂ ; the addition of acid additives M, Ag, and Ag ₂ O can have a good interaction with CeO ₂ and promote the generation of more oxygen vacancies on the surface, thereby enhancing the adsorption performance of the catalyst for NO ₂ , and at the same time It is also conducive to the further improvement of the redox performance of the catalyst and the improvement of the denitrification efficiency.

Among the catalysts, CeO ₂ is preferably obtained by calcining cerium nitrate hexahydrate at 400-450° C. for 4-5 hours.

The present invention also provides the preparation method of described catalyst, and described preparation method comprises steps:

(1) Preparation of Ag-M/CeO ₂ : disperse the precursors of CeO ₂ , silver nitrate and acid additive M in deionized water, dry and roast after mixing to obtain Ag-M/CeO ₂ ;

(2) Preparation of TiO _sol : Dissolve tetrabutyl titanate in ethanol as liquid A, mix nitric acid with deionized water and ethanol as liquid B, then add liquid A to liquid B which is continuously stirred to obtain TiO ₂ sols;

(3) Preparation of Ag-M/CeO ₂ @TiO ₂ catalyst: Add the Ag-M/CeO _{2 of} step (1) into the TiO sol of step (2), and keep stirring, then aging and roasting to obtain Ag-M/CeO ₂ @TiO ₂ catalyst suitable for storage and reduction of nitrogen oxides in gas turbines.

In step (1), the precursor of the acidic additive M is preferably at least one of ammonium metatungstate, antimony acetate, ammonium molybdate, and niobium oxalate.

Preferably, in step (1), the temperature of the calcination is 400-450° C., and the time is 4-5 hours.

Preferably, in step (3), the aging temperature is 75-85° C., and the aging time is 40-56 hours.

Preferably, in step (3), the temperature of the calcination is 400-450° C., and the time is 3-4 hours.

As a general inventive concept, the present invention also provides the application of the catalyst in the storage and catalytic reduction of nitrogen oxides in gas turbines.

Compared with the prior art, the present invention has beneficial effects:

1. The present invention uses _CeO2 as the main _NO2 adsorption storage site, and each added component greatly increases the surface oxygen vacancy content, and at the same time improves the surface acidity and redox ability of the catalyst, so that the catalyst has low-temperature _NO2 adsorption and Dual function of medium and high temperature _NOx catalytic reduction.

2. Coating the outer layer of Ag-M/CeO ₂ with amorphous TiO ₂ can avoid the agglomeration of CeO ₂ and provide abundant acid sites, further ensuring the medium and high temperature denitrification performance and stability of the catalyst.

3. The present invention has good cycle stability, and the NO ₂ adsorption performance of the catalyst can be regenerated by spraying NH ₃ in situ with SCR reaction at medium and high temperatures, and can realize the gas turbine start-stop cycle process within a long period of time. _NOx control.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

Example 1

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Ammonium metatungstate and mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain Ag-W/ _CeO2 powder, the total loading of Ag and _Ag2O was controlled to be about 0.1wt% ( Based on the mass of Ag and Ag ₂ O converted to Ag ₂ O, and based on the mass of CeO ₂ ), the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 12.8mg/g at 150°C, a _NOx conversion of 98.6% and a _N2 selectivity of 99.4% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 2

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.05wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV (mass space velocity)=30,000mL g - ¹ h- ¹ ; in the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV= 30,000mL g- ¹ h- ¹ . The _NO2 adsorption capacity of the catalyst at 150°C is 11.9 mg/g; the _NOx conversion at 300°C is 97.2%, the _N2 selectivity is 97.9%; the _NOx conversion at 350°C is 97.3%, The _N2 selectivity was 98.4%, and it showed good stability, and the _NO2 adsorption performance after 3 cycles was close to that of fresh samples.

Example 3

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.2wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 12.2mg/g at 150°C, a _NOx conversion of 100% at 350°C, and a _N2 selectivity of 97.9%, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 4

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.1wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 0.5wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 11.1 mg/g at 150°C, a _NOx conversion of 86.7% at 350°C, and a _N2 selectivity of 97.1%, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 5

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.1wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 2wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 10.8mg/g at 150°C, a _NOx conversion of 98.7% and a _N2 selectivity of 98.4% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 6

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.1wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 5 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 10.3mg/g at 150°C, a _NOx conversion of 92.5% and a _N2 selectivity of 99.0% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 7

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Mix ammonium metatungstate evenly, then dry at 120°C for 12 hours, and then bake at 450°C for 4 hours to obtain Ag-W/CeO ₂ , and control the total loading of Ag and Ag ₂ O to about 0.1wt% (with Ag and Ag ₂ O are all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), and the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 20 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 10.8mg/g at 150°C, a _NOx conversion of 93.7% and a _N2 selectivity of 99.1% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 8

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Antimony acetate and mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain Ag-Sb/CeO ₂ , the total loading of Ag and Ag ₂ O was controlled to be about 0.1wt% Ag ₂ O is all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), the loading of Sb is about 1wt% (based on the mass of Sb ₂ O ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-Sb/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-Sb/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm,

[H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ; in the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ] = 200ppm, [H ₂ O] = 10vol%, [O ₂ ] = 15vol%, N ₂ carrier gas, MHSV = 30,000mL g- ¹ h- ¹ . The catalyst has a _NO2 adsorption capacity of 9.9mg/g at 150°C, a _NOx conversion of 91.1% and a _N2 selectivity of 98.3% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 9

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Ammonium molybdate and mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain Ag-Mo/ _CeO2 , the total loading of Ag and _Ag2O was controlled to be about 0.1wt% (as Ag , Ag ₂ O is all converted to the mass of Ag ₂ O, and based on the quality of CeO ₂ ), the loading of Mo is about 1wt% (in terms of the mass of MoO ₃ , and based on the quality of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-Mo/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-Mo/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm,

[H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ; in the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ] = 200ppm, [H ₂ O] = 10vol%, [O ₂ ] = 15vol%, N ₂ carrier gas, MHSV = 30,000mL g- ¹ h- ¹ . The catalyst has a _NO2 adsorption capacity of 11.5mg/g at 150°C, a _NOx conversion of 98.2% and a _N2 selectivity of 99.2% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 10

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Niobium oxalate and mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain Ag-Nb/CeO ₂ , the total loading of Ag and Ag ₂ O was controlled to be about 0.1wt% (as Ag, Ag ₂ O is all converted to the mass of Ag ₂ O, and based on the mass of CeO ₂ ), the loading amount of Nb is about 1wt% (based on the mass of Nb ₂ O ₅ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-Nb/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-Nb/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O2]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h - ¹ . The catalyst has a _NO2 adsorption capacity of 10.7mg/g at 150°C, a _NOx conversion of 95.8% and a _N2 selectivity of 98.9% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 11

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Ammonium metatungstate and mixed evenly, then dried at 120°C for 12h, and then roasted at 400°C for 4h to obtain Ag-W/ _CeO2 powder, the total loading of Ag and _Ag2O was controlled to be about 0.1wt% ( Based on the mass of Ag and Ag ₂ O converted to Ag ₂ O, and based on the mass of CeO ₂ ), the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 12.0mg/g at 150°C, a _NOx conversion rate of 97.8% and a _N2 selectivity of 99.5% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Example 12

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and Ammonium metatungstate and mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain Ag-W/ _CeO2 powder, the total loading of Ag and _Ag2O was controlled to be about 0.1wt% ( Based on the mass of Ag and Ag ₂ O converted to Ag ₂ O, and based on the mass of CeO ₂ ), the loading amount of W is about 1wt% (based on the mass of WO ₃ , and based on the mass of CeO ₂ );

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add Ag-W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 400°C for 3h, The Ag-W/CeO ₂ @TiO ₂ catalyst is obtained, and the content of TiO ₂ in the outer layer is controlled to be about 10 wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm,

[H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ; in the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ] = 200ppm, [H ₂ O] = 10vol%, [O ₂ ] = 15vol%, N ₂ carrier gas, MHSV = 30,000mL g- ¹ h- ¹ . The catalyst has a _NO2 adsorption capacity of 12.1 mg/g at 150°C, a _NOx conversion of 96.6% and a _N2 selectivity of 99.6% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Comparative example 1

Catalyst preparation: (1) Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL deionized water, then add a certain amount of metatungstic acid ammonium and _mixed evenly, then dried at 120°C for 12h, and then roasted at 450°C for 4h to obtain W/ _CeO2 powder _. quality as the benchmark);

(2) Dissolve a certain amount of tetrabutyl titanate in 40mL of absolute ethanol as solution A, mix 5mL of 68wt% concentrated nitric acid with 20mL of absolute ethanol and 20mL of deionized water as solution B, and then add solution A dropwise In the stirring B liquid, obtain TiO _sol ;

(3) Add W/ _CeO2 powder into the fresh _TiO2 sol prepared in step (2), and keep stirring for 6h, then aging at 80°C for 48h, and finally roasting at 450°C for 3h to obtain W /CeO ₂ @TiO ₂ catalyst, the content of TiO ₂ in the outer layer is controlled to be about 10wt% (based on the mass of CeO ₂ ).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 6.9 mg/g at 150°C, a _NOx conversion of 92.2% and a _N2 selectivity of 97.4% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

Comparative example 2

Catalyst preparation: Roast cerium nitrate hexahydrate at 450°C for 4 hours to obtain CeO ₂ , after grinding and sieving, take 8g of 40-60 mesh CeO ₂ and disperse it in 100mL of deionized water, then add a certain amount of silver nitrate and partial tungsten ammonium phosphate and P25 titanium dioxide and mixed evenly, then dried at 120°C for 12 hours, and then calcined at 450°C for 4 hours to obtain Ag-W-TiO ₂ /CeO ₂ catalyst, the total loading of Ag and Ag ₂ O was controlled to be about 0.1wt% (based on the mass of Ag and _Ag2O converted to _Ag2O , and based on the mass of _CeO2 ), the loading of W is about 1wt% (based on the mass of _WO3 , and based on the mass _{of CeO2} As a benchmark), the content of TiO ₂ is about 10wt% (based on CeO ₂ mass).

Catalyst activity test: The activity test was carried out in a fixed-bed reactor with a catalyst dosage of 3.0 g and a particle size of 40-60 mesh. In the NO ₂ adsorption experiment, the mixed gas composition is: [NO ₂ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h- ¹ ;In the SCR experiment, the mixed gas composition is: [NO]=[NH ₃ ]=200ppm, [H ₂ O]=10vol%, [O ₂ ]=15vol%, N ₂ carrier gas, MHSV=30,000mL g- ¹ h ^-1 . The catalyst has a _NO2 adsorption capacity of 9.3mg/g at 150°C, a _NOx conversion of 95.7% and a _N2 selectivity of 99.4% at 350°C, and exhibits good stability, after 3 cycles The NO ₂ adsorption performance is close to that of fresh samples.

In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (10)

1. A catalyst suitable for nitrogen oxide storage reduction of a gas turbine is characterized in that Ag-M/CeO in the catalyst ₂ Is a core, the surface of which is coated with amorphous TiO ₂ A layer;

the Ag-M/CeO ₂ Representing CeO ₂ Surface loading Ag, ag ₂ Oxides of O and of the acidic auxiliaries M;

the acid assistant M is at least one of W, sb, mo, nb.

2. The catalyst according to claim 1, wherein in the catalyst, ceO ₂ And TiO ₂ The mass ratio of (2) is 100:5-20.

3. The catalyst according to claim 1, wherein the Ag-M/CeO ₂ Among Ag, ag ₂ The sum of the masses of O and the oxide of the acid auxiliary agent M, ceO ₂ The mass ratio of (2) is 0.02-0.2:0.5-2:100; wherein Ag,Ag ₂ The sum of the masses of O is Ag and Ag ₂ O is converted into Ag ₂ Mass of the oxide of the acid auxiliary M is calculated by mass of O in WO ₃ 、Sb ₂ O ₃ 、MoO ₃ 、Nb ₂ O ₅ And (5) counting.

4. The catalyst according to claim 1, wherein in the catalyst, ceO ₂ The cerium nitrate hexahydrate is obtained by roasting for 4 to 5 hours at the temperature of 400 to 450 ℃.

5. The method for producing a catalyst according to any one of claims 1 to 4, characterized in that the method comprises the steps of:

(1)Ag-M/CeO ₂ is prepared from the following steps: ceO is added with ₂ Dispersing the silver nitrate and the precursor of the acid auxiliary agent M in deionized water, uniformly mixing, drying and roasting to obtain Ag-M/CeO ₂ ；

(2)TiO ₂ Preparation of sol: dissolving tetrabutyl titanate in ethanol to obtain solution A, mixing nitric acid with deionized water and ethanol to obtain solution B, and adding the solution A into the solution B under continuous stirring to obtain TiO ₂ Sol;

(3)Ag-M/CeO ₂ @TiO ₂ preparation of the catalyst: ag-M/CeO of step (1) ₂ TiO added to step (2) ₂ In the sol, stirring continuously, aging and roasting to obtain Ag-M/CeO suitable for the storage reduction of nitrogen oxides of gas turbines ₂ @TiO ₂ A catalyst.

6. The preparation method according to claim 5, wherein in the step (1), the precursor of the acid promoter M is at least one of ammonium metatungstate, antimony acetate, ammonium molybdate and niobium oxalate.

7. The method according to claim 5, wherein in the step (1), the baking temperature is 400 to 450 ℃ for 4 to 5 hours.

8. The method according to claim 5, wherein in the step (3), the aging is performed at a temperature of 75 to 85 ℃ for 40 to 56 hours.

9. The method according to claim 5, wherein in the step (3), the baking temperature is 400 to 450 ℃ and the time is 3 to 4 hours.

10. Use of a catalyst according to any one of claims 1-4 in gas turbine nitrogen oxide storage catalytic reduction.