CN111408365A - A kind of preparation method of monolithic manganese-based catalyst for low-temperature denitration - Google Patents

Abstract

The invention discloses a preparation method of an integral manganese-based catalyst for low-temperature denitration, and relates to the technical field of environmental catalysis. The method comprises the following steps: A. soaking the honeycomb ceramic catalyst carrier in an oxidizing solvent, washing to be neutral and drying; B. dissolving manganese salt, ferric salt or manganese salt and cerium salt in a solvent to obtain a mixed solution, adding an organic compound, and heating and stirring in a water bath; C. drying and roasting the catalyst precursor solution to obtain catalyst powder, mixing the catalyst powder with deionized water and a complexing binder, and coating the mixture on a pretreatment carrier; or directly adding the pretreatment carrier into the catalyst precursor solution, and drying and roasting the pretreatment carrier coated with the catalyst precursor solution to obtain the monolithic manganese-based catalyst for low-temperature denitration. The method is simple and efficient, nontoxic and harmless, the prepared product is uniform in dispersion, firm in combination and high in activity, the NOx removal efficiency can reach 70% -96%, the flue gas denitration effect is obvious, and the method has a wide application prospect.

Description

A kind of preparation method of monolithic manganese-based catalyst for low-temperature denitration

technical field

The invention relates to the technical field of environmental catalysis, in particular to a monolithic manganese-based catalyst for low-temperature denitration and a preparation method thereof, in particular to a monolithic catalyst based on manganese-based composite oxide and applied to low-temperature denitration of sintering flue gas and its preparation method.

Background technique

With the development of the iron and steel industry, the emission of nitrogen oxides in sintering flue gas has become one of the main obstacles hindering the green development of iron and steel enterprises. These pollutions not only cause damage to the atmospheric environment (the hole in the ozone layer, acid rain and photochemical smog, etc.), but also seriously endanger human health. Selective catalytic reduction (SCR) of nitrogen oxides (NOx) in flue gas by selective catalytic reduction of nitrogen oxides (NOx) into nitrogen at a certain temperature with a nitrogen-containing reductant such as ammonia (NH ₃ ) using an appropriate catalyst The main method of sintering flue gas denitrification.

At present, the most mature catalyst system used in the SCR process in the industry is vanadium-tungsten-titanium catalyst. However, due to its high activity temperature, the denitration reactor needs to be installed before the desulfurization device, electrostatic precipitator and air preheater, so it is easy to cause flying Ash clogging the catalyst bed and catalyst _SO2 poisoning. In addition, the precursors of vanadium oxides are highly toxic and easily cause environmental pollution. Therefore, it is urgent to develop new low-temperature SCR catalysts to reduce the catalyst activity temperature to 120 °C-160 °C, so as to realize the backward shift of the denitrification device.

Manganese-based catalysts are new high-efficiency catalysts currently used in SCR processes _. For example, Mn3O4 can achieve efficient adsorption _of NO and convert it into adsorbed NO, while the oxygen vacancies on its surface can effectively capture oxygen molecules and enable It becomes activated, which in turn completes the NO to _NO2 reaction process. This makes it easier to achieve a "fast SCR reaction" of NO:NO ₂ =1:1.

Chinese invention patent No. 107126955A "A carbon-based low-temperature sintering flue gas denitration catalyst and its preparation method" discloses a kind of modified biomass coke as a carrier, MnO ₂ as an active component, and CeO ₂ as a co-catalyst group. The different powder catalysts show excellent performance in the fixed bed denitration test, and the denitration rate can reach more than 90% in the range of 100℃-200℃. In addition, the Chinese invention patent with publication number 108671965A "A semi-coke low-temperature SCR denitration catalyst and its preparation method" proposes to prepare an activated carbon carrier with semi-coke, and then use melamine as a reducing agent to support manganese oxide active components by impregnation and roasting. , the denitration efficiency of the obtained catalyst can reach more than 90% in the range of 175℃-300℃. However, considering that the catalyst components need to be coated on a large-sized shaped carrier in practical applications, and the space velocity of the actual working condition is low, how to prepare an efficient monolithic catalyst needs to be further explored.

The Chinese invention patent "Denitration catalyst and its preparation method and application in flue gas denitration" with the announcement number of 105854874A discloses a low-temperature self-propagating combustion coating method to prepare a low-temperature denitration catalyst, mainly using glycine, urea and other substances to The state solution is ignited, so that the active components such as Mn, Ce and Al are evenly supported on the carrier. The obtained monolithic catalyst can achieve a NO conversion rate of about 80% at 250 °C, but it still cannot meet the current requirements.

Chinese invention patent No. 101879452A "A manganese-based low-temperature denitration catalyst and its preparation method" discloses a low-temperature denitration catalyst containing four elements of manganese, iron, cerium and tin, and the obtained 200mg powder sample is at 30000h ^-1 Under the space velocity, the NO conversion rate in the range of 110℃-200℃ can reach more than 95%. In this patent, manganese and other elements are precipitated by dropwise addition of ammonium salt solution to the precursor solution, followed by calcination to obtain oxide complexes of manganese and other elements. However, the combination of various active ingredients increases the manufacturing cost, and it is particularly important to reduce the cost of raw materials and optimize the preparation process to further meet the actual production requirements under the premise of meeting emission reduction standards.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to propose a preparation method of a monolithic manganese-based catalyst for low-temperature denitration. The monolithic catalyst prepared by the invention can be applied to the removal of nitrogen oxides through selective catalytic reduction of ammonia, so as to realize the denitration treatment of sintered flue gas.

The object of the present invention is achieved through the following technical solutions: a preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Pretreatment carrier: The honeycomb ceramic catalyst carrier is immersed in an oxidizing solvent, washed to become neutral, and dried for later use;

B. Preparation of catalyst precursor solution: dissolving manganese salt, iron salt or manganese salt and cerium salt in a solvent to obtain a mixed solution, adding an organic compound, heating and stirring in a water bath;

C. Preparation of monolithic catalyst: drying and calcining the catalyst precursor solution to obtain catalyst powder, mixing the catalyst powder with deionized water and complex binder and coating it on the pretreatment carrier; or directly adding the pretreatment carrier to the catalyst precursor In the bulk solution, the pretreatment carrier coated with the catalyst precursor solution is dried and calcined to obtain the monolithic manganese-based catalyst for low-temperature denitration, and the manganese supported by the monolithic manganese-based catalyst for low-temperature denitration The mass percentage content of the base active component is 6% to 14%.

When the mass percentage of manganese-based active components supported by the monolithic manganese-based catalyst for low-temperature denitration is less than 6%, excellent low-temperature denitration performance cannot be achieved due to the lack of active components; When the mass percentage content of the manganese-based active component supported by the monolithic manganese-based catalyst for low-temperature denitration is higher than 14%, due to the excessively high metal element content, agglomeration forms a large number of oxide particles, which increases the gas phase diffusion resistance and reduces the catalyst. activity. At the same time, an excessively high content of active components will also increase the production cost of the monolithic catalyst per unit volume.

Preferably, the honeycomb ceramic catalyst carrier in step A includes one or more of alumina ceramics and cordierite ceramics.

Preferably, the oxidizing solvent in step A includes a phosphoric acid solution with a concentration of 20%-40% by mass or a hydrogen peroxide solution with a concentration of 15%-30% by mass.

Preferably, in step A, the impregnation time of the honeycomb ceramic catalyst carrier in the oxidizing solvent is 4-8h, and the drying temperature is 80-120°C.

Preferably, the manganese salt in step B includes one or more of manganese nitrate and manganese acetate; the iron salt includes one or more of ferric nitrate, ferric ammonia oxalate, ferric acetate, and ferric citrate; The cerium salt includes one or more of cerium nitrate and ceric amine oxalate; the solvent includes one or more of deionized water, methanol, and ethanol.

More preferably, the manganese salt in step B is preferably manganese nitrate.

Preferably, the organic compound in step B includes one or more of urea, citric acid, and glycine.

Preferably, the molar ratio of manganese element and iron element in the mixed solution described in step B is (0.5-1.5): 1; the molar ratio of manganese element and cerium element is (1-5): (5-9), the said The molar ratio of the organic compound to the manganese element is (0.5-5):1; more preferably, the molar ratio of the urea to the manganese element is (3-5):1.

In the ratio of ferromanganese and manganese to cerium, too little manganese and too much iron or cerium will cause the activity to decrease. Too little organic matter will cause insufficient oxidation of nitrate, resulting in decreased catalyst yield and activity; too much organic matter will cause excessive oxidation of nitrate, or even sintering, resulting in decreased catalyst activity.

Preferably, the heating temperature of the water bath in step B is 70°C-90°C, and the heating time is 1h-4h.

More preferably, before adding the organic compound in step B, a TiO(NO ₃ ) precursor solution is added, and the TiO(NO ₃ ) precursor solution is twice the molar amount of manganese _; The preparation method is as follows: using tetrabutyl titanate equivalent to twice the molar amount of manganese element as the precursor of titanium dioxide, slowly adding anhydrous ethanol dropwise to a beaker containing an appropriate amount of tetrabutyl titanate for alcoholysis, and at room temperature Magnetic stirring was performed under the same method, and deionized water was added dropwise to the alcoholysis solution in the same way to hydrolyze to form TiO(OH) ₂ precipitation, and then an appropriate amount of nitric acid was added to dissolve the precipitation to obtain a clear and transparent TiO(NO ₃ ) precursor solution.

Preferably, the step C specifically includes the following steps:

The catalyst precursor solution was dried at 80°C-120°C for 6h-12h and calcined at 450°C-650°C for 4h-6h to obtain catalyst powder, then mixed with ionized water and complex binder, and sprayed with a compressor spray gun for pre-treatment. The treated carrier is dried for 1min-5min at 80℃-120℃ for 1h-3h, and repeated several times to obtain the monolithic manganese-based catalyst for low-temperature denitration, wherein the quality of the pretreated carrier is combined with deionized water, complexed The mass ratio of the binder is 1:(0.75-1.25):(0.05-0.2);

Or add the pretreated carrier to the catalyst precursor solution, ultrasonically immerse it for 10min-60min, and then dry the pretreated carrier coated with the catalyst precursor solution at 150℃-350℃ for 1h, then at 450℃-650℃ After calcining for 5h-6h, the monolithic manganese-based catalyst for low-temperature denitration can be obtained; the more preferred ultrasonic impregnation time is 35-60min.

When the calcination temperature is too high, it will cause excessive oxidation, resulting in excessive catalyst lattice distortion, etc., and the activity will decrease; if the calcination temperature is too low, the oxidation of the precursor nitrate will be insufficient, and the activity will also decrease.

Preferably, the complex binder includes one or more of silica sol, aluminum sol, and methyl cellulose.

To sum up, compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention mainly utilizes manganese-based oxide composite iron element or cerium element to prepare catalyst, the raw material composition is simple, non-toxic and harmless, and the preparation process is fast, which is conducive to further realizing large-scale production test;

(2) In the catalyst loading method of the present invention, the content of the active components of the carrier coating is mainly in the range of 6%-14%. For the same precursor, the monolithic catalyst with low content of active components prepared by the optimized process has higher specific activity. Thereby, the reuse rate of the precursor solution can be improved, and the production cost can be reduced;

(3) The present invention realizes efficient coating preparation on the basis of powder catalyst and honeycomb ceramic carrier, optimizes the dispersibility of active components on the honeycomb ceramic carrier, thereby improving the diffusion conditions of reactants during gas-solid two-phase reaction and reducing denitrification The reaction activity temperature enables the catalyst to achieve a NO conversion rate of more than 90% in the temperature range of 110℃-160℃ under the condition of low space velocity below 8000h ^-1 , and its performance is better than that of general molding and powder system manganese-based catalysts.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a broken line graph of NO conversion rate of the catalysts of the monolithic manganese-based catalysts used for low-temperature denitration in the NH ₃ -SCR denitration process in Examples 1-7.

Detailed ways

The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. For those skilled in the art, on the premise of not departing from the concept of the present invention, several changes and improvements can also be made, which all belong to the protection scope of the present invention. The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that The scope should be considered to be specifically disclosed herein, and the present invention will be described in detail below in conjunction with specific embodiments:

Example 1

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the cylindrical alumina honeycomb ceramic catalyst carrier with a bottom diameter of 11mm and a height of 24mm in a container with a mass concentration of 30% hydrogen peroxide solution, let stand for 6h at room temperature, and then repeatedly wash and dry until it becomes clear properties, put it in an oven to dry at 80°C for 12h to obtain the pretreated alumina honeycomb ceramic catalyst carrier;

B. Use manganese nitrate as manganese source, and use a mixture of deionized water and methanol as solvent. A certain amount of manganese nitrate tetrahydrate and ferric nitrate nonahydrate (molar ratio of ferromanganese element = 1:1) are respectively dissolved in an appropriate amount of solvent, stirred until completely dissolved and mixed evenly, and 5 times the molar ratio of manganese element is added to the above solution. Urea, stir and disperse, and fully stir the sample solution in a water bath at 80°C for 2h.

C. Put it in an oven to dry at 110°C for 12h, and finally put the powder solid sample into a corundum crucible with a volume of 100mL, then place the sample crucible in a muffle furnace, and heat it up to 550°C at a rate of 5°C/min , keep warm for 4h. After cooling, take it out and grind it in an agate mortar to obtain the target;

Dissolve the ground catalyst powder and a certain amount of silica sol in an appropriate amount of deionized water, wherein the mass ratio of the pretreated carrier to deionized water and complex binder is 1:1:0.125 to obtain a catalyst slurry. The pretreated carrier was sprayed with a compressor spray gun for 3 minutes, dried at 100°C for 2 hours, and repeated several times to obtain the monolithic manganese-based catalyst for low-temperature denitration;

The proportion of active components in the prepared ferromanganese low-temperature denitration monolithic catalyst is about 10%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. min, N ₂ flow rate of 129 mL/min, and space velocity of 4000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 2

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the cylindrical alumina honeycomb ceramic catalyst carrier with a bottom diameter of 11mm and a height of 24mm in a container with a mass concentration of 30% hydrogen peroxide solution, let stand for 6h at room temperature, and then repeatedly wash and dry until it becomes clear properties, put it in an oven to dry at 80°C for 12h to obtain the pretreated alumina honeycomb ceramic catalyst carrier;

B. Use manganese nitrate as manganese source, and use anhydrous methanol or ethanol as solvent. A certain amount of manganese nitrate tetrahydrate and ferric nitrate nonahydrate (molar ratio of manganese-iron element = 1:1) are respectively dissolved in an appropriate amount of solvent, stirred until completely dissolved, and then mixed evenly. Use tetrabutyl titanate equivalent to twice the molar amount of manganese as the precursor of titanium dioxide, slowly add anhydrous ethanol dropwise to a beaker containing an appropriate amount of tetrabutyl titanate for alcoholysis, and use magnetic stirring at room temperature. , and then add deionized water dropwise to the alcoholysis solution in the same way to make it hydrolyze to form TiO(OH) ₂ precipitation, and then drop an appropriate amount of nitric acid to dissolve the precipitation to obtain a clear and transparent TiO(NO ₃ ) precursor solution; Mix the above solutions evenly , add urea equivalent to 5 times the molar amount of manganese, stir and disperse, and fully stir the sample solution in a water bath at 80°C for 2h.

C. Put it in an oven to dry at 110°C for 12h, and finally put the powder solid sample into a corundum crucible with a volume of 100mL, then place the sample crucible in a muffle furnace, and heat it up to 450°C at a rate of 5°C/min , keep warm for 4h. After cooling, take it out and grind it in an agate mortar to obtain the target;

Dissolve the ground catalyst powder and a certain amount of silica sol in an appropriate amount of deionized water, wherein the mass ratio of the pretreatment carrier to deionized water and complex binder is 1:1.25:0.2 to obtain a catalyst slurry. The pretreated carrier was sprayed with a compressor spray gun for 5 minutes, dried at 110° C. for 3 hours, and repeated several times to obtain the monolithic manganese-based catalyst for low-temperature denitration;

The proportion of active components in the prepared ferromanganese/titania low-temperature denitration monolith catalyst is about 10%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is Under the conditions of 15 mL/min, N ₂ flow rate of 129 mL/min, and space velocity of 4000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 3

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the 11mm*11mm*48mm cube-shaped alumina honeycomb ceramic catalyst carrier in a container with a mass concentration of 30% hydrogen peroxide solution, let it stand for 6 hours at room temperature, and then repeatedly wash and dry until it is neutral. The pretreated alumina honeycomb ceramic catalyst carrier was obtained by drying at 80°C for 12h in an oven;

B. Dissolve a certain amount of manganese nitrate tetrahydrate and ferric nitrate nonahydrate (molar ratio of ferromanganese element = 1:1) in an appropriate amount of deionized water, stir until completely dissolved, and mix evenly, and then add a molar amount equivalent to manganese element. 2 times of urea, and fully stirred in a water bath at 80 °C for 2 h.

C. Immerse the pretreated ceramic carrier in the obtained mixed solution, ultrasonically impregnate it for 35 minutes, and then dry the pretreated carrier coated with the catalyst precursor solution at 350 °C for 1 hour, and then bake it at 450 °C for 5 hours. to obtain the monolithic manganese-based catalyst for low-temperature denitration;

The proportion of active components in the prepared ferromanganese low-temperature denitration monolithic catalyst is about 6%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. Under the conditions of min, N ₂ flow rate of 129 mL/min, and space velocity of 1625 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 4

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the 6mm*6mm*28mm cube-shaped alumina honeycomb ceramic catalyst carrier in a container with a mass concentration of 30% hydrogen peroxide solution, let it stand for 6 hours at room temperature, and then repeatedly wash and dry until it is neutral. The pretreated alumina honeycomb ceramic catalyst carrier was obtained by drying at 80°C for 12h in an oven;

B. Dissolve a certain amount of manganese nitrate tetrahydrate and ferric nitrate nonahydrate (molar ratio of ferromanganese element = 1:1) in an appropriate amount of deionized water, stir until completely dissolved, and mix evenly, and then add a molar amount equivalent to manganese element. 4 times of urea, and fully stirred in a water bath at 80 °C for 2 h.

C. Immerse the pretreated ceramic carrier in the obtained mixed solution, ultrasonically impregnate it for 35 minutes, and then dry the pretreated carrier coated with the catalyst precursor solution at 250 °C for 1 h, and then bake it at 550 °C for 5.5 h , that is, the monolithic manganese-based catalyst for low-temperature denitration is obtained;

The proportion of active components in the prepared ferromanganese low-temperature denitration monolithic catalyst is about 6%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. Under the conditions of min, N ₂ flow rate of 129 mL/min, and space velocity of 8000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 5

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the 6mm*6mm*28mm cube-shaped alumina honeycomb ceramic catalyst carrier in a container with a mass concentration of 30% hydrogen peroxide solution, let it stand for 6 hours at room temperature, and then repeatedly wash and dry until it is neutral. The pretreated alumina honeycomb ceramic catalyst carrier was obtained by drying in an oven at 80 °C for 12 h.

B. Dissolve a certain amount of manganese acetate tetrahydrate and cerium nitrate (molar ratio of manganese-cerium element = 1:1) in an appropriate amount of deionized water respectively, stir until completely dissolved and mix evenly, then add 0.7 times the molar amount of manganese element citric acid and fully stirred in a water bath at 80 °C for 2 h.

C. Immerse the pretreated ceramic carrier in the obtained mixed solution, ultrasonically impregnate it for 10 minutes, and then dry the pretreated carrier coated with the catalyst precursor solution at 150 °C for 1 hour, and then bake it at 650 °C for 5 hours. to obtain the monolithic manganese-based catalyst for low-temperature denitration;

The proportion of active components in the prepared manganese-cerium low-temperature denitration monolith catalyst is about 8%. At the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. Under the conditions of min, N ₂ flow rate of 129 mL/min, and space velocity of 8000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 6

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the 6mm*6mm*28mm cube-shaped alumina honeycomb ceramic catalyst carrier in a container with a mass concentration of 30% hydrogen peroxide solution, let it stand for 6 hours at room temperature, and then repeatedly wash and dry until it is neutral. The pretreated alumina honeycomb ceramic catalyst carrier was obtained by drying in an oven at 80 °C for 12 h.

B. Dissolve a certain amount of manganese nitrate tetrahydrate and cerium nitrate (molar ratio of manganese-cerium element = 1:1) in an appropriate amount of deionized water respectively, stir until completely dissolved and mix evenly, then add 0.7 times the molar amount of manganese element citric acid and fully stirred in a water bath at 80 °C for 2 h.

C. Immerse the pretreated ceramic carrier in the obtained mixed solution, ultrasonically impregnate it for 60 minutes, and then dry the pretreated carrier coated with the catalyst precursor solution at 350 °C for 1 h, and then bake it at 450 °C for 5 h, That is, the monolithic manganese-based catalyst for low-temperature denitration is obtained.

The proportion of active components in the prepared manganese-cerium low-temperature denitration monolith catalyst is about 6.39%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. Under the conditions of min, N ₂ flow rate of 129 mL/min, and space velocity of 8000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 7

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, comprising the following steps:

A. Immerse the 6mm*6mm*28mm cube-shaped alumina honeycomb ceramic catalyst carrier in a container with a mass concentration of 30% hydrogen peroxide solution, let it stand for 6 hours at room temperature, and then repeatedly wash and dry until it is neutral. The pretreated alumina honeycomb ceramic catalyst carrier was obtained by drying in an oven at 80 °C for 12 h.

B, a certain amount of manganese nitrate tetrahydrate and cerium nitrate (molar ratio of manganese-cerium element = 3:7) are dissolved in an appropriate amount of deionized water respectively, stirred to be completely dissolved and mixed uniformly, and then added equivalent to 0.7 mole of manganese element times of citric acid and fully stirred in a water bath at 80 °C for 1 h.

C. Immerse the pretreated ceramic carrier in the obtained mixed solution, ultrasonically impregnate it for 35 minutes, and then dry the pretreated carrier coated with the catalyst precursor solution at 150 °C for 1 h, and then bake it at 650 °C for 5 h. That is, the monolithic manganese-based catalyst for low-temperature denitration is obtained.

The proportion of active components in the prepared manganese-cerium low-temperature denitration monolithic catalyst is about 13.6%. Within the reaction temperature of 110℃-160℃, the NO flow rate is 6mL/min, the NO flow rate is 6mL/min, and the O ₂ flow rate is 15mL/min. Under the conditions of min, N ₂ flow rate of 129 mL/min, and space velocity of 8000 h ^-1 , the NO conversion rate of the obtained catalyst in the NH ₃ -SCR denitration process is shown in Figure 1.

Example 8

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, the difference from Example 1 is that step A specifically includes the following steps: a cylindrical cordierite ceramic catalyst carrier with a bottom diameter of 11 mm and a height of 24 mm It was immersed in a container containing a phosphoric acid solution with a mass concentration of 20%, left standing at room temperature for 8 hours, washed and dried repeatedly until it became neutral, and was dried in an oven at 120 ° C for 12 hours to obtain a pretreated cordierite ceramic catalyst carrier. ; In step B, the molar ratio of manganese element and iron element in the sample solution is 0.5:1, and the molar ratio of organic compound and manganese element is 0.5:1. The rest of the operations are the same as in Example 1.

Example 9

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, the difference from Example 1 is that step A specifically includes the following steps: a cylindrical cordierite ceramic catalyst carrier with a bottom diameter of 11 mm and a height of 24 mm Immerse in a container containing a phosphoric acid solution with a mass concentration of 40%, let stand for 4 hours at room temperature, and then repeatedly wash and dry until it becomes neutral, put it in an oven and dry at 90 ° C for 12 hours to obtain the pretreated cordierite ceramic catalyst carrier In step B, the molar ratio of manganese element and iron element in the sample solution is 1.5:1, and the molar ratio of organic compound and manganese element is 1:1; the remaining operations are the same as those in Example 1.

Example 10

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, which differs from Example 5 in that step A specifically includes the following steps: a cylindrical alumina ceramic catalyst carrier with a bottom diameter of 11 mm and a height of 24 mm Immerse in a container with a hydrogen peroxide solution with a mass concentration of 20%, let stand for 8 hours at room temperature, and then repeatedly wash and dry until it becomes neutral, put it in an oven and dry at 120 ° C for 12 hours to obtain pretreated alumina ceramics catalyst carrier. In step B, the molar ratio of manganese element to cerium element in the sample solution is 1:7, and the molar ratio of organic compound to manganese element is 2:1. In step C, the pretreated ceramic carrier is immersed in the obtained mixed solution, ultrasonically immersed for 60 min, and then the pretreated carrier coated with the catalyst precursor solution is first dried at 350 ° C for 1 h, and then calcined at 550 ° C for 6 h , that is, the monolithic manganese-based catalyst for low-temperature denitration is obtained. The rest of the operations are the same as in Example 1 and the rest of the operations are the same as those in Example 5.

Example 11

A preparation method of a monolithic manganese-based catalyst for low-temperature denitration, which differs from Example 5 in that step A specifically includes the following steps: a cylindrical alumina ceramic catalyst carrier with a bottom diameter of 11 mm and a height of 24 mm It was immersed in a container containing a phosphoric acid solution with a mass concentration of 30%, stood at room temperature for 4 hours, washed and dried repeatedly until it became neutral, and was dried in an oven at 90 °C for 12 hours to obtain the pretreated alumina ceramic catalyst carrier. In step B, the molar ratio of manganese element and cerium element in the sample solution is 2:9, and the molar ratio of organic compound and manganese element is 2:1. In step C, the pretreated ceramic carrier is immersed in the obtained mixed solution, ultrasonically immersed for 60 min, and then the pretreated carrier coated with the catalyst precursor solution is first dried at 250 ° C for 1 h, and then calcined at 500 ° C for 6 h , that is, the monolithic manganese-based catalyst for low-temperature denitration is obtained. The rest of the operations are the same as in Example 1 and the rest of the operations are the same as those in Example 5.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily, provided that there is no conflict.

Claims (10)

1. a preparation method for the monolithic manganese-based catalyst for low temperature denitration, is characterized in that: comprise the steps: A. Pretreatment carrier: The honeycomb ceramic catalyst carrier is immersed in an oxidizing solvent, washed to become neutral, and dried for later use; B. Preparation of catalyst precursor solution: dissolving manganese salt, iron salt or manganese salt and cerium salt in a solvent to obtain a mixed solution, adding an organic compound, heating and stirring in a water bath; C. Preparation of monolithic catalyst: drying and calcining the catalyst precursor solution to obtain catalyst powder, mixing the catalyst powder with deionized water and complex binder and coating it on the pretreatment carrier; or directly adding the pretreatment carrier to the catalyst precursor In the bulk solution, the pretreatment carrier coated with the catalyst precursor solution is dried and calcined to obtain the monolithic manganese-based catalyst for low-temperature denitration, and the manganese supported by the monolithic manganese-based catalyst for low-temperature denitration The mass percentage content of the base active component is 6% to 14%. 2. The preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the honeycomb ceramic catalyst carrier described in step A comprises one or more of alumina ceramics and cordierite ceramics. kind. 3. The preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the oxidizing solvent in step A comprises a phosphoric acid solution with a mass percentage concentration of 20%-40% or Hydrogen peroxide solution with mass percentage concentration of 15%-30%. 4. The preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the dipping time of the honeycomb ceramic catalyst carrier in the step A is 4-8h, and the drying time is 4-8h. The temperature is 80-120℃. 5. The preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the manganese salt in step B comprises one or more of manganese nitrate and manganese acetate; the described The iron salt includes one or more of ferric nitrate, ferric ammonia oxalate, ferric acetate, and ferric citrate; the cerium salt includes one or more of cerium nitrate and ceric amine oxalate; the solvent includes deionized water , one or more of methanol and ethanol. 6. The method for preparing a monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the organic compound described in step B comprises one or more of urea, citric acid, and glycine . 7. the preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, is characterized in that, in the described mixed solution of step B, the mol ratio of manganese element and iron element is (0.5-1.5): 1 ; The molar ratio of manganese element and cerium element is (1-5): (5-9), and the molar ratio of described organic compound and manganese element is (0.5-5): 1. 8 . The method for preparing a monolithic manganese-based catalyst for low-temperature denitration according to claim 1 , wherein the heating temperature of the water bath in step B is 70°C-90°C, and the heating time is 1h-4h. 9 . 9. The preparation method of the monolithic manganese-based catalyst for low-temperature denitration according to claim 1, wherein the step C specifically comprises the following steps: The catalyst precursor solution was dried at 80°C-120°C for 6h-12h and calcined at 450°C-650°C for 4h-6h to obtain catalyst powder, then mixed with ionized water and complex binder, and sprayed with a compressor spray gun for pre-treatment. The treated carrier is dried for 1min-5min at 80℃-120℃ for 1h-3h, and repeated several times to obtain the monolithic manganese-based catalyst for low-temperature denitration, wherein the quality of the pretreated carrier is combined with deionized water, complexed The mass ratio of the binder is 1:(0.75-1.25):(0.05-0.2); Or add the pretreated carrier to the catalyst precursor solution, ultrasonically immerse it for 10min-60min, and then dry the pretreated carrier coated with the catalyst precursor solution at 150℃-350℃ for 1h, then at 450℃-650℃ After calcining for 5h-6h, the monolithic manganese-based catalyst for low-temperature denitration can be obtained. 10 . The method for preparing a monolithic manganese-based catalyst for low-temperature denitration according to claim 9 , wherein the complex binder comprises one of silica sol, aluminum sol, and methyl cellulose. 11 . variety.

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