CN115155559B

CN115155559B - Denitration catalyst and preparation method and application thereof

Info

Publication number: CN115155559B
Application number: CN202210921596.3A
Authority: CN
Inventors: 张一波; 韩新宇; 刘凯杰; 杨向光; 廖伍平
Original assignee: Ganjiang Innovation Academy of CAS
Current assignee: Ganjiang Innovation Academy of CAS
Priority date: 2022-08-02
Filing date: 2022-08-02
Publication date: 2023-04-25
Anticipated expiration: 2042-08-02
Also published as: CN115155559A

Abstract

The invention relates to a denitration catalyst, a preparation method and application thereof, wherein the denitration catalyst comprises a tin niobate nanosheet carrier and cerium-based active nanospheres loaded on the tin niobate nanosheet carrier. The preparation method comprises the steps of firstly carrying out a first reaction to prepare tin niobate nanometer material, then carrying out a second reaction to obtain cerium-based active component colloid, finally mixing the tin niobate nanometer material and the cerium-based active component colloid, and then evaporating and roasting to obtain the denitration catalyst. The denitration catalyst provided by the invention can increase the surface acidity and the oxidation-reduction capability of the whole catalyst by loading the cerium-based active nanospheres on the acidic tin niobate nanosheets, and can be used for the reaction of ammonia selective catalytic reduction of nitrogen oxides.

Description

Denitration catalyst and preparation method and application thereof

Technical Field

The invention relates to the technical field of flue gas purification, in particular to a denitration catalyst and a preparation method and application thereof.

Background

Nitrogen Oxides (NO) _x ) Is the main pollutant in air and its source is fossilCombustion of the fuel. Excessive emissions of nitrogen oxides can cause a series of environmental and climate problems such as acid rain, photochemical smog, and global warming. Traditional fixed source flue gas denitration is mainly performed by using ammonia selective catalytic reduction (NH ₃ -SCR), V ₂ O ₅ /WO ₃ -TiO ₂ Or a modified material thereof, is a catalyst and is operated at a temperature of typically 300-400 ℃. The catalyst has low catalytic activity at 250 ℃ and V ₂ O ₅ Belongs to toxic substances, and the recovery and the post-treatment of the toxic substances become bottleneck problems for restricting the development of the catalyst. With cerium oxide (CeO) ₂ ) And the catalyst with the modified ceria as an active component has received a great deal of attention due to the characteristics of good oxygen storage and release performance, high nitrogen selectivity and environmental protection. The pure ceria catalyst has poor catalytic performance and narrow temperature range. Thus, modification studies, such as doping and loading, of ceria-based catalysts are critical to the value of the performance of ceria-based catalysts.

The key to the modification of ceria-based denitration catalysts is to increase their surface acidity. According to NH ₃ The mechanism of the SCR reaction, if more Lewis acid sites or

Acidic sites, they can exhibit more excellent catalytic performance at higher reaction temperatures (250 ℃ and above). At present, many researches are carried out on cerium oxide-based catalysts, such as supported cerium-based catalysts synthesized by taking substances such as titanium dioxide nanosheets, molecular sieves, active carbon and the like as carriers, and the catalysts play a role in supplementing acidic sites to a certain extent, but the supported catalysts still have the defects of poor ammonia adsorption capacity, low active window temperature, poor nitrogen selectivity, serious side reactions and the like due to the fact that the surface acidity of the substances such as titanium dioxide, the molecular sieves and the like is still low.

CN110124680a discloses a denitration catalyst using ceria as a base material, comprising: cerium oxide as a base material, an active material and an auxiliary agent, wherein the mass ratio of the cerium oxide to the active material is (72-85): (15-28) the active material comprises ammonium paratungstate, ferric nitrate and cupric nitrate, and the auxiliary agent comprises at least a plasticizer, a reinforcing agent, a binder and a solvent. However, the denitration catalyst provided by the method has low catalytic conversion rate on nitrogen oxides.

CN105561983a discloses a Mn-Ce supported low-temperature denitration catalyst and a preparation method thereof, and the method adopts common chemical reagents such as cerium nitrate, urea and the like to prepare a nano cerium dioxide carrier, and has the advantages of simple and controllable preparation process, good powder dispersibility, fine particles and larger specific surface area. However, the catalyst provided by the method also has the problems of poor nitrogen selectivity, low catalytic conversion rate and the like.

Therefore, it is of great importance to provide a method for improving the acidity and redox ability of the catalyst surface and a denitration catalyst having excellent catalytic effect and a wide use temperature range.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a denitration catalyst and a preparation method and application thereof.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a denitration catalyst comprising a tin niobate nanosheet support and cerium-based active nanospheres supported on the tin niobate nanosheet support.

The denitration catalyst provided by the invention uses the acidic tin niobate nanosheets to load cerium-based active nanospheres, and provides more Lewis acid sites or Lewis acid sites through the acidic tin niobate nanosheets

Acidic sites, thereby increasing the surface acidity and redox capacity of the catalyst and ensuring that the catalyst has higher catalytic activity and nitrogen at a temperature of 150-550 ℃, especially at a temperature of 250-400 ℃ in the optimal use temperature rangeGas selectivity.

Preferably, the cerium-based active nanospheres account for 5-45% of the mass of the tin niobate nanoplatelet carrier, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%, but are not limited to the recited values, and other non-recited values within the range of values are equally applicable, preferably 10-25%.

The invention preferably controls the mass of the cerium-based active nanospheres to occupy the mass of the tin niobate nanosheet carrier within a specific range, and can further regulate and control the synergistic effect of the cerium-based active nanospheres and the tin niobate nanosheets, thereby further improving the catalytic activity and selectivity of the catalyst.

Preferably, the particle size of the cerium-based active nanospheres is 5-10nm, for example, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the tin niobate nanoplatelet carrier contains a first doping element.

Preferably, the first doping element comprises any one or a combination of at least two of iron, samarium, zirconium, copper, cobalt, potassium, sodium, calcium, nickel, manganese, neodymium or aluminum, wherein typical but non-limiting combinations include combinations of iron and samarium, combinations of copper and cobalt or combinations of sodium and copper, preferably sodium and/or copper.

Preferably, the cerium-based active nanospheres contain a second doping element.

Preferably, the second doping element comprises any one or a combination of at least two of neodymium, samarium, cobalt, chromium, silver, zinc, europium, yttrium, dysprosium, zirconium, copper, iron, ytterbium, lanthanum, manganese, or praseodymium, wherein typical but non-limiting combinations include combinations of neodymium and samarium, cobalt and chromium or zirconium and samarium, preferably zirconium and/or samarium.

In a second aspect, the present invention provides a method for preparing a denitration catalyst according to the first aspect of the present invention, the method comprising the steps of:

(1) Mixing a tin-containing compound and a niobium-containing compound, performing a first reaction, and then sequentially performing solid-liquid separation, washing and drying to obtain a tin niobate nanomaterial;

(2) Mixing cerium salt and a surfactant, then adding organic alkali, and performing a second reaction to obtain cerium-based active component colloid;

(3) Grinding the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the condition of stirring, and roasting to obtain the denitration catalyst;

the step (1) and the step (2) have no sequence relation.

The preparation method of the denitration catalyst provided by the invention prepares cerium-based active nanospheres with small particle size so as to form uniform and stable colloid; and mixing the cerium-based active component colloid with the tin niobate nanometer material, and uniformly and fully dispersing cerium-based active nanospheres on the surface of the tin niobate nanometer material to finally obtain the denitration catalyst. The preparation method of the denitration catalyst provided by the invention not only can stably combine the cerium-based active nanospheres and the tin niobate nanosheets, but also can promote the cerium-based active nanospheres to be uniformly dispersed on the tin niobate nanosheets, thereby greatly improving the catalytic activity and selectivity of the denitration catalyst.

The solid-liquid separation method of the present invention is not particularly limited, and may be, for example, filtration or centrifugation.

The washing mode of the present invention is not particularly limited, and for example, washing with water for 2 to 3 times and then washing with ethanol for 2 to 3 times may be used.

In the present invention, the tin-containing compound and the niobium-containing compound in the mixing in step (1) are mixed in a first solvent, which is not particularly limited, and may be deionized water, for example.

In the present invention, the cerium salt and the surfactant are mixed in the second solvent in the mixing in the step (2), and the second solvent is not particularly limited, and may be, for example, ethanol.

Preferably, the chloride containing the first doping element is also added to the mixture of step (1).

Preferably, the first doping element-containing chloride comprises any one or a combination of at least two of ferric chloride, samarium chloride, zirconium chloride, cupric chloride, cobalt chloride, potassium chloride, sodium chloride, calcium chloride, nickel chloride, manganese chloride, neodymium chloride or aluminum chloride, wherein typical but non-limiting combinations include combinations of ferric chloride and samarium chloride, combinations of cupric chloride and cobalt chloride or combinations of sodium chloride and cupric chloride, preferably sodium chloride and/or cupric chloride.

Preferably, the tin-containing compound comprises stannous chloride dihydrate.

Preferably, the niobium-containing compound comprises niobium pentoxide.

Preferably, the molar ratio of tin-containing compound to niobium-containing compound is (0.5-1): 1.25, which may be, for example, 0.5:1.25, 0.6:1.25, 0.7:1.25, 0.8:1.25, 0.9:1.25 or 1:1.25, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the molar ratio of tin-containing compound, first doping element-containing chloride and niobium-containing compound is (0.5-1): (0.05-0.5): 1.25, which may be, for example, 0.5:0.05:1.25, 0.6:0.05:1.25, 0.8:0.05:1.25, 1:0.05:1.25, 0.5:0.1:1.25, 0.5:0.2:1.25, 0.5:0.4:1.25 or 0.5:0.5:1.25, but is not limited to the values recited, other non-recited values within the range of values equally apply, preferably (0.8-1): (0.05-0.2): 1.25.

Preferably, the mixing of step (1) comprises stirring.

Preferably, the stirring time in step (1) is 0.8-1.2h, for example, 0.8h, 0.9h, 1h, 1.1h or 1.2h, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the first reaction comprises a hydrothermal reaction.

Preferably, the temperature of the first reaction is 190-210 ℃, for example 190 ℃, 195 ℃, 200 ℃, 205 ℃ or 210 ℃, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the time of the first reaction is 48-72h, and may be, for example, 48h, 50h, 52h, 55h, 58h, 60h, 62h, 65h, 68h, 70h or 72h, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the drying temperature is 70-90 ℃, for example, 70 ℃, 72 ℃, 75 ℃, 78 ℃, 80 ℃, 82 ℃, 85 ℃, 88 ℃, or 90 ℃, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the drying time is 10-14h, for example, 10h, 11h, 12h, 13h or 14h, but not limited to the recited values, and other non-recited values within the range are equally applicable.

Preferably, the nitrate containing the second doping element is also added to the mixture of step (2).

Preferably, the nitrate containing the second doping element comprises any one or a combination of at least two of neodymium nitrate, samarium nitrate, cobalt nitrate, chromium nitrate, silver nitrate, zinc nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, zirconium nitrate, copper nitrate, iron nitrate, ytterbium nitrate, lanthanum nitrate, manganese nitrate or praseodymium nitrate, wherein typical but non-limiting combinations include a combination of neodymium nitrate and samarium nitrate, a combination of cobalt nitrate and chromium nitrate or a combination of zirconium nitrate and samarium nitrate, preferably zirconium nitrate and/or samarium nitrate.

Preferably, the molar ratio of cerium salt to nitrate containing the second doping element is (0.5-1): (0.05-0.5), which may be, for example, 0.5:0.05, 0.6:0.05, 0.8:0.05, 1:0.05, 0.5:0.2, 0.5:0.4 or 0.5:0.5, but is not limited to the recited values, other non-recited values within the range of values are equally applicable, preferably (0.8-1): (0.05-0.2).

Preferably, the cerium salt comprises cerium nitrate hexahydrate.

Preferably, the surfactant comprises polyvinylpyrrolidone.

Preferably, the polyvinylpyrrolidone has a weight average molecular weight of 45000-58000, for example 45000, 50000, 55000 or 58000, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

The surfactant is preferably added in an amount of 0.005 to 0.1g/mL, for example, 0.005g/mL, 0.008g/mL, 0.01g/mL, 0.02g/mL, 0.04g/mL, 0.06g/mL, 0.08g/mL or 0.1g/mL, but not limited to the values recited, other non-recited values within the numerical range are equally applicable, preferably 0.01 to 0.05g/mL.

The invention preferably controls the addition amount of the surfactant in a specific range, and can regulate and control the structure and the particle size of the nanospheres in the cerium-based active component colloid, thereby further improving the catalytic activity and the nitrogen selectivity of the catalyst.

Preferably, the organic base comprises triethylamine.

The organic base is preferably added in an amount of 0.008 to 0.012mL/mL, for example, 0.008mL/mL, 0.009mL/mL, 0.010mL/mL, 0.011mL/mL or 0.012mL/mL, but the amount is not limited to the values listed, and other values not listed in the numerical range are equally applicable.

Preferably, the stirring is performed after the addition of the organic base in step (2).

Preferably, the stirring time in the step (2) is 8-12min, for example, 8min, 9min, 10min, 11min or 12min, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.

Preferably, the second reaction comprises a hydrothermal reaction.

Preferably, the temperature of the second reaction is 170-190 ℃, for example 170 ℃, 172 ℃, 174 ℃, 176 ℃, 178 ℃, 180 ℃, 182 ℃, 185 ℃, 188 ℃ or 190 ℃, but the second reaction is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the second reaction is carried out for a period of time ranging from 22 to 26 hours, such as 22 hours, 23 hours, 24 hours, 25 hours or 26 hours, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the particle size of the carrier powder in step (3) is 250-420. Mu.m, for example 250 μm, 260 μm, 270. Mu.m, 280 μm, 290 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm or 420 μm, but not limited to the values recited, other non-recited values within the range of values being equally applicable.

Preferably, the evaporating temperature is 70-80 ℃, for example, 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃ or 80 ℃, but the evaporating temperature is not limited to the recited values, and other non-recited values in the numerical range are applicable.

Preferably, the baking temperature is 400-600 ℃, for example, 400 ℃, 420 ℃, 440 ℃, 460 ℃, 480 ℃, 500 ℃, 520 ℃, 540 ℃, 580 ℃, or 600 ℃, but the baking temperature is not limited to the recited values, and other non-recited values in the numerical range are equally applicable.

Preferably, the temperature rising rate of the roasting is 1-10 ℃ per minute, for example, 1 ℃ per minute, 2 ℃ per minute, 3 ℃ per minute, 4 ℃ per minute, 5 ℃ per minute, 6 ℃ per minute, 7 ℃ per minute, 8 ℃ per minute, 9 ℃ per minute or 10 ℃ per minute, but the temperature rising rate is not limited to the listed values, and other values not listed in the numerical range are applicable.

Preferably, the baking time is 3-10h, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

As a preferred technical solution of the second aspect of the present invention, the preparation method includes the following steps:

(1) Mixing a tin-containing compound, a niobium-containing compound and a chloride containing a first doping element, stirring for 0.8-1.2h, then carrying out hydrothermal reaction at 190-210 ℃ for 48-72h, then sequentially carrying out solid-liquid separation and washing, and drying at 70-90 ℃ for 10-14h to obtain a tin niobate nanomaterial;

The mol ratio of the tin-containing compound, the chloride containing the first doping element and the niobium-containing compound is (0.5-1): 0.05-0.5): 1.25;

(2) Mixing cerium salt, surfactant and nitrate containing a second doping element, adding organic alkali, stirring for 8-12min, and performing hydrothermal reaction at 170-190 ℃ for 22-26h to obtain cerium-based active component colloid;

the addition amount of the surfactant is 0.005-0.1g/mL, the addition amount of the organic base is 0.008-0.012mL/mL, and the molar ratio of the cerium salt to the nitrate containing the second doping element is (0.5-1): 0.05-0.5;

(3) Grinding the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 70-80 ℃, and then heating to 400-600 ℃ at 1-10 ℃/min for roasting for 3-10 hours to obtain the denitration catalyst;

the particle size of the carrier powder is 250-420 mu m.

In a third aspect, the present invention provides the use of a denitration catalyst according to the first aspect of the present invention for the reaction of ammonia selective catalytic reduction of nitrogen oxides.

The denitration catalyst provided by the invention has high catalytic activity and selectivity, can be used for treating nitrogen oxides in flue gas, and can be arranged in a mobile source gas denitration device and a fixed source gas denitration device. The mobile source denitration device is not particularly limited, and may be, for example, a diesel engine, a gas turbine, an aeroengine, or the like. The fixed source gas device is not particularly limited, and may be, for example, a device such as an industrial kiln of a thermal power plant, a boiler plant, a coking plant, or a glass plant, a calciner kiln, or the like.

Preferably, the denitration catalyst has an operating temperature window of 150 to 550 ℃, for example, 150 ℃, 160 ℃, 180 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or 500 ℃, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable, preferably 250 to 400 ℃.

Preferably, the denitration catalyst is used for treating nitrogen oxides in flue gas.

Preferably, the mass space velocity of the flue gas is 100 to 500000 mL/(h.g), and for example, 100 mL/(h.g), 100000 mL/(h.g), 200000 mL/(h.g), 400000 mL/(h.g), or 500000 mL/(h.g), but the flue gas is not limited to the recited values, and other non-recited values within the numerical range are equally applicable.

The nitrogen oxide is not particularly limited, and may be, for example, nitrogen monoxide, nitrogen dioxide, or other gas containing two elements of nitrogen and oxygen.

Preferably, the concentration of nitrogen oxide gas in the flue gas is 10-5000ppm, for example, 10ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm or 5000ppm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the volume percentage of oxygen in the flue gas is 5-20%, for example, 5%, 10%, 15% or 20%, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.

Preferably, the concentration of ammonia in the flue gas is 100-5000ppm, for example, 100ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm or 5000ppm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the concentration of sulfur dioxide gas in the flue gas is 10-200ppm, for example, 10ppm, 100ppm, 150ppm, 180ppm or 200ppm, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

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

(1) The denitration catalyst provided by the invention can increase the surface acidity and redox capacity of the whole catalyst by loading the cerium-based active nanospheres with the acidic tin niobate nanosheets, thereby ensuring that the denitration catalyst has higher catalytic activity and nitrogen selectivity and maximum NO in the optimal use temperature range of 250-400 DEG C _x The removal rate can reach more than 97.5 percent, more than 98.1 percent under the preferable condition, more than 97.1 percent of nitrogen selectivity and more than 97.4 percent under the preferable condition.

(2) The preparation method of the denitration catalyst provided by the invention is simple to operate, does not use additives such as sodium hydroxide, ethylene glycol and the like, does not need to adjust pH, and is low in cost, clean and environment-friendly.

(3) The denitration catalyst provided by the invention can be used for treating nitrogen oxides in flue gas, can be arranged in a mobile source gas denitration device and a fixed source gas denitration device, and has a wide application prospect.

Drawings

FIG. 1 is NO of the denitration catalyst described in example 1 of the present invention _x A removal rate result chart;

FIG. 2 is a graph showing the nitrogen selectivity results of the denitration catalyst described in example 1 of the present invention;

FIG. 3 is NO of the denitration catalyst described in example 4 of the present invention _x A removal rate result chart;

FIG. 4 is a graph showing the nitrogen selectivity results of the denitration catalyst described in example 4 of the present invention;

FIG. 5 is NO of the denitration catalyst described in example 5 of the present invention _x A removal rate result chart;

FIG. 6 is a graph showing the nitrogen selectivity results of the denitration catalyst described in example 5 of the present invention;

FIG. 7 is NO of the denitration catalyst described in example 6 of the present invention _x A removal rate result chart;

FIG. 8 is a graph showing the nitrogen selectivity results of the denitration catalyst described in example 6 of the present invention;

FIG. 9 is NO of the denitration catalyst described in example 7 of the present invention _x A removal rate result chart;

FIG. 10 is a graph showing the nitrogen selectivity results of the denitration catalyst described in example 7 of the present invention;

FIG. 11 is NO of the denitration catalyst described in example 8 of the present invention _x A removal rate result chart;

FIG. 12 is a graph showing the nitrogen selectivity results of the denitration catalyst in example 8 according to the present invention;

FIG. 13 is NO of the denitration catalyst described in comparative example 1 of the present invention _x A removal rate result chart;

FIG. 14 is a graph showing the nitrogen selectivity results of the denitration catalyst according to comparative example 1 of the present invention;

FIG. 15 is NO of the denitration catalyst described in comparative example 2 of the present invention _x A removal rate result chart;

FIG. 16 is a graph showing the nitrogen selectivity results of the denitration catalyst according to comparative example 2 of the present invention;

FIG. 17 is NO of the denitration catalyst described in comparative example 3 of the present invention _x A removal rate result chart;

FIG. 18 is a graph showing the nitrogen selectivity results of the denitration catalyst according to comparative example 3 of the present invention.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

The embodiment provides a denitration catalyst, which comprises a tin niobate nanosheet carrier and cerium-based active nanospheres loaded on the tin niobate nanosheet carrier, wherein the mass of the cerium-based active nanospheres is 10% of that of the tin niobate nanosheet carrier, the particle size of the cerium-based active nanospheres is 5-10nm, the tin niobate nanosheet carrier contains sodium element, and the cerium-based active nanospheres contain samarium element.

The embodiment also provides a preparation method of the denitration catalyst, which comprises the following steps:

(1) Mixing stannous chloride dihydrate, niobium pentoxide and sodium chloride with 70mL deionized water, stirring for 1h, then carrying out hydrothermal reaction at 200 ℃ for 60h, sequentially centrifuging, washing for 2 times with water, washing with ethanol for 2 times, and drying in air at 80 ℃ for 12h to obtain a tin niobate nanomaterial;

the molar ratio of stannous chloride dihydrate to sodium chloride to niobium pentoxide is 1:0.05:1.25;

(2) Mixing cerous nitrate hexahydrate, polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) and samarium nitrate hexahydrate with 40mL of ethanol, adding triethylamine, stirring for 10min, and performing hydrothermal reaction at 180 ℃ for 24h to obtain cerium-based active component colloid;

the addition amount of polyvinylpyrrolidone is 0.0088g/mL, the addition amount of triethylamine is 0.01mL/mL, and the molar ratio of cerium nitrate hexahydrate to samarium nitrate hexahydrate is 0.8:0.2;

(3) Grinding 0.310g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 40mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 2

The embodiment provides a denitration catalyst, which comprises a tin niobate nanosheet carrier and cerium-based active nanospheres loaded on the tin niobate nanosheet carrier, wherein the mass of the cerium-based active nanospheres is 5% of that of the tin niobate nanosheet carrier, the particle size of the cerium-based active nanospheres is 5-10nm, the tin niobate nanosheet carrier contains copper elements, and the cerium-based active nanospheres contain samarium elements.

(1) Mixing stannous chloride dihydrate, niobium pentoxide and copper chloride in 70mL deionized water, stirring for 0.8h, then carrying out hydrothermal reaction at 210 ℃ for 48h, sequentially centrifuging, washing for 2 times with water, washing with ethanol for 2 times, and drying in air at 90 ℃ for 10h to obtain a tin niobate nanomaterial;

the molar ratio of stannous chloride dihydrate to copper chloride to niobium pentoxide is 0.8:0.2:1.25;

(2) Mixing cerous nitrate hexahydrate, polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) and samarium nitrate hexahydrate with 40mL of ethanol, adding triethylamine, stirring for 8min, and performing hydrothermal reaction at 190 ℃ for 22h to obtain cerium-based active component colloid;

The addition amount of polyvinylpyrrolidone is 0.005g/mL, the addition amount of triethylamine is 0.012mL/mL, and the molar ratio of cerium nitrate hexahydrate to samarium nitrate hexahydrate is 0.95:0.05;

(3) Grinding 0.654g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 40mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 75 ℃, and then heating to 400 ℃ at 1 ℃/min for roasting for 10 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 3

The embodiment provides a denitration catalyst, which comprises a tin niobate nanosheet carrier and cerium-based active nanospheres loaded on the tin niobate nanosheet carrier, wherein the mass of the cerium-based active nanospheres is 45% of the mass of the tin niobate nanosheet carrier, the particle size of the cerium-based active nanospheres is 5-10nm, the tin niobate nanosheet carrier contains sodium element, and the cerium-based active nanospheres contain samarium element.

(1) Mixing stannous chloride dihydrate, niobium pentoxide and sodium chloride with 70mL deionized water, stirring for 1.2h, then carrying out hydrothermal reaction at 190 ℃ for 72h, sequentially centrifuging, washing for 2 times with water, washing with ethanol for 2 times, and drying in air at 70 ℃ for 14h to obtain a tin niobate nanomaterial;

The molar ratio of stannous chloride dihydrate to sodium chloride to niobium pentoxide is 0.5:0.5:1.25;

(2) Mixing cerous nitrate hexahydrate, polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) and samarium nitrate hexahydrate with 40mL of ethanol, adding triethylamine, stirring for 12min, and performing hydrothermal reaction at 170 ℃ for 26h to obtain cerium-based active component colloid;

the addition amount of polyvinylpyrrolidone is 0.1g/mL, the addition amount of triethylamine is 0.008mL/mL, and the molar ratio of cerium nitrate hexahydrate to samarium nitrate hexahydrate is 0.5:0.5;

(3) Grinding 0.084g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 80mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 70 ℃, and then heating to 600 ℃ at 10 ℃/min for roasting for 3 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 4

This example provides a method for preparing a denitration catalyst, which differs from example 1 only in that no sodium chloride is added in step (1), namely: mixing stannous chloride dihydrate and niobium pentoxide with deionized water, stirring, performing hydrothermal reaction, sequentially centrifuging, washing and drying to obtain a tin niobate nanomaterial; the molar ratio of stannous chloride dihydrate to niobium pentoxide is 1:1.25;

And (2) adding no samarium nitrate hexahydrate, namely mixing cerium nitrate hexahydrate and polyvinylpyrrolidone with ethanol, then adding triethylamine, stirring, and performing hydrothermal reaction to obtain cerium-based active component colloid.

Example 5

The embodiment provides a preparation method of a denitration catalyst, which comprises the following steps:

(1) Mixing stannous chloride dihydrate, niobium pentoxide and samarium chloride with 70mL deionized water, stirring for 1h, then carrying out hydrothermal reaction at 200 ℃ for 60h, sequentially centrifuging, washing for 2 times with water, washing with ethanol for 2 times, and drying in air at 80 ℃ for 12h to obtain a tin niobate nanomaterial;

the molar ratio of stannous chloride dihydrate to sodium chloride to niobium pentoxide is 0.9:0.1:1.25;

(2) Mixing cerous nitrate hexahydrate and polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) with 40mL of ethanol, adding triethylamine, stirring for 10min, and performing hydrothermal reaction at 180 ℃ for 24h to obtain cerium-based active component colloid;

the addition amount of polyvinylpyrrolidone is 0.04g/mL, and the addition amount of triethylamine is 0.01mL/mL;

(3) Grinding 0.206g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 80mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at a speed of 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 6

(1) Mixing stannous chloride dihydrate and niobium pentoxide with 70mL deionized water, stirring for 1h, then carrying out hydrothermal reaction at 200 ℃ for 60h, sequentially centrifuging, washing with water for 2 times, washing with ethanol for 2 times, and drying in air at 80 ℃ for 12h to obtain a tin niobate nanomaterial;

the molar ratio of stannous chloride dihydrate to niobium pentoxide is 1:1.25;

(2) Mixing cerous nitrate hexahydrate, zirconium nitrate pentahydrate and polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) with 40mL of ethanol, adding triethylamine, stirring for 10min, and performing hydrothermal reaction at 180 ℃ for 24h to obtain cerium-based active component colloid;

the addition amount of polyvinylpyrrolidone is 0.05g/mL, and the addition amount of triethylamine is 0.01mL/mL; the molar ratio of the cerium nitrate hexahydrate to the zirconium nitrate pentahydrate is 0.9:0.1;

(3) Grinding 0.189g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 40mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 7

the molar ratio of stannous chloride dihydrate to niobium pentoxide is 1:1.25;

(2) Mixing cerous nitrate hexahydrate, ferric nitrate nonahydrate and polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) with 40mL of ethanol, adding triethylamine, stirring for 10min, and performing hydrothermal reaction at 180 ℃ for 24h to obtain cerium-based active component colloid;

the addition amount of polyvinylpyrrolidone is 0.02g/mL, and the addition amount of triethylamine is 0.01mL/mL; the molar ratio of the cerium nitrate hexahydrate to the ferric nitrate nonahydrate is 0.9:0.1;

(3) Grinding 0.185g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 40mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 8

(1) Mixing stannous chloride dihydrate, aluminum trichloride hexahydrate and niobium pentoxide with 70mL of deionized water, stirring for 1h, performing hydrothermal reaction at 200 ℃ for 60h, sequentially centrifuging, washing with water for 2 times, washing with ethanol for 2 times, and drying in air at 80 ℃ for 12h to obtain a tin niobate nanomaterial;

the molar ratio of stannous chloride dihydrate to aluminum trichloride hexahydrate to niobium pentoxide is 1:0.05:1.25;

(3) Grinding 0.390g of the tin niobate nanometer material obtained in the step (1) to obtain carrier powder, mixing the carrier powder with 80mL of the cerium-based active component colloid obtained in the step (2), evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at a speed of 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst; the particle size of the carrier powder is 250-420 mu m.

Example 9

This example provides a denitration catalyst differing from example 1 only in that the mass of cerium-based active nanospheres is 2% of the mass of tin niobate nanosheet supports.

Example 10

This example provides a denitration catalyst differing from example 1 only in that the mass of cerium-based active nanospheres accounts for 70% of the mass of the tin niobate nanosheet support.

Example 11

This example provides a method for preparing a denitration catalyst, which differs from example 1 only in that the amount of polyvinylpyrrolidone added is 0.001g/mL.

Example 12

This example provides a method for preparing a denitration catalyst, which differs from example 1 only in that the amount of polyvinylpyrrolidone added is 0.5g/mL.

Comparative example 1

The present comparative example provides a preparation method of a denitration catalyst, which comprises the following steps:

(1) The titanium dioxide nanosheets with the length of 80nm are prepared by adopting the method of the example 3 in CN 112007627A;

(3) Mixing the titanium dioxide nanosheets obtained in the step (1) and the cerium-based active component colloid obtained in the step (2), then evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst.

In the denitration catalyst, the mass percentage of cerium-based active nanospheres is the same as that of example 1.

Comparative example 2

(1) Mixing cerous nitrate hexahydrate, polyvinylpyrrolidone (PVP-K30, weight average molecular weight 45000) and samarium nitrate hexahydrate with 40mL of ethanol, adding triethylamine, stirring for 10min, and performing hydrothermal reaction at 180 ℃ for 24h to obtain cerium-based active component colloid;

(2) Mixing the cerium-based active component colloid obtained in the step (2) with a commercially available SBA-15 molecular sieve, then evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst.

Comparative example 3

(2) Mixing the tin niobate nanomaterial obtained in the step (1) with cerium nitrate hexahydrate, then adding 50mL of deionized water, evaporating to dryness under the conditions of stirring and 80 ℃, and then heating to 500 ℃ at 5 ℃/min for roasting for 4 hours to obtain the denitration catalyst.

In the denitration catalyst, the mass percentage of the cerium-based active component is the same as that of the cerium-based active nanospheres in the example 1.

The denitration catalysts in examples 1 to 12 and comparative examples 1 to 3 were used for carrying out denitration activity test on simulated flue gas, and the simulated flue gas had the following components: NH (NH) ₃ 500ppm，NO 500ppm，O ₂ 5, the balance gas was nitrogen, the space velocity was 60000 mL/(h.g), and the maximum NO was measured at a temperature range of 250 to 400 ℃ _x The removal rate and nitrogen selectivity, and the results are shown in Table 1.

TABLE 1

From table 1, the following points can be seen:

(1) As can be seen from the data of examples 1-12, the denitration catalyst provided by the invention has higher surface acidity and redox capacity, and has maximum NO in the optimal use temperature range of 250-400 DEG C _x The removal rate can reach more than 97.5 percent, more than 98.1 percent under the preferable condition, more than 97.1 percent of nitrogen selectivity and more than 97.4 percent under the preferable condition.

(2) As can be seen from a combination of the data of examples 1 and examples 9-10, the mass of cerium-based active nanospheres in example 1 is 10% of the mass of the tin niobate nanoplatelet support, compared to 2% and 70% in examples 9-10, respectively, the maximum NO in example 1 _x The removal rate and the nitrogen selectivity are obviously higher than those of examples 9-10, so that the invention can improve the catalytic activity and the nitrogen selectivity of the catalyst by preferably controlling the mass of the cerium-based active nanospheres to account for the mass percentage of the tin niobate nanosheet carrier.

(3) As can be seen from a combination of the data of examples 1 and examples 11-12, the amount of polyvinylpyrrolidone added in example 1 was 0.0088g/mL, and the maximum NO in example 1 was compared to 0.001g/mL and 0.5g/mL in examples 11-12, respectively _x The removal rate and nitrogen selectivity are obviously higher than those of examples 11-12, so that the catalytic activity and nitrogen selectivity of the catalyst can be improved by preferably controlling the addition amount of polyvinylpyrrolidone.

(4) As can be seen from a combination of comparative example 1 and comparative examples 1 to 3, comparative example 1 uses titanium dioxide to support cerium-based active nanospheres, comparative example 2 uses SBA-15 molecular sieve to support cerium-based active nanospheres, comparative example 3 uses an impregnation method to prepare a denitration catalyst composed of tin niobate nanoplatelets and cerium-based active components, and maximum NO in example 1 _x The removal rate and the nitrogen selectivity are obviously higher than those of comparative examples 1-3, so that the preparation method provided by the invention can improve the catalytic activity and the nitrogen selectivity of the catalyst through the synergistic effect of the tin niobate nanosheets and the cerium-based active nanospheres.

In summary, the denitration catalyst provided by the invention can increase the surface acidity and the oxidation-reduction capability of the whole catalyst by loading the cerium-based active nanospheres on the acidic tin niobate nanosheets, and can be used for the reaction of ammonia selective catalytic reduction of nitrogen oxides.

The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims

1. The denitration catalyst is characterized by comprising a tin niobate nanosheet carrier and cerium-based active nanospheres loaded on the tin niobate nanosheet carrier;

the mass of the cerium-based active nanospheres accounts for 5-45% of the mass of the tin niobate nanosheet carrier.

2. The denitration catalyst according to claim 1, wherein the mass of the cerium-based active nanospheres accounts for 10-25% of the mass of the tin niobate nanosheet carrier.

3. The denitration catalyst of claim 1, wherein the cerium-based active nanospheres have a particle size of 5-10nm.

4. The denitration catalyst of claim 1, wherein the tin niobate nanosheet support contains a first doping element.

5. The denitration catalyst of claim 4, wherein the first doping element comprises any one or a combination of at least two of iron, samarium, zirconium, copper, cobalt, potassium, sodium, calcium, nickel, manganese, neodymium, or aluminum.

6. The denitration catalyst of claim 5, wherein the first doping element is sodium and/or copper.

7. The denitration catalyst of claim 1, wherein the cerium-based active nanospheres contain a second doping element.

8. The denitration catalyst of claim 7, wherein the second doping element comprises any one or a combination of at least two of neodymium, samarium, cobalt, chromium, silver, zinc, europium, yttrium, dysprosium, zirconium, copper, iron, ytterbium, lanthanum, manganese, or praseodymium.

9. The denitration catalyst of claim 8, wherein the second doping element is zirconium and/or samarium.

10. A method for preparing the denitration catalyst as claimed in any one of claims 1 to 9, characterized in that the preparation method comprises the steps of:

the step (1) and the step (2) have no sequence relation.

11. The method of claim 10, wherein a chloride containing the first doping element is further added to the mixture of step (1).

12. The method according to claim 11, wherein the first doping element-containing chloride comprises any one or a combination of at least two of ferric chloride, samarium chloride, zirconium chloride, cupric chloride, cobalt chloride, potassium chloride, sodium chloride, calcium chloride, nickel chloride, manganese chloride, neodymium chloride, and aluminum chloride.

13. The method of claim 12, wherein the first doping element-containing chloride is sodium chloride and/or copper chloride.

14. The method of preparation of claim 10, wherein the tin-containing compound comprises stannous chloride dihydrate.

15. The method of claim 10, wherein the niobium-containing compound comprises niobium pentoxide.

16. The method according to claim 10, wherein the molar ratio of the tin-containing compound to the niobium-containing compound is (0.5-1): 1.25.

17. The method according to claim 11, wherein the molar ratio of the tin-containing compound, the first doping element-containing chloride and the niobium-containing compound is (0.5-1): 0.05-0.5): 1.25.

18. The method according to claim 17, wherein the molar ratio of the tin-containing compound, the first doping element-containing chloride and the niobium-containing compound is (0.8-1): 0.05-0.2): 1.25.

19. The method of claim 10, wherein the mixing of step (1) comprises stirring.

20. The method of claim 19, wherein the stirring in step (1) is performed for a period of 0.8 to 1.2 hours.

21. The method of claim 10, wherein the first reaction is a hydrothermal reaction.

22. The method of claim 10, wherein the temperature of the first reaction is 190-210 ℃.

23. The method of claim 10, wherein the first reaction is for a period of 48-72 hours.

24. The method of claim 10, wherein the drying temperature is 70-90 ℃.

25. The method of claim 10, wherein the drying time is 10 to 14 hours.

26. The method of claim 10, wherein the mixing of step (2) further comprises adding a nitrate containing a second doping element.

27. The method according to claim 26, wherein the nitrate containing the second doping element includes any one or a combination of at least two of neodymium nitrate, samarium nitrate, cobalt nitrate, chromium nitrate, silver nitrate, zinc nitrate, europium nitrate, yttrium nitrate, dysprosium nitrate, zirconium nitrate, copper nitrate, iron nitrate, ytterbium nitrate, lanthanum nitrate, manganese nitrate, and praseodymium nitrate.

28. The method of claim 27, wherein the nitrate containing the second doping element is zirconium nitrate and/or samarium nitrate.

29. The method of claim 26, wherein the molar ratio of cerium salt to nitrate containing the second doping element is (0.5-1): 0.05-0.5.

30. The method of claim 29, wherein the molar ratio of cerium salt to nitrate containing the second doping element is (0.8-1): 0.05-0.2.

31. The method of preparation of claim 10, wherein the cerium salt comprises cerium nitrate hexahydrate.

32. The method of preparation of claim 10, wherein the surfactant comprises polyvinylpyrrolidone.

33. The method of claim 32, wherein the polyvinylpyrrolidone has a weight average molecular weight of 45000-58000.

34. The method according to claim 10, wherein the surfactant is added in an amount of 0.005-0.1g/mL.

35. The method of claim 34, wherein the surfactant is added in an amount of 0.01-0.05g/mL.

36. The method of claim 10, wherein the organic base comprises triethylamine.

37. The method according to claim 10, wherein the organic base is added in an amount of 0.008 to 0.012mL/mL.

38. The method of claim 10, wherein the adding of the organic base in step (2) is followed by stirring.

39. The method of claim 38, wherein the stirring in step (2) is performed for a period of 8 to 12 minutes.

40. The method of claim 10, wherein the second reaction is a hydrothermal reaction.

41. The method of claim 10, wherein the second reaction is at a temperature of 170-190 ℃.

42. The method of claim 10, wherein the second reaction is performed for a period of time ranging from 22 to 26 hours.

43. The method of claim 10, wherein the carrier powder in step (3) has a particle size of 250 to 420 μm.

44. The method according to claim 10, wherein the evaporating temperature is 70-80 ℃.

45. The method of claim 10, wherein the firing temperature is 400-600 ℃.

46. The method of claim 10, wherein the firing is at a rate of 1-10 ℃/min.

47. The method of claim 10, wherein the baking is carried out for a period of 3 to 10 hours.

48. The preparation method according to claim 10, characterized in that the preparation method comprises the steps of:

the particle size of the carrier powder is 250-420 mu m.

49. Use of a denitration catalyst according to any one of claims 1 to 9, characterized in that the denitration catalyst is used for a reaction for the selective catalytic reduction of nitrogen oxides by ammonia.

50. The use according to claim 49, wherein the denitration catalyst has an operating temperature window of 150 to 550 ℃.

51. The use according to claim 50, wherein the denitration catalyst has an operating temperature window of 250 to 400 ℃.