A sulfur-poisoning-resistant denitration and carbon monoxide removal synergistic SCR catalyst and a preparation method thereof

Abstract

The application belongs to the technical field of atmosphere treatment, and provides a sulfur-poisoning-resistant denitration and carbon monoxide removal SCR catalyst and a preparation method thereof. Part of anatase titanium white, platinum nitrate, ammonium metatungstate and water are first mixed to perform first calcination to obtain a precursor powder; the rest of the anatase titanium white, clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerous nitrate, zirconium nitrate and water are second mixed to obtain a slurry; the slurry, the precursor powder, carboxymethyl cellulose ammonia and polyoxyethylene are mixed, and after the pH value is adjusted to be alkaline, kneading and aging are sequentially performed to obtain an aged slurry; the aged slurry is sequentially subjected to extrusion molding, drying and second calcination to obtain the SCR catalyst. The obtained SCR catalyst can efficiently remove nitrogen oxides and carbon monoxide, and also has excellent sulfur-poisoning resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of atmospheric treatment, in particular to an SCR catalyst, a preparation method and application thereof. BACKGROUND

[0002] Nitrogen oxides, as one of the important sources of atmospheric pollution, mainly include N2O, NO, N2O2, N2O3, NO2, N2O4, N2O5, etc., among which NO and NO2 seriously pollute the atmosphere. The emission of nitrogen oxides aggravates environmental deterioration. On the one hand, nitrogen oxides form photochemical smog with hydrocarbons under certain conditions, which destroys the atmospheric environment and harms human health; on the other hand, nitrogen oxides are the main cause of acid rain. In fact, most of the human-emitted nitrogen oxides are derived from the combustion process of fossil fuels. Power generation, steel sintering, waste incineration, glass kiln, cement kiln, etc. are the main sources of nitrogen oxides.

[0003] At present, SNCR or SCR is generally used for flue gas denitrification. SNCR denitrification technology is a selective non-catalytic reduction technology, which sprays an amino reducing agent into the furnace to remove NOx in the flue gas X gases, generating nitrogen and water. SCR denitrification technology is a selective catalytic reduction technology, which sprays an amino reducing agent into the flue gas upstream of the catalyst, and converts NOx in the flue gas into nitrogen and water through the catalyst.

[0004] Some tail gas contains not only nitrogen oxides but also carbon monoxide, such as steel smelting kiln flue gas or coal-fired power plant flue gas. This requires that the SCR catalyst needs to remove carbon monoxide while removing nitrogen oxides. However, the current SCR catalyst has poor resistance to sulfur poisoning. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an SCR catalyst, a preparation method and application thereof. The SCR catalyst prepared by the preparation method provided by the present application can efficiently remove nitrogen oxides and carbon monoxide, and has excellent resistance to sulfur poisoning.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of an SCR catalyst, comprising the following steps:

[0008] Part of the anatase titanium dioxide, platinum nitrate, ammonium metatungstate and water are first mixed to perform first calcination to obtain a precursor powder; the pH value of the first mixed system obtained by the first mixing is 1-3, and the temperature of the first calcination is 700 DEG C;

[0009] mixing the balance of the anatase titanium dioxide, the clay, the stearic acid, the ammonium heptamolybdate, the ammonium metavanadate, the glass fiber, the cerous nitrate, the zirconium nitrate and the water to obtain a slurry;

[0010] mixing the slurry, the precursor powder, the carboxymethyl cellulose ammonia and the polyoxyethylene, adjusting the pH value to be alkaline, and then kneading and aging in sequence to obtain an aged slurry;

[0011] extruding, drying and second calcining the aged slurry in sequence to obtain the SCR catalyst.

[0012] Preferably, the anatase titanium dioxide, the platinum nitrate, the ammonium metatungstate, the clay, the stearic acid, the ammonium heptamolybdate, the ammonium metavanadate, the glass fiber, the cerous nitrate, the zirconium nitrate, the carboxymethyl cellulose ammonia and the polyoxyethylene constitute the solid preparation raw materials;

[0013] The mass percentage of each component in the solid preparation raw materials is:

[0014] The anatase titanium dioxide is 60-85%, the platinum nitrate is 1-3%, the ammonium metatungstate is 1-2%, the clay is 3-5%, the stearic acid is 1-2%, the ammonium heptamolybdate is 1-3%, the ammonium metavanadate is 4-12%, the glass fiber is 1-3%, the cerous nitrate is 1-2%, the zirconium nitrate is 1-2%, the carboxymethyl cellulose ammonia is 1-2%, and the polyoxyethylene is 1-2%.

[0015] Preferably, the temperature of the first mixing is 60-70°C, and the time is 2h; the time of the first calcining is 2h.

[0016] Preferably, the temperature of the second mixing is 60-70°C, and the time is 2-2.5h, and the second mixing is carried out under stirring;

[0017] The water content of the slurry is 30-40%.

[0018] Preferably, the pH value of the alkalinity is 7.5-8.5, and the reagent for adjusting the pH value to be alkaline is ammonia water.

[0019] Preferably, the temperature of the kneading is 50-60°C, and the water content of the slurry obtained by the kneading is 25-28%; the time of the aging is 10-14h.

[0020] Preferably, the extrusion forming includes pre-extruding into a strip and mold extrusion forming in sequence.

[0021] Preferably, the water content of the material obtained by the drying is less than or equal to 5%;

[0022] The temperature of the second calcining is 500-600°C, and the time is 30-32h.

[0023] The application further provides the SCR catalyst prepared by the preparation method.

[0024] The application further provides application of the SCR catalyst in flue gas treatment, wherein the flue gas comprises nitrogen oxides, carbon monoxide and sulfur dioxide.

[0025] The application provides a preparation method of an SCR catalyst, and has the following effects:

[0026] 1. Element doping: Zr is introduced to optimize the surface properties of the SCR catalyst and enhance the sulfur poisoning resistance; and the doping of Ce helps to improve the denitration and carbon monoxide removal activity.

[0027] 2. A precursor powder is prepared from platinum nitrate, anatase titanium white and ammonium metatungstate, and is introduced into the catalyst carrier, so that a multi-layer catalyst carrier structure is formed, thereby improving the sulfur poisoning resistance and simultaneously achieving the denitration and carbon monoxide removal capacity.

[0028] 3. Carrier optimization: the SCR catalyst with a Ti-Si-W carrier is prepared from anatase titanium white, clay and ammonium metatungstate.

[0029] The SCR catalyst of the application can be applied to industrial scenes where nitrogen oxides, carbon monoxide and sulfur pollution exist simultaneously, such as tail gas treatment in coal-fired power plants and steel plants. The SCR catalyst of the application is expected to replace the traditional SCR catalyst due to its advantages of sulfur poisoning resistance and high carbon monoxide removal efficiency, thereby improving the pollutant treatment efficiency, reducing the cost and maintenance burden caused by frequent replacement of the catalyst due to poisoning, and having good application and promotion value. DETAILED DESCRIPTION

[0030] The application provides a preparation method of an SCR catalyst, comprising the following steps:

[0031] Part of the anatase titanium white, platinum nitrate, ammonium metatungstate and water are first mixed to perform first calcination to obtain a precursor powder; the pH value of the first mixed system obtained by the first mixing is 1-3, and the temperature of the first calcination is 700 DEG C;

[0032] The remaining anatase titanium white, clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate and water are second mixed to obtain a slurry;

[0033] The slurry, the precursor powder, carboxymethyl cellulose ammonia and polyoxyethylene are mixed, and after the pH value is adjusted to be alkaline, kneading and aging are sequentially performed to obtain an aged slurry;

[0034] The aged slurry is sequentially subjected to extrusion molding, drying and second calcination to obtain the SCR catalyst.

[0035] The raw materials used in the present application are preferably commercially available products, unless otherwise specified.

[0036] The present application first mixes part of the anatase titanium dioxide, platinum nitrate, ammonium metatungstate and water, and then performs first calcination to obtain a precursor powder; the pH value of the first mixed system is 1-3, and the temperature of the first calcination is 700°C.

[0037] In the present application, the specific surface area of the anatase titanium dioxide (TiO2) is preferably 90-110 m 2 / g, and the average particle size is preferably 0.8-1.2 μm. 50 In the present application, the main function of the anatase titanium dioxide is to constitute the main structure of the SCR catalyst, and the large specific surface area serves as a carrier for the active components.

[0038] In the present application, the platinum nitrate is preferably used in the form of a platinum nitrate solution, and the concentration of the platinum nitrate solution is preferably 10 wt%. In the present application, the platinum nitrate can provide platinum elements to perform carbon monoxide removal reactions.

[0039] In the present application, the ammonium metatungstate serves as a cocatalyst to improve the sintering resistance of the SCR catalyst.

[0040] In the present application, the temperature of the first mixing is preferably 60-70°C, and the time is preferably 2 h. In the present application, the first mixing is preferably performed in a kneader.

[0041] In the present application, the water content of the first mixed system obtained by first mixing part of the anatase titanium dioxide, platinum nitrate, ammonium metatungstate and water is preferably 30-35%, and the pH value is 1-3. In the present application, the pH value of the first mixed system is 1-3, which is beneficial to the exertion of the platinum catalytic performance.

[0042] In the present application, the first mixing of part of the anatase titanium dioxide, platinum nitrate, ammonium metatungstate and water preferably includes the following steps: adding the platinum nitrate solution and the ammonium metatungstate to part of the anatase titanium dioxide, adjusting the water content of the obtained mixed system to 30-35%, then adjusting the pH value to 1-3, and finally increasing the temperature to 60-70°C and stirring for 2 h. In the present application, the reagent used to adjust the pH value to 1-3 is preferably nitric acid.

[0043] After the first mixing and before the first calcination, the present application preferably further includes performing steam water, and the water content of the mud obtained by the steam water is preferably 25-30%.

[0044] In the present application, the temperature of the first calcination is 700 DEG C, and the time is preferably 2h. In the present application, the first calcination is preferably carried out in an air atmosphere. In the present application, the temperature of the first calcination is controlled to be 700 DEG C, which is more advantageous to improve the catalytic activity of platinum.

[0045] After the first calcination, the present application preferably further comprises: grinding and sieving the powder to pass through a 100 mesh screen to obtain the precursor powder.

[0046] The first calcination at 700 DEG C under the condition of pH value of 1-3 in the present application can improve the acid active sites of the precursor powder, and thus is advantageous to improve the resistance to sulfur dioxide poisoning of the final catalyst; meanwhile, the preparation of the precursor powder from the platinum nitrate and part of the anatase titanium white powder is advantageous to improve the performance of platinum in removing carbon monoxide, and finally is advantageous to improve the efficiency of the SCR catalyst in removing carbon monoxide.

[0047] In the present application, the rest of the anatase titanium white powder, the clay, the stearic acid, the ammonium heptamolybdate, the ammonium metavanadate, the glass fiber, the cerium nitrate, the zirconium nitrate and water are secondly mixed to obtain a slurry.

[0048] In the present application, the specific surface area of the clay is preferably 50-60 m 2 / g, the particle size D 90 is preferably ≤18 μm, and specifically preferably 15-18 μm. In the present application, the main components of the clay preferably include SiO2 and MgO; the content of aluminum in the clay is low. In the present application, the main function of the clay is to constitute the main structure of the SCR catalyst, and the large specific surface area, low thermal expansion coefficient and high stability improve the sintering resistance of the SCR catalyst in a high temperature environment.

[0049] In the present application, the stearic acid can reduce the friction and is beneficial to the extrusion demolding.

[0050] In the present application, the ammonium heptamolybdate can improve the denitration activity of the catalyst.

[0051] In the present application, the ammonium metavanadate is the main active component of the SCR catalyst.

[0052] In the present application, the main components of the glass fiber preferably include SiO2, Al2O3, CaO, B2O3, MgO and Na2O; the glass fiber plays a role of framework in the SCR catalyst and improves the structural strength of the SCR catalyst. In the present application, the single filament diameter of the glass fiber is preferably 13-16 μm, and the length is preferably 6 mm.

[0053] In the present application, the cerium nitrate is helpful to improve the denitration and carbon monoxide removal activities.

[0054] In the present application, the zirconium nitrate can improve the sulfur poisoning resistance of the SCR catalyst.

[0055] In the present application, the water is preferably deionized water.

[0056] In the present application, the temperature of the second mixing is preferably 60-70℃, and more preferably 65℃; and the time is preferably 2-2.5h. In the present application, the second mixing is preferably carried out under stirring. In the present application, the second mixing is preferably carried out in a kneader.

[0057] In the present application, the water content of the slurry is preferably 30-40%.

[0058] After obtaining the slurry and the precursor powder, the present application mixes the slurry, the precursor powder, carboxymethyl cellulose ammonia and polyoxyethylene, adjusts the pH value to be alkaline, and then carries out kneading and aging in sequence to obtain aged slurry.

[0059] In the present application, the viscosity of the carboxymethyl cellulose ammonia is preferably 100-200mpa·s. In the present application, the carboxymethyl cellulose ammonia can improve the water absorption and water retention of the slurry and improve the plasticity of the slurry while serving as a pore-forming agent.

[0060] In the present application, the viscosity of the polyoxyethylene is preferably 250-350mpa·s. In the present application, the polyoxyethylene can improve the plasticity of the slurry while serving as a thickening agent, a flocculating agent and a lubricant.

[0061] In the present application, the pH value of the alkalinity is preferably 7.5-8.5, and the reagent for adjusting the pH value to be alkaline is preferably ammonia water. The present application does not specifically limit the concentration and the amount of the ammonia water, and the pH value can be 7.5-8.5.

[0062] In the present application, the temperature of the kneading is preferably 50-60℃, and the kneading is preferably carried out in a kneader. In the present application, the water content of the slurry obtained by the kneading is preferably 25-28%, and the time of the kneading is not specifically limited as long as the water content of the slurry obtained by the kneading is 25-28%. In the present application, the time of the aging is preferably 10-14h, and more preferably 12h; and the slurry obtained by the kneading is preferably sealed with a preservative film during the aging.

[0063] After obtaining the aged slurry, the present application carries out extrusion molding, drying and second calcination in sequence to obtain the SCR catalyst.

[0064] In the present application, the extrusion molding preferably comprises sequentially pre-extruding into a strip and mold extrusion molding. In the present application, the pre-extruding into a strip is preferably performed on a pre-extruder, and the pre-extruding into a strip can obtain a strip-shaped clay. In the present application, the mold extrusion molding obtains a 35-hole honeycomb catalyst with an inner wall thickness of 0.55 mm and an outer wall thickness of 0.95 mm.

[0065] In the present application, the water content of the dried material is less than or equal to 5%; the drying is preferably performed in a drying room, and the present application does not specifically limit the parameters of the drying, as long as the water content of the dried material is less than or equal to 5%.

[0066] In the present application, the temperature of the second calcination is preferably 500-600°C, and further preferably 550°C; the time is preferably 30-32h. In the present application, the second calcination is preferably performed in a mesh belt kiln.

[0067] In the application, the solid preparation raw materials are composed of anatase titanium dioxide, platinum nitrate, ammonium metatungstate, kaolin, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate, carboxymethyl cellulose ammonia and polyoxyethylene; the mass percentage of each component in the solid preparation raw materials is preferably: anatase titanium dioxide 60-85%, platinum nitrate 1-3%, ammonium metatungstate 1-2%, kaolin 3-5%, stearic acid 1-2%, ammonium heptamolybdate 1-3%, ammonium metavanadate 4-12%, glass fiber 1-3%, cerium nitrate 1-2%, zirconium nitrate 1-2%, carboxymethyl cellulose ammonia 1-2% and polyoxyethylene 1-2%. In the application, the mass percentage of anatase titanium dioxide in the solid preparation raw materials is specifically preferably 60%, 63%, 65%, 68.5%, 70%, 72.5%, 75%, 76%, 80%, 82% or 85%. In the application, the mass percentage of platinum nitrate in the solid preparation raw materials is specifically preferably 1%, 1.5%, 2%, 2.5% or 3%. In the application, the mass percentage of ammonium metatungstate in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%. In the application, the mass percentage of kaolin in the solid preparation raw materials is specifically preferably 3%, 3.5%, 4%, 4.5% or 5%. In the application, the mass percentage of stearic acid in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%. In the application, the mass percentage of ammonium heptamolybdate in the solid preparation raw materials is specifically preferably 1%, 1.5%, 2%, 2.5% or 3%. In the application, the mass percentage of ammonium metavanadate in the solid preparation raw materials is specifically preferably 4%, 6%, 8%, 10% or 12%. In the application, the mass percentage of glass fiber in the solid preparation raw materials is specifically preferably 1%, 1.5%, 2%, 2.5% or 3%. In the application, the mass percentage of cerium nitrate in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%. In the application, the mass percentage of zirconium nitrate in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%. In the application, the mass percentage of carboxymethyl cellulose ammonia in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%. In the application, the mass percentage of polyoxyethylene in the solid preparation raw materials is specifically preferably 1%, 1.5% or 2%.

[0068] In the application, the mass ratio of the partial anatase titanium dioxide to the residual anatase titanium dioxide is preferably 1:4.

[0069] Compared with the traditional noble metal supported catalyst, the preparation method of the application is simpler, and has the abilities of denitration, carbon monoxide removal and sulfur poisoning resistance. The composition of flue gas for denitration is complex, and the moisture content is high. Compared with the noble metal catalyst prepared by the spraying method, the method of the application does not worry about the problems of coating falling off, oxidation and being covered by ash due to the complexity of flue gas for denitration and the high ash content.

[0070] The application further provides the SCR catalyst prepared by the preparation method.

[0071] The application further provides application of the SCR catalyst in flue gas treatment.

[0072] In the application, the flue gas at the inlet comprises the following concentration components:

[0073] Inlet NO X 200 ppm, CO 2500 ppm, 10 v.% O2, SO2 0~100 ppm.

[0074] In the application, the concentration of SO2 in the flue gas is preferably 0 ppm or 100 ppm.

[0075] In the application, the molar ratio of ammonia nitrogen in the flue gas is preferably 1.

[0076] In the application, the space velocity of the flue gas is preferably 3000 h -1 .

[0077] The SCR catalyst, the preparation method and the application thereof provided by the application are described in detail below in combination with examples, but they should not be understood as limitations to the protection scope of the application.

[0078] Examples

[0079] The formula of the solid preparation raw material of the SCR catalyst in Examples 1~3 and Comparative Examples 1~3 is shown in Table 1.

[0080] Table 1 Formula of solid preparation raw material of the SCR catalyst in Examples and Comparative Examples

[0081]

[0082] In the application, the specific surface area of the anatase titanium white powder is 90~100 m 2 / g, the particle size D 50 is 0.8~1.2 μm; the specific surface area of the clay is 50~60 m 2 / g, the particle size D 90 is 15~18 μm; the viscosity of the carboxymethyl cellulose ammonia is 100~200 mpa·s, the viscosity of the polyoxyethylene is 250~350 mpa·s; the monofilament diameter of the glass fiber is 13~16 μm, and the length is 6 mm.

[0083] The preparation method of the above-mentioned SCR catalyst is as follows:

[0084] (1) Preparation of precursor powder: take 1 / 5 of total amount of anatase titanium white powder into a kneader, add platinum nitrate solution (10wt%), ammonium metatungstate into the anatase titanium white powder, control the moisture content to be 30-35%, adjust the pH value to 1-3 by using nitric acid, heat to 60-70°C and stir for 2h until the mud is uniform, evaporate water to 25-30% of the mud to form granules, take out the mud, calcine at 700°C for 2h, grind and sieve the powder to pass through a 100 mesh sieve, and collect the precursor powder.

[0085] (2) Put the remaining 4 / 5 of the anatase titanium white powder, clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate and deionized water into the kneader, heat to 60-70°C and stir for 2h until the mud is uniform, control the amount of deionized water added, and obtain a mud with a water content of 30-35wt%.

[0086] (3) In the mud, continue to add the precursor powder, carboxymethyl cellulose ammonia and polyoxyethylene, add ammonia water to adjust the pH value of the system to 7.5-8.5, stir the mud under the heating state (50-60°C) of the kneader until the moisture content of the mud is 25wt%, take out the mud and seal it with plastic preservative film, and age for 12h to obtain aged mud.

[0087] (4) The mud is extruded into a block-shaped mud by a pre-extruder, the block-shaped mud is put into an extruder, and the honeycomb catalyst is extruded into a 35-hole honeycomb catalyst with an inner wall thickness of 0.55mm and an outer wall thickness of 0.95mm by a mold. Put the honeycomb catalyst into a drying room for water loss drying until the water content of the catalyst is less than 5wt%, put it into a mesh belt kiln for calcination, the calcination temperature is 550°C, and the calcination time is 30h, to obtain the SCR catalyst sample.

[0088] Comparative Example 4

[0089] The difference from Example 1 is that the operation of step (1) is omitted, and the platinum nitrate solution and ammonium metatungstate are directly mixed with clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate, etc. in step (2), and the rest is the same as Example 1.

[0090] Comparative Example 5

[0091] The difference from Example 1 is that the calcination step in step (1) is cancelled, and the rest is the same as Example 1.

[0092] Comparative Example 6

[0093] The difference from Example 1 is that the pH value in step (1) is adjusted to 4-5, and the rest is the same as Example 1.

[0094] The composition of the obtained SCR catalyst was tested by X-ray fluorescence spectroscopy, and the results are shown in Table 2.

[0095] Table 2 Composition of the obtained SCR catalyst of the examples and comparative examples

[0096]

[0097] As can be seen from Table 2, each component changes with the change of the addition amount, and there is no other abnormal condition.

[0098] The specific surface area of the obtained SCR catalyst was tested by BET method, and the results are shown in Table 3.

[0099] Table 3 Specific surface area data of the obtained SCR catalyst of the examples and comparative examples

[0100]

[0101] As can be seen from Table 3, in Examples 1-3 and Comparative Examples 1-3 and 6, the specific surface area of the obtained SCR catalyst changes, which is due to the increase of the proportion of anatase titanium white powder, as a carrier, the specific surface area of anatase titanium white powder is higher than that of clay, and this situation still exists after calcination. Comparative Examples 4 and 5 lack the calcination process of step 1, and the material is not subjected to secondary calcination, so the specific surface area is higher than that of Example 1.

[0102] The compressive strength of the obtained SCR catalyst was tested by GB / 31587-2015 method, and the results are shown in Table 4.

[0103] Table 4 Compressive strength data of the obtained SCR catalyst of the examples and comparative examples

[0104]

[0105] As can be seen from Table 4, the changes of zirconium, cerium and platinum nitrate have no obvious effect on the compressive strength of the SCR catalyst.

[0106] The prepared SCR catalyst was tested at a flue gas temperature of 280℃, and the working conditions were as follows: X Gas 1: inlet NO 200ppm, CO 2500ppm, 10v.%O2, ammonia nitrogen molar ratio 1, space velocity 3000h-1 -1 Under these conditions, the denitration efficiency can reach more than 80%. The test conditions are based on GBT31587-2015 honeycomb flue gas denitration catalyst, the aging time is 30h, and the gas composition and content are tested every 1h. The test device used is an SCR flue gas denitration test device produced by Tianjin Aoxuan Technology Co., Ltd.

[0107] Gas 2: inlet NO X200ppm, CO 2500ppm, 10v.%O2, SO2 gas 100ppm, ammonia nitrogen molar ratio 1. Test conditions GBT31587-2015 honeycomb flue gas denitration catalyst is standard, aging time is 72h, test gas composition and content every 1h. The test equipment used is SCR flue gas denitration test device produced by Tianjin Ao Zhan Technology Co., Ltd.

[0108] The denitration and CO removal efficiency of the SCR catalyst without passing in sulfur dioxide is shown in Table 5.

[0109] Table 5 Denitration and CO removal efficiency without passing in sulfur dioxide

[0110]

[0111] The denitration and CO removal efficiency of the SCR catalyst after passing in sulfur dioxide is shown in Table 6.

[0112] Table 6 Denitration and CO removal efficiency of the SCR catalyst after passing in sulfur dioxide

[0113]

[0114] It can be seen from Table 5 that: compared with Example 2, the Comparative Example 1 omitted zirconium nitrate in the preparation raw material, so that the sulfur poisoning resistance decreased, which indicated that the zirconium element doping helped to improve the sulfur poisoning resistance; compared with Example 2, the Comparative Example 2 omitted cerium nitrate, so that the denitration and carbon monoxide removal efficiency decreased more obviously, which indicated that the doping of cerium element helped to improve the denitration and carbon monoxide removal activity; compared with Example 2, the Comparative Example 3 omitted platinum nitrate, so that the carbon monoxide removal efficiency decreased obviously, which indicated that in the process of removing carbon monoxide, platinum element played a leading role; compared with Comparative Example 1, the Comparative Example 4 omitted the preparation process of the precursor powder, so that the carbon monoxide removal efficiency decreased obviously, which indicated that in the preparation of the denitration and carbon monoxide removal catalyst, the uniformity of the active component in the carrier and the acidity of the catalyst carrier surface needed to be considered, and the simultaneous addition of the acidic active component and the alkaline active component material might affect the distribution of the active component on the surface of the catalyst material, further affect the active site distribution on the surface of the catalyst material, affect the oxidation reaction of the carbon monoxide removal, and also affect the reduction reaction of the nitrogen oxide removal. Compared with Comparative Example 1, the Comparative Example 5 omitted the precursor calcination process, retained the adjustment of the acidification process, and without the calcination process, the test results were similar to those of Comparative Example 4, and the problem of efficiency decrease caused by the mutual influence of the active components was not solved. Compared with Comparative Example 1, the Comparative Example 6 lacked the acidification process, and the carbon monoxide removal efficiency decreased.

[0115] From table 6, it can be seen that: by comparing the efficiency of the sample after aging by passing sulfur dioxide, it is found that the denitration and decarburization efficiency of examples 1-3 is less affected, and the efficiency of comparative examples 1-3 is greatly affected, which shows that the SCR catalyst obtained by examples 1-3 is not easy to be poisoned by sulfur dioxide. Comparative example 1 omits zirconium nitrate and adds cerium nitrate, which reduces the sulfur poisoning resistance of the SCR catalyst, but ensures high denitration activity, comparative example 2 omits cerium nitrate and adds zirconium nitrate, which improves the sulfur poisoning resistance of the SCR catalyst, but reduces the denitration activity; after passing sulfur dioxide, the denitration activity of the SCR catalyst obtained by comparative example 1 is higher than that of the SCR catalyst obtained by comparative example 2. After omitting platinum nitrate in comparative example 3, the denitration and decarburization efficiency decreases sharply, which shows that the addition of platinum nitrate plays a major role in removing carbon monoxide. In comparative example 4 and comparative example 5, the efficiency of removing carbon monoxide decreases more obviously, which shows that the addition method of the two active components affects the sulfur poisoning resistance, and in the preparation process of the denitration and decarburization catalyst, the sulfur poisoning resistance of the layered catalyst carrier system is stronger. After passing sulfur dioxide, the efficiency of removing carbon monoxide in comparative example 6 compared with example 1 decreases, which shows that acidizing the precursor improves the sulfur poisoning resistance of the catalyst for removing carbon monoxide.

[0116] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method for the preparation of an SCR catalyst, characterized in that The method comprises the following steps: Part of the anatase titanium dioxide, platinum nitrate, ammonium metatungstate and water are first mixed to perform first calcination to obtain a precursor powder; The pH value of the first mixed system obtained by the first mixing is 1-3, and the temperature of the first calcination is 700 DEG C; The rest of the anatase titanium dioxide, clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate and water are second mixed to obtain a slurry; The slurry, the precursor powder, carboxymethyl cellulose ammonium and polyoxyethylene are third mixed, and after the pH value is adjusted to be alkaline, kneading and aging are sequentially performed to obtain an aged slurry; The aged slurry is sequentially subjected to extrusion molding, drying and second calcination to obtain the SCR catalyst; The anatase titanium dioxide, platinum nitrate, ammonium metatungstate, clay, stearic acid, ammonium heptamolybdate, ammonium metavanadate, glass fiber, cerium nitrate, zirconium nitrate, carboxymethyl cellulose ammonium and polyoxyethylene constitute solid preparation raw materials; The mass percentage of each component in the solid preparation raw materials is: The anatase titanium dioxide is 60-85%, the platinum nitrate is 1-3%, the ammonium metatungstate is 1-2%, the clay is 3-5%, the stearic acid is 1-2%, the ammonium heptamolybdate is 1-3%, the ammonium metavanadate is 4-12%, the glass fiber is 1-3%, the cerium nitrate is 1-2%, the zirconium nitrate is 1-2%, the carboxymethyl cellulose ammonium is 1-2% and the polyoxyethylene is 1-2%; the sum of the mass percentages of each component in the solid preparation raw materials is 100%; The temperature of the second calcination is 500-600 DEG C, and the time is 30-32 h.

2. The production method according to claim 1, characterized by, The temperature of the first mixing is 60-70 DEG C, and the time is 2 h; the time of the first calcination is 2 h.

3. The preparation method according to claim 1, characterized in that, The temperature of the second mixing is 60-70 DEG C, and the time is 2-2.5 h, and the second mixing is performed under stirring; The water content of the slurry is 30-40%.

4. The method of claim 1, wherein, The pH value of the alkalinity is 7.5-8.5, and the reagent for adjusting the pH value to be alkaline is ammonia water.

5. The preparation method according to claim 1, characterized in that, The temperature of the kneading is 50-60 DEG C, the water content of the slurry obtained by the kneading is 25-28%, and the time of the aging is 10-14 h.

6. The method of claim 1, wherein, The extrusion molding comprises sequentially performing pre-extrusion into a strip and mold extrusion molding.

7. The preparation method according to claim 1, characterized in that, The water content of the obtained material after drying is less than or equal to 5%.

8. The SCR catalyst prepared by the preparation method of any one of claims 1-7.

9. Use of the SCR catalyst according to claim 8 in flue gas treatment, characterized in that, The flue gas comprises nitrogen oxides, carbon monoxide and sulfur dioxide.

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