CN114632537A - Integral denitration catalyst and preparation method and application thereof - Google Patents
Integral denitration catalyst and preparation method and application thereof Download PDFInfo
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- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 24
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- 238000000034 method Methods 0.000 claims abstract description 20
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- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 26
- 239000002808 molecular sieve Substances 0.000 claims description 22
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 22
- 239000011148 porous material Substances 0.000 claims description 19
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- FPCJKVGGYOAWIZ-UHFFFAOYSA-N butan-1-ol;titanium Chemical compound [Ti].CCCCO.CCCCO.CCCCO.CCCCO FPCJKVGGYOAWIZ-UHFFFAOYSA-N 0.000 claims description 9
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 9
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- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
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- 239000000463 material Substances 0.000 claims description 3
- 238000000746 purification Methods 0.000 claims description 3
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 2
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- 238000001771 vacuum deposition Methods 0.000 claims description 2
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- 230000000694 effects Effects 0.000 description 6
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
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- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
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- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
-
- B01J35/56—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
- B01J37/0219—Coating the coating containing organic compounds
Abstract
The invention provides an integral denitration catalyst and a preparation method and application thereof, wherein the preparation method comprises the following steps: the preparation method comprises the steps of sequentially adding the thickening agent, the active component powder, the binder and the coating auxiliary agent into deionized water under the stirring condition, uniformly mixing to obtain the catalyst slurry, strictly limiting the adding sequence of each ingredient, avoiding agglomeration of the active component powder, avoiding grinding steps, completing the preparation of the catalyst slurry only by stirring, reducing the preparation flow of the integral denitration catalyst, reducing the technical difficulty and the production cost, having the advantages of simple process, safe operation and the like, and further being capable of enabling the temperature window of the integral denitration catalyst to be wide, uniform in coating and convenient for industrial application.
Description
Technical Field
The invention relates to the technical field of motor vehicle exhaust purification, and relates to an integral denitration catalyst, and a preparation method and application thereof.
Background
Diesel engines are widely used in road transportation due to their high combustion efficiency and high power, and nitrogen oxides emitted from diesel vehicles account for 88.8% of the total amount of emissions of automobiles according to the annual regulations of chinese environmental regulations (2021). NOxIs an important atmospheric pollutant and can cause environmental problems such as photochemical smog, haze and the like. The emission control requirement of diesel vehicles in China is increasingly strict, and national six standards are comprehensively implemented in 7 months in 2021 for NOxThe emission limit of (a) is significantly tightened.
Ammonia selective catalytic reduction (NH)3-SCR) is currently the mainstream technology for nitrogen oxide purification, using urea/ammonia etc. as a reducing agent to selectively catalyze and reduce nitrogen oxides into nitrogen gas and water. The SCR denitration technology is the most mature and widely used denitration technology at home and abroad, and the SCR denitration catalyst is the core of the denitration technology. The SCR catalyst types can be divided into three types: plate, honeycomb, and corrugated plate. For engines such as diesel engines, a honeycomb SCR denitration catalyst is generally used.
Currently, diesel vehicle NH3SCR catalysts are generally formed by coating, i.e. the catalyst powder is slurried and then applied to a honeycomb support. The current coating process mainly comprises an immersion method and a vacuum method. For example, CN105688892B discloses a preparation method of a honeycomb-shaped SCR denitration catalyst, which comprises pretreating the surface of a honeycomb-shaped cordierite ceramic; preparation of active component MnO of catalystxUniformly dispersing the powdery catalyst in silica sol to prepare a mixed solution; pre-treating the surfaceAnd immersing the honeycomb cordierite ceramic in the mixed solution, taking out the honeycomb cordierite ceramic, and performing heat treatment to obtain the honeycomb SCR denitration catalyst loaded with the active component. For example, CN104353485A discloses a preparation method of a honeycomb carrier catalyst for molecular sieve denitration, which comprises the steps of preparing a Cu/ZSM-5 catalyst, mixing the Cu/ZSM-5 catalyst with a binder and the like to prepare a slurry, putting a pretreated cordierite honeycomb ceramic carrier into the slurry, drying and roasting the cordierite honeycomb ceramic carrier to complete primary coating, putting the cordierite honeycomb ceramic carrier subjected to primary coating into the slurry, drying again and roasting the cordierite honeycomb ceramic carrier to complete secondary coating, and thus obtaining the honeycomb carrier molecular sieve denitration catalyst. The two technical schemes both belong to an impregnation method, and although the prepared denitration catalyst has good low-temperature activity, the impregnation method is low in coating rate and difficult to control the wall thickness uniformly.
CN109499607A discloses a vacuum method pumping coating molecular sieve process, in particular to a preparation method of a copper-iron composite honeycomb coating type denitration catalyst, which comprises the following steps: preparing an active component, preparing a binder, preparing active component slurry, pretreating a carrier, putting the pretreated carrier into a ceramic cavity, sucking the active component slurry into a cordierite pore channel by a vacuum pumping method, taking out, blowing out residual liquid in the pore channel, and sequentially drying and roasting to finish primary coating; and then coating can be repeated for 1-3 times according to the needs. The technical method adopts a vacuum method for coating, has good activity and sulfur resistance, but uses a dangerous product nitric acid in the process flow, has a certain requirement on the particle size of a molecular sieve, cannot directly apply the initially prepared powder to coating, needs to be ground again in the midway, and has a long preparation period.
In summary, aiming at the defects of the preparation process of the monolithic denitration catalyst in the prior art, especially the problem that the active component slurry is easy to agglomerate in the preparation process, which leads to long-time grinding, a novel preparation method of the monolithic denitration catalyst needs to be provided, which not only omits the grinding step, has the advantages of simple process, safe operation and the like, but also can ensure that the temperature window of the monolithic denitration catalyst is wide, the coating is uniform, and the preparation method is convenient for industrial application.
Disclosure of Invention
In view of the problems in the prior art, the invention provides an integral denitration catalyst, a preparation method and an application thereof, wherein the preparation method comprises the following steps: the preparation method comprises the steps of sequentially adding the thickening agent, the active component powder, the binder and the coating auxiliary agent into deionized water under the stirring condition, uniformly mixing to obtain the catalyst slurry, strictly limiting the adding sequence of each ingredient, avoiding agglomeration of the active component powder, avoiding grinding steps, completing the preparation of the catalyst slurry only by stirring, reducing the preparation flow of the integral denitration catalyst, reducing the technical difficulty and the production cost, having the advantages of simple process, safe operation and the like, and further being capable of enabling the temperature window of the integral denitration catalyst to be wide, uniform in coating and convenient for industrial application.
In order to achieve the purpose, the invention adopts the following technical scheme:
one of the purposes of the invention is to provide a preparation method of an integral denitration catalyst, which comprises the following steps:
(1) weighing a certain amount of deionized water, sequentially adding a thickening agent, active component powder, a binder and a coating auxiliary agent under the stirring condition, and uniformly mixing to obtain catalyst slurry;
(2) under the negative pressure condition, vacuum coating the catalyst slurry obtained in the step (1) on the surfaces of the pore channels of the honeycomb carrier to obtain a catalyst blank;
(3) and (3) drying and roasting the catalyst blank obtained in the step (2) in sequence to obtain the integral denitration catalyst.
In the prior art, certain particle size requirements are met in the preparation process of the catalyst slurry, and meanwhile, in the preparation process, catalyst powder is easy to agglomerate, so that grinding is inevitably needed in the preparation process.
It is worth noting that the preparation method of the invention does not specifically limit the kind and preparation method of the active component powder, and the active component powder can be obtained by drying the active component powder at 100-120 ℃ for 12-16 h and then roasting the active component powder at 550-830 ℃ for 4-6 h by adopting conventional active component powder preparation methods in the prior art such as a hydrothermal method, an ion exchange method, filter pressing and the like.
As a preferable technical scheme of the invention, the thickening agent in the step (1) comprises hydroxycellulose and/or polyacrylic acid.
Preferably, in the step (1), the thickening agent is added to make the viscosity of the system between 3500 and 9000 mPa-s, and then the active component powder is added.
It should be noted that the thickener is added so that the viscosity of the system is 3500 to 9000 mPas, for example, 3500 mPas, 4000 mPas, 4500 mPas, 5000 mPas, 5500 mPas, 6000 mPas, 6500 mPas, 7000 mPas, 7500 mPas, 8000 mPas or 9000 mPas, but is not limited to the exemplified values, and other values not exemplified in the above-mentioned range of values are also applicable.
Preferably, in the step (1), after the thickener is added and before the active component powder is added, the stirring speed of the system is controlled to 1400-1600 rpm, such as 1400rpm, 1450rpm, 1500rpm, 1550rpm or 1600rpm, etc., and the stirring time is controlled to 30-50 min, such as 30min, 35min, 40min, 45min or 50min, etc., but not limited to the enumerated values, and other non-enumerated values within the above numerical range are also applicable.
It is worth to say that the preparation method controls the thickener to be added at a high speed of 1400-1600 rpm and stirs for 30-50 min, so that active component powder added subsequently can be effectively prevented from agglomerating into blocks, further the grinding step can be omitted, and the blending of the catalyst slurry can be completed only by stirring; and the stirring speed of the thickening agent is about 1.5 times of that of the subsequent system, so that the aim of uniform mixing can be fulfilled, the energy consumption can be reduced, and the cost can be reduced. If the thickener is added after the addition of the active ingredient powder, it is necessary to extend the stirring time to more than 6 hours to possibly prevent the problem of agglomeration.
As a preferred technical scheme of the invention, the active component powder in the step (1) comprises a molecular sieve and/or a vanadium-based oxide.
Preferably, the binder of step (1) comprises any one of or a combination of at least two of an aluminum sol, a silica sol or an aqueous solution of an alkali metal silicate, and typical but non-limiting examples of the combination include a combination of an aluminum sol and a silica sol, a combination of an aluminum sol and an aqueous solution of an alkali metal silicate, or a combination of a silica sol and an aqueous solution of an alkali metal silicate, and the like.
As a preferable technical scheme of the invention, the coating auxiliary agent in the step (1) comprises tributyl phosphate and/or butyl titanate.
Preferably, the coating assistant in the step (1) is a mixture of tributyl phosphate and butyl titanate in a mass ratio of 1: 3.
It is worth to say that in the preparation method, the coating auxiliary agent is added, so that foam generated in stirring can be eliminated, the system viscosity, the coating uniformity and the slurry water-retaining property are enhanced, the agglomeration of catalyst powder in the slurry is further inhibited, and the slurry storage time is prolonged.
Preferably, in the step (1), the active component powder is added and stirred for 0.5-3 h, and then the coating auxiliary agent is added.
It is noted that the active ingredient powder is added and stirred for 0.5 to 3 hours, such as 0.5 hour, 1 hour, 1.5 hour, 2 hours, 2.5 hours or 3 hours, but not limited to the recited values, and other values not recited in the above range of values are also applicable.
Preferably, in step (1), after the coating assistant is added, the stirring speed of the system is controlled to be 900-1100 rpm, such as 900rpm, 950rpm, 1000rpm, 1050rpm or 1100rpm, and the stirring time is controlled to be 50-60 min, such as 50min, 52min, 54min, 55min, 57min or 60min, but not limited to the enumerated values, and other unrecited values within the above-mentioned range of values are also applicable.
In the preferred embodiment of the present invention, in the step (1), the mass ratio of the deionized water to the thickener is 1 (0.004 to 0.006), for example, 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06, etc., but the present invention is not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.
Preferably, in step (1), the mass ratio of the deionized water to the active component powder is 1 (0.25-0.45), such as 1:0.25, 1:0.3, 1:0.35, 1:0.4, or 1:0.45, but not limited to the enumerated values, and other unrecited values within the above-mentioned range of values are also applicable.
Preferably, in step (1), the mass ratio of the active ingredient powder to the binder is (3-6: 1), for example, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, or 6:1, but not limited to the recited values, and other values not recited within the above numerical range are also applicable.
Preferably, in step (1), the mass ratio of the deionized water to the coating assistant is 1 (0.01-0.015), such as 1:0.01, 1:0.011, 1:0.012, 1:0.013, 1:0.014, or 1:0.015, but not limited to the enumerated values, and other unrecited values within the above-mentioned range of values are also applicable.
In a preferred embodiment of the present invention, the honeycomb carrier in the step (2) has a cell density of 200 to 600 mesh, that is, the number of cells per square inch area is 200 to 600, for example, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, 500 mesh, 550 mesh, or 600 mesh, but the number is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.
Preferably, the material of the honeycomb carrier in the step (2) is cordierite and/or mullite.
Preferably, the vacuum degree corresponding to the negative pressure condition in step (2) is-20 to-60 kPa, such as-20 kPa, 25kPa, 30kPa, 35kPa, 40kPa, 45kPa, 50kPa, 55kPa, or-60 kPa, but not limited to the recited values, and other values not recited in the above-mentioned range of values are also applicable.
In a preferred embodiment of the present invention, the drying temperature in the step (3) is 100 to 150 ℃, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, but the temperature is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.
Preferably, the drying time in step (3) is 2 to 4 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, but not limited to the recited values, and other values not recited in the above range of values are also applicable.
Preferably, the temperature of the calcination in the step (3) is 500 to 550 ℃, for example, 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, 550 ℃, etc., but is not limited to the recited values, and other values not recited in the above-mentioned range of values are also applicable.
Preferably, the time for the calcination in step (3) is 2-6 h, such as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, but not limited to the recited values, and other values not recited in the above range are also applicable.
As a preferred technical scheme of the invention, the preparation method comprises the following steps:
(1) weighing a certain amount of deionized water, adding a thickening agent under stirring conditions, controlling the stirring speed of a system to be 1400-1600 rpm, and the stirring time to be 30-50 min, so that the viscosity of the system is 3500-9000 mPa & s, then adding active component powder and a binder, stirring for 0.5-3 h, adding a coating aid, controlling the stirring speed of the system to be 900-1100 rpm, and the stirring time to be 50-60 min, and uniformly mixing to obtain catalyst slurry;
wherein the thickener comprises hydroxycellulose and/or polyacrylic acid; the active component powder comprises a molecular sieve and/or a vanadium-based oxide; the binder comprises any one of aluminum sol, silica sol or alkali metal silicate aqueous solution or the combination of at least two of the aluminum sol, the silica sol or the alkali metal silicate aqueous solution; the coating auxiliary agent comprises tributyl phosphate and/or butyl titanate; controlling the mass ratio of deionized water to the thickening agent to be 1 (0.004-0.006), controlling the mass ratio of deionized water to the active component powder to be 1 (0.25-0.45), controlling the mass ratio of the active component powder to the binder to be (3-6) to 1, and controlling the mass ratio of the deionized water to the coating auxiliary agent to be 1 (0.01-0.015);
(2) under the negative pressure condition that the vacuum degree is-20 to-60 kPa, the catalyst slurry obtained in the step (1) is coated on the surface of a pore channel of a honeycomb carrier with the pore density of 200 to 600 meshes in a vacuum manner to obtain a catalyst blank;
(3) drying the catalyst blank obtained in the step (2) at 100-150 ℃ for 2-4 h, and then roasting at 500-550 ℃ for 2-6 h to obtain the integral denitration catalyst.
In the step (2), catalyst slurry is covered on the upper surface of the honeycomb carrier to form a closed space according to the loading amount, the surface residence time of the catalyst slurry is controlled to be at most 1min, the bottom of the honeycomb carrier is vacuumized by using a vacuum pump, the vacuum degree is-20 to-60 kPa, the catalyst slurry is sucked into a pore channel of the honeycomb carrier, and the pore blocking rate is ensured not to exceed 1%; furthermore, the coating can be carried out for multiple times according to the coating requirement until the coating reaches 120-180 g/L.
It is worth mentioning that the honeycomb carrier of the present invention needs to be pretreated before being vacuum coated, and specifically includes: putting the honeycomb carrier into deionized water for ultrasonic treatment for 30min, then washing for 6min, cleaning the inner pore channels of the honeycomb carrier, and finally drying in an oven at 100 ℃ for 6 h.
The second purpose of the invention is to provide the monolithic denitration catalyst prepared by the preparation method according to the first purpose.
The third purpose of the invention is to provide the application of the monolithic denitration catalyst according to the second purpose, and the monolithic denitration catalyst is used for purifying the tail gas of the diesel engine.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) the preparation method simplifies the process flow of the denitration catalyst, the preparation process of the catalyst slurry only needs a stirring step, the requirement on the particle size of the catalyst is low, the necessary grinding step in the past is eliminated, the machine configuration is reduced, and the process flow is reduced;
(2) the preparation method can reduce the viscosity requirement of the catalyst slurry, so that the viscosity has higher elasticity;
(3) the preparation method has the advantages of flexible and changeable production technology, easy modification and the like, and the catalyst powder can be freely changed according to the pollutant treatment requirement;
(4) the raw materials adopted by the preparation method disclosed by the invention do not contain dangerous chemicals, so that green production can be realized, and the safety of operators is guaranteed to a certain extent;
(5) the catalyst slurry obtained by the preparation method can be uniformly coated in cordierite channels, and through conversion rate and selectivity tests, the molecular sieve in the catalyst slurry has almost no difference from the original molecular sieve in activity, which shows that the influence of additives such as thickening agents, binders and the like on the molecular sieve activity is low.
Drawings
FIG. 1 is a sectional view of the monolithic denitration catalyst according to example 1 of the present invention;
FIG. 2 is a graph comparing conversion and selectivity of calcined powder and molecular sieve powder of catalyst slurry obtained in example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
pretreatment of a honeycomb carrier: the honeycomb carrier of the invention needs to be pretreated before being coated in vacuum, and the pretreatment method specifically comprises the following steps: putting the honeycomb carrier into deionized water for ultrasonic treatment for 30min, then washing for 6min, cleaning the inner pore channels of the honeycomb carrier, and finally drying in an oven at 100 ℃ for 6 h.
Example 1
The embodiment provides an integral denitration catalyst and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) weighing 3.5 parts of deionized water, firstly adding 0.02 part of hydroxy cellulose under the stirring condition, controlling the stirring speed of a system to be 1500rpm and the stirring time to be 40min so that the viscosity of the system is 3500-9000 mPa & s, then adding 1.5 parts of molecular sieve powder and 0.4 part of alumina sol, stirring for 1h, adding 0.04 part of coating auxiliary agent, wherein the coating auxiliary agent is a mixture of tributyl phosphate and butyl titanate with the mass ratio of 1:3, controlling the stirring speed of the system to be 1000rpm and the stirring time to be 60min, uniformly mixing, and measuring the viscosity of the system to be 4000-5000 mPa & s by using a viscometer to obtain catalyst slurry;
(2) preparing a cavity which is completely consistent with the cross section of a cordierite honeycomb carrier and is provided with an upper opening and a lower opening from stainless steel on the upper part of the cordierite honeycomb carrier with the pore density of 400 meshes, inputting the catalyst slurry obtained in the step (1) to the upper surface of the cordierite honeycomb carrier through a pipeline to form a closed space, vacuumizing the bottom of the cordierite honeycomb carrier by using a vacuum pump, wherein the vacuum degree is-40 kPa, the catalyst slurry is sucked into a pore channel of the cordierite honeycomb carrier, and after splitting, observing the cross section, the catalyst slurry can be uniformly coated in a vacuum manner to obtain a catalyst blank;
(3) and (3) drying the catalyst blank obtained in the step (2) at 100 ℃ for 4h, and then roasting at 550 ℃ for 3h to obtain the integral denitration catalyst.
The sectional view of the monolithic denitration catalyst obtained in this example is shown in fig. 1, and it can be seen that the molecular sieve powder as the active component can be uniformly coated on the channel wall.
The catalyst slurry obtained in the step (1) of the embodiment is directly roasted at 550 ℃ for 3h, and the obtained slurry roasted powder and the molecular sieve powder obtained in the step (1) are subjected to a comparative experiment under the evaluation condition of 500ppm NH3、500ppmNO、5vol％O2、5vol％H2And O, the flow rate is 500ml/min, the volume space velocity is 200000/h, conversion rate and selectivity data corresponding to the powder and the molecular sieve powder after the slurry roasting at different temperatures are respectively obtained, and specific contents are shown in figure 2, so that the conversion rate and the selectivity of the powder after the slurry roasting are almost the same as the original molecular sieve activity, which shows that the addition auxiliaries such as the thickening agent and the bonding agent added in the preparation method have lower influence on the molecular sieve activity.
Example 2
The embodiment provides an integral denitration catalyst and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) weighing 3.5 parts of deionized water, adding 0.015 part of hydroxy cellulose under the stirring condition, controlling the stirring speed of a system to be 1400rpm and the stirring time to be 30min so that the viscosity of the system is 3500-9000 mPa & s, adding 0.9 part of molecular sieve powder and 0.2 part of alumina sol, stirring for 1h, adding 0.035 part of coating auxiliary agent, wherein the coating auxiliary agent is a mixture of tributyl phosphate and butyl titanate with the mass ratio of 1:3, controlling the stirring speed of the system to be 900rpm and the stirring time to be 50min, uniformly mixing, and measuring the viscosity of the system to be 4000-5000 mPa & s by a viscometer to obtain catalyst slurry;
(2) preparing a cavity which is completely consistent with the cross section of a cordierite honeycomb carrier and is provided with an upper opening and a lower opening from stainless steel on the upper part of the cordierite honeycomb carrier with the pore density of 200 meshes, inputting the catalyst slurry obtained in the step (1) to the upper surface of the cordierite honeycomb carrier through a pipeline to form a closed space, vacuumizing the bottom of the cordierite honeycomb carrier by using a vacuum pump, wherein the vacuum degree is-20 kPa, the catalyst slurry is sucked into a pore channel of the cordierite honeycomb carrier, and observing the cross section after splitting the catalyst slurry to ensure that the catalyst slurry is uniformly coated in vacuum to obtain a catalyst green body;
(3) and (3) drying the catalyst blank obtained in the step (2) at 150 ℃ for 2h, and then roasting at 550 ℃ for 2h to obtain the integral denitration catalyst.
The molecular sieve powder as an active component in the monolithic denitration catalyst obtained in this example can be uniformly coated on the channel wall.
Example 3
The embodiment provides an integral denitration catalyst and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) weighing 3.5 parts of deionized water, adding 0.02 part of polyacrylic acid under stirring conditions, controlling the stirring speed of a system to be 1600rpm and the stirring time to be 50min so that the viscosity of the system is 3500-9000 mPa & s, adding 1.58 parts of molecular sieve powder and 0.3 part of alumina sol, stirring for 1h, adding 0.05 part of coating auxiliary agent, wherein the coating auxiliary agent is a mixture of tributyl phosphate and butyl titanate with the mass ratio of 1:3, controlling the stirring speed of the system to be 1100rpm and the stirring time to be 50min, uniformly mixing, and measuring the viscosity of the system to be 4000-5000 mPa & s by a viscometer to obtain catalyst slurry;
(2) preparing a cavity which is completely consistent with the cross section of the cordierite honeycomb carrier and is provided with an upper opening and a lower opening on the upper part of the cordierite honeycomb carrier with the pore density of 600 meshes by adopting stainless steel, inputting the catalyst slurry obtained in the step (1) to the upper surface of the cordierite honeycomb carrier through a pipeline to form a closed space, vacuumizing the bottom of the cordierite honeycomb carrier by using a vacuum pump, wherein the vacuum degree is-60 kPa, sucking the catalyst slurry into a pore channel of the cordierite honeycomb carrier, splitting the pore channel, and observing the cross section to see that the catalyst slurry is uniformly coated in vacuum to obtain a catalyst blank;
(3) and (3) drying the catalyst blank obtained in the step (2) at 120 ℃ for 3h, and then roasting at 500 ℃ for 6h to obtain the integral denitration catalyst.
The molecular sieve powder as an active component in the monolithic denitration catalyst obtained in this example can be uniformly coated on the channel walls.
In conclusion, the preparation method of the invention sequentially adds the thickening agent, the active component powder, the binder and the coating auxiliary agent into the deionized water under the stirring condition and uniformly mixes the materials to obtain the catalyst slurry, the addition sequence of all ingredients is strictly limited, the active component powder can be prevented from agglomerating, the grinding step is not needed, the blending of the catalyst slurry can be completed only by stirring, the preparation process of the integral denitration catalyst is reduced, the technical difficulty and the production cost are reduced, the preparation method has the advantages of simple process, safe operation and the like, the temperature window of the integral denitration catalyst is wide, the coating is uniform, and the industrial application is facilitated.
The present invention is described in detail with reference to the above embodiments, but the present invention is not limited to the above detailed structural features, that is, the present invention is not meant to be implemented only by relying on the above detailed structural features. It should be understood by those skilled in the art that any modifications, equivalent substitutions of selected elements of the present invention, additions of auxiliary elements, selection of specific forms, etc., are intended to fall within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present invention does not separately describe various possible combinations.
In addition, any combination of the various embodiments of the present invention can be made, and the same should be considered as the disclosure of the present invention as long as the idea of the present invention is not violated.
Claims (10)
1. A preparation method of an integral denitration catalyst is characterized by comprising the following steps:
(1) weighing a certain amount of deionized water, sequentially adding a thickening agent, active component powder, a binder and a coating auxiliary agent under the stirring condition, and uniformly mixing to obtain catalyst slurry;
(2) under the negative pressure condition, vacuum coating the catalyst slurry obtained in the step (1) on the surfaces of the pore channels of the honeycomb carrier to obtain a catalyst blank;
(3) and (3) drying and roasting the catalyst blank obtained in the step (2) in sequence to obtain the integral denitration catalyst.
2. The method according to claim 1, wherein the thickener in step (1) comprises hydroxycelluloses and/or polyacrylics;
preferably, in the step (1), the thickening agent is added to ensure that the viscosity of the system is 3500-9000 mPa & s, and the active component powder is added;
preferably, in the step (1), after the thickener is added and before the active component powder is added, the stirring speed of the system is controlled to be 1400-1600 rpm, and the stirring time is controlled to be 30-50 min.
3. The production method according to claim 1 or 2, wherein the active component powder of step (1) comprises a molecular sieve and/or a vanadium-based oxide;
preferably, the binder in step (1) comprises any one of aluminum sol, silica sol or alkali metal silicate aqueous solution or a combination of at least two of the two.
4. The production method according to any one of claims 1 to 3, wherein the coating aid of step (1) comprises tributyl phosphate and/or butyl titanate;
preferably, the coating auxiliary agent in the step (1) is a mixture of tributyl phosphate and butyl titanate in a mass ratio of 1: 3;
preferably, in the step (1), the active component powder is added and stirred for 0.5-3 h, and then the coating auxiliary agent is added;
preferably, in the step (1), after the coating auxiliary agent is added, the stirring speed of the system is controlled to be 900-1100 rpm, and the stirring time is controlled to be 50-60 min.
5. The method according to any one of claims 1 to 4, wherein in the step (1), the mass ratio of deionized water to the thickener is 1 (0.004 to 0.006);
preferably, in the step (1), the mass ratio of the deionized water to the active component powder is 1 (0.25-0.45);
preferably, in the step (1), the mass ratio of the active component powder to the binder is (3-6): 1;
preferably, in the step (1), the mass ratio of the deionized water to the coating auxiliary agent is 1 (0.01-0.015).
6. The production method according to any one of claims 1 to 5, wherein the honeycomb carrier of the step (2) has a cell density of 200 to 600 mesh;
preferably, the material of the honeycomb carrier in the step (2) is cordierite and/or mullite;
preferably, the vacuum degree corresponding to the negative pressure condition in the step (2) is-20 to-60 kPa.
7. The method according to any one of claims 1 to 6, wherein the drying temperature in step (3) is 100 to 150 ℃;
preferably, the drying time in the step (3) is 2-4 h;
preferably, the roasting temperature in the step (3) is 500-550 ℃;
preferably, the roasting time in the step (3) is 2-6 h.
8. The production method according to any one of claims 1 to 7, characterized by comprising the steps of:
(1) weighing a certain amount of deionized water, adding a thickening agent under stirring conditions, controlling the stirring speed of a system to be 1400-1600 rpm, and the stirring time to be 30-50 min, so that the viscosity of the system is 3500-9000 mPa & s, then adding active component powder and a binder, stirring for 0.5-3 h, adding a coating aid, controlling the stirring speed of the system to be 900-1100 rpm, and the stirring time to be 50-60 min, and uniformly mixing to obtain catalyst slurry;
wherein the thickener comprises hydroxycellulose and/or polyacrylic acid; the active component powder comprises a molecular sieve and/or a vanadium-based oxide; the binder comprises any one of aluminum sol, silica sol or alkali metal silicate aqueous solution or the combination of at least two of the aluminum sol, the silica sol or the alkali metal silicate aqueous solution; the coating auxiliary agent comprises tributyl phosphate and/or butyl titanate; controlling the mass ratio of deionized water to the thickening agent to be 1 (0.004-0.006), the mass ratio of deionized water to the active component powder to be 1 (0.25-0.45), the mass ratio of the active component powder to the binder to be (3-6) to 1, and the mass ratio of the deionized water to the coating auxiliary agent to be 1 (0.01-0.015);
(2) coating the catalyst slurry obtained in the step (1) on the surface of a pore channel of a honeycomb carrier with the pore density of 200-600 meshes in vacuum under the negative pressure condition that the vacuum degree is-20 to-60 kPa to obtain a catalyst blank;
(3) and (3) drying the catalyst blank obtained in the step (2) at 100-150 ℃ for 2-4 h, and then roasting at 500-550 ℃ for 2-6 h to obtain the integral denitration catalyst.
9. An integral denitration catalyst prepared by the preparation method of any one of claims 1 to 8.
10. Use of the monolithic denitration catalyst according to claim 9, wherein the monolithic denitration catalyst is used for diesel exhaust gas purification.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115155576A (en) * | 2022-07-22 | 2022-10-11 | 山东亮剑环保新材料有限公司 | Preparation method of monolithic metal substrate precious metal catalytic module |
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