CN109277098A - Heat-staple Si modification SCR catalyst of high-temperature water and preparation method thereof - Google Patents
Heat-staple Si modification SCR catalyst of high-temperature water and preparation method thereof Download PDFInfo
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Abstract
The heat-staple Si modification SCR catalyst of high-temperature water provided by the invention, by Si modification WO3/CexZr1‑xO2Obtained composite oxides, chemical formula WO3/SiO2/CexZr1‑xO2, wherein 0 < x < 1, WO3Mass fraction is to be less than or equal to 15%, SiO greater than 0 in the catalyst2Mass fraction is 2-8% in the catalyst.Preparation method includes: by cerium zirconium compound oxide powder CexZr1‑xO2It is added in deionized water, lower addition ethyl orthosilicate (TEOS) is stirred at room temperature, first stir 5-15 hour, continue stirring 1-6 hours after standing 6-15h at room temperature, separation of solid and liquid is precipitated, gained will be precipitated drying, obtain SiO2/CexZr1‑xO2Powder；By tungsten source incipient impregnation to SiO2/CeZrO2In powder.The catalyst that the present invention obtains shows excellent water resistant heat aging performance in ammine selectivity catalytic reduction nitrous oxides reaction, while having excellent catalytic activity excellent, environmentally protective.
Description
Technical field
The invention belongs to NH3A kind of SCR catalyst field, and in particular to catalytic purification exhaust gas from diesel vehicle NOxGas it is non-
Vanadium base WO3/CeZrO2Composite oxides NH3SCR catalyst.
Background technique
NO with the promulgation for the discharged nitrous oxides regulation that countries in the world are increasingly stringenter, in lean combustion motor-vehicle tail-gasx
Purification has become current one of environmental problem in the urgent need to address.Nitrogen oxides can be brought such as acid rain, photochemical fog, greenhouse
The environmental problems such as effect and ozone hole cause serious harm to human health and ecological environment.95% NO in atmospherex
Flue gas (46%) from motor-vehicle tail-gas (49%) and thermal power plant is discharged.Ammine selectivity catalytic reduction NOx(NH3-
SCR) be most application prospect at present exhaust gas from diesel vehicle NOxPurification techniques has obtained industry in American-European-Japanese equal developed countries
Change application and Science in Future in China controls diesel vehicle NOxOne of major technique of discharge.
V2O5-WO3(MO3)/TiO2Catalyst series (i.e. catalytic component based on vanadium) have been successfully applied to Section IV (state IV) and V (state
V) on stage diesel vehicle for purifying its tail gas NOx, with the promulgation of the 6th stringenter stage (i.e. state six) discharge standard,
Such catalyst is not able to satisfy state six and higher standard to exhaust gas from diesel vehicle NOxDischarge requirement.Mainly due to vanadium base
There are still some inevitable disadvantages for catalyst: effective operation window (300-400 DEG C) of such catalyst does not adapt to bavin
Oily tailstock gas temperature range (175-550 DEG C)；NH under high temperature (450 DEG C)3Non-selective oxidation make NOxUnder purifying rate is quick
Drop, and generate a large amount of greenhouse gases N2O leads to principal product N2Selectivity be substantially reduced, secondary pollution also is caused to atmosphere；
The thermal stability of catalytic component based on vanadium is poor, V2O5With very strong bio-toxicity.In exhaust gas from diesel vehicle after-treatment system, NH3-SCR
Device is in grain catcher rear end, and the periodic regeneration of the grain catcher in exhaust gas from diesel vehicle can be such that exhaust temperature moment reaches
To 800 DEG C or more, vanadium species can be sintered at such high temperatures, and main carriers TiO2Rutile will be changed by anatase
Catalyst activity mutually is greatly reduced or even complete deactivation, the serious service life for reducing catalyst.Therefore, in reality
Existing NH3While SCR catalyst is environmentally protective and catalytic activity is excellent, hydro-thermal performance resistant to high temperatures be can not ignore.
Ce base catalyst has obtained extensive concern in recent years, due to excellent Oxygen storage capacity, redox property
And thermal stability, and the rich reserves of cerium.Pass through solid acid WO3Modified CeZrO2Obtained WO3/CeZrO2Catalyst is not only
It is environmentally protective and have excellent NH3SCR activity, before there is in diesel vehicle denitration under lean burn conditions preferable application
Scape.But WO3/CeZrO2For catalyst after hydrothermal aging, catalyst surface can generate Ce2(WO4)3, so as to cause catalyst
Inactivation.
Summary of the invention
The purpose of the present invention is to provide heat-staple Si modification SCR catalysts of a kind of high-temperature water and preparation method thereof, obtain
The catalyst obtained shows excellent water resistant heat aging performance in ammine selectivity catalytic reduction nitrous oxides reaction, has simultaneously
Excellent catalytic activity, it is nontoxic, it is environmentally protective.
The heat-staple Si modification SCR catalyst of high-temperature water provided by the invention, by SiO2Modified (doping) WO3/CexZr1- xO2Obtained composite oxide catalysts, chemical formula WO3/SiO2/CexZr1-xO2, wherein 0 < x < 1, WO3Matter in the catalyst
Measuring score is to be less than or equal to 15%, SiO greater than 02Mass fraction is 2-8% in the catalyst.
Further, the WO3Mass fraction in the catalyst is 6-12%.
Further, the CexZr1-xO2In, preferably 0.5 < x < 0.8, further preferably 0.68.
The preparation method of above-mentioned catalyst provided by the invention, comprising the following steps:
(1) according to chemical formula CexZr1-xO2, in which: 0 < x < 1 weighs cerium source, zirconium source, is dissolved in water respectively and is configured to solution；
(2) the cerium source solution of preparation and zirconium source solution are uniformly mixed to get mixed solution, it is molten with ammonium hydroxide-ammonium carbonate buffering
Liquid carries out cocurrent titration as precipitating reagent, with mixed solution, is co-precipitated cerium and zirconium, controls in titration coprecipitation process
PH=8.2~8.5, ammonium hydroxide adjusts gained suspension pH=10 after co-precipitation, stands after adjusting not less than for 24 hours；
(3) the precipitating suspension after standing step (2) is aged 6~8h at 96~98 DEG C, and ageing terminates to be cooled to room
Temperature, filtering, and filter cake to last time filtrate is washed with deionized and is in neutrality；
(4) by after gained filtration cakes torrefaction, 550-650 DEG C of predecomposition roasts 3~5h in Muffle furnace, obtains CexZr1-xO2It is yellow
Color powder；
(5) by cerium zirconium compound oxide powder CexZr1-xO2Be added deionized water in, cerium zirconium compound oxide powder with go
The mass ratio of ionized water is 0.01-0.1, and lower addition ethyl orthosilicate (TEOS), ethyl orthosilicate and deionized water is stirred at room temperature
Volume ratio be 0.005-0.05, first stir 5-15 hour, at room temperature stand 6-15 hours after continue stir 1-6 hours, Gu
Gained will be precipitated drying, obtains SiO by the isolated precipitating of liquid2/CexZr1-xO2Powder；
(6) by tungsten source incipient impregnation to SiO2/CeZrO2In powder, 6-12h is stood, after drying in air atmosphere
500-600 DEG C of calcining 2-3h, obtains composite oxides WO3/SiO2/CexZr1-xO2Powder, the load capacity of tungsten meet gained catalysis
WO in agent powder3Mass fraction be greater than 0 be less than or equal to 15%.
Further, in step (1) cerium source in carbonic acid Asia cerium, cerous nitrate, ammonium ceric nitrate, cerous carbonate, cerous nitrate
Any one or a few.
Further, zirconium source is selected from zirconium carbonate, zirconyl carbonate, zirconium nitrate, zirconyl nitrate, acetic acid zirconium, acetic acid in step (1)
Any one or a few in oxygen zirconium.
Further, any one or a few in ammonium metatungstate, ammonium paratungstate, ammonium tungstate of tungsten source in step (1).
Further, the molar ratio of ammonia and ammonium carbonate is (0.5~3) in the buffer solution of the ammonium hydroxide-ammonium carbonate: 1, it is excellent
The concentration for being selected as ammonia and carbonic acid ammonia is 2.5-3.5mol/L, further preferably 3mol/L.
Further, when preparing zirconium source solution, tungsten source solution, deionized water and zirconium source, tungsten source mass ratio be (1~
3): 1, when preparing silicon source solution, the mass ratio of deionized water and silicon source is (1~4): 1.
Further, step (4) drying condition is in 80~100 DEG C of dry 20~30h.
Further, it is 25%-28% that step (2), which adjusts the ammoniacal liquor mass concentration of pH,.
Further, step (3) can be aged under 96~98 DEG C of oil baths or water bath condition.
Further, step (3) be washed with deionized filter cake to neutrality be washing to last time filtrate pH=6.8~
7.5。
Further, step (5) drying is will to precipitate to move in 80-90 DEG C of water-bath, and heating and continuous stirring is until moisture
Evaporation, placing into dry 3-4 hours in 100-120 DEG C of baking oven is extremely in fine powdered.
Further, step (6) drying is to heat and be stirred continuously until that moisture evaporates under 70-95 DEG C of water-bath, preferably
2h is dried on ground under 70 DEG C, 80 DEG C, 90 DEG C of water-baths respectively.
Further, step (1) room temperature is 20-30 DEG C.
The WO that the present invention is prepared3/SiO2/CexZr1-xO2Catalyst fines, in application, being preferably prepared into monoblock type
Catalyst, the preparation method is as follows:
(1) by WO3/SiO2/CexZr1-xO2Fine catalyst is uniformly mixed with deionized water, bonding agent and slurries is made, control
Slurrying fluid solid content is 45~50%；
(2) gained catalyst slurry is coated uniformly on cordierite ceramic honeycomb matrix, control catalysis
Upper carrying capacity of the agent powder on matrix is 150~160g/L；
(3) cordierite substrates after coating step are after 100~120 DEG C of dry 8~12h, 500-600 DEG C in Muffle furnace
3~5h is roasted to get WO is arrived3/SiO2/CexZr1-xO2Integral catalyzer.
Further, it is Φ 11mm*25mm/400cpsi that the cordierite, which selects specification,.
Further, any one or a few in boehmite, silica solution, acetic acid zirconium of bonding agent.
Compared with prior art, the invention has the following advantages:
1. the method for the invention is using ethyl orthosilicate as presoma, chemical solution deposition is in CexZr1-xO2And WO3It
Between formed a SiO2Layer inhibits Ce as diffusion barrier2(WO4)3Generation, to improve the property of the hydrothermally stable of catalyst
Can, extend the service life of catalyst.
2. the composite oxides WO that the method for the present invention obtains3/SiO2/CexZr1-xO2Catalyst hydrothermally stable with higher
Property, 800 DEG C of 10vol.%H2After O hydrothermal aging 10 hours, either low temperature or hot stage, SCR activity are substantially better than WO3/
CexZr1-xO2Catalyst, reaction temperature window is also wider, this is conducive to the application of exhaust gas from diesel vehicle denitration in real process.
Detailed description of the invention
Fig. 1 is WO3/CeZrO2And WO3/SiO2/CeZrO2TEM map when catalyst is fresh and hydrothermal aging；
Fig. 2 is WO3/CeZrO2- HA and WO3/SiO2/CeZrO2The HRTEM map of-HA catalyst；
Fig. 3 is WO3/CeZrO2- HA and WO3/SiO2/CeZrO2The XRD spectrum of-HA catalyst；
Fig. 4 is WO3/CeZrO2- HA and WO3/SiO2/CeZrO2The NH of-HA catalyst3SCR activity map.
Specific embodiment
The present invention is further described through below by embodiment, the present embodiment is served only for carrying out into one the present invention
Step explanation, but should not be understood as limiting the scope of the invention, all to make some nonessential change based on the content of present invention
The scope of protection of the invention is belonged into the technology realized after adjustment
In following embodiment, cerium zirconium oxide powder CexZr1-xO2In, X=0.68 is prepared using following methods
Ce0.68Zr0.32O2Powder is used for embodiment 1-6 and comparative example, hereinafter abbreviated as CeZrO2。
(1) 15.70g cerous nitrate is dissolved in 32.2g deionized water, 6.23g zirconium nitrate is dissolved in 12.9g deionized water
In, until completely dissolved, zirconium nitrate dissolution is added cerous nitrate solution and stirs evenly.
(2) ammonium hydroxide-ammonium carbonate buffer solution that molar ratio is 3:3 is prepared as precipitating reagent, and step (1) is resulting mixes
Solution cocurrent is co-precipitated and is controlled pH=8.2~8.5, adds 28% concentrated ammonia liquor to adjust and control pH=after precipitating
10, and place not less than for 24 hours.
(3) gained precipitating suspension in step (2) is aged 6h under 98 DEG C of oil bath or water bath condition；
(4) it after being cooled to room temperature suspension obtained by step (3), filters and repeatedly washs filter cake with deionized water to pH=
6.8~7.5；
(5) by filter cake obtained by step (4) in 100 DEG C it is dry for 24 hours after, in Muffle furnace 600 DEG C of predecomposition roasting 4h to get
To Ce0.68Zr32O2Yellow powder；
Comparative example
0.98 gram of ammonium metatungstate is dissolved in 2.88 ml deionized waters, by 8 grams of CeZrO after ammonium metatungstate dissolution2Powder
End is added in ammonium metatungstate solution, stirs 30 minutes, after standing 10 hours, is sequentially placed into 70 DEG C, 80 DEG C, 90 DEG C, water
2h is separately dried in bath, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/CeZrO2Catalyst, wherein WO3It accounts for and urges
The 10% of agent weight.By WO3/CeZrO2For catalyst at 800 DEG C, aging 10h under conditions of 10vol.% obtains urging for aging
Agent WO3/CeZrO2-HA。
Embodiment 1
(1) 8 grams of cerium zirconium powder CeZrO are weighed2Powder is added in 150 ml deionized waters, and lower addition is stirred at room temperature
1.4ml ethyl orthosilicate, continues to stir 13h, continues to stir 3h after standing 12h at room temperature；Gained suspension is centrifuged, deionization
Water washing precipitating, precipitating is moved in 90 DEG C of water-baths, and heating and continuous stirring is until moisture evaporates to obtain powder；Powder is put into
Dry 3h, obtains yellow SiO in 120 DEG C of baking ovens2/CeZrO2- 1 powder.
(2) 1.04 grams of ammonium metatungstates are dissolved in 3.05 ml deionized waters, obtain ammonium metatungstate solution, by 8.47 grams
SiO2/CeZrO2- 1 powder is added in ammonium metatungstate solution, is stirred 30 minutes, after standing 10h, is sequentially placed into 70 DEG C, and 80 DEG C,
2h is separately dried in 90 DEG C of water-bath, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2- 1 catalysis
Agent powder, wherein WO3Account for 10%, SiO of catalyst weight2Account for catalyst weight 2%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 1 catalyst.
Embodiment 2
(1) 8 grams of cerium zirconium powder are weighed to be added in 150 ml deionized waters, the positive silicon of 3.4ml is added under room temperature magnetic agitation
Acetoacetic ester continues to stir 16h；Gained salting liquid is centrifuged, washing precipitating moves to precipitating in 90 DEG C of water-baths, heating and continuous
Stirring is until moisture evaporates to obtain powder；Powder is put into 120 DEG C of baking ovens dry 3h, obtains yellow SiO2/CeZrO2- 2 powder
End.
(2) 1.04 grams of ammonium metatungstates are dissolved in 3.05 ml deionized waters, obtain ammonium metatungstate solution, by 8.47 grams
SiO2/CeZrO2- 2 powder are added in ammonium metatungstate solution, are stirred 30 minutes, after standing 10h, are put into 70 DEG C, 80 DEG C, 90 DEG C
Water-bath in be separately dried 2h, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2Catalyst powder
End, wherein WO3Account for 10%, SiO of catalyst weight2Account for catalyst weight 5%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 2 catalyst.
Embodiment 3
(1) 8 grams of cerium zirconium powder are weighed to be added in 150 ml deionized waters, the positive silicon of 5.4ml is added under room temperature magnetic agitation
Acetoacetic ester continues to stir 16h；Gained salting liquid is centrifuged, washing precipitating moves to precipitating in 90 DEG C of water-baths, heating and continuous
Stirring is until moisture evaporates to obtain powder；Powder is put into 120 DEG C of baking ovens dry 3h, obtains yellow SiO2/CeZrO2- 3 powder
End.
(2) 1.04 grams of ammonium metatungstates are dissolved in 3.05 ml deionized waters, obtain ammonium metatungstate solution, by 8.47 grams
SiO2/CeZrO2- 3 powder are added in ammonium metatungstate solution, are stirred 30 minutes, after standing 10h, are put into 70 DEG C, 80 DEG C, 90 DEG C
Water-bath in be separately dried 2h, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2Catalyst powder
End, wherein WO3Account for 10%, SiO of catalyst weight2Account for catalyst weight 8%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 3 catalyst.
Embodiment 4
(1) 8.36 grams of cerium zirconium powder are weighed to be added in 157 ml deionized waters, 5.64ml is added under room temperature magnetic agitation
Ethyl orthosilicate continues to stir 16h；Gained salting liquid is centrifuged, precipitating is moved in 90 DEG C of water-baths, heated by washing precipitating
It is stirred continuously until that moisture evaporates to obtain powder；Powder is put into 120 DEG C of baking ovens dry 3h, obtains yellow SiO2/CeZrO2-4
Powder.
(2) 0.624 gram of ammonium metatungstate is dissolved in 1.83 ml deionized waters, obtains ammonium metatungstate solution, by 8.85
Gram SiO2/CeZrO2- 4 powder are added in ammonium metatungstate solution, are stirred 30 minutes, after standing 10h, are put into 70 DEG C, and 80 DEG C, 90
DEG C water-bath in be separately dried 2h, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2Catalyst powder
End, wherein WO3Account for 6%, SiO of catalyst weight2Account for catalyst weight 5%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 4 catalyst.
Embodiment 5
(1) 8.18 grams of cerium zirconium powder are weighed to be added in 153 ml deionized waters, 5.64ml is added under room temperature magnetic agitation
Ethyl orthosilicate continues to stir 16h；Gained salting liquid is centrifuged, precipitating is moved in 90 DEG C of water-baths, heated by washing precipitating
It is stirred continuously until that moisture evaporates to obtain powder；Powder is put into 120 DEG C of baking ovens dry 3h, obtains yellow SiO2/CeZrO2-5
Powder.
(2) 0.832 gram of ammonium metatungstate is dissolved in 2.44 ml deionized waters, obtains ammonium metatungstate solution, by 8.66
Gram SiO2/CeZrO2- 4 powder are added in ammonium metatungstate solution, are stirred 30 minutes, after standing 10h, are put into 70 DEG C, and 80 DEG C, 90
DEG C water-bath in be separately dried 2h, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2Catalyst powder
End, wherein WO3Account for 8%, SiO of catalyst weight2Account for catalyst weight 5%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 5 catalyst.
Embodiment 6
(1) 7.82 grams of cerium zirconium powder are weighed to be added in 147 ml deionized waters, 5.28ml is added under room temperature magnetic agitation
Ethyl orthosilicate continues to stir 16h；Gained salting liquid is centrifuged, precipitating is moved in 90 DEG C of water-baths, heated by washing precipitating
It is stirred continuously until that moisture evaporates to obtain powder；Powder is put into 120 DEG C of baking ovens dry 3h, obtains yellow SiO2/CeZrO2-6
Powder.
(2) 1.248 grams of ammonium metatungstates are dissolved in 3.66 ml deionized waters, obtain ammonium metatungstate solution, by 8.28
Gram SiO2/CeZrO2- 6 powder are added in ammonium metatungstate solution, are stirred 30 minutes, after standing 10h, are put into 70 DEG C, and 80 DEG C, 90
DEG C water-bath in be separately dried 2h, then 550 DEG C of roasting 3h in air atmosphere, obtain WO3/SiO2/CeZrO2Catalyst powder
End, wherein WO3Account for 12%, SiO of catalyst weight2Account for catalyst weight 5%.
Prepare integral catalyzer
Resulting fine catalyst is uniformly mixed with deionized water, bonding agent, slurries are made, control slurry solid content is
50%, it is coated uniformly on Φ 11mm*25mm/400cpsi cordierite ceramic honeycomb matrix, controlling carrying capacity on catalyst powder is
150g/L is then placed in baking oven respectively at 70 DEG C, 80 DEG C, 90 DEG C of dry 2h, then in Muffle furnace 550 DEG C of roasting 3h to get
To the WO of monoblock type3/SiO2/CeZrO2- 6 catalyst.
By embodiment 2 and comparative example catalyst, with corresponding hydrothermal aging treated catalyst in fixed bed reactors
Upper carry out NH3- SCR reactivity evaluation test.Hydrothermal aging conditions are as follows: catalyst at 800 DEG C, moisture content 10vol.%'s
Under the conditions of aging 10h, heating rate be 10 DEG C/min (aging sample is denoted as HA).When test, reaction mixture gas forms by volume
Are as follows: 500ppm NO, 500ppm NH3, 5%O2, 5%H2O, total gas flow rate 1.25L/min, N2As Balance Air, air speed is
30000h-1, reaction temperature is 190~500 DEG C.The equal using gas infrared radiation detection apparatus detection of the gas composition of reactor inlet and outlet.
NH3- SCR reactivity evaluation result is shown in Fig. 4.As seen from Figure 4, WO3/SiO2/CeZrO2Catalyst ratio WO3/SiO2/
CeZrO2Catalyst has more preferable water resistant heat aging performance.WO3/SiO2/CeZrO2202 DEG C of-HA catalyst) initiation temperature (NOx
Conversion ratio be 50% when temperature) obviously compare WO3/CeZrO2- HA's (238 DEG C) is low.Due to the introducing of Si, WO3/CeZrO2-
The NO of HA catalystxConversion window (NO completelyxConversion ratio be greater than 90% temperature range) widened from 243-487 DEG C to 302-
454℃。WO3/CeZrO2The NO of-HA catalystxHighest conversion ratio has 96%, WO3/SiO2/CeZrO2The NOx of-HA catalyst
Highest conversion ratio can reach 100%.These results suggest that the present invention significantly improves the water resistant heat aging performance of catalyst.
The catalyst XRD result that embodiment 2 obtains is shown in Fig. 3.
Find out from Fig. 3 XRD result, the cubic phase cerium zirconium of mainly fluorite structure is solid on the catalyst of two hydrothermal agings
Solution Ce0.25Zr0.75O2In the presence of, but WO3/CeZrO2There is Ce in-HA catalyst surface2(WO4)3Phase, Ce2(WO4)3It can drop
The redox property of low catalyst, to make catalyst inactivation.The doping of Si on the map of XRD and finds no Ce2
(WO4)3Occur into.Illustrate that Si can effectively inhibit Ce2(WO4)3It generates, improves the hydrothermally stable performance of catalyst.This is living with SCR
Property result is consistent.
The catalyst TEM the result is shown in Figure 1 and Fig. 2 obtained to embodiment 2.
From figure TEM the results show that W/CZ (WO3/CeZrO2) catalyst serious sintering aggregation after hydrothermal aging.But
Si significantly reduces the sintering of catalyst.It can be seen that from HRTEM map in WO3/SiO2/CeZrO2It is obvious on-HA catalyst
Form Si layers, to protect catalyst, it is suppressed that the sintering of catalyst.
Claims (10)
1. the heat-staple Si modification SCR catalyst of high-temperature water, which is characterized in that by Si modification WO3/CexZr1-xO2What is obtained is compound
Oxide, chemical formula WO3/SiO2/CexZr1-xO2, wherein 0 < x < 1, WO3In the catalyst mass fraction be greater than 0 be less than etc.
In 15%, SiO2Mass fraction is 2-8% in the catalyst.
2. the heat-staple Si modification SCR catalyst of high-temperature water according to claim 1, which is characterized in that the WO3It is being catalyzed
Mass fraction in agent is 6-12%.
3. the heat-staple Si modification SCR catalyst of high-temperature water according to claim 1, which is characterized in that the CexZr1-xO2
In, 0.5 < x < 0.8.
4. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water described in claim 1, which is characterized in that including with
Lower step:
It (1) will be using the cerium zirconium compound oxide powder Ce of coprecipitation preparationxZr1-xO2, wherein 0 < x < 1, is added deionized water
In, the mass ratio of cerium zirconium compound oxide powder and deionized water is 0.01-0.1, lower addition ethyl orthosilicate is stirred at room temperature, just
The volume ratio of silester and deionized water is 0.005-0.05, first stirs 5-15 hour, after standing 6-15 hours at room temperature
Continue stirring 1-6 hours, separation of solid and liquid is precipitated, gained is precipitated drying, obtains SiO2/CexZr1-xO2Powder；
(2) tungsten source is configured to solution, incipient impregnation to SiO2/CexZr1-xO2In powder, 6-12h is stood, in sky after drying
500-600 DEG C of calcining 2-3h, obtains composite oxides WO under gas atmosphere3/SiO2/CexZr1-xO2The load capacity of powder, tungsten meets
WO in gained catalyst fines3Mass fraction be greater than 0 be less than or equal to 15%.
5. the preparation method of heat-staple Si modification SCR catalyst of high-temperature water and preparation method thereof according to claim 4,
It is characterized in that, zirconium mixed oxide powder CexZr1-xO2It is prepared by the following method:
(1) according to chemical formula CexZr1-xO2, in which: 0 < x < 1 weighs cerium source, zirconium source, and weighs silicon source, tungsten source, is dissolved in water respectively
It is configured to solution；
(2) the cerium source solution of preparation and zirconium source solution are uniformly mixed to get mixed solution, are made with ammonium hydroxide-ammonium carbonate buffer solution
For precipitating reagent, cocurrent titration is carried out with mixed solution, is co-precipitated cerium and zirconium, controls pH=in titration coprecipitation process
8.2~8.5, ammonium hydroxide adjusts gained suspension pH=10 after co-precipitation, stands after adjusting not less than for 24 hours；
(3) the precipitating suspension after standing step (2) is aged 6~8h at 96~98 DEG C, and ageing terminates to be cooled to room temperature, mistake
Filter, and filter cake to last time filtrate is washed with deionized and is in neutrality；
(4) by after gained filtration cakes torrefaction, 550-650 DEG C of predecomposition roasts 3~5h in Muffle furnace, obtains CexZr1-xO2Yellow powder
End.
6. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water according to claim 5, which is characterized in that step
Suddenly any one or a few in carbonic acid Asia cerium, cerous nitrate, ammonium ceric nitrate, cerous carbonate, cerous nitrate of cerium source in (1)；Zirconium
Any one or a few in zirconium carbonate, zirconyl carbonate, zirconium nitrate, zirconyl nitrate, acetic acid zirconium, zirconium oxyacetate of source.
7. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water according to claim 4, which is characterized in that tungsten
Any one or a few in ammonium metatungstate, ammonium paratungstate, ammonium tungstate of source.
8. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water according to claim 4, which is characterized in that step
Suddenly (1) drying is will to precipitate to move in 80-90 DEG C of water-bath, and heating and continuous stirring places into 100-120 DEG C until moisture evaporation
Dry 3-4 hours in baking oven are extremely in fine powdered.
9. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water according to claim 4, which is characterized in that step
Suddenly (2) drying is to heat and be stirred continuously until that moisture evaporates under 70-95 DEG C of water-bath.
10. the preparation method of the heat-staple Si modification SCR catalyst of high-temperature water according to claim 8, which is characterized in that step
Suddenly (2) drying is that 2h is successively dried under 70 DEG C, 80 DEG C, 90 DEG C of water-baths.
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| CN110270321A (en) * | 2019-07-04 | 2019-09-24 | 南京大学 | The preparation method and its product of a kind of cerium Si composite oxide and application |
| CN113318728A (en) * | 2021-06-25 | 2021-08-31 | 北京化工大学 | Three-dimensional ordered macroporous tungsten-cerium-zirconium composite oxide catalyst and preparation method and application thereof |
| CN115585039A (en) * | 2022-11-02 | 2023-01-10 | 四川大学 | Application of cerium-zirconium oxide carrier material containing pyrochlore structure in nitrogen oxide purification in cold start stage of diesel vehicle |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110270321A (en) * | 2019-07-04 | 2019-09-24 | 南京大学 | The preparation method and its product of a kind of cerium Si composite oxide and application |
| CN113318728A (en) * | 2021-06-25 | 2021-08-31 | 北京化工大学 | Three-dimensional ordered macroporous tungsten-cerium-zirconium composite oxide catalyst and preparation method and application thereof |
| CN113318728B (en) * | 2021-06-25 | 2023-06-27 | 北京化工大学 | Three-dimensional ordered large Kong Wushi zirconium composite oxide catalyst and preparation method and application thereof |
| CN115585039A (en) * | 2022-11-02 | 2023-01-10 | 四川大学 | Application of cerium-zirconium oxide carrier material containing pyrochlore structure in nitrogen oxide purification in cold start stage of diesel vehicle |
| CN115585039B (en) * | 2022-11-02 | 2023-12-22 | 四川大学 | Application of cerium-zirconium oxide carrier material containing pyrochlore structure in diesel vehicle |
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