CN101462054A - Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides - Google Patents
Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides Download PDFInfo
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- CN101462054A CN101462054A CN 200810131487 CN200810131487A CN101462054A CN 101462054 A CN101462054 A CN 101462054A CN 200810131487 CN200810131487 CN 200810131487 CN 200810131487 A CN200810131487 A CN 200810131487A CN 101462054 A CN101462054 A CN 101462054A
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Abstract
A first catalyst for reducing nitrogen oxides comprising a crystalline silicate containing an iron in -framework structure wherein a SiO 2 /Fe 2 O 3 mol ratio is 20-300 and at least 80% of the contained iron is an isolated iron ion Fe 3+ . A second catalyst for reducing nitrogen oxides comprising a crystalline silicate containing an iron in -framework structure wherein a SiO 2 /Fe 2 O 3 mol ratio is 20-300 and log(SiO 2 /Al 2 O 3 ) by mol is at least 2. A predominant part of the contained iron is isolated iron ion Fe 3+ and at least a part thereof preferably has a tetrahedral coordination. These catalysts have high hydrothermal stability and exhibit enhanced activity for reducing nitrogen oxides by a reaction with a reducing agent such as ammonia, urea or an organic amine in a broad temperature range between lower temperature and higher temperature.
Description
Technical field
The present invention relates to from the purification method of the nitrogen oxide of internal combustion engine discharge, a kind of catalyst for purification of nitrogen oxides that comprises the ferrosilite with beta structure is provided, and use this catalyst, make the purification method of at least a substance reaction in nitrogen oxide and ammonia, urea, the organic amine.
Background technology
With regard to regard to the silicate of having replaced assorted element in the skeleton structure, expect that it has the characteristic different with common aluminosilicate zeolites, so studied its utilization in catalytic reaction.
For example, disclose: used load have the ferrosilite of platinum xylene isomerization catalyst (patent documentation 1), used the selective methylation catalyst (patent documentation 2) of the naphthalene compounds of ferrosilite and used ferrosilite as the manufacture method (patent documentation 3) of the PAG of cyclic ether ring-opening polymerization catalyst etc.
On the other hand, also studying about the purification techniques of the nitrogen oxide that uses ferrosilite among.
For example, the technology that is disclosed has: spread loads has the exhaust gas purification catalyst (patent documentation 4) of nitrogen-containing oxide of the co-precipitation composite oxides of copper and gallium in ZSM-5 type ferrosilite; In the atmosphere that has superfluous oxygen, under the condition that hydro carbons or oxygenatedchemicals exist, the purification of nitrogen oxides method (patent documentation 5) that the alkali metal exchanger of ZSM-5 type ferrosilite is contacted with the waste gas of nitrogen-containing oxide; In the presence of ferrosilite catalyst and hydrocarbon reducing agent, make the burnt gas that contains nitrogen oxide, oxygen and non-essential sulfur dioxide gas come in contact the method for removing nitrogen oxide (patent documentation 6) of reaction; At least a material on ferrosilite in load platinum, palladium, rhodium and the cobalt be used to remove cleaning catalyst (patent documentation 7) based on the waste gas of nitrogen oxide etc.
Because the ferrosilite of patent documentation 6,7 records uses the tetrapropyl ammonium salt when synthetic, so think that its skeleton structure as ferrosilite has the ZSM-5 structure.
Cleaning catalyst about nitrous oxide, a kind of manufacture method of catalyst is disclosed, this catalyst is used for nitrous oxide and directly decomposes, and load has copper or cobalt etc., and contain β type ferrosilite (patent documentation 8), use has the method for the direct decomposing nitrous oxide of ferrosilite of beta structure, and carbon monoxide is as non-selective contact method of reducing of the nitrous oxide of reducing agent (non-patent literature 1) etc.
On the other hand, cleaning catalyst about nitrogen oxides from exhaust gas, in the purification of nitrogen oxide of oxygen excess exhaust gas that with lean mixture gas burnt gas and diesel combustion waste gas is representative, known working load has the aluminosilicate zeolite catalyst of iron or copper, optionally contacts nitrogen oxides reduction (claiming SCR usually) method (patent documentation 9) with ammonia.
Yet, in using the method for reducing of ammonia, do not know the performance and the good ferrosilite of hydro-thermal durability of decomposing nitrogen oxide under the low temperature so far as yet as the nitrogen oxide (NOx) of reducing agent.
No. 3269828 communique of [patent documentation 1] Japan Patent
[patent documentation 2] special table 2004-524142 communique=USP7022637
No. 3477799 communique=USP5648558 of [patent documentation 3] special permission
[patent documentation 4] spy opens flat 5-305240 communique=USP5256614
No. 2691643 communique of [patent documentation 5] Japan Patent
[patent documentation 6] spy opens flat 5-154349 communique
No. 2605956 communique of [patent documentation 7] Japan Patent
[patent documentation 8] U.S. Patent Application Publication 2006-0088469 communique
[patent documentation 9] spy opens flat 2-293021 communique=USP4961917
[non-patent literature 1] Journal of Catalysis, 232 (2005) 318-334
Summary of the invention
[inventing problem to be solved]
People wish always and nitrogen oxides from exhaust gas can be purified effectively, but also do not learn the active high and higher catalyst for purification of nitrogen oxides of hydro-thermal endurance quality of purification of nitrogen oxides under the low temperature below 250 ℃ at present.
The object of the present invention is to provide a kind of ferrosilite cleaning catalyst, it is in the wide cut temperature province, have the catalytic performance of purifying nitrogen oxide efficiently in the lower temperature district below 250 ℃ especially, and compared with prior art, have better hydro-thermal durability.
Another object of the present invention is to provide the purification method of the nitrogen oxide that uses above-mentioned catalyst.
[method of dealing with problems]
The result that the inventor studies intensively repeatedly to the selective reducing nitrogen oxide method (SCR) of having used ammonia etc., find: as the crystallized silicon hydrochlorate that in the β skeleton structure, contains iron of one of crystallized silicon hydrochlorate that in the β skeleton structure, contains iron with good purification of nitrogen oxides performance (hereinafter claiming β type ferrosilite) (below, claim " β type ferrosilite 1 "), wherein, SiO
2/ Fe
2O
3Mol ratio is 20～300, in micropore, do not comprise under the state (fresh state) of organic structure directing agent, iron-holder be isolated iron ion more than 80%, result of study is also found, as the β type ferrosilite that another kind has good purification of nitrogen oxides performance, be SiO
2/ Fe
2O
3Mol ratio is 20～30, SiO
2/ Al
2O
3Mol ratio log (SiO
2/ Al
2O
3) be the β type silicate (below, claim " β type silicate 2 ") more than 2, it also has good purification of nitrogen oxides performance in the selective reduction as the nitrogen oxide of reducing agent such as ammonia, thereby has finished the present invention.
Description of drawings
[Fig. 1] is illustrated in the ultraviolet-visible absorption spectroscopy of the β type ferrosilite 1 of the present invention that obtains among the embodiment 3.
[Fig. 2] is illustrated in a durable example handling the electron spin resonance spectroscopy figure of front and back β type ferrosilite 1 that obtains among the embodiment 3.
[Fig. 3] is illustrated in the example of electron spin resonance spectroscopy figure that load before and after durable handle that obtains in the comparative example 1 has the zeolite beta of iron.
[Fig. 4] is illustrated in a durable example handling the electron spin resonance spectroscopy figure of front and back β type ferrosilite 2 that obtains among the embodiment 4.
[Fig. 5] is illustrated in the example of electron spin resonance spectroscopy figure that load before and after durable handle that obtains in the comparative example 4 has the zeolite beta of iron.
[Fig. 6] is illustrated in the ultraviolet-visible absorption spectroscopy of the β type ferrosilite 2 of the present invention that obtains among the embodiment 4.
[Fig. 7] illustrates durable nox purification rate (200 ℃) and the log (SiO that handles front and back
2/ Al
2O
3) the curve map of relation.
The specific embodiment
Below describe for catalyst for purification of nitrogen oxides of the present invention.
The composition of β type ferrosilite 1 of the present invention is represented with following formula:
(x+y)M
(2/n)O·xFe
2O
3·yAl
2O
3·zSiO
2·wH
2O
Wherein, n is the valence of cation M, and x, y, z represent Fe respectively
2O
3, Al
2O
3, SiO
2Mol ratio, x+y+z=1.W is the number more than 0, and z/x is 20～300, and y can be 0.
The composition of β type ferrosilite 2 of the present invention is represented with following formula:
(x+y)M
(2/n)O·xFe
2O
3·yAl
2O
3·zSiO
2·wH
2O
Wherein, n is the valence of cation M, and x, y, z represent Fe respectively
2O
3, Al
2O
3, SiO
2Mol ratio, x+y+z=1.W is the number more than 0, and z/x is 20～300, and z/y is more than 100, and y can be 0.
The crystal structure of β type ferrosilite 1 of the present invention and β type ferrosilite 2 is confirmed as the β type crystal structure by X-ray diffraction.β type ferrosilite is the metal silicate with three-dimensional pore, and the pore of described three-dimensional pore by 0.76 * 0.64nm of being made of 12 yuan of rings of oxygen and 0.55 * 0.55nm intersects and form.
The X-ray diffraction figure of β type ferrosilite 1 and β type ferrosilite 2 is characterised in that: lattice plane spacing d (dust) and its diffracted intensity of following table 1 expression.
[table 1]
SiO
2/ Fe
2O
3Mol ratio was less than 20 o'clock, though the total content of iron is more, heat-resisting water treatment makes crystallinity reduce easily, the isolated iron ion Fe of the given activity that is difficult to keep enough
3+Consider SiO from the crystallinity viewpoint
2/ Fe
2O
3Mol ratio is preferred more than 25.On the other hand, SiO
2/ Fe
2O
3Mol ratio surpasses at 300 o'clock, and the absolute magnitude of iron ion is less, can not obtain enough catalyst activities.
The SiO of β type ferrosilite 1
2/ Fe
2O
3Mol ratio is 40～150 scope, preferably 50～80 scope.
The SiO of β type ferrosilite 2
2/ Fe
2O
3Mol ratio is 20～150 scope, preferably 25～100 scope.
In β type ferrosilite 1 of the present invention and β type ferrosilite 2, help the iron of nitrogen oxide reduction most, with isolated iron ion (Fe
3+) form disperses to be present in the silicate skeleton described later, rather than be condensed into Fe
2O
3In the present invention, employed SiO during the composition of definition β type ferrosilite
2/ Fe
2O
3Mol ratio is the used easy expression way of total iron content that comprises isolated iron ion in order to define.
Log (the SiO of β type ferrosilite 2 of the present invention
2/ Al
2O
3) be (mol ratio) more than 2.Log (SiO
2/ Al
2O
3) less than 2 o'clock, reduce rapidly owing to the durable processing of hydro-thermal makes the purification of nitrogen oxides performance under the low temperature below 250 ℃.
Log (SiO
2/ Al
2O
3) the upper limit be not particularly limited, as long as greater than 2 (SiO
2/ Al
2O
3Be 100) get final product preferred especially 2.5 (SiO
2/ Al
2O
3Be 310) more than, more preferably 3 (SiO
2/ Al
2O
3Be 1000) more than.On the other hand, even log is (SiO
2/ Al
2O
3) be 4 (SiO
2/ Al
2O
3Be 10000) more than, its effect also has saturated tendency.
Known in the purification of nitrogen oxides that adopts ferrosilite, though directly the reactivity point is isolated iron ion, the aluminium in the skeleton also helps to improve active.In the past, in the alumina silicate, SiO
2/ Al
2O
3Higher than more, hear resistance is often high more, but because Al
2O
3I haven't seen you for ages makes solid acid point (solid acid point) reduce in quantitative change, and catalyst activity may not be just high., the log (SiO of β type ferrosilite 2 of the present invention
2/ Al
2O
3) 2 when above, the low temperature active (hear resistance) that hydro-thermal is durable before and after handling is remarkable.
When β type ferrosilite 1 of the present invention did not contain the state (fresh state) of organic structure directing agent in micro hole, all iron-holder was isolated iron ion more than 80%.
The structure that the iron that β type ferrosilite 1 of the present invention and β type ferrosilite 2 have a four-coordination structure and oxygen atom as skeletal atom are formed by connecting, identical with aluminosilicate zeolite, have the not enough solid acid character that produces of electric charge because of the silicate skeleton.With common catalyst at the aluminosilicate zeolite load iron relatively, in the ferrosilite of the present invention, as the iron of catalyst activity metal isolated iron ion (Fe with high degree of dispersion
3+) form exists, in the selective reduction reaction of using ammonia etc., the gathering of iron is inhibited, and especially can give play to extra high performance.
The isolated iron ion of β type ferrosilite 1 of the present invention and β type ferrosilite 2 can absorb the light measurement method with UV, visible light and measure.
Iron ion or ferriferous oxide show absorption in ultraviolet and wavelength of visible light zone.UV, visible light absorbs in the light measurement, and the absorbing wavelength zone of iron is different because of the existence of iron, belongs to isolated iron ion (Fe less than the absorption of 300nm
3+), the absorption of 300～400nm belongs to Fe
2O
3Bunch, the absorption that surpasses 400nm belongs to Fe
2O
3Aggregate particles.That is, by being about the absorption that decomposition waveform C that the Gaussian curve of 211 ± 10nm and about 272 ± 10nm constitutes and D belong to isolated iron ion by spike in the ultraviolet-visible absorption spectroscopy.Isolated iron ion mainly comprises the skeleton of β type ferrosilite or is positioned at the Fe in ion-exchange site
3+, belong to the iron that exists under the high dispersion state.
UV, visible light absorbs the ratio of the isolated iron ion of light measurement, in the scope of the wavelength region may 220～700nm of ultraviolet-visible absorption spectroscopy, integration absorption intensity (C) by the long 211 ± 10nm of spike and the integration absorption intensity (D) of wavelength 272 ± 10nm are with respect to the ratio (A=(C+D)/B) try to achieve of total absorption integrated intensity (B).
Because iron condenses outside skeleton and causes in the lower β type ferrosilite of purification of nitrogen oxides performance, the ratio of isolated iron ion diminishes.In the β type ferrosilite 1 of the present invention, the ratio that isolated iron ion accounts for total iron-holder is more than 80%, particularly preferably in more than 90%, more preferably more than 95%.Be no more than 100% on the upper-bound theory of isolated iron ion ratio.
UV, visible light absorbs light measurement can use following conventional method.
That is, use the uatomatic recording spectrophotometer (UV-3100 of (strain) Shimadzu Seisakusho Ltd. system) of the device (for example, the ISR-3100 of (strain) Shimadzu Seisakusho Ltd. manufacturing) that the band integrating sphere has been installed in the sample room to carry out UV, visible light absorption light measurement.Sweep speed is made as 200nm/min, and sweep length is 5.0nm, uses the barium sulfate powder to carry out the baseline correction.The sample of powdered is filled in the sample bomb (Off ォ Le ダ), and the reflectivity of measuring wave-length coverage 220～700nm gets final product.
In addition, owing to contain organic structure directed agents (Structure Directing Agent) (to call " SDA " in the following text) such as tetraethylammonium cation in the micro hole of the β type ferrosilite after just hydro-thermal has been synthesized, so, the mensuration of ultraviolet-visible absorption spectroscopy will be carried out afterwards in the operation (being called fresh roasting) of removing of the SDA that carries out usually, and described SDA removes operation by carrying out in 600 ℃ of roasting β type ferrosilites under the atmosphere of dry air or nitrogen etc.
β type ferrosilite 1 contained iron ion of the present invention be isolated iron ion Fe3 more than 80%
+, isolated iron ion Fe
3+Preferably contain symmetrical tetrahedral structure, have the isolated iron ion Fe of symmetrical tetrahedral structure
3+Ratio be preferably more than 20% of iron-holder.
In β type ferrosilite 2 of the present invention, isolated iron ion is preferably more than 90% with respect to the ratio of total iron-holder, but only be that iron ion is isolated state not enough, the isolated iron ion with symmetrical tetrahedral structure just helps to improve the purification of nitrogen oxides performance.
The total relatively iron-holder of ratio with isolated iron ion of symmetrical tetrahedral structure is preferably more than 60%.Be no more than 100% on the upper-bound theory of isolated iron ion ratio.
The iron that exists with isolated iron ion form described herein is not picture iron oxide (Fe
2O
3) wait such agglomerate, and be meant and be scattered in the silicate skeleton or on the ion-exchange site and the isolated iron ion that exists refers to detected iron ion in electron spin resonance is measured particularly.
The structural symmetry of ferrous components can be measured by electron spin resonance determination method (measuring temperature 77K).
Paramagnetic iron ion (Fe
3+) in measuring, electron spin resonance demonstrates RESONANCE ABSORPTION, and known, absworption peak belongs to and has g
And g〉material (in addition with reference to Journal of Catalysis, 249 (2007) 67) of at least 3 absworption peaks of 4.3.Have
The material of absworption peak belongs to and has symmetrical tetrahedral structure the isolated iron ion of (or polygamy bit architecture of high symmetry), has
And g〉4.3 iron ions that absorb belong to the isolated iron ion with distortion tetrahedral structure and distortion polygamy bit architecture.
Promptly, iron-holder is the isolated iron ion with symmetrical tetrahedral structure more than 20% in β type ferrosilite 1, and, iron-holder is the isolated iron ion with symmetrical tetrahedral structure more than 60% in β type ferrosilite 2, and these content can absorb isolated iron ion containing ratio that light measurement tries to achieve by above-mentioned UV, visible light and multiply by the product of measuring the symmetrical tetrahedral structure containing ratio of trying to achieve by electron spin resonance and obtain.
In β type ferrosilite 2, the isolated iron ion with symmetrical tetrahedral structure this means in electron spin resonance is measured for all isolated more than 70% of iron ion
The electron spin resonance wave spectrum intensity with respect to
And g〉whole wave spectrum intensity sums of 4.3 are more than 70%.
Because the general wave spectrum of representing with differential form that adopts of electron spin resonance wave spectrum is estimated, the intensity of electron spin resonance wave spectrum also adopts the amplitude length of differential curve to obtain in the present invention.That is, the ratio with isolated iron ion of symmetrical tetrahedral structure is
The electron spin resonance wave spectrum the differential curve amplitude length divided by
And g〉each amplitude size sum of 4.3 and the value that obtains.
The electron spin resonance wave spectrum can be measured with general method.For example, use electron spin resonance device (JES-TE200 that (strain) NEC makes), condition determination can be made as 77K with measuring temperature, microwave output power is 1.0mW, range of observation is 0～1000mT, and modulated amplitude is 0.32mT, and time constant is 0.3sec.Take by weighing about 10mg sample and put into the sample cell that quartz is made, measure after inserting the Dewar bottle be used to measure liquid nitrogen temperature.
In the present invention, the following mensuration of measured value that the evaluation of electron spin resonance wave spectrum is used: under the atmosphere of dry air and/or nitrogen, remove (title fresh state) behind the SDA in the micropore by about 600 ℃ burning till, measure and obtain in the mensuration temperature of 77K.
Belonging to of β type ferrosilite 1 of the present invention and β type ferrosilite 2
The peak strength of differential absorption curve of electron spin resonance wave spectrum (measure temperature 77K) be preferably greater than
And g〉any one peak strength in 4.3 the differential absorption curve.
In β type ferrosilite 1 of the present invention, the ratio with isolated iron ion of symmetrical tetrahedral structure is more than 20% of iron-holder, preferably more than 30%.Have the iron ion ratio of symmetrical tetrahedral structure, be no more than 100% in theory.
In β type ferrosilite 2 of the present invention, the ratio with isolated iron ion of symmetrical tetrahedral structure is all isolated more than 70% of iron ion, particularly preferably in more than 80%.This ratio is no more than 100% in theory.
In addition, in β type ferrosilite 2 of the present invention, the ratio of isolated iron ion with symmetrical tetrahedral structure with respect to total iron-holder preferably more than 60%, particularly preferably in more than 70%.Though its upper limit is not particularly limited, be no more than 100% in theory.
And, absorb the isolated iron ion that obtains confirming in the light measurement at UV, visible light and pass through other approach load iron on β type ferrosilite, can increase its absolute magnitude., such iron ion is not to be substituted in the crystallization skeleton after all, and is because major part is not symmetrical tetrahedral structure, less to the contribution of nitrogen oxide selective reduction.Therefore, β type ferrosilite of the present invention under the less situation of the isolated iron ion ratio that UV, visible light absorption light measurement method is measured, can not have been given play to excellent properties even increase iron-holder.
β type ferrosilite 1 of the present invention also can be the ferrosilite aluminium that contains aluminium in the structure.For the preferred SiO of this ferrosilite aluminium
2/ Al
2O
3Mol ratio is not particularly limited, but considers SiO from the viewpoint of durability (the low temperature catalyst activity after especially durable)
2/ Al
2O
3Mol ratio is preferably bigger.As long as iron ion is in belonging to scope of the present invention, SiO
2/ Al
2O
3Mol ratio is preferably more than 40, more preferably more than 70.
β type ferrosilite 1 of the present invention also has higher nitrogen oxide reducing property after durable processing, even if after durable processing, the isolated iron ion ratio of the symmetrical tetrahedral structure that exists in the β type ferrosilite is still higher.
After durable processing, the isolated iron ion ratio in the β type ferrosilite 1 of the present invention is with respect to iron-holder, preferably more than 50%, particularly preferably in more than 60%, further preferably more than 70%.
In addition, so-called " durable processing " is that habitual processing is meant containing H for the hydro-thermal durability of estimating silicate catalyst here
2The heat treatment of carrying out in the high-temperature atmosphere of O.For example, insert silicate catalyst in reaction tube, 700 ℃ of following experience made and contain H in 20 hours
2The air circulation of O flows and carries out durable processing.Concrete treatment conditions are documented among the embodiment of back.β type ferrosilite catalyst of the present invention has higher hydro-thermal durability, also keeps higher purification of nitrogen oxides performance after the durable processing.
The isolated iron ion ratio that has symmetrical tetrahedral structure in the β type ferrosilite 1 of the present invention also surpasses 15% after durable processing, be preferably especially to remain on more than 20%.
Then, in β type ferrosilite 2 of the present invention, have the containing ratio of the isolated iron ion of symmetrical tetrahedral structure, it is above (with Fe to be preferably 2 moles of %
3+/ (Si+Al+Fe) molar ratio computing).
Even it is bigger to have the isolated iron ion ratio of symmetrical tetrahedral structure, if but its absolute magnitude very little, the purifying property of nitrogen oxide is still lower.
Absolute magnitude with isolated iron ion of symmetrical tetrahedral structure is the numerical value of following acquisition: the iron molal quantity Fe/ (Si+Al+Fe) in the β type ferrosilite multiply by the ratio of the isolated iron ion of obtaining with the UV, visible light absorption spectrum, multiply by the ratio of the isolated iron ion with symmetrical tetrahedral structure in the isolated iron ion of being obtained by the electron spin resonance wave spectrum again and obtains.
The containing ratio of the iron with isolated symmetrical tetrahedral structure in the β type ferrosilite 2 of the present invention is 2 moles more than the %, more preferably at 2.2 moles more than the %.On the other hand, because the present invention stipulates SiO
2/ Fe
2O
3Mol ratio following is limited to 20 (the Si/Fe mol ratio is 10), and the upper limit that therefore has the isolated iron ion absolute magnitude of symmetrical tetrahedral structure is about 9.1 moles of % (1/ (10+0+1)).
Also have the reducing property of higher nitrogen oxide after the β type ferrosilite 2 durable processing of the present invention, after durable processing, the ratio of the isolated iron ion with symmetrical tetrahedral structure that exists in the β type ferrosilite is still higher.
The isolated iron ion that has symmetrical tetrahedral structure in the β type ferrosilite 2 of the present invention with respect to the electron spin resonance determination method can detected isolated iron ion ratio after durable processing, also surpass 40%, particularly preferably in more than 80%, more preferably remain on more than 90%.
The isolated iron ion that has symmetrical tetrahedral structure in the β type ferrosilite 2 of the present invention also surpasses 20% with respect to total iron-holder after durable processing, be preferably especially to remain on more than 40%, more preferably remains on more than 50%.
The absolute magnitude that has the isolated iron ion of symmetrical tetrahedral structure in the β type ferrosilite 2 of the present invention also surpasses 0.6 mole of % after durable processing, be preferably especially and remain on 1 mole more than the %, more preferably remains on 1.5 moles more than the %.
After durable processing, the ratio of isolated iron ion is preferably with respect to iron-holder and surpasses 50% in the β type ferrosilite 2 of the present invention, and preferred especially this ratio not only is meant isolated iron ion, but has the isolated iron ion of above-mentioned symmetrical tetrahedral structure.
Then, illustrate that β type ferrosilite 1 of the present invention reaches and the manufacture method of β type ferrosilite 2.
β type ferrosilite 1 of the present invention is by the high dispersive of introducing capacity in the ferrosilite skeleton and the Fe with high symmetrical tetrahedral structure
3+Make.The mole control recently of the iron of introducing is crossed by this high dispersive Tie Tong in the skeleton in the silicate skeleton.
β type ferrosilite 2 of the present invention can be made by the following method, reaches SiO according to the composition of the β type ferrosilite that obtains
2/ Fe
2O
3Mol ratio is 20～300, and log (SiO
2/ Al
2O
3) be 2 with on control batching and form, and carry out crystallization.
In the crystallization under this condition, can introduce with isolated iron ion form high degree of dispersion in the skeleton structure of β type ferrosilite, and have the isolated iron ion of high symmetrical tetrahedral structure.
When the amount of iron is too many,, introduce the iron ion deficiency of isolated symmetrical tetrahedral structure, also cause the crystallinity of β type ferrosilite to reduce easily because freshization processing (Off レ ッ シ ュ processing) or durable processing cause assembling easily.
Though reckon with when in the skeleton of β type ferrosilite, introducing Al and Fe to form competitive reaction, because the Al content of the present invention's competition is less, so think the ratio that helps to increase isolated iron ion with symmetrical tetrahedral structure.
Synthesize and comprise silica source, source of iron, SDA and water, as required, also use aluminium source and fluorine source with raw material.
As silica source, can use cataloid, amorphous silica, sodium metasilicate, tetraethyl orthosilicate, silicate gel etc.As source of iron, can use ferric nitrate, iron chloride, ferric sulfate, metallic iron etc.These raw materials preferably with the full and uniform state that mixes of other composition.
As the SDA raw material, can use more than at least a in the following compound: tetraethyl ammonium hydroxide with tetraethylammonium cation, tetraethylammonium bromide, tetraethyl ammonium fluoride, eight di-2-ethylhexylphosphine oxide quinines (octamethylenebisquinuclidinium), α, α '-two quinine (diquinuclidinium)-paraxylene, α, α '-two quinine (diquinuclidinium)-meta-xylene, α, α '-two quinine (diquinuclidinium)-ortho-xylene, 1,4-diazabicyclo [2,2,2] octane, 1,3,3, N, N-pentamethyl-6-nitrogen dicyclo [3,2,1] octane or N, N-diethyl-1,3,3-trimethyl-6-nitrogen dicyclo [3,2,1] octane cation.
Can use aluminum sulfate, sodium aluminate, aluminium hydroxide, aluminum nitrate, silicate gel, metallic aluminium etc. as the aluminium source, can use hydrofluoric acid, sodium fluoride, potassium fluoride, ammonium fluoride, tetraethyl ammonium fluoride etc. as the fluorine source.
These materials preferably can form the form of full and uniform mixing with other composition.
The ingredient groups precedent of the raw mix when making the β type ferrosilite 1 of the present application is as being following compositing range.
SiO
2/ Al
2O
3Mol ratio is 15～30000, preferred 30～100
SiO
2/ Fe
2O
3Mol ratio is 20～300, and is preferred below 100
H
2O/SiO
2Mol ratio is 5～50, preferred 5～10
SDA/SiO
2Mol ratio is 0.1～5, preferred 0.1～1
F/SiO
2Mol ratio is 0～5, preferred 0～1
The ingredient groups precedent of the raw mix when making the β type ferrosilite 2 of the present application is as being following compositing range.
SiO
2/ Al
2O
3Mol ratio is more than 15, also can not add Al
2O
3
SiO
2/ Fe
2O
3Mol ratio is 20～300, and is preferred below 100
H
2O/SiO
2Mol ratio is 5～50, preferred 5～10
SDA/SiO
2Mol ratio is 0.1～5, preferred 0.1～1
F/SiO
2Mol ratio is 0～5, preferred 0～1
But, even under the situation of any one in making β type ferrosilite 1 of the present invention and β type ferrosilite 2, also can not limit the compositing range of these materials, can reach according to the composition of end product in the compositing range of β type ferrosilite of the present invention and set arbitrarily.In addition, can also add the composition that crystal seed etc. has the crystallization facilitation, preferably obtain condition than the megacryst particle diameter.
Raw mix by making water, silica source, source of iron, SDA, the aluminium source of using as required and fluorine source with 100～180 ℃ temperature crystallization, can obtain β type ferrosilite 1 of the present invention and β type ferrosilite 2 in the closed pressure vessel.
During crystallization, raw mix also can be to mix the state that stirs, and also can be the state that leaves standstill, but be preferably the state that leaves standstill especially.After crystallization finishes, fully after the cooling, carry out Separation of Solid and Liquid, clean with the washing of capacity, dry under 110～150 ℃ temperature, obtain β type ferrosilite 1 of the present invention and β type ferrosilite 2.
In order to obtain β type ferrosilite 1 of the present invention and β type ferrosilite 2, the special bigger β type ferrosilite of preferred crystal particle diameter (SEM particle diameter).The SEM diameter should surpass 5 μ m, preferably more than 7 μ m, more than 10 μ m.Carrying out crystallization obtains the bigger crystal of particle diameter easily with stirring by not having.
β type ferrosilite 1 of the present invention and β type ferrosilite 2 are owing to contain active isolated iron ion, so can be directly use as the cleaning catalyst of nitrogen oxide, but β type ferrosilite 1 after just synthetic and β type ferrosilite 2 are because pore contains SDA, preferably after removing these materials as required, the cleaning catalyst that is re-used as nitrogen oxide uses.
SDA removes processing and can adopt the liquid phase of the soup that uses the composition contain acid solution or to decompose SDA to handle, use exchange processing, the thermal decomposition process of resin etc.Also can be used in combination these processing methods.In addition, also can adopt ion-exchange can make it to be transformed into H type and NH by β type ferrosilite
4Type uses.
Also can adopt in β type ferrosilite 1 of the present invention and β type ferrosilite 2 further load to have the metal kind of catalytic activity.
Though the metal kind of load is not particularly limited, be preferably for example element of the 8th, 9,10 families, 11 families, be preferably selected from more than one the element in iron, cobalt, palladium, iridium, platinum, copper, silver, the gold especially.The element of more than one in preferred especially iron, palladium, platinum, copper, the silver.
Also can add co-catalyst component such as rare earth metal, titanium, zirconium in addition.The carrying method that has in load under the situation of metal kind of catalytic activity is not particularly limited.Carrying method can use methods such as ion-exchange, dip loading method, evaporation drying method, precipitating load method, physical mixed method.Nitrate, sulfate, acetate, chloride, complex salt, oxide, composite oxides etc. all can be used as the used raw material of metal load and use.
The load capacity of metal is unqualified, but is preferably the scope of 0.1～10 weight % especially.
Catalyst of the present invention uses by carrying out hybrid shaping with adhesives such as silica, aluminium oxide and clay minerals.The clay mineral that uses during as shaping for example can be kaolin, attapulgite (attapulgite), montmorillonite, bentonite, allophane, sepiolite.Also can cordierite make or metal honeycomb fashion base material on impose wash coat (Wash coat) and use.
Use β type ferrosilite of the present invention as catalyst for purification of nitrogen oxides, use nitrogen oxide and ammonia, urea, at least a of organic amine to react, optionally reduce nitrogen oxides from exhaust gas as reducing agent.
The nitrogen oxide that is cleaned among the present invention is nitric oxide, nitrogen dioxide and their mixture.Herein, the nitrogen oxides of exhaust gas concentration of handling by the present invention is not particularly limited.
The adding method of reducing agent is not particularly limited, and can adopt gas form directly to add the method for reduction composition, the method that makes liquid spraying gasifications such as the aqueous solution, atomizing thermolysis process etc.The addition of these reducing agents can be according to making nitrogen oxide be able to fully purify set arbitrarily.
In addition, this waste gas also can contain the composition beyond the nitrogen oxide, for example, can also contain hydrocarbon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, oxysulfide, water.Specifically, method of the present invention can purify from diversified nitrogen oxides from exhaust gas such as diesel-engined vehicle, gasoline engine car, boiler, gas turbines.
In purification of nitrogen oxides method of the present invention, the space velocity the when catalyst that comprises β type ferrosilite of the present invention is contacted with waste gas is not particularly limited, and preferred space velocity is 500～500,000 hr with the volume during for benchmark
-1, 2000～300000hr more preferably
-1
The purification of nitrogen oxides performance of β type ferrosilite 1 of the present invention and β type ferrosilite 2 of the present invention is higher, in the wide cut temperature province, special in the lower temperature zone below 250 ℃ effective purifying nitrogen oxide, durability is good, durable processing rear catalyst activity is still than known product height.
Embodiment
Below, the present invention is described in conjunction with the embodiments, but the present invention is not limited to these embodiment.
(UV, visible light absorption light measurement)
UV, visible light is light absorbing to be determined at following condition and to carry out.
The device of band integrating sphere: the ISR-3100 that (strain) Shimadzu Seisakusho Ltd. makes
Uatomatic recording spectrophotometer: the UV-3100 that (strain) Shimadzu Seisakusho Ltd. makes
Sweep speed: 200nm/min
Slit width: 5.0nm
Baseline (ベ-ス ラ イ Application) is revised: use the barium sulfate powder
The measuring reflectance of wave-length coverage: 220～700nm
Sample pre-treatments: in the dry air, 600 ℃ are burnt till (fresh roasting (Off レ ッ シ ュ baked one-tenth))
(electron spin resonance mensuration)
Carrying out electron spin resonance with following condition measures.
Measure temperature: 77K
Microwave output: 1.0mW
Observation scope: 0～1000mT
The modulation length (Bian Tone width of cloth): 0.32mT
Time constant: 0.3sec
Sample size: about 10mg
(purification of nitrogen oxides test)
Ferrosilite powder pressing synthetic in embodiment, comparative example, pulverize then, make 12～20 purpose particles.The powder 1.5cc of particle is made in filling in atmospheric fixed bed flow type reaction tube.Gas with the composition in the tabulation 2 is down circulated with 1500cc/min at catalyst layer, simultaneously, under the arbitrary temp of 100～500 ℃ of scopes, measure stable nitrogen oxide and remove rate.
[table 2]
| Gas | Concentration |
| NO | 200ppm |
| NH 3 | 200ppm |
| O 2 | 10vol％ |
| H 2O | 3vol％ |
| N 2 | Balance |
Removing the activity of nitrogen oxide represents with following formula.
X
NOx＝{([NOx]
in-[NOx]
out)/[NOx]
in}×100
Here, X
NOxThe purifying rate (%) of expression nitrogen oxide, [NOx]
InThe nitrous oxides concentration of expression inflow gas, [NOx]
OutThe nitrous oxides concentration of expression eluting gas.
The following mensuration of performance after the durable processing: in atmospheric fixed bed flow type reaction tube, add each catalyst 3cc, under 700 ℃, made through 20 hours and to contain H
2The air of O=10vol% circulates with 300cc/min, handle, then, with above-mentioned same condition under measure the rate of removing of nitrogen oxide.
Following embodiment 1～3rd, the embodiment of relevant β type ferrosilite 1.
Dissolving aluminum nitrate nonahydrate 18.79g, ferric nitrate nonahydrate 4.63g in the aqueous solution (to call " TEAOH " in the following text) of 257g tetraethyl ammonium hydroxide 35%, add tetraethyl orthosilicate (TEOS) 209g again, fully mix, room temperature is hydrolyzed, and evaporates the ethanol of generation.Then, evaporate the water of necessary amount.Add 48% hydrofluoric acid 20.88g therein, after mixing with mortar, in stainless steel autoclave, add this reactant mixture, 150 ℃ down heating carried out crystallization in 240 hours.Reactant mixture consist of 40SiO
2: Al
2O
3: 0.23Fe
2O
3: 20HF:24.4TEAOH:300H
2O.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with pure water, dry down at 110 ℃.
Under circulation of air, in this dried powder of 600 ℃ of following roastings 2 hours.The result that the β type ferrosilite process X-ray diffraction that obtains is measured has obtained the X-ray diffraction figure shown in the table 1 as can be known.The result of ICP luminesceence analysis, SiO
2/ Al
2O
3Mol ratio is 41, SiO
2/ Fe
2O
3Mol ratio is 166.Crystal particle diameter is 10 μ m.
Except the ratio of components of the reactant mixture of crystallization is become 70SiO
2: Al
2O
3: 0.47Fe
2O
3: 35HF:42TEAOH:490H
2Beyond the O, by operating procedure preparation reactant mixture similarly to Example 1.In stainless steel autoclave, add this reactant mixture, carried out crystallization in 160 hours 150 ℃ of heating.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, in this dried powder of 600 ℃ of following roastings 2 hours.
The result who is measured by the X-ray diffraction of the β type ferrosilite that obtains has obtained the X-ray diffraction figure shown in the table 1 as can be known.
Except the ratio of components of the reactant mixture of crystallization is become 70SiO
2: Al
2O
3: Fe
2O
3: 35HF:42TEAOH:490H
2Beyond the O, by operation preparation reactant mixture similarly to Example 1.In stainless steel autoclave, add this reactant mixture, heat down at 150 ℃ and carried out crystallization in 240 hours.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, burnt till this dried powder 2 hours in 600 ℃.
The result that the X-ray diffraction of the β type ferrosilite that obtains is measured has obtained the X-ray diffraction figure shown in the table 1.
Fig. 1 illustrates the ultraviolet-visible absorption spectroscopy of β type ferrosilite (before the durable processing).Fig. 2 illustrates a durable example handling the electron spin resonance wave spectrum of front and back β type ferrosilite 1.
Comparative example 1
Flow down at dry air, in 600 ℃ of roasting SiO
2/ Al
2O
3Mol ratio is the zeolite beta (trade name: HSZ-940NHA) that 40 TOSOH makes.The result that X-ray diffraction is measured shows that zeolite beta has the X-ray diffraction figure of table 1, and the result of ICP luminesceence analysis shows, SiO
2/ Al
2O
3Mol ratio be 40.Use is 3 weight % and the accurate Fe (NO of weighing according to the load capacity of iron
3)
39H
2The aqueous solution of O, impregnation and load iron on this zeolite beta.It is burnt till in 500 ℃ air.
After the impregnation processing by iron, the total content of iron is more, is 38% but UV, visible light absorbs the containing ratio of the isolated iron ion of light measurement, and the iron of cohesion is also more.
Fig. 3 illustrates the example of electron spin resonance spectroscopy figure that load before and after durable handle has the zeolite beta of iron.
Comparative example 2
In the aqueous solution (to call " TEAOH " in the following text) of the tetraethyl ammonium hydroxide 35% of 235g, add aluminium hydroxide 1.26g, ferric nitrate 8.36g, (trade name: ニ ッ プ シ-Le VN-3) 62.8g and water 172g fully mix the amorphous silica powder that TOSOH Silica makes.The composition of reactant mixture is 90SiO
2: Al
2O
3: Fe
2O
3: 54TEAOH:1800H
2O.This reactant mixture of sealing in stainless steel autoclave carried out crystallization in 96 hours 150 ℃ of heating.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air,, obtain β type ferrosilite in 600 ℃ of these dried powders of following roasting.
The result that the X-ray diffraction of the β type ferrosilite that obtains is measured obtains the X-ray diffraction figure shown in the table 1, but is 78% by the containing ratio that UV, visible light absorbs the isolated iron ion that light measurement obtains.
Table 3 (before the durable processing, fresh) and table 4 (the durable back of handling) are illustrated in the durable purifying property evaluation result of handling the front and back nitrogen oxide of the catalyst that obtains in embodiment 1～3 and the comparative example 1～2.For before the durable processing and durable processing after catalyst, obtain the relation of the purification of nitrogen oxides performance of the ratio of ratio that UV, visible light absorbs the isolated iron ion of light measurement, symmetrical tetrahedral structure that electron spin resonance is measured and the low temperature after the durable processing (below 250 ℃), what obtain the results are shown in table 5 (before the durable processing: fresh) and the table 6 (durable processings afterwards).
[table 3]
※ is because the catalyst of comparative example 1 is a load iron just afterwards, therefore with () expression SiO
2/ Fe
2O
3
[table 4]
[table 5]
Before the durable processing
(a) mol ratio of iron-holder (Fe/ (Si+Al+Fe) mol ratio)
(b) isolated iron ion is with respect to ratio (the isolated Fe of total iron-holder
3+/ whole Fe)
(c) the isolated iron ion of symmetrical tetrahedral structure is with respect to ratio (the isolated Fe with symmetrical tetrahedral structure of whole isolated iron ions
3+/ whole isolated Fe
3+)
(d) the isolated iron ion of symmetrical tetrahedral structure is with respect to ratio (the isolated Fe with symmetrical tetrahedral structure of total iron-holder
3+/ whole Fe)
[table 6]
After the durable processing
(a) mol ratio of iron content (Fe/ (Si+Al+Fe) mol ratio)
(b) isolated iron ion is with respect to ratio (the isolated Fe of total iron-holder
3+/ whole Fe)
(c) the isolated iron ion of symmetrical tetrahedral structure is with respect to ratio (the isolated Fe with symmetrical tetrahedral structure of all isolated iron ion
3+/ whole isolated Fe
3+)
(d) the isolated iron ion of symmetrical tetrahedral structure is with respect to ratio (the isolated Fe with symmetrical tetrahedral structure of total iron-holder
3+/ whole Fe)
As shown in table 5, isolate under the less situation of iron ion, the purification of nitrogen oxides performance under the low temperature is lower.Iff being to import iron by the impregnation load iron, the ratio that absorbs the isolated iron ion of light measurement observation at UV, visible light is 38%, finally causes the catalyst activity under the low temperature lower.
Following embodiment 4～6th, the embodiment of relevant β type ferrosilite 1.
Dissolving ferric nitrate nonahydrate 9.43g adds tetraethyl orthosilicate (TEOS) 214g again in the aqueous solution (to call " TEAOH " in the following text) of the tetraethyl ammonium hydroxide 35% of 264g, fully mixes, and at room temperature is hydrolyzed, and evaporates the ethanol of generation.Then, evaporate the water of necessary amount.Add 48% hydrofluoric acid 21.45g therein, after mixing with mortar, in stainless steel autoclave, add this reactant mixture, 150 ℃ down heating carried out crystallization in 240 hours.Reactant mixture consist of 62SiO
2: Fe
2O
3: 31HF:37.8TEAOH:465H
2O.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, dry down at 110 ℃.
Under circulation of air, in this dried powder of 600 ℃ of following roastings 2 hours.The result that X-ray diffraction is measured shows that β type ferrosilite has the X-ray diffraction figure identical with table 1.The result of ICP luminesceence analysis shows, SiO
2/ Al
2O
3Mol ratio is 4743, SiO
2/ Fe
2O
3Mol ratio is 62.Crystal particle diameter is 7.5 μ m approximately.
Fig. 6 illustrates the ultraviolet-visible absorption spectroscopy of β type ferrosilite (before the durable processing).In addition, Fig. 4 illustrates a durable example handling the electron spin resonance wave spectrum of front and back β type ferrosilite 2.
No. 3 sodium metasilicate (SiO that hybrid regulatory is quantitative
2: 402g/1, Na
2O:129g/1, Al
2O
3: 0.22g/1), 98% sulfuric acid, water and ferric nitrate nonahydrate, make the gel Separation of Solid and Liquid of generation with suction filter after, carry out cleaning fully with pure water.In the gel of cleaning, add water, TEAOH and the NaOH of ormal weight, fully mix.The ratio of components of reactant mixture is 1965SiO
2: Al
2O
3: 30.05Fe
2O
3: 98.27Na
2O:786.2TEAOH:19654H
2O.This reactant mixture of sealing in stainless steel autoclave carried out crystallization in 90 hours in 150 ℃ of heating in rotating condition.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, in this dried powder of 600 ℃ of following roastings 2 hours.
Embodiment 6
The ratio of components of the reactant mixture of to be crystallizedization is become 500SiO
2: Al
2O
3: 7.69Fe
2O
3: 250HF:305TEAOH:3750H
2O uses the aluminum nitrate nonahydrate, in addition, and by operation preparation reactant mixture similarly to Example 4.In stainless steel autoclave, fill this reactant mixture, heat down at 150 ℃ and carried out crystallization in 240 hours.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, in this dried powder of 600 ℃ of roastings 2 hours.
Comparative example 3
Except the ratio of components of the reactant mixture of to be crystallizedization is become 70SiO
2: Al
2O
3: Fe
2O
3: 35HF:42TEAOH:490H
2Beyond the O, by operation preparation reactant mixture similarly to Example 1.In stainless steel autoclave, add this reactant mixture, heat down at 150 ℃ and carried out crystallization in 240 hours.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, in this dried powder of 600 ℃ of roastings 2 hours.
Comparative example 4
Air in drying flows down, in 600 ℃ of roasting SiO
2/ Al
2O
3Mol ratio is the zeolite beta (trade name: HSZ-940NHA) that 40 TOSOH makes.The result that X-ray diffraction is measured shows that zeolite beta has the X-ray diffraction figure of table 2, in the ICP luminesceence analysis, and SiO
2/ Al
2O
3Mol ratio be 40.Use is the Fe (NO that 3 weight % come accurate weighing according to the iron load capacity
3)
3The aqueous solution of 9 hydrates, impregnation load iron in zeolite beta.Then with the roasting under 500 ℃ air of this dried powder.
Fig. 5 illustrates the example of electron spin resonance wave spectrum that load before and after durable handle has the zeolite beta of iron.
Comparative example 5
In the aqueous solution (to call " TEAOH " in the following text) of the tetraethyl ammonium hydroxide 35% of 235g, add aluminium hydroxide 1.26g, ferric nitrate 8.36g, (trade name: ニ ッ プ シ-Le VN-3) 62.8g and water 172g fully mix the amorphous silica powder that TOSOH Silica makes.The composition of reactant mixture is 90SiO
2: Al
2O
3: Fe
2O
3: 54TEAOH:1800H
2O.This reactant mixture of sealing in stainless steel autoclave carried out crystallization in 96 hours 150 ℃ of heating.Paste mixture behind the crystallization is white in color.This mixture is carried out Separation of Solid and Liquid, clean with the pure water of q.s, 110 ℃ of dryings.Under circulation of air, with it 600 ℃ of following roastings.
Table 7 (before the durable processing, fresh) and table 8 (the durable back of handling) are illustrated in the durable evaluation result of handling the purification of nitrogen oxides performance of front and back of the β type ferrosilite that obtains in embodiment 4～6 and the comparative example 3～5.To before the durable processing and durable processing after catalyst, obtain by UV, visible light and absorb relation between the nox purification rate (after the durable processing) of isolated iron ion ratio, isolated iron ion ratio and low temperature (200 ℃, 250 ℃) that light and electron spin resonance measure with symmetrical tetrahedral structure, the result is illustrated in table 9 (before the durable processing, fresh), the table 10 (durable processing back).
Fig. 7 represents log (SiO
2/ Al
2O
3) and low temperature (200 ℃) under the relation of nox purification rate.Clearly show among Fig. 7, at log (SiO
2/ Al
2O
3) be 2 when above, find that the purifying rate under the low temperature (200 ℃) after the durable processing is increased sharply, at Log (SiO
2/ Al
2O
3) be 2 o'clock, find to have critical flex point.
[table 7]
※ is because comparative example 4 is load irons just afterwards, therefore with () expression SiO
2/ Fe
2O
3
[table 8]
[table 9]
Before the durable processing
(a) the mol ratio Fe/ of iron content (Si+Al+Fe) mol ratio
(b) the isolated iron ion Fe isolated with respect to the ratio of total iron-holder
3+/ whole Fe
(c) the isolated iron ion of symmetrical tetrahedral structure has the isolated Fe of symmetrical tetrahedral structure with respect to the ratio of whole isolated iron ions
3+/ whole isolated Fe
3+
(d) the isolated iron ion of symmetrical tetrahedral structure has the isolated Fe of symmetrical tetrahedral structure with respect to the ratio of total iron-holder
3+/ whole Fe
(e) has the isolated Fe of mole % of the isolated iron ion of symmetrical tetrahedral structure
3+/ (Si+Al+Fe)
[table 10]
After the durable processing
(a) iron content mol ratio Fe/ (Si+Al+Fe) mol ratio
(b) the isolated iron ion Fe isolated with respect to the ratio of total iron-holder
3+/ whole Fe
(c) the isolated iron ion of symmetrical tetrahedral structure has the isolated Fe of symmetrical tetrahedral structure with respect to the ratio of whole isolated iron ions
3+/ whole isolated Fe
3+
(d) the isolated iron ion of symmetrical tetrahedral structure has the isolated Fe of symmetrical tetrahedral structure with respect to the ratio of total iron-holder
3+/ whole Fe
(e) has the isolated Fe of mole % of the isolated iron ion of symmetrical tetrahedral structure
3+/ (Si+Al+Fe)
Claims (7)
1. catalyst for purification of nitrogen oxides, it is included in the crystallized silicon hydrochlorate that contains iron in the β skeleton structure, wherein, SiO
2/ Fe
2O
3Mol ratio be 20～300, and that total iron-holder of described silicate is isolated iron ion (Fe more than 80%
3+).
2. catalyst for purification of nitrogen oxides according to claim 1, wherein, always that iron-holder is the isolated iron ion (Fe with symmetrical tetrahedral structure more than 20%
3+).
3. catalyst for purification of nitrogen oxides, it is included in the crystallized silicon hydrochlorate that contains iron in the β skeleton structure, wherein, SiO
2/ Fe
2O
3Mol ratio be 20～300, and log (SiO
2/ Al
2O
3) be more than 2.
4. catalyst for purification of nitrogen oxides according to claim 3 wherein, has the isolated iron ion (Fe of symmetrical tetrahedral structure
3+) be all isolated iron ion (Fe
3+) more than 70%.
5. catalyst for purification of nitrogen oxides according to claim 3 wherein, has the isolated iron ion (Fe of symmetrical tetrahedral structure
3+) be more than 60% of total iron-holder.
6. according to any described catalyst for purification of nitrogen oxides in the claim 3～5, wherein has the isolated iron ion (Fe of symmetrical tetrahedral structure
3+) content (Fe
3+/ (Si+Al+Fe)) be 2 moles more than the %.
7. the purification method of a nitrogen oxide, this method is used each described catalyst for purification of nitrogen oxides in the claim 1～6, by make nitrogen oxide with as at least a the reacting in the ammonia of reducing agent, urea, the organic amine compound, optionally nitrogen oxides reduction.
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| JP2009166031A (en) | 2009-07-30 |
| JP5169779B2 (en) | 2013-03-27 |
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