CN1131724C - Compositions used as NOX trap, based on manganese and alkaline or alkaline-earth and use for treating exhaust gases - Google Patents

Compositions used as NOX trap, based on manganese and alkaline or alkaline-earth and use for treating exhaust gases Download PDF

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Publication number
CN1131724C
CN1131724C CN008078866A CN00807886A CN1131724C CN 1131724 C CN1131724 C CN 1131724C CN 008078866 A CN008078866 A CN 008078866A CN 00807886 A CN00807886 A CN 00807886A CN 1131724 C CN1131724 C CN 1131724C
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carrier
manganese
composition
potassium
elements
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CN1354686A (en
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T·伯彻姆
C·海杜因
T·塞古隆
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Rhodia Chimie SAS
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Rhone Poulenc Chimie SA
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    • 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
    • B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
    • 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
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • 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
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/32—Manganese, technetium or rhenium
    • B01J23/34—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B01D2255/2022—Potassium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B01D2255/2027—Sodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2042—Barium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/2073—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Combustion & Propulsion (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Treating Waste Gases (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

The invention relates to compositions used as NOx trap, based on manganese and an alkaline or an alkaline-earth and their use for treating exhaust gases. Said compositions comprise a carrier and an active phase; and they are characterised in that the active phase is based on manganese and at least another element A selected among alkalines or alkaline-earths, the manganese and element A being chemically bound. Said compositions can be used in a process for treating gases to reduce nitrogen oxide emissions, as NOx traps, said gases being derived from internal combustion engines and in particular diesel engines or lean-burn engines.

Description

As NO xTrap based on the composition of manganese and alkali metal or alkaline-earth metal and the application in exhaust-gas treatment thereof
Invention field
The present invention relates to as NO xTrap based on the composition of manganese and alkali metal or rare earth metal and the application in exhaust-gas treatment thereof.Can use the three-way emission control agent to reduce the nitrogen oxide (NO that particularly discharges from vehicle engine exhaust gas x), utilize to the metering of three-way emission control thinner the reducing gas in the gaseous mixture.Any excessive oxygen all can make the performance of catalyst significantly degenerate.
Background technology
But some engine for example Diesel engine or lean mixture petrol engine can effectively utilize the alkene material, but discharging always contains the waste gas of a large amount of excessive oxygens, for example at least 5% oxygen.Therefore, in this case, the three-way emission control agent of standard is for reducing NO xDischarging be invalid.In addition, because constantly strict automobile after-combustion rules have expanded such engine now to, so propose NO xThe restriction of discharging.
In order to address this problem, the various NO of being called have been proposed xThe system of trap (trap), they can be oxidized to NO with NO 2, and then absorb the NO that generates 2Under certain conditions, NO 2Leached, can be reduced into N by reducing substances contained in the waste gas then 2But, these NO xTrap has many shortcomings.For example, their optimum operation scope is in low relatively humidity province, usually at 200-270 ℃, and under higher temperature their limited low efficient or inefficent.Therefore, it is important being provided at than the system that works under the higher temperature of the temperature of existing system.In addition, they have low heat endurance at the hydro-thermal medium or in the high-temperature oxydation medium.Therefore, the improvement of this stability will constitute an advantage.In addition, they are usually based on noble metal.These metals are expensive, and its for the property may also be a problem.Can provide that to contain that non-noble metal catalyst reduces cost also be that people are interested in.
Summary of the invention
Therefore, the purpose of this invention is to provide and a kind ofly can at high temperature be used as NO xThe composition of trap, and optional their use base metals.The present invention also aims to provide a kind of NO that good thermal stability is arranged xTrap.
For this reason, the present invention can be used as NO xThe composition of trap be is characterized in that by carrier and active phase composition active in manganese and at least a other elements A that are selected from alkali metal or alkaline-earth metal, manganese and elements A are by chamical binding; Following situation is excluded: at first, A is the composition of potassium, and wherein carrier is provided its atomic ratio [K]/([K]+[CeO for cerium oxide and manganese and two kinds of elements of potassium by potassium permanganate 2])=0.16 and [Mn]/([Mn]+[CeO 2])=0.16; Secondly, A is the composition of potassium, and wherein carrier is based on cerium oxide, zirconia and lanthana, and its oxide weight ratio is 72/24/2, and carrier also has the storage oxygen capacity of 2.8 milliliters of oxygen/grams.
The specific embodiment
Other features of the present invention, detailed content and advantage are from following description and in order to illustrate that given non-limiting example will become clearer.
The term that uses in this description " rare earth metal " refers to the element of yttrium and periodic table atomic number 57-71.
The storage oxygen capacity of mentioning in this description is measured with such test, CO content that the continuous oxidation of this test evaluation carrier or product is introduced and the amount that consumes the oxygen of introducing for oxidation product.Used method is called a kind of alternative method.
Carrier gas is pure helium, and flow velocity is 10 liters/hour.Introduce with the loop of containing 16 milliliters of gases.CO introduces with containing the gaseous mixture that 5%CO is diluted in the helium, and O 2With containing 2.5%O 2The gaseous mixture that is diluted in the helium is introduced, with thermal conductivity assessor gas chromatograph analytical gas.
The oxygen amount that consumes can draw the storage oxygen capacity that will measure.The character numerical value of storage oxygen capacity is expressed as the product that a milliliter oxygen (under the normal temperature and pressure condition)/gram is introduced, and measures down at 400 ℃.The storage oxygen capacity that provides in this description is used under 900 ℃ in air that 6 hours product of preliminary treatment draws in Muffle furnace.
Composition of the present invention is by carrier and active phase composition.The broad sense of its name should be considered in term " carrier ", in its composition for essential element and/or do not have catalytic activity or trap is active or catalytic activity or the trap activity that is different from active phase arranged; And other element depositions are on it.For simplicity, the remainder of describing will be discussed carrier and activity mutually or the load phase, but should be appreciated that scope of the present invention comprises that also described element mutually active as formation or load phase part exists in the situation in the carrier, for example introduces in the preparing carriers process.
In characteristics of the present invention, active based on manganese and at least a other elements A that is selected from alkali metal and alkaline-earth metal.Alkali metal example more specifically is sodium and potassium.Barium can be used as alkali earth metal.Because composition can contain one or more elements A, so the situation that several elements A exist that comprises all should be thought in any place of mentioning elements A in the remainder of this description.
In addition, in composition of the present invention, element manganese and A exist with the form of chamical binding.This just means between manganese and the elements A because there is chemical bond in the result of reaction, and these two kinds of elements are not that the form with simple mixtures puts together simply.For example, element manganese can compound or the form existence mutually of mixed oxide type with A.This compound or phase can specifically be used chemical formula A xMn yO 2 ± δ(1) expression, 0.5≤y/x in the formula≤6, and the oxidation state of the character of the numerical value of δ and elements A and manganese is relevant.The phase of the chemical formula that can mention (1) or the example of compound are vernadite, hollandite, romanechite or psilomelane, sodium manganite, todorokite, buserite or phosphorus cryptomelane-type compound.It is hydration that compound can be chosen wantonly.Compound also can have stratiform CdI 2The type structure.Provide chemical formula (1) in order to illustrate here, and scope of the present invention also includes the compound of different chemical formula, condition is that manganese and elements A are chamical bindings certainly.The provable such compound of X-ray analysis or electron-microscopic analysis exists.
The oxidation state of manganese can be in the 2-7 scope, more specifically in the 3-7 scope.
As for potassium, this element and manganese can K 2Mn 4O 8The form of type compound exists.As for barium, it can be BaMnO 3The type compound.
The present invention relates to such situation, wherein active phase is made up of manganese and at least a other elements A that are selected from alkali metal and alkaline-earth metal basically, and manganese and elements A are chamical bindings.So-called " basically by ... form " refer to that composition of the present invention also can have NO under the active condition mutually of any element that is not different from manganese and elements A xThe trap activity, for example noble metal or other are used for the element of the metal types of catalytic action.
Compound of the present invention also contains carrier.Carrier can be any porous carrier that can be used for catalytic action.Preferably, this carrier is enough chemically inert for element manganese and A, to avoid one or more and carrier in the element significant reaction is arranged, and this reaction can be detrimental between manganese and the elements A and forms chemical bond.But, just in case react between carrier and these elements, can use a large amount of manganese and elements A, so that between these elements, obtain required chemical bond.
Carrier can be based on aluminium oxide.Aluminium oxide with any kind of the specific surface that is enough to be used in catalytic applications can use.Can mention by at least a aluminium hydroxide bayerite, gibbsite or zirlite, promise gibbsite and/or at least a aluminium hydroxide boehmite, boehmite and the diaspore aluminium oxide that dewaters rapidly and form for example for example.
Also can use stable aluminium oxide.As stable element, can mention rare earth metal, barium, silicon, titanium and zirconium.As rare earth metal, the most worth cerium, lanthanum or the lanthanum-neodymium mixture that should be mentioned that.
Stable aluminium oxide traditionally by with the salt of above-mentioned stable element for example nitrate solution impregnated alumina or the salt precursor by alumina precursor and these elements altogether drying then roasting prepare.
Carrier also can be based on being selected from cerium oxide and zirconic oxide or its mixture.
The cerium oxide that can mention and zirconic actual mixt are those disclosed in Europe patent application EP-A-0605274 and EP-A-0735984, and therefore the disclosure of above-mentioned patent is incorporated the present invention into.More particularly, using such is possible based on cerium oxide and zirconic carrier, and wherein cerium/the atomic percent zirconium of these oxides is at least 1.For these carriers, it also is possible using the carrier of solid solution form.In this case, the X-ray diffraction spectrum of carrier shows that single homogeneous state exists mutually in carrier.For the carrier that is rich in most cerium, this corresponds to a cube crystallization cerium oxide CeO 2Phase, what have with the pure zirconia cerium and to depart from its lattice parameter, and this is because zirconium is added to the result in the crystalline network of cerium oxide, thereby generates real solid solution.
Also can mention based on cerium oxide and these two kinds of hopcalites of zirconia and based on scandium oxide or be different from the mixture, particularly those disclosed in International Patent Application WO 97/43214 of the rare earth metal of cerium, so its disclosure is incorporated the present invention into.Specifically, this application discloses the composition based on cerium oxide, zirconia and yittrium oxide, perhaps except cerium oxide and zirconia also based at least a composition that is selected from other oxides (except cerium) of scandium oxide and rare-earth oxide, its cerium/atomic percent zirconium is at least 1.After 6 hours, the specific surface of these compositions is at least 35 meter 2/ gram 900 ℃ of following roastings, and the storage oxygen capacity under 400 ℃ is at least 1.5 milliliters of oxygen/grams.
In the present invention's one specific embodiments, this carrier is based on cerium oxide, and it also contains silica.This class carrier is open in patent application EP-A-0207857 and EP-A-0547924, so its disclosure is incorporated the present invention into.
The total content of manganese, alkali metal and alkaline-earth metal can be in a wide region.Minimum content no longer observes NO for being lower than this content xAbsorb active content.This content can be between the 2-50%, more particularly between 5-30%, and this content is with respect to % (atom) expression with the molal quantity summation of the active element that relates in mutually of the oxide of carrier.Each manganese, alkali metal and alkaline earth metal content can be in wide regions; Specifically manganese content can equal or near the content of alkali metal or alkaline-earth metal.
One embodiment of being interested in according to the present invention, alkali metal is potassium, its content (as above-mentioned calculating) can be 10-50%, more particularly is 30-50%.
Composition of the present invention can prepare with such method, and wherein carrier contacts with at least a elements A with manganese or contacts with the precursor of manganese and at least a elements A, and they are being enough to make the roasting temperature that forms chemical bond between manganese and the elements A.
A method that can be used to carry out above-mentioned contact is a dipping.Therefore, at first make the salt of load phase element or the solution or the slurries of compound.Salt can be selected from inorganic acid salt, for example nitrate, sulfate or chloride.Also can use the salt of acylate, particularly aliphatic saturated monocarboxylic acid or the salt of hydroxycarboxylic acid.The example that can mention is formates, acetate, propionate, oxalates and citrate.Use this solution or slurry carrier then.More particularly, use dried infusion process.Dried infusion process comprises that the element aqueous solution that will equal to flood the pore volume of solid is added in the product that will flood.May be favourable with active phase element deposition in two steps.For example, advantageously, sedimentation manganese in the first step, deposition of elements A in second step then.After the dipping, optional with carrier drying roasting then.Should be pointed out that use unfired carrier before dipping is possible.Active also can deposit mutually by method with the spray dried of the salt of active phase element or compound and carrier.
As what point out above, scope of the present invention does not comprise such composition, and wherein carrier is a cerium oxide, and elements A is a potassium, the ratio shown in manganese and potassium have, and wherein be used for the preparation method's that just discussed potassium and the precursor of manganese is a potassium permanganate.
As what point out above, roasting is carried out under the temperature that forms chemical bond between manganese and the elements A being enough to.This temperature is relevant with the character of elements A, but when roasting in air, this temperature is generally at least 600 ℃, more specifically at least 700 ℃, particularly 800-850 ℃.Chemical bond between manganese and elements A forms, and higher temperature normally there is no need, and higher temperature may make the specific surface of carrier descend, thereby the catalytic performance of composition is descended.Roasting time depends primarily on temperature, therefore is set to the time that is enough to form chemical bond between element.
As above-mentioned, composition of the present invention is a powder type, but they also can choose particle, bead, cylinder thing or the cellular thing that forms various sizes wantonly.
The invention still further relates to a kind of usefulness compositions-treated gas of the present invention to reduce the method for discharged nitrous oxides.Accessible in the present invention gas for example is the gas from combustion gas turbine, power station boiler or explosive motor.Under one situation of back, they can be Diesel engine or lean-burn engine.
Composition of the present invention when contacting with the gas of elevated oxygen level as NO xTrap.Term " gas of elevated oxygen level " refers to that the quantity required with respect to the chemistry of fuel metering combustion has the gas of excess of oxygen, more precisely, with respect to stoichiometric number λ=1 gas of excess of oxygen is arranged, and just the numerical value of λ is greater than 1 gas.Numerical value λ is associated with the air/fuel ratio in known manner, particularly for explosive motor.Such gas can be the gas of gas from lean-burn engine (for example the oxygen content of representing with volume is at least 2%) and elevated oxygen level, for example from the gas of Diesel engine, just at least 5% or be higher than 5%, more particularly at least 10%, this quantity may be in the 5-20% scope.
The present invention also can be used for also containing for example the above-mentioned type gas of 10% left and right sides amount of water.
The invention still further relates to a kind of gas of handling to reduce the system of discharged nitrous oxides, described gas can be the gas of the above-mentioned type, and more specifically say so those have the gas of excess of oxygen with respect to stoichiometric number.The system is characterized in that it contains above-mentioned composition.For example, it can contain the washcoat layer that catalytic property is arranged that has based on these compositions on bulk metal or ceramic base material.
At last, the invention still further relates to the application of composition in producing such system.
Provide some embodiment now.In these embodiments, estimate NO xThe test of trap is carried out as follows: with 0.15 gram graininess NO xThe trap quartz reactor of packing into.Used powder is compacted, and the particle that granularity is the 0.125-0.250 millimeter is told in broken then and screening.
At reactor inlet place reactant mixture by following the composition (by volume):
·NO：300vpm
·O 2：10％
·CO 2：10％
·H 2O：10％
·N 2：
Total flow velocity be 30 the mark liter/time.
HSV is 150000 o'clock -1About.
NO and NO xSignal ( ) temperature in reactor is by recording occurring continuously.NO and NO xSignal uses chemiluminescence principle by NO xThe ECOPHYSICS analyzer produces.
By measuring the NO that till trap is mutually saturated, absorbs xQuantity (being expressed as milligram a NO/ gram trap or an active phase) is estimated NO xTrap.Experiment repeats under 250-500 ℃ different temperatures.Therefore, might determine NO xThe optimum temperature district that trap works.
Embodiment 1-12
Raw material
Use manganese nitrate Mn (NO 3) 24H 2O, 99.5% potassium nitrate KNO 399.5% barium nitrate Ba (NO 3) 2With 99.5% sodium nitrate NaNO 3
The HSA5 that the carrier that uses provides as Rhodia The HSA1 that cerium oxide, Rhodia provide , contain the zirconia (ZrO of cerium oxide 2/ CeO 2Weight ratio is 80/20) and the HSA514 that contains silica that provides of Rhodia Cerium oxide (99.15%CeO 2, 0.85%SiO 2); All carriers are all 500 ℃ of following roastings 2 hours.
Preparation of compositions
Active also have other elements A based on manganese, is K, Ba or Na.Preparation process is as follows:
The first step: the deposition of the element of first kind of load
The first step comprises with the element M n deposition with respect to 10% (atom) of terms of oxide moles in the molal quantity of element and the carrier, that is:
[Mn]/([Mn]+[oxide of carrier])=0.1, just [oxide of carrier]=0.9.
Second step: the deposition of the element of second kind of load
This step comprises the element with second kind of load, promptly with respect to 10% (atom) deposition of the summation of oxide molar number, just:
[A]/([Mn]+[A]+[oxide of carrier])=0.1, A=K, Ba or Na in the formula.
Do dipping, comprise impregnated carrier, the element that should consider load be dissolved in the solution that its volume equals pore volume (use aquametry: 0.5 milliliter/gram) with and concentration can reach the concentration of required adding.
Under this example, element is impregnated on the carrier one by one.Use following operation scheme:
The dried dipping of first kind of element;
Stove inner drying (110 ℃, 2 hours);
In 500 ℃ of following roastings 2 hours (5 ℃/minute);
The dried dipping of second kind of element;
Stove inner drying (110 ℃, 2 hours).
After the dipping, with product in air 500 ℃, 600 ℃, 700 ℃, 800 ℃ and 850 ℃ of following roastings 6 hours.So make following composition:
For embodiment 1-8, use HSA5 Carrier; For embodiment 9 and 10, use HSA514 Carrier; For embodiment 11, use ZrO 2/ CeO 2Carrier, and, use HSA1 for embodiment 12 Carrier.
Comparative Examples 1:[Mn]=10% (atom); [K]=10% (atom); At 500 ℃ of following roastings 2 hours, SBET=115 rice 2/ gram.
Embodiment 2:[Mn]=10% (atom); [K]=10% (atom) is at 600 ℃ of following roastings 2 hours, SBET=106 rice 2/ gram.
Embodiment 3:[Mn]=10% (atom); [K]=10% (atom) is at 700 ℃ of following roastings 2 hours, SBET=15 rice 2/ gram.
Embodiment 4:[Mn]=10% (atom); [K]=10% (atom) is at 850 ℃ of following roastings 6 hours, SBET=12 rice 2/ gram.
Embodiment 5:[Mn]=10% (atom); [Ba]=10% (atom) is at 500 ℃ of following roastings 2 hours, SBET=112 rice 2/ gram.
Embodiment 6:[Mn]=10% (atom); [Ba]=10% (atom) is at 850 ℃ of following roastings 6 hours, SBET=23 rice 2/ gram.
Comparative Examples 7:[Mn]=10% (atom); [Na]=10% (atom) is at 500 ℃ of following roastings 2 hours, SBET=112 rice 2/ gram.
Embodiment 8:[Mn]=10% (atom); [Na]=10% (atom) is at 850 ℃ of following roastings 6 hours, SBET=6 rice 2/ gram.
Embodiment 9:[Mn]=10% (atom); [K]=10% (atom) is at 800 ℃ of following roastings 2 hours, SBET=6 rice 2/ gram.
Comparative Examples 10: identical among composition and the embodiment 9, but it was 500 ℃ of following roastings 2 hours; SBET=111 rice 2/ gram.
Embodiment 11:[Mn]=10% (atom); [K]=10% (atom) is at 850 ℃ of following roastings 6 hours, SBET=11 rice 2/ gram.
Embodiment 12:[Mn]=10% (atom); [K]=10% (atom) is at 850 ℃ of following roastings 6 hours, SBET=5 rice 2/ gram.
SBET is defined as according to the BET specific surface of standard A STMD3663-78 method with the nitrogen determining adsorption, said method by " JACS, 60, 309 (1938) " and the middle BRVNAVER-EMMETT-TELLER method foundation of describing.
Under the situation of Comparative Examples, X-ray analysis only shows CeO 2Phase.Under the situation of embodiment 2,3,4,9 and 11, X-ray analysis shows CeO 2Phase and K 2Mn 4O 3Phase is retrieved with reference to JCPDS16-0205.Microscopic analysis shows the megacryst of about 200 to 300 nanometers that are made of Mn and K.Manganese is in oxidation state III and IV.For embodiment 6, X-ray analysis shows CeO 2Phase and Ba 0.7MnO 3The type phase.For embodiment 8, X-ray analysis shows CeO 2Phase and Na 0.7MnO 2-δThe type phase.
In following table, provide the NO of embodiment product xThe result of trap; Numerical value shown in the table is corresponding to storage NO xAmount, represent mutually with milligram NO/ gram activity:
Table 1
T(℃) Comparative Examples 1 Embodiment 2 Embodiment 3 Embodiment 4 Comparative Examples 5 Embodiment 6
250 12.4 8.5 5.8 7.4
300 10.8 13.5 12.9 1.2 5.5 3.6
350 7.1 12.4 12.3 10.2 0.7 4.1
400 2.4 9.5 11.1 9.1 0 1.7
450 0 6.4 8.5 7.4 1.3
500 3.6 6.6
Table 2
T(℃) Comparative Examples 7 Embodiment 8 Embodiment 9 Comparative Examples 10 Embodiment 11 Embodiment 12
250 8.9
300 7.8 1.2 1.6 12.2 6 1.7
350 3.1 3.0 5.9 10.5 13.7 10.6
400 0 3.0 7.4 8.3 11.1 9.3
450 1.0 7.5 4.4 10.7 7
500 5.9 0.6 7.6 6.4
With manganese and other elements not the composition of chamical binding compare, compositions display of the present invention goes out T MaximumTo higher temperature big displacement is arranged.In addition, even under the condition of not platiniferous or other noble metals, these compositions are to storing NO xAlso be effective.
Embodiment 13
This embodiment illustrates the heat endurance of the present composition.
The composition that use is used in embodiment 4, but it in the blanket of nitrogen that contains 10% (volume) hydrogen 750 ℃ of following roastings 6 hours.The catalytic result of composition is listed following table in, for relatively it has also write down the result of embodiment 4:
Table 3
T(℃) Embodiment 13 Embodiment 4
250
300 2.3 1.2
350 10.4 10.2
400 9.3 9.1
450 6.9 7.4
500 5.4 6.6
Do not observe tangible difference between the result of the ageing products of embodiment 13 and embodiment 4.
Embodiment 14
Use carrier in this embodiment, its CeO based on cerium oxide, zirconia and lanthana 2/ ZrO 2/ La 2O 3Weight ratio was 67/23/10,800 ℃ of following roastings 2 hours.
Under these conditions, do dipping by following mol ratio with manganese and potassium:
[Mn]/([Mn]+[oxide of carrier])=0.1
[K]/([K]+[Mn]+[oxide of carrier])=0.4
After the dipping, with product 850 ℃ of following roastings 2 hours.Its SBET is 2 meters 2/ gram.
Following table 4 provides stores NO as previously indicated xAmount.
Table 4
Temperature NO xAmount
300℃ 3.9
350℃ 11.5
400℃ 20.7
450℃ 34.3
Under the situation of this embodiment, observe extra high storage NO xAmount.
Embodiment 15
Use carrier in this embodiment,, do dipping by following mol ratio with manganese and potassium under these conditions 500 ℃ of following roastings 2 hours based on aluminium oxide:
[Mn]/([Mn]+[Al 2O 3])＝0.1
[K]/([K]+[Mn]+[Al 2O 3])＝0.2
After the dipping, with product 750 ℃ of following roastings 6 hours.Its SBET is 129 meters 2/ gram.
Following table 5 provides stores NO as previously indicated xAmount.
Table 5
Temperature NO xAmount
300℃ 23.3
350℃ 22.2
400℃ 18.8
450℃ 12.8

Claims (10)

1. a gas processing method that reduces discharged nitrous oxides is characterized in that using a kind of composition as NO xTrap, described composition contain carrier with mutually active, it is characterized in that, active in manganese and at least a other elements A that are selected from alkali metal and alkaline-earth metal, manganese and elements A are by chamical binding; Following situation is excluded: at first, A is the composition of potassium, wherein carrier be cerium oxide and wherein two kinds of element manganese and potassium by atomic ratio [K]/([K]+[CeO 2])=0.16 and [Mn]/([Mn]+[CeO 2])=0.16 potassium permanganate provides, and secondly, A is the composition of potassium, and wherein carrier is based on cerium oxide, zirconia and lanthana, and its oxide weight ratio is 72/24/2, and wherein carrier also has the storage oxygen capacity of 2.8 milliliters of oxygen/grams.
2. according to the method for claim 1, it is characterized in that elements A is potassium, sodium or barium.
3. according to the method for claim 1 or 2, it is characterized in that carrier is based on being selected from aluminium oxide, cerium oxide, zirconic oxide or cerium oxide and zirconic mixture.
4. according to the method for claim 3, it is characterized in that carrier also contains silica based on cerium oxide.
5. according to the method for claim 1, it is characterized in that activity is made up of manganese and at least a elements A that is selected from potassium, sodium or barium.
6. according to the method for claim 1 or 2, it is characterized in that, handle the explosive motor exhaust gas discharged.
7. according to the method for claim 6, it is characterized in that gas to be processed contains the oxygen excessive with respect to stoichiometric number.
8. according to the method for claim 6 or 7, it is characterized in that the oxygen content in the gas is at least 2% (volume).
9. method according to Claim 8 is characterized in that, the oxygen content in the gas is at least 5 (volumes).
10. system that is used to implement the method for claim 1 is comprising the NO on bulk metal or ceramic base material xThe trap composition.
CN008078866A 1999-04-12 2000-04-10 Compositions used as NOX trap, based on manganese and alkaline or alkaline-earth and use for treating exhaust gases Expired - Fee Related CN1131724C (en)

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FR2841438A1 (en) * 2002-06-26 2004-01-02 Rhodia Elect & Catalysis CIGARETTE COMPRISING A CATALYST FOR THE TREATMENT OF SMOKE
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FR2901155B1 (en) * 2006-05-16 2008-10-10 Rhodia Recherches & Tech COMPOSITIONS USED IN PARTICULAR FOR TRACING NITROGEN OXIDES (NOX)
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