CN100503032C

CN100503032C - Catalysts for the simultaneous removal of carbon monoxide and hydrocarbons from oxygen-rich exhaust gases and processes for the manufacture thereof

Info

Publication number: CN100503032C
Application number: CNB2005800167403A
Authority: CN
Inventors: W·施特尔劳; O·格拉赫; J·迈尔; T·加布里尔
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2004-04-26
Filing date: 2005-04-25
Publication date: 2009-06-24
Anticipated expiration: 2025-04-25
Also published as: DE102004020259A1; CN101014408A

Abstract

Catalyst containing tin oxide, palladium and a carrier oxide, charaterized in that tin oxide and palladium are present on the carrier oxide in a roentgenographically amorphous or a nanoparticular form or that the carrier oxide is present in a nanoparticular form or that both tin oxide and palladium and the carrier oxide are present in nanoparticular form. Said catalyst has the function of the simultaneous removal of carbon monoxide and hydrocarbons from oxygen-rich exhaust gases.

Description

Be used for from the Catalysts and its preparation method of removal of carbon monoxide of oxygen containing waste gas while of richness and hydrocarbon

The present invention relates to from the oxygen containing waste gas of richness for example from the catalyst of removal of carbon monoxide and hydrocarbon simultaneously the waste gas of Diesel engine, poor four-stroke engine and stationary source.Described catalyst contains support oxide, and load has palladium and tin-oxide on the support oxide.In one embodiment, tin-oxide and palladium are present on the support oxide with X ray picture amorphous form or nanoscale form.In another embodiment, support oxide exists with nanoscale form.Support oxide preferably contains silicon or aluminium.Catalyst can be chosen wantonly and comprise as other platinum group metal of promoter and the oxide of indium, gallium, alkali metal, alkaline-earth metal and rare earth metal.This catalyst has the anti-sulphur that high carbon monoxide and hydrocarbon conversion performance, high heat endurance are become reconciled.The invention still further relates to the method for the described catalyst of preparation and the method for using this raw catelyst purifying waste gas.

Important harmful substance has carbon monoxide (CO), unburned hydrocarbon (HC) as alkane, alkene, aldehyde, aromatic compounds and nitrogen oxide (NO in the diesel engine exhaust _X), sulfur dioxide (SO ₂) and carbon black pellet, wherein said carbon black pellet contains the carbon that exists with solid form and with the so-called " carbon that volatility organic fraction ＂ (VOF) form exists.In addition, diesel exhaust also contains certain density oxygen, and this oxygen concentration is about 1.5-15% according to the operating point.

The harmful substance of discharging from the four-stroke engine of poor four-stroke engine such as direct injection mainly contains CO, HC, NO _XAnd SO ₂Compare with HC with CO, oxygen exists so that stoichiometry is excessive.

Hereinafter, Diesel engine and poor four-stroke engine are known as the poor burn engine ＂ of ＂.

Industrial waste gas and domestic fuel waste gas also may contain unburned hydrocarbon and carbon monoxide.

Term ＂ is rich, and oxygen containing waste gas ＂ comprises waste gas, wherein compares with HC with oxidable harmful substance such as CO, and oxygen exists so that stoichiometry is excessive.

Use oxidation catalyst and from described waste gas, remove harmful substance.Described catalyst has the function of coming removal of carbon monoxide and hydrocarbon by oxidation, wherein produces water and carbon dioxide in the ideal case.In addition, also carbon black be can remove, water and carbon dioxide wherein also formed by oxidation.

US 5,911, and 961 disclose a kind of oxidation catalyst by metal that has two catalytic active coatings or ceramic monolith preparation.As first component, at first fire-resistant (infusibility) oxide such as the TiO ₂Or ZrO ₂Last application Pt and/or Pd and at least a W, Sb, Mo, Ni, V, Mn, Fe, Bi, Co, Zn and alkali-metal oxide, wherein second component is by second refractory oxides such as Al ₂O ₃, SiO ₂, TiO ₂, ZrO ₂, SiO ₂-Al ₂O ₃, Al ₂O ₃-ZrO ₂, Al ₂O ₃-TiO ₂, SiO ₂-ZrO ₂, TiO ₂-ZrO ₂, zeolite forms.

EP 1 129 764 A1 disclose a kind of oxidation catalyst, and it contains at least a zeolite and additional a kind of support oxide such as aluminium oxide, silica, titanium oxide and alumina silicate and a kind of noble metal such as Pt, Pd, Rh, Ir, Au and Ag.

US 6,274, and 107 B1 disclose a kind of oxidation catalyst, and it contains cerium oxide and optional aluminium oxide and zeolite such as beta-zeolite.In addition, the zeolite platinum group metal of also can mixing.Described catalyst has promoted CO, HC and the oxidation of the hydrocarbon of condensation on carbon black pellet.

EP 0 432 534 B2 disclose a kind of continuous type oxidation catalyst that has high conversion performance for hydrocarbon and carbon monoxide in low temperature range.This catalyst is made up of vfanadium compound and platinum group metal, and it is applied on aluminium oxide in small, broken bits, titanium oxide, silica, zeolite and composition thereof.According to the table 2 and the table 3 of described document, for freshly prepd catalyst, 50%CO and HC conversion value (T ₅₀Value is also referred to as ignition (light-off) temperature) for being higher than 200 ℃ temperature.

EP 0 566 878 A1 disclose a kind ofly to have high conversion performance and nitrogen oxide and oxysulfide is had the oxidation catalyst that suppresses oxidation characteristic concerning hydrocarbon and carbon monoxide.Catalyst contains unitary body, is made up of dispersion coatings and catalytic active component as the promotion activity that is made by broken fine metallic oxide such as aluminium oxide, titanium oxide, silica, zeolite or its mixture of carrier.Use the platinum group metal and make active component, its can mix vanadium or barium oxide.According to the table 1 of described document, in the ignition test of carrying out with Diesel engine, for the CO oxidation, the initiation temperature (T of freshly prepd catalyst ₅₀) be 195-220 ℃, and concerning the HC oxidation, its value is for 210-222 ℃.

The claimed a kind of catalyst that is used for purification of diesel waste gas of WO 03/024589 A1 is characterized in that at least a noble metal deposits on atresia silica, for example the silicon tetrachloride by the flame pyrolysis form can obtain.Catalyst according to described method preparation has extraordinary tolerance performance to sulphur.

The catalyst that the application tin-oxide is made catalytic active component also is known.

US 6,132, and 694 disclose a kind of catalyst of voloxidation hydrocarbon, and described catalyst comprises noble metal such as Pt, Pd, Au, Ag and Rh and has the metal oxide of multiple stable oxidation states and tin-oxide at least.Can the mix oxide of a small amount of transition metal of described metal oxide.Do not mention other oxide.Prepare this catalyst by certain way, preferably to make which floor tin-oxide of unitary body load.On tin-oxide, use noble metal then.According to embodiment,, can give especially good results when noble metal is platinum and the oxide with multiple stable oxidation states when being tin-oxide.

US 4,117, and 082 discloses a kind of oxidation catalyst, and wherein tin-oxide is as the carrier of active component Pt, Pd, Rh, Ir and Ru.Also can use other support oxide, as Al ₂O ₃Or SiO ₂And magnesia.Prepare this catalyst in some way, thereby active component at first is deposited on the tin-oxide.In second step, resulting solid particle deposits on the support oxide from aqueous suspension then.Thereby obtain the catalyst be made up of the support oxide that is coated with tin-oxide, wherein said tin-oxide is applied by active component.

US 4,855, and 274, US 4,912,082 and US 4,991,181 disclose and be used for the catalyst that oxidizing carbon monoxide is a carbon dioxide.Described catalyst is made up of the silica gel that is coated with tin-oxide.Then, in second reactions steps, the platinum group metal to tin oxide layer application of water solution form is preferably platinum.Therefore obtain the catalyst be made up of the support oxide that is coated with tin-oxide, it is further by platinum or contain platinum compounds and apply.

As principle, technical catalyst for application contains platinum usually as active component.Hereinafter, will the merits and demerits of this catalyst be discussed briefly.

Except oxidation CO and HC, also promote to form NO by NO and oxygen ₂The repertoire that depends on oxidation catalyst, this can be that advantage also can be a shortcoming.

When relevant, under the effect of diesel oxidation catalyst, form NO with the carbon black filter ₂May wish that this is because NO ₂Help the degraded of carbon black, promptly it helps carbon black to be oxidized to carbon dioxide and water.This combination of diesel oxidation catalyst and carbon black pellet filter is also referred to as CRT-system (cyclic regeneration trap), and is for example disclosed in patent EP 835 684 and US 6,516,611.

When on waste line during without the carbon black filter, NO ₂Formation be undesirable, this is because the NO that discharged ₂Can produce strong bad smell.

Because the chemical property and the physical property of platinum, after being subjected to high thermal stress, the catalyst of platiniferous has sizable shortcoming.

The EGT of often being furnished with the effective Diesel engine of turbocharger is 100-350 ℃ of operation down in temperature range mainly, wherein provides the regulation of electric motor car operating point by NED circulation (new Europe drives circulation).When operating under sub-load, the temperature of waste gas is 120-250 ℃.When operating under full load, the temperature maximum can reach 650-700 ℃.On the one hand, need have than low light-off temperature (T ₅₀Value) oxidation catalyst on the other hand, in order to avoid huge loss of activity when full load is operated, needs high heat endurance.In addition, what it should be noted that is that unburned hydrocarbon can be accumulated on catalyst, and may ignition, thus the temperature that the local temperature of catalyst may be far above 700 ℃.Temperature peak may be up to 1000 ℃.Described temperature peak may cause oxidation catalyst to damage.Then, particularly in low temperature range, can not realize the obvious conversion of harmful substance by oxidation.

In addition, developed multiple different carbon black filter, be used for reducing the particulate emission in the diesel exhaust, for example described in patent application WO 02/26379 A1 and US 6,516,611 B1.When the carbon black of accumulating in the particulate filter burns, can give off carbon monoxide, it can be converted into carbon dioxide by the catalytically active coatings on the carbon black filter.Suitable coating compounds is also referred to as oxidation catalyst.In order to make carbon black be converted into harmless CO ₂And water, collected carbon black is burnt at regular intervals, wherein produce the required temperature of burning carbon black by the engine interior method.But the burning of carbon black is accompanied by emitting of big calorimetric, and it can cause the oxidation catalyst inactivation of the platiniferous used on filter.

Therefore, in order to compensate cause thermal damage, the waste gas for carrying diesel oil car is discharged mainly provides the oxidation catalyst of the platiniferous with a large amount of platinum.Described amount is generally 2.1-4.6g/l (60-130g/ft ³).For example, for 2 liters catalyst, use platinum up to 9g.For the waste gas of handling diesel locomotive, using a large amount platinum is the main expensive factor of expense.In catalyst, reduce part platinode tool economic attractiveness.

When introducing diesel particulate filter and combine, for oxidation catalyst, except low initiation temperature of needs and high heat endurance, other demand also clearly, this will provide hereinafter.

For example, oxidation catalyst can be installed in the upstream of engine particulate filter.Then, might increase the concentration of oxidation catalyst place hydrocarbon and use the heat that the hydrocarbon burning is emitted, thereby cause the burning of the carbon black on the diesel particulate filter that is installed in the downstream.As an alternative or additionally, diesel particulate filter itself can apply with oxidation catalyst.Therefore, the additional coatings of diesel particulate filter has the function that oxidizing carbon monoxide is a carbon dioxide, and wherein said carbon monoxide is to discharge in the combustion process of carbon black.When the high thermal stability of considering this coating simultaneously and high activity, in some applications, can cancel the additional oxidation catalyst that is installed in the upstream.Here two functions of the oxidation catalyst of discussing at diesel particulate filter need catalyst to have high heat endurance, and wherein said catalyst made from platonic may have shortcoming noted earlier.

Another problem of purifying waste gas from diesel engine relates to the existence of sulphur in the diesel fuel.Sulphur can be deposited on the support oxide, and might make the oxidation catalyst inactivation by the catalyst poisoning effect.The oxidation catalyst of platiniferous shows extraordinary anti-sulphur effect.In known catalyst formulation, confirmed that platinum is better than other platinum group metal such as rhodium, palladium or iridium.

For the waste gas of handling poor four-stroke engine such as direct injection four-stroke engine, use waste gas system, described waste gas system is made up of No. three catalytic converters, perhaps by oxidation catalyst and the storage NO that is installed in the downstream _xCatalyst form.Particularly, the oxidation catalyst in No. three catalytic converters has the function of the high relatively hydrocarbon discharge capacity of minimizing, and wherein said emission source moves under heterogeneous load condition particularly from the poor operator scheme of homogeneous phase.Therefore, under the cryogenic conditions of suitable catalyst, heat endurance and high as far as possible activity have optimum function, and wherein said catalyst mainly is used in the position near engine.

The objective of the invention is to develop a kind of new catalyst, be used for removing harmful substance from the waste gas of poor burn engine and off-air, it can have low temperature active oxidation CO and HC is CO ₂And water, to compare with the prior art catalyst, described catalyst has the anti-sulphur that improved heat endurance is become reconciled simultaneously.Except exploitation has the catalyst that improves operating characteristics, also should find a kind of method that reduced preparation cost with respect to former catalyst for application.

This purpose can realize by following catalyst: it contains tin-oxide, palladium and support oxide, and described support oxide preferably contains silicon and/or aluminium, and wherein said catalyst can be chosen wantonly and comprise other platinum group metal or promoter.

In first embodiment, catalyst contains tin-oxide, palladium and support oxide, it is characterized in that palladium and tin-oxide are present on the support oxide with the X ray picture amorphous form or with nanoscale form.

In second embodiment, catalyst contains tin-oxide, palladium and support oxide, it is characterized in that the support oxide nanoscale form exists.

Compare freshly prepd catalyst and the catalyst after aging shows suitable CO and HC oxidation efficiency with sulphur at low temperatures with the catalyst of prior art.But after at high temperature carrying out heat ageing, they obviously are better than described efficient.Therefore, the heat endurance of catalyst is very good, has good anti-sulphur simultaneously.

In addition, can prepare catalyst under the condition that does not have expensive noble metal platinum, correspondingly can reduce the amount of platinum in some way, thereby compare with the catalyst of prior art, the minimizing of material cost and the minimizing of preparation cost are all possible.

In fact and be not easy to utilize air oxygen oxidation NO to be NO when without platinum or when only using small amounts of platinum, catalyst of the present invention ₂, thereby can reduce bad smell.

When comparing with the catalyst of prior art, raw catelyst possesses skills and the advantage of economic two aspects.

The catalyst of first embodiment is different from the disclosed catalyst that contains tin-oxide in the prior art in the following areas:

A) tin-oxide and palladium directly are stored on the support oxide particle near form with landform together,

B) tin-oxide be present on the support oxide with X ray picture amorphous form or nanoscale form and

C) palladium exists with X ray picture amorphous form or nanoscale form,

D) tin-oxide and palladium are dispersed in the surface of support oxide very much.

Catalyst than prior art, these differences realize by following disclosed Preparation of catalysts method, it realizes by the high relatively tin-oxide of load on support oxide, or recently realizes by the weight of the component that comprises in the selecting catalyst.

Tin and palladium dispersed uniform can be as described below on the support oxide, and it preferably

(1) when considering individual particle, tin and palladium be dispersed on the support oxide particle with almost constant concentration respectively and

(2) when considering individual particle, the concentration ratio of tin and palladium is approximately constant on the concentration ratio of tin and support oxide and the support oxide particle surface.

Described dispersion comprises that also described catalyst contains at least two kinds of stanniferous and the mixture that contains the support oxide of palladium, and wherein every kind of support oxide has different tin and/or palladium concentration.In addition, described dispersion also comprises according to the gradient cladding process and prepares support oxide.When using gradient and apply,, wherein use honeycomb body and prepare described catalyst, just as discussed below along the gradient of length adjustment palladium, tin, promoter or the boron oxide of honeycomb ceramics.

Preferably, term ＂ gradient applies the gradient that ＂ relates to chemical composition.

As the inhomogeneity measuring method of test, in the application's context, use REM/EDX.

The tin-oxide that deposits on support oxide has X ray picture amorphous form or nanoscale form.

Say that briefly granularity can detect by the Scherrer equation based on the X-ray diffraction analysis:

Scherrer equation: D=(0,9* λ)/(B cos θ _B)

Wherein, ＂ D ＂ refers to the thickness of crystallite, and ＂ λ ＂ is the wavelength of applied X ray, and ＂ B ＂ is the full duration at half maximum place of corresponding reflection, θ _BBe its position.Fresh catalyst promptly has the tin-oxide granularity at 500 ℃ of catalyst of calcining down, and when pressing the measurement of Scherrer method, this particle size range is 1-100nm, and the granularity of tin-oxide may depend on applied support oxide.In some cases, even cannot see the reflection of tin-oxide, thereby the tin-oxide that exists can be known as the amorphous ＂ of ＂ X ray picture on described catalyst.When after wearing out under 700 ℃, do not detect or only detect very small amount of tin oxide granule agglomeration, and it depends on applied support oxide.This summary has represented that catalyst of the present invention has extraordinary durability.

Surprisingly, when support oxide has high capacity tin, also can keep the X ray picture amorphous form and the nanoscale form of tin-oxide.

Palladium also can exist with X ray picture amorphous form or nanoscale form.

In the context of the present invention, the meaning of term ＂ nanoscale ＂ is meant that the granularity that detects by the Scherrer equation is 0.5-100nm.The particle size range that particularly preferably is tin-oxide is 1-50nm.

The meaning of the amorphous ＂ of term ＂ X ray picture is meant and does not obtain the reflection of analyzable expression substance characteristics by the X ray wide angle deflection.

The term ＂ tin-oxide ＂ of Ying Yonging comprises the oxide and the suboxide of all possible tin hereinafter.

Term ＂ palladium ＂ comprises element palladium and possible oxide and suboxide.

＂ support oxide ＂ is preferably the oxide with heat endurance and large surface area.Term ＂ support oxide ＂ also comprises at least two kinds of different carriers hopcalites.

This oxide preferably has greater than 10m ²The BET surface area of/g.Particularly preferably be, the BET surface area of oxide is greater than 50m ²/ g, preferred BET surface area is 80-350m ²/ g.

Preferably, use through still having the support oxide of big BET surface area after the high-temperature process.More preferably support oxide is difficult for and sulfur oxide (SO _X) combination.

Support oxide preferably comprises silicon and/or aluminium.

Support oxide siliceous or that contain aluminium is a kind of support oxide, and it contains mixed oxide, alumina silicate, the kaolin of Si oxide, aluminium oxide, silicon/aluminium, kaolin or its mixture of modification particularly.

In addition, can use silica coking or that pass through the generation of silica deposit method.

Preferably, also can use coking aluminium oxide, Alpha-alumina, δ-aluminium oxide, θ-aluminium oxide and gama-alumina.

In addition, can use the aluminium oxide that is doped with silica, alkaline earth element oxide or rare earth oxide.

Mention as the front, basically mixture that also can the application of aforementioned support oxide.

The kaolin ＂ of term ＂ modification refers to following this kaolin: a part of Al that exists in its structure ₂O ₃Disperse by heat treatment and acid treatment subsequently.For raw material, the kaolin of Chu Liing has the bigger BET surface area and the aluminium of lower amount by this way.The kaolin of modification also can be known as alumina silicate, and can be commercially available.

Except oxide above-mentioned, described carrier can also contain the mixture of one or more zeolites.

For the diesel oxidation catalyst prescription, the mixture of zeolite can be by learning among the EP 0 800 856.Zeolite has following ability: adsorbed hydrocarbons under the low EGT and when meeting or exceeding the initiation temperature of catalyst the described hydrocarbon of desorb.

As disclosed among EP 1,129 764 A1, the function of zeolite can make the long chain hydrocarbon ＂ cracking ＂ that exists in waste gas, that is to say to make described hydrocarbon be decomposed into less fragment, and these fragments can be more easily by the noble metal oxidation then.

Zeolite as mixture can be used with following form: the Y-zeolite of H-ZSM-5, dealuminzation, Y-zeolite, modenite or the zeolite-β that hydrothermal treatment consists is crossed.Described zeolite can be used with pure form, perhaps uses as mixture, and wherein this application also comprises the zeolite of using doped forms, and the zeolite of described doped forms obtains by ion-exchange or other processing.

Concrete applicable also have Si/Al than 15 hydrothermally stable zeolite.In the context of the present invention, particularly, Y-zeolite, DAY-zeolite (the Y-zeolite of dealuminzation), ZSM-5, modenite and beta-zeolite all are applicable.

Therefore, zeolite can exist with sodium type, ammonium type or H type.In addition, also can be by making sodium, ammonium or H type be converted to another kind of ionic species with slaine or metal oxide impregnated or ion-exchange.Should be mentioned that as an example in the rare earth element aqueous chloride solution makes the Na-Y-zeolite be converted into SE-zeolite (SE=rare earth element) by ion-exchange.

Some examples of adaptable support oxide are following commercially available oxides for the present invention, but the present invention is not limited thereto:

Siralox 5/320 (Sasol company), Siralox 10/320 (Sasol company), Siralox 5/170 (Sasol company), Puralox SCFa 140 (Sasol company), Puralox SCFa 140L3 (Sasol company), F (Dorfner company), F50 (Dorfner company), F80 (Dorfner company), F+5/24 (Dorfner company), F-5/24 (Dorfner company), F-5/48 (Dorfner company), F+10/2 (Dorfner company), F+20/2 (Dorfner company), SIAL 35 (Dorfner company), alumina C (Degussa company), SA 3*77 (Norton company), SA 5262 (Norton company), SA 6176 (Norton company), aluminaHiQR10 (Alcoa company), alumina HiQR30 (Norton company), Korund (Alcoa company), MI307 (Grace Davison company), MI286 (GraceDavison company), MI386 (Grace Davison company), MI396 (Grace Davison company), MI486 (Grace Davison company), Sident 9 (Degussa company), Sipernat C 600 (Degussa company), Sipernat 160 (Degussa company), Ultrasil 360 (Degussa company), Ultrasil VN 2 GR (Degussa company), Ultrasil 7000 GR (Degussa company)

The hydrotalcite Pural MG70 (Sasol company) of 22 (Degussa companies), Aerosil 150 (Degussa company), Aerosil 300 (Degussa company), calcining, the hydrotalcite Pural MG50 (Sasol company) of calcining.

The example that can be used for zeolite of the present invention is following material, but the present invention is not limited thereto: Mordenit

(Tosoh company), Ferrierit

-700 (Tosoh companies),

-900 (Tosoh companies), USY

-300 (Tosoh companies), DAYWessalith HY25/5 (Degussa company), ZSM-5 SiO ₂/ Al ₂O ₃25-30 (GraceDavison company), ZSM-5 SiO ₂/ Al ₂O ₃50-55 (Grace Davison company), beta-zeolite HBEA-25 (S ü d-Chemie company), HBEA-150 (S ü d-Chemie company).

Catalyst prepares by the method that comprises following steps (i):

(i) compound of tin and palladium is contacted with support oxide.

The compound ＂ of term ＂ tin and palladium refers to suspend in liquid medium and/or the compound of complete or partly soluble at least all tin and palladium in described medium.

Preferably, be applied in the compound of complete or partly soluble at least tin and palladium in the described liquid medium.

Described liquid medium is preferably water.

Preferably, use tin and palladium salt.For example, described salt is the salt of inorganic acid, and as halide or nitrate, perhaps organic acid salt is as formates, acetate, caproate, tartrate or oxalates.The complex chemical compound of using tin and palladium also is possible.For example, can be with the form using palladium of soluble ammonium salt composite.

Preferably, be applied in the tin oxalate that dissolves in the water and make tin compound, can further improve its solubility by adding nitric acid.

If the application of palladium and tin compound is carried out simultaneously, then preferred palladium is used with its nitrate form.

In addition, the compound of applied tin and palladium can carry out chemical treatment.For example, as above described at tin oxalate, can use the described compound of acid treatment.It also is possible adding complexing agent.By described processing, described compound can be converted to the state with very good solubility, and this processing for next step plan is favourable.

For Preparation of Catalyst, preferably method is wherein used the not chloride tin and the compound of palladium as far as possible, and this is because the latter discharges chlorine-containing compound and can cause badly damaged to exhaust gas apparatus from catalyst.

＂ makes it to contact ＂ and is meant with the compound of tin and palladium with suspended state or preferably with dissolved form simultaneously or be administered to successively on the general support oxide.

For Preparation of Catalyst, all embodiments all are preferred, and these schemes have proved to have value usually in catalyst research, particularly ＂ wash coat ＂ and/or ＂ honeycomb ＂ and ＂ powder or pellet ＂ technology.Embodiment (α), (β), (γ), (δ) exemplarily discuss below.

(α) might carry out in some way, the major part that makes support oxide is ground in aqueous suspension has only several microns particle for granularity, it is applied on pottery or the metal forming body then.For this purpose, formed body is soaked in the support oxide suspension, thereby makes its load carriers oxide, promptly impregnated.Through as after dry or the calcining heat treatment, obtain the formed body that applies with support oxide.Formed body through applying is immersed in the solution of tin and palladium compound, thereby makes support oxide by load or coating.Carry out drying then and preferably calcine.Can repeat this process up to reaching desirable load capacity.

(β) still, also can in support oxide suspension, add the tin and the palladium compound of dissolving, formed body is soaked into carry out load in the suspension, promptly flood, carry out drying and calcining again.Often can repeat this process up to reaching desirable load capacity.

(γ) in addition, might be at first with the tin and the palladium compound impregnated carrier oxide that dissolve, the dipping solution volume of correspondence when wherein the cumulative volume of applied each dipping solution is lower than support oxide maximum liquid adsorption ability.By this way, can obtain seeming the support oxide of dry dipping, it carries out drying and calcining in step subsequently.The constituent that obtains by this way can provide in water, and can be ground.Subsequently, can on formed body, use wash coat.

(δ) also can in support oxide suspension, add tin and the palladium compound that dissolves, subsequent filtration solid, drying, calcining.As a kind of alternative, the suspension that contains tin and palladium compound can spray-drying and calcining.Can obtain the catalyst of powder type so again.Described material also can be used for coated molded body, and the step of choosing wantonly in aqueous suspension that grinds is carried out afterwards.

Basically tin and palladium compound need do not used in common treatment step promptly simultaneously on the support oxide.Therefore, can at first handle tin compound by said process, and palladium compound is used by the dip mold body at first, described formed body applies with wash coat in the solution of suitable palladium compound.

Can use all known methods and come the load carriers oxide, promptly contact and pass through the drying and the calcining step of catalyst with palladium compound with support oxide by the tin that makes dissolving.Described method depends on selected Method type, particularly, whether at first uses ＂ wash coat ＂ on formed body, or does not select powder method.Described method comprises following method: ＂ initial wetting ＂, ＂ soak dipping ＂, ＂ spraying dipping ＂, ＂ spray-drying ＂, ＂ spraying calcining ＂ and ＂ rotation calcining ＂.Also can be by known method as by extruding or extrusion molding carries out the refining of catalyst.

Therefore, catalyst of the present invention preferably provides with the honeycomb ceramics form of powder, particle, extrudate, formed body or coating.

Except above method of on support oxide, evenly disperseing catalytic active substance, also can use with metal salt solution impregnated carrier oxide, with metal salt solution impregnated carrier material, from liquid absorption slaine and spray solution and by solution precipitation or solution deposition etc.

Also can from solution, use tin and palladium compound.

With behind tin and the palladium compound load carriers oxide, implement subsequently drying steps and common calcining step.When spraying calcining, described in EP 0 957 064 B1, in fact dry and calcining can be implemented in a process steps.

Therefore, described method also comprises step (ii):

(ii) calcining.

Calcining step preferably is 200-1000 ℃ in temperature to be implemented down, and more preferably 300-900 ℃, particularly 400-800 ℃.

By calcining step, pink salt decomposes by Temperature Treatment, and is converted into tin-oxide at least in part.

Palladium salt also can be converted into its oxide by Temperature Treatment.The forming element palladium also is possible.

By calcining step, also increased the mechanical stability of catalyst.

In Preparation of Catalyst or its processing procedure, except top needed catalytic component, can in carrier material, add auxiliary material and/or additive, for example oxide and mixed oxide, its as additive, adhesive, filler, hydrocarbon adsorbent or other sorbing material, be used for increasing the mixture of durothermic adulterant and at least two kinds of above-mentioned substances.

Before or after coating procedure, in wash coat, add described other component of water-soluble and/or water-insoluble form.After using all catalytic components on the formed body, make the dry and calcining of formed body usually.

The component that can mix on catalyst comprises other platinum family material, i.e. platinum, rhodium, iridium and ruthenium.Here term ＂ platinum, rhodium, iridium and ruthenium ＂ comprise element and oxide.

Therefore, catalyst is characterised in that and mixes it one or more are selected from the metal of platinum, rhodium, iridium or ruthenium.

Therefore, the method for preparing catalyst also comprises step (iii):

(iii) be selected from the compound doped described catalyst of platinum, rhodium, iridium or ruthenium with one or more.

Step compound (iii) can add in step (i).But, also can after support oxide or formed body are coated, add them again, preferably by preceding method (α), (β), (γ) and (δ) carry out described coating.

The water soluble salt of described compound is preferably used with the form of its nitrate.For ruthenium, ruthenium-nitrosyl radical-trinitrate is proved to be of great value.Preferably flood and use by above-mentioned immersion.After using all catalytic components, implement drying steps and calcining step subsequently.

Through behind the calcining step, described metal is present in the catalyst with the form of element or oxide.

By oxide or its mixture of doped indium, gallium, alkali metal, alkaline-earth metal, rare earth element, can realize the further increase of catalyst activity.This compound is also referred to as promoter.

Promoter is dispersed on the catalyst surface in a certain way, thereby it evenly disperses with tin-oxide and palladium.

Term ＂ indium oxide ＂, ＂ gallium oxide ＂, ＂ alkali metal oxide ＂, ＂ alkaline earth oxide ＂ and ＂ rare earth oxide ＂ comprise all possible oxide and suboxide and all possible hydroxide and carbonate.

Therefore term ＂ alkali metal oxide ＂ comprises all oxides, suboxide, hydroxide and the carbonate of element Li, Na, K, Rb and Cs.

Term ＂ alkaline-earth metal metal oxide ＂ comprises all oxides, suboxide, hydroxide and the carbonate of element M g, Ca, Sr and Ba.

Term ＂ rare earth oxide ＂ comprises all oxides, suboxide, hydroxide and the carbonate of element La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc.

If catalyst of the present invention prepares by adding promoter, then tin-oxide and promoter can exist with mixed oxide, perhaps can exist with the oxide with the burnt chlorine ＂ of ＂ structure according to circumstances.The burnt chlorine ＂ of ＂ oxide can be with general empirical formula A ₂B ₂O ₇Describe.Along with the variation that is used to prepare the stanniferous of catalyst and contains the amount of promoter component, depend on the granularity of formed burnt oxychloride, except the amorphous tin-oxide phase of above-mentioned X ray picture, described oxide can also exist mutually with the stanniferous crystal.

For the anti-sulphur of catalyst, it also is favourable adding boron oxide compound.

Term ＂ boron oxide compound ＂ comprises all oxides, suboxide and the hydroxide of element boron.

Preferably, on support oxide, flood boron oxide compound, preferably use the aqueous solution of boric acid, use separately or with the compound that at least a compound above-mentioned is tin, platinum or promoter.Thereby boron oxide compound is dispersed on the catalyst surface.

In addition, the feature of catalyst is that also it can comprise the promoter that is selected from indium oxide, gallium oxide, alkali metal oxide, alkaline earth oxide and rare earth oxide.

Therefore, the method for preparing catalyst also comprises step (iv):

(iv) use the promoter doped catalyst

If use gallium oxide, indium oxide, alkali metal oxide, alkaline earth oxide and rare earth oxide, the also preferred form down to the water-soluble compound of small part of these compounds is used.

Promoter is preferably used with the form of its nitrate.For example nitrate of rare earth element can obtain with commercial scale in nitric acid by making its dissolves carbonate.If when using promoter simultaneously with the compound of tin that contains nitrate and palladium on support oxide, it is particularly advantageous using nitrate.

A kind of method for preparing catalyst of advantageous applications wherein makes the raw material of promoter contact with support oxide by water-bearing media.

In step (i), can add compound.But, also can support oxide or formed body preferably by above-mentioned (α), (β), (γ) and (δ) one of method add them again after applying.

Also can be with adding the compound that the platinum group metal is platinum, rhodium, iridium and ruthenium or after it adds, adding them again.

After using promoter, implement drying and/or calcining step according to circumstances subsequently successively.

The chemical composition of catalyst of the present invention will be described below.The weight ratio that % represents is respectively based on the element wt of tin, palladium or other platinum group and promoter.For support oxide and zeolite, weight ratio is a benchmark with oxide separately.

Total amount with applied support oxide is a benchmark, and catalyst contains the tin-oxide that total amount is 3-50wt% (in tin), and wherein total amount is that the tin-oxide of 5-40wt% is preferred.

For the total amount of applied all support oxide, the total amount of palladium, platinum, rhodium, iridium and ruthenium is preferably 0.2-10wt%.Preferred total amount is 0.5-5wt%.

Following weight ratio is respectively based on the element wt of each element.

Weight ratio between the gross weight of tin-oxide (in tin) and palladium, platinum, rhodium, iridium and ruthenium is preferably 2:1 to 25:1, and wherein preferred weight ratio is 4:1 to 20:1.Preferred weight ratio scope is 6:1 to 15:1.

If also use platinum except that palladium, then the weight ratio between palladium and platinum is preferably 0.3:1 to 1000:1.1:1 to 50:1 more preferably.

If use rhodium, ruthenium, iridium or its mixture replacing platinum, then the weight ratio of palladium and rhodium, ruthenium, iridium or its mixture is preferably 2.5:1 to 1000:1.5:1 to 20:1 more preferably.

If also use platinum and at least a other platinum group metal except that palladium, then the weight ratio between the total amount of palladium and platinum and at least a other metal is preferably 0.3:1 to 1000:1.1:1 to 50:1 more preferably.

If use promoter, then the weight ratio between the total amount of tin-oxide (in tin) and all promoter (in element) is 0.66:1 to 33:1.0.8:1 to 10:1 more preferably.Further preferred weight ratio scope is 1:1 to 6:1.

If the application boron oxide compound, then the weight ratio between all support oxide of Ying Yonging and boron oxide compound (in boron) is 1:0.00005 to 1:0.2.1:0.0001 to 1:0.1 more preferably.1:0.00002 to 1:0.075 more preferably.

If the application zeolite, then the total amount with applied all support oxide is a benchmark, and the total amount of zeolite is preferably 5-50wt%.The total amount of zeolite is 8-40wt% more preferably.Be preferably 10-25wt% especially.

In another embodiment, also can realize purpose of the present invention by using a kind of catalyst, wherein said catalyst contains the nano carrier oxide, and uses tin-oxide and palladium on described carrier.

Here, term ＂ tin-oxide ＂ and ＂ palladium ＂ have equivalent as defined above.

Term ＂ support oxide ＂ preferably includes thermally-stabilised and has the oxide on big surface.Term ＂ support oxide ＂ also comprises the mixture of at least two kinds of different support oxide.Also comprise corresponding hydroxide or hydrous oxide, for example as the aluminum oxide hydroxide of boehmite.

For support oxide, the meaning of term ＂ nanoscale ＂ is meant that its granularity is 0.5-250nm.The particularly preferred particle size range of nano carrier oxide is 5-180nm.

Granularity can disperse to determine by light according to known method.Here, particle exists with size distribution.Granularity is mainly with d ₅₀Value characterizes, and it is defined as 50% the particle diameter shown in having.

Than the support oxide of routine, the nano carrier oxide has big relatively external surface area, and its granularity is in the micron order scope.Described outer surface can be estimated by following equation:

External surface area=4* π * (d _Particle/ 2) ²

Wherein, ＂ d ＂ is the diameter of particle.Also can determine the surface area of nano carrier oxide of the present invention by known BET method.Say that briefly the BET surface area of particle preferably surpasses 10m ²/ g.More preferably the BET surface area of nano carrier oxide surpasses 50m ²/ g.Particularly, surface area is 70-400m ²/ g.The surface area of determining by the BET method provides the value that departs from the external surface area value of being calculated usually.

Preferably, application also has the nano carrier oxide of BET surface area greatly after being exposed to high temperature.

The nano carrier oxide preferably contains silicon or aluminium or silicon and aluminium.

Particularly preferably be the nano carrier oxide and contain aluminium.

The support oxide that contains aluminium is for specifically containing the support oxide of aluminium oxide, silicon/aluminium-mixed oxide, alumina silicate or its mixture.

Except that this this, can also use the nano carrier oxide that is doped with Si oxide, alkali metal oxide or rare earth oxide.

The method for preparing the nano carrier oxide is known.For example, this method comprises the hydrolysis and the sol-gal process of controlled deposition process, fatty alcohol.Other method of preparation nano-scale oxide is included in revolving burner or the pulsation reactor carries out flame treatment by vapour deposition and by pyrolytic proper raw material such as silicon tetrachloride.In addition, conventional support oxide can transform by chemical treatment, and wherein said chemical treatment is known method, for example is converted into oxide with nitric acid treatment, and the oxide after the processing contains nano particle and can be used as support oxide.

In addition, the nano carrier oxide can be commercially available.For example, can take from the product data sheet of manufacturer or relevant patent application or patent EP 1,359 123 A2, EP 0 931 017 B1 and WO 00/76643 A1 about the information of its characteristic.

The example of the adaptable nano carrier oxide of the present invention comprises following commercially available oxide, but the present invention is not limited thereto:

Disperal (Sasol company), Disperal S (Sasol company), Disperal HP14 (Sasol company), Disperal 40 (Sasol company), Disperal AL 25 (Sasol company), Dispal 11N7-12 (Sasol company), Dispal 14N4-25 (Sasol company), Dispal 18N4-20 (Sasol company), Dispal 23N4-20 (Sasol company), DisperalP2 (Sasol company), Disperal HP 14/2 (Sasol company), Dispal11N7-80 (Sasol company), Dispal 14N4-80 (Sasol company), Dispal18N4-80 (Sasol company), Dispal 23N4-80 (Sasol company).

Some characteristic of nano carrier oxide above-mentioned is exemplarily following listed, and described information is corresponding to the information of manufacturer.Here, d ₅₀Value refers to that 50% particle has the diameter of being mentioned.

Support oxide	Granularity (d ₅₀)[nm]	BET surface (m ²/g)
Support oxide	Granularity (d ₅₀)[nm]	BET surface (m ²/g)	Disperal?SDisperal?40Disperal?AL?25Disperal?P2	100 ^140 ^200 ^25 ^	180 ^100 ^100 ^260 ^

^*At water or rare HNO ₃The aqueous solution in disperse

^*Drying and calcining are after 3 hours under 550 ℃

According to the information of manufacturer, conventional support oxide such as PuraloxSCFa (90-210) (Sasol company) or Puralox (NGa) (80-160) (Sasol company) have the granularity (d of about 20 or 35 μ m ₅₀), and its BET surface area is about 90-210m ²/ g or 80-160m ²/ g.

Also can applying nano grade carrier hopcalite.

For example, the nano carrier oxide that contains aluminium very preferably can be with other nano carrier oxide such as siliceous, titaniferous, contain cerium, the support oxide that contains zirconium or iron content mixes.The example of the nano carrier oxide of this siliceous or titaniferous has:

Ludox AS40 (Dupont company), Ludox CL (Dupont company), LudoxTMA (Dupont company), Hombicat XXS 100 (Sacht leben company), Aerosil150 (Degussa company).

Also can make the nano carrier oxide, particularly very preferably the nano carrier oxide that contains aluminium with conventional be that non-nano grade carrier oxide mixes, the non-nano grade carrier oxide of described routine for example siliceous, titaniferous, contains cerium, contains the support oxide of zirconium or iron content as described below.The support oxide of this routine has micron order granularity as mentioned above, and its example comprises the following oxide that is available commercially:

Siralox 10/320 (Sasol company), Siralox 5/170 (Sasol company), Puralox SCFa 140 (Sasol company), F50 (Dorfner company), F80 (Dorfner company), F+5/24 (Dorfner company), F+5/48 (Dorfner company), F-5/24 (Dorfner company), F+10/2 (Dorfner company), F+20/2 (Dorfner company), SIAL 35 (Dorfner company) SIAL 25-H (Dorfner company), SA3*77 (Norton company), SA 5262 (Norton company), SA 6176 (Norton company), Alumina HiQR10 (Aloca company), Alumina HiQR30 (Aloca company), Korund (Aloca company), MI307 (Grace Davison company), MI407 (GraceDavison company), MI286 (Grace Davison company), MI386 (Grace Davison company), MI396 (Grace Davison company), MI486 (Grace Davison company), Hydrotalzit Pural MG70 (Sasol company) after the calcining, Hydrotalzit Pural MG50 (Sasol company) after the calcining, Sident 9 (Degussa company), Sipernat C 600 (Degussa company), Sipernat 160 (Degussa company), Ultrasil 360 (Degussa company); Ultrasil VN 2 GR (Degussa company), Ultrasil 7000 GR (Degussa company), 22 (Degussa companies), P 25 (Degussa company), XT 25384 (Norton company), XT 25376 (Norton company), Cer (IV) Oxid (Merck company), XZ 16052 (Norton company), XZ16075 (Norton company).

Except the oxide of being mentioned, the nano carrier oxide can also comprise the mixture of one or more zeolites.Can use the disclosed zeolite in front.

The example of the zeolite that can use in the present invention is as follows, but the present invention is not limited thereto:

Mordenit

(Tosoh company), Ferrierit HSZ@-700 (Tosoh company), HSZ@-900 (Tosoh company), USY HSZ@-300 (Tosoh company), DAYWessalith HY25/5 (Degussa company), ZSM-5 SiO ₂/ Al ₂O ₃25-30 (GraceDavison company), ZSM-5 SiO ₂/ Al ₂O ₃50-55 (Grace Davison company), beta-zeolite HBEA-25 (S ü d-Chemie company), HBEA-150 (S ü d-Chemie company), P 814C (Zeolyst company), CP 814E (Zeolyst company), ZeocatFM-8/25H (Zeochem company), Zeocat PB/H (ZeoChem company).

If only use a kind of support oxide, and it has only part to exist with nano particle, then preferably at least the carrier material of 3wt% exist with the form of nano particle.More preferably the carrier material of 10wt% exists with the form of nano particle at least.

If the support oxide of nano carrier oxide and other non-nano particle form and/or combination of zeolites are used, then further preferably at least 3wt%, more preferably whole carrier materials of 10wt% exist with the form of nano particle at least.

The catalyst of the present embodiment prepares according to certain method, and described method relates to above-mentioned method, thereby support oxide is a nanoscale.

Further processing step comprise above-mentioned calcining step (ii) with the doping step (iii) and (iv).

Use respective compound and the reaction condition mentioned.

Therefore, can use one or more elements that are selected from platinum, rhodium, iridium or ruthenium and make adulterant.

It also is possible mixing with one or more promoter that are selected from indium oxide, gallium oxide, ferriferous oxide, alkali metal oxide, alkaline earth oxide and rare earth oxide.

Should be mentioned that be the embodiment (α) mentioned in front, (β), (γ) and (δ) in, can substitute nano carrier oxide applications nano carrier hopcalite.What in addition, also can make one or more routines is that non-nano grade carrier oxide mixes with nano carrier oxide or nano carrier oxide mixture.For this situation, be adhered to well on the formed body in order to ensure support oxide in principle, before being coated on the formed body, make support oxide suspension stand to grind processing.In addition, in all embodiments, can add the nano carrier oxide suspension of one or more zeolite types.

By calcining step, the nano carrier oxide may partial coalescence be bigger particle.Say that briefly this does not influence the efficient of catalyst or only influences described efficient in edge.The polymolecularity that should keep in a word, tin-oxide, palladium and optional promoter of adding as much as possible.

If use promoter, then described promoter is dispersed in catalyst surface in a certain way, thereby it evenly disperses with tin-oxide and palladium.When using zeolite in the wash coat that can carry out ion-exchange, then described promoter can be accumulated in described zeolite.

Except adding boron oxide compound, for the anti-sulphur of catalyst, adding phosphorous oxides may also be favourable.

Term ＂ phosphorous oxides ＂ comprises all oxides, suboxide and the hydroxide of element phosphor.

Phosphorous oxides preferably is impregnated into from phosphate aqueous solution on the support oxide, and its compound independent or that be tin, platinum or promoter with at least a above-mentioned compound floods.Thereby phosphorous oxides is dispersed on the catalyst surface.

For Preparation of Catalyst, do not get rid of and add boron oxide compound and phosphorous oxides simultaneously.

The chemical composition of catalyst of the present invention will be disclosed below.Wt% is a benchmark with the element wt of tin, palladium or other platinum group and promoter respectively.For support oxide and zeolite, weight ratio is a benchmark with corresponding oxide.

Total amount with applied all support oxide is a benchmark, and catalyst contains the nano carrier oxide that total amount is 3-100wt%, and wherein total amount is that 10-100wt% is preferred.

Total amount with applied all support oxide is a benchmark, and catalyst contains the tin-oxide that total amount is 3-50wt% (in tin), and wherein total amount is that the tin-oxide of 5-40wt% is preferred.

Total amount with applied all support oxide is a benchmark, and the total amount of palladium, platinum, rhodium, iridium and ruthenium is preferably 0.2-10wt%.Preferred total amount is 0.4-5wt%.

At this specification hereinafter, weight ratio is a benchmark with the element wt of respective element respectively.

Weight ratio between the gross weight of tin-oxide (in tin) and palladium, platinum, rhodium, iridium and ruthenium is preferably 2:1 to 50:1, wherein wt than for 4:1 to 45:1 more preferably.Further preferred weight ratio scope is 5:1 to 40:1.

If use promoter, then the weight ratio between the total amount of tin-oxide (in tin) and all promoter (in element) is 2:1 to 50:1.4:1 to 45:1 more preferably.Further preferred weight ratio scope is 7:1 to 35:1.

If the application phosphorous oxides, then the weight ratio between all support oxide of Ying Yonging and phosphorous oxides (in P) is 1:0.00005 to 1:0.2.1:0.0001 to 1:0.1 more preferably.1:0.00002 to 1:0.075 more preferably.

If the application zeolite, then the total amount with applied all support oxide is a benchmark, and the total amount of zeolite is preferably 5-70wt%.The total amount of zeolite is 8-60wt% more preferably.Be preferably 10-50wt% especially.

Tin-oxide and palladium preferably are evenly dispersed on the nano carrier oxide surface very much.

The distributing homogeneity of tin and palladium can be described as being preferably as follows on support oxide:

(3) when considering individual particle, tin and palladium on the support oxide particle respectively with distribute near constant concentration and

(4) when considering individual particle, on the surface of support oxide particle, the concentration ratio of the concentration ratio of tin and support oxide and tin and palladium is near constant.

Described dispersion also comprises: catalyst contains at least two kinds of mixtures that have the stanniferous of different tin and/or palladium concentration respectively and contain the support oxide of palladium.In addition, described distribution also comprises according to the gradient painting method and prepares support oxide.In the gradient coating procedure, discussed as top, continue to use in the length of the honeycomb ceramics of preparation catalyst, the gradient of regulating palladium, tin, promoter or boron oxide compound.

Term ＂ gradient coating ＂ preferably relates to the gradient in chemical composition.

As the inhomogeneity measuring method of checking, can use known REM/EDX method (electron microscope scanning/energy disperses the micro-analysis of X-ray).

In addition, applying nano grade carrier oxide can make tin-oxide, palladium and optional promoter be present on the support oxide mutually with high degree of dispersion in Preparation of Catalyst.For the purpose of planning, verified this is very favorable.Not bound by theory, suppose along with the dispersed mutually increase of catalyst activity, i.e. the dispersiveness of tin-oxide and palladium, the atomicity that can contact with reaction gas also will increase, thereby cause the catalytic activity increase of catalyst.

As the measuring method of the dispersiveness of tin-oxide on the checking nano carrier oxide, palladium and optional promoter, can consider transmission electron microscope (TEM) method, and in conjunction with the EDX method.

The tin-oxide that deposits on the nano carrier oxide preferably has X ray picture amorphous form or nanoscale form.

Palladium also preferably exists with X ray picture amorphous form or nanoscale form.

Fresh catalyst is the catalyst of calcining down at 500 ℃, and when measuring by the Scherrer method, it has the tin oxide granule that granularity is preferably about 1-100nm, thereby the granularity of tin-oxide may depend on applied support oxide.In some cases, even detect reflection, thereby the tin-oxide that exists can be known as the amorphous ＂ of ＂ X ray picture on described catalyst less than tin-oxide.Depend on applied support oxide,, do not detect or only detect very small amount of tin oxide granule agglomeration when after wearing out under 700 ℃.This summary has represented that catalyst of the present invention has extraordinary durability.

For tin-oxide, term ＂ nanoscale ＂ refers to preferably be lower than 100nm by the granularity that the Scherrer equation is determined.0.5-100nm be preferred.More preferably granularity is lower than 50nm.The particle size range that particularly preferably is tin-oxide is 1-50nm.

Equally, the palladium particle can exist with aforementioned particle size range.

The amorphous ＂ of term ＂ X ray picture refers to not reflect generation, and described reflective representation is offset the characteristic of the material that obtains by X ray.

The amorphous ＂ of term ＂ X ray picture refers to that also the granularity of tin-oxide and/or palladium can be in atoms range.

Surprisingly, for support oxide, keep the X ray picture amorphous form or the nanoscale form of tin-oxide with high capacity tin.

Catalyst of the present invention is different from the catalyst that contains tin-oxide of prior art aspect following:

E) support oxide is used with nanoscale form,

F) on the support oxide particle, tin-oxide and palladium exist together in the approaching mode of direct landform,

G) in the Preparation of catalysts process, tin-oxide contacts with support oxide with form dissolving or partly soluble at least precursor.

Compare with the catalyst of prior art, other main difference realizes by following aspect: support oxide has the tin-oxide of higher relatively tin-oxide load, the weight ratio that is chosen in each component that comprises in the catalyst, nanoscale or X ray picture amorphous character and the disclosed Preparation of catalysts method of high dispersion and front of palladium etc.

Catalyst of the present invention preferably has certain structure, wherein has the macropore that has conduit, itself and mesopore and/or micropore coexistence.

The invention still further relates to the purposes of described catalyst, be used for removing harmful substance from the waste gas and the off-air of poor burn engine.

In addition, the invention still further relates to a kind of method that the open catalyst in front purifies the waste gas and the off-air of poor burn engine, particularly Diesel engine of using.

Described exhaust gas purifying method is preferably implemented in some way, makes the purification of described waste gas comprise the simultaneous oxidation of hydrocarbon and carbon monoxide, and passes through the oxidation removal carbon black.

Also can be and move described catalyst in conjunction with at least a other catalyst or carbon black pellet filter.For example, here the carbon black pellet filter can be used catalyst-coated, and preferred described catalyst is as the face coat of carbon black pellet filter.It is contemplated that the combination of catalyst of the present invention and other catalyst: (α α) by order arrange different catalyst, (β β) by different catalysts physical mixture and be administered on the public formed body or (γ γ) by on public formed body, using the different catalysts of stratiform form, and above-mentioned combination arbitrarily.

The carbon black pellet filter itself preferably applies with oxidation catalyst.

Hereinafter, described as exemplary Preparation of catalysts, with and characteristic compared with prior art the time.Utilize the fact of specific embodiment by concrete numeric representation to be construed as restriction in no instance in the literary composition, and described restriction will provide in specification and claims to specification.

The embodiment of catalyst embodiments, wherein tin-oxide and palladium exist with X ray picture amorphous form or nanoscale form:

Provided in the accompanying drawings:

Fig. 1: the C0 conversion ratio of catalyst and the relation between reaction temperature, wherein said catalyst are to be in fresh attitude and at the catalyst sample of the embodiment 5 (B5) of 700 ℃ of following heat ageings after 16 hours, it consists of Pd _1.4Pt _0.6Sn ₅/ Siralox.In Fig. 1, transverse axis is for ℃ being the temperature of unit representation, and the longitudinal axis is for being the C0 conversion ratio of unit representation with %.

Fig. 2: the diffraction analysis of following sample: (a) VB2, (b) the support oxide Siralox 5/170 of not load, (c) fresh B31 and (d) aging B31.In Fig. 2, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the X ray intensity of unit representation wantonly.

Fig. 3: the diffraction analysis of following sample: (a) VB2, (b) the support oxide Siralox 5/320 of not load, (c) fresh B24 and (d) aging B24.In Fig. 3, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the X-radiation intensity of unit representation wantonly.

Fig. 4: through the diffraction analysis of the catalyst of the Embodiment B 31 after the following different pre-treatment step: (a) fresh sample, the sample after (b) aging and (c) through the fresh sample after the catalysis test.Wherein Siralox 5/170 is used as support oxide.In Fig. 4, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the X-radiation intensity of unit representation wantonly.

Fig. 5: through the diffraction analysis of the catalyst of the Embodiment B 37 after the following different pre-treatment step: (a) fresh sample, the sample after (b) aging and (c) through the fresh sample after the catalysis test.Wherein Puralox SCFa 140 is used as support oxide.In Fig. 5, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the X-radiation intensity of unit representation wantonly.

Fig. 6: the accumulation HC discharging of the catalyst of Embodiment B 153, it obtains by new Europe superscript locomotive circulation at the Engine Block Test station.Transverse axis is for being the time of unit representation with the second, and the longitudinal axis is the HC discharging of speed or accumulation.Wherein A has described engine load over time, and B is the HC discharging of accumulating when not having catalyst, the HC discharging that C accumulates when using reference catalyst, the HC discharging that D accumulates when using catalyst of the present invention.

Fig. 7: the CO discharging of the accumulation of the catalyst of Embodiment B 153, it obtains by new Europe superscript locomotive circulation at the Engine Block Test station.Transverse axis is for being the time of unit representation with the second, and the longitudinal axis is the corresponding speed of the CO discharging of accumulation.Wherein A has described engine load over time, and E is the CO discharging of accumulating when not having catalyst, the CO discharging that F accumulates when using reference catalyst, the CO discharging that G accumulates when using catalyst of the present invention.

The catalysis test

Fully automatically implementing activity measurement in the catalyst facility, wherein said facility is with the fixed bed reactors (internal diameter of each reative cell is 7 mm) of being made by stainless steel of 16 parallel runnings. Catalyst is being similar under the condition of diesel exhaust, utilizes excess of oxygen to test with continuous operation mode under the following conditions:

Temperature range: 120-400 ℃

Waste gas forms: CO:1000ppmv, propylene: 100ppmv, NO:300

ppmv，O ₂：10％，H ₂O：6％，N ₂: surplus

Gas flow: 45 l/h unit's catalyst

Catalyst quality: 0.125g

Most of catalyst are measured by material of main part, and it is comprised of support oxide, tin-oxide, palladium and optional promoter and other platinum group metal, and this is because great majority do not need to use wash coat on formed body. As principle, be that activity is partly measured in the screening of 315-700 μ m with granularity.

As reference catalyst (VB), application has 3.1g/l (90g/ft³) the cellular oxidation catalyst that is purchased that is used for diesel engine exhaust of platinum. The described catalyst of 0.52g is ground, and measure as material of main part. Compare with the quality of catalyst of the present invention, the quality of the reference catalyst of be used for measuring is obviously higher, and reason is reference catalyst by the honeycomb substrate ＂ dilution ＂ that draws up. Therefore, under the benchmark of almost identical noble metal quality, carry out comparing and measuring between catalyst of the present invention and reference catalyst.

FT-IR equipment with Nicolet company is implemented CO, CO₂, propylene and H₂The mensuration of O. O₂λ-sensor by Etas company is measured, and NO, NO₂And NO_XChemiluminescence equipment with Ecophysics company is measured.

For evaluate catalysts, use T₅₀Value (temperature when reaching 50% conversion ratio) is as the standard of the oxidation activity of CO and propylene oxidation.

For being in fresh attitude with for the catalyst after different ageing processes (heat ageing,, hydrothermal aging aging with the sulphur) processing, its T₅₀Value is summed up in table 3-8.

Aging with sulphur

Term ＂ has described after being subjected to oxysulfide (SOX) impact with the aging ＂ (also claiming sulphur tolerance or anti-sulphur) of sulphur, and the CO and the HC that comprise in the oxidation catalyst oxidizes waste gas become CO₂And H₂The ability of O.

In the reactor of 16 parallel operations, carry out under the following conditions with sulphur is aging:

Temperature: 350 ℃

Duration: 16 hours

Gas composition: SO₂：100ppmv，H ₂O:5%, synthesis of air: surplus

Gas flow: 10 l/h unit's catalyst

Catalyst quality: 0.125g

Aging after 16 hours, stop SO₂Charging, and under synthesis of air, catalyst is cooled down.

Heat ageing

Under air conditions, in Muffle furnace, under 700 ℃ temperature, implement the heat ageing of catalyst. Thereby catalyst kept 16 hours under this temperature, then was cooled to room temperature. In addition, selected catalyst is also aging under 850 ℃ and 1000 ℃ in air.

Hydrothermal aging

In the air stream that contains 10% water, in Muffle furnace, under 750 ℃ temperature, implement hydrothermal aging. Thereby catalyst kept 16 hours under described temperature, then was cooled to room temperature.

Embodiment

Embodiment 1 (B1)

In order to prepare catalytic active substance, the silica-alumina of suspension Sasol company (Siralox 5/320) in water, and in ball milling, it is ground.After the drying, provide material that 0.4g grinds as support oxide.

Make 225 μ l by tin oxalate and 30% nitric acid (HNO ₃) 0.75 mole aqueous solution forming and 100 μ l contain HNO ₃0.75 mole palladium nitrate aqueous solution [Pd (NO ₃) ₂Solution] mix, and dilute with the water of 315 μ l.Described solution impregnating carrier oxide with 640 μ l.The support oxide that to so flood is under 80 ℃ in drying oven dry 16 hours then.In Muffle furnace, under 500 ℃, in air, described material is calcined 2 hours (being called the fresh ＂ catalyst of ＂) subsequently.In addition, its part is calcined 16 hours (being called the aging ＂ catalyst of ＂) in air under 700 ℃.

The load of gained support oxide is the palladium of 2wt% and the tin of 5wt%.

Embodiment 2-4 (B2-B4)

Be similar to embodiment 1 and the preparation catalyst, thereby make the aqueous solution dipping of support oxide with tin oxalate, palladium nitrate and platinum nitrate, wherein said aqueous solution HNO ₃Handle.

In table 1, be the composition that benchmark has provided various catalyst with wt%, wherein said specification relates to the element form of noble metal and tin.

Embodiment 5

In order to prepare catalytic active substance, the silica-alumina of suspension Sasol company (Siralox 5/320) in water, and in ball milling, it is ground.After the drying, provide material that 0.5g grinds as support oxide.

Administration of active ingredients is implemented in two steps on support oxide.In the first step, support oxide contains the HNO that contains of 211 μ l tin oxalates and 66 μ mol palladium nitrates with 800 μ l ₃The aqueous solution flood, and carry out drying.In second step, so the carrier of dipping floods with the aqueous solution that contains 15 μ mol platinum nitrates, then 80 ℃ dry 16 hours down.

Under 500 ℃, in air, described material is calcined 2 hours (being called the fresh ＂ catalyst of ＂) subsequently.In addition, its part is calcined 16 hours (being called the aging ＂ catalyst of ＂) in air under 700 ℃.

Amount with support oxide is a benchmark, and load is the palladium of 1.4wt%, the platinum of 0.6wt% and the tin of 5wt%.

Embodiment 6

Be similar to embodiment 5 and the preparation catalyst, wherein in second impregnation steps, substitute platinum nitrate with EA platinate (bis-ethanol ammonium-hexahydroxy-platinate).

Embodiment 7

In order to prepare catalytic active substance, the silica-alumina (Siralox 5/320) of Sasol company is mixed with water, and in ball milling, it is ground.Under stirring condition, will contain the suspension of 0.5g support oxide and the aqueous solution that 800 μ l contain 211 μ mol tin oxalates and 66 μ mol palladium nitrates, wherein in described 211 μ mol tin oxalates, add small amount of H NO ₃, make described mixture drying then, and in Muffle furnace, under 500 ℃, in air, calcined 2 hours.Subsequently, the aqueous solution that usefulness contains 15 μ mol EA platinates floods described material, and following dry 16 hours at 80 ℃.

Amount with support oxide is a benchmark, and the load of annexing ingredient is the palladium of 1.4wt%, the platinum of 0.6wt% and the tin of 5wt%.

Embodiment 8

Be similar to embodiment 1 and the preparation catalyst, wherein with the contain HNO of support oxide with tin oxalate, palladium nitrate and platinum nitrate ₃Aqueous solution dipping.

With respect to the amount of support oxide, load is the palladium of 1wt%, the platinum of 1wt% and the tin of 5wt%.

Embodiment 9

Be similar to embodiment 1 and the preparation catalyst, wherein with the HNO that contains of tin oxalate, palladium nitrate and ruthenium-nitrosyl radical-trinitrate ₃Solution impregnating carrier.

Amount with support oxide is a benchmark, and load is the palladium of 1.8wt%, the ruthenium of 0.2wt% and the tin of 5wt%.

Embodiment 10-13 (B10-B13)

Be similar to embodiment 1 and the preparation catalyst, wherein use the HNO that contains of tin oxalate, palladium nitrate, platinum nitrate and ruthenium-nitrosyl radical (nitroyl)-trinitrate ₃The solution impregnating carrier oxide.

Embodiment 14-29 (B14-B29)

Be similar to embodiment 1 and the preparation catalyst, tin, palladium and the platinum of wherein carrier loaded different amounts.Prepare catalyst by two or three step dipping process with higher tin load.

Embodiment 30 (B31)

In order to prepare catalytic active substance, the silica-alumina (Siralox 5/170) of Sasol company is suspended in water, and in ball milling, it is ground.After the drying, provide material that 2g grinds as support oxide.

The HNO that contains that 9ml is contained 376 μ mol palladium nitrates and 1685 μ mol tin oxalates ₃The aqueous solution mixes with support oxide, and dry in circulating air.Subsequently, under 500 ℃, in air, described material is calcined 2 hours (being called the fresh ＂ catalyst of ＂).In addition, its part is calcined 16 hours (being called the aging ＂ catalyst of ＂) in air under 700 ℃.

Amount with support oxide is a benchmark, and load is the palladium of 2wt% and the tin of 20wt%.

Embodiment 31 (B31)

In order to prepare catalytic active substance, the silica-alumina (Siralox 5/170) of Sasol company is suspended in water, and in ball milling, it is ground.After the drying, provide 2

The material that g grinds is as carrier.

Administration of active ingredients carries out in two steps on support oxide.In the first step, contain the HNO that contains of 1685 μ mol tin oxalates with 9ml ₃The solution impregnating carrier oxide, and dry in circulating air.In second step, with the support oxide of dipping like this again with the aqueous solution dipping that contains 376 μ mol palladium nitrates, and 80 ℃ dry 16 hours down.Subsequently, under 500 ℃, in air, described material is calcined 2 hours (being called the fresh ＂ catalyst of ＂).In addition, its part is calcined 16 hours (being called the aging ＂ catalyst of ＂) in air under 700 ℃.

Embodiment 32-36 (B32-B36)

Be similar to embodiment 30 and the preparation catalyst, wherein change the load capacity of palladium and tin.

Embodiment 37-47 (B37-B47)

Be similar to embodiment 30 and the preparation catalyst, wherein the Puralox SCFa140 of Sasol company is used as carrier, and changes the composition (referring to table 1) of active component.

Embodiment 48-106 (B48-B106)

Be similar to embodiment 1 and the preparation catalyst, wherein with the HNO that contains of tin oxalate, palladium nitrate and platinum nitrate ₃Aqueous solution dipping contains the different carriers of aluminium oxide and silica and the physical mixture of oxidation carrier and zeolite.

In table 1, applied support oxide of Embodiment B 1-B106 and prescription composition have been provided.

Embodiment 107-117 (B107-B117)

Be similar to embodiment 1 and the preparation catalyst, wherein with the HNO that contains of tin oxalate, palladium nitrate ₃The salt of the aqueous solution and promoter and optional boric acid impregnated carrier oxide S iralox 5/320.

In table 2, provided the composition of corresponding catalyst.

Embodiment 118-150 (B118-B150)

Be similar to embodiment 30 and the preparation catalyst, wherein use the HNO that contains of tin oxalate, palladium nitrate, ruthenium-nitrosyl radical-trinitrate (B127-B132) ₃The support oxide of the following form of salt load of the aqueous solution and promoter: Puralox SCFa 140, the mechanical impurity (B143) of Puralox SCFa 140/L3 (B149, B150) or Puralox SCFa 140 and beta-zeolite.

In table 2, provided the composition of corresponding catalyst based on wt%, wherein these specifications relate to the element form of noble metal, tin and promoter component.

Embodiment 151 (B151)

The catalyst of present embodiment prepares as follows, wherein uses the tin impregnated alumina under the situation of no zeolite, and zeolite is mixed with aluminium oxide/tin-oxide composition.In addition, described catalyst is administered on the honeycomb support.

Then, make 200g aluminium oxide and 900ml contain the HNO that contains of 0.17mol tin oxalate ₃Aqueous solution, and dry in circulating air.Subsequently, by method noted earlier described material is calcined in air.

Then, the tin aluminum composition that so obtains is suspended in deionized water, and in ball milling, it is ground.The zeolite that in suspension, adds the 40g iron content again.Making coating suspension be adjusted to its solid content by the adding deionized water is 20wt%.

Application is made catalyst carrier by the honeycomb core that has 400cpsi (port number of going up per square inch) of the Cordierit of NGK company preparation, before its to be cut into diameter be that 1 inch and length are 2 inches size.

By repeatedly soaking aluminium oxide/tin composition and zeolite applies described core in applying suspension, wherein behind each soaking step, in order to remove excessive suspension, the passage of core all will be blown sky.Behind each coating step, in air stream,, and calcine by preamble is described subsequently described core drying.The load of wash coat is 130g/l.What described load was represented is the solid content that is administered to the wash coat on the formed body after the calcining.

Using by soak described coating core in palladium nitrate solution of palladium compound implemented.The concentration of palladium nitrate solution is regulated in some way, thereby can use 40g/ft in an impregnation steps ³Pd.Dry so core of dipping in air stream, and calcining in air stream then.

Measure in order to carry out synthesis gas, the catalyst with carrier band is transferred in the material that grinds in the mortar carefully.

Embodiment 152 (B152)

The catalyst of present embodiment is with double-deck formal construction.

In order to prepare the ground floor of catalyst, the 200g aluminium oxide is suspended in deionized water, and in ball milling, grind.So the coating suspension that forms has the solid content of 20wt%.Described coating suspension has extraordinary bond properties, and can use under the situation of not adding other adhesive, thus first coating of preparation wash coat.

Application by the honeycomb core that has 400cpsi (port number of going up per square inch) of the Cordierit of NGK company preparation as catalyst carrier, before its to be cut into diameter be that 1 inch and length are 2 inches size.

Apply described core by repeatedly soaking in applying suspension with alumina washcoat, wherein behind each soaking step, in order to remove excessive suspension, the passage of described core all will be blown sky.Behind each coating step, in air stream,, and calcine subsequently described core drying.The load of wash coat is 108g/l.What described load was represented is the solid content that is administered to the wash coat on the formed body after the calcining.

Using tin compound soaks in 0.5 mole tin oxalate solution by the core that will apply in the past and implements.Dry described core in air stream, and calcining in air stream subsequently then.

The ground floor of catalyst contains the aluminium oxide of 108g/l and the tin of 9.5g/l.

In order to prepare the second layer of catalyst, zeolite is suspended in deionized water, and in ball milling, grind.So the coating suspension that forms has the solid content of 20wt%.In order to improve bond properties, add colloidal state SiO ₂Suspension.

Apply described core by in zeolite suspension, repeating to soak with the second layer then.Wherein behind each soaking step, in order to remove excessive zeolite suspension, the passage of described core all will be blown sky, and in air stream with described core drying.Subsequently, the described coating of calcining in air stream.The load of the second layer is 35g/l.What described load was represented is the solid content that is administered to the wash coat that contains zeolite on the formed body after the calcining.

Second coating of catalyst contains the zeolite of 35g/l and the SiO of 1.05g ₂

Using palladium implements by soak described core in palladium nitrate aqueous solution.Dry described core in air stream then, and in Muffle furnace, in air, calcine (being called the fresh ＂ catalyst of ＂).

Finished catalyst contains 40g/ft ³Palladium.

Embodiment 153 (B153)

In order to test, press embodiment 152 preparation catalyst at the Engine Block Test station.Correspondingly amplify consumption, thereby preparation size is the carried catalyst of 5.66 ＂ x6 ＂.The honeycomb support that is made by Cordierit is derived from NGK company and has the cellular densities of 400cpsi.

Comparative Examples 1 (VB1)

As a comparison, the platinum content of using based on platinum is 3.1g/l (90g/ft ³) oxidation catalyst (＂ reference catalyst ＂).

Comparative Examples 2 (VB2)

As a comparison, the tin-oxide catalyst that does not contain support oxide of application load Pd.In order to prepare described material, get the pulverous tin-oxide of 1.5g (Merck company, sequence number is 1,078,180,250), and with the HNO that contains of palladium nitrate ₃The aqueous solution [Pd (NO ₃) ₂Solution] dipping.In drying oven, that the tin-oxide that so floods is following dry 16 hours at 80 ℃ then.Subsequently, in Muffle furnace, under 500 ℃, in air, described material is calcined 2 hours (being called the fresh ＂ catalyst of ＂).In addition, its part is calcined 16 hours (being called the aging ＂ catalyst of ＂) in air under 700 ℃.

The load of gained tin-oxide is the palladium of 2wt%.

Table 1: based on the amount and the type of different carriers oxide, platinum family active metal component, catalyst is formed the variation in its preparation process:

Table 2: catalyst is formed, and described catalyst prepares as the platinum group metal active component with palladium or palladium and ruthenium, and is doped with the different component of two kinds of Different Weight amounts

Table 3: test with fresh catalyst with in the catalysis that 700 ℃ of aging down catalyst carry out CO and HC oxidation, its result is

Table 4: use different catalyst and carry out the catalysis test of CO and HC oxidation after 16 hours 1000 ℃ of following heat ageings, its result is:

^*The platinum that has double amount

Table 5: use different catalyst and test in 750 ℃ of following hydrothermal agings carry out CO and HC oxidation after 16 hours catalysis, its result is:

Table 6: use different catalyst SO ₂Carry out the catalysis test of CO and HC oxidation after aging, its result is:

Table 7: use the catalysis test that a series of catalyst carries out CO and HC oxidation, wherein said catalyst is in heat ageing (700 ℃, 16 hours) and use SO subsequently ₂Test after aging, test result is as follows:

Embodiment	T ₅₀(CO)[℃]	T ₅₀(HC)[℃]
Embodiment	T ₅₀(CO)[℃]	T ₅₀(HC)[℃]	B1	267	271
B8	224	236	B1	267	271
B8	224	236	B14	267	279
B18	232	236	B14	267	279
B18	232	236	B19	228	236
B20	222	234	B19	228	236
B20	222	234	B21	244	256
B22	245	256	B21	244	256

B23	241	241
B23	241	241	B24	211	240
B25	201	217	B24	211	240
B25	201	217	B26	223	235
B27	236	244	B26	223	235
B27	236	244	B28	224	232
B29	230	242	B28	224	232
B29	230	242	B30	197	210
B31	194	207	B30	197	210
B31	194	207	B32	204	208
B33	195	213	B32	204	208
B33	195	213	B34	194	202
B35	207	225	B34	194	202
B35	207	225	B36	201	223
B37	192	205	B36	201	223
B37	192	205	B38	193	202
B39	195	207	B38	193	202
B39	195	207	B40	199	221
B41	202	215	B40	199	221
B41	202	215	B42	204	212
B43	216	233	B42	204	212
B43	216	233	B44	213	226
B45	214	223	B44	213	226
B45	214	223	B46	202	214
B47	196	196	B46	202	214
B47	196	196	B53	247	253
B54	207	220	B53	247	253
B54	207	220	B55	197	209
B58	235	241	B55	197	209

B59	240	240
B59	240	240	B60	238	244
B61	245	245	B60	238	244
B61	245	245	B107	240	252
B108	232	232	B107	240	252
B108	232	232	B109	246	246
B110	227	232	B109	246	246
B110	227	232	B111	223	235
B112	229	229	B111	223	235
B112	229	229	B113	227	230
B114	226	232	B113	227	230
B114	226	232	B115	235	241
B116	184	201	B115	235	241
B116	184	201	B117	222	235
B118	228	234	B117	222	235
B118	228	234	B119	212	224
B120	212	217	B119	212	224
B120	212	217	B121	200	214
B122	202	216	B121	200	214
B122	202	216	B123	215	223
B124	218	226	B123	215	223
B124	218	226	B125	220	220
B126	208	208	B125	220	220
B126	208	208	B127	211	226
B128	221	221	B127	211	226
B128	221	221	B129	209	226
B130	218	228	B129	209	226
B130	218	228	B131	202	207
B132	198	209	B131	202	207

B133	198	220
B133	198	220	B134	185	196
B135	189	196	B134	185	196
B135	189	196	B136	185	196
B137	197	207	B136	185	196
B137	197	207	B138	195	205
B139	185	196	B138	195	205
B139	185	196	B140	191	207
B141	201	207	B140	191	207
B141	201	207	B142	196	201
B144	191	201	B142	196	201
B144	191	201	B148	196	201
VB1	202	220	B148	196	201

Table 8: use different catalyst and carry out the catalysis test of CO and HC oxidation after 16 hours 850 ℃ of following heat ageings, test result is as follows:

Sample	T ₅₀(CO)[℃]	T ₅₀(HC)[℃]
Sample	T ₅₀(CO)[℃]	T ₅₀(HC)[℃]	B139	186	204
B140	157	186	B139	186	204
B140	157	186	B141	182	208
B142	182	201	B141	182	208
B142	182	201	B144	175	204
B145	186	208	B144	175	204
B145	186	208	B149	179	201
B150	175	190	B149	179	201
B150	175	190	B151	175	190
B152	172	188	B151	175	190
B152	172	188	VB1	203 ^*	219 ^*

^*800 ℃ of following heat ageings after 10 hours

For example, than reference catalyst VB1, catalyst B 3, B4 and B5 demonstrate extraordinary result in fresh attitude and aging attitude (table 3) and the back (table 4) of at high temperature wearing out to CO and HC conversion.

As example, the oxidation characteristic of 5 pairs of carbon monoxide of catalyst B provides in Fig. 1.

Compare the T of catalyst B 5 with the value of initial disclosed prior art catalyst (EP 0 432 534 B2 and EP 0 566 878A1) ₅₀Value advantageously will be hanged down.

Compare with reference catalyst VB1 (table 7), the catalyst of embodiment 31,37,38,134,136,139 and B144 all shows very high activity in heat ageing with after wearing out with sulphur subsequently.

Than the VB2 and the support oxide of load not, the phase composition x-ray analysis of catalyst B 31 and B24 (each includes fresh attitude and aging attitude) shows that the tin-oxide of catalyst of the present invention has nanoscale structures or X ray picture impalpable structure.Therefore, for catalyst V B2, tin-oxide is high-visible in the reflection of 2 θ～26.7 and 34.0 o'clock, is difficult to difference and obviously widens (Fig. 2) and the reflection of catalyst B 31 and B24 is extremely faint.

Fig. 3 has provided the diffraction analysis of following sample: (a) not support oxide Siralox 5/320, (c) B24 (fresh) and (d) B24 (wearing out) of load of VB2, (b).

Catalyst B 31 and B37 after the heat ageing and the phase composition X-ray analysis after carrying out catalysis test show that compare with fresh sample, sample does not have significant change.Can exemplarily support described result by Fig. 4 and diffraction analysis shown in Figure 5.As for X-ray diffraction equipment, use equipment (the BRUKER AXS that has surface detectors GADDS) from Bruker company.

Fig. 4 has provided the diffraction analysis through the catalyst of B31 after the following different pre-treatment step: (a) fresh sample, (b) after aging sample and (c) through the fresh sample after the catalysis test.Wherein Siralox 5/170 is used as support oxide.

Fig. 5 has provided the diffraction analysis through the catalyst of Embodiment B 37 after the following different pre-treatment step: (a) fresh sample, (b) after aging sample and (c) through the fresh sample after the catalysis test.Wherein Puralox SCFa 140 is used as support oxide.

Overall with evaluation during as for half-peak and press the granularity assessment of Scherrer equation has been estimated at 2 θ～26.7 (d=3.34591) and 2 θ～34.0 (d=2.64021) and has been located by the reflection owing to tin-oxide.Confirmed the feature tin-oxide of granularity less than 1nm-30nm.For B24 (fresh), do not detect the reflection of tin-oxide.Therefore, described sample is the amorphous ＂ of ＂ X ray picture for tin-oxide.

The diffraction analysis of catalyst of the present invention is not found significantly reflection, and this reflection is clearly by owing to palladium.Therefore, palladium also exists with X ray picture amorphous form or nanoscale form.

Tin and palladium dispersed uniform are verified by the REM/EDX (with the SEM of energy-dispersive X-ray fluorescence coupling) on the selected catalyst.Table 9 contains and is normalized to the result that 100% EDX-analyzes.Therefore, press the concentration that ＂ element scanning ＂ implication detects tin and palladium at three diverse locations (measurement point 1,2 and 3) of the selected catalyst of graininess respectively.Siralox 5/320 is used as support oxide, and it contains the SiO of 5wt% ₂Al with 95wt% ₂O ₃Measurement result shows that tin and palladium are evenly dispersed on the support oxide very much.Particularly, for each sample, detected Al/Sn ratio and Sn/Pd are than all being almost steady state value (respectively at measurement point 1,2 and 3 places).

Carry out with REM/EDX (the Hi tachi S3500N that has the Oxford INCA of EDX system).Must be noted that as measuring principle,, may take place with obviously departing from that the catalyst of percentage (wt%) expression is formed than normal value.But Al (aluminium) and tin (Sn) and palladium (Pd) and Sn are more meaningful than absolute value with the relative concentration of Pd.

Table 9: the element distribution results of utilizing REM/EDX to obtain to selected catalyst:

The uniformity of the amorphous or nanoscale structures of tin also can reflect by the specific area of sample on catalyst and the support oxide, and described specific area detects by the BET measurement.Therefore, it is apparent that the BET surface area of catalyst changes with the tin load hardly.In addition, under the situation of high tin load, the Kong Buhui of support oxide stops up, and described obstruction may be caused by the tin-oxide crystallization, and promptly ＂ agent structure ＂ forms tin-oxide.BET measures and implements with the TriStar type nitrogen adsorption plant of Micromeritics company.

Table 10: the BET surface area of selected catalyst

Measured BET surface area is the surface area that directly derives from measurement result under the initial sample weight of determining.And the BET surface area through overregulating is by the standardized meter area of unified support oxide amount.

Fig. 6 has provided the accumulation HC discharging of the catalyst of Embodiment B 153, and it obtains by new Europe superscript locomotive circulation at the Engine Block Test station.The 1.9L TDI engine of VW company is used as test carrier.As reference catalyst, adopted the respective series catalyst that contains active component platinum.

Fig. 7 has provided the accumulation CO discharging of the catalyst of Embodiment B 153, and it obtains by new Europe superscript locomotive circulation at the Engine Block Test station.Equally, the 1.9L TDI engine of VW company is used as test carrier.As reference catalyst, adopt the respective series catalyst that contains active component platinum.

Fig. 6 and Fig. 7 show: new oxidation catalyst not only is starkly lower than EuropeanNorm EU-IV at CO, and better than the reference catalyst based on platinum aspect CO and HC oxidation.The repeatability of test has proved that catalyst of the present invention has stable conversion ratio, and does not have inactivation in the process of test.

The embodiment of the embodiment of catalyst, wherein tin-oxide and palladium are present on the nano carrier oxide:

In the accompanying drawings:

Figure 20 1: utilize the noble metal load capacity to be 31g/ft ³The catalyst sample of embodiment 201 (B201), when it is being in (a) fresh attitude and (b) 700 ℃ of following heat ageings after 16 hours, as the CO conversion ratio of reaction temperature function.In Figure 20 1, transverse axis is for ℃ being the temperature of unit representation, and the longitudinal axis is for being the CO conversion ratio of unit representation with %.

Figure 20 2: the X-ray diffraction analysis of catalyst that is in the Embodiment B 203 of the fresh attitude ＂ of ＂.In the drawings, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the x transmitted intensity of unit representation wantonly.

Figure 20 3: the X-ray diffraction analysis of catalyst that is in the Embodiment B 206 of the aging attitude ＂ (promptly behind 700 ℃ of following hydrothermal agings) of ＂.In the drawings, transverse axis is for being 2 θ angles of unit representation with the degree, and the longitudinal axis be to choose the X ray intensity of unit representation wantonly.

Figure 20 4: the TEM that takes from Embodiment B 203 takes a picture: (a) scope (scale is represented the length range of 50nm) of expression sample under high-resolution, (b) under the average resolution rate expression sample scope (scale is represented the length range of 100nm) and (c) under low resolution the expression sample scope (scale is represented the length range of 200nm).

The catalysis test

Fully automatically implementing activity measurement in the catalyst facility, wherein said facility has the fixed bed reactors of being made by stainless steel of 48 parallel runnings, and (internal diameter of each reative cell is 7

mm)。Catalyst is being similar under the condition of diesel exhaust, utilizes excess of oxygen to test with continuous operation mode under the following conditions:

Temperature range: 120-400 ℃

Waste gas is formed: CO:1500ppmv, C ₁(octane): 100ppmv,

NO：300ppmv，O ₂：10％，CO ₂：10％，H ₂O：6％，

N ₂: surplus

Gas flow: 45 l/h unit's catalyst

Catalyst quality: 0.5g

Listed in these embodiments catalyst all prepares by honeycombed catalyst.Then they are ground, and as the material of main part of measuring.

As reference catalyst (VB), application has 3.1g/l (90g/ft ³) platinum be used for the cellular oxidation catalyst of being purchased of diesel engine exhaust (VB).The described catalyst of 0.5g is ground, and also as the material of main part of measuring.Based on identical catalyst quality, carry out comparing and measuring between catalyst of the present invention and the reference catalyst.Wherein, concerning catalyst of the present invention, in reactor, use significantly lower noble metal quality.

CO and CO ₂Evaluation implement with the ND-IR analyzer (model is ＂ AdvanceOptima ＂) of ABB AB.Definite FID (model is ＂ AdvanceOptima ＂) by ABB AB of hydrocarbon implements.O ₂λ-sensor by Etas company is determined, and NO, NO ₂And NO _XMeasurement utilize the UV equipment (model is ＂ Advance Optima ＂) of ABB AB to implement.

For evaluate catalysts, use the T of CO oxidation ₅₀Value (temperature when reaching 50% conversion ratio) is as the standard of oxidation activity.

T for the catalyst after being in fresh attitude and handling through different aging (heat ageing and hydrothermal agings) ₅₀Value is summed up in table 202.

Heat ageing and hydrothermal aging

In Muffle furnace, under 700 ℃ of temperature, in air, implement the heat ageing of catalyst.Thereby catalyst kept 16 hours under described temperature, was cooled to room temperature then.

Under the condition identical, implement hydrothermal aging, but charging contains the air of 10% water in Muffle furnace with heat ageing.

Embodiment

Embodiment 201

In order to prepare catalyst of the present invention, with the nano carrier oxide (Disperal P2) of Sasol company by dispersed with stirring at room temperature in water.Formed coating suspension contains the solid of 20wt%.Described coating suspension shows extraordinary adhesion characteristic, and it can be used to prepare wash coat under the situation that does not add other adhesive.Application by the honeycomb core that has 400cpsi (port number of going up per square inch) of the Cordierit of NGK company preparation as catalyst carrier, in that it is cut into the specification of 2*2*2cm before.Apply described core by it being soaked into coating suspension with wash coat.Coating under 80 ℃ at air drying, and in Muffle furnace under 500 ℃ in air the calcining 2 hours.The load of wash coat is 109g/l.What the load of wash coat was represented is the fraction solids that is administered to the wash coat on the formed body after the calcining.

Administration of active ingredients is implemented by the core that the aqueous solution of nitric acid dipping contains wash coat that contains with tin oxalate/palladium nitrate of 3562 μ l on wash coat.Wherein, with 1998 μ 1 by tin oxalate and 30% nitric acid (HNO ₃) 1.0 molar solutions formed and 164 μ l, 0.75 molar nitric acid palladium contain HNO ₃The aqueous solution [Pd (NO ₃) ₂Solution] mix, and dilute with 1400 μ l water.Descend dry described cores at 80 ℃ subsequently, and under 500 ℃, in air, calcine 2 hours (being called the fresh ＂ catalyst of ＂).

Its part is calcined 16 hours (being called ＂ heat ageing ＂ catalyst) in air under 700 ℃.

Finished catalyst contains 31g/ft ³Palladium.

Embodiment 202

Be similar to embodiment 201 and the preparation catalyst, use the mixture of following material this moment: the beta-zeolite of the nano carrier oxide of 80wt% (the Disperal P2 of Sasol company) and 20wt% (H-BEA 25 of S ü d-Chemie company).Total solid in the aqueous suspension also is 20wt%.

Finished catalyst contains wash coat and the 28g/ft of 50g/l ³Palladium.

Embodiment 203

Be similar to embodiment 201 and the preparation catalyst, wherein use the nano carrier oxide (Disperal) of Sasol company for applying suspension.

Finished catalyst contains wash coat and the 39g/ft of 69g/l ³Palladium.

Embodiment 204

Be similar to embodiment 201 and the preparation catalyst, use the mixture of following material this moment: the DuPont company of nano carrier oxide of the Sasol company of 95wt% (Disperal P2) and 5wt% be the SiO of colloidal suspension liquid ₂(Ludox CL).

Finished catalyst contains wash coat and the 23g/ft of 27g/l ³Palladium.

Embodiment 205

Be similar to embodiment 201 and the preparation catalyst, use the mixture of following material this moment: the nano carrier oxide (Disperal) of the Sasol company of 60wt% and the beta-zeolite of 40wt% (the Zeocat FM-8/25H of Zeochem company).

Finished catalyst contains wash coat and the 28g/ft of 100g/l ³Pd.

Embodiment 206

Be similar to embodiment 201 and the preparation catalyst, wherein use gallium and make adulterant.

Finished catalyst contains wash coat and the 14g/ft of 50g/l ³Palladium.

Embodiment 207

Be similar to embodiment 201 and the preparation catalyst, wherein use indium and make adulterant.

Finished catalyst contains wash coat and the 14g/ft of 50g/l ³Palladium.

The specification of in table 201, having summarized catalyst of the present invention as embodiment 201-207.The composition of active component reports that based on wt% specification described herein is relevant with the element form of noble metal, tin and dopant component.

Provided to the Embodiment B 203 of fresh attitude in Figure 20 2 and Figure 20 3 and be the X-ray diffraction analysis of the Embodiment B 206 of aging attitude, it shows and does not have the crystal phase that contains tin-oxide or contain the palladium oxide component.The reflection of finding in diffraction analysis is by the structure owing to the support oxide of being made up of cordierite.Diffraction analysis shown in the figure is gathered by BRUKER AXS equipment, and described equipment is furnished with the GADDS surface detectors.

The TEM that represents in Figure 20 4a-c takes a picture and has shown the catalyst of the Embodiment B 203 that is in the fresh attitude ＂ of ＂.Take a picture by TEM, sample does not have uneven feature as can be known.Take a picture according to EDX, do not detect, have the scope that contains palladium or the agglomeration of stanniferous component.Therefore, in the resolution limit of device therefor, can determine described even distribution.Photograph utilizes the TEM equipment H-7500 of Hitachi company, and the EDX measurement device INCA of combination Oxford instrument company carries out.

Table 201: the composition of catalyst

Table 202: the catalysis of carrying out the CO oxidation with the catalyst through heat ageing or hydrothermal aging is tested, and its result is as follows:

Embodiment	Noble metal (NM)	The quality [g] of noble metal in detecting catalyst	T ₅₀(CO) [℃] at 700 ℃ of down aging 16h
Embodiment	Noble metal (NM)	The quality [g] of noble metal in detecting catalyst	T ₅₀(CO) [℃] at 700 ℃ of down aging 16h	B201	Pd	0.00078	157
B202	Pd	0.00081	158	B201	Pd	0.00078	157
B202	Pd	0.00081	158	B203	Pd	0.00107	168
B204	Pd	0.00072	171	B203	Pd	0.00107	168
B204	Pd	0.00072	171	B205	Pd	0.00080	154 ^*
B206	Pd	0.00044	168 ^*	B205	Pd	0.00080	154 ^*
B206	Pd	0.00044	168 ^*	B207	Pd	0.00044	168 ^*
VB201	Pt	0.00250	172	B207	Pd	0.00044	168 ^*

^*Hydrothermal aging

Claims

1. one kind contains tin-oxide, palladium and optional platinum, rhodium, iridium and ruthenium, be used for from the rich oxygen containing waste gas while removal of carbon monoxide of poor burn engine and the purposes of hydrocarbon with the catalyst of support oxide, if wherein except that palladium, also use platinum, then the weight ratio of palladium and platinum is 1:1 to 50:1, if and application rhodium, ruthenium, iridium or its mixture replacing platinum, then palladium and rhodium, ruthenium, the weight ratio of iridium or its mixture is 2.5:1 to 1000:1, be characterised in that tin-oxide and palladium are present on the support oxide with the granularity of 0.5-100nm, and described carbon monoxide and hydrocarbon are oxidized to water and carbon dioxide by described catalyst.

2. the purposes of claim 1 is characterised in that described support oxide contains silicon or aluminium or silicon and aluminium.

3. claim 1 or 2 purposes are characterised in that described catalyst contains zeolite.

4. the purposes of claim 3 is characterised in that the form application of described zeolite with Y-zeolite, modenite or the zeolite-β of H-ZSM-5, dealuminzation Y-zeolite, hydrothermal treatment consists.

5. the purposes of claim 1 is characterised in that described catalyst is doped with the promoter that one or more are selected from indium oxide, gallium oxide, alkali metal oxide, alkaline earth oxide and rare earth oxide.

6. the purposes of claim 1 is characterised in that described catalyst contains boron oxide compound.

7. the purposes of claim 1 is characterised in that with the weight ratio with respect to support oxide be benchmark, is 3-50wt% in the amount of tin tin-oxide.

8. the purposes of claim 1 is characterised in that with the weight ratio with respect to support oxide be benchmark, and palladium is 0.2-10wt% with the amount of platinum, rhodium, iridium and the ruthenium chosen wantonly.

9. the purposes of claim 1 is characterised in that the weight ratio in tin tin-oxide and the palladium and the gross weight of platinum, rhodium, iridium and the ruthenium chosen wantonly is 2.0:1 to 25:1.

10. the purposes of claim 1 is characterised in that then the weight ratio of the gross weight of palladium and platinum and at least a other platinum group metal is 0.3:1 to 1000:1 if also use platinum and at least a other platinum group metal except that palladium.

11. the purposes of claim 3 is characterised in that with the support oxide to be benchmark, the total amount of zeolite is 5-50wt%.

12. the purposes of claim 5 is characterised in that be 0.66:1 to 33:1 in the tin tin-oxide with weight ratio in the gross weight of all promoter of element.

13. the purposes of claim 6 is characterised in that support oxide and is 1:0.00005 to 1:0.2 in the weight ratio of boron boron oxide compound.

14. the purposes of claim 1 is characterised in that described catalyst is with powder, particle, extrudate, formed body or the application of coating honeycomb ceramics form.

15. the purposes of claim 1 is characterised in that described purposes comprises simultaneously by the oxidation removal carbon black pellet.

16. the purposes of claim 15 is characterised in that the face coat of described catalyst as the carbon black pellet filter.

17. one kind contains tin-oxide, palladium and optional platinum, rhodium, iridium and ruthenium, catalyst with support oxide, if wherein except that palladium, also use platinum, then the weight ratio of palladium and platinum is 1:1 to 50:1, if and application rhodium, ruthenium, iridium or its mixture replacing platinum, then palladium and rhodium, ruthenium, the weight ratio of iridium or its mixture is 2.5:1 to 1000:1, be characterised in that tin-oxide and palladium are present on the support oxide with the granularity of 0.5-100nm, described catalyst contains zeolite, and described catalyst is doped with one or more and is selected from platinum, rhodium, the element of iridium or ruthenium, perhaps described catalyst is doped with one or more and is selected from indium oxide, gallium oxide, alkali metal oxide, the promoter of alkaline earth oxide and rare earth oxide, perhaps described catalyst is doped with one or more and is selected from platinum, rhodium, the element of iridium or ruthenium and one or more are selected from indium oxide, gallium oxide, alkali metal oxide, the promoter of alkaline earth oxide and rare earth oxide.