CN1984715A - Catalyst, exhaust gas purification catalyst, and method for manufacturing same - Google Patents

Abstract

A catalyst suppresses aggregation of metal particles and has superior heat resistance. In the catalyst, metal particles are supported by a surface of a carrier while being partially embedded therein.

Description

Catalyst, exhaust gas purifying catalyst and manufacture method thereof

The application requires the Japanese publication No.2004-202 of submission on July 8th, 2004, the Japanese publication No.2004-377 that on December 27th, 125 and 2004 submitted to, and 929 rights and interests, its whole contents is hereby incorporated by.

Technical field

The present invention relates to catalyst, exhaust gas purifying catalyst and make the method for catalyst and more specifically, relate to the exhaust gas purifying catalyst that is used to purify the waste gas of discharging from internal combustion engine.

Background technology

Owing on global basis, carry out the emission control of automobile, three-way catalyst be used for removing the hydrocarbon (HC) that waste gas comprises, carbon monoxide (CO), and nitrogen oxide (NO cumulatively ₂).Three-way catalyst is usually by porous oxide carrier such as aluminium oxide (Al ₂O ₃) the thin noble metal of load such as platinum (Pt), palladium (Pd) and rhodium (Rd) form.The effect of this noble metal is as the activity of such catalysts point.

Noble metal tends at high temperature, as several Baidu (℃) assemble down.This gathering causes the reduction of the surface area of active site.Therefore, for preventing to assemble, distance and its particle diameter of control between the thin noble metal have been considered to control.

Control as for distance between the thin noble metal, since when with thin precious metal particle load externally on the carrier surface time its gathering be easy to carry out, so also attempt with on the inside of carrier surface, i.e. this thin noble metal of load on the surface of carrier hole.In addition, as for the control of the particle diameter of thin noble metal,, therefore require the original dimension of thin at least noble metal to have certain minimum of a value (referring to people such as Ph.Buffat because the fusing point of particle reduces with the reduction of size, Phys.Rev.A.Vol.13, No.6 (1976)).Further, when the particle diameter of the thin noble metal of load was inhomogeneous, the localization metallic that has big particle diameter by use was as nuclear, and its gathering is easier to carry out (referring to M.Che., people such as J.F.Dutel, J.Phys.Chem.80, p2371. (1976)).

Therefore, for suppressing the gathering of thin noble metal, consider to use effectively to have the diameter that satisfies certain minimum of a value and on carrier surface, disperse equably and the thin noble metal of load particle.

In the trial of finishing above content, catalyst has been proposed, wherein use chelating agent to form metallic colloid and wherein metallic is disperseed on carrier surface and load (disclosing No.2000-279824, the 2nd page) referring to Japanese unexamined patent.In addition, catalyst has been proposed also, wherein by using quaternary ammonium salt, by the internal holes load colloid salt (referring to the open No.2002-1119 of Japanese unexamined patent, the 2nd page) that is immersed in carrier as protecting colloid.

Yet according to technology described above, with the protective agent of polymeric material as the thin noble metal of protection, the molecular dimension of this polymeric material is greater than the bore dia in alumina support.Therefore, this thin noble metal can not be long-pending at the inner hole deposition of carrier.In addition, quaternary ammonium salt can produce the stability problem of colloid salt as under the situation of protecting colloid therein.That is, for example, colloid can partly be assembled when long time stored, then precipitation.In addition, even when simply at the thin noble metal of the hole of carrier internal load, can not suppress the migration of noble metal self.That is, because it is assembled, the deterioration of noble metal can take place unfriendly, such as previously discussed.

Summary of the invention

The present invention is to address the above problem in exploitation.According to a first aspect of the invention, this catalyst comprises the metallic by the carrier surface load, and wherein this metallic is partially submerged in the carrier.

According to a second aspect of the invention, the method of making this catalyst comprises: introduce and seal (enclosing) metallic colloid to form the sealing step of catalyst precarsor in precursor carrier, this metallic colloid is by the metallic of organic molecule protection that provides around it and is dispersed in the decentralized medium; Calcining step with calcined catalyst precursor in oxidation environment.

According to a third aspect of the invention we, exhaust gas purifying catalyst comprises catalyst layer, and this catalyst layer comprises catalyst according to a first aspect of the invention.

Owing to suppress the gathering of noble metal, catalyst of the present invention shows excellent hear resistance.

In addition, method of the present invention allows more effectively carried noble metal particle on the carrier inner surface.

These advantages of the present invention are convenient to make the exhaust gas purifying catalyst with excellent heat resistance.

Description of drawings

For fully understanding essence of the present invention and purpose, following detailed description that should reference implementation preference pattern of the present invention, relevant reading with accompanying drawing, wherein:

Fig. 1 (A) is the view of catalyst according to the invention, and Fig. 1 (B) is the part viewgraph of cross-section of catalyst according to the invention.

Fig. 2 is the flow chart that explanation is used to make the method for catalyst according to the invention.

Fig. 3 (A) is the explanatory diagram that shows mixed solution; Fig. 3 (B) is the explanatory diagram that shows metallic colloid; Fig. 3 (C) is the explanatory diagram that shows catalyst precarsor; And Fig. 3 (D) is the explanatory diagram that shows the gained catalyst.

Fig. 4 is the flow chart of the different examples of the explanation method that is used to make catalyst according to the invention.

Fig. 5 (A) is the part viewgraph of cross-section by the catalyst of the partial oxidation agent manufacturing of using the reduction amount; Fig. 5 (B) is by the part viewgraph of cross-section of use amount greater than the catalyst of the manufacturing of the partial oxidation agent in situation shown in Fig. 5 (A); And Fig. 5 (C) is the part viewgraph of cross-section by the catalyst of use even more substantial partial oxidation agent manufacturing.

Fig. 6 is the flow chart of the different examples of the explanation method that is used to make catalyst according to the invention.

Fig. 7 (A) is the explanatory diagram that shows reverse micelle; Fig. 7 (B) shows the wherein explanatory diagram of the state of the noble metal in reverse micelle and transition metal precipitation; Fig. 7 (C) shows the explanatory diagram that wherein comprises the state of precursor carrier salt and water in reverse micelle; Fig. 7 (D) shows the wherein explanatory diagram of the state of precipitophore precursor in reverse micelle; Fig. 7 (E) is the explanatory diagram of demonstration by the precipitating reagent of (collapse) acquisition of caving in of reverse micelle; And Fig. 7 (F) is the explanatory diagram that shows the catalyst that obtains.

Fig. 8 is the explanatory diagram that is presented at the relation between platinum amount and the purifying rate.

The specific embodiment

Below, with the method for reference implementation scheme detailed description catalyst, exhaust gas purifying catalyst and manufacturing catalyst.

Catalyst

To the embodiment of catalyst according to the invention be described.In the catalyst 1 of this embodiment, shown in Fig. 1 (A) and 1 (B), metallic 3 is partially submerged in the carrier 2 simultaneously by the area load of carrier 2.In this catalyst 1, because metallic 3 is partially submerged in the carrier 2 simultaneously by the area load of carrier 2, so metallic 3 is stable and do not move on the surface of carrier 2.Even at high temperature, also can prevent the gathering of metallic 3 therefore.

In this embodiment, the surface of carrier 2 comprises the outer surface of carrier 2 and forms to have the hole surface of hungry ghosts who spit fire's shape, shape of slit etc. that promptly the surface of carrier 2 comprises outer surface and inner surface in carrier 2.In addition, shown in Fig. 1 (A), because metallic 3 not only by the outer surface load of carrier 2 and by its inner surface load, therefore can effectively use the surf zone of whole catalyst, increase the catalytic activity of per unit weight catalyst and increase the waste gas adsorbance that allows reaction.When metallic during by the outer surface load of carrier, the distance between the metallic is little, makes that its gathering is easy to take place.Yet, when metallic during, increasing the distance between the metallic at the hole of carrier internal load, the result can suppress to assemble.

In addition, shown in Fig. 1 (B), in the catalyst 1 of this embodiment, owing to the area load of metallic 3 by carrier 2 is partially submerged in the carrier 2 simultaneously, the effect that centers on metallic 3 carrier 2 on every side is the maintenance thing as fixing metal particle 3.Therefore, keep the distance between the metallic 3, the result can effectively suppress the gathering of metallic 3.Usually, if the particle diameter of metallic is below the 10nm, then metallic is easy to assemble.Yet, catalyst according to the invention, because metallic 3 is partially submerged in the surface of carrier 2, retention effect is significant especially, even after heating, also can keep the state that obtains when making catalyst.Owing to keep the particle diameter of metallic, so can keep catalytic activity, the result can obtain to have the catalyst of excellent heat resistance.

In the catalyst 1 of this embodiment, the rate that exposes to the open air of the metallic 3 that is obtained by following formula is preferably 50% to 85%:

Wherein,

A is the CO adsorbance (cm on the metallic ³/ g),

B is the cross-sectional area (nm of an atom of the noble metal of load ²),

C is the density (g/cm of the noble metal of load ³),

D is the particle radii (nm) of the noble metal of load, and it is estimated by tem observation,

E be load noble metal each atomic adsorption CO molecular number stoichiometric ratio and

F is the precious metal concentration (wt%/g) in this catalyst.

For simplicity, following table provides the related data of Pt, Pd and Rh:

	Pt	Pd	Rh
				Atomic mass	195.09	106.4000	102.9060
Density (g/cm 3)	21.45	11.9900	12.4000
				Cross-sectional area (nm 2)	0.08	0.0787	0.0752
Stoichiometric ratio	1	1	2

Atomic radius ()	1.38	1.376	1.345
				The cube volume of an atom	1.1E-29	1.1E-29	1.0E-29
Surface area (the m of an atom 2)	2.4E-19	2.4E-19	2.3E-19

When the rate that exposes to the open air of metallic 3 was in 50% to 85% scope, this expression metallic 3 was partially submerged into wherein simultaneously by the area load of carrier 2.Usually, because the atom that exists on the metallic surface plays the effect of catalyst effectively, therefore cross when hanging down when the rate of exposing to the open air, although the stability of metallic is high, metallic can not sufficiently contact with reactant materials, and the result can not obtain enough catalytic activitys.Therefore, for keeping the performance as catalyst, the rate of exposing to the open air is preferably more than 50%.Yet, when the rate that exposes to the open air is too high, although the initial activity height of catalyst, by the metallic of heating gathering by the carrier surface load, result, durability deterioration.Therefore, expose rate to the open air and preferably be not more than 85%.Therefore the rate that exposes to the open air of metallic is preferably in 50% to 85% scope, when the rate that exposes to the open air in the above range the time, because metallic is disperseed and load thus, can suppress the gathering of metallic on carrier.As described below, in the catalyst 1 of this embodiment, because the rate that exposes to the open air of metallic 3 is 50% to 85%, so carrier 2 is significant for the retention effect of metallic 3, even after heating, the state that obtains in the time of also can keeping making catalyst.

The particle diameter of metallic is preferably in 1 to 10nm scope.When the rate that exposes to the open air of metallic in 50% to 85% scope and its particle diameter in 1 to 10nm scope the time, can obtain enough catalytic activitys.

Metallic preferably is made up of at least a noble metal that is selected from the group of being made up of Pt (platinum), Pd (palladium) and Rh (rhodium).Above-mentioned metal has high catalytic activity, and when as catalyst, above metal is effective.In addition, in those, can use at least two kinds of noble metals by being mixed with each other, above-mentioned as Pt and Rh.

The catalyst of the present embodiment preferably further comprises at least a transition metal that is selected from the group of being made up of Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper) and Zn (zinc), it contacts with the carrier both with noble metal, and at least a portion transition metal preferably forms complex chemical compound with carrier.In these cases, it is believed that the improvement catalytic performance because noble metal contacts with the complex chemical compound that comprises transition metal.It is believed that reason for this reason is the result of so-called spillover, wherein on being adsorbed on the surface of noble metal after, waste gas moves to the surface of complex chemical compound, is cleaned in its surface then.Promptly, it is believed that because noble metal contacts with each other with the complex chemical compound that comprises transition metal, therefore remove as the catalyst, noble metal is also as the adsorption site of absorption waste gas, and with the activation of the transition metal in the complex chemical compound with catalytic site as the generation catalytic reaction.As mentioned above, in the catalyst of the present embodiment,, therefore can improve catalytic activity owing to can obtain to comprise the effect that the complex chemical compound of transition metal improves the catalytic activity of noble metal.In addition, because at least a portion transition metal forms complex chemical compound with carrier, this complex chemical compound is as above-mentioned maintenance thing, and it suppresses the migration of noble metal.Therefore, suppress the gathering of noble metal, the result can reduce the deterioration of catalytic activity point.

Carrier preferably includes the compound that is selected from least a element in the group of being made up of Al (aluminium), Ti (titanium), Zr (zirconium), Ce (cerium) and La (lanthanum).When comprising one or more above-mentioned elements, by forming complex chemical compound with above-mentioned transition metal, this compound is as the maintenance thing of noble metal.In addition, because above-mentioned element has effect and the improvement carrier stable on heating effect of activation as the noble metal and the transition metal of catalytic metal, therefore improve catalytic activity and hear resistance.

In those, preferred noble metal is Pt above-mentioned, and transition metal is that Co and carrier are the compounds that comprises Al.In the case, by reacting with Al, Co is easy to form CoAl ₂O ₄(cobalt aluminate) is as complex chemical compound.In addition, when Pt being fixed on the cobalt aluminate surface, owing to compare with conventional alumina catalyst support, cobalt aluminate has high-fire resistance and stable crystal structure, therefore can prevent the gathering of Pt.

When complex chemical compound was inhomogeneous, a part of transition metal dissolved in single-element oxide such as aluminium oxide to form the oversize grain of transition metal.In the case, owing to can be reduced in contact between complex chemical compound and the noble metal, or can reduce the possibility that contacts with reacting gas in some cases, this complex chemical compound is preferably even as far as possible.In addition, complex chemical compound can partially or completely be made up of at least a simple oxide, complex chemical compound oxide or its analog, also can partly comprise alloy.In addition, a part of transition metal in the complex chemical compound can have zeroth order, that is, a part of transition metal can be metallic state.When the part transition metal is metallic state, be that the situation of oxide is compared with whole transition metal wherein, can increase catalytic activity in some cases and improve the efficient of waste gas purification.

As mentioned above, in catalyst of the present invention, because metallic is partially submerged in the carrier by the area load of carrier simultaneously, even after heating, also can prevent the gathering of metallic, remain on the dispersity that obtains in the catalyst manufacturing thus, therefore obtain to have the catalyst of excellent heat resistance.In addition, because metallic is formed by noble metal, contact with the complex chemical compound of this noble metal with transition metal and carrier, obtain the catalytic action of transition metal in the complex chemical compound, the result can improve catalytic activity.

Make the method for catalyst

Secondly, the embodiment that is used to make the method for catalyst according to of the present invention is described.This method comprises: introducing and closed metal colloid are to form the sealing step of catalyst precarsor in precursor carrier, and this metallic colloid is by the metallic of protecting and being dispersed at its organic molecule that provides on every side in the decentralized medium; Calcining step with calcined catalyst precursor in oxidation environment.

In the method for this embodiment, make this catalyst by enclosure method.In this enclosure method, after the colloid that forms metallic, around metallic colloid, form the hydroxide of carrier metal, it is the precursor of carrier, this catalyst precarsor of calcining makes metallic to disperse and load in carrier in oxidation environment.In addition, because precursor carrier formation around metallic colloid, so metallic is partially submerged in the carrier.Therefore, can the fixing metal particle, the result can obtain to have the catalyst of high-fire resistance.As mentioned above, in the method for making catalyst, according to the present embodiment, can obtain catalyst, wherein metallic is partially submerged into wherein simultaneously by the area load of carrier.

In the present embodiment, as organic molecule, the preferred compound that uses with high stability, as PVP, polyvinyl alcohol, polyethylene imide, polyacrylic acid, oxalic acid, butanedioic acid and maleic acid, and composition thereof.In addition,, preferably make water, alcohol as methyl alcohol and ethanol, ester such as methyl acetate and ethyl acetate, ether such as diethyl ether as decentralized medium, and composition thereof.

When using above-mentioned organic molecule and decentralized medium to form catalyst precarsor, by the protective layer at metallic arranged around organic molecule, this metallic can evenly disperse in decentralized medium.In addition, can obtain the stability of colloidal solution, i.e. the inhibition of metallic precipitation.Therefore, can form and be in the catalyst precarsor that metallic is wherein introduced the state of precursor carrier equably.

In addition, when calcining in oxidation environment during this catalyst precarsor, water evaporates from the hydroxide for the carrier metal of precursor carrier, forms many holes thus after calcining in carrier, and therefore formation has the carrier of high-specific surface area.Subsequently, because the metallic of catalyst precarsor is introduced precursor carrier equably, therefore in the catalyst that is formed by calcining, metallic is equably by the area load that comprises the carrier inner surface.As mentioned above, even when the size of metallic colloid during greater than the hole dimension of carrier, metallic also can inner dipping and load in the hole.

In addition, by using above-mentioned carrying method, owing to around metallic, form the barrier of carrier, retention effect that can the acquired disturbance thing, the result can suppress the gathering of metallic.In addition, the formation that breaks the barriers, metallic is partially submerged in the carrier.In addition, when a part of barrier and transition metal formed complex chemical compound, the catalytic activity of transition metal was produced by noble metal, and the result increases the surface area of catalytic activity point, made the catalytic performance that can obtain excellence for a long time.

For obtaining above-mentioned effect, the colloidal particle of the preferred complex metal compound of metallic colloid, this complex metal compound comprise and are selected from least a noble metal in the group of being made up of Pt, Pd and Rh and are selected from least a transition metal in the group of being made up of Mn, Fe, Co, Ni, Cu and Zn.In these cases, owing to form particle, therefore can prepare wherein the catalysis material that around noble metal selectivity is arranged the complex chemical compound that comprises transition metal as the nuclear of metallic colloid from the compound of noble metal and transition metal.

Precursor carrier preferably includes the compound that is selected from least a element in the group of being made up of Al, Ti, Zr, Ce and La.Can be water-soluble inorganic salt with form, above every kind of element as nitrate or acetate at first adds in the aqueous solution of the colloidal particle that comprises the complex metal compound that is formed by noble metal and transition metal, add alkaline precipitating agent such as moisture ammonium or moisture tetramethyl-ammonium (TMAH) solution subsequently, to form hydroxide.Perhaps, alkoxide can be added aqueous colloidal solution around the colloidal particle of complex metal compound, to form hydroxide.In addition, when the polymer chain of the organic molecule that forms metallic colloid has imino group (NH) or its similar group separately, when having alkaline performance with colloidal solution, the mixed aqueous solution that comprises precipitating reagent and metallic colloid by adding is in the aqueous solution that comprises precursor carrier, and metallic colloid can be stably by carrier loaded.

More preferably noble metal is Pt, and transition metal is that Co and precursor carrier are the compounds that comprises Al.In the case, because transition metal such as Co are comprised as precursor carrier, thereby the transition metal that can suppress wherein to contact with noble metal is dissolved in the phenomenon of carrier material.

Fig. 2 is the flow chart that the step of first method of making this catalyst is described, Fig. 3 (A)-(D) is the explanatory diagram of explanation state of material during this technology.At first, organic molecule and at least a slaine are added in the decentralized medium, stir then, prepare mixed solution (Fig. 2 thus; Step 10).In this step, as slaine, can use the precious metal salt that comprises following material: precious metals complex such as dinitro two amine salt, three ammino salt, four ammino salt or six ammino salt, or inorganic salts such as nitrate, chloride or sulfate, as transition metal salt, can use acetate, nitrate or carbonate.In addition, as organic molecule, can use for example PVP, polyvinyl alcohol, polyethylene imide, polyacrylic acid, oxalic acid, butanedioic acid and maleic acid.In addition, can use and comprise at least wherein mixed solution of two kinds of materials.In the present embodiment, shown in Fig. 3 (A), in decentralized medium, there are metal ion 21 and organic molecule 22.

Then, reducing agent is added this solution so that with metal ion 21 reduction, therefore form the dispersing liquid of metallic colloid 23, in each, shown in Fig. 3 (B), organic molecule is coordination (Fig. 2 around the metallic 21a of so reduction at it; Step 11).In this step,, can use hydrazine, sodium borohydride or hydrogen as reducing agent.

After the carrier metal hydrate that will be precursor carrier adds in this solution and fully stirs, the precipitating reagent aqueous solution is splashed into this solution up to obtaining pH7.0, the solution that will obtain like this wears out a night then.In this step, shown in Fig. 3 (C), it is in the hydroxide 24 of precursor carrier that metallic colloid 23 is introduced it, therefore obtains sediment (Fig. 2 of catalyst precarsor 25; Step 12-seals step).The colloid 23a of metallic colloid 23 is partly introduced in the hydroxide 24, and other colloid 23b is introduced in the hydroxide 24 fully.In this step, the precursor of carrier can comprise water.In addition, as the precipitating reagent aqueous solution, can use moisture ammonium or moisture TMAH solution.

Then, after the filtration of using film filter, adopt massive laundering to wash (Fig. 2 the sediment that obtains like this; Step 13).In addition, with sediment dry one day (Fig. 2 under 120 ℃ temperature; Step 14).After drying, sediment is being calcined 1 hour (Fig. 2 under 400 ℃ in air stream; Step 15-calcining step), therefore obtain the catalyst 31 shown in Fig. 3 (D).

Because the catalyst 31 that obtains like this forms by calcined catalyst precursor 25, wherein metallic colloid 23 being introduced is in the hydroxide 24 of precursor carrier, and water is from hydroxide 24 evaporations, the result, and hydroxide 24 is shunk by dehydration.In this step, in carrier 32, form many holes, and the metallic colloid 23 of introducing hydroxide 24 becomes the outer surface that is partially submerged into carrier 32 and the metallic 33 of inner surface, this inner surface is in the hole of carrier 32.As mentioned above, metallic 33 is evenly dispersed on the carrier 32 and is fixed firmly on it.In addition, because carrier 32 as the maintenance thing of metallic 33, therefore suppresses the gathering of metallic, and can form catalyst 31 thus to have high catalytic activity and the high-specific surface area that improves catalytic performance.

In above-mentioned sealing step, the partial oxidation agent can be added metallic colloid wherein and be dispersed in the colloidal solution in the decentralized medium.This partial oxidation agent for example is, comprises the aqueous solution of oxidant such as hydrogen peroxide.The surface of the surface of this partial oxidation agent partial oxidation granulated metal or the complex metal compound of noble metal and transition metal, it metallizes once by using the reducing agent reduction.By this oxidation, granulated metal or complex metal compound are to being that the carrier metal hydrate of precursor carrier has improved affinity and can promote fixing by carrier loaded granulated metal or complex metal compound thus.Therefore, can control the rate that exposes to the open air of granulated metal or complex metal compound.

Only use therein that this effect is significant especially under the situation of noble metal.Because it is relatively stable that noble metal is compared with transition metal,, can not obtain the enough affinities between carrier and noble metal unless therefore carry out partial oxidation.Therefore, the control of the rate that exposes to the open air of noble metal becomes difficult.Yet, when being oxidized to predetermined ratio when the partial oxidation agent is added colloidal solution so that with the surface portion of noble metal, the part surface of oxidized noble metal has further improvement affinity to precursor carrier, and therefore the rate that exposes to the open air of noble metal is more controlled after calcining.As mentioned above, by regulating the partial oxidation dosage that drops into colloidal solution, can control the rate that exposes to the open air of the granulated metal or the complex metal compound of catalyst.

Fig. 4 illustrates according to another embodiment of the invention, the flow chart of the step of the method for manufacturing catalyst.Be after step 11, to add the aqueous solution of partial oxidation agent with the discrepancy of the flow chart shown in Fig. 2.At first, organic molecule and at least a slaine are added decentralized medium, stir then, prepare mixed solution (Fig. 4 thus; Step 40).In this step, as slaine, can use the precious metal salt that comprises following material: precious metals complex such as dinitro two amine salt, three ammino salt, four ammino salt or six ammino salt or inorganic salts such as nitrate, chloride or sulfate, as transition metal salt, can use acetate, nitrate or carbonate.In addition, as organic molecule, can use for example PVP, polyvinyl alcohol, polyethylene imide, polyacrylic acid, oxalic acid, butanedioic acid or maleic acid.In addition, can use and comprise the mixed solution of its two kinds of materials at least.In the present embodiment, in decentralized medium, there are metal ion and organic molecule.

Then, reducing agent added this solution so that the reducing metal ion, therefore form the dispersing liquid of metallic colloid, wherein, organic molecule is coordination (Fig. 4 around the metallic of reduction like this; Step 41).In this step,, can use hydrazine, sodium borohydride or hydrogen as reducing agent.

The aqueous solution with the partial oxidation agent adds in this solution then, so that with the metallic partial oxidation.As the partial oxidation agent, can use any compound, as long as it is the oxidant with performance of association oxygen atom and metallic, as hydrogen peroxide.After the carrier metal hydrate that will be precursor carrier adds this solution and fully stirs, the precipitating reagent aqueous solution is splashed into this solution up to obtaining pH7.0, the solution that will obtain like this wears out a night then.In this step, obtaining wherein metallic colloid to be introduced is the sediment of the catalyst precarsor in the hydroxide of precursor carrier, (Fig. 4; Step 42-seals step).Some colloids of metallic colloid are partly introduced in the hydroxide, other colloid is introduced in the hydroxide fully.In this step, the precursor of carrier can comprise water.In addition, as the precipitating reagent aqueous solution, can use moisture ammonium or moisture TMAH solution.

Then, after the filtration of using film filter, adopt massive laundering to wash (Fig. 4 the sediment that obtains like this; Step 43).In addition, with sediment dry one day (Fig. 4 under 120 ℃ temperature; Step 44).After drying, sediment is being calcined 1 hour (Fig. 4 under 400 ℃ in air stream; Step 45-calcining step), obtain catalyst thus.

Owing to the catalyst that obtains like this is the catalyst precarsor formation of the hydroxide of precursor carrier with the metallic colloid introducing wherein by calcining, water evaporates from hydroxide, the result, and hydroxide is shunk by dehydration.In this step, the metallic colloid that forms many holes and introduce hydroxide in carrier becomes the outer surface that is partially submerged into carrier and the metallic of inner surface, and inner surface is in the hole of carrier.As mentioned above, metallic is evenly dispersed on the carrier and is fixed firmly on it.In addition, because carrier as the maintenance thing of metallic, suppresses the gathering of metallic, and therefore can form and have the high catalytic activity that improves catalytic performance and the catalyst of high-specific surface area.

In addition, by using the partial oxidation agent, can control the rate that exposes to the open air of catalyst.Fig. 5 (A) is the part viewgraph of cross-section by the catalyst 51 of the partial oxidation agent manufacturing of using the reduction amount.In this catalyst 51, metallic 53 is partially submerged into wherein simultaneously by the area load of carrier 52.In the case, because the amount of partial oxidation agent is little, the rate that exposes to the open air the height of metallic 53 is also little around the amount of metallic 53 carrier 52 on every side.

Fig. 5 (B) is by to use the part viewgraph of cross-section of the catalyst 61 that the partial oxidation agent makes greater than the amount under the situation of catalyst 51.In this catalyst 61, metallic 63 makes about 50% of each particle imbed in the carrier 62 by the area load of carrier 62.

Fig. 5 (C) is by to use the part viewgraph of cross-section of the catalyst 71 that the partial oxidation agent makes with the above-mentioned amount of comparing further increase.In this catalyst 71, metallic 73 makes the major part of each particle imbed in the carrier 72 by the area load of carrier 72.In the case, because the amount of partial oxidation agent is big, so the rate that exposes to the open air of metallic 73 is low and big around the amount of the carrier of metallic 73.

Shown in Fig. 5 (A)-(C), by regulating the amount of part oxidant, can control the affinity of metallic to carrier, therefore can control the rate that exposes to the open air by carrier loaded metallic.

In addition, catalyst can be by using the inverse micelle method manufacturing, and the diameter of drop is below the 20nm in the method.Promptly, can carry out following manufacture method: the composition metal particle of precipitation noble metal or noble metal and transition metal in each reverse micelle adds the partial oxidation agent-adding step of partial oxidation agent and the step of being sealed noble metal or composition metal particle by catalyst precarsor subsequently in reverse micelle.When catalyst when manufacture method prepares thus,, can improve the affinity of precursor carrier to the composition metal particle of noble metal or noble metal and transition metal by the noble metal of partial oxidation in reverse micelle or the composition metal particle of noble metal and transition metal.In addition, as mentioned above,, can control the rate that exposes to the open air of the composition metal particle of noble metal or noble metal and transition metal by using the partial oxidation agent.

Fig. 6 is the flow chart of explanation according to the step of the method for another embodiment manufacturing catalyst according to the present invention.Be to use inverse micelle method to make catalyst with the discrepancy of the flow chart shown in Fig. 2 and 4.In Fig. 6,, use the composition metal particle of noble metal and transition metal as metallic.Fig. 7 (A)-(E) is the explanatory diagram of explanation state of material during this manufacturing process.

At first, preparation comprises organic solvent and the mixed solution (Fig. 6 that is dissolved in surfactant wherein; Step 80).In this step,, can use for example cyclohexane, cycloheptane, octanol, isooctane, n-hexane, n-decane, benzene, toluene or dimethylbenzene as organic solvent.In addition, also can use the mixed solution that comprises above-mentioned at least two kinds of solvents.As surfactant, can use for example polyethylene glycol (5) list-4-nonylplenyl ether, or five ethylidene glycol lauryl ethers.

When the mixed aqueous solution with precious metal salt and transition metal salt adds in the above mixed solution and stirs 2 hours, form the thin reverse micelle 90 shown in Fig. 7 (A).In reverse micelle 90, layout surface activating agent 91 make its hydrophilic radical and hydrophobic group lay respectively at spherical droplets by inboard and in the outer part, the diameter of this drop is approximately ten to tens nanometers, with aqueous phase, comprise the aqueous solution 92 (Fig. 6 that contain precious metal salt and transition metal salt in reverse micelle 90 inside; Step 81).In this step,, can use for example nitrate, acetate, chloride, amines, carbonyls and metal alkoxide as precious metal salt and transition metal salt.In addition, also can use the mixed solution that comprises above-mentioned at least two kinds of salt.

Then, the reducing agent that will be used for precious metal salt and transition metal salt adds the mixed solution of the organic solvent that comprises reverse micelle 90, and stirred 2 hours, make that shown in Fig. 7 (B) precious metal salt and transition metal salt pass through reduction metallization (Fig. 6 simultaneously in reverse micelle 90; Step 82).As reducing agent, can use for example ammonia, tetramethyl-ammonium, alkali metal hydroxide (as NaOH), hydrazine or sodium borohydride.

Subsequently, the aqueous solution of partial oxidation agent is added the mixed solution of the organic solvent that comprises reverse micelle, composition metal particle (Fig. 6 of partial oxidation noble metal and transition metal in reverse micelle; Step 83-Fig. 7 (C)).As the partial oxidation agent, as mentioned above, can use any compound, as long as it is the oxidant with performance of association oxygen atom and metallic, as hydrogen peroxide.

Then, the carrier metal aqueous solution was mixed together and stirs 2 hour, make the salt and the water retting of carrier metal are gone in the reverse micelle 90, this reverse micelle 90 comprises composition metal particle (Fig. 6 of the partial oxidation of noble metal 93 and transition metal 94; Step 84).In this step,, can use for example nitrate, chloride, acetate or amines as the salt of carrier metal.

Then, the mixed solution of the precipitating reagent aqueous solution with the organic solvent that comprises reverse micelle mixed, so that with the salt precipitation of the carrier metal of reverse micelle inside.In the case, shown in Fig. 7 (D), with the salt metallization of the carrier metal of reverse micelle 90 inside be precipitated as carrier metal 95, then by composition metal particle (Fig. 6 of carrier metal 95 sealing noble metals 93 and transition metal 94; Step 85).In this step,, for example can use hydrazine, sodium borohydride or ammonium as precipitating reagent.As selection, also can use the mixed solution that comprises above-mentioned at least two kinds of reagent.

Subsequently, alcohol is added the mixed solution of the organic solvent comprise reverse micelle and stir 2 hours to allow the reverse micelle (Fig. 6 that caves in; Step 86).By caving in of reverse micelle, shown in Fig. 7 (E), can obtain the sediment of the composition metal particle of noble metal 93 and transition metal 94, this composition metal particle is by carrier metal 95 sealings.In this step,, can use for example methyl alcohol or ethanol as alcohol.

Then, after using the film filter filtration, adopt the alcohol and water washing so that remove impurity (as the surfactant) (Fig. 6 that in sediment, comprises the sediment that obtains like this; Step 87).In addition, with sediment dry one day (Fig. 6 under 120 ℃ temperature; Step 88).After drying, sediment is being calcined 1 hour (Fig. 6 under 400 ℃ in air stream; Step 89), therefore obtain catalyst 96.In this catalyst 96, the compound particle 98 of noble metal and transition metal by the area load of carrier to be partially submerged in the carrier body 97.

In the case, preferred noble metal is at least a noble metal that is selected from the group of being made up of Pt, Pd and Rh, transition metal is that at least a transition metal and the precursor carrier that are selected from the group of being made up of Mn, Fe, Co, Ni, Cu and Zn are at least a compounds that comprises among Al, Ti, Zr, Ce and the La.

As mentioned above, using inverse micelle method to make in the method for catalyst equally, owing to form precursor carrier around metallic, metallic is partially submerged in the carrier.Therefore, can the fixing metal particle, the result can obtain to have the catalyst of high-fire resistance.As mentioned above, by method, can obtain metallic wherein and be partially submerged into wherein catalyst simultaneously by the area load of carrier according to the manufacturing catalyst of the present embodiment.

In the method according to the manufacturing catalyst of this embodiment, the catalytic activity of catalyst changes according to type service condition of element etc.Therefore, for obtaining required catalytic activity, can suitably change type, reaction temperature, reaction time, stirring intensity and the stirring means of element, reducing agent and precipitating reagent.

Embodiment 1 to 11, reference example 1 and Comparative Examples 1

Below, with reference example 1 to 11, reference example 1 and Comparative Examples 1 more detailed description catalyst of the present invention.Yet, the invention is not restricted to these embodiment.Carry out embodiment and be used to study the effect of catalyst of the present invention, and in an embodiment, show from the catalyst of various different materials preparations by embodiment.

Embodiment 1

In embodiment 1, use enclosure method by the precious metals pt of alumina load as metallic.At first, in mixing ratio is the mixed solution of 1: 1 water and ethanol, add the 55mmol PVP and 1.54mmol dinitro diamines closes platinum, stir (Fig. 2 then; Step 10).Then, hydrazine is added this solution be used to reduce the Pt compound, obtain to have dispersing liquid (Fig. 2 of the Pt fine particle of average grain diameter 2.1nm thus; Step 11).In this dispersing liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH (tetramethyl ammonium hydroxide) solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopting the washing of big water gaging to repeat processing (Fig. 2; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, form catalyst fines (Fig. 2 thus; Step 15).The Pt concentration of the catalyst of Huo Deing is 0.3wt% like this.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 3.3nm.

Embodiment 2

In embodiment 2, use enclosure method by the precious metals pd of zirconia load as metallic.At first, in mixing ratio is the mixed solution of 1: 1 water and ethanol, add 55mmol PVP and 2.82mmol palladium nitrate, stir (Fig. 2 then; Step 10).Hydrazine is added this solution be used to reduce the Pd compound, obtain to have dispersing liquid (Fig. 2 of the Pd fine particle of average grain diameter 3.3nm thus; Step 11).In this dispersing liquid, add 216.9g two nitric hydrate zirconiums and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, form catalyst fines (Fig. 2 thus; Step 15).The Pd concentration of the catalyst of Huo Deing is 0.3wt% like this.In addition, the average grain diameter of the Pd of the catalyst that obtains like this is 3.8nm.

Embodiment 3

In embodiment 3, use enclosure method by the noble metal Rh of titanium dichloride load as metallic.At first, in mixing ratio is the mixed solution of 1: 1 water and ethanol, add 55mmol PVP and 2.92mmol rhodium nitrate, stir (Fig. 2 then; Step 10).Hydrazine is added this solution be used to reduce the Rh compound, obtain to have dispersing liquid (Fig. 2 of the Rh fine particle of average grain diameter 1.0nm thus; Step 11).In this dispersing liquid, add have the drying solid component be 5% 2, the 000g ammonium oxalate titanium aqueous solution, and fully stirring splashes into concentration as precipitating reagent and is 15% TMAH solution then up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, form catalyst fines (Fig. 2 thus; Step 15).The Rh concentration of the catalyst of Huo Deing is 0.3wt% like this.In addition, the average grain diameter of the Rh of the catalyst that obtains like this is 1.6nm.

Embodiment 4

In embodiment 4, use enclosure method by the precious metals pt and the transition metal Co of alumina load as metallic.At first, add the 55mmol PVP in mixing ratio is the mixed solution of 1: 1 water and ethanol, 1.54mmol dinitro diamines closes platinum and 25.5mmol cobalt nitrate, stirs (Fig. 2 then; Step 10).Hydrazine is added this solution be used to reduce Pt and Co compound, obtain to have dispersing liquid (Fig. 2 of the Pt-Co mixing fine particle of average grain diameter 3.2nm thus; Step 11).In this dispersing liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, therefore form catalyst fines (Fig. 2; Step 15).The Pt load concentration of the catalyst of Huo Deing is that the concentration of 0.3wt% and Co is 1.5wt% like this.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 3.3nm.In addition, Co and aluminium oxide are compound to form cobalt aluminate.

Embodiment 5

In embodiment 5, use enclosure method by the precious metals pd and the transition metal Ni of alumina load as metallic.At first, add the 55mmol PVP in mixing ratio is the mixed solution of 1: 1 water and ethanol, 2.82mmol palladium nitrate and 25.5mmol nickel nitrate stir (Fig. 2 then; Step 10).Hydrazine is added this solution be used to reduce Pd and Ni compound, obtain to have dispersing liquid (Fig. 2 of the Pd-Ni mixing fine particle of average grain diameter 3.8nm thus; Step 11).Then, in this dispersing liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, therefore form catalyst fines (Fig. 2; Step 15).The Pd concentration of the catalyst of Huo Deing is 0.3wt% like this, and the load concentration of Ni is 1.5wt%.In addition, the average grain diameter of the Pd of the catalyst that obtains like this is 4.6nm.In addition, Ni and aluminium oxide are compound to form nickel aluminate.

Embodiment 6

In embodiment 6, use enclosure method by the precious metals pt and the transition-metal Fe of alumina load as metallic.At first, add the 55mmol PVP in mixing ratio is the mixed solution of 1: 1 water and ethanol, 1.54mmol dinitro diamines closes platinum and 26.9mmol ferric nitrate, stirs (Fig. 2 then; Step 10).Then, hydrazine is added this solution be used to reduce Pt and Fe compound, obtain to have dispersing liquid (Fig. 2 of the Pt-Fe mixing fine particle of average grain diameter 3.6nm thus; Step 11).In this dispersing liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, therefore form catalyst fines (Fig. 2; Step 15).The Pt concentration of the catalyst of Huo Deing is 0.3wt% like this, and the load concentration of Fe is 1.5wt%.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 4.2nm.In addition, Fe and aluminium oxide are compound to form iron aluminate could.

Embodiment 7

In embodiment 7, use enclosure method by the precious metals pt and the transient metal Mn of alumina load as metallic.At first, add the 55mmol PVP in mixing ratio is the mixed solution of 1: 1 water and ethanol, 1.5 4mmol dinitro diamines close platinum and 27.3mmol manganese nitrate, stir (Fig. 2 then; Step 10).Hydrazine is added this solution be used to reduce Pt and Mn compound, obtain to have dispersing liquid (Fig. 2 of the Pt-Mn mixing fine particle of average grain diameter 3.0nm thus; Step 11).Then, in this dispersing liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 2; Step 12).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 2 of big water gaging; Step 13); Subsequently at 120 ℃ of down dry one day (Fig. 2; Step 14).Subsequently, under 400 ℃, calcined 1 hour, form catalyst fines (Fig. 2 thus; Step 15).The Pt concentration of the catalyst of Huo Deing is 0.3wt% like this, and the load concentration of Mn is 1.5wt%.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 3.4nm.In addition, Mn and aluminium oxide are compound to form manganese aluminate.

Embodiment 8

In embodiment 8, obtain the catalyst fines of embodiment 8 in the mode identical with embodiment 1, difference is to carry out this technology to obtain the Pt load concentration of 1wt%.The average grain diameter of the Pt of the catalyst of Huo Deing is 3.5nm like this.

Embodiment 9

In embodiment 9, obtain the catalyst fines of embodiment 9 in the mode identical with embodiment 1, difference is to carry out this technology to obtain the Pt load concentration of 3wt%.The average grain diameter of the Pt of the catalyst of Huo Deing is 5.2nm like this.

Embodiment 10

In embodiment 10, use the oxidation of enclosure method bound fraction by the precious metals pt and the transition metal Co of alumina load as metallic.At first, add the 55mmol PVP in mixing ratio is the mixed solution of 1: 1 water and ethanol, 1.54mmol dinitro diamines closes platinum and 25.5mmol cobalt nitrate, stirs (Fig. 4 then; Step 40).Hydrazine is added this solution be used to reduce Pt and Co compound, obtain to have dispersing liquid (Fig. 4 of the Pt-Co mixing fine particle of average grain diameter 3.2nm thus; Step 41).Then, in this dispersing liquid, adding concentration is 1% aqueous hydrogen peroxide solution, and it is equal to 1.62mmol H ₂O ₂, make Pt-Co mixing fine particle process by surface treatment.Subsequently, in this liquid, add the 735.8g ANN aluminium nitrate nonahydrate and fully stir, splash into concentration as precipitating reagent then and be 15% TMAH solution up to obtaining pH7.0 (Fig. 4; Step 42).After an aging night, with the liquid that obtains like this by filtering and adopt washing reprocessing (Fig. 4 of big water gaging; Step 43); Subsequently at 120 ℃ of down dry one day (Fig. 4; Step 44).Subsequently, under 400 ℃, calcined 1 hour, by therefore forming catalyst fines (Fig. 4; Step 45).The Pt concentration of the catalyst of Huo Deing is that the load concentration of 0.3wt% and Co is 1.5wt% like this.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 4.0nm.In addition, Co and Al ₂O ₃Compound to form cobalt aluminate.

Embodiment 11

In embodiment 11, use inverse micelle method by the precious metals pt and the transition metal Co of alumina load as metallic.At first, prepare 1,000ml, is blended together to form mixed solution as polyethylene glycol (5) list-4-nonylplenyl ether of surfactant then as the cyclohexane of organic solvent and 66g, stir subsequently (surfactant/organic solvent (molar percentage/L)=0.15) (Fig. 6; Step 80).Then, in the mixed solution of such preparation, add 0.037g closes platinum as the dinitro diamines of noble metal aqueous solution of nitric acid (the Pt concentration of 8.46wt%), 0.09g cabaltous nitrate hexahydrate as transition metal, with the water of 7.95ml through purifying, stirred subsequently 2 hours, so that preparation comprises inverse micellar solution (Fig. 6 of Pt ion and Co ion in reverse micelle; Step 81).After stirring, in the Pt-Co inverse micellar solution, add hydrazine and further stir other 2 hour of 0.065g as reducing agent, obtain the composite superfine dispersion of nano-particles liquid (Fig. 6 that forms by metallization Pt-Co thus; Step 82).Then, in this dispersing liquid, add aqueous hydrogen peroxide solution as the partial oxidation agent aqueous solution carrying out the surface treatment of Pt-Co compound particle, so noble metal in the partial oxidation reverse micelle and transition metal.As the carrier metal precursor, the mixed solution that preparation is made up of 2.0g aluminium isopropoxide and 20ml cyclohexane drips in the dispersing liquid then, stirs subsequently about 2 hours.Therefore, in this reverse micelle, by aluminium hydroxide sealing Pt-Co ultrafine particle (Fig. 6; Step 84).In this mixing material, add 122.6ml methyl alcohol and make and allow the reverse micelle (Fig. 6 that caves in; Step 86), after stirring about 2 hours, filters, so remove and desolvate, the precipitation that so obtains is washed with ethanol, to remove remaining surfactant (Fig. 6; Step 87).With sediment dry 12 hours (Fig. 6 under 120 ℃; Step 88), in calcining in air stream under 400 ℃, therefore obtain catalyst fines (Fig. 6 then; Step 89).About the catalyst of such acquisition with respect to 1g Al ₂O ₃Concentration, Pt is 0.3wt%, Co is 1.5wt%.In addition, the particle diameter of the Pt of the powder that obtains like this is 3.5nm.In addition, Co and Al ₂O ₃Compound to form cobalt aluminate.

Reference example 1

In reference example 1, obtain the catalyst fines of reference example 1 in the mode identical with embodiment 1, difference is to carry out this technology to obtain the Pt concentration of 0.1wt%.The average grain diameter of Pt is 2.6nm in catalyst.

Comparative Examples 1

In Comparative Examples 1, use dipping method to make catalyst.At first, be that 200m2/g and average pore size are that the alumina load dinitro diamines of 20nm closes platinum having the concentration of 0.3wt% by the 100g specific area, at 120 ℃ down after dry one day, under 400 ℃, calcined 1 hour.The concentration of the Pt of the catalyst of Huo Deing is 0.3wt% like this.In addition, the average grain diameter of the Pt of the catalyst that obtains like this is 3.1nm.

In the above-described embodiments, the sample of so preparation in calcining 3 hours in air stream under 700 ℃, for the embodiment of such processing, is carried out measuring by the grain diameter measurement of TEM (transmission electron microscope(TEM)) with by the rate that exposes to the open air of CO absorption.

The grain diameter measurement of metallic

Carrying out TEM-EDX for the catalyst by above-mentioned catalyst for preparing and acquisition after secondary clacining measures.For measurement, use the HF-2000 that makes by Hitachi Ltd., measurement carries out under the accelerating potential of 200kV and the cutting condition is at room temperature.As for measuring method, use epoxy resin to be used for the processing of sealing of catalyst fines, after cured epoxy resin, form ultra-thin section by ultramicrotomy.By using the section of such acquisition, measure the dispersity of various crystal particles by transmission electron microscope(TEM) (TEM).In the image that therefore obtains, focus on contrast (shade) part with the type of identification metal with measure its particle diameter.

The measurement of the CO of unit adsorbance

For obtaining to expose to the open air rate, the CO of measurement unit adsorbance.For the measurement of the CO of unit adsorbance, by using the measurement device of metal dispersion, by BEL Japan, the BEL-M ETAL-3 that Inc. makes carries out following process.The He gas of sample being put into 100% concentration flows, and is heated to 400 ℃ with the speed of 10 ℃/min, then by oxidation processes O in 100% concentration under 400 ℃ ₂Processing is 15 minutes in the gas stream.Subsequently, use the He gas of 100% concentration to purify 5 minutes, then under 400 ℃ at 40%H ₂Handled 15 minutes with reducing in the mixture of surplus He gas.Then, in the He of 100% concentration gas stream, temperature is reduced to 50 ℃.Subsequently, measure by the mixture of sending into 10%CO and surplus He gas with pulse mode.

Shown in the following table 1 from embodiment 1 to 11, the noble metal that obtains in each sample of reference example 1 and Comparative Examples 1 and the load concentration of transition metal, the particle diameter of noble metal (nm), the particle diameter (nm) of noble metal and expose rate to the open air after hear resistance test.

Table 1

	Noble metal		Transition metal		Manufacture method	Carrier	The particle diameter (nm) of noble metal after preparation	Calcine the particle diameter (nm) of noble metal afterwards down at 700 ℃	Expose rate (%) to the open air
										Type	Concentration (%)	Type	Concentration (%)
	Embodiment 1	Pt	0.3	-										0	Sealing	Al 2O 3	3.3	11.9	72
Embodiment 2					Pd	0.3	-	0	Sealing	ZrO 2	3.8	12.7	75
	Embodiment 3	Rh	0.3	-										0	Sealing	TiO 2	1.6	8.9	67
Embodiment 4					Pt	0.3	Co	1.5	Sealing	Al 2O 3	3.9	14.1	68
	Embodiment 5	Pd	0.3	Ni										1.5	Sealing	Al 2O 3	4.6	15.4	62
Embodiment 6					Pt	0.3	Fe	1.5	Sealing	Al 2O 3	4.2	19.6	51
	Embodiment 7	Pt	0.3	Mn										1.5	Sealing	Al 2O 3	3.4	11.4	60
Embodiment 8					Pt	1.0	-	0	Sealing	Al 2O 3	3.5	15.6	77
	Embodiment 9	Pt	3.0	-										0	Sealing	Al 2O 3	5.2	23.9	83
Embodiment 10					Pt	0.3	Co	1.5	Sealing	Al 2O 3	4.0	9.8	58
	Embodiment 11	Pt	0.3	Co										1.5	Sealing	Al 2O 3	3.5	13.2	85
Reference example 1					Pt	0.1	-	0	Sealing	Al 2O 3	2.6	5.6	32
	Comparative Examples 1	Pt	0.3	-										0	Dipping	Al 2O 3	3.1	22.6	89

From by using TEM-EDX to measure the result who obtains, in each sample, 700 ℃ down the particle diameter after the calcining 3 hours approximately be about 4 times of particle diameter of acquisition before calcining.On the other hand, when the catalyst that obtains in the calcining Comparative Examples 1, its particle diameter is not less than 7 times of the grain warp that obtains before the calcining.As mentioned above, find when the rate that exposes to the open air greater than 85% the time, particle is owing to cause that by heating its gathering grows, when the rate of exposing to the open air is 50% to 85%, by the growth of retention effect inhibition particle.In addition, as shown in the reference example 1, when the rate that exposes to the open air less than 50% the time, further suppress the particle growth.Yet as described later, cross when low when the rate of exposing to the open air, reduce purifying rate, the result is as the function deterioration of catalyst.In addition,, find when the colloidal particle that uses the complex metal compound that is formed by noble metal and transition metal is made catalyst as by shown in the result of embodiment 4-7, from transition metal Co, Ni, the effect that Fe and Mn obtain roughly is equal to each other.In addition, use the partial oxidation agent to make among the embodiment 10 and 11 of catalyst therein, find as the growth of the inhibition of the situation in embodiment 4 particle.

As mentioned above; method according to the catalyst that is used to make embodiment of the present invention; because having, the method for manufacturing catalyst in precursor carrier, introduces metallic colloid to form the step of catalyst precarsor; metallic colloid is protected by the organic molecule around it and is disperseed in decentralized medium; with calcined catalyst precursor in oxidation environment, can obtain metallic wherein and be partially submerged into catalyst in the carrier simultaneously by the carrier surface load.Therefore, even after calcining, owing to can suppress the gathering of metallic, therefore can remain on and make the dispersity that obtains in this catalyst, the result can obtain to have the catalyst of excellent heat resistance.

Exhaust gas purifying catalyst

The embodiment of exhaust gas purifying catalyst of the present invention then, is described.The exhaust gas purifying catalyst of this embodiment has the Catalytic Layer from above-mentioned Preparation of Catalyst, and this layer applies on the wall surface of honeycomb substrate or its analog.In the case, the amount of metallic is preferably below every liter of exhaust gas purifying catalyst 0.72g.When this noble metal as in the past originally bravely is every liter of exhaust gas purifying catalyst 0.72g when following, can not obtain enough catalyst activities.Yet, as mentioned above, because metallic is partially submerged in the carrier by the carrier surface load simultaneously, this metallic is made up of noble metal, this noble metal contacts with the complex chemical compound of transition metal and carrier, because retention effect and complex chemical compound are used to improve the effect of the catalytic activity of noble metal, even when the amount of reduction noble metal, can obtain enough catalytic activitys.

Embodiment 12 to 15, reference example 2 and Comparative Examples 2 to 4

Below, with reference example 12 to 15, reference example 2 and Comparative Examples 2 to 4 more detailed descriptions exhaust gas purifying catalyst of the present invention.Yet, the invention is not restricted to these embodiment.For the effectiveness of studying exhaust gas purifying catalyst of the present invention is carried out embodiment, in an embodiment, show from the catalyst of various different materials preparations by embodiment.

Embodiment 12

Will amount be the catalyst fines that obtains in embodiment 1 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, therefore obtains catalyst pulp.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In the case, " the little number of chambers " indication cell number (an inch is about 2.54cm) per square inch, the wall thickness of " mil " demonstrative definition cell (mil is a mil).In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 110g and every liter of catalyst is 0.30g.

Embodiment 13

Will amount be the catalyst fines that obtains in embodiment 4 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 110g and every liter of catalyst is 0.30g.

Embodiment 14

Will amount be the catalyst fines that obtains in embodiment 8 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 80g and every liter of catalyst is 0.72g.

Embodiment 15

Will amount be the catalyst fines that obtains in embodiment 9 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 110g and every liter of catalyst is 2.97g.

Reference example 2

Will amount be the catalyst fines that obtains in reference example 1 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 310g and every liter of catalyst is 0.10g.

Comparative Examples 2

Will amount be the catalyst fines that obtains in Comparative Examples 1 of 50g, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 110g and every liter of catalyst is 0.3g.

Comparative Examples 3

In Comparative Examples 3, the catalyst-coated that will be made by dipping method is on the honeycomb ceramics of supported catalyst.At first, load on by 100g and have 200m the dinitro diamines being closed platinum ²To have the concentration of 1.0wt%, under 120 ℃, after dry one day, under 400 ℃, calcined 1 hour then on the aluminium oxide of/g specific area and 20nm average pore diameter, obtain catalyst fines thus.The load concentration of the Pt of the catalyst of Huo Deing is 1.0wt% like this.Then, with the catalyst fines that 50g obtains like this, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 85g and every liter of catalyst is 0.72g.

Comparative Examples 4

In Comparative Examples 4, the catalyst-coated that will be made by dipping method is on the honeycomb ceramics of supported catalyst.At first, load on 100g and have 200m the dinitro diamines being closed platinum ²To have the concentration of 3.0wt%, descended dry one day at 120 ℃ then on the aluminium oxide of/g specific area and 20nm average pore diameter, under 400 ℃, calcined 1 hour, obtain catalyst fines thus.The load concentration of the Pt of the catalyst of Huo Deing is 1.0wt% like this.Then, with the catalyst fines that 50g obtains like this, it is that the aqueous solution of 10% nitric acid is introduced alumina container and pulverized by the vibration of adopting alumina balls that 5g boehmite, 157g comprise concentration, obtains catalyst pulp thus.Then, the catalyst pulp that obtains like this is applied to the cordierite honeycomb carrier (400 cell/6 mils) with 0.0595 liter of volume, in air stream, remove the excess slurry in the cell, under 120 ℃, carry out drying, in air stream, calcining under 400 ℃ then.In this embodiment, the catalytic amount that applies on the honeycomb ceramics of the supported catalyst that obtains like this is that the Pt amount of every liter of catalyst 110g and every liter of catalyst is 2.97g.

By following method evaluation by the above-mentioned sample for preparing.

The hot test of catalyst tolerates

Estimated in 1 hour by in oxygen atmosphere, calcining the catalyst fines that obtains down at 700 ℃.

The evaluating catalyst test

A preparation part by the catalyst carrier of above heat treatment process so that after obtaining to have the catalyst of 40ml volume, carry out evaluating catalyst.The flow velocity of reacting gas is set to 40 liters/minute, the reacting gas temperature is set to 350 ℃ and set reacting gas and form so that be equal to each other from stoichiometric viewpoint in the amount of the oxygen shown in the table 2 and the amount of reducing agent.

Table 2

Reactant gas components
		Form	Concentration
NO	1000ppm
		CO	0.60％

H 2	0.20％
		O 2	0.60％
CO 2	13.90％
		C 3H 6	1665ppm
H 2O	1665ppm
		N 2	Surplus

Then, obtain NO according to following formula 4 _xPurifying rate and from thus obtained numerical value, evaluation of catalyst activity:

In following table 3, show from the foregoing description 12 to 15, reference example 2 and the noble metal of Comparative Examples 2 to 4 acquisitions and the load concentration of transition metal, and NO _xPurifying rate.

Table 3

	Noble metal		Transition metal		Manufacture method	Carrier	NO xPurifying rate (%)
								Type	Amount (g/L)	Type	Load concentration (%)
	Embodiment 12	Pt	0.30	-								0	Sealing	Al 2O 3	66
Embodiment 13					Pt	0.30	Co	1.5	Sealing	Al 2O 3	72
	Embodiment 14	Pt	0.72	-								0	Sealing	Al 2O 3	78
Embodiment 15					Pt	2.97	-	0	Sealing	Al 2O 3	91
	Reference example 2	Pt	0.10	-								0	Sealing	Al 2O 3	51
Comparative Examples 2					Pt	0.30	-	0	Dipping	Al 2O 3	39
	Comparative Examples 3	Pt	0.72	-								0	Dipping	Al 2O 3	72
Comparative Examples 4					Pt	2.97	-	0	Dipping	Al 2O 3	86

Embodiment 12,13, the NO of 14 and 15 exhaust gas purifying catalyst _xPurifying rate is respectively 66%, 72%, 78% and 91%, Comparative Examples 2,3, the NO of 4 exhaust gas purifying catalyst _xPurifying rate is respectively 39%, 72% and 86%.In addition, the NO of the exhaust gas purifying catalyst of reference example 2 _xPurifying rate is 51%.Fig. 8 shows the exhaust gas purifying catalyst that obtained by enclosure method and the amount at Pt (g/L) of the exhaust gas purifying catalyst that obtained by dipping method and the relation between the purifying rate (%).

Reference numeral A in Fig. 8 is presented at the NO of embodiment 15 and Comparative Examples 4 under the Pt amount of 2.97g/L _xPurifying rate (%).When being compared to each other by two values at the some place that is represented by Reference numeral A shown in Fig. 8, it is higher wherein to form the purifying rate of embodiment 15 of exhaust gas purifying catalyst by enclosure method.In addition, the Reference numeral B among Fig. 8 is presented at the following embodiment 14 of Pt amount of 0.72g/L and the NO of Comparative Examples 3 _xConversion ratio (%).When two values being compared to each other by the some place that represents at the Reference numeral B shown in Fig. 8, it is higher equally wherein to form the purifying rate of embodiment 14 of exhaust gas purifying catalyst by enclosure method.

The Pt that reference number C among Fig. 8 is presented at 0.30g/L measures embodiment 12 down, wherein comprises the embodiment 13 of Co and the NO of Comparative Examples 4 _xConversion ratio (%).At point, forms the embodiment 12 of exhaust gas purifying catalyst and 13 purifying rate the both by enclosure method and be significantly higher than purifying rate by the catalyst of dipping method manufacturing by reference number C shown in Fig. 8 indication.In addition, find to compare, comprise therein among the embodiment 13 of Co and obtain high purifying rate and improved catalyst activity with the embodiment 12 that does not wherein comprise Co.

As mentioned above, when the amount of Pt during, can obtain significant effect by using enclosure method to make exhaust gas purifying catalyst less than 0.72g/L.In addition, according to the result who is displayed in Table 3, find when making, can obtain to have the catalyst of excellent heat resistance by enclosure method.

According to the result of such acquisition, discovery can obtain to have the catalyst of excellent heat resistance when the amount of noble metal therein is when making exhaust gas purifying catalyst by enclosure method in the zone below the 0.72g/L.In addition, when further comprising transition metal,, also can obtain enough catalyst activities although the amount of noble metal reduces.

Claims (13)

1. catalyst, it comprises: by the metallic of carrier surface load, wherein metallic is partially submerged in the carrier.

2. catalyst according to claim 1, wherein the rate that exposes to the open air of the metallic that is obtained by following formula is 50% to 85%:

Wherein,

A is the CO adsorbance (cm on the metallic ³/ g),

B is the cross-sectional area (nm of an atom of the noble metal of load ²),

C is the density (g/cm of the noble metal of load ³),

D is the particle radii (nm) of the noble metal of load, and it is estimated by tem observation,

E be load noble metal each atomic adsorption the CO molecular number stoichiometric ratio and

F is the precious metal concentration (wt%/g) in this catalyst.

3. catalyst according to claim 2, wherein to have particle diameter be about 1nm to 10nm to this metallic.

4. catalyst according to claim 1, wherein this metallic comprises at least a noble metal that is selected from the group of being made up of Pt, Pd and Rh.

5. catalyst according to claim 4, it further comprises at least a transition metal that is selected from the group of being made up of Mn, Fe, Co, Ni, Cu and Zn, it contacts with the carrier both with noble metal, and wherein this transition metal of at least a portion forms complex chemical compound with carrier.

6. catalyst according to claim 1, wherein this carrier comprises at least a element that is selected from the group of being made up of Al, Ti, Zr, Ce and La.

7. method of making catalyst, it comprises:

Introducing and closed metal colloid are to form the sealing step of catalyst precarsor in precursor carrier, and this metallic colloid is by the metallic of organic molecule protection that provides around it and is dispersed in the decentralized medium; With

Calcined catalyst precursor in oxidation environment.

8. method according to claim 7 wherein in this sealing step, adds the partial oxidation agent in the colloidal solution that wherein this metallic colloid disperses in this decentralized medium.

9. method according to claim 7, wherein:

This metallic colloid is to comprise the colloidal particle that is selected from least a noble metal in the group of being made up of Pt, Pd and Rh and is selected from the complex metal compound of at least a transition metal in the group of being made up of Mn, Fe, Co, Ni, Cu and Zn; With

This precursor carrier is to comprise the compound that is selected from least a element in the group of being made up of Al, Ti, Zr, Ce and La.

One kind to use liquid-drop diameter wherein be the method that the inverse micelle method below the 20nm is made catalyst, this method comprises:

With noble metal or comprise noble metal and after the composition metal particle of transition metal precipitates, in reverse micelle, introduce the partial oxidation agent in reverse micelle; With

In reverse micelle, adopt precursor carrier sealing noble metal or composition metal particle.

11. method according to claim 10, wherein:

This noble metal is at least a noble metal that is selected from the group of being made up of Pt, Pd and Rh;

This transition metal is at least a transition metal that is selected from the group of being made up of Mn, Fe, Co, Ni, Cu and Zn; With

This precursor carrier is to comprise the compound that is selected from least a element in the group of being made up of Al, Ti, Zr, Ce and La.

12. an exhaust gas purifying catalyst that comprises catalyst layer, this catalyst layer comprises catalyst according to claim 1.

13. exhaust gas purifying catalyst according to claim 12, wherein the amount of this metallic is below every liter of Catalytic Layer 0.72g.

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