WO2016117240A1

WO2016117240A1 - Carrier for exhaust gas purifying catalysts, and exhaust gas purifying catalyst

Info

Publication number: WO2016117240A1
Application number: PCT/JP2015/084938
Authority: WO
Inventors: 純雄加藤; 正剛小笠原; 大典岩倉; 貴仁浅沼; 若林　誉; 中原　祐之輔
Original assignee: 三井金属鉱業株式会社
Priority date: 2015-01-19
Filing date: 2015-12-14
Publication date: 2016-07-28

Abstract

Provided is a novel carrier for exhaust gas purifying catalysts, which exhibits excellent catalytic activity, especially excellent catalytic activity at low temperatures. Proposed is a carrier for exhaust gas purifying catalysts, which is composed of particles containing a silicate or phosphate that contains one or more elements selected from among group 1 and group 2 elements of the periodic table.

Description

Carrier for exhaust gas purification catalyst and exhaust gas purification catalyst

The present invention relates to an exhaust gas purification catalyst that can be used to purify exhaust gas discharged from an internal combustion engine such as a gasoline engine such as a two-wheeled or four-wheeled vehicle or a diesel engine, and a carrier for the exhaust gas purification catalyst used therefor.

The exhaust gas from gasoline-fueled vehicles contains harmful components such as hydrocarbons (THC), carbon monoxide (CO), and nitrogen oxides (NOx). Therefore, the hydrocarbon (THC) is oxidized to be converted to water and carbon dioxide, the carbon monoxide (CO) is oxidized to be converted to carbon dioxide, and the nitrogen oxide (NOx) is reduced to be nitrogen In order to convert, it is necessary to purify each harmful component.

As a catalyst for treating such exhaust gas (hereinafter referred to as “exhaust gas purification catalyst”), a three-way catalyst (Three way catalysts: TWC) capable of oxidizing and reducing CO, THC and NOx is used. There is.
As such a three-way catalyst, a noble metal is supported on an oxide porous body having a high specific surface area, such as an alumina porous body having a high specific surface area, and this is used as a base material such as a refractory ceramic or a honeycomb structure made of metal. Are known to be supported on a monolithic substrate made of aluminum or supported on refractory particles.

On the other hand, in addition to the above-mentioned CO, THC, and NOx, the exhaust gas emitted from diesel engines includes sulfate based on the sulfur content in the fuel and tar-like particulate matter (“PM”) derived from incomplete combustion. And so on are included.
A diesel oxidation catalyst (referred to as "DOC") is known as a device for removing CO and THC contained in exhaust gas of a diesel engine.
As DOC, it is known that a porous filter base material exhibiting a honeycomb structure is coated with a refractory inorganic porous material such as zeolite or Al ₂ O ₃ .

Either a catalyst for purifying exhaust gas emitted from a gasoline engine or a catalyst for purifying exhaust gas emitted from a diesel engine, any of the catalysts can be platinum (Pt) or palladium (p Noble metals such as Pd) and rhodium (Rh) have often been used as catalytically active components. Also, since the bonding strength between the noble metal as the catalytically active component and the substrate is not so strong, and the specific surface area of the substrate itself is not so large, a sufficient amount of supported noble metal can be directly supported on the substrate It is difficult to carry it with high dispersion. Therefore, in order to load a sufficient amount of catalytically active components in a highly dispersed manner on the surface of a substrate, it has been practiced to load a noble metal on a particulate catalyst support having a high specific surface area.

As a carrier for this kind of exhaust gas purification catalyst (also referred to as "catalyst carrier" or "carrier"), porous particles composed of a refractory inorganic oxide such as silica, alumina, or a titania compound are known. Among them, from the viewpoint of being excellent in purification performance at low temperature, conventionally, a catalyst obtained by supporting a noble metal in a highly dispersed manner on an inorganic porous material such as alumina having a high specific surface area has been widely used.

With regard to the catalyst carrier, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 6-218282 (Kurosaki Kogyo Co., Ltd.)), it is a heat-resistant catalyst carrier substantially consisting of alumina, which is SiO ₂ , CaO, SrO, BaO, La. A heat resistant catalyst support is disclosed having a coating layer of one or more oxides selected from ₂ O ₃ .

Patent Document 2 (Japanese Patent Application Laid-Open No. 2000-157865 (Toyota Motor Corporation)) is a complex oxide carrier mainly composed of TiO ₂ -Al ₂ O ₃ and contains Si, which is the above-mentioned TiO. Disclosed is a composite oxide support characterized in that it comprises a composite oxide with at least one of ₂ and Al ₂ O ₃ .

Patent Document 3 (Japanese Patent Laid-Open No. 2007-144393 (Toyota Motor Co., Ltd.)) is a catalyst carrier for supporting noble metal, which is composed of a composite oxide of an electron accepting element and another element, which is characterized in that the electron The acceptor element is selected from the group consisting of lanthanum, neodymium, yttrium, magnesium and a combination thereof, and the other element is selected from the group consisting of silicon, aluminum, zirconium, titanium and a combination thereof, and the electron Disclosed is a catalyst support wherein the molar ratio of the electron accepting element to the total of the accepting element and the other element is 0.3 or more.

Patent Document 4 (Japanese Patent Application Publication No. 2012-520236 (BASF SE)) has an average diameter of 10 to 120 μm and a BET surface area of 400 to 800 m ² / g as beads which can be used as a catalyst carrier. Metal having a pore volume in the range of 0.3 to 3.0 cm ³ / g, and selected from the group consisting of SiO ₂ , Al ₂ O ₃ , TiO ₂ , MgO, and mixtures thereof Or spherical beads comprising metalloid oxides are disclosed.

Patent Document 5 (JP 2013-252465 JP (Mitsui Mining & Smelting Co., Ltd.)), while suppressing the deterioration of the NO _X purification activity at large lean region than the excess air ratio λ is 1, compared to the Rh-supporting zirconia As a catalyst support for exhaust gas purification capable of greatly improving performance, and is a catalyst support for exhaust gas purification, which is represented by the general formula MPO ₄ (wherein, M is Y, La or Al) A catalyst support for exhaust gas purification is disclosed which is characterized in that it contains a phosphoric acid salt or a zirconium phosphate represented by the formula ZrP ₂ O ₇ .

Japanese Patent Application Laid-Open No. 6-218282 JP 2000-157865 A Japanese Patent Application Publication No. 2007-144393 JP 2012-520236 gazette JP, 2013-252465, A

As described above, alumina, which is widely used as a catalyst carrier, can support noble metals in a highly dispersed state because it has a large specific surface area, and since it is possible to earn reaction sites, it is possible for purification performance at low temperatures. Are better. However, while being exposed to heat during use, the alumina support itself coagulates or sinters and the specific surface area gradually decreases, and at the same time the precious metal also agglomerates, resulting in a decrease in catalytic activity, particularly low temperature catalytic activity. Had the task of

Therefore, the present invention is intended to provide a new support for an exhaust gas purification catalyst, which is superior in catalytic activity, particularly in catalyst purification performance at a low temperature, compared to the alumina support conventionally used.

The present invention proposes a support for an exhaust gas purification catalyst comprising particles containing a silicate or a phosphate containing one or more of elements belonging to Periodic Table Group 1 and Group 2. For example, a support for an exhaust gas purification catalyst is proposed which is composed of particles containing a silicate containing Ca, Sr or Ba, or two or more of them.

The support for an exhaust gas purification catalyst proposed by the present invention has a high specific surface area Al, even when it has a low surface area, when it is made to coexist with a catalytically active component such as a noble metal by enhancing the cocatalytic action to the exhaust gas purification reaction. It can exhibit excellent low temperature activity (in particular, propylene activation ability or oxygen activation ability) as compared to a ₂ O ₃ carrier. Furthermore, the high temperature NOx conversion rate can also be improved.
Thus, the exhaust gas purification catalyst support proposed by the present invention is useful as a support for a diesel oxidation catalyst. In addition, the NO-C ₃ H ₆ -O ₂ system, which is a reaction system of a three-way catalyst, is also excellent in low temperature activity, and thus is useful as a carrier for a gasoline three-way catalyst.

Next, the present invention will be described based on an embodiment. However, the present invention is not limited to the embodiments described below.

<This catalyst>
An exhaust gas purification catalyst (hereinafter referred to as "the present catalyst") as an example of an embodiment of the present invention has a composition containing a catalyst carrier (hereinafter referred to as "the present catalyst carrier") and a catalytically active component supported on the catalyst carrier. And, if necessary, may contain co-catalysts such as OSC materials, stabilizers and other components.

<The catalyst carrier>
The present catalyst support is a support for an exhaust gas purification catalyst, which is composed of particles containing a silicate or a phosphate containing one or more of the elements belonging to Groups 1 and 2 of the periodic table.

In addition, the present catalyst carrier may contain other components other than the above-mentioned silicate or phosphate or both, as long as the action of the above-mentioned silicate or phosphate is not hindered. However, the present catalyst carrier preferably contains 30% by mass or more of the above-mentioned silicate or phosphate or both, more preferably 50% by mass or more and even more preferably 95% by mass or more.

Examples of the “silicate or phosphate containing one or more of the elements belonging to Periodic Table Group 1 and Group 2” include Li, Na, K, and Rb belonging to Periodic Table Group 1 And silicates or phosphates containing Cs, Fr and Be, Mg, Ca, Sr, Ba and Ra belonging to Group 2 of the periodic table.

As said "silicate", Ca, Sr or Ba, or the silicate containing 2 or more types of these is preferable.
Specific examples of the silicate include, for example, A ₂ SiO ₄ (A is Ca, Sr or Ba, or an element containing two or more of them), or ASiO ₃ (A is Ca, Sr) Or Ba, or an element containing two or more of them) or a mixture of these.
At this time, in the A ₂ SiO ₄ and ASiO _3, A is, Ca, may if it contains either Sr or Ba, may contain other elements such as a divalent metal element such as Mg .

Among the above, from the viewpoint of durability and catalytic activity at low temperature, A ₂ SiO ₄ (A is Ca, Sr or Ba, or an element containing two or more of them), or ASiO ₃ (A is Preferably contains a single phase of Ca, Sr or Ba, or an element containing two or more of them, and among them, from the viewpoint of durability and low temperature catalytic activity, A ₂ SiO ₄ (A Particularly preferred is one containing a single phase of Ca, Sr or Ba, or an element containing two or more of them.

Above (the A, Ca, Sr or Ba, or an element comprising two or more of these) of A ₂ SiO ₄ as a, A ₂ SiO ₄ (A is, Ca, Sr or Ba, or of these And A ₂ SiO ₄ (A is a combination of Ca, Sr or Ba, or two or more of these elements and a divalent metal element such as Mg), and the like.
Specifically, for example, _{_{_{Ca 2 SiO 4, Sr 2 SiO}}} 4, Ba 2 SiO 4, (Ca 1-x Sr x) 2 SiO 4, (Ca 1-x Ba x) 2 SiO 4, (Sr 1-x _{_{_{Ba x) 2 SiO 4, (}}} Ca 1-x Mg x) 2 SiO 4, (Sr 1-x Mg x) 2 SiO 4, (Ba 1-x Mg x) 2 SiO 4, and other like in place of the Mg The composition etc. which contain the bivalent metal element of these are mentioned. In the above equation, x is a numerical value of 0 to 1.

As the above ASiO ₃ (A is Ca, Sr or Ba, or an element containing two or more of them), ASiO ₃ (A is Ca, Sr or Ba, or two or more of them) Elements, ASiO ₃ (A is Ca, Sr or Ba, or a combination of two or more of these elements with a divalent metal element such as Mg), and the like.
Specifically, _{_{_{CaSiO 3, SrSiO 3, BaSiO 3}}} , (Ca 1-x Sr x) SiO 3, (Ca 1-x Ba x) SiO 3, (Sr 1-x Ba x) SiO 3, (Ca _1-x Mg _x ) SiO ₃ , (Sr _{1 -x} Mg _x ) SiO ₃ , (Ba _{1 -x} Mg _x ) SiO ₃ , and other compositions containing a divalent metal element such as Mg instead of be able to. In the above equation, x is a numerical value of 0 to 1.

A ₂ SiO ₄ is characterized by having independent SiO ₄ tetrahedra and having a high content of alkaline earth metals.

Among the above-mentioned silicates, from the viewpoint of durability and catalytic activity at low temperature, it is preferable to be a support for an exhaust gas purification catalyst comprising particles containing a silicate containing Ba or Ba and Sr. Moreover, it is preferable that the said silicate is a thing which does not contain a rare earth element substantially. In addition, "substantially" is the meaning which accept | permits, when the rare earth element is included as an unavoidable impurity.
Here, as the said silicate containing Ba, Ba ₂ SiO ₄ or BaSiO ₃ or a mixture thereof can be mentioned as a preferable example, for example. Further, as the silicate containing Ba and Sr, for _{_{example, (Ba 1-x Sr x}} ) 2 SiO 4, _{_{or, (Ba 1-x Sr x}} ) SiO 3, or, as a preferable example of these mixtures It can be mentioned.
In addition, it is accept | permitted that elements other than the element mentioned already are contained in a silicate in the extent which does not impair the effect of this invention.

On the other hand, as said "phosphate", Ca, Sr or Ba, or the phosphate containing 2 or more types of these is preferable.
As a specific example of the phosphate, for example, A _x PO ₄ (x = 2 or 1.5, and in the case of x = 2, A is any one of Li, Na, K and Cs) A combination of a monovalent element or two or more types of monovalent elements and any one type of divalent elements or two or more types of divalent elements of Mg, Ca, Sr, and Ba, x In the case of = 1.5, A is any one of Mg, Ca, Sr and Ba, or one or more bivalent elements. It can be mentioned.

Among the above-mentioned phosphates, from the viewpoint of durability and catalytic activity at low temperatures, it is preferable to be a support for an exhaust gas purification catalyst comprising particles containing a phosphate containing Ba or Ba and Sr. Moreover, it is preferable that the said phosphate is a thing which does not contain a rare earth element substantially. In addition, "substantially" is the meaning which accept | permits, when the rare earth element is included as an unavoidable impurity.
Here, as the said phosphate containing Ba, for example, Ba _1.5 PO ₄ and KBaPO ₄ can be mentioned as preferable examples.
Further, as the phosphate containing Ba and Sr, for _{_{example, (Ba 1-x Sr x}} ) 1.5 PO 4 ( where 0 <x <1), K (Ba 1-x Sr x) PO 4 ( where 0 <X <1) can be mentioned as a preferable example.
In addition, it is accept | permitted that elements other than the element mentioned already are included in a phosphate in the extent which does not impair the effect of this invention.

The particles of the catalyst support are preferably porous in view of increasing the specific surface area, so the specific surface area of the catalyst support is preferably 0.1 m ² / g or more. It is preferably at least 0. ¹⁰ m ² / g, and particularly preferably at least 1.5 m ² / g.
There is no particular limitation on the upper limit of the specific surface area of the present catalyst carrier. According to the results of Examples and the results of tests conducted by the inventor so far, the specific surface area of the catalyst carrier may be 100 m ² / g or less, preferably 50 m ² / g or less, among which It is particularly preferred that it is 10 m ² / g or less.

(Method for producing the present catalyst carrier)
An example of a method for producing the present catalyst carrier will be described. However, the method for producing the catalyst carrier is not limited to the example described below.

For example, carbonates or acetates of elements belonging to Periodic Table Groups 1 and 2 and silicon oxide (SiO ₂ ) or phosphate ((NH ₄ ) ₂ HPO ₄ , NH ₄ H ₂ PO ₄ ) After being added to an organic solvent such as pure water or ethanol, stirred and wet-mixed, for example, the temperature is 100 to 120 ° C. (material temperature) in the case of pure water, and 50 to 100 ° C. in the case of an organic solvent. The catalyst carrier can be obtained by drying so as to hold for about 15 minutes to 15 minutes and calcining. However, the method for producing the catalyst carrier is not limited to the example described below.

In this case, for example, in the case of a carrier for an exhaust gas purification catalyst comprising particles containing a silicate containing Ca, Sr or Ba, or two or more of them, a carbonate of a Group 2 element (ACO ₃ (A is Ca, Sr or Ba, or an element containing two or more of them) and silicon oxide (SiO ₂ ) in an organic solvent such as pure water or ethanol, stirred and wet mixed After drying, for example, it is dried and maintained at 100 to 120 ° C. (material temperature) in the case of pure water and at 50 to 100 ° C. in the case of an organic solvent for about 40 minutes to 15 hours. A catalyst support can be obtained, but the method for producing the catalyst support is not limited to the example described below.

On the other hand, in the case of a carrier for an exhaust gas purification catalyst comprising particles containing phosphate containing Ca, Sr or Ba, or two or more of them, carbonates of Group 2 elements (ACO ₃ (A Is an element containing Ca, Sr or Ba, or two or more of them or an acetate, and a dihydrogen phosphate of a Group 1 element (LiH ₂ PO ₄ , NaH ₂ PO ₄ , KH ₂ PO ₄ ) Is poured into an organic solvent such as pure water or ethanol, stirred and wet mixed, and then, for example, in the case of pure water, 100 to 120 ° C. (product temperature), and in the case of organic solvent, 50 to 100 ° C. The catalyst carrier can be obtained by drying so as to maintain each for about 40 minutes to 15 hours and calcining, however, the method for producing the catalyst carrier is not limited to the example described below. .

As the firing atmosphere, an air atmosphere, an oxygen atmosphere, and an inert gas atmosphere can be mentioned. Among them, the air atmosphere is preferable from the viewpoint of mass productivity.
The firing temperature may be 500 to 1500 ° C., and more preferably 700 ° C. or more or 1400 ° C. or less.
Incidentally, when sintering is performed at a high temperature of about 1300 ° C., the crystallinity can be further improved, but the specific surface area is smaller than when sintered at a lower temperature.
The firing time may be appropriately set according to the firing temperature. As a standard, it is preferable to set it as 10 to 20 hours.

<Other catalyst support>
The present catalyst may contain other inorganic porous particles as a catalyst support in addition to the present catalyst support.
As the other inorganic porous particles, for example, porous particles of a compound selected from the group consisting of silica, alumina and a titania compound, more specifically, for example, alumina, silica, silica-alumina, alumino-silicates, Mention may be made of porous particles consisting of a compound selected from alumina-zirconia, alumina-chromia and alumina-ceria.
Other inorganic porous particles may include, for example, an OSC material, that is, a cocatalyst having oxygen storage capacity (OSC).
As such an OSC material, for example, a cerium compound, a zirconium compound, a ceria-zirconia composite oxide, etc. can be mentioned.

<Catalytic active component>
The catalytically active component contained in the present catalyst, that is, the metal exhibiting catalytic activity, for example, palladium, platinum, rhodium, gold, silver, ruthenium, iridium, nickel, cerium, cobalt, copper, iron, manganese, osmium, strontium and the like Metals can be mentioned. Moreover, these oxides can also be preferably adopted.
Among them, from the viewpoint of further enjoying the effect of the present catalyst, it is particularly preferable to include platinum or palladium or both as a catalytically active component.
In particular, platinum with higher sulfur poisoning resistance than palladium is more suitable for diesel engine applications with high sulfur content, which is a fuel poison, and sulfur poisoning resistance for gasoline engine applications with low sulfur content. In view of cost and cost, palladium is more preferable than platinum.

The supported amount of the catalytically active component in the present catalyst is preferably 5.0% by mass or less, more preferably 0.1% by mass or more, in terms of the metal mass of the active component, based on the mass of the carrier. In particular, it is more preferable that the content is 0.5% by mass or more or 3.0% by mass or less.
In addition, since the present catalyst carrier itself has a propylene activating ability, it is expected that the exhaust gas purification effect can be obtained only by mixing the catalytically active component and the present catalyst carrier without supporting the noble metal. Further, by the noble metal being supported by the present catalyst carrier, it is possible to obtain a further excellent exhaust gas purification effect.

<Stabilizer and other components>
The catalyst can include stabilizers, binders and other components.

As a stabilizer, an alkaline earth metal, an alkali metal, and a lanthanoid metal can be mentioned, for example. Among them, it is possible to select one or more of metals selected from the group consisting of magnesium, barium, boron, thorium, hafnium, silicon, calcium, lanthanum, neodymium and strontium.

Moreover, you may contain well-known addition components, such as a binder component.
As the binder component, an inorganic binder, for example, a water-soluble solution such as alumina sol can be used.

<Method of producing the present catalyst>
Next, an example of a method for producing the present catalyst will be described. However, the method for producing the present catalyst is not limited to the example described below.

The present catalyst can be produced, for example, by mixing the present catalyst carrier, a catalytically active component such as a noble metal compound, and other components, heating and drying, and calcining.

Examples of the solution of the above-mentioned noble metal compound include nitrates, chlorides and sulfates of noble metals.
As other components, co-catalysts such as OSC materials, stabilizers, binders and the like can be mentioned.

<The present catalyst component>
A catalyst construction for exhaust gas purification (referred to as "the present catalyst construction") can be produced which includes a catalyst layer made of the present catalyst and a base made of, for example, a ceramic or a metal material.

The catalyst layer may have, for example, a structure in which a catalyst layer is formed on the surface of a substrate, or a structure in which a catalyst layer is formed on the surface of a substrate via another layer. The catalyst layer may be provided, or may be provided with a structure in which the catalyst layer is formed at a place other than the surface side of the base material.
In any of the production methods, the catalyst layer may be a single layer or a multilayer of two or more layers.

(Base material)
A wide variety of currently known substrates can be adopted as the substrate of the present catalyst component.
As a material of a base material, refractory materials and metal materials, such as ceramics, can be mentioned.
The material of the ceramic base material is refractory ceramic material such as cordierite, cordierite-alpha alumina, silicon carbide (SiC), silicon nitride, mullite, alumina, aluminum titanate, zircon mullite, spodumene, alumina-silica Mention may be made of magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha alumina and aluminosilicates.
The material of the metal substrate may include a refractory metal such as stainless steel or other suitable corrosion resistant alloy based on iron such as a refractory metal such as Fe-Cr-Al alloy.

The shape of the substrate is not particularly limited. In general, the shape is a honeycomb, a plate, a pellet or the like, preferably in a honeycomb shape.
Moreover, the shape mainly employ | adopted by the particulate filter may be sufficient. For example, wall-through type, flow-through honeycomb type, wire mesh type, ceramic fiber type, porous metal type, particle-filled type, foam type and the like can be mentioned.

When a honeycomb-shaped substrate is used, for example, a monolithic substrate having a large number of fine gas flow passages parallel to the inside of the substrate, ie, channels, can be used so that the fluid can flow inside the substrate. At this time, the catalyst can be formed by coating the present catalyst on the inner wall surface of each channel of the monolithic substrate.

(Method of producing the present catalyst component)
As a method for producing the present catalyst component, for example, the present catalyst carrier, a catalyst active component such as a noble metal, and optionally an OSC material, a binder and water are mixed and stirred to obtain a slurry, and the obtained slurry is The present catalyst component can be produced by applying a base material such as a honeycomb body and firing it to form a catalyst layer on the surface of the base material.
In addition, after the catalyst carrier, and if necessary, the OSC material, the binder, and water are mixed and stirred to form a slurry, and the obtained slurry is applied to a substrate such as a ceramic honeycomb body to form a catalyst carrier layer. And immersing the catalyst active layer in a solution of the catalytic active component so that the catalytic support layer is adsorbed, and calcinated to form a catalyst layer on the surface of the substrate, thereby producing the present catalyst structure. You can also.
In addition, the catalyst active component supporting body in which the catalyst active component is supported on an oxide, the present catalyst carrier, and if necessary, the OSC material, the stabilizing material, the binder and water are mixed and stirred to form a slurry. The catalyst composition can also be produced by applying to a material and calcining this to form a catalyst layer on the surface of the substrate.
In addition, it is possible to employ | adopt all well-known methods for the method for manufacturing this catalyst, and it is not limited to the said example.

<Explanation of the phrase>
In the present specification, when expressing as “X to Y” (where X and Y are arbitrary numbers), “preferably more than X” or “preferably Y” with the meaning of “X or more and Y or less” unless otherwise stated. Also includes the meaning of "smaller".
Also, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), “greater than X is preferable” or “preferably less than Y” It also includes the intention.

Hereinafter, the present invention will be further described in detail based on examples and comparative examples.

Comparative Example 1
A commercially available alumina powder (specific surface area: 159.6 m ² / g) is introduced into a Pt (NH ₃ ) ₂ (NO ₂ ) ₂ aqueous solution and stirred for 2 hours to impregnate the catalyst support with Pt, and then evaporated. It was dried and then kept in the atmosphere at 600 ° C. for 3 hours to obtain a noble metal-supported catalyst (sample).
The amount of noble metal carried of the obtained noble metal-supported catalyst (sample) was 1 mass%.

Example 1
Ba carbonate (BaCO ₃ ) and silicon oxide (SiO ₂ ) are mixed at a molar ratio of 2: 1 and charged into ethanol, stirred for 24 hours and wet mixed, and then 60 ° C. (product temperature) The catalyst carrier was obtained by drying to hold for 12 hours and then calcining in the air at 1350 ° C. for 36 hours.
The catalyst support thus obtained had a specific surface area of 0.4 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of Ba ₂ SiO ₄ was confirmed. .

The catalyst support (Ba ₂ SiO ₄ ) thus obtained is put into a Pt (NH ₃ ) ₂ (NO ₂ ) ₂ aqueous solution and stirred for 2 hours to impregnate the catalyst support with Pt, and then the temperature is 60 ° C. The product temperature was dried for 1 hour, and then kept at 600 ° C. for 3 hours in the atmosphere to obtain a noble metal-supported catalyst (sample).
The amount of noble metal carried of the obtained noble metal-supported catalyst (sample) was 1 mass%.

<C ₃ H ₆ -O ₂ reaction (Light-off test)>
As a pretreatment of the C ₃ H ₆ oxidation activity evaluation test, a gas flow rate of 500 cm ³ / min is applied to a gas of 1.5% O ₂ / He (600 ° C.) and 0.1 g of the noble metal-supported catalyst (sample) Pretreatment was carried out at a flow rate of 10 min.

For each of the noble metal-supported catalysts (samples) obtained in Comparative Example 1 and Example 1, the purification performance with simulated exhaust gas was evaluated using a fixed bed flow type reactor.
That is, in a reaction tube, 0.1 g of each noble metal-supported catalyst (sample) is packed with quartz wool before and after the catalyst so as to sandwich the catalyst, and quartz wool is packed before and after the noble metal-supported catalyst (sample). Set.
Then, after the above pretreatment, a simulated exhaust gas consisting of C ₃ H ₆ 1500 ppm, O ₂ 9000 ppm and the balance He composition is introduced into the reaction tube at a total flow rate of 500 cm ³ / min, and 100 ° C. to 600 ° C. at 10 ° C. The temperature was continuously raised at 1 / min, and the exhaust gas at the outlet of the reaction tube was analyzed using a quadrupole mass spectrometer to determine the component composition in the reaction gas.

(result)
Although the catalyst support of Example 1 has a significantly smaller specific surface area than the catalyst support of Comparative Example 1, it can be confirmed that the catalyst support exhibits excellent propylene activation ability or oxygen activation ability. The Above all, it could be confirmed that the propylene activation ability or the oxygen activation ability at low temperature was excellent.

Example 2
Ca carbonate (CaCO ₃ ) and silicon oxide (SiO ₂ ) are mixed at a molar ratio of 2: 1 and charged into pure water, stirred for 24 hours and wet mixed, and then 120 ° C. (product temperature) The catalyst carrier was obtained by drying so as to hold for 12 hours and then calcining at 1350.degree. C. for 24 hours in the atmosphere.
The catalyst support thus obtained had a specific surface area of 8.8 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of Ca ₂ SiO ₄ was confirmed. .

The catalyst support (Ca ₂ SiO ₄ ) thus obtained is put into a Pt (NH ₃ ) ₂ (NO ₂ ) ₂ aqueous solution and stirred for 2 hours to impregnate the catalyst support with Pt, and then evaporated to dryness. Then, it was kept in the air at 600 ° C. for 3 hours to obtain a noble metal-supported catalyst (sample).
The amount of noble metal carried of the obtained noble metal-supported catalyst (sample) was 1 mass%.

Example 3
A catalyst carrier and a noble metal-supported catalyst (sample) were obtained in the same manner as in Example 2 except that Ca carbonate was changed to Sr carbonate in Example 2.
The catalyst support had a specific surface area of 9.6 m ² / g, and as a result of analysis by X-ray diffraction (XRD), a peak showing a single phase of Sr ₂ SiO ₄ was confirmed.

Example 4
In Example 2, Ca carbonate (CaCO ₃ ) and Sr carbonate (CaCO ₃ ) were mixed with Ca carbonate (CaCO ₃ ) and silicon oxide (SiO ₂ ) in a molar ratio of 2: 1. A catalyst carrier and a noble metal-supported catalyst (sample) were obtained in the same manner as in Example 2 except that SrCO ₃ ) and silicon oxide (SiO ₂ ) were mixed at a molar ratio of 1: 1: 1.
The catalyst support had a specific surface area of 1.9 m ² / g, and as a result of analysis by X-ray diffraction (XRD), a peak showing a single phase of (Sr _0.5 Ca _0.5 ) ₂ SiO ₄ was confirmed. The

Example 5
In Example 2, Ca carbonate (CaCO ₃ ) and silicon oxide (SiO ₂ ) were mixed at a molar ratio of 2: 1, Sr carbonate (SrCO ₃ ) and Mg carbonate ( A catalyst carrier and a noble metal-supported catalyst (sample) were obtained in the same manner as in Example 2 except that MgCO ₃ ) and silicon oxide (SiO ₂ ) were mixed at a molar ratio of 1: 1: 1.
The catalyst support had a specific surface area of 3.1 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of (Sr _0.5 Mg _0.5 ) ₂ SiO ₄ was confirmed. The

Example 6
In Example 2, Ca carbonate (CaCO ₃ ) and Mg carbonate (CaCO ₃ ) were mixed with Ca carbonate (CaCO ₃ ) and silicon oxide (SiO ₂ ) at a molar ratio of 2: 1. A catalyst carrier and a noble metal-supported catalyst (sample) were obtained in the same manner as in Example 2 except that MgCO 3) and silicon oxide (SiO ₂ ) were mixed at a molar ratio of 1: 1: 1.
The catalyst support had a specific surface area of 2.2 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of (Ca _0.5 Mg _0.5 ) ₂ SiO ₄ was confirmed. The

Example 7
In Example 2, in a place where Ca carbonate (CaCO ₃ ) and silicon oxide (SiO ₂ ) were mixed at a molar ratio of 2: 1, Ba carbonate (BaCO ₃ ) and silicon oxide (SiO ₂ ) were mixed. _A catalyst carrier and a noble metal-supported catalyst (sample) were obtained in the same manner as in Example 2 except that ₂ ) and ₂ ) were mixed at a molar ratio of 1: 1.
The catalyst support had a specific surface area of 1.7 m ² / g, and as a result of analysis by X-ray diffraction (XRD), a peak showing a single phase of BaSiO ₃ was confirmed.

Example 8
In Example 2, the change Ca carbonate salt (CaCO ₃₎ to Ba carbonate _{(BaCO 3), Pt (NH} 3) 2 (NO 2) 2 solution points except that the Pd nitrate solution, implemented As in Example 2, a catalyst carrier and a noble metal-supported catalyst (sample) were obtained.
The catalyst support had a specific surface area of 3.9 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of Ba ₂ SiO ₄ was confirmed.

<Measurement of degree of dispersion (%) of Pt or Pd>
The degree of dispersion (%) of Pt (Pd) was measured by a CO pulse adsorption method.
In addition, Pt (Pd) dispersion degree shown to Table 1 and Table 2 is the value calculated by Formula (1).
Pt (Pd) dispersion degree (%) = (amount of Pt (Pd) corresponding to CO adsorption amount (mol) / total amount of contained Pt (Pd) (mol)) × 100

For each of the noble metal-supported catalysts (samples) obtained in Comparative Example 1 and Examples 2 to 7, the purification performance with simulated exhaust gas was evaluated using a fixed bed flow type reactor.
That is, in a reaction tube, 0.1 g of each noble metal-supported catalyst (sample) is packed with quartz wool before and after the catalyst so as to sandwich the catalyst, and quartz wool is packed before and after the noble metal-supported catalyst (sample). Set.
Then, after the above pretreatment, a simulated exhaust gas consisting of C ₃ H ₆ 1500 ppm, O ₂ 9000 ppm and the balance He composition is introduced into the reaction tube at a total flow rate of 500 cm ³ / min, and 100 ° C. to 600 ° C. at 10 ° C. The temperature was continuously raised at 1 / min, and the exhaust gas at the outlet of the reaction tube was analyzed using a quadrupole mass spectrometer to determine the component composition in the reaction gas.

<NO-C ₃ H ₆ -O ₂ reaction (Light-off test)>
As a pretreatment for the NO reduction activity evaluation test, a gas of 1.5% O ₂ / He (600 ° C.) was used, and a gas flow rate of 500 cm ³ / min was applied for 10 minutes with respect to 0.1 g of a noble metal-supported catalyst (sample) It was allowed to flow, pretreated and cooled to the reaction start temperature.

For each of the noble metal-supported catalysts (samples) obtained in Comparative Example 1 and Examples 2 to 8, the purification performance with simulated exhaust gas was evaluated using a fixed bed flow type reactor.
That is, quartz wool is packed in front and back of the catalyst so as to sandwich 0.1 g of each noble metal-supported catalyst (sample) in the reaction tube, and quartz wool is packed in front of and behind the noble metal-supported catalyst (sample). I set it.
Then, after the above pretreatment, a simulated exhaust gas composed of NO 1000 ppm, C ₃ H ₆ 1500 ppm, O ₂ 9000 ppm, balance He is introduced into the reaction tube at a total flow rate of 500 cm ³ / min, and from 200 ° C. to 600 ° C. The temperature was raised stepwise at 10 ° C./min, and the exhaust gas at the outlet of the reaction tube was analyzed using a quadrupole mass spectrometer to determine the component composition in the reaction gas.

(Discussion)
Looking at the results of the C ₃ H ₆ -O ₂ reaction (light-off test), compared to Comparative Example 1 in which alumina is the carrier, in the example, the T-50 of THC is at a lower temperature side, and the alumina carrier is It was found to express higher low temperature activity as compared with.
Also, looking at the results of the NO-C ₃ H ₆ -O ₂ reaction (Light-off test), compared to Comparative Example 1 in which alumina is the carrier, the example shows T-50 of THC even in the presence of NO. Of the lower temperature side, and it was observed that high temperature activity was expressed as compared to the alumina carrier. Furthermore, as the T-50 of THC on the lower temperature side, there was a tendency that the T-20 of NO was also lowered.
The same can be said for phosphate particles.

In addition, although the alumina used by the comparative example 1 has high dispersion degree compared with the silicate particle | grains used in the Example, the result in which the Example was excellent in low temperature activity is obtained. In this respect, in view of, for example, the result of the C ₃ H ₆ -O ₂ reaction, in the example, C ₃ H ₆ is activated on the catalyst support, that is, on the silicate particle surface, and HC activation from the low temperature range Since reaction between species and O ₂ or NO is likely to occur, it is speculated that excellent low temperature activity is exhibited in both reactions despite the fact that the specific surface area and the degree of dispersion of precious metals are extremely small compared to Comparative Example 1. Be done.
In addition, in the high temperature region, the example showed that the C ₃ H ₆ conversion was increased, and it was found that C ₃ H ₆ combustion was dominant. On the other hand, it was found that although the NO conversion rate decreases with the temperature rise, the example shows higher η 500 as compared with Comparative Example 1.

In addition, as shown in Example 8, the present catalyst support is Al ₂ O ₃ even if it is a noble metal other than Pt as the noble metal to be supported, and has a low surface area as in the case of supporting Pt. It was confirmed that propylene activation ability or oxygen activation ability can be exhibited and NOx conversion at high temperatures up to about 400 ° C. can be maintained at an equivalent level as compared with the case where a carrier is used.
In addition to the low temperature activity, it has also been confirmed that the active species supported on the present catalyst carrier is expressed in the high temperature region in addition to the low temperature activity by combining it with Pt and Pd.

The above examples and the tests conducted so far according to the present invention, and the elements belonging to Group 1 of the periodic table have the same chemical properties, and the elements belonging to Group 2 of the periodic table have the same chemical properties Based on common technical knowledge that it is a carrier for an exhaust gas purification catalyst comprising particles containing a silicate containing one or more of the elements belonging to Groups 1 and 2 of the periodic table. For example, it can be expected that the same effect as the above embodiment can be obtained.

Example 9
A mixture of Ba carbonate (BaCO ₃ ) and dihydrogen phosphate K (KH ₂ PO ₄ ) in a molar ratio of 1: 1 is added to ethanol, stirred for 24 hours for wet mixing, and then at 60 ° C. The catalyst carrier was obtained by drying so as to maintain (material temperature) for 12 hours, and then calcining in air for 3 hours at 600 ° C. for 3 hours and then calcining at 1300 ° C. for 3 hours.
The catalyst support thus obtained had a specific surface area of 1.0 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak indicating a single phase of KBaPO ₄ was confirmed.
The noble metal-supported powder using the catalyst carrier was obtained by the same procedure as in Example 2.

Example 10
After mixing Sr carbonate (SrCO ₃ ) and dihydrogen phosphate K (KH ₂ PO ₄ ) in a molar ratio of 1: 1, charging to ethanol, stirring for 24 hours and wet mixing, 60 ° C. The catalyst carrier was obtained by drying so as to maintain (material temperature) for 12 hours, and then calcinating in the air at 1200 ° C. for 12 hours.
The catalyst support thus obtained had a specific surface area of 0.9 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak indicating a single phase of KSrPO ₄ was confirmed.
The noble metal-supported powder using the catalyst carrier was obtained by the same procedure as in Example 2.

Example 11
Ba acetate (Ba (CH ₃ COO) ₂ ) and sodium dihydrogenphosphate (NaH ₂ PO ₄ .2H ₂ O) are mixed at a molar ratio of 1.5: 1 and charged into nitric acid, and then The suspension was adjusted to pH = 13 with sodium hydroxide, and the suspension aged at 90 ° C. for 12 hours was filtered off and dried at 60 ° C. for 12 hours to obtain a catalyst carrier.
The catalyst support thus obtained has a specific surface area of 3.0 m ² / g, and as a result of X-ray diffraction (XRD) analysis, a peak showing a single phase of Ba _1.5 PO ₄ is confirmed It was done.
The noble metal-supported powder using the catalyst carrier was obtained by the same procedure as in Example 2.

<Measurement of Specific Surface Area and Pt Dispersion>
The specific surface area (m ² / g) and the degree of Pt dispersion (%) were measured in the same manner as described above.

<C ₃ H ₆ -O ₂ reaction (Light-off test)>
Measurement of the C ₃ H ₆ -O ₂ reaction (Light-off test) was performed in the same manner as described above.

Considering Examples 9 to 11 and the test results that the present inventor has conducted, it includes a phosphate containing one or more of the elements belonging to Groups 1 and 2 of the periodic table. A carrier for an exhaust gas purification catalyst consisting of particles is the same as the carrier for an exhaust gas purification catalyst consisting of particles containing a silicate containing one or two or more kinds of elements belonging to Groups 1 and 2 of the periodic table. The mechanism of action was shown, and it could be confirmed that the same effect could be obtained.

Claims

A support for an exhaust gas purification catalyst comprising particles containing a silicate or phosphate containing one or more of elements belonging to Periodic Table Group 1 and Group 2.
A carrier for an exhaust gas purification catalyst, which comprises particles containing a silicate containing Ca, Sr or Ba, or two or more of them.
The silicate is A 2 SiO 4 (A is Ca, Sr or Ba, or an element containing two or more of them), or ASiO 3 (A is Ca, Sr or Ba, or these) The support for an exhaust gas purification catalyst according to claim 1 or 2, which is an element containing two or more of them or a mixture thereof.
The phosphate is A x PO 4 (x = 2 or 1.5, and in the case of x = 2, A is any one monovalent element or two of Li, Na, K and Cs) A combination of at least one kind of monovalent element and any one kind of divalent element or two or more kinds of divalent elements of Mg, Ca, Sr and Ba, in the case of x = 1.5 4) any one of Mg, Ca, Sr, and Ba, or two or more kinds of divalent elements). A carrier for an exhaust gas purification catalyst according to any one of the above.
The exhaust gas purification catalyst support according to any one of claims 1 to 4, wherein the silicate or phosphate is a Ba-containing silicate or phosphate.
An exhaust gas purification catalyst comprising the exhaust gas purification catalyst support according to any one of claims 1 to 5 and a catalytically active component.