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    • 专利摘要:
    abstract "exhaust gas purification catalyst" the aim of the present invention is to provide an exhaust gas purification catalyst that can achieve high purification performance while eliminating the emission of h2s. the objective is solved through an exhaust gas purification catalyst where the lower layer of the catalyst coating layer comprises a zirconia composite oxide ceria presenting an ordered structure of the pyrochlorine type, where the zirconia composite oxide is ceria contains at least one additional element selected from the group consisting of prasiodymium, lanthanum, and yttrium from 0.5 to 5.0 mole % with respect to the total amount of cation, and the molar ratio of (cerium + the additional element) : (zirconium) occurs in the range from 43:57 to 48:52.
    公开号:BR112017012336B1
    申请号:R112017012336-3
    申请日:2015-12-11
    公开日:2021-07-20
    发明作者:Isao Chinzei；Hiromasa Suzuki；Takeru Yoshida；Masahide Miura；Yuki Aoki；Mitsuyoshi Okada；Toshitaka Tanabe；Akihiko Suda；Yoshinori Saito；Hirotaka Ori；Kosuke IIZUKA；Akira Morikawa
    申请人:Cataler Corporation；Toyota Jidosha Kabushiki Kaisha；
    IPC主号:
    专利说明:

    Technical Field
    [001] The present invention relates to an exhaust gas purification catalyst. More specifically, the present invention relates to an exhaust gas catalyst having a catalyst coating layer composed of lower and upper layers, where the lower layer contains a pyrochlorine-type ceria-zirconia compound oxide comprising of additional elements predetermined. ceria-zirconia Technical Fundamentals
    [002] Exhaust gas discharged from internal combustion engines such as vehicle engines contains harmful gases such as carbon monoxide (C)), nitrogen oxides (NOx), and unburned hydrocarbons (HC). An exhaust gas purification catalyst (ie, the so-called three-way catalyst) capable of decomposing such noxious gases contains, in the form of a co-catalyst incorporating the oxygen storage capacity (OSC), an oxide of composed of ceria-zirconia or the like. A material incorporating oxygen storage capacity (OSC material) has an effect of suppressing the reduction in the purification rate due to variation in the exhaust gas composition through oxygen absorption/release, thereby controlling the fuel-air rate ( A/F) in a micro space.
    [003] In order to improve the purification performance of an exhaust gas purification catalyst, an OSC material is required to have a desirable rate of oxygen absorption/release to respond to a sudden atmospheric change due to variation in the rate of A /F and the desirable oxygen storage capacity for maintenance of oxygen absorption/release capacity over a long period of time. In compliance with such requirements, for example, Patent Reference 1 suggests an exhaust gas purification catalyst exerting a high NOx purification capacity even after a test duration, which comprises of a first oxygen storage material where no noble metals are supported and having an orderly arrangement structure of the pyrochlore type; and a second oxygen storage material having a higher oxygen storage rate and a second oxygen storage material having a higher oxygen storage rate and a lower oxygen storage capacity relative to the first oxygen storage material. oxygen, where a platinum group noble metal is supported on the second oxygen storage material.
    [004] There has been, for example, a catalyst incorporating two layers of catalysts (i.e. upper and lower layers) which separately contain Pt and Rh, respectively, has been suggested in view of the problematic deterioration of catalyst activity due to the formation of solid metal solution in an exhaust purification catalyst with reduced NOx storage that stores NOx in the poor atmosphere where there is excess oxygen, effecting the release of stored NOx by changing the exhaust gas atmosphere with a rich or stoichiometric atmosphere with the excess of reduced components and with NOx purification through reaction with reducible components such as HC and CO through the effect of noble metals aimed at reduction (Patent References 2 and 3). List of Citations Patent References (RP 1) JP Patent Application (Kokai) No. 2012-024701 A (RP 2) JP Patent Application (Kokai) No. 2010-201284 A (RP 3) Patent Application (Kokai) No. 2009-285604 A Invention Summary Technical problem
    [005] A dual catalyst system combining an initiating catalyst (S/C, also referred to as an initiating converter) and an under-floor catalyst (UF/C, also referred to as an under-floor converter or an under-floor catalyst). floor) has been widely used in recent years. In such a type of dual catalytic system, the S/C is installed just below an internal combustion engine and exposed to an exhaust gas at elevated temperatures. Since the UF/C is provided downstream of the S/C where the ingress exhaust gas concentration is small and its temperature is relatively small, a conventional OSC material that requires temperatures high to exert its properties may not exert a sufficient oxygen absorption/release function. Furthermore, if the S/C becomes unstable to function sufficiently due to deterioration or rupture, the UF/C's own ability to exert sufficient exhaust gas purification becomes necessary. Especially in the case of UF/C, the performance of oxygen absorption/release capacity and NOx purification are mutually exclusive events, thus there is a difficulty in reaching a use of the conventional material.
    [006] In addition, there has been a problem regarding the growth in the amount of conventional OSC material used to improve the oxygen absorption/release capacity that comes to occur with the adsorption of sulfur dioxide contained in an exhaust gas through of ceria and elements of the genus and due to an increase in the amount of hydrogen sulfide (H2S) generated by the reduction of sulfur dioxide. Since even a minute's worth of H2S has a bad odor, it is preferable to suppress H2S emissions as much as possible. However, it has proved difficult to reach both a rich oxygen absorption/release capacity and the elimination of H2S emissions with the use of conventional materials. The aim of the present invention is to provide an exhaust gas purification catalyst with preferential use as UF/C that presents a high purification performance while eliminating the emission of H2S. Solution of the problem
    [007] The present inventors have studied the above problem and determined that the exhaust gas purification catalyst that achieves a high purification performance while eliminating the H2S emission can be provided through the use of the oxide of ceria-zirconia compound of the newly developed pyrochlore type comprising an additional element predetermined as an OSC material in the lower layer of a catalyst coating layer having upper and lower layers. The present invention is summarized as follows below. (1) An exhaust gas purification catalyst comprising a substrate and a catalyst coating layer formed adjacent to the substrate, the catalyst coating layer having at least one upper layer directly in contact with the gas exhaust flowing towards the catalyst, and a lower layer formed below the upper layer, with the upper layer comprising a carrier and a carrier-supported first noble metal catalyst, where the first noble metal catalyst contains at least Rh, the lower layer comprises of a carrier, a second carrier-supported noble metal catalyst, and a ceria-zirconia compound oxide having an ordered array structure of the pyrochlorine type, where the second noble metal catalyst contains at least Pt or Pd, where the ceria-zirconia compound oxide contains at least one additional element selected from the consist group. ranging from praseodymium, lanthanum, and yttrium from 0.5 to 5.0% of moles in relation to the total amount of cation, and the molar ratio of (cerium + the additional element): (zirconium) is in the range ranging from 43 :57 to 48:52. (2) The exhaust gas purification catalyst according to (1), the additional element contained in the ceria-zirconia compound oxide being praseodymium. (3) The exhaust gas purification catalyst according to items (1) or (2), where the lower layer contains oxide of ceria-zirconia compound in an amount ranging from 1 to 20 g/L in relation to the substrate volume. (4) The exhaust gas purification catalyst according to any one of items (1) to (3), where the catalyst coating layer has: a portion where the top layer is not formed near the side edge a upstream of the exhaust gas purification catalyst; a further portion where the lower layer is not formed near the downstream side end of the exhaust gas purification catalyst; and (5) the exhaust gas purification catalyst according to item (4), where the lower layer is formed over the area where the length is within the range ranging from 75% to 85% of the total length of the substrate from the upstream side end of the exhaust gas purification catalyst, and the top layer being formed over the area whose length is within the range ranging from 75% to 85% of the total length of the substrate from the side end downstream of the exhaust gas purification catalyst. Advantageous Effects of the Invention
    [008] According to the exhaust gas purification catalyst of the present invention, a pyrochlore-type ceria-zirconia compound oxide comprising of an additional predetermined element is employed for the lower layer of a coating layer of catalyst incorporating top and bottom layers. This allows for a complete improvement of the absorption/release capacity, improvement of the NOx purification performance, and the elimination of H2S emissions, which comprise of mutually exclusive events, thus making it possible to reach a high purification performance even in the face of relatively low temperatures while eliminating H2S emissions.
    [009] This descriptive report incorporates the contents of the report of Japanese Patent Application No. 2014-252022, where priority of the present application is claimed. Brief Description of Drawings
    [010] Fig. 1 schematically shows a cross-sectional view of a catalyst coating layer of the exhaust gas purification catalyst of the present invention in one embodiment.
    [011] Fig. 2 presents a graph showing the relationship between the amounts of ZC with Pr pyrochlore added, conventional ZC or conventional pyrochlore ZC added near the bottom layer of the NOx purification rate.
    [012] Fig. 3 consists of a graph showing the relationship between the amount of ZC with Pr pyrochlore added or conventional ZC added and the NOx purification rate containing variable A/F ratio. Description of Modalities
    [013] The exhaust gas purification catalyst of the present invention comprises a substrate and a catalyst coating layer formed on the substrate, where the catalyst coating layer has at least one upper layer directly contacting a gas of exhaust flowing to the catalyst and a lower layer formed below the upper layer, and with the lower layer comprising of a ceria zirconia compound oxide having an ordered pyrochlorine-type disposition structure and containing at least one additional element selected from the group consisting of praseodymium (Pr), lanthanum (La), and yttrium (Y). The catalyst coating layer is composed of at least two layers, ie a top layer and a bottom layer, however, it can be composed of three or more layers if required. In such a case, it is preferable that the "bottom layer" where an oxide of ceria-zirconia compound of the pyrochlorine type comprises an additional predetermined incorporated element is formed directly below a top layer of the catalyst coating layer , which comes in direct contact with an exhaust gas that flows to the catalyst. (Ceria-zirconia composite oxide contained in the lower layer of the catalyst coating layer)
    [014] The oxide of ceria-zirconia compound contained in the lower layer (if the catalyst coating layer has three or more layers, which may be any layer below the top layer) of the catalyst coating layer of the purification catalyst The exhaust gas of the present invention is characterized in that an orderly arrangement structure of the pyrochlore type contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium from 0.5 to 5.0% of moles in relation to the total amount of cation, and the molar ratio of (cerium + the additional element): (zirconium) is in the range from 43:57 to 48:52.
    [015] Ceria-zirconia composite oxide consists of a new OSC material developed by the present inventors. It is characterized by the fact that heat-induced deterioration is eliminated and sufficient oxygen absorption/release capacity can be exerted at temperatures as low as around 400°C. It is characterized by the fact that the absorption capacity/ oxygen release is large, while the oxygen absorption/release rate is relatively low, both the specific surface area and the volumetric density are small. With respect to the specific surface area of the ceria-zirconia compound oxide, the BET specific surface area calculated from an adsorption isotherm using the BET isothermal adsorption formula is preferably within the range of 0.1 to 2 m2/g, particularly ranging from 0.2 to 1 m2/g.
    [016] In general, the phrase that an oxide of ceria-zirconia compound "shows a pyrochlore-type orderly arrangement structure" implies that a crystal phase incorporating an orderly pyrochlore-type arrangement consisting of cerium and ions zirconium ions (pyrochlore phase) come to be formed. The disposition structure of the pyrochlore phase can be identified with the 2θ angled peaks along the 14.5°, 28°, 37°, 44.5°, and 51° positions within a ray diffraction pattern. X obtained with CuKα radiation. The word “peak” used in this report refers to a peak having an elevation from the baseline to the top of the peak of 30 cps or more. In addition, when the diffraction line intensity is obtained, the calculation is performed by subtracting the average diffraction line intensity from θ = 10° to 12° as a base value from the value of each line intensity of diffraction.
    [017] In a ceria-zirconia compound oxide incorporating an ordered array structure of the pyrochlore type, the content ratio of a crystal phase incorporating an ordered array structure of the pyrochlore type, which is calculated from a rate X-ray diffraction pattern peak intensity is preferably at 50% or more, and particularly at 80% or more of the entire crystal phase. Methods for the preparation of ceria-zirconia compound oxide having an ordered pyrochlore-like structure are known to those skilled in the art.
    [018] The pyrochlore phase of a ceria-zirconia compound oxide (Ce2Zr2O7) presents defective sites in oxygen. When oxygen atoms enter the sites, the pyrochlore phase changes to a K phase (Ce2Zr2O8). The K phase can change to a pyrochlore phase through the release of oxygen atoms. The oxygen storage capacity of a ceria-zirconia compound oxide is due to the mutual phase transition between the pyrochlore phase and the k phase that causes oxygen absorption/release.
    [019] In measuring the X-ray diffraction (XRD) of a crystal phase of a ceria-zirconia compound oxide with CuKα radiation, a diffraction line of 2θ = 14.5° is derived from a plane (111) of an ordered phase (phase k ), and a diffraction line of 2θ = 29° is superimposed from a diffraction line derived from a plane (222) of an ordered phase and a diffraction line derived from a plane (111) of a solid ceria-zirconia solution not having a pyrochlore phase. Therefore, the value I(14/29) which consists of the intensity rate of both diffraction lines, can be used as an index demonstrating the ordered phase abundance rate. Furthermore, since a diffraction line of 2θ = 28.5° is derived from a plane (111) of the CeO2 itself, the value l(28/29), which comprises the intensity ratio of the diffraction line of 2θ = 28.5° and that 2θ = 29° can be used as an index demonstrating the degree of phase separation of CeO2 coming from the composite phase. In the present case, based on the one-phase PDF card (PDF2: 01-070-4048) and the one-phase pyrochlore PDF card (PDF2: 01-075-2694), the values of I(14/29) of a complete k-phase and a complete pyrochlore phase can be calculated, respectively, as 0.04 and 0.05.
    [020] The reason why the use of a pyrochlore-type ceria-zirconia compound oxide in the present invention presents the above properties coming to contain at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium is assumed by the following condition. In the case of praseodymium, since ΔG (Gibbs free energy) of a reaction the reduction expressed by the formula Pr6θii^3Pr2θa+θ2 turns out to be negative, a reduction reaction of CeO2 expressed by the formula: 2Ceθ2^Ce2θa+0.5θ2 which ΔG is positive with a high probability of occurring. In the case of lanthanum and yttrium, since they are stable in the trivalent state, they stabilize intracrystalline oxygen defects according to the principle of charge compensation.
    [021] With respect to durability, a ceria-zirconia composite oxide used in the present invention is characterized by the fact that when heated in air at 1100°C for 5 hours, the values of I(14/29) and I( 28/29) obtained by measuring X-ray diffraction with CuKα radiation are, respectively, 0.02 or more and 0.08 or less. (The bottom layer of the catalyst coating layer)
    [022] The lower layer of the catalyst coating layer of the exhaust gas purification catalyst of the present invention contains, as the second noble metal catalyst, Pt or Pd. The second noble metal catalyst can be Pt or Pd alone, or just a mixture of Pt or Pd. Pt or Pd mainly contribute to purification through the oxidation of CO and HC. The second noble metal catalyst is supported with a carrier and contained in such form. The bearer is not particularly limited. Examples of carrier include arbitrary metal oxides generally used as catalyst carriers such as aluminum (Al2O3), ceria (CeO2), zirconia (ZrO2), silica (SiO2), and titanium (TiO2) and any combinations thereof . Aluminum is preferably employed as a carrier for a second noble metal catalyst containing Pt or Pd in the lower layer of the catalyst coating layer. An aluminum carrier may comprise an aluminum carrier with added lantana (lanthanum oxide added).
    [023] According to the above description, the lower layer of the catalyst coating layer comprises of a ceria-zirconia compound oxide containing at least one additional element selected from the group consisting of praseodymium (Pr), lanthanum (La ), and yttrium (Y) and having an ordered pyrochlore-like structure. In order that ceria-zirconia compound oxide sufficiently exerts its properties, the ceria-zirconia compound oxide is preferably present in the lower layer of the catalyst coating layer in an amount of 1g/L or more, particularly 5 g/l or more, and more particularly 7.5 g/l or more with respect to the volume of substrate. Even though conventional OSC materials cannot sufficiently exert their properties due to the temperature of the lower layer of the catalyst coating layer being below said upper layer of the catalyst coating layer, the oxide of ceria-zirconia compound used in the present invention can exert the oxygen absorption/release capacity even at relatively low temperatures and therefore, its function would not deteriorate significantly when being employed in the lower layer. In addition, ceria-zirconia composite oxide has a small specific surface area and is therefore unlikely to adsorb sulfur oxide, indicating that an increase in the amount of ceria-zirconia composite oxide employed does not cause an increase. in the amount of H2S emissions. Considering the balance between the effect of improving the purity capacity of NOx or such element and the amount of ceria-zirconia composite oxide employed, the ceria-zirconia composite oxide is preferably present in the lower layer of the coating layer of catalyst in an amount of 20 g/l or less, particularly 15 g/l or less, and more particularly 12 g/l or less with respect to the volume of substrate. Typically, the oxide of ceria-zirconia compound is present in the lower layer of the catalyst coating layer in a preferential amount of 1 to 20 g/L in relation to the volume of the substrate.
    [024] The lower layer of the catalyst coating layer further comprises, as an OSC material, preferably a ceria-zirconia compound oxide, particularly preferably a ceria-zirconia compound oxide having a higher content of zirconia in relation to ceria (ZC). The expression “a broad content of zirconia in relation to ceria” used in this report means that the proportion by weight of zirconia contained in a compound oxide is greater than that referring to the ceria contained in the composition. With respect to abundance ratio, the ratio by weight of ceria:zirconia in the ZC material is preferably within the range of 1:1.1 to 1:5, particularly 1:1.5 to 1:3. The ZC material has higher oxygen absorption/release efficiency than that of a CZ material and therefore the use of the ZC material enables the minimization of the amount of Ce to be used, which can lead to a reduction in the activity of noble metals such as the Rh.
    [025] In addition, the lower layer of the catalyst coating layer may contain a barium compound such as barium sulfate (BaSO4). Barium sulphate can be used as an agent that controls the viscosity of the slurry to form a catalyst coating. Furthermore, it is known that barium sulfate is thermally decomposed when exposed to heat so that it is supported as Ba oxide in a surrounding constituent material, and the resulting Ba oxide functions temporarily store the stored NOx contained in an exhaust gas. (The top layer of the catalyst coating layer)
    [026] In the exhaust gas purification catalyst of the present invention, the top layer of the catalyst coating layer contains, as a first noble metal catalyst, Rh, and may further contain Pt or Pd. A first noble metal catalyst may contain only Rh, a mixture of Rh and Pt only, a mixture of Rh and Pd only, or a mixture of only Rh, Pt, and Pd. Rh mainly contributes to the reduction and purification of NOx. As in the case of the lower layer, a first noble metal catalyst is supported together with a carrier. Examples of the carrier include, but are not particularly limited to, arbitrary metal oxides generally employed as catalyst carriers, such as aluminum (Al2O3), zirconia (ZrO2), silica (SiO2), titanium (TiO2), and any combinations of the same. A carrier for a first noble metal catalyst containing Rh in the upper layer of the catalyst coating layer preferably comprises of a ceria-zirconia compound oxide, particularly of a ceria-zirconia compound oxide having a higher content of zirconia than ceria (ZC), able to work with a OSC material. Furthermore, the durability of the catalyst coating layer can be improved by blending aluminum having high thermal stability with the catalyst coating layer in addition to the carrier. (Substrate and catalyst coating)
    [027] A substrate employed to be the exhaust gas purification catalyst of the present invention is not restricted in particular, being generally employed as a material within a honeycomb structure incorporating many cells that can be employed as substrates. Examples of such material include: ceramic materials exhibiting thermal stability such as cordierite (2MgO ■ 2AI2O3 ■ 5SiO2), aluminum, zirconium, and silicon carbides and noble metal in sheet metal form such as stainless steel. It is possible to form a catalyst coating layer on a substrate by a well-known method comprising, for example, decanting the slurry prepared by the suspension materials into distilled water and a binder onto a substrate and venting away by through a fan an unnecessary portion of the slurry.
    [028] In the exhaust gas purification catalyst of the present invention, as shown in Fig. 1, it is preferred that the catalyst coating layer has a portion where the top layer near one end of the exhaust gas purification catalyst from the upstream side of the exhaust gas flow (Fr side) and another portion where the lower layer is not formed near the other end of the exhaust gas purification catalyst from the downstream side of the flow of the exhaust gas (Rr side). By providing a portion where the upper layer is not formed along its side upstream of the exhaust gas, it is possible to facilitate the oxidation and purification of HC and CO in the exhaust gas through the lower layer containing Pt and Pd, as the second noble metal catalysts. This results in the oxidation and purification of HC and CO in the upstream side, making it possible to prevent the generation of a reduction atmosphere, which causes the sulfur dioxide in the exhaust gas to become sulfide. hydrogen (H2S), eliminating the generation of H2S. In addition, by providing a portion where the lower layer is not formed along the downstream side of the exhaust gas flow, it becomes possible to reduce the total amount of catalyst coating to reduce the locations of adsorption of SO2 in the exhaust gas, thus enabling further elimination of H2S generation. Preferably, the lower layer is formed so that the area thereof from the upstream side end of the exhaust gas purification catalyst has a length accounting for from 75% to 85%, particularly from 78% to 82% of the length. total substrate ("a" of Fig. 1), and the top layer is preferably formed so that its area from the downstream side end of the exhaust gas purification catalyst has a length accounting for 75% at 85%, particularly from 78% to 82% of the total length of the substrate ("b" of Fig. 1). (Properties of the exhaust gas purification catalyst of the present invention)
    [029] The exhaust gas purification catalyst of the present invention is particularly suitable for use as UF/C in a dual catalyst system where an initiating catalyst (S/C) and an under-floor catalyst (UF/C) are combined. In such a dual-catalyst system, the S/C installed just below an internal combustion engine is exposed to exhaust gas at elevated temperatures. It has to be that once the UF/C is provided downstream of the S/C where the ingress exhaust gas concentration is small and its temperature is relatively low, a conventional OSC material (for example, pyrochlorine type ZC material) may not sufficiently exert an oxygen absorption/release function. The exhaust gas purification catalyst of the present invention features a catalyst coating layer where a lower layer comprises of a pyrochlorine type ceria-zirconia compound oxide containing a predetermined additional element, and therefore having the capacity to exercise with sufficient oxygen storage capacity even at low temperatures and thermal stability. Therefore, the exhaust gas purification catalyst of the present invention is particularly preferable for use as UF/C. Examples
    [030] The present invention is explained in more detail with reference to the Examples below. However, the present invention is not restricted to the Examples. 1. Preparation of pyrochlorine ZC with added Pr
    [031] First, there was the addition of 1217 g of an aqueous solution containing ammonia in an amount 1.2 times the equivalent of neutralization to obtain a co-precipitate: 442 g of an aqueous solution of cerium nitrate (28 % by mass calculated in terms of CeO2), 590 g of an aqueous solution of zirconium oxynitrate (18% by mass calculated in terms of ZrO2), 100 g of an aqueous solution containing praseodymium nitrate in an amount corresponding to 1.2 g of Pr6O11, 197 g of an aqueous solution containing hydrogen peroxide in an amount corresponding to 1.1 times the molar amount of contained cerium. The co-precipitate obtained was centrifuged and washed with water for ion exchange. The resulting coprecipitate was dried at 110°C for 10 hours or more and sintered at 400°C for 5 hours in air. Thus, a solid solution containing cerium, zirconium, and praseodymium (a solid solution of CeO2-ZrO2-Pr6O11) was obtained. The obtained solid solution was sprayed by means of a sprayer (product name: Wonder-Blender; AS ONE Corporation) so that they presented a particle size equal to or smaller than 75 µm after penetration to obtain a praseodymium-zirconia-ceria solid solution powder.
    [032] Then the 20 g of solid solution powder obtained came to be packaged in a polyethylene bag (volume of 0.05 L), with the removal of the bag aeration and the bag opening was thermally sealed. Subsequently, the bag was subjected to cold isostatic pressure (CIP) at a pressure (molding pressure) of 2000 kgf/cm2 for 1 minute for molding using an isostatic pressing machine (product name: CK4-22-60, Nikkiso Co, Ltd.) for obtaining a molded product from the solid powder of praseodymium-zirconia-ceria solution. The size and weight of the molded product were as follows: length: 4 cm; width: 4 cm; average thickness: 7mm; and weight: approximately 20 g.
    [033] Then, the molded product obtained (2 plates) was placed in a crucible filled with 70 g of activated carbon (internal volume of 8 cm in diameter and 7 cm in height). The crucible was closed with a lid and placed in an electric high-speed heating furnace, followed by heating to 1000°C for further heating for a period of 1 hour and heating to 1700°C (reduction treatment temperature ) for an additional heating period of 4 hours. The temperature was maintained for 5 hours. The temperature was then cooled to 1000°C for a cooling period of 4 hours and then cooled to room temperature by natural thermal radiation. The product obtained from the reduction treatment was heated at 500° for 5 hours in air facing oxidation to obtain a pyrochlore-type ceria-zirconia compound oxide (ZC with Pr pyrochlore added) containing a content rate ( molar ratio) cerium : zirconium : praseodymium 45 : 54 : 1. The ZC with Pr pyrochlore added was sprayed to a particle size of 75 µm or less through penetration.
    [034] The pyrochlore ZC with added Pr was heated to 1100°C for 5 hours in air (high temperature durability test). Then, in order to confirm whether or not the pyrochlor structure came to be maintained, the crystal phase of the treated added Pr pyrochlore ZC was subjected to an X-ray diffraction test. An X-ray diffraction apparatus (product name: RINT-2100; Corporation Rigaku) was employed to measure the X-ray diffraction patterns under the conditions below to obtain the I values(14/29 ) and I(28/29): CuKα radiation: 40 KV; 30 mA; 2θ = 2°/minute.
    [035] Samples from A to E of ZC with added Pr pyrochlore showing differentiated molar ratios of cerium : zirconium : praseodymium were prepared and subjected to high temperature durability tests, and then to X-ray diffraction patterns were measured to obtain values I14/29) and I(28/29) in the manner described above. Table 1 summarizes the results. (Table 1)

    2. Preparation of Catalysts (1) Comparative Example: ZC-free double layer catalyst with added Pr pyrochlorine (a) Bottom layer Pt (Pt (0.2) / Al2O3 (25) + ZC (30) + BaSO4 (2.5))
    [036] The Pt material supported by Al2O3 (material 1) was prepared using an Al2O3 carrier containing La2O3 (1% by mass) and platinum nitrate by an impregnation method. Then material 1, a ceria-zirconia compound oxide containing a molar ratio of cerium: zirconium of 46 : 54 (ZC), barium sulfate (BaSO4), and an Al2O3 binder added to distilled water with stirring and suspension for obtaining semi-fluid paste 1.
    [037] The slurry 1 was decanted onto a honeycomb cordierite substrate for coating the substrate wall surface with ventilation to drive away an unnecessary portion of the slurry 1 with the employment of a fan. The coating was initialized from the upstream side of the exhaust gas flow (Fr side) so that a coating is formed over the area whose length coming from the upstream side end is within 80% of the total length of the substrate (see Fig. 1, a = 80%). The coating was controlled so that the contents of material 1, ZC, and BaSO4 in the render coating were, respectively, 25 g/L (Pt: 0.2 g/L), 30 g/L, and 2.5 g/L, in relation to the volume of the substrate. After coating, moisture was removed using a dryer at 120°C for 2 hours, and the resulting compound was sintered at 500°C in an electric furnace for 2 hours. (b) Upper Rh Layer (Rh (0.12) / ZrO2 (40) + Al2O3 (20))
    [038] The Rh/ZC material supported by the ZC (material 2) was prepared by employing a ceria-zirconia composite oxide carrier containing a molar ratio of cerium : zirconium of 46 : 54 (ZC) and rhodium nitrate through of an impregnation method. Then, material 2, Al2O3, and an Al2O3 agglutinator were added together with distilled water with stirring and suspension to obtain the semi-fluid paste 2.
    [039] The slurry 2 was decanted onto a honeycomb structured substrate, where a coating is formed according to item (a) above with ventilation removing an unnecessary portion of the slurry 2 by employing a fan. The coating was initialized from a downstream side of the exhaust gas flow (Rr side) so that a coating was formed over the area within 80% of the total length of the substrate from the downstream side edge (see Fig. 1, b=80%). The coating was controlled in such a way that the contents of material 2 and Al2O3 in the coating became, respectively, 40 g/L (Rh: 0.12 g/L) and 20 g/L, in relation to the volume of the substrate . After coating, moisture was removed using a dryer at 120°C for 2 hours, with the resulting compound being sintered at 500°C in an electric furnace for 2 hours. (2) Examples 1 to 3
    [040] A catalyst was prepared in the manner described in Comparative Example 1, except the Pr-added pyrochlore ZC containing a molar ratio of cerium: zirconium: praseodymium of 45: 54: 1 (A in table 1) came to be added when of slurry preparation 1. The ZC contents with Pr pyrochlore added in the coating were adjusted to 5 g/L, 10 g/L, and 20 g/L, respectively, in Examples 1, 2, and 3, in in relation to the volume of the substrate. (3) Comparative Examples 2 and 3 A catalyst was prepared in the manner described as in Comparative Example 1, except with a cerium-zirconia compound oxide having a molar ratio of cerium:zirconium of 46 : 54 (ZC) was added when adding preparing the semi-fluid mixture 1. The ZC contents in a coating were adjusted to 10 g/L and 30 g/L in Comparative Examples 2 and 3, respectively, in relation to the volume of the substrate. (4) Comparative Example 4
    [041] A Pr-free pyrochlore-type ceria-zirconia compound oxide (containing cerium and zirconium containing a cerium:zirconium molar ratio of 46:54) (conventional pyrochlore ZC) came to be prepared in the manner described in item (1) above with the exception of praseodymium nitrate which was not used. A catalyst was prepared in the manner described above in Comparative Example 1 except that conventional pyrochlore ZC was added when preparing slurry 1. The content of conventional pyrochlore ZC in a coating was adjusted to 10 g/L in in relation to the volume of the substrate.
    [042] Table 2 lists the compositions of the upper and lower layers of catalysts in Examples 1 to 3 and Comparative Examples 1 to 4. (Table 2)

    3. Evaluation (1) Durability Test
    [043] Each catalyst was attached to an exhaust system of a V-type 8-cc gasoline engine (4.3 L) and subjected to a 50-hour durability test at a catalyst bed temperature of 950 °C through conditions including spare feedback switching, fuel cutoff, rich mix, and lean within one minute. (2) Evaluation of NOx purification rate by variable A/F rate
    [044] Each catalyst submitted to the durability test came to be installed, as a UF/C, in a present engine provided with deteriorated S/C (Pd/Rh catalyst). The inlet gas temperature was set at 400°C. The measurement of the amount of NOx emissions was made when the A/F of the inlet gas atmosphere was induced to oscillate periodically between rich regions and the surroundings (14.0-15.0). (3) Assessing the amount of H2S emissions during acceleration
    [045] Each catalyst was installed in an engine where a fuel incorporating a high sulfur content came to be supplied in such a way that the catalyst adsorbed the sulfur. Next, the amount of hydrogen sulfide emissions during engine acceleration came to be gauged. The evaluation was based on the rate with respect to the level of Comparative Example 1 where ZC with pyrochlore and Pr added, conventional ZC, or ZC with additional pyrochlore were not added. 4. Results
    [046] Fig. 2 consists of a graph showing the relationship between the amounts of ZC with pyrochlore and Pr added, conventional ZC, or conventional pyrochlorine ZC added to the lower layer and the NOx purification rate. even a small amount of ZC with pyrochlore and Pr added came to be effective, with the effect of increasing the maximum NOx purification rate being 1.5 times. Bearing in mind that when conventional ZC was used, as the added amount increased, the NOx purification rate increased. However, it was determined that comparable effects could not be obtained without a significant increase in the amount added compared to the amount of ZC with pyrochlore and Pr added. Furthermore, when the oxide of ceria-zirconia compound free of additional elements, such as Pr (ZC with conventional pyrochlore), was used, the effect obtained was much lower than that obtained with the use of conventional ZC.
    [047] Fig. 3 consists of a graph showing the relationship between the amount of ZC with pyrochlore and Pr added or an additional ZC added and the NOx purification rate with variable A/F rate. When conventional ZC is used, the amount of H2S emissions increased proportionally to an increase in the amount of added conventional ZC. On the other hand, when ZC was used with pyrochlore and Pr added, the amount of H2S emissions did not increase substantially.
    [048] All references, including any publications, patents or patent applications mentioned in this report are included as full references.
    权利要求:
    Claims (5)
    [0001]
    1. Exhaust gas purification catalyst, CHARACTERIZED in that it comprises a substrate and a catalyst coating layer formed on the substrate, wherein the catalyst coating layer has at least one upper layer that contacts directly with an exhaust gas flowing into the catalyst, and a lower layer, the upper layer comprising a carrier and a carrier-supported first noble metal catalyst, wherein the first noble metal catalyst contains at least rhodium, the lower layer comprises a carrier, a second carrier-supported noble metal catalyst, and a ceria-zirconia compound oxide having an ordered array structure of the pyrochlore type, wherein the second noble metal catalyst contains at least platinum or palladium, wherein the ceria-zirconia compound oxide contains at least one additional element selected from the group consisting of praseodymium, lant anium, and yttrium in 0.5 to 5.0 mole % in relation to the total amount of cation, and the molar ratio of cerium + additional element: zirconium is within the range of 43:57 to 48:52, and where the catalyst coating layer has: a portion in which the top layer is not formed on the upstream side end of the exhaust gas purification catalyst; a portion in which the lower layer is formed below the upper layer; and a portion in which the lower layer is not formed at the downstream side end of the exhaust gas purification catalyst.
    [0002]
    2. Exhaust gas purification catalyst, according to claim 1, CHARACTERIZED by the fact that the additional element contained in the oxide of ceria-zirconia compound is praseodymium.
    [0003]
    3. Exhaust gas purification catalyst, according to claim 1, CHARACTERIZED by the fact that the lower layer contains the oxide of ceria-zirconia compound in an amount ranging from 1 to 20 g/L in relation to the volume of substrate .
    [0004]
    4. Exhaust gas purification catalyst, according to claim 2, CHARACTERIZED by the fact that the lower layer contains the oxide of ceria-zirconia compound in an amount ranging from 1 to 20 g/L in relation to the volume of substrate .
    [0005]
    5. Exhaust gas purification catalyst according to claim 1, CHARACTERIZED by the fact that the lower layer is formed over the area whose length is within the range of 75% to 85% of the total length of the substrate from the end upstream side of the exhaust gas purification catalyst; and the top layer is formed over the area whose length is within the range of 75% to 85% of the total length of the substrate from the downstream side end of the exhaust gas purification catalyst.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US2671638A|1952-04-08|1954-03-09|Safway Steel Products Inc|Safety device|
    JPH064133B2|1986-01-20|1994-01-19|株式会社豊田中央研究所|Zirconia carrier|
    CN101291731B|2005-10-24|2012-07-04|丰田自动车株式会社|Catalyst support and catalyst for exhaust-gas purification|
    CA2648314C|2006-03-28|2011-11-15|Kabushiki Kaisha Toyota Chuo Kenkyusho|Catalyst for purification of exhaust gas, regeneration method for the catalyst, and apparatus and method for purification of exhaust gas using the catalyst|
    EP2127744B1|2007-02-01|2018-07-18|Daiichi Kigenso Kagaku Kogyo Co., Ltd.|Exhaust gas purification apparatus comprising a catalyst system and exhaust gas purification method|
    JP2009285604A|2008-05-30|2009-12-10|Toyota Motor Corp|Catalyst for cleaning exhaust gas|
    US20090324468A1|2008-06-27|2009-12-31|Golden Stephen J|Zero platinum group metal catalysts|
    JP4751917B2|2008-06-30|2011-08-17|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    WO2010064497A1|2008-12-03|2010-06-10|第一稀元素化学工業株式会社|Exhaust gas purifying catalyst, exhaust gas purifying apparatus using same, and exhaust gas purifying method|
    JP5253233B2|2009-02-27|2013-07-31|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    JP5565569B2|2009-04-07|2014-08-06|株式会社豊田中央研究所|Exhaust gas purification catalyst|
    US8530372B2|2009-07-22|2013-09-10|Basf Corporation|Oxygen storage catalyst with decreased ceria reduction temperature|
    JP5547539B2|2010-04-13|2014-07-16|株式会社豊田中央研究所|Ceria-zirconia composite oxide, production method thereof, and exhaust gas purification catalyst using the ceria-zirconia composite oxide|
    JP5567923B2|2010-07-23|2014-08-06|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    JP5240275B2|2010-10-22|2013-07-17|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    JP5287884B2|2011-01-27|2013-09-11|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    BR112013019650B1|2011-02-01|2019-12-17|Umicore Shokubai Japan Co Ltd|catalyst and method for purifying exhaust gases|
    JP5724856B2|2011-12-02|2015-05-27|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    JP5763711B2|2013-06-13|2015-08-12|株式会社豊田中央研究所|Ceria-zirconia composite oxide, production method thereof, and exhaust gas purification catalyst using the ceria-zirconia composite oxide|
    JP5763722B2|2013-08-09|2015-08-12|株式会社豊田中央研究所|Ceria-zirconia composite oxide, production method thereof, and exhaust gas purification catalyst using the ceria-zirconia composite oxide|
    JP5883425B2|2013-10-04|2016-03-15|株式会社豊田中央研究所|Ceria-zirconia composite oxide, production method thereof, and exhaust gas purification catalyst using the ceria-zirconia composite oxide|
    JP6133835B2|2014-12-12|2017-05-24|トヨタ自動車株式会社|Exhaust gas purification catalyst|JP6133835B2|2014-12-12|2017-05-24|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    WO2017130917A1|2016-01-26|2017-08-03|新日本電工株式会社|Ceria·zirconia-based composite oxide oxygen absorption/release material, exhaust gas cleaning catalyst and honeycomb structure for exhaust gas cleaning|
    GB2554859A|2016-10-04|2018-04-18|Johnson Matthey Plc|NOx adsorber catalyst|
    JP6693406B2|2016-12-20|2020-05-13|三菱自動車工業株式会社|Exhaust gas purification device|
    SG10202003942VA|2017-03-28|2020-05-28|Mitsubishi Hitachi Power Sys|Ship desulfurization device, hull integrated desulfurization device, ship, and method for assembling hull integrated desulfurization device to ship|
    JP6753811B2|2017-04-19|2020-09-09|トヨタ自動車株式会社|Exhaust gas purification catalyst|
    EP3616789A4|2017-04-28|2021-01-06|Umicore Shokubai Japan Co., Ltd.|Exhaust gas purification catalyst and exhaust gas purification method using same|
    JP6865664B2|2017-09-25|2021-04-28|株式会社キャタラー|Oxidation catalyst device for exhaust gas purification|
    JP6954796B2|2017-10-06|2021-10-27|トヨタ自動車株式会社|Exhaust gas purification catalyst for automobiles|
    CN110026175B|2019-04-17|2020-10-23|山东国瓷功能材料股份有限公司|Cerium-zirconium composite oxide and application thereof in catalyzing CO oxidation reaction|
    法律状态:
    2019-09-17| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-04-06| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2021-05-25| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-07-20| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 11/12/2015, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2014-252022|2014-12-12|
    JP2014252022A|JP6133836B2|2014-12-12|2014-12-12|Exhaust gas purification catalyst|
    PCT/JP2015/006201|WO2016092860A1|2014-12-12|2015-12-11|Exhaust gas purifying catalyst|
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