JP7172902B2 - oxygen storage material - Google Patents
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- JP7172902B2 JP7172902B2 JP2019138818A JP2019138818A JP7172902B2 JP 7172902 B2 JP7172902 B2 JP 7172902B2 JP 2019138818 A JP2019138818 A JP 2019138818A JP 2019138818 A JP2019138818 A JP 2019138818A JP 7172902 B2 JP7172902 B2 JP 7172902B2
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- 229910052760 oxygen Inorganic materials 0.000 title claims description 105
- 239000001301 oxygen Substances 0.000 title claims description 103
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims description 98
- 239000011232 storage material Substances 0.000 title claims description 66
- 238000003860 storage Methods 0.000 claims description 31
- 239000003054 catalyst Substances 0.000 claims description 22
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 20
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 239000002131 composite material Substances 0.000 description 23
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 229910052802 copper Inorganic materials 0.000 description 9
- 239000007789 gas Substances 0.000 description 9
- 229910052758 niobium Inorganic materials 0.000 description 9
- 239000000203 mixture Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 5
- 150000002926 oxygen Chemical class 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910052684 Cerium Inorganic materials 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 4
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 4
- 239000008188 pellet Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 3
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000009694 cold isostatic pressing Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 240000007594 Oryza sativa Species 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Description
本開示は、酸素吸蔵材に関する。 The present disclosure relates to oxygen storage materials.
自動車等のための内燃機関、例えば、ガソリンエンジン又はディーゼルエンジン等から排出される排ガス中には、例えば、一酸化炭素（ＣＯ）、炭化水素（ＨＣ）、及び窒素酸化物（ＮＯｘ）等の成分が含まれている。 Exhaust gases emitted from internal combustion engines such as automobiles, such as gasoline or diesel engines, contain components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). It is included.
このため、一般的には、これらの成分を浄化するための排ガス浄化装置が内燃機関に取り付けられており、この排ガス浄化装置内に取り付けられた排ガス浄化触媒によってこれらの成分がほとんど浄化されている。 For this reason, in general, an exhaust gas purifying device for purifying these components is attached to the internal combustion engine, and most of these components are purified by an exhaust gas purifying catalyst attached in the exhaust gas purifying device. .
このような排ガス浄化触媒に含まれる酸素吸蔵材の例として、セリア系の酸素吸蔵材が知られている。セリアは、リーン雰囲気で酸素を吸蔵し、リッチ雰囲気で酸素を放出する酸素吸蔵能（ＯＳＣ：Ｏｘｙｇｅｎ Ｓｔｏｒａｇｅ Ｃａｐａｃｉｔｙ）特性を有している。このため、セリア系の酸素吸蔵材を三元触媒等で好適に採用することができる。 A ceria-based oxygen storage material is known as an example of the oxygen storage material contained in such an exhaust gas purifying catalyst. Ceria has an oxygen storage capacity (OSC) characteristic of absorbing oxygen in a lean atmosphere and releasing oxygen in a rich atmosphere. Therefore, the ceria-based oxygen storage material can be suitably used in a three-way catalyst or the like.
例えば、特許文献１は、酸素吸蔵材として、セリア―ジルコニア複合酸化物を用いることを開示している。 For example, Patent Document 1 discloses using a ceria-zirconia composite oxide as an oxygen storage material.
排ガス浄化触媒の排ガス浄化性能を向上させる観点から、より酸素吸蔵能が高い酸素吸蔵材が求められている。特に、より低い温度域、例えば３００℃以下の温度における酸素吸蔵能を有する酸素吸蔵材が求められている。 From the viewpoint of improving the exhaust gas purification performance of an exhaust gas purification catalyst, an oxygen storage material with a higher oxygen storage capacity is desired. In particular, there is a demand for an oxygen storage material having an oxygen storage capacity in a lower temperature range, for example, at a temperature of 300° C. or less.
本開示は、高い酸素吸蔵能、特に低い温度域において高い酸素吸蔵能を有する酸素吸蔵材を提供することを目的とする。 An object of the present disclosure is to provide an oxygen storage material having a high oxygen storage capacity, especially in a low temperature range.
本開示者は、以下の手段により上記課題を達成することができることを見出した：
《態様１》
Ｃｕ及びＮｂの複合酸化物である、酸素吸蔵材。
《態様２》
前記複合酸化物が、Ｃｕ３Ｎｂ２Ｏ８又はＣｕＮｂ２Ｏ６である、態様１に記載の酸素吸蔵材。
《態様３》
前記複合酸化物が単相である、態様１又は２に記載の酸素吸蔵材。
《態様４》
３００℃において、８００．０μｍｏｌ／ｇ以上の酸素吸蔵量を有する、態様１～３のいずれか一つに記載の酸素吸蔵材。
《態様５》
触媒金属が担持されている、態様１～４のいずれか一つに記載の酸素吸蔵材。
《態様６》
前記触媒金属の前記酸素吸蔵材に対する割合が０質量％超５質量％以下である、態様５に記載の酸素吸蔵材。
《態様７》
前記触媒金属が、Ｐｔ、Ｐｄ、又はＲｈである、態様５又は６に記載の酸素吸蔵材。
The present discloser has found that the above objects can be achieved by the following means:
<<Aspect 1>>
An oxygen storage material which is a composite oxide of Cu and Nb.
<<Aspect 2>>
The oxygen storage material according to aspect 1 , wherein the composite oxide is Cu3Nb2O8 or CuNb2O6 .
<<Aspect 3>>
The oxygen storage material according to aspect 1 or 2, wherein the composite oxide is a single phase.
<<Aspect 4>>
The oxygen storage material according to any one of aspects 1 to 3, which has an oxygen storage capacity of 800.0 μmol/g or more at 300°C.
<<
The oxygen storage material according to any one of aspects 1 to 4, wherein a catalyst metal is supported.
<<Aspect 6>>
The oxygen storage material according to
<<Aspect 7>>
7. The oxygen storage material according to
本開示によれば、高い酸素吸蔵能、特に低い温度域において高い酸素吸蔵能を有する酸素吸蔵材を提供することができる。 According to the present disclosure, it is possible to provide an oxygen storage material having a high oxygen storage capacity, especially in a low temperature range.
以下、本開示の実施の形態について詳述する。なお、本開示は、以下の実施の形態に限定されるのではなく、開示の本旨の範囲内で種々変形して実施できる。 Hereinafter, embodiments of the present disclosure will be described in detail. It should be noted that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the disclosure.
本開示の酸素吸蔵材は、Ｃｕ及びＮｂの複合酸化物である。 The oxygen storage material of the present disclosure is a composite oxide of Cu and Nb.
従来の排ガス浄化触媒における酸素吸蔵材として用いられてきたセリア－ジルコニア複合酸化物は、パイロクロア相またはκ相を有しており、高温条件下において高い酸素貯蔵能を有している。しかしながら、セリウムはセリウム１個に対して酸素原子を０．５個吸蔵することができるが、一方で、セリア－ジルコニア複合酸化物のセリウムとジルコニウムの組成比は１：１であり、セリア－ジルコニア複合酸化物は、既にその材料自身が持つセリウムの９割以上が酸素吸蔵能を発現しており、すなわち、既に理論限界程の酸素吸蔵能を示しており、酸素吸蔵量において増大の余地が見込まれない。 Ceria-zirconia composite oxide, which has been used as an oxygen storage material in conventional exhaust gas purifying catalysts, has a pyrochlore phase or a κ phase and has a high oxygen storage capacity under high temperature conditions. However, cerium can occlude 0.5 oxygen atoms per cerium, while the composition ratio of cerium and zirconium in the ceria-zirconia composite oxide is 1:1. In composite oxides, more than 90% of the cerium contained in the material itself already exhibits oxygen storage capacity. can't
また、セリア－ジルコニア複合酸化物の酸化物構造内の酸素を出し入れするための活性エネルギーが高いため、低温域、例えば３００℃以下の低温においては十分に酸素を吸蔵することが出来ない。 In addition, since the active energy for taking in and out oxygen in the oxide structure of the ceria-zirconia composite oxide is high, it is not possible to sufficiently occlude oxygen in a low temperature range, for example, a low temperature of 300° C. or less.
本開示者らは、Ｃｕ及びＮｂの複合酸化物を酸素吸蔵材として用いることにより、高い酸素吸蔵能、特に低い温度域において高い酸素吸蔵能が得られることを見出した。 The present inventors have found that by using a composite oxide of Cu and Nb as an oxygen storage material, a high oxygen storage capacity, especially in a low temperature range, can be obtained.
本開示の酸素吸蔵材は、例えば３００℃において、８００．０μｍｏｌ／ｇ以上の酸素吸蔵量を有していることができる。ここで、酸素吸蔵量は、酸素吸蔵材が吸蔵することができる酸素原子の量（μｍｏｌ）を酸素吸蔵材の質量（ｇ）で除した値である。 The oxygen storage material of the present disclosure can have an oxygen storage capacity of 800.0 μmol/g or more at 300° C., for example. Here, the oxygen storage capacity is a value obtained by dividing the amount (μmol) of oxygen atoms that the oxygen storage material can store by the mass (g) of the oxygen storage material.
本開示の酸素吸蔵材の３００℃における酸素吸蔵量は、８００．０μｍｏｌ／ｇ以上、８５０．０μｍｏｌ／ｇ以上、又は９００．０μｍｏｌ／ｇ以上であってよく、１０００．０μｍｏｌ／ｇ以下、９５０．０μｍｏｌ／ｇ以下、又は９００．０μｍｏｌ／ｇ以下であってよい。 The oxygen storage capacity at 300° C. of the oxygen storage material of the present disclosure may be 800.0 μmol/g or more, 850.0 μmol/g or more, or 900.0 μmol/g or more, and may be 1000.0 μmol/g or less, 950.0 μmol/g or more. It may be 0 μmol/g or less, or 900.0 μmol/g or less.
〈複合酸化物〉
Ｃｕ及びＮｂの複合酸化物は、Ｃｕ及びＮｂを含有しており、酸素吸蔵能を有するものであれば特に限定されないが、例えばＣｕ３Ｎｂ２Ｏ８又はＣｕＮｂ２Ｏ６であることが好ましい。
<Composite oxide>
The composite oxide of Cu and Nb contains Cu and Nb and is not particularly limited as long as it has an oxygen storage capacity .
複合酸化物がＣｕ３Ｎｂ２Ｏ８である場合、低温域、例えば３００℃付近において高い酸素吸蔵能を有すると共に、高温域、例えば５００℃付近又は７００℃付近においても高い酸素吸蔵能を有する。また、複合酸化物がＣｕＮｂ２Ｏ６である場合、低温域、例えば３００℃付近において特に高い酸素吸蔵能を有する。 When the composite oxide is Cu 3 Nb 2 O 8 , it has a high oxygen storage capacity in a low temperature range, for example around 300°C, and also has a high oxygen storage capacity in a high temperature range, for example around 500°C or 700°C. Moreover, when the composite oxide is CuNb 2 O 6 , it has a particularly high oxygen storage capacity in a low temperature range, for example, around 300°C.
Ｃｕ及びＮｂの複合酸化物は、単相であってよい。
〈触媒金属〉
The composite oxide of Cu and Nb may be single-phase.
<Catalyst metal>
本開示の酸素吸蔵材は、触媒金属が担持されていることができる。 The oxygen storage material of the present disclosure can carry a catalytic metal.
触媒金属の酸素吸蔵材に対する割合は、０質量％超５質量％以下であってよい。触媒金属の酸素吸蔵材に対する割合は、０質量％超、１質量％以上、又は２質量％以上であってよく、５質量％以下、４質量％以下、又は３質量％以下であってよい。 The ratio of the catalyst metal to the oxygen storage material may be more than 0% by mass and 5% by mass or less. The ratio of the catalyst metal to the oxygen storage material may be more than 0% by mass, 1% by mass or more, or 2% by mass or more, and may be 5% by mass or less, 4% by mass or less, or 3% by mass or less.
触媒金属は、例えば貴金属又は貴金属と他の金属との合金を挙げることができる。貴金属としては、例えばＰｔ、Ｐｄ、又はＲｈを挙げることができるが、これらに限定されない。 Catalyst metals can include, for example, noble metals or alloys of noble metals with other metals. Noble metals may include, but are not limited to, Pt, Pd, or Rh, for example.
〈製造方法〉
本開示の酸素吸蔵材は、Ｃｕ及びＮｂの複合酸化物を得ることができる任意の方法によって製造することができる。
<Production method>
The oxygen storage material of the present disclosure can be produced by any method capable of obtaining a composite oxide of Cu and Nb.
本開示の酸素吸蔵材は、例えばＣｕ酸化物、例えばＣｕ２Ｏと、Ｎｂ酸化物、例えばＮｂ２Ｏ５とを混合して焼成することによって得ることができるが、この方法に限定されない。 The oxygen storage material of the present disclosure can be obtained, for example, by mixing a Cu oxide such as Cu 2 O and a Nb oxide such as Nb 2 O 5 and firing the mixture, but is not limited to this method.
本開示の酸素吸蔵材に触媒金属を担持する方法は、酸素吸蔵材に触媒金属を担持させることができる任意の方法によって行うことができる。このような方法としては、例えば含浸法によって触媒金属を酸素吸蔵材に担持させることができるが、この方法に限定されない。 The method of supporting the catalyst metal on the oxygen storage material of the present disclosure can be carried out by any method capable of supporting the catalyst metal on the oxygen storage material. As such a method, the catalyst metal can be supported on the oxygen storage material by, for example, an impregnation method, but the method is not limited to this method.
《実施例１》
Ｃｕ２ＯとＮｂ２Ｏ５とをモル比が３：２になるように秤量してメノウ乳鉢に入れ、１時間磨砕混合した。その後、冷間等方圧加圧法を用いて１９６ｋＮで圧粉してペレットを得た。このペレットを８００℃で３６時間空気焼成し、続けて９５０℃で４０時間空気焼成して、複合酸化物のペレットを得た。得られた複合酸化物をメノウ乳鉢で磨砕したのち、少量の水に懸濁し、この複合酸化物に対してＰｄの量が１質量％となるように硝酸パラジウム硝酸溶液を滴下し、十分に撹拌した後１２０℃で蒸発乾固させた。その後、４００℃で２時間水素還元することにより、Ｐｄ粒子が担持されている酸素吸蔵材を得た。
<<Example 1>>
Cu 2 O and Nb 2 O 5 were weighed so that the molar ratio was 3:2, placed in an agate mortar, and ground and mixed for 1 hour. After that, it was compacted at 196 kN using a cold isostatic pressing method to obtain pellets. The pellets were air-fired at 800° C. for 36 hours and then air-fired at 950° C. for 40 hours to obtain composite oxide pellets. After grinding the obtained composite oxide with an agate mortar, it is suspended in a small amount of water, and a palladium nitrate nitric acid solution is added dropwise so that the amount of Pd is 1% by mass with respect to the composite oxide. After stirring it was evaporated to dryness at 120°C. After that, hydrogen reduction was performed at 400° C. for 2 hours to obtain an oxygen storage material carrying Pd particles.
なお、この酸素吸蔵材は、酸素吸蔵材としてのＣｕ３Ｎｂ２Ｏ８に金属触媒としてのＰｄが担持された構成を有していた。 This oxygen storage material had a structure in which Pd was supported as a metal catalyst on Cu 3 Nb 2 O 8 as the oxygen storage material.
《実施例２》
Ｃｕ２ＯとＮｂ２Ｏ５とをモル比が１：２になるように秤量したことを除いて、実施例１と同様にして、Ｐｄ粒子が担持されている酸素吸蔵材を得た。
<<Example 2>>
An oxygen storage material supporting Pd particles was obtained in the same manner as in Example 1, except that Cu 2 O and Nb 2 O 5 were weighed so that the molar ratio was 1:2.
なお、この酸素吸蔵材は、酸素吸蔵材としてのＣｕＮｂ２Ｏ６に金属触媒としてのＰｄが担持された構成を有していた。 This oxygen storage material had a structure in which Pd was supported as a metal catalyst on CuNb 2 O 6 as the oxygen storage material.
《比較例１》
硝酸セリウムとオキシ硝酸ジルコニルとのモル比が１：１となるように水溶液を調製し、硝酸セリウムに対し６当量のクエン酸を加え、ホットスターラーにて攪拌しながら１００℃以上で加熱して、溶液を乾固させた。その後、電気炉にて１２０℃で８時間以上加熱し、得られた固体をメノウ乳鉢で十分に磨砕し、アルミナルツボに入れて７００℃で３時間空気焼成した。焼成後の粉末を、水素流下１２００℃で２４時間還元し、複合酸化物としてのＣｅ２Ｚｒ２Ｏ７を得た。得られた複合酸化物をメノウ乳鉢で磨砕したのち、少量の水に懸濁し、この複合酸化物に対してＰｄの量が１質量％となるように硝酸パラジウム硝酸溶液を滴下し、十分に撹拌した後１２０℃で蒸発乾固させた。その後、４００℃で２時間水素還元することにより、Ｐｄ粒子が担持されている酸素吸蔵材を得た。
<<Comparative example 1>>
An aqueous solution was prepared so that the molar ratio of cerium nitrate and zirconyl oxynitrate was 1:1, 6 equivalents of citric acid was added to the cerium nitrate, and the mixture was heated at 100°C or higher while stirring with a hot stirrer. The solution was allowed to dry. After that, the mixture was heated in an electric furnace at 120° C. for 8 hours or longer, and the obtained solid was thoroughly ground in an agate mortar, placed in an alumina crucible, and calcined in air at 700° C. for 3 hours. The fired powder was reduced under flowing hydrogen at 1200° C. for 24 hours to obtain Ce 2 Zr 2 O 7 as a composite oxide. After grinding the obtained composite oxide with an agate mortar, it is suspended in a small amount of water, and a palladium nitrate nitric acid solution is added dropwise so that the amount of Pd is 1% by mass with respect to the composite oxide. After stirring it was evaporated to dryness at 120°C. After that, hydrogen reduction was performed at 400° C. for 2 hours to obtain an oxygen storage material carrying Pd particles.
なお、この酸素吸蔵材は、酸素吸蔵材としてのＣｅ２Ｚｒ２Ｏ７に金属触媒としてのＰｄが担持された構成を有していた。 This oxygen storage material had a structure in which Pd was supported as a metal catalyst on Ce 2 Zr 2 O 7 as the oxygen storage material.
《比較例２》
市販のＣｕ２Ｏを少量の水に懸濁し、Ｃｕ２Ｏに対してＰｄの量が１質量％となるように硝酸パラジウム硝酸溶液を滴下し、十分に撹拌した後１２０℃で蒸発乾固させた。その後、４００℃で２時間水素還元することにより、Ｐｄ粒子が担持されている酸素吸蔵材を得た。
<<Comparative Example 2>>
Commercially available Cu 2 O was suspended in a small amount of water, a palladium nitrate nitric acid solution was added dropwise so that the amount of Pd was 1% by mass with respect to Cu 2 O, and the mixture was thoroughly stirred and then evaporated to dryness at 120°C. rice field. After that, hydrogen reduction was performed at 400° C. for 2 hours to obtain an oxygen storage material carrying Pd particles.
なお、この酸素吸蔵材は、酸素吸蔵材としてのＣｕ２Ｏに金属触媒としてのＰｄが担持された構成を有していた。 This oxygen storage material had a structure in which Pd as a metal catalyst was supported on Cu 2 O as an oxygen storage material.
《比較例３》
市販のＮｂ２Ｏ５を少量の水に懸濁し、Ｃｕ２Ｏに対してＰｄの量が１質量％となるように硝酸パラジウム硝酸溶液を滴下し、十分に撹拌した後１２０℃で蒸発乾固させた。その後、４００℃で２時間水素還元することにより、Ｐｄ粒子が担持されている酸素吸蔵材を得た。
<<Comparative Example 3>>
Commercially available Nb 2 O 5 was suspended in a small amount of water, a palladium nitrate nitric acid solution was added dropwise so that the amount of Pd in Cu 2 O was 1% by mass, and the mixture was thoroughly stirred and then evaporated to dryness at 120°C. let me After that, hydrogen reduction was performed at 400° C. for 2 hours to obtain an oxygen storage material carrying Pd particles.
なお、この酸素吸蔵材は、酸素吸蔵材としてのＮｂ２Ｏ５に金属触媒としてのＰｄが担持された構成を有していた。 This oxygen storage material had a structure in which Pd was supported as a metal catalyst on Nb 2 O 5 as the oxygen storage material.
《試験１：酸素吸蔵能の評価》
〈試験方法〉
固定床流通式反応装置を用いて酸素吸蔵能を評価した。
<<Test 1: Evaluation of oxygen storage capacity>>
<Test method>
The oxygen storage capacity was evaluated using a fixed bed flow reactor.
実施例１及び２、並びに比較例１～３の酸素吸蔵材を冷間等方圧加圧法にて１９６ｋＮで圧粉した後、ふるいを用いてペレット化し、そのペレットを２ｇ用いて評価を行った。 The oxygen storage materials of Examples 1 and 2 and Comparative Examples 1 to 3 were compacted at 196 kN by a cold isostatic pressing method, pelletized using a sieve, and evaluated using 2 g of the pellets. .
前処理として、酸素５％／窒素９５％の混合ガスを３００℃で５分間、１０Ｌ／ｍｉｎで流通させた。その後、図１に示す温度プロファイルに従って３００℃、５００℃、及び７００℃で酸素貯蔵能測定を行った。 As a pretreatment, a mixed gas of 5% oxygen/95% nitrogen was passed at 300° C. for 5 minutes at 10 L/min. After that, the oxygen storage capacity was measured at 300°C, 500°C, and 700°C according to the temperature profile shown in FIG.
なお、流速は常に１０Ｌ／ｍｉｎで２分間１％酸素→３０秒窒素置換→２分間２％ＣＯのサイクルを各温度で６回繰り返し、ＣＯを流通させているときに検出されるＣＯ２の量（μｍｏｌ）をサイクルの２，３，４、５回目で積算して４で割り、更にサンプル量２ｇで割った値を酸素貯蔵量（μｍｏｌ／ｇ）とした。 The flow rate was always 10 L/min and the cycle of 1% oxygen for 2 minutes → 30 seconds nitrogen replacement → 2% CO for 2 minutes was repeated 6 times at each temperature, and the amount of CO 2 detected when CO was flowing. (μmol) was integrated at the 2nd, 3rd, 4th, and 5th cycles, divided by 4, and further divided by the sample amount of 2 g to obtain the oxygen storage amount (μmol/g).
〈試験結果〉
実施例１及び２、並びに比較例１～３の酸素吸蔵材の構成及び酸素吸蔵能の評価を、表１及び図２に示した。
<Test results>
The structures of the oxygen storage materials of Examples 1 and 2 and Comparative Examples 1 to 3 and the evaluation of the oxygen storage capacity are shown in Table 1 and FIG.
表１及び図２に示すように、ＣｕとＮｂとを含有している複合酸化物を酸素吸蔵材として用いた実施例１及び２では、３００℃においてそれぞれ酸素吸蔵量が８７４．０μｍｏｌ／ｇ及び９４７．０μｍｏｌ／ｇであり、高い酸素吸蔵量を有していた。 As shown in Table 1 and FIG. 2, in Examples 1 and 2 in which the composite oxide containing Cu and Nb was used as the oxygen storage material, the oxygen storage capacity at 300° C. was 874.0 μmol/g and 874.0 μmol/g, respectively. It was 947.0 μmol/g and had a high oxygen storage capacity.
これに対して、Ｃｅ２Ｚｒ２Ｏ７を酸素吸蔵材として用いた比較例１では、３００℃において酸素吸蔵量が０．０であり、酸素吸蔵能を全く有していなかった。 On the other hand, in Comparative Example 1 using Ce 2 Zr 2 O 7 as the oxygen storage material, the oxygen storage capacity at 300° C. was 0.0, indicating no oxygen storage capacity at all.
また、Ｃｕ又はＮｂの一方のみの酸化物を酸素吸蔵材として用いた比較例２及び３では、３００℃においてそれぞれ酸素吸蔵量が６９５．０μｍｏｌ／ｇ及び３１．７μｍｏｌ／ｇであり、一定の酸素吸蔵能は有していたが、実施例１及び２と比較して小さかった。 In addition, in Comparative Examples 2 and 3 in which only one of Cu and Nb oxides was used as the oxygen storage material, the oxygen storage capacities at 300° C. were 695.0 μmol/g and 31.7 μmol/g, respectively. Although it had an occlusive capacity, it was small compared to Examples 1 and 2.
このように、実施例１及び２の結果は、比較例２及び３の単なる足し合わせより高い酸素吸蔵能を示しているため、ＣｕとＮｂとが複合酸化物を形成していることによって、高い酸素吸蔵能が発現したと考えられる。 Thus, the results of Examples 1 and 2 show a higher oxygen storage capacity than the simple addition of Comparative Examples 2 and 3. It is considered that the oxygen storage capacity was expressed.
《試験２：Ｘ線回折試験》
〈試験方法〉
Ｘ線源にＣｕＫα（λ＝１．５４１８Å）を用い、ステップ幅１０～４０°、０．０２°／０．３ｓｅｃ、管電圧５０ｋＶ、管電流３００ｍＡで、実施例１及び２の酸素吸蔵材を測定した。
<<Test 2: X-ray diffraction test>>
<Test method>
CuKα (λ = 1.5418 Å) was used as the X-ray source, the step width was 10 to 40°, 0.02°/0.3 sec, the tube voltage was 50 kV, and the tube current was 300 mA. It was measured.
〈試験結果〉
実施例１の酸素吸蔵材のＸ線回折の測定結果を図３に、実施例２の酸素吸蔵材のＸ線回折の測定結果を図４に、それぞれ示した。
<Test results>
The results of X-ray diffraction measurement of the oxygen storage material of Example 1 are shown in FIG. 3, and the results of X-ray diffraction measurement of the oxygen storage material of Example 2 are shown in FIG.
図３及び図４における回折パターンは、それぞれ単相のＣｕ３Ｎｂ２Ｏ８及びＣｕＮｂ２Ｏ６が得られていることを示している。 The diffraction patterns in FIGS. 3 and 4 show that single-phase Cu 3 Nb 2 O 8 and CuNb 2 O 6 are obtained, respectively.
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| JP2016540641A (en) | 2013-10-16 | 2016-12-28 | クリーン ディーゼル テクノロジーズ インコーポレーテッドＣｌｅａｎ Ｄｉｅｓｅｌ Ｔｅｃｈｎｏｌｏｇｉｅｓ， Ｉｎｃ． | OSM heat-stable composition containing no rare earth metal |
| JP2017502824A (en) | 2013-11-29 | 2017-01-26 | ユミコア・アクチエンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフトＵｍｉｃｏｒｅ ＡＧ ＆ Ｃｏ．ＫＧ | Oxygen storage material |
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| JP2017502824A (en) | 2013-11-29 | 2017-01-26 | ユミコア・アクチエンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフトＵｍｉｃｏｒｅ ＡＧ ＆ Ｃｏ．ＫＧ | Oxygen storage material |
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