JP2021020171A - Oxygen storage material - Google Patents
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- JP2021020171A JP2021020171A JP2019138818A JP2019138818A JP2021020171A JP 2021020171 A JP2021020171 A JP 2021020171A JP 2019138818 A JP2019138818 A JP 2019138818A JP 2019138818 A JP2019138818 A JP 2019138818A JP 2021020171 A JP2021020171 A JP 2021020171A
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- oxygen storage
- storage material
- oxygen
- composite oxide
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- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 120
- 239000001301 oxygen Substances 0.000 title claims abstract description 117
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 112
- 239000011232 storage material Substances 0.000 title claims abstract description 59
- 238000003860 storage Methods 0.000 claims abstract description 32
- 229910052751 metal Inorganic materials 0.000 claims abstract description 21
- 239000002184 metal Substances 0.000 claims abstract description 21
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 15
- 229910052802 copper Inorganic materials 0.000 claims abstract description 14
- 239000002131 composite material Substances 0.000 claims description 27
- 239000003054 catalyst Substances 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 13
- 229910052763 palladium Inorganic materials 0.000 claims description 4
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 230000003197 catalytic effect Effects 0.000 abstract 1
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 239000007789 gas Substances 0.000 description 9
- 238000000746 purification Methods 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 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
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 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
- 150000002926 oxygen Chemical class 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 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
- 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
- 238000005259 measurement Methods 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- 239000008188 pellet Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 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
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 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
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- LFLZOWIFJOBEPN-UHFFFAOYSA-N nitrate, nitrate Chemical compound O[N+]([O-])=O.O[N+]([O-])=O LFLZOWIFJOBEPN-UHFFFAOYSA-N 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- 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
Landscapes
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Catalysts (AREA)
Abstract
Description
本開示は、酸素吸蔵材に関する。 The present disclosure relates to an oxygen occlusion material.
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。 In the exhaust gas emitted from an internal combustion engine for automobiles, for example, a gasoline engine or a diesel engine, components such as carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) are contained. 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。 Therefore, in general, an exhaust gas purification device for purifying these components is attached to the internal combustion engine, and most of these components are purified by the exhaust gas purification catalyst installed in the exhaust gas purification 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 purification catalyst. Ceria has an oxygen occlusion ability (OSC: Oxygen Property Capacity) property of storing oxygen in a lean atmosphere and releasing oxygen in a rich atmosphere. Therefore, a ceria-based oxygen storage material can be suitably used as 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 that a ceria-zirconia composite oxide is used 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 the exhaust gas purification catalyst, an oxygen storage material having a higher oxygen storage capacity is required. In particular, there is a demand for an oxygen storage material having an oxygen storage capacity in a lower temperature range, for example, a temperature of 300 ° C. or lower.
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。 It is an object of the present disclosure to provide an oxygen storage material having a high oxygen storage capacity, particularly a high oxygen storage capacity 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 Discloser has found that the above tasks can be achieved by the following means:
<< Aspect 1 >>
An oxygen occlusion 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 Cu 3 Nb 2 O 8 or Cu Nb 2 O 6 .
<< 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 amount of 800.0 μmol / g or more at 300 ° C.
<< Aspect 5 >>
The oxygen storage material according to any one of aspects 1 to 4, wherein the catalyst metal is supported.
<< Aspect 6 >>
The oxygen storage material according to aspect 5, wherein the ratio of the catalyst metal to the oxygen storage material is more than 0% by mass and 5% by mass or less.
<< Aspect 7 >>
The oxygen storage material according to aspect 5 or 6, wherein the catalyst metal is Pt, Pd, or Rh.
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, particularly a high oxygen storage capacity 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, but can be variously modified within the scope of the purpose 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。 The ceria-zirconia composite oxide, which has been used as an oxygen occlusion material in a conventional exhaust gas purification catalyst, has a pyrochlore phase or a κ phase, and has a high oxygen storage capacity under high temperature conditions. However, cerium can store 0.5 oxygen atoms per cerium, while the composition ratio of cerium to zirconium of the ceria-zirconia composite oxide is 1: 1 and ceria-zirconia. In the composite oxide, 90% or more of the cerium possessed by the material itself has already expressed the oxygen storage capacity, that is, the oxygen storage capacity has already reached the theoretical limit, and there is expected room for an increase in the oxygen storage capacity. I 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。 Further, since the active energy for taking in and out oxygen in the oxide structure of the ceria-zirconia composite oxide is high, oxygen cannot be sufficiently occluded in a low temperature range, for example, at a low temperature of 300 ° C. or lower.
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 disclosers have found that by using a composite oxide of Cu and Nb as an oxygen occlusion material, a high oxygen occlusion ability, particularly a high oxygen occlusion ability 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 amount of 800.0 μmol / g or more at, for example, 300 ° C. Here, the oxygen storage amount is a value obtained by dividing the amount of oxygen atoms (μmol) 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 amount of the oxygen storage material of the present disclosure at 300 ° C. may be 800.0 μmol / g or more, 850.0 μmol / g or more, or 900.0 μmol / g or more, 1000.0 μmol / g or less, 950. 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 is not particularly limited as long as it contains Cu and Nb and has an oxygen storage capacity, but is preferably Cu 3 Nb 2 O 8 or Cu Nb 2 O 6 , for example.
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. Further, 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 catalyst 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。 Examples of the catalyst metal include noble metals or alloys of noble metals with other metals. Examples of the noble metal include, but are not limited to, Pt, Pd, or Rh.
〈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 by mixing, for example, Cu oxide, for example Cu 2 O, and Nb oxide, for example, Nb 2 O 5 and firing, 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 as to have a molar ratio of 3: 2, placed in an agate mortar, and ground and mixed for 1 hour. Then, the pellets were obtained by compacting at 196 kN using a cold isotropic pressurization method. The pellets were air calcined at 800 ° C. for 36 hours, followed by air calcining at 950 ° C. for 40 hours to obtain pellets of composite oxide. The obtained composite oxide is ground in an agate mortar, 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 based on the composite oxide. After stirring, the mixture was evaporated to dryness at 120 ° C. Then, hydrogen reduction was performed at 400 ° C. for 2 hours to obtain an oxygen occlusion material on which Pd particles were supported.
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。 In addition, this oxygen storage material had a structure in which Pd as a metal catalyst was supported on Cu 3 Nb 2 O 8 as an 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 occlusion material carrying 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 as to have a molar ratio of 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。 In addition, this oxygen storage material had a structure in which Pd as a metal catalyst was supported on CuNb 2 O 6 as an 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 cerium nitrate, and the mixture was heated at 100 ° C. or higher while stirring with a hot stirrer. The solution was allowed to dry. Then, it was heated in an electric furnace at 120 ° C. for 8 hours or more, the obtained solid was sufficiently ground in an agate mortar, placed in an alumina crucible, and air-baked at 700 ° C. for 3 hours. The powder after calcination was reduced at 1200 ° C. under a hydrogen flow for 24 hours to obtain Ce 2 Zr 2 O 7 as a composite oxide. The obtained composite oxide is ground in an agate mortar, 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 based on the composite oxide. After stirring, the mixture was evaporated to dryness at 120 ° C. Then, hydrogen reduction was performed at 400 ° C. for 2 hours to obtain an oxygen occlusion material on which Pd particles were supported.
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。 In addition, this oxygen storage material had a structure in which Pd as a metal catalyst was supported on Ce 2 Zr 2 O 7 as an 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 is suspended in a small amount of water, a palladium nitric acid nitric acid solution is added dropwise so that the amount of Pd is 1% by mass with respect to Cu 2 O, and the mixture is sufficiently stirred and then evaporated to dryness at 120 ° C. It was. Then, hydrogen reduction was performed at 400 ° C. for 2 hours to obtain an oxygen occlusion material on which Pd particles were supported.
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。 In addition, 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 is suspended in a small amount of water, a palladium nitrate nitric acid solution is added dropwise so that the amount of Pd is 1% by mass with respect to Cu 2 O, and the mixture is sufficiently stirred and then evaporated to dryness at 120 ° C. I let you. Then, hydrogen reduction was performed at 400 ° C. for 2 hours to obtain an oxygen occlusion material on which Pd particles were supported.
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。 In addition, this oxygen storage material had a structure in which Pd as a metal catalyst was supported on Nb 2 O 5 as an 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 occlusion materials of Examples 1 and 2 and Comparative Examples 1 to 3 were compacted at 196 kN by a cold isotropic pressurization 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 circulated at 300 ° C. for 5 minutes at 10 L / min. Then, 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 velocity is always 10 L / min, and the cycle of 1% oxygen for 2 minutes → nitrogen substitution for 30 seconds → 2% CO for 2 minutes is repeated 6 times at each temperature, and the amount of CO 2 detected when CO is circulated. (Μmol) was integrated at the 2, 3, 4 and 5th cycles and divided by 4, and the value further divided by the sample amount of 2 g was taken as 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>
Tables 1 and 2 show the configurations of the oxygen storage materials of Examples 1 and 2 and Comparative Examples 1 to 3 and the evaluation of the oxygen storage capacity.
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 occlusion material, the oxygen occlusion amount was 874.0 μmol / g and respectively at 300 ° C. It was 947.0 μmol / g and had a high oxygen occlusion.
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 in which Ce 2 Zr 2 O 7 was used as the oxygen storage material, the oxygen storage amount was 0.0 at 300 ° C., and the oxygen storage capacity was not provided 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。 Further, in Comparative Examples 2 and 3 in which only one oxide of Cu or Nb was used as the oxygen storage material, the oxygen storage amounts were 695.0 μmol / g and 31.7 μmol / g at 300 ° C., respectively, and constant oxygen was obtained. Although it had occlusion ability, it was smaller than that of 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。 As described above, the results of Examples 1 and 2 show higher oxygen occlusion ability than the mere addition of Comparative Examples 2 and 3, and thus are high because Cu and Nb form a composite oxide. It is considered that the oxygen storage capacity was developed.
《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>
Using CuKα (λ = 1.5418Å) as the X-ray source, the oxygen storage materials of Examples 1 and 2 were used with a step width of 10 to 40 °, 0.02 ° / 0.3sec, a tube voltage of 50 kV, and a tube current of 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 measurement result of the X-ray diffraction of the oxygen storage material of Example 1 is shown in FIG. 3, and the measurement result of the X-ray diffraction of the oxygen storage material of Example 2 is shown in FIG. 4, respectively.
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 Cu Nb 2 O 6 are obtained, respectively.
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JPH01138102A (en) * | 1987-11-25 | 1989-05-31 | Mitsubishi Electric Corp | Oxygen gas storage apparatus |
JP2011174167A (en) * | 2010-02-01 | 2011-09-08 | Ryukoku Univ | Oxide film, method for producing the same, target, and method for producing oxide sintered compact |
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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JPH01138102A (en) * | 1987-11-25 | 1989-05-31 | Mitsubishi Electric Corp | Oxygen gas storage apparatus |
JP2011174167A (en) * | 2010-02-01 | 2011-09-08 | Ryukoku Univ | Oxide film, method for producing the same, target, and method for producing oxide sintered compact |
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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