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Preparation of ceria-zirconia solid solution with enhanced oxygen storage capacity and redox performance

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Frontiers of Environmental Science & Engineering 2010年第2期4卷 164-171页

作者： Lijing MENG Licheng LIU Xuehong ZI Hongxing DAI Zhen ZHAO Xinping WANG Hong HE Laboratory of Catalysis Chemistry and Nanoscience College of Environment and Energy EngineeringBeijing University of TechnologyBeijing 100124China State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China State Key Laboratory of Fine Chemicals Dalian University of TechnologyDalian 116024China

A new method called ultrasonic-assisted membrane reaction(UAMR)was reported for the fabrication of ceria-zirconia solid solution.A series of ceria-zirconia solid solutions with different Ce/Zr molar ratios were prepared by the UAMR method and characterized by Xray diffraction(XRD),N2 adsorption,hydrogen temperature-programmed reduction(H2-TPR),scanning electron microscope(SEM),and transmission electron microscopy(TEM)*** UAMR method proved to be superior,especially when the Ce/Zr molar ratio was lower than 1,in fabricating ceria-zirconia solid solutions with large BET surface area,high oxygen storage capacity(OSC),and low reduction temperature.

关键词： membrane reaction ceria-zirconia Ce/Zr molar ratio solid solution hydrogen temperatureprogrammed reduction(H2-TPR)

Preparation, Characterization and Catalytic Performance of Nanometer ceria-zirconia Solid Solution

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Journal of Rare Earths 2004年第Z1期22卷 188-190页

作者： Hu Yucai Wang Yinghui Pan Junyan School of Chemistry and Material Sciences Yantai Normal University Yantai 264025 China School of Chemistry and Material Sciences Yantai Normal University Yantai 264025 China School of Chemistry and Material Sciences Yantai Normal University Yantai 264025 China

Ce0.6Zr0.4O2 solid solution was prepared by co-precipitation technique using hydrazine hydrate as *** physico-chemical techniques such as XRD, FT-Raman, SEM, TEM, *** used to characterize the resultant ***, its catalytic activity was evaluated in the synthesis of n-butyl acetate by the reaction of acetic acid and n-butyl *** results show that ceria-zirconia solid solution forms single cubic structure and its particle diameter is less than 100 *** a sort of solid acid, it possesses high catalytic activity and can be easily separated from reaction *** it is used for ten times, its activity basically kees unchanging.

关键词： nanometer ceria-zirconia solid solution characterization catalytic activity

Recent progress on ceria-zirconia Mixed Oxides for automotive Three-Way Catalysts

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Recent progress on Ceria-Zirconia Mixed Oxides for automotiv...

Doping of ceria-zirconia Solid Solution with Rare-earth Elements

2013中国汽车工程学会年会

作者： R.Marques S.Ifrah L.Itani N.Ohtake J.Yao J.Hernandez E.Rohart

＜正＞Introduction The three-way catalyst technology has undergone significant advances during the past 30 years,involving major changes in the usage of *** is now combined in solid solution with Zireonia to achieve high OSC performance under severe *** development of such ceria-zirconia mixed oxide materials began in the late 1980s and ultimately achieved widespread incorporation into TWC’s by the mid-1990s under

关键词： ceria-zirconia Automotive catalysts Oxygen Storage Capacity TWC

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合成化学 2004年第Z1期12卷 136-136页

作者： HU Yu-cai FENG Chang-gen WANG Li-qiong WANG Ya-jun State Key Laboratory of Explosive and Safety Sciences Beijing Institute of Technology Beijing 100081China State Key Laboratory of Explosive and Safety Sciences Beijing Institute of Technology Beijing 100081China State Key Laboratory of Explosive and Safety Sciences Beijing Institute of Technology Beijing 100081China State Key Laboratory of Explosive and Safety Sciences Beijing Institute of Technology Beijing 100081China

The increasingly restrictive regulations on car exhaust emissions will necessitate the development of a new generation of three way catalysts (TWC) with better performance1. ceria (CeO2) is the main component of the current TWC: its key role is to compensate the fluctuations in the exhaust stream composition, therefore, allowing to expand the air/fuel(A/F) operating window of catalytic converters2. This property is related to its oxygen storage capacity (OSC), associated to the redox couple Ce4+/Ce3+. However, CeO2 alone is easy to sinter to lost OSC at high ***-zirconia (CexZr1-xO2) solid solutions by incorporation of Zr4+ in the CeO2 lattice have enhanced OSC and greater thermal stability, which are becoming the key materials for the new generation of TWC4. OSC of ceria-zirconia solid solutions can be further improved by the addition of M3+ dopants5. Besides Ce, other rare-earth elements such as Pr and Tb can vary their oxidation state. Pr and Tb are particularly suitable for making solid solutions with cerium because the known structure of PrO2 and TbO2 is of the cubic fluorite type, and the ionic radii of Pr4+ and Tb4+ are close to that of Ce4+*** this paper, Ce0.6Zr0.3M0.1O2 (M=Y, La, Pr, Tb) were prepared by co-precipitation technique and characterized by a series of methods. Meanwhile, palladium-only TWCs were prepared by slurry coating and their catalytic activity was evaluated under the condition of simulated exhaust in the *** and FT-Raman spectra results show Ce0.6Zr0.3M0.1O2 have cubic fluorite structure which keep unchanging at high temperature. The different dopant ion radii brought different effect on the cell parameter of Ce0.6Zr0.3M0.1O2. The X-ray photoelectron spectroscopy (XPS) results show that the binding energy of Ce3d, Zr3d and O1s for Ce0.6Zr0.3M0.1O2 rose compared with that for Ce0.6Zr0.4O2, indicating dopant elements changed chemistry environment of solid solutions which was available to improve redox performance From T

关键词： ceria-zirconia solid solution, doping, Ce0.6Zr0.3M0.1O2 (M=Y, La, Pr, Tb), three- way catalyst

CO oxidation under lean and stoichiometric conditions over ceriazirconia with very low metal contents(Cu,Co,Ag and Pt)

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Journal of Rare Earths 2024年第9期42卷 1669-1681,I0002页

作者： J.C.Martínez-Munuera M.P.Yeste A.García-García MCMA Group Department of Inorganic Chemistry and Institute of MaterialsUniversity of AlicanteCarretera de San Vicente del Raspeig s/n03690San Vicente del RaspeigAlicanteSpain Solid Chemistry and Catalysis Group Department of Materials ScienceMetallurgic Engineering and Inorganic ChemistryInstitute of Electronic Microscopy and Materials ResearchUniversity of CádizAp.40E-11510Puerto RealCádizSpain

In this work,several ceria-zirconia based catalysts with very lo w(and equimolar) metal contents were prepared,characterised and tested for the CO oxidatio n reaction(under lean and stoichiometric conditions),trying to emulate those conditions found in a diesel oxidation catalyst(DOC) system from a diesel engine and those encountered under gasoline exhaust(λ=1).The metals chosen are Cu,Co,Ag and Pt(as a reliable benchmark).The results reveal enormous differences among reducibility and catalytic activity despite quite similar structural and textural properties of the catalysts,showing differences among dispersion(Ag-catalyst seems to present a low level of dispersion).This catalyst seems to be characterised,as well,by a strong electronic interaction between Ce and Ag centres which is suggested to yield an improved reducibility under H_(2)-TPR ***,the order in catalytic activity(Cu>Ag>Co≈Pt>>support) seems not to follow the order found in reducibility and the Cu-catalyst seems to be the most active independently on the reaction conditions,yielding nearly overlapped CO oxidation catalytic *** restingly,a stro ng correlation between the catalytic activity under the two conditions tested and the OSC values of the Ce_(0.8)Zr_(0.2)O_(2)-supported metal catalysts is ***,OSC parameter measured at 150℃ can be used as a relevant descriptor to evaluate the CO oxidation activity at low and medium conversions for the investigated catalysts,much better than the H_(2)-TPR measurements.

关键词： CO oxidation Low metal content ceria-zirconia Copper species OSC parameter Rare earths

Influence of Different Subsistence States of CeO_2^-ZrO_2 Mixed Oxides in Catalyst Coating on Catalytic Properties

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Journal of Rare Earths 2006年第1期24卷 54-59页

作者：陈建军冯长根舒柏崇樊俊 School of Mechanic-Electronic Engineering Beijing Institute of Technology Beijing 100081 China School of Mechanic-Electronic Engineering Beijing Institute of Technology Beijing 100081 Chin Guilin REEcat Environment Industry Co. Guilin 541004 China Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

The metallic substrate-catalysts with different subsistence states of CeO2-ZrO2 mixed oxides were prepared and the catalytic properties were investigated. The studies on CeO2-ZrO2-V2O5-CuO mixed oxides which were prepared by coprecipitation, show that the doping of V^5＋ and Cu^2＋ in CeO2-ZrO2 mixed oxides can enhance the catalytic activity and thermal stability of coating materials. Moreover, different additives were doped in slurries of γ-Al2O3 to investigate the influence of additives on oxidation activity of catalysts. The mixture of ceria-zirconia, alkali metals and other rare earths acting as additives exhibits promotion effect on oxidation activity by optimizing the distribution of oxygen on the surface and in the bulk of ceria species. This mentioned mixture was mixed with γ-Al2O3 and a newly proposed active component to prepare a new catalyst. Afterward, the influence of thermal treatment on the new catalyst were investigated by calcinations at 500, 650, 750, 800, 850 and 900 ℃ for 2 h. The light-off curves of CO and HC show that after being treated at 650 - 750 ℃, catalysts present the best activity. XRD patterns show that ceria and zirconia species in the newly proposed active component form a phase of extra CeO2-ZrO2 mixed oxides on the surface of catalysts after the thermal treatment at 750 ℃, which has practical value for improving the preparation process and promoting the catalytic properties. Moreover, XPS resuits imply the existence of Ce1-xPdxO2-σ and Ce1- xPtxO2-σ on the surface of these treated samples, which may show influence on the catalytic activities.

关键词： catalyst metallic substrate ceria-zirconia dopant subsistent form coating technology rare earths

Pd Pt VO_(x)/CeO_(2)-ZrO_(2):Highly efficient catalysts with good sulfur dioxide-poisoning reversibility for the oxidative removal of ethylbenzene

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Journal of Environmental Sciences 2024年第4期138卷 153-166页

作者： Jia Wang Yuxi Liu Jiguang Deng Lin Jing Xiuqing Hao Xing Zhang Xiaohui Yu Hongxing Dai Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaLaboratory of Catalysis Chemistry and NanoscienceDepartment of Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The PdPtVO_(x)/CeO_(2)-ZrO_(2)(PdPtVO_(x)/CZO)catalysts were obtained by using different approaches,and their physical and chemical properties were determined by various *** activities of these materials in the presence of H_(2)O or SO_(2)were evaluated for the oxidation of ethylbenzene(EB).The PdPtVO_(x)/CZO sample exhibited high catalytic activity,good hydrothermal stability,and reversible sulfur dioxide-poisoning performance,over which the specific reaction rate at 160℃,turnover frequency at 160℃(TOF_(Pd or Pt)),and apparent activation energy were 72.6 mmol/(g_(Pt)·sec)or 124.2 mmol/(g_(Pd)·sec),14.2 sec^(-1)(TOF_(Pt))or 13.1 sec^(-1)(TOF_(Pd)),and 58 k J/mol,*** large EB adsorption capacity,good reducibility,and strong acidity contributed to the good catalytic performance of PdPtVO_(x)/*** activity of PdPtVO_(x)/CZO decreased when 50 ppm SO_(2)or(1.0 vol.%H_(2)O+50 ppm SO_(2))was added to the feedstock,but was gradually restored to its initial level after the SO_(2)was cut *** good reversible sulfur dioxide-resistant performance of PdPtVO_(x)/CZO was associated with the facts:(i)the introduction of SO_(2)leads to an increase in surface acidity;(ii)V can adsorb and activate SO_(2),thus accelerating formation of the SO_(x)^(2-)(x=3 or 4)species at the V and CZO sites,weakening the adsorption of sulfur species at the PdPt active sites,and hence protecting the PdPt active sites to be not poisoned by SO_(2).EB oxidation over PdPtVO_(x)/CZO might take place via the route of EB→styrene→phenyl methyl ketone→benzaldehyde→benzoic acid→maleic anhydride→CO_(2)and H_(2)O.

关键词： ceria-zirconia Supported palladium-platinum-vanadium catalyst Volatile organic compound Ethylbenzene oxidation Sulfur dioxide resistance

Influence of surface Ce/Zr ratio on formation of κ-Ce_(2)Zr_(2)O_(8) superstructure and its application in three-way catalysis

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Journal of Rare Earths 2023年第1期41卷 67-76页

作者： Jie Deng Shanshan Li Xinyi Yin Mengchen Li Jianli Wang Yongdong Chen Yaoqiang Chen College of Chemistry and Chemical Engineering Southwest Petroleum UniversityChengdu 610500China College of Chemistry Sichuan UniversityChengdu 610064China National Engineering Research Center for Flue Gas Desulfurization Sichuan UniversityChengdu 610064China

ceria-zirconia based(CZ) materials are still a crucial component of three-way catalysts(TWCs) *** with traditional cubic or tetragonal phase,CZ material with pyrochlore-type κ-Ce_(2)Zr_(2)O_(8) phase shows an excellent oxygen storage capacity,and thus is examined as a promising material for developing *** the remarkable surface Ce/Zr ratio change during the κ-Ce_(2)Zr_(2)O_(8) formation,we investigated the effects of surface Ce/Zr ratio on the formation of κ-Ce_(2)Zr_(2)O_(8) and on the supported Pdonly three-way *** and transmission electron microscopy(TEM) results demonstrate that partial κ-Ce_(2)Zr_(2)O_(8) structure is formed in the three oxides,and the content of κ-Ce_(2)Zr_(2)O_(8) structure increases with increasing surface Ce/Zr ratio,but its stability *** thermal aging,the proportions of Ce^(3+) and oxidized palladium(Pd^(δ+)+Pd^(2+)) in the catalysts,which are shown to be positively correlated with catalytic activity,follow the same sequence as the stability of κ-Ce_(2)Zr_(2)O_(8),namely Pd/M0.33 ROa> Pd/M0.4 ROa> Pd/CeM0.33 *** particular,Pd/M0.33 RO,which possesses 100%((Pd^(δ+)+Pd^(2+))/Pd) even after thermal aging at 900℃ for 4 h,owing to the strengthened metal-support interaction by the presence of stable κ-Ce_(2)Zr_(2)O_(8),shows the best catalytic *** work is instructive to the application of κ-Ce_(2)Zr_(2)O_(8) in three-way catalysis.

关键词： ceria-zirconia κ-Ce_(2)Zr_(2)O_(8) Ce/Zr ratio Three-way catalyst Rare earths

Structure and oxygen storage capacity of Pr-doped Ce_(0.26)Zr_(0.74)O_2 mixed oxides

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Journal of Rare Earths 2011年第11期29卷 1053-1059页

作者：冉锐翁端吴晓东樊俊王蕾吴筱笛 Laboratory of Advanced Materials Department of Materials Science and EngineeringTsinghua University The Administrative Center for China's Agenda 21

Binary Ce-Zr（CZ）,Pr-Zr（PZ） and ternary Ce-Zr-Pr（CZP） mixed oxides were prepared by an ammonia-aided co-precipitation method,and were aged in a steam/air flow at 1050 °C.X-ray diffraction（XRD）,Raman spectra,X-photon spectra（XPS） and CO temperature programmed reduction（TPR） were carried out to characterize the micro-structure and reducibility of *** oxygen storage capacity（OSC） was evaluated with CO serving as probe *** results showed that a pseudo cubic structure was formed for the Zr-rich ceria-zirconia mixed oxides with Pr *** insertion of Pr prevented the phase segregation of the mixed oxides during the hydrothermal *** Pr doped samples showed better redox performances in comparison with CZ,and the sample doped with 5 wt.% Pr showed the most remarkably promoted dynamic oxygen storage *** phenomenon was closely related to both the reducibility and oxygen mobility of the mixed *** introduction of praseodymium into ceria-zirconia could accelerate the oxygen migration by increasing the amount of oxygen vacancies,although it was difficult for Pr3＋ ions themselves to participate in the oxygen exchange process.

关键词： ceria-zirconia Zr-rich praseodymium oxygen storage capacity rare earths