改进共沉淀法以提高三效催化剂中铈锆复合氧化物的热稳定性（英文）
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摘要
采用共沉淀法制备了铈锆材料(铈锆比为3/2)。通过改进反应器装置(图1),延长了初始晶粒生长的时间,提高了铈锆材料的热稳定性。采用X射线衍射(XRD)、氮气吸脱附和透射电镜(TEM)对制备的材料进行了表征。结果表明,延长初始晶粒生长的时间可以得到较大尺寸的晶粒,这有利于提高材料的织构和结构性能,从而提高热稳定性。本研究将该材料应用于单Pd三效催化剂,表现出了优异的活性和热稳定性,具有良好的应用前景。
A series of ceria-zirconia mixed oxides(CZ-x; x=0,20,40 and 80) with Ce/Zr molar ratio of 3/2 were synthesized by co-precipitation method.In order to improve the thermal stability of ceria-zirconia mixed oxides,we extended the time for the primary grain to grow up by a modified synthesis reactor.The resulting samples were characterized by X-ray diffraction(XRD),N_2 adsorption-desorption,and transmission electron microscopy(TEM).The results revealed that bigger grain could be obtained by extending time for the primary grain to grow up,which was propitious to enhance the textural properties and structural properties of the materials.Thus,the thermal stability of the materials was improved.In this study,the materials were applied in the field of Pd-only three way catalysts(TWCs).The catalysts exhibited excellent catalytic performance and thermostability,showing better prospect in application.
A series of ceria-zirconia mixed oxides(CZ-x; x=0,20,40 and 80) with Ce/Zr molar ratio of 3/2 were synthesized by co-precipitation method.In order to improve the thermal stability of ceria-zirconia mixed oxides,we extended the time for the primary grain to grow up by a modified synthesis reactor.The resulting samples were characterized by X-ray diffraction(XRD),N_2 adsorption-desorption,and transmission electron microscopy(TEM).The results revealed that bigger grain could be obtained by extending time for the primary grain to grow up,which was propitious to enhance the textural properties and structural properties of the materials.Thus,the thermal stability of the materials was improved.In this study,the materials were applied in the field of Pd-only three way catalysts(TWCs).The catalysts exhibited excellent catalytic performance and thermostability,showing better prospect in application.
引文
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[16]FORNISIERO P,MONTE R D,RAO G R,et al.Rh-loaded Ce O2-Zr O2 solid solutions as highly efficient oxygen exchangers:dependence of the reduction behavior and the oxygen storage capacity on the structural properties.J.Catal.,1995,151(1):168–177.
[17]WENG X,PERSTON B,WANG X Z,et al.Synthesis and characterization of doped nano-sized ceria–zirconia solid solutions.Appl.Catal.B:Environ.,2009,90(3/4):405–415.
[18]SUN Y,SERMON P A.Surface reactivity and bulk properties of ZrO 2 Part 2-Importance of homogeneity in the stabilisation of high surface area Ce O2-ZrO 2 aerogels.J.Mater.Chem,1996,6(6):1025–1029.
[19]MONTE R D,KA?PAR J,BRADSHAW H,et al.A rationale for the development of thermally stable nanostructured Ce O2-Zr O2-containing mixed oxides.J.Rare Earths,2008,26(2):136–140.
[20]ZHOU Y,LAN L,GONG M,et al.Modification of the thermal stability of doped Ce O2-Zr O2 mixed oxides with the addition of triethylamine and its application as a Pd-only three-way catalyst.J.Mater.Sci.,2016,51(9):4283–4295.
[2]MATSUMOTO S.Recent advances in automobile exhaust catalysts.Catal.Today,2004,90(3/4):183–190.
[3]KA?PAR J,FORNASIERO P.Nanostructured materials for advanced automotive de-pollution catalysts.Solid State Chem.,2003,171(1/2):19–29.
[4]FARRAUTO R J,HECK R M.Catalytic converters:state of the art and perspectives.Catal.Today,1999,51(3/4):351–360.
[5]HECK R M,FARRAUTO R J.Automobile exhaust catalysts.Appl.Catal.A:Gen.,2001,221(1/2):443–457.
[6]KA?PAR J,FORNASIERO P,GRAZIANI M.Use of CeO 2-based oxides in the three-way catalysis.Catal.Today,1999,50(2):285–298.
[7]MONTE R D,KA?PAR J.Heterogeneous environmental catalysis-a gentle art:Ce O2-ZrO 2 mixed oxides as a case history.Catal.Today,2005,100(1/2):27–35.
[8]SHIGAPOV A N,GRAHAM G W,MCCABE R W,et al.The preparation of high-surface area,thermally-stable,metal-oxide
[9]catalysts and supports by a cellulose templating approach.Appl.Catal.A:Gen.,2001,210(1/2):287–300.
[10]BUMAJDAD A,ZAKI M I,EASTOE J,et al.Microemulsionbased synthesis of Ce O2 powders with high surface area and hightemperature stabilities.Langmuir,2004,20(25):11223–11233.
[11]FUENTES R O,BAKER R T.Synthesis of nanocrystallineCe O2-Zr O2 solid solutions by a citrate complexation route:a thermochemical and structural study.J.Phys.Chem.C,2009,113(3):914–924.
[12]NAKATANI T,OKAMOTO H,OTA R.Preparation of Ce O2-ZrO 2mixed oxide powders by the coprecipitation method for the purification catalysts of automotive emission.J.Sol-Gel Science and Technology,2003,26(1):859–863.
[13]KA?PAR J,FORNASIERO P,BALDUCCI G,et al.Effect of Zr O2content on textural and structural properties of Ce O2-ZrO 2 solid solutions made by citrate complexation route.Inorg.Chim.Acta,2003,349(5):217–226.
[14]TROVARELLI A,ZAMAR F,LLORCA J,et al.Nanophase fluorite-structured Ce O2-ZrO 2 catalysts prepared by high-energy mechanical milling.J.Catal.,1997,169(2):490–502.
[15]BOARO M,VICARIO M,LEITENBURG C D,et al.The use of temperature-programmed and dynamic/transient methods in catalysis:characterization of ceria-based.Catal.Today,2003,77(4):407–417.
[16]FORNISIERO P,MONTE R D,RAO G R,et al.Rh-loaded Ce O2-Zr O2 solid solutions as highly efficient oxygen exchangers:dependence of the reduction behavior and the oxygen storage capacity on the structural properties.J.Catal.,1995,151(1):168–177.
[17]WENG X,PERSTON B,WANG X Z,et al.Synthesis and characterization of doped nano-sized ceria–zirconia solid solutions.Appl.Catal.B:Environ.,2009,90(3/4):405–415.
[18]SUN Y,SERMON P A.Surface reactivity and bulk properties of ZrO 2 Part 2-Importance of homogeneity in the stabilisation of high surface area Ce O2-ZrO 2 aerogels.J.Mater.Chem,1996,6(6):1025–1029.
[19]MONTE R D,KA?PAR J,BRADSHAW H,et al.A rationale for the development of thermally stable nanostructured Ce O2-Zr O2-containing mixed oxides.J.Rare Earths,2008,26(2):136–140.
[20]ZHOU Y,LAN L,GONG M,et al.Modification of the thermal stability of doped Ce O2-Zr O2 mixed oxides with the addition of triethylamine and its application as a Pd-only three-way catalyst.J.Mater.Sci.,2016,51(9):4283–4295.