一种暴露CeO_2{100}晶面的铈钛复合氧化物合成及其负载Au催化剂一氧化碳低温氧化性能研究
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摘要
利用水热法制备了一种具有花朵状形貌的铈钛复合氧化物,该复合氧化物主要暴露CeO_2{100}晶面。SEM、XRD表征结果表明,花朵状铈钛复合氧化物的形成主要分为两个阶段,即无定型的快速生长及缓慢结晶两个过程;在制备过程中,铈钛比例、KOH浓度、晶化时间和焙烧温度是该形貌形成的主要影响因素。其负载Au催化剂后常温即能实现CO的完全转化;TEM和H_2-TPR结果表明,暴露的CeO_2{100}晶面以及Au和载体的强相互作用是该催化剂具有高活性的主要原因。
In this work,a flower-like CeTiO_x composite oxide,predominantly exposing CeO_2{100} plane,was synthesized by a simple hydrothermal method.The SEM and XRD results revealed the growth mechanism of CeTiOx composite oxide can be divided into two stages,including the rapid growth of amorphous and the following crystallization.The ratio of Ce/Ti,KOH concentration,crystallization time and calcination temperature are the key factors for the synthesis of the flower-like CeTiOx composite oxide.Au catalyst supported on this composite oxide exhibited superior activity for CO oxidation at room temperature.The TEM and H_2-TPR results suggested that the exposed CeO_2{100} plane and the strong interaction between Au and CeTiO_x composite oxide are responsible for the high activity.
In this work,a flower-like CeTiO_x composite oxide,predominantly exposing CeO_2{100} plane,was synthesized by a simple hydrothermal method.The SEM and XRD results revealed the growth mechanism of CeTiOx composite oxide can be divided into two stages,including the rapid growth of amorphous and the following crystallization.The ratio of Ce/Ti,KOH concentration,crystallization time and calcination temperature are the key factors for the synthesis of the flower-like CeTiOx composite oxide.Au catalyst supported on this composite oxide exhibited superior activity for CO oxidation at room temperature.The TEM and H_2-TPR results suggested that the exposed CeO_2{100} plane and the strong interaction between Au and CeTiO_x composite oxide are responsible for the high activity.
引文
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[2]HARUTA M,YAMADA N,KOBAYASHI T.Gold catalysts prepared by coprecipitation for low-temperature oxidation of hydrogen and of carbon monoxide[J].J Catal,1989,115(2):301-309.
[3]HARUTA M,TSUBOTA S,KOBAYASHI T.Low-temperature oxidation of CO over gold supported on TiO2,α-Fe2O3,and Co3O4[J].J Catal,1993,144(1):175-192.
[4]PANDIAN L,LAURENT D,VINCENT R.Total oxidation of propene over Au/CeO2-Al2O3 catalysts:Influence of the CeO2 loading and the activation treatment[J].Appl Catal B:Environ,2010,96(1/2):117-125.
[5]MARIA P C,ALESSANDRO L,ANNA M V.Metal-support and preparation influence on the structural and electronic properties of gold catalysts[J].Appl Catal A:Gen,2006,302(2):309-316.
[6]LI Q,ZHANG Y H,CHEN G X.Ultra-low-gold loading Au/CeO2 catalysts for ambient temperature CO oxidation:Effect of preparation conditions on surface composition and activity[J].J Catal,2010,273(2):167-176.
[7]LI S H,ZHU H Q,QIN Z F.Morphologic effects of nano CeO2-TiO2 on the performance of Au/CeO2-TiO2 catalysts in low-temperature CO oxidation[J].Appl Catal B:Environ,2014,144:498-506.
[8]QIAN K,HUANG W X,JIANG Z Q.Anchoring highly active gold nanoparticles on SiO2 by CoOx additive[J].J Catal,2007,248(1):137-141.
[9]WANG Z H,FU H F,TIAN Z W.Strong metal-support interaction in novel core-shell Au-CeO2 nanostructures induced by different pretreatment atmospheres and its influence on CO oxidation[J].Nanoscale,2016,8(11):5865-5872.
[10]ALESSANDRO L,LEONARDA F L,GABRIELLA D C.Structure and the metal support interaction of the Au/Mn oxide catalysts[J].Chem Mater,2010,22(13):3952-3960.
[11]LIU X J,LIU J F,CHANG Z.Crystal plane effect of Fe2O3 with various morphologies on CO catalytic oxidation[J].Catal Commun,2011,12(6):530-534.
[12]LIN S J,SUA G J,ZHENG M H.Synthesis of flower-like Co3O4-CeO2 composite oxide and its application to catalytic degradation of 1,2,4-trichlorobenzene[J].Appl Catal B:Environ,2012,123/124:440-447.
[13]ZHENG Y H,CHENG Y,WANG Y S.Quasicubic alpha-Fe2O3 nanoparticles with excellent catalytic performance[J].J Phys Chem B,2006,110(7):3093-3097.
[14]XIE X W,LI Y,LIU Z Q.Low-temperature oxidation of CO catalysed by Co3O4 nanorods[J].Nature,2009,458(7239):746-749.
[15]LIU L J,JIANG Y Q,ZHAO H L.Engineering coexposed{001}and{101}facets in oxygen-deficient TiO2 nanocrystals for enhanced CO2photoreduction under visible light[J].ACS Catal,2016,6(2):1097-1108.
[16]WANG G H,LI W C,JIA K M.Shape and size controlled alpha-Fe2O3 nanoparticles as supports for gold-catalysts:Synthesis and influence of support shape and size on catalytic performance[J].Appl Catal A:Gen,2009,364(1/2):42-47.
[17]ZIOLKOWSKI J,BARBAUX Y.Identification of sites active in oxidation of butene to butadiene and CO2 on CO3O4 in terms of the crystallochemical model of solid surface[J].J Mol Catal,1991,67(2):199-215.
[18]TTHX T S,FRANCESCO C,ZHANG X Q.Structure-activity map of ceria nanoparticles,nanocubes,and mesoporous architectures[J].Chem Mater,2016,28(20):7287-7295.
[19]HAUNG W X.Oxide nanocrystal model catalysts[J].Acc Chem Res,2016,49(3):520-527.
[20]TA N,LIU J Y,SANTHOSH C.Stabilized gold nanoparticles on ceria nanorods by strong interfacial anchoring[J].J Am Chem Soc,2012,134(51):20585-20588.
[21]TIZIANO M,MICHELE M,MATTEO M.Fundamentals and catalytic applications of CeO2-based materials[J].Chem Rev,2016,116(10):5987-6041.
[22]HU Z,LIU X F,MENG D M.Effect of ceria crystal plane on the physicochemical and catalytic properties of Pd/ceria for CO and propane oxidation[J].Acs Catal,2016,6(4):2265-2279.
[23]SUN C W,LI H,CHEN L Q.Study of flowerlike CeO2 microspheres used as catalyst supports for CO oxidation reaction[J].J Phys Chem Solids,2007,68(9):1785-1790.
[24]LIU W,FENG L U,ZHANG C.A facile hydrothermal synthesis of 3D flowerlike CeO2 via a cerium oxalate precursor[J].J Mater Chem A,2013,1(23):6942-6948.
[25]ZHOU K B,WANG X,SUN X M.Enhanced catalytic activity of ceria nanorods from well-defined reactive crystal planes[J].J Catal,2005,229(1):206-212.
[26]MAI H X,SUN L D,ZHANG Y W.Shape-selective synthesis and oxygen storage behavior of ceria nanopolyhedra,nanorods,and nanocubes[J].J Phys Chem B,2005,109(51):24380-24385.
[27]SUN C W,SUN J,XIAO G L.Mesoscale organization of nearly monodisperse flowerlike ceria microspheres[J].J Phys Chem B,2007,110(27):13445-13452.
[28]PUTLA S,BAITHY M,PADIGAPATI S R.Nano-Au/CeO2 catalysts for CO oxidation:Influence of dopants(Fe,La and Zr)on the physicochemical properties and catalytic activity[J].Appl Catal B:Environ,2014,144:900-908.
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[30]CHEN Y,WANG Y S,ZHEGN Y H.Two-step self-assembly of nanodisks into plate-built cylinders through oriented aggregation[J].J Phys Chem B,2005,109(23):11548-11551.
[31]HUANG X S,SUN H,WANG L C.Morphology effects of nanoscale ceria on the activity of Au/CeO2 catalysts for low-temperature CO oxidation[J].Appl Catal B:Environ,2009,90(1/2):224-232.
[32]ZHONG L S,HU J S,CAO A M.3D flowerlike ceria micro/nanocomposite structure and its application for water treatment and CO removal[J].Chem Mater,2007,19(7):1648-1655.
[33]QI J,CHEN J,LI G D.Facile synthesis of core-shell Au@CeO2 nanocomposites with remarkably enhanced catalytic activity for CO oxidation[J].Energy Environ Sci,2012,5(10):8937.