Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (06): 498-503.doi: 10.3866/PKU.WHXB20030604

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Structure Characteristic of Novel SnxZr1-xO2 Solid Solution Catalysts for

Wei Ji-Ying;Zhu Yue-Xiang;Duan Lian-Yun;Xie You-Chang   

  1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871
  • Received:2002-09-09 Revised:2002-11-29 Published:2003-06-15

Abstract: A series of SnxZr1-xO2 solid solution catalysts with SnO2 content varied from 10%(w) to 90%(w) were prepared by co-current coprecipitation method (CCP method) using ammonia solution as precipitating agent and calcined at 500 ℃ for 4 h in air.The structure variation with SnO2 content was investigated by XRD,electron diffraction,FT-Raman and FT-IR.Tin dioxide and zirconia can react with each other to form solid solutions within a large composition range.In the present work,zirconia prepared by CCP method and calcined at 500 ℃ was monoclinic,and tin dioxide prepared by the same way possessed rutile structure.The experiment results showed the following dependence of the solid solution structure on SnO2 content.First,less than 20% SnO2 inserted into the lattice of ZrO2 could stabilize the tetragonal structure of zirconia and form the zirconia-rich solid solutions.Then,amorphous zirconia-rich solid solutions were formed in the SnO2 content region from 30 % to 50%.Furthermore,a rutile structure tin dioxide-rich solid solution existed as SnO2 content over 60%.Finally,the zirconia-rich solid solution and tin dioxide-rich solid solution could co-exist while the SnO2 content maintained at 55%,which exhibited a structure transition between zirconia-rich and tin dioxide-rich solid solutions.Because the Sn-O bond was weakened and the effective electropositivity of Sn4+ was decreased as Zr4+ inserted into SnO2 lattice as proved by FT-Raman and FT-IR measurements,both the activation and the complete combustion of propene were restrained by Zr4+,as a result,the catalytic performance for NO selective reduction was promoted.

Key words: NO, Selective catalytic reduction, SnxZr1-xO2 solid solution, Rutile structure