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采用溶胶 凝胶法制备了三效催化剂助剂 (Ce Zr)O2 ,(Pr Ce Zr)O2 和 (Pr Zr)O2 ,并对它们进行了XRD ,EXAFS和BET比表面的测定。采用H2 的程序升温还原 (TPR)表征该类助剂的还原特性 ,以考察此类含有镨的混合氧化物作为三效催化剂储氧组分的可能性。在≥ 80 0℃高温时 ,(Pr Zr)O2 形成了立方相固溶体 ,并且变得更容易被还原。含少量Pr的三元固溶体 (Pr Ce Zr)O2 在其还原过程中起着重要的作用 ,也具有易被还原的重要特性。测量了含有Pt ,Pd和Rh的三效催化剂活性 ,即固定反应气氛组成 (S =1.0 0 )时CO ,C3H6 和NOx 转化的起燃温度。结果表明 ,在 (Ce Zr)O2 固溶体中加入少量的镨可使得C3H6 和NOx 转化的起燃温度降低 ,所有含镨的催化剂对NOx 转化均表现出较高的活性 ,并且在富氧区 (S≥ 1.0 0 )具有更大的S值宽度。
Three-way catalyst aids (Ce Zr) O2, (Pr Ce Zr) O2 and (Pr Zr) O2 were prepared by sol-gel method and their XRD, EXAFS and BET surface areas were measured. The reduction characteristics of these auxiliaries were characterized by temperature programmed reduction (TPR) of H2 to investigate the potential of such praseodymium-containing mixed oxide as a three-way catalyst oxygen storage component. (Pr Zr) O 2 forms a cubic solid solution at a high temperature of ≥ 80 0 ° C and becomes more easily reduced. The ternary solid solution (Pr Ce Zr) O2 containing a small amount of Pr plays an important role in the reduction process and also has important properties that are easily reduced. The three-way catalyst activity with Pt, Pd and Rh was measured, that is, the light-off temperature of CO, C3H6 and NOx conversion at a fixed reaction atmosphere composition (S = 1.0 0) The results showed that the addition of a small amount of praseodymium to the Ce (Zr) O2 solid solution led to the decrease of the light-off temperature of C3H6 and NOx conversion. All praseodymium-containing catalysts exhibited higher activity for NOx conversion. In addition, ≥ 1.0 0) has a larger S-value width.