摘要
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。
The three way catalysts promoters (Ce Zr)O 2, (Pr Ce Zr)O 2 and (Pr Zr)O 2 were prepared by sol gel method with some special procedures. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature programmed reduction(TPR) of H 2, to access the potential for the promoters containing praseodymia as oxygen storage component in three way catalyst. The (Pr Zr)O 2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce Zr)O 2 solid solution. For the (Pr Ce Zr)O 2 samples, the trinary solid solution also plays an important role in the reduction process. The performance of the three way catalysts with fully formulated Pt, Pd and Rh was proceeded by using light off temperature under a stoichiometric gas composition. It was indicated that a small amount of praseodymia, doping into(Ce Zr)O 2 favors the light off temperature of C 3H 6 and NO, and all the catalysts containing praseodymia, exhibit enhanced with of S value for NO conversion at lean region( S ≥1 00 obviously)
出处
《中国稀土学报》
CAS
CSCD
北大核心
2002年第3期265-269,共5页
Journal of the Chinese Society of Rare Earths
基金
国家自然科学基金资助项目 (2 9973 0 3 7)
