Studies on the Deactivation-resistant Ru Catalyst

Ru 촉매의 비활성화 억제를 위한 연구

  • Kim, Young-Kil (Dept. of Applied Chem. Ajou Univ.) ;
  • Yie, Jae-Eui (Dept. of Applied Chem. Ajou Univ.) ;
  • Cho, Sung-June (Dept. of Chem. and Center for Molecular Science, Korea Advenced Institute of Science and Technology) ;
  • Ryoo, Ryong (Dept. of Chem. and Center for Molecular Science, Korea Advenced Institute of Science and Technology)
  • 김영길 (아주대학교 공업화학과) ;
  • 이재의 (아주대학교 공업화학과) ;
  • 조성준 (한국과학기술원 화학과) ;
  • 유룡 (한국과학기술원 화학과)
  • Received : 1994.04.11
  • Accepted : 1994.07.15
  • Published : 1994.10.01

Abstract

Effects of ceria additive on the activity and thermal aging behavior of supported Ru catalysts were investigated using Ru/${\gamma}$-$Al_2O_3$and Ru/$CeO_2$-${\gamma}$-$Al_2O_3$. The catalysts were characterized by $^{129}Xe$-NMR and $H_2$ chemisorption. The cataltic activity for conversion of CO, HC and $NO_x$ was measured using simulated automobile engine exhausts under lean, rich and stoichiometric conditions. For both fresh and aged catalysts, Ru/$CeO_2$-${\gamma}$-$Al_2O_3$ was more active than Ru/${\gamma}$-$Al_2O_3$ for all three pollutants. Results of $^{129}Xe$-NMR and $H_2$ chemisorption indicated that sintering of Ru particles occurred to the same extent for both catalysts during the thermal aging process. After thermal aging at 673K, however, the catalytic activity of the aged Ru/$CeO_2$-${\gamma}$-$Al_2O_3$ was substantially higher than that of the fresh one, while the activity of Ru/${\gamma}$-$Al_2O_3$ decreased after the thermal aging. This finding may suggest new active sites were created during the thermal aging, probably in the vicinity of the interface between Ru and Ce. For more quantitative investigation of the effect of a cation such as Ce on the thermal aging of Ru metal particles, Ru catalysts supported on cation-exchanged Y-zeolites were used as the model catalysts. The results indicated that when Ba, Ca, La, Y or Ce was used for the cation exchange, the exchanged cation did not affect the thermal aging behavior of Ru in Y-zeolite, as evidenced by $^{129}Xe$-NMR and EXAFS.

Keywords

Acknowledgement

Supported by : 학술진흥재단