Ru 촉매의 비활성화 억제를 위한 연구

김영길; 이재의; 조성준; 유룡

Journal of the Korean Industrial and Engineering Chemistry, Vol.5, No.5, 808-818, October, 1994

Export Citation

Ru 촉매의 비활성화 억제를 위한 연구

Studies on the Deactivation-resistant Ru Catalyst

김영길, 이재의, 조성준, 유룡

초록

Ru/γ-Al₂O₃와 Ru/CeO₂-γ-A1₂O₃를 사용하여 Ru담지 촉매의 반응성과 열적노화현상에 미치는 Ce의 영향을 연구하였다. ¹²⁹Xe-NMR과 수소흡착법을 사용하여 촉매특성을 검토하였으며, 모사 자동차 배기가스를 사용하여 과농, 양론 및 희박조건에서의 CO, HC 및 NO_x 전환율을 측정하였다. 새촉매와 노화촉매 모두 Ru/CeO₂-γ-Al₂O₃가 Ru/γ-A1₂O₃보다 세 가지 오염물질에 대한 전환율이 높았다. ¹²⁹Xe-NMR과 수소흡착에 의하면 Ce을 첨가하여도 열적노화현상을 억제할 수 없었다. 그러나 673K에서 열적노화시킨 경우 Ru/r-Al₂O₃의 반응성은 새촉매보다 작았으나 Ru/CeO₂-γ-A1₂O₃의 반응성은 오히려 컸다. 이것은 열적 노화과정에서 Ru/Ce 사이의 계면에 아마도 새로운 활성점이 만들어지기 때문이 아닌가 사료된다. 또한, Ru금속에 미치는 Ce같은 양이온 효과를 좀더 정량적으로 구하기 위하여 Ca, Ba, La, Y, Ce 등의 양이온을 교환한 Y-제올라이트에 Ru을 담지시킨 모델 촉매의 열적노화 정도를 ¹²⁹ Xe-NMR과 EXAFS로 연구한 결과 이들 양이온이 Ru의 열적 노화성에 거의 영향을 미치지 못하는 것을 관찰하였다.

Effects of ceria additive on the activity and thermal aging behavior of supported Ru catalysts were investigated using Ru/γ-Al₂O₃ and Ru/CeO₂-γ-Al₂O₃. The catalysts were characterized by ¹²⁹Xe-NMR and H₂ 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/CeO₂-γ-Al₂O₃ was more active than Ru/γ-A1₂O₃ for all three pollutants. Results of 129 Xe-NMR and H₂ 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/CeO₂-γ-A1₂O₃ was substantially higher than that of the fresh one, while the activity of Ru/γ-A1₂O₃ 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 ¹²⁹Xe-NMR and EXAFS.

[References]

Oh SH, Carpenter JE, J. Catal., 98, 178 (1986)
Oukaci R, Sayri A, Goodwin JG, J. Catal., 102, 126 (1986)
Oukaci R, Wu JCS, Goodwin JG, J. Catal., 107, 471 (1987)
Imamura S, Uematsu Y, Utani K, J. Am. Chem. Soc., 30, 18 (1991)
Gustafson BL, Lin MJ, Lunsford JH, J. Phys. Chem., 84, 3211 (1980)
Shelef M, Gandhi HS, Plastinum Metals Rev., 18, 2 (1974)
Yao HC, Stepien HK, Gandhi HS, J. Catal., 61, 547 (1980)
Summers JC, Ausen SA, J. Catal., 58, 131 (1979)
Harrison B, Diwell AF, Hallett C, Plastinum Metal Rev., 32, 73 (1988)
Oh SH, Eickel CC, J. Catal., 112, 543 (1988)
Shyu JZ, Otto K, Watkins WLH, Graham GW, Belitz RK, J. Catal., 114, 23 (1988)
Oh SH, J. Catal., 124, 477 (1990)
Diwell AF, Rajaram RR, Shaw HA, Truex TJ, "Catalysis and Automotive Pollution Control II," 139, Elsevier Science Publishers, B.V., Amsterdam (1991)
Silver RG, Summers JC, Williamson WB, "Catalysis and Automotive Pollution Control II," 167, Elsevier Science Publishers B.V., Amsterdam (1991)
Nunan JG, Robota HJ, Cohn MJ, Bradley SA, J. Catal., 133, 309 (1992)
Serre C, Garin F, Belot G, Maire G, J. Catal., 141, 9 (1993)
Zafiris GS, Gorte RJ, J. Catal., 143, 86 (1993)
Gallezot P, Catal. Rev.-Sci. Eng., 20(1), 121 (1979)
Forger K, Anderson JR, J. Catal., 54, 318 (1978)
Boudart M, Samant MG, Ryoo R, Ultra-microscopy, 20, 125 (1986)
Fraissard J, Ito T, Zeolites, 8, 310 (1988)
Kim JG, Ihm SK, Lee JY, Ryoo R, J. Phys. Chem., 95, 8546 (1991)
Cho SJ, Joung SM, Shul YG, Ryoo R, J. Phys. Chem., 96, 9922 (1992)
Ryoo R, J. Korean Ind. Eng. Chem., 2(1), 1 (1991)
Ryoo R, Cho SJ, Pak C, Kim J, Ihm S, Lee JY, J. Am. Chem. Soc., 114, 76 (1992)
Pak C, Ryoo R, J. Korean Chem. Soc., 36, 3 (1992)
Kim JG, Kompany T, Ryoo R, Ito T, Fraissard J, Zeolites, in press
DeMenorval LC, Fraissard J, Ito T, J. Chem. Soc.-Faraday Trans., 78, 402 (1982)
Kim YK, M.S. Dissertation, Ajou Univ., Suwon, Korea (1989)
Samant MG, Boudart M, J. Phys. Chem., 95, 4070 (1991)
Samant MG, Bergeret G, Meitzner G, Gallezot P, Boudart M, J. Phys. Chem., 92, 3542 (1988)
Chonjack T, Krause K, Shmidt LD, J. Catal., 128, 161 (1991)
Shyu JZ, Wber WH, Gandhi HS, J. Phys. Chem., 92, 4964 (1988)

[1] Oh SH, Carpenter JE, J. Catal., 98, 178 (1986)

[2] Oukaci R, Sayri A, Goodwin JG, J. Catal., 102, 126 (1986)

[3] Oukaci R, Wu JCS, Goodwin JG, J. Catal., 107, 471 (1987)

[4] Imamura S, Uematsu Y, Utani K, J. Am. Chem. Soc., 30, 18 (1991)

[5] Gustafson BL, Lin MJ, Lunsford JH, J. Phys. Chem., 84, 3211 (1980)

[6] Shelef M, Gandhi HS, Plastinum Metals Rev., 18, 2 (1974)

[7] Yao HC, Stepien HK, Gandhi HS, J. Catal., 61, 547 (1980)

[8] Summers JC, Ausen SA, J. Catal., 58, 131 (1979)

[9] Harrison B, Diwell AF, Hallett C, Plastinum Metal Rev., 32, 73 (1988)

[10] Oh SH, Eickel CC, J. Catal., 112, 543 (1988)

[11] Shyu JZ, Otto K, Watkins WLH, Graham GW, Belitz RK, J. Catal., 114, 23 (1988)

[12] Oh SH, J. Catal., 124, 477 (1990)

[13] Diwell AF, Rajaram RR, Shaw HA, Truex TJ, "Catalysis and Automotive Pollution Control II," 139, Elsevier Science Publishers, B.V., Amsterdam (1991)

[14] Silver RG, Summers JC, Williamson WB, "Catalysis and Automotive Pollution Control II," 167, Elsevier Science Publishers B.V., Amsterdam (1991)

[15] Nunan JG, Robota HJ, Cohn MJ, Bradley SA, J. Catal., 133, 309 (1992)

[16] Serre C, Garin F, Belot G, Maire G, J. Catal., 141, 9 (1993)

[17] Zafiris GS, Gorte RJ, J. Catal., 143, 86 (1993)

[18] Gallezot P, Catal. Rev.-Sci. Eng., 20(1), 121 (1979)

[19] Forger K, Anderson JR, J. Catal., 54, 318 (1978)

[20] Boudart M, Samant MG, Ryoo R, Ultra-microscopy, 20, 125 (1986)

[21] Fraissard J, Ito T, Zeolites, 8, 310 (1988)

[22] Kim JG, Ihm SK, Lee JY, Ryoo R, J. Phys. Chem., 95, 8546 (1991)

[23] Cho SJ, Joung SM, Shul YG, Ryoo R, J. Phys. Chem., 96, 9922 (1992)

[24] Ryoo R, J. Korean Ind. Eng. Chem., 2(1), 1 (1991)

[25] Ryoo R, Cho SJ, Pak C, Kim J, Ihm S, Lee JY, J. Am. Chem. Soc., 114, 76 (1992)

[26] Pak C, Ryoo R, J. Korean Chem. Soc., 36, 3 (1992)

[27] Kim JG, Kompany T, Ryoo R, Ito T, Fraissard J, Zeolites, in press

[28] DeMenorval LC, Fraissard J, Ito T, J. Chem. Soc.-Faraday Trans., 78, 402 (1982)

[29] Kim YK, M.S. Dissertation, Ajou Univ., Suwon, Korea (1989)

[30] Samant MG, Boudart M, J. Phys. Chem., 95, 4070 (1991)

[31] Samant MG, Bergeret G, Meitzner G, Gallezot P, Boudart M, J. Phys. Chem., 92, 3542 (1988)

[32] Chonjack T, Krause K, Shmidt LD, J. Catal., 128, 161 (1991)

[33] Shyu JZ, Wber WH, Gandhi HS, J. Phys. Chem., 92, 4964 (1988)