다결정 백금표면에서의 일산화탄소와 일산화질소의 촉매반응에 미치는 황의 영향

박윤석; 김영호; 이호인

Journal of the Korean Industrial and Engineering Chemistry, Vol.1, No.2, 215-223, December, 1990

The Effects of Sulfur on the Catalytic Reaction between Carbon Monoxide and Nitric Oxide on Polycrystalline Platinum Surface

박윤석, 김영호, 이호인

초록

자동차 배기가스 정화용 촉매계에서 중요하게 취급되는 CO 와 NO의 산화환원반응에서 대표적인 촉매독으로 작용하는 황의 영향을 다결정 Pt 표면 위에서 초고진공계를 이용한 열탁착 분광법(TDS)을 통하여 알아보았다. Pt 표면에서의 CO 와 NO의 흡착은 황에 의하여, 물리적인 흡착방해에 의한 직접적인 영향과 전자적 효과에 의한 간접적인 영향을 받았다. 800K 이하의 온도에서 탈착하는 S는 반응활성에 큰 영향을 미치지 못하는 반면, 800K이상에서 탈착하는 S는 원자상태의 것으로서 반응활성에 직접적인 영향을 미쳤다. Pt 표면위에 흡착된 S는 island 형태로 존재하며, S에 의한 전자적인 영향은 주위의 모든 흡착점에 미치는 먼거리 상호작용의 경향을 나타내었다. 한편, Pt 표면에서의 CO 와NO의 반응에서 S에 의한 피독은 특정 활성점에 우선적으로 영향을 미치는 선택적인 경향을 보였다.

The effects of sulfur on the catalytic reaction between CO and NO on polycrystalline Pt surface, which is very important in the development of catalyst for automobile exhaust gas control, have been studied using thermal desorption spectrometry(TDS) under ultra-high vacuum(UHV) conditions. Sulfur weakened both the adsorptions of CO and NO by direct site blocking and indirect electronic effect. S(a) desorbing below 800K gave little effect on reaction activity whereas S(a) desorbing above 800K, which adsorbs as an atomic state, gave much effect on it. The adsorbed sulfur existed on the surface of platinum in the form of islands, and also reduced the adsorption energies of adsorbates by the long-ranged electronic effect. The platinum catalyst in the reaction between CO and NO was poisoned selectively by S(a), poisoning firstly the active sites of this reaction.

[References]

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[1] Gland JL, Madix RJ, McCabe RW, DeMaggic C, Surf. Sci., 143, 46 (1984)

[2] Hardegree EL, Ho P, White JM, Surf. Sci., 165, 488 (1986)

[3] Trenary M, Uram KJ, Yates JT, Surf. Sci., 157, 512 (1985)

[4] Hughes R, "Deactivation of Catalysts," Academic Press, London, Chap. 5 (1986)

[5] Oudar J, Wise H, "Deactivation and Poisoning of Catalysts," Marcel Dekker, New York, Chap. 1 (1985)

[6] Ertl G, Kuppers J, "Low Energy Electrons and Surface Chemistry," Springer-Verlag, Berlin (1974)

[7] Billy J, Abbon M, Surf. Sci., 146, L525 (1984)

[8] Hayek K, Surf. Sci., 152-153, 419 (1985)

[9] Gdowski GE, Madix RJ, Surf. Sci., 115, 524 (1982)

[10] Bonzel HP, Ku R, J. Chem. Phys., 58, 4617 (1973)

[11] Pracier CM, Berthier Y, Oudar J, Surf. Sci., 130, 229 (1983)

[12] Heegeman W, Meister KH, Bechtold E, Hayek K, Surf. Sci., 49, 161 (1975)

[13] Park YS, Lee WY, Lee HI, Korean J. Chem. Eng., 2, 75 (1985)

[14] Park YS, Lee HI, HWAHAK KONGHAK, 23(2), 79 (1985)

[15] Nickless G, "Inorganic Sulphur Chemistry," Elsevier, Amsterdam, p. 247 (1968)

[16] Berthier Y, Perdereau Y, Oudar J, Surf. Sci., 36, 225 (1973)

[17] Contractor AQ, Lal H, J. Electroanal. Chem., 96, 175 (1979)

[18] Jayaram R, Contractor AQ, Lal H, J. Electroanal. Chem., 87, 225 (1978)

[19] Thiel PA, Behm RJ, Norton PR, Ertl G, Surf. Sci., 121, 553 (1982)

[20] Behm RJ, Thiel PA, Norton PR, Ertl G, J. Chem. Phys., 78, 7437 (1983)

[21] Thiel PA, Behm RJ, Norton PR, Ertl G, J. Chem. Phys., 78, 7448 (1983)

[22] Steininger H, Lehwald S, Ibach H, Surf. Sci., 123, 264 (1982)

[23] Nguyen TTA, Cinti RC, Surf. Sci., 68, 566 (1977)

[24] Abon M, "Metal-Supported and Metal-Additive Effects in Catalysis," Imelik (ed.), Elsevier, Amsterdam, p. 269 (1982)