Promoters, in catalysis

Volume 70 Poisoning and Promotion in Catalysis based on Surface Science Concepts and Experiments by M. Kiskinova... 

G. Pacchioni, F. Illas, S. Neophytides, and C.G. Vayenas, Quantum-Chemical Study of Electrochemical Promotion in Catalysis, J. Phys. Chem. 100, 16653-16661 (1996). 

C.G. Vayenas, S. Ladas, S, Bebelis, I.V. Yentekakis, S. Neophytides, J. Yi, C. Karavasilis, and C. Pliangos, Electrochemical promotion in catalysis Non-Faradaic electrochemical modification of catalytic activity, Electrochim. Acta 39(11/12), 1849-1855 (1994). 

Poisoning and Promotion in Catalysis based on Surface Science... 

Restructuring of the metal surface by adsorbed sulfur appears to be a general phenomenon (58,63,65, 70, 71, 74,81, 92,93). One observation is of particular interest here. It was observed that the Pt(l 11) surface reorients to the (100) plane in the presence of H2S (81). McCarroll (94) reported, on the other hand, that when Ca+ or Na+ ions were added to a clean Pt(100) surface, it caused a reorientation of surface Pt atoms to a (111) plane. He suggested that the switching between (100) and (111) planes may be the result of the cationic/anionic role played by Na+ or Ca+/S, respectively, and that this might possibly explain the role of promoters in catalysis. The reorientation of the metal surface is not unique to sulfur, sodium, or calcium only. It has been observed, for example, that the Ni(l 11) surface reorients to the (100) surface in the presence of ethylene or benzene (55). Somorjai (95) has... 

This section reports a series of examples of application of the cluster model approach to problems in chemisorption and catalysis. The first examples concern rather simple surface science systems such as the interaction of CO on metallic and bimetallic surfaces. The mechanism of H2 dissociation on bimetallic PdCu catalysts is discussed to illustrate the cluster model approach to a simple catalytic system. Next, we show how the cluster model can be used to gain insight into the understanding of promotion in catalysis using the activation of CO2 promoted by alkali metals as a key example. The oxidation of methanol to formaldehyde and the catalytic coupling of prop)me to benzene on copper surfaces constitute examples of more complex catalytic reactions. 

Prague, Czechoslovakia, September 8-13,1991 edited by P.A. Jacobs, N.l. Jaeger, L. Kubelkova and B. Wichterlova Volume 70 Poisoning and Promotion in Catalysis based on Surface Science Concepts and... 

M. Kiskinova, Poisoning and promotion in catalysis based on surface science concepts and experiments, in Stud. Surf Sci. Catal. 70, Elsevier, Amsterdam (1992). 

---