All That Glitters Is Not Gold – Lessons from Surface Science and Catalysis on Silver
Mark A. Barteau, Chemical Engineering, University of Delaware, Colburn Lab, Newark, DE 19716
Research on the surface reactivity of silver begun by the Madix group in the early 1970s continues to inspire new fundamental insights and new catalytic developments. Following early experiments by Wachs and Madix that resolved the mechanism of selective methanol oxidation, the acid-base character of oxidation reactions on silver was developed, and the application of gas phase acidities to surface chemistry was advanced for the first time. The implications of this formalism – anionic adsorbates on silver – have recently been “rediscovered” a quarter century later. Meanwhile, oxametallacycle intermediates of the sort first proposed in 1987 by Brainard and Madix in the oxidation of tert-butanol on Ag(110), have been isolated within the past decade and shown to control the selectivity of ethylene epoxidation by silver catalysts. This has led to new understanding of the performance and promotion of silver catalysts for this process, and to the development of new bimetallic catalysts based on silver. The genesis of all of these advances is the fundamental approach to understanding surface reaction processes pioneered by Bob Madix and his co-workers.