Understanding Catalysis Through Characterization and Synthesis of Catalysts: Gabor A. Somorjai Award and Symposium for Creative Research 2011

Abstract

The 2011 American Chemical Society Gabor A. Somorjai Award Symposium in honor of Harold H. Kung was held on March 28–29, in Anaheim, California. The symposium was filled with personal anecdotes of the awardee and cutting edge scientific presentations delivered by Harold’s collaborators, friends, and current and former coworkers. The breadth of topics covered by these experts in the field mirrored the diverse interests of Harold and the many aspects of catalysis he has engaged in throughout his career. Presentations dealt with fundamental surface science studies, green chemistry, emission control catalysis, acid–base catalysis, computational studies, synthesis of novel materials, and X-ray absorption spectroscopy. The underlying theme of the symposium explored the on-going quest to better understand the structural and mechanistic aspects of catalysis through characterization and wellcontrolled synthesis of catalysts, aspects that Harold strongly subscribes to. This special issue is a collection of representative contributions to catalysis by those who participated in the symposium, which in many cases, are based on the presentations at the symposium. In the earlier part of his work, Harold explored the use of surface science techniques to gain a fundamental understanding of catalysis. He pioneered the use of highindex surface oxide planes to demonstrate the relationship between surface structure of an oxide and its catalytic function at the atomic level. Using the catalytic decomposition of alcohols, he and his coworkers demonstrated for the first time the widely different activities of different oxide surface crystal planes, particularly the important role of atomic structures at stepped surfaces that mimic cation vacancies. Microcalorimetric determination of the heat of removal of oxygen from the oxide catalysts, as well as in situ Raman and X-ray absorption spectroscopy were some of the tools he used to generate an in-depth understanding of how the surface properties of an oxide catalyst influence its ability to catalyze selective hydrocarbon oxidation. His group also demonstrated that oxides and oxide-supported catalysts can be effective hydrocarbon-NOx reduction catalysts without using zeolites, and provided a quantitative description of the monomolecular mechanism in the alkane cracking reaction. Harold also found concrete experimental evidence of the nature of active sites and the potential role of hydroxycarbonyl in the CO oxidation reaction over supported Au catalysts. This was achieved by combining results from various characterization techniques with quantitative evaluation of catalytic activity during various stages of catalyst use, including activation of the Au from metal precursors, deactivation with time on-stream, re-activation with moisture, and poisoning by halides. While conducting his catalytic studies, Harold noted the difficulty of obtaining precise structure–activity relationships because of the non-uniform nature of catalysts prepared using conventional techniques. To tackle this issue, he began to explore synthesis strategies based on techniques employed in the field of organometallic chemistry. In particular, he exploited the know-how in the field of siloxane chemistry to design and construct structures that could offer precise control of not only the active site composition and structure but also the functional groups surrounding the active site. Some of the interesting M. C. Kung (&) Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA e-mail: m-kung@northwestern.edu