The fight for a reactive site

Abstract

A catalyst is a compound that speeds up a chemical reaction without being consumed itself. The proces of catalysis is one of the most important technologies in the modern world. Approximately 90% of all chemicals and materials around us is produced using catalysis. To get a better understanding of these industrial processes, it is important to investigate the exact role of the catalyst in the process, and the factors that can influence the outcome of the reaction. Therefore, it is necessary to first comprehend simple processes, such as the dissociation of hydrogen, the smallest molecule on Earth, on metal surfaces. In addition, this reaction is an elementary step in many industrial processes. My thesis describes the dissociation of hydrogen on bare and CO-precovered ruthenium, and on stepped platinum. These metals are important catalysts in e.g. ammonia synthesis (ruthenium) and fuel cells (platinum). I have discovered that ruthenium is a very good catalyst for hydrogen dissociation. The presence of CO, however, poisons the catalyst, and less hydrogen is able to dissociate. The presence of steps on a platinum surface increases the catalytic activity of the metal significantly.