Ammonia (NH₃) is a very important molecule with conflicting roles. On the one hand, NH₃ is a commodity chemical; its manufacture is integral to the production of fertilizers and polyamides. The oxidation of NH₃ on Platinum to NOx (x = 1, 2) is one of the oldest commercialized catalytic reactions; it is the basis for the Ostwald Process for the manufacture of nitric acid. On the other hand, NH₃ has emerged as an important reagent in emission control. For the first generation of catalytic converters, NH₃ was an inconvenient byproduct and converter design changes were made to minimize its production. For the modern diesel vehicle, NH₃ is the NOx reductant of choice. However, due to NH₃ toxicity, the NOx reduction must be accomplished without releasing NH₃ to the environment by Pt-catalyzed NH₃ oxidation. While the Ostwald process relies on high NOx yield, the diesel emission control application requires a high N₂ yield.

In this talk we will describe our research in the understanding and design of the structured ammonia slip catalyst (ASC), wherein an NH₃ oxidation function is combined with a selective catalytic reduction (SCR) function. We show that a combination of targeted experiments and modeling enable convergence to an optimal architecture that minimizes the Pt loading We will also describe advances in the understanding and modeling of NH₃ oxidation kinetics, linking the environmental and chemical manufacturing applications. Finally, we will present a novel core-shell catalyst that comprises a Pt/Al₂O₃ core and a SCR shell provide for unparalleled ammonia oxidation activity and N₂ selectivity.

Dr. Michael P. Harold is the ChBE Chair Professor and Department Chair of Chemical and Biomolecular Engineering at the University of Houston. With expertise in reaction engineering and catalysis, Harold is the author of more than 175 peer-reviewed papers and book chapters and has given over 350 presentations and invited lectures. He is the founder and principal investigator of the University of Houston’s Texas Center for Clean Engines, Emissions & Fuels (TxCEF), established in 2003. Mike was appointed Editor-in-Chief of the AIChE Journal in 2012, the 7th in the Journal’s 60-year history.

A Pittsburgh, Pennsylvania native, Harold received his Bachelor’s degree at Pennsylvania State University, and his PhD from the University of Houston. He joined the faculty at University of Massachusetts at Amherst in 1985 where he became Associate Professor. In 1993 Harold joined DuPont Company, where he held several technical and managerial positions. In 2000 Harold returned to the University of Houston where he became the Dow Chair Professor and Department Chair, a position he held for 8 years. He was re-appointed to that position in early 2013. His honors include the Excellence in Applied Catalysis from the Southwest Catalysis Society in 2019, the Ester Farfel Award at the University of Houston in 2013 (highest honor bestowed on a faculty member) and the American Chemical Society’s Fuel Division Richard A. Glenn Award in 2008.

Professor Harold's research summary can be found here: http://www.chee.uh.edu/faculty/harold