Monday, September 18, 2017 at 9:00am
Dr. Mike Harold
M.D. Anderson Professor and Chair
Department of Chemical and Biomolecular Engineering, University of Houston
"Multi-Functional Structured Catalysts For Clean Exhaust from Lean Burn Vehicles"
The U.S. faces the difficult dual challenge of reducing the consumption of transportation fuels and improving air quality. Lean burn gasoline, diesel, and natural gas engines are of interest because they are more fuel efficient than conventional stoichiometric gasoline engines. Unfortunately, the unconverted oxygen in the exhaust prevents the use of the conventional three-way catalytic converter to reduce nitrogen oxides (“NOx”) to N2. In this talk we describe progress towards the combination of two NOx reduction technologies, NOx Storage and Reduction (NSR) and Selective Catalytic Reduction (SCR). Research in our group uses a combination of experimentation and modeling both to provide deeper insight and to devise “optimal” structures and operating strategies.
NSR is shown to be a promising but complex catalytic process that involves the sequential periodic reactive trapping of NOx and its rapid reduction on multi-functional catalysts containing precious metal and storage components. SCR is adopted from the stationary source process which utilizes NH3 as the NOx reductant, and utilizes both Cu- and Fe-exchanged zeolite catalysts. As stand-alone reactors, NSR has the noted disadvantage of cost (precious metal) and byproducts (NH3, N2O), while SCR requires an aqueous urea system to provide the NH3, which may “slip” from the reactor under the inherent transient vehicle operation. Moreover, both NSR and SCR have constrained temperature operating windows (low and high). Multi-functional catalyst architectures that combine two or more active layers or zones can be effective strategies to address cost and/or performance limitations. The “NSR + SCR” catalyst combines periodic NOx storage and reduction with in situ NH3 generation and selective catalytic reduction of NOx. To be described are results from targeted experiments as well as kinetic and reactor modeling that advance our understanding of these interesting catalytic reaction systems.
Bio: Michael P. Harold received his B.S. in Chemical Engineering from Penn State in 1980 and his PhD in Chemical Engineering from the University of Houston in 1985. Mike joined the faculty of the Chemical Engineering Department at the University of Massachusetts at Amherst, where he became Associate Professor in 1991. In 1991 Mike was a Visiting Research Scholar at the Chemical Technology Department of University of Twente in Enschede, the Netherlands. In 1993 Mike joined DuPont Company where he held several research and supervisory positions. In 1999 Mike was appointed Research Manager of the Chemical Process Fundamentals Group in the Central Research Department of the DuPont Company. While at DuPont Mike was Adjunct Professor at the University of Delaware and was Chair of the Catalysis and Reaction Engineering Division of AIChE. In his R&D supervisory roles at DuPont Mike led programs to develop breakthrough technologies for the manufacture of key industrial polymers and their corresponding chemical intermediates, and synthetic melt-spun fibers. Mike then moved back to academia as chair of the UH Department of Chemical Engineering, which later became the Department of Chemical and Biomolecular Engineering. He served this post until fall 2008.
Mike’s research expertise and interests are in the area of chemical reaction engineering, with specific focus on reaction-separation devices, inorganic membrane synthesis and applications, and catalytic and biocatalytic materials. Mike has 90 refereed publications, over 100 presentations at technical conferences, and over 60 invited seminars and lectures.