Unless otherwise noted, all Seminar Series events are held at 3 p.m. in the MoSE "M" Building (Room G011). Refreshments are served outside of the room starting at 2:30 p.m.
Dr. Lars Grabow, University of Houston
"Theory-guided Design of Diesel Oxidation Catalysts with Improved Activity at Reduced Temperature"
Low temperature combustion (LTC) diesel engines have higher fuel efficiency and produce less NOx and particulate matters (PM) compared to traditional diesel engines. However, this benefit comes at the cost of higher concentrations of CO and unburned hydrocarbons (HC) emissions. Meanwhile the low exhaust temperature results in a reduction in the activity of commonly used diesel oxidation catalysts (DOC). Thus, improved DOC with superior activity at reduced exhaust temperatures are needed.
Based on computational screening for rapid catalyst discovery under different reaction conditions we show that better low temperature DOC can be made by the alloys of coinage metals with Pt or Pd. Compared to the commonly used DOC materials, which are Pt and Pd alloys, these coinage metal alloys will not only achieve higher activity at reduced temperature, but also prevent mutual inhibition between CO and NO oxidation. Moreover, we have integrated the descriptor-based catalyst design approach with reactor models to further optimize the overall DOC efficiency and minimize catalysts loading. As the exhaust contaminants CO, NO and HC are oxidized along the DOC reactor they are exposed to different reaction conditions, which each require different catalyst properties. Thus, the overall DOC performance can be improved by designing a DOC reactor with metal concentration gradients, where the local alloy formulation is optimized for the local temperature and exhaust gas compositions. From our simulation results we have developed a prototype catalyst and reactor configuration, which is able to meet the Department of Energy 150 [Symbol]C challenge. Indeed, light off experiments confirm that our catalyst and reactor design can achieve full conversion of CO in mixtures of CO/NO, CO/C3H6, CO/NO/ C3H6, and even CO/NO/ C3H6/H2O well below T = 150 [Symbol]C. A patent application is pending and we believe that these significant advances to meet tailpipe emission regulations at low exhaust temperatures will contribute to a widespread adoption of LTC vehicles in the future.
Dr. Lars Grabow joined the Department of Chemical and Biomolecular Engineering at the University of Houston as tenure-track Assistant Professor in Fall 2011 and accepted a joint appointment with the Department of Chemistry in February 2014. He received his PhD in Chemical Engineering under the guidance of Manos Mavrikakis from the University of Wisconsin in 2008 and continued his research between 2008 and 2011 in the group of Jens Nørskov at the Technical University of Denmark and Stanford University. His expertise is the application of electronic structure calculations (density functional theory) and kinetic modeling to problems in heterogeneous catalysis and surface science.
Dr. Grabow won the prestigious U.S. Department of Energy (DOE) Early Career Award (2014) and the NSF CAREER Award (2015), the Excellence in Research Award at the assistant professor level from the University of Houston (2017). He was a member of member of the Early Career Advisory Board of ACS Catalysis from 2017 – 2018. Currently, he serves as Chair of the AIChE Catalysis and Reaction Engineering division and Secretary of the Southwest Catalysis Society. He is also a member of the International Advisory Board of ChemCatChem.