Professor and Department Chair
Ph.D., University of Florida (1997)
B.S., Virginia Tech (1992)
Phone: (434) 924-6278
Honors and Awards
- Early Researcher Award, Province of Ontario (2007)
- Outstanding Performance Award, University of Waterloo (2011)
Heterogeneous and environmental catalysis, Reaction Engineering
Our research group focuses on understanding and engineering the reaction process on and along a catalyst surface, and how these change as a function of catalyst degradation modes. This encompasses the preparation of novel catalyst materials, the fundamental characterization of catalyst surfaces, developing new analytic techniques, processes or devices, and preparing or manufacturing pilot-scale samples for testing and application. All of which results in our ability to obtain and translate in-depth fundamental catalyst knowledge to practical, industrially relevant applications.
1) Reaction Characterization and Engineering
Catalyst poisoning or other forms of catalyst degradation do not homogeneously affect industrial-scale systems. So, although most systems operate in a steady-state mode, the integral nature of catalyst systems needs to be modeled. We use and develop new tools, functionally-specific techniques and processes to monitor changes in catalyst reaction chemistry as a function of both catalyst life and position in the catalyst bed. These results are used as inputs for time-dependent control strategies and for designing and engineering better catalysts. Current applications include catalysts for after treatment systems and CH4 partial oxidation and steam reforming.
An extension of this work includes pulsed/transient operation of catalyst systems. Via controlling the introduction of reactants, periodic temperature and concentration gradients within a catalyst system can be established which result in changed catalytic activity. This change can be associated with both selectivity and conversion to the desired products. Using experimental techniques designed to be functionally specific, we monitor the transient operation and optimize the strategy toward better performance.
2) Remediation of regulated emissions in lean-burn exhaust gases
More widespread use of lean-burn engines could result in decreased fuel consumption and thus also decreased CO2 emissions. With lean-burn operation however, NOX emissions become significantly more difficult to control. One solution is selective catalytic reduction (SCR). We are currently focused on understanding the reaction chemistry that occurs on the surface of such catalysts and understanding how such chemistry changes as a function of axial position along the catalyst.
Current predictions indicate that different engine fueling recipes will result in significantly changed emissions characteristics in the future. Most predict, however, an increase in hydrocarbon emissions. Although lean-burn operation would seemingly facilitate easier hydrocarbon oxidation, the exhaust gas temperatures associated with these new combustion recipes are lower. The challenge therefore becomes low-temperature hydrocarbon oxidation in a transient operating environment. Our current efforts focus on defining the operational boundaries of catalysts in this environment, evaluating optional (meaning cheaper) catalyst types, and monitoring catalytic changes as a function of time-on-stream.
A full list of publications is available via Google Scholar.
W.S. Epling, G.B. Hoflund, J.F. Weaver, S. Tsobota and M. Haruta, “Surface Characterization Study of Au/α-Fe2O3 and Au/Co3O4 Low-Temperature CO Oxidation Catalysts,” Journal of Physical Chemistry 100(1996)9929. (link)
W.S. Epling, G.B. Hoflund and D.M. Minahan, “Reaction and Surface Characterization Study of Higher Alcohol Synthesis Catalysts I: K-Promoted Commercial Zn/Cr Spinel,” Journal of Catalysis 169(1997)438. (link)
W.S. Epling, C.H.F. Peden, M.A. Henderson and U. Diebold, “Evidence for Oxygen Adatoms on TiO2(110) Resulting from O2 Dissociation at Vacancy Sites,” Surface Science 412/413(1998)333. (link)
W.S. Epling and G.B. Hoflund, “Catalytic Oxidation of Methane Over Zirconia-Supported Pd Catalysts,” Journal of Catalysis 182(1999)5. (link)
W.S. Epling, L.E. Campbell, A. Yezerets, N.W. Currier, and J.E. Parks II, “Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts,” Catalysis Reviews 46(2004)163. (link)
K. Irani, W. Epling and R. Blint, “Effect of Hydrocarbon Species on NO Oxidation over Diesel Oxidation Catalysts,” Applied Catalysis B: Environmental 92(2009)422. (link)
J.-Y. Luo, X. Hou, P. Wijayakoon, S.J. Schmieg, W. Li and W.S. Epling, “Spatially resolving different SCR reactions over a Fe/zeolite catalyst,” Applied Catalysis B: Environmental 102(2011)110. (link)
M. AL-Harbi, J.-Y. Luo, R. Hayes, M. Votsmeier and W.S. Epling, “Hydrogen Generation and Coke Formation over a Diesel Oxidation Catalyst under Fuel Rich Conditions,” Journal of Physical Chemistry C 115(2011)1156. (link)
A. M. Amin, E. Croiset and W. Epling, “Review of Methane Catalytic Cracking for Hydrogen Production,” International Journal of Hydrogen Energy 36(2011)2904. (link)
A. Russell, C. Henry, N. W. Currier, A. Yezerets and W.S. Epling, “Spatially-Resolved Temperature and Gas Species Concentration Changes during C3H6 Oxidation over a Pt/Al2O3 Catalyst Following Sulfur Exposure,” Applied Catalysis A: General 397(2011)272. (link)
A. Russell and W.S. Epling, “Diesel Oxidation Catalysts,” Catalysis Reviews 53(2011)337. (link)
X. Hou, S.J. Schmieg, W. Li and W.S. Epling, “NH3 pulsing adsorption and SCR reactions over a Cu-CHA SCR catalyst,” Catalysis Today 197(2012)9. (link)
C. Constantinou, W. Li, G. Qi and W.S. Epling, “NOX Storage and Reduction over a Perovskite-Based Lean NOX Trap Catalyst,” Applied Catalysis B: Environmental 134-135(2013)66. (link)
T. Hamzehlouyan, C. Sampara, J. Li, A. Kumar and W. Epling, “Experimental and kinetic study of SO2 oxidation on a Pt/γ-Al2O3 catalyst,” Applied Catalysis B: Environmental 152-153(2014)108. (link)
A. Amin, A. Abedi, B. Hayes, M. Votsmeier and W. Epling, “Methane Oxidation Hysteresis over Pt/Al2O3,” Applied Catalysis A: General 478(2014)91. (link)
D. Wang, Y. Jangjou, Y. Liu, M. Sharma, J. Luo, J. Li, K. Kamasamudram and W.S. Epling, “A comparison of hydrothermal aging effects on NH3-SCR of NOX over Cu-SSZ-13 and Cu-SAPO-34 catalysts,” Applied Catalysis B: Environmental 165(2015)438. (link)
Y. Jangjou, M. Ali, Q. Chang, D. Wang, J. Li, A. Kumar and W.S. Epling, “Effect of SO2 on NH3 oxidation over a Cu-SAPO-34 SCR catalyst,” Catalysis Science and Technology 6(2016)2679. (link)