Chemical and Biomolecular Engineering

Top 20 Doctoral Program — National Research Council


Dr. William Epling
Dr. William Epling

Professor of Chemical and Biomolecular Engineering

Phone: 713-743-4234   |   Fax: 713-743-4323
Email: wsepling [at] central [dot] uh [dot] edu
Epling's research


B.S. Chemical Engineering, Virginia Tech (1992)
Ph.D Chemical Engineering, University of Florida (1997)

Research Interests: 

Our research group focuses on understanding and engineering the reaction process on and along a catalyst surface. 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 application.

Remediation of regulated emissions in lean-burn exhaust gases

More widespread use of lean-burn engines would result in decreased fuel consumption. With lean-burn operation however, NOX emissions become significantly more difficult to control. Current aftertreatment systems for NOX control on gasoline-powered automobiles work only because the engine operates in a stoichiometric burn mode, and are inefficient when used in lean-burn exhaust gas. A novel catalyst technology, NOX storage/reduction (NSR), has been developed for this application.

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. With such results we engineer the reaction and catalyst, with the goal of reducing catalyst cost and fuel consumption associated with catalyst use.

Current predictions indicate that different fueling recipes in diesel engines will result in significantly less soot and NOX emissions in the future (homogeneous charge compression ignition - HCCI - for example). There will, however be a coincident and significant 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 very low. 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.

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 H2 generation for fuel cells.

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.

Awards & Honors: 

Vice-Chair, Canadian Society of Catalysis, May 2010 – current
Secretary/Treasurer for the Canadian Society of Catalysis, June 2008 – May 2010
Province of Ontario Early Researcher Award, 2008
University of Waterloo, Faculty of Engineering Outstanding Performance Award, 2009
Editorial Board Member, Applied Catalysis A: General
Editorial Board Member, The Canadian Journal of Chemical Engineering
Session Chair or co-Chair (2005-2010) for 19th and 20th North American Meeting of the North American Catalysis Society
Session Chair or co-Chair (2005-2010) for 2006 and 2007 Annual Meetings of the American Institute of Chemical Engineers
Session Chair or co-Chair (2005-2010) for 56th Canadian Society of Chemical Engineering Conference
Session Chair or co-Chair (2005-2010) for 20th Canadian Symposium on Catalysis
Session Chair or co-Chair (2005-2010) for ISCRE 21
Guest Editor of Catalysis Today, volumes 114, 136 and 151

Selected Publications

  1. Hamzehlouyan, T., Sampara, C. S., Li, J. H., Kumar, A., & Epling, W. S.,

    Kinetic study of adsorption ad desorption of SO2 over gamma-Al2O3 and Pt/gamma-Al2O3. Applied Catalysis B-Environmental, 181, 587-598. doi: 10.1016/j.apcatb.2015.08.003

    , 2016
  2. Hamzehlouyan, T., Sampara, C., Li, J. N., Kumar, A., & Epling, W.,

    Sulfur Poisoning of a Pt/Al2O3 Oxidation Catalyst: Understanding of SO2, SO3 and H2SO4 Impacts. Topics in Catalysis, 59(10-12), 1028-1032. doi: 10.1007/s11244-016-0592-0

    , 2016
  3. Hazlett, M. J., & Epling, W. S.,

    Spatially resolving CO and C3H6 oxidation reactions in a Pt/Al2O3 model oxidation catalyst. Catalysis Today, 267, 157-166. doi: 10.1016/j.cattod.2015.11.033

    , 2016
  4. Jangjou, Y., Ali, M., Chang, Q. Y., Wang, D., Li, J. H., Kumar, A., & Epling, W. S.,

    Effect of SO2 on NH3 oxidation over a Cu-SAPO-34 SCR catalyst. Catalysis Science & Technology, 6(8), 2679-2685. doi: 10.1039/c5cy02212f

    , 2016
  5. Jangjou, Y., Wang, D., Kumar, A., Li, J. H., & Epling, W. S.,

    SO2 Poisoning of the NH3-SCR Reaction over Cu-SAPO-34: Effect of Ammonium Sulfate versus Other S-Containing Species. Acs Catalysis, 6(10), 6612-6622. doi: 10.1021/acscatal.6b01656

    , 2016
  6. Piubello, F., Jangjou, Y., Nova, I., & Epling, W. S.,

    Study of NO Formation During NH3 Oxidation Reaction Over a Cu-SAPO-34 SCR catalyst. Catalysis Letters, 146(8), 1552-1561. doi: 10.1007/s10562-016-1783-9

    , 2016
  7. Ashraf Amin, Ali Abedi, Bob Hayes, Martin Votsmeier and William Epling,

    “Methane Oxidation Hysteresis over Pt/Al2O3,” Applied Catalysis A: General 478, 91

    , 2014
  8. Di Wang, Feng Gao, Charles H.F. Peden, Junhui Li, Krishna Kamasamudram and William S. Epling,

    “Excellent performance in selective catalytic reduction of NOx with NH3 (NH3-SCR) over a Cu-SSZ-13 catalyst prepared by a solid state ion exchange method,”  ChemCatChem 6,1579.

    , 2014
  9. Tayebeh Hamzehlouyan, Chaitanya Sampara, Junhui Li, Ashok Kumar and William Epling,

    “Experimental and kinetic study of SO2 oxidation on a Pt/γ-Al2O3 catalyst,” Applied Catalysis B: Environmental 152-153,108.

    , 2014
  10. Di Wang, Li Zhang, Krishna Kamasamudram and William S. Epling,

    “In situ-DRIFTS study of selective catalytic reduction of NOx by NH3 over Cu-exchanged SAPO-34,” ACS Catalysis 3(2013)871. DOI: 10.1021/cs300843k

    , 2013
  11. Li Zhang, John Pierce, Victor L. Leung, Di Wang and William S. Epling,

    “Characterization of Ceria’s Interaction with NOx and NH3,” Journal of Physical Chemistry C 117(2013)8282. DOI: 10.1021/jp401442e

    , 2013
  12. Al-Harbi, M.; Luo, J. Y.; Hayes, R.; Votsmeier, M.; Epling, W. S.,

    Hydrogen Generation and Coke Formation over a Diesel Oxidation Catalyst under Fuel Rich Conditions. Journal of Physical Chemistry C 2011, 115 (4), 1156-1162.

    , 2011
  13. Amin, A. M.; Croiset, E.; Epling, W.,

    Review of methane catalytic cracking for hydrogen production. International Journal of Hydrogen Energy 2011, 36 (4), 2904-2935.

    , 2011
  14. Amin, A.; Epling, W.; Croiset, E.,

    Reaction and Deactivation Rates of Methane Catalytic Cracking over Nickel. Industrial & Engineering Chemistry Research 2011, 50 (22), 12460-12470.

    , 2011
  15. Jasdeep S. Mandur, Meshari AL-Harbi, William S. Epling and Hector M. Budman,

    “Modeling the transient cyclic operation of a commercial NSR catalyst,” Chemical Engineering Journal,166, 607

    , 2011
  16. Jin-Yong Luo, Xuxian Hou, Prasanna Wijayakoon, Steven J. Schmieg, Wei Li andWilliam S. Epling,

    “Spatially resolving different SCR reactions over a Fe/zeolite catalyst,” Applied Catalysis B: Environmental102, 110

    , 2011
  17. Liu, Z. Q.; Epling, W. S.; Anderson, J. A.,

    Influence of Pt Loading in Aged NOx Storage and Reduction Catalysts. Journal of Physical Chemistry C 2011, 115 (4), 952-960.

    , 2011
  18. Luo, J. Y.; Al-Harbi, M.; Pang, M.; Epling, W. S.,

    Spatially resolving LNT desulfation: re-adsorption induced by oxygen storage materials. Applied Catalysis B-Environmental 2011, 106 (3-4), 664-671.

    , 2011
  19. Luo, J. Y.; Hou, X. X.; Wijayakoon, P.; Schmieg, S. J.; Li, W.; Epling, W. S.,

    Spatially resolving SCR reactions over a Fe/zeolite catalyst. Applied Catalysis B-Environmental 2011, 102 (1-2), 110-119.

    , 2011
  20. Mandur, J. S.; Al-Harbi, M.; Epling, W. S.; Budman, H. M.,

    Modeling the transient cyclic operation of a commercial NSR catalyst. Chemical Engineering Journal 2011, 166 (2), 607-615.

    , 2011
  21. Pieta, I. S.; Epling, W. S.; Garcia-Dieguez, M.; Luo, J. Y.; Larrubia, M. A.; Herrera, M. C.; Alemany, L. J.,

    Nanofibrous Pt-Ba Lean NO(x) trap catalyst with improved sulfur resistance and thermal durability. Catalysis Today 2011, 175 (1), 55-64.

    , 2011
  22. Russell, A.; Henry, C.; Currier, N. W.; Yezerets, A.; Epling, W. S.,

    Spatially resolved temperature and gas species concentration changes during C(3)H(6) oxidation over a Pt/Al(2)O(3) catalyst following sulfur exposure. Applied Catalysis a-General 2011, 397 (1-2), 272-284.

    , 2011
  23. Alan Shaw, William Epling, Christy McKenna and Beth Weckman,

    “Infra-red Thermography Evaluation of the Ignition of Diesel Fuels on Hot Surfaces,” Fire Technology46, 407

    , 2010
  24. April Russell, William S. Epling, Howard Hess, Hai-Ying Chen, Cary Henry, Neal Currier and Aleksey Yezerets,

    “Spatially-Resolved Temperature and Gas Species Changes in a Lean-Burn Engine Emissions Control Catalyst,” Industrial Engineering and Chemistry Research,49, 10311

    , 2010
  25. Jin-Yong Luo and William S. Epling,

    “New insights into the promoting effect of H2O on a model Pt/Ba/Al2O3 NSR catalyst,” Applied Catalysis B: Environmental97, 236

    , 2010
  26. Jin-Yong Luo, Darren Kisinger, Ali Abedi and William S. Epling,

    “Sulfur release from a model Pt/Al2O3 diesel oxidation catalyst: Temperature-programmed and step-response techniques characterization,” Applied Catalysis A: General383, 182

    , 2010
  27. Meshari AL-Harbi and William Epling,

    “Effects of Regeneration Timing Protocols on the Performance of a Model NOX Storage/Reduction Catalyst,” Catalysis Today151, 347

    , 2010
  28. Meshari AL-Harbi, David Radtke and William S. Epling,

    “Regeneration of a Model NOX Storage/Reduction Catalyst Using Hydrocarbons as the Reductant,” Applied Catalysis B: Environmental96, 524

    , 2010
  29. Karishma Irani, William Epling and Richard Blint,

    “Effect of Hydrocarbon Species on NO Oxidation over Diesel Oxidation Catalysts,” Applied Catalysis B: Environmental92, 422

    , 2009
  30. Luke Coleman, Eric Croiset, William Epling, Mike Fowler and Robert Hudgins,

    “Evaluation of Foam Nickel for the Catalytic Partial Oxidation of Methane,” Catalysis Letters128, 144

    , 2009
  31. Luke Coleman, William Epling, Robert Hudgins and Eric Croiset,

    “Ni-Mg/Al Mixed Oxide Catalyst for the Steam Reforming of Ethanol,” Applied Catalysis A: General363, 52

    , 2009
  32. Meshari AL-Harbi and William S. Epling,

    “The Effects of Regeneration-Phase CO and/or H2 Amount on the Performance of a NOX Storage/Reduction Catalyst,” Applied Catalysis B: Environmental89, 315

    , 2009
  33. Meshari AL-Harbi and William S. Epling,

    “Investigating the Effect of NO Versus NO2 on the Performance of a Model NOX Storage/Reduction Catalyst,” Catalysis Letters130, 121

    , 2009
  34. Osama Shakir, Alexsey Yezerets, Neal Currier and William Epling,

    “Spatially Resolving Concentration and Temperature Gradients During the Oxidation of Propylene on Pt/Al2O3,” Applied Catalysis A: General365, 301

    , 2009
  35. Khurram Aftab, Jasdeep Mandur, Hector Budman, Neal W. Currier, Aleksey Yezerets and William S. Epling,

    “Spatially-Resolved Calorimetry: Using IR Thermography to Measure Temperature and Trapped NOX Distributions on a NOX Adsorber Catalyst,” Catalysis Letters125, 229

    , 2008
  36. William S. Epling, Charles H.F. Peden and Janos Szanyi,

    “Carbonate Formation and Stability on a Pt/BaO/γ-Al2O3 NOX Storage/Reduction Catalyst,” Journal of Physical Chemistry C,112, 10952

    , 2008
  37. William S. Epling, Darren Kisinger and Chris Everest,

    “NOX Storage/Reduction Catalyst Performance with Oxygen in the Regeneration Phase,” Catalysis Today136, 156

    , 2008
  38. Do Heui Kim, Ya-Huei Chin, George G. Muntean, Aleksey Yezerets, Neal W. Currier, William S. Epling, Hai-Ying Chen, Howard Hess and Charles H. F. Peden,

    “Design of a reaction protocol for decoupling sulfur removal and thermal aging effects during desulfation of Pt-BaO/Al2O3 lean NOx trap catalysts,” Industrial Engineering and Chemistry Research46, 2735

    , 2007
  39. Janos Szanyi, Ja Hun Kwak, Do Heui Kim, Xianqin Wang, Ricardo Chimentao, Jonathan Hanson, William W. Epling and Charles H.F. Peden,

    “Water-Induced Morphology Changes in BaO/γ-Al2O3 NOX Storage Materials: an FTIR, TPD, and Time-Resolved Synchrotron XRD Study,” Journal of Physical Chemistry C111, 4678

    , 2007
  40. William S. Epling, Aleksey Yezerets and Neal W. Currier,

    “The Effects of Regeneration Conditions on NOX and NH3 Release from NOX Storage/Reduction Catalysts,” Applied Catalysis B: Environmental74, 117

    , 2007
  41. Do Heui Kim, Ya-Huei Chin, George G. Muntean, Aleksey Yezerets, Neal W. Currier, William S. Epling, Hai-Ying Chen, Howard Hess and Charles H. F. Peden,

    “Relationship of Pt Particle Size to the NOX Storage Performance of Thermally Aged Pt/BaO/Al2O3 Lean NOX Trap Catalysts,” Industrial Engineering and Chemistry Research45, 8815 – 8821

    , 2006
  42. Jae-Soon Choi, William P. Partridge, William S. Epling, Neal W. Currier, Thomas M. Yonushonis,

    “Intra-Channel Evolution of Carbon Monoxide and Its Implication on the Regeneration of a Monolithic Pt/K/Al2O3 NOX Storage/Reduction Catalyst,” Catalysis Today114, 102

    , 2006
  43. Shadab Mulla, Nan Chen, Lasitha Cumaranatunge, W. Nicholas Delgass, William S. Epling and Fabio H. Ribeiro,

    “Reaction of NO and O2 to NO2 on Pt: Kinetics and Catalyst Deactivation,” Journal of Catalysis241, 389

    , 2006
  44. William S. Epling, Aleksey Yezerets and Neal W. Currier,

    “The Effect of Exothermic Reactions During Regeneration of the NOX Trapping Efficiency of a NOX Storage Reduction Catalyst,” Catalysis Letters, 110, 143

    , 2006
  45. “NO2 inhibits the catalytic reaction of NO and O2 over Pt,” Catalysis Letters100, 267

    , 2005
  46. Aleksey Yezerets, Neal W. Currier, Do Heui Kim, Heather A. Eadler, William S. Epling and Charles H. F. Peden,

    “Differential Kinetic Analysis of Diesel Particulate Matter (Soot) Oxidation by Oxygen Using a Step-Response Technique,” Applied Catalysis B: Environmental61, 134

    , 2005
  47. Praveen Cheekatamarla, William S. Epling, Alan M. Lane,

    “Selective low-temperature removal of carbon monoxide from hydrogen-rich fuels over Cu-Ce-Al catalysts,” Journal of Power Sources147, 178

    , 2005
  48. Todd J. Toops, D. Barton Smith, William S. Epling, James E. Parks, William P. Partridge,

    “Quantified NOx adsorption on Pt/K/gamma-Al2O3 and the effects of CO2 and H2O,”Applied Catalysis B: Environmental58, 255

    , 2005
  49. William S. Epling, James E. Parks, Neal W. Currier and Aleksey Yezerets,

    “Further Evidence for Multiple NOx Sorption Sites or Mechanisms on NOx Storage/Reduction Catalysts,”Catalysis Today96, 21

    , 2004
  50. William S. Epling, Larry E. Campbell, Aleksey Yezerets, Neal W. Currier, and James E. Parks II,

    “Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts,” Catalysis Reviews46, 163

    , 2004
  51. Michael A. Henderson, William S. Epling, Charles H.F. Peden and Craig L Perkins,

    “Insights into Photoexcited Electron Scavenging Processes on TiO2 Obtained from Studies of the Reaction of O2 with OH Groups Adsorbed at Electronic Defects on TiO2 (110)”, Journal of Physical Chemistry B107, 534

    , 2003
  52. William S. Epling, Greg Campbell and James E. Parks,

    “The Effects of CO2 and H2O on the NOx Destruction Performance of a Model NOx Storage/Reduction Catalyst,” Catalysis Letters90, 45

    , 2003
  53. William S. Epling, Praveen Cheekatamarla and Alan M. Lane,

    “Reaction and Surface Characterization Studies of Co- and Co/Pt-Based Catalysts for the Selective Oxidation of CO in H2-Containing Streams,” Chemical Engineering Journal93, 61

    , 2003