Supported Catalysts: Does Surface Roughness Matter? A Case Study with VOx-SBA-15

2013 Spring Symposium

Michael A. Smith
Department of Chemical Engineering
Villanova University
Villanova, PA 19085

Abstract – SBA-15 is a template-synthesized mesoporous silicate that has found extensive use as a model support for studies of supported catalysis.[1, 2] Thorough structural analyses clearly describe the dual micropore-mesopore structure with a broad distribution of micropore sizes.[3] Silicas such as SBA-15 have long been considered a relatively inert support, quite in contrast to other oxides such as titania or ceria. We find the effect of surface roughness of SBA-15 has an underappreciated effect on catalyst performance. Specifically, samples of VOx-SBA-15 where the support surface roughness was systematically varied were charaterized using UV-Vis and Raman spectroscopy, then tested in the catalytic partial oxidation of methanol to formaldehyde, and propane to propene. Results show that supports with smoother surfaces permit the development of more polymeric vanadia species at the same surface density loading. Such smoother-surface catalysts result in a lower selectivity of methanol to formadehyde, yet conversely show a higher selectivity of propane to propene. This result is significant with respect to our understanding the role of vanadium in in partial oxidation catalysts, and illustrates the importance of considering differences in support surface morphology in analyzing catalytic behavior.
[1] V. Dufaud, M. E. Davis, J. Am. Chem. Soc. 125 (2003) 9403-9413.
[2] R. K. Zeidan, S. J. Hwang, M. E. Davis, Angew. Chem.-Int. Edit. 45 (2006) 6332-6335.
[3] M. Kruk, M. Jaroniec, R. Ryoo, J. M. Kim, Chem. Mat. 11 (1999) 2568-2572.

Michael A. Smith

Michael A. Smith

Biography – Professor Michael A. Smith is currently an Assistant Professor in the Department of Chemical Engineering at Villanova University. He received his BS in Chemical Engineering from Lafayette College in 1980, then worked in a variety of assignments with the DuPont Company for 17 years. Dr. Smith returned to school to obtain a Masters at Villanova University, and obtained his PhD in Chemical Engineering from the University of Delaware in 2004 working with Prof Raul Lobo. Since he has work as a research scientist for an SBIR startup, and has been at Villanova since 2006, first as a Visiting Assistant Professor, then in a tenure track position since 2008. Dr Smith’s research interests include the synthesis and characterization of nanostructured materials made using colloidal self-assembly and sol-gel techniques, and heterogeneous catalysis with an emphasis on catalysis by metal oxides.