Brent H. Shanks
Professor
2119 Sweeney Hall
Iowa State University
Ames, IA 50011-2230
Phone (515)294-1895
Fax (515)294-2689
bshanks
iastate.edu
Education
B.S., ChE, Iowa State University, 1983
M.S., ChE, California Institute of Technology, 1985
Ph.D., ChE, California Institute of Technology, 1988
Professional Experience
Research Engineer, Shell Chemical Co., 1988-1997.
Department Manager, Shell Chemical Co., 1997-1999.
Honors and Awards
ISU Engineering Student Council Leadership Award, 2004
Teaching Award, AIChE Student Chapter, 2001, 2002, 2003, 2005, 2006
Shell Faculty Fellow, 2000-2002
VEISHEA Engineering Faculty of the Year, 2000
Teaching/Office Hours Schedule
Research Interests
Heterogeneous catalysis
Catalytic conversion of biorenewable feedstocks
Mesoporous metal oxides
Novel coupling of reactor/catalyst combinations
Professional Memberships
American Chemical Society
American Institute of Chemical Engineers
North American Catalysis Society
Omega Chi Epsilon
Tau Beta Pi
Research Projects
Catalytic Conversion of Biorenewable Feedstocks
Biorenewable feedstocks represent a potentially attractive source of organic chemicals. The processing of these feedstocks will require the development of new chemical processes as well as biological processes for economical manufacture of chemicals and/or fuels. However, biorenewable feedstock conversion with heterogeneous catalysts provides new challenges in inorganic catalyst research and development relative to the voluminous historical work with petrochemical feedstocks. These unique challenges include the need to convert selectively, highly functionalized molecules and to develop catalytic liquid-solid interfaces in which the liquid phase is commonly aqueous. Examples of ongoing projects in our group include:
a) esterification of fatty acids to alkyl acids -- We are synthesizing and testing nanostructured organic-inorganic hybrid catalysts for use in esterification reactions. In these catalysts, organic acid catalytic sites are covalently bound to the metal oxide. We are also examining the impact of modulating the hydrophobicity/hydrophilicity within the catalyst pores.
b) hydrogenolysis of sugar alcohols to polyols -- We are examining the mechanism involved in sugar alcohol hydrogenolysis over supported metal catalysts to better understand the potential for selectively converting a specific hydroxyl group within a polyhydroxylated molecule.
c) oligosaccharide hydrolysis to monosaccharides -- We are synthesizing organic-inorganic hybrid catalysts with reactions domains tailored at the molecular level to hydrolyze oligosaccharides without concomitant degradation of the resulting monosaccharides.
Mesoporous Metal Oxides as Nanostructured Catalytic Hosts
Nanostructured metal oxides hold promise for applications as unique catalytic hosts in which catalytic reactions requiring directed conformational synthesis can be achieved. We are interested in the controlled synthesis of mesoporous aluminas, silicas and alumino- silcates to produce nanostructured materials with specific surface chemistry and particle morphology. The surface chemistry properties to be manipulated during material synthesis include the population and type of catalytic sites. To control the interplay of diffusional effects with reactivity, the ability to manipulate pore size as well as particle morphology is important. We are examining synthesis strategies that can provide particle morphologies with reduced diffusional limitations. Also, we are interested in the incorporation of catalytic functionality into our nanostructured supports through co-condensation and grafting.
Potassium-Promoted Iron Oxide Catalysts
Potassium-promoted iron oxide catalysts are commonly used in dehydrogenation reactions with the largest commercial application being the dehydrogenation of ethylbenzene (EB) to styrene (ST). The ST reaction is performed in excess steam with a dilution of 8-10 moles of steam/mole of EB. The steam is required to keep the catalyst active. The loss in catalyst activity has historically been ascribed to formation of "coke." The potassium was added to the iron oxide catalyst to catalyze the "coke" gasification reaction with steam. Recent work has shown that the interaction of potassium with the iron oxide matrix is more complex than merely serving to catalyze "coke" gasification. It appears that the active site for the dehydrogenation reaction is a potassium ferrite, KFeO2, with iron in the +3 oxidation state despite the fact that the bulk of the iron is in the magnetite form under reaction conditions. As the steam to hydrocarbon ratio is decreased, which is directionally towards a more reducing atmosphere, there is evidence suggesting that the potassium ferrite phase is reduced. Therefore, the steam may be playing the important role of maintaining the proper oxidation state of the active site. To guide the development of catalysts that can operate at lower steam to hydrocarbon ratios, we are trying to determine what is the most important mechanism for loss of activity; the blocking of active sites with "coke" or the loss of active sites through reduction.
Research Group
Selected Publications
Mbaraka, I. K. and Shanks, B. H., “Design of Multifunctionalized Mesoporous Silicas for Fatty Acid Esterification,” J. Amer. Oil. Chem. Soc., 83, 79-91 (2006).
Mbaraka, I. K., McGuire, K. J. and Shanks, B. H., “Acidic Mesoporous Silica for the Catalytic Conversion of Fatty Acids in Beef Tallow,” Ind. Eng. Chem. Res., 45, 3022-3028 (2006).
Jackson, M. A., Mbaraka, I. K. and Shanks, B. H., “Esterification of Oleic Acid in Supercritical Carbon Dioxide Catalyzed by Functionalized Mesoporous Silica and an Immobilized Lipase,” Appl. Catal. A: Gen., 310, 48-53 (2006).
Ndlela, S. C. and Shanks, B. H., “Reduction Behavior of Potassium-Promoted Iron Oxide under Mixed Steam/Hydrogen Atmospheres,” Ind. Eng. Chem. Res., 45, 7427-7434 (2006).
Mbaraka, I. K. and Shanks, B. H., “Acid Strength Variation Due to Spatial Location of Organosulfonic Acid Groups in Mesoporous Silica,” J. Catal., 244, 78-85 (2006).
Mbaraka, I. K. and Shanks, B. H., “Design of Multifunctionalized Mesoporous Silicas for Fatty Acid Esterification,” J. Catal., 229, 365-373 (2005).
Bootsma, J. A. and Shanks, B. H., “Hydrolysis Characteristics of the Tissue Fractions Resulting from Mechanical Separation of Corn Stover,” Appl. Biochem. Biotechnol., 125, 27-39 (2005).
Satrio, J. A., Shanks, B. H., and Wheelock, T. D., “Development of a Novel Combined Catalyst and Sorbent for Hydrocarbon Reforming,” Ind. Eng. Chem. Res., 44, 3901-3911 (2005).
Lahr, D. G. and Shanks, B. H., “Effect of Sulfur and Temperature on Ruthenium Catalyzed Glycerol Hydrogenolysis to Glycols,” J. Catal., 232, 386-394 (2005).
Deng, W. and Shanks, B. H., “Synthesis of Hierarchically Structured Aluminas under Controlled Hydrodynamic Conditions,” Chem. Mater., 17, 3092-3100 (2005).
