Brent H Shanks
- Mike and Jean Steffenson Professor and Director of NSF Engineering Research Center for Biorenewable Chemicals (CBiRC)
Main Office1140L Biorenewables Research Laboratory
Ames, IA 50011-2230
Ph.D. Chemical Engineering, California Institute of Technology, 1988
M.S. Chemical Engineering, California Institute of Technology, 1985
B.S. Chemical Engineering, Iowa State University, 1983
BRENT SHANKS' RESEARCH PAGE
Catalytic conversion of biorenewable feedstocks
Mesoporous metal oxides
Novel coupling of reactor/catalyst combinations
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 carboxylic acids to alkyl esters -- 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) C-O bond hydrogenolysis of biorenewable molecules -- We are examining the mechanism involved in C-O bond hydrogenolysis over supported metal catalysts to better understand the potential for selectively converting a specific hydroxyl group within a polyhydroxylated molecule.
c) selective dehydration of carbohydrates -- We are exploring novel chemical catalyst systems that can selectively dehydrate carbohydrates or their derivatives to valuable products such as 5-hydroxymethylfurfural and diols.
d) ketonization of carboxylic acids – C-C bond formation can be accomplished via ketonization of carboxylic acids. We are studying the inorganic catalyst properties needed for high activity in this reaction.
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.
Honors and Awards
Superior Engineering Teacher Award, 2007
ISU Engineering Student Council Leadership Award, 2004
Teaching Award, AIChE Student Chapter, 2001, 2002, 2003, 2005, 2006, 2008
Shell Faculty Fellow, 2000-2002
VEISHEA Engineering Faculty of the Year, 2000
1997-1999; Department Manager, Shell Chemical Co.
1988-1997; Research Engineer, Shell Chemical Co.
American Chemical Society
American Institute of Chemical Engineers
North American Catalysis Society
Omega Chi Epsilon
Tau Beta Pi
- Miao, S., and Shanks, B. H. "On the Mechanism of Acetic Acid Esterification over Sulfonic Acid Functionalized Mesoporous Silica," J. Catal ., 279 , 136-143 (2011).
- Cinlar, B., and Shanks, B. H. "Characterization of the Acidic Sites in Organic Acid Functionalized Mesoporous Silica in the Aqueous Phase," Appl. Catal. A: Gen ., 396 , 76-84 (2011). http://dx.doi.org/10.1016/j.apcata.2011.01.044
- Shanks, B. H. "Conversion of Biorenewable Feedstocks: New Challenges in Heterogeneous Catalysis," Ind. Eng. Chem. Res ., 49 , 10212-10217 (2010). http://dx.doi.org/10.1021/ie100487r
- Dapsens, P. Y., Hakim, S., Su, B.-L., and Shanks, B. H. "Direct Observation of Macropore Self-Formation in Hierarchically Structured Metal Oxides," Chem. Comm., 46 , 8980-8982 (2010). http://dx.doi.org/10.1039/c0cc02684k
- Patwardhan, P. R., Satrio, J. A., Brown, R. C., and Shanks, B. H. "Influence of Inorganic Salts and Switchgrass Ash on Primary Pyrolysis Products of Cellulose," Bioresource Technol., 101 , 4646-4655 (2010). http://dx.doi.org/10.1016/j.biortech.2010.01.112
- Tang, Y., Miao, S., Shanks, B. H., and Zheng, X. "Bifunctional Mesoporous Organic/Inorganic Hybrid Silica for Combined One-step Hydrogenation Esterification," Appl. Catal A: Gen ., 375 , 310-317 (2010). http://dx.doi.org/10.1016/j.apcata.2010.01.015
- Hakim, S., and Shanks, B. H. "Manipulation of Mesoporous Structure and Crystallinity in Spontaneously Self-Assembled Hierarchical Metal Oxides," Microporous Mesoporous Mater., 135 , 105-115 (2010). http://dx.doi.org/10.1016/j.micromeso.2010.06.017
- Snell, R. W., Combs, E., and Shanks, B. H. "Aldol Condensations using Bio-oil Model Compounds: The Role of Acid-Base Bi-functionality," Catal. Today, 53, 1248-1253 (2010).
- Albrecht, K. O., Satrio, J. A., Shanks, B. H., and Wheelock, T. D. "The Application of a Combined Catalyst and Sorbent for Steam Reforming of Methane," Ind. Eng. Chem. Res ., 49 , 4091-4098 (2010).
- Li, Z., and Shanks, B. H. "Stability and Phase Transformations of Potassium Promoted Iron Oxide in Various Gas Phase Environments," Appl. Catal. A: Gen., 354 , 50-56 (2009). http://dx.doi.org/10.1016/j.apcata.2008.11.007
- Zhu, H., Shanks, B. H., and Heindel, T. J. "Effect of electrolytes on CO-water mass transfer," Ind. Eng. Chem. Res., 48 , 3206-3210 (2009). http://dx.doi.org/10.1021/ie8012924
- Hruby, S. L., and Shanks, B. H. "Acid-Base Cooperativity in Condensation Reactions with Functionalized Mesoporous Silica Catalysts," J. Catal., 263, 181-188 (2009). http://dx.doi.org/10.1016/j.jcat.2009.02.011
- Miao, S., and Shanks, B. H. "Esterification of Biomass Pyrolysis Model Acids over Sulfonic Acid-Functionalized Mesoporous Silicas," Appl. Catal. A: Gen., 359, 113-120 (2009). http://dx.doi.org/10.1016/j.apcata.2009.02.029