Biofuels Production programs
Development Of Novel Catalysts
Catalysts must be developed that facilitate selective conversion of all biomass components including carbohydrates (cellulose and starch), hemicellulose (and associated C5 platform carbohydrates), lignin, proteins, and oils to useful products. The focus of this program is to identify and optimize new catalytic reactions that allow for selective transformation of renewable biomass-derived cellulose and lignin.
The majority of our efforts have focused on the development of heterogeneous catalysts for the condensation of acetone, 1-butanol, and ethanol (ABE) mixture produced by Clostridium acetobutylicum to higher ketones, alcohols and/or hydrocarbons. Our investigation has identified at least 5 heterogeneous catalysts that can upgrade ABE mixture to diesel range products (C11+: C11, C13, C15, and C19) in excellent yield and with ~95% selectivity. Chemical kinetic studies employing the best of these catalysts were conducted in batch and flow reactors. In conjunction with our efforts to increase yields for the diesel or lubricant-range compounds in the ABE process, we have also developed and are investigating catalysts for the Guerbet reaction of ethanol and longer-chain alcohols. As an extension of this concept, we have explored and developed catalysts for the condensation of biomass-derived furanic aldehydes and bioalcohols. In collaboration with the Bell lab, we accomplished the hydrodeoxygenation of the resulting furanic ketones to afford hydrocarbons (C7-C20) that can be used as blendstocks for gasoline, jet and diesel fuels.
derived from fermentation to higher ketones, alcohols and/or hydrocarbons. The majority of our efforts have focused on the development of heterogeneous catalysts for the condensation of acetone, 1-butanol, and ethanol (ABE) mixture produced by Clostridium acetobutylicum in a 2.3: 3.7: 1 molar ratio (3: 6: 1 mass ratio). Our investigation of different transition metals (Ir, Ru, Rh, Pt, Pd, Cu and Ni and their combinations) impregnated on a variety of bifunctional heterogeneous supports (alkali and alkaline earth oxides, nonmetal oxides, transition metal oxides, rare metal oxide, cation-exchanged zeolites and their combinations) led to the development of at least five different heterogeneous catalysts that can upgrade ABE mixture to diesel range products (C11+: C11, C13, C15, and C19) in excellent yield and with ≥95 percent selectivity. These catalysts include, 3:1PdCu/hydrotalcite, 3:1 PdCu/CaOMgO, CuZn/hydrotalcite, HiFuel/Pd, C/CeO2, HiFuel/PdC/La2O3. We have completed the construction of two flow reactors: an atmospheric pressure gas phase reactor and a high-pressure reactor. The atmospheric pressure reactor has been used for the detailed kinetic study of aldol condensation reactions, whereas the high-pressure reactor has been used to simulate industrially relevant reaction conditions, such as liquid flow and high conversions, with a view to assessing catalyst performance in such environments. Kinetic studies have shown that the rate-determining step for aldol condensation over hydrotalcite-type materials is the C-C bond formation. Under ABE condensation conditions over hydrotalcite-supported metals, the most abundant surface intermediate on the hydrotalcite are alcohols, whereas the reactive species are butyraldehyde/acetaldehyde and the reactant acetone. As a result, the aldol condensation rate is proportional to the total pressure of the reactants. In conjunction with our efforts to increase yields for the diesel-range compounds in the ABE process, we also investigated the Guerbet reaction of alcohols. To this end, we utilized palladium and copper impregnated on titanium and zirconium oxides.
We have been developing catalysts for the conversion of products derived from fermentation to higher ketones, alcohols and/or hydrocarbons. More specifically, our efforts have focused on the development of catalysts for combining the acetone, 1-butanol, and ethanol (ABE) mixture produced by Clostridium acetobutylicum. Our investigation of different transition metal catalysts revealed that palladium was superior to the other metals. For large-scale production of renewable fuels, the reaction would ideally be tolerant of some amount of water contamination carried over from the fermentation process. Unfortunately, although wet organic solvents could be used for the alkylation reaction, no reaction was observed in the presence of significant amounts of water.
In order to overcome the sensitivity of the catalysts to water, we collaborated with the Blanch/Clark team to identify a highly selective, water-immiscible extractant to remove acetone, 1-butanol, and ethanol in situ. Glyceryl tributyrate was identified as a water-immiscible solvent capable of efficiently recovering both acetone and 1-butanol; however, ethanol preferentially remained in the aqueous phase. Using the mixture of acetone and alcohols obtained from this extractive fermentation, high yields of ketone products was obtained. One important aspect of any catalytic process is the lifetime of the catalyst. In some cases we were able to achieve catalytic turnover numbers >3000 and conducted preliminary studies using a flow reactor and found that catalytic activity was maintained for 25 hours under flow reaction conditions. While these results are promising, a major goal of the next funding period will be identification of improved catalyst systems.
The Toste team designed a palladium-based catalyst system that effectively converted acetone, butanol and ethanol to higher order compounds with yields over 90 percent. A second project aims to find catalysts that can effectively depolymerize lignins recovered from pretreatment. After experimenting with different solvents and metals, they have a vanadium-based catalyst system that does the trick.
In 2010, Toste’s group reported a vanadium(V)-based catalyst system for the non-oxidative cleavage of carbon-oxygen bonds and applied it to C-O bond cleavage in lignin model systems. Optimization of the catalyst ligand structure allowed for selective C-O bond cleavage versus simple alcohol oxidation. They have subsequently shown that the same catalyst system can be applied to Miscanthus giganteus-derived lignin.
Published in 2014
Engineering Clostridium acetobutylicum for Production of Kerosene and Diesel Blendstock Precursors, S. Bormann, Z. C. Baer, S. Sreekumar, J. M. Kuchenreuther, F. D. Toste, H. W. Blanch, D. G. Clark, Metabolic Engineering, V. 55, pp. 124-130, July 28, 2014.
Chemocatalytic Upgrading of Tailored Fermentation Products Toward Biodiesel, S. Sreekumar, Z. C. Baer, E. Gross, S Padmanaban, K. Goulas, G. Gunbas, S. Alayoglu, H. Blanch, D. S. Clark, and F. D. Toste, ChemSusChem, V. 7 (9), pp. 2445–2448, July 15, 2014.
Published in 2013
Studies on the Vanadium-Catalyzed Nonoxidative Depolymerization of Miscanthus giganteus-Derived Lignin, J. M. W. Chan, S. Bauer, H. Sorek, S. Sreekumar, K. Wang, F. D. Toste, ACS Catalysis, 3(6), pp. 1369-1377, doi: 10.1021/cs400333q, May 21, 2013.
Expanding the Scope of Biomass-Derived Chemicals through Tandem Reactions Based on Oxorhenium-Catalyzed Deoxydehydration, M. Shiramizu, F. D. Toste, Angewandte Chemie, 52, pp. 12905-12909, doi: 10.1002/anie.201307564, November 14, 2013.
Published in 2012
Integration of Chemical Catalysis with Extractive Fermentation to Produce Fuels, Pazhamalai Anbarasan, Zachary C. Baer, Sanil Sreekumar, Elad Gross, Joseph B. Binder, Harvey W. Blanch, Douglas S. Clark, and F. Dean Toste, Nature, doi:10.1038/nature11594, November 8, 2012.
Deoxygenation of Biomass-Derived Feedstocks: Oxorhenium-Catalyzed Deooxygenation of Sugars and Sugar Alcohols, Mika Shiramizu, F. Dean Toste, Angewandte Chemie International Edition, Doi: 10.1002/anie.201203877, July 4, 2012.
Published in 2011
Structural Transformation of Miscanthus giganteus Lignin Fractionated Under Mild Formosolov, Basic Organoslov and Cellulolytic Enzyme Conditions, Kun Wang, Run-Cang Sun, Stefan Bauer, Journal of Agricultural and Food Chemistry, doi: 10.1021/jf2037399, November 30, 2011.
On the Diels-Alder Approach to Solely Biomass-Derived Polyethylene Terephthalate (PET): Conversion of 2,5-Dimenthylfuran and Acrolein into p-Xylene, Mika Shiramizu, Dean Toste, Chemistry -- A European Journal, doi: 10.1002/chem.201101580, September 16, 2011.
Published in 2010
Non-Oxidative Vanadium-Catalyzed C-O Bond Cleavage: Application to Degradation of Lignin Model Compounds, Sunghee Son and F. Dean Toste, Angewandte Chemie, 49(22): pp. 3791-3794, May 2010.