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The material presented here is based upon work supported by the National Science Foundation under Award No. EEC-0813570. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, nor of Iowa State University. Results & Discussion Base catalyzed glucose/fructose isomerization Thrust 3: Chemical Catalyst Design Sarah Curry, Participant in the 2014 CBiRC RET; Jack Carraher; Chelsea Fleitman; Alex Liu; Jean-Philippe Tessonnier Iowa State University Project Rationale & Goals What: Production of fructose from glucose Why: Fructose is a feedstock chemical for the production of biomass-derived commodity chemicals Current Methods: In Industry, enzymes are used to catalyze isomerization of glucose to fructose using High Fructose Corn Syrup process • Expensive catalyst, slow process, sensitive to conditions Solid acid catalyzed isomerization (Moliner, 2010) utilizing tin-beta zeolite • Expensive catalyst, difficult to synthesize Objective: Develop inexpensive, environmentally friendly, and efficient method for conversion of glucose to fructose Utilizing triethylamine in base catalyzed reaction Conclusions Identified mechanism scheme for glucose isomerization • Determined optimum conditions for fructose formation • Identified fructose decomposition pathways Obtained 33% fructose • (Enzyme: 41% yield) • ~ 50 times faster than enzyme method • More cost effective Future: Develop heterogeneous catalyst that meets the optimization criteria for isomerization Acknowledgements I would like to thank the Tessonnier Research Group for guidance and mentoring, as well as , Adah Leshem, Stacy Renfro, Diana Loutsch, Maureen Griffin, Craig Walter, and Eric Hall for organizing the 2014 CBiRC RET Program. 0 20 40 60 80 100 9 10 11 12 Glucose Consumption Fructose Selectivity Fructose Yield Progress of Reaction Expressed as % Initial pH Extent of reaction as a function of pH Materials & Methods Hot Oil Bath Reaction • Prepare aqueous solution of glucose and control the pH by adding a base • Purge the samples under argon gas to remove any carbon dioxide • Heat samples of the solution in an oil bath for set time intervals • Quench reaction with ice bath, then proceed to the dilution phase for analysis Running reaction in hot oil bath Post-reaction vials; removed at 2, 3, 4, 5, 7, 10, 12, and 15 minutes. Sample Analysis • Dilute samples and analyze with UPLC Ultra Performance Liquid Chromatography unit UPLC chromatogram showing fructose and glucose peaks. Fructose Glucose 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50 1.55 0 0.1 0.2 0.3 0.4 0.5 0 200 400 600 800 1000 1200 [Glucose] / M Time / sec Concentration of Glucose as a Function of Time (100 o C) Maximum yields of fructose are obtained in the pH range of 10 - 12 Consumes more glucose at higher pH Production of fructose complicated by simultaneous decomposition Activation parameters for fructose formation and decay: Reaction DH ‡ / kJ mol -1 DS ‡ / J mol -1 K -1 DG ‡ / kJ mol -1 @ 100 o C Formation 84 ± 7 -70 ± 20 110 Unimolecular RXN 153 115 110 Bimolecular RXN 15 -250 109 Kinetic maximum yield of fructose from glucose DG ‡ formation / (ΣDG ‡ ) × 100 110 / (110 + 110 + 109) × 100 = 33 % ‡ ‡ ‡ ‡ ‡ ‡ 0 2 10 -3 4 10 -3 6 10 -3 8 10 -3 0 0.2 0.4 0.6 0.8 Fructose decay rate constant vs [Frucotose], 100 o C, pH 11 k obs / s -1 [Fructose] / M Unimolecular Reaction Two pathways identified by which fructose is consumed * Moliner, M. et al. Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water. PNAS. 2010, 107, 6164-6168. Time in minutes 0 0.05 0.1 0.15 0.2 0 200 400 600 800 1000 1200 Concentration of Fructose as a Function of Time (100 o C) pH 9.5 pH 10.2 pH 10.5 pH 10.7 pH 10.9 pH 11.0 pH 11.1 pH 11.3 pH 11.5 [Fructose] / M Time / sec
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