Abstracts 2006

Charu L. Shukla, Jason P. Hallett, Alexander V. Popov , Rigoberto Hernandez*, Charles L. Liotta, and Charles A. Eckert, “Molecular Dynamics Simulation of the Cybotactic Region in Gas-Expanded Methanol-Carbon Dioxide and Acetone-Carbon Dioxide Mixtures,” J Phys Chem B, 110, 24101-24111, 2006.

Local solvation and transport effects in gas-expanded liquids (GXLs) are reported based on molecular simulation. GXLs were found to exhibit local density enhancements similar to those seen in supercritical fluids, although less dramatic. This approach was used as an alternative to a multiphase atomistic model for these mixtures by utlilizing experimental results to describe the necessary fixed conditions for a locally (quasi-) stable molecular dynamics model of the (single) GXL phase. The local anisotropic pair correlation function, orientational correlation functions, and diffusion rates are reported for two systems: CO 2 -expanded methanol and CO 2 -expanded acetone at 298 K and pressures up to 6 MPa.

Yingxin Liu, Philip G. Jessop, Michael Cunningham, Charles A. Eckert, Charles L. Liotta, “Switchable Surfactants,” Science, 313, 958-960, 2006.

Many industrial applications that rely on emulsions would benefit from an efficient, rapid method of breaking these emulsions at a specific desired stage. We report that long-chain alkyl amidine compounds can be reversibly transformed into charged surfactants by exposure to an atmosphere of carbon dioxide, thereby stabilizing water/alkane emulsions or, for the purpose of microsuspension polymerization, styrene-in-water emulsions. Bubbling nitrogen, argon, or air through the amidinium bicarbonate solutions at 65°C reverses the reaction, releasing carbon dioxide and breaking the emulsion. We also find that the neutral amidines function as switchable demulsifiers of an aqueous crude oil emulsion, enhancing their practical potential.

Laura C. Draucker, Malina Janakat, Michael J. Lazzaroni, David Bush , and Charles A. Eckert and Timothy C. Frank and James D. Olson, “Experimental Determination and Model Prediction of Solid Solubility of Multi-functional Compounds in Pure and Mixed Non-electrolyte Solvents, I&EC Research, 46, 2198-2204, 2007.

We seek an improved methodology for the design of solvents and solvent mixtures for separations, especially purification of solids by crystallization. This paper reports new data for the solubility of four multifunctional solids: 3-nitrophthalimide, 5-fluoroisatin, 2-amino-5-nitrobenzophenone, and benzimidazole. The heat of fusion for each solid was measured along with the solubility in several pure and mixed solvents at 283, 298, and 313 K. These data were used to determine new parameters for the MOSCED model for these solids, and those parameters were then used to predict the solid solubility in mixed solvents. The ability to use thermodynamic models to predict solubility of complex solutes provides a new paradigm for the selection of both pure and mixed solvents.

James M. Broering, Elizabeth M. Hill, Jason P. Hallett, Charles L. Liotta, Charles A. Eckert, and Andreas S. Bommarius, “Biocatalytic Reaction And Recycle Using Organic Aqueous Tunable Solvents (OATS),” Angewandte Chemie, 45, 4670-4673, 2006.


Arthur J. Ragauskas, Mate Nagy, Dong Ho Kim, Charles A. Eckert, Jason P. Hallett, Charles L. Liotta, "From Trees to Fuels: Integrating Biofuels and Pulp Production," Industrial Biotechnology, 2, No. 1, 55-65, 2006

Bioethanol currently contributes ~2% to the total US transportation fuels mix, and another ~0.01% is based on biodiesel. To make a substantial contribution to the United States ' energy portfolio, biofuels production needs to grow substantially over the next decade by a factor of 10 or more. Although the contribution of agro-energy crops and agriculture waste for biofuels production is being intensively developed, the potential of the forest products industry to contribute to this effort has been generally underestimated. The forest products industry is one of a few nationally based industries that have the necessary skill set and infrastructure available to process sufficient biomass for the rapid short-term development and commercialization of biofuel and biochemical technologies. On an annual basis, the US pulp and paper industry collects and processes approximately 108 million tons of wood for the production of pulp and paper in a sustainable manner. Wood extractives from pulping provide approximately 700 million liters of turpentine and tall oil annually that could be employed for biodiesel applications. Wood chip preextraction technologies could make available to the biofuels industry about 14 million tons of hemicelluloses annually while at the same time enhancing the production of kraft pulps. This review highlights the chemical resources available from wood and summarizes which biomaterials are needed for pulp production and which could be utilized for biofuels, with a special emphasis on select hemicelluloses that are currently degraded during kraft pulping that could be utilized for bioethanol production. The review further describes the operational considerations by which the biofuels and pulp manufacturing industries could synergistically operate together.

Jason P. Hallett, Christopher L. Kitchens, Rigoberto Hernandez, Charles L. Liotta, and Charles A. Eckert, "Probing the Cybotactic Region in Gas-Expanded Liquids (GXLs),” Accounts of Chemical Research, 39, 531-538, 2006.

Gas-expanded liquids (GXLs) are a new and benign class of liquid solvents, which may offer many advantages for separations, reactions, and advanced materials. GXLs are intermediate in properties between normal liquids and supercritical fluids, both in solvating power and in transport properties. Other advantages include benign nature, low operating pressures, and highly tunable properties by simple pressure variations. The chemical community has only just begun to exploit the advantages of these GXLs for industrial applications. This Account focuses on the synergism of experimental techniques with theoretical modeling resulting in a powerful combination for exploring chemical structure and transport in the cybotactic region of GXLs (at the nanometer lengthscale).

Weikel, R.R., Hallett, J.P., Liotta, C.L., and Eckert , C.A. , Self-neutralizing in situ acid catalysts from CO2. Topics in Catalysis, 2006. 37 (2-4): p. 75-80.

Acids are the most common industrial catalysts but have the disadvantage of requiring post-reaction neutralization and salt disposal. We show the catalytic use of self-neutralizing acids. Carbon dioxide interacts with water and amines to form carbonic acid and carbamates. A similar interaction occurs with alcohols to form alkylcarbonic acids. All three solvent systems provide in situ acid formation for catalysis which can be easily neutralized by removal of carbon dioxide. However, water has poor organic solubility and amines form salts so only alkylcarbonic acids combine good organic solubility with simple neutralization via depressurization. The use of in situ acid also completely eliminates the solid salt wastes associated with many acid processes. To elucidate how to implement these systems in place of a standard acid system we compare the reaction rates of several alkylcarbonic acids with diazodiphenylmethane (DDM). We report also the effect of CO2 pressure on reaction rate of DDM as well as measure the dielectric constant of these systems. Finally, a Hammett plot is used to identify the dominant step in alkylcarbonic acid catalysis.

Draucker, L.C., Hallett, J.P., Bush, D., and Eckert , C.A. , Vapor-liquid-liquid equilibria of perfluorohexane plus CO2 + methanol, plus toluene, and plus acetone at 313 K. Fluid Phase Equilibria, 2006. 241 (1-2): p. 20-24.

Homogeneous catalysts offer many advantages over heterogeneous catalysts, such as higher activities and selectivities. However, recovery of homogeneous catalysts is often complicated by difficulties in separating these complexes from the reaction products. The use of gaseous carbon dioxide (CO2) as miscibility switch for organic and fluorous phases has been proposed to overcome this limitation. By using CO2 as a cosolvent, polar organic reactants can be homogenized with catalysts immobilized in a fluorous phase without using elevated temperatures. The phase behavior underlying this concept is investigated. High-pressure phase equilibria for the systems containing carbon dioxide, an organic (methanol, toluene, or acetone), and perfluoro-n-hexane were measured using a variable-volume view cell, by a method capable of rapid and facile measurement of compositions and density in both phases with no sampling or calibration. (c) 2006 Elsevier B.V. All rights reserved.

Lazzaroni, M.J., Bush, D., Eckert , C.A. , and Glaser, R., High-pressure vapor-liquid equilibria of argon plus carbon dioxide+2-propanol. Journal of Supercritical Fluids, 2006. 37 (2): p. 135-141.

The high-pressure phase equilibria for a heterogeneously catalyzed oxidation reaction in a carbon dioxide-expanded liquid were investigated. For safety argon was used as a substitute for oxygen in this Study. A Visual synthetic technique was used to determine the vapor-liquid equilibria data for the systems carbon dioxide + argon + 2-propanol and carbon dioxide + argon + 2-propanol + acetone + water at 313 K and pressures from 6.9 to 15.0 M Pa. (c) 2005 Elsevier B.V. All rights reserved.

Ragauskas, A.J., Williams, C.K., Davison, B.H., Britovsek, G., Cairney, J., Eckert, C.A., Frederick, W.J., Hallett, J.P., Leak, D.J., Liotta, C.L., Mielenz, J.R., Murphy, R., Templer, R., and Tschaplinski, T., The path forward for biofuels and biomaterials. Science, 2006. 311 (5760): p. 484-489.

Biomass represents an abundant carbon-neutral renewable resource for the production of bioenergy and biomaterials, and its enhanced use would address several societal needs. Advances in genetics, biotechnology, process chemistry, and engineering are leading to a new manufacturing concept for converting renewable biomass to valuable fuels and products, generally referred to as the biorefinery. The integration of agroenergy crops and biorefinery manufacturing technologies offers the potential for the development of sustainable biopower and biomaterials that will lead to a new manufacturing paradigm.

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