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857 results on '"Brennecke, Joan F."'

153. Hydrogen Stable Supported Ionic Liquid Membranes with Silver Carriers: Propylene and Propane Permeability and Solubility

Author

Sanchez, Constanza Miguel, Song, Tangqiumei, Brennecke, Joan F., and Freeman, Benny D.

Abstract

Pure gas permeabilities of propylene and propane through ionic liquids supported on porous alumina membranes were determined as a function of silver salt concentration from 0 to 1 M and feed pressure from 0.15 to 2.0 bar at 35 °C. Two ionic liquids were tested: 1-hexyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([hmmim][Tf2N]) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]). Propylene permeability increased with increasing silver content due to facilitated transport, but it decreased with increasing feed pressure. Permeability selectivity exhibited a nonlinear upward trend with silver concentration, indicating the formation of higher order silver-propylene complexes at higher silver concentrations. Solubility measurements were performed gravimetrically, which allowed for simultaneous determination of diffusion coefficients. Permeabilities were hindered by low diffusion coefficients due to increasing viscosity with increasing silver content. The most surprising result was the stability of the membrane after exposure to hydrogen gas, suggesting that the ionic liquids significantly slowed silver ion reduction.

Published
2020
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154. Uncommon Behavior of Tetra-alkyl-phosphonium 2-Cyano-pyrrolide Ionic Liquids + Glycerol and Triethanolamine Systems

Author

Nordness, Oscar, Morales-Collazo, Oscar, and Brennecke, Joan F.

Abstract

We use multiple characterization methods, including viscosity, ionic conductivity, density, and surface tension measurements, to investigate the unusual transport behavior of multiple tetra-alkyl-phosphonium-2-cyano-pyrrolide ([Pnnnm][2CNPyr]) ILs in glycerol and triethanolamine solvents. Specifically, the viscosity goes through a maximum for all of the IL/glycerol and IL/triethanolamine mixtures, which cannot be explained by traditional mixing rules. Through conductivity and surface tension characterization we find substantial evidence of microstructure formation driven by the amphiphilic structure of the tetra-alkyl-phosphonium ([Pnnnm]+) cation accounting for the uncommon viscosity behavior. While micelle formation is well-known for IL+ water systems, the observation of these microstructures in nonaqueous systems is a significant discovery. The slope of the ionic conductivity as a function of IL concentration changes substantially at the critical aggregate concentration cac, at which point the ILs undergo solvophobic self-assembly; this phenomenon is observed in all IL/solvent mixtures investigated. The cac is observed at more dilute IL concentrations for ILs containing longer alkyl chains. Furthermore, we observe lower cac values in glycerol compared to that of triethanolamine, owing to its higher dielectric constant and larger cohesion energy, as measured by the Gordon parameter.

Published
2020
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155. Abstraction of hydrogen from methanol by hydroxyl radical in subcritical and supercritical water

Author

Feng, Junbo, Aki, Sudhir N.V.K., Chateauneuf, John E., and Brennecke, Joan F.

Subjects
Radicals (Chemistry) -- Research, Methanol -- Research, Methanol -- Chemical properties, Hydrogen -- Research, Hydrogen -- Chemical properties, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

The measurements of the hydrogen abstraction from methanol by hydroxyl radical in water at temperatures from ambient to 390 degree C and at 250 bar is presented. The experimental rate constants for hydrogen abstraction from methanol to hydroxyl radical are significantly higher than the values used by a variety of researchers who have attempted to model oxidation of methanol in supercritical water using detailed chemical kinetics models.

Published
2003

158. Solubilities and thermodynamic properties of gases in the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate

Author

Anthony, Jennifer L., Maginn, Edward J., and Brennecke, Joan F.

Subjects
Solubility -- Research, Carbon monoxide -- Thermal properties, Nitrogen -- Thermal properties, Hydrogen -- Thermal properties, Argon -- Thermal properties, Methane -- Thermal properties, Ethanes -- Thermal properties, Ethylene -- Thermal properties, Carbon dioxide -- Thermal properties, Chemicals, plastics and rubber industries
Abstract

The solubility of nine different gases in 1-n-butyl-3-methylimidazolium hexafluorophosphate namely carbon dioxide, ethylene, ethane, methane, argon, oxygen, carbon monoxide, hydrogen and nitrogen are presented. The result suggests that the mass transfer of gases into ionic liquids is important for reactions involving in these gases and it is determined that ionic liquids show good potential for use as a gas-separation medium.

Published
2002

160. High-pressure phase behavior of ionic liquid/CO2 systems

Author

Blanchard, Lynnette A., Zhiyong Gu, and Brennecke, Joan F.

Subjects
Oxygen -- Chemical properties, Carbon -- Chemical properties, Water chemistry -- Research, Ionic crystals -- Research, Chemicals, plastics and rubber industries
Abstract

The high-pressure phase behavior of CO2 with six ionic liquids and the effect of systematically changing the anionic and cationic components of the ionic liquid on the CO2-ionic liquid phase behavior are studied. The result tries to explain the physical mechanism of the unusual phase behavior and also indicates the existence of the correlation between CO2 solubility and liquid molar volume.

Published
2001

161. Impact of a protic dimeric ionic liquid on PEM fuel cell performance and durability.

Author

Wang, Liang, Morales-Collazo, Oscar, Brennecke, Joan F., and Jia, Hongfei

Subjects
*LIQUID fuels, *IONIC liquids, *FUEL cells, *PROTON exchange membrane fuel cells
Abstract

Protic dimeric ionic liquid (IL) 9′9'-(butane-1, 4-diyl)bis (3,4,6,7,8,9-hexahydro-2H-pyrimido [1,2- a ]pyrimidin-1-ium) 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (D-HTBD) has been developed as a surface modifier to a PtCo/C oxygen reduction reaction (ORR) catalyst for polymer electrolyte membrane fuel cells (PEMFCs). Thermal properties, intrinsic conductivity, and viscosity were studied to understand the ionic liquid's protonation effect. The protic IL was incorporated into the PtCo/C catalyst and its effect on MEA performance at various humidities were evaluated and compared with pristine PtCo/C catalyst. Electrochemically active surface area, AC impedance and gas diffusion resistance of the MEAs with IL were compared with the PtCo/C catalyst without modification by IL. Besides promoting the oxygen reduction reaction activity of the PtCo/C catalyst, the protic dimeric IL enhances dry condition MEA performance significantly, attributed to the hydrogen bonds between the Brønsted acids and Brønsted bases. A durability study of the PtCo/C catalyst with and without IL shows the reduction of catalyst degradation after incorporating IL. This work suggests that the protic dimeric IL could be a promising modifier to enhance ORR catalyst activity, fuel cell performance and durability. [Display omitted] • Protic dimeric ionic liquid improves ORR catalyst performance and durability. • Dry condition MEA performance improves significantly owning to hydrogen bonds from the protic ionic liquid. • The protic ionic liquid shows high stability against water in MEAs. [ABSTRACT FROM AUTHOR]

Published
2024
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169. Guidelines for Reporting of Phase Equilibrium Measurements

Author

Chirico, Robert D., primary, De Loos, Theodoor W., additional, Gmehling, Jürgen, additional, Goodwin, Anthony R. H., additional, Gupta, Sumnesh, additional, Haynes, William M., additional, Marsh, Kenneth N., additional, Rives, Vicente, additional, Olson, James D., additional, Spencer, Calvin, additional, Brennecke, Joan F., additional, and Trusler, J. P. Martin, additional

Published
2016
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170. Thermodynamic and Thermophysical Properties of the Reference Ionic Liquid: 1-Hexyl-3-Methylimidazolium Bis[(Trifluoromethyl)Sulfonyl]Amide (Including Mixtures) Part 1. Experimental Methods and Results

Author

Marsh, Kenneth N., primary, Brennecke, Joan F., additional, Chirico, Robert D., additional, Frenkel, Michael, additional, Heintz, Andreas, additional, Magee, Joseph W., additional, Peters, Cor J., additional, Rebelo, Luis Paulo N., additional, and Seddon, Kenneth R., additional

Published
2016
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173. Editorial: Molecular Modeling and Simulation in JCED

Author

Kofke, David A., primary, Siepmann, J. Ilja, additional, Chirico, Robert D., additional, Kroon, Maaike, additional, Mathias, Paul M., additional, Sadowski, Gabriele, additional, Wu, Jiangtao, additional, and Brennecke, Joan F., additional

Published
2016
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175. CO2 Chemistry of Phenolate-Based Ionic Liquids

Author

Lee, Tae Bum, primary, Oh, Seungmin, additional, Gohndrone, Thomas R., additional, Morales-Collazo, Oscar, additional, Seo, Samuel, additional, Brennecke, Joan F., additional, and Schneider, William F., additional

Published
2015
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179. Enhancing Pt/C Catalysts for the Oxygen Reduction Reaction with Protic Ionic Liquids: The Effect of Anion Structure.

Author

Kan Huang, Tangqiumei Song, Morales-Collazo, Oscar, Hongfei Jia, and Brennecke, Joan F.

Subjects
CATALYSTS, OXYGEN, IONIC liquids
Abstract

Protic ionic liquids (ILs) have been recently studied as a potential approach to enhance oxygen reduction reaction (ORR) activity of carbon supported platinum catalysts (Pt/C) for application in polymer electrolyte membrane fuel cells. The high oxygen solubility in the ILs was suggested as one of the main reasons for the accelerated reaction rates. Because the nature of the anion of the IL has been associated with increased oxygen solubility, in this work we survey a number of ionic liquids with various anions to study this effect. While the search for direct correlation between the ORR activities and the oxygen solubilities does not produce any conclusive results, by contrast, the specific activity showed dependence on the availability of oxygenated species free Pt sites. This finding indicates that the inhibition of Pt oxidation and less adsorption of non-reactive species may also play an important role in the enhanced ORR activity. Moreover, the degree of IL coverage on the Pt surface was estimated using (bi)sulfate ions as an indicator. The surface coverage not only affected the ORR activity, but also the Pt dissolution process. This suggests that an optimal balance between activity and stability can be achieved on a partially covered Pt surface. [ABSTRACT FROM AUTHOR]

Published
2017
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180. Evaluating the Performance of Micro-Encapsulated CO2Sorbents during CO2Absorption and Regeneration Cycling

Author

Knipe, Jennifer M., Chavez, Kathya P., Hornbostel, Katherine M., Worthington, Matthew A., Nguyen, Du T., Ye, Congwang, Bourcier, William L., Baker, Sarah E., Brennecke, Joan F., and Stolaroff, Joshuah K.

Abstract

We encapsulated six solvents with novel physical and chemical properties for CO2sorption within gas-permeable polymer shells, creating Micro-Encapsulated CO2Sorbents (MECS), to improve the CO2absorption kinetics and handling of the solvents for postcombustion CO2capture from flue gas. The solvents were sodium carbonate (Na2CO3) solution, uncatalyzed and with two different promoters, two ionic liquid (IL) solvents, and one CO2-binding organic liquid (CO2BOL). We subjected each of the six MECS to multiple CO2absorption and regeneration cycles and measured the working CO2absorption capacity as a function of time to identify promising candidate MECS for large-scale carbon capture. We discovered that the uncatalyzed Na2CO3and Na2CO3-sarcosine MECS had lower CO2absorption rates relative to Na2CO3-cyclen MECS over 30 min of absorption, while the CO2BOL Koechanol appeared to permeate through the capsule shell and is thus unsuitable. We rigorously tested the most promising three MECS (Na2CO3-cyclen, IL NDIL0309, and IL NDIL0230) by subjecting each of them to a series of 10 absorption/stripping cycles. The CO2absorption curves were highly reproducible for these three MECS across 10 cycles, demonstrating successful absorption/regeneration without degradation. As the CO2absorption rate is dynamic in time and the CO2loading per mass varies among the three most promising MECS, the process design parameters will ultimately dictate the selection of MECS solvent.

Published
2019
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189. Co2 as a separation switch for ionic liquid/organic mixtures

Author

Scurto, Aaron M., Aki, Sudhir N. V. K., and Brennecke, Joan F.

Subjects
Ions -- Research, Ionization -- Analysis, Carbon dioxide -- Electric properties, Chemistry
Abstract

Chemists have always been intrigued by the usefulness of ionic liquids at room temperatures especially since they are used as solvents for extractions and reactions but separation of these liquids from organic and inorganic species is a difficult task. Experiments were conducted to use carbon dioxide to separate ionic liquids from their compounds.

Published
2002

192. Confronting Racism in Chemistry Journals

Author

Burrows, Cynthia J., Huang, Jiaxing, Wang, Shu, Kim, Hyun Jae, Meyer, Gerald J., Schanze, Kirk, Lee, T. Randall, Lutkenhaus, Jodie L., Kaplan, David, Jones, Christopher, Bertozzi, Carolyn, Kiessling, Laura, Mulcahy, Mary Beth, Lindsley, Craig W., Finn, M. G., Blum, Joel D., Kamat, Prashant, Choi, Wonyong, Snyder, Shane, Aldrich, Courtney C., Rowan, Stuart, Liu, Bin, Liotta, Dennis, Weiss, Paul S., Zhang, Deqing, Ganesh, Krishna N., Atwater, Harry A., Gooding, J. Justin, Allen, David T., Voigt, Christopher A., Sweedler, Jonathan, Schepartz, Alanna, Rotello, Vincent, Lecommandoux, Sébastien, Sturla, Shana J., Hammes-Schiffer, Sharon, Buriak, Jillian, Steed, Jonathan W., Wu, Hongwei, Zimmerman, Julie, Brooks, Bryan, Savage, Phillip, Tolman, William, Hofmann, Thomas F., Brennecke, Joan F., Holme, Thomas A., Merz, Kenneth M., Scuseria, Gustavo, Jorgensen, William, Georg, Gunda I., Wang, Shaomeng, Proteau, Philip, Yates, John R., Stang, Peter, Walker, Gilbert C., Hillmyer, Marc, Taylor, Lynne S., Odom, Teri W., Carreira, Erick, Rossen, Kai, Chirik, Paul, Miller, Scott J., Shea, Joan-Emma, McCoy, Anne, Zanni, Martin, Hartland, Gregory, Scholes, Gregory, Loo, Joseph A., Milne, James, Tegen, Sarah B., Kulp, Daniel T., and Laskin, Julia

Published
2020
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193. Physicochemical Properties

Author

Holbrey, John D., primary, Rogers, Robin D., additional, Mantz, Rob A., additional, Trulove, Paul C., additional, Cocalia, Violina A., additional, Visser, Ann E., additional, Anderson, Jessica L., additional, Anthony, Jennifer L., additional, Brennecke, Joan F., additional, Maginn, Edward J., additional, Welton, Tom, additional, and Mantz, Robert A., additional

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194. CHAPTER 6. New Fluids

Author

Wakeham, William A., primary, Egry, Ivan, additional, Brillo, Jürgen, additional, Nagasaka, Yuji, additional, Assael, Marc J., additional, Brennecke, Joan F., additional, Massel, Marjorie, additional, and Shi, Chaojun, additional

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195. Physicochemical Properties of Ionic Liquids

Author

Anthony, Jennifer L., primary, Brennecke, Joan F., additional, Holbrey, John D., additional, Maginn, Edward J., additional, Mantz, Rob A., additional, Rogers, Robin D., additional, Trulove, Paul C., additional, Visser, Ann E., additional, and Welton, Tom, additional

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