Canepa P.,Massachusetts Institute of Technology |
Canepa P.,Lawrence Berkeley National Laboratory |
Jayaraman S.,Massachusetts Institute of Technology |
Jayaraman S.,Chemours Company |
And 9 more authors.
Energy and Environmental Science | Year: 2015
Non-aqueous Mg-ion batteries offer a promising way to overcome safety, costs, and energy density limitations of state-of-the-art Li-ion battery technology. We present a rigorous analysis of the magnesium aluminum chloride complex (MACC) in tetrahydrofuran (THF), one of the few electrolytes that can reversibly plate and strip Mg. We use ab initio calculations and classical molecular dynamics simulations to interrogate the MACC electrolyte composition with the goal of addressing two urgent questions that have puzzled battery researchers: (i) the functional species of the electrolyte, and (ii) the complex equilibria regulating the MACC speciation after prolonged electrochemical cycling, a process termed as conditioning, and after prolonged inactivity, a process called aging. A general computational strategy to untangle the complex structure of electrolytes, ionic liquids and other liquid media is presented. The analysis of formation energies and grand-potential phase diagrams of Mg-Al-Cl-THF suggests that the MACC electrolyte bears a simple chemical structure with few simple constituents, namely the electro-active species MgCl+ and AlCl4 - in equilibrium with MgCl2 and AlCl3. Knowledge of the stable species of the MACC electrolyte allows us to determine the most important equilibria occurring during electrochemical cycling. We observe that Al deposition is always preferred to Mg deposition, explaining why freshly synthesized MACC cannot operate and needs to undergo preparatory conditioning. Similarly, we suggest that aluminum displacement and depletion from the solution upon electrolyte resting (along with continuous MgCl2 regeneration) represents one of the causes of electrolyte aging. Finally, we compute the NMR shifts from shielding tensors of selected molecules and ions providing fingerprints to guide future experimental investigations. © 2015 The Royal Society of Chemistry.
Petrov V.A.,Chemours Company |
Dooley R.,Chemours Fluoroproducts Analytical Experimental Station |
Marchione A.A.,Chemours Fluoroproducts Analytical Experimental Station |
Marshall W.,DuPont Company
Journal of Fluorine Chemistry | Year: 2016
Reaction of indoles with 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane 1 in the presence of CsF catalyst led to the rapid and high yield formation of indoles bearing a -SCH(CF3)2 group in the 3-position. The same reaction carried out in the absence of catalyst unexpectedly resulted in the formation of indoles bearing a-C(CF3)2S2CH(CF3)2 group in the 3-position. Pyrrole, 2-Ethyl-1H-pyrrole and 2,4-dimethyl-1H-pyrrole were found to be more reactive toward 1, giving the corresponding 1:1 adducts, while both furan and thiophene were not active toward 1 even at elevated temperature. Activated 2,3-dimethylfuran gave the corresponding 1:1 adduct in the reaction with 1, while both 2,5-dimethylfuran and 2,5-dimethylthiophene reacted with 1 at elevated temperature giving the corresponding ene-products. © 2015 Elsevier B.V. All rights reserved.
Thermodynamic properties of cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)): Measurements of the pρT property and determinations of vapor pressures, saturated liquid and vapor densities, and critical parameters
Tanaka K.,Nihon University |
Akasaka R.,Kyushu Sangyo University |
Sakaue E.,Toshiba Corporation |
Ishikawa J.,DuPont Company |
Kontomaris K.K.,Chemours Company
Journal of Chemical and Engineering Data | Year: 2016
In this work, comprehensive measurements of pρT (pressure-density-temperature) properties of cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) were performed. Although this novel fluid has been proposed for various applications, including its use as a possible working fluid for organic Rankine cycle systems, reliable experimental data on its thermodynamic properties are scarcely available. In this work, the isochoric method was employed to obtain the properties of this fluid along 26 isochores for densities between 88 and 1295 kg·m-3, and 344 pρT data points were obtained in the temperature range from 323 K (49.85 °C) to 503 K (229.85 °C) and at pressures up to 10 MPa. The data covered single-phase liquid and vapor regions, two-phase region, and supercritical region. The data in the critical region were correlated with a simple polynomial expression, which was used to determine the critical parameters analytically. The vapor pressures and the densities of the saturated liquid and vapor were obtained from an analysis of the single- and two-phase data. The experimental uncertainties in the measurements of temperatures, pressures, densities below 100 kg·m-3, and higher densities were estimated to be 0.028 K, 4 kPa, 0.6%, and 0.4%, respectively. © 2016 American Chemical Society.
Warheit D.B.,Chemours Company |
Donner E.M.,DuPont Company
Food and Chemical Toxicology | Year: 2015
The basic tenets for assessing health risks posed by nanoparticles (NP) requires documentation of hazards and the corresponding exposures that may occur. Accordingly, this review describes the range and types of potential human exposures that may result from interactions with titanium dioxide (TiO2) particles or NP - either in the occupational/workplace environment, or in consumer products, including food materials and cosmetics. Each of those applications has a predominant route of exposure. Very little is known about the human impact potential from environmental exposures to NP - thus this particular issue will not be discussed further. In the workplace or occupational setting inhalation exposure predominates. Experimental toxicity studies demonstrate low hazards in particle-exposed rats. Only at chronic overload exposures do rats develop forms of lung pathology. These findings are not supported by multiple epidemiology studies in heavily-exposed TiO2 workers which demonstrate a lack of correlation between chronic particle exposures and adverse health outcomes including lung cancer and noncancerous chronic respiratory effects. Cosmetics and sunscreens represent the major application of dermal exposures to TiO2 particles. Experimental dermal studies indicate a lack of penetration of particles beyond the epidermis with no consequent health risks. Oral exposures to ingested TiO2 particles in food occur via passage through the gastrointestinal tract (GIT), with studies indicating negligible uptake of particles into the bloodstream of humans or rats with subsequent excretion through the feces. In addition, standardized guideline-mandated subchronic oral toxicity studies in rats demonstrate very low toxicity effects with NOAELs of >1000 mg/kg bw/day. Additional issues which are summarized in detail in this review are: 1) Methodologies for implementing the Nano Risk Framework - a process for ensuring the responsible development of products containing nanoscale materials; and 2) Safe-handling of nanomaterials in the laboratory. © 2015 Elsevier Ltd.
Koban M.E.,Chemours Company
International Journal of Automotive Engineering | Year: 2016
HFO-1234yf is a low GWP refrigerant developed for automotive air-conditioning (A/C) systems to replace HFC-134a. Industry-wide risk assessments found that HFO-1234yf can be safely used in mobile A/C applications with results previously presented. Various global automotive OEMs have transitioned to HFO-1234yf at selected manufacturing sites in different regions. This paper documents critical steps for successful transition, including installation, commissioning and startup of storage and vehicle charging facilities. Observations will also be shared concerning potential pit-falls that have been encountered during new refrigerant implementation at these sites. © 2016 Society of Automotive Engineers of Japan, Inc.