排序方式: 共有37条查询结果,搜索用时 31 毫秒
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Eugene Olivier Trevor M. Letcher Paramespri Naidoo Deresh Ramjugernath 《The Journal of chemical thermodynamics》2011,43(6):829-833
Activity coefficients at infinite dilution were determined for 27 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, alcohols, and ketones in the ionic liquid 1-butyl-3-methylimidazolium hexafluoroantimonate, [BMIM][SbF6], by gas–liquid chromatography at three different temperatures, T = (313.15, 323.15, and 333.15) K. The results are compared to published data on related compounds. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental data over the same temperature range. Selectivities and capacities at infinite dilution were calculated for the hexane/benzene and methanol/benzene systems from experimental infinite dilution activity coefficients and compared to the literature values for related ionic liquids, as well as to data on industrial molecular solvents. 相似文献
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Chien-Bin Soo Elise El Ahmar Christophe Coquelet Deresh Ramjugernath Dominique Richon 《Fluid Phase Equilibria》2009
Vapor–liquid equilibrium (VLE) data are presented for the n-butane + ethanol system in the temperature range from 323 to 423 K. Measurements were performed using a “static-analytic” apparatus, equipped with two electromagnetic ROLSI™ capillary samplers, and thermally regulated via an air bath. This work presents vapor compositions which have not been explicitly measured previously. The modeling of the data was performed using two models: the Peng–Robinson equation of state with the Wong and Sandler mixing rule and NRTL excess function (PR/WS/NRTL); and the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state. To assess the effect of dipole–dipole interactions present, a dipolar contribution developed by Jog and Chapman (1999) [20] was tested with the second model. Temperature dependent binary interaction parameters have been adjusted to the new data. The PR/WS/NRTL equation of state shows good correlation with the results, while the PC-SAFT is slightly less accurate. 相似文献
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Amir H. Mohammadi Ali Eslamimanesh Veronica Belandria Dominique Richon Paramespri Naidoo Deresh Ramjugernath 《The Journal of chemical thermodynamics》2012
The application of semi-clathrate hydrate formation technology for gas separation purposes has gained much attention in recent years. Consequently, there is a demand for experimental data for relevant semi-clathrate hydrate phase equilibria. In this work, semi-clathrate hydrate dissociation conditions for the system comprising mixtures of {CO2 (0.151/0.399 mole fraction) + N2 (0.849/0.601 mole fraction) + 0.05, 0.15, and 0.30 mass fraction tetra-n-butylammonium bromide (TBAB)} aqueous solutions have been measured and are reported. An experimental apparatus which was designed and built in-house was used for the measurements using the isochoric pressure-search method. The range of conditions for the measurements was from 277.1 K to 293.2 K for temperature and pressures up to 16.21 MPa. The phase equilibrium data measured demonstrate the high hydrate promotion effects of TBAB aqueous solutions. 相似文献
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Roger A. Harris Michael Wilken Kai Fischer Trevor M. Letcher J. David Raal Deresh Ramjugernath 《Fluid Phase Equilibria》2007
High pressure vapor–liquid equilibrium data for binary systems of carbon dioxide with naphthalene and benzoic acid were measured at three different temperatures for each system. Experimental temperatures and pressures ranged from 373 to 458 K and 0 to 22 MPa, respectively. Dew points were also measured for naphthalene in the CO2 rich region. The data measured provides valuable solubility information and is used to derive gas–solvent group interaction parameters for the predictive Soave–Redlich–Kwong equation of state. 相似文献
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Gas‐phase equilibrium constants for the thermally initiated oxidation of hexafluoropropene with molecular oxygen 下载免费PDF全文
David Lokhat Deresh Ramjugernath Maciej Starzak 《Journal of Physical Organic Chemistry》2015,28(7):460-471
Equilibrium constants for a kinetic model of the thermally initiated gas‐phase oxidation of hexafluoropropene have been calculated in the temperature range of 463–493 K based on the thermochemical properties of the reactive species. Standard molar enthalpies and entropies of formation as well as heat capacities of trifluoroacetyl fluoride, hexafluorocyclopropane, hexafluoropropene, and hexafluoropropene oxide were predicted using methods of quantum statistical mechanics. These along with literature data for remaining species involved allowed for calculating reaction enthalpies of individual steps of the proposed reaction mechanism. The calculations were performed at the G4 B3LYP/6‐31G(2df,p) level of theory. The enthalpy of formation was determined using both the atomization method and isodesmic reaction schemes. All reactions apart from the decomposition of hexafluoropropene oxide were found to be exothermic. Only the hexafluoropropene oxide decomposition reaction was found to be noticeably reversible under the reaction conditions considered. This was confirmed through independent experimentation and kinetic model identification. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Paramespri Naidoo Deresh Ramjugernath Johan David Raal 《Fluid Phase Equilibria》2008,269(1-2):104-112
A new variable volume static type high-pressure VLE apparatus has been designed, constructed, and tested on a number of systems. The apparatus has an operating temperature range from 250 K to 393 K and pressure range from absolute vacuum up to 120 bar. The stainless steel equilibrium cell has sapphire viewing windows and a novel liquid sampling technique utilizing gas chromatographic sampling valves which permit phase sampling without disturbance to the equilibrium condition. The apparatus was tested by measuring VLE isotherms for some binary systems, viz., carbon dioxide + toluene at 283.25 K, 311.15 K, 353.15 K and 391.45 K; carbon dioxide + methanol at 263.15 K, 273.15 K, 313.15 K, 363.15 K and 373.15 K; and propane + 1-propanol at 323.15 K, 378.15 K and 393.15 K. Satisfactory modeling was obtained of the measured VLE data and thermodynamic consistency tests showed the data to be not inconsistent. 相似文献
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Mehdi Sattari Farhad Gharagheizi Poorandokht Ilani-Kashkouli Amir H. Mohammadi Deresh Ramjugernath 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1863-1882
In this communication, a new approach is presented which combines a group-contribution (GC) method approach with genetic function approximation (GFA) for the prediction of liquid heat capacities at constant pressure (C pL) for ionic liquids at atmospheric pressure. The proposed method can be used instead of complicated nonlinear modeling approaches like artificial neural networks and support vector machine. The NIST standard reference database was used to prepare a dataset for C pL data. The dataset comprised 82 ionic liquids and consisted of 3,726 experimental data points. The dataset was divided such that 80 % of the data were used as a training set, and 20 % as a validation and test set. GFA was used to select functional groups, from which the GC based model was developed. Statistical analysis of the model shows that it has an overall average absolute relative deviation of 1.68 %, coefficient of determination (R 2) of 0.990, and root mean square of error (RMSE) of 18.42 J mol?1 K?1. 相似文献
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Capillary gas chromatography was investigated as a method of analyzing and quantifying the products of the high-temperature gas-phase oxidation of hexafluoropropene. Standard polysiloxane polymer stationary phases were found to be ineffective in separating the aggressive mixture of oxyfluorocarbons and perfluorocarbons. Adsorbent type stationary phases provided better retention and separation for the exceedingly volatile components than polar/non-polar liquid phases. The tested silica-based porous-layer phase was found to be susceptible to degradation through interaction with acid fluoride species. The analysis was ultimately performed in two stages. Authentic oxidation product gas samples were first analyzed, then treated with aqueous potassium hydroxide to remove carbonyl compounds and resampled to determine oxygen content on the same system. Detector response factor ratios for a number of different perfluorocarbons were obtained, the information which is useful for chromatographic method development but is conspicuously absent in the open literature. The system was found to have good long-term stability with calibration deviations of less than 3% over a period of two years. 相似文献