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Inthis work experimental vapor–liquid equilibrium (VLE)data and three-phase vapor–liquid–liquid equilibrium(VLLE) data are presented for the carbon dioxide 1-decanol system.The VLE data were measured at five temperatures, (303.2, 308.2, 323.2,333.2, and 343.2) K, and pressures up to 16 MPa. The VLLE data coverpressure–temperature (P–T) values from289 K and 5 MPa to the upper critical end point (UCEP). We have usedtwo models to represent the complex fluid phase behavior (P–Tcritical curve, VLLE line, and VLE isotherms)of the carbon dioxide 1-decanol system: the cubic general equationof state (GEOS) and Peng–Robinson (PR) equation in conjunctionwith van der Waals two parameters conventional mixing rules (2PCMR).A correlation method involving temperature-dependent interaction parametersand a semipredictive approach with independent temperature interactionparameters have been used. Comparisons with experimental data reportedin this work and available in the literature indicate that the topologyof fluid phase behavior is satisfactorily given by the semipredictiveprocedure both for the critical line and in subcritical region, consideringthe relative simple used cubic equations of state. [ABSTRACT FROM AUTHOR]

Enzymaticalcoholysis of fish oil can produce monoacylglycerolsrich in polyunsaturated fatty acids at atmospheric pressure and lowtemperature. Biocatalysis in organic solvents helps to create a homogeneousreaction system for the reactants, ethanol and fish oil. This workpresents liquid–liquid equilibrium at two different temperatures(303.2 K and 323.2 K) and at atmospheric pressure for two solvent-systemsin the ethanolysis of fish oil: ethanol oil tert-pentanol and ethanol oil hexane. Experimental solubility (binodal)curves were obtained by the cloud point method and tie-line compositionwas obtained by density and high-temperature gas chromatography. Theconsistency of experimental tie-line data was checked by using theOthmer–Tobias equation. The experimental liquid–liquiddata were correlated satisfactorily by the nonrandom two liquid modelfor activity coefficient calculations. [ABSTRACT FROM AUTHOR]

Transesterification of triolein in excess methanol oversodium-loadedcatalysts prepared from Na-ion exchange with zeolites at a relativelylower reaction temperature, namely, at 60 °C, is studied in thiswork. Two zeolites, i.e., as-synthesized ZeoliteMCM-22 and commercial Zeolite HY (CBV-780), are employed in this study.Althoughboth zeolites show to some extent the capability of catalyzing transesterificationof triolein in methanol to biodiesel, the resulting yields are onlyca. 90% for CBV-780 after a 40-h reaction and 16.3% for MCM-22 aftera90-h reaction. In contrast, the conversion yields are much improvedwith Na-ion exchange to the surface of zeolite catalysts. For example,the yields of triolein to biodiesel have reached 98% and 99% withina 5.5-h reaction, respectively, using the NaOH-treated CBV-780 andMCM-22 catalysts, even if these NaOH-treated catalysts become amorphousand have suffered a loss of the Brunauer–Emmett–Tellersurface area. Furthermore, no saponification was observed using theseNaOH-treated catalysts. [ABSTRACT FROM AUTHOR]

In this study, kinetics of formic acid-catalyzed xylosedehydrationinto furfural and furfural decomposition was investigated using batchexperiments within a temperature range of 130–200 °C.Initial xylose and furfural concentrations up to 0.2 and 0.08 mol/L,respectively, were used. The room temperature pH of the formic acidcatalyst solution was between 0.9 and 1.7. The kinetic model usedwas based on a specific acid catalysis model and included the prevailinghydrogen ion concentration in reaction conditions. The study showedthat the modeling must account for other reactions for xylose besidesdehydration into furfural. Moreover, the reactions between xyloseintermediate and furfural play only a minor role. The study also showedthat kinetic modeling of xylose and furfural decomposition reactionsmust take the uncatalyzed reaction in water solvent into account. [ABSTRACT FROM AUTHOR]

A computational study of the reaction of P(3P) with acetylene has been carried out. The only exothermicproducts correlating with the reactants are PCCH(2Π) H(2S). Two different pathways leadingto these products that are apparently barrier-free have been found.Both pathways involve isomerization into open-chain intermediatesfollowed by direct elimination of a hydrogen atom. The possibilityof spin-crossing has been considered because the species on the singletsurface are considerably more stable than those on the triplet one.On the singlet surface, there are other possible channels for thereaction, namely, cyclic PC2H(2A′) H(2S) and CCP(1Σ) H2(1Σg). A computationalkinetic study shows that, in agreement with the experimental evidence,the major products are PCCH(2Π) H(2S) at all temperatures. Only at very high temperatures isCCP(1Σ) H2(1Σg) formed in non-negligible amounts.Therefore, only PCCH눚⺕ be formed in the interstellarmedium. [ABSTRACT FROM AUTHOR]

Cycloplatinated neutral [Pt(C∧N){H2B(pz)2}] (1–3) [C∧N = benzoquinolate (bzq), 2-phenylpyridinate (ppy), and 2-phenylquinolate (pq)] and [Pt(pq){HB(pz)3}] 10and cationic [Pt(C∧N){H2C(pz)2}](4–6) and [Pt(C∧N){HC(pz)3}](7–9) complexes were synthesized by the reaction of the corresponding precursors [Pt(C∧N)(μ-Cl)]2with the adequate poly(pyrazolyl)-borate or -methane ligand. However, the reactions of [Pt(C∧N)(μ-Cl)]2(C∧N = bzq, ppy) with [HB(pz)3]−evolve with B–N bond cleavage, yielding the binuclear systems [Pt(C∧N)(μ-pz)]2as a mixture of cis and trans isomers. Complexes were characterized in solution by multinuclear and multidimensional NMR spectroscopy. The solid-state structures of 1, 3, 6, 7–9, and [Pt(bzq)(μ-pz)]2were confirmed by X-ray single-crystal studies. The absorption, emission, and electrochemical properties of these complexes are mainly dominated by the nature of the cyclometalated ligand and the charge of the complex. On the basis of TD-DFT calculations (1, 7–9), the lowest-energy absorption for neutral 1has been ascribed to a mixed 1ILCT/1MLCT transition, whereas for the cationic 7–9, it is mainly attributed to 1ILCT combined with some CT to both ligands in 9(1MLCT/ML′CT 9) or to the HC(pz)3in 7and 8(1ML′CT). These compounds are emissive in all media (except 4and 10in the solid state at 298 K). In the solid state at 298 K and at 77 K, these complexes display intense phosphorescence, which is typical of monomers. In deoxygenated CH3CN solutions at 298 K, phosphorescence is accompanied by higher-energy fluorescence in complexes 1, 4, and 8, which disappears at concentrated solutions and at 77 K. Complex 7displays a special behavior, observing fluorescence and/or excimer fluorescence only at 298 K and excimeric emission (diluted glasses) and emission from aggregates in concentrated glasses. TD-DFT of the lowest-lying excited states responsible for the phosphorescence of 1and 7–9reveals a 3ILCT origin with a mixed 3MLCT character for 1and, in the case of the cationic 7–9, a 3ILCT transition mixed with 3ML′CT (especially in 8) and with some 3MLCT in 9. [ABSTRACT FROM AUTHOR]

The surface tension of (2-methyl-2-butanol ethanol), (3-methyl-1-butanol ethanol), and (2-methyl-1-butanol ethanol) binary solutions was measured over the entire composition range and at temperatures from (293.15 to 323.15) K. The experimental data were correlated with the temperature, the maximum deviation being less than 0.4 %. [ABSTRACT FROM AUTHOR]

A combined exhaust gas aftertreatment system, consisting of a diesel oxidation catalyst (DOC), an NOxstorage and reduction catalyst (NSRC, which also is called lean NOxtrap, LNT), and a catalyst for selective catalytic reduction of NOxby NH3(NH3-SCR) is studied experimentally. The catalyst samples are placed in series in an almost isothermal laboratory minireactor. Dynamic behavior of the system is examined under periodic lean/rich operation in temperature range of 200−400 °C with varying composition of the rich mixture, containing CO, H2and C3H6. Concentrations of gas components are measured at the inlet, outlet, and between the individual catalysts. The individual DOC, NSRC, SCR, NSRC−SCR, and DOC−NSRC subsystems are also examined. The DOC is used as the first element in the exhaust aftertreatment line. It is responsible for the oxidation of CO and unburned hydrocarbons (HC), and it also supports the oxidation of NO to NO2. NSRC and SCR converters are employed for the abatement of nitrogen oxides. A significant amount of NH3can be formed in the NSRC as a byproduct of the NOxreduction, depending on the regeneration phase length, temperature, and gas composition. The generated ammonia is adsorbed in the SCR and used for additional NOxreduction. The dynamics of the combined system is investigated, and the conversions, selectivities, and reaction mechanisms in each converter, as well as mutual synergic and competitive effects, are discussed. [ABSTRACT FROM AUTHOR]

The pyrolysis of a chromium-tanned waste (bovine splitleather)under inert atmosphere has been carried out in a vertical lab scalereactor. The influence of process conditions, such as temperature,residence time, and heating rate on the pyrolytic product distributionhas been studied, in order to optimize the liquid fraction obtained.Flash pyrolysis at three different temperatures (450, 500, and 550°C) and slow pyrolysis up to 750 °C have been performed.Results indicate that, in the range of low temperatures, the productdistribution is slightly dependent on temperature. In general, a reductionof the heating rate or residence time favors the presence of heavygases (i.e., more than four carbon atoms hydrocarbons). The analysisof the pyrolytic liquid shows a wide spectrum of products (mainlynitrogenated and oxygenated compounds and phenols) which can be usefulas a source of chemicals. A comparison between the results reachedin the pyrolysis of tanned leather and a commercial collagen allowsus to study the effect of the tanning process. According to the resultobtained, the tanned leather produces more nitrogenated compoundsand phenols and less ketones and linear hydrocarbons than pure collagen.A very good agreement between the evolution of pyrolytic gases producedin a slow pyrolysis and the weight loss of the solid measured by thermogravimetricanalysis has been observed. [ABSTRACT FROM AUTHOR]

The reactions of the NHC-functionalized phosphines 1-[{2-(diphenylphosphino)phenyl}methyl]-3-methylimidazol-2-ylidene (Ph2PC6H4CH2ImMe) and 1-[{2-(dicyclohexylphosphino)phenyl}methyl]-3-methylimidazol-2-ylidene(Cy2PC6H4CH2ImMe) andthe NHC-functionalizedthioether 1-{(2-methylsulfide)ethyl}-3-methylimidazol-2-ylidene(MeSCH2CH2ImMe) with [Ru3(CO)12] have been studied. Both NHC-phosphines react with equimolaramounts of [Ru3(CO)12], inTHF at room temperature, to give the edge-bridged disubstituted products[Ru3(μ-κ2P,CNHC-R2PC6H4CH2ImMe)(CO)10], R = Ph (1), Cy (2), which selectivelyundergo a double C–H bond activation of their CH2group upon gentle warming (R = Ph) or at room temperature (R = Cy)to give the dihydrido derivatives [Ru3(μ-H)2(μ3-κ3P,C,CNHC-R2PC6H4CImMe)(CO)8], R = Ph (3) and Cy (4), respectively.These products contain novel face-capping ligands that arise fromthe oxidative addition of both C–H bonds of the correspondingNHC-phosphine ligand CH2group. This double-metalationprocess is facilitated by the rigidity of the C6H4CH2linker of these ligands. The treatment of[Ru3(CO)12] with 3 equivalents of Ph2PC6H4CH2ImMe leads to the mononuclearruthenium(0) complex [Ru(κ2P,CNHC-Ph2PC6H4CH2ImMe)(CO)3] (5). No trinuclear derivativeswere obtained from reactions of [Ru3(CO)12]with MeSCH2CH2ImMe, the tetranuclear derivative [Ru4(μ-κ2S,CNHC-MeSCH2CH2ImMe)(μ-CO)2(CO)10] (6) being the only product that could be isolated. Compound 6contains a butterfly arrangement of the metal atoms withthe wing tips bridged by the ligand sulfur atom, while the NHC fragmentis attached to one wing tip. [ABSTRACT FROM AUTHOR]

The structure and physicochemical properties of the nanoparticles spontaneously formed within aqueous mixtures of the hydrogenated/fluorinated catanionic surfactant cetyltrimetylammonium perfluorooctanoate in the absence of counterions as a function of its concentration are investigated by a combined experimental/computational study at room temperature. Apparent molar volumes, isentropic apparent molar compressibilities, and dynamic light scattering measurements together with transmission and cryo-scanning electron as well as confocal laser microscopy images, and computational molecular dynamics simulations indicate that a variety of structures of different sizes coexist in solution with vesicles of ∼160 nm diameter. Interestingly, the obtained nanostructures were observed to self-assemble from a random distribution of monomers in a time scale easily accessible by atomistic classical molecular dynamics simulations, allowing to provide a comprehensive structural and dynamic characterization of the surfactant molecules at atomic level within the different aggregates. Overall, it is demonstrated that the use of mixed fluorinated hydrogenated surfactant systems represents an easy strategy for the design of specific nanoscale structures. The detailed structural analysis provided in the present work is expected to be useful as a reference to guide the design of new nanoparticles based on different hydrogenated/fluorinated catanionic surfactants. [ABSTRACT FROM AUTHOR]

The influence of temperature (T) and ionic strength (Im) on the stoichiometric (molality scale) acidity constants of nicotinic acid in aqueous solution was investigated by potentiometry (H+glass electrode). The background salt used was potassium chloride, and the temperature and ionic strength ranges covered were 283.15 K < T< 318.15 K and 0.05 mol·kg–1< Im< 0.52 mol·kg–1, respectively. Acidity constants at zero ionic strength were derived by means of a Debye–Hückel type formalism, and their temperature dependence was obtained through a van't Hoff analysis. This led to pKa1= 2.19 ± 0.06 and pKa2= 4.86 ± 0.03 at 298.15 K and to the corresponding standard molar enthalpies and entropies of proton dissociation in the temperature range of the experiments, ΔrHm,l°= (4.5 ± 3.5) kJ·mol–1, ΔrSm,l°= −(26.8 ± 11.8) J·K–1·mol–1, ΔrHm,2°= (12.5 ± 2.1) kJ·mol–1, and ΔrSm,2°= −(51.2 ± 7.0) J·K–1·mol–1. These values were compared with previously reported data. [ABSTRACT FROM AUTHOR]

In this study, the phase behavior of an asymmetric system consisting of the refrigerant, trifluoromethane, and 1-phenyltetradecane, a lubricant from the family of alkylbenzenes, is investigated. Equilibrium data were obtained using a synthetic method in the temperature range 253.34−370 K and pressures up to12 MPa. The investigated system exhibits type III phase behavior, according to the classification of van Konynenburg and Scott. The new experimental data were modeled with two cubic equations-of-state, Soave−Redlich−Kwong (SRK) and Peng−Robinson (PR), and were coupled with classical van der Waals mixing rules. A single set of binary parameters was used to predict the global phase behavior of the system for a large range of pressure and temperature. Although the model is simple, it is able to represent correctly the complex phase equilibria of the system studied in this work. [ABSTRACT FROM AUTHOR]

Experimental results (and a correlation) are presented for the liquid−liquid equilibrium of an example for the Biphasic Acid Scavenging utilizing Ionic Liquids (BASIL) process: for the binary system (butylacetate 1-methyl imidazolium chloride) and for the partitioning of 1-butanol and 1-methyl imidazole to the coexisting liquid phases at temperatures from (363 to 373) K. [ABSTRACT FROM AUTHOR]

Thiswork addresses the measurement and modeling of the densitiesof seven vegetable oils (soybean, rapeseed, castor, palm, sunflower, Aleurites moluccana, and Jatropha curcasoils) at temperatures from (283.15 to 363.15) K and pressures from(0.1 to 45) MPa. The data measured here was correlated using the modifiedTait-Tammann equation, and the data was used to evaluate the predictiveabilities of the Halvorsen model, the fragment-based approach, andthe revised GCVOL group contribution method. The results show thatthe models studied described well the experimental data, presentingnot only stable deviations over the temperature range but also overallaverage relative deviations (OARD) of only (1.2, 0.34, and 1.1) %,respectively. An extension of the models here studied to high pressureis proposed. The models of Halvorsen, Zong, and revised GCVOL providevery good predictions of high-pressure densities with OARDs of (0.75,1.04, and 0.41) %, respectively, with the deviations presenting justa slightly pressure-dependent with maximum deviations of less than2.0 %. [ABSTRACT FROM AUTHOR]

Ethanol may be used in diesel−ethanol mixtures in order to decrease soot emissions. Therefore, it is important to evaluate the contribution of ethanol to soot formation. The influence of the temperature on the pyrolysis of ethanol under sooting conditions has been studied. Pyrolysis experiments were carried out in a quartz reactor in the 700−1200 °C temperature range, for an inlet C2H5OH concentration of 50 000 ppm and a gas residence time in seconds of 1706/(T/K) . The concentrations of the gases analyzed in the experiments are shown in this work together with simulations carried out with a literature kinetic model. Theoretical and experimental results present, generally, a good agreement in spite of the model not taking into account the soot formation. Under the studied conditions, soot formation has been observed above 1050 °C. With the soot samples obtained, a study of their reactivity toward O2and NO has been carried out, and several characterization techniques, such as elemental analysis, Brunauer−Emmett−Teller (BET) surface area, transmission electron microscopy, and X-ray diffraction have been used to study the structural properties of the collected soot samples and relate them to their reactivity. It has been observed that the soot samples formed at higher temperatures exhibit a lower reactivity toward O2and NO, and the characterization analyses support these results. [ABSTRACT FROM AUTHOR]