首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Molar excess enthalpies H E have been measured for the binary mixtures MTBE+methanol, MTBE+n-heptane and methanol+n-heptane using a quasi-isothermal flow calorimeter. The measurements have been performed at atmospheric pressure and at 25 and 40°C for all the mixtures and for MTBE+methanol also at 50°C. The experimental results for MTBE methanol and MTBE+n-heptane are compared with those calculated using the NRTL equation.Communicated at the Festsymposium celebrating Dr. Henry V. Kehiaian's 60th birthday, Clermont-Ferrand, France, 17–18 May 1990  相似文献   

2.
The excess molar enthalpy of ternary mixture for 3-diethylaminopropylamine+heptane+cyclohexane were measured using a Calvet microcalorimeter at 303.15 K. Empirical equations, Redlich-Kister, Tsao-Smith, and Kohler and group contribution models, UNIFAC (modified version) and DISQUAC have been applied. A reasonable representation of ternary data is obtained. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
Excess molar enthalpies are measured for the binary mixtures methanol—acetonitrile and ethanol—acetonitrile at 25 and 35°C and for the ternary mixtures methanol—acetonitrile—benzene and ethanol—acetonitrile—benzene at 25°C using an isothermal dilution calorimeter. The binary results are well reproduced with an association model which contains four equilibrium constants for the association of alcohol, two equilibrium constants for that of acetonitrile, and two solvation equilibrium constants between alcohol and acetonitrile molecules. The ternary results are compared with those calculated from the model with binary parameters.  相似文献   

4.
Excess molar enthalpies of the ternary mixture {x1 tert-butyl methyl ether (MTBE)+x2 ethanol+(1–x1x2) hexane} and, the involved binary mixtures {x tert-butyl methyl ether (MTBE)+(1–x) ethanol}, {x tert-butyl methyl ether (MTBE)+(1–x) hexane} and {x ethanol+( 1–x) hexane} have been measured at 298.15 K and atmospheric pressure, over the whole composition range, using a Calvet microcalorimeter. The results were fitted by means of different variable degree polynomials.  相似文献   

5.
Excess molar enthalpies of the ternary mixture {x 1 tert-butyl methyl ether (MTBE)+x 2 ethanol+(1–x 1x 2) octane} and the involved binary mixture {x ethanol+(1–x) octane} have been measured at 298.15 K and atmospheric pressure, over the whole composition range, using a Calvet microcalorimeter. The results were fitted by means of different variable degree polynomials.  相似文献   

6.
Excess molar enthalpies, measured at 25°C in a flow microcalorimeter, are reported for the three ternary systems [ethanol + methyl tert-butyl ether + (n-hexane or 2,3-dimethylbutane, or cyclohexane)]. Smoothing equations were fitted to the results and used to construct constant excess enthalpy contours for each of the systems.  相似文献   

7.
Excess molar volumes are reported for binary mixtures of methyl tert-butyl ether with trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, or 1,1,1,2,2-pentachloroethane at 30°C over the entire composition range of the mixtures. Excess volumes for all the mixtures are found to be negative. A qualitative interpretation of the results in terms of O–H–C and Cl–O interactions is presented. The Prigogine-Flory-Patterson theory has been used to analyze the results.  相似文献   

8.
Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are oxygenated compounds added to gasoline to enhance octane rating and to improve combustion. They may be found as pollutants of living and working environments. In this work a robotized method for the quantification of low level MTBE, ETBE and TAME in human urine was developed and validated. The analytes were sampled in the headspace of urine by SPME in the presence of MTBE-d12 as internal standard. Different fibers were compared for their linearity and extraction efficiency: carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene, and polydimethylsiloxane. The first, although highly efficient, was discarded due to deviation of linearity for competitive displacement, and the polydimethylsiloxane/divinylbenzene fiber was chosen instead. The analysis was performed by GC/MS operating in the electron impact mode. The method is very specific, with range of linearity 30-4600 ng L−1, within- and between-run precision, as coefficient of variation, <22 and <16%, accuracy within 20% the theoretical level, and limit of detection of 6 ng L−1 for all the analytes. The influence of the matrix on the quantification of these ethers was evaluated analysing the specimens of seven traffic policemen exposed to autovehicular emissions: using the calibration curve and the method of standard additions comparable levels of MTBE (68-528 ng L−1), ETBE (<6 ng L−1), and TAME (<6 ng L−1) were obtained.  相似文献   

9.
The H-forms of mordenite, ZSM-11 and ZSM-5 zeolites were employed for the decomposition of methyl tert-butyl ether to methanol and isobutene. It was found that even at low temperatures the zeolites exhibit an extremely high and relatively very stable activity and selectivity in this decomposition compared with the amorphous silica-based catalysts.
- ZSM-11 ZSM-5 -.- . , , , .
  相似文献   

10.
11.
Excess enthalpies of di-n-butyl ether and methyl-tert-butyl ether with trichloromethane, tetrachloromethane, 1,2-dichloroethane, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane have been determined at 26.9°C. Excess enthalpies H m E for all (except di-n-butyl ether + dichloroethane and + trichloroethane) of the binary mixtures are found to be negative. Enthalpies are generally more negative for mixtures containing methyl-tert-buthyl ether. The results have been compared with our earlier data on tetrahydrofuran and tetrahydropyran with chloroalkanes.  相似文献   

12.
13.
14.
The influence of the composition and structure of heteropolyacids (HPA) on their catalytic activity in the liquid phase synthesis of methyl tert-butyl ether (MTBE) at 42 °C has been studied. The activity of HPA is compared with that of other acid catalysts. The most active are HPA's of the Dawson structure, then come HPA's of the Keggin and Dexter-Silverton structures. HPA salts have low activity in the synthesis of MTBE.
() () 42°C. . , -. .
  相似文献   

15.
Ab initio calculations are presented representing the ionization of tertbutyl methyl ether and its subsequent fragmentation via loss of a methyl radical. This process is shown to proceed via an ion-molecule complex, the nature of which is explored. The results obtained are found to be consistent with mass spectrometric evidence.  相似文献   

16.
A strategy is described to determine the second and third cross interaction coefficients h ij , h iij , and h ijj for the viral expansion of the excess enthalpies of aqueous solutions of non-electrolytes when these coefficients are comparable in magnitude and opposite in sign. Gross errors can occur especially if both self interaction coefficients h ii and h jj are small, if the heats of mixing are small, or if the extrapolation must be carried out from moderately concentrated regions. The exemplary case of two solutes, as different as glycerol and urea, is extensively discussed.  相似文献   

17.
Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures formed by mixing either methyl tert-butyl ether with binary mixtures of 3-methylpentane and either n-decane or n-dodecane. Smooth representations of the ternary results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is found that the Liebermann and Fried model also provided good representation of the ternary results, using only the physical properties of the components and their binary mixtures.  相似文献   

18.
The heats of dilution of nine ternary solutions of urea and polyols have been determined at 25°C. Excess enthalpies and their virial coefficients h xy have been evaluated and compared with the data reported in the literature for mono- and polyfunctional alcohols and other oxygenated nonelectrolytes. The group additivity approach of Savage and Wood was applied and the contributions to the enthalpy coefficients, due to the water mediated interactions between urea and the functional groups –CH2–, –OH, and –O– were determined. On the other hand, by using empirical combination rules among the cross- and self-enthalpic interaction coefficients it is possible to emphasize the large differences in the behavior (even in the presence of urea) of the polyols (and in particular of cyclitols) and of saccharides.  相似文献   

19.
Journal of Thermal Analysis and Calorimetry - Excess molar enthalpies, H m E , for the ternary mixture n-propanol (n-PrOH)&nbsp;+&nbsp;n-propyl acetate (n-PrOAc)&nbsp;+&nbsp;water...  相似文献   

20.
The excess molar enthalpies HmE of methyl propanoate or methyl pentanoate + 1-butanol, + 1-hexanol, + 1-octanol, and + 1-decanol have been determined experimentally at 298.15 K using a Calvet microcalorimeter. For all these mixtures HmE > 0; the values increase with the chain length of the alkanol but decrease as the ester chain lengthens.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号