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171.
《Analytical letters》2012,45(11):849-855
Abstract Atomic absorption spectroscopy has been used to determine the concentration of lead in gasoline. The method employs the use of iodine to “level” the variation in response of different lead alkyls. It has been reported that this method is useless when applied to real gasolines, possibly because of the interference of iodine with olefins in the gasoline. The work performed here shows that olefins do not interfere with the lead analysis even when the concentration of olefins is 254 times that of iodine in the test gasoline. 相似文献
172.
《Physics and Chemistry of Liquids》2012,50(5):637-654
Abstract Consistent vapor-liquid equilibria data at 94.00 kPa have been determined for the ternary system ethyl 1,1-dimethylethyl ether + benzene + 2,2,4-trimethylpentane and for its constituent binary benzene + 2,2,4-trimethylpentane, in the temperature range 343 to 370 K. The systems exhibit slight positive deviations from ideal behavior and the system benzene + 2,2,4-trimethylpentane presents an azeotrope. The VLE data have been correlated with the mole fraction using the Redlich-Kister, Wilson, NRTL, UNIQUAC, and Tamir relations. These models, in addition to UNIFAC, allow good prediction of the VLE properties of the ternary system from those of the pertinent binary systems. 相似文献
173.
Isobaric Vapor-Liquid Equilibria in the Systems Ethyl 1,1-Dimethylethyl Ether + Hexane and + Heptane
《Physics and Chemistry of Liquids》2012,50(2):217-232
Abstract Pure-component vapor pressure of ethyl 1,1-dimethylethyl ether and vapor-liquid equilibrium for the binary systems of ETBE with hexane and with heptane have been measured at 94kPa. Both systems deviate slightly from ideal behavior, can be described as regular solutions and do no present an azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by the Redlich-Kister, Wohl, Wilson, UNIQUAC, NRTL, and Wisniak-Tamir equations. 相似文献
174.
Hoeil Chung 《应用光谱学评论》2013,48(3):251-285
Abstract This review primarily concerns NIR (near‐infrared) applications in refineries. Initially, this article reviews the fundamental aspects for analysis of hydrocarbon mixture by NIR spectroscopy, such as spectral sensitivity in various spectral regions, signal‐to‐noise ratio, and spectral resolution. Though there are applications of NIR to diverse petroleum products, this review subsequently focuses only on applications to four major products: gasoline, diesel, naphtha, and crude oil, which are the most interesting from a refiner's viewpoint. In each application, discussion of important issues to consider for proper and optimal NIR measurement is included. Finally, the issue of calibration transfer is discussed. 相似文献
175.
This work presents the application of continuous thermodynamics to investigate the limited miscibility of methanol–gasoline blends. To predict the liquid–liquid equilibrium of these systems, the Gaussian distribution function was used to represent the composition of paraffins in the gasoline. The naphthenes and aromatics were represented by model compounds. A model has been developed using three different continuous versions of the UNIFAC model. Methanol is an associating component, and association affects phase equilibria. Therefore, the CONTAS (continuous thermodynamics of associating systems) model based on the Flory–Huggins equation, for multicomponent methanol–gasoline blends has also been investigated. The predicted results including the cloud point curve, shadow curve and phase separation data have been compared with experimental data and good agreement was found for the two UNIFAC and CONTAS models. 相似文献
176.
一种市售汽油添加剂,常温下是半固态。加少量到一定量汽油中,轻摇即可溶解。但当温度降低到10℃,小晶体颗粒陆续开始析出。温度降到0℃时,溶质基本完全析出,且逐渐形成较大的颗粒团,严重影响了此添加剂在低温环境下的使用。为此我们进行了其延时降凝研究。发现溶液中加入少量具有较强极性可与溶质形成氢键、同时具有与溶剂部分相似结构的化合物异丙醇二甲基甲酰胺等,可使溶质在-15℃以下不析出,保持为均匀溶液。1 实验部分此添加剂的主要成份是分子量较大的软脂酸甘油酯,凝固点19℃。据此,在含溶质5%的条件下加入尽可能少的不同溶剂(下… 相似文献
177.
178.
Isotactic crystalline low-molecular-weight poly(1-butene), iPBu-1, was synthesised by using a metallocene catalyst. The molecular weight was determined by GPC. The chemical structure of iPBu-1 was verified by using high-temperature (13)C NMR spectroscopy and the thermal properties by differential scanning calorimetry (DSC). The (solid+liquid) equilibria, SLE, of iPBu-1 with different hydrocarbons (n-hexadecane, 1-heptene, 1-heptyne, cyclopentane, cyclohexane, cycloheptane, cyclooctane, benzene and propylbenzene) were studied by a dynamic method. By performing these experiments over a large concentration range, the temperature-mole fraction phase diagrams of the polymer-solvent systems could be constructed. From these diagrams it was found that iPBu-1 had the highest solubility in small-ring cycloalkanes and the lowest in n-hexadecane, 1-heptyne and benzene in the mole fraction range measured. The excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase and to estimate the solubility of iPBu-1 in the whole mole fraction range. Activity coefficients at infinite dilution of polymer and solvent were determined from the solubility measurements and were predicted by using the UNIFAC FV model and molecular Monte Carlo simulations. 相似文献
179.
Methyl tert-butyl ether (MTBE) as an octane promoter in automobile fuels has been phased out in some countries due to environmental problems. This motivates substantial interest in finding new ways for upgrading gasoline[1,2]. The use of a replacement for MTBE, such as ethanol, is a feasible method to enhance the oxygenates and increase the octane number of gasoline[3]. 相似文献
180.