Thermophysical properties for (diethyl carbonate + p-xylene + octane) ternary system

The density and speed of sound of the ternary mixture (diethyl carbonate + p-xylene + octane) have been measured at atmospheric pressure and in the temperature range T = (288.15 to 308.15) K. Besides, surface tension has been also determined for the same mixture at T = 298.15 K. The experimental measurements have allowed the calculation of the corresponding derived properties: excess molar volumes, excess isentropic compressibilities, and surface tension deviations. Excess properties have been correlated using Nagata and Tamura equation and correlation for the surface tension deviation has been done with the Cibulka equation. Good accuracy has been obtained. Based on the variations of the derived properties values with composition, a qualitative discussion about the intermolecular interactions was drawn.     

近红外光谱预测汽油辛烷值和辛烷值仪的研制

本文报道了用近红外光谱预测汽油马达法辛烷值,研究法辛烷值和抗爆指数的方法。用多重线性回归和偏最小二乘法回归建立辛烷值的预测模型。基于此模型,首次研制成功光学多道近红外辛烷值仪。     

An octane-fueled low temperature solid oxide fuel cell with Ru-free anodes

A Ru-free anode was developed for the direct utilization of iso-octane in low temperature solid oxide fuel cells (SOFCs). The anode was consisted of a Ni framework and a nano-sized oxygen–ion conductor, samaria-doped ceria (SDC), which was coated onto the inner surface of the framework via an ion impregnation process. Compared with the cells based on conventional Ni–SDC anodes, single cells with the SDC-coated Ni anodes exhibited improved stability and enhanced electrochemical activity. Peak power density of 400 mW cm⁻² was achieved at 600 °C, and power generation was relatively stable over 260 h when iso-octane–air mixture was directly used as the fuel. The performance is comparable with those obtained using ceria-Ru as an internal reforming catalyst.     

不同硅铝比ZSM-5分子筛作为助催化剂在渣油裂化中的应用

采用不同方法表征了硅铝比(SiO2/Al2O3)为33、266和487的质子型ZSM-5分子筛,并研究了ZSM-5分子筛作为助催化剂在渣油裂解中的应用。与USY分子筛基催化剂混合后,在固定流化床上,评价了ZSM-5分子筛助催化剂的催化裂化性能。研究发现,提高ZSM-5分子筛硅铝比,可以有效抑制混合催化剂对汽油烯烃的裂解,从而避免了汽油烷烃的大量损失。加入ZSM-5助催化剂后,伴随着液化气(LPG)产率的增加,异丁烷和异戊烷产率增加,这可能是由USY基催化剂和ZSM-5助催化剂的综合效应引起的。汽油烷烃和芳烃含量的变化,引起了汽油辛烷值的增加。高硅铝比ZSM-5分子筛(硅铝比为266和487)不仅可以显著改善汽油的辛烷值,而且有效避免了汽油的大量损失。催化汽油辛烷值的改善主要是由于高硅铝比ZSM-5分子筛具有适宜的芳构化和异构化活性,这些变化主要源于高硅铝比ZSM-5分子筛小的孔道直径和适宜的酸性。     

Increasing the octane number of gasoline using functionalized carbon nanotubes

The octane number is one of the characteristics of spark-ignition fuels such as gasoline. Octane number of fuels can be improved by addition of oxygenates such as ethanol, MTBE (methyl tert-butyl ether), TBF (tertiary butyl formate) and TBA (tertiary butyl alcohol) as well as their blends with gasoline that reduce the cost impact of fuels. Carbon nanotubes (CNTs) are as useful additives for increasing the octane number. Functionalized carbon nanotubes containing amide groups have a high reactivity and can react with many chemicals. These compounds can be solubilized in gasoline to increase the octane number. In this study, using octadecylamine and dodecylamine, CNTs were amidated and the amino-functionalized carbon nanotubes were added to gasoline. Research octane number analysis showed that these additives increase octane number of the desired samples. X-ray diffraction (XRD), Fourier transforms infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetry analyses (TGA) were used for characterization of the prepared functionalized carbon nanotubes.     

Classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric or gas-chromatographic data and chemometrics tools

The approach for classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric permeability data has been proposed and compared with classification of same samples on the basis of gas-chromatographic data. The precision of dielectric permeability measurements was investigated by using ANOVA. The relative standard deviation of dielectric permeability was in the range from 0.3 to 0.5% for the range of dielectric permeability from 1.8 to 4.4. The application of exploratory chemometrics tools (cluster analysis and principal component analysis) allow to explicitly differentiate the gasoline and light gas condensate fractions into groups of samples related to specific octane number or origin. The neural networks allow to perfectly classifying the gasoline and light gas condensate fractions.     

Regio-selective hydroxylation of gem-difluorinated octanes by alkane hydroxylase (AlkB)

gem-Difluoromethylene substituted molecules constitute a distinct class of fluorinated compounds. In this study, special chemistry has been developed for their preparation based on the highly selective terminal hydroxylation of these gem-difluorinated octanes by AlkB (alkane hydroxylase) from Pseudomonas putida Gpo1 to form gem-difluorinated octan-1-ols. The hydroxylation reaction is performed by whole-cell catalysis. Identification of the distal- and proximal-hydroxylation products was made by ¹H, ¹³C, and ¹⁹F NMR; GC and GC/MSD; and/or by comparison with authentic standards in GC. To the best of our knowledge, we have obtained the first synthesis of 2,2-, 3,3- and 4,4-difluorooctan-1-ols, from simple and inexpensive starting materials.     

A chemical kinetic interpretation of the octane appetite of modern gasoline engines

Fuel anti-knock quality is a critical property with respect to the effective design of next-generation spark-ignition engines which aim to have increased efficiency, and lower emissions. Increasing evidence in the literature supports the fact that the current regulatory measures of fuel anti-knock quality, the research octane number (RON), and motor octane number (MON), are becoming decreasingly relevant to commercial engines. Extrapolation and interpolation of the RON/MON scales to the thermodynamic conditions of modern engines is potentially valuable for the synergistic design of fuels and engines with greater efficiency. The K-value approach, which linearly weights the RON/MON scales based on the thermodynamic history of an engine, offers a convenient experimental method to do so, although complementary theoretical interpretations of K-value measurements are lacking in the literature.This work uses a phenomenological engine model with a detailed chemical kinetic model to predict and interpret known trends in the K-value with respect to engine intake temperature, pressure, and engine speed. The modelling results support experimental trends which show that the K-value increases with increasing intake temperature and engine speed, and decreases with increasing intake pressure. A chemical kinetic interpretation of trends in the K-value based on fundamental ignition behaviour is presented. The results show that combined experimental/theoretical approaches, which employ a knowledge of fundamental fuel data (gas phase kinetics, ignition delay times), can provide a reliable means to assess trends in the real-world performance of commercial fuels under the operating conditions of modern engines.     

On-line octane-number analyser for reforming unit effluents. Principle of the analyser and test of a prototype

An on-line automatic explosion-proof process octane-number analyser was developed. The principle is based on on-line capillary gas chromatographic analysis of the sample. A computer program performs the identification and the quantification of the components and calculates the octane numbers and other physical properties. The process analyser consists of laboratory equipment placed in an explosion-proof shelter. A prototype of the analyser was tested on a pilot plant under industrial conditions. It was shown that the fully automated analyser is reliable and reproducible.