汽油对柴油质量的影响及柴油质量存在的问题

通过改变柴油中汽油的加入量,探讨了柴油中混入汽油时对柴油闪点、凝点、冷滤点、馏程几项指标的影响,并分析了目前我国柴油质量存在的主要问题.     

EIS study of corrosion behavior of metallic materials in ethanol blended gasoline containing water as a contaminant

In the present paper, the effects of ethanol as a gasoline additive and water as a contaminant on the corrosion behavior of metallic components of a fuel delivery system were investigated. Electrochemical impedance spectroscopy (EIS) testing was performed in both water-free and water contaminated gasoline containing 0%, 5%, 10% and 15% ethanol without the addition of any supporting electrolyte. The surface of the specimens examined in 10% ethanol blended gasoline was observed by scanning electron microscope to understand what types of corrosion attack occurred. The results revealed that the addition of ethanol to gasoline fuel decreased the solution resistance and polarization resistance values of the specimens, resulting in an increase in the corrosion rates of these specimens in ethanol blended gasoline. Water contaminant caused a decrease in the polarization resistance of the ferrous specimens, whereas the observed behavior in others was reversed. Among the investigated metallic materials, the brazing alloy fared the best while Al 6061 alloy showed satisfactory corrosion resistance compared to the rest of the materials in both water-free and water-contaminated ethanol blended gasoline. Moreover, no localized attack was observed in corrosion products.     

Combined PFPD–FID assessment of sulfur in liquid fuels

A pulsed flame photometric detector (PFPD) was calibrated using standard sulfur compounds present in gasoline and diesel fuels, in combination with a flame ionization detector (FID). Gasoline range standards were added to a hydrocarbon mixture simulating gasoline, with individual sulfur concentrations from 3 to 80 ppm. Diesel range standards were added to a low sulfur commercial diesel fuel, with sulfur concentrations from 10 to 100 ppm. In gasoline, both the chromatographic areas calculated with the linearized signal (data points elevated to a given power), and reported by the instrument were regressioned with the sulfur mass concentrations. In both cases the areas were normalized with the FID areas to reduce deviations. Results were better when using the linearized signal. Only the normalized areas calculated with the linearized signal can be used in the case of the diesel, due to significant peak coelution. Individual calibration coefficients were calculated for each standard, but overall coefficients can be used safely in each of the boiling ranges. The compliance of regulations about sulfur was verified in commercial fuels and the different sulfur compounds were inspected. The simultaneous combined FID-PFPD use allows adding the sulfur to the conventional analysis of liquid fuels (e.g. composition, simulated distillation).     

Effect of ethanol addition in gasoline and gasoline–surrogate on soot formation in turbulent spray flames

The effect of ethanol on soot formation has been studied in turbulent spray flames of gasoline/ethanol and gasoline–surrogate/ethanol mixtures containing 10%, 20% and 30% of alcohol in volume. A hybrid burner specially designed to stabilize different liquid fuels flames with identical hydrodynamic conditions has been used. Spatially resolved measurements of soot volume fraction and of soot precursors concentration have been carried out by coupling Laser-Induced Incandescence (LII) at 1064 nm and Laser-Induced Fluorescence (LIF) at 532 nm. Significant reductions of the concentrations of soot and soot precursors have been observed when adding ethanol to gasoline. A similar behaviour has been obtained with a gasoline–surrogate which has been found to reproduce well the sooting propensity of the unleaded gasoline used in this work. The analysis of the correlation existing between the peak soot volume fraction measured in flames and the Threshold Soot Index (TSI) of the different mixtures tested in this work revealed that the effect of ethanol was not only a dilution one but that the oxygen contained in the alcohol also influence the soot formation. Finally, the comparison of the LII fluence curves and time decays obtained in gasoline/ethanol mixtures showed that soot particles oxidized faster when ethanol is added to the base fuel.     

Properties of Brazilian gasoline mixed with hydrated ethanol for flex-fuel technology

In the present work, samples of Brazilian gasoline type C previously mixed with hydrated ethanol at concentrations of 20, 40, 60 and 80 vol.% were analyzed by distillation, octane number, specific mass, pH and conductivity, in order to evaluate the physico-chemical properties for a better comprehension of the effects caused by the flex-fuel technology. The obtained results were compared with the specifications of the ANP – Agência Nacional de Petróleo Gás Natural e Biocombustíveis – that is the federal regulatory agency for monitoring of the quality of fuels in Brazil. It was observed that there exists an ideal concentration of hydrated ethanol for addition in gasoline type C in order to obtain good properties for application in the flex-fuel technology.     

A simple impedance method for determining ethanol and regular gasoline mixtures mass contents

A simple electric impedance sensor embedded in ethanol and regular gasoline blends for determining mass ratios was built and tested in the present work. It was carried out a quantitative evaluation of mixtures for several fuel mass ratios in the temperature range of −10 to 40 °C. A non-linear dimensionless electrical conductivity-fuel mass ratio correlation was obtained for a 0-100% ethanol mass content in gasoline. Tests at different temperatures showed that the temperature had an important influence over the mixture bulk conductivity and sensor signal. This work was carried out following the Brazilian automotive industry trend of using ethanol-gasoline mixtures at any proportion to power passenger automobile engines.     

Adulteration detection of Brazilian gasoline samples by statistical analysis

Unfortunately, addition of organic solvents (heavy aliphatic, light aliphatic and aromatic hydrocarbons) in Brazilian gasoline is very frequent, and this illegal practice does not guarantee gasoline quality. Organic solvent adulterations of gasoline samples have been investigated. For characterization and comparison of these samples, physico-chemical parameters together with gas chromatographic analyses data were proposed as the factors for multivariate analysis. Hierarchical clusters analysis was used to improve the detection of the type of solvent and their relative proportion used for this practice. More detailed information of their compositions was revealed. It was found that using physico-chemical properties of gasoline samples together with statistical analysis are a useful method to adulteration detection.     

车用乙醇汽油添加清净剂影响试验

车用乙醇汽油加入清净剂可以清除发动机进气系统沉积物,起到节能环保的作用.选用车用乙醇汽油和车用乙醇汽油清净剂,进行添加和未添加清净剂理化性能对比试验,空白样和加剂样分别贮存15、30、45、60d.试验结果表明,车用乙醇汽油加入清净剂对各项指标无影响,其清净性效果表现明显,加清净剂车用乙醇汽油不宜贮存时间太长.建议车用乙醇汽油添加清净剂环节应尽量靠近使用环节,尽可能减少贮存时间.     

The performance of solid phosphoric acid catalysts and macroporous sulfonic resins on gasoline alkylation desulfurization

Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353-413 K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds.     

Aging effects on gasoline-ethanol blend properties and composition

Blends of 75% gasoline and 25% ethanol (E25) are unique fuels used in Brazil. The natural E25 oxidation process due to aging under atmospheric conditions has been investigated. To evaluate aging effects on the properties of commercially available fuel blends, two samples of regular E25, one sample of regular E25 with additives, and one sample of high octane E25 were tested. The samples were analyzed as new and in aging periods of 30 and 180 days. Fuel density, distillation temperatures T₁₀, T₅₀ and T₉₀, motor and research octane number, as well as concentrations of ethanol, oxygen, olefins, total aromatics, benzene and saturates were evaluated. It was observed an increase of fuel density, distillation temperatures, aromatics and oxygen concentration, and a decrease of the concentration of olefins with aging. The results indicate that the use of aged fuel in automotive engines may increase fuel consumption, carbon deposits formation, carbon monoxide and hydrocarbon emissions.     

Fuel grade ethanol by diffusion distillation: an experimental study

BACKGROUND: Fuel grade ethanol (anhydrous ethanol) is considered to be an excellent alternative clean burning fuel to gasoline. It is now used as an additive to gasoline to enhance its octane number and combustibility. Owing to its high energy values, ethanol is the most promising future biofuel. Because of azeotrope formation, anhydrous ethanol cannot be achieved by conventional distillation. Diffusion distillation is one of the several processes that can be used to separate azeotropes. Diffusion distillation takes advantage of differences in relative rates of diffusion using inert gas as selective filter. RESULTS: Effect of vaporization temperature and feed composition on diffusion distillation of an ethanol–water mixture using air as the inert gas has been studied. A new quantity S_az(N₂/N₁) has been suggested to find the optimum vaporization temperature. In the present study this was found to be about 46 °C. The pseudo‐azeotrope has been observed at 0.697 mole fraction of ethanol at a vaporization temperature of 50 °C. Separation is effected by diffusion distillation even at the azeotropic ethanol mole fraction of 0.894. The experimental results were compared with a Stefan–Maxwell equations based mathematical model and found to be in good agreement with theoretical results. CONCLUSIONS: Experimental results demonstrate that fuel grade ethanol can be produced by diffusion distillation. The new quantity S_az(N₂/N₁) is a key variable for vaporization temperature optimization. Copyright © 2011 Society of Chemical Industry     

A predictive thermodynamic model for the Brazilian gasoline

In Brazil, as in many other countries, the fuel quality control is made according to standard assays, which depend on some of the fuel properties, such as specific gravity, Reid vapor pressure and distillation curve. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. In Brazil, 25% (v/v) of anhydrous ethanol is added to the mixture of hydrocarbons that is usually called gasoline, according to the local regulations. In this work, the composition of the gasoline was obtained by gas chromatography as a small series of pseudo-components. Given the gasoline composition, its volatility properties and specific gravity were calculated using the Peng-Robinson equation of state with the Fisher-Gmehling mixing rule. The model provided excellent predictions for specific gravity, Reid vapor pressure and most of the distillation curve. However, important deviations are observed at the end of the distillation curve (90+%). These deviations are due to chemical alterations of the fuel caused by the high temperatures occurring at the end of the distillation curve. The model, as proposed, is efficient to forecast the fuel properties; as a consequence, it can be applied as a tool in the study of gasoline formulations and as an alternative tool in quality control.     

A molecular thermodynamic model for temperature- and solvent-sensitive hydrogels,application to the swelling behavior of PNIPAm hydrogels in ethanol/water mixtures

The swelling curves of poly-N-isopropylacrylamide (PNIPAm) hydrogels in ethanol/water mixtures were determined. A molecular thermodynamic model for swelling behavior of temperature- and solvent-sensitive hydrogels in solvent mixtures was developed by integrating a modified multiple lattice model developed previously for the mixing term and the Flory's Gaussian chain model for the elastic term. Three energy parameters and one volume parameter are included in this model for gel/solvent mixtures systems. Three of the four parameters can be determined from the swelling behavior of hydrogels in pure solvents. The energy parameter measuring the interaction between the two solvents is adjustable and expressed as a quadratic form of the inverse temperature. The calculated results for the swelling curves of PNIPAm hydrogels in ethanol/water mixtures at different temperatures are in good agreement with the experiments. In addition, the equilibrium concentrations of solvent mixtures inside and outside hydrogels can be predicted by this model, which is important for the application of hydrogels.     

催化裂化汽油脱硫技术进展

随着环保法规的日益严格,对汽油的质量要求越来越高,全世界都在为降低汽油硫含量而不懈努力。降低汽油硫含量是改善空气质量的有效手段。脱硫技术已经成为各炼油企业的关键技术。汽油中的硫化合物主要来自FCC(流化催化裂化)汽油,因此FCC汽油脱硫技术的研究与开发具有重要意义。目前,减少FCC汽油硫含量的技术主要有：FCC原料油加氢脱硫、FCC汽油加氢脱硫、溶剂萃取脱硫、催化裂化脱硫、氧化脱硫、生物脱硫和吸附脱硫等。笔者综述了国内外FCC汽油脱硫技术进展。     

萃取蒸馏脱除油品中硫的过程模拟与优化

汽车尾气严重污染环境,为了生产满足环保法规的硫含量低于10μg/g的汽油,提出了在传统的萃取蒸馏中以有机溶剂+离子液体（IL）为复合萃取剂的脱硫法。以与真实催化裂化（FCC）汽油组成及物性相近的模型油为模拟汽油,利用COSMO-RS模型计算了30种常见IL对环己烷-噻吩的选择性和溶解能力,筛选出用于萃取蒸馏脱硫添加剂的最佳离子液体为[EMIM][BF₄]。通过Aspen Plus软件以N-甲酰吗啉（NFM）+[EMIM][BF₄]为复合萃取剂进行了汽油脱硫的工艺流程模拟与优化。优化结果为萃取剂由NFM（质量分数98%）和[EMIM][BF₄]（质量分数2%）构成,萃取蒸馏塔质量回流比R=0.4,剂油质量比S/F=1,采出率为70%。模拟结果表明：萃取蒸馏可高效地脱除苯并噻吩、硫醚及噻吩类硫化物,上述硫化物总量可从1581μg/g降低至5.37μg/g,脱硫率达98.1%,质量收率为70%,体积收率为75%。此外,通过对比计算值与文献中实验值,验证了COSMO-RS预测IL热力学性质、UNIFAC预测有机硫化物-烃类汽液相平衡的准确性和模拟工艺流程的可靠性。     

间歇萃取精馏技术的研究进展

对间歇萃取精馏分离技术和进展进行了评述,主要从萃取精馏的溶剂选择与设计、模拟及优化、操作参数对分离过程影响及萃取精馏塔设备等几个方面,介绍了国内外关于间歇萃取精馏新兴分离技术的最新研究动态,最后指出了萃取精馏技术目前存在的问题和今后发展的方向。     

车用乙醇汽油挥发性研究

分析了车用乙醇汽油中影响挥发性的组分,介绍了变性燃料乙醇对汽油挥发性及车用乙醇汽油挥发性对汽车运行和环境的影响。通过对车用乙醇汽油族组成、蒸汽压和蒸馏特性的解析,明确了催化裂化汽油、催化重整汽油、烷基化汽油、异构化汽油、直馏汽油及含氧化合物等的调合作用。车用乙醇汽油挥发性的增大使汽车的启动性能增强、驱动性能变差、发生光化学污染的可能性变大。针对环保方面提出了车用乙醇汽油调合组分偏重一些,少加或不加其他含氧化合物,增加高辛烷值调合组分调合量的建议。     

Quality control of gasoline by H NMR: Aromatics, olefinics, paraffinics, and oxygenated and benzene contents

A simple and fast ¹H NMR method, without any pretreatment, was developed for quality control of gasoline. It is based on the average group molecular weight approach and relative-content concept involving aromatics, olefinics and paraffinics, including also ethanol and benzene contents. The ethanol content was evaluated for Brazilian samples, but the method can be easily adapted to any oxygenated compound (ex. MTBE), and to gasoline from other countries. Twenty two laboratory prepared gasoline samples (gasoline from Brazilian refineries plus hydrocarbon solvents) and thirty four real (i.e., Brazilian gas stations) gasoline samples were tested. The routine quality control carried out through the usual physicochemical analyses reached a level of confidence of 75% and 73% in detecting non conformity in laboratory and real gasoline samples, respectively. The NMR method was very superior reaching 100% and 97% of confidence, respectively. It was better suited for laboratories with high sample throughput since measurement time is short and only one NMR experiment is needed per sample.     

A review on removal of sulfur components from gasoline by pervaporation

Desulfurization of gasoline has gained growing importance because of tighter limits of less than 10 ppm sulfur in gasoline in recent regulations. On the other hand, preserving octane rating in gasoline is the most concern subject of the manufacturers. This review focuses on the desulfurization of gasoline by means of pervaporation (PV) process. The process as a new technology has drawn increasing attention and provided an efficient approach for eco-friend sulfur removal in petrochemical industries due to its high selectivity, feasible economics, and safety. Theoretical aspects in selection of materials for the applied membranes and their modifications are investigated. The various parameters including the type and concentrations of sulfur and hydrocarbon species, feed temperature, feed flow rate, and permeate pressure, which influence the performance of PV are discussed.     

乙醇-水-离子液体三元体系的气液平衡测定及其萃取精馏试验

在101.32 kPa下,用改进的Othmer釜测定了乙醇-水-1,3-二甲基咪唑磷酸二甲酯盐([MMIM]+[DMP]-)物系等压气液平衡数据。实验结果表明,加入[MMIM]+[DMP]-使气液平衡线偏离乙醇-水二组分物系的气液平衡线,[MMIM]+[DMP]-含量越高,偏离程度越大;[MMIM]+[DMP]-表现出盐效应,使乙醇对水的挥发度发生改变,消除了乙醇-水物系的共沸点;并以[MMIM]+[DMP]-作为乙醇-水物系萃取精馏的溶剂,进行了萃取精馏的小型工艺试验,结果塔顶乙醇质量分数达到99.5%,能够满足工业要求。