Specific consumption of liquid biofuels in gasoline fuelled engines

Oxygenated fuels increase fuel consumption due to their low enthalpy of combustion; however, their high antiknock index renders them suitable for use in engines with a high compression rate, increasing their thermal yield. This study evaluated the performance of biorenewable oxygenated fuels (ethanol and isoamyl alcohol) and partially renewable fuels (ETBE: ethyl tert-butyl ether, TAEE: tert-amyl ethyl ether and di-TAE: di-tert-amyl ether) with high degree of purity and in mixtures with automotive gasoline, based on tests with Otto cycle engines. Among the oxygenated fuels evaluated here, di-TAE was found to present the best characteristics of performance, both individually and in mixtures with gasoline.     

Effect of ethers and ether/ethanol additives on the physicochemical properties of diesel fuel and on engine tests

This study evaluates the effect of ether additives (ETBE and TAEE) in diesel and of ether/ethanol/diesel blends on the properties of density, volatility, viscosity, characteristics at cold temperatures, cetane number and performance in engine tests. The formulations were carried out with 5, 10 and 20% v/v of ethyl ter-butyl ether (ETBE) and ter-amyl ethyl ether (TAEE) and with 5, 10 and 20% v/v of ether/ethanol blends (50/50% v/v) starting from a base diesel. The formulations containing up to 5% v/v of TAEE displayed satisfactory results in the evaluation of physicochemical properties and greater efficiency in the engine tests. The results indicate that the ETBE and TAEE ethers act as cosolvents of ethanol in diesel. The presence of ethanol and ETBE significantly alter the characteristics of volatility (flashpoint and distillation curve) and reduce the cetane number, impairing the fuel's performance in engine tests.     

Oxygenate fuels: Market expansion and catalytic aspect of synthesis

Periodical oil crises, environmental issues, and energy consumption optimisation brought oxygenated compounds into consideration as fuel additives with the role of enhancer and/or octane booster. Their progressive introduction into the fuel market is examined in the light of technical and legislative motivation. Their different roles played in the fuel formulation are recognised and their past, present and future importance is discussed here. Light alcohols and ethers offer different and specific advantages in meeting the clean fuel requirements. Methyl tert-butyl ether (MTBE) has been the preferred product up to now; positive future perspectives can be envisaged for the less volatile ethyl tert-butyl ether (ETBE) and methyl-tert amyl ether (TAME). A schematic oxygenate production pattern is reported allowing to clarify the complex integration of oxygenate manufacture with, natural gas, refinery and petrochemical. The main reactions involved are outlined. Alcohol addition to tertiary olefins appears to be a focal point in oxygenated production leading to alkyl tert-alkyl ethers (MTBE, ETBE, TAME). The industrial production of ethers started in 1972 in Italy and grew impressively: from 50,000 tons/year to about 30 million tons/year actually. Parallel to the industrial development fundamental studies were done to clarify the mechanism of reaction, the role and criteria of choice of catalysts. This review covers the thermodynamic, kinetic and catalytic aspects of the reaction. The results available in the literature are referred, compared and discussed.     

Etherification on Zeolites: MTBE synthesis

Although the use of methyl-tert butyl ether (MTBE) in reformulated gasoline has raised concerns due to its detection in ground water and has led to its gradual phase out in parts of the United States, the use of heavier ethers in gasoline in the future is possible. The synthesis of MTBE provides us with an insight into etherification reactions in general. This article reviews the extensive findings over the past 15 years on the application of acidic zeolites as alternative catalysts for etherification reactions and, in particular, MTBE synthesis, and compares the results with those of the commercially used ion-exchange resins. Although the resin catalysts are very active, they have some significant drawbacks (i.e., thermal fragility, sensitivity to methanol/isobutene ratios, and corrosive/disposal problems). Zeolites have been considered to be potential alternative catalysts for MTBE synthesis due to their excellent properties such as high thermal stability and modifiable acidity. The impact of various zeolite parameters, such as Si/Al ratio, type of zeolite, and the presence of extra-lattice Al, on activity is explored. Although the specific activities of most zeolites have been found to be too low to compete at low temperatures required to avoid thermodynamic limitations, H-beta zeolite has been found to be as active as the current commercial resin catalysts being used for MTBE synthesis. In addition, all zeolites studied have been found to have high selectivities to MTBE and low sensitivities to methanol/isobutene molar ratio, permitting the use of the stoichiometric reactant ratio. Application of zeolites for the synthesis of higher ethers is suggested.     

Etherification on Zeolites: MTBE synthesis

Although the use of methyl-tert butyl ether (MTBE) in reformulated gasoline has raised concerns due to its detection in ground water and has led to its gradual phase out in parts of the United States, the use of heavier ethers in gasoline in the future is possible. The synthesis of MTBE provides us with an insight into etherification reactions in general. This article reviews the extensive findings over the past 15 years on the application of acidic zeolites as alternative catalysts for etherification reactions and, in particular, MTBE synthesis, and compares the results with those of the commercially used ion-exchange resins. Although the resin catalysts are very active, they have some significant drawbacks (i.e., thermal fragility, sensitivity to methanol/isobutene ratios, and corrosive/disposal problems). Zeolites have been considered to be potential alternative catalysts for MTBE synthesis due to their excellent properties such as high thermal stability and modifiable acidity. The impact of various zeolite parameters, such as Si/Al ratio, type of zeolite, and the presence of extra-lattice Al, on activity is explored. Although the specific activities of most zeolites have been found to be too low to compete at low temperatures required to avoid thermodynamic limitations, H-beta zeolite has been found to be as active as the current commercial resin catalysts being used for MTBE synthesis. In addition, all zeolites studied have been found to have high selectivities to MTBE and low sensitivities to methanol/isobutene molar ratio, permitting the use of the stoichiometric reactant ratio. Application of zeolites for the synthesis of higher ethers is suggested.     

Integral process for obtaining acetins from crude glycerol and their effect on the octane index

Abstract

The improvement of the combustion process in gasoline spark engines has been a painstaking task focused on developing chemical compounds. These ones have to be capable of bettering the engine performance and meeting standards set by environmental and health regulations aimed at reducing the emission of hazardous pollutants. Among the molecules synthesized for reaching these goals, oxygenating agents have been used to increase the octane number and make more efficient the combustion reaction by reducing the emissions of CO, polyaromatic hydrocarbons (PAHs), and particulate matter. As a result of this quest, MTBE has been used as a solution, but in recent years, negative effects of its use polluting water bodies and, as a consequence, the human health, have proven the opposite. For this reason, alternative oxygenating compounds to MTBE such as alcohols, ethers, and esters are being studied. According to the aforementioned, in the present paper, alternative oxygenating agents belonging to glycerol acetates (GAs) were synthesized from crude glycerol (CG) obtained as a biodiesel by-product and conditioned as starting material to perform esterification reactions with acetic acid or acetic anhydride. In order to assess the performance of these compounds as octane index enhancers, measurements using the same composition of ethanol, MTBE and the as-obtained GAs, in reference gasoline, were made, yielding comparable results that encourage the potential use of acetins as a replacement of MTBE.     

Investigations on surrogate fuels for high-octane oxygenated gasolines

Gasoline is a complex mixture that possesses a quasi-continuous spectrum of hydrocarbon constituents. Surrogate fuels that decrease the chemical and/or physical complexity of gasoline are used to enhance the understanding of fundamental processes involved in internal combustion engines (ICEs). Computational tools are largely used in ICE development and in performance optimization; however, it is not possible to model full gasoline in kinetic studies because the interactions among the chemical constituents are not fully understood and the kinetics of all gasoline components are not known. Modeling full gasoline with computer simulations is also cost prohibitive. Thus, surrogate mixtures are studied to produce improved models that represent fuel combustion in practical devices such as homogeneous charge compression ignition (HCCI) and spark ignition (SI) engines. Simplified mixtures that represent gasoline performance in commercial engines can be used in investigations on the behavior of fuel components, as well as in fuel development studies. In this study, experimental design was used to investigate surrogate fuels. To this end, SI engine dynamometer tests were conducted, and the performance of a high-octane, oxygenated gasoline was reproduced. This study revealed that mixtures of iso-octane, toluene, n-heptane and ethanol could be used as surrogate fuels for oxygenated gasolines. These mixtures can be used to investigate the effect of individual components on fuel properties and commercial engines performance.     

我国MTBE的生产使用现状及趋势分析

对我国MTBE的生产工艺及下游产品进行了详细的分析,重点分析了影响MTBE产品生产使用的各方面因素,从能源方针、车用燃料政策及环保要求等角度对我国MTBE产品的未来发展趋势进行了预测分析。结果显示,2020年以后我国汽油调和用MTBE的生产使用量将逐步降低,但此过程可能会较为平缓。     

Calculation of mass emissions, oxygen mass fraction and thermal capacity of the inducted charge in SI and diesel engines from exhaust and intake gas analysis

New computational procedures are proposed for experimentally evaluating air-fuel ratio and mass fractions of exhaust emissions as well as EGR rate, oxygen mass fraction and thermal capacity of the inducted charge in IC engines running with diesel oil, gasoline or any alternative liquid or gaseous fuel, such as LPG or CNG. Starting from the chemical reaction of fuel with air, from gaseous and smoke level measurements in the raw gases, the procedures calculate the volume fractions of oxygen in the combustion air and of compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The methods also take the effects of various fuel and combustion air compositions into account, as well as to the presence of water vapor, CO₂, Ar and He in the combustion air.The algorithms are applied to four different automotive engines under wide ranges of steady-state operating conditions: three turbocharged diesel engines featuring high-pressure cooled EGR systems, and an SI naturally aspirated bi-fuel engine running on either gasoline or CNG. The computed air-fuel ratios are compared to those obtained from directly measured air and fuel mass-flow rates as well as from more conventional UEGO sensor data. The mass emissions are worked out in terms of both brake specific mass emissions and emission indexes of each pollutant species, and the results are compared to those obtained by applying SAE and ISO recommended practices. The computed oxygen mass fraction of the inducted charge was then compared to that derived from direct measurement of O₂ concentration in inlet manifold. Finally, the sensitivity of results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NO_x formation) and the experimental uncertainties are determined.     

高辛烷值汽油添加剂的研究现状及进展

本文主要介绍了锰系、醚系、酯系和酸酯类抗爆剂及其他新型抗爆剂的研究状况及应用情况,指出我国虽已研发了一系列高辛烷值汽油添加剂,但工业化的较少,今后寻求高辛烷值汽油添加剂的多样化,开发新一代MTBE替代品以满足日益严格的绿色环保清洁燃料的要求是高辛烷值汽油添加剂的发展趋势。     

Methyl Ethyl Ketone Production through an Intensified Process

Methyl ethyl ketone (MEK) is widely used in the industry and is mainly produced from petroleum. Some works have projected MEK as a possible fuel since its performance in spark engines has overcome the performance of gasoline in certain indexes. Two intensified alternatives to produce MEK are introduced here, consisting of a reactive distillation column, an extractive distillation column, and three conventional distillation columns. The direct alternative resulted as the most promising when it was evaluated based on energy consumption, greenhouse gas emissions, and an environmental index. The obtained energy consumption for MEK production was 11.62 MJ kg_MEK⁻¹ for the entire process. Moreover, those intensified alternatives showed better performance indexes in comparison with a conventional process.     

MTBE辛烷值测试法的探讨

MTBE作为调合生产高标号无铅汽油的重要的高辛烷值组分油，准确测试其辛烷值在汽油调和生产中具有重要的意义。初步探讨了MTBE研究法辛烷值的测试方法，尝试了用甲苯标准燃料做参比燃料直接测定其净辛烷值，同时也测定了MTBE的混配辛烷值，通过MTBE辛烷值的测试，了解了MTBE的调和效应，确认了在石油二厂无铅汽油调和生产中对催化汽油的MTBE的真实辛烷值约为108／RON，指导了车用无铅汽油的调和生产。     

Determination of oxygenates in gasoline by FTIR

Oxygenates of the type C₁ to C₄ alcohols and MTBE have been used for improving the octane number of gasoline and helping in reduction of emissions. These oxygenates are used as substitutes for the poisonous tetraethyl lead. The ASTM D-4815 method utilizes a GC method for determining methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol (2-methyl-1-propanol), tert-butanol (2-methyl-2-propanol) and methyl tert-butyl ether (MTBE) in gasoline. However, since this method requires a variety of column switching and back-flushing systems, the possibility of using a simple and fast mid-IR transmission method for accomplishing the same task was pursued. For this, an instrument manufacturer's software that utilizes a partial least square (PLS) regression analysis in the region of importance for alcohols and ethers (1300 to 810 cm⁻¹) was chosen and successfully developed. A set of fuel blend samples (32) that contained concentrations in the range of 0.7 to 4.0 (wt/vol) of the components were used for calibration purposes. Results indicated that the correlation (R²) between the actual and predicted values of 70 laboratory prepared samples of concentrations in the range 0.7 to 8.1% (wt/vol) were 0.995, 0.995, 0.991, 0.992, 0.983, 0.995, 0.989, 0.984 and 0.996 for methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol and MTBE respectively.     

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.     

微生物降解甲基叔丁基醚及其关键酶的研究进展

为了减少机动车排放的CO和O3等污染气体,提高汽油的辛烷值,甲基叔丁基醚（MTBE）作为燃料氧化剂而广泛应用于汽油中。与此同时,由于MTBE具有很高的水溶性和难降解性,使用过程中的泄露带来了严重的污染问题。其自身的化学特性也给去除环境中的MTBE增添了很多困难。生物降解是土壤地下水修复中公认的有效又可以节省成本的方法。国外已经报道MTBE能在好氧或厌氧的条件下被微生物通过直接代谢或共代谢的方式而降解,国内在此方面的研究刚刚开始,尤其在降解机理方面的研究还存在很大的空白。本文对能够降解MTBE的微生物进行了总结,并且重点阐述了在MTBE降解过程中起作用的关键酶。     

甲基叔丁基醚的降解技术研究进展

随着汽油添加剂甲基叔丁基醚（MTBE）的普及使用和用量增加,其对环境和人体的危害受到了人们的普遍重视。主要介绍了MTBE在污染环境中的检测分析方法和降解技术研究进展,包括：物理吸附和曝气吹除、化学降解、生物降解和植物修复技术。分析了各种技术的原理及特点后指出,化学和生物降解MTBE可以将其对环境的危害降低到最低限度,是在修复由MTBE污染的环境时优先考虑的处理技术。     

甲醇燃料的研究进展与展望

随着化石资源的不断枯竭,能源消费将逐步向可再生能源时期发展.甲醇燃料不仅可以替代汽柴油作为内燃机燃料,而且也可以作为燃料电池等燃料或新型C1化工原料;不仅可以由化石能源生产,而且也可以由可再生能源生产:不仅具有高效、清洁燃料的特征,而且具有生产技术成熟、原料来源丰富的特点,能够实现可持续发展.甲醇燃料是理想的能源载体,在化石能源和可再生能源时期均可发展应用,特别是对于以煤为主要能源的中国,在由化石能源向可再生能源时期过渡的阶段,选择甲醇燃料为发展方向,意义将十分重大.     

Investigation on combustion and emissions of DME/gasoline mixtures in a spark-ignition engine

Dimethyl ether (DME) has a lot of good properties and is thought to be one of the best alternative fuels for IC engines in the future. In order to improve the efficiency, combustion stability and emissions performance of a spark-ignited (SI) gasoline engine at stoichiometric condition, an experimental study aiming at improving engine performance through DME addition was carried out on a four-cylinder SI engine. The engine was modified to be fueled with the mixture of gasoline and DME which were injected into the engine intake ports simultaneously. A hybrid electronic control unit (HECU) was dedicatedly developed to control the injection timings and durations of gasoline and DME. The spark timing was adjusted to reach the maximum brake torque (MBT) without knocking. Various DME fractions were selected to investigate the effect of DME addition on engine performance, thermal efficiency, combustion characteristics, cyclic variation and emissions under stoichiometric conditions. The experimental results showed that thermal efficiency, NOx and HC emissions are improved with the increase of DME addition level. The combustion performance was improved when DME addition fraction was less than 10%. CO emission first decreased and then increased with the increase of DME enrichment level at stoichiometric condition.     

碳五叔碳烯烃乙醇醚化研究进展

FCC轻汽油中的叔碳烯烃和乙醇醚化,不仅可以降低油品中的烯烃含量,而且可获得优良的汽油增辛剂乙基叔烷基醚。本文全面回顾了碳五（C₅）叔碳烯烃与乙醇醚化合成乙基叔戊基醚（TAEE）的研究进展,分析了所涉及的醚化、异构化、烯烃聚合以及水合等各类反应,并通过对反应体系的热力学分析,考察了各反应进行的难易程度。同时对醚化催化剂、反应机理及动力学等方面的研究成果进行了综合分析,并对今后该领域的发展方向进行了展望。     

Performance and exhaust emission characteristics of a spark ignition engine using ethanol and ethanol-reformed gas

Since ethanol is a renewable source of energy and has lower carbon dioxide (CO₂) emissions than gasoline, ethanol produced from biomass is expected to be used more frequently as an alternative fuel. It is recognized that for spark ignition (SI) engines, ethanol has the advantages of high octane and high combustion speed and the disadvantage of ignition difficulties at low temperatures. An additional disadvantage is that ethanol may cause extra wear and corrosion of electric fuel pumps. On-board hydrogen production out of ethanol is an alternative plan.Ethanol has been used in Brazil as a passenger vehicle fuel since 1979, and more than six million vehicles on US highways are flexible fuel vehicles (FFVs). These vehicles can operate on E85 - a blend of 85% ethanol and 15% gasoline.This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency and emissions. The combustion characteristics of hydrogen enriched gaseous fuel made from ethanol are also examined.Ethanol has excellent anti-knock qualities due to its high octane number and a high latent heat of evaporation, which makes the temperature of the intake manifold lower. In addition to the effect of latent heat of evaporation, the difference in combustion products compared with gasoline further decreases combustion temperature, thereby reducing cooling heat loss. Reductions in CO₂, nitrogen oxide (NOx), and total hydrocarbons (THC) combustion products for ethanol vs. gasoline are described.