Future Transportation Fuels Research Articles

Noble Metal-Free Hierarchical ZrY Zeolite Efficient for Hydrogenation of Biomass-Derived Levulinic Acid.

Developing a low-cost and robust catalyst for efficient transformation of biomass-derived platform chemicals plays a crucial role in the synthesis of future transportation fuels. Herein, a post-synthetic strategy was employed to develop a noble metal-free and robust ZrY zeolite catalyst, which is efficient for the hydrogenation of biomass-derived levulinic acid (LA) into biofuel γ-valerolactone (GVL), whereas over 95% yield of GVL was achieved in 10 h at 220°C. The effects of acidic properties from ZrY catalysts and various reaction parameters on the catalytic performance were then discussed in detail. Subsequently, different characterization tools were used to compare the difference and relationship of structure activity between the fresh and spent ZrY catalysts. It was found that acidity and the metal–support interaction were important for the direct synthesis of GVL. This work provides a guideline to design a noble metal-free catalyst for high-value utilization of biomass-derived sources.

Optimum Fuel for Spark Ignition Engines from Lignin Pyrolysis Oil

Lignin is a high-energy-content material, which could be used as feedstock for future transportation fuels. To this aim, it must be liquefied and upgraded. Currently, the most promising way of upgrading is considered to be hydrodeoxygenation. By combining an upgrading reaction pathway network and a model of a spark ignition internal combustion engine, the fuel properties are linked to the degree of upgrading. This study answers the question how much upgrading is required to obtain the optimum fuel for a spark ignition engine. Depending on the optimization criteria (efficiency, specific CO2 emissions, or volumetric fuel consumption), different selections of compounds are identified both for summer and all-year applications. Most of the compounds exhibit a significantly higher efficiency than gasoline at lower volumetric fuel consumption. Specific CO2 emissions are expected to be marginally reduced, compared to gasoline. Furthermore, this study confirms that the initial bio-oil is not suitable as fuel and reveals that complete hydrodeoxygenation is not beneficial.

Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on performance and emissions of internal combustion engines

Energy security is an important consideration for development of future transport fuels. Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen production centres established with large investments.Different electrode design and different electrolytes have been tested to find the best electrode design and electrolyte for higher amount of HHO production using same electric energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine without any structural changes. Later, previously developed commercially available dry cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel fuel + biodiesel mixtures with different volumetric flow rates are also used as pilot injection fuel in the test engine. The effects of HHO enrichment on engine performance and emissions in compression-ignition and spark-ignition engines have been examined in detail. It is found from the experiments that plate type reactor with NaOH produced more HHO gas with the same amount of catalyst and electric energy. All experimental results from Gasoline and Diesel Engines show that performance and exhaust emission values have improved with hydroxy gas addition to the fossil fuels except NOx exhaust emissions. The maximum average improvements in terms of performance and emissions of the gasoline and the diesel engine are both graphically and numerically expressed in results and discussions. The maximum average improvements obtained for brake power, brake torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively. Furthermore, maximum improvements in performance data obtained with the use of HHO enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake torque and 10% for BSFC.

Manifestation of octane rating, fuel sensitivity, and composition effects for gasoline surrogates under advanced compression ignition conditions

Substantial research effort has been spent on the development of advanced compression ignition (ACI) engine combustion strategies over the past decades, including homogeneous charge compression ignition (HCCI), reactivity controlled compression ignition (RCCI), and gasoline direct-injection compression-ignition (GDCI), etc. The behavior of gasoline-type fuels under compression ignition conditions has subsequently attracted extensive experimental and kinetic modeling interest. On the other hand, towards the development of future transportation fuels and engines, the evaluation of general fuel properties, instead of endless testing of specific fuels, should be the future research focus. In this study, the individual roles of the research and motor octane numbers (i.e., RON and MON) and fuel sensitivity (S) in characterizing the ignition performance of gasoline surrogates have been systematically investigated under a typical ACI engine condition using well-validated surrogate and kinetic models. The crank angle corresponding to 50% total heat release (CA50) was utilized as an indicator of the overall fuel reactivity, and iso-contours of CA50 were mapped out in the full engine operating domain characterized by the temperature and pressure at intake valve closing (IVC). By comparing the ignition performance of toluene primary reference fuel blends (TPRF) with the same RON, MON or S values, the distinctive effects and dominant ACI operating conditions of these fuel properties are clearly demonstrated. The role of equivalence ratio is also discussed by comparing the intrinsic stoichiometric condition of the standard octane rating tests and the lean mixture conditions required by ACI operation. The results show that octane sensitivity manifests itself in the high pressure low temperature operating regime for fuels with identical RON or MON, through different low temperature reactivities and heat release rates, while in low pressure high temperature conditions, combustion phasing is less sensitive to all fuel properties, including RON, MON and S. TPRFs with the same sensitivity show the largest variation of CA50 in the intermediate operating conditions, where the thermodynamic traces pass primarily through the ignition delay regime characterized by negative-temperature coefficient (NTC) behavior. Finally, by comparing the combustion phasing of five different gasoline surrogates with nearly identical RON and MON, potential compositional effects for gasoline fuels under ACI condition are further discussed via kinetic modeling. This study also demonstrates that the controlling fuel properties of gasoline-like fuels depend on ACI operating conditions (pressure and temperature trajectory), which should be carefully considered when constructing fuel metrics and comparing experimental results of ACI engines.

Developments in internal combustion engines and implications for combustion science and future transport fuels

Changes in engine technology, driven by the need to increase the efficiency of the SI engine and reduce NOx and soot from diesel engines, and in transport energy demand will have a profound effect on the properties, specifications and production of future fuels. The expected increase in global demand for transport energy is significantly skewed towards heavier fuels like jet fuel and diesel compared to gasoline. Abnormal combustion such as knock and preignition will become more likely as spark-ignition (SI) engines develop to become more efficient and fuel antiknock quality will become more important. In current and future SI engines, for a given RON (research octane number), a fuel of lower MON (motor octane number) has better antiknock quality. Current fuel specifications in several parts of the world assume that MON contributes to antiknock quality and will need to be revised as the mismatch with engine requirements widens. Diesel engines need to maintain efficiency while reducing emissions of soot and NOx. Soot and NOx can be controlled more easily if such engines are run on fuels of extremely low cetane. In the long term compression ignition engines could run on fuels which require less processing in the refinery compared to today’s fuels. Such an engine/fuel system could be significantly cheaper and also help mitigate the expected demand imbalance in favour of heavier fuels. The review concludes with a list of issues for combustion science that are relevant to this fuel and engine development.

WITHDRAWN: Developments in internal combustion engines and implications for combustion science and future transport fuels

WITHDRAWN: Developments in internal combustion engines and implications for combustion science and future transport fuels

Lactic acid as a platform chemical in the biobased economy: the role of chemocatalysis

Upcoming bio-refineries will be at the heart of the manufacture of future transportation fuels, chemicals and materials. A narrow number of platform molecules are envisioned to bridge nature's abundant polysaccharide feedstock to the production of added-value chemicals and intermediate building blocks. Such platform molecules are well-chosen to lie at the base of a large product assortment, while their formation should be straightforward from the refined biomass, practical and energy efficient, without unnecessary loss of carbon atoms. Lactic acid has been identified as one such high potential platform. Despite its established fermentation route, sustainability issues – like gypsum waste and cost factors due to multi-step purification and separation requirements – will arise as soon as the necessary orders of magnitude larger volumes are needed. Innovative production routes to lactic acid and its esters are therefore under development, converting sugars and glycerol in the presence of chemocatalysts. Moreover, catalysis is one of the fundamental routes to convert lactic acid into a range of useful chemicals in a platform approach. This contribution attempts a critical overview of all advances in the field of homogeneous and heterogeneous catalysis and recognises a great potential of some of these chemocatalytic approaches to produce and transform lactic acid as well as some other promising α-hydroxy acids.

European Expert Group reports on future transport fuels

The European Expert Group on Future Transport Fuels recently published its report on the future of fuels for transportation in the European Union. While this covered the range of alternative fuel options, from synthetic and biofuels to natural/biomethane and LPG, it also anticipates the increasing use of electricity and hydrogen in transportation out to 2050. This article extracts the report's analysis of hydrogen in fuel cell vehicles, within the overall context of EU policy development to 2050.

Present and Future Transportation Fuels

The alternate fuels are substitute fuel sources to petroleum. These fuels are important because they replace petroleum fuels; however, some still include a small amount of petroleum in the mixture. Almost all motor vehicles today are powered by either diesel or gasoline. Both fuels are mainly derived from petroleum. Diesel fuel consists of hydrocarbons with between 9 and 27 carbon atoms in a chain as well as a smaller amount of sulfur, nitrogen, oxygen, and metal compounds. There are four alternate fuels that can be relatively easily used in conventional diesel engines: vegetable oil, biodiesel, Fischer-Tropsch (F-T), and dimethyl ether (DME). Gasoline is a blend of hydrocarbons with some contaminants, including sulfur, nitrogen, oxygen, and certain metals. The four major constituent groups of gasoline are olefins, aromatics, paraffins, and napthenes. The main alternate fuels include alcohol, liquefied petroleum gas, compressed natural gas, hydrogen, and electricity for operation of gasoline-type vehicles. Blended with petrol at 10%, bioethanol can be used in vehicles without the need to change fuel or engine specifications.

Transport fuel for the post-oil era — a different view

In the March 1978 issue of Energy Policy, G. Charlesworth and T.M. Baker published an article on future transport fuels. Of the two principal alternatives to petroleum-based fuels — electricity and coal-derived liquids — the authors chose to devote primary attention to electricity and to the implications of a shift from heat engines to battery electric vehicles. The purpose of the article below is not to refute their findings, but to point out that their conclusions apply only to the UK and to countries with similar resource bases (such as other European countries and Japan). Changes in automotive engine design and in the fuels to power motor vehicles are likely to have a very different effect in countries such as the USA and Brazil. This paper addresses the outlook for motor fuels in the USA.