Oxidation characteristics of ethanol in the temperature range 200 to 1000 o C suitable to its use in automobiles are studied to highlight the role and optimum values of different combustion controlling parameters for its clean combustion. Sensitivity evaluation of different reaction paths has concluded some important reactions responsible for the ethanol oxidation. It is observed that clean combustion of ethanol can be obtained with a proper combination of combustion parameters viz.,

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... , C 2 H 5 OH/O 2 mole ratio and residence time. IPC Code: C07B 33/00 Ethanol is a high-octane fuel with high oxygen content (35% oxygen by weight) and when blended properly in gasoline produces a cleaner and more complete combustion. Recently the interest 1-7 in ethanol as a fuel extender, octane enhancer, oxygenate, and a neat fuel has increased dramatically because of the environmental concerns associated with conventional transportation fuels. Currently, ethanol and methyl tetra-butyl ether (MTBE) are the two oxygenated fuels most widely used in a number of developed countries. However, ethanol appears to be an attractive oxygenate over MTBE as it is produced from biomass; which is a renewable fuel and has roughly double the oxygen content than MTBE on an oxygen to carbon basis. Ethanol advocates 1-7 base their arguments for promoting the use of this fuel on three main issues: air quality, energy security, and farm income. Ethanol is a quality fuel alternative (anti-knock) rating when blended with gasoline. It improves combustion and keeps fuel systems clean. Ethanol combustion can also contribute towards the control of global warming. As for ethanol and NOx, while there is some difference of opinion, it appears that combustion of ethanol does produce more tailpipe emissions of NOx than gasoline, because the ethanol blend can be burned as a leaner (i.e., with low fuel/air ratio) mixture, resulting in higher combustion temperatures than with gasoline. With regulations on pollutant emissions becoming strict, the amount of oxygenated fuel like ethanol in gasoline needs to be increased. Therefore, a full understanding of the reaction pathways of oxidation of ethanol and of the pollutant species that may be produced during its combustion is needed. This understanding will allow industry and regulatory agencies to better evaluate the feasibility and relationship between the combustion process and pollutant emissions when using ethanol. Reaction pathway and sensitivity analysis are used to help identify those reactions and accompanying rate constants that exhibit a strong influence on the ethanol oxidation process. The presently considered temperature range (200-1000 o C) is drawn from the literature 1-4 representing the homogeneous gaseous phase as well as catalytic oxidation of ethanol at low temperatures. The oxidation kinetics of ethanol in this temperature range are investigated in order to highlight the product composition characteristics under different operating conditions such as temperature, fuel/oxygen mole ratio and residence time. Sensitivity evaluation of the chemical reactions involved in the oxidation of ethanol and the reaction involved in the formation of other important combustion species is also carried out to highlight the possible reaction paths for ethanol oxidation.