Complex materials as fuel oils are characterized by physical and chemical parameters. This paper deals with the determination of the activation energy of three kinds of Brazilian fuel oils. As it is possible to establish a direct relation between ignition delay and activation energy, these kinetic parameters can be used to characterize these oils regarding the combustion quality of the fuel. Activation energies were determined as a function of conversion degree (R) and temperature by model-free kinetics. The samples, here named A, B, and C, were supplied by Petrobras-Cenpes, and they were characterized by thermogravimetry (TG) and differential thermal analysis (DTA). Transient experiments were performed from room temperature up to 600 °C at five heating rates (2.5, 5.0, 10.0, 15.0, and 20.0 °C min -1 ) in an atmosphere of synthetic air and samples of about 20.0 mg were used. In all experiments, three distinct decomposition regions were observed and identified as lowtemperature oxidation (LTO), fuel deposition (FD), and high-temperature oxidation (HTO). In order to compare these oils, we considered the medium value of the activation energy obtained between conversions of 1% and 90% only for the LTO region. The results are as follows: sample A ) 43.8 kJ mol -1 , sample B ) 57.2 kJ mol -1 , and sample C ) 61.8 kJ mol -1 , showing that the sample A is the best option among the samples studied in this work and that the activation energy is a suitable parameter for this purpose.
Available online xxxKeywords: Ethanol dehydrogenation Fuel blend Hydrogen PEMFC Catalysis a b s t r a c t This study aims at analyzing the potential application of the liquid effluent coming from a catalytic ethanol dehydrogenation reactor as a fuel blend or additive for internal combustion engines, and also of the hydrogen produced, as fuel for a polymer electrolyte fuel cell (PEMFC). The liquid effluent is obtained by the catalytic reaction of ethanol over Cu/ ZrO 2 at different contact times of the reactant with the catalyst bed. Subsequently, highperformance liquid chromatography analysis and heat of combustion measurements are used to analyze the composition and the heat of combustion of the liquid effluent trapped by cold condensation at 271.65 K. In parallel, the effect of the presence of residual parts of the constituents of the liquid effluent in the H 2 stream on the operational characteristics of a PEMFC having a Pt/C anode and cathode is investigated. Results show that the liquid fuel blend obtained from ethanol dehydrogenation has a heat of combustion higher than that of ethanol, and it is essentially formed by un-reacted ethanol, acetaldehyde and ethyl acetate.Thermodynamic calculations evidence a good agreement with the liquid effluent composition and its respective combustion enthalpy. Polarization curves of a PEMFC supplied with hydrogen containing 1000 ppm of acetaldehyde and ethyl acetate evidence performances comparable to that of the same system when fed with pure hydrogen, while with ethanol significant loss of activity is observed.
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