Determinação experimental de dados de pressão de vapor e de equilíbrio líquido-vapor de componentes do biodiesel através da calorimetria exploratória diferencial / Experimental determination of vapor pressure and vapor-liquid equilibrium data of components of biodiesel by differential

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Biodiesel is a biodegradable, renewable fuel with lower greenhouse gas emissions. It consists of the alkyl esters of fatty acids, obtained by the transesterification of fats and oils with a short chain alcohol such as methanol or ethanol. Ethyl esters resulting from transesterification with ethanol are poorly characterized. The thermophysical properties and phase equilibrium data involving the fatty acid ethyl esters are very important in the design, modeling, simulation, and the optimization of the production of biodiesel, are scarce in the literature. In this work was determined vapor pressure data of the esters ethyl laurate, ethyl myristate, ethyl palmitate, ethyl stearate, ethyl oleate and ethyl linoleate; and vapor-liquid equilibrium data of systems ethyl pamitate + ethyl stearate at 40 mmHg, ethyl palmitate + ethyl oleate at 40 and 70 mmHg and ethyl palmitate + ethyl linoleate ant 70 mmHg. For the experimental determination proposed the use of a non-conventional technique: differential scanning calorimetry (DSC). Samples of 2 to 5 mg were used in the analysis, with heating rate of 25 ?C/min. The samples were placed in hermetic aluminum crucibles with a small hole in the lid ("pinhole") of 0.25 mm diameter, which maintain a constant internal pressure. The technique of differential scanning calorimetry was shown to be appropriate to determining the vapor pressure of ethyl esters. This technique showed advantages over conventional techniques: the use of a small sample size and shorter analysis time. The vapor-liquid equilibrium data measured by DSC were satisfactory. This technique proved to be restricted and it is not suitable for determining the vapor-liquid equilibrium data of systems whose components have large difference in volatility

ASSUNTO(S)

biodiesel esters calorimetry calorimetria esteres equilíbrio líquido-vapor pressão de vapor biodiesel vapor-liquid equilibrium vapor pressure

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