KINETIC STUDY ON DECOMPOSITION OF THE RESIDUE OBTAINED FROM DISTILLATION OF GASOLINE MIXED WITH ETHANOL FOR FLEX-FUEL TECHNOLOGY IN BRAZIL

Abstract

This work is a kinetic study of the degradation of the final residue obtained from distillation of gasoline mixed with hydrated ethanol. To obtain a flex-fuel, gasoline was mixed with distinct fractions of 20; 40; 60; and 80% volume of ethanol, and the samples were named as: G80:A20; G60:A40; G40:A60; and G20:A80, respectively. The samples were characterized by distillation, specific mass, density, pH, and conductivity. The distillation was carried out according the ASTM D86. At the end of the distillation, the residues of the samples were recovered and subsequently analyzed by thermogravimetry with the temperature ranging from 30 to 400 °C, at heating rates of 5; 10; and 20 °C min-1, under synthetic air atmosphere. From TG and DTG curves, it was verified that the total decomposition of the residues occurred in the range of 80-180 °C. The maximum temperature for thermal degradation of the samples increased with the concentration of ethanol in the mixtures. Applying the Ozawa-Flynn-Wall kinetic model, samples with high concentration of alcohol presented high activation energy for the thermal degradation of the distillation residue. With values ranging from 140 to 173 kJ mol-1, the abovementioned samples proved to be steadier, if compared to the ones with an excessive use of oxygenated solvents to the gasoline.