Wei Yanju

The Effects of Methanol Fraction on the Azeotropic Behaviors of Methanol/Gasoline Mixtures

Methanol is regarded as a potential alternative fuel for spark ignition (SI) engine. It is feasible for SI engines to run on methanol/gasoline mixtures. When methanol is mixed with gasoline, the physicochemical properties of the mixtures are changed different from the properties of both methanol and pure gasoline to some extent. This paper focused on the azeotropic behaviors of saturated vapor pressure (ps) and the distillation curves of methanol/gasoline mixtures. And compositions of the distillates were identified and quantified by a gas chromatography—mass spectrometry (GC–MS) under various Td. Experimental results show that the ps and distillation curves of methanol/gasoline mixtures showed strong positive deviation of Raoult’s law. The maximum deviation occurred around the Td of methanol’s boiling point, i.e., 64.5°C. Increasing the heavy hydrocarbon contents in gasoline could draw the Td of methanol/gasoline mixtures back to that of base gasoline. C4–C8 alkanes, olefins, and benzenes were the main components in distillates of gasoline and its methanol mixture. However, the additive with hetero atom of oxygen, methyl tertiary butyl ether (MTBE) was the leading component with the largest mass percentage in all the distillates, while methanol was another leading component in methanol mixture distillates. Methanol co-boiled with all of the gasoline components rather than with some certain ones; even so, pentane, 2-methyl-2-butene and toluene were the three leading azeotropes with the change ratio of over 4% in mass percentage.