A Study On The Phase Stability And Evaporation Of Methanol Gasoline Blends

In connection with technical problems about phase stability and vapor pressure of methanol gasoline system, the phase separate temperature of the methanol gasoline blends (M15, M30, M50, M65, M85) which was the different ratio of alcohol and oil was tested in the temperature range from-25.0℃to40.0℃. Effects of the different additives of methanol gasoline blends were studied. The cosolvent of n-alcohols which the number of carbon atoms of was from2to10, fusel oil, acetals(ketals), hydroxy carboxylic acid ester, dicarboxylic acid esters, natural fats and their derivatives were researched. The curve of additives’ dosage and phase separate temperature was drawn. The law which cosolvent had effect on phase stability of each system was investigated. The results show that:the nature of its own the blending agents (molecular species of the cosolvent, chain length, isomerization, etc.), content of the methanol, content of the water, content of the gasoline and many other effects impacted on the effects of the stability and the evaporation of the blending agents.In the low alcohol and oil ratio of methanol gasoline system, n-heptanol and n-hexanol showed good effects of phase stability, but more than seven carbon atoms of n-alcohol showed bad effects of phase stability. Fusel oil was less effective on phase stability of methanol gasoline system. The phase stability which the different acetals(ketals) products had effect on methanol gasoline system was variation:six-ring structure, a linear structure and the benzene ring structure of the acetals(ketals) compounds. In the same the amount of additives’dosage, the effects of the phase stability of glycolic ester was better than tartaric esters. The effects of the phase stability of malonic ester was better than adipic esters. In methanol gasoline system, natural fats derivatives showed good effects of phase stability. The phase separation temperature of M65system reached-24℃as the additives of on the phase stability of castor oil methyl ester which was13.3%for the dosage.The effect of its series of n-alcohol was little difference in the low alcohol and oil ratio of methanol gasoline system. The acetals(ketals) could significantly reduce the saturated vapor pressure of low alcohol and oil ratio of methanol gasoline system. The series of the acetals(ketals) compound were synthesized by the benzaldehyde with ethylene glycol, n-butanol and glycerol which could significantly reduce the saturated vapor pressure of low alcohol and oil ratio of methanol gasoline system. And the rate of the reduction of thesaturated vapor pressure was close. The rate of the reduction of the saturated vapor pressureof M15and M30system was15.6kPa and13.3kPa. The rate of the reduction of the saturatedvapor pressure of hydroxy carboxylic acid ester and dicarboxylic acid esters was much lowerthan the acetal(ketals). The amount of methyl glycolic was1%, the rate of the reduction ofsaturated vapor pressure of M15systems was43.8kPa. For the same methanol content ofmethanol gasoline system, with the increasing chain length of malonate and adipate, saturatedvapor pressure of methanol gasoline system reduced which the overall effect enhanced. Theamount of hepyl adipic was1.0%, the rate of the reduction of saturated vapor pressure ofM15systems was8.4kPa. Natural fats derivatives could significantly reduce the saturatedvapor pressure of methanol gasoline system. The saturated vapor pressure of methanolgasoline M30system could reach17.1kPa and19.9kPa. The amount of castor oil could becontrolled within0.2%,1.0%.