Phase separation gasoline

Owing to this problem of phase separation, gasoline/ethanol blends should be not exposed to water during distribution or use in a vehicle. For this reason, they cannot be transported in pipelines, which sometimes contain water. This water sensitivity also means that extra care should be taken when gasoline/ethanol blends are used as a fuel for boat engines. 

In Germany in the early 1950s, a 50 50 mixture of methanol and 2-propanol was blended with gasoline, first at a level of 7.5% and later at 1.5% (79). Complaints about stalling, power loss, and phase separation caused the ratio to be changed to 60 40 methanol 2-propanol but this apparentiy aggravated... 

Isopropanol is a colorless liquid having a pleasant odor it is soluble in water. It is more soluble in hydrocarbon liquids than methanol or ethanol. For this reason, small amounts of isopropanol may be mixed with methanol-gasoline blends used as motor fuels to reduce phase-separation problems. ... 

Immiscible-phase separation Transformation Processes No Fluids (such as gasoline) that are immiscible in water are a significant consideration in near-surface contamination. Deep-well injection is limited to wastestreams that are soluble in water. Well blowout from gaseous carbon dioxide formation is an example of this process that is distinct to the deep-well environment. 

In gasoline-methanol mixtures containing 0.1% water i-propanol is added to the environment (medium) in order to decrease the phase separation temperature. Fuels containing different ratios of gasoline-methanol-i-propanol and water are also composed, which are proved to be stable in the climatic conditions. An increase in the aromatic character of the gasoline, a decrease in the water content of the mixtme, an increase in the amount of the additive used results in a decrease in the phase separation temperature of the mixture. In gasoline-ethanol mixtures the additive used is also i-propanol. In gasoline-alcohol mixtures various additives like i-propanol, n-butanol, i-butanol, and i-amylalcohol are used. 

The butanols and their methyl and ethyl ethers have several advantages as oxygenates over methanol and ethanol in gasoline blends. Their energy contents are closer to those of gasoline the compatibility and miscibility problems with petroleum fuels are nil excessive vapor pressure and volatility problems do not occur and they are water tolerant and can be transported in gasoline blends by pipeline without danger of phase separation due to moisture absorption. Fermentation processes (Weizmann process) have been developed for simultaneous production of 1-butanol, 2-propanol, acetone, and ethanol from... 

Whereas gasoline and water are almost entirely immiscible, and will readily separate into two phases, a gasoline-oxygenate blend is used to dissolve water without phase separation, hence the use of the term water tolerance. Gasoline-oxygenate blends will dissolve some water but will also separate into two phases when contacted with water that is beyond the threshold concentration. Such a phenomenon is a major issue for alcohol-containing blends. 

There is general agreement that methanol blends in gasoline will be a suitable way to improve the octane number.Methanol is facing serious overcapacity and is available at low cost(5-9) however,it needsa cosolvent in gasaline,mainly C -Cg alcohols, to avoid problems such as phase separation,high volatility ( 10-12 ). 

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