Lawyer, K., Ickes, A., Wallner, T., Ertl, D. et al., "Blend Ratio Optimization of Fuels Containing Gasoline Blendstock, Ethanol, and Higher Alcohols (C3-C6): Part II - Blend Properties and Target Value Sensitivity," SAE Technical Paper 2013-01-1126, 2013, doi:10.4271/2013-01-1126.
Higher carbon number alcohols offer an opportunity to meet the Renewable Fuel Standard (RFS2) and improve the energy content, petroleum displacement, and/or knock resistance of gasoline-alcohol blends from traditional ethanol blends such as E10 while maintaining desired and regulated fuel properties. Part II of this paper builds upon the alcohol selection, fuel implementation scenarios, criteria target values, and property prediction methodologies detailed in Part I.For each scenario, optimization schemes include maximizing energy content, knock resistance, or petroleum displacement. Optimum blend composition is very sensitive to energy content, knock resistance, vapor pressure, and oxygen content criteria target values. Iso-propanol is favored in both scenarios' suitable blends because of its high RON value. A range of blends of ethanol, propanol, butanol, and pentanol with a gasoline blendstock can possess energy content, knock resistance, and/or petroleum displacement that exceed current gasoline-ethanol blends while meeting oxygen content and vapor pressure regulations.Results are similar whether examining blends with total alcohol content comparable to E10/E15 or alcohol content high enough to meet RFS2 requirements. Blends of higher alcohols with BOB can meet oxygen content, vapor pressure, and/or knock resistance requirements while increasing energy content and/or petroleum displacement. For example, if higher knock resistance is desired, a blend of iso-propanol and iso-butanol with BOB meets oxygen content, vapor pressure, and energy content requirements while increasing knock resistance and petroleum displacement as compared to E10.