Molecular design of ethanol/gasoline blends

T. M. SORIA; F. SANCHEZ; S. PEREDA; S. B. BOTTINI; E. A.BRIGNOLE

Miniapolis

Conferencia; AIChE Annual Meeting 2011; 2011

Bioethanol fuel blends play nowadays an important role in countries like Brazil and USA. Moreover, policies worldwide promote blending of fossil- and bio-fuels to meet sustainable targets. Ethanol has a high impact in the final fuel properties. The high non-ideality of mixtures containing ethanol and hydrocarbons strongly affects the phase behavior of the blend and consequently has an impact on its storage, transportation and use in engines. French and Malone[1] discussed the effect of adding ethanol to gasoline, in several properties: i) volatility (i.e. Reid vapor pressure, ASTM D-86 Distillation, vapor-liquid ratio, and evaporative emissions), ii) liquid split (e.g. water tolerance and enhanced solubility of aromatic fuel components in groundwater). Thus, the design of new biofuel blends requires tools able to predict final fuel properties. Gasoline is a multicomponent mixture of mainly four families of hydrocarbons: normal-, branched- and cyclic-alkanes, together with aromatic hydrocarbons. Group contribution models are the best option to calculate the properties of mixtures containing a large number of similar compounds. In this case the number of required interaction parameters is dramatically reduced when compared with molecular models. In previous works, phase behavior of the family of normal-[2], branched-[3], aromatic-[4] and cyclic[5] hydrocarbons in mixtures with water and alcohols were modeled with the group-contribution with association GCA-EoS equation of state. In the present work, this predictive tool is applied to the molecular design of naphtha/ethanol mixtures that present an adequate phase behavior to be use as fuel blends. References [1] R. French, P. Malone, Fluid Phase Equilibria (2005), 228-229, 27-40. [2] T.M. Soria, F.A. Sánchez, S. Pereda, S.B. Bottini, Fluid Phase Equilibria (2010), 296, 116-124. [3] T.M. Soria, A. Andreatta, S. Pereda, S.B. Bottini, Fluid Phase Equilib. 2011, 302, 1-9.