In the framework of a multistep program devoted to the ternary gasoil/alcohol/water system, the authors investigated the miscibility of anhydrous and hydrated ethanol qualities with four classes of industrial gasoil having different compositions and densities. To that end, they considered a pseudo binary system made by the various hydrocarbon species on one hand and the alcohol/water sub-system on another hand. Using the UNIQUAC thermodynamic theory and the Group Contribution approach, the team computed the Minimum Miscibility Temperature (“MMT”) for a series of the gasoil/ethanol/water system having water concentrations in ethanol comprised between 0 and 10%. The TMM is the temperature above which the various components of the system form a sole phase. This work is summarized in two papers already published (Part 1: GT 2010-22126; Part 2: GT2011-45896).
In the continuity of this prior work and considering the potential interest of alternative alcohols as “gasoil extenders”, the team has generalized this approach to selected C1-C4 alcohols: methanol, isopropanol (or 2-propanol) and n-butanol (or 1-butanol). While methanol is an interesting “energy vector” of coal and biomass via the CTL and BTL processes, isopropanol is a widespread commodity produced by the classical petrochemistry and 1-butanol is a promising biofuel candidate of the second, “lingo-cellulosic” generation.
This third part of the project shows that the introduction of these alternative alcohols and their respective interactions with water lead to considerable changes in the liquid-liquid equilibria and important shifts of the MMTs, trends that were difficult to anticipate beforehand.