Formation of vegetable oil based microemulsion biofuel with ethanol/butanol in palm oil/diesel blends

Abstract

Vegetable oil is an option for renewable fuels production to replace the diesel oils. Because vegetable oils have higher viscosity than diesel oils, the usability of neat vegetable oils can lead to engine stability problems such as poor atomization of the fuel. However, vegetable oil viscosity can be reduced by blending with diesel fuel in thermodynamically stable mixtures using micro emulsion formulation. This work focused on the formation of micro emulsion biofuels consisting of plam oil/diesel and refined bleached deodorized palm oil (RBDPO)/diesel blends as an oil phase with ethanol and butanol blend as a viscosity reducer. Methyl oleate (MO) and palm oil methyl ester (POME) were used as a surfactant and 1-octanol was used as a cosurfactant at 1:8 surfactant:cosurfactant molar ratio. This work studied the effects of surfactant structure, ethanol/butanol blending ratios, palm oil/diesel blending ratios on phase behaviour, kinematic viscosity, micro emulsion droplet size and fuel properties for micro emulsion fuel formation and compared their fuel properties to regular biodiesel (B100) and diesel (No.2). The result showed that the phase behaviors of different surfactant systems had similar trend of the miscibility curve. The micro emulsion biofuels containing butanol in the mixture showed a remarkable result on phase behavior. Based on our findings, the blending ratios of ethanol/butanol is a major parameter for optimizing the viscosity and other fuel properties of micro emulsion biofuels.