Technologies for energetic exploitation of biodiesel chain derived glycerol: oxy-fuels production by catalytic conversion

The paper describes the results of a co-operative research project aimed at the energetic exploitation of the biodiesel derived glycerol. The research objective is the definition and validation of a synthesis process for conversion of glycerol in an oxygenated fuel additive (glycerol alkyl-ether) suitable for blending with diesel and biodiesel. The employed facilities, methodologies and first results from engine tests are described, including a preliminary Life Cycle Assessment (LCA). Etherification of glycerol with tert-butyl alcohol and isobutylene allowed to identify the suitable experimental conditions required to obtain a mixture predominantly composed of higher glycerol ethers (GEM). Novel catalysts, based on perfluorosulphonic ionomers as active species and spherical silica as support, were found to be stable and easy reusable allowing to obtain mixtures containing very low amount of monoethers and oligomers considered as undesired products. Engine tests with blends of GEM in diesel fuels revealed good combustion and emission performances when compared both to neat diesel fuel and a blend diesel/biodiesel. LCA analysis indicates that the GEM/diesel blend generates an environmental impact which is lower than the one of neat diesel.