Preparation and properties of diesel fuels from vegetable oils

Vegetable oils have heat contents approximately 90 % of that of diesel fuel and are alternative fuel candidates. A major obstacle deterring their use in the direct-injection diesel engine is their inherent high viscosities, which are nearly 10 times that of diesel fuel. Solution to the viscosity problem has been approached in at least four ways:(1) dilution, (2) microemulsification, (3) pyrolysis and (4) transesterification. Dilution procedures have been only partially successful in giving a fuel that passes the 200 h EMA test. Microemulsification is a relatively new approach and has yielded fuels that pass the 200 h EMA test. Pyrolysis gives fractions with compositions similar to No. 2 diesel fuel. Transesterification with methanol, ethanol or butanol produces alternative fuels which could be used in times of emergency.