Technical Committee Automotive Fuels

Solubility Properties of Blends of Diesel Fuel and FAME

During the last years, certain incidents were observed with diesel fuels, such as deposit formation in storage tanks in connection with corrosion and filter clogging at service stations. The phenomena occurred at various parts of the logistic chain, and they differ regionally and from company to company. In this project, it was investigated, whether the composition of diesel fuels and FAME, the concentration and oxidation stability of the FAME, the addition of antioxidants and the storage stability had any impact on the solubility properties of FAME containing fuels. The project was carried out in three parts in the time period from 2007 to 2009. In each of the project parts, blends of different basis diesel fuels and FAME were tested in concentrations of 5 or 7 to 20 % (vlv) during a storage period of eight weeks. During storage, visual assessments of all mixtures in part 1, 2 and 3 showed clouding, sediments or deposits, which partly decreased or totally disappeared. In part 1 and 2, selected blends were tested at the end of the storage time for their content of steryl glycosides in the filter residues in addition to their filterability according to IP 387. In almost all of the filter residues of the blends, steryl glucosides could be detected qualitatively. In addition, oxidation stability according to DIN 51627-2 was checked before and after storage. No distinct trends could be detected. In part 3, storage temperature was varied at the beginning and end of the storage time of eight weeks, and filterability according to IP 387, oxidation stability according to DIN 51627-2 and ASTM D 7545 and water content according to DIN EN ISO 12937 were determined. Altogether, a correlation between the FBT results and the visual assessment could be established: A negative visual assessment is accompanied by a poor filterability. As a tendency, the results of the analytical methods for the determination of oxidation stability DIN 51627-2 and ASTM D 7545 show that the increase of the blending rate reduces the oxidation stability, and an increase of the storage temperature has a negative impact on the oxidation stability.