As part of the SynergyFuels project, TUM is developing synthesis routes for producing poly(oxymethylene)butyl ethers (OMBE), which can serve as renewable blending components for diesel fuels. In addition to basic fuel properties such as density and viscosity, the stability of these components is also decisive for their use in practice. The diesel fuel standards define minimum requirements for the parameter of oxidation stability. For novel fuel components such as OMBEs, however, it is unknown whether this test method is applicable and whether practical information on storage stability can be derived.
The RapidOxy can be used to determine oxidation stability in accordance with DIN EN 16091. The fuel sample is exposed to oxygen at a pressure of 700 kPa and a temperature of 140 °C in a measuring chamber. The chamber pressure is measured over time, which decreases when the oxygen is bound in oxidation reactions. Compared to other measurement methods for oxidation stability, the sample quantity, measurement duration, and effort required for the analysis are significantly lower, as the sample is oxidized at a higher temperature and in a simple setup.
Initial measurements at the Technology and Support Centre (TFZ) using OMBEs indicate that degradation reactions occur at the specified temperature of 140 °C that would not happen under normal fuel storage conditions. This is shown by analyses of samples from different aging processes, in which a significantly larger number of degradation products were detected for samples from the RapidOxy.
In order to investigate whether the method is suitable for assessing the oxidation stability of the novel fuels from the SynergyFuels project, the temperature and oxygen pressure in the sample chamber will be varied in future tests. The results will then be compared with other methods for measuring oxidation stability and a storage test.
