Determination of the Chemical and Physical Stability of Middle Distillates with Various Alternative Components under Different Storage Conditions

Due to politically induced developments in the blending of alternative fuels such as esterified vegetable oils (fatty acid methyl ester/FAME) and increasingly purely paraffinic products such as hydrogenated vegetable oils (HVO) or synthetic fuels (XtL) to fuels derived from mineral oils, significant changes have occurred with regard to composition and product properties/storage stability. Iteractions of the admixing components within these long-term stored multi-component fuels (blends) are currently unknown. Some of the fuels are stored for up to 5 years in the end customer tank before they are technically used in the combustion process. When heating systems are renewed, the fuel oil burner systems are increasingly combined as back-up systems with log wood boilers or solar collectors with hot water storage tanks (fluctuating energy sources) (hybrid systems). Conventional fuel oil burner systems are approved up to a FAME content of maximum 10 %(V/V). Therefore, an increase in the proportion of alternative components is currently only conceivable by adding purely paraffinic components (HVO, XtL products). The assessment of the usability of multi-component fuels from XtL, FAME and EL fuel oil in fuel oil burner systems against the background of longer storage times in the future is absolutely necessary to ensure the availability and reliability of burner systems.

In the project, the ageing mechanisms and previously unknown chemical and physical phenomena during the storage of fuels with high paraffinic contents are to be investigated in detail. For this purpose, the very complex mixtures of fuels (fuel oil/FAME/XtL) and ageing products under different storage conditions are to be characterised at the molecular level by using high-resolution mass spectrometry. This improves the understanding of chemical ageing reactions, physical effects and the interaction of different fuels (fuel oil/FAME/XtL). The aim is to show the possible influences of the more complex fuel matrix on common analytical methods and to identify potential modifications. This enables the standard analysis to be used to evaluate the long-term stability behaviour of multi-component fuels from heating oil EL, FAME and paraffinic fuels (XtL). Furthermore, the identification of reactive molecules or groups of substances can be used to define potential lead components of ageing reactions. This plays a role in the product development of e.g. new additives and multi-component fuels as well as in the introduction of potential new analytical methods, which specifically examine for corresponding reactive groups of substances, whereby product ageing can be traced.

The project has been completed. The research report has been published.