Nile Red as a Fluorescence Marker and Antioxidant for Regenerative Fuels

This article contributes to the ongoing dialogue regarding the future application of renewable e-fuels as part of a holistic solution to the energy crisis. In order to be able to continue using internal combustion engines in a sustainable manner, it must be ensured that these engines are operated exclusively with renewable, CO₂-neutral fuels. One way to achieve this is the use of a fluorescence sensor in the vehicle in combination with fuels that are labeled with a fluorescence marker. This study presents an investigation into the use of the benzophenoxazine dye Nile red as a fluorescent marker for distinguishing fossil from renewable fuels. In addition to assessing the stability of the fluorescent marker against thermo-oxidative aging, the study probes its antioxidative impact on fuel aging, by comparing unlabeled and with Nile red labeled aged fuels. Furthermore, an examination of fuel-specific parameters underscores the positive effect of Nile red on fuel stability. A comparison with the antioxidant butylated hydroxytoluene confirms the antioxidant effect of Nile red.