Time-resolved Characterization of Aging Products from Fossil and Biogenic Diesel Fuels

摘要

Diesel fuels of fossil as well as of biogenic origin are subject to chemical aging. In diesel fuel injection systems, high pressures and temperatures lead to stressing of the fuel and can cause formation of aging products. The main objective of the present study is to develop a deeper understanding of the processes involved in diesel fuel aging. Fossil diesel, biodiesel, and hydrogenated vegetable oil (HVO) were aged under accelerated conditions (elevated temperatures and increased air supply). In time-resolved analyses, identification and quantification of low-, medium- and increased molecular mass aging products was performed. Similarities as well as differences in the formation of aging products in different diesel fuels could be determined. The main aging products that were found in investigated aged fuels include formic acid, acetic acid and other short-chain carboxylic acids, aldehydes and ketones of various chain lengths and dimers and oligomers of complex compositions. Other aging products, such as epoxides, could only be identified in biodiesel. A causal link between the ends of the fuels' induction periods and the formation of aging products was observed.