Instability of middle distillate fuels during storage and characterization of insolubles by FTIR

The problem of stability of diesel fuels has become more pronounced in recent years with the increasing use of cracked stocks in the diesel pool. These cracked products induce gum and sediment formation in fuels. In the present paper, the instability of total cycle oil (TCO) derived from FCC operation of Bombay High VGO, under accelerated and ambient storage conditions has been studied with and without additive doping During ambient storage yield of the insolubles in TCO has been found to decrease after a period of about 18 months which may be attributed to the reformation of fresh oxidised species from insolubles. However during accelerated tests trend of increasing insoluble formation with time is revealed. The qualitative composition of insolubles obtained from ambient storage of additive doped and undoped fuels has been studied by FTIR and the role of additives on the composition of insolubles is discussed.