CHEMICAL BASIS OF MIDDLE DISTILLATE FUEL INSTABILITY: Interactive Effects of Selected Nitrogen Heterocycles with Organic Bases in a Shale-Derived Diesel Fuel.

ABSTRACT

Fuel instability reactions are defined in terms of the formation of deleterious products such as filterable sediments and peroxides. Gravimetric stability tests have been carried out at 80^°C using two model nitrogen heterocycles: 2,5-dimethy1pyrrole, DMP, and 3-methylindole, 3-MI, in an otherwise stable shale derived middle distillate fuel. Potential interactive effects for these model nitrogen heterocycles have been described by the presence of organic base co-dopants. Organic bases employed included: tri-n-butylamine, N, N-dimethyl-aniline, and 4-dimethylaminopyridine. Simple organic amines exerted only minor interactive effects, usually an increase in filterable sediment in the range of 5–15%. However, the diamine species, 4-dimethylaminopyridine, interacted in a strong positive fashion to generate increased amounts, 22–44%, of sediment.