The general features of sediment formation in middle distillate fuels were investigated. The effect of nitrogen compounds on sediment formation was determined by using pure nitrogen compounds in model petroleum-derived fuel systems. The rate of sediment formation was dependent on the presence of nitrogen compounds, the nature of the diluent employed, and the storage conditions. Detailed studies of the effects of reaction conditions were carried out witii 2,5-dimethylpyrrole (DMP) as the model. Air, increased temperature, dissolved oxygen, and light all strongly accelerated the sediment forming reaction while moisture had a variable effect. The initial reaction rate was approximately first order in nitrogen concentration. The reaction has a low apparent activation energy and appears to involve a free-radical oxidative self-condensation of the nitrogen compound.

The storage stability of various middle distillate fuels derived from oil shale was investigated by means of an accelerated storage stability test. A variety of liquids were studied including crude shale oils boiling in the middle distillate range, partially upgraded shale oils, and severely refined fuels. Large amounts of sediment were obtained from liquids with high heteroatom content. However, no direct correlation between nitrogen, sulfur, no oxygen levels and sediment level was observed. The results of these studies are consistent with those from previous work with model fuel systems. The sediments produced by different liquids differed in heteroatom content and other characteristics. The nitrogen level of the original liquid was only one factor determining the amounts and types of sediments produced. Thus, studies with model compounds and with actual shale-derived liquids indicate that the total nitrogen content of a fuel per se is not a general predictor of fuel storage stability.

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This paper investigates the potential of thermogravimetric analysis (TGA) as a tool for determination of different species of polymers. Materials analyzed include polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polystyrene, polypropylene, nitriles, and nylon. Analyses showed excellent discriminating results even when samples were contaminated with silicates, organics, moisture, and char. The techniques developed were designed with a forensic-type analysis in mind, such as analysis of blast fragments and arson debris. Techniques were developed that gave satisfactory results even when sample sizes were less than five milligrams.

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