Effect of minerals on coke precursor formation

The effect of fine solids on the incipient formation of toluene insoluble material (coke) from Cold Lake bitumen at temperatures of about 380–400°C was investigated. Experiments were performed at atmospheric pressure using both 1.5 g samples of bitumen without stirring and stirred bitumen samples of 50 or 100 g. Volatiles formed during the reaction were swept from the reactors by a continuous nitrogen purge. The toluene insolubles yield and weight loss of bitumen were measured in the absence and presence of different solid additives present at 2 wt%. Molybdenum sulfide, silica, kaolinite and Southern Alberta clay had no effect on either the toluene insolubles yield or the weight loss at 390°C and 4.5 h reaction time. However, native clays, which were originally separated from Athabasca bitumen, decreased the incipient coke yield by one quarter, from 4% (in the blank experiments) to 3%. No effect on volatiles formation was observed. The reduction in the coke yield increased as the concentration of native clays was raised.