Reversing and non-reversing phase transitions in Athabasca bitumen asphaltenes

摘要

The phase behaviour of Athabasca bitumen asphaltenes separated from their native hydrocarbon resource using normal alkanes was studied using differential scanning calorimetry (DSC) and temperature modulated differential scanning calorimetry (FMDSC) measurements in the temperature range 300 K to 520 K. For pentane through dodecane Athabasca bitumen asphaltenes, there is a broad reversible endothermic transition, from solid to liquid, overlapping an irreversible exothermic transition in the temperature range 330 IC and 520 K. Thus, in general, asphaltene thermal properties and hence phase behaviour differ depending on their thermal history above 330 K.;The starting temperature of the non-reversing transition was found to be 380 +/- 8 K. The end temperatures increased linearly from heptane to dodecane asphaltenes; pentane and hexane asphaltenes have the same end temperature, which is higher than for the other asphaltenes.