(66f) Kinetic Precipitation of Asphaltenes with the Presence of Inorganic Solids

Authors: 
Hoepfner, M. P., The University of Utah
Chaisoontornyotin, W., University of Utah
Zhang, J., University of Utah
Ng, S., Syncrude Canada
This work investigated the influence of inorganic solids on the rate of kinetic precipitation of asphaltenes from diluted bitumen. At a fixed amount of precipitated asphaltenes, higher solid contents significantly enhanced the rate of asphaltenes precipitation, resulting in no significant observable kinetics under certain conditions. The results suggested a heterogeneous precipitation mechanism for asphaltenes exists when inorganic solids are present in bitumen or petroleum samples. A combined homogeneous aggregation and heterogeneous nucleation model was developed to analyze the results. The rate of heterogeneous nucleation was observed to be upwards of 90% faster than the rate of homogeneous aggregation, but as the quantity of precipitated asphaltenes increased, the rate of homogeneous aggregation could exceed that of heterogeneous nucleation. Scanning Electron Microscope with Energy- Dispersive X-ray Spectroscopy was used to investigate the inorganic solid properties. The results suggest that kaolinite is likely the mineral present in the studied samples that exhibit the heterogeneous precipitation mechanism; however, other materials may also behave similarly. This investigation leads to a better understanding of asphaltene aggregation in systems with inorganics solids and provides a simple model that can estimate the rate of asphaltene precipitation under different conditions. Moreover, this work provides a potential new tool to increase the rate of the often-slow kinetic precipitation of asphaltenes using inorganic solids as nucleation sites to reduce experimental time.