Molecular Modeling of the Heavy Components from Athabasca Bitumen Pitch

As the declining production of conventional light crude oils in North America continues there is increased interest in the heavy oils and bitumen resources of Western Canada. While these oils represent a very large resource, they exhibit unique behavior during upgrading to lighter products. In particular, the heaviest fraction from bitumen pitch (end-cut) is exceptionally intractable. An earlier study showed that the molecular structure of the end-cut comprises three clusters of condensed aromatic and hydroaromatic rings, joined by aliphatic bridges. In this present work we use Computer Aided Molecular Dynamics (CAMD) to provide further insight into the structure of this component. Energy minimization indicates that the most likely bridge length between the clusters comprises five to seven carbon atoms. The calculations also provide information on molecular size and shape, i.e., those properties most closely associated with reactivity in catalytic upgrading processes.