โ Scribed by Suoqi Zhao; Luba S Kotlyar; Bryan D Sparks; John R Woods; Jinsen Gao; Keng H Chung
No coin nor oath required. For personal study only.
As the Canadian supply of light crudes has diminished in recent years, reยฎneries have necessarily been required to deal with difยฎcult to process oilsands bitumens and heavy oils. Bitumen in particular exhibits unique behavior during upgrading; nearly 50% (w/w) of the feedstock is an intractable residuum. The fast catalyst deactivation and high coke forming propensity displayed by this feedstock have been attributed to the asphaltene and associated solids contents of extracted bitumen. The variability of these intractable components in bitumens from mined and in-situ Athabasca oilsands were examined and compared with bitumens from Nigerian and Utah oilsands. Except for the in-situ bitumen, all of the samples were found to contain signiยฎcant amounts of ยฎne solids. Unexpectedly, the in-situ bitumen also contained the least amount of asphaltene and the highest amount of the intractable heteroatoms nickel and vanadium. Solids-free asphaltene samples were characterized by several complementary analytical techniques to determine the relative abundance of different carbon types and to calculate their average three-dimensional molecular conformations. Even though the parent bitumens came from geographically diverse sources the corresponding asphaltene fractions had similar structures. Each sample comprised basic units, or `cores', of condensed aromatic rings connected by bridges. The main differences relate to the number and complexity of the basic units.
๐ SIMILAR VOLUMES
It has been proved in our previous study that during the melt-blending of an epoxy oligomer based on the diglycidyl ether of bisphenol-A (DGEBA) with polycarbonate (PC) at 200ยฐC, the secondary hydroxyl groups in the DGEBA react with the carbonate groups in PC through transesterification, resulting i
Aslphaltenes are difficult to characterize by any procedure that involves chromatography. In an attempt to obtain useful information on unfractionated asphaltenes and their structural relations to their parent coals, asphaltenes from a set of eight coals of hvA rank and different coalification histo