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Low Temperature Pyrolysis and its Application in Bitumen Processing Open Access


Other title
Coke Suppression
H-Transfer Solvents
Low Temperature Pyrolysis
Type of item
Degree grantor
University of Alberta
Author or creator
Zachariah, Ashley
Supervisor and department
Dr. Arno de Klerk (Chemical Engineering)
Examining committee member and department
Dr. Arno de Klerk (Chemical Engineering)
Dr. Natalia Semagina (Chemical Engineering
Dr. Vinay Prasad (Chemical Engineering)
Department of Chemical and Materials Engineering
Chemical Engineering
Date accepted
Graduation date
Master of Science
Degree level
Observations in literature date back to 1926 to suggest that bitumen should not be treated like a residuum but more like a young crude oil. This is because of its high reactivity at low temperatures. Taking these observations into consideration, lower temperatures (400 °C and lower) were used to improve pyrolysis product quality (particularly liquid viscosity). A major problem in visbreaking is the formation of coke. The effect of specific solvent properties on coke suppression during mild pyrolysis was investigated. It was noticed that coke suppression was based on the overall availability of transferable hydrogen and methyl-groups present in the system, not just donor hydrogen by solvents. In light of these results it was suggested to co-feed light hydrocarbons to help in coke suppression and improve liquid yields. As an extension of the coke suppression studies, the influence of reaction time was investigated. Various regimes were seen when neat bitumen was pyrolysed that affected product quality. A complex relationship was observed between bitumen viscosity and the asphaltene fraction with at least one local maxima and one local minimum being observed. Two orders of magnitude decrease in viscosity was seen when bitumen was heated for 30 minutes at 400 °C. This was not accompanied by a change in the asphaltenes content. Based on this, it was argued that asphaltenes fraction could donate its hydrogen and methyl groups, and, in a solvent deasphalting-visbreaking sequence, the most meaningful difference in the product quality is observed when the reaction time given was equal to the induction period of coke formation of the feed.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Chapter-3 in this thesis has been published as “Zachariah, A.; Wang, L.; Yang, S.; Prasad, V.; De Klerk, A. Suppression of coke formation during bitumen pyrolysis. Energy Fuels 2013, 27, 3061-3070.”

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