Bitumen oxidation for anaerobic digestion and upgrading

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Oil sands derived bitumen is an important energy source in Canada, but its recovery and use is increasingly coming under environmental scrutiny. In comparison to oil sands bitumen, methane is a clean energy source. Methane is free of heteroatom contaminants (e.g. sulfur) and the infrastructure to employ methane as energy source is already available. This project investigates an enabling step in the conversion of marginal oil sands deposits into methane, namely selective bitumen oxidation to enable bio-conversion into methane. It also considers the upgrading of the oxidised bitumen not suitable for methanogenesis to an upgraded oil. It was demonstrated at laboratory scale that marginal reserves of oil sands bitumen could be harnessed as energy source by chemical oxidation followed by anaerobic digestion of the bitumen to produce methane. The oxidation step was found to be critical and it limited the industrial viability of the process. In this industrially sponsored project, bitumen oxidation will be investigated with the specific objective of devising an alternative strategy to chemical oxidation. Oxidation with air (autoxidation) holds promise to reduce the environmental impact and cost of the process. Challenges that must be overcome include mass transfer limitations due to high bitumen viscosity, the avoidance of free radical addition reactions, obtaining adequate oxidation rate while minimising energy consumption and selective oxidation to products that are suitable for microbial digestion. These topics will be investigated on a fundamental level to develop the science and understanding necessary to devise a strategy for industrial application. The key areas of research are: (a) Oxidation chemistry of bitumen, (b) Reaction engineering of bitumen oxidation, and (c) Bio-conversion of oxidised bitumen.