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Asphaltene Microencapsulation of Bitumen as a Means of Solid-Phase Transport

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journal contribution
posted on 29.03.2021, 07:04 by Anita, Wasif Zaheer, Lacey Douglas, Diane G. Sellers, Subodh Gupta, Sarbajit Banerjee
As a result of the depletion of conventional oil reserves and the unprecedented growth in world energy demand, increasing attention has focused on the extraction and utilization of unconventional oils. The high viscosity of these unconventional hydrocarbons, specifically bitumen and heavy crude oil, is an obstacle to their transportation through conventional means such as pipelines. Rheological challenges associated with the transportation of bitumen are typically addressed through dilution with light hydrocarbons and thermal jacketing, which consume considerable energy and result in wasteful consumption of pipeline capacity with diluent fluids. Liquid-phase transportation further poses the risk of spillage and ecological contamination. Enabling the transport of bitumen as a solid-phase material will mitigate the transportation constraints of pipelines and the disastrous effects of oil spills. The formation of bitumen prills that can be reversibly fluidized at the point of recovery presents a considerable challenge. To prepare solid-phase bitumen, we have sought to encapsulate lighter fractions of bitumen within a cross-linked shell of asphaltenes recovered from the same source. Asphaltenes are extracted from bitumen and reconfigured to coat the outer surfaces of bitumen droplets, thereby constituting core–shell microcapsules. An automated jetting system equipped with a dual-flow nozzle has been reconfigured to prepare bitumen microcapsules coated with cross-linked asphaltenes. The core–shell microcapsules are collected in a heated surfactant-water bath designed to prevent capsule agglomeration and enhance the cross-linking of the asphaltenes shell. The release of bitumen in response to the application of mechanical stress has been studied and indicates that the microcapsules exhibit size-dependent stress-withstanding abilities ranging up to ca. 145 kN/m2 for 2.4 mm microcapsules. The prepared microcapsules demonstrate the viability of solid-phase transportation of bitumen via roadways and marine tankers through reconstitution of the components of bitumen without the need for extraneous additives.