Halogenation of Oilsands Bitumen, Maltenes, and Asphaltenes

Abstract

Bromination of oilsands-derived materials was investigated as part of a search to find conversion pathways other than traditional hydroprocessing and thermal processing for the upgrading of asphaltenes. The working hypothesis was that the insertion of a bulky halogen substituent on an aromatic carbon of a multinuclear aromatic might sterically disrupt π–π ring stacking. Mild bromination (1–3 wt % Br incorporation) caused observable changes in the physical appearance of bitumen, maltenes, and asphaltenes. The hardness was increased and the asphaltenes gained solvent resistance, suggesting potential application as pretreatment for road paving asphalt. UV–vis spectrometry indicated that metalloporphyrin structures were disrupted, suggesting possible demetalation. There was also an increased association of oxygenate-rich asphaltenes with iron pyrite particulates already present in this fraction. Bromination was deleterious in its effect on bitumen and the maltenes, resulting in a decrease in straight run vacuum gas oil yield and increase in microcarbon residue. Conversely, bromination of asphaltenes resulted in an increase in straight run vacuum gas oil yield from 2.0 ± 0.3 wt % to 7.5 ± 1.8 wt % without affecting the microcarbon residue. It was not possible to unequivocally attribute the observed changes in the asphaltenes to the disruption of π–π ring stacking.