Effect of Inter-Molecular Association on Bitumen Oxidation

Abstract

The hypothesis that inter-molecular associations between species in petroleum bitumens affects the rate of air oxidation of the bitumens was examined using infrared spectroscopy, gel permeation chromatography and viscosity measurements. Experiments were carried out in which the rate of oxidation of two different bitumens and their fractions (maltenes, resins, asphaltenes) were measured in terms of carbonyl group formation. In THF solution at 30°C the rates of reaction of the maltene and asphaltene fractions were the same when oxidised separately or as a mixture. Although the presence of inter-molecular associations were confirmed by gel permeation chromatography, the results indicated that such effects were unimportant to the rate of the reaction. Further experiments were performed in which neat bitumen, resin and maltene (n-heptane) factors and reconstituted mixtures were 291 oxidised under 2069 kPa of oxygen or air at 40°C or 60°C. Again, no evidence for the effect of inter-molecular association on oxidation rate was obtained. Another experiment in which a bitumen, rejuvenating oil (RO), and a mixture of the two was oxidised (2069 kPa air, 60°C) again showed that the reaction rate of the bitumen and RO were the same when oxidised separately or in the mixture. However, in contrast, the rate of increase of viscosity of the bitumen was significantly affected by the RO and was attributed to dispersal of polar oxidation products by the RO.

Desulfurization of Heavy Oil–Oxidative Desulfurization (ODS) As Potential Upgrading Pathway for Oil Sands Derived Bitumen

“…Herrington and Wu observed that the rate of oxidation of undiluted bitumen (with aggregation) and diluted bitumen was similar, 53 even though some matrix effects have been reported in model compound studies. 54 The sulfur oxidation reaction should therefore not be drastically affected by n-heptane dilution.…”

Effect of Air on the Kinetics of Asphaltene Precipitation from Diluted Crude Oils

“…It is well known that asphalt oxidizes under ambient conditions with long exposure to air. − Oxygen has also been shown to affect asphaltenes at lower temperatures near ambient conditions. Herrington and Wu , studied the oxidation of toluene-diluted bitumen at 50 °C and found that oxidation at low temperatures may not be caused by oligomerization of aromatic species but instead by intermolecular associations formed within the oxidized asphaltenes. Choi et al investigated asphaltene oxidation with ozone at 40 °C in a model oil consisting of n -heptane Athabasca asphaltenes rediluted in toluene.…”

A New Hybrid Approach for Desulfurization of Diesel Fuel and Straight Run Gas Oil using MIM-PW11CuO39@CuO as a Heterogeneous Nanocatalyst

“…hazardous emission of Sox (Herrington and Wu, 1999;samimi et al, 2020). So far, a wide variety of techniques has been proposed for the desulfurization of fuels and oils.…”