Ozonation of Oilsands Bitumen

Abstract

The conversion of bitumen with ozone should in principle lead to oxidative degradation, as opposed to the increase in viscosity found during the reaction with oxygen because ozonation can lead to CC scission by ozonolysis. However, when bitumen was reacted with ozonated air at 140−160 °C, the viscosity increased compared to conversion with air under the same conditions. To explain these observations, the ozonation of model compounds of various hydrocarbon and heterocyclic compound classes was studied. The selectivity and nature of the oxidation products from ozonation were different from that of autoxidation. Ozonolysis that led to the ring opening of aromatics was observed. At low conversion (<10%), the addition product selectivity of the five-membered cyclic hydrocarbons, indane and indene, was less after reaction with ozonated air than with air. It appears that the observed increase in bitumen viscosity was due to the increased free radical addition product selectivity of heterocyclic compounds, which was higher after reaction with ozonated air than with air. It was also found that at higher conversion (>10%), the increase in oxidized material caused a dramatic increase in addition product selectivity during ozonation. A plausible reaction pathway for addition product formation was proposed on the basis of the Criegee mechanism. The nature of unique addition products from ozonation that were not observed after autoxidation could be explained in terms of the decomposition of the ozonide and recombination of the free radical fragments.

Prospect of Controlled Autoxidation to Produce High‐Value Products from the Low‐Value Petroleum Fractions

“…[69] Viscosity increases were also observed during the oxidation of Athabasca bitumen with air, oxygen, and ozone. [70] Although viscosity increase and bitumen hardening are detrimental from an upgrading perspective, there is potential to prepare petroleum-based precursors for carbon fiber manufacturing by increasing molecular weight distribution, aromaticity, [26] and crosslinking that would result in a higher softening point of heavy petroleum fractions. Barr and Lewis (1978) documented identical chemical changes during mild air oxidation of coal tar pitches.…”

“…Moreover, heteroatoms containing part of the bitumen (e. g., part having N, S, and O) show the addition product formation (Figure 14). [69] Viscosity increases were also observed during the oxidation of Athabasca bitumen with air, oxygen, and ozone [70] . Although viscosity increase and bitumen hardening are detrimental from an upgrading perspective, there is potential to prepare petroleum‐based precursors for carbon fiber manufacturing by increasing molecular weight distribution, aromaticity, [26] and crosslinking that would result in a higher softening point of heavy petroleum fractions.…”

Aging Mechanism and Rejuvenating Possibility of SBS Copolymers in Asphalt Binders

“…This phenomenon could be explained with Equation (2). Irradiated by ultraviolet light in the aging box, parts of oxygen were transformed into ozone [41], which behaved stronger in terms of oxidizability. Consequently, SBS copolymers were oxidized by both ozone and oxygen in the ultraviolet aging box, the larger then was obtained at a UV aging condition.…”

Study on the Aging Behavior of Asphalt Binder Exposed to Different Environmental Factors

“…Asphalt binder UV aging tests are now increasingly becoming standardized [11][12][13][14][15]. Ozone, water, and multifactorial coupled aging are also garnering increased attention [10,[16][17][18]. Qian [19] delved into the effects of UV radiation and various water environments on asphalt binder, uncovering that water environments and UV aging exacerbated asphalt binder aging and diminished its low-temperature crack resistance.…”