Viscosity Changes during Mild Oxidation of Oilsands-Derived Bitumen: Solvent Effects and Selectivity
Bibliographic record
Abstract
The low-temperature oxidation of oilsands bitumen was investigated to determine how viscosity was affected by oxidation and whether oxidative hardening could be suppressed by solvent dilution. This work was performed to support the development of an oxidative desulfurization process, but it could also find application in processes for bitumen recovery by in situ low-temperature oxidation. The experimental investigation was conducted at 140–200 °C and near atmospheric pressure with oilsands-derived bitumen, air, and mesitylene as the solvent. Solvent dilution decreased the bitumen viscosity through diluent action, but it did not suppress oxidative hardening of the bitumen. In fact, with the presence of a solvent, the bitumen viscosity increased more than by oxidation of bitumen on its own. This could be explained in terms of easier hydrogen abstraction from bitumen relative to the solvent, which increased the probability of addition reactions. The increase in viscosity with oxidation extent was also investigated, and apparently conflicting reports in the literature were reconciled. At a constant temperature, different periods of near constant viscosity increase with the increase in the oxygen consumption were identified. It was also found that, during the first free radical chain-propagation-dominated oxidation period, the extent of viscosity increase was different at different oxidation temperatures for the same level of O 2 consumption. Oxidative hardening is not just related to oxidation extent, but it is also affected by changes in oxidation selectivity because of the conditions at which the oxidation was performed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".