Hydrocarbon Addition Reactions during Low-Temperature Autoxidation of Oilsands Bitumen
Bibliographic record
Abstract
Abstract Low-temperature oxidation of bitumen with air in the temperature range of 130–160 °C was investigated. Of particular interest were the addition reactions taking place during oxidation, which contributed to the observed increase in viscosity of oxidized bitumen. During the autoxidation of bitumen, the relative aliphatic to aromatic loss-ratio of hydrogen increased from 18:1 to 30:1 when the temperature was increased from 140 °C to 150 °C and then remained almost the same at 160 °C. It coincided with a bitumen oxidation selectivity change reported in the literature. The hydrocarbon class responsible for most addition reactions during bitumen oxidation is the naphthenic-aromatic class. A model compound oxidation study at 130 °C found no addition products during paraffin oxidation, low addition product selectivity for naphthenic and alkylaromatic compounds, and no measurable oxidation of aromatics without alkyl groups. It was proposed that the dominant pathway for addition reactions of hydrocarbons is hydrogen disproportionation of free radicals to produce olefins. Free-radical addition to olefins through the formation of C–C bonds explained all of the oxidation selectivity observations from the model compound studies, as well as the addition products identified from their mass spectra. It could also be applied to explain the bitumen oxidation results in these and other studies.
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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 | 0.000 |
| 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 | 0.000 |
| 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".