Bibliographic record
Abstract
Thermal conversion of oilsands bitumen at 400 °C was investigated to gain a better understanding of temporal changes in liquid properties. The work approximated a mild thermal cracking (visbreaking) process with run-lengths extending into the coking region. Reaction progress could be divided into three main regimes: (I) stable visbreaking, (II) coking visbreaking, and (III) coking. In addition to observations anticipated from the literature, the work revealed aspects of the reaction progression that was not fully appreciated before. Stable visbreaking with minimal formation of coke had a “productive” period during which viscosity decreased, while asphaltenes content and gas yield were unchanged, followed by an “unproductive” period during which the viscosity, asphaltenes content, and gas yield all increased. After the onset of precipitation of solids, the solids (“coke”) yield increased and the asphaltenes content in the liquid decreased, but the viscosity increased. The origin of increased viscosity was not due to increased asphaltenes content but due mainly to free radical addition products that remained soluble in the bulk liquid. The insolubility of molecules in the liquid and meso-phase that ultimately led to precipitation as solids and coke formation at higher temperatures, appeared to be caused by addition reactions more than as result of asphaltenes and hydrogen-depletion. The investigation does not prove this conclusively, but if this interpretation is correct, the coking limit of stable visbreaking operation at 400 °C is not as result of a solubility constraint caused by hydrogen-depletion; instead, it is the result of free radical addition that manifests as a solubility constraint leading to hydrogen-depletion. In the reaction sequence, the importance of hydrogen disproportionation of alkyl cycloalkane functionality in the bitumen was highlighted to explain the major changes, including the onset of increased gas yield and increased viscosity that was attributed to free radical addition.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".