Thermal Cracking of Athabasca Bitumen: Influence of Steam on Reaction Chemistry
Bibliographic record
Abstract
Thermal cracking of Athabasca bitumen at various reaction conditions with and without the presence of steam was investigated to determine if steam has a chemical influence on coking. The reactions were done in 15 mL microautoclave reactors and a 3” diameter fluidized bed coking pilot unit over a range of reaction severity (350−530 °C, 10−60 min reaction time). The differences between reactions with and without steam were investigated by comparing elemental composition of the products and coke yield. The presence of steam decreased coke yield and decreased sulfur removal, and reduced the H/C ratio of the liquid products. Hydrogen exchange from steam to thermally cracked bitumen molecules was tested by doping water with deuterium oxide (D 2 O) and analyzing liquid and coke products by NMR and stable isotope mass spectrometry, respectively. Preferential deuteration of benzylic carbons was observed along with a trend of increasing deuterium transfer to liquids and coke as reaction severity increased. Free-radical, ionic, and physical mechanisms that can account for these experimental results are discussed.
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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".