Investigation on the Reversibility of Asphaltene Precipitation
Bibliographic record
Abstract
The precipitation and redissolution of asphaltenes upon the addition and removal of solvent were investigated for Athabasca and Cold Lake bitumens using a flow-loop apparatus. The presence of precipitate was detected through an increase in pressure drop across an in-line filter. These solvent-reversibility experiments were conducted at 40 and 60 °C with n -heptane solvent. A significant hysteresis was observed for Athabasca bitumen while little or no hysteresis was observed for Cold Lake bitumen. In both cases, the precipitation could be completely reversed. Temperature-reversibility was also investigated with n -dodecane solvent at temperatures ranging from 40 to 160 °C. A hysteresis was observed for both bitumens and only partial reversibility was achieved. Benchtop solvent-reversibility experiments were also conducted on the two bitumens at room temperature. In this case, the precipitate was recovered by centrifugation. The benchtop results were in good agreement with the flow-loop experimental results. Two heavy oils were also tested and both exhibited hysteresis and complete reversibility. Precipitation and redissolution in n -heptane were measured over time for the Athabasca bitumen. Precipitation increased over time reaching an apparent equilibrium after 8 days. Redissolution experiments reached virtually the same equilibrium position in less than 1 day. The slow kinetics of precipitation suggests rate-limiting nucleation, growth, or flocculation of the asphaltenes. Redissolution experiments with their more rapid kinetics are better suited for obtaining equilibrium solubility data.
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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".