Visbreaking of Deasphalted Oil from Bitumen at 280–400 °C
Bibliographic record
Abstract
The time-dependent thermal conversion of vacuum residue deasphalted oil was studied at 280, 320, 360, and 400 °C. The vacuum residue deasphalted oil was an industrial product produced by vacuum distillation of Athabasca bitumen followed by solvent deasphalting using n-pentane. This type of visbreaking process was of interest for partial upgrading of bitumen to facilitate pipeline transport. Practically useful cracking conversion and viscosity reduction for upgrading were found only at 360 and 400 °C. The viscosity measured at 40 °C could be reduced by 3 orders of magnitude from 3720 Pa s in the feed to 2–5 Pa s in the product. The density of the product was not reduced by much, despite vacuum residue cracking conversions of 34% at 360 °C and 45–47% at 400 °C before the onset of coking. The liquid yield was 88–89%. A heavier product fraction was formed during thermal conversion. The heavy material was not necessarily asphaltenes, but an increase in n-pentane-insoluble material was also found that appeared correlated with the aromatic hydrogen content of the product. The limited change in density was at least partly explained by the increase in both heavy material and aromatic nature of the product. Vacuum residue conversion at 360 °C increased linearly with time, which indicated zero-order kinetics. Vacuum residue conversion at 400 °C was non-zero-order. This study showed that thermal cracking at 360–400 °C is better described by a rate equation with two terms. Temperature-dependent differences in the maximum conversion before the onset of coking and the kinetic description of vacuum residue conversion indicated that the equivalent residence time description of visbreaking was an inadequate approximation of thermal conversion at 400 °C and below.
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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) | 0.003 | 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".