In Situ Observation of Mesophase Formation and Coalescence in Catalytic Hydroconversion of Vacuum Residue Using a Stirred Hot-Stage Reactor
Bibliographic record
Abstract
A microreactor equipped with a view window and a stirrer was used to observe mesophase formation in Athabasca vacuum residue with and without catalyst. The effect of stirring on mesophase formation and its growth and coalescence was studied during the cracking of vacuum residue under hydrogen at 4.8 MPa and 440 °C. Stirring can result in a bimodal distribution of size of mesophase domains. The forced coalescence of mesophase droplets by the stirrer led to the formation of very large mesophase regions (bulk mesophase), which coexisted with a large number of small micrometer-sized mesophase domains. The addition of catalyst likely had both chemical and physical effects on the formation and growth of mesophase. The catalyst gave a delay in the onset of mesophase formation as a chemical effect and a decrease in the amount of bulk mesophase regions by suppressing the coalescence of smaller mesophase domains as a physical effect. The analysis of the resulting cokes by scanning electron microscopy (SEM) showed that catalyst particles agglomerated and stuck to the outer surface of the mesophase domains and suppressed their coalescence. The agglomeration of catalyst particles likely decreased their ability to suppress the formation of small mesophase domains, in the range of a few micrometers in size. However, catalyst was effective in suppressing the formation of bulk mesophase domains with areas over 2000 μm 2 . The results showed that the onset of observable mesophase initially increased with the addition of catalyst, but then decreased at higher catalyst concentrations. SEM observation confirmed that the significant agglomeration of catalyst particles at higher concentrations was likely responsible for the decreased effectiveness of the catalyst in suppressing mesophase formation.
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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".