Impact of Multiphase Behavior on Coke Deposition in a Commercial Hydrotreating Catalyst under Sedimentation Conditions
Bibliographic record
Abstract
Diverse coke deposition mechanisms and models, all supported by experimental data, have been proposed for catalytic hydrogenation processes related to heavy oil and bitumen refining. The influence of multiphase behavior on the observed deposition mode is an important but unresolved question in this literature. The model mixture Athabasca vacuum bottoms (ABVB) + decane, which is shown to exhibit L1L2V phase behavior at elevated temperatures and a commercial heavy oil hydrotreating catalyst (NiMo/γ-Al 2 O 3 ) were employed in this preliminary investigation. Under sedimentation conditions, the impact of phase behavior, per se, on the amount of coke deposited on and within catalyst pellets and the distribution of coke within catalyst pellets was found to be a secondary one despite the differences in the physical properties of the solvent-rich L1 phase and asphaltene-rich L2 phase. In all cases, the exterior surfaces of pellets were coated with a thick nanoporous coke layer. The ratio of pore surface area to pore volume also increased with the extent of reaction in all cases, indicating that larger pores are filled in part or plugged in preference to smaller ones. Observed differences in the properties of coked catalyst exposed to the L1 and L2 phases and to multiphase environments are attributed to differences in the asphaltene aggregate size distribution in the two phases and to multiphase hydrodynamic effects.
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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) | 0.000 | 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".