Upgrading of Athabasca Vacuum Tower Bottoms (VTB) in Supercritical Hydrocarbon Solvents with Activated Carbon-Supported Metallic Catalysts
Bibliographic record
Abstract
The hydrotreatment of Athabasca vacuum tower bottoms (VTB) has been examined in supercritical fluids of lower boiling-point hydrocarbon solvents (pentane, heptane, and toluene) and 10 MPa H 2 with and without activated carbon-supported Ni−Mo catalysts (in a reduced or sulfided form). For conversion of asphaltenes (AS) to maltenes (MA), the reduced metal catalysts were more active than the sulfided ones and the acid-washed activated charcoal without any metal loading was found to be the most effective catalyst for converting AS to MA. Sulfided metal catalysts, supported on either γ-Al 2 O 3 or activated carbon (AC), showed much higher activity for both the sulfur and nitrogen conversions than those without sulfidation. Because of its best activities for HDS/HDN, the sulfided 3% Ni−10% Mo/AC (S Ni−Mo/AC) was selected as the catalyst for further detailed studies. With respect to both AS conversion and S/N removal efficiencies for hydrotreatment of the VTB, the following priority sequence for the three supercritical solvents was obtained: toluene > heptane > pentane, following the same decreasing trend of their molecular weights, and hence, supercritical toluene was selected as the reaction medium for more detailed studies discussed in this work. The optimal temperature for hydroconversion of the VTB in supercritical toluene appears to be at around 380 °C, where the greatest yields of MA and the lowest yields of AS and TI were obtained, irrespective as to whether the catalyst was present or not. The catalyst was also most effective for sulfur conversion at 380 °C, attaining a HDS activity of about 70% compared to only about 35% in the treatment without the catalyst at the same temperature. The optimal reaction time for hydroconversion of VTB in supercritical toluene appears to be shorter than 30–60 min, where a greater yield of MA and lower yields of AS and TI as well as less aromatic liquid products might be expected, irrespective as to whether the catalyst was present or not. The optimal time for HDS of VTB in supercritical toluene with the catalyst appears to be at 60 min. On the other hand, the effects of temperature, reaction time, and the catalyst on nitrogen conversion were less significant, compared to those on sulfur conversion, while the catalyst did show some HDN activities in the hydrotreatment of the VTB.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".