First-Principles Investigation of Selective Oxidation of Propane on Clean and Sulfided V<sub>2</sub>O<sub>5</sub> (010) Surfaces
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Bibliographic record
Abstract
Oxidative dehydrogenation of propane on single-crystal V 2 O 5 and V 2 O 4 S surfaces has been studied by means of periodic density functional theory. Three previously proposed ODH reaction mechanisms, namely the multisite vanadyl mechanism, the vanadyl-lattice mechanism, and the multisite bridging mechanism, were investigated. Results were compared with existing data from the literature. It was found that the multisite vanadyl mechanism plays the most dominant role in propene formation, with an apparent activation energy of 27 kcal/mol, in very good agreement with the experimental value. The present study also demonstrated that the other two mechanisms are less important in the propane ODH reaction because of the kinetic hindrance arising from the H 2 O desorption and O 2 addition at the lattice site. On the other hand, the effects of sulfur substituents on V 2 O 5 are detrimental in general. In the presence of H 2 S, V 2 O 5 could be readily sulfided, with the estimated activation energy of 30 kcal/mol and reaction energy of 2.5 kcal/mol. At moderate temperatures, a small amount of surface V═O will be converted to V═S, which raises the apparent activation energy associated with the multisite vanadyl mechanism by only 3 kcal/mol. Further increase of reaction temperatures, however, would lead to the formation of lattice S whose accumulation results in the deactivation of the catalyst.
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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 it