Methane Oxidation over Nanocrystalline LaCo<sub>1-<i>X</i></sub>Fe<i><sub>X</sub></i>O<sub>3</sub>: Resistance to SO<sub>2</sub> Poisoning
Bibliographic record
Abstract
Catalytic activity for CH 4 oxidation and resistance to SO 2 poisoning were tested for three LaCo 1 - X Fe X O 3 prepared by reactive grinding. The catalysts prepared by this method showed well-crystallized perovskite structure and various specific surface areas. The activity in CH 4 oxidation correlates well with BET specific surface area. TPDO experiments showed very large quantities of desorbed β-oxygen that could not be correlated to the activity for CH 4 oxidation. Resistance to sulfur poisoning in the same reaction was tested at 500 °C with 25 ppmv SO 2 added to the feed. Two steps were distinguished during the poisoning reaction. The first one followed an exponential decrease of conversion versus time. The time to reach the end of this step was shown to be directly proportional to the specific surface area. In this step, deactivation was found to be reversible. During regeneration, some sulfur species were found to desorb from the catalyst. The second step was found to be a linear diminution of conversion with time. The slopes of these lines were found to be the same for the three catalysts. A total of 860 h is necessary to deactive the catalyst with the higher specific surface area, and the quantity of sulfur accumulated in the catalyst was found to vary linearly with the poisoning time. XRD showed significant conversion of the catalyst into La 2 (SO 4 ) 3, Co 3 O 4, and iron oxide. The complex poisoning behavior is discussed and associated to the observed differences in the catalyst morphology.
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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".