Performance and Lifespan Analysis of Modified Al<sub>2</sub>O<sub>3</sub> Catalysts under Varying Oxygen Concentrations and Temperatures for the Degradation of 1,1,1,2-Tetrafluoroethane
Bibliographic record
Abstract
Global warming and the Montreal Protocol necessitate efficient HFC refrigerant degradation. This study evaluates Al 2 O 3 catalysts modified by phosphorus loading, high-temperature calcination, and fluorination. XRD, NH 3 -TPD, Raman spectroscopy, and lifespan experiments showed all catalysts remained in the γ-Al 2 O 3 phase, initially achieving over 99.5% degradation. Significant differences in activity lifespan were observed: P-5-Al 2 O 3 exhibited the highest final activity due to abundant Lewis acidic sites, while Al 2 O 3 -700 demonstrated superior retention, attributed to unique crystalline features, higher active site density, and efficient AlF 3 phase formation. Activity model parameters ( r AlF 3,max, k r, S Al 2 O 3, 0 /N Al 2 O 3, and S Al 2 O 3, 0 / k a ) quantified deactivation dynamics and highlighted the impact of modification methods. Oxygen concentration enhanced degradation rates, CO 2 selectivity, and reduced carbon deposition, while temperatures above 450 °C achieved near-complete degradation. Kinetic analysis revealed a reaction order of 1.434 and activation energy of 70.26 kJ/mol.
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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".