Cu-Zeolite SCR Catalyst Thermal Deactivation Studied with FTIR Spatial Resolution
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
<div class="section abstract"><div class="htmlview paragraph">The performance of a commercial Cu-zeolite SCR catalyst after differing degrees of hydrothermal aging (aged for 72 hours at 500, 700 and 800°C with 10% moisture balanced with air) was studied by spatially resolving different key reactions using gas-phase FTIR measurements. Gases were sampled along a channel at different positions and analyzed using FTIR, which overcomes the interference of water and nitrogen on ammonia concentration detection encountered in standard mass spectrometer-based spatial resolution measurements. The NO:NO₂ concentration ratio was changed so that the standard (NO:NO₂ = 1:0), fast (NO:NO₂ = 1:1) and NO₂ (NO:NO₂ = 0:1) SCR reactions could be investigated as a function of the catalyst's hydrothermal aging extent. In addition, the effects of hydrothermal aging on the activity of NH₃ and NO oxidation were also investigated.</div><div class="htmlview paragraph">Hydrothermal aging had little effect on NO oxidation activity. For standard and fast SCR processes, NO<sub>x</sub> conversion attained its maximum at 300°C. Hydrothermal aging decreased reaction rates for SCR and NH₃ overconsumption simultaneously. However, selectivity to NH₃ overconsumption was high over the highly aged catalyst at high temperatures. NO was oxidized to NO₂ at the outlet portion of the catalyst under standard SCR conditions at high temperatures, suggesting a balance between NO oxidation and SCR at limited NH₃ concentrations. NO conversion under standard SCR conditions decreased more with hydrothermal aging compared to NO<sub>x</sub> conversion under fast SCR conditions. Coincidently, NH₃ overconsumption was more significant under standard SCR versus fast SCR conditions.</div><div class="htmlview paragraph">Along a monolithic catalyst channel, the extent of reaction changed with the NO:NO₂ composition. When both NO and NO₂ were present in the inlet gas, the fast SCR reaction dominated. At temperatures below 200°C, a small amount of reaction between NH₃ and NO₂ was also observed. Standard SCR became more significant with NO₂ depletion along the catalyst. However, the fast SCR reaction at high temperatures can be limited by the decomposition of NO₂ at the front of the catalyst.</div><div class="htmlview paragraph">Hydrothermal aging decreased the extent of NO₂ decomposition into NO at high temperatures, which helps maintain fast SCR reaction conditions in the system. The effects of hydrothermal aging on NH₃ oxidation was more complicated. Generally, aging reduced NH₃ oxidation activity, but it did not change monotonically with aging extent and neither did NO<sub>x</sub> produced via NH₃ oxidation. However, the highly aged catalyst did produce a high proportion of NO<sub>x</sub>.</div></div>
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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 | 0.001 |
| Open science | 0.001 | 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