Structural stability and adsorption behaviour of CO2-loaded pure silica CHA and ITW zeolites upon compression
Bibliographic record
Abstract
The present study investigates the structural stability and adsorption behavior of ultrahigh CO 2 -loaded pure-silica zeolites chabazite (CHA) and ITQ-12 (ITW) under high pressure conditions. To analyze these properties, we have utilized in situ synchrotron-based X-ray powder diffraction techniques. Lattice indexation provides information of the filling process and, through Rietveld refinements and Fourier recycling methods, we have been able to (i) determine the location and amount of guest carbon dioxide molecules within the cavities of pure-SiO 2 CHA zeolite and (ii) tentatively determine that within the channels of the porous pure-SiO 2 ITW framework. The filling of the zeolite pores with CO 2 molecules was found to have a positive impact on the structural stability of both CHA and ITW under compression, which do not undergo pressure-induced amorphization up to 12.2 GPa and 15.9 GPa, respectively. Interestingly, low compressibility takes place in CHA zeolite below 4 GPa during CO 2 loading and a second-order phase transition occurs in CO 2 -filled ITW zeolite at 2.1 GPa. These results highlight the influence of CO 2 adsorption on the compressibility behavior of these zeolites. Overall, our study provides detailed insights into the structural behavior of CO 2 -loaded CHA and ITW under high pressure and allows comparison with other pure silica zeolites described in the literature. • Ultrahigh CO 2 filling in the zeolite pores preventing pressure-induced amorphization. • CHA zeolite exhibits low compressibility below 4 GPa during the accommodation of CO 2 . • A second-order phase transition occurs in CO 2 -filled ITW zeolite at 2.1 GPa. • Determined location and quantity of guest CO 2 molecules within the zeolite pores.
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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) | 0.000 | 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 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".