Solid-State NMR Investigation of the Possible Existence of “Nanoblocks” in the Clear Solution Synthesis of MFI Materials
Bibliographic record
Abstract
The structure of the intermediate species in the clear solution synthesis of the MFI framework (zeolite ZSM 5) has been investigated using the characteristic 13 C, 14 N, 15 N, and 2 D spectra of the tetrapropylammonium (TPA) template ions as probes as well as the 29 Si spectra of the silicate species present in samples that can be isolated by centrifugation. Comparison with the corresponding spectra of the final products that can be characterized by X-ray diffraction indicates that there is no evidence for the involvement of nanospecies, as has been proposed, and that crystallization is most probably from an amorphous gel. This conclusion is supported by the lack of deuterium rotational echo double-resonance dephasing of the 29 Si spectra by deuterated TPA of the earliest intermediate species obtained, while it is clearly observed in the final product. These observations indicate that any TPA ions present in the gel phase are not in intimate contact with the silicon nuclei as they would be if in the local MFI environment. This is supported by the very low amount of TPA found by 14 N NMR, which is much less than needed for the proposed nano intermediates and the fact that the TPA present can be removed by simple re-suspension in water and recovery.
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.
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 | 0.001 | 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 | 0.000 |
| 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 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".