Natural Gas Hydrate Formation and Decomposition in the Presence of Kinetic Inhibitors. 3. Structural and Compositional Changes
Bibliographic record
Abstract
A synthetic natural gas mixture composed of methane, ethane, and propane in a batch reactor was used to form gas hydrates in the presence of two commercial, chemical kinetic inhibitors, polyvinylpyrrolidone (PVP) and H1W85281, and one biological inhibitor, antifreeze protein type III (AFP-III). Powder X-ray diffraction and nuclear magnetic resonance spectroscopy showed that structure II hydrates dominated, as expected, but in the presence of the chemical inhibitors, structure I was also present. Raman spectroscopy confirmed the complexity and the heterogeneity of the guest composition within these hydrates, which was also consistent with the gas analysis obtained using gas chromatography. However, in the presence of AFP-III, hydrates appeared to be relatively homogeneous structure II hydrates, with weaker evidence of structure I. When individual gas cage occupancies were calculated, both classes of inhibitors reduced large cage methane occupancy by ∼25%. With the chemical inhibitors, these large cage methane guests appeared to be substituted by ethane, likely resulting in a decreased driving force for hydrate production. In contrast to the near full occupancy of large cages with these inhibitors, almost 10% of the large cages were not filled when hydrates were formed in the presence of AFP-III, likely contributing to the easy decomposition of such hydrates seen in other studies. Therefore, hydrates formed in the presence of these two classes of inhibitors appear to be distinct, and as a consequence, their inhibition mechanisms, as well their practical utility in the field, are likely to be marked by important differences.
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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".