Molecular Insight into the Growth of Hydrogen and Methane Binary Hydrates
Bibliographic record
Abstract
H 2 is considered as the ideal fuel; however, the storage and transportation of H 2 limit its usage. Clathrate hydrates are candidate materials for H 2 storage and transportation. Because of the extreme conditions necessary to stabilize the pure H 2 hydrate, additives are proposed to stabilize a mixed H 2 hydrate. Compared to the widely studied H 2 + tetrahydrofuran binary hydrates, H 2 + CH 4 binary hydrates contain a higher energy density. In this study, we study the growth of H 2 + CH 4 binary hydrates for two sets of temperature and pressure conditions by using molecular dynamics simulations with atomic models. Our results show that CH 4 acts as a thermodynamic promoter for H 2 + CH 4 hydrate formation, while H 2 acts as a kinetic promoter for H 2 + CH 4 hydrate growth at some of our working conditions. We find that there is a maximum growth rate of H 2 + CH 4 binary hydrates at 250 K when the pressure is 50 MPa, and at fixed temperature, the growth rate of H 2 + CH 4 binary hydrates shows a positive correlation with pressure. We also find that adding H 2 in the gas phase, decreasing temperature (not smaller than 240 K), or increasing pressure can dramatically reduce the percentage of empty cages in the grown hydrate. Moreover, with increasing temperature, the occupancy of 5 12 and 5 12 6 4 cages by H 2 decreases, and inversely, the occupancy of cages by CH 4 increases when the temperature is above 240 K. With increasing pressure, there is an increase in the percentage of 5 12 cages occupied by H 2, where the ratio of H 2 and CH 4 occupied cages in the grown hydrate can be 3:1 at 250 K and 80 MPa. However, the occupancy of 5 12 6 4 cages by H 2 and CH 4 remains relatively constant with increasing pressure. In addition, at our working conditions, 5 12 6 4 cages can be double-occupied by H 2, and several 5 12 6 4 cages can be occupied by H 2 and CH 4 or triple H 2 . Our simulations show that the solubility and diffusivity of guest molecules, especially CH 4, in solution dominate the growth process.
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 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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".