Characterization of particles generated by non-catalytic methane pyrolysis in a tubular flow reactor
Bibliographic record
Abstract
This research investigates the influence of temperature on the physicochemical and morphological characteristics of particles produced during methane pyrolysis in a quartz tubular reactor. To achieve this, a range of analytical techniques, including Raman spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), mobility and aerodynamic particle size spectroscopy, and tandem measurements with a centrifugal particle mass analyzer (CPMA) paired with a single particle soot photometer (SP2) and a scanning mobility particle sizer (SMPS), have been employed. The structural evolution of carbon particles, as depicted by Raman spectroscopy, shows a transition from polycyclic aromatic hydrocarbons (PAHs) to more graphitized forms of carbon with an increase in temperature, marked by the emergence of structural defects. This is further evidenced by TGA, where a significant increase in the mass fraction of coke was found, from roughly 23% to 94% at the pyrolysis temperatures of 950 °C and 1100 °C, respectively. Morphologically, this temperature-dependent transformation results in a shift in the particle size distribution, evolving from smaller, less dense particles with count median mobility diameters around 100 nm at 900 °C to larger, denser particles of approximately 400 nm median mobility diameter at 1100 °C. Additionally, the refractory carbon mass fraction is not strongly dependent on individual particle mass; instead, it increases from ∼0% to over 83% as the temperature rises from temperatures below 975 °C to 1100 °C, further highlighting the significant influence of thermal conditions on aerosol formation in methane pyrolysis. These results have implications for product purity and how to process undesirable PAHs, as well as the development of particle and gas phase separation techniques.
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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".