Characterization of Asphaltene Building Blocks by Cracking under Favorable Hydrogenation Conditions
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Bibliographic record
Abstract
The chemical building blocks that comprise petroleum asphaltene molecules were determined by thermal cracking of samples under conditions that minimized alterations to aromatic and cycloalkyl groups. Favorable hydrogenation conditions that used tetralin as a hydrogen-donor solvent and an iron-based catalyst allowed asphaltenes derived from different crude oils to yield approximately 50–60 wt % distillates (<538 °C fraction), with coke yields below 10 wt %, and reach conversions of the vacuum residue fraction between 65 and 75 wt %. Products in a wide range of boiling points, from naphtha to heavy material in the vacuum residue range, were observed by simulated distillation. Quantitative recovery of the cracked products, with mass balances above 96%, and characterization of the distillate fraction by gas chromatography–field ionization–time-of-flight high-resolution mass spectrometry (GC–FI–TOF HR MS) provided information on the abundance of building blocks, including saturates, 1–3-ring aromatics, 4+-ring aromatics, and nitrogen- and sulfide-containing molecules. Samples of asphaltenes from different geological basins exhibited a remarkable similarity in the yields of building blocks, with paraffins and 1–3-ring aromatics as the most abundant species. The diversity of molecules identified in the distillate products from the cracking of asphaltenes suggests a high degree of heterogeneity and complexity of asphaltene molecules, built up by smaller fragments attached to each other by bridges. The sum of material remaining in the vacuum residue fraction and the yield of coke were in the range of 35–45% and represent the maximum amount of large aromatic clusters present in asphaltenes that could not be converted to distillates or gases under the cracking conditions used in this study.
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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) | 0.001 | 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 it