P17994_Molecular Characterization of Remnant Polarizable Asphaltene Fractions Upon Bitumen Upgrading and Possible Implications in Petroleum Viscosity
Bibliographic record
Abstract
Thermal processing and hydrotreatment are used to decrease the viscosity of Alberta bitumen. However, changes in bulk properties, such as API gravity and viscosity, do not correlate to the gravimetric content of maltenes and asphaltenes. Thus, the work herein employs an extrography separation that yields asphaltene fractions enriched with distinct structural motifs and aggregation tendencies to investigate if changes in viscosity could be linked to the transformation or survival of specific asphaltene compounds and/or extrography fractions. Samples with limited change in viscosity upon thermal processing display minor changes in the gravimetric distribution of the extrography fractions, specifically polarizable species (Tol/THF/MeOH fraction). Ultrahigh-resolution mass spectrometry analysis demonstrates that such samples reveal neither a significant decrease in chemical polydispersity nor a change in the relative content of multicore/archipelago structural motifs post thermal treatment. Conversely, hydroprocessed samples with a pronounced viscosity reduction feature a remarkably lower chemical polydispersity and increased content of single-core (island) structural motifs. Polarizable asphaltene fractions from severely hydrotreated samples feature S-containing species with a low aromaticity, which on the basis of their molecular composition suggests that they are composed of the expected, alkyl substituted, geologically stable thiophenic cores (e.g., benzothiophene) as well as “unexpected” sulfides and sulfoxides. Collectively, the results suggest that the high viscosity of thermally upgraded samples could be correlated to the survival of asphaltene species with high heteroatom content (up to five heteroatoms per molecule) and persistent, high abundance of archipelago structural motifs. Thus, it is suspected that nanoaggregation of such fractions prevents their transformation into lighter products.
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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.002 |
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".