Oxidation of Oils and Bitumen at Various O<sub>2</sub> Concentrations
Bibliographic record
Abstract
This paper describes the effects of various amounts of oxygen on the oxidation of conventional oils and Athabasca bitumen and their coke-forming tendency. At any given oxygen concentration, the weight loss profile with an increasing temperature up to 500 °C during simultaneous thermal analysis (STA) shows the presence of two distinct regions: one below 400 °C, showing distillation/bond breaking and low-temperature oxidation, and the other beyond 400 °C, depicting fuel deposition combined with high-temperature oxidation and combustion of hydrocarbons. Heat-flow changes during oxidation show that exothermicity of the reaction is dependent upon the oxygen concentration as well as the heating rate. The activation energy of the oxidation step was calculated for each oxygen concentration using the Coats−Redfern method. The data showed a decrease in the activation energy with an increase in the oxygen concentration, showing dominance of different reactions under different O 2 concentrations. The activation energy value for oxidation above 400 °C decreased from 72 kJ/mol in the presence of N 2 to 30 kJ/mol in the presence of 21% O 2 . The effect of oxidation on the coke-forming tendency during pyrolysis for some oil fractions shows that, for a fixed sample amount, coke-forming propensity may increase or decrease depending upon the O 2 concentration in the atmosphere above the sample. The extent of increase or decrease in coke-forming tendency varies for different petroleum oils. A Fourier transform infrared (FTIR) spectroscopy study of the sample before and after heating in inert or oxidative atmospheres shows that the presence of small amounts of O 2 affect these samples to varying levels depending upon their chemical composition. Results also give proof of oxidative addition reactions taking place in the presence of O 2 within the whole evaluated temperature range, spanning from about 300 to 500 °C.
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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) | 0.001 | 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".