Parametric Study on the CO<sub>2</sub> Capture Capacity of CaO-Based Sorbents in Looping Cycles
Bibliographic record
Abstract
An experimental parametric study on the CO 2 capture activity of four limestone-derived CaO-based sorbents has been performed. Experiments were done in a thermogravimetric analyzer (TGA) at temperatures ranging from 650 to 850 °C. Three particle-size fractions of Kelly Rock limestone and powders obtained by their grinding were also tested, while the influence of carbonation and calcination durations was examined at 750 and 850 °C. Calcination is typically performed in an atmosphere of N 2 and carbonation in 50% CO 2 (N 2 balance), and the influence of the effective CO 2 concentration surrounding reacting particles was examined by changing the sample mass in some experiments. The results indicated that increasing the calcination/carbonation temperature had a negative influence on the sorbent activity, while the influence of particle size was small, although larger particles have higher activity. This was unexpected, but it can be explained by the higher content of impurities in the smaller particles. Grinding enhances sorbent activity, and this appears to be more than simply due to increased external surface area of the sorbent particles in the powdered samples. Prolonged carbonation time has a negative effect on the sorbent performance. The formation and decomposition of CaCO 3 as well as its presence on the sorbent surface at higher temperatures appear to be key factors in the loss of surface area (i.e., decrease in sorbent activity). However, it is shown that the prolonged exposure to calcination conditions employed in this work (inert atmosphere) has a slightly beneficial effect on sorbent behavior as a function of the number of calcination/carbonation cycles. Experiments with larger sample masses typically resulted in better conversions. Analysis of scanning electron microscope (SEM) images of spent sorbent particles obtained from different reactor types indicated that thermal stresses are the main cause for sorbent particle fracture and attrition.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".