Sulfation Performance of CaO-Based Pellets Supported by Calcium Aluminate Cements Designed for High-Temperature CO<sub>2</sub> Capture
Bibliographic record
Abstract
CaO-based sorbents supported by calcium aluminate cements were originally prepared as sorbents for CO 2 capture in looping cycles. However, their high affinity for CO 2 at high temperatures suggests that they will readily react with any SO 2 present in flue gases to be decarbonated. Thus, the sulfation performance of these pellets was investigated in this study using a synthetic flue gas in a thermogravimetric analyzer (TGA). The results obtained showed that after 6 h in gas containing 0.5% SO 2 at 900 °C the pellets prepared from hydrated lime and cement were >90% sulfated. They showed the highest sulfation affinity among the sorbents tested here. Namely, Cadomin limestone was <30% sulfated and the corresponding hydrated lime <70%. The pellets prepared from limestone powder and cement had significantly lower sulfation (∼65%) in comparison to that for pellets obtained from hydrated lime and cement. The scanning electron microscope (SEM) images of sulfated samples clearly showed the presence of a sulfated shell at the surface of original limestone particles, while the calcium aluminate pellets had porous morphology even after almost 100% sulfation. The X-ray diffraction (XRD) analyses showed that mayenite (Ca 12 Al 14 O 33 ), which is responsible for the good CO 2 capture performance of these pellets, was not present after sulfation. Pellets after 30 carbonation/calcination cycles displayed significantly reduced affinity for SO 2, with sulfation conversions at ∼15%, but they easily recovered this capacity with ∼80% sulfation levels after hydration. These results clearly show that, for the pellets to perform well, the presence of SO 2 must be avoided during looping cycles at least during sorbent regeneration at high temperatures.
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How this classification was reachedexpand
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) | 0.000 | 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 teacher head, 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".