Intriguing Catalyst (CaO) Pretreatment Effects and Mechanistic Insights during Propylene Carbonate Transesterification with Methanol
Bibliographic record
Abstract
Transesterification of cyclic carbonates to dimethyl carbonate using metal oxide (CaO, BaO and SrO) catalysts is reported with the objective of understanding the pretreatment effect of methanol and cyclic carbonates on catalytic performance. Stirred batch reactor experiments reveal that with untreated CaO as catalyst, significant induction time was observed. The induction time was eliminated upon CaO pretreatment with methanol and the transesterification activity increased from 11 to 947 h –1 . In contrast, pretreatment with PC resulted in a prolonged induction time and rate inhibition. Further, although the methanol pretreatment effects were found to be irreversible, those with PC were reversible upon methanol treatment. Pretreatment of CaO with other cyclic carbonates including ethylene carbonate (EC) and 1,2-butylene carbonate (BC) showed similar transesterification trends as PC. Based on these experimental results and complementary catalyst characterization results using SEM, CO 2 -TPD, XRD, FT-IR, XANES and 13 C NMR, a possible reaction mechanism that involves methoxy species as the key intermediate is proposed. In the last, recycle experiments were carried out verified that the catalyst is stable during successive cycles of substrate addition. These results provide new fundamental insights into transesterification catalysis and guidance for rational catalyst design and activation.
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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".