Catalyst and Process Effects in the Solvent-Free Hydrogenation of p-Cymene to p-Menthane
Bibliographic record
Abstract
The hydrogenation of p-cymene to p-menthane, a bio-based solvent, over four platinum-group catalysts, was thoroughly investigated in this study. The effect of the support material, pressure, and temperature were explored. Rhodium was the most effective metal, even under normal pressure conditions. Charcoal was a better metal support compared to alumina, offering better selectivity at lower pressure and outstanding recyclability. Hydrogen pressure had no effect on the selectivity; however, the conversion rate was maximal at higher pressure. At higher temperatures, the thermodynamically stable trans-isomer was favored, whereas at lower temperatures the cis-isomer became predominant. Remarkably, Rh/C achieved >99% conversion of p-cymene and maintained stable activity and selectivity over 66 recycling cycles, whereas the same metal-based catalyst on alumina was only recycled twice. These findings demonstrate that the solvent-free hydrogenation of p-cymene can be efficiently achieved using commercially available catalysts, with Rh/C emerging as a promising benchmark for sustainable and green catalytic processes.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".