Glycerol Steam Reforming over Bimetallic Co−Ni/Al<sub>2</sub>O<sub>3</sub>
Bibliographic record
Abstract
Glycerol steam reforming has been performed in a fixed-bed microreactor containing bimetallic Co−Ni/Al 2 O 3 catalyst using a wide range of steam-to-glycerol ratios (3 ≤ STGR ≤ 12) for reaction temperatures between 773 and 823 K at atmospheric pressure. Physicochemical characterization revealed the presence of both Lewis and Brönsted acid sites on the catalyst although the catalyst appears to have a net surface acidity (acid:basic site concentration ratio = 9.0). Co and Ni oxides as well as the metal aluminates were identified from XRD pattern with crystallite size (131.5 nm) similar to that obtained from H 2 chemisorption experiments (136.0 nm). Glycerol consumption rate data analysis implicates fractional orders with respect to both glycerol (0.25) and steam (0.36) with an activation energy of 63.3 kJ mol −1 . Similar treatment for H 2, CO 2, CO, and CH 4 production rate evinced positive fractional orders for both reactants with the exception of CO which has mild inhibition by steam (−0.065). Mechanistic considerations and associated Langmuir−Hinshelwood and Eley−Rideal kinetic models were derived for both single- and dual-site adsorption modes. However, statistical discrimination as well as thermodynamic evaluation of the associated parameter estimates suggest that the most adequate representation involved molecular adsorption of glycerol and steam on two different sites with surface reaction as the rate-controlling step consistent with the presence of both Brönsted acid and basic sites on the catalyst. Carbon deposition during reaction appeared to be responsible for the loss in surface area and pore volume of the used catalysts. However, these attributes were nearly recovered after regeneration (>90%) using TPR−TPO−TPR−TPO cycles. Significantly, carbon deposition is a strong function of glycerol partial pressure but somewhat insensitive to the presence of steam, suggesting that the carbon residue was probably unreactive with steam under the reaction conditions. Indeed, temperature-programmed heat treatment (TPO−TPR−TPO−TPR and TPR−TPO−TPR−TPO) revealed at least two types of carbonaceous deposits. However, one of these carbon pools was resistant to removal with H 2 .
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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".