Research and development of Co and Rh-promoted alkali-modified molybdenum sulfide catalysts for higher alcohols synthesis from synthesis gas
Notice bibliographique
Résumé
The demand for mixed alcohols has grown since ether compounds were banned as gasoline octane improvers in North America.Molybdenum-based catalysts in sulfide form are an attractive catalyst system for the conversion of synthesis gas to alcohols, due to their excellent resistance to sulfur poisoning and high activity for the water-gas shift reaction.The higher alcohols activity over these catalysts is low, due to the formation of hydrocarbons and CO 2 .Although a number of catalysts have been developed for this purpose, not any are used commercially at this time.The main objective of this Ph.D. research is to develop a catalyst system that is capable of selectively producing higher alcohols, particularly ethyl alcohols from synthesis gas.In the present series of studies, the investigation of an alkali-promoted trimetallic Co-Rh-Mo catalyst system has led to improvements in product stream composition.The effect of different loadings of active metal (Mo), alkali (K) promoter, and metal promoters (Co and Rh) on higher alcohol synthesis from synthesis gas were investigated using commercially available multi-walled carbon nanotubes (MWCNTs) as the catalyst support.The role of support on higher alcohols synthesis was also studied using different supports, such as -Al 2 O 3 , activated carbons with different textural characteristics, and MWCNTs.The catalysts were prepared using the incipient wetness impregnation method and extensively characterized in both oxide and sulfide phases using different techniques.Transmission electron microscopy (TEM) results revealed that the metal particles were uniformly distributed inside and outside of the carbon nanotubes, and that metal dispersions were higher on the alkali-promoted trimetallic catalyst supported on MWCNTs.The existence of promoted and un-promoted MoS 2 sites was confirmed by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) studies of adsorbed CO over sulfided catalysts.Temperature programmed reduction (TPR) tests showed that the addition of metal promoters improved the reduction behaviour of the catalysts.XRD patterns showed that alkali-promoted catalysts were less crystalline compared to that of the catalyst not promoted with K.The formation of Co (Rh)-Mo-S species was evident in the XANES spectra of bimetallic and trimetallic alkali-promoted MoS 2 catalysts.The activity and selectivity of the catalysts were assessed in a fixed-bed micro-reactor using temperature, pressure, and gas hourly space velocity in the ranges of 275 to 350C, 800 to 1400 psig (5.52-9.65 Mpa), and unlimited enthusiasm for intellectual growth made my learning experience truly rewarding.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,004 |
| Communication savante | 0,000 | 0,002 |
| Science ouverte | 0,002 | 0,002 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».