Study of catalysts for the hydrodeoxygenation reaction of phenol
Notice bibliographique
Résumé
The conversion of biomass into bio-oil through fast pyrolysis followed by its upgrading via hydrodeoxygenation (HDO) is considered a potential route for the production of renewable fuels. The present work aimed to develop new catalysts for the hydrodeoxygenation (HDO) of phenol, which is a typical bio-oil model compound. The work section was divided in 5 independent chapters: (i) a thermodynamic study in order to determine the most favorable operational conditions for the HDO of phenol. According to this study when methane was added to the system, the equilibrium composition calculated indicated only the formation of methane for all the conditions evaluated. However without CH4, the best operational conditions to perform the phenol HDO reaction are at intermediate temperatures and with high H2/phenol ratio; (ii) In sequence, the effect of to the addition of a second metal (Cu, Ag, Zn, Sn) on the performance of Pd/ZrO2 catalyst for HDO of phenol in the gas phase was studied. The incorporation of dopants to Pd/ZrO2 resulted in the formation of Pd–X (Cu, Ag, Zn) alloys, which reduced the reaction rate for HDO and increased the selectivity to hydrogenation products (cyclohexanone and cyclohexanol). However, the oxophilic sites generated by Sn cations promoted the hydrogenation of the carbonyl group of the keto-tautomer intermediate formed, producing benzene as the main product; (iii) The impact of particle size of ZrO2-supported Pd and of alloying with Ag was explored for hydrogenation of phenol in aqueous phase. This study was performed during an internship at PNNL (Pacific Northwest National Laboratory). Kinetic assessments were performed in a batch reactor, on monometallic Pd/ZrO2 samples with different Pd loadings (0.5%, 1% and 2%), as well as on a 1% PdAg/ZrO2 sample. In general, the lower activity of the small Pd particles was attributed to low activation entropies for the strongly bound species and the presence of Ag increases catalyst activity by decreasing the apparent energy of activation and increasing the coverages of phenol and H2, without negatively affecting the transition entropy; (iv) After that, based on the recent insides reported about the HDO reactions, the hydrodeoxygenation of phenol was studied using Rh, Pd and Ni catalysts supported on Nb2O5. This part allowed understanding how the SMSI (strong metal-support interaction) affects the selectivity of the HDO reaction. In general, an increase in the reduction temperature favored benzene selectivity, all the samples showed selectivity of approximately 95% for benzene for high reduction temperatures; (v) In the final chapter of this work the effect of doping cerium oxide support with niobium was investigated for HDO of phenol at 573K in the gas phase. The incorporation of niobium altered the lattice parameters of cerium based oxides, favored the reduction of the cerium and increased the selectivity to deoxygenated products (benzene). Small amounts of niobium affected the surface area of the support and promoted the formation of more dispersed nickel particles, which disfavored the hydrogenolysis of benzene. In general, the data presented in this thesis contributed to a better understanding of the HDO reaction. Keywords: hydrodeoxygenation, phenol, bimetallic, thermodynamics, niobium, oxides.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| 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 source (Gemma direct ou Codex distillé), 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 ».