Microwave Conversion of High-density Polyethylene to Hydrogen
Notice bibliographique
Résumé
Out of the 35 million tonnes of Canadian solid waste collected in 2018, only 29% was diverted (away from landfill). One of the roadblocks to increasing the diversion rate is the lack of knowledge about the potential of solid waste for thermochemical conversion. The total energy potential was quantified at 193 PJ/y if all solid waste were converted to heat, exceeding the total annual energy consumption of both the cement and steel industries in Canada. Plastic waste is the third-largest component of waste, accounting for 10% of total Canadian solid waste collected. The higher heating value of plastic waste—30 MJ/kg on an as-received basis—and its low moisture content—10 wt% on an as-received basis—resulted in the highest energy potential—58 PJ/y—among waste types. Polyethylene waste alone accounts for 27 wt% of total plastic waste, and its energy potential contributes 40% of the total plastic waste energy potential due to its high heating value of 44 MJ/kg. Approximately 89% of Canadian plastic waste is currently being landfilled, despite its high energy content and abundance. One way to valorize plastic waste is to convert it into gaseous fuel using microwave technology. Some plastics, such as high-density polyethylene (HDPE), are transparent to microwaves. Therefore, a microwave absorber, such as carbon material, must be mixed with the plastic before treatment. However, the active properties of carbon material for the microwave conversion of HDPE to hydrogen are not well understood. This thesis investigated the surface oxygen groups of carbon materials that affect hydrogen production in the microwave conversion of HDPE. Heat treatment and hydrogen peroxide treatment were performed on two different activated carbon materials. Quinone was identified as an impactful surface oxygen group (promoted by 14 mmol H2/gHDPE) for hydrogen production. In addition, the most active activated carbon material (reaching 15 mmol H2/gHDPE) can be reused for five cycles, maintaining more than 80% of its fresh hydrogen yield. The experimental setup significantly affected hydrogen yield, with the feed-to-absorber ratio and sample bed height as critical parameters. Hydrogen production reached a local maximum with changes in the feed-to-absorber ratio varied by more than threefold. Additionally, hydrogen yield decreased by a factor of two with increasing sample bed height. The impact of oxygen in metal oxides on hydrogen production in microwave conversion of HDPE is not well understood. This thesis uses cobalt oxide, both on and off an alumina support, and cerium oxide to explore the role of oxygen in metal oxides on hydrogen yield. The oxygen in the cobalt oxide reacted with hydrogen to produce water, which then reacted with hydrocarbons via steam reforming and subsequent water-gas shift reactions to produce hydrogen. The findings identified the potential for solid waste diversion in Canada through thermochemical conversion. Additionally, the experimental results will aid in designing a bifunctional carbon material that can serve as both a microwave absorber and a catalyst to enhance hydrogen production in the microwave conversion of high-density polyethylene plastic waste. Moreover, metal oxides can be incorporated into the carbon-HDPE system, further enhancing hydrogen production for the microwave conversion of HDPE.
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) | 0,003 | 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 ».