The role of the Boudouard and water–gas shift reactions in the methanation of CO or CO2 over Ni/γ-Al2O3 catalyst

Autor: John S. Dennis, James McGregor, Jin Yang Lim, Andrew J. Sederman
Jazyk: angličtina
Rok vydání: 2016
Předmět:
ISSN: 1873-4405
DOI: 10.17863/cam.802
Popis: The Boudouard and the water–gas shift reactions were studied at different temperatures between 453 and 490 K over a Ni/γ-Al$_2$O$_3$ catalyst in a Carberry batch reactor using various mixtures of CO, H$_2$ and CO$_2$. The activity of the Boudouard reaction was found to be low, compared to the water–gas shift reaction, and diminished over time, suggesting that the temperature was too low for significant activity after an initiation period of CO adsorption. Furthermore, the rate of the Boudouard reaction has been reported to decrease in the presence of H$_2$O and H$_2$. The water–gas shift reaction was found to be the main reaction responsible for the production of CO$_2$ in a mixture of CO, H$_2$ and H$_2$O in the batch reactor. The ratio of the total amount of CO consumed to the total amount of CO$_2$ produced showed that the catalyst was also active towards hydrogenation, where the rate of the hydrogenation reaction was very much faster than the water–gas shift reaction. The resulting ratio of $\textit{p}$$_{H_2}$ to $\textit{p}$$_{CO}$ was found to be extremely low, probably leading to the production of long-chain hydrocarbons. The stoichiometry of the overall reaction was such that for every mole of CO$_2$ produced, 1.5 mol of CO was consumed in the batch reactor. Kinetic studies were performed in the batch reactor. An Eley-Rideal mechanism was found to provide a good agreement with the experimental results over a wide range of partial pressures of steam and CO.
Databáze: OpenAIRE
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