Transient kinetics study of catalytic char gasification in carbon dioxide

Autor:	A.A. Lizzio, Ljubisa R. Radovic
Rok vydání:	1991
Předmět:	medicine.medical_specialty Chemistry General Chemical Engineering Inorganic chemistry Carbochemistry General Chemistry Decomposition Chemical reaction Industrial and Manufacturing Engineering Catalysis Chemical kinetics Desorption medicine Reactivity (chemistry) Char
Zdroj:	Industrial & Engineering Chemistry Research. 30:1735-1744
ISSN:	1520-5045 0888-5885
DOI:	10.1021/ie00056a009
Popis:	In this paper, the deactivation behavior of K, Ca, and Ni catalysts during carbon (char) gasification in CO{sub 2} is investigated. Correlations were sought between gasification rates and reactive surface areas (RSA) of the chars. In addition, the results allowed some speculation on recently proposed mechanisms of catalysis. An excellent correlation was found in the case of K catalysis, suggesting the rate-determining step in the overall mechanism to be the same as in the uncatalyzed reaction, i.e., desorption of the reactive C(O) intermediate. For the Ca-catalyzed reaction, the quality of the correlation depended on catalyst dispersion, suggesting that an additional process, besides the direct decomposition of the reactive C(O) intermediate, contributed to the transient evolution of CO (e.g., oxygen spillover). No correlation was found for Ni-catalyzed gasification; an oxygen-transfer mechanism is proposed to explain these findings. Mixed catalyst systems (Ca/K, K/Ni, Ca/Ni) were also studied. An excellent correlation between reactivity and RSA was observed in cases where the K-catalyzed reaction was dominant.
Databáze:	OpenAIRE
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