Nature, activity and stability of active sites during alkali metal carbonate-catalysed gasification reactions of coal char
✍ Scribed by Teus Wigmans; Hans Haringa; Jacob A. Moulijn
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 635 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0016-2361
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✦ Synopsis
The activity pattern of potassium carbonate-containing coal char during gasification with low pressures of steam, is shown to consist of at least three stages of activity. The relative importance of these stages, that occur at different burn-off levels, is influenced by the pretreatment temperature, the catalyst loading and the sequence of catalyst addition and coal pyrolysis. An explanation for this is given, based on the assumption of three processes occurring simultaneously during pretreatment: oxygen retention by potassium, intercalation of potassium and potassium carbonate crystallization. Comparison with activated carbon results supports the interpretation of the results. It follows that the maximum activity of alkali metals correlates with the oxygen content of carbon and that intercalation depends on the degree of graphitization of carbon