Southern pines char gasification with CO2—Kinetics and effect of alkali and alkaline earth metals

• Southern pine char was gasified in a fixed bed reactor.
• RPM predicted the experimental data best among three different models.
• Chars loaded with metal catalysts were gasified and their kinetic parameters were predicted.
• The activity of the metals was observed in the order of: K-char > Ca-char > Na-char ≥ Mg-char.
• The reduction of activation energy was the most significant for K-char (ΔEa = 114 kJ/mol).

Carbon dioxide gasification of southern pine char was carried out in a fixed bed reactor at temperatures in the range of 800 °C–975 °C. Evolution of carbon monoxide was used as the basis for conversion. The conversion versus time data were fitted to three different solid-gas reaction models: volume reaction model (VRM); non-reactive core model (NRC) and random pore model (RPM). Regression analysis showed that the RPM was the best at predicting experimental data. The measured change in char surface area was in agreement with the change in surface area predicted by the RPM. Furthermore, the RPM was used to predict the kinetic parameters of gasification of chars that were loaded with alkali and alkaline earth metals such as Na, Mg, K and Ca. The reduction in activation energy and hence increase in gasification reactivity was highest for potassium followed by calcium, sodium and magnesium. The pore structure parameter was highest for sodium implying a significant change in surface area of the char with initial conversion.

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