Catalytic Effect of Metal Species on Enhancement of CO2 Gasification Reactivity of Biomass Char

Abstract

In the Boudouard reaction, where CO2 is reacted with carbon (char) to produce CO, very high temperatures are required to shift the equilibrium towards CO production. This endothermic reaction is inherently slow and catalytic species are effective to speed up the reaction rate at temperatures below 900 °C. In this study, the catalytic effect of some alkali (K, Na), alkaline earth (Ca) and transition (Fe) metals on enhancing the CO2 gasification reactivity of pistachio shell (PS) char was investigated. The CO2 gasification studies were performed in a Thermogravimetric analyzer (TGA). Among the examined potassium species, K2CO3 showed the highest catalytic effect; wherein, complete carbon conversion was achieved 48.1% faster as compared to un-catalyzed PS char. The highest catalytic effect among the sodium salts was devoted to NaNO3 which showed 57.7% enhancement in the reactivity of char. CaCl2 and Fe(NO3)2 also showed the best catalytic performance among the examined calcium and iron species and improved the reaction rate by 64.6 and 46.1%, respectively.