Variation of Char Reactivity during Catalytic Gasification with Steam: Comparison among Catalytic Gasification by Ion-Exchangeable Na, Ca, and Na/Ca Mixture

Abstract

The reactivity profile of char during catalytic gasification is crucial for designing and optimizing the gasification process, and it is greatly affected by the types and changes in activity of the catalyst during gasification. The catalytic gasification of Na-Char, Ca-Char, and Na/Ca-Char mixtures with different concentrations of steam was conducted within the temperature range of 700–900 °C using a microfluidized bed reaction analyzer. The results indicate that the reactivity of Na-Char is always higher than that of Ca-Char during the initial gasification stage (0–Xi) and then lower than that of Ca-Char in the later stage. The observations are mainly attributed to the different deactivation paths for the Na and Ca catalysts. The drastic loss of Na during gasification corresponds well to the sharp decrease of Na-Char reactivity within the initial carbon conversion, and the gradual change of the Ca dispersion contributes to the deactivation of the Ca catalyst. It is also demonstrated that the catalysis of...