Some new insights into the synergy occurring during char gasification in CO2/H2O mixtures

Abstract This study aimed to investigate the mutual effects of CO2, H2O, and their mixtures on char reactivity and to explore the essence of the observed interaction between CO2 and H2O during char gasification. A Y-type dual fixed-bed (DFB) reactor was designed for gasification studies, which allowed direct comparison of product gas compositions between the separate and mixed gasification modes. Experimental and analytical data provided conclusive evidence of synergistic interaction between CO2 and H2O during gasification in mixed atmospheres. The results revealed that H2O played a role in promoting the development of mesopores, which allowed CO2 to enter the micropores more rapidly and to contribute to the observed synergy. This observed synergy increased with the increasing volume fraction of the reactant gases, while it decreased with the rising gasification temperature.