Catalytic CO2 gasification of coal char with Ca/K compounds in a mic-fluidized bed reactor

In this study, the effects of gasification temperature (860, 890, 920, 950 °C) and catalyst loading (Ca: 0.5%, 1%, 1.5%, 2%; K: 3%, 5%, 7%) on the catalytic performance of Ca and K-based catalysts for coal char gasification were investigated using a Micro Fluidized Bed Reaction Analyzer. The results indicated that increasing the gasification temperature can improve the gasification performance. The residual sintering of Ca catalyst with a loading amount exceeding 1.5% blocked the active sites, leading to a decrease in gasification reactivity. A threshold of the K catalyst loading amount, beyond 5% the catalytic effect will not be enhanced. At 950 °C, the Ca and K catalysts exhibited the strongest catalytic effects at loading ratios of 1.5% and 5%, and the complete reaction times were 125.2 s and 150.1 s with activation energies of 147.81 kJ·mol−1 and 147.65 kJ·mol−1, respectively. In binary catalyst systems, the evaporation of K2CO3 at high temperatures can promote the dispersion of Ca(OH)2, prevent its agglomeration, and inhibit sintering. The binary catalyst of 0.5% Ca +5% K exhibited the best synergistic effect with the activation energy was reduced to 112.5 kJ·mol−1.