Reforming of coal volatiles over ilmenite ore

Chemical-looping combustion is one of the most promising technologies for generating electricity from coal with high CO2 capture. This process burns the fuel with the oxygen from metal oxide particles in the fuel reactor while the depleted oxygen in the metal oxides is compensated for in the air reactor. This study investigated the performance of ilmenite as an oxygen carrier during the steam reforming when actual coal volatiles are used as fuel. Steam reforming experiments on coal volatiles with ilmenite were carried out in a two-stage fixed-bed reactor under various steam conditions. The effect of pre-oxidation and of steam ratios on the conversion reactivity of ilmenite was investigated at 1173 K. The conversion reactivity of ilmenite was greatly enhanced after pre-oxidation, and there was no tar formation when pre-oxidized ilmenite was used. The internal and external porosity of ilmenite also increased after steam reforming of coal volatiles. Ilmenite showed good performance under the various steam conditions. Carbon formation decreased considerably as steam ratios increased. Moreover, the reduced phase FeTiO3 of ilmenite was maintained with the addition of steam, and its reactivity was relatively stable compared with a synthetic iron-based carrier, Fe2O3/Al2O3.