Kinetics Study of Reduction / Sulfidation of ZnO and

The reaction kinetics of fine particles of zinc oxide and zinc titanate with H2S were studied using a drop-tube furnace in order to test the potential of the sorbent injection hot-gas desulfurization process. Fine ZnO sorbent particles with diameter smaller than 50 tm were sulfided with H2S and/or reduced with H2 in a laminar flow reactor over the temperature range of 620-910 C. The reacted sorbent particles were separated from gas and size-classified using a cascade impactor and an absolute filter. Sulfidation conversion was measured by thermo-gravimetric analyses and compared for different particle sizes and reaction conditions. Other sorbents such as zinc titanate, metallic zinc, and ZnO with different porosity were also tested and compared. In the experiments of the reduction of ZnO without H2S, it was deduced from the change of size distribution of particles that a significant amount of Zn was formed and vaporized. On the other hand, the presence of H2S suppressed the change of size distribution of particles. This suggests that H2S suppresses the reductio