Preparation and Desulfurization Behavior of Zinc Oxide Based Sorbent for Moderate Temperature

Zinc oxide based moderate-temperature sorbents were obtained by mixing active zinc oxide with other additives, shaping, drying and calcinating in a given order. The influences of preparation conditions on the desulfurization behaviors for the prepared ZnO based desulfurization sorbent were carried out in simulated coal gas using a fixed-bed reactor. The changes of crystal phase before and after desulfurization were characterized by XRD. The experimental results showed that ZnO based desulfurization sorbent was effective for removing H₂S in simulating coal gas at 300°C, space velocity 2000 h-1. When H₂S concentration in inlet gas was 1100 mg/m³ and H₂S concentration in outlet gas was no more than 0.1 mg/m³, the accumulated sorption sulfur capacity in the prepared ZnO based desulfurization sorbent reached 12 wt.%. But there is carbonyl sulfide in outlet gas during desulfurization process, and carbonyl sulfide concentration in outlet gas approached 40 mg/m³ as H₂S concentration in out gas breakthrough. Both the decomposition temperature for precursor basic zinc carbonate and the additives for ZnO based sorbent influenced the desulfurization behavior of the prepared desulfurization sorbent. The best preparation conditions are shown in the following: both the decomposition temperature of basic zinc carbonated and the calcination temperature of ZnO sorbent are 500°C; the additive is graphite.