Ceria−Zirconia High-Temperature Desulfurization Sorbents

Abstract

Ceria and ceria−zirconia desulfurization sorbents containing up to 20 mol % ZrO2 were prepared using a coprecipitation method. XRD analysis indicated the formation of solid solutions of ZrO2 in CeO2. ZrO2 addition produced larger specific surface area, improved sintering resistance, and increased the reducibility of the ceria. Desulfurization was studied using a laboratory-scale fixed-bed quartz reactor. Special precautions were taken to minimize interaction between sub-ppmv concentrations of H2S with stainless steel and eliminate contamination from residual sulfur in the reactor system. The performance of sorbents containing ZrO2 was superior to that of ZrO2-free sorbents. Product gas concentrations in the range of 0.1−0.2 ppmv H2S were achieved during the prebreakthrough period over the temperature range of 600−750 °C. In particular, the duration of the sub-ppmv prebreakthrough period lasted as much as twice as long when the sorbent contained 20 mol % ZrO2 compared to ZrO2-free CeO2.