Zinc oxide (ZnO) is a widely used sorbent for H₂S removal at low temperatures, ca. 400 °C. In this study, nine different transition metal doped ZnO sorbents were prepared and loaded on SiO₂ particles (100-200 µm) by incipient wetness impregnation for H₂S removal at stack temperatures of PEM fuel cells. The results of desulfurization tests on these sorbents at room temperature indicates that a copper doped ZnO/SiO₂ sorbent (Cu-ZnO/SiO₂) had the highest saturation sulfur capacity at 0.213 g sulfur/g ZnO (54% of the theoretical capacity) which was two times higher than that of ZnO/SiO₂ sorbent at room temperature. In these experiments, CO₂, CO and water did not demonstrate significant effects on the desulfurization performance of Cu-ZnO/SiO₂. The addition of copper to ZnO/SiO₂ made the sorbents more sensitive to desulfurization temperature in a low temperature range of 100-250 °C. Compared with a widely used commercial ZnO sorbents, ZnO/SiO₂ and Cu-ZnO/SiO₂ were highly regenerable. Cu-ZnO/SiO₂ can be regenerated at a low regeneration temperature, ca. 300 °C, which is 200-300 °C lower than these of ZnO/SiO₂ and the commercial sorbent. The microfibrous entrapped Cu-ZnO/SiO₂ sorbent can be applied as an inline filter to protect the fuel cell from sulfur poisoning.

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