Abstract:A highly effective desulphurization agent (PSAC-I) was prepared by impregnating sodium carbonate on pitch-based spherical activated carbon (PSAC). The PSAC-I before and after desulphurization was characterized using nitrogen adsorption，FT-IR，thermogravimetry and elemental analysis to study desulphurization products and causes to deactivation on PSAC-I. The effects of temperature and relative humidity on the performance of PSAC-I for H2S removal were also investigated. The results reveal that PSAC impregnated with Na2CO3 has much larger capacity to remove hydrogen sulfide than common coal-based activated carbon and commercial desulphurization agent. Elemental sulfur is the main product after desulphurization, and a little amount of sulfuric acid is also produced on PSAC-I. When the pores are completely saturated or all the entrances of the pores are jammed by the products, PSAC-I will be deactivation. 30 ℃ is the optimal temperature for the desulphurization process while higher or lower than that will lead to rapid deactivation. Increasing the relative humidity of the inlet gas will improve the sulfur capacity of the PSAC-I.