Modified Semi-Coke-Supported Cerium Oxide-Doped Zinc Ferrites for the Removal of H2S from Coal Gas

摘要

Cerium oxide-doped ZnFe2O4 sorbents supported on modified semi-coke (MSC) were prepared to improve the desulfurization efficiency of zinc ferrites. The sulfi-dation tests of the ZnFe2O4/MSC sorbents with and without Ce were carried out using a fixed-bed reactor at 450 °C. The effect of the CeO2/ZnFe2O4 molar ratio of the sorbents on the sulfur capacity was studied. The characteristics of the sorbents were analyzed by X-ray diffraction, N2 adsorption, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that cerium oxide could greatly improve the desulfurization reactivity of the ZnFe2O4/MSC sorbents. The molar ratio of Ce to Zn and Fe influences the desulfurization reactivity, and a good sulfur capacity of the sorbent can be obtained with a Ce/Zn/Fe ratio of 4:4:1. It was also found that the addition of CeO2 could enlarge the surface area and the pore volume, thus improving the dispersion of active components. Ce doping results in an increment of the oxygen adsorbed on the sorbent surface, which facilitates the adsorption of H2S. The Ce ions could act as carriers of the oxidation and reduction reactions and the oxygen transfer could be accelerated during the desulfurization process of coal gas.