Study of Hg0 removal characteristics on Fe2O3 with H2S

• Different reaction temperatures significantly influented the Hg0 oxidation.
• The Hg0 captured by the Fe2O3 sorbents could re-release at the certain temperatures.
• We carried on a qualitative analysis of foundational mercury adsorptive products by TG/DSC.
• The probable products are deduced through the morphological characterization by XPS.

A series of elemental mercury removal experiments were performed at different temperatures to explore the elemental mercury oxidation efficiency on α-Fe2O3 and γ-Fe2O3 in the presence of H2S. Our experimental results indicated that the α-Fe2O3 and γ-Fe2O3 similarly played important roles in removing elemental mercury. The reaction temperature around 230 °C is a critical turning point in effectively capturing elemental mercury, above which the Hg0 removal efficiency would decrease. According to our previous researches, H2S will preferentially adsorb on the Fe2O3 surface, forming active sulfur sites to react with Hg0. In this paper, we analyzed the contrastive samples before and after removing Hg0 to further investigate the probable products by the Hg0 re-release experiments, as well as thermogravimetry–differential scanning calorimeter (TG–DSC) and X-ray photoelectron spectroscopy (XPS) analysis. The test results of morphological characterization showed that mercury compounds and new substances generated in the Fe2O3 samples after adsorbing Hg0. At the same time, the detection results showed that Hg2+, sulfur, S2−, S− and Fe2+ had appeared, which demonstrated the probable mercury products, and the H2S pre-adsorption and Hg0 oxidation could be confirmed as well by the different groups of comparative tests. In conclusion, our experimental results are in good agreement with our previous experiments and computational results.