Mercury removal from syngas by metal oxides based adsorbent: A review

The injection of adsorbent can effectively remove Hg from syngas, in which metal oxide based adsorbent (MOBA) is a promising adsorbent as their simultaneous adsorption and oxidation properties. This review summarized the influences and mechanisms of adsorbent composition, syngas component, and reaction temperature on Hg-0 removal by MOBA in syngas. The adsorption of Hg-0 by CeO2-based, Fe2O3-based, CuO-based, and V2O5-based MOBA belong to physisorption, the adsorption of Hg-0 by MnO2 and Co3O4 belong to chemisorption. The oxidation of Hg-0 by MOBA follows Mars-Maessen mechanism. The Hg-0 removal capacity of MOBA with different composition follows the descending sequence of V2O5 > MnO2 > Co3O4 > Fe2O3 > CuO(CeO2). H2S and HCl are beneficial to Hg-0 removal by MOBA, but CO, H-2, and H2O are harmful to Hg-0 removal by MOBA. The influence of H2S, HCl, and CO are affected by their concentration. Both HCl and H2S can mitigate the inhibition of CO and H-2 on Hg-0 removal by MOBA. The increase of temperature can both promote and inhibit Hg-0 removal by MOBA. In addition, the advantages and disadvantages of three main regeneration methods of thermal regeneration, non-thermal plasma regeneration, and elution regeneration were respectively summarized, especially the prominent advantages of elution regeneration method were emphasized. Finally, further works about the development of spine MOBA, the synergistic removal of Hg-0 and H2S by MOBA, study at higher temperature range, and the application of elution regeneration method were summarized to provide some references for the application of MOBA on Hg-0 removal in syngas.