Seawater-assisted synthesis of MnCe/zeolite-13X for removing elemental mercury from coal-fired flue gas

摘要

To develop an efficient and low-cost sorbent for removing elemental mercury (Hg-0) from chlorine-free coal-fired flue gas, the Na-13X zeolite (Z13X) was modified by the natural seawater and MnOx-CeO2. The elemental mercury removal activity over the developed sorbents was tested under a simulated coal-fired flue gas on a labscale fixed bed reactor. The novel sorbents were characterized by XRF, XRD, XPS, nitrogen adsorption and Hg-TPD. For the seawater-modified Z13X samples, the Cl species in the seawater were the main active species for Hg-0 removal. The optimal reaction temperature was in the range of 250-350 degrees C. For the seawater- and MnCe oxides- comodified sorbents, the experimental results suggested that the Cl species in the seawater and the loaded metal oxides were responsible for the superior Hg-0 capture activity. For the seawater modified sorbents, the best Hg-0 capture activity could be achieved with loading only 1 wt% metal oxides on the Z13X. The elemental mercury removal activity tests showed that the co-modified sorbents exhibited superior and stable elemental mercury removal efficiency ( 95%) for temperatures between 200 degrees C and 350 degrees C and with a flow rate-to-mass value of 2 x 10(5) mL/(h.g). Based on the XPS results of the surface Cl, O and metals species, the active chlorine species generated from the reactions between the adsorbed seawater chlorine and the metal oxides were responsible for enhancing the performance.