Abstract:
Aiming at the difficulty of elemental mercury (Hg
0) removal from flue gas due to its indissolubility in water and the problem of lower SO
2 resistance performance of manganese-based adsorbent, the MnO
x-TiO
2 adsorbents prepared with impregnation (IM), sol-gel (SG) and deposition-precipitation method (DP) were employed to remove Hg
0 in the absence and presence of SO
2. The adsorbents were characterized by N
2 adsorption-desorption, TG-DSC, XRD, TEM, H
2-TPR, and XPS techniques. The results showed that Hg
0 removal performance over MnO
x-TiO
2 adsorbents was markedly influenced by the preparation methods. The adsorbent prepared by DP method exhibited a superior activity for Hg
0 adsorption and the best SO
2 resistance performance. The characterization results indicated that the Hg
0 removal activity did not correlate with the BET surface area. The preparation method of deposition-precipitation could not only lead to an increase of reducibility and high dispersion of MnO
x, but also significantly enhance a migration of well-dispersed active phase from bulk to surface, resulting in a higher Mn
4+/Mn ratio and the presence of abundant chemisorbed oxygen, which would play an important role in promoting Hg
0 removal.