Promoting Effect of the Core-Shell Structure of MnO2@TiO2 Nanorods on SO2 Resistance in Hg0 Removal Process

Abstract

Sorbent of αMnO2 nanorods coating TiO2 shell (denoted as αMnO2-NR@TiO2) was prepared to investigate the elemental mercury (Hg0) removal performance in the presence of SO2. Due the core-shell structure, αMnO2-NR@TiO2 has a better SO2 resistance when compared to αMnO2 nanorods (denoted as αMnO2-NR). Kinetic studies have shown that both the sorption rates of αMnO2-NR and αMnO2-NR@TiO2, which can be described by pseudo second-order models and SO2 treatment, did not change the kinetic models for both the two catalysts. In contrast, X-ray photoelectron spectroscopy (XPS) results showed that, after reaction in the presence of SO2, S concentration on αMnO2-NR@TiO2 surface is lower than on αMnO2-NR surface, which demonstrated that TiO2 shell could effectively inhibit the SO2 diffusion onto MnO2 surface. Thermogravimetry-differential thermosgravimetry (TG-DTG) results further pointed that SO2 mainly react with TiO2 forming Ti(SO4)O in αMnO2-NR@TiO2, which will protect Mn from being deactivated by SO2. These results were the reason for the better SO2 resistance of αMnO2-NR@TiO2.

New Insight into Hg0 Oxidation over a Mn-Doped VWTi Catalyst at a Wide Temperature Window

“…Figure depicts the Mn 2p XPS curves for the Mn 3 -VWTi catalyst pretreated under different conditions. For all catalysts, the Mn 2p 3/2 peak could be fitted into three peaks attributed to Mn 2+ at 640.6 eV, Mn 3+ at 641.8 eV, and Mn 4+ at 643.5 eV. , Noting that V 4+ species increased after Mn loading (Figure S2), it could be speculated that there existed a synergistic interaction between Mn 2+ and V 5+ species, which could improve the V 4+ and Mn 4+ /Mn 3+ species probably ascribed to the redox cycle of Mn 2+ + V 5+ ↔ Mn 4+ /Mn 3+ + V 4+ shifting to the right. Similarly, Liu et al also found synergistic interaction between Mn and V, which could promote the adsorption and activation of NO and NH 3 , thus promoting the NO removal performance.…”

Editorial: Special Issue on “Advanced Strategies for Catalyst Design”

“…The work by He et al [5] deals with the removal of elementary mercury in the presence of SO 2 using Mn/Ti nanorods, showing how the coating with TiO 2 protects Mn by the unwanted deactivation by SO 2 .…”