Rationally Designed Confined Structure Ce-Mn-TNTs Catalyst for Low-Temperature NH<sub>3</sub>-SCR Reaction with Superior Activity and H<sub>2</sub>O/SO<sub>2</sub> Tolerance
Qiang Zhao, Xiaosheng Huang, Tian Zhao, Rongji Cui, Jiyi Zhang, Zhicheng Tang
Abstract
The SO 2 tolerance of catalysts is often the key factor limiting their catalytic activity during practical applications for low-temperature NH 3 -SCR reaction. There has been no in-depth research and exploration on the confined location of active components so far. In this work, we investigated the activity and SO 2 tolerance of catalysts by loading Mn into cerium-titanium nanotubes (Ce-TNTs) in three different ways. It was found that the Ce-Mn-TNT catalyst with Mn confined in a nanotube structure by the direct strong alkali hydrothermal method showed excellent catalytic activity and strong resistance to SO 2 and H 2 O. This was mainly due to the unique nanotube structure, which provided a large specific surface area and promoted uniform dispersion of active sites. Importantly, the confinement effect of the nanotube structure accelerated the electron transfer rate among Ce, Mn, and Ti metals, which enhanced the redox performance of the catalyst and improved the resistance to SO 2 . In addition, it was also found that the introduction of Mn increased the amounts of weak acid sites and inhibited oxygen inhibition, enhanced the adsorption of NO on the catalyst surface, and formed more lattice defect structures. Finally, the possible reaction mechanism of the Ce-Mn-TNT catalyst was investigated by in situ DRIFTs. When the gas reaction temperature was 200 °C, it was found that the E-R and L-H reaction pathways coexisted in the NH 3 -SCR reaction when SO 2 was present in the reaction atmosphere.