Study on NH₃-SCR Activity and HCl/H₂O Tolerance of Titanate-Nanotube-Supported MnO<i>_x</i>-CeO₂ Catalyst at Low Temperature

Abstract

Manganese oxide-cerium oxide supported on titanate nanotubes (i.e., MnCe/TiNTs) were prepared and their catalytic activities towards NH3-SCR of NO were tested. The results indicated that the MnCe/TiNT catalyst can achieve a high NO removal efficiency above 95% within the temperature range of 150–350 °C. Even after exposure to a HCl-containing atmosphere for 2 h, the NO removal efficiency of the MnCe/TiNT catalyst maintains at approximately 90% at 150 °C. This is attributed to the large specific surface area as well as the unique hollow tubular structure of TiNTs that exposes more Ce atoms, which preferentially react with HCl and thus protect the active Mn atoms. Moreover, the abundant OH groups on TiNTs serve as Brønsted acid sites and provide H protons to expel Cl atom from the catalyst surface. The irreversible deactivation caused by HCl can be alleviated by H2O. That is because the dissociated adsorption of H2O on TiNTs forms additional OH groups and relieves HCl poisoning.

Keywords

• titanate nanotubes
• manganese-cerium oxides
• low-temperature deNO<i>_x</i>
• HCl and H₂O poisoning