Synthesis of CenTiOx flakes with hierarchical structure and its enhanced activity for selective catalytic reduction of NOx with NH3

Abstract

Herein, a series of CenTiOx (n = 0.068, 0.15, 0.21 and 0.30) flakes with hierarchical structure was prepared by alcoholysis under solvothermal conditions and explored for the selective catalytic reduction (SCR) of NOx with NH3. The morphology of the CenTiOx flakes was related to the Ce doping content. Remarkably, the flakes morphology of catalyst greatly promoted the SCR activity derived from the strong interaction between the Ce and Ti oxides. Among these samples, the Ce0.21TiOx with rod-like hierarchical structures demonstrated good SCR activity that the NO conversion was still over 90% from 270 °C to 450 °C even under SO2 and H2O. Various characterizations clarified that the good activity over Ce0.21TiOx was due to the increase of BET surface area (195 m2/g), surface Ce3+ amount and surface Oα species. In-situ DRIFTS was conducted to determine the distribution and reactivity of surface acid sites. The results demonstrated that there was a direct correlation between the coverage of the Brønsted acid sites and the NO conversion. Eley-Rideal (E-R) mechanism is the most likely to represent the reaction mechanism on Ce0.21TiOx catalyst.