Promoting effect of Ti addition on three-dimensionally ordered macroporous Mn-Ce catalysts for NH3-SCR reaction: Enhanced N2 selectivity and remarkable water resistance

A series of 3DOM-Mn x Ce y Ti z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn 3 Ce 1 catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO x resulted in the nonselective oxidation of NH 3 and generation of N 2 O, decreasing the N 2 selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn 3 Ce 1 Ti 1 catalyst decreased, and the NH 3 were strongly adsorbed on the acid sites, which enhanced the N 2 selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h −1 . Furthermore, both the 3DOM-Mn 3 Ce 1 and 3DOM-Mn 3 Ce 1 Ti 1 catalysts showed remarkable tolerance of H 2 O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn 3 Ce 1 Ti 1 catalyst.