Mechanistic insights into NH-assisted selective reduction of NO on CeO: a first-principles microkinetic study on selectivity and activity.

To understand the activity- and selectivity-limiting factors of selective catalytic reduction of NO with NH (NH-SCR) catalyzed by CeO-based oxides, a molecular-level mechanistic exploration was performed on CeO(110) using a first-principles microkinetic study. Herein, the favored reaction pathway for N formation on CeO(110) is unveiled, which includes three key subprocesses. (i) NH adsorbs on the Ce site and dissociates into *NH assisted by O; (ii) *NH preferentially couples with NO adsorbed on O (ONO#), forming *NHNO on the Ce site; (iii) *NHNO undergoes dehydrogenation into *NHNO, which can be easily anchored by O and can then decompose into N. The quantitative microkinetic results show that the transfer of NHNO from Ce to O, rather than the further conversion of NO to N on O, emerges as the N selectivity-determining step on CeO, in which O plays a key role. The number of O is an important factor determining the N selectivity of CeO-based catalysts. The sensitivity analysis reveals that NHNO formation, , *NH + ONO# → *NHNO + O#, is the rate-determining step for NH-SCR on the CeO catalyst; accordingly, enhancing NH adsorption could be an effective strategy to boost the catalytic activity of CeO for NH-SCR. In general, creating O on CeO and introducing components (, WO) with strong NH adsorption would be efficient for designing CeO-based catalysts with superior N selectivity and activity. These results could provide a consolidated theoretical basis for understanding and optimizing CeO-based catalysts for NH-SCR.