Synthesis of CeMnOδ/3DOM Ti1−xWxOy catalysts: catalytic performance and reaction mechanism for the simultaneous removal of soot and NOx

Abstract

The reduction and elimination of soot particles (PM) and nitrogen oxides (NO_x) emitted by diesel engines are of paramount importance and urgent necessity. Herein, a family of novel CeMnO_δ/3DOM Ti_1−xW_xO_y catalysts was prepared using the colloidal crystal template method and incipient-wetness impregnation method. The catalytic performance of the CeMnO_δ/3DOM Ti_1−xW_xO_y catalysts for the simultaneous abatement of soot and NO_x was investigated by adjusting the molar ratio of Ti and W in the 3DOM Ti_1−xW_xO_y carriers. The results show that when the Ti : W molar ratio is 7 : 3, the temperature corresponding to the highest soot oxidation activity is 488 °C, and at this ratio, the catalyst not only exhibits the highest NO conversion rate of 99.2% but also has the widest NO conversion window (216–377 °C) over a 90% conversion rate among the as-prepared catalysts; at the same time, it also demonstrates excellent stability. Moreover, the selectivity for N₂ is improved by the component of W in the support. The enhanced catalytic activity of the CeMnO_δ/3DOM Ti₇W₃O_y catalyst can be ascribed to its macroporous structure, sufficient surface acid sites and oxygen vacancies, and the synergistic effects between different elements. This study also proposes the potential reaction mechanisms of CeMnO_δ/3DOM Ti_1−xW_xO_y catalysts and offers valuable insights into the design and synthesis of high-efficiency catalysts for the purification of soot and NO_x.