Structure-activity relationship and the inhibitory effect of sulfur dioxide and water on nitrous oxide formation in selective catalytic reduction of nitrogen oxides by ammonia over hollow Co3O4@CoMn2O4 catalyst

Abstract

Hollow structures have attracted great interest in many areas for their diverse applications. In this work, a new catalyst with an open and hollow structure (Co₃O₄@CoMn₂O₄) is designed for selective catalytic reduction of nitrogen oxides by ammonia (NH₃-SCR). The as-prepared hollow-structured catalyst provides a high surface area and has thin shells. Owing to its structural benefits, this catalyst exhibited enhanced nitrogen oxides (NO_x) removal activity and better resistance to water and sulfur dioxide than cobalt manganate nanoparticles. It also has proved that both the Eley-Rideal and Langmuir-Hinshelwood mechanisms are present in the NH₃-SCR process in this catalyst. The improved nitrogen selectivity after the addition of water and sulfur dioxide occurs owing to the inhibition of nitrous oxide formation through the Eley-Rideal and Langmuir-Hinshelwood mechanisms. The deep insight into the structure-activity relationship and the influence of water and sulfur dioxide on nitrogen selectivity provide a new perspective for constructing high-performance de-NO_x catalysts.

Keywords: CoMn(2)O(4); Hollow structures; Nitrogen oxides; Selective catalytic reduction; ZIF-67.