Substrate engineering-enhanced low-temperature NO<sub>x</sub> and CO removal by Co<sub>1</sub>Mn<sub>2</sub>O<sub>x</sub>@CuO/copper mesh monolithic catalyst.

Abstract

This paper addresses the challenges of simultaneously removing nitrogen oxides (NO_x) and carbon monoxide (CO) from industrial flue gas at low temperatures. A highly efficient Co₁Mn₂O_x@CuO/copper mesh (CM) monolithic catalyst with higher oxygen vacancies was developed by growing Cu(OH)₂ nanorods in-situ on a copper mesh and subsequently synthesizing via a hydrothermal method. Experimental results show that the Co₁Mn₂O_x@CuO/CM catalyst can achieve 99.7 % NO_x conversion and 99.4 % CO conversion at 160 °C, with strong resistance to H₂O and SO₂ and outstanding long-term stability. Characterization results demonstrated that the excellent catalytic performance can be ascribed to the presence of abundant high-valent Co³⁺, Mn⁴⁺, and Cu²⁺ species, an increased number of reducible species, more acidic sites, and a higher concentration of oxygen vacancies. The interaction between ammonia-based selective catalytic reduction (NH₃-SCR) and CO oxidation reactions revealed that NH₃ primarily inhibited CO oxidation, whereas CO had no significant inhibitory effect on NH₃-SCR. Additionally, this study explored the factors contributing to the enhanced water resistance and the underlying mechanisms of both NH₃-SCR and CO oxidation reactions using in-situ diffuse reflectance infrared transform spectroscopy (in-situ DRIFTS). In terms of application, computational fluid dynamics (CFD) simulations demonstrated that the copper mesh-based monolithic catalyst provided better heat distribution, preventing partial deactivation and contributed to the improvement of catalytic activity. This research provides an efficient solution for industrial flue gas treatment and highlights its potential for environmental applications.