Reaction Mechanisms and Low-Temperature Performance of Cu-Doped Magnesium-Based Catalysts for NOx Removal with Enhanced Sulfur Resistance

Abstract

The simultaneous removal of nitrogen oxides (NOx) at low temperatures with high catalytic efficiency and strong sulfur resistance remains a major challenge in environmental catalysis. In this study, a novel magnesium-based catalyst was prepared via the sol-gel method, with calcination temperature and copper (Cu) doping used as key parameters to optimize catalytic performance. The results show that Cu doping significantly improved the dispersion of active catalytic sites, broadened the operating temperature window, and enhanced low-temperature catalytic activity. Among the magnesium-based catalysts, the sample calcined at 600 °C exhibited the highest NOx removal efficiency, reaching 73.75% at flue gas temperatures above 160 °C. Notably, Cu doping further improved the denitrification performance of the catalyst calcined at 500 °C, achieving a NOx conversion rate of 82.7%, which highlights its potential as an efficient low-temperature catalyst. Comprehensive characterization by BET, XRD, SEM, and NH3-TPD revealed that Cu doping preserved the crystal structure and surface functional groups of the magnesium-based catalyst while significantly increasing surface acidity and the density of active acid sites. In addition, Cu doping markedly enhanced the sulfur resistance of the catalyst, overcoming a key limitation for industrial application. This study provides an effective and environmentally sustainable NOx removal strategy for magnesium kiln industries and other small- to medium-scale industrial operations, offering a promising pathway toward greener industrial processes.

Graphical Abstract