Surface Effects of Trace CuMnCe Loading on Coal-Based Carbon Materials and Mechanisms of NO_<i>x</i> Adsorption and Removal

Abstract

This study employed the water-thermal coupled high-temperature CO2 gasification method using Zhundong coal as the raw material to prepare porous carbon materials. A dual-function catalyst for NOx adsorption and reduction was prepared by loading Cu, Mn, and Ce components onto the carbon material through hydrothermal impregnation. The influence of metal loading content on the pore structure, surface functional groups, and synergistic effects between metals in the carbon-based catalyst was investigated during the preparation process. In the process of NOx removal using carbon-based catalysts, the primary components comprise two distinct phases: NOx adsorption and CO-SCR experiments. The experimental sequence involves the initial execution of NOx adsorption tests, succeeded by subsequent reduction treatments. These processes are undertaken systematically to comprehensively investigate the attributes of the catalyst. The physical and chemical parameters of the samples were characterized using XRD, Raman, H2-TPR, NOx-TPD, and other techniques. Finally, the NOx adsorption and reduction mechanism of representative samples were deeply analyzed using in situ DRIFTS. The results showed that when the loading amounts of Cu, Mn, and Ce were 0.006, 0.012, and 0.003 g, respectively, the pore structure of the catalyst was excellent, with a NOx adsorption performance (qe) of 16.23 mg/g, and the NO conversion rate reached 66% at 200 °C. This is mainly attributed to the enhanced interaction between metal species on the catalyst surface by optimizing the metal content on the carbon support, which promotes the dissociation of NO in the NO + CO reaction. In situ DRIFTS results confirmed that NO and CO adsorb on the catalyst surface, and CO* reacts with NO* to produce N2 and CO2, following the Langmuir–Hinshelwood mechanism.