Sm-modified Mn-Ce oxides supported on cordierite as monolithic catalyst for the low-temperature reduction of nitrogen oxides
Nitrogen oxides (NO x ) are typical atmospheric pollutants that harm the environment and human body, and selective catalytic reduction (SCR) with NH 3 is one of the most effective technologies to deal with NO x emissions at present. In this work, a monolithic catalyst, Sm-modified Mn-Ce composite oxides (Sm-MnCe) supported on cordierite (CC), is prepared by impregnation for the first time, and their denitration (de-NO x ) performance in NH 3 -SCR reaction is evaluated in detail. The results show that 0.1Sm-MnCe/CC (Sm/Mn mole ratio is 0.1) has the best de-NO x efficiency with above 80 % NO x conversion from 60° to 270°C, and the high NO x conversion can be maintained within 15 h in the presence of 100 ppm SO 2 . It is found that appropriate introduction of Sm increases the specific surface area and acid sites, improves the redox environment, elevates the content of Mn 4+ on the catalyst surface, which are conducive to the improvement of catalytic activity. In addition, the interaction between active components (Sm, Mn and Ce) also plays a positive role for the excellent de-NO x activity. It is revealed by in-situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) that the NH 3 -SCR reaction over the 0.1Sm-MnCe/CC catalyst follows Eley-Rideal (E-R) and Langmuir-Hinshel (L-H) mechanisms. This work provides ideas for the preparation and modification of monolithic catalysts, which is conducive to promoting the practical industrial application of low-temperature SCR de-NO x technology.
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