Doping regulation increased SCR activity, selectivity, and hydrothermal stability of Mn-based cordierite catalyst

Abstract

Mn-based catalyst is widely investigated in selective catalytic reduction (SCR) of nitrogen oxide (NO), and shows high NO conversion at low temperatures. However, most reports emphasize on powder catalyst instead of monolithic one. In this work, Mn-containing cordierite honeycomb and CeWFe co-doping comparisons were synthesized and applied in SCR. As a result, MnCeWFe showed the best catalytic activity, selectivity, temperature window, and hydrothermal stability. It removed 90.4% of NO together with a selectivity of 97.7% at 150 °C, and removed over 90% of NO from 150 °C to 250 °C. Even after a hydrothermal treatment, the activity of MnCeWFe was only decreased from 90.4% to 75.4% at 150 °C. In comparison, the activity of Mn was decreased from 60.7% to 32.4%. According to X-ray photoelectron spectroscopy and Diffuse Reflection Fourier Transform Infrared, CeWFe co-doping made the ratio between Mn3+ and Mn4+ close to 1:1, maintained this ratio under hydrothermal environment, and carried out SCR by both Eley-Rideal and Langmuir-Hinshelwood mechanisms, thus resulting in good performances. This work is in favor of developing an effective catalyst for industrial application.