Bimetallic modification of MnFeOx nanobelts with Nb and Nd for enhanced low-temperature de-NOx performance and SO2 tolerance

Abstract

Nitrogen oxide (NOx) is one of the key factors contributing to air pollution, and selective catalytic reduction with ammonia (NH3-SCR) is widely used for denitrification (de-NOx). To effectively deal with the NOx pollution, it is urgent to develop efficient catalyst working at below 300 °C with a wide operating temperature window. Herein, a series of ferromanganese oxides (MnFeOx) nanobelts are bimetallically modified with niobium (Nb) and neodymium (Nd) for the first time via electrospinning method. The resultant MnFeNbNdOx catalysts present improved low-temperature de-NOx performance and sulfur dioxide (SO2) tolerance, particularly MnFeNb0.2Nd0.1Ox who achieves a NOx conversion up to over 90 % during the range of 120–330 °C and an enhanced tolerance of water (H2O) and SO2. Experimental and theoretical calculations confirm that strong adsorption of nitric oxide (NO) and ammonia (NH3) and weak adsorption of SO2 with the synergy of Nd, Nb and Mn enable MnFeNb0.2Nd0.1Ox excellent SCR activity and good SO2 tolerance. In-situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) further reveal that the de-NOx reaction over MnFeNb0.2Nd0.1Ox follows both Eley-Rideal (E-R) and Langmuir-Hinshel-wood (L-H) mechanisms. This study will inspire the further design and study of the synergy of transition metals and rare earth elements for de-NOx.