Preparation and evaluation of iron nanoparticles embedded CNTs grown on ZSM-5 as catalysts for NO decomposition

Due to their high activity and selectivity, single-atoms based catalysts for oxygen removal and wastewater treatment have received enormous attentions in academia and industry. The present work sought to extend the single-atom catalyst concept to NO decomposition. A series of catalysts with highly dispersed iron nanoparticles embedded in carbon nanotubes grown on a ZSM-5 zeolite were prepared using an induced growth method, by pyrolysing melamine and ferric nitrate precursors impregnated on ZSM-5 at 900 degrees C. The catalysts were then tested for their catalytic activity in NO decomposition using a fixed-bed reactor operating at 300 degrees C and were shown to be able to completely decompose NO under the test conditions. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), BET, Raman and temperature-programmed oxidation (TPO) were used to study the effects of molar ratio of ferric nitrate to melamine on the active species, sample structures and NO decomposition mechanism. An increase in the molar ratio of melamine to iron nitrate led to an improvement to the dispersibility of iron nanoparticles and enhancement of NO decomposition. The use of ZSM-5 increased the dispersion of iron, thus enhancing the catalytic decomposition of NO. The characterisation of the used catalysts revealed that it was possible to regenerate the catalytic activity by doping and pyrolysing the deactivated catalysts with melamine, with no significant difference to that of the fresh catalysts.