Comparative study on N2O formation pathways over bulk MoO3 and MoO3-x nanosheets decorated Fe2O3-containing solid waste NH3-SCR catalysts

NH 3 -SCR technology with commercialized V 2 O 5 -WO 3 (MoO 3 )/TiO 2 catalysts has become the most efficient technology for the removal of NO x from coal-fired power plants. However, the weaknesses of V 2 O 5 -WO 3 (MoO 3 )/TiO 2 catalysts such as the biotoxicity of vanadium species and high cost restrict their increased applicability. Fe 2 O 3 -based NH 3 -SCR catalysts show potential in placing traditional catalysts due to their good N 2 selectivity, excellent environmentally friendly performance, high thermal stability, and low cost. In this work, low cost Fe 2 O 3 -containing solid waste was exploited as the base material for NH 3 -SCR catalyst preparing. Moreover, bulk MoO 3 and MoO 3-x nanosheets decorated Fe 2 O 3 composite NH 3 -SCR catalysts were synthesized and both revealed conspicuously improved NO x removal efficiency compared with bare-Fe 2 O 3 catalyst. However, the N 2 selectivity of these two catalysts showed significant differences. Therefore, comprehensive characterizations, NH 3 oxidation experiments, and in-situ diffusion Fourier transform infrared spectroscopy (DRIFTS) experiments were performed to determine the N 2 O formation pathways of the above two catalysts. The redox properties were highly related to the N 2 O generated from NH 3 oxidation. Moreover, the huge difference in NH 3 and NO adsorption ability led to disparate reaction mechanisms over the two catalysts. This new understanding of the N 2 O formation mechanism has the potential to guide the rational design of improved NH 3 -SCR catalysts suffering from low N 2 selectivity.