Ni enhanced reactivity of Fe/TiO2 for selective catalytic reduction of NO with CO and the mechanism investigation

The effect of surface synergetic oxygen vacancy constructed by bimetallic metal on CO selective catalytic reduction of NOx (CO-SCR) was investigated by loading Fe and Ni on TiO2. Herein, a series of NixFe1−x/TiO2 was prepared by the wet impregnation method. The microstructures, elemental states, and reactivity of the prepared samples were characterized by XRD, HRTEM, EPR, H2-TPD, CO-TPD, NO-TPD, and XPS. The results show that the synergistic effect between Ni and Fe effectively optimized the dispersion of Fe and constructed abundant Ni-O-Fe bonds. Furthermore, the excellent CO trapping capacity led to an increased number of cNi-□-Fe structures (SSOV), which effectively promotes NO activation at low temperatures. The in situ DRIFT spectra illustrated that N2O intermediate species rapidly transformed into N2-based species at 250 ℃, and the catalyst modified with Ni presented excellent NO conversion and N2 selectivity. The Ni0.2Fe0.8/TiO2 sample demonstrated almost 100% NO conversion, 93% N2 selectivity, and considerable stability with a gas hourly space velocity of 33,000 h-1 at 250 ℃. This work provides a novel way for the design and preparation of a bimetallic NO reduction catalyst to promote the further study of efficient CO-SCR catalysts.