Low-cost Co–Al spinel and M–Co–Al (M = Fe and Ce) catalysts for selective catalytic reduction of NO x with NH 3

In this work, the Co–Al spinel catalyst and M–Co–Al (M = Fe and Ce) catalysts were synthesized to explore their catalytic performance for the NH 3 -SCR reaction. The physicochemical properties of these catalysts were further characterized utilizing N 2 -physisorption, XRD, NH 3 -TPD, H 2 -TPR, XPS, SEM, and EDS mapping. The results show that Fe/Ce addition has a significant influence on the catalytic performance and physicochemical properties of catalysts. The Co-Al spinel catalyst yields the lowest catalytic performance, while the Fe–Co–Al catalyst exhibits the best catalytic performance and more than 93% NO x conversion can be obtained in the range of 240–270 °C. Meanwhile, Fe or Ce addition can promote the oxidation of NO to NO 2 and inhibit the NH 3 oxidation reaction. The characterization results indicate that the addition of Fe or Ce remarkably reduces the crystallinity of spinel oxides and facilitates the dispersion of active species. Furthermore, the synergistic interaction between Fe/Ce and Co increases the ratio of O β /(O α + O β ) and Co 3+ /(Co 3+ + Co 2+ ), which can accelerate the catalytic performance of catalysts. Finally, better redox properties and moderate surface acidity of catalysts can be obtained with the addition of Fe or Ce. All of the mentioned above contribute to the promoted catalytic performance of catalysts and such an effect is more pronounced with Fe doping.