Unraveling the Role of Sodium in Removing Oxygen from Propylene over Fe-Based Catalysts

Development of effective non-noble metals catalysts in removing oxygen from propylene remains a substantial challenge. Herein, the designed catalyst of 0.5%Na–Fe/Al 2 O 3 exhibited up to 100% O 2 conversion and inhibited the greenhouse gas CO 2 formation under hydrogen existence. Multiple characterization results confirmed that Na promoter enhances the dispersion of Fe species and the formation of oxygen vacancies, contributing to enriching the reactivity of the O 2 . Significantly, the TPD results further demonstrated that the Na promoter facilitates the desorption of C 3 H 6 , decreasing the reaction probability of O 2 and C 3 H 6 , which plays an important role in suppressing the formation of CO 2 . This finding not only provides a novel approach to understand the role of Na promoter, but also opens an avenue for providing scientific guidance to design and synthesis of high-efficiency catalysts. Graphical Abstract The effective Na-promoted iron-based catalysts achieved 100% O 2 conversion with almost no formation of by-product CO 2 . Several characterization results confirmed that the presence of Na promoter affected the electronic state of Fe atoms, promoted the formation of oxygen vacancies and improved the O 2 reactivity. Significantly, the Na promoter plays an important role in the adsorption of H 2 and desorption of C 3 H 6 , facilitating to improve the O 2 reactivity and inhibit the formation of the by-product CO 2 .