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Potassium associated manganese vacancy in birnessite-type manganese dioxide for airborne formaldehyde oxidation


As a strategy for regulating electronic structure of metal oxides, defect engineering has been widely studied, and the concentrations and spatial distributions of metal vacancy in the metal oxides always resulting in unprecedented properties. Meanwhile, alkali metals exhibit a universal promotion effect on catalytic oxidation of formaldehyde (HCHO). Herein, a kind of birnessite-type manganese dioxide (MnO2) with rich Mn vacancy was hydrothermally synthesized for catalytic oxidation of HCHO. The significant effect of the K+ content on the structures, morphologies and catalytic activity of the birnessite-type MnO2 for HCHO oxidation was systematically studied for the first time. Initially the increasing content of K+ obviously improves the catalytic performance for HCHO oxidation due to the considerable enhancement of the lattice oxygen activity. However, due to the interaction from the excess K atoms, the oxygen atoms nearest to K atoms are supposed to be more stable and its mobility decreases, which is confirmed by the experimental characterization and DFT (Density Functional Theory) theoretical calculation. Moreover, the excess K+ will increase the amount of surface basic sites, making CO2 difficult to desorb. Thus, there is an optimal K+ content to promote the activity of birnessite-type MnO2. With the moderate content of K+ in the birnessite-type MnO2, the excellent catalytic activity for HCHO oxidation has been achieved (T50%= 56 °C; T90%= 82 °C) under 100 ppm of HCHO, ~90 L/gcat•h of gas hourly space velocity (GHSV). The present work provides an in-depth insight into the structure-activity relationship between birnessite-type MnO2 and its catalytic activity.

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Publication details

The article was received on 16 Oct 2017, accepted on 10 Jan 2018 and first published on 11 Jan 2018

Article type: Paper
DOI: 10.1039/C7CY02121F
Citation: Catal. Sci. Technol., 2018, Accepted Manuscript
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    Potassium associated manganese vacancy in birnessite-type manganese dioxide for airborne formaldehyde oxidation

    S. Rong, K. Li, P. Zhang, F. Liu and J. Zhang, Catal. Sci. Technol., 2018, Accepted Manuscript , DOI: 10.1039/C7CY02121F

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