Harnessing Adsorption–Catalysis Synergy: Efficient Oxidative Removal of Gaseous Formaldehyde by a Manganese Dioxide/Metal–Organic Framework Nanocomposite at Room Temperature
Kumar Vikrant, Ki‐Hyun Kim, Chaozheng He, Dimitrios A. Giannakoudakis
Abstract
Abstract The potential utility of a transition metal oxide/metal–organic framework (MOF) nanocomposite has been explored using manganese dioxide (MnO 2 )/Universitetet i Oslo (UiO)‐66‐amine (NH 2 (prototypical zirconium (Zr) MOF)) to develop an efficient adsorption–catalysis system for the removal of formaldehyde (FA) from the air. The room‐temperature FA (100 ppm) conversion ( X FA (%)), when tested using five different MnO 2 (wt%) loadings in the nanocomposite, is estimated as: 1% MnO 2 (88%) > 2% MnO 2 (86%) > 4% MnO 2 (84%) > 6% MnO 2 (75%) > 20% MnO 2 (47%). The FA removal performance is lowered as the active catalytic sites are covered with the increases in the MnO 2 loading (e.g., >1 wt%). The FA and molecular oxygen species preferably adsorb (and activate) onto the Zr atoms attached to the NH 2 groups. The oxidation of FA into carbon dioxide proceeds subsequently through the formation of intermediates (e.g., dioxymethylene and formate). The MnO 2 nanoclusters act as secondary reactive adsorption sites to boost the capture, activation, and oxidation of the FA molecules at the Zr active centers. Accordingly, the MnO 2 /UiO‐66‐NH 2 nanocomposite is demonstrated to effectively harness the adsorption–catalysis synergy for highly efficient removal of FA relative to other well‐known catalysts (e.g., platinum and metal oxide‐based nanomaterials).