Hydroxy-Modified Hierarchical Porous Na-CoOx /CN Material for Low-Concentration High-Throughput Formaldehyde Oxidation at Room Temperature.

Engineering the pore structure and surface properties of the catalyst are the key to realizing the highly efficient conversion of low-concentration and high-throughput formaldehyde at room temperature. Herein, alkali-modified hierarchical porous Na-CoOx /CN material was prepared using a novel freeze-drying-pyrolysis method by employing super absorbent resin/MOF composites as templates, which generate mesopores distributed in a narrow region of 6∼20 nm and abundant hydroxyl groups on the surface by alkali-modification. At room temperature, the Na-CoOx /CN material exhibited full conversion of low concentration (1.0 mg/m3 ) and high throughput (240,000 mL/(gcat  h)) formaldehyde while also demonstrating outstanding catalytic stability under a even higher space velocity (480,000 mL/(gcat  h)). In situ DRIFTS characterization revealed that the hydroxyl groups on the catalyst's surface could be consumed by oxidizing formaldehyde to intermediate species (carbonate, hydrocarbonate), which were then regenerated by Na+ and CO3 2- , contributing to the cycle of the reaction path.