Tungsten doped manganese dioxide for efficient removal of gaseous formaldehyde at ambient temperatures

Abstract

Room-temperature active catalysts are very important to combat against ubiquitous indoor HCHO pollution. Here, tungsten doped MnO2 (W-MnO2) was first synthesized and investigated for HCHO decomposition at ambient temperature. With addition of WCl6 as precursor into the mixture of permanganate and manganese chloride, tungsten-doped δ-MnO2 with weak crystallinity and large specific surface area (>230m2/g) was synthesized. Substitution of W6+ for Mn in MnO6 groups reduced the chemical valence of Mn and made adsorbed surface oxygen species more active. As a result, the W-MnO2 catalyst with the nominal W/Mn ratio achieved efficient and stable activity for real-level indoor HCHO (0.3mg/m3) under the GHSV as high as 600L/gcat·h, the removal efficiency reaching 90% at 30°C and 60% at 5°C, respectively.