Highly active manganese oxide catalysts for low-temperature oxidation of formaldehyde

Abstract

a b s t r a c tBirnessite -type manganese oxides with very high surface areas (up to 154 m 2 /g) were successfully prepared using a microemulsion process. The morphology, surface area, pore size, and the surface reducibility of these materials were readily tailored via the synthesis temperature. The physiochemical properties of the manganese oxides were characterized by means of XRD, TEM, SEM, BET and H 2 -TPR techniques. These materials were also catalytically tested in HCHO oxidation, showing significantly high catalytic activity. It was found that the differences in catalytic performance of these materials were jointly attributed to the effects of the morphology, surface area and surface reducibility. The highly porous feature of the catalyst with nanospheres could allow HCHO molecules to easily diffuse onto catalytically active sites, which endows the nanospheres with high catalytic activity. The higher the surface area, the higher its catalytic activity. A higher surface reducibility offered a lower temperature of HCHO oxidation. The most active manganese catalyst (BSW-120) showed a 100% HCHO conversion at 100°C.

MnOx‐loaded Mesoporous Silica for the Catalytic Oxidation of Formaldehyde. Effect of the Melt Infiltration Conditions on the Activity – Stability Behavior

“…Therefore, despite the remarkable Mn 3 O 4 dispersion and spatial distribution of NPs, 20Mn‐MIa‐300 catalyst showed a limited catalytic activity due to the low Mn AOS. This result suggests that the Mn 3+ /Mn 2+ redox couple is far less efficient than the Mn 4+ /Mn 3+ couple in the total formaldehyde oxidation, in agreement with literature on bulk MnO 2 and Mn 3 O 4 catalysts for HCHO oxidation . When compared with the catalysts proposed in the literature, even if the comparison is difficult considering the differences in terms of setup configuration and reaction conditions, these catalysts presents comparable T 50 (<150 °C) than reported for pure – undoped – manganese oxide …”

Progress of Catalytic Oxidation of Formaldehyde over Manganese Oxides

“…However, the high cost and limited resources hinder the application of supported noble metal catalysts . Therefore, the development of low‐cost catalytic materials for room‐temperature oxidation of HCHO has become a research hotspot in recent years . In 2002, Sekine et al .…”

A novel formaldehyde sensor based on the pseudocapacitive catalysis of birnessite

“…Birnessite (δ-type; A x MnO 2 where A = H + or metal cation) is a naturally-occurring manganese oxide which consists of a two-dimensional layered structure of edge-shared MnO 6 . Among various polymorphs of MnO 2 , birnessite can be regarded as the most effective catalyst for gas-phase oxidative decomposition of FA at relatively low temperatures [16][17][18][19]. Accordingly, an electroactive thin film of birnessite adhered well to a conducting substrate would be a good sensor material for FA detection.…”