Ozone Catalytic Oxidation of Gaseous Toluene over MnO2-Based Ozone Decomposition Catalysts Immobilized on a Nonwoven Fabric

Abstract

Degradation of toluene gas by ozone catalytic oxidation (OZCO) by using a MnO 2 -based ozone decomposition catalyst (ODC) was investigated to clarify the reactive site of ODC material with O 3 . An optimum structure for the ODC to remove O 3 and toluene were proposed. For honeycomb ODC, toluene degradation by OZCO occurred only around the entrance of the honeycomb ODC, and we expected that a thinner ODC would increase the toluene degradation efficiency. A nonwoven fabric on which ODC was immobilized was developed to decompose O 3 and volatile organic compounds simultaneously. The toluene degradation ratio and the mineralization of toluene to CO 2 were determined to evaluate the performance of the fabric. Furthermore, the effects of relative humidity and O 3 concentration on the decomposition and mineralization ratios were also investigated with or without 254 nm UV irradiation (UV 254 ). The fabric decomposed and mineralized toluene to CO 2 , even at low O 3 concentrations. Although high humidity reduced the degradation ratio of toluene, UV 254 irradiation improved the recovery of the degradation ratio and increased the mineralization ratio.

MnO2‐Based Materials for Environmental Applications

“…Among many catalysts, MnO 2 ‐based materials have been extensively studied in the catalyst degradation of VOCs due to their natural abundance, environmentally friendliness, low cost, and specific chemical/physical properties, including different crystal structures and suitable redox activity. Currently, the reported types of VOCs degraded by MnO 2 ‐based materials include benzene series (such as toluene, [ 166,217,226,430–438 ] benzene, [ 171,173,439–441 ] ethylbenzene, [ 442–444 ] and o ‐xylene [ 297,445–448 ] ), formaldehyde, [ 54,86,116,123,137,155,156,296,449–455 ] propane, [ 456 ] aerobic sulfide, [ 172 ] methyl mercaptan, [ 299,457 ] acetone, [ 458,459 ] etc. Among them, formaldehyde and benzene series are the most common VOC pollutants in the air that have been studied the most ( Table 3 ).…”

Removal of VOCs by Ozone: n-Alkane Oxidation under Mild Conditions

“…Since the enhancement of the oxidation efficiency in the presence of O3 is attributable to a formation of highly reactive O atoms [29,32,33], catalytic O3 decomposition (over Mn/Al2O3 or Al2O3) as well as gas-phase decomposition (in the empty reactor) was also studied in detail. The results obtained are shown in Figure 5.…”

“…The high efficiency of supported MnO x catalysts in the OZCO of VOCs can be attributed to their ability in terms of O 3 decomposition [30]. It has been reported that highly reactive oxygen species such as atomic oxygen, peroxide, and OH radicals are formed (Equations ( 1)-( 4)) on the surface of metal oxides as a result of O 3 decomposition [30][31][32][33]. These species can completely oxidize adsorbed VOCs to CO 2 , even at room temperature (RT).…”

Non-thermal Plasma Assisted Preparation of MnCeOx, MnOx and CeO2 Catalysts for Enhancement of Surface Active Oxygen and NO Oxidation Activity

“…Although the active oxygen species in plasma are shortliving and unstable, they can be adsorbed by the catalyst and interact with the ion on the catalysts surface. For example, when O 3 reaches the catalysts surface, O atoms, O 2 and OH radicals are formed on the surface (Sekiguchi et al, 2017). Therefore, the ratio of O and O α /(O α + O β ) on catalysts surface prepared by plasma is relatively high.…”